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Published on: May 27, 2022
Selenium speciation in whole sediment using X-ray absorption spectroscopy and micro X-ray fluorescence imaging
Cheryl I E Wiramanaden1, Karsten Liber, Ingrid J Pickering
1Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Environmental Science & Technology
|June 26, 2010
Summary
Elemental selenium, a major component of lake sediments, is insoluble and not bioavailable. Dissolved selenium in pore water correlates with sediment selenite, influenced by sand content.
Area of Science:
- Environmental Science
- Geochemistry
- Ecotoxicology
Background:
- Freshwater lakes in Canada's Athabasca Basin receive selenium-rich effluent from metal mining.
- Selenium contamination poses risks to aquatic ecosystems and higher trophic levels.
Purpose of the Study:
- To link selenium speciation in lake sediments to environmental factors.
- To assess selenium bioavailability to benthic macroinvertebrates.
Main Methods:
- Field survey of lake sediments, pore water, surface water, and chironomid larvae.
- Selenium speciation analysis using synchrotron-based selenium K-edge X-ray absorption spectroscopy (XAS).
- Confirmation of elemental selenium and metal selenides using extended X-ray absorption fine structure (EXAFS) and micro X-ray fluorescence (XRF) imaging.
Main Results:
- Elemental selenium (approx. 50%) was prevalent in all lake sediments, exhibiting low solubility and bioavailability.
- Inorganic metal selenides were identified in whole sediment samples.
- Dissolved selenium in pore water correlated with sediment selenite, dependent on sediment sand content.
Conclusions:
- Elemental selenium is a stable, non-bioavailable form in these lake sediments.
- Sediment sand content influences selenium speciation and pore water dissolved selenium concentrations.
- Understanding selenium speciation is crucial for assessing ecological risk in mining-affected aquatic systems.
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