Assessment of Hydrogeochemical Characteristic in an Urbanized Estuary using Environmental Techniques

Abstract

Assessment of spatial variat ion in hydrogeochemical characteristics was studied in a tropical estuary, Cochin India. Noticeable spatial variations was observed in transparency, turbidity, salinity, PO4 3- -P, NH4 + -N, d issolved Cd and Hg. Light limitat ion due to high turbidity reduced the primary production, even under high nutrient conditions. An enrichment of both dissolved and sediment Cd, Pb and Hg were noticed in the harbour region associated with high organic carbon and silty-clay fraction. The mu ltivariate statistical methods such as factor analysis (FA), cluster analysis (CA), canonical corre- spondence analysis (CCA) and analysis of variance (ANOVA) were emp loyed to appraise and interpret co mplex hydro- geochemical data, to categorize pollution sources for better understanding about various biogeochemical processes. CA and CCA showed a meaningful classificat ion of estuarine samples based on spatial criteria. Statistical analysis revealed that Secchi disk depth (SD), water salin ity, NO2 - -N, NO3 - -N, dissolved oxygen (DO), total phosphorus (TP), total nit rogen (TN), petroleum hydrocarbon (PHC), sediment pH, organic carbon (SOC) and Pb were the most crucial parameters influencing the hydrogeochemistry of the estuary.