Bakshi Madhurima, Ram S S, Ghosh Somdeep, Chakraborty Anindita, Sudarshan M, Chaudhuri Punarbasu
Department of Environmental Science, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, West Bengal, 700019, India.
UGC-DAE Consortium for Scientific Research, Kolkata Centre, Kolkata, India.
Environ Monit Assess. 2017 May;189(5):221. doi: 10.1007/s10661-017-5891-9. Epub 2017 Apr 19.
This work describes the micro-spatial variation of elemental distribution in estuarine sediment and bioaccumulation of those elements in different mangrove species of the Indian Sundarbans. The potential ecological risk due to such elemental load on this mangrove-dominated habitat is also discussed. The concentrations of elements in mangrove leaves and sediments were determined using energy-dispersive X-ray fluorescence spectroscopy. Sediment quality and potential ecological risks were assessed from the calculated indices. Our data reflects higher concentration of elements, e.g., Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Pb, in the sediment, as compared to that reported by earlier workers. Biological concentration factors for K, Ca, Mn, Fe, Cu, and Zn in different mangroves indicated gradual elemental bioaccumulation in leaf tissues (0.002-1.442). Significant variation was observed for elements, e.g., Ni, Mn, and Ca, in the sediments of all the sites, whereas in the plants, significant variation was found for P, S, Cl, K, Ca, Mn, Fe, Cu, and Zn. This was mostly due to the differences in uptake and accumulation potential of the plants. Various sediment quality indices suggested the surface sediments to be moderately contaminated and suffering from progressive deterioration. Cu, Cr, Zn, Mn, and Ni showed higher enrichment factors (0.658-1.469), contamination factors (1.02-2.7), and geo-accumulation index (0.043-0.846) values. The potential ecological risk index values considering Cu, Cr, Pb, and Zn were found to be within "low ecological risk" category (20.04-24.01). However, Cr and Ni in the Sundarban mangroves exceeded the effect range low and probable effect level limits. Strong correlation of Zn with Fe and K was observed, reflecting their similar transportation and accumulation process in both sediment and plant systems. The plant-sediment elemental correlation was found to be highly non-linear, suggesting role of some physiological and edaphic factors in the accumulation process. Overall, the study of micro-spatial distribution of elements can act as a useful tool for determining health of estuarine ecosystem.
这项工作描述了河口沉积物中元素分布的微观空间变化以及印度孙德尔本斯不同红树林物种中这些元素的生物累积情况。还讨论了这种元素负荷对这个以红树林为主的栖息地造成的潜在生态风险。使用能量色散X射线荧光光谱法测定了红树林树叶和沉积物中的元素浓度。根据计算得出的指数评估了沉积物质量和潜在生态风险。我们的数据表明，与早期研究人员报告的数据相比，沉积物中铝、钾、钙、钛、钒、铬、锰、铁、镍、铜、锌和铅等元素的浓度更高。不同红树林中钾、钙、锰、铁、铜和锌的生物浓缩系数表明，这些元素在叶片组织中逐渐发生生物累积（0.002 - 1.442）。在所有采样点的沉积物中，镍、锰和钙等元素存在显著差异，而在植物中，磷、硫、氯、钾、钙、锰、铁、铜和锌存在显著差异。这主要是由于植物吸收和累积能力的差异。各种沉积物质量指数表明表层沉积物受到中度污染且质量在逐渐恶化。铜、铬、锌、锰和镍的富集系数（0.658 - 1.469）、污染因子（1.02 - 2.7）和地累积指数（0.043 - 0.846）值较高。考虑铜、铬、铅和锌的潜在生态风险指数值处于“低生态风险”类别（20.04 - 24.01）。然而，孙德尔本斯红树林中的铬和镍超过了效应范围低值和可能效应水平的限值。观察到锌与铁和钾之间存在强相关性，这反映了它们在沉积物和植物系统中相似的迁移和累积过程。发现植物 - 沉积物元素相关性高度非线性，表明在累积过程中一些生理和土壤因素发挥了作用。总体而言，元素微观空间分布的研究可作为确定河口生态系统健康状况的有用工具。
