| 摘要: |
| 【目的】探究不同生物炭与聚丙烯酰胺（PAM）复合对汞污染土壤的钝化修复效果。【方法】以贵州万山汞矿区中度汞污染酸性土壤为研究对象，将玉米秸秆生物炭、牛粪生物炭、药渣生物炭分别与聚丙烯酰胺按7∶3质量比混合处理，得到了玉米秸秆生物炭基复合材料、牛粪生物炭基复合材料、药渣生物炭基复合材料，通过土培盆栽试验，以不施用生物炭基复合材料为对照（CK），研究了3个施用比例（1%，3%，5%）生物炭基复合材料对土壤有机碳含量、pH、汞形态、有效态汞含量和小白菜各部位汞含量及土壤酶活性的影响。【结果】与单一生物炭相比，生物炭基复合材料比表面积和孔径明显增加。施用生物炭基复合材料可有效提高土壤有机碳含量和pH值，且以施用比例为5%药渣生物炭基复合材料处理最佳，此时土壤有机碳含量和pH分别较对照提高426.36%和20.95%。不同种类生物炭基复合材料及其施用比例处理土壤中不同形态汞的比例存在差异，3种生物炭基复合材料处理的水溶态汞、可交换态汞所占比例分别较对照降低60.35%～87.03%，40.54%～75.58%，强有机结合态汞和残渣态汞分别较对照增加41.99%～125.96%，25.77%～34.18%，其中药渣生物炭基复合材料处理更有利于促进土壤水溶态汞、可交换态汞向残渣态和强有机结合态汞转化。与对照相比，不同种类生物炭基复合材料处理土壤有效态汞含量均显著降低了41.33%～74.67%，且土壤有效态汞含量随着生物炭基复合材料施用比例的增加而下降；施用生物炭基复合材料显著降低了小白菜地下根部及茎叶部的汞含量，且当施用比例为5%时，药渣生物炭基复合材料处理小白菜根部汞含量和茎叶汞含量分别较其他2种生物炭基复合材料下降幅度大。相关性分析结果表明，小白菜根部及茎叶部汞含量与土壤有效态汞含量均呈极显著正相关关系，而与土壤pH、有机碳含量呈显著或极显著负相关关系。与对照相比，施用生物炭基复合材料均可显著提高土壤酶活性，且随着施用比例的增加，土壤过氧化氢酶和蔗糖酶活性呈现先增后减的趋势，而土壤脲酶活性则表现为逐渐增加的趋势。【结论】生物炭基复合材料对中度汞污染酸性土壤具有明显的钝化修复效果，其中以施用比例为5%的药渣生物炭基复合材料的修复效果较优。 |
| 关键词: 生物炭基复合材料 土壤有机碳 酸性土壤 汞形态 土壤酶活性 |
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| 基金项目:贵州省教育厅自然科学基金资助项目（黔教合 KY字［2018］349）；农业农村部产地环境污染防控重点实验室开放基金项目（19cdhj-5)；铜仁学院博士科研启动基金项目（trxyDH1701） |
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| Effect of biochar based composite materials on mercury passivation in contaminated acidic soils |
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YU Gao,CHEN Fen,ZHANG Hongli,et al
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| Abstract: |
| 【Objective】This study evaluated the effectiveness of different biochars mixed with polyacrylamide (PAM) on remediating mercury (Hg)-contaminated acidic soils.【Method】Soil culture experiment was conducted under greenhouse conditions,with Chinese cabbage as testing crop.Three biochar based composite materials of mixing corn stalks,cow dung and traditional Chinese herb residue produced biochar with PAM at the ratio of 7 to 3 were applied with application rates of 1%,3% and 5%,respectively.A treatment without biochar was included as the control.Soil organic carbon,pH,soil Hg form,available Hg and Hg contents in shoot and root of Chinese cabbage as well as soil enzyme activities were determined at the end of experiments.【Result】Compared with single application of biochar,specific surface area and pore diameter of biochar composite materials increased significantly,along with improved surface structure.Application of biochars resulted in increases in both soil organic carbon content and pH.The application rate of 5% traditional Chinese herb residue biochar based composite material was the best,with soil organic carbon content and pH increased by 426.36% and 20.95%,respectively.Effects of biochar based composite materials on soil Hg form varied depending on biochar type and application rates.Compared with the control,three kinds of biochar composite materials decreased water soluble mercury and exchangeable mercury by 60.35%－87.03% and 40.54%－75.58%,respectively.Biochar composite materials increased strong organic combined mercury and residual mercury by 41.99%－125.96% and 25.77%－34.18%.Traditional Chinese herb residue biochar based composite materials had the greatest effect on reduction of soil water and exchangeable Hg.Compared with the control,soil available Hg content were decreased by 41.33%－74.67% under biochar composite materials treatment.Soil available Hg content decreased with the increase of application rate.Biochar composite materials decreased Hg contents in underground roots and edible stems and leaves of Chinese cabbage,with the largest reduction in 5% application rate of traditional Chinese herb residue biochar based composite materials.Correlation analysis showed that Hg contents in underground roots and edible stems and leaves of Chinese cabbage had positive correlation with soil available Hg content,and negative correlation with soil pH and organic carbon content.Biochar composite materials increased soil enzyme activity.Soil catalase and sucrase activities increased first and then decreased with the increase of application rate,while soil urease activity showed a gradually increasing trend.【Conclusion】Biochar composite materials showed significant passivation effect on acidic soils moderately polluted by Hg.The application of traditional Chinese herb residue biochar based composite material at the rate of 5% was the best. |
| Key words: biochar-based composite materials soil organic carbon acidic soil mercury form soil enzyme activity |
