| Summary: | Hydrocarbon contamination of Antarctic soils is evident in limited areas where accidental fuel spills have occurred, usually near scientific bases or field camps. To understand the short-term fate and effects of fuel spills on Antarctic soils a contained experiment was established at Scott Base, Antarctica. Soil cores (105 x 10.5 cm diameter and 30 cm high) were filled with a sieved fraction(< 6.7 mm) of soil (Typic Anhyorthel), buried to the ground surface, and left to equilibrate over winter. Fuel (60 mL of JP-5, an equivalent depth of 7 mm) was applied in droplets, evenly to each of 63 cores. The remaining 42 cores were kept as controls. Ten cores (five control and five JP-5 treated) were weighed daily to monitor changes in moisture and snowfall, and to quantify the volatile loss of JP-5 fuel. In-situ temperatures (2, 5 and 20 cm depth) of both control and JP-5 treated cores were measured in triplicate at hourly intervals. Cores were destructively sampled in triplicate 0.1, 1, 3, 7, 14, 21, 28, 35, 42, 358, 365, 372, 379, and 397 days after fuel application and samples were returned, frozen, to New Zealand for total petroleum hydrocarbon (TPH) and microbial analyses. During destructive core sampling fuel penetration was observed to have reached a mean maximum depth of 15 cm ten days after JP-5 application, and 17 cm after one year. A large proportion (between 35% and 60%) of the fuel applied was lost to volatilisation within six weeks following the spill. The volatile loss of JP-5 fuel, as determined by weighing cores after correcting for moisture addition and evaporation of snowfall was about 9% after 18 hours, 26% after one week, and 35% after six weeks. The TPH content of the soil decreased in the 0-2.5 cm depth range from 46 000 mg kg- 1, two hours after fuel application, to 9 000 mg kg-1 after six weeks. In the depth range from 2.5 cm to the mean maximum depth of fuel penetration the TPH content of the soil decreased from 45 000 mg kg-1 two hours after fuel application to 10 000 mg kg-1 after six weeks. The corresponding volatile loss of JP-5 fuel, as determined from TPH concentrations within the total depth of fuel contaminated soil was about 50% after one week, and 60% after six weeks. Differences in the exact total fuel loss as recorded by weighing cores and TPH were attributed to various errors within each technique. The application of fuel had no measurable effect on soil temperature at 2 cm, 5 cm, and 20 cm depth, even though the surfaces of JP-5 treated cores were visibly darker than the control cores. The colour difference however had decreased markedly after three weeks. No differences were observed in the mean numbers of culturable heterotrophic bacteria and hydrocarbon-degrading microbes between JP-5 treated and control cores six weeks after the spill. It is, therefore, inferred that the initial application of fuel was non-toxic to culturable heterotrophic bacteria and hydrocarbondegrading microbes. Soil surface albedo measurements were also made over three previously contaminated sites in the Ross Sea region, and were found to be lower where the surface remained darkened by hydrocarbons, compared to nearby controls.
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