| 引用本文: | 魏样,李日升,卢楠,石海兰,张钊熔.2025.三种秸秆生物炭对污染土壤中汞、砷钝化的研究[J].地球环境学报,16(1):99-106 |
| WEI Yang,LI Risheng,LU Nan,SHI Hailan,ZHANG Zhaorong.2025.Study on passivation of mercury and arsenic in contaminated soil by three straw biochars[J].Journal of Earth Environment,16(1):99-106 |
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| 三种秸秆生物炭对污染土壤中汞、砷钝化的研究 |
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魏样1, 2, 3, 4*，李日升1, 2, 3, 4，卢楠 2, 3, 4，石海兰1, 2, 3, 4，张钊熔1, 2, 3, 4
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1. 陕西地建土地工程技术转化中心有限公司，咸阳 712046
2. 陕西地建土地工程技术研究院有限责任公司，西安 710075
3. 陕西省土地工程建设集团有限责任公司，西安 710075
4. 自然资源部退化及未利用土地整治工程重点实验室，西安 710075
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| 摘要: |
| 汞（Hg）、砷（As）作为典型的有毒有害重金属元素，在土壤中复合存在具有很大的潜在环境风险。利用秸秆生物炭修复重金属具有良好的应用前景，但是不同原料制备的生物炭在元素组成、表面特性和微观形态上存在较大差异，导致其对重金属的修复性能也存在一定差异。选用3种秸秆（芦苇、木薯、水稻）作为原料分别制备获得芦苇秸秆生物炭（REB）、木薯秸秆生物炭（CAB）和水稻秸秆生物炭（RIB），通过盆栽实验，研究3种秸秆生物炭对重金属污染土壤中Hg和As生物有效性的影响。结果表明：3种生物炭对比，RIB的产率最大，平均孔径RIB＜CAB＜REB，比表面积RIB＞CAB＞REB；与不添加生物炭的CK对比，3种秸秆生物炭可促使土壤中的可交换态Hg（F1-Hg）、As（F1-As）含量显著降低，降幅分别为11.1%—16.3%和13.4%—25.1%，残渣态Hg（F5-Hg）、As（F5-As）含量显著增加，增幅分别为8.4%—20.2%和19.8%—29.5%，RIB对Hg、As的F1和F5两种形态含量的影响最为显著；添加生物炭后植物对两种重金属的富集系数均显著降低，富集系数RIB最小，REB最大。综上所述，与REB和CAB相比，RIB的添加更为显著地促进了重金属复合污染土壤中Hg、As的可交换态向化学性质稳定的残渣态转化，降低了土壤重金属的生物有效性，一定程度上实现了对重金属复合污染土壤的修复。 |
| 关键词: 生物炭 重金属 土壤 |
| DOI：10.7515/JEE222069 |
| CSTR：32259.14.JEE222069 |
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| 基金项目:陕西地建-西安交大土地工程与人居环境技术创新中心开放基金资助项目（2021WHZ0094） |
| 英文基金项目:Technology Innovation Center for Land Engineering and Human Settlements, Shaanxi Provincial Land Engineering Construction Group Co., Ltd. and Xi’an Jiaotong University (2021WHZ0094) |
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| Study on passivation of mercury and arsenic in contaminated soil by three straw biochars |
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WEI Yang1, 2, 3, 4*, LI Risheng1, 2, 3, 4, LU Nan2, 3, 4, SHI Hailan1, 2, 3, 4, ZHANG Zhaorong1, 2, 3, 4
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1. Land Engineering Technology Transformation Center, Shaanxi Provincial Land Engineering Construction Group Co., Ltd., Xianyang 712046, China
2. Institute of Land Engineering & Technology, Shaanxi Provincial Land Engineering Construction Group Co. Ltd., Xi’an 710075, China
3. Shaanxi Provincial Land Engineering Construction Group Co. Ltd., Xi’an 710075, China
4. Key Laboratory of Degraded and Unused Land Consolidation Engineering, Ministry of Natural Resources, Xi’an 710075, China
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| Abstract: |
| Background, aim, and scope Mercury (Hg) and arsenic (As), as the typical toxic and harmful heavy metal, have great potential environmental risks when combined in soil. Despite that straw biochar is of good application prospect for heavy metal remediation, biochars prepared from different raw materials show great differences in elemental composition, surface characteristics and microscopic morphology, and then their adsorption performance for heavy metals has certain differences as well. This study was aimed to investigate the effects of different straw biochars on the bioavailability of Hg and As in order to provide a basis for the remediation of heavy metal polluted soil. Materials and methods Three kinds of straw (reed, cassava and rice) had been selected as raw materials to prepare reed straw biochar (REB), cassava straw biochar (CAB) and rice straw biochar (RIB). To test the effects of biochars on morphological transformation of Hg and As in polluted soil, pot experiments were conducted. Apart from that, the Tessier sequential extraction was used to fractionate soil Hg and As to exchangeable (F1), carbonate-bound (F2), Fe/Mn oxides-bound (F3), organic-bound (F4), and residual fractions (F5). In addition, the basic physicochemical properties and microstructure of biochar were determined. Results The yield of RIB was the largest, followed by CAB, and the yield of REB was the smallest. The average pore size was in the order of RIB＜CAB＜REB, and the specific surface area was in the order of RIB＞CAB＞REB. In comparison to control (no biochar added), the three biochar species could significantly reduce the contents of F1-Hg and F1-As and remarkably increase the contents of F5-Hg and F5-As in the soil. The decrease of F1-Hg and F1-As ranged from 11.1% to 16.3% and 13.4% to 25.1%, respectively, whereas the increase of F5-Hg and F5-As ranged from 8.4% to 20.2% and 19.8% to 29.5%, respectively. The RIB had the most significant effect on the contents of both F1 and F5 of Hg and As. The addition of biochar triggered a significant decrease in the bioconcentration factors (BCFs) of plants for both heavy metals. The BCFs of the three treatments with biochar were the smallest in the RIB treatment but the largest in the REB treatment for both Hg and As. Discussion The differences in the characteristics of different biochars and their effects on soil properties after application may be the main reasons for the different application effects of different types of biochars. By comparing the three types of biochars, it could be found that RIB has a hierarchical pore structure with the smallest average pore size, and RIB has the best adsorption and passivation effect on the two heavy metals. Beyond that, RIB contains high sulfur and silicon simultaneously, the sulfur group can react with Hg to form a stable residual mercury sulfide, and silicon can promote the conversion of heavy metals to a refractory state. Biochar also increases soil pH, CEC and organic matter content to a certain extent, and the combined effect of these factors promotes the transformation of heavy metals from exchangeable to refractory states. Conclusions In comparison to REB and CAB, the addition of RIB not only significantly promotes the conversion of the exchangeable state of Hg and As in the composite polluted soil to the chemically stable residue state, but also reduces the bioavailability of heavy metals. To a certain extent, biochar has achieved the remediation of heavy metal combined polluted soil. Recommendations and perspectives The overall results have provided guidance for optimization of biochars for the remediation of Hg and As polluted soil. However, with RIB as remediation agent, the optimal amount and the best application environmental conditions still need to be further explored, so as to provide theoretical basis and technical support for the field application. |
| Key words: biochar heavy metal soil |
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