不同风化程度煤矸石中重金属释放及潜在生态风险  

Potential ecological risks of heavy metals in the coal gangue and their release in different weathering degrees

作　　者：段磊[1,2] 孙亚乔[1,2] 王晓冬 窦琳[1,2] DUAN Lei;SUN Ya-qiao;WANG Xiao-dong;DOU Lin(School of Water and Environment,Chang’an University,Xi'an 710054,China;Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education,Xi’an 710054,China)

机构地区：[1]长安大学水利与环境学院,西安710054 [2]旱区地下水文与生态效应教育部重点实验室,西安710054

出　　处：《安全与环境学报》2021年第2期874-881,共8页Journal of Safety and Environment

基　　金：国家自然科学基金项目(41877190,41372258);陕西省重点研发项目(2020ZDLSF06-04)。

摘　　要：为研究不同风化程度煤矸石中重金属释放特征及潜在生态风险,以3种不同风化年限的煤矸石为研究对象,采用连续提取试验、动态淋滤试验和XRD分析的方式,研究不同风化程度煤矸石中重金属的赋存形态与释放规律的关系,并利用RAC风险评价法评估不同风化煤矸石中重金属元素的潜在环境风险。结果表明:在不同风化程度煤矸石中,重金属Mo、Co、Cr、Cu、Pb以残渣态为主;受风化作用影响,Co和Cu的碳酸盐结合态明显降低。在煤矸石动态淋滤过程中,Co、Cu、Pb在初期(1~6 d)均为快速释放,中后期(6 d后)为稳定释放。随着风化时间延长,Co、Cu、Pb与S、Ca的相关性减弱,碳酸盐态分解,风化煤矸石重金属的释放量明显高于新鲜煤矸石。RAC风险评价结果表明:3种不同风化程度的煤矸石中Mo和Cr为无污染;随着风化作用时间延长,Co由新鲜煤矸石的中度污染下降为风化煤矸石的轻度污染;Pb由新鲜煤矸石的轻度污染下降为风化煤矸石的无污染;Cu的环境风险程度从大到小依次为新鲜煤矸石、风化2年煤矸石、风化7年煤矸石。The paper is aimed to study the release characteristics and potential ecological risks of heavy metals in the coal gangue at different weathering degrees.In this paper,3 kinds of coal gangues with different weathering ages are taken as the research subject.The coal gangues we have collected are from the coal mines of Hancheng city area,Shaanxi,China.The said coal gangues we have collected are fresh ones,weathered for about 2 years in comparison with the weathered coal gangue for 7 years.In our paper,we have managed to finish our investigation of the relationship between the chemical speciation and the heavy metal release in different weathering degree gangues.And,in our research,we have done the said 5 step sequential extraction experiment and the dynamic leaching experiment through XRD analysis.And,in the above said research,we have assessed the potential environmental risk of the heavy metal contaminants with the different weathering coal gangues via the RAC risk evaluation method.The results of the above examination and analysis prove that the elements of Mo,Co,Cr,Cu and Pb are mainly composed with the residual fraction in the coal gangue of different weathering degrees,whose carbonate bound state of Co and Cu has been obviously reduced under the weathering impact.And,so,in the process of the dynamic leaching of coal gangue,the content rates of Co,Cu and Pb can be released promptly in the early stage(1-6 days),and then be made getting to be stabilized during the middle and later stages(after 6 days).And,then,with the extension of the weathering time,the correlation between Co,Cu,Pb and S,Ca may tend to be weakened,carbonate minerals are decomposed,and the release of heavy metal slags from the weathered coal gangue is significantly higher than that from the fresh coal gangue.According to the RAC risk assessment results,Mo and Cr in the 3 kinds of gangues with different weathering degrees can be made pollution-free.With the weathering time prolonging,the environmental risk of Co can be expected to be reduced fro

关 键 词：环境学 煤矸石 风化程度 重金属 风险评价 

分 类 号：X501[环境科学与工程—环境工程] X820.4