基于离子特征和生物配体耦合的土壤金属元素生态毒性预测模型研究

The types of contaminating metal elements in soil are increasing, however, the corresponding ecological risk assessment is still significantly lagging. The Biotic Ligand Model (BLM) can effectively evaluate the ecological risk of elements, but has a limitation on biological species and elements. However, the limitation of BLM will be compensated by coupling with the Quantitative Ion Character−activity Relationship model (QICAR), which can predict toxicity of the elements based on the physical and chemical characteristics of elements. The current challenge is lacking of a systematic and complex homogeneous (same soil properties)-heterogeneous (different soil properties) metals ecotoxicity transformation theory and typical experiments for coupling and correction. Therefore, a creative project will be carried out. In this project, eight soil samples will be selected, and with adding seven elements, BLM for seven metal elements will be developed. Then, by using cluster and principal component analyses, K-value crossover, optimal spatial statistics and other methodologies, the relationship between metal toxicity and physicochemical properties of homogeneous elements and the quantitative relationship of metal biological toxicity from homogeneity to heterogeneity will be studied. Furthermore, the intrinsic relationship between metallic forms, physicochemical properties and biotoxicity will be portrayed, the influencing mechanism of soil media will also be studied. Through the above analysis, QICAR and BLM of two types of biology will be coupled, and this can be further extended to the binary composite elements. Finally, a new method for evaluating ecological risk of arbitrary elements with different soil properties can be established.

土壤中污染金属元素种类日趋增多，与之对应的生态风险评价却严重滞后。目前发展的生物配体模型（BLM）能够有效评价金属生态风险，但其包含的元素种类十分有限，如能将依据元素理化性质预测其毒性的离子特征活性模型（QICAR）与BLM耦合来填充BLM空白，具有十分重要的意义，但极具挑战的是QICAR源于毒理数据丰富、环境条件均一的水环境，缺乏系统复杂的从同质（相同理化性质）基础转化至异质基础的理论和典型实验偶联修正，为此，本项目拟采集我国8个地区土壤，通过外源添加金属，研究建立和完善7种金属BLM，在此基础上通过聚类-主成分分析、K值交叉、最优空间统计等方法，构建同质土壤中金属毒性与金属理化性质关系模型及这种模型转化至异质土壤的对应关系，揭示金属形态、理化性质与生物毒性的内在联系和土壤介质影响机制，从而完成QICAR和BLM的耦合并推广应用，最终建立能够预测不同土壤性质下任意金属生态风险评价新方法。

土壤中污染金属元素的生态风险评价一直是土壤学关注的热点。目前发展的生物配体模型（BLM）能够有效评价金属生态风险，但其包含的元素种类有限，如能将离子特征活性模型（QICAR）与BLM耦合，可拓宽BLM应用范围，对元素生态风险评价具有十分重要的意义。本项目采用室内模拟试验，结合文献数据，综合应用多种数理统计方法，从模拟土壤溶液、人工土壤至田间土壤三个维度探索BLM和QICAR模型在土壤中的应用及耦合机制，取得的关键数据结果包括：（1）揭示了我国带典型土壤/土壤溶液性质中钴（Co）、铬Cr(Ⅵ)和钼Mo(Ⅵ)的植物毒性及影响因素，如土壤pH、粘粒含量（Clay%）、铝氧化物含量和CEC等，在此基础上建立了3种元素的阈值预测模型；（2）通过模拟土壤溶液揭示了不同伴随离子对Sb(V)和Se(VI)植物毒性的影响规律，构建Sb(V)和Se(VI)对植物毒性的BLM，获得相关参数，为BLM和QICAR模型的耦合提供数据基础。（3）结合Co、Cr(Ⅵ)和 Mo(Ⅵ)等田间数据和毒理学数据库资料，研究得出了离子特征结构参数如电化学势、原子离子化电位、第一水解常数等与元素毒性的关系，优化重组了与小麦和生菜元素毒性的离子特征结构新参数如生物配体参数logK，最终建立了基于不同土壤介质（土壤溶液/人工土壤/田间土壤）下的QICAR方程；（3）明晰了BLM和QICAR的耦合条件和方法，建立了土壤中BLM和QICAR的耦合模型并进行验证，结果表明，BLM-QICAR实测值和预测值在0.5倍范围内变化。进一步利用该模型对元素周期表第四、五周期的元素典型植物毒性进行预测并分组，得出最高、高度、中度和低度生态毒害的4组元素，为认识这些元素的生态毒害提供了数据支撑。项目研究结果可为土壤污染的评价与管理、控制与修复提供重要参考，具有重要的理论意义和应用前景。依托本项目目前已发表中英文论文16篇，SCI收录论文11篇（9篇为JCRQ1论文，1篇入选ESI高倍引），其中包含Journal of Hazardous Materials 2篇、Journal of Cleaner Production 1篇、Environmental Pollution 1篇、Chemosphere 2篇、Journal of Environmental Management1篇，获专利2项。