Organochlorine pesticide residues in fishes from the Chao Phraya river
1998
Supaporn Chinda
Types and quantities of organochlorine pesticide residues in fishes from the Chao Phraya River were investigated by collecting fish samples from seven stations in the Chao Phraya River during April, July and November 1997. Gas Chromatography method were used to detect organochlorine pesticide residue. Twelve detectable pesticide residues were observed namely: p,p'-DDE, p,p'-DDD, p,p'-DDT, o,p'-DDT, alpha-BHC, beta-BHC, gamma-BHC, delta-BHC, heptachlor, heptachlorepoxide, aldrin and dieldrin, whereas endrin was nondetectable. The mean concentrations of BHC, Cyclodiene and DDT analogues groups found in fish samples were 0.7733, 0.5810 and 2.4618 ppb, respectively. Correlation between the quantity of pesticide residues in water and fish samples showed that all the three groups were significantly different at 95 percent, whereas the correlation between the quantity of pesticide residues in sediment and fish samples were nonsignificantly different. The changes in pesticide residues in different seasons and areas of the Chao Phraya River revealed that the quantity of three pesticides, heptachlor, dieldrin and DDT analogues, were highest in the lowver part of the Chao Phraya River followed by the middle and upper parts respectively. Among those three pesticides, the mean highest quantity were different by seasons. The highest quantities of heptachlor and DDT analogues were observed in rainy season, while dieldrin was found highest in dry season. Besides, there was no correlation between the quantity of three pesticide groups and seasons which changes of seasons did not influence on the quantity of pesticide residues in fishes.
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