Poolpak T, Pokethitiyook P, Kruatrachue M, Arjarasirikoon U, Thanwaniwat N
Department of Biology, Faculty of Science, Mahidol University, Phayathai, Bangkok, Thailand.
J Hazard Mater. 2008 Aug 15;156(1-3):230-9. doi: 10.1016/j.jhazmat.2007.12.078. Epub 2007 Dec 28.
The most natural waterways in Thailand are utilized for conventional agricultures, e.g. irrigation and wastewater discharge. Concentrations of 20 organochlorine pesticides (OCPs) were measured in surface sediments collected from the tributaries of the Mae Klong River during 2003-2005. The sampling sites chosen were nearby the rice paddy which organochlorine pesticides were intensively used for crop cultivation. Solid-liquid extraction technique was used for sediment extraction, and gas chromatography with electron capture detector was applied for pesticides determination. Total concentrations of OCPs found were ranged from 4.12 to 214.91 microg g(-1) dw in the first year. In the second year, total residue concentrations in the surface sediments were in the range of 3.26-215.09 microg g(-1) dw. Concentrations of pesticides were greater in dry-season rice cultivation period in both sampling years, and heptachlor epoxide was the contaminant found at highest concentration in this study. In addition, the occurrence of some selected contaminants including DDT, DDD and DDE reflects the recent contamination in the study area. This demonstrates not only that the natural waterway was polluted and contained much pesticide residues, but it also illustrates the necessity of a continuous long-term monitoring of the affected environment.
泰国最天然的水道被用于传统农业，例如灌溉和废水排放。2003年至2005年期间，对从湄公河支流采集的表层沉积物中20种有机氯农药（OCPs）的浓度进行了测量。所选采样点位于大量使用有机氯农药进行作物种植的稻田附近。采用固液萃取技术进行沉积物萃取，并使用带有电子捕获检测器的气相色谱法测定农药。第一年发现的OCPs总浓度范围为4.12至214.91微克/克干重。第二年，表层沉积物中的总残留浓度范围为3.26至215.09微克/克干重。在两个采样年份的旱季水稻种植期，农药浓度都更高，七氯环氧化物是本研究中发现浓度最高的污染物。此外，一些选定污染物（包括滴滴涕、滴滴滴和滴滴伊）的出现反映了研究区域近期的污染情况。这不仅表明天然水道受到污染且含有大量农药残留，还说明了对受影响环境进行持续长期监测的必要性。
