An Index Approach to Metallic Pollution in River Waters

Twenty water samples from a river system in southern Caspian Sea basin were collected and analyzed for physicochemical parameters and metals (Cu, Zn, As, Cd, Pb, Ni and Mn). In order to evaluate the risk potential of metal pollution in river water, use of two indices namely heavy metal pollution index (HPI) and contamination index (C-d) accompanied by cluster analysis was taken in to consideration. Stations located within the upstream of the river (1 to 13) seemed to encounter low risk potentials while the downstream stations (14 to 20) approved to hold higher risks.The results also showed relatively meaningful correlation among different metals which may be attributed to their same entry source, mainly mining and quarrying activities in the central parts of the basin following by municipal and industrial wastewater discharge to the river in downstream. The convergence of both indices in this study was also of interest. Although the mean values of both indices were below the critical values, severe precautions must be taken into consideration especially in the stations holding high risk potentials. Extreme use of river water for drinking, agriculture and industrial purposes within the water basin, relatively biota-rich characteristic of the river and Caspian Sea as the final sink of the river are among the most significant reasons that make the river monitoring implementation inevitable.