Bala Krishna Prasad M, Ramanathan A L, Shrivastav Sunil Kr, Saxena Rajinder
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, India.
Environ Monit Assess. 2006 Oct;121(1-3):77-102. doi: 10.1007/s10661-005-9108-2. Epub 2006 Jun 7.
The Fractionation of Fe, Zn, Cu, Pb, Mn and Cd in the sediments of the Achankovil River, Western Ghats, India using a sequential extraction method was carried out to understand the metal availability in the basin for biotic and abiotic activities. Spatial distribution of heavy metals has been studied. Sediment grain size has significant control over the heavy metal distribution. The fluctuations in their concentration partly depend upon the lithology of the river basin and partly the anthropogenic activities. The sediments are dominated by sand and are moderately to strongly positively skewed and are very leptokurtotic in nature. The quartzite and feldspars are abundant minerals along with significant amount of mica with low clay content. The core sediments show increasing trend of heavy metal concentration with depth due to the recent addition of anthropogenic sources and post-diagenic activities. Significant amount of Cd (18%) was found in carbonate fraction, which may pose environmental problems due to its toxic nature. Small concentrations of metals, except Cd and Cu, are in exchangeable fraction, which indicate low bio-availability. Enrichment Factor (EF) for individual metals shows the contribution from terrregious and in part from anthropogenic sources. Selective Sequential Extraction (SSE) study shows the variation in specific metal distribution pattern, their distribution in different phases and their bio-availability. Maximum amount of the metals were bound to the non-residual fractions (mainly Fe-oxides). Overall, bio-availability of these micronutrients from sediments seems to be very less. Non-residual phase is the most important phase for majority of heavy metals studied. Among the non-residual fraction, maximum amount of the heavy metals bound to Fe-oxides. The study high lights the need for in-depth study of heavy metals distribution and fractionation in the smaller river basins to get precise information on the behavior and transport of heavy metals in the fluvial environment and their contribution to the world ocean.
采用连续萃取法对印度西高止山脉阿昌科维尔河沉积物中的铁、锌、铜、铅、锰和镉进行了分级，以了解该流域内金属在生物和非生物活动中的有效性。研究了重金属的空间分布。沉积物粒度对重金属分布有显著控制作用。其浓度的波动部分取决于流域的岩性，部分取决于人为活动。沉积物以砂为主，呈中度至强烈正偏态，本质上非常尖峰态。石英岩和长石是丰富的矿物，还有大量云母，粘土含量低。由于近期人为源的增加和成岩后活动，岩芯沉积物中重金属浓度随深度呈增加趋势。在碳酸盐组分中发现了大量的镉（18%），由于其毒性，可能会带来环境问题。除镉和铜外，其他金属的浓度较低，处于可交换组分中，这表明生物有效性较低。各金属的富集因子（EF）显示了陆源和部分人为源的贡献。选择性连续萃取（SSE）研究显示了特定金属分布模式的变化、它们在不同相中的分布及其生物有效性。大部分金属与非残留组分（主要是铁氧化物）结合。总体而言，这些沉积物中微量营养素的生物有效性似乎非常低。对于大多数研究的重金属来说非残留相是最重要的相。在非残留组分中，大部分重金属与铁氧化物结合。该研究强调需要对较小流域内的重金属分布和分级进行深入研究，以获取关于河流环境中重金属行为和迁移及其对世界海洋贡献的精确信息。
