Residue levels of organochlorine pesticides in some ecosystem components of Manzala Lake M. M. Azab & A. A. Darwish & Hend A. Mahmoud & Fayza A. Sdeek Received: 3 March 2013 / Accepted: 26 June 2013 # Springer Science+Business Media Dordrecht 2013 Abstract To evaluate the organochlorine pesticide (OCP) contamination of Manzala Lake, its ecosystem was investigated during the winter season (December to March). The studied ecosystem components were water, sediment, aquatic weeds, and fishes in four locations. The samples were analyzed by gas chroma- tography with electron capture detector. Pollutant levels of total OCPs showed significantly high levels in the water areas of Round road (46.253 ng/ml), Port- Said Damietta road (19.301 ng/ml), followed by Bughas El-Rasoah (5.539 ng/ml), then Ashtoum El Gamel (natural reserve area now) (0.289 ng/ml). Or- ganochlorines were detected in sediment only in Round road (3.359 μg/kg) and Port-Said Damietta road (0.171 μg/kg) by significant order while they were undetectable in Ashtoum El Gamel and Bughas El- Rasoah. Total OCPs in aquatic weeds ranged between 0.194 μg/kg in Port-Said Damietta and 0.026 μg/kg in Ashtoum El Gamel. While OCPs were 0.160 and 0.153 μg/kg in Round road and Bughas El-Rasoah, respectively. Concerning fish muscles OCPs were sig- nificantly higher in the Round road area (0.397 μg/kg) followed by the Port-Said Damietta road (0.258 μg/kg), and finally, Ashtoum El Gamel samples (0.126 μg/kg). The results revealed the direct relation for the accumu- lation of OCPs between studied ecosystem parameters at the Manzala Lake during the winter season. Results also demonstrated that fish samples collected from the Manzala Lake in the studied areas were contaminated with levels of organochlorines, not higher than the maximum permissible level recorded by FAO/WHO, and that the public is not at risk with fish consumption. Keywords Ecosystem . Pollution . Organochlorine pesticides . Gas chromatography Introduction Manzala Lake has been gradually transformed from being a basically marine environment to a freshwater system. This occurred in response to the increased freshwater inputs and nutrient loading associated with agricultural land reclamation and urban waste disposal. These in- creased the pollution effect and dramatically changed its ecosystem. Pesticide contamination of river and lake wa- ters from agricultural use is a problem of worldwide importance. Manzala Lake is located on the Northeastern edge of the Nile Delta and discharges to the Mediterranean Sea. The lake is exposed to pollutants from industrial, domestic, and agricultural sources. Pollutants have severe- ly impacted the lake and now threaten the Mediterranean Sea (Chikuni et al. 1997; Mageed 2007; Bauer et al. 2010). Manzala Lake is a highly dynamic aquatic system that has undergone considerable physical, chemical, and Environ Monit Assess DOI 10.1007/s10661-013-3330-0 M. M. Azab (*) : A. A. Darwish Plant Protection Department, Benha University, Benha, Egypt e-mail: azabmohamed@hotmail.com H. A. Mahmoud : F. A. Sdeek Residue Analysis Department, Central Agri. Pesticides Lab, Dokki, Egypt