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| Cr(VI)及Ni(II)在偏碱性土壤中的共运移及稳定 |
| Co-transport and immobilization of Cr(VI) and Ni(II) in alkaline soil |
| 投稿时间：2024-04-09 修订日期：2024-05-08 |
| DOI： |
| 中文关键词: Cr(VI)和Ni(II) 共运移 土壤 稳定 形态 |
| 英文关键词: Cr(VI) and Ni(II) Co-transport soil immobilization speciation |
| 基金项目:国家重点研发项目(2018YFC1800600) |
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| 中文摘要: |
| 本文通过动态柱试验研究重金属含氧酸根阴离子Cr(VI)和重金属阳离子Ni(II)在偏碱性土壤中的运移与稳定及其稳定的形态，以期为土壤-地下水环境中重金属阴阳离子复合污染的迁移与稳定机制提供参考。共运移实验表明，Cr(VI)和Ni(II)对入流液流速、水化学条件的变化的响应不同，如不同流速、pH几乎不影响Cr(VI)的穿透量，而Ni(II)在0.05 ml min-1流速下的穿透明显低于0.2 ml min-1流速下且其穿透量随pH升高而降低；较细土壤粒径及较低流速条件下pH对Ni(II)的穿透具有更明显的影响。三种稳定剂存在下的穿透实验及界面过程实验表明，腐殖酸、磁铁矿以及零价铁存在下可以稳定土壤孔隙水中两种金属，但腐殖酸和磁铁矿的反应速率较慢，而零价铁的反应速率较快，200 h内零价铁可以使溶液中Cr(VI)及Ni(II)几乎全部去除；土壤介质本身的性质、孔隙水pH以及反应接触时间是影响两种重金属离子穿透与滞留的关键因素。联合处理的穿透实验中，腐殖酸+磁铁矿组含氧阴离子Cr(VI)以及金属阳离子Ni(II)大部分转化为非易移动的形态；腐殖酸+零价铁的复合处理，具有较高反应效率，能够同时稳定Cr(VI)及Ni(II)，将其几乎完全转变为非易移动的形态。尽管土壤偏碱性，腐殖酸+零价铁的复合处理中Cr(VI)绝大部分转变为Cr(III)，土柱深层Cr(VI)含量低于6%。 |
| 英文摘要: |
| Transport and immobilization of Cr(VI) anion and Ni(II) cation in alkaline soil through column experiments, with the aim of providing useful information for the migration and stabilization mechanism of heavy metal cations and anions in soil groundwater environments. Co-transport experiments showed Cr(VI) and Ni(II) responded differently to changes in flow rate and hydro-chemical conditions. For example, different flow rates and pH have little effect on the penetration of Cr (VI), while the penetration of Ni (II) at a flow rate of 0.05 ml min-1 was obviously lower than that at the flow rate of 0.2 ml min-1, and its penetration decreased with increasing pH. Influent pH had a more significant effect on the penetration of Ni (II) under the conditions of finer soil particle size and lower flow rate. The transport experiments and static surficial reaction experiment at the presence of humic acid, magnetite, and zero valent iron showed that the three materials could simultaneously immobilize the two metals from the influent. However, the low reaction rate of humic acid and magnetite and the high reaction rate of zero-valent iron were found and Cr(VI) and Ni(II) were almost completely removed in 200 h by zero valent iron. The properties of the soil medium, pore water pH, and contact time were key factors affecting the transport and retention of the two metals. In the penetration experiment of joint treatment, a large proportion of retained Cr (VI) oxygen-containing anions and the Ni (II) cations in the humic acid + magnetite treatment were transformed into non easy-mobile forms, while the treatment of humic acid + zero valent iron had a high reaction efficiency and could simultaneously stabilize Cr (VI) and Ni (II), transforming them mostly into non easy-mobile forms. Despite the alkalinity of the soil, Cr(VI) was overwhelmingly transformed to Cr(III) in the joint treatment of humic acid + zero valent iron, with less than 6% Cr remaining as Cr(VI) in the deeper layers of the soil column. |
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