Assessment of sediment quality of the Qalubiya drain and adjoining soils, Eastern Nile Delta, Egypt

Qalubiya drain suffers from the presence of large quantities of pollutants as a result of receiving industrial and sewage water from several governorates through which it passes. Some of the agricultural fields surrounding the drain are irrigated with untreated water, and the sediments of its banks are also used for soil fertilization. To assess the accumulation risk of pollutants in the soil of these agricultural fields, Fe, Mn, Cu, Zn, Pb, Ni, Cd, Co, Cr, Hg metals were measured by atomic absorption spectrophotometer. Forty-one surface sediment samples collected from the drain banks and the neighboring wastewater-irrigated soils. The potential ecological index results demonstrated that the sediments of the studied drain are at a very high risk of being contaminated with Hg (3695), Cd (3017), Pb (634), Co (572), Cu (343), and at high-risk contamination of Ni (316). Also, there is considered a risk of being contaminated with Cr (84) and Zn (79). However, wastewater-irrigated soils were higher contaminated with Co, Cr, and Hg. The results of contamination factor and enrichment factor indicated that the source of the heavy metals was referred to wastewater plants, illegal domestic sewage pipes, and garbage collection sites. Besides, the Qalubiya drain showed higher levels of Ni, Cu, Zn, Pb, Cd, Co, and Cr than some ecotoxicological values as their levels in shale background, their average concentrations in the earth’s crust, the lowest effective level of metals, the severe effect levels, and even the recommended maximum limit of heavy metals.