Department of Civil Engineering, Architecture and Art, Science and Research Branch, Islamic Azad University, Tehran, Iran.
School of Environment, College of Engineering, University of Tehran, Tehran, 1417853111, Iran.
Environ Sci Pollut Res Int. 2020 Dec;27(36):45639-45649. doi: 10.1007/s11356-020-10298-x. Epub 2020 Aug 15.
Desiccation of the Namak Lake (NL) can result in the release of fine-grained dust contaminated with heavy metals, while there is little information available on the propagation of metals in the bed sediments of this lake. In this study, contamination of metals in the surface sediments of the NL was analyzed and the pollution status of sediments was assessed using geo-accumulation index (I), enrichment factor (EF), the consensus-based sediment quality guidelines (CBSQGs), and mean probable effect concentration quotient (mPECQ). Results indicated that metal concentrations at the southern part were higher than at the middle and northern parts of the lake. Possible reasons are (i) pollution loads mainly entered the lake through the rivers at the west and northwest, but accumulated at the southern parts, (ii) hard layer of salt covering the bottom of the NL at the northern part suppresses adsorption of metals to the sediment, and (iii) the muddy nature of sediments at the southern part makes it easier for metals to be absorbed. EF results showed that sediments at the southern part of the lake were moderately enriched with lead (Pb). The low I values suggested no pollution with the metals, and CBSQG values showed that the sediments of the NL were not toxic, while the mPECQ index suggested a toxicity probability of less than 25%. Cluster analysis classified the metals into two clusters. In general, the results showed that metal pollution in the surface sediments of NL was generally low although the concentration of Pb at the southern part of the lake was worrisome.
纳木错湖的干涸可能导致细颗粒灰尘释放出来，这些灰尘受到重金属的污染，而关于这些重金属在该湖底沉积物中的传播情况，目前信息很少。本研究分析了纳木错湖表层沉积物中金属的污染情况，并利用地积累指数（I）、富集因子（EF）、基于共识的沉积物质量准则（CBSQGs）和平均可能效应浓度商（mPECQ）评估了沉积物的污染状况。结果表明，该湖南部的金属浓度高于中部和北部。可能的原因是：（i）污染负荷主要通过西部和西北部的河流进入湖中，但在南部积累；（ii）纳木错湖北部覆盖着厚厚的盐层，抑制了金属对沉积物的吸附；（iii）南部的沉积物为泥质，使金属更容易被吸收。EF 结果表明，该湖南部的沉积物中铅（Pb）中度富集。低 I 值表明这些金属没有受到污染，CBSQG 值表明纳木错湖的沉积物没有毒性，而 mPECQ 指数表明毒性的可能性小于 25%。聚类分析将这些金属分为两类。总的来说，结果表明尽管该湖南部的 Pb 浓度令人担忧，但纳木错湖表层沉积物中的金属污染总体较低。
