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Application of bioactivity-based monitoring to evaluate remediation effectiveness – a case study at Erie Pier Ponds, Duluth, MN.
Citation:
Santana Rodriguez, K., Dan Villeneuve, K. Jensen, M. Kahl, J. Doering, J. Cavallin, A. Cole, A. Kittleson, S. Poole, K. Dean, C. Jenson, AND G. Ankley. Application of bioactivity-based monitoring to evaluate remediation effectiveness – a case study at Erie Pier Ponds, Duluth, MN. SETAC North America, Fort Worth, TX, November 15 - 19, 2020.
Impact/Purpose:
Remediation of contaminated sites is a costly and time-consuming endeavor for stakeholders. An important aspect of remediation projects is the ability to provide timely evaluation of the success of remediation or mitigation measures in reducing hazard and/or risk associated with site contaminants. For sites dominated by a relative handful of contaminants with well established toxicity benchmarks, effectiveness can be judged using analytical monitoring of chemical concentrations. However for sites impacted by complex mixtures that include both legacy and current inputs, evaluation of remedy effectiveness can be more challenging. The aim of the present work was to explore and evaluate the use of bioactivity-based monitoring approaches as an alternative way to assess remedy effectiveness. Particularly where remediation activities may cause physical alterations to an intact system, bioactivity-based remediation may be one of the few viable ways to provide a relatively short-term assessment of a remediated site. Thus, methods piloted as part of this research, if successful, are likely to be of interest to federal, state, local, and tribal authorities that are making investments in remediation of contaminated sites.
Description:
Several small ponds neighboring the Erie Pier, an historical loading dock for ships, in the St Louis River, Duluth, MN have been scheduled for remediation of sediments with elevated concentrations of mercury, dioxins, furans and PCBs. This remediation will involve bank to bank removal of the sediment, which will disrupt the habitat and basic ecosystem structure of the ponds. The current research examined whether molecular and physiological bioactivity profiles associated with samples and/or biota from the site could be used as a near-term indicator of remedy effectiveness while the ecosystem recovers from the physical disturbance associated with the dredging. Our initial goal was to establish baseline bioactivity profiles for the site. For a 2018 pilot investigation, lab-reared fathead minnows were caged at the site for 48 h or 21 d. Additionally, composite water samples were evaluated for bioactivity using multifactorial in vitro screening assays. In these assays, water from the site activated several nuclear receptors including peroxisome proliferator-activated receptors (PPAR), pregnane X receptor, and retinoid X receptor beta (RXR-b), as well as G protein-coupled receptors (GPCRs) such as prostaglandin receptors I, D2, and E2, dopamine receptor D1 (DRD1), adenosine A2b receptor (ADORA2B) and melanocortin receptor (MC4R). Transcripts for an inducible enzyme involved in xenobiotic metabolism, cytochrome P450 1a1 (cyp1a1) were upregulated in the liver of male fathead minnows caged at the site, but no significant induction of vitellogenin mRNA, an indicator of estrogenicity, was detected. In 2019, fish were caged at the site for 7-day intervals over the course of 8 weeks to capture a broader range of seasonal and temporal variation in biological endpoints of interest. Up regulation of cyp1a1 and the PPAR-regulated gene coding for lipoprotein lipase (lpl) was detected in the liver of male fish and the range of variation typical of late summer/early fall at the site was captured. This presentation will report on the biological parameters evaluated in 2018-2019 and outline additional pre-remediation characterization planned for 2020, the final year of pre-remediation sampling. The success of this bioactivity-based approach for evaluating remedy effectiveness will be evaluated in subsequent years and opportunities for deployment at other sites explored.