土壤镉污染对小麦生长及镉吸收的影响

为明确小麦对镉的吸收状况，以扬麦13号为材料，采用盆栽试验，分析了不同外源镉污染水平（0、5、10、20 mg·kg^-1和50mg·kg^-1）对小麦生长状况、光合生理指标、磷含量及镉吸收的影响，并使用目标危险系数（THQ）法预估了食用该小麦籽粒对人体健康产生的风险。结果表明，低浓度的外源镉（<10 mg·kg^-1）未显著影响小麦的生长速率、各部位生物量、光合生理指标和小麦各部位的磷含量。但当外源镉浓度增大时，小麦生长速率受到抑制。当外源镉浓度>20 mg·kg^-1时，小麦生物量、蒸腾速率及磷含量显著降低。小麦各部位的镉含量及籽粒中镉的THQ值都随镉污染水平的增大而增加，各污染水平下THQ值均大于1，且儿童的THQ值大于成人。研究结果显示，虽然中、低浓度的外源镉不会对小麦生长造成显著的影响，但在该环境中生长的小麦籽粒中的镉含量仍然会对人体造成明显的不利影响，表明仅依靠镉对小麦的生长影响不足以说明镉对小麦及人体的危害，必须综合各个指标来讨论。

Effects of cadmium pollution in soil on growth and cadmium uptake of wheat

In order to clarify the uptake of Cadmium (Cd) by wheat, the effects of different exogenous Cd concentration (0, 5, 10, 20 mg·kg^-1 and 50 mg·kg^-1) on wheat growth, photosynthetic physiological indexes, phosphorus concentration and Cd uptake were examined in a pot experiment using the cultivar of Yangmai 13. The risks to human health were also estimated by the target hazard factor (THQ) method. The results showed that growth rate, biomass, net photosynthesis rate, transpiration rate and phosphorus concentration of wheat plant were not significantly affected by low exogenous Cd concentration, while high exogenous Cd concentration inhibited wheat growth. When exogenous Cd concentration was higher than 20 mg·kg^-1, biomass, transpiration and phosphorus concentration of wheat significantly decreased. Cd concentration in stem, leaf and husk of wheat and THQ of Cd in grain all increased with increase of exogenous Cd concentration. The THQ of Cd for children was higher than that for adults, and both THQ>1. The results showed low exogenous Cd concentration didn''t significantly affect growth of wheat plant, but Cd concentration in edible parts would have a significant adverse impact on human, which indicated that the effect of Cd on wheat growth alone was not enough to explain the harm of Cd to wheat and human. All the indexes must be considered.