Accumulation of organochlorine residues in water, sediment and aquatic invertebrates at Khong 7, Rangsit agricultural area, Pathum Thani Province

Abstract

Organochlorine pesticides residues (OCPRs) such as sigmaBHCs, sigmaHeptachlor, sigmaAldrin, sigmaDDTs, sigmaEndosulfans, sigmaEndrin, and methoxychlor collected from water, sediment, and aquatic invertebrates such as Lanchester's freshwater prawn Machrobrachium lanchesteri, aple snail Pomacea sp., and freshwater snail Filopaludina martensi from Khlong 7, Rangsit agricultural area, Pathum Thani province from June 2004 to May 2005, were measured using gas chromatography-micro electron capture detector (GC- microECD). The means of minimum and maximum concentrations of OCPRs in water, sediment, M. lanchesteri, Pomacea sp., and F. martensi were 0.004-0.08 microg./L, 0.16-14.67 microg./kg dry weight, 2.08-53.04 microg./kg dry wet weitht, 6.77-47.83 microg./kg dry weight, and 5.39-79.61 microg./kg dry weight, respectively. The highest amount of OCPRs were sigmaEndosulfans (0.08 microg./L) in water samples, sigmaHeptachlors (14.67 microg./kg dry weight) in sediment samples, and sigmaDDTs in invertebrate samples (47.83, 53.04, and 79.61 microg./kg wet weight in Pomacea sp., M. lanchesteri, and F. martensi, respectively). For the OCPSs accumulations, the invertebrate-water ratios of sigmaDDTs were 2,483, 2,754 and 4,133 folds in Pomacea sp., M. lanchesteri, and F. martensi, respectively, whereas the invertebrate-desiment ratios were 4.0, 4.4 and 6.6 folds in Pomacea sp., M. lanchesteri, and F. martensi, respectively. Accumulations of OCPSs were mostly found in F. martensi more than in Pomacea sp. and M. lanchesteri. The higher OCPSs accumulation in F. martensi might be explained by its feeding behavior as a scavenger and its benthic life form. Therefore, F. martensi tents to expose to pesticides, by both absorption and ingestion, higher than Pomacea sp. and M. lanchesteri which prefer to live mainly at the littoral zone. However, the levels of OCPSs in all aquatic invertebrates were in acceptable limit recommended by the Codex Alimentarius Commission and the Ministry of Public Health in Thailand.