Selenium, arsenic, and mercury in fish inhabiting a fly ash exposure gradient: interspecific bioaccumulation patterns and elemental associations

Releases from coal ash impoundments can be a significant source of trace elements to the aquatic environment. In the present study, whole‐body concentrations of As, Hg, and Se in various fish species inhabiting streams receiving a gradient of fly ash exposure are reported. High‐exposure sites had elevated water concentrations of As, Mo, Se, and SO 4 . Fish were collected during two seasons in 2007. Mercury concentrations in all fish samples were low (range = 1.2–99 ng/g wet wt); highest As concentrations occurred in fish from high‐exposure sites. Whole‐body Se concentrations were low at reference sites but increased as the magnitude of fly exposure increased. For all sites combined, a significant ( r 2  = 0.60) correlation was observed between the geometric mean of each species' whole‐body Se concentration and log‐transformed water Se concentration. A significant inverse relationship was apparent with log‐transformed whole‐body Hg and Se concentrations ( r 2  = 0.56 for all species and sites combined), suggesting that high tissue Se levels antagonistically regulated Hg bioaccumulation. Sunfish ( Lepomis sp.) from high‐ and medium‐exposure sites had significantly higher Se body residues, but significantly lower Hg, relative to fish from low‐exposure and reference sites. Ninety percent of fish from high‐exposure sites had a surplus of Se, whereas all fish from reference sites had Se/Hg molar ratios <1.0. These ratios increased as water Se increased. Where fish have moderate to high exposure to fly ash‐influenced water, Se tissue levels can be expected to be elevated (as well as As, in some cases), but tissue Hg concentrations will likely be low. Environ. Toxicol. Chem. 2012;31:739–747. © 2012 SETAC