S. Vasudevan

Application of water quality index for groundwater quality assessment: Thirumanimuttar sub-basin, Tamilnadu, India

An attempt has been made to understand the hydrogeochemical parameters to develop water quality index in Thirumanimuttar sub-basin. A total of 148 groundwater samples were collected and analyzed for major cations and anions. The domination of cations and anions was in the order of Na>Mg>Ca>K for cations and Cl>HCO3 >SO4 in anions. The hydrogeochemical facies indicate alkalis (Na and K) exceed alkaline earths (Ca and Mg) and strong acids (Cl and SO4) exceed weak acid (HCO3). Water quality index rating was calculated to quantify overall water quality for human consumption. The PRM samples exhibit poor quality in greater percentage when compared with POM due to effective leaching of ions, over exploitation of groundwater, direct discharge of effluents and agricultural impact. The overlay of WQI with chloride and EC correspond to the same locations indicating the poor quality of groundwater in the study area. SAR, Na%, and TH were noted higher during both the seasons indicating most of the groundwater locations not suitable for irrigation purposes.

Heavy metal distribution in surface sediments of the Tirumalairajan river estuary and the surrounding coastal area, east coast of India

Surface sediments collected at the Tirumalairajan river estuary and their surrounding coastal areas were analyzed for the bulk metal concentration. The sediments were collected from post- and premonsoon seasons. Dominances of heavy metals are in the following order: Fe > Mn > Zn > Pb > Cu in both seasons from estuary and coastal area. The results reveal that Fe, Mn, Cu, Pb, and Zn demonstrated an increased pattern from the estuary when compared to the coastal area. The heavy metal pattern of the sediments of the Tirumalairajan river estuary and its surrounding coastal area offered strong evidence that the coastal area was a major source of heavy metals to the estuarine region. For various metals, the contamination factor and geoaccumulation index (Igeo) have been calculated to assess the degree of pollution in sediments. The contamination factor and geoaccumulation index show that Zn, Pb, and Cu unpolluted to moderately pollute the sediments in estuarine part. This study shows the major sources of metal contamination in catchment and anthropogenic ones, such as agriculture runoff, discharge of industrial wastewater, and municipal sewage through the estuary and adjoining coastal area.

Spatial Distribution of Grain Size Characteristics and its Role in Interpreting the Sedimentary Depositional Environment, Kodaikanal Lake, Tamil Nadu, India

The surface sediments of Kodaikanal Lake is situated in the palani hills at an altitude of 2,285 m above sea level, the geo co-ordinates of the lake are lies between 10°14’ N latitude and 77°28’ E longitudes. In the present study determination of grain size and its deposition environment were carried out for surface sediments collected from different parts of the Lake. The study permits to infer the changes in the depositional environment during the period of infilling at the sites. The spatial distribution of Mean size of the sediments varies from medium sand to medium silt, moderately well sorted to very poorly sorted characteristics, near- symmetrical to very fine-skewed type, and falling in platykurtic to very leptokutic nature. United State Department of Agriculture (USDA) textural triangle plot expresses sediments are clustered tightly in silty sand variable, and its type ranges falls within the field of Loamy sand, sand, sandy loam and silty loam fractions. Thus, the Lake sediments are dominance of silt and sand fractions. Multivariant statistics (discriminant analysis) express that the plots fall scattered in Turbidite and Aeolian environment. The Bivariate textural plot falls in Quiet water environment. The polymodel nature of the sediments also implies that transportation by rolling, sliding, saltation and suspension processes in the Kodaikanal Lake.