Assessment of trace metal contamination in a historical freshwater canal (Buckingham Canal), Chennai, India.

The present study was done to assess the sources and the major processes controlling the trace metal distribution in sediments of Buckingham Canal. Based on the observed geochemical variations, the sediments are grouped as South Buckingham Canal and North Buckingham Canal sediments (SBC and NBC, respectively). SBC sediments show enrichment in Fe, Ti, Mn, Cr, V, Mo, and As concentrations, while NBC sediments show enrichment in Sn, Cu, Pb, Zn, Ni, and Hg. The calculated Chemical Index of Alteration and Chemical Index of Weathering values for all the sediments are relatively higher than the North American Shale Composite and Upper Continental Crust but similar to Post-Archaean Average Shale, and suggest a source area with moderate weathering. Overall, SBC sediments are highly enriched in Mo, Zn, Cu, and Hg (geoaccumulation index (I(geo)) class 4-6), whereas NBC sediments are enriched in Sn, Cu, Zn, and Hg (I(geo) class 4-6). Cu, Ni, and Cr show higher than Effects-Range Median values and hence the biological adverse effect of these metals is 20%; Zn, which accounts for 50%, in the NBC sediments, has a more biological adverse effect than other metals found in these sediments. The calculated I(geo), Enrichment Factor, and Contamination Factor values indicate that Mo, Hg, Sn, Cu, and Zn are highly enriched in the Buckingham Canal sediments, suggesting the rapid urban and industrial development of Chennai Metropolitan City have negatively influenced on the surrounding aquatic ecosystem.

Accumulation of total trace metals due to rapid urbanization in microtidal zone of Pallikaranai marsh, South of Chennai, India.

The article presents the results for enrichment of total trace metals (TTMs) from Pallikaranai salt marsh in South Chennai, a metropolis on the southeast coast of India. TTMs Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, Sr, V, and Hg along with sediment texture, OC, and CaCO3 were analyzed in 36 surface sediments collected during August 2008 to recognize and observe the input of TTMs in the marsh from various sources in the city limits. In view of the rapid urbanization and industrialization in Chennai City, especially on the southern side, uncontrolled input of sewage, garbage, and industrial effluents into the Pallikaranai marsh land, the elevated concentrations are not surprising. The level of enrichment of TTMs has also increased by 20% to 60% for most of the elements when compared with all other ecosystems in the world as well as the nearby area. The results also indicate that the marshy region is more heavily contaminated with Cd, Hg, Cr, Cu, Ni, Pb, and Zn than other regions on the southeast coast of India. The Enrichment Factor, Contamination Factor, and I (geo) indexes are calculated, and these values are useful to assess the degree of pollution in sediments. The spatial distributions of TTMs are also controlled by other factors like geochemical, precipitation, and flocculation of particulate substances in the marsh. The results of the present study suggest the need for a regular monitoring and management program which will help to improve the quality of Pallikaranai pristine marsh land.

A comprehensive geochemical evaluation of the water quality of River Adyar, India.

The River Adyar flows through the fault of south Chennai for about 50 Km and enters into the Bay of Bengal. This river is almost stagnant and do not carry enough water except during rainy season. Rapid industrialization and urbanization along the river course during 80s and 90s of last century has increased the pollution of the river water. The main objective of this study is to identify and assess the nature of pollution. In order to achieve this objective, necessary geochemical parameters were determined and the quality of water is evaluated using various tools, such as Wilcox diagram, USIS, Piper, sodium absorption ratio (SAR), 3D scattered diagrams, and seasonal variation diagrams. The monsoonal variations in the data matrix of the river water (River Adyar) was monitored at 33 stations for the premonsoon and postmonsoon periods during September 2005 and February 2006.