Distribution and residue profile of organochlorine pesticides and polychlorinated biphenyls in sediment and fish of Lake Manzala, Egypt.

Sediment and fish (Oreochromis niloticus) samples collected from Lake Manzala were analyzed to assess the spatial distribution of OCPs and 96 PCBs. Relatively higher concentrations of chlorpyrifos, ∑DDT, and HCB were found, particularly at the Bahr Al-Baqar drain station, which has uncontrolled inputs of untreated domestic, agricultural, and industrial wastes. The concentrations of ∑PCBs ranged from 19 to 69 ng/g dw and from 7.4 to 29 ng/g dw for sediment and fish samples, respectively. Ratios of DDT to its metabolites suggest that the source of ∑DDT is from past usage of technical DDT in the regions surrounding the lake. Sediment quality guidelines were exceeded in 88, 75, and 42% of sediments for the Effects Range Low (ERL) for ∑PCBs, ∑DDT, and 4,4'-DDE, respectively. Sediment from the Bahr Al-Baqar drain exceeded the Probable Effects Level (PEL) for DDT isomers 2,4' and 4,4'. All fish samples from Lake Manzala were well below action and tolerance levels set by US EPA for ∑DDT, chlordane, dieldrin, heptachlor, mirex, and PCBs.

HIGHLIGHTS: Distributions of OCPs and PCBs in sediment and tilapia from Lake Manzala were investigated. Chlorpyrifos, ∑DDT, and HCB sediment concentrations were spatially variable and relatively elevated. ∑96PCBs, ∑DDT, and 4,4'-DDE exceeded the Effects Range Low in 88, 75, and 42% of the sediments, respectively. The major input from Cairo, the Bahr Al-Baqar drain, exceeded the Probable Effects Level for DDT isomers in sediments. OCP and PCB concentrations in tilapia were below action and tolerance levels set by the US-EPA.