Chemometric study on the trace metal accumulation in the sediments of the Cochin Estuary-Southwest coast of India.
ABSTRACT The distribution and accumulation of trace metals in the sediments of the Cochin estuary during the pre-monsoon, monsoon and post-monsoon periods were investigated. Sediment samples from 14 locations were collected and analysed for the metal contents (Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb), organic carbon, total nitrogen, total sulphur and grain size. The data were processed using statistical tools like correlation, factor and cluster analysis. The study revealed an enrichment of Cd and Zn in the study area particularly at station 2, which is confirmed by enrichment factor, contamination factor and geoaccumulation index. The factor analysis revealed that the source of Cd and Zn may be same. The study indicated that the spatial variation for the metals like Mg, Cr, Fe, Co, Ni, Cu, Zn, Cd and Pb were predominant unlike Mn which shows a temporal variation. The strong association of trace metals with Fe and Mn hydroxides and oxides are prominent along the Cochin estuary. The anthropogenic inputs of industrial effluents mainly control the trace metals enrichment in the Cochin estuary.
- [Show abstract] [Hide abstract]
ABSTRACT: The Cochin Backwaters in India are part of the Vembanad-Kol system, which is a protected wetland and one of the largest estuarine ecosystems in South Asia. The backwaters are a major supplier of fisheries resources and are developed as tourist destination. Periyar River discharges into the northern arm of the system and receives effluents from chemical, petrochemical and metal processing industries which release huge amounts of wastewaters after little treatment. We investigated water and sediment contamination in the industrial vicinity and at one station further away including organic and inorganic contaminants. In total 83 organic contaminants were found, e.g. well known priority pollutants such as endosulfan, hexachlorobenzene, DDT, hexachlorocyclohexane and their metabolites, which likely stem from the industrial manufacturing of organochlorine pesticides. Furthermore, several benzothiazole, dibenzylamine and dicyclohexylamine derivatives were detected, which indicated inputs from rubber producing facilities. Several of these compounds have not been reported as environmental contaminants so far. A comparison of organic contaminant and trace hazardous element concentrations in sediments with reported sediment quality guidelines revealed that adverse effects on benthic species are likely at all stations. The chemical assessment was combined with an investigation of macrobenthic diversity and community composition. Benthic organisms were completely lacking at the site with the highest trace hazardous element concentrations. Highest species numbers, diversity indices and abundances were recorded at the station with the greatest distance to the industrial area. Filter feeders were nearly completely lacking, probably leading to an impairment of the filter function in this area. This study shows that a combination of chemical and biological methods is an innovative approach to achieve a comprehensive characterization of industrial contamination, to evaluate associated risks for bottom dwelling consumers regarding sediment quality guidelines, and to observe related adverse effects on the benthic community directly in the field.Science of The Total Environment 03/2014; · 3.26 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Lakes in the middle and lower reaches of the Yangtze River form a shallow lake group unique in the World that is becoming increasingly polluted by heavy metals. Previous studies have largely focused on individual lakes, with limited exploration of the regional pattern of heavy metal pollution of the lake group in this area. This paper explores the sources, intensity and spatial patterns of heavy metal pollution of lake sediments. A total of 45 sample lakes were selected and the concentrations of key metal elements in the sediments of each lake were measured. The cluster analysis (CA), principal component analysis (PCA) and Geo-accumulation index (I(g)) analysis permitted analysis of the source and pollution intensity of the target lakes. Results suggested a notable spatial variation amongst the sample lakes. Lakes in the upper part of the lower reach of the Yangtze River surrounded by typical urban landscapes were strongly or extremely polluted, with high concentrations of Pb, Zn, Cu and Cd in their sediments. This was attributed to large amount of untreated industrial discharges and municipal sewage produced within the lake catchments. In contrast, the heavy-metal pollution of lakes in the Taihu Delta area was notably lower due to industrial restructuring and implementation of effective environmental protection measures. Lakes along the middle reach of Yangtze River surrounded by agricultural areas were unpolluted to moderately polluted by heavy metals overall. Our results suggested that lakes in the central part of China require immediate attention and efforts should be made to implement management plans to prevent further degradation of water quality in these lakes.International Journal of Environmental Research and Public Health 01/2013; 10(3):793-807. · 2.00 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Urbanisation has a profound influence on our environment, and its burden is often transferred to aquatic systems. The surface sediments of urban lake systems are severely threatened with major contamination on a daily basis. Empirical evidence gleaned from the study of Akkulam Veli, a tropical urban lake in Southern India, indicates the need to evaluate all factors defining the contamination status of lake systems, rather than the conventional procedure that use Al or Fe, and select normalisers to evaluate metal enrichment in contaminated lake systems. A two step correlation analysis was done using Fe, Al, Co, Mn, Ti and Si as normalisers for Cr, Co, Ni, Cu, Zn and Pb. However, Fe, Al, Co, Mn and Ti are found to be unsuitable as normalisers for various reasons, including the redox condition of the lake for Fe, the geological structure of the lake, with its laterite basin that is conducive to high concentrations of Al, the near-detectable range in many stations that can magnify the enrichment for Co, the escalation in EF values for Mn, and the probability of effluent entry from the nearby titanium-based industry for Ti. Si, which is highly refractory, stable, associated with clay minerals, and unaffected by environmental factors such as reduction/oxidation, adsorption/desorption and other diagenic processes, appears to be the most appropriate normaliser in AV lake sediments. The average EF values calculated using Si as a normaliser are Pb (3.88) > Cr (1.77) > Zn (1.71) > Co (1.34) > Cu (1.29) > Ni (0.94). The results of the study show that this alternate method is more accurate at estimating EF values, which in turn can be employed more precisely to evaluate the extent of anthropogenic contamination in urban lake systems with highly contaminated surface sediments.Journal of Environmental Management 06/2013; 129C:54-61. · 3.06 Impact Factor