用火焰原子吸收光谱法(FAAS)测定了土壤样品中铜、锰两种重金属元素的含量,并以此作判据比较了直接法和间接法提取土壤中重金属元素多种化学形态的优缺点。两种方法均以Tessier等提出的连续提取法为基础,采用4种不同的提取溶剂按先后顺序将土壤中元素分别以可交换态、碳酸盐结合态、铁锰氧化物结合态和有机结合态的形态提取。试验结果表明:直接法测定时,由于有些提取溶剂的盐浓度较高,在FAAS测定中产生基体干扰,此外也发现提取溶剂中存在重金属元素,造成较高的空白值,由此造成较明显的分析误差。而在总量测定和残留物分析中,上述问题可避免。因此认为用间接法测定优于直接法。

Virtues and defects of the direct method (sequential extraction procedure proposed by Tessier and etc.) and the indirect method for speciation of heavy metals in soil were studied comparatively using the data of Cu and Mn in soil found by FAAS as criterion. In both the 2 methods, species of heavy metals in exchangeable state, combined carbonate state, combined oxides of iron and manganese state and combined organic state were first separated by applying the sequential extraction produre with 4 different extraction solvents. It was found that due to high concentration of salt in the extraction solvents which led to matrix interference in FAAS analysis and due to remarkable blank values found in the reagents used, significant errors were found in the direct method. The indirect method was preferred to avoid the interferences mentioned above.