The depletion of dieldrin and DDT concentrations in Kinglake soils

Twenty-two sites on 14 former potato growing properties at Kinglake, Victoria, with similar soil type, topography and history of chemical use, were soil tested for organochlorine chemicals during 1987-88 and again during 1997-98. The 95% confidence limits for the decline in concentrations of dieldrin and DDT in the soil were 5.5-41.5% and 29.1-48.5%, respectively. There were no significant differences between farms in the rate of depletion of either organochlorine. Reductions in both to 1997-98 were not significantly associated with the concentration in 1987-88.