土壤－水稻系统中镉迁移与阻控.

Rice grain contaminated with elevated cadmium（Cd）in some areas of Southern China is serious, with this problem attributable to some reasons including increasing inputs of Cd into soils, soil acidification, typical water management of paddy soils, and certain varieties of rice grain with a higher Cd accumulation capacity planted in the South. Soil total Cd concentrations are not worse in China than in other regions of the world, but the bioavailability of Cd is higher in Chinese soils. Soil Cd bioavailability varies largely among different regions in China; soils from Hunan Province are generally higher in Cd bioavailability than those from Guangxi and Guizhou. The grain filling is the key period for the accumulation of Cd in the rice grain, with this period concurrent with soil drainage. The remobilization of Cd during this period is mainly controlled by the voltaic effect, free radical oxidation effect and pH-dependent Fe oxide adsorption effect. Amendment of Zn and Mn fertilizers can suppress the oxidative dissolution of CdS during soil drainage through the voltaic effect. Raising soil pH can reduce the partitioning of Cd into the soil solution, thus decreasing soil Cd solubility. Several key genes involved in Cd uptake, translocation, and sequestration in rice have been cloned. Allelic variations of some genes to some extent explain the variations of grain Cd in different cultivars. The Cd-safe rice grain can be achieved by reducing soil Cd bioavailability, decreasing the uptake/translocation of Cd to the grain, and removing Cd from soils. Hence, the use of low Cd rice cultivars, liming, and applications of Zn/Mn fertilizers are particularly effective and economical for producing safe rice in some Cd-contaminated soils. Rice cultivars with the ability to accumulate high Cd can be used as a feasible phytoremediation method for reducing Cd from the soil. [ABSTRACT FROM AUTHOR]