Heavy metals pollution is a worldwide problem that has grown during the past few decades because of their toxicity, extensive sources, non-biodegradable characteristics, and accumulative behaviors in aquatic environments [1][2][3]. These metals are identified as a significant indicator for degradation of aquatic environments. Enormous quantities of metals are being released into the environment both from anthropogenicrelated processes and natural sources through direct discharge into water or indirectly through stormwater runoff, domestic effluents, fossil fuel combustion, and atmospheric depositions [4]. Heavy metals ultimately Pol. J. Environ. Stud. Vol. 27, No. 2 (2018), 675-688 Original Research
Heavy Metals Contamination and Ecological Risk
AbstractHeavy metal concentrations were determined using inductively coupled plasma-optical emission spectrometry (ICP-OES) in surface sediments of Namal Lake, Pakistan. The metals content in sediment varied significantly and were in the order of Al>Fe>Mn>V>Zn>Cr>Ni>Cu>As>Co>Pb>Cd. Except for Al, the average concentrations of metals were higher than the average value of the upper continental crust (UCC). The significant positive correlations among heavy metals (p<0.01) suggested that these metals originated from the same sources. The pollution indices indicated severe contamination of sediments with As, Cd, and Ni. The sediment quality guidelines (SQGs) revealed that 19.2% of As, 11.5% of Cr, and 88.5% of Ni from all the sampling sites exceeded the probable effect level (PEL). The computed average risk index (RI) of single elements were in the following order Cd(411.9)>As(69.0)>Ni(15.4)>Cu(10.0)>Cr(4.3)> Pb(3.66)>Zn(1.7). Principle component analysis (PCA) extracted three components explaining (76.136%) of total variance of chemical data and were highly to moderately loaded with Fe, Mn, Co, Cu, Zn, Al, As, Cd, Ni, V, Cr, TOC, pH, CaCO 3 , and Pb in three principal components (PCs). The results obtained from cluster analysis, correlation of heavy metals, and principal component analysis suggested the origin of metals from both anthropogenic and natural sources.