Water quality concern in the Amaravathi River Basin of Karur district: a view at heavy metal concentration and their interrelationships using geostatistical and multivariate analysis

摘要

Several textile and bleaching industries in the city of Karur, discharge their effluent and was mixed with municipal sewage let into the river Amaravathi at different discharge points. Concentration of trace elements (Cd, Pb, and Ni) exceeded their permissible limits (.003, .01, and .02?ppm, respectively) prescribed by the World Health Organization. C _(d ) (Degree of contamination) and HEI (Heavy metal evaluation index) values were calculated, C _(d ) value of 50% samples have 4 indicates low degree of contamination and for groundwater samples only one-third samples were observed in low pollution and the remaining samples fall in medium to high degree of pollution. HEI value indicates that the average value (12.510, 12.514, and 12.164) of both the samples were above the low pollution range. Good positive correlations observed for Mn, Ni, and Fe with r value from .522 to .913. Principal component analysis (PCA) was used to analyze the data and to identify possible sources of these heavy metals. Three factors for surface water and two factors for groundwater were extracted, where the first three factors account for approximately 58.7% of the total variance of the data-set. The results of groundwater samples show that the factor 1 and 2 accounted for 74.508 and 71.261% of the total variance. The data thus obtained are a sign of anthropogenic and mineral source for these elements in river and groundwater. The spatial distribution map based on ordinary kriging showed that elevated concentrations of heavy metals were located in the upper and down streams of the Amaravathi River basin. The dominance of heavy metals in groundwater and surface water of the Amaravathi river followed the sequence as Pb??Fe??Zn??Cd??Cu??Ni??Mn: Pb??Zn??Cd??Fe??Cu??Ni??Mn, respectively.