Title
Arsenic, chromium, and other elements of concern in fish from remote boreal lakes and rivers: Drivers of variation and implications for subsistence consumption
Author(s)
Lescord, G.L., Johnston, T.A., Heerschap, M.J., Keller, W., Southee, F.M., O'Connor, C.M., Dyer, R.D., Branfireun, B.A., and Gunn, J.M. 2019.
Published
2019
Publisher
Environmental Pollution
Abstract
Eating fish provides numerous health benefits, but it is also a dominant pathway for human exposure to contaminants. Many studies have examined mercury (Hg) accumulation in fish, but fewer have considered other elements, such as arsenic (As) and chromium (Cr). Recently, freshwater fish from several pristine boreal systems across northern Ontario, Canada, have been reported with elevated concentrations of As and Cr for reasons that are not well understood. Our goal was to investigate the ecological and environmental influences over concentrations of As, Cr, and other elements in these fish to better understand what affects metal uptake and the risk to consumers. We measured 10 elements (including As, Cr, Hg) as well as carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) stable isotopes in 388 fish from 25 lake and river sites across this remote region. These data were used to determine the effect of: 1) trophic ecology; and 2) watershed geology on piscine elemental content. Overall, most element concentrations were low, often below provincial advisory benchmarks (ABs). However, traces of Hg, As, Cr, and selenium (Se) were detected in most fish. Based on their exceedance of their respective ABs, the most restrictive elements on fish consumption in these boreal systems were Hg > As > Cr. Arsenic and Se, but not Cr concentrations were related to fish size and trophic ecology (inferred from δ13C and δ15N), suggesting bioaccumulation of the former elements. Fish with enriched δ34S values, suggestive of anadromous behaviour, had lower Hg and higher Se concentrations. Modeling results suggested a strong effect of site-specific factors, though we found weak trends between piscine elemental content and geological features (e.g., mafic intrusions), potentially due to the broad spatial scale of this study. Results from this study address gaps in our understanding of As and Cr bioaccumulation and will be help inform fish consumption guidelines.
Keywords
Metals; Bioaccumulation; Geology; Mining; Stable isotopes; Freshwater
Full Citation
Lescord, G.L., Johnston, T.A., Heerschap, M.J., Keller, W., Southee, F.M., O'Connor, C.M., Dyer, R.D., Branfireun, B.A., and Gunn, J.M. 2019. Arsenic, chromium, and other elements of concern in fish from remote boreal lakes and rivers: Drivers of variation and implications for subsistence consumption. Environmental Pollution
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