| Abstrakt: |
Groundwater contaminant plumes from a variety of point sources, including landfills, are a potential risk to biota in receiving surface waters, particularly invertebrates in the benthic zone. Assessing contaminant exposure and impacts on benthic invertebrates is a challenge due to mixing of groundwater and surface water around the sediment interface, and potential confounding effects of other water quality and sediment properties (natural and human factors). These issues were addressed by a multiple-lines-of-evidence approach applied to an Ontario stream impacted by a historic landfill. Assessment components applied within and outside of the contaminant footprint included (a) sampling shallow groundwater to determine concentrations of a range of legacy (ammonium, metals, hydrocarbons, etc.) and emerging contaminants (PFAS, bis-phenols, pharmaceuticals, etc.), (b) sampling surficial sediment to determine benthic community densities and composition, (c) subsampling the sediment cores for microbial genomics analysis, (d) assessment of natural habitat potential cofactors (sediment particle size, water and sediment depths, stream velocity), and (e) in-situ toxicity testing of groundwater discharging across the sediment bed using caged invertebrates. This presentation will demonstrate these applications and discuss their successes and limitations, with the aim to provide guidance on assessments of aquatic ecosystem risk posed by groundwater contaminants at the large number of landfills and other contaminated sites in Ontario and elsewhere. [ABSTRACT FROM AUTHOR] |
