ENVIRONMENTAL RISK ASSESSMENT AND CHEMICAL CONTAMINATION WITH HEAVY METALS IN THE SEDIMENTS OF THREE DRAINS, SOUTH OF MANZALA LAKE (EGYPT)

Six heavy metals (Fe, Cd, Co, Cr, Ni, and Pb) were measured in all 15 sediment samples collected from three drains south of Manzala Lake (Egypt). The possible environmental risks of heavy metals in the sediment of the three drains were investigated using soil indices and risk assessment. Results showed that heavy metal contamination was found at the studied sites along the three drains, and pollution levels varied depending on metals and sites. The mean concentration (mgkg-1) ranked in the order of Fe (3950) > Cd (22.36) > Cr (21.15) > Co (19.01) > Pb (14.16) > Ni (10.40) for Faraskour drain, Fe (5068) > Cd (30.29) > Co (18.97) > Cr (16.90) > Ni (15.03) > Pb (12.16) for Al-Etaiwy drain and Fe (56.12) > Cd (19.60) > Co (17.15) > Ni (14.88) > Cr (10.10) > Pb (10.03) for Ramsis drain. The mean ranges of enrichment factor for Cd, Co, Pb, Ni and Cr were 167.5-3858, 6.11-51.78, 4.3831.20, 1.07-11.84 and 0.61-7.43, respectively. The average degree of contamination revealed that the majority of the sites had reached very high levels of pollution, with the exception of site 1, which had reached a moderate level of contamination. The ecological risk of heavy metals can be ranked as follows: Cd > Co > Pb > Ni > Cr, and the potential ecological risk index (PERI) were 931.0, 1173 and 818.5 in the Faraskour, Al-Etaiwy and Ramsis drains, respectively. To decrease pollution in these drains, it was determined that more effective restrictions on Cd and Co were needed. In general, the mean levels of Cr, Ni, and Pb in sediments from the three drains are within the European Union (EU) and Canadian Soil Quality Guidelines (CSQGD), Cd higher than EU and CSQGD, and Co higher than EU but lower than CSQGD.