Paraquat contaminations in the Chanthaburi river and vicinity areas, Chanthaburi province, Thailand

Abstract

ABSTRACT            The main objective of this study was to determine paraquat concentrations found both in the river water of the Chanthaburi River and in surface soils in the vicinity area along the riverbank, as well as the potential environmental risks of paraquat to living organisms by Hazard Quotient (HQ) Equation. The results revealed that paraquat was detected in samples collected from soil surface and water column both in dry and wet seasons. The concentrations of paraquat detected in surface soil samples were in the ranges of 3.33 to 8.28 and 1.30 to 9.15 mg/kg dry weight (dw), respectively. While the concentrations of paraquat detected in water column samples taken from the upstream of the river down to estuaries, which were collected in two seasons, were ranged from 0.13 to 7.13 and 0.07 to 13.05 µg/l, respectively, where they did not exceed the standard levels. The potential environmental risks of surface soils, which were collected in both seasons, were not at risks (HQ < 0.1), with low hazard levels (HQ 0.1-1.0). Likewise, HQ of water samples was not considered to be at risk levels (HQ < 0.1). It could be concluded that the concentrations of paraquat detected in the study area were not at risks, with low hazard effects to living organisms, despite the fact that herbicides had been applied for many decades. Regarding to the water characteristics of collected water samples, the water qualities were classified as good quality water