Satapathy D R, Panda C R
Environment and Sustainability Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar, 751013, Odisha, India,
Environ Monit Assess. 2015 Jan;187(1):4133. doi: 10.1007/s10661-014-4133-7. Epub 2014 Dec 6.
The research depicts the spatial and temporal variation of major and trace metals in marine sediments at various monitoring stations of Dhamra estuary, Bay of Bengal, Odisha. The concentration and distribution of selected metals in surface sediments of the estuary were studied in order to assess the spatial extent of anthropogenic inputs viz., mining activities and to estimate the effects of seasonal variations on geochemical processes in this particular tropical estuarine system. Surface sediments reflect the presence of trace and major metals in parts per million, and the concentrations vary in the range of Cu (0.083 to 127.2), Ni (17.35 to 122.8), Co (1.2 to 31.58), Pb (0.8 to 95.86), Zn (12.1 to 415), Cd (0 to 11) and Cr (35.21 to 5,890), Fe (7,490 and 169,100), Mn (20 to 69,188), Ca (10 to 10,520), Mg (990 to 28,750), Na (300 to 51,700), and K (1,100 to 30,010). The comparison of spatial distribution of metal contents using GIS in marine sediments indicates that there is a substantial anthropogenic input in the Dhamra estuary. The enrichment of Cr is ascribed to the sedimentation of Brahmani River, passing through the mining region and discharging Cr pollutant to the sea. Similarly, the sources of Cd are attributable to corrosion-resistant paints used by a large number of trawlers. Contamination factor has been calculated for various metals to assess the degree of pollution. As per Hakanson's classification, Cr indicates very high contamination with considerable contamination of Cd, whereas moderate contamination of Pb, Zn, and Mn are observed in marine sediments. Pollution load index also indicate that there is deterioration of site quality in premonsoon season, which almost attains the baseline level in post monsoon and perfection in monsoon season (Tomlinson et al. (Helgolander Wissenschaftliche Meeresuntersuchungen, 33, 566-572, 1980)). The geoaccumulation index shows that the metal concentrations in sediments can be considered as background levels except Cr and Cd. The geoaccumulation index shows that Cr is moderately contaminated and it is higher in offshore region in post monsoon and monsoon than premonsoon season. All the calculated indices show that Cr and Cd levels are more than the desired limits in the marine sediments. Multivariate statistical analysis evaluates the plausible sources of contaminants, attributing to mining, industrial, and urban wastes by way of Brahmani River discharging to the estuarine region.
该研究描绘了孟加拉湾奥里萨邦达姆拉河口各监测站海洋沉积物中主要和痕量金属的时空变化。为了评估人为输入（即采矿活动）的空间范围，并估计季节变化对这个特定热带河口系统地球化学过程的影响，对河口表层沉积物中选定金属的浓度和分布进行了研究。表层沉积物中痕量和主要金属的含量以百万分之一计，其浓度范围为：铜（0.083至127.2）、镍（17.35至122.8）、钴（1.2至31.58）、铅（0.8至95.86）、锌（12.1至415）、镉（0至11）、铬（35.21至5890）、铁（7490至169100）、锰（20至69188）、钙（10至10520）、镁（990至28750）、钠（300至51700）和钾（1100至30010）。利用地理信息系统（GIS）对海洋沉积物中金属含量的空间分布进行比较表明，达姆拉河口存在大量人为输入。铬的富集归因于布拉马尼河流经矿区并将铬污染物排放到海中的沉积作用。同样，镉的来源可归因于大量拖网渔船使用的防腐漆。已计算出各种金属的污染因子以评估污染程度。根据哈坎森的分类，铬显示出极高的污染，镉有相当程度的污染，而在海洋沉积物中观察到铅、锌和锰有中度污染。污染负荷指数还表明，季风前季节场地质量恶化，在季风后季节几乎达到基线水平，在季风季节达到良好状态（汤姆林森等人，《黑尔戈兰海洋科学研究》，33，566 - 572，1980）。地累积指数表明，除铬和镉外，沉积物中的金属浓度可视为背景水平。地累积指数表明铬受到中度污染，在季风后和季风季节近海区域的污染程度高于季风前季节。所有计算出的指数都表明，海洋沉积物中铬和镉的含量超过了期望限值。多变量统计分析评估了污染物的可能来源，这些污染物通过布拉马尼河流入河口区域，归因于采矿、工业和城市废物。
