Levels, Sources, Toxicity and Ecological Risk Assessment of OCPs and PCBs in Lake Edku Waters, Egypt

Abstract

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) have the ability to bioaccumulate in food chains and bodies. For Lake Edku, hexachlorocyclohexane (HCH) was isometrically arranged as β > γ > α during both seasons and seasonally arranged as spring> summer. The β-HCH was the most dominant isomer that can be attributed to the biodegradation of α-HCH and γ-HCH to β-HCH. Total Cyclodienes were arranged as Aldrin> Dieldrin> Endrin, and seasonally as spring> summer. The average contributions of DDT congeners mixture detected in Edku Lake waters were in the order of o,p′-DDD> o,p′-DDT> o,p′-DDE> p,p′-DDE>p,p′-DDT > p,p′-DDD during spring and o,p′-DDT> o,p′-DDE> o,p′-DDD> p,p′-DDE and p,p′-DDT > p,p′-DDD during summer; total DDTs recorded higher values during the summer compared to spring. Seasonal distribution is referred to the fact that PCB 28> 52>138> 101> 118> 153> 180 during both seasons. α-HCH/γ-HCH indicated the dominance of lindane. β-/(α+γ)-HCH ratio suggested the recent HCH input for station VI and past input for most stations. DDE/DDD ratios indicate anaerobic and aerobic degradation. (DDE + DDD)/∑DDTs ratios suggesting past input for DDT for most stations during both seasons. o,p′-DDT/p,p′-DDT ratio indicates that stations (I and VIII), as well as station VIII during spring and summer, respectively, recorded technical grade DDT, while the rest of the stations recorded dicofol-type DDT. While, the risk quotient recorded very high risk, except for α-HCH which recorded a moderated risk at some stations. Upon comparing the results of the current study with water quality standards, it was noted that some OCPs and PCBs recorded values higher than the criteria continuous concentration (CCC), while others were higher than the criteria maximum concentration (CMC) during spring and summer.