Wang Lin, Gu Peng-Lei, Li Ran, Xu Ying-Ming, Sun Yue-Bing, Liang Xue-Feng, Dai Jing-Jing
Agro-environmental Protection Institute, Ministry of Agriculture, Tianjin 300191, China.
Key Laboratory of Original Agro-Environmental Pollution Prevention and Control, Ministry of Agriculture, Tianjin 300191, China.
Huan Jing Ke Xue. 2018 Jun 8;39(6):2944-2952. doi: 10.13227/j.hjkx.201711157.
Two cultivars of pakchoi with different cadmium (Cd) accumulation were grown in nutrient solutions containing low and sufficient zinc (Zn) levels. ZnSO and ZnNa EDTA were applied as foliar fertilizers. The bioaccessibilities of Cd and Zn in pakchoi were assessed by the digestion method, and the bioaccessible established daily intakes (BEDI) of Cd and Zn from pakchoi were calculated. The effect of foliar zinc application on concentrations, bioaccessibilities, and BEDIs of Cd and Zn in pakchoi was evaluated. Results show that the Cd concentrations in shoots of the tested pakchoi cultivars under sufficient Zn condition were significantly lower than those under low Zn condition, and foliar application of ZnNa EDTA significantly decreased the Cd concentrations of pakchoi. The tested pakchoi cultivars with sufficient Zn had a significantly higher mean shoot Zn concentration than those with low Zn. Foliar Zn treatments significantly increased shoot Zn concentrations of pakchoi, with the highest in the ZnSO treatment. Cd bioaccessibility in the tested pakchoi cultivars with sufficient Zn was significantly lower than that with low Zn. Foliar applied Zn could significantly reduce Cd bioaccessibility in the gastric phase, with a maximal reduction of 35.81% compared to the control. Foliar treatment with ZnSO could significantly decrease Cd bioaccessibility in the small intestinal phase, with a maximal reduction of 59.24% compared to the control. Foliar Zn treatments reduced significantly the Zn bioaccessibility of pakchoi in the gastric and small intestinal phases, with a maximal reduction of 68.90% compared to the control. The reduction of Zn bioaccessibility was higher in the ZnSO treatment than in the ZnNa EDTA treatment. Via the consumption of the Cd-contaminated common cultivar Hanlv, the BEDI values of Cd were higher than that of the provisional tolerable daily intake (PTDI) standard of WHO [0.83 μg·(kg·d)]. However, via the consumption of the low-Cd accumulating cultivar Huajun or pakchoi with foliar application of ZnSO, the BEDI values of Cd decreased significantly and were below the PTDI value. Via the consumption of pakchoi in the control or low-level ZnNa EDTA treatments, the BEDI values of Zn were below that of the recommended nutrient intake for Zn. However, via the consumption of pakchoi with foliar application of ZnSO or high-level ZnNa EDTA, the BEDI values of Zn were higher than that of the recommended nutrient intake and met the human needs for Zn from vegetables. Under the ZnSO treatment, the BEDI values of Zn from pakchoi were the highest. In conclusion, foliar zinc application could significantly reduce the bioaccessibilities of Cd and Zn in pakchoi and the BEDI values of Cd and increase the BEDI values of Zn. Foliar application with ZnSO was the most suitable treatment to reduce Cd intake and increase Zn intake from pakchoi.
在含有低锌和充足锌水平的营养液中种植了两个镉（Cd）积累量不同的小白菜品种。硫酸锌（ZnSO）和乙二胺四乙酸锌钠（ZnNa EDTA）作为叶面肥施用。采用消化法评估小白菜中镉和锌的生物可给性，并计算小白菜中镉和锌的生物可给性确定每日摄入量（BEDI）。评估了叶面喷施锌对小白菜中镉和锌的浓度、生物可给性及BEDI的影响。结果表明，充足锌条件下，受试小白菜品种地上部的镉浓度显著低于低锌条件下的，叶面喷施乙二胺四乙酸锌钠显著降低了小白菜的镉浓度。充足锌条件下的受试小白菜品种地上部锌平均浓度显著高于低锌条件下的。叶面锌处理显著提高了小白菜地上部锌浓度，硫酸锌处理下的最高。充足锌条件下受试小白菜品种的镉生物可给性显著低于低锌条件下的。叶面喷施锌可显著降低胃相中镉的生物可给性，与对照相比最大降低了35.81%。硫酸锌叶面处理可显著降低小肠相中镉的生物可给性，与对照相比最大降低了59.24%。叶面锌处理显著降低了小白菜在胃相和小肠相中的锌生物可给性，与对照相比最大降低了68.90%。硫酸锌处理中锌生物可给性的降低幅度高于乙二胺四乙酸锌钠处理。通过食用受镉污染的常见品种汉绿，镉的BEDI值高于世界卫生组织临时每日耐受摄入量（PTDI）标准[0.83 μg·(kg·d)]。然而，通过食用低镉积累品种华军或叶面喷施硫酸锌的小白菜，镉的BEDI值显著降低并低于PTDI值。通过食用对照或低水平乙二胺四乙酸锌钠处理的小白菜，锌的BEDI值低于锌的推荐营养素摄入量。然而，通过食用叶面喷施硫酸锌或高水平乙二胺四乙酸锌钠的小白菜，锌的BEDI值高于推荐营养素摄入量，满足了人体从蔬菜中获取锌的需求。在硫酸锌处理下，小白菜中锌 的BEDI值最高。总之，叶面喷施锌可显著降低小白菜中镉和锌的生物可给性以及镉的BEDI值，并提高锌的BEDI值。叶面喷施硫酸锌是减少镉摄入和增加小白菜锌摄入的最合适处理方法。
