NATURAL DEGRADATION RATES OF BTEX COMPOUNDS AND NAPHTHALENE IN A SULFATE-REDUCING GROUNDWATER ENVIRONMENT

Field and laboratory evidence show natural degradation of toluene, ethylbenzene, m-, p- and o-xylenes, 1,3,5-trimethylbenzene and naphthalene in sulphate reducing groundwater conditions of the Bassendean Sands in the Perth basin, Western Australia. Natural degradation rates were obtained from a groundwater tracer test with deuterated organic compounds injected into a dissolved hydrocarbon plume, down-gradient of a leaking underground storage tank at an urban service station. These were compared with similar data obtained from modelling of the whole contaminant plume itself and also with data obtained from large-scale laboratory column experiments with groundwater spiked with BTEX compounds. Toluene degradation rate was 200 to 500 times higher in the anaerobic laboratory columns than in the field. Degradation rates in the tracer test compared well with model-derived field estimates.