Document Type : Original Article
Authors
1
Geology and Physics Department, Freshwater Division, National Institute of Oceanography and Fishers-Cairo
2
National Institute of Oceanography and Fisheries, Cairo, Egypt
3
Geology and Physics Department, Inland and Freshwater Branch, National Institute of Oceanography and Fishers, Cairo, Egypt.
4
Geology Dept. Faculty of Sciences Menoufiya University
5
Geology Department, Faculty of Science, Menoufia University, Menofia Governorate, Egypt.
6
Geology Department, Faculty of Science, Menoufia University, Menofia Governorate, Egypt
Abstract
The saline continental Qaroun Lake is situated in the deepest part of the Fayoum mega depression (~2580 km2 size) within the Western Desert of Egypt. It covers an area of about 245 Km2 and descends 45 meters below sea level. The lake represents the lowest land in the Nile River floodplain and plays a crucial role as the ultimate stop for both natural (subsurface flow) and artificial (agricultural) drainage in the Fayoum Depression. Hence, it collects most industrial and agricultural wastes including heavy metals as well as fertilizer and pesticides wastes. With continuous evaporation, the concentrations of heavy metals increase, and environmental problems worsen in Lake Qaroun. Twenty-five samples were selected for chemical analysis by XRF.The main objective of the present study is to investigate the ecological risk of heavy metals pollution in the recent sediments of Qaroun Lake. For the environmental assessment of Lake Qaroun sediments, four pollution indicators including three single indices were employed: The Enrichment Factor (EF), Index of Geo-accumulation (IGeo), and Contamination Factor (CF), along with the integrated Pollution Load Index (PLI). The results revealed that the distribution of the measured heavy metals over the lake was found in the range of (0.55 – 7.72%), (227 – 1840 ppm), (43 – 174 ppm), (24 – 76 ppm), (18 – 42 ppm), (48 – 114 ppm), (31 – 94 ppm), (21 – 49 ppm), and (583 – 4944 ppm) for Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Lead (Pb), Cobalt (Co), Nickel (Ni), Rubidium (Rb), and Strontium (Sr); respectively. Another way combines indices like the degree of pollution (Cd), ecological risk factor (RI), and potential ecological risk index (RI). These indices are instrumental in assessing heavy metal contamination in sediment. All parts of Qaroun Lake show high contamination levels (Cd). The ecological risk factor (RI) indicates no contamination in most stations, except for one close to the polluted El-Wadi drain. Importantly, the potential ecological risk index (RI) is consistently low in all stations around Qaroun Lake, providing reassurance about the lake's current state.
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