Soil biogeochemical toxicity end points for sub‐Antarctic islands contaminated with petroleum hydrocarbons

Abstract

Sub-Antarctic islands have been subjected to petroleum hydrocarbon spills, yet no information is available regarding the toxicity of petroleum hydrocarbons to these subpolar soils. The purpose of the present study was to identify soil biogeochemical toxicity end points for petroleum hydrocarbon contamination in sub-Antarctic soil. Soil from Macquarie Island, a sub-Antarctic island south of Australia, was collected and exposed to 10 concentrations of Special Antarctic Blend (SAB) diesel fuel, ranging from 0 to 50,000 mg fuel/kg soil, for a 21-d period. The sensitivity of nitrification, denitrification, carbohydrate utilization, and total soil respiration to SAB fuel was assessed. Potential nitrification activity was the most sensitive indicator of SAB contamination assessed for nitrogen cycling, with an IC20 (concentration that results in a 20% change from the control response) of 190 mg fuel/ kg soil. Potential denitrification activity was not as sensitive to SAB contamination, with an IC20 of 950 mg fuel/kg soil for nitrous oxide production. Nitrous oxide consumption was unaffected by SAB contamination. Carbohydrate utilization (respiration caused by sucrose) was a more sensitive indicator (IC20, 16 mg fuel/kg soil) of SAB contamination than total respiration (IC20, 220 mg fuel/kg soil). However, total soil respiration was a more responsive measurement end point, increasing soil respiration over a 72-h period by 17 mg of CO2, compared to a change of only 2.1 mg of CO2 for carbohydrate utilization. Our results indicate that IC20s varied between 16 to 950 mg fuel/kg soil for Macquarie Island soil spiked with SAB diesel fuel. These results indicate that current cleanup levels derived from temperate zones may be too liberal for soil contamination in sub-Antarctic islands.

Toxicity of diesel contaminated soils to the subantarctic earthworm Microscolex macquariensis

“…Rayner et al [15] used a hydrocarbon distribution model to determine that nonaqueous phase liquid (NAPL) droplets start to form in Macquarie Island soils at hydrocarbon concentrations between 50 to 1,000 mg/kg, depending on soil type and carbon content. Soil biogeochemical endpoints, including nitrification, denitrification, carbohydrate utilization, and total soil respiration, were developed for Macquarie Island soils by Schafer et al [36] to examine SAB contamination. The potential nitrification activity was the most sensitive endpoint to the native microbial community, with an IC20 value of 190 mg SAB/kg soil.…”

Impact of hydrocarbons from a diesel fuel on the germination and early growth of subantarctic plants

“…Thus, the added organic matter reduced the toxicity of SAB-contaminated soils in germination tests, but increased toxicity in terms of above ground shoot growth. This may be related to nutrient cycling within contaminated soils, as microbial-driven nitrification was inhibited within SAB-contaminated fuels in subantarctic regions (IC 20 at 660 mg SAB/kg soil over 21 days [14]), most likely due to the enzymatic inhibition of ammonia monooxygenase (AMO), however, denitrification process were very tolerant.…”

“…The negative environmental impacts and high costs associated with excavating and transporting contaminated soils for off-site processing and treatment have led the Australian Antarctic Division (AAD) to abandon dig-and-haul methods in favour of implementing alternative onsite in situ remediation techniques [2,3]. The in situ techniques utilised on subantarctic Macquarie Island include injection of nutrients and aeration into the soils, both of which promote natural attenuation by encouraging hydrocarbon-degrading microbes [3,[10][11][12][13][14].…”

“…This study is focused on subantarctic Macquarie Island, for which there is data for biological responses to total petroleum hydrocarbons (TPH) exposure for earthworms [21], soil microbes [13,14] and the grass Poa foliosa [22]. This is insufficient information to enable guideline development to assess the risk of fuel-contaminated soils on native subantarctic species.…”

Phytoremediation of hydrocarbon contaminants in subantarctic soils: An effective management option

“…An extensive history of polar exploration and exploitation, together with present research activities, has left subantarctic islands, such as Macquarie Island, with a legacy of petroleum pollution as a result of accidental fuel spills (Aislabie et al, 2001;Schafer et al, 2007;Tin et al, 2008). Australia's research station on Macquarie Island is heavily reliant on a light range diesel fuel known as Special Antarctic Blend (SAB), which is comprised mainly of petroleum hydrocarbons in the range C9-18.…”