Abstract: The contents of heavy metals in sediment are decided by lots of factors such as pH, Eh, TOC, Fe-Mn oxide etc. And their toxicity are up to their forms, bioavailability and environmental features. It is well know that heavy metals can form sulfides that are not soluble in water, but we are not quite clear with acid-volatile sulfide (AVS) can also form sulfides with the heavy metals. AVS plays an important role on mediating the toxicity of the heavy metals in sediment. We assessed the pollution of heavy metals in the main rivers of Hong Kong based on the molar ratio of Simultaneous Extract Metals (SEM) and AVS. This method is helpful on predicting the toxicity of heavy metals.

Key words: Hong Kong, sediment, heavy metals, toxicity, AVS, SEM

摘要： 沉积物中重金属的含量取决于样品的酸度、氧化还原电位、总有机碳、铁锰氧化物含量等诸多因素，而沉积物中重金属的毒性取决于其赋存的化学形态、生物有效性和环境特征。众所周知，重金属可形成不溶于水的硫化物，但以往对酸可挥发硫(AVS)能与重金属形成硫化物认识不太清楚。现已查明，重金属在沉积物中的毒性大小，AVS起了重要作用。根据酸化过程中被溶解释放的重金属(SEM)与AVS当量摩尔浓度关系所产生的生物有效性，评价香港主要河流重金属的污染危害，用此方法对预测重金属毒性很有实际意义。

关键词: 香港, 沉积物, 重金属, 毒性, 酸可挥发硫, 同时释放金属