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 mea surements and modelling. A vehicle travelling at 80 lan h(-1) on an un sealed 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 cul tivation was finer (mode of 19-22 mu m) than that from vehicular traff ic on unsealed roads (mode of 32 mu m) and hence may be transported fu rther. Endosulfan source strength from inter-row cultivation was 3.6 m u g m(-1) of travel (or 0.45 mu g m(-2)) which was only 6.0E-4% of tha t applied, 4 days after endosulfan application. This was slightly high er than the endosulfan source strength from vehicular traffic on an un sealed road (3.1 mu g m(-1) of travel), only 2 days after spraying. On unsealed roads, particle-associated endosulfan mass fractions decline d rapidly with time due to volatilisation and photodegradation and a d ecrease in endosulfan-enriched source sediment due to the removal by r epeated vehicle passes. For unsealed roads, TSP at 0.63 m height showe d endosulfan-enrichment ratios of approximately four, compared to the surface soil 0-1 cm depth, for inter-row cultivation and vehicular tra ffic. (C) 1998 Elsevier Science B.V. Al rights reserved.