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.
"Lake sediments are generally recognized as a sink for many substances in aquatic systems and are also a potential source of dissolved and particulate-bound contaminants to overlying waters, resulting in adverse effects on aquatic ecosystems (Segura et al., 2006). Coal combustion, high-temperature processing of ores, and agricultural practices have been identified as input pathways of toxic metals for lake sediments (Dassenakis et al., 2003; Deepulal et al., 2012; Gao et al., 2005; von Gunten et al., 1997). Balogh et al. (1999) and Birch et al. (1996) pointed out that lake sediments can provide a stable archive of past and present inputs of trace metals to a lake, permitting reconstruction of the historical record. "
[Show abstract][Hide abstract] ABSTRACT: A systematic geochemical lake sediment survey has been carried out in major freshwater lakes in China. Surface lake sediment (0–20 cm) at a density of 1 sample/4 km2 and deep lake sediment (150–180 cm) at a density of 1 sample/16 km2 were collected and analyzed with standard procedures. This overview provides a current ecological risk assessment for toxic metals contamination (As, Cd, Cr, Cu. Hg, Ni, Pb, and Zn) in the surface sediments of major freshwater lakes in China. Lake sediment in China poses a moderate ecological risk on a nationwide basis using a potential ecological risk index (PERI).Mercury ranked as presenting the greatest ecological risk, followed by Cd, As, Pb, Cu, Ni, Cr, and Zn. Liangzi Lake was classified as having high ecological risk; Dalonghu Lake, Dianchi Lake, Dongting Lake, Fuxian Lake, and Qilu Lake as having moderate ecological risk; while the other surveyed lakes were classified as having low ecological risk. Uncertainties of risk assessment are also discussed by considering geochemical background, the eco-toxicity of metals and the sensitivities of local benthic communities. These comprehensive findings have provided valuable information for improvement of lake management and pollution prevention and control in China.
"). Balachandran et al. (2006) reported that geochemical behavior of the metals in estuary is controlled by anthropogenic forces, whereas the coastal environment remained free from contaminants as the metals are rapidly removed by the coastal currents and biogenic association. Deepulal et al. (2012) also confirmed the predominant role of anthropogenic inputs of industrial effluents in controlling the trace metals enrichment in the Cochin estuary. It was reported that incidence of high levels of Cd, Cu, Pb and Zn in the estuarine sediments, corresponded to the anthropogenic inputs from upstream and co-precipitation of iron hydroxide along with scavenging of other metals (Shajan, 2001; Balachandran et al., 2005; Balachandran et al., 2006). "
"Heavy metals such as cadmium, lead, copper and zinc are principal pollutants of aquatic ecosystems because of their environmental persistence, toxicity and great potential of accumulation in the food chains [1,2,3]. They enter the aquatic system through river flow or atmospheric deposition, and can be transported to the sediments immediately through absorption and sedimentation processes by suspended matters [4,5]. Thus, sediments are recognized as important sinks of heavy metals and they reflect the quality of an aquatic system. "
[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 03/2013; 10(3):793-807. DOI:10.3390/ijerph10030793 · 2.06 Impact Factor
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