镉在土壤-植物-人体系统中迁移积累及其影响因子

Transfer of cadmium through soil-plant-human continuum and its affecting facto rs

环境镉 (Cd)污染对微生物、植物、动物和人体均可产生较大的危害。食物链是镉对普通人群造成健康危害的主要途径之一。污染土壤中的 1镉通过植物根系吸收与体内转运最终在植物可食部分中积累。Cd通过食物链进入人体并在体内蓄积受许多因素的影响 ,这些影响因素主要有 3个方面 :土壤性质 (土壤含镉量、p H、有机质、粘土矿物和土壤养分状况 ) ,植物特性 (包括基因型差异、根际过程和植物生理机制 )和人体微量元素营养状况等因素。

Cadmium is a non-essential element with no known benefits to plants, animals an d humans. However, due to geological processes (parent rocks) and anthropogenic sources (mining and smelting, fertilizer application and waste disposal), Cd in the environment has been increasing worldwide in the last two centuries or so. U nlike other metals, Cd is mobile in soils, and can be easily transferred from so il to plants leading to food safety problems. It has been generally recognized t hat food chain is a key pathway through that cadmium in the environment affects human health adversely. Accumulation of cadmium in the bodies will eventually ca use renal dysfunction and other diseases, and this has been reported in many cou ntries, such as Japan and China. \;There are several steps that control the transfer of Cd from the soil to humans. The first one is plant uptake from soils, and factors such as soil total Cd, cl ay contents, organic matter contents, other nutrients (P, Zn), pH and plant geno types can affect plant uptake processes. The second step is the redistribution o f Cd within plants, this depends on plant genotypes and nutritional status of th e plant. The third step is the bio-accessibility of Cd in foodstuffs. In this l ast step, the key controlling factor is the micronutrient (Fe, Ca and Zn) status of the person of concern. Marginal iron, calcium or zinc deficiency in the diet can significantly increase the bio-accessibility of Cd in foodstuffs. \;In order to mitigate the adverse effects of environmental Cd contamination, it i s necessary to investigate the mechanisms involved in the transfer of Cd through food chains to human and the factors that influence Cd absorption and accumulat ion in both plants and humans. Therefore, the study on cadmium in soil-plant-( animal)-human continuum has been a focus in environmental science worldwide sin ce the late 1980s. This paper attempts to provide an overview on recent advancem ents in studies on the factors that influence Cd transfer through food chain to human.