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Hydrological and biogeochemical controls governing the speciation and accumulation of selenium in a wetland influenced by mine drainage
Author(s) -
Martin Alan J.,
Fraser Colin,
Simpson Stephanie,
Belzile Nelson,
Chen Y.W.,
London Jacqueline,
Wallschläger Dirk
Publication year - 2018
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.4123
Subject(s) - biogeochemical cycle , environmental chemistry , genetic algorithm , water column , hydrology (agriculture) , chemistry , selenate , selenium , dry weight , water quality , zoology , geology , ecology , agronomy , biology , geotechnical engineering , organic chemistry
Controls governing the speciation and accumulation of Se in a 3.7‐ha marsh influenced by mine drainage were assessed through examination of water balance, water quality, sediment, and plant tissue components. Over the 8‐mo study period (April through November, 2009), mean monthly flows ranged from 1600 to 2300 m 3 d −1 (hydraulic retention time of 1–3 d). Total Se concentrations in the marsh outflow were lower than the inflow by 0.4 to 6.2 μg L −1 (mean difference = 3.3 μg L −1 ), illustrating Se removal. The Se accumulation pathways are illustrated by elevated concentrations of Se in sediments (3–35 mg kg −1 dry wt) as well as in below‐ground (2–41 mg kg −1 dry wt; mean = 10 mg kg −1 dry wt) and above‐ground (0.8–6.3 mg kg −1 dry wt; mean = 2 mg kg −1 dry wt) emergent plant tissues. Redox stratification in the shallow water column had a marked effect on Se speciation and behavior, illustrating bottom water removal of dissolved selenate in suboxic horizons and increased mobility of dissolved organo‐Se. Mass balance data yielded inflow and outflow loading rates for Se of 27 and 23 g d −1 , respectively (net accumulation rate of 4 g d −1 or 0.11 mg m 2 d −1 ). The rate of accumulation as calculated from the mass balance agrees with independently measured rates of Se accumulation in sediments for the site (3.6–8.1 g d −1 or 0.10–0.22 mg m −2 d −1 ). Environ Toxicol Chem 2018;37:1824–1838. © 2018 SETAC