Mercury and other trace elements in Ohio River fish collected near coal‐fired power plants: Interspecific patterns and consideration of consumption risks

Abstract

Many coal-fired electric generating facilities in the United States are discharging higher loads of Hg, Se, and other chemicals to receiving streams due to the installation of flue gas desulfurization (FGD) air pollution control units. There are regulatory concerns about the potential increased uptake of these bioaccumulative trace elements into food webs. We evaluated the concentrations of As, total Hg (THg), methylmercury (MeHg), and Se in Ohio River fish collected proximal to coal-fired power plants, of which 75% operate FGD systems. Fillet samples (n = 50) from 6 fish species representing 3 trophic levels were analyzed. Geometric mean fillet concentrations of THg (wet wt), MeHg (wet wt), and Se (dry wt) in 3 species were 0.136, 0.1181, and 3.19 mg/kg (sauger); 0.123, 0.1013, and 1.56 mg/kg (channel catfish); and 0.127, 0.0914, and 3.30 mg/kg (hybrid striped bass). For all species analyzed, only 3 fillet samples (6% of total) had MeHg concentrations that exceeded the US Environmental Protection Agency (USEPA) human health criterion (0.3 mg/kg wet wt); all of these were freshwater drum aged ≥ 19 y. None of the samples analyzed exceeded the USEPA proposed muscle and whole body Se thresholds for protection against reproductive effects in freshwater fish. All but 8 fillet samples had a total As concentration less than 1.0 mg/kg dry wt. Mean Se health benefit values (HBVSe ) for all species were ≥ 4, indicating that potential Hg-related health risks associated with consumption of Ohio River fish are likely to be offset by adequate Se concentrations. Overall, we observed no measurable evidence of enhanced trace element bioaccumulation associated with proximity to power plant FGD facilities, however, some enhanced bioaccumulation could have occurred in the wastewater mixing zones. Furthermore, available evidence indicates that, due to hydraulic and physical factors, the main stem Ohio River appears to have low net Hg methylation potential.

Selenium and Mercury in Freshwater Fish Muscle Tissue and Otoliths: A Comparative Analysis

“…The muscle tissue trace element concentrations reported in the present study were generally similar to previous studies documenting Se and Hg fish tissue amounts for fish collected at reference locations in the Ohio River (Walters et al ; Reash et al ). In contrast, concentrations of THg in Ohio River hybrid striped bass recorded by Emery and Spaeth () were considerably higher relative to accumulations in the present study.…”

Mercury and selenium concentrations in fishes of the Upper Colorado River Basin, southwestern United States: A retrospective assessment

“…We found mean Se:THg molar ratios to be positive and above 1 in all species, concurrent with previous studies investigating Se:Hg molar ratios in freshwater fish ( Fig 4A) [24,25,94,95] though our ratios were much higher than other comparable species [24,25]. The higher values are presumably a result of the elevated Se concentrations found across the UCRB.…”

Bioavailability of mercury in power plant wastewater and ambient river samples: Evidence that the regulation of total mercury is not appropriate

“…The low median percentage of THg as MeHg in samples from the current study (<2%) is similar to findings reported for samples collected at the same 4 Ohio River power plant intake locations and at various ambient locations (ORSANCO , ). The findings from this study support previous inferences that the methylation potential of the Ohio River is low (EPRI ; Reash et al ).…”