Environmental Fate of Atrazine Applied Pre- and Post-planting in a Eucalyptus Nitens Plantation in Tasmania, Australia

The potential for contamination of surface and ground water by atrazine, applied preand postplant in a Eucalyptus nitens (Deane & Maid.) Maid plantation is investigated as part of a wider based Australian study. These studies aim to provide forest plantation managers with a better understanding of the processes involved in the behaviour of atrazine in the Australian environment. This information will in turn be used to develop management systems for the continued, safe use of atrazine in forestry. Atrazine was applied, by tractor, at 8 kg a.i. ha immediately prior to planting of E. nitens and again 12 months after planting in a 60 hectare catchment on the North West Coast of Tasmania. After spraying at regular fortnightly intervals, spot water samples were taken over periods of nine and 12 months respectively, whilst more intense water sampling occurred in association with rainfall events. Initially samples were analysed for atrazine, total suspended solids and turbidity. After the post-plant spray, water samples were analysed for atrazine and the metabolites desethylatrazine and desisopropylatrazine. Water sample results and relationships between water flow, metabolites and the parent compound will be discussed. The potential for the vertical movement of atrazine through a soil profile was determined by applying atrazine at 8 kg a.i. ha to a small area at the top of the catchment. Soil cores were taken at 1, 7, 14, 28, 56, 112, 280, 410 and 890 days after atrazine application. Atrazine half-life, and the potential for movement through the soil profile, will be discussed.