| Summary: | Progress Code: completed Purpose To provide an ecotoxicological risk assessment of groundwater from two Macquarie Island fuel spill sites that have undergone remediation, delivering evidence to assess the level of residual risk posed by the sites to the adjacent marine receiving environment. An ecotoxicological risk assessment of groundwater from two Macquarie Island fuel spill sites was conducted to assess the level of risk posed by the sites to the adjacent marine receiving environment. Experiments were conducted on Macquarie Island during the summer season of 2017/18. The two fuel spill sites (known as: Fuel Farm and Power House, see file: Map-macquarie_building_and_structures_14676.pdf) within the vicinity of the Macquarie Island research station had undergone intensive in situ remediation by the Australian Antarctic Division over the previous decade. Despite remediation efforts, groundwater leaching from the sites continued to contain some residual fuel contamination, with sheen observed at several shoreline seeps and chemical analysis of groundwater samples confirmed some hydrocarbon contamination remained. This study aimed to assess the level of residual risk posed by groundwater from these sites as it enters the adjacent marine environment. We ran a series of toxicity tests using composited samples of salinity-adjusted groundwater discharge, as an exposure medium to test the sensitivity of 11 locally collected marine invertebrate species to the groundwater. Groundwater sampling was conducted over two periods: 23-29/11/17 and 18-20/12/17, for use in two rounds of toxicity testing (referred to as test round 1 (A and B) and test round 2). Groundwater samples were collected from 22 groundwater monitoring points; 12 surface seeps and 7 previously installed piezometers. These monitoring points were located along the coastal margin of the of the fuel spill sites, at their boundary with the adjacent marine environment (see: Locations-Fuel Farm-groundwater monitoring.pdf and Locations-Powerhouse-groundwater ...
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