Microbial Effects on Geochemical Parameters in a Tropical River Basin

Domestic sewage discharge and live stocks are the main sources of pathogenic contaminations in rivers. The river Tamiraparani in southern India is affected by such non-point source pollution throughout the year. We collected a total of 264 samples (water and sediment) from 22 locations in 2-month intervals during a period of 1 year. Bacteriological analysis such as total viable counts (TVC), total coliform (TC), total Streptococcus (TS), Vibrio like organisms (VLO) and five pathogens as well as 12 geochemical parameters (pH, EC, TDS, Cl, HCO3, Ca, Mg, Na, K, PO4, other nutrients and total hardness) were studied. Principal Component Analysis (PCA) and correlation analysis proved that microbial communities were separated with geochemical parameters in order to gain their efficacy. Factor analysis confirmed separate loading rates of microbial (32.3 %) and geochemical (32.7 %) parameters representing ‘allochthonous – geochemical’ and ‘fecal matters – microbial’ interactions, respectively. We used geographical information systems (GIS) for mapping the occurrence of indicator organisms from non-point sources throughout the river basin.