• 关键词：载铁生物炭  砷  汞  镉  浸出浓度  形态分析

• 基金项目：国家自然科学基金（No.41301339）；湖南省地理学重点学科项目；湖南省高校科技创新团队项目；霍英东教育基金会高等院校青年教师基金（No.151029）；湖南省自然科学基金（No.2017JJ2180）

• 潘亚男
• 1. 湖南师范大学资源与环境科学学院, 长沙 410081;2. 湖南省环境保护科学研究院, 长沙 410004

• 陈灿
• 湖南省环境保护科学研究院, 长沙 410004

• 王欣
• 湖南师范大学资源与环境科学学院, 长沙 410081

• 万勇
• 湖南省环境保护科学研究院, 长沙 410004

• 钟振宇
• 湖南省环境保护科学研究院, 长沙 410004

• 彭渤
• 湖南师范大学资源与环境科学学院, 长沙 410081

• 谭长银
• 湖南师范大学资源与环境科学学院, 长沙 410081

• 摘要：以我国典型水生入侵植物凤眼莲为前体制备了生物炭（BCW）和负载铁生物炭（BCW-Fe），在对其理化特性进行充分表征的基础上，系统分析了这2类生物炭对金矿冶炼区酸性复合污染土壤中As、Hg、Cd的钝化修复效果.水浸与酸浸实验表明，5%（质量分数）BCW与5%（质量分数）BCW-Fe处理分别使土壤As浸出浓度降低91.4%~91.6%和64.9%~96.8%，Hg浸出浓度由0.03~0.04 μg·L^-1降低至0~0.02 μg·L^-1；而2种材料对Cd的钝化优势分别出现在中性和酸性浸出条件下.重金属形态分析结果显示，2种生物炭处理均使As、Hg、Cd由植物可利用性较高的可交换态和碳酸盐结合态向较为稳定的铁锰氧化物与有机物结合态转化.其中，BCW与BCW-Fe的加入分别使可交换态与碳酸盐结合态As总量减少0.3%和3.1%，使这2种非稳态Hg总量分别减少2.3%和3.4%，使这2种形态Cd总量分别减少7.7%和14.9%.综合以上研究结果，凤眼莲负载铁生物炭提供了一种能够在我国广泛分布的酸雨沉降地区内实现对复合污染土壤中As、Hg、Cd同步稳定钝化的有效材料，与此同时，该方法有利于实现对入侵植物的有效管理和应用土地系统进行长期固碳.

• Abstract：In this study, water hyacinth derived biochar (BCW) and Fe-modified BCW (BCW-Fe) were prepared. Based on a full characterization of the physiochemical properties of the two biochars, the immobilization of As, Hg, and Cd with BCW and BCW-Fe was investigated with an acidic and multi-metal contaminated soil from a gold mining site. With the incorporation of BCW and BCW-Fe, soluble As concentrations in the neutral and acidic extractions were significantly reduced by 91.4%~91.6% and 64.9%~96.8%, respectively. Meanwhile, the extractable Hg levels decreased from 0.03~0.04 μg·L^-1 to 0~0.02 μg·L^-1 with the amendments. Regarding Cd, the most prominent immobilization was determined with BCW under neutral condition and BCW-Fe under acidic condition. With the application of both two amendments, an apparent transformation of the easily exchangeable and carbonate-associated As, Hg, Cd to their non-labile Fe/Mn oxide and organic bound forms has been unraveled by sequential extraction. For example, with the addition of BCW and BCW-Fe, the more labile pool of As including the easily exchangeable and carbonate-associated fractions was decreased by 0.3% and 3.1%, respectively. In parallel, Hg level in these two fractions was reduced by 2.3% and 3.4%, respectively, in the BCW and BCW-Fe treatments. Similarly, the more labile Cd was decreased by 7.7% and 14.9% with the above two treatments. These results highlight that effective and simultaneous immobilization of soil As, Hg and Cd can be achieved with this Fe-modified biochar derived from water hyacinth even under acid precipitation, which also provides a win-win strategy for the effective management of invasive species and long-term sequestration of carbon in land system.

• Key words：Fe-modified biochar  arsenic  mercury  cadmium  leaching concentration  mobility chemical speciation

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