Change search
Refine search result
1 - 11 of 11
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Bröder, Lisa
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Tesi, Tommaso
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. CNR-National Research Council of Italy, ISMAR-Marine Sciences Institute, Italy.
    Andersson, August
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Eglinton, Timothy I.
    Semiletov, Igor P.
    Dudarev, Oleg V.
    Roos, Per
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Historical records of organic matter supply and degradation status in the East Siberian Sea2016In: Organic Geochemistry, ISSN 0146-6380, E-ISSN 1873-5290, Vol. 91, p. 16-30Article in journal (Refereed)
    Abstract [en]

    Destabilization and degradation of permafrost carbon in the Arctic regions could constitute a positive feedback to climate change. A better understanding of its fate upon discharge to the Arctic shelf is therefore needed. In this study, bulk carbon isotopes as well as terrigenous and marine biomarkers were used to construct two centennial records in the East Siberian Sea. Differences in topsoil and Pleistocene Ice Complex Deposit permafrost concentrations, modeled using delta C-13 and Delta C-14, were larger between inner and outer shelf than the changes over time. Similarly, lignin-derived phenol and cutin acid concentrations differed by a factor of ten between the two stations, but did not change significantly over time, consistent with the dual-carbon isotope model. High molecular weight (HMW) n-alkane and n-alkanoic acid concentrations displayed a smaller difference between the two stations (factor of 3-6). By contrast, the fraction for marine OC drastically decreased during burial with a half-life of 19-27 years. Vegetation and degradation proxies suggested supply of highly degraded gymnosperm wood tissues. Lipid Carbon Preference Index (CPI) values indicated more extensively degraded HMW n-alkanes on the outer shelf with no change over time, whereas n-alkanoic acids appeared to be less degraded toward the core top with no large differences between the stations. Taken together, our results show larger across-shelf changes than down-core trends. Further investigation is required to establish whether the observed spatial differences are due to different sources for the two depositional settings or, alternatively, a consequence of hydrodynamic sorting combined with selective degradation during cross-shelf transport.

  • 2.
    Bröder, Lisa
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Tesi, Tommaso
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. Institute of Marine Sciences - National Research Council, Italy.
    Andersson, August
    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.
    Bounding cross-shelf transport time and degradation in Siberian-Arctic land-ocean carbon transfer2018In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, article id 806Article in journal (Refereed)
    Abstract [en]

    The burial of terrestrial organic carbon (terrOC) in marine sediments contributes to the regulation of atmospheric CO2 on geological timescales and may mitigate positive feedback to present-day climate warming. However, the fate of terrOC in marine settings is debated, with uncertainties regarding its degradation during transport. Here, we employ compound-specific radiocarbon analyses of terrestrial biomarkers to determine cross-shelf transport times. For the World's largest marginal sea, the East Siberian Arctic shelf, transport requires 3600 +/- 300 years for the 600 km from the Lena River to the Laptev Sea shelf edge. TerrOC was reduced by similar to 85% during transit resulting in a degradation rate constant of 2.4 +/- 0.6 kyr(-1). Hence, terrOC degradation during cross-shelf transport constitutes a carbon source to the atmosphere over millennial time. For the contemporary carbon cycle on the other hand, slow terrOC degradation brings considerable attenuation of the decadal-centennial permafrost carbon-climate feedback caused by global warming.

  • 3. Cathalot, C.
    et al.
    Rabouille, C.
    Tisnerat-Laborde, N.
    Toussaint, F.
    Kerherve, P.
    Buscail, R.
    Loftis, K.
    Sun, M. -Y
    Tronczynski, J.
    Azoury, S.
    Lansard, B.
    Treignier, C.
    Pastor, L.
    Tesi, Tommaso
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    The fate of river organic carbon in coastal areas: A study in the Rhone River delta using multiple isotopic (delta C-13, Delta C-14) and organic tracers2013In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 118, p. 33-55Article in journal (Refereed)
    Abstract [en]

    A significant fraction of the global carbon flux to the ocean occurs in River-dominated Ocean Margins (RiOMar) although large uncertainties remain in the cycle of organic matter (OM) in these systems. In particular, the OM sources and residence time have not been well clarified. Surface (0-1 cm) and sub-surface (3-4 cm) sediments and water column particles (bottom and intermediate depth) from the Rhone River delta system were collected in June 2005 and in April 2007 for a multi-proxy study. Lignin phenols, black carbon (BC), proto-kerogen/BC mixture, polycyclic aromatic hydrocarbons (PAHs), carbon stable isotope (delta C-13(OC)), and radiocarbon measurements (delta C-14(OC)) were carried out to characterize the source of sedimentary organic material and to address degradation and transport processes. The bulk OM in the prodelta sediment appears to have a predominantly modern terrigenous origin with a significant contribution of modern vascular C-3 plant detritus (Delta C-14(OC) = 27.9 parts per thousand, delta C-13(OC) = -27.4 parts per thousand). In contrast, the adjacent continental shelf, below the river plume, seems to be dominated by aged OM (Delta C-14(OC) = -400 parts per thousand, delta C-13(OC) = -24.2 parts per thousand), and shows no evidence of dilution and/or replacement by freshly produced marine carbon. Our data suggest an important contribution of black carbon (50% of OC) in the continental shelf sediments. Selective degradation processes occur along the main dispersal sediment system, promoting the loss of a modern terrestrial OM but also proto-kerogen-like OM. In addition, we hypothesize that during the transport across the shelf, a long term resuspension/deposition loop induces efficient long term degradation processes able to rework such refractory-like material until the OC is protected by the mineral matrix of particles.

  • 4.
    Karlsson, Emma
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Gelting, Johan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Tesi, Tommaso
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    van Dongen, Bart
    Semiletov, Igor
    Charkin, Alexander
    Dudarev, Oleg
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Different sources and degradation state of dissolved, particulate and sedimentary organic matter along the Eurasian Arctic coastal marginManuscript (preprint) (Other academic)
    Abstract [en]

    Thawing of permafrost in the Eurasian Arctic causes massive fluvial and erosional releases of both dissolved and particulate organic carbon (DOC and POC) to coastal waters. Here we investigate how different sources and extent of degradation of remobilized terrestrial carbon pools imprint on major recipient carbon pools and thereby affect large-scale carbon cycling.  The molecular and dual-isotope composition is compared with source end-member composition in waterborne high-molecular weight DOC (>1kD, a.k.a. colloidal OC), POC and in sedimentary OC (SOC) along coastal Kara, Laptev and East Siberian Seas.

    The lignin phenol fingerprint demonstrates a clear geospatial trend in the relative contribution of different terrestrial sources to coastal OC in going from the west to the east.  The wax lipids and cutins were much less abundant in the COC compared to in the POC and SOC compartment, suggesting that different terrestrial carbon pools partition into different aquatic carrier phases.  The Δ14C signal suggests that the COC is overwhelmingly derived from contemporary carbon sources. Furthermore, degradation proxies based on terrestrial lignin phenol biomarkers suggest a highly degraded COC composition. Monte Carlo based source apportionment simulations of the δ13C/Δ14C composition constrained that the COC is dominated by terrestrial OC from topsoil permafrost (65%) and marine plankton (25%) with smaller contribution from Ice Complex Deposit (ICD) and other older stocks of permafrost carbon (9%). This contrasts starkly to the POC and especially the SOC compartment, which are dominated by old C from ICD-OC permafrost.

    These results combine with other recent studies to suggest a pattern along the East Siberian Arctic margin of SOC being constantly older yet less degraded than water column POC. This study also extends this perspective spatially along the Eurasian Arctic seaboard and also to the large COC (HMW DOC) pool, which is even younger yet even more degraded than the POC. An implication is that DOC and POC pools need to be treated separately in assessments of effects on the large-scale carbon cycle (and climate feedback) of old carbon released from thawing permafrost to aquatic receptors across the Eurasian Arctic coast. 

  • 5.
    Karlsson, Emma S.
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Bruchert, Volker
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Tesi, Tommaso
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Charkin, A.
    Dudarev, O.
    Semiletov, I.
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Contrasting regimes for organic matter degradation in the East Siberian Sea and the Laptev Sea assessed through microbial incubations and molecular markers2015In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 170, p. 11-22Article in journal (Refereed)
    Abstract [en]

    Compositional studies of organic matter on the East Siberian Arctic Shelf (ESAS) suggest that different terrestrial carbon pools have different propensities for transport and/or degradation. The current study combined laboratory-based microbial degradation experiments with earlier published degradation-diagnostic composition of several classes of terrestrial biomarkers on the same sediments to investigate differences and driving forces of terrestrial organic matter (TerrOM) degradation in two biogeochemically-contrasting regimes of the ESAS. The incubation-based anaerobic degradation rates were consistently higher (by average factor of 6) in the East Siberian Sea Kolyma Paleoriver Channel (ESS-KPC) (15 mu mol CO2 g OC-1 day(-1)) compared to the Laptev Sea Buor-Khaya Bay (LS-BKB) (2.4 mu mol CO2 g OC-1 day(-1)). The reported molecular markers show similarities between the terrestrial carbon pools in the two systems, but impose contrasting degradation regimes in combination with the incubation results. For the LS-BKB, there was a strong relationship between the degradation rates and the three lignin phenol-based degradation proxies (r(2) = 0.93-0.96, p < 0.01, linear regression) and two wax lipid-based degradation proxies (r(2) = 0.71 and 0.66, p < 0.05, linear regression). In contrast, for the ESS-KPC system, there was no relationship between incubation-based degradation rates and molecular marker-based degradation status of TerrOM. A principal component analysis indicated that short-chain fatty acids and dicarboxylic acids from CuO oxidation are mainly of terrestrial origin in the LS-BKB, but mainly of marine origin in the ESS-KPC. Hence, the microbial degradation in the western (LS-BKB) system appears to be fueled by TerrOM whereas the eastern (ESS-KPC) system degradation appears to be driven by MarOM. By combining molecular fingerprinting of TerrOM degradation state with laboratory-based degradation studies on the same ESAS sediments, a picture evolves of two distinctly different modes of TerrOM degradation in different parts of the ESAS system.

  • 6.
    Martens, Jannik
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Wild, Birgit
    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.
    Tesi, Tommaso
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry. National Research Council, Italy.
    Andersson, August
    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. Vrije Universiteit Amsterdam, Netherlands,.
    O'Regan, Matt
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Jakobsson, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Sköld, Martin
    Stockholm University, Faculty of Science, Department of Mathematics.
    Gemery, Laura
    Cronin, Thomas M.
    Semiletov, Igor
    Dudarev, Oleg V.
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Remobilization of Old Permafrost Carbon to Chukchi Sea Sediments During the End of the Last Deglaciation2019In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 33, no 1, p. 2-14Article in journal (Refereed)
    Abstract [en]

    Climate warming is expected to destabilize permafrost carbon (PF-C) by thaw-erosion and deepening of the seasonally thawed active layer and thereby promote PF-C mineralization to CO2 and CH4. A similar PF-C remobilization might have contributed to the increase in atmospheric CO2 during deglacial warming after the last glacial maximum. Using carbon isotopes and terrestrial biomarkers (Delta C-14, delta C-13, and lignin phenols), this study quantifies deposition of terrestrial carbon originating from permafrost in sediments from the Chukchi Sea (core SWERUS-L2-4-PC1). The sediment core reconstructs remobilization of permafrost carbon during the late Allerod warm period starting at 13,000 cal years before present (BP), the Younger Dryas, and the early Holocene warming until 11,000 cal years BP and compares this period with the late Holocene, from 3,650 years BP until present. Dual-carbon-isotope-based source apportionment demonstrates that Ice Complex Deposit-ice- and carbon-rich permafrost from the late Pleistocene (also referred to as Yedoma)-was the dominant source of organic carbon (66 +/- 8%; mean +/- standard deviation) to sediments during the end of the deglaciation, with fluxes more than twice as high (8.0 +/- 4.6 g.m(-2).year(-1)) as in the late Holocene (3.1 +/- 1.0 g.m(-2).year(-1)). These results are consistent with late deglacial PF-C remobilization observed in a Laptev Sea record, yet in contrast with PF-C sources, which at that location were dominated by active layer material from the Lena River watershed. Release of dormant PF-C from erosion of coastal permafrost during the end of the last deglaciation indicates vulnerability of Ice Complex Deposit in response to future warming and sea level changes.

  • 7. Panova, Elena V.
    et al.
    Ruban, Alexey S.
    Dudarev, Oleg V.
    Tesi, Tommaso
    Brooder, Lisa
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Grinko, Andrey A.
    Shakhova, Natalia E.
    Goncharov, Ivan V.
    Mazurov, Alexey K.
    Semiletov, Igor P.
    ЛИТОЛОГИЧЕСКИЕ ОСОБЕННОСТИ ДОННЫХ ОСАДКОВ И ИХ ВЛИЯНИЕ НА РАСПРЕДЕЛЕНИЕОРГАНИЧЕСКОГО МАТЕРИАЛА НА ТЕРРИТОРИИ ВОСТОЧНО|СИБИРСКОГО ШЕЛЬФА [Lithological features of surface sediment and their influence on organic matter distribution across the East-Siberian Arctic shelf]2017In: Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, ISSN 2500-1019, Vol. 328, no 8, p. 94-105Article in journal (Refereed)
    Abstract [ru]

    The Arctic is undergoing rapid climate change, which affects the global and regional carbon cycles. The East Siberian Arctic shelf, that is believed to store huge amounts of organic carbon in different pools, has been the subject of growing scientific interest in recent decades. The aim of the work was to study the lithological features of bottom sediments on the East Siberian Arctic shelf and to assess their influence on the spatial distribution of organic material in the study area. Materials and methods. The sediment samples were collected during the 45-day multidisciplinary SWERUS-C3 expedition on IB ODEN in summer 2014. Surface sediments from inner and middle East Siberian Arctic shelf were collected in summer 2008 during the International Siberian Shelf Study (ISSS-08) campaign onboard the HV Yakob Smirnitsky. The samples were analyzed for the grain size and specific surface area characteristics and total organic carbon content. It is shown that the subglacial sedimentation and the accumulation of predominantly fine-grained sediments prevail within the study area. Nevertheless, atypical sand zones were identified on the outer shelf. The authors have suggested several external factors, including modern and paleo ice scouring in the early Holocene, and intensive gas venting, which are accompanied by removal of fine-grained sediments. The paper considers spatial distribution of organic matter in the bottom sediments of the East Siberian Arctic shelf and its interrelation with their lithological properties.

  • 8. Pasqual, Catalina
    et al.
    Goni, Miguel A.
    Tesi, Tommaso
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Sanchez-Vidal, Anna
    Calafat, Antoni
    Canals, Miguel
    Composition and provenance of terrigenous organic matter transported along submarine canyons in the Gulf of Lion (NW Mediterranean Sea)2013In: Progress in Oceanography, ISSN 0079-6611, Vol. 118, no SI, p. 81-94Article, review/survey (Refereed)
    Abstract [en]

    Previous projects in the Gulf of Lion have investigated the path of terrigenous material in the Rhone deltaic system, the continental shelf and the nearby canyon heads. This study focuses on the slope region of the Gulf of Lion to further describe particulate exchanges with ocean's interior through submarine canyons and atmospheric inputs. Nine sediment traps were deployed from the heads to the mouths of Lacaze-Duthiers and Cap de Creus submarine canyons and on the southern open slope from October 2005 to October 2006. Sediment trap samples were analyzed by CuO oxidation to investigate spatial and temporal variability in the yields and compositional characteristics of terrigenous biomarkers such as ligninderived phenols and cutin acids. Sediment trap data show that the Dense Shelf Water Cascading event that took place in the months of winter 2006 (January, February and March) had a profound impact on particle fluxes in both canyons. This event was responsible for the majority of lignin phenol (55.4%) and cutin acid (42.8%) inputs to submarine canyons, with lignin compositions similar to those measured along the mid- and outer-continental shelf, which is consistent with the resuspension and lateral transfer of unconsolidated shelf sediment to the canyons. The highest lithogenic-normalized lignin derived phenols contents in sediment trap samples were found during late spring and summer at all stations (i.e., 193.46 mu g VP g(-1) lithogenic at deep slope station), when river flow, wave energy and total particle fluxes were relatively low. During this period, lignin compositions were characterized by elevated cinnamyl to vanillyl phenol ratios (>3) at almost all stations, high p-coumaric to ferulic acid ratios (>3) and high yields of cutin acids relative to vanillyl phenols (>1), all trends that are consistent with high pollen inputs. Our results suggest marked differences in the sources and transport processes responsible for terrigenous material export along submarine canyons, mainly consisting of fluvial and shelf sediments during winter and atmospheric dust inputs during spring and summer.

  • 9.
    Tesi, Tomaso
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Miserocchi, S.
    Acri, F.
    Langone, L.
    Boldrin, A.
    Hatten, J. A.
    Albertazzi, S.
    Flood-driven transport of sediment, particulate organic matter, and nutrients from the Po River watershed to the Mediterranean Sea2013In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 498, p. 144-152Article in journal (Refereed)
    Abstract [en]

    The Po River (Northern Italy) discharge represents a considerable input of the land-derived material entering the Mediterranean Sea. Most of its particulate and dissolved constituents are supplied to the sea in response to short-lived climate events. Although these floods exert first-order control on the transport of organic and inorganic elements, both composition and magnitude of the river material are poorly constrained during high discharge periods. In order to fill this knowledge gap, in this study we carried out an event response sampling in the Po River in November 2011. Beginning in early November, intense rainfall occurred in the Po watershed that resulted in a flood of similar to 6000 m(3) s(-1) year return period). Water samples were collected from the river before and during the flood. Dissolved nitrate, nitrite, ammonia, and silicate were measured and the particulate material was analyzed for total suspended sediment, elemental composition, delta C-13, delta N-15, grain-size, and Cs-137 activity. Our results showed a temporal decoupling between solid and water discharge implying that predicted sediment loads simply derived from sediment rating curves could potentially give rise to large errors, especially when calculations are used to understand the sediment export in response short-lived events. The suspended organic material during high flow was dominated by soil organic matter while high delta N-15 indicated the influence of an additional N-15-enriched source (e.g., manure, sewage, and algal biomass) during low discharge. Because the concentrations of nitrite and ammonia were positively correlated with the content of particulate material in suspension, we inferred that nitrite and ammonia concentrations were driven by either bacteria activity (ammonification-nitrification) or ionic exchange whose rates were proportional to concentration of the suspended material. In addition, due to the dilution with nitrate-poor rainfall, the concentration of nitrate decreased with increasing water discharge. High concentrations of nitrate were instead attributable to the influx of nitrate-rich water from groundwater that is chronically contaminated and constitutes most of the baseflow during low flow. Our results indicate that the event-dominated transport in the Po drainage basin is particularly important for the organic matter supply as flood events account for at least one-third of the particulate annual export (organic carbon and nitrogen). Finally, this study has demonstrated the utility of event-response sampling for understanding the importance of event-dominated transport in rivers.

  • 10.
    Tesi, Tommaso
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Langone, L.
    Giani, M.
    Ravaioli, M.
    Miserocchi, S.
    Source, diagenesis, and fluxes of particulate organic carbon along the western Adriatic Sea (Mediterranean Sea)2013In: Marine Geology, ISSN 0025-3227, E-ISSN 1872-6151, Vol. 337, p. 156-170Article in journal (Refereed)
    Abstract [en]

    In this study, we investigated the modern organic carbon (OC) cycling along the clinoform-shaped deposit that developed after the attainment of the modern sea-level in the Adriatic Sea (similar to 5.5 kyr cal BP). Newly acquired data were combined with published results to characterize the (i) origin, (ii) diagenesis, and (iii) fluxes of OC along the Adriatic clinoform. delta C-13, Delta C-14, and lignin phenols were used to constrain the composition of CC accumulating in surface sediments. Sediment cores collected at different water depths were used to describe the early diagenesis during burial in different regions. In addition, on the basis of an extensive number of accumulation rates and CC data, we assessed the flux of CC to the seabed and its burial. Our results showed that terrigenous CC is the dominant CC source in the Po prodelta mainly in the form of pre-aged soil-derived CC and vascular plant fragments. Along the clinoform, both Delta 14C and the concentration of lignin-derived phenols decreased with increasing distance from the Po prodelta indicating the influence of an additional pool of aged CC that gradually becomes more important because of its selective preservation during the sediment transport. As a result, degradation rates (k) decreased along the clinoform as a function of the sediment oxidative history. The calculated half-life of reactive OC (t(1/2)) was similar to 14.6 yrs in the Po prodelta whereas topset/forest deposits south of this region exhibited higher values, similar to 100 yrs, indicating the presence of refractory material. In the distal bottomset region, the tip was particularly high ranging from similar to 255 to similar to 912 yrs. Because of the significant southward component of the sediment transport, the CC deposition in the southern surface sediments exceeded the local CC input via rivers (ratio deposition/input 12). Conversely, the northern Adriatic was characterized by a marked imbalance (ratio deposition/input 0.3-0.5). According to our calculations, the CC flux to the seabed along the clinoform was similar to 309 Gg of C per year whereas the OC burial was similar to 180 Gg of C per year, corresponding to an overall burial efficiency of similar to 59%.

  • 11.
    Tesi, Tommaso
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Semiletov, Igor
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Dudarev, Oleg
    Kuhry, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Gustafsson, Örjan
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Composition and fate of terrigenous organic matter along the Arctic land-ocean continuum in East Siberia: Insights from biomarkers and carbon isotopes2014In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 133, p. 235-256Article in journal (Refereed)
    Abstract [en]

    Climate warming is predicted to translocate terrigenous organic carbon (TerrOC) to the Arctic Ocean and affect the marine biogeochemistry at high latitudes. The magnitude of this translocation is currently unknown, so is the climate response. The fate of the remobilized TerrOC across the Arctic shelves represents an unconstrained component of this feedback. The present study investigated the fate of permafrost carbon along the land-ocean continuum by characterizing the TerrOC composition in three different terrestrial carbon pools from Siberian permafrost (surface organic rich horizon, mineral soil active layer, and Ice Complex deposit) and marine sediments collected on the extensive East Siberian Arctic Shelf (ESAS). High levels of lignin phenols and cutin acids were measured in all terrestrial samples analyzed indicating that these compounds can be used to trace the heterogeneous terrigenous material entering the Arctic Ocean. In ESAS sediments, comparison of these terrigenous biomarkers with other TerrOC proxies (bulk delta C-13/delta C-14 and HMW lipid biomarkers) highlighted contrasting across-shelf trends. These differences could indicate that TerrOC in the ESAS is made up of several pools that exhibit contrasting reactivity toward oxidation during the transport. In this reactive spectrum, lignin is the most reactive, decreasing up to three orders of magnitude from the inner-to the outer-shelf while the decrease of HMW wax lipid biomarkers was considerably less pronounced. Alternatively, degradation might be negligible while sediment sorting during the across-shelf transport could be the major physical forcing that redistributes different TerrOC pools characterized by different matrix-association. Despite the marked decrease shown by lignin, the fingerprint of lignin phenols such as the acid: aldehyde ratio of vanillyl and syringyl phenols showed a lack of any across-shelf trends and exhibited an extremely wide range of values in all terrestrial samples. By contrast, the 3,5-dihydroxybenzoic: vanillyl phenols ratio exhibited a clear across-shelf trend suggesting either increasing degradation with distance from the coast or TerrOC sorting along the sediment dispersal system. The ratio of syringyl: vanillyl phenols indicated that gymnosperm tissues are more important than angiosperm tissues in surface sediments, in particular off the Lena River mouth, consistent with the vegetation in its watershed. Conversely, the fingerprint of p-hydroxybenzenes suggests lack of substantial input of moss-derived material. Finally, autochthonous lipid-and protein-derived CuO reaction products displayed a strong along-shelf gradient likely reflecting the inflow of nutrient-rich Pacific waters from the Bering Strait that stimulate primary productivity in the eastern ESAS. In particular short-chain fatty acids showed a clear frontal/transition zone between Pacific-influenced and river-influenced waters approximately along the 160 degrees E longitude. Considering the labile nature of phytoplankton, priming and co-metabolism processes might stimulate degradation of TerrOC in the easternmost region of the Siberian shelf. This study demonstrated the need to consider multiple TerrOC proxies at isotopic/molecular levels to differentiate the fate for different allocthonous components in Arctic sediments and the need to assess how these TerrOC pools are distributed in different density, size, and settling fractions to better discriminate between the extent of hydrodynamic sorting versus degradation.

1 - 11 of 11
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf