Studies on degradation of C-14-chlorpyrifos in the marine environment

Degradation of C-14-chlorpyrifos was studied in a marine ecosystem for 60 d ays and in marine sediment under moist and flooded conditions using a conti nuous flow system allowing a total C-14-mass balance for a period of 40 day s. In the marine ecosystem, C-14-chlorpyrifos underwent rapid degradation a nd very little (1-2%) C-14- residues of the applied activity were detected after two months in sediments. Clams were major component of the ecosystem and played a significant role in degradation of the insecticide. In the con tinuous flow system chlorpyrifos did not undergo substantial mineralization . Volatilization accounted for 0.8-1% loss during first ten days of applica tion. The amounts of extractable C-14-activity were higher in flooded sedim ents than in moist sediment. More bound residues were formed under moist co nditions. TCP (3,5,6-trichloro-2-pyridinol) was the major degradation produ ct formed under both moist and flooded conditions, its formation being high er in the latter conditions. These studies underline the role of clams in d egradation of chlorpyrifos and lack of microbial degradation. In absence of clams, chlorpyrifos underwent abiotic degradation in marine sediment with formation of bound residues, (C) 1999 Elsevier Science Ltd. All rights rese rved.