Abstract

  Lake Temsah is the end point where some municipal, agricultural and industrial wastewaters are discharged. The lake is connected to the Suez Canal where large volumes of petroleum oil are passed from producing countries in the Arab Gulf to Europe and North America. The lake is the main source of fish for the area of Ismailia and a recreational site where the tourism industry thrives. Recently, numerous complaints have been made about the level of pollution in the lake which affects to a significant extent fishing and tourism industries. In the present study, residues of some chlorinated hydrocarbon pesticides, polycyclic aromatic hydrocarbons and polychlorinated biphenyls were monitored in some of the lake's organisms. Mullet (Mugil cephalus, usually living in the water column), crab (Lupa pelagcus, an intertidal organism) and a bivalve (Ruditapes decussata, a benthic sedentary organism) were selected as representatives of various strata of the lake ecosystem. Residues of an endosulfan, DDE, Dieldrin, heptachlor epoxide and Dicofol were detected. Aroclor residues were not seen. Endosulfan had the highest detected concentration of all organochlorines: concentrations were 24.1, 52.3, 124.8, and 65.6 Fg kg-1 in fish skin, fish gills, fish muscles and bivalves respectively. DDE was the most frequent detected organochlorine, detected in all samples, while Dieldrin was only detected in bivalves and crab. The concentration of polycyclic aromatic hydrocarbons was lowest in fish skin, 2.7 µg kg-1, and highest in bivalves, 48.9 µg kg-1. Fluorine and anthracene were the most frequently detected polycyclic aromatic hydrocarbons compounds, while acenaphthene was the least detected. The highest concentrations of organochlorines and polycyclic aromatic hydrocarbons, 108 and 48.9 µg kg-1, respectively, were detected in bivalves. Bivalves also had the widest spectrum of detected organochlorines and polycyclic aromatic hydrocarbons. All tested organisms showed a higher ability to accumulate organochlorines in comparison to polycyclic aromatic hydrocarbons. Results also showed some indications that factors other than fat content may have some influence on the accumulation of persistent contaminants in biological tissues.

Keywords: organochlorines, accumualation, persistant contaminants, DDE, fluorine, anthracene