黔西北土法炼锌废渣堆场重金属释放的原位植物固持机制研究

The smelting Zn waste residue heap located in the upstream of rock reservoir and water conservancy project of Guizhou province, has continuously released high levels heavy metals into the down stream water source and posed serious threat to the surrounding water quality and environmental safety. The phytoremediation is a vital measure to control the pollution and improve the ecological environment. However, many studies have indicated that the phytoremediation in the tailings rich in heavy metals could increase the leaching of heavy metals due to release of organic acids from plant roots. And our engineering practice showed that phytoremediation can significantly control the heavy metal released from the waste residue. In this study, we select the waste residue have successfully restored for 4 years as the research object to clarify related mechanisms, and using synchrotron radiation, nuclear magnetic resonance, isotope tracing and combined with the theory of biogeochemistry to study the bioavailability and chemical efficiency of heavy metals with and without plant participation, which will clear the role of direct passivation and indirect immobilization of heavy metals under the presence of plant root exudates and plant litter. It will be reveal the holding mechanism that the coupling effect among root exudates, aggregate and plant litter on the heavy metals, which can provide theory for in situ control and ecological restoration of heavy metals released from heavy metal tailings dump in China.

位于黔西北夹岩水库枢纽及黔中水利枢纽上游的黔西北土法炼锌废渣多年来向下游持续释放重金属，严重威胁周边重大工程的水质和环境安全。堆场植被恢复是控制污染和改善生态的重要措施，但大量研究表明，在富含重金属的尾矿堆场上进行植被修复会因植物根系分泌有机酸而增加重金属的淋溶风险，而团队前期的工程实践及研究表明，在炼锌废渣上进行植被恢复却可使废渣重金属释放得到显著控制。为明确相关作用机制，本研究拟以已成功恢复4年植被的黔西北铅锌冶炼废渣为研究对象，综合采用同步辐射、核磁共振、同位素示踪等手段结合生物地球化学理论，研究有无植物参与条件下废渣重金属的生物有效性及化学有效性，明确生态恢复植物根系分泌物、凋落物等对矿渣重金属的直接钝化及间接固持作用，揭示恢复植被的根系分泌物-团聚体-凋落物耦合作用及其对炼锌废渣重金属的固持机制，为我国广大含重金属尾矿堆场重金属污染释放的原位控制与生态修复提供理论依据及数据支撑。

位于黔西北夹岩水库枢纽及黔中水利枢纽上游的黔西北土法炼锌废渣多年来向下游持续释放重金属，严重威胁周边重大工程的水质和环境安全。堆场植被恢复是控制污染和改善生态的重要措施。本研究以黔西北铅锌冶炼废渣为研究对象，综合采用高通量测序、傅里叶变换红外光谱、高效液相色谱、电子扫描显微镜-能量分散X射线光谱、X射线衍射仪等手段结合生物地球化学理论，系统研究了不同类型优势植物（构树、刺槐、柳杉、芦竹等）修复对土法炼锌废渣的理化特征、微生物学特性、废渣中重金属的赋存形态及迁移转化特征、团聚体与颗粒态有机质的组成及其对重金属迁移转化的影响，明确了生态恢复植物根系分泌物、凋落物等对矿渣重金属的直接钝化及间接固持作用，揭示了恢复植被的根系分泌物-团聚体-凋落物耦合作用及其对炼锌废渣重金属的固持机制。项目的开展可为我国广大含重金属尾矿堆场重金属污染释放的原位控制与生态修复提供理论依据及数据支撑。