Strontium Isotope Ratios in Fish Otoliths as Biogenic Tracers of Coal Combustion Residual Inputs to Freshwater Ecosystems

Permitted and accidental releases of contaminants from coal combustion residual (CCR) storage facilities pose environmental and ecological risks for associated freshwater ecosystems around the world. Previous studies have applied isotope ratios in CCRs as environmental tracers to delineate and quantify the impact of CCRs and other fossil fuel wastes. In this proof-of-concept study, we present data from CCR-receiving as well as non-impacted lakes in North Carolina to assess the applicability of otolith-based strontium isotope ratios as biogenic tracers of CCRs in ecosystems receiving coal-fired power plant effluents. We show that while discrepancies between bulk otolith and surface water ratios likely reflected temporal variations in CCR inputs and/or upstream water sources over fish lifetimes, 87Sr/86Sr ratios in largemouth bass (Micropterus salmoides) otoliths consistently reflected those in lake sediment pore waters. Because biogenic 87Sr/86Sr ratios are both geochemically and metabolically stable, they are potentially powerful tools for informing contamination sources and timing alongside studies investigating the effects of co-occurring trace elements in fossil fuel waste streams