| 淹水和干湿交替对修复后土壤铬的稳定性影响研究 |
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| 引用本文： | 常春英,曹浩轩,陶亮,刘丽丽,陈文洁,吕贻忠.淹水和干湿交替对修复后土壤铬的稳定性影响研究[J].环境科学研究,2022,35(5):1150-1158. |
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| 作者姓名： | 常春英 曹浩轩 陶亮 刘丽丽 陈文洁 吕贻忠 |
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| 作者单位： | 1.广东省环境科学研究院，广东省污染场地环境管理与修复重点实验室，广东 广州 510045 |
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| 基金项目： | 国家重点研发计划项目(No.2018YFC1801403)；;国家自然科学基金项目(No.41907337,41877038)~~； |
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| 摘 要： | 采用固化/稳定化技术修复后的场地和土壤因其污染物未彻底清除而备受关注，外界环境胁迫下重金属存在再活化的风险，但再活化的速率和形式尚不明确. 我国华南地区高温多雨，水热交换频繁剧烈，固化/稳定化后修复场地的安全利用面临更大的潜在风险. 以珠三角地区2个典型固化/稳定化修复后场地土壤为研究对象，开展淹水和干湿交替对土壤重金属铬(Cr)的释放、形态转化及其影响机制研究. 结果表明:①淹水和干湿交替可提高已固化/稳定化土壤中Cr的浸出浓度. 场地A和B土壤Cr的浸出浓度较淹水前分别上升了1.32和8.72倍，干湿交替后场地A土壤Cr的浸出浓度略有下降，场地B土壤Cr的浸出浓度则增加了4.32倍. ②淹水和干湿交替促使已固化/稳定化的Cr从酸可提取态向相对稳定的可氧化态等转化. 场地A和B土壤中酸可提取态Cr含量较淹水前的变化率分别为?60.17%和?14.34%，可氧化态Cr含量的变化率分别为2.71%和13.30%；干湿交替后土壤可提取态Cr含量的变化率分别为?28.78%和?2.13%，可氧化态Cr含量的变化率分别为5.48%和10.22%. ③淹水通过降低土壤氧化还原点位(Eh)、pH和无定形氧化铁等影响Cr的稳定性，促使Mn4+、Fe3+的还原和Cr的重新释放；干湿交替较淹水处理对固化/稳定化体系的影响相对较小. 研究显示，水分胁迫可提高固化/稳定化修复后土壤Cr的浸出浓度、改变赋存形态，但其浸出浓度远低于GB 5085.3—2007《危险废物鉴别标准 浸出毒性鉴别》和HJ/T 301—2007《铬渣污染治理环境保护技术规范(暂行)》规定的浸出液浓度限值；鉴于外界环境胁迫的长期性和复杂性，以及当前“一评定终身”的效果评估管理模式对未彻底清除污染物场地后期监管的无力性，持续关注和系统管控是实现固化/稳定化修复后场地可持续安全利用的必要途径.
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| 关 键 词： | 淹水 干湿交替 固化/稳定化 土壤重金属 稳定性 |
| 收稿时间： | 2021-10-31 |
Effects of Flooding and Dry-Wet Alternation on the Stability of Chromium(Cr) in Soil after Solidification/Stabilization Remediation |
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| CHANG Chunying,CAO Haoxuan,TAO Liang,LIU Lili,CHEN Wenjie,LüYizhong.Effects of Flooding and Dry-Wet Alternation on the Stability of Chromium(Cr) in Soil after Solidification/Stabilization Remediation[J].Research of Environmental Sciences,2022,35(5):1150-1158. |
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| Authors: | CHANG Chunying CAO Haoxuan TAO Liang LIU Lili CHEN Wenjie LÜYizhong |
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| Abstract: | Sites and soils treated with solidification/stabilization remediation have received much attention due to the residual pollutants in the soil. The solidified/stabilized heavy metals may be reactivated under environmental stress, and the rate and form of reactivation are unknown. It is hot and rainy in South China, with frequent and intense heat and humidity exchanges. Therefore, the use of solidified/stabilized sites are at greater risk. Typical solidified/stabilized soil samples were collected from two sites in the Pearl River Delta region to study the effect of flooding and dry-wet alternation on the release and transformation of chromium (Cr) in soil. The results showed that: (1) Flooding and dry-wet alternation increased the Cr leaching concentration. Compared with pre-flooding, the Cr leaching concentration of soil from Sites A and B increased by 1.32 and 8.72 times, respectively. After dry-wet alternation, the Cr leaching concentration of soil from Site A decreased slightly, while the Cr leaching concentration from Site B increased by 4.32 times. (2) Flooding and dry-wet alternation promoted the Cr conversion from the acid extractable state to the relatively stable oxidizable state. Compared with pre-flooding, the acid extractable Cr content of soils from Sites A and B decreased by 60.17% and 14.34%, respectively, and the oxidizable Cr content increased by 2.71% and 13.30%, respectively. After dry-wet alternation, acid extractable Cr content of soils from Sites A and B decreased by 28.78% and 2.13%, respectively, while the oxidizable Cr content increased by 5.48% and 10.22%, respectively. (3) Flooding affected Cr stability by reducing soil oxidation-reduction potential (Eh), pH, and amorphous iron oxides, promoting the Mn4+ reduction, Fe3+ reduction, and Cr re-release. Dry-wet alternation had less influence on the solidified/stabilized system than flooding. This study also showed that water stress increased the Cr leaching concentration of solidified/stabilized soils and changed the Cr occurrence forms, but the leaching concentration was much lower than the Toxic Leaching-Related Limit Specified in the Identification Standards for Hazardous Wastes: Identification for Extraction Toxicity (GB 5085.3—2007) and Environmental Protection Technical Specifications for Pollution Treatment of the Chromium Residue (on trial) (HJ/T 301—2007). In consideration of the long-term and complex environmental stress and the inadequate subsequent supervision of solidified/stabilized sites caused by the current ‘determined by one assessment’ effect evaluation management mode, continuous attention and systematic management are necessary for sustainable and safe utilization of the solidified/stabilized sites. |
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