白腐真菌耦合氯磷灰石强化修复湖泊湿地底泥重金属污染的行为机制及其对底泥微环境的影响研究

The heavy metal pollution in Dongting Lake Wetland poses a serious threat to the health of aquatic organisms and even humans. Microbial remediation technique has become a hot research for the remediation of heavy metal contaminated soil or sediment because of its low processing cost and environmental friendliness. However, the performance of microbial remediation technique is restricted by the remediation efficiency and system stability. The combination of microorganisms and chloroapatite is an effective way to efficiently repair heavy metal pollution. Therefore, this project takes the sediment of East Dongting Lake Wetland as the research object, and a combined remediation system of white rot fungus coupled with chloroapatite is constructed, the influence law of environmental factors is clarified and the performance of the combined remediation system is optimized. The coupling strengthening effect and interaction mechanism of white rot fungus and chloroapatite are studied, and the remedied products are analyzed by the modern characterization techniques, and the remediation mechanism of white rot fungus coupled with chloroapatite in strengthening the remediation of heavy metal contaminated sediment is revealed. Finally, the changes of the physical and chemical properties of sediment, the microbial enzyme activities and the microbial community structure are observed, and the ecological safety of using the combined remediation technique to repair heavy metal contaminated sediment is comprehensively evaluated. This study is expected to provide theoretical basis and technical support for the development of low-cost, efficient, stable and safe techniques for remediation of heavy metal contaminated lake wetland.

洞庭湖湿地的重金属污染对水生生物乃至人类的健康构成了严重威胁。微生物修复技术因其处理成本低和对环境友好等优点已经成为重金属污染土壤或底泥修复的研究热点，但应用过程中其性能受到修复效率和体系稳定性的制约。将微生物与氯磷灰石联用是高效修复重金属污染的一种有效途径。本项目以东洞庭湖湿地底泥为研究对象，拟构建白腐真菌耦合氯磷灰石联合修复体系，明确环境因子的影响规律，对联合修复体系的修复性能进行优化调控；研究白腐真菌与氯磷灰石的耦合强化效应及交互作用机理，并利用现代表征技术对修复产物进行分析，揭示白腐真菌耦合氯磷灰石强化修复底泥重金属污染的行为机制；最后研究联合修复体系中底泥理化性质、微生物酶活性和底泥微生物群落结构的变化，综合评价联合修复技术应用于重金属污染底泥修复的生态安全性。本研究有望为开发廉价、高效、稳定和安全的重金属污染湖泊湿地修复技术提供理论依据与技术支持。

针对目前重金属污染的土壤和底泥等环境修复问题，微生物修复技术已成为当前的研究热点，利用磷灰石材料联合溶磷微生物能够有效地解决单一微生物修复技术应用过程中的稳定性和长效性等问题。本项目首先利用包埋技术将黄孢原毛平革菌与羟基磷灰石制备成包埋小球，在溶液体系中探究其对Pb(II)的去除，通过实验发现黄孢原毛平革菌能分泌大量的小分子有机酸，其中甲酸含量达到66.02 g L-1，有机酸能够促进羟基磷灰石的溶解，释放出的磷酸根与Pb(II)结合生成沉淀实现对溶液中Pb(II)的高效去除；然后探究了溶磷细菌与羟基磷灰石对Pb(II)的生物矿化位点，解析了溶磷细菌强化羟基磷灰石矿化重金属的作用机理，实验发现羟基磷灰石能够为溶磷细菌提供更好的生长环境，从而提高溶磷细菌对重金属Pb(II)的耐受能力，最终有95.78%的Pb分布在细胞周质，表明溶磷细菌细胞周质是生物矿化的主要位点，生物矿化产物为稳定的铅磷酸盐矿物（Pb10(PO4)6Cl2和Pb10(PO4)6(OH)2）；探究了黄孢原毛平革菌耦合羟基磷灰石修复重金属Pb污染的底泥和Cr、Zn、As、Pb和Sb复合污染的酸性矿山土壤，分析了修复过程中土壤理化性质（pH、有机酸、有机质和有效磷）的变化，结果发现黄孢原毛平革菌耦合羟基磷灰石能够有效地稳定底泥和土壤中的多种重金属，并对修复产物进行表征，揭示了黄孢原毛平革菌耦合羟基磷灰石稳定底泥和土壤中重金属的作用机理；最后探究了黄孢原毛平革菌耦合羟基磷灰石修复重金属污染土壤过程中的生态安全性，结果表明加入黄孢原毛平革菌和羟基磷灰石会改善土壤的理化性质，改变重金属BCR提取形态，影响微生物群落结构和组成。因此，在利用溶磷微生物联合磷酸盐材料修复重金属污染的土壤过程中，应综合考虑修复菌剂和材料的生态安全性，并结合环境因子考察该应用方法的长效性和稳定性。