Forensic tracers of exposure to produced water in freshwater mussels: a preliminary assessment of Ba, Sr, and cyclic hydrocarbons

Abstract

Hydraulic fracturing is often criticized due in part to the potential degradation of ground and surface water quality by high-salinity produced water generated during well stimulation and production. This preliminary study evaluated the response of the freshwater mussel, Elliptio complanata, after exposure to produced water. A limited number of adult mussels were grown over an 8-week period in tanks dosed with produced water collected from a hydraulically fractured well. The fatty tissue and carbonate shells were assessed for accumulation of both inorganic and organic pollutants. Ba, Sr, and cyclic hydrocarbons indicated the potential to accumulate in the soft tissue of freshwater mussels following exposure to diluted oil and gas produced water. Exposed mussels showed accumulation of Ba in the soft tissue several hundred times above background water concentrations and increased concentrations of Sr. Cyclic hydrocarbons were detected in dosed mussels and principle component analysis of gas chromatograph time-of-flight mass spectrometer results could be a novel tool to help identify areas where aquatic organisms are impacted by oil and gas produced water, but larger studies with greater replication are necessary to confirm these results.

Freshwater Mussel Soft Tissue Incorporates Strontium Isotopic Signatures of Oil and Gas Produced Water

“…Normalizing mussel soft tissue metal concentrations to Ca soft tissue concentrations helps to reduce variability associated with differences in metal uptake by individual mussels, increasing the sensitivity of mussels as indicators of water pollution . Sr/Ca tissue molar ratios in soft tissue significantly correlated with Sr/Ca water molar ratios in the final tank water samples ( R 2 = 0.95; p ≪ 0.001), indicating that, similar to hard shells, Sr/Ca molar ratios remain a strong tracer of Marcellus O&G-produced water contamination. , Ba/Ca molar ratios yielded no significant correlations between tissue and water (Figure ), unlike findings from Gillikin et al, who found increasing Ba/Ca tissue ratios associated with increasing Ba/Ca water ratios . Barite precipitation may have reduced the aqueous Ba concentrations bioavailable to mussel feeding.…”

“…Piotrowski et al observed a higher abundance and diversity of cyclic hydrocarbons, Sr, and Ba in mussels dosed in tanks with Utica Shaleproduced water compared to those of control tank mussels. 32 The uptake of alkaline earth metals as metabolic analogues for Ca represents a unique forensics opportunity to trace wellestablished isotopic signatures in Marcellus Shale-produced water that contains inherently high alkaline earth metal concentrations (i.e., 87 Sr/ 86 Sr ranging from 0.71150 to 0.71275, 3,33,34 226 Ra/ 228 Ra of >1 35,36 ). 87 Sr/ 86 Sr, in particular, provides a robust tool for elucidating salinity sources (i.e., natural evaporites and municipal, industrial, and agricultural wastewater).…”

“…Even at low metal water concentrations, increased metal bioaccumulation in caged mussels grown in the Athabasca oil sands region presented ecotoxicological risks to aquatic life by impacting mussel metallothionein and lipid peroxidation, indicating oxidative stress. Piotrowski et al observed a higher abundance and diversity of cyclic hydrocarbons, Sr, and Ba in mussels dosed in tanks with Utica Shale-produced water compared to those of control tank mussels …”

Freshwater salinization syndrome: from emerging global problem to managing risks

“…Biomonitoring approaches may also be useful to track and record changes in major ions in freshwater environments (e.g. Piotrowski et al 2020). Given that land use change and climate variability amplify contaminant pulses in many human-impacted streams, it is difficult to accurately quantify exceedances and violations in water quality with traditional grab sampling during fixed routine monitoring of growing water quality problems (Kaushal et al 2014(Kaushal et al , 2019Haq et al 2018;Moore et al 2019;Morel et al 2020).…”