Derivation of site-specific environmental quality guideline values for fuel-contaminated soils on sub-Antarctic Macquarie Island.

Accidental fuel spills associated with the storage, transfer, and use of diesel fuel for power generation have occurred on sub-Antarctic Macquarie Island since the establishment of the island's research station in 1948. An extensive in situ remediation program was implemented by the Australian government from 2009 to 2016 that used nutrient addition and air sparging to enhance the microbial degradation of petroleum products. During this period, a range of ecotoxicological assessments were conducted to better understand the impacts of fuel in soils on native biota and their sensitivity. This study compiles this ecotoxicological data into a species sensitivity distribution (SSD) to establish environmental quality guideline values (EQGVs) for fuels in soils on Macquarie Island. The SSD model includes 13 critical effect concentrations (CECs) selected using an expert judgment approach. These include data from functional and community-based tests as well as traditional single-species toxicity tests using microbes, plants, and invertebrates and representing the range of carbon content (~3%-48%) and fuel composition at various stages of degradation (from fresh to 18 months aged) in soils as occurs at contaminated sites on the island. A protective concentration (PC80) of 97 mg/kg TPH C9-C40 (95% CI 24-283) was derived for special Antarctic blend diesel from the SSD and is recommended as an appropriate site-specific EQGV and potential remediation target for the immediate station area in the vicinity of infrastructure. More conservative PC values are also provided for areas with higher conservation values outside the station footprint. These EQGVs are the first to be produced for fuels in the sub-Antarctic and Antarctic regions. They will be used to inform ongoing environmental management on Macquarie Island and are likely suitable and recommended for use more broadly across the sub-Antarctic. Integr Environ Assess Manag 2024;20:2334-2346. © 2024 Commonwealth of Australia. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).