中文摘要：

生物配体模型（BLM）是一个理论的、潜在的机理方法,用来评估金属离子在水体及土壤体系的生物有效性。BLM概念中,毒性与生物配体位点被占据的比例有直接关系,而被占据的比例又受溶液组成成分的影响。该研究综述了当前水培体系以及土壤溶液体系中不同植物品种的BLM概况,通过对其特征性常数及毒性阈值的比较发现,重金属离子的毒性与条件结合常数（logK）呈显著正相关,即金属毒性越强,logK值越大。不同重金属元素对植物的毒性强弱总体符合以下规律,即Cu、Ag、Cd、Cr（Ⅲ）〉Co〉Ni〉Zn。不同植物测试终点对重金属毒性的敏感程度大致为：莴苣根长〉西红柿茎叶≥大麦根长、小麦根长〉葡萄根长〉豌豆根长。水培体系中影响金属毒性的主要竞争离子为H、Mg、Ca、K,且竞争能力呈依次递减的顺序。除自由金属离子形态之外,其他碱性复合形态离子如MCO3（x＋）、MOH（x＋）、MHCO3（x＋）同样具有生物有效性/毒性,然而毒性贡献的归属是根据金属元素的不同与体系pH的不同而变化。真实的土壤溶液相对于水培体系的BLM更加复杂,导致陆地系统的生物配体模型（t-BLM）研究存在很多不确定性。总之,BLM的研究和发展为重金属元素在水体及土壤体系的风险评价提供了切实可依的重要手段。

英文摘要：

The biotic ligand model（BLM） is a theoretical, potentially mechanistic approach to assess metal bioavailability in soil and aquatic systems. In a BLM, toxicity is linked to the fraction of biotic ligand occupied, which in turn, depends on the various components of the solution, including activity of the metal. Bioavailability is a key factor in determining toxicity and uptake of metals in organisms. In this study, the present status of BLM development based on water and soil is summarized.For plant species, toxicity of heavy metals is positively correlated with the conditional binding constants（logK）, values are displayed in the order as Cu, Ag, Cd, Cr（ Ⅲ）〉 Co〉 Ni 〉Zn. Also, the sensitivity of different plant species to metals is shown in the order of lettuce root elongation 〉tomato shoot growth ≥ barley and wheat root elongation 〉grape root elongation pea root elongation. Moreover, the main competitive cations for binding sites of biotic ligand in solutions are H＋,Mg2＋, Ca2＋ and K＋, and H＋（K＋） appears the strongest（weakest） competition ability. Besides of free metal ions, other complex metal speciations, i.e. MCO3（x＋）, MOH（x＋） and MHCO3（x＋）, could be also toxic/bioavailable to plant species dependable of metal species and pH ranges in solution systems. In conclusion, BLM provides a potential method for risk assessment of heavymetal elements in water and soil systems.