| 我国城市污泥中重金属的赋存形态与生态风险评价 |
| 摘要点击 2119 全文点击 763 投稿时间：2021-01-18 修订日期：2021-03-17 |
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| 中文关键词 城市污泥 重金属(HMs) 生态风险评价 毒液浸出法(TCLP) 风险评价编码法(RAC) |
| 英文关键词 sewage sludge heavy metal(loid)s (HMs) ecological risk assessment toxicity characteristic leaching procedure(TCLP) risk assessment code(RAC) |
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| 中文摘要 |
| 为全面了解中国城市污水处理厂脱水污泥中重金属（HMs）的形态特征和污染状况，本研究以我国40座城市污水处理厂的剩余污泥为研究对象，对污泥中重金属As、Cd、Cr、Cu、Ni、Pb和Zn的总量以及赋存形态进行了测定.采用毒液浸出法（TCLP）、风险评价编码法（RAC）和潜在生态风险指数法评价了其生态风险.结果表明，40个样品中重金属含量的中位值由大到小依次为：Zn > Cu > Cr > Pb > Ni > As > Cd，各元素整体达标率>90%.As的各形态分布较为平均；Cd和Zn以可还原态为主；Cr主要以残渣态的形式存在，其次为可氧化态和可还原态；Cu主要以可氧化态的形式存在；Ni主要以可交换态的形式存在；Pb主要以可还原态和残渣态的形式存在，可交换态的含量最低.TCLP提取态重金属的比例大小顺序为：Ni > As > Zn > Cd > Cu > Cr，所有样品中Pb的TCLP提取态含量均低于检出限；RAC法评价结果显示，7种重金属环境风险大小依次为：Ni > As > Zn > Cd > Cu > Cr > Pb，Ni的生态风险等级为高等，Zn、As和Cd的生态风险等级为中等，Cr和Cu的生态风险等级为低等，Pb无生态风险；潜在生态风险评价结果表明，城市污泥中Cd和Cu的潜在生态风险最高，是我国城市污泥中主要的重金属污染物，但是如果按照国家标准规定的方法进行农用，造成土壤污染的风险总体处于较低水平. |
| 英文摘要 |
| To reveal the speciation and pollution status of heavy metal(loid) s (HMs) in the dewatered sewage sludge(SS) of municipal wastewater treatment plants(MWTPs) in China, SS samples were collected from 40 MWTPs located in different regions of China. The total concentrations and geochemical fractions of As, Cd, Cr, Cu, Ni, Pb, and Zn in the SS samples were analyzed. The ecological risks induced by HMs in the SS were assessed based on the toxicity characteristic leaching procedure(TCLP), risk assessment code(RAC), and potential ecological risk index(RI). The median values of HMs in SS followed the order Zn > Cu > Cr > Pb > Ni > As > Cd. The general attainment rates of HMs in SS were satisfactory(>90%). As showed a generally even distribution among all the fractions; Cd and Zn mainly existed in the reducible fraction; Cr mainly occurred in the residual fraction, followed by oxidizable and reducible fractions; Cu mainly occurred in the oxidizable fraction; Ni occurred mainly as exchangeable forms; and Pb mainly occurred in the reducible and residual fractions, with its exchangeable form being the lowest fraction. According to the RAC method, the environmental risks induced by HMs in the SS followed the order Ni > As > Zn > Cd > Cu > Cr > Pb. The ecological risk of Ni was high; Zn, As, and Cd had a medium level of risk; Cr and Cu had a low level of risk; and the risk of Pb was negligible. According to the RI method, Cd and Cu showed the highest potential ecological risk, indicating that these are the primary HM pollutants in the SS. However, if the agricultural application of SS is carried out in accordance with the national standards, the overall level of risk from soil HM pollution is considered relatively low. |
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