2015 Volume 6 Issue 1 Pages 175-180
Large quantities of pesticides and herbicides are used in the Namphong River catchment, NE Thailand for protection of crops and agro industrial production. The aim of this study was to screen pesticides in waters of the Namphong River from in-situ river aquaculture, surface runoff and agro industrial discharges to identify if pesticide levels pose significant risk to the aquatic ecosystem. A passive sampling technique was used to estimate the level of pesticides in the river water. Pesticides were accumulated on polydimethyl siloxane (PDMS) strip passive samplers during 29 days deployment in January-February 2012, and then sent to Australia for analysis of pesticides at the University of Queensland and Queensland Health Laboratories. The PDMS passive samplers were deployed at 5 sites in the Namphong River from below the Ubonratana Dam, the tributary downstream of the paper mill and vegetable and paddy fields down to the Chi River above the junction of Namphong River. Atrazine, ametryn, chlorpyrifos and oxadiazon were found at all sites at elevated levels associated with vegetable and paddy field areas indicating their extensive application. Terbuthylazine, terbuphos and phosphate tri-n-butyl were found only in the paper mill discharge. Traces of galaxolide were found at all sites but only in significant amounts (30 times higher) just below the paper mill. Comparison of pesticides between the present and an earlier 2005 study of the paddy field ecosystem 50 km N from Khon Kaen show a shift from organochlorine use to low persistence pesticides, particularly chlorpyrifos. The results confirm that a range of pesticides are being used in the Namphong river catchment able to be detected downstream, though at low levels. These data provide a baseline, showing the need exists for more systematic and complex assessment of the catchment to develop a tool for pollution control in the catchment and to identify major sources of contamination and for ongoing environmental risk management.
