Investigating the Spatial Trends in the Level of Organic Contaminants in the Ethiopian Rift Valley Lakes Using Semipermeable Membrane Devices.

Abstract

Organic pollutants in the Ethiopian Rift Valley Lakes are the major factors that contribute to severe environmental problem. SPMDs were deployed for the analysis of selected organic pollutants for 1 month at 2 sites in Lakes Hawassa, Ziway and Koka, Ethiopia. From SPMDs placed in the three lakes, the predominant OCPs were DDT which comprise 67% and followed by endosulfan 23% of the total organochlorine pesticides (OCPs) retrieved. The highest level of OCPs, in general, was found in the SPMDs deployed in Lake Ziway with the mean concentration of 308.5ng/SPMD. However, the concentrations of polychlorinated biphenyls (PCBs) were the highest in the SPMDs deployed in Lake Hawassa with mean concentration of 50.2ng/SPMD. Spatial variation on the accumulation of OCPs and PCBs among the lakes depends on the shoreline activities, distance of the lakes from point and non-point sources, and the biofouling factors.