ScienceAsia 23 (1997): 241-248 |doi: 10.2306/scienceasia1513-1874.1997.23.241

STUDY ON ORGANOCHLORINE PESTICIDES RESIDUES IN THE MEKLONG RIVER

MONCHAN MAKETON^a, MONTIEN SONGSERM^a, AND MUKDA AUTARRAPONG^b

ABSTRACT: Study on organochlorine pesticides residues in the water samples of the Meklong River were carried out during March 1995 to February 1996. The water samples were collected every month at 15 stations. Eleven organochlorine pesticide residues were determined by Gas Chromatography. Ten organochlorine pesticide residues have been determined from 180 water samples, these are; o,p'-DDT, heptachlor, p,p'-DDT, p,p'-DDD, dieldrin, p,p'-DDE, lindane, o,p'-DDD, heptachlor epoxide and aldrin with the averages of 0.068, 0.118, 0.023, 0.074, 0.058, 0.021, 0.003, 0.016, 0.004 and 0.002 ppb. with the percentage of each pesticide found as 60.0, 52.22, 51.11, 48.88, 47.22, 39.44, 26.67, 22.22, 10.56 and 1.11 respectively. The organochlorine pesticides found could be divided into four group, these include; total DDT, heptachlor group, drin group and lindane group with their average of 0.201, 0.118, 0.059 and 0.003 ppb respectively. There were no significant difference of the pesticide residues among the 15 stations at 95% confidence interval. And it seems to be higher residues during the rainy season than the dry season with significant difference at 95% confidence interval in heptachlor and total DDT. Heptachlor group in rainy season and dry season were 0.088 and 0.030 ppb, while total DDT were 0.153 and 0.048 ppb, respectively.

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a Department of Zoology, Faculty of Science, Kasetsart University.
b Toxicology Group, Fisheries Environment Department, Division of Fisheries, Bangkok.

Received 20 May 1997