石煤提钒区农田土壤钒污染及其微生物生态效应研究

Stone coal resource is abundant and available vanadium ore in China. The extraction vanadium from stone coal ore,however, pose serious risks for the local environment safety and the pollution of vanadium has occured in recent years.In the proposal, the agricultural soil from the vicinity areas of vanadium smelters in Xiangxi and Huaihua districts of Hunan province is selected for the present research. Firstly, based on the investigation and greenhouse experiments, the content, speciations, valence changes and transferring of vanadium in soils will be studied by XRD, SEM/EDX and ICP-OES techniques in order to elucidate the chemical behaviors and spational distribution of vadadium in soils.and profile distribution of vanadium content, chemical mobility and valence state of vanadium in different land-use soils including rice soil and arable soil. Secondly, the microbial community and functional diversity in soils will be determined using PLFA and PCR-DGGE techniques. Then, stress toxic responses of microbial and emzyme activities will be studied through greehouse experiments in order to elucidate the qualitifical relationships between the pollution of vanadium and the microbial physiological index elucidate the characteristics of vanadium pollution for soil as well as its environmental behavior. Finally, the permissible value of vanadium for microbial ecological effects and index in agricultural soils will be suggested. The results obtained in the propsal will be severed to both provide theoretical basis for environmental risk assessment and establish the environmental quality standard of V in agricultural soil.

我国石煤资源丰富，是我国一种独特的钒矿资源。石煤资源的选冶活动给当地生态系统带来严重的破坏，土壤钒污染风险已经显现。本项目拟以我国石煤资源丰富、石煤提钒活动聚集的湖南湘西和怀化地区的农田土壤为研究对象，通过现场调查，利用XRD、SEM/EDM及ICP-OES检测技术，分析不同利用类型(水稻土和旱地)土壤中钒的矿物相、含量、形态和价态转化及其迁移特征，阐明农田土壤钒的化学行为及其空间迁移规律；利用PLFA、PCR-DGGE等现代分子生物技术，研究自然状态钒污染土壤中微生物的群落结构与功能多样性；开展室内培养试验，研究钒污染土壤中微生物及酶活性的生态毒害响应机制，建立钒污染与土壤微生物生理生化指标之间的定量表征关系，结合田间调查结果提出农田土壤钒污染的微生物生态效应的微生物学指标和临界值。研究成果为我国土壤钒的环境质量标准制定和风险评估提供科学依据。

我国含钒(V)石煤资源丰富，湖南省是主要分布区之一。土壤钒污染已成为倍受关注的环境问题之一。本项目以湖南湘西和怀化地区典型石煤提钒活动区域内土壤及周边农田土壤(水稻土和旱地)为研究对象，通过野外调查，探讨了土壤钒污染特征及其对土壤微生物生态的影响；通过静态培养试验，研究了pH值、水分条件对水稻土中钒的形态与价态变化影响，以及钒在水稻土壤中的吸附-解吸特征；通过柱淋洗试验，研究了模拟酸雨和含钒污水淋溶下钒在土壤的垂直迁移特征；结合田间调查和室内模拟试验，研究了钒含量对土壤酶活性、微生物碳量及群落结构多样性的影响。. 野外调查结果表明，石煤提钒活动区域内土壤V平均含量远高于加拿大土壤钒环境质量标准和荷兰土壤钒调节值，土壤样品V的超标率分别为100%和70.6%，土壤V污染明显抑制了土壤酶活性及微生物基础呼吸率；与加拿大土壤环境质量标准相比，石煤提钒区周边水稻土和菜地土壤中V超标率分别为100%和93.3%，呈重度污染。静态平衡试验表明，淹水和土壤溶液pH值升高有利于土壤残渣态V向酸溶态和可还原态形态转化；水稻土对钒的吸附等温线均符合Langmuir方程和Freundlich方程，酸性条件和较高温度下水稻土吸附的钒较易解吸，进入环境的风险较高。柱淋洗试验表明，相当于10年降雨量的模拟酸雨淋溶下，淋出液中V浓度高于或接近我国《地表水环境质量标准》(GB 3838-2002)规定的V浓度标准限值(50 µg/L)；V污水灌溉下，外源V主要累积在水稻土壤表层，淋出液V浓度均低于我国《地表水环境质量标准》(GB 3838-2002)规定的V浓度标准限值，表明中长期灌溉含V污水对地下水不会造成直接污染。野外和室内培养试验表明，土壤脱氢酶、基础呼吸率和土壤生物量碳与钒含量呈显著负相关，对钒污染敏感，可作为土壤钒污染的微生物学指标；土壤V污染影响微生物群落的细菌种群数目，改变微生物群落结构以及优势种群，特别是高钒含量条件增加了土壤中微生物种群数目，耐受性提高。综上所述，石煤提钒区及周边农田土壤V污染严重，对微生物产生毒害效应，潜在生态风险高；土壤脱氢酶、基础呼吸率和土壤生物量碳等可作为钒污染的微生物评价诊断指标。研究成果为我国土壤钒的环境质量标准制定和风险评估提供科学依据。.本项目研究成果已公开发表学术论文3篇，其中，SCI收录论文2篇，CSCD收录 1篇。