Abstract
Residual level of persistent organochlorines (OC) such as Sigma HCH (alpha-HCH, beta-HCH, gamma-HCH, delta-HCH, Sigma DDT (o,p'-DDD, op-DDE, p,p-DDE pp-DDD, pp'-DDT, o,p'-DDT), dieldrin and endrin were measured in a number of water samples from Ambro creek and their accumulation in shrimp (Penaeus merguiensis and P. penicillatus), fish (Otolithes ruber) and brine shrimp (Artemia sp.) reared in ponds for a period of four months. Samples were extracted with organic solvents, and quantified using gas chromatography-electron capture detection (GC/ECD). It has been found that results of animal tissue and water are not same however OCs, (mainly Sigma DDT and Sigma HCH 4,4-DDT, Dieldrin+2,4-DDT, and Methoxychlor were detected in all samples). Heptachlor exo-epoxide were found in fish and Artemia sp. and absent in all shrimp samples. Heptachlor endo-epoxide was detected only in Artemia sp. and average residual concentration of OCs in Artemia sp. was 0.004-0.09 ppm. Methoxychlor was found in the highest quantity in all the samples whether it was fish, shrimp or Artemia. In fish average residual concentration of all (OCs) in individual sample was 0.03-0.180 ppm.
Bio-accumulation of pesticides in shrimps and fish was found to be with in the permissible limit after four months rearing since none of the detected pesticides seem to exceed their ADI. It has been found that all the pesticides present in water were not found in similar concentration in animal tissue. The maximum quantity and number of pesticide residues was found in brine shrimp, Artemia sp., the fish and shrimp 35-37 however a number of pesticides were found below the detectable limits of the instrument (BLD). The accumulation of pesticides in shrimps and fish was found to be with in the permissible limit according to codex convention 2003.