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  • 701.
    Tengstrand, Erik
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Data analysis of non-targeted mass spectrometry experiments2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Data processing tools are valuable to the analytical chemist as they can speed up the analysis, and sometimes solve problems that are not feasible to solve in a traditional manner. However, the complexity of many data processing tools can make their use daunting for the inexperienced user.

    This thesis includes two applications and two tools for data processing. The first application focuses on minimizing the manual input, reducing the time required for a simple task. The second application required more manual input, in the form of parameter selection, but process far more data.  The data processing tools both include features that simplify the manual work required. The first by including visual diagnostics tools that helps in setting the parameters. The second via internal validation that makes the tool’s process more robust and reliable, and thereby less sensitive to small changes in the parameters.

    No matter how good or precise a data processing tool is, if it is so cumbersome that it is not used by the analytical chemists that need it, it is useless. Therefore, the main focus of this thesis is to make data processing easier.

  • 702.
    Tengstrand, Erik
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Åberg, K. Magnus
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Exploiting the sample dimension to resolve ambiguities in chromatographic peak alignmentIn: Journal of Chemometrics, ISSN 0886-9383, E-ISSN 1099-128XArticle in journal (Refereed)
  • 703.
    Tesche, Matthias
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Achtert, Peggy
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Glantz, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Noone, Kevin J.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Aviation effects on already-existing cirrus clouds2016In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, article id 12016Article in journal (Refereed)
    Abstract [en]

    Determining the effects of the formation of contrails within natural cirrus clouds has proven to be challenging. Quantifying any such effects is necessary if we are to properly account for the influence of aviation on climate. Here we quantify the effect of aircraft on the optical thickness of already-existing cirrus clouds by matching actual aircraft flight tracks to satellite lidar measurements. We show that there is a systematic, statistically significant increase in normalized cirrus cloud optical thickness inside mid-latitude flight tracks compared with adjacent areas immediately outside the tracks.

  • 704. Tesche, Matthias
    et al.
    Glantz, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Johansson, Christer
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Environment and Health Administration, Stockholm, Sweden.
    Spaceborne observations of low surface aerosol concentrations in the Stockholm region2016In: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 68, article id 28951Article in journal (Refereed)
    Abstract [en]

    This article investigates the feasibility of using spaceborne observations of aerosol optical thickness (AOT) derived with the Moderate Resolution Imaging Spectroradiometer (MODIS) for monitoring of fine particulate matter (PM2.5) in an environment of low aerosol loading. Previous studies of the AOT-to-PM2.5 relationship benefit from the large range of observed values. The Stockholm region features a comprehensive network of ground-based monitoring stations that generally show PM2.5 values <20 mu g m(-3). MODIS AOT at 555nm is usually <0.20 and in good agreement with ground-based sun photometer observations in this region. We use MODIS Collection 5 AOT data with a horizontal resolution of 10km x 10km and ground-based in-situ PM2.5 observations to derive an AOT-to-PM2.5 relationship that can be used to estimate fields of PM2.5. This has been carried out with respect to the months from April to September of the period 2000-2013. Relative average absolute deviations of 33-55 % (mean of 45 %) are obtained between MODIS-retrieved and ground-based PM2.5. The root mean square error is 0.2159 mu gm(-3) between retrieved and measured PM2.5. From spaceborne lidar observations, it is found that elevated aerosol layers are generally sparse in the Stockholm region. This favours remote sensing of PM2.5 from space. The deviations found between measured and retrieved PM2.5 are mainly attributed to infrequent situations of inhomogeneous aerosol layering for which column-integrated observations cannot be connected to surface conditions. Using MODIS Collection 6 data with a resolution of 3km x 3 km in a case study actually gives far fewer results than the coarser Collection 5 product. This is explained by the complex geography of the Stockholm region with a coastline and an abundance of lakes, which seems to induce biases in the retrieval of AOT at higher spatial resolution.

  • 705.
    Tesi, Tommaso
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. National Research Council (ISMAR-CNR), Italy.
    Geibel, Marc C.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Pearce, Christof
    Stockholm University, Faculty of Science, Department of Geological Sciences. Aarhus University, Denmark.
    Panova, Elena
    Vonk, Jorien E.
    Karlsson, Emma
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Salvado, Joan A.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Krusa, Martin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Bröder, Lisa
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Humborg, Christoph
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Semiletov, Igor
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Carbon geochemistry of plankton-dominated samples in the Laptev and East Siberian shelves: contrasts in suspended particle composition2017In: Ocean Science, ISSN 1812-0784, E-ISSN 1812-0792, Vol. 13, no 5, p. 735-748Article in journal (Refereed)
    Abstract [en]

    Recent Arctic studies suggest that sea ice decline and permafrost thawing will affect phytoplankton dynamics and stimulate heterotrophic communities. However, in what way the plankton composition will change as the warming proceeds remains elusive. Here we investigate the chemical signature of the plankton-dominated fraction of particulate organic matter (POM) collected along the Siberian Shelf. POM (>10 mu m) samples were analysed using molecular biomarkers (CuO oxidation and IP25 ) and dual-carbon isotopes (delta C-13 and Delta C-14). In addition, surface water chemical properties were integrated with the POM (>10 mu m) dataset to understand the link between plankton composition and environmental conditions. delta C-13 and Delta C-14 exhibited a large variability in the POM (> 10 mu m) distribution while the content of terrestrial biomarkers in the POM was negligible. In the Laptev Sea (LS), delta C-13 and Delta C-14 of POM (> 10 mu m) suggested a heterotrophic environment in which dissolved organic carbon (DOC) from the Lena River was the primary source of metabolisable carbon. Within the Lena plume, terrestrial DOC probably became part of the food web via bacteria uptake and subsequently transferred to relatively other heterotrophic communities (e.g. dinoflagellates). Moving eastwards toward the sea-ice-dominated East Siberian Sea (ESS), the system became progressively more autotrophic. Comparison between delta C-13 of POM (> 10 mu m) samples and CO(2)aq concentrations revealed that the carbon isotope fractionation increased moving towards the easternmost and most productive stations. In a warming scenario characterised by enhanced terrestrial DOC release (thawing permafrost) and progressive sea ice decline, heterotrophic conditions might persist in the LS while the nutrient-rich Pacific inflow will likely stimulate greater primary productivity in the ESS. The contrasting trophic conditions will result in a sharp gradient in delta C-13 between the LS and ESS, similar to what is documented in our semi-synoptic study.

  • 706.
    Tesi, Tommaso
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Institute of Marine Sciences, National Research Council (ISMAR-CNR), Italy.
    Muschitiello, Francesco
    Stockholm University, Faculty of Science, Department of Geological Sciences. Columbia University, USA; Uni Research Climate, Norway.
    Smittenberg, Rienk H.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Jakobsson, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences. University Centre in Svalbard (UNIS), Svalbard.
    Vonk, J. E.
    Hill, P.
    Andersson, August
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Kirchner, Nina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Noormets, R.
    Dudarev, O.
    Semiletov, I.
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Massive remobilization of permafrost carbon during post-glacial warming2016In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 7, article id 13653Article in journal (Refereed)
    Abstract [en]

    Recent hypotheses, based on atmospheric records and models, suggest that permafrost carbon (PF-C) accumulated during the last glaciation may have been an important source for the atmospheric CO2 rise during post-glacial warming. However, direct physical indications for such PF-C release have so far been absent. Here we use the Laptev Sea (Arctic Ocean) as an archive to investigate PF-C destabilization during the last glacial–interglacial period. Our results show evidence for massive supply of PF-C from Siberian soils as a result of severe active layer deepening in response to the warming. Thawing of PF-C must also have brought about an enhanced organic matter respiration and, thus, these findings suggest that PF-C may indeed have been an important source of CO2 across the extensive permafrost domain. The results challenge current paradigms on the post-glacial CO2 rise and, at the same time, serve as a harbinger for possible consequences of the present-day warming of PF-C soils.

  • 707.
    Tesi, Tommaso
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Institute of Marine Sciences, National Research Council (ISMAR-CNR), Italy.
    Semiletov, Igor
    Dudarev, Oleg
    Andersson, August
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Matrix association effects on hydrodynamic sorting and degradation of terrestrial organic matter during cross-shelf transport in the Laptev and East Siberian shelf seas2016In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, no 3, p. 731-752Article in journal (Refereed)
    Abstract [en]

    This study seeks an improved understanding of how matrix association affects the redistribution and degradation of terrigenous organic carbon (TerrOC) during cross-shelf transport in the Siberian margin. Sediments were collected at increasing distance from two river outlets (Lena and Kolyma Rivers) and one coastal region affected by erosion. Samples were fractionated according to density, size, and settling velocity. The chemical composition in each fraction was characterized using elemental analyses and terrigenous biomarkers. In addition, a dual-carbon-isotope mixing model (C-13 and C-14) was used to quantify the relative TerrOC contributions from active layer (Topsoil) and Pleistocene Ice Complex Deposits (ICD). Results indicate that physical properties of particles exert first-order control on the redistribution of different TerrOC pools. Because of its coarse nature, plant debris is hydraulically retained in the coastal region. With increasing distance from the coast, the OC is mainly associated with fine/ultrafine mineral particles. Furthermore, biomarkers indicate that the selective transport of fine-grained sediment results in mobilizing high-molecular weight (HMW) lipid-rich, diagenetically altered TerrOC while lignin-rich, less degraded TerrOC is retained near the coast. The loading (mu g/m(2)) of lignin and HMW wax lipids on the fine/ultrafine fraction drastically decreases with increasing distance from the coast (98% and 90%, respectively), which indicates extensive degradation during cross-shelf transport. Topsoil-C degrades more readily (903.5%) compared to the ICD-C (6011%) during transport. Altogether, our results indicate that TerrOC is highly reactive and its accelerated remobilization from thawing permafrost followed by cross-shelf transport will likely represent a positive feedback to climate warming.

  • 708. Thao, Thi
    et al.
    Gentsch, Norman
    Mikutta, Robert
    Sauheitl, Leopold
    Shibistova, Olga
    Wild, Birgit
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Schnecker, Jörg
    Bárta, Jiri
    Čapek, Petr
    Gittel, Antje
    Lashchinskiy, Nikolay
    Urich, Tim
    Šantrůčková, Hana
    Richter, Andreas
    Guggenberger, Georg
    Fate of carbohydrates and lignin in north-east Siberian permafrost soils2018In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 116, p. 311-322Article in journal (Refereed)
    Abstract [en]

    Permafrost soils preserve huge amounts of organic carbon (OC) prone to decomposition under changing climatic conditions. However, knowledge on the composition of soil organic matter (OM) and its transformation and vulnerability to decomposition in these soils is scarce. We determined neutral sugars and lignin-derived phenols, released by trifluoroacetic acid (TFA) and CuO oxidation, respectively, within plants and soil density fractions from the active layer and the upper permafrost layer at three different tundra types (shrubby grass, shrubby tussock, shrubby lichen) in the Northeast Siberian Arctic. The heavy fraction (HF; > 1.6 g mL(-1)) was characterized by a larger enrichment of microbial sugars (hexoses vs. pentoses) and more pronotmced lignin degradation (acids vs. aldehydes) as compared to the light fraction (LF; < 1.6 g mL(-1)), showing the transformation from plant residue-dominated particulate OM to a largely microbial imprint in mineral-associated OM. In contrast to temperate and tropical soils, total neutral sugar contents and galactose plus mannose to arabinose plus xylose ratios (GM/AX) decreased in the HE with soil depth, which may indicate a process of effective recycling of microbial biomass rather than utilizing old plant materials. At the same dine, lignin-derived phenols increased and the degree of oxidative decomposition of lignin decreased with soil depth, suggesting a selective preservation of lignin presumably due to anaerobiosis. As large parts of the plant-derived pentoses are incorporated in lignocelluloses and thereby protected against rapid decomposition, this might also explain the relative enrichment of pentoses with soil depth. Hence, our results show a relatively large contribution of plant derived OM, particularly in the buried topsoil and subsoil, which is stabilized by the current soil environmental conditions but may become available to decomposers if permafrost degradation promotes soil drainage and improves the soil oxygen supply.

  • 709. Thomas, Manu Anna
    et al.
    Brännström, Niklas
    Persson, Christer
    Grahn, Håkan
    von Schoenberg, Pontus
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. The Swedish Defence Research Agency, FOI, Sweden.
    Robertson, Lennart
    Surface air quality implications of volcanic injection heights2017In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 166, p. 510-518Article in journal (Refereed)
    Abstract [en]

    Air quality implications of volcanic eruptions have gained increased attention recently in association with the 2010 Icelandic eruption that resulted in the shut-down of European air space. The emission amount, injection height and prevailing weather conditions determine the extent of the impact through the spatio-temporal distribution of pollutants. It is often argued that in the case of a major eruption in Iceland, like Laki in 1783-1784, that pollutants injected high into the atmosphere lead to substantially increased concentrations of sulfur compounds over continental Europe via long-range transport in the jet stream and eventual large-scale subsidence in a high-pressure system. Using state-of-the-art simulations, we show that the air quality impact of Icelandic volcanoes is highly sensitive to the injection height. In particular, it is the infinitesimal injections into the lower half of the troposphere, rather than the substantial injections into the upper troposphere/lower stratosphere that contribute most to increased pollutant concentrations, resulting in atmospheric haze over mainland Europe/Scandinavia. Besides, the persistent high pressure system over continental Europe/Scandinavia traps the pollutants from dispersing, thereby prolonging the haze.

  • 710. Thor, Peter
    et al.
    Bailey, Allison
    Halsband, Claudia
    Guscelli, Ella
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Fransson, Agneta
    Seawater pH Predicted for the Year 2100 Affects the Metabolic Response to Feeding in Copepodites of the Arctic Copepod Calanus glacialis2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 12, article id e0168735Article in journal (Refereed)
    Abstract [en]

    Widespread ocean acidification (OA) is transforming the chemistry of the global ocean, and the Arctic is recognised as a region where the earliest and strongest impacts of OA are expected. In the present study, metabolic effects of OA and its interaction with food availability was investigated in Calanus glacialis from the Kongsfjord, West Spitsbergen. We measured metabolic rates and RNA/DNA ratios (an indicator of biosynthesis) concurrently in fed and unfed individuals of copepodite stages CII-CIII and CV subjected to two different pH levels representative of present day and the business as usual IPCC scenario (RCP8.5) prediction for the year 2100. The copepods responded more strongly to changes in food level than to decreasing pH, both with respect to metabolic rate and RNA/DNA ratio. However, significant interactions between effects of pH and food level showed that effects of pH and food level act in synergy in copepodites of C. glacialis. While metabolic rates in copepodites stage CII-CIII increased by 78% as a response to food under present day conditions (high pH), the increase was 195% in CII-CIlls kept at low pH-a 2.5 times greater increase. This interaction was absent for RNA/DNA, so the increase in metabolic rates were clearly not a reaction to changing biosynthesis at low pH per se but rather a reaction to increased metabolic costs per unit of biosynthesis. Interestingly, we did not observe this difference in costs of growth in stage CV. A 2.5 times increase in metabolic costs of growth will leave the copepodites with much less energy for growth. This may infer significant changes to the C. glacialis population during future OA.

  • 711.
    Thornton, Brett F.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Geibel, Marc C.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Crill, Patrick M.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Humborg, Christoph
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Mörth, Carl-Magnus
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Methane fluxes from the sea to the atmosphere across the Siberian shelf seas2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 11, p. 5869-5877Article in journal (Refereed)
    Abstract [en]

    The Laptev and East Siberian Seas have been proposed as a substantial source of methane (CH4) to the atmosphere. During summer 2014, we made unique high-resolution simultaneous measurements of CH4 in the atmosphere above, and surface waters of, the Laptev and East Siberian Seas. Turbulence-driven sea-air fluxes along the ship's track were derived from these observations; an average diffusive flux of 2.99mgm(-2) d(-1) was calculated for the Laptev Sea and for the ice-free portions of the western East Siberian Sea, 3.80mgm(-2)d(-1). Although seafloor bubble plumes were observed at two locations in the study area, our calculations suggest that regionally, turbulence-driven diffusive flux alone accounts for the observed atmospheric CH4 enhancements, with only a local, limited role for bubble fluxes, in contrast to earlier reports. CH4 in subice seawater in certain areas suggests that a short-lived flux also occurs annually at ice-out.

  • 712.
    Thornton, Brett F.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Horst, Axel
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Carrizo, Daniel
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Holmstrand, Henry
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Methyl chloride and methyl bromide emissions from baking: an unrecognized anthropogenic source2016In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 551, p. 327-333Article in journal (Refereed)
    Abstract [en]

    Methyl chloride and methyl bromide (CH3Cl and CH3Br) are the largest natural sources of chlorine and bromine, respectively, to the stratosphere, where they contribute to ozone depletion. We report the anthropogenic production of CH3Cl and CH3Br during breadbaking, and suggest this production is an abiotic process involving the methyl ester functional groups in pectin and lignin structural polymers of plant cells. Wide variations in baking styles allow only rough estimates of this flux of methyl halides on a global basis. A simple model suggests that CH3Br emissions from breadbaking likely peaked circa 1990 at approximately 200 tonnes per year (about 0.3% of industrial production), prior to restrictions on the dough conditioner potassium bromate. In contrast, CH3Cl emissions from breadbaking may be of similar magnitude as acknowledged present-day CH3Cl industrial emissions. Because the mechanisms involve functional groups and compounds widely found in plant materials, this type of methyl halide production may occur in other cooking techniques as well.

  • 713.
    Thurner, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Max Planck Institute for Biogeochemistry, Germany.
    Beer, Christian
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Carvalhais, Nuno
    Forkel, Matthias
    Santoro, Maurizio
    Tum, Markus
    Schmullius, Christiane
    Large-scale variation in boreal and temperate forest carbon turnover rate related to climate2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 9, p. 4576-4585Article in journal (Refereed)
    Abstract [en]

    Vegetation carbon turnover processes in forest ecosystems and their dominant drivers are far from being understood at a broader scale. Many of these turnover processes act on long timescales and include a lateral dimension and thus can hardly be investigated by plot-level studies alone. Making use of remote sensing-based products of net primary production (NPP) and biomass, here we show that spatial gradients of carbon turnover rate (k) in Northern Hemisphere boreal and temperate forests are explained by different climate-related processes depending on the ecosystem. k is related to frost damage effects and the trade-off between growth and frost adaptation in boreal forests, while drought stress and climate effects on insects and pathogens can explain an elevated k in temperate forests. By identifying relevant processes underlying broadscale patterns in k, we provide the basis for a detailed exploration of these mechanisms in field studies, and ultimately the improvement of their representations in global vegetation models (GVMs).

  • 714.
    Thurner, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Beer, Christian
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ciais, Philippe
    Friend, Andrew D.
    Ito, Akihiko
    Kleidon, Axel
    Lomas, Mark R.
    Shaun, Quegan
    Rademacher, Tim T.
    Schaphoff, Sibyll
    Tum, Markus
    Wiltshire, Andy
    Carvalhais, Nuno
    Evaluation of climate-related carbon turnover processes in global vegetation models for boreal and temperate forests2017In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 23, no 8, p. 3076-3091Article in journal (Refereed)
    Abstract [en]

    Turnover concepts in state-of-the-art global vegetation models (GVMs) account for various processes, but are often highly simplified and may not include an adequate representation of the dominant processes that shape vegetation carbon turnover rates in real forest ecosystems at a large spatial scale. Here, we evaluate vegetation carbon turnover processes in GVMs participating in the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP, including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT) using estimates of vegetation carbon turnover rate (k) derived from a combination of remote sensing based products of biomass and net primary production (NPP). We find that current model limitations lead to considerable biases in the simulated biomass and in k (severe underestimations by all models except JeDi and VISIT compared to observation-based average k), likely contributing to underestimation of positive feedbacks of the northern forest carbon balance to climate change caused by changes in forest mortality. A need for improved turnover concepts related to frost damage, drought, and insect outbreaks to better reproduce observation-based spatial patterns in k is identified. As direct frost damage effects on mortality are usually not accounted for in these GVMs, simulated relationships between k and winter length in boreal forests are not consistent between different regions and strongly biased compared to the observation-based relationships. Some models show a response of k to drought in temperate forests as a result of impacts of water availability on NPP, growth efficiency or carbon balance dependent mortality as well as soil or litter moisture effects on leaf turnover or fire. However, further direct drought effects such as carbon starvation (only in HYBRID4) or hydraulic failure are usually not taken into account by the investigated GVMs. While they are considered dominant large-scale mortality agents, mortality mechanisms related to insects and pathogens are not explicitly treated in these models.

  • 715.
    Thurner, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Beer, Christian
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Crowther, Thomas
    Falster, Daniel
    Manzoni, Stefano
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Prokushkin, Anatoly
    Schulze, Ernst-Detlef
    Sapwood biomass carbon in northern boreal and temperate forests2019In: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 28, no 5, p. 640-660Article in journal (Refereed)
    Abstract [en]

    Aim Information on the amount of carbon stored in the living tissue of tree stems (sapwood) is crucial for carbon and water cycle applications. Here, we aim to investigate sapwood-to-stem proportions and differences therein between tree genera and derive a sapwood biomass map. Location Northern Hemisphere boreal and temperate forests. Time period 2010. Major taxa studied Twenty-five common tree genera. Methods First, we develop a theoretical framework to estimate sapwood biomass for a given stem biomass by applying relationships between sapwood cross-sectional area (CSA) and stem CSA and between stem CSA and stem biomass. These measurements are extracted from a biomass and allometry database (BAAD), an extensive literature review and our own studies. The established allometric relationships are applied to a remote sensing-based stem biomass product in order to derive a spatially continuous sapwood biomass map. The application of new products on the distribution of stand density and tree genera facilitates the synergy of satellite and forest inventory data. Results Sapwood-to-stem CSA relationships can be modelled with moderate to very high modelling efficiency for different genera. The total estimated sapwood biomass equals 12.87 +/- 6.56 petagrams of carbon (PgC) in boreal (mean carbon density: 1.13 +/- 0.58 kgC m(-2)) and 15.80 +/- 9.10 PgC in temperate (2.03 +/- 1.17 kgC m(-2)) forests. Spatial patterns of sapwood-to-stem biomass proportions are crucially driven by the distribution of genera (spanning from 20-30% in Larix to > 70% in Pinus and Betula forests). Main conclusions The presented sapwood biomass map will be the basis for large-scale estimates of plant respiration and transpiration. The enormous spatial differences in sapwood biomass proportions reveal the need to consider the functionally more important sapwood instead of the entire stem biomass in global carbon and water cycle studies. Alterations in tree species distribution, induced by forest management or climate change, can strongly affect the available sapwood biomass even if stem biomass remains unchanged.

  • 716. Tian, Lin
    et al.
    Inthavong, Kiao
    Lidén, Göran
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Shang, Yidan
    Tu, Jiyuan
    Transport and Deposition of Welding Fume Agglomerates in a Realistic Human Nasal Airway2016In: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 60, no 6, p. 731-747Article in journal (Refereed)
    Abstract [en]

    Welding fume is a complex mixture containing ultra-fine particles in the nanometer range. Rather than being in the form of a singular sphere, due to the high particle concentration, welding fume particles agglomerate into long straight chains, branches, or other forms of compact shapes. Understanding the transport and deposition of these nano-agglomerates in human respiratory systems is of great interest as welding fumes are a known health hazard. The neurotoxin manganese (Mn) is a common element in welding fumes. Particulate Mn, either as soluble salts or oxides, that has deposited on the olfactory mucosa in human nasal airway is transported along the olfactory nerve to the olfactory bulb within the brain. If this Mn is further transported to the basal ganglia of the brain, it could accumulate at the part of the brain that is the focal point of its neurotoxicity. Accounting for various dynamic shape factors due to particle agglomeration, the current computational study is focused on the exposure route, the deposition pattern, and the deposition efficiency of the inhaled welding fume particles in a realistic human nasal cavity. Particular attention is given to the deposition pattern and deposition efficiency of inhaled welding fume agglomerates in the nasal olfactory region. For particles in the nanoscale, molecular diffusion is the dominant transport mechanism. Therefore, Brownian diffusion, hydrodynamic drag, Saffman lift force, and gravitational force are included in the model study. The deposition efficiencies for single spherical particles, two kinds of agglomerates of primary particles, two-dimensional planar and straight chains, are investigated for a range of primary particle sizes and a range of number of primary particles per agglomerate. A small fraction of the inhaled welding fume agglomerates is deposited on the olfactory mucosa, approximately in the range 0.1-1%, and depends on particle size and morphology. The strong size dependence of the deposition in olfactory mucosa on particle size implies that the occupation deposition of welding fume manganese can be expected to vary with welding method.

  • 717. Titos, G.
    et al.
    Cazorla, A.
    Zieger, Paul
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Andrews, E.
    Lyamani, H.
    Granados-Munoz, M. J.
    Olmo, F. J.
    Alados-Arboledas, L.
    Effect of hygroscopic growth on the aerosol light-scattering coefficient: A review of measurements, techniques and error sources2016In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 141, p. 494-507Article, review/survey (Refereed)
    Abstract [en]

    Knowledge of the scattering enhancement factor,.f(RH), is important for an accurate description of direct aerosol radiative forcing. This factor is defined as the ratio between the scattering coefficient at enhanced relative humidity, RH, to a reference (dry) scattering coefficient. Here, we review the different experimental designs used to measure the scattering coefficient at dry and humidified conditions as well as the procedures followed to analyze the measurements. Several empirical parameterizations for the relationship between f(RH) and RH have been proposed in the literature. These parameterizations have been reviewed and tested using experimental data representative of different hygroscopic growth behavior and a new parameterization is presented. The potential sources of error in f(RH) are discussed. A Monte Carlo method is used to investigate the overall measurement uncertainty, which is found to be around 20-40% for moderately hygroscopic aerosols. The main factors contributing to this uncertainty are the uncertainty in RH measurement, the dry reference state and the nephelometer uncertainty. A literature survey of nephelometry-based f(RH) measurements is presented as a function of aerosol type. In general, the highest f(RH) values were measured in clean marine environments, with pollution having a major influence on f(RH). Dust aerosol tended to have the lowest reported hygroscopicity of any of the aerosol types studied. Major open questions and suggestions for future research priorities are outlined.

  • 718.
    Tiwari, Suresh
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Indian Institute of Tropical Meteorological, India.
    Dumka, U. C.
    Gautam, A. S.
    Kaskaoutis, D. G.
    Srivastava, A. K.
    Bisht, D. S.
    Chakrabarty, R. K.
    Sumlin, B. J.
    Solmon, F.
    Assessment of PM2.5 and PM10 over Guwahati in Brahmaputra River Valley: Temporal evolution, source apportionment and meteorological dependence2017In: Atmospheric Pollution Research, ISSN 1309-1042, E-ISSN 1309-1042, Vol. 8, no 1, p. 13-28Article in journal (Refereed)
    Abstract [en]

    Temporal evolution, source apportionment and transport pathways of particulate matter (PM2.5 and PM10) are analysed over Guwahati, located in the Brahmaputra River Valley (BRV), as a function of meteorological dynamics. During the study period (July 2013-June 2014), the mean PM2.5 and PM10 mass concentrations were found to be 52 +/- 37 and 91 +/- 60 mu g m (-3), respectively, both exhibiting higher concentrations during DecembereMarch and very low during summer. The annual mean ratio of PM2.5/ PM10 was 0.57 +/- 0.11, varying from 0.24 to 0.86, suggesting dominance of anthropogenic vs natural emissions during winter and spring, respectively. Diurnal variation reveals higher PM concentrations during morning (similar to 9: 00 local time (LT)) and evening (similar to 23: 00 LT) and lowest around similar to 14: 00 to 17: 00 LT due to influence of dilution processes and higher mixing-layer height over the region. Bivariate plots and Conditional Bivariate Probability Function (CBPF) analysis showed that the highest PM2.5 and PM10 concentrations are mostly associated with weak northwestern winds (< 1.5 ms (- 1)) in all seasons except spring, when the highest PM10 are for southwestern winds above 4-6 ms(- 1), indicating dust transport from SW Asia. Analysis reveals that the local emissions, transported aerosols, along with seasonallychanged air masses, meteorology and boundary-layer dynamics control the concentrations, evolution and fractions of PM over BRV. The turbid air masses transported over Guwahati mostly from western and southwestern directions contribute to higher PM concentrations, either carrying anthropogenic pollution from Indo-Gangetic Plains or locally and LRT dust from BRV and western India, respectively.

  • 719.
    Tiwari, Suresh
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Indian Institute of Tropical Meteorology, India.
    Dumka, U. C.
    Hopke, P. K.
    Tunved, Peter
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Srivastava, A. K.
    Bisht, D. S.
    Chakrabarty, R. K.
    Atmospheric heating due to black carbon aerosol during the summer monsoon period over Ballia: A rural environment over Indo-Gangetic Plain2016In: Atmospheric research, ISSN 0169-8095, E-ISSN 1873-2895, Vol. 178, p. 393-400Article in journal (Refereed)
    Abstract [en]

    Black carbon (BC) aerosols are one of the most uncertain drivers of global climate change. The prevailing view is that BC mass concentrations are low in rural areas where industrialization and vehicular emissions are at a minimum. As part of a national research program called the Ganga Basin Ground Based Experiment-2014 under the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) Phase-III of Ministry of Earth Sciences, Government of India, the continuous measurements of BC and particulate matter (PM) mass concentrations, were conducted in a rural environment in the highly-polluted Indo-Gangetic Plain region during 16th June to 15th August (monsoon period), 2014. The mean mass concentration of BC was 4.03 (+/- 0.85) mu g m(-3) with a daily variability between 2.4 and 5.64 mu g m(-3), however, the mean mass PM concentrations [near ultrafine (PM1.0), fine (PM2.5) and inhalable (PM1.0)] were 29.1(+/- 16.2), 34.7 (+/- 19.9) and 43.7 (+/- 283) mu g m(-3), respectively. The contribution of BC in PM1.0 was approximately 13%, which is one of the highest being recorded. Diurnally, the BC mass concentrations were highest (mean: 5.89 mu g m(-3)) between 20:00 to 22:00 local time (LT) due to the burning of biofuels/biomass such as wood, dung, straw and crop residue mixed with dung by the local residents for cooking purposes. The atmospheric direct radiative forcing values due to the composite and BC aerosols were determined to be +78.3, +44.9, and +45.0 W m(-2) and +42.2, +35.4 and +34.3 W m(-2) during the months ofJune, July and August, respectively. The corresponding atmospheric heating rates (AHR) for composite and BC aerosols were 2.21,1.26 and 1.26; and 1.19, 0.99 and 0.96 K day(-1) for the month ofJune, July and August, respectively, with a mean of 1.57 and 1.05 K day(-1) which was 33% lower AHR (BC) than for the composite particles during the study period. This high AHR underscores the importance of absorbing aerosols such as BC contributed by residential cooking using biofuels in India. Our study demonstrates the need for immediate, effective regulations and policies that mitigate the emission of BC particles from domestic cooking in rural areas of India.

  • 720.
    Tiwari, Suresh
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Indian Institute of Tropical Meteorology, New Delhi Branch, India.
    Kumar, R.
    Tunved, Peter
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Singh, S.
    Panicker, A. S.
    Significant cooling effect on the surface due to soot particles over Brahmaputra River Valley region, India: An impact on regional climate2016In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 562, p. 504-516Article in journal (Refereed)
    Abstract [en]

    Black carbon (BC) is an important atmospheric aerosol constituent that affects the climate by absorbing (directly) the sunlight and modifying cloud characteristics (indirectly). Here, we present first time yearlong measurements of BC and carbon monoxide (CO) from an urban location of Guwahati located in the Brahmaputra River valley (BRV) in the northeast region of India from 1st July 2013 to 30th June 2014. Daily BC concentrations varied within the range of 2.86 to 11.56 mu g m(-3) with an annual average of 7.17 +/- 1.89 mu g m(-3), while, CO varied from 0.19 to 1.20 ppm with a mean value of 0.51 +/- 0.19 ppm during the study period. The concentrations of BC (8.37 mu g m(-3)) and CO (0.67 ppm) were similar to 39% and similar to 55% higher during the dry months (October to March) than the wet months (April to September) suggesting that seasonal changes in meteorology and emission sources play an important role in controlling these species. The seasonal Delta BC/Delta CO ratios were highest (lowest) in the pre-monsoon (winter) 18.1 +/- 1.4 mu g m(-3) ppmv(-1) (12.6 +/- 2.2 mu g m(-3) ppmv(-1)) which indicate the combustion of biofuel/biomass as well as direct emissions from fossil fuel during the pre-monsoon season. The annual BC emission was estimated to be 2.72 Gg in and around Guwahati which is about 44% lower than the mega city 'Delhi' (4.86 Gg). During the study period, the annual mean radiative forcing (RF) at the top of the atmosphere (TOA) for clear skies of BC was +9.5Wm(-2), however, the RF value at the surface (SFC) was -21.1 Wm(-2) which indicates the net warming and cooling effects, respectively. The highest RF at SFC was in the month of April (-30 Wm(-2)) which is coincident with the highest BC mass level. The BC atmospheric radiative forcing (ARF) was +30.16 (annualmean) Wm(-2) varying from +23.1 to +43.8 Wm(-2). The annualmean atmospheric heating rate (AHR) due to the BC aerosols was 0.86 K day(-1) indicates the enhancement in radiation effect over the study region. The Weather Research and Forecasting model coupled with Chemistry(WRF-Chem) captured the seasonal cycle of observed BC fairly well but underestimated the observed BC during the month of May-August. Model results show that BC at Guwahati is controlled mainly by anthropogenic emissions except during the pre-monsoon season when open biomass burning also makes a similar contribution.

  • 721.
    Tiwari, Suresh
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Indian Institute of Tropical Meteorology, India.
    Tunved, Peter
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Hopke, Philip K.
    Srivastava, A. K.
    Bisht, D. S.
    Pandey, A. K.
    Observations of ambient trace gas and PM10 concentrations at Patna, Central Ganga Basin during 2013-2014: The influence of meteorological variables on atmospheric pollutants2016In: Atmospheric research, ISSN 0169-8095, E-ISSN 1873-2895, Vol. 180, p. 138-149Article in journal (Refereed)
    Abstract [en]

    Atmospheric pollutants including ozone (O-3), sulfur dioxide (SO2), oxides of nitrogen (NOx), carbon monoxide (CO), and inhalable particulate matter (PM10) were measured in the central Indo-Gangetic Basin (IGB) at Patna, India, from 1st March 2013 to 31st December 2014, and significant variability was observed in the temporal patterns of these pollutant concentrations. The mean O-3, SO2, NO, NO2, CO (trace gases: TG), and PM10 (PM) concentrations were 14.5 +/- 4.8, 5.9 +/- 4.8, 23.1 +/- 22, 20.6 +/- 14.6 ppb, 1.5 +/- 0.7 ppm, and 192.0 +/- 132.8 ng/m(3), respectively, over the study period. The highest concentrations of these species were during the post-monsoon and winter seasons except O-3 and SO2 that showed the highest concentrations during the pre-monsoon. The lowest concentrations of TG and PM were observed during the monsoon season as a result of scavenging by rain. NO and NO2 along with PM concentrations decreased by similar to 76,19, and 63% when the wind speed (WS) was >0.5 m/s. However, for O-3, an opposite trend was observed with similar to 14% higher concentrations. The WS was negatively correlated with PM during the winter (-0.48) and post-monsoon (-0.32) seasons. In order to investigate the source region of TG and PM, 5-day air mass back trajectories were computed. The dominance of the air masses (92, 53, and 49%) were from the IGB is highly polluted during the winter, pre-monsoon, and post-monsoon, respectively. The TG and PM were observed much higher during these periods. During the biomass burning period (post-monsoon), the trajectory analysis showed that the TG and PM concentrations were around three-fold higher (flow from the IGB) than the other seasons. To improve air quality over IGB, the mitigation measures should be designed to reduce emissions from both local and regional sources.

  • 722. Todea, Ana Maria
    et al.
    Beckmann, Stefanie
    Kaminski, Heinz
    Bard, Delphine
    Bau, Sebastien
    Clavaguera, Simon
    Dahmann, Dirk
    Dozol, Helene
    Dziurowitz, Nico
    Elihn, Karine
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Fierz, Martin
    Lidén, Göran
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Meyer-Plath, Asmus
    Monz, Christian
    Neumann, Volker
    Pelzer, Johannes
    Simonow, Barbara Katrin
    Thali, Patrick
    Tuinman, Ilse
    van der Vleuten, Arjan
    Vroomen, Huub
    Asbach, Christof
    Inter-comparison of personal monitors for nanoparticles exposure at workplaces and in the environment2017In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 605, p. 929-945Article in journal (Refereed)
    Abstract [en]

    Personal monitors based on unipolar diffusion charging (miniDiSC/DiSCmini, NanoTracer, Partector) can be used to assess the individual exposure to nanoparticles in different environments. The charge acquired by the aerosol particles is nearly proportional to the particle diameter and, by coincidence, also nearly proportional to the alveolar lung-deposited surface area (LDSA), the metric reported by all three instruments. In addition, the miniDiSC/DiSCmini and the NanoTracer report particle number concentration and mean particle size. In view of their use for personal exposure studies, the comparability of these personal monitors was assessed in two measurement a large range of particle sizes, morphologies and concentrations. The data provided by the personal monitors were compared with those obtained from reference instruments: a scanning mobility particle sizer (SMPS) for LDSA and mean particle size and a ultrafine particle counter (UCPC) for number concentration. The results indicated that the LDSA concentrations and the mean particle sizes provided by all investigated instruments in this study were in the order of +/- 30% of the reference value obtained from the SMPS when the particle sizes of the test aerosols generated were within 20-400 nm and the instruments were properly calibrated. Particle size, morphology and concentration did not have a major effect within the aforementioned limits. The comparability of the number concentrations was found to be slightly worse and in the range of +/- 50% of the reference value obtained from the UCPC. In addition, a minor effect of the particle morphology on the number concentration measurements was observed. The presence of particles >400 nm can drastically bias the measurement results of all instruments and all metrics determined.

  • 723. Ulvestad, Bente
    et al.
    Randem, Britt Grethe
    Skare, Oivind
    Aalokken, Trond Mogens
    Myranek, Georg Karl
    Elihn, Karine
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Lund, May Brit
    Lung function in asphalt pavers: a longitudinal study2017In: International Archives of Occupational and Environmental Health, ISSN 0340-0131, E-ISSN 1432-1246, Vol. 90, no 1, p. 63-71Article in journal (Refereed)
    Abstract [en]

    To study longitudinal changes in lung function in asphalt pavers and a reference group of road maintenance workers, and to detect possible signs of lung disease by high-resolution computed tomography (HRCT) scans. Seventy-five asphalt pavers and 71 road maintenance workers were followed up with questionnaires and measurements of lung function. Not every worker was tested every year, but most of them had four or more measurement points. The 75 asphalt pavers were also invited to have HRCT scans of the lungs at the end of the follow-up period. Mean annual decline in forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) of the asphalt pavers was 58 and 35 ml, respectively. Adjusted for age at baseline, packyears of smoking and BMI, the asphalt pavers had a significant excess annual decline in FVC and FEV1 compared to the references. The screedmen, the most exposed group of the asphalt pavers, showed a significantly larger decline in FVC than the other asphalt pavers (P = 0.029). Fine intralobular fibrosis without evident cysts was identified with HRCT in three subjects (4 %). We conclude that our findings may indicate an excess annual decline in FVC and FEV1 related to exposure to asphalt fumes. The screedmen, who carry out their work behind and close to the paving machine, had the largest decline in lung function. The finding of adverse pulmonary effects in asphalt pavers calls for better technological solutions to prevent exposure.

  • 724.
    Undeman, Emma
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Brown, Trevor N.
    McLachlan, Michael S.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Wania, Frank
    Who in the world is most exposed to polychlorinated biphenyls? Using models to identify highly exposed populations2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 6, article id 064036Article in journal (Refereed)
    Abstract [en]

    Human subpopulations experience different exposure to persistent organic pollutants (POPs) because of differences in the structure of their food webs and the extent of environmental contamination. Here we quantify the time-variant exposure of different human populations around the world to one representative POP, namely the polychlorinated biphenyl (PCB) congener 153, based on a dynamic simulation of both global environmental fate (using the model BETR-Global) and human food chain bioaccumulation (using the model ACC-HUMAN). The approach identifies subpopulations whose diets include a carnivorous mammal as experiencing the world's highest PCB-153 exposure, i.e. the very large biomagnification potential of their food web more than makes up for the remoteness of their living environment. However, for subpopulations that do not eat warm-blooded carnivores, the proximity to sources of PCBs is more important than food web structure and environmental conditions for differentiating their exposure to PCBs.

  • 725.
    Undeman, Emma
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Gustafsson, Bo G.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Humborg, Christoph
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    McLachlan, Michael S.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Application of a novel modeling tool with multistressor functionality to support management of organic contaminants in the Baltic Sea2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, p. 498-506Article in journal (Refereed)
    Abstract [en]

    Organic contaminants constitute one of many stressors that deteriorate the ecological status of the Baltic Sea. When managing environmental problems in this marine environment, it may be necessary to consider the interactions between various stressors to ensure that averting one problem does not exacerbate another. A novel modeling tool, BALTSEM-POP, is presented here that simulates interactions between climate forcing, hydrodynamic conditions, and water exchange, biogeochemical cycling, and organic contaminant transport and fate in the Baltic Sea. We discuss opportunities to use the model to support different aspects of chemicals management. We exemplify these opportunities with a case study where two emission-reduction strategies for a chemical used in personal care products (decamethylcyclopentasiloxane) are evaluated, and where the confounding influence of future climate change and eutrophication on the impact of the emission-reduction strategies are assessed.

  • 726. Upstill-Goddard, Robert C.
    et al.
    Salter, Matthew E.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Mann, Paul J.
    Barnes, Jonathan
    Poulsen, John
    Dinga, Bienvenu
    Fiske, Gregory J.
    Holmes, Robert M.
    The riverine source of CH4 and N2O from the Republic of Congo, western Congo Basin2017In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 14, no 9, p. 2267-2281Article in journal (Refereed)
    Abstract [en]

    We discuss concentrations of dissolved CH4, N2O, O-2, NO(3)(-)and NH4-, and emission fluxes of CH4 and N2O for river sites in the western Congo Basin, Republic of Congo (ROC). Savannah, swamp forest and tropical forest samples were collected from the Congo main stem and seven of its tributaries during November 2010 (41 samples; wet season) and August 2011 (25 samples; dry season; CH4 and N2O only). Dissolved inorganic nitrogen (DIN: NH4- + NO3-; wet season) was dominated by NO3- (63 +/- 19% of DIN). Total DIN concentrations (1.545.3 mu mol L-1) were consistent with the near absence of agricultural, domestic and industrial sources for all three land types. Dissolved O-2 (wet season) was mostly undersaturated in swamp forest (36 +/- 29 %) and tropical forest (77 +/- 36 %) rivers but predominantly supersaturated in savannah rivers (100 +/- 17 %). The dissolved concentrations of CH4 and N2O were within the range of values reported earlier for sub-Saharan African rivers. Dissolved CH4 was found to be supersaturated (11.2-9553 nmol L-1; 440-354 444 %), whereas N2O ranged from strong undersaturation to supersaturation (3.2-20.6 nmol L-1; 47-205 %). Evidently, rivers of the ROC are persistent local sources of CH4 and can be minor sources or sinks for N2O. During the dry season the mean and range of CH4 and N2O concentrations were quite similar for the three land types. Wet and dry season mean concentrations and ranges were not significant for N2O for any land type or for CH4 in savannah rivers. The latter observation is consistent with seasonal buffering of river discharge by an underlying sandstone aquifer. Significantly higher wet season CH4 concentrations in swamp and forest rivers suggest that CH4 can be derived from floating macrophytes during flooding and/or enhanced methanogenesis in adjacent flooded soils. Swamp rivers also exhibited both low (47 %) and high (205 %) N2O saturation but wet season values were overall significantly lower than in either tropical forest or savannah rivers, which were always supersaturated (103-266 %) and for which the overall means and ranges of N2O were not significantly different. In swamp and forest rivers O-2 saturation co-varied inversely with CH4 saturation (log %) and positively with % N2O. A significant positive correlation between N2O and O-2 saturation in swamp rivers was coincident with strong N2O and O-2 undersaturation, indicating N2O consumption during denitrification in the sediments. In savannah rivers persistent N2O supersaturation and a negative correlation between N2O and O-2 suggest N2O production mainly by nitrification. This is consistent with a stronger correlation between N2O and NH4+ than between N2O and NO3-. Our ranges of values for CH4 and N2O emission fluxes (33-48 705 mu mol CH4 m(-2) d(-1); 1-67 mu mol N(2)Om(2)(-) d(-1)) are within the ranges previously estimated for sub-Saharan African rivers but they include uncertainties deriving from our use of basin-wide values for CH4 and N2O gas transfer velocities. Even so, because we did not account for any contribution from ebullition, which is quite likely for CH4 (at least 20 %), we consider our emission fluxes for CH4 to be conservative.

  • 727. Vandenberg, Laura N.
    et al.
    Ågerstrand, Marlene
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Beronius, Anna
    Beausoleil, Claire
    Bergman, Åke
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Swedish Toxicology Sciences Research Center, Sweden.
    Bero, Lisa A.
    Bornehag, Carl-Gustaf
    Boyer, C. Scott
    Cooper, Glinda S.
    Cotgreave, Ian
    Gee, David
    Grandjean, Philippe
    Guyton, Kathryn Z.
    Hass, Ulla
    Heindel, Jerrold J.
    Jobling, Susan
    Kidd, Karen A.
    Kortenkamp, Andreas
    Macleod, Malcolm R.
    Martin, Olwenn V.
    Norinder, Ulf
    Scheringer, Martin
    Thayer, Kristina A.
    Toppari, Jorma
    Whaley, Paul
    Woodruff, Tracey J.
    Rudén, Christina
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    A proposed framework for the systematic review and integrated assessment (SYRINA) of endocrine disrupting chemicals2016In: Environmental health, ISSN 1476-069X, E-ISSN 1476-069X, Vol. 15, article id 74Article in journal (Refereed)
    Abstract [en]

    Background: The issue of endocrine disrupting chemicals (EDCs) is receiving wide attention from both the scientific and regulatory communities. Recent analyses of the EDC literature have been criticized for failing to use transparent and objective approaches to draw conclusions about the strength of evidence linking EDC exposures to adverse health or environmental outcomes. Systematic review methodologies are ideal for addressing this issue as they provide transparent and consistent approaches to study selection and evaluation. Objective methods are needed for integrating the multiple streams of evidence (epidemiology, wildlife, laboratory animal, in vitro, and in silico data) that are relevant in assessing EDCs.

    Methods: We have developed a framework for the systematic review and integrated assessment (SYRINA) of EDC studies. The framework was designed for use with the International Program on Chemical Safety (IPCS) and World Health Organization (WHO) definition of an EDC, which requires appraisal of evidence regarding 1) association between exposure and an adverse effect, 2) association between exposure and endocrine disrupting activity, and 3) a plausible link between the adverse effect and the endocrine disrupting activity.

    Results: Building from existing methodologies for evaluating and synthesizing evidence, the SYRINA framework includes seven steps: 1) Formulate the problem; 2) Develop the review protocol; 3) Identify relevant evidence; 4) Evaluate evidence from individual studies; 5) Summarize and evaluate each stream of evidence; 6) Integrate evidence across all streams; 7) Draw conclusions, make recommendations, and evaluate uncertainties. The proposed method is tailored to the IPCS/WHO definition of an EDC but offers flexibility for use in the context of other definitions of EDCs.

    Conclusions: When using the SYRINA framework, the overall objective is to provide the evidence base needed to support decision making, including any action to avoid/minimise potential adverse effects of exposures. This framework allows for the evaluation and synthesis of evidence from multiple evidence streams. Finally, a decision regarding regulatory action is not only dependent on the strength of evidence, but also the consequences of action/inaction, e.g. limited or weak evidence may be sufficient to justify action if consequences are serious or irreversible.

  • 728. Varpe, Sandeep R.
    et al.
    Kolhe, Amol R.
    Kutal, Ganesh C.
    Pawar, Ganesh V.
    Payra, Swagata
    Budhavant, Krishnakant B.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Maldives Climate Observatory at Hanimaadhoo, Republic of the Maldives; Indian Institute of Science, India.
    Aher, Gajanan R.
    Devara, Panuganti C. S.
    Heterogeneity in aerosol characteristics at the semi-arid and island AERONET observing sites in India and Maldives2018In: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 39, no 19, p. 6137-6169Article in journal (Refereed)
    Abstract [en]

    Multi-year Aerosol Robotic Network (AERONET) direct Sun retrieved and inversion algorithm derived aerosol products at a semi-arid, urban site, Jaipur (26.90 degrees N, 75.80 degrees E) and island observing site, Maldives Climate Observatory-Hanimaadhoo (MCO-Hanimaadhoo, 6.74 degrees N, 73.17 degrees E) are analysed to investigate heterogeneity in aerosol optical and microphysical properties. Results reveal the existence of a large seasonal diversity in the frequency distributions of aerosol optical depth (AOD(500) (nm), AOD(1020) (nm)) and angstrom ngstrom exponent (AE(440-870) (nm)) during different seasons at Jaipur and MCO-Hanimaadhoo. These are indicative of the advection of different aerosol types (viz., black carbon (BC) aerosol, organic aerosol, sulfate particle, dust, sea salt, nitrate particle, and mixtures thereof) from a variety of production mechanisms influenced by strong seasonal changes of anthropogenic activities as well as modulations induced by the climatic condition. The cumulative frequency analysis of the single scattering albedo (SSA) difference (i.e. Delta SSA = SSA(440) (nm) - SSA(1020) (nm)) shows that at Jaipur Delta SSA is predominantly negative (around 88% days) while at MCO-Hanimaadhoo it is positive (around 74% days). The positive and negative values of Delta SSA are respectively linked to a stronger absorption by BC mixed anthropogenic pollution aerosols at 1020 nm and to a stronger absorption by mineral dust containing iron oxide at 440 nm. The spectral behaviour of SSA, thus, facilitates investigation of the existence of iron oxide or BC in aerosols. The 'Bivariate Kernel density' plots of SSA versus fine-mode fraction (FMF) of AOD(440) (nm)/AE(440-870) (nm) reveal that at Jaipur the aerosol ensemble consists of coarse-mode particles (AE and FMF cluster in the range 0.2-0.4), a dominant category along with significant fine-mode and much less mixed category. At MCO-Hanimaadhoo fine-mode particle category (with FMF and AE cluster in the range 0.90-0.95 and 1.2-1.6 respectively) is the only dominant category. The persisting log-normal bimodal feature in aerosol volume size distribution (AVSD) is observed both at Jaipur and MCO-Hanimaadhoo. The modal volume concentration of coarse-mode aerosol decreases from FMF of AOD(675) (nm) = 0.25 (inherently belonging to the coarse-mode regime) to FMF of AOD(675) (nm) = 0.95 (inherently belonging to the fine-mode regime). This transformation in coarse-to fine-mode volume concentration is associated with a steady rise in AE(440-874) (nm) supporting this changeover.

  • 729. Vehmaa, Anu
    et al.
    Almen, Anna-Karin
    Brutemark, Andreas
    Paul, Allanah
    Riebesell, Ulf
    Furuhagen, Sara
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Swedish Chemical Agency, Sweden.
    Engstrom-Ost, Jonna
    Ocean acidification challenges copepod phenotypic plasticity2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 22, p. 6171-6182Article in journal (Refereed)
    Abstract [en]

    Ocean acidification is challenging phenotypic plasticity of individuals and populations. Calanoid copepods (zooplankton) are shown to be fairly plastic against altered pH conditions, and laboratory studies indicate that transgenerational effects are one mechanism behind this plasticity. We studied phenotypic plasticity of the copepod Acartia sp. in the course of a pelagic, large-volume mesocosm study that was conducted to investigate ecosystem and biogeochemical responses to ocean acidification. We measured copepod egg production rate, egg-hatching success, adult female size and adult female antioxidant capacity (ORAC) as a function of acidification (fCO(2) similar to 365-1231 mu atm) and as a function of quantity and quality of their diet. We used an egg transplant experiment to reveal whether transgenerational effects can alleviate the possible negative effects of ocean acidification on offspring development. We found significant negative effects of ocean acidification on adult female size. In addition, we found signs of a possible threshold at high fCO(2), above which adaptive maternal effects cannot alleviate the negative effects of acidification on egg-hatching and nauplii development. We did not find support for the hypothesis that insufficient food quantity (total particulate carbon <55 mu m) or quality (C : N) weakens the transgenerational effects. However, females with high-ORAC-produced eggs with high hatching success. Overall, these results indicate that Acartia sp. could be affected by projected near-future CO2 levels.

  • 730. von Deimling, Thomas Schneider
    et al.
    Kleinen, Thomas
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Knoblauch, Christian
    Beer, Christian
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Brovkin, Victor
    Long-term deglacial permafrost carbon dynamics in MPI-ESM2018In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 14, no 12, p. 2011-2036Article in journal (Refereed)
    Abstract [en]

    We have developed a new module to calculate soil organic carbon (SOC) accumulation in perennially frozen ground in the land surface model JSBACH. Running this offline version of MPI-ESM we have modelled long-term permafrost carbon accumulation and release from the Last Glacial Maximum (LGM) to the pre-industrial (PI) age. Our simulated near-surface PI permafrost extent of 16.9 x 10(6) km(2) is close to observational estimates. Glacial boundary conditions, especially ice sheet coverage, result in profoundly different spatial patterns of glacial permafrost extent. Deglacial warming leads to large-scale changes in soil temperatures, manifested in permafrost disappearance in southerly regions, and permafrost aggregation in formerly glaciated grid cells. In contrast to the large spatial shift in simulated permafrost occurrence, we infer an only moderate increase in total LGM permafrost area (18.3 x 10(6) km(2)) - together with pronounced changes in the depth of seasonal thaw. Earlier empirical reconstructions suggest a larger spread of permafrost towards more southerly regions under glacial conditions, but with a highly uncertain extent of non-continuous permafrost. Compared to a control simulation without describing the transport of SOC into perennially frozen ground, the implementation of our newly developed module for simulating permafrost SOC accumulation leads to a doubling of simulated LGM permafrost SOC storage (amounting to a total of similar to 150 PgC). Despite LGM temperatures favouring a larger permafrost extent, simulated cold glacial temperatures - together with low precipitation and low CO2 levels - limit vegetation productivity and therefore prevent a larger glacial SOC build-up in our model. Changes in physical and biogeochemical boundary conditions during deglacial warming lead to an increase in mineral SOC storage towards the Holocene (168 PgC at PI), which is below observational estimates (575 PgC in continuous and discontinuous permafrost). Additional model experiments clarified the sensitivity of simulated SOC storage to model parameters, affecting long-term soil carbon respiration rates and simulated ALDs. Rather than a steady increase in carbon release from the LGM to PI as a consequence of deglacial permafrost degradation, our results suggest alternating phases of soil carbon accumulation and loss as an effect of dynamic changes in permafrost extent, ALDs, soil litter input, and heterotrophic respiration.

  • 731. Vonk, Jorien E.
    et al.
    Drenzek, Nicholas J.
    Hughen, Konrad A.
    Stanley, Rachel H. R.
    McIntyre, Cameron
    Montlucon, Daniel B.
    Giosan, Liviu
    Southon, John R.
    Santos, Guaciara M.
    Druffel, Ellen R. M.
    Andersson, August A.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Sköld, Martin
    Stockholm University, Faculty of Science, Department of Mathematics.
    Eglinton, Timothy I.
    Temporal deconvolution of vascular plant-derived fatty acids exported from terrestrial watersheds2019In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 244, p. 502-521Article in journal (Refereed)
    Abstract [en]

    Relatively little is known about the amount of time that lapses between the photosynthetic fixation of carbon by vascular land plants and its incorporation into the marine sedimentary record, yet the dynamics of terrestrial carbon sequestration have important implications for the carbon cycle. Vascular plant carbon may encounter multiple potential intermediate storage pools and transport trajectories, and the age of vascular plant carbon accumulating in marine sediments will reflect these different pre-depositional histories. Here, we examine down-core C-14 profiles of higher plant leaf wax-derived fatty acids isolated from high fidelity sedimentary sequences spanning the so-called bomb-spike, and encompassing a ca. 60-degree latitudinal gradient from tropical (Cariaco Basin), temperate (Saanich Inlet), and polar (Mackenzie Delta) watersheds to constrain integrated vascular plant carbon storage/transport times (residence times). Using a modeling framework, we find that, in addition to a young (conditionally defined as < 50 y) carbon pool, an old pool of compounds comprises 49 to 78 % of the fractional contribution of organic carbon (OC) and exhibits variable ages reflective of the environmental setting. For the Mackenzie Delta sediments, we find a mean age of the old pool of 28 ky (+/- 9.4, standard deviation), indicating extensive pre-aging in permafrost soils, whereas the old pools in Saanich Inlet and Cariaco Basin sediments are younger, 7.9 (+/- 5.0) and 2.4 (+/- 0.50) to 3.2 (+/- 0.54) ky, respectively, indicating less protracted storage in terrestrial reservoirs. The young pool showed clear annual contributions for Saanich Inlet and Mackenzie Delta sediments (comprising 24% and 16% of this pool, respectively), likely reflecting episodic transport of OC from steep hillside slopes surrounding Saanich Inlet and annual spring flood deposition in the Mackenzie Delta, respectively. Contributions of 5-10 year old OC to the Cariaco Basin show a short delay of OC inflow, potentially related to transport time to the offshore basin. Modeling results also indicate that the Mackenzie Delta has an influx of young but decadal material (20-30 years of age), pointing to the presence of an intermediate reservoir. Overall, these results show that a significant fraction of vascular plant C undergoes pre-aging in terrestrial reservoirs prior to accumulation in deltaic and marine sediments. The age distribution, reflecting both storage and transport times, likely depends on landscape-specific factors such as local topography, hydrographic characteristics, and mean annual temperature of the catchment, all of which affect the degree of soil buildup and preservation. We show that catchment-specific carbon residence times across landscapes can vary by an order of magnitude, with important implications both for carbon cycle studies and for the interpretation of molecular terrestrial paleoclimate records preserved in sedimentary sequences.

  • 732. Vonk, Jorien E.
    et al.
    Tesi, Tommaso
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. ISMAR Institute of Marine Sciences, Italy.
    Bröder, Lisa
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Holmstrand, Henry
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Andersson, August
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Dudarev, Oleg
    Semiletov, Igor
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Distinguishing between old and modern permafrost sources in the northeast Siberian land-shelf system with compound-specific delta H-2 analysis2017In: The Cryosphere, ISSN 1994-0416, E-ISSN 1994-0424, Vol. 11, no 4, p. 1879-1895Article in journal (Refereed)
    Abstract [en]

    Pleistocene ice complex permafrost deposits contain roughly a quarter of the organic carbon (OC) stored in permafrost (PF) terrain. When permafrost thaws, its OC is remobilized into the (aquatic) environment where it is available for degradation, transport or burial. Aquatic or coastal environments contain sedimentary reservoirs that can serve as archives of past climatic change. As permafrost thaw is increasing throughout the Arctic, these reservoirs are important locations to assess the fate of remobilized permafrost OC. We here present compound-specific deuterium (delta H-2) analysis on leaf waxes as a tool to distinguish between OC released from thawing Pleistocene permafrost (ice complex deposits; ICD) and from thawing Holocene permafrost (from near-surface soils). Bulk geochemistry (%OC; delta C-13; % total nitrogen, TN) was analyzed as well as the concentrations and delta H-2 signatures of long-chain n-alkanes (C-21 to C-33) and midto long-chain n-alkanoic acids (C-16 to C-30) extracted from both ICD-PF samples (n = 9) and modern vegetation and Ohorizon (topsoil-PF) samples (n = 9) from across the northeast Siberian Arctic. Results show that these topsoil-PF samples have higher %OC, higher OC/TN values and more depleted delta(COC)-C-13 values than ICD-PF samples, suggesting that these former samples trace a fresher soil and/or vegetation source. Whereas the two investigated sources differ on the bulk geochemical level, they are, however, virtually indistinguishable when using leaf wax concentrations and ratios. However, on the molecular isotope level, leaf wax biomarker delta H-2 values are statistically different between topsoil PF and ICD PF. For example, the mean delta H-2 value of C-29 n-alkane was -246 +/- 13% (mean +/- SD) for topsoil PF and -280 +/- 12 parts per thousand for ICD PF. With a dynamic isotopic range (difference between two sources) of 34 to 50 parts per thousand; the isotopic fingerprints of individual, abundant, biomarker molecules from leaf waxes can thus serve as endmembers to distinguish between these two sources. We tested this molecular delta H-2 tracer along with another source-distinguishing approach, dual-carbon (delta C-13-Delta C-14) isotope composition of bulk OC, for a surface sediment transect in the Laptev Sea. Results show that general offshore patterns along the shelfslope transect are similar, but the source apportionment between the approaches vary, which may highlight the advan-tages of either. This study indicates that the application of delta H-2 leaf wax values has potential to serve as a complementary quantitative measure of the source and differential fate of OC thawed out from different permafrost compartments.

  • 733. Wagner, Robert
    et al.
    Yan, Chao
    Lehtipalo, Katrianne
    Duplissy, Jonathan
    Nieminen, Tuomo
    Kangasluoma, Juha
    Ahonen, Lauri R.
    Dada, Lubna
    Kontkanen, Jenni
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. University of Helsinki, Finland.
    Manninen, Hanna E.
    Dias, Antonio
    Amorim, Antonio
    Bauer, Paulus S.
    Bergen, Anton
    Bernhammer, Anne-Kathrin
    Bianchi, Federico
    Brilke, Sophia
    Mazon, Stephany Buenrostro
    Chen, Xuemeng
    Draper, Danielle C.
    Fischer, Lukas
    Frege, Carla
    Fuchs, Claudia
    Garmash, Olga
    Gordon, Hamish
    Hakala, Jani
    Heikkinen, Liine
    Heinritzi, Martin
    Hofbauer, Victoria
    Hoyle, Christopher R.
    Kirkby, Jasper
    Kürten, Andreas
    Kvashnin, Alexander N.
    Laurila, Tiia
    Lawler, Michael J.
    Mai, Huajun
    Makhmutov, Vladimir
    Mauldin, Roy L.
    Molteni, Ugo
    Nichman, Leonid
    Nie, Wei
    Ojdanic, Andrea
    Onnela, Antti
    Piel, Felix
    Quéléver, Lauriane L. J.
    Rissanen, Matti P.
    Sarnela, Nina
    Schallhart, Simon
    Sengupta, Kamalika
    Simon, Mario
    Stolzenburg, Dominik
    Stozhkov, Yuri
    Tröstl, Jasmin
    Viisanen, Yrjo
    Vogel, Alexander L.
    Wagner, Andrea C.
    Xiao, Mao
    Ye, Penglin
    Baltensperger, Urs
    Curtius, Joachim
    Donahue, Neil M.
    Flagan, Richard C.
    Gallagher, Martin
    Hansel, Armin
    Smith, James N.
    Tomé, António
    Winkler, Paul M.
    Worsnop, Douglas
    Ehn, Mikael
    Sipilä, Mikko
    Kerminen, Veli-Matti
    Petäjä, Tuukka
    Kulmala, Markku
    The role of ions in new particle formation in the CLOUD chamber2017In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 17, no 24, p. 15181-15197Article in journal (Refereed)
    Abstract [en]

    The formation of secondary particles in the atmosphere accounts for more than half of global cloud condensation nuclei. Experiments at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber have underlined the importance of ions for new particle formation, but quantifying their effect in the atmosphere remains challenging. By using a novel instrument setup consisting of two nanoparticle counters, one of them equipped with an ion filter, we were able to further investigate the ion-related mechanisms of new particle formation. In autumn 2015, we carried out experiments at CLOUD on four systems of different chemical compositions involving monoterpenes, sulfuric acid, nitrogen oxides, and ammonia. We measured the influence of ions on the nucleation rates under precisely controlled and atmospherically relevant conditions. Our results indicate that ions enhance the nucleation process when the charge is necessary to stabilize newly formed clusters, i.e., in conditions in which neutral clusters are unstable. For charged clusters that were formed by ion-induced nucleation, we were able to measure, for the first time, their progressive neutralization due to recombination with oppositely charged ions. A large fraction of the clusters carried a charge at 1.5 nm diameter. However, depending on particle growth rates and ion concentrations, charged clusters were largely neutralized by ion-ion recombination before they grew to 2.5 nm. At this size, more than 90% of particles were neutral. In other words, particles may originate from ion-induced nucleation, although they are neutral upon detection at diameters larger than 2.5 nm. Observations at Hyytiala, Finland, showed lower ion concentrations and a lower contribution of ion-induced nucleation than measured at CLOUD under similar conditions. Although this can be partly explained by the observation that ion-induced fractions decrease towards lower ion concentrations, further investigations are needed to resolve the origin of the discrepancy.

  • 734.
    Wallin, Cecilia
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Sholts, Sabrina B.
    Österlund, Nicklas
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Luo, Jinghui
    Jarvet, Jüri
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. The National Institute of Chemical Physics and Biophysics, Estonia.
    Roos, Per M.
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Wärmländer, Sebastian K. T. S.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Alzheimer's disease and cigarette smoke components: effects of nicotine, PAHs, and Cd(II), Cr(III), Pb(II), Pb(IV) ions on amyloid-beta peptide aggregation2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 14423Article in journal (Refereed)
    Abstract [en]

    Cigarette smoking is a significant risk factor for Alzheimer’s disease (AD), which is associated with extracellular brain deposits of amyloid plaques containing aggregated amyloid-β (Aβ) peptides. Aβ aggregation occurs via multiple pathways that can be influenced by various compounds. Here, we used AFM imaging and NMR, fluorescence, and mass spectrometry to monitor in vitro how Aβ aggregation is affected by the cigarette-related compounds nicotine, polycyclic aromatic hydrocarbons (PAHs) with one to five aromatic rings, and the metal ions Cd(II), Cr(III), Pb(II), and Pb(IV). All PAHs and metal ions modulated the Aβ aggregation process. Cd(II), Cr(III), and Pb(II) ions displayed general electrostatic interactions with Aβ, whereas Pb(IV) ions showed specific transient binding coordination to the N-terminal Aβ segment. Thus, Pb(IV) ions are especially prone to interact with Aβ and affect its aggregation. While Pb(IV) ions affected mainly Aβ dimer and trimer formation, hydrophobic toluene mainly affected formation of larger aggregates such as tetramers. The uncharged and hydrophilic nicotine molecule showed no direct interactions with Aβ, nor did it affect Aβ aggregation. Our Aβ interaction results suggest a molecular rationale for the higher AD prevalence among smokers, and indicate that certain forms of lead in particular may constitute an environmental risk factor for AD.

  • 735. Wang, Jian
    et al.
    Krejci, Radovan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Giangrandel, Scott
    Kuang, Chongai
    Barbosa, Henrique M. J.
    Brito, Joel
    Carbone, Samara
    Chi, Xuguang
    Comstock, Jennifer
    Ditas, Florian
    Lavric, Jost
    Manninen, Hanna E.
    Mei, Fan
    Moran-Zuloaga, Daniel
    Poehlker, Christopher
    Poehlker, Mira L.
    Saturno, Jorge
    Schmid, Beat
    Souza, Rodrigo A. F.
    Springston, Stephen R.
    Tomlinson, Jason M.
    Toto, Tami
    Walter, David
    Wimmer, Daniela
    Smith, James N.
    Kulmala, Markku
    Machado, Luiz A. T.
    Artaxo, Paulo
    Andreae, Meinrat O.
    Petaja, Tuukka
    Martin, Scot T.
    Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall2016In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 539, no 7629, p. 416-419Article in journal (Refereed)
    Abstract [en]

    The nucleation of atmospheric vapours is an important source of new aerosol particles that can subsequently grow to form cloud condensation nuclei in the atmosphere(1). Most field studies of atmospheric aerosols over continents are influenced by atmospheric vapours of anthropogenic origin (for example, ref. 2) and, in consequence, aerosol processes in pristine, terrestrial environments remain poorly understood. The Amazon rainforest is one of the few continental regions where aerosol particles and their precursors can be studied under near-natural conditions(3-5), but the origin of small aerosol particles that grow into cloud condensation nuclei in the Amazon boundary layer remains unclear(6-8). Here we present aircraft- and ground-based measurements under clean conditions during the wet season in the central Amazon basin. We find that high concentrations of small aerosol particles (with diameters of less than 50 nanometres) in the lower free troposphere are transported from the free troposphere into the boundary layer during precipitation events by strong convective downdrafts and weaker downward motions in the trailing stratiform region. This rapid vertical transport can help to maintain the population of particles in the pristine Amazon boundary layer, and may therefore influence cloud properties and climate under natural conditions.

  • 736. Wang, Thanh
    et al.
    Vestergren, Robin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Norwegian Institute for Air Research (NILU), FRAM − High North Research Centre on Climate and the Environment, Norway.
    Herzke, Dorte
    Yu, Junchao
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Levels, Isomer Profiles, and Estimated Riverine Mass Discharges of Perfluoroalkyl Acids and Fluorinated Alternatives at the Mouths of Chinese Rivers2016In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, no 21, p. 11584-11592Article in journal (Refereed)
    Abstract [en]

    An extensive sampling campaign was undertaken to study the levels, isomer profiles and riverine mass discharges of perfluoroalkyl acids (PFAAs) and fluorinated alternatives in 19 Chinese rivers. The levels and homologue profiles of Sigma(10)PFAAs varied considerably among the 19 rivers (mean 106; median 16.3, range 8.91240 ng/L), indicating the influence of specific point sources. Highly branched isomer profiles of perfluorooctanoic acid (1825% br-PFOA) in rivers with elevated concentrations (96352 ng/L) indicate that releases during production of PFOA by electrochemical fluorination and/or its use in fluoropolymer manufacture were the dominant sources to these rivers. The fluorinated alternatives 6:2 fluorotelomer sulfonate (detection frequency 21%, < 0.13.1 ng/L) and chlorinated polyfluoroalkyl ether sulfonate F-53B (51%, < 0.5678.5 ng/L) were also found in some rivers. The total Chinese riverine mass discharges of PFOA (mean 80.9; range 16.8168 t/y) (including monitoring data from this and other studies) were in good agreement with theoretical PFOA emission estimates (17.3203 t/y) whereas riverine mass discharges of PFOS (mean 3.6; range 1.95.6 t/y) could only account for a minor fraction of theoretically estimated PFOS releases (70 t/y). This study provides empirical evidence that emissions from Chinese point sources likely dominate the global emissions of several legacy PFASs (notably PFOA) and fluorinated alternatives (e.g., F-53B).

  • 737. Wang, Yuan
    et al.
    Shi, Yali
    Vestergren, Robin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. IVL Swedish Environmental Research Institute, Sweden.
    Zhou, Zhen
    Liang, Yong
    Cai, Yaqi
    Using hair, nail and urine samples for human exposure assessment of legacy and emerging per- and polyfluoroalkyl substances2018In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 636, p. 383-391Article in journal (Refereed)
    Abstract [en]

    Non-invasive samples present ethical and practical benefits for investigating human exposure to hazardous contaminants, but analytical challenges and difficulties to interpret the results limit their application in biomonitoring. Here we investigated the potential for using hair, nail and urine samples as a measure of internal exposure to an array of legacy and emerging per- and polyfluoroalkyl substances (PFASs) in two populations with different exposure conditions. Paired urine-serum measurements of PFASs from a group of highly exposed fishery employees displayed strong correlations for PFASs with three to eight perfluorinated carbons (p > 0.653; p < 0.01). Consistent statistical correlations and transfer ratios in nails and hair from both populations demonstrated that these non-invasive samples can be used as a measure of internal exposure to perfluorooctane sulfonic acid and CS chlorinated polyfluoralkyl ether sulfonic acid (CS Cl-PFESA). Contrastingly, the infrequent detections and or lack of consistent transfer ratios for perfluorooctanoic acid, perfluorononanoic acid and short-chain PFASs in hair and nail samples indicate passive uptake from the external environment rather than uptake and internal distribution. Collectively, the study supports the use of urine samples as a valid measure of internal exposure for a range of short- and medium-chain PFASs, while the validity of nail and hair samples as a measure of internal exposure may vary for different PFASs and populations. The ubiquitous detection of C8 CI-PFESA in all sample matrices from both populations indicates widespread exposure to this contaminant of emerging concern in China.

  • 738. Wang, Yuan
    et al.
    Vestergren, Robin
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Shi, Yali
    Cao, Dong
    Xu, Lin
    Cai, Yaqi
    Zhao, Xiaoli
    Wu, Fengchang
    Identification, Tissue Distribution, and Bioaccumulation Potential of Cyclic Perfluorinated Sulfonic Acids Isomers in an Airport Impacted Ecosystem2016In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, no 20, p. 10923-10932Article in journal (Refereed)
    Abstract [en]

    The use of cyclic perfluoroalkyl acids as anticorrosive agents in hydraulic fluids remains a poorly characterized source of organofluorine compounds to the environment. Here, we investigated the presence of perfluoroethylenecyclohexanesulfonate (PFECHS) isomers in environmental samples for the first time using a combination of high resolution and tandem mass spectrometry. Five distinct peaks attributed to different isomers of PFECHS and perfluoropropylcyclopentanesulfonate (PFPCPeS) were identified in environmental samples. The sum of PFECHS and PFPCPeS isomers displayed logarithmically decreasing spatial trends in water (1.04-324 ng/L) and sediment samples (<MLQ 2.23 ng/g dw) with increasing distance from Beijing international airport. PFECHS and PFPCPeS displayed the highest accumulation in liver, kidney, blood and bladder and average whole body bioaccumulation factors (log BAF(whole-body)) were estimated to be 2.7 and 1.9 respectively. Isomer-specific differences in the tissue/blood distribution ratios and BAF(whole-body) indicate that ring structure and position of the sulfonic acid group affect the bioaccumulation potential of cyclic perfluoroalkyl acids. Based on the high mobility and moderate bioaccumulation potential of cyclic perfluorinated acids it is suggested that contamination of aquifers used for drinking water around airports may be a hitherto overlooked problem for this novel class of contaminants.

  • 739. Wang, Zhanyun
    et al.
    Boucher, Justin M.
    Scheringer, Martin
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Hungerbühler, Konrad
    Toward a Comprehensive Global Emission Inventory of C-4-C-10 Perfluoroalkanesulfonic Acids (PFSAs) and Related Precursors: Focus on the Life Cycle of C-8-Based Products and Ongoing Industrial Transition2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, no 8, p. 4482-4493Article in journal (Refereed)
    Abstract [en]

    Here a new global emission inventory of C-4-C-10 perfluoroalkanesulfonic acids (PFSAs) from the life cycle of perfluorooctanesulfonyl fluoride (POSF)-based products in 1958-2030 is presented. In particular, we substantially improve and expand the previous frameworks by incorporating missing pieces (e.g., emissions to soil through land treatment, overlooked precursors) and updating parameters (e.g., emission factors, degradation half-lives). In 1958-2015, total direct and indirect emissions of perfluorooctanesulfonic acid (PFOS) are estimated as 1228-4930 tonnes, and emissions of PFOS precursors are estimated as 1230-8738 tonnes and approximately 670 tonnes for x-perfluorooctanesulfonamides/sulfonamido ethanols (xFOSA/Es) and POSF, respectively. Most of these emissions occurred between 1958 and 2002, followed by a substantial decrease. This confirms the positive effect of the ongoing transition to phase out POSF-based products, although this transition may still require substantial time and cause substantial additional releases of PFOS (8-153 tonnes) and xFOSA/Es (4-698 tonnes) in 2016 to 2030. The modeled environmental concentrations obtained by coupling the emission inventory and a global multimedia mass-balance model generally agree well with reported field measurements, suggesting that the inventory captures the actual emissions of PFOS and xFOSA/Es for the time being despite remaining uncertainties. Our analysis of the key uncertainties and open questions of and beyond the inventory shows that, among others, degradation of side-chain fluorinated polymers in the environment and landfills can be a long-term, (potentially) substantial source of PFOS.

  • 740. Wang, Zhanyun
    et al.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Berger, Urs
    Hungerbuhler, Konrad
    Scheringer, Martin
    Comparative assessment of the environmental hazards of and exposure to perfluoroalkyl phosphonic and phosphinic acids (PFPAs and PFPiAs): Current knowledge, gaps, challenges and research needs2016In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 89-90, p. 235-247Article, review/survey (Refereed)
    Abstract [en]

    Perfluoroalkyl phosphonic and phosphinic acids (PFPAs and PFPiAs) are sub-groups of per- and polyfluoroalkyl substances (PFASs) that have been commercialized since the 1970s, particularly as defoamers in pesticide formulations and wetting agents in consumer products. Recently, C-4/C-4 PFPiA and its derivatives have been presented as alternatives to long-chain PFASs in certain applications. In this study, we systematically assess the publicly available information on the hazardous properties, occurrence, and exposure routes of PFPAs and PFPiAs, and make comparisons to the corresponding properties of their better-known carboxylic and sulfonic acid analogs (i.e. PFCAs and PFPAs). This comparative assessment indicates that [i] PFPAs likely have high persistence and long-range transport potential; [ii] PFPiAs may transform to PFPAs (and possibly PFCAs) in the environment and biota; [iii] certain PFPAs and PFPiAs can only be slowly eliminated from rainbow trout and rats, similarly to long-chain PFCAs and PFPAs; [iv] PFPAs and PFPiAs have modes-of-action that are both similar to, and different from, those of PFCAs and PFSAs; and [v] the measured levels of PFPAs/PFPiAs in the global environment and biota appear to be low in comparison to PFCAs and PFPAs, suggesting, for the time being, low risks from PFPAs and PFPiAs alone. Although risks from individual PFPAs/PFPiAs are currently low, their ongoing production and use and high persistence will lead to increasing exposure and risks over time. Furthermore, simultaneous exposure to PFPAs, PFPiAs and other PFASs may result in additive effects necessitating cumulative risk assessments. To facilitate effective future research, we highlight possible strategies to overcome sampling and analytical challenges.

  • 741. Wang, Zhanyun
    et al.
    DeWitt, Jamie C.
    Higgins, Christopher P.
    Cousins, Ian T.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)?2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, no 5, p. 2508-2518Article in journal (Refereed)
    Abstract [en]

    More than 3000 per- and polyfluoroalkyl substances (PFASs) are, or have been, on the global market, yet most research and regulation continues to focus on a limited selection of rather well-known long-chain FASs, particularly perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA) and their precursors. Continuing to overlook the vast majority of other PFASs is a major concern for society. We provide recommendations for how to proceed with research and cooperation to tackle the vast number of PFASs on the market and in the environment.

  • 742. Weidemann, Eva
    et al.
    Andersson, Patrik L.
    Bidleman, Terry
    Boman, Christoffer
    Carlin, Danielle J.
    Collina, Elena
    Cormier, Stephania A.
    Gouveia-Figueira, Sandra C.
    Gullett, Brian K.
    Johansson, Christer
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Environment and Health Administration, Stockholm, Sweden.
    Lucas, Donald
    Lundin, Lisa
    Lundstedt, Staffan
    Marklund, Stellan
    Nording, Malin L.
    Ortuno, Nuria
    Sallam, Asmaa A.
    Schmidt, Florian M.
    Jansson, Stina
    14th congress of combustion by-products and their health effects-origin, fate, and health effects of combustion-related air pollutants in the coming era of bio-based energy sources2016In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 23, no 8, p. 8141-8159Article in journal (Refereed)
    Abstract [en]

    The 14th International Congress on Combustion By-Products and Their Health Effects was held in UmeAyen, Sweden from June 14th to 17th, 2015. The Congress, mainly sponsored by the National Institute of Environmental Health Sciences Superfund Research Program and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, focused on the Origin, fate and health effects of combustion-related air pollutants in the coming era of bio-based energy sources. The international delegates included academic and government researchers, engineers, scientists, policymakers and representatives of industrial partners. The Congress provided a unique forum for the discussion of scientific advances in this research area since it addressed in combination the health-related issues and the environmental implications of combustion by-products. The scientific outcomes of the Congress included the consensus opinions that: (a) there is a correlation between human exposure to particulate matter and increased cardiac and respiratory morbidity and mortality; (b) because currently available data does not support the assessment of differences in health outcomes between biomass smoke and other particulates in outdoor air, the potential human health and environmental impacts of emerging air-pollution sources must be addressed. Assessment will require the development of new approaches to characterize combustion emissions through advanced sampling and analytical methods. The Congress also concluded the need for better and more sustainable e-waste management and improved policies, usage and disposal methods for materials containing flame retardants.

  • 743.
    Weiss, Jana M.
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Swedish University of Agricultural Sciences, Sweden.
    Gustafsson, Åsa
    Gerde, Per
    Bergman, Åke
    Lindh, Christian H.
    Krais, Annette M.
    Daily intake of phthalates, MEHP, and DINCH by ingestion and inhalation2018In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 208, p. 40-49Article in journal (Refereed)
    Abstract [en]

    Phthalate esters, suspected endocrine disrupting chemicals, are used in a wide range of applications. Because phthalate esters are not covalently bound, they can easily leach into the indoor environment and associate to dust particles. Thus, exposure may occur through inhalation, ingestion, or contact with the skin. However, it is unclear to what degree indoor dust contributes to the daily intake of phthalate esters. This study investigates household dust as an exposure pathway for seven phthalate esters, the monoester MEHP, and the plasticizer DINCH. Household dust collected from children's sleeping rooms and from living rooms were analysed using gas and liquid chromatography tandem mass spectrometry. To compare two exposure pathways, different dust particle sizes were generated: a respirable fraction (<5 mu m) and an ingested particle fraction in the anticipated size range of skin adherence (<75 mu m). Modelling of dust inhalation and ingestion showed that the daily intake of dust-bound phthalate esters was likely to be 2 times (inhalation) to 12 times (ingestion) higher for 21-month-old children than for adults. These children's daily uptake of phthalate esters was 40-140 times higher through ingestion than inhalation. Furthermore, dust may be an exposure pathway for phthalate esters as well as for MEHP. Therefore, phthalate monoesters could be environmental contaminants of their own and need to be considered in health risk assessments.

  • 744. Werner, Josephina
    et al.
    Dalirian, Maryam
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Walz, Marie-Madeleine
    Ekholm, Victor
    Wideqvist, Ulla
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Lowe, Samuel J.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Öhrwal, Gunnar
    Persson, Ingmar
    Riipinen, Ilona
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Björneholm, Olle
    Surface Partitioning in Organic-Inorganic Mixtures Contributes to the Size-Dependence of the Phase-State of Atmospheric Nanoparticles2016In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, no 14, p. 7434-7442Article in journal (Refereed)
    Abstract [en]

    Atmospheric particulate matter is one of the main factors governing the Earth's radiative budget, but its exact effects on the global climate are still uncertain. Knowledge on the molecular-scale surface phenomena as well as interactions between atmospheric organic and inorganic compounds is necessary for understanding the role of airborne nanoparticles in the Earth system. In this work, surface composition of aqueous model systems containing succinic acid and sodium chloride or ammonium sulfate is determined using a novel approach combining X-ray photoelectron spectroscopy, surface tension measurements and thermodynamic modeling. It is shown that succinic acid molecules are accumulated in the surface, yielding a 10-fold surface concentration as compared with the bulk for saturated succinic acid solutions. Inorganic salts further enhance this enrichment due to competition for hydration in the bulk. The surface compositions for various mixtures are parametrized to yield generalizable results and used to explain changes in surface tension. The enhanced surface partitioning implies an increased maximum solubility of organic compounds in atmospheric nanoparticles. The results can explain observations of size-dependent phase-state of atmospheric nanoparticles, suggesting that these particles can display drastically different behavior than predicted by bulk properties only.

  • 745. Westberg, Håkan
    et al.
    Elihn, Karine
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Andersson, Eva
    Persson, Bodil
    Andersson, Lennart
    Bryngelsson, Ing-Liss
    Karlsson, Cathe
    Sjögren, Bengt
    Inflammatory markers and exposure to airborne particles among workers in a Swedish pulp and paper mill2016In: International Archives of Occupational and Environmental Health, ISSN 0340-0131, E-ISSN 1432-1246, Vol. 89, no 5, p. 813-822Article in journal (Refereed)
    Abstract [en]

    To study the relationship between exposure to airborne particles in a pulp and paper mill and markers of inflammation and coagulation in blood. Personal sampling of inhalable dust was performed for 72 subjects working in a Swedish pulp and paper mill. Stationary measurements were used to study concentrations of total dust, respirable dust, PM10 and PM2.5, the particle surface area and the particle number concentrations. Markers of inflammation, interleukins (IL-1b, IL-6, IL-8, and IL-10), C-reactive protein (CRP), serum amyloid A (SAA), and fibrinogen and markers of coagulation factor VIII, von Willebrand, plasminogen activator inhibitor, and D-dimer were measured in plasma or serum. Sampling was performed on the last day of the work free period of 5 days, before and after the shift the first day of work and after the shifts the second and third day. In a mixed model analysis, the relationship between particulate exposures and inflammatory markers was determined. Sex, age, smoking, and BMI were included as covariates. The average 8-h time-weighted average (TWA) air concentration levels of inhalable dust were 0.30 mg/m(3), range 0.005-3.3 mg/m(3). The proxies for average 8-h TWAs of respirable dust were 0.045 mg/m(3). Significant and consistent positive relations were found between several exposure metrics (PM 10, total and inhalable dust) and CRP, SAA and fibrinogen taken post-shift, suggesting a dose-effect relationship. This study supports a relationship between occupational particle exposure and established inflammatory markers, which may indicate an increased risk of cardiovascular disease.

  • 746. Weyhenmeyer, Gesa A.
    et al.
    Muller, Roger A.
    Norman, Maria
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Uppsala University, Sweden.
    Tranvik, Lars J.
    Sensitivity of freshwaters to browning in response to future climate change2016In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 134, no 1-2, p. 225-239Article in journal (Refereed)
    Abstract [en]

    Many boreal waters are currently becoming browner with effects on biodiversity, fish production, biogeochemical processes and drinking water quality. The question arises whether and at which speed this browning will continue under future climate change. To answer the question we predicted the absorbance (a(420)) in 6347 lakes and streams of the boreal region under future climate change. For the prediction we modified a numerical model for a(420) spatial variation which we tested on a temporal scale by simulating a(420) inter-annual variation in 48 out of the 6347 Swedish waters. We observed that inter-annual a(420) variation is strongly driven by precipitation that controls the water flushing through the landscape. Using the predicted worst case climate scenario for Sweden until 2030, i.e., a 32 % precipitation increase, and assuming a 10 % increase in imports of colored substances into headwaters but no change in land-cover, we predict that a(420) in the 6347 lakes and streams will, in the worst case, increase by factors between 1.1 and 7.6 with a median of 1.3. This increase implies that a(420) will rise from the present 0.1-86 m(-1) (median: 7.3 m(-1)) in the 6347 waters to 0.1-154 m(-1) (median: 10.1 m(-1)), which can cause problems for the preparation of drinking water in a variety of waters. Our model approach clearly demonstrates that a homogenous precipitation increase results in very heterogeneous a(420) changes, where lakes with a long-term mean landscape water retention time between 1 and 3 years are particularly vulnerable to climate change induced browning. Since these lake types are quite often used as drinking water resources, preparedness is needed for such waters.

  • 747. Whaley, Paul
    et al.
    Halsall, Crispin
    Ågerstrand, Marlene
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Aiassa, Elisa
    Benford, Diane
    Bilotta, Gary
    Coggon, David
    Collins, Chris
    Dempsey, Ciara
    Duarte-Davidson, Raquel
    FitzGerald, Rex
    Galay-Burgos, Malyka
    Gee, David
    Hoffmann, Sebastian
    Lam, Juleen
    Lasserson, Toby
    Levy, Len
    Lipworth, Steven
    Ross, Sarah Mackenzie
    Martin, Olwenn
    Meads, Catherine
    Meyer-Baron, Monika
    Miller, James
    Pease, Camilla
    Rooney, Andrew
    Sapiets, Alison
    Stewart, Gavin
    Taylor, David
    Implementing systematic review techniques in chemical risk assessment: Challenges, opportunities and recommendations2016In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 92-93, p. 556-564Article, review/survey (Refereed)
    Abstract [en]

    Systematic review (SR) is a rigorous, protocol-driven approach designed to minimise error and bias when summarising the body of research evidence relevant to a specific scientific question. Taking as a comparator the use of SR in synthesising research in healthcare, we argue that SR methods could also pave the way for a step change in the transparency, objectivity and communication of chemical risk assessments (CRA) in Europe and elsewhere. We suggest that current controversies around the safety of certain chemicals are partly due to limitations in current CRA procedures which have contributed to ambiguity about the health risks posed by these substances. We present an overview of how SR methods can be applied to the assessment of risks from chemicals, and indicate how challenges in adapting SR methods from healthcare research to the CRA context might be overcome. Regarding the latter, we report the outcomes from a workshop exploring how to increase uptake of SR methods, attended by experts representing a wide range of fields related to chemical toxicology, risk analysis and SR Priorities which were identified include: the conduct of CRA-focused prototype SRs; the development of a recognised standard of reporting and conduct for SRs in toxicology and CRA; and establishing a network to facilitate research, communication and training in SR methods. We see this paper as a milestone in the creation of a research climate that fosters communication between experts in CRA and SR and facilitates wider uptake of SR methods into CRA.

  • 748. Wiedensohler, A.
    et al.
    Andrade, M.
    Weinhold, K.
    Mueller, T.
    Birmili, W.
    Velarde, F.
    Moreno, I
    Forno, R.
    Sanchez, M. F.
    Laj, P.
    Ginot, P.
    Whiteman, D. N.
    Krejci, Radovan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Sellegri, K.
    Reichler, T.
    Black carbon emission and transport mechanisms to the free troposphere at the La Paz/El Alto (Bolivia) metropolitan area based on the Day of Census (2012)2018In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 194, p. 158-169Article in journal (Refereed)
    Abstract [en]

    Urban development, growing industrialization, and increasing demand for mobility have led to elevated levels of air pollution in many large cities in Latin America, where air quality standards and WHO guidelines are frequently exceeded. The conurbation of the metropolitan area of La Paz/El Alto is one of the fastest growing urban settlements in South America with the particularity of being located in a very complex terrain at a high altitude. As many large cities or metropolitan areas, the metropolitan area of La Paz/El Alto and the Altiplano region are facing air quality deterioration. Long-term measurement data of the equivalent black carbon (eBC) mass concentrations and particle number size distributions (PNSD) from the Global Atmosphere Watch Observatory Chacaltaya (CHC; 5240 m a.s.l., above sea level) indicated a systematic transport of particle matter from the metropolitan area of La Paz/El Alto to this high altitude station and subsequently to the lower free troposphere. To better understand the sources and the transport mechanisms, we conducted eBC and PNSDs measurements during an intensive campaign at two locations in the urban area of La Paz/El Alto from September to November 2012. While the airport of El Alto site (4040 m a.s.l.) can be seen as representative of the urban and Altiplano background, the road site located in Central La Paz (3590 m a.s.l.) is representative for heavy traffic-dominated conditions. Peaks of eBC mass concentrations up to 5 mu g m(-3) were observed at the El Alto background site in the early morning and evening, while minimum values were detected in the early afternoon, mainly due to thermal convection and change of the planetary boundary layer height. The traffic-related eBC mass concentrations at the road site reached maximum values of 10-20 mu g m(-3). A complete traffic ban on the specific Bolivian Day of Census (November 21, 2012) led to a decrease of eBC below 1 mu g m(-3) at the road site for the entire day. Compared to the day before and after, particle number concentrations decreased by a factor between 5 and 25 over the particle size range from 10 to 800 nm, while the submicrometer particle mass concentration dropped by approximately 80%. These results indicate that traffic is the dominating source of BC and particulate air pollution in the metropolitan area of La Paz/El Alto. In general, the diurnal cycle of eBC mass concentration at the Chacaltaya observatory is anti-correlated to the observations at the El Alto background site. This pattern indicates that the traffic-related particulate matter, including BC, is transported to higher altitudes with the developing of the boundary layer during daytime. The metropolitan area of La Paz/El Alto seems to be a significant source for BC of the regional lower free troposphere. From there, BC can be transported over long distances and exert impact on climate and composition of remote southern hemisphere.

  • 749. Wiese, Jutta
    et al.
    Abdelmohsen, Usama Ramadan
    Motiei, Asa
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany.
    Humeida, Ute Hentschel
    Imhoff, Johannes F.
    Bacicyclin, a new antibacterial cyclic hexapeptide from Bacillus sp strain BC028 isolated from Mytilus edulis2018In: Bioorganic & Medicinal Chemistry Letters, ISSN 0960-894X, E-ISSN 1090-2120, Vol. 28, no 4, p. 558-561Article in journal (Refereed)
    Abstract [en]

    A new cyclic hexapeptide, cyclo-(Gly-Leu-Val-IIe-Ala-Phe), named bacicyclin (1), was isolated from a marine Bacillus sp. strain associated with Mytilus edulis. The sequences of the amino acid building blocks of the cyclic peptide and its structure were determined by 1D- and 2D-NMR techniques. Marfey's analysis showed that the amino acid building blocks had L-configuration in all cases except for alanine and phenylalanine, which had D-configuration. Bacicyclin (1) exhibited antibacterial activity against the clinically relevant strains Enterococcus faecalis and Staphylococcus aureus with minimal inhibitory concentration values of 8 and 12 mu M, respectively. These results demonstrate the potential of marine bacteria as a promising source for the discovery of new antibiotics.

  • 750. Wikström, Sverre
    et al.
    Lindh, Christian H.
    Shu, Huan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Karlstad University, Sweden.
    Bornehag, Carl-Gustaf
    Early pregnancy serum levels of perfluoroalkyl substances and risk of preeclampsia in Swedish women2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 9179Article in journal (Refereed)
    Abstract [en]

    Preeclampsia is a major cause of maternal and fetal morbidity. Emerging research shows an association with environmental exposures. The present aim was to investigate associations between early pregnancy serum levels of perfluoroalkyl substances (PFAS) and preeclampsia. Within the Swedish SELMA study, eight PFAS were measured at median 10 gestational weeks and cases of preeclampsia were postnatally identified from registers. Associations between individual PFAS and preeclampsia were assessed, adjusting for parity, age, weight and smoking. Out of 1,773 women in the study group, 64 ( 3.6%), developed preeclampsia. A doubling of PFOS and PFNA exposure, corresponding to an inter-quartile increase, was associated with an increased risk for preeclampsia of about 38-53% respectively. Serum PFOS within the highest quartile was associated with an odds ratio of 2.68 ( CI 95%: 1.17-6.12), equal to the increased risk associated with nulliparity, when compared to exposure in the first quartile. The same associations were identified, although with higher risk estimates, in analyses restricted to nulliparous women. For other PFAS, there were no associations. In conclusion and consistent with limited previous research only on PFOS, increasing serum levels of PFOS and PFNA during early pregnancy were associated with a clinically relevant risk of preeclampsia, adjusting for established confounders.

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