Title: Investigating the partitioning behaviour of neonicotinoids in Australian soils
Authors: Carla Alongi PhD candidate1, Carly Beggs, Professor Jochen Mueller2
Introduction: Neonicotinoids are systemic pesticides that have been successfully used in the management of pests in arable farming, horticulture, urban landscapes and veterinary medicine. Their widespread use has led to residues being ubiquitously detected in soil, sediments, and waters around the world. Compounds such as imidacloprid have been consistently detected in the Great Barrier Reef Catchment in Australia, indicating field run-off as an important process regulating the movement of neonicotinoids in the environment. These pesticides have come under scrutiny as they have been found to be toxic to an array of terrestrial and aquatic invertebrates at environmentally relevant concentrations.
Aims: The aim of this research is to investigate the partitioning behaviour of neonicotinoids in 13 Australian soils to understand their availability in the soil after application. This is the first component on a broader project focusing on investigating neonicotinoids in environmental and human matrices.
Methods: The study will focus on the determination of sorption coefficients (Kd values) of neonicotinoids in 13 Australian soils which cover a range of physical-chemical properties. Statistical analysis is used to determine soil characteristics that may influence sorption capacities of analytes.
Results and Conclusion: Sorption coefficients (Kd values) for 7 neonicotinoid insecticides (Imidacloprid, Acetamiprid, Thiamethoxam, Thiacloprid, Clothianidin, Dinotefuran, Nitenpyram) were determined for 13 Australian. Calculated coefficients showed a high affinity of analytes to partition into the water phase; however, Kd values were slightly higher than those found in previous studies. The most significant soil property to influence sorption is Organic Carbon (OC).
Results indicate that neonicotinoids are highly mobile in the environment, specifically during run-off event as they show a high affinity to partition into water after soil application.