紫坪铺水库淤积物物化特性分析及重金属污染评价

李洪 由丽华 李昆鹏 石华伟 王丹柏

摘 要：為了掌握紫坪铺水库淤积物的物化特性及重金属污染特征、给淤积物多途径资源利用提供理论依据，基于库区21个淤积物深层样品测定结果，采用重金属地累积指数法、富集系数法及潜在生态风险指数法，对紫坪铺水库淤积物物化特性及重金属污染风险进行了分析评价。结果表明：截至2020年10月，紫坪铺水库淤积物总量为1.952亿m3，其中黏土约0.381亿m3、粉细沙约1.424亿m3、中粗沙及卵石约0.147亿m3，分别占淤积物总量的19.5%、73.0%、7.5%;淤积物湿容重平均值为1.7 g/cm3、干容重平均值为1.2 g/cm3、含水率平均值为46%，自上游库尾至坝前湿容重沿程变化较小、干容重沿程有减小趋势、含水率沿程有增大趋势;淤积物主要由SiO2、Al2O3、Fe2O3、CaO组成，这4种氧化物约占80%;各取样点淤积物均为碱性，pH值自上游向下游有减小趋势;淤积物中氮磷钾总含量满足土地改良所需养分要求，但有机质含量相对较低;淤积物中Cd、Hg、Cu、Ni、As、Pb、Cr、Zn这8种重金属的综合潜在生态风险较低，大部分取样点重金属综合潜在生态风险等级为轻度，但坝前库区部分取样点Cd和Hg有中度潜在生态风险。

关键词：淤积物;物化特性;重金属;有机质;紫坪铺水库

中图分类号：X524;TV697.2+2   文献标志码：A     doi：10.3969/j.issn.1000-1379.2021.12.028

引用格式：李洪，由丽华，李昆鹏，等.紫坪铺水库淤积物物化特性分析及重金属污染评价[J].人民黄河，2021，43（12）：139-142，146.

Abstract： In order to grasp the physicochemical characteristics and heavy metal pollution characteristics of Zipingpu Reservoirs silt， and provide a theoretical basis for the utilization of silts multi-channel resources， based on the measurement results of 21 silt deep samples in the reservoir area， the heavy metal accumulation index method， the enrichment coefficient method and the potential ecological risk index method were used to analyze and evaluate the physicochemical characteristics of Zipingpu Reservoir silt and the risk of heavy metal pollution. The results show that as of October 2020， the total amount of silt in Zipingpu Reservoir is 195.2 million m3， of which clay is about 38.1 million m3， silty fine sand is about 142.4 million m3， medium-coarse sand and pebbles are about 14.7 million m3. Correspondingly， they accounted for 19.5%， 73.0%， and 7.5% of the total sludge. The average wet bulk density and dry bulk density of sedimentation is 1.7 g/cm3 and 1.2 g/cm3， respectively， and the average moisture content is 46%. From the upstream end of the reservoir to the front of the dam， the wet bulk density has a small change along the way， and dry bulk density has a decreasing trend along the way， thus the water content has an increasing trend along the way. The sludge is mainly composed of SiO2， Al2O3， Fe2O3， and CaO， and these account for about 80% of the total content. The sludge at each sampling point is alkaline， and the pH value decreases from upstream to downstream. The total content of nitrogen， phosphorus， and potassium in the sludge meets the nutrient requirements for land improvement， but the organic matter content is relatively low. The heavy metals Cd， Hg， Cu， Ni， As， Pb， Cr， and Zn in the sludge have low comprehensive potential ecological risks. Most of the sampling sites have a low comprehensive potential ecological risk of heavy metals， but Cd and Hg in some sampling points in the reservoir area of the dam have a medium potential ecological risk.

Key words： silt; physicochemical properties; heavy metals; organic matter; Zipingpu Reservoir

紫坪铺水库距成都市约60 km，是以灌溉和供水为主兼顾发电、防洪、环境保护、旅游等综合利用的水利枢纽工程。受2008年汶川地震影响，库区两岸山体稳定性降低，导致暴雨时泥石流、山体滑坡等次生地质灾害频发并加速了库区淤积，至2020年10月累计淤积量达1.952亿m3，拦沙库容淤损87.1%[1]，严重影响了水库的功能和寿命。……