Pollution and health risk assessment of heavy metals in the surface sediments of Timsah Lake, Suez Canal, Egypt

Abstract

Urbanization and industrial activities around Timsah Lake have led to discharging of pollutants into the lake. The heavy metals pollution level in the lake sediments and implications for living organisms and human health were estimated using several ecological indices. The spatial variations of metals (Cd, Cu, Pb, Mn, Zn, Ni, and Fe) and organic matter content demonstrate that most concentrations increase toward the western part of the lake. The geoaccumulation index (Igeo) arranged the metals as next; Cd > Pb > Zn > Cu > Mn > Fe > Ni, where the lake sediments are extended between moderately-to-extremely contaminated by Cd. Moreover, the contamination factor (CF) for Cd and Pb indicates very high contamination for 100 % of stations and moderate contamination for 58.3 % of the stations, respectively. Spatially, the degree of contamination (Cd) classified lake sediments into three categories; moderately, considerable and very highly contaminated, distributed in the lake's eastern, middle and western parts, respectively. Regarding ecological risk, the potential ecological risk factor (Eri) arranged the metals risks as follows: Cd > Pb > Cu > Ni > Zn, where Cd concentrations suggest high and very high risk for 16.7% and 83.3 % of stations, respectively. The potential ecological risk index (RI) divided lake sediments into moderate, considerable (most of the eastern part), and very high risk (most of the western part). According to sediment quality guidelines (SQGs), Cd values indicate that there have been negative effects on the biota ranging between occasional and frequent. A dermal exposure-based health risk evaluation revealed no non-carcinogenic impact on human health, while Cd indicated a tolerable risk of cancer for children. Moreover, 58.3 and 83.3 % of the stations indicated a tolerable risk of cancer by Ni for adults and children, respectively. The study recommended necessary proactive measures to monitor and manage heavy metal pollution, especially Cd, Pb, and Ni caused by human activities in the Lake.