重金属化学活性评估方法准确性质疑--以煤矸石样品为例

重金属元素化学活性的大小是决定它们环境行为最主要的因素之一,我们曾分别用总量法,实验模拟法,环境地球化学法和化学形态分析法对煤矸石样品所含的重金属元素进行过环境影响分析,试图了解自然风化条件下这些有害元素潜在的生态环境效应,结果发现重金属元素的化学活性除了与它们在样品中含量的高低,赋存状态和化学形态等因素有关外,更主要地是取决于样品基质的组成和结构,由于大量有机质的络合和风化过程中生成的铁的胶体的吸附,从煤矸石释放出的重金属元素的化学活性受到明显限制,它们对环境的污染可能仅限于煤矸石堆周围有限的范围。

Discussion about Accuracy of Assessment Method of Chemical Mobility of Heavy Metals

Knowledge of chemical mobility of heavy metals is fundamental to understanding their toxicity,bioavailability and geochemical behavior.Different approaches,i.e.,total content,experimental simulation,mineralogical means and sequential extractions,were employed to analyze the environmental effect of heavy metals in the coal mine spoil.The results demonstrate that the mobility of heavy metals in coal mine spoils depends not only on their concentration,existing states and the stability of their host minerals but also on the properties of the coal mine spoils.In the process of natural weathering,metals released from coal mine spoils are adsorbed and complexed by the iron oxyhydroxide colloid resulting from pyrite oxidization and organic matter,and the migration of these metals are limited.