污灌区土壤-蔬菜系统中镉的生物有效性及迁移特征

The Bioavailability and Migration Characteristics of Cadmium in Soil-Vegetable System in Sewage Irrigation District

以北方城市污灌区——长春市季家和四间房为例,采用"五步提取法"分析了受污染土壤Cd的赋存形态与生物有效性的关系,通过计算Cd在土壤和蔬菜中的富集系数和迁移系数,探讨Cd在北方污灌区土壤-蔬菜系统中的污染和迁移特征。研究表明:污灌区土壤耕作层中Cd的形态特征为可交换态>铁锰氧化态>碳酸盐结合态或有机结合态>残渣态,季家和四间房污灌区土壤Cd的迁移系数为0.367、0.651;污灌区土壤镉含量超标,蔬菜各部位镉含量分布特征呈现根>叶>茎>果实的规律;季家和四间房白菜都是土壤-根富集系数>茎-叶迁移系数,Cd主要在根部富集;季家西红柿茎-叶迁移系数最高,而四间房西红柿的土壤-根富集系数最高;四间房白菜、西红柿土壤-根的富集系数均高于季家蔬菜,这与四间房土壤活性态Cd含量较高有关,且含量越高,蔬菜吸收量越大。

This article choose the northern city Changchun as the study area,using five-step extraction method to discuss the relationship between Cd fractions and bioavailability,calculating the migration coefficient and enrichment factor of Cd,and discussing the migration characteristics of cadmium in soil-vegetable system in sewage irrigation district.The research has shown that：the Cd fractions in soil mainly exists in the state of Cd exchangeable fractionCd ferric-manganese oxidation fractionCarbonate-bound or bound to organic Cd fraction residual Cd fraction,the Cd coefficient migration of Jijia and Sijianfang are 0.367and 0.651,the sewage irrigation district excessive the national standard value of cadmium,the cadmium content distribution characteristics presented the law of rootleafstemfruit;Jijia and Sijianfang shows the same feature：soil-root enrichment coefficientstem-leaves migration coefficient,Cd was mainly enriched in the roots;the migration coefficient of Jijia tomato stems-leaves is the highest,while the soil-root enrichment factor of Sijianfang is the highest;the soil-root enrichment factor of Sijianfang cabbage,tomatoes is higher than the Jijia vegetables,because of the active form Cd is higher than Jijia,the higher the content in soil,the larger the absorption by vegetables.