Physicochemical and Spatial Distributions of Trace Elements and Organochlorine Compounds in Lake Idku Water, Egypt

Abstract

This study aimed to characterize the water quality of 4 sites in Lake Idku, the third largest wetland region in Egypt regarding the physicochemical indicators, the spatial distributions of certain trace elements and organochlorine compounds (OCs). Most of the tested water quality indicators were above the permissible limits of River Nile water except nitrate was lower than the permissible limits. The distribution and concentrations of Fe, Cu, Zn, Mn, Pb, and Cd significantly differed (p > 0.05) among the sampling sites, where mean concentrations of these trace elements in all the tested sites ranged from 0.0226–0.0392, 0.010–0.098, 0.3570–1.0160, 0.084–0.942, 0.015–0.024, and 0.011–0.023 mg/L, respectively. The west site of the lake contained the highest contents of the trace elements, followed by the east, north, and then south sites. Water collected from the south site had the highest concentrations of Fe and Cu, while those collected from the west site had the highest concentrations of Zn, Pb, and Cd, and samples from the east site had the highest concentrations of Mn. The concentrations of Cu, Zn, Pb, Cd, and Mn in all samples which exceeded the Egyptian regulations, except those collected from the south site which contained levels of Mn that met the regulations. Regarding the residues of OCs, the ∑OCs can be grouped in descending order as follows: north site > east site > west site > south site, with values of 5.632, 5.230, 4.731, and 4.650 µg/L, respectively. All the detected OCs were above the maximum acceptable levels as compared to WHO standards of 0.1 μg/L, except for p,p'-DDT, p,p'-DDD, and p,p'-DDE which were at lower levels. In conclusion, the water quality of Lake Idku may at risk to biota and humans, monitoring, management, and mitigation strategies are urgently required to prevent further pollution by restricting the discharge of industrial and agricultural wastewater into Lake Idku.