Rates and processes affecting As speciation and mobility in lake sediments during aging
| Autor: | Dirk Wallschläger, Nelson Belzile, Céline Guéguen, Graeme Spiers, Alan Lock |
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| Rok vydání: | 2016 |
| Předmět: |
Geologic Sediments
Environmental Engineering Goethite 010504 meteorology & atmospheric sciences Inorganic chemistry Iron oxide Oxide chemistry.chemical_element Fractionation 010501 environmental sciences Chemical Fractionation 01 natural sciences Arsenic chemistry.chemical_compound Oxidizing agent Environmental Chemistry 0105 earth and related environmental sciences General Environmental Science Arsenite General Medicine Amorphous solid Lakes chemistry visual_art visual_art.visual_art_medium Water Pollutants Chemical Environmental Monitoring |
| Zdroj: | Journal of environmental sciences (China). 66 |
| ISSN: | 1001-0742 |
| Popis: | Sediments from an arsenic (As) contaminated groundwater vent site were used to investigate As(III) binding, transformation and redistribution in native and iron oxide amended lake sediments using aging spiked batch reactions and a sequential extraction procedure that maintains As(V) and As(III) speciation. In the native sediments, fractionation analysis revealed that 10% of the spiked As(III) remained intact after a 32-day aging experiment and was predominantly adsorbed to the strongly sorbed (NH4H2PO4 extractable) and amorphous Fe oxide bound (H3PO4 extractable) fractions. Kinetic modelling of the experimental results allowed identifying the dominant reaction path for depletion of dissolved As(III) to As(III) absorbed on to the solid phase, followed by oxidation in the solid phase. Arsenite was initially adsorbed primarily to the easily exchangeable fraction ((NH4)2SO4 extractable), then rapidly transformed into As(V) and redistributed to the strongly sorbed and amorphous Fe oxide bound fractions. Oxidation of As(III) in recalcitrant fractions was less efficient. The iron oxide amendments illustrated the controls that iron oxides can have on As(III) binding and transformation rates. In goethite amended samples As(III) oxidation was faster and primarily occurred in the strongly sorbed and amorphous Fe oxide bound fractions. In these samples, 19.3μg Mn was redistributed (compared to the native sediment) from the easily exchangeable and crystalline Fe oxide bound fractions to the strongly sorbed and amorphous Fe oxide bound fractions, indicating that goethite may act as a catalyst for Mn(II) oxidation, thereby producing sorbed Mn(III/IV), which then appears to be involved in rapidly oxidizing As(III). |
| Databáze: | OpenAIRE |
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