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Modelling inorganic Aluminium with WHAM in environmental monitoring
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
2007 (English)In: APPLIED GEOCHEMISTRY, ISSN 0883-2927, Vol. 22, 1196-1201 p.Article in journal (Refereed) Published
Abstract [en]

Due to the varying toxicity of different Al species, information about Al concentration and speciation is important when assessing water quality. Modelling Al speciation can support operational monitoring programmes where Al speciation is not measured directly. Modelling also makes it possible to retroactively speciate older samples where laboratory fractionation was not undertaken. Organic-rich waters are a particular challenge for both laboratory analysis and models. This paper presents the modelling of Al speciation in Swedish surface waters using the Windermere Humic Acid Model (WHAM). The model was calibrated with data from operational monitoring, the Swedish national survey of lakes and rivers, and covers a broad spectrum of physical and chemical conditions. Calibration was undertaken by varying the amount of DOC active in binding Al. A sensitivity analysis identified the minimum parameters required as model input variables primarily to be total Al, organic C, pH, F-, and secondly Fe, Ca and Mg. The observed and modelled Ali had no significant differences (Spearman rank, p < 0.01), however, lake samples modelled better than rivers. Samples were placed in the correct toxicological category in 89-95% of the cases. The importance of the size of the calibration data set was assessed, and reducing the calibration data set resulted in poorer correlations, but had little impact on the toxicological placement. Overall, the modelling gave satisfactory results from samples covering a broad spectrum of physical and chemical conditions. This indicates the potential value of WHAM as a tool in operational monitoring of surface waters.

Place, publisher, year, edition, pages
2007. Vol. 22, 1196-1201 p.
Keyword [en]
Environmental science
National Category
Geophysics Geochemistry
URN: urn:nbn:se:su:diva-11073DOI: 10.1016/j.apgeochem.2007.03.011ISI: 000248070200014OAI: diva2:177592
Available from: 2008-01-09 Created: 2008-01-09 Last updated: 2012-09-26Bibliographically approved
In thesis
1. Toxicity of Inorganic Aluminium in Humic Streams
Open this publication in new window or tab >>Toxicity of Inorganic Aluminium in Humic Streams
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Aluminium (Al) has been recognised as a main toxic factor alongside pH in acidified water ecosystems. The toxic effect of Al has been attributed to inorganic Al (Ali), though there are few in situ studies in ambient humic waters which are the focus of this thesis.

The aim was to estimate Ali toxicity and thus also Ali concentrations in Swedish humic streams. Subsequently it is necessary to analyse Ali correctly, which was studied by modelling and method intercalibrations. The hypothesis was that the effect of Ali could be followed via physiological effects and Al accumulation, as well as by mortality. Toxicity was studied by in stream exposures of brown trout (Salmo trutta L.) and two salmonid prey organisms (Gammarus pulex and Baetis rhodani) during spring flood.

The modelling of the Ali fraction was performed using monitoring data covering all of Sweden with satisfactory results. The essential variables for Ali modelling were determined; Al, DOC, pH and F, while Fe, Ca and Mg had less effect. The automated analytical procedure for Ali (with cation exchange followed by complexation with pyrocatechol violet) was modified and validated and showed to be the preferred method for laboratory analyses.

To avoid detrimental effects for brown trout Ali should be <20 µg/L and pH >5.0; mortality was high when the Ali was above 50 µg/L. The invertebrates were more sensitive, as mortalities occurred at pH <6.0 and Ali >15 µg/L for G. pulex, and at pH <5.7 and Ali >20 µg/L for B. rhodani. It is prudent to use a wide view and let the most sensitive species set the tolerance limits; a pH above 5.7-6.0 and Ali below 15-20 µg/L allows the stream ecosystems to thrive.

Today, as waters are recovering from acidification, the aim of mitigating liming is to carefully adjust dosage to avoid suboptimal water quality. The thresholds found in this thesis can be used to efficiently but carefully decrease liming, as both Ali and pH levels have to be balanced to sustain the recovering aquatic biota.

Place, publisher, year, edition, pages
Stockholm: Department of Applied Environmental Science (ITM), Stockholm University, 2012. 42 p.
Inorganic Al, toxicity, acidification, humic streams
National Category
Environmental Sciences
Research subject
Applied Environmental Science
urn:nbn:se:su:diva-80651 (URN)978-91-7447-577-7 (ISBN)
Public defence
2012-10-26, De Geer Salen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:00 (Swedish)
Available from: 2012-10-04 Created: 2012-09-25 Last updated: 2012-09-25Bibliographically approved

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Andrén, Cecilia M
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