Evaluation of Herbicide Pollution in the Kerian Ricefields of Perak, Malaysia

Pesticide use in agriculture can cause undesirable effects to the natural environment as well as to humans. A field trial to determine residues of 2,4-D and paraquat in the ricefield soil and surface water of the drainage canals in the Kerian district of Perak, Malaysia, was conducted during 2006/2007. Analyses of 2,4-D and paraquat in the soil and water samples were carried out using a high performance liquid chromatograph (HPLC) fitted with a UV detector. The water sampling activities were conducted from 12 April to 03 September 2006 and18 February to 15 April 2007. The parameters of water drainage were measured during the study. Residues of paraquat were detected in only a few of the water samples at levels ranging from 0.6-6.9 μg/l but in many samples from the drainage canals 2,4-D was detected frequently at levels ranging from 0.04-1.49 μg/l. The fate of 2,4-D and paraquat in clay loam soil under tropical conditions showed that both herbicides leached downward to the depth of 5 cm on the first day after treatment (DAT). Throughout the sampling period, 2,4-D and paraquat were detected in the soil profile at levels ranging from 0.046-0.128 and 0.212-0.362 mg/kg, respectively. The maximum concentrations at one DAT at the (0-5) cm soil depth were 0.128 and 0.362 mg/kg for 2,4-D and paraquat respectively.