Department of Environmental Science, Bangalore University, Bangalore 560 056, India.
Environ Monit Assess. 2012 Jan;184(1):361-73. doi: 10.1007/s10661-011-1973-2. Epub 2011 Mar 25.
The purpose of this research work was to appraise extent of heavy metals in sediment and the degree to which its quality tainted seasonally and spatially in river Cauvery. In this study, heavy metals such as Fe, Zn, Ni, Mn, Pb, Cu, Co, Cd and Cr were analysed in sediments. Results were compared with sediment quality guidelines from various derived criteria. Twenty-five sampling points were selected based on geographical proximity of agricultural fields and industrial discharges; river-tributary confluence points; settlements located along the river bank; ritual and recreational activities. Sampling was done for the period of 3 years (2007 to 2009). Digestion of the samples was done by microwave-assisted digestion technique. Analysis was carried out using flame furnace atomic absorption spectrophotometer, and results are expressed in micrograms per gram. The mean concentration of Fe (11144 μg/g) followed by Mn (1763.3 μg/g), Zn (93.1 μg/g), Cr (389 μg/g), Ni (27.7 μg/g), Cu (11.2 μg/g), Pb (4.3 μg/g), Co (1.9 μg/g) and Cd (1.3 μg/g) remained within the levels of sediment quality guidelines. Multivariate statistical techniques such as principal component analysis and cluster analysis (CA) were employed to better comprehend the controlling factors of sediment quality and spatial homogeneity among the stations. The sediment geo-accumulation index (I(geo)) showed maximum value of Cd (2.69) and least value of Mn (-1.44). The geo-accumulation class (I(geo) class) was in the sequence as follows: Cd>Zn>Pb>Cr>Cu>Co>Ni>Fe>Mn. Negative total geo-accumulation indices (I(tot)) revealed that mean concentration of heavy metals in the river bed sediment are lower than their respective shale values. The statistical analysis of inter-metallic relationship revealed the high degree of correlation among the metals indicated their identical behaviour during transport. This study concludes that insignificant geo-accumulation with metals except Cd (moderate contamination), Pb and Zn (slight contamination) principally in downstream stretch may perhaps deteriorate the sediment quality due to intensification anthropogenic influences. It also proves that extent of existing metal concentrations in sediments of river Cauvery in Karnataka not exceeded the toxic limit, and there is no peril to the aquatic life.
本研究工作旨在评估克里希纳河（Cauvery）中沉积物重金属的含量及其季节性和空间污染程度。本研究分析了沉积物中的重金属，如 Fe、Zn、Ni、Mn、Pb、Cu、Co、Cd 和 Cr。结果与各种衍生标准的沉积物质量指南进行了比较。根据农业用地和工业排放的地理位置接近程度、河流支流汇合点、沿河岸的定居点、仪式和娱乐活动等因素，选择了 25 个采样点。采样时间为 3 年（2007 年至 2009 年）。采用微波辅助消解技术对样品进行消解。使用火焰炉原子吸收分光光度计进行分析，结果以微克/克表示。Fe（11144μg/g）的平均浓度最高，其次是 Mn（1763.3μg/g）、Zn（93.1μg/g）、Cr（389μg/g）、Ni（27.7μg/g）、Cu（11.2μg/g）、Pb（4.3μg/g）、Co（1.9μg/g）和 Cd（1.3μg/g）的浓度均在沉积物质量指南的水平内。主成分分析（PCA）和聚类分析（CA）等多元统计技术被用来更好地理解沉积物质量的控制因素和站点之间的空间均一性。沉积物地质累积指数（I(geo)）显示 Cd 的最大值（2.69）和 Mn 的最小值（-1.44）。地质累积指数（I(geo) 类）的顺序如下：Cd>Zn>Pb>Cr>Cu>Co>Ni>Fe>Mn。负的总地质累积指数（I(tot)）表明，河底沉积物中重金属的平均浓度低于各自的页岩值。金属之间的统计相互关系分析表明，它们在运输过程中表现出高度的相关性。本研究得出的结论是，克里希纳河（Cauvery）除 Cd（中度污染）、Pb 和 Zn（轻度污染）外，金属的地质累积程度不高，主要发生在下游，这可能是由于人为影响的加剧而导致沉积物质量恶化。这也证明了卡纳塔克邦克里希纳河（Cauvery）沉积物中现有金属浓度未超过毒性极限，对水生生物没有危害。
