Assessing pollution in Izmir Bay from rivers in western Turkey: heavy metals

Abstract

Urban rivers having different catchment areas and properties are investigated in order to infer their heavy metal contribution to the Izmir Inner Bay. The concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in the waters and sediments of these rivers were measured and compared with the limit values given in the Sediment Quality Guidelines and Screening Quick Reference Tables (SQuiRTs). Metal concentrations in the sediments were determined to be between 0.5 and 3.5 mg kg⁻¹, 10 to 221.5 mg kg⁻¹, 28 to 153.5 mg kg⁻¹, 13 to 103.5 mg kg⁻¹, 31.5 to 157 mg kg⁻¹, and 124 to 1065.5 mg kg⁻¹ for Cd, Cr, Cu, Ni, Pb, and Zn, respectively. Higher metal concentrations in river waters were observed in rainy seasons, and Cu and Zn were frequently found above the critical limits. The correlations between the concentrations in waters, sediments, and wash off fluxes of the river catchments were statistically investigated and evaluated. Strong correlations between Ni–Cr (r = 0.618, p < 0.01), Ni–Zn (r = 0.578, p < 0.01), and Zn–Pb (r = 0.590, p < 0.01) concentrations in water were found. The metal load entering the inner bay was found to be 28.2 tons per year. The fluxes (mg m⁻² per day) were generally high in large catchments with high annual flows, in regions with high runoff coefficients, and in areas hosting industrial activities. The strong correlations between the heavy metal fluxes suggest that the atmospheric pollution, which influences the whole city, may be the major source of these metals.