A PILOT STUDY INTO PESTICIDES AND THE BURDEKIN DELTA AQUIFER SYSTEM

THE Burdekin delta relies heavily on the underground aquifer system for the irrigation of sugarcane and domestic supply. Therefore, the whole community, not just the irrigation sector, feels any adverse impacts on the aquifer system. An initial investigation into the level of pesticides in each of the irrigation water being applied, water moving through the soil profile and of the soil itself was conducted on six sites across the delta. Irrigation water (pumped from groundwater sources) was analysed on three occasions over the 2002–2003 season. This analysis included MCPA, 2,4-D, diuron, atrazine, ametryn, chlorpyrifos, pendimethalin and hexazinone, which are the active ingredients of the most commonly used pesticides in the Burdekin delta. The groundwater samples returned no quantifiable levels of any pesticide. Soil samples taken in October 2002 showed a small amount (< 0.023 mg/kg) of diuron and atrazine adsorbed at a number of the sites. Water samples taken after each irrigation at the 1.5 m depth in the soil profile showed that there were small levels of pesticides moving though the soil profile in deep drainage water. These preliminary results suggest that the groundwater sources for the six experimental sites were comparatively uncontaminated by pesticides at the time these samples were taken. However, these results indicate the potential for pesticide movement through the soil profile and highlight that there is a real (however small) possibility of pesticides reaching the underground aquifers through soil water movement.