LAUSR

ABSTRACT The paper reports an assessment of the quality of some watercourses located in three Egyptian governorates by investigation of organochlorine and organophosphorus pesticides residues, and the distribution of macroinvertebrates. Water and sediment samples were collected from the investigated sites in Giza, Qalubeya and Gharbeya governorates. The results showed that the total beta- hexachlorocyclohexane (β-HCH) was the highest in concentration amongst other organochlorine pesticides in both Giza and Gharbeya governorates, and the total Dichlorodiphenyltrichloroethane (DDT) concentration was the highest in Qalubeya Governorate. In the organophosphorus pesticides group, fenitrothion and fenamiphos showed the highest concentrations in all collected samples. In addition, gastropods were the dominant macroinvertebrates, and all sensitive organisms disappeared from all studied sites during all seasons indicating a poor water quality. The investigated watercourses are highly polluted with pesticides residues which have harmful consequences for both aquatic biodiversity and human health.