蔬菜不同部位对DDTs的富集与分配作用

Accumulation and Distribution of DDTs in Different Parts of Vegetables

在可控条件下研究了人为污染土壤中DDT类污染物在蔬菜(菠菜和胡萝卜)不同部位的富集与分配规律。结果表明,DDT类污染物在菠菜和胡萝卜叶部和根部均有一定富集,其中菠菜叶面富集量占富集总量的68.6%～92.2%之间;而胡萝卜叶部富集占富集总量的34.9%～41.6%之间。不同DDTs在菠菜和胡萝卜体内的生物富集量呈:p,p′-DDE>p,p′-DDT>p,p′-DDD>o,p′-DDE>o,p′-DDT的规律。DDTs通过不同途径在菠菜和胡萝卜内的生物富集系数表现如下规律:BCF大气-菠菜>BCF大气-胡萝卜>BCF土壤-胡萝卜>BCF土壤-菠菜。不同DDTs在蔬菜体内的生物富集系数表现为:BCFp,p′-DDE>BCFo,p′-DDE>BCFp,p′-DDD>BCFp,p′-DDT>BCFo,p′-DDT。由于DDTs在蔬菜体内富集后,可沿食物链传递和放大,对农产品质量和人体健康构成直接威胁。

Accumulation by plants is an important step for transferring DDT and its metabolites DDE and DDD into the terrestrial food chains. A better understanding the process of DDT and its metabolites accumulation by plants is an essential approach to assess crop contamination and subsequent human exposure. Uptake and distribution of DDTs in different parts of the vegetables（spinach and carrot） from the artificially spiked soils were investigated under the controlled conditions. The results indicated that spinach and carrot can either accumulate DDTs from air through the aboveground parts（leaves） or from soil through the roots. About 68.6% to 92.2% of the DDTs accumulated in the spinach were mainly stored in the leaves. Approximately 58.4% to 65.1% of the DDTs were detected in the roots of carrot. The amounts of the DDTs accumulated in the spinach and carrot were in the same order： p,p＇-DDE〉p,p＇-DDT〉p,p＇-DDD〉o,p＇-DDE〉o,p＇-DDT. Furthermore, the contents of p,p＇-DDT and o,p＇-DDT accumulated in spinach and carrot were lower than their metabolites p,p＇-DDE, o,p＇-DDE. The accumulative abilities, expressed as a bioconcentration factors（BCF）, of DDTs in the spinach and carrot through different ways were in the following sequence ： BCFair-spinach〉BCFair-carrot〉BCFsoil-carrot〉BCFsoil-spinach. Besides, the bioconcentration factor of DDT, DDE and DDD in vegetables showed the following order： BCFp,p＇-DDE〉BCFo,p＇-DDE〉BCFp,p＇-DDD〉BCFp,p＇-DOt〉BCFo,p＇-DOT. Because of the high accumulative ability in the vegetables, DDT may produce potential risks to food quality and human health.