摘要
为探究矿区生态修复工程对土壤污染源头防控工作的成效,本研究对江西某矿区煤矸石、矿区新覆土壤、矿区下游农用地土壤、灌溉水及底泥进行系统的环境质量调查,并对样品Cd含量进行分析测试.采用莫兰指数、地累积指数、生态风险指数对矿区及周边表生环境中Cd的源汇关系、污染程度、生态风险进行评估.结果显示矿区周边土壤受煤矸石和矿区新覆土壤以及自然本底的多重影响,Cd含量(0.33 mg·kg-1)介于煤矸石与新覆土壤之间,污染程度(Igeo为-2.03～0.37)介于轻微污染-中度污染之间,生态风险(Er为11～58)介于低风险-中度风险之间.研究表明矿区生态修复工作对下游农田保护效果显著,周边农田土壤Cd元素含量、污染程度、风险水平相较于煤矸石均显著降低.但在土地开发利用过程中,需注意土壤酸化问题,及时避免由于酸化而引起的大量重金属的释放.
Abstract
To investigate the effectiveness of ecological restoration projects in controlling the sources of soil pollution,a pollution assessment and ecological risk evaluation of Cd in the surrounding environment of the mining area were conducted.This study systematically investigated the environmental quality of coal gangue,newly covered soil in the mining area,agricultural soil,irrigation water,and sediment in a mining area in Jiangxi.Cd in the samples was analyzed and tested,using Moran′s I,geo-accumulation index,and ecological risk index to evaluate the source-sink relationship,pollution level,and ecological risk of Cd in the mining area and its surrounding surface environment.The results indicate that the soil surrounding the mining area is influenced by multiple factors,including coal gangue,newly covered soil in the mining area,and local natural background.The Cd content(0.33 mg·kg-1)falls between that of coal gangue and newly covered soil,pollution level(Igeo:-2.03 to 0.37)ranging from slightly polluted to moderately polluted,ecological risk(Er:11 to 58)ranging from low to moderate.The study demonstrates that the soil restoration project in the mining area is significantly effective.The Cd content,pollution level,and risk level in the surrounding agricultural soil are all significantly reduced compared to coal gangue.However,during land development and utilization,attention must be paid to the issue of soil acidification,and measures should be taken promptly to avoid the release of large amounts of heavy metals due to acidification.
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