Evaluation of Heavy Metals Pollution in Seawater, Suspended Particulate Matter and Sediment from Abu-Qir Bay, Alexandria, Egypt

Abstract

The level of heavy metals (Mn, Fe, Co, Ni, Cu, Zn, Pb, and Cd) in seawater, suspended particulate matter (SPM) and sediment along Abu-Qir Bay coast, Alexandria, Egypt, were evaluated by selecting nine stations as hot spots during winter 2020. Resuls showed that, the average concentrations of the investigated heavy metals followed the following order: Fe > Zn > Mn > Ni > Pb > Co > Cu > Cd in seawater, Fe > Zn > Mn > Pb > Cu > Ni > Co > Cd in SPM, and Fe > Mn > Zn > Ni > Co > Cu > Pb > Cd in sediment. Moreover, the distribution coefficient ( 16Kd> ) revealed that, Fe was highly stable in sediments, and the log ( 16Kd> ) value was 6.521 in all water bodies. In addition, geo-accumulation index (Igeo), pollution load index ( 16PLI> ), modified degree of contamination (mCd), potential ecological risk index ( 16RI> ), as well as the mean effect range median quotient ( 16MERM-Q> ) were calculated. Calculations recorded that, the values of Igeo for Cd in surface sediments ranged between 1 and 3 indicating that, the study sites were moderate to strongly contaminated with Cd. The mCd values of Ni, Cu, Zn, Pb, and Cd ranged between 1.32 and 4.24, reflecting a low to moderate degree of contamination. The studied metals presented a moderately toxic ecological risk (150 ≤ RI  > 300). Based on 16MERM-Q>  classification, all samples had medium-low toxicity; Ni, Cu, Zn, and Pb may be originated from anthropogenic sources, whereas Cd emerged from natural sources with some contribution of anthropogenic source. Redundancy analysis (RDA) revealed that the TOC % and fine sand % of the sediment had a certain influence on the Fe enrichment. The data of the water quality index (WQI) revealed that St 2, St 3, St 4, St 5 & St 6 were slightly polluted, and could be considered hot spots.