Environmental risk assessment of some potentially toxic elements in El-Tabbin region (Cairo, Egypt)

As much as 24 soil samples and 6 stream sediments from the River Nile were studied in El-Tabbin region (Great Cairo, Egypt). Twelve chemicals, potentially toxic elements posing potential environmental risk, were the object of concern in this study. Mean contents of analysed elements (in mg kg(-1)) in soils and the River Nile stream sediments were the following: As(s) 3.6/As(ss) 1.5, Cd(s) 0.33/Cd(ss) 0.12, Cr(s) 87.7/Cr(ss) 141.5, Cu(s) 40.3/Cu(ss) 43.8, Hg(s) 0.03/Hg(ss) 0.13, Pb(s) 33.3/Pb(ss) 20.2, Zn(s) 150/Zn(ss) 109, Se(s) 0.24/Se(ss) 0.05, Ni(s) 37.2/Ni(ss) 48, Sb(s) 1.25/Sb(ss) 1, Ba(s) 892/Ba(ss) 431, V(s) 103.3/V(ss) 167.8. Furthermore, geochemical background values were derived for soil and stream sediment samples. The values are as follows (in mg kg(-1)): As(s) 1.33/As(ss) 1, Cd(s) 0.48/Cd(ss) 0.05, Cr(s) 54.7/Cr(ss) 106.5, Cu(s) 23.8/Cu(ss) 23, Hg(s) 0.025/Hg(ss) 0.095, Pb(s) 15.3/Pb(ss) 13.5, Zn(s) 70/Zn(ss) 55, Se(s) 0.13/Se(ss) 0.05, Ni(s) 19.5/Ni(ss) 32.5, Sb(s) 1/Sb(ss) 1, Ba(s) 266/Ba(ss) 275, V(s) 50.7/V(ss) 119. More than two-thirds of soil and sediment samples exceeded established (based on literature data) risk limit values for non-polluted environment. Based on environmental risk assessment for potentially toxic elements in soils and sediments in more than 45% of total area disturbed environment (I (ER) = 1-3) was documented and more than 13% of territory was characterised with highly disturbed environment (I (ER) > 3).