Anthropogenic dust and endosulfan emissions on a cotton farm in northern New South Wales, Australia

Dust has been implicated as a pathway for endosulfan transport to the riverine environment in New South Wales. Anthropogenic dust, expressed as total suspended sediment (TSP), and particle associated endosulfan emissions were estimated on a cotton (Gossypium hirsutum L.) farm in northern New South Wales, Australia, using a combination of direct measurements and modelling. A vehicle travelling at 80 km h−1 on an unsealed road was a greater source of TSP emission (3.7 g m−1) than an 8-m wide inter-row cultivator travelling at 8 km h−1 (1.7 g m−1). However, the particle size distribution of the TSP from inter-row cultivation was finer (mode of 19–22 μm) than that from vehicular traffic on unsealed roads (mode of 32 μm) and hence may be transported further. Endosulfan source strength from inter-row cultivation was 3.6 μg m−1 of travel (or 0.45 μg m−2) which was only 6.0E-4% of that applied, 4 days after endosulfan application. This was slightly higher than the endosulfan source strength from vehicular traffic on an unsealed road (3.1 μg m−1 of travel), only 2 days after spraying. On unsealed roads, particle-associated endosulfan mass fractions declined rapidly with time due to volatilisation and photodegradation and a decrease in endosulfan-enriched source sediment due to the removal by repeated vehicle passes. For unsealed roads, TSP at 0.63 m height showed endosulfan-enrichment ratios of approximately four, compared to the surface soil 0–1 cm depth, for inter-row cultivation and vehicular traffic.