微生物驱动土壤BHMTPMPA-Cd螯合物的地球化学过程及分子机制研究

Remediation of Cd contaminated soil is an important subject in the world, organic phosphonic acid can effectively improve the repair efficiency of Cd contaminated soil, however, the biogeochemical processes and microbial degradation mechanism of organic phosphonic acid and Cd in the soil after combining is not clear. This project is based on the heavy metal Cd contaminated soil repaired by the double 1, 6-hexylidene three five amino methylene phosphonic acid (BHMTPMPA), analysis of adsorption and desorption of Cd contaminated soil on BHMTPMPA, to discuss the stay and release mechanism of BHMTPMPA in Cd contaminated soil, revealing the migration regularity of chelate in soils. The concentration and structure changes of heavy metal chelates in soil were determined by HPLC-ESI-MS, and the degradation and transformation process and main controlling factors of BHMTPMPA-Cd chelates were elucidated. The characteristics of soil microbial quantity, proportion and microbial activity were analyzed, and the ecological status of soil microorganisms and the ability to participate in the biodegradation was discussed. Using PCR-DGGE analysis method, PLFA method and biolog-eco micro plate technique, explore the molecular mechanism of microbial driven BHMTPMPA-Cd chelates. The implementation of this project will not only promote the development of heavy metal Cd contaminated soil remediation technology in China, but also provide a scientific basis and theoretical guidance for the comprehensive evaluation of the biogeochemical processes of BHMTPMPA-Cd chelate.

修复Cd污染土壤为世界各国的重要课题，有机膦酸能有效提高Cd污染土壤的修复效率，但是其与土壤中Cd结合后的生物地球化学过程及微生物降解机制尚不明确。本项目以双1，6-亚己基三胺五甲叉膦酸（BHMTPMPA）修复的Cd污染土壤为研究对象，分析Cd污染土壤对BHMTPMPA的吸附解吸行为，探讨BHMTPMPA在Cd污染土壤内停留释放机制，揭示螯合物在土壤中的迁移规律；利用HPLC-ESI-MS确定土壤中螯合物的浓度及结构变化，阐明螯合物的降解转化过程；分析土壤微生物数量、比例及活性的波动特征，探讨微生物参与降解的生物化学反应能力；利用PCR-DGGE、PLFA及Biolog-ECO微平板技术，探索微生物驱动BHMTPMPA-Cd螯合物生物地球化学过程的分子机制。本项目的实施不仅将推动我国Cd污染土壤修复技术的新发展，更能为全面评价螯合物生物地球化学过程提供科学依据和理论指导。

有机膦酸能有效提高Cd污染土壤的修复效率，但其与土壤中Cd结合后的生物地球化学过程及微生物降解机制尚不明确。本项目通过考察BHMTPMPA在Cd污染在土壤中的环境行为，研究微生物驱动BHMTPMPA的降解转化过程，探讨了土壤BHMTPMPA降解与微生物生态状况的关系，阐明了BHMTPMPA-Cd螯合物生物地球化学过程的机制。.结果表明，BHMTPMPA在棕壤和黑土上吸附迅速，棕壤上吸附最强，但其解吸难度最大。BHMTPMPA在黑土中吸附量随阳离子价态升高而降低，在棕壤中吸附量没有明显差异。BHMTPMPA吸附量均随pH的升高先增加，后略有降低，解吸能力随pH的增大而逐渐减小。可交换态Cd浓度在10-20 cm中最高，BHMTPMPA对土壤Cd的活化作用主要在0-70 cm土层深度中。.土壤中BHMTPMPA在温度30℃，pH值8，3周生物降解率最高，达到52%，在此条件下，BHMTPMPA半衰期约为3周。有根土壤中有机膦酸降解率显著高于无根土壤。随着培养时间延长，0-20 cm土层中可交换态Cd浓度先上升后下降，20-40、40-60 cm土层可交换态镉浓度逐渐降低，60-100 cm土层中可交换态Cd浓度无显著差异。随土层加深，可交换态镉浓度下降。施加BHMTPMPA浓度为8%，土壤中Ca2-P、Ca8-P、Al-P浓度在培养14 d时达到最高；培养21 d，Fe-P、O-P浓度达到最高；土壤中Ca10-P浓度在培养28 d时达到最高。.随BHMTPMPA浓度升高，土壤微生物量碳、微生物量氮显著下降，脲酶、蔗糖酶、转化酶活性逐渐下降，过氧化氢酶活性逐渐增强。随着培养时间增加，土壤脲酶、蔗糖酶活性、过氧化氢酶略有下降，土壤转化酶活性变化不显著。.低浓度BHMTPMPA处理下土壤PLFA含量有所上升，中、高浓度处理下有所抑制。细菌为各处理土壤的优势微生物，革兰氏阴性菌和阳性菌所占比重较高。BHMTPMPA处理Cd污染土壤的谱系多样性低于对照组，BHMTPMPA的加入使土壤细菌多样性和均匀性下降，降低了酸杆菌门、绿弯菌门、拟杆菌门、放线菌门、浮霉菌门细菌丰度，增加了变形菌门、厚壁菌门细菌的相对丰度。.本项目对控制有机膦酸修复Cd污染土壤生态风险，全面评价有机膦酸生物地球化学过程，推动我国重金属污染土壤修复技术的发展具有非常重要和紧迫的现实意义。