Huang Hui, Tang Zhi-Xian, Qi Hong-Yuan, Ren Xiao-Tong, Zhao Fang-Jie, Wang Peng
College of Resources and Environmental Sciences and Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, China; College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China; State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
College of Resources and Environmental Sciences and Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, China; State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
Environ Pollut. 2022 Feb 1;294:118650. doi: 10.1016/j.envpol.2021.118650. Epub 2021 Dec 6.
Cadmium (Cd) contamination in paddy soil often results in elevated Cd concentrations in rice grain, which is a serious concern threatening food safety. Most of the Cd accumulated in rice grain is derived from its remobilization in paddy soil during the grain filling period when paddy water is drained. We have previously shown that the voltaic cell effect controls the oxidative release of cadmium sulfide (CdS) during the drainage period. Metal sulfides with lower electrochemical potentials than CdS can suppress the oxidation of CdS. In the present study, we tested whether amendments of ZnSO or MnSO could enhance the suppressive voltaic effect on Cd release and subsequent accumulation in rice grain. The one-time addition of ZnSO (75 kg/ha Zn) decreased CaCl-extractable Cd concentrations in soils by 32-64% in pot experiments and by 16-30% in field trials during the drainage period. Consequently, Cd concentrations in brown rice were reduced by 74-87% and 60-72% in pot experiments and field trials, respectively. Importantly, this effect persisted in the second year without further addition. The amendment of MnSO had similar effects in decreasing soil extractable Cd and Cd concentrations in brown rice. These effects were not attributed to the addition of sulfate. A single application of such doses of ZnSO or MnSO (e.g. 75-150 kg/ha Zn or Mn) only caused a marginal increase in soil Zn or Mn concentrations and had no significant impact on grain yield. Taken together, amendments of ZnSO and/or MnSO (at the rate of 75-150 kg/ha Zn and or Mn) formed a protective voltaic cell partner against the oxidative dissolution of CdS and thus were highly effective in reducing Cd accumulation in rice grain. This work provides a simple but effective method to decrease soil Cd availability during soil drainage and mitigate Cd accumulation in rice to ensure food safety.
稻田土壤中的镉（Cd）污染常常导致稻米中镉浓度升高，这是威胁食品安全的一个严重问题。稻米中积累的大部分镉来自灌浆期稻田排水时土壤中镉的再活化。我们之前已经表明，伏打电池效应控制着排水期硫化镉（CdS）的氧化释放。电化学电位低于CdS的金属硫化物可以抑制CdS的氧化。在本研究中，我们测试了添加硫酸锌（ZnSO）或硫酸锰（MnSO）是否能增强对镉释放及随后在稻米中积累的抑制性伏打效应。一次性添加硫酸锌（75千克/公顷锌）使盆栽试验中排水期土壤中氯化钙可提取镉浓度降低了32% - 64%，田间试验降低了16% - 30%。因此，盆栽试验和田间试验中糙米中的镉浓度分别降低了74% - 87%和60% - 72%。重要的是，这种效果在第二年无需进一步添加时仍然存在。添加硫酸锰也有类似效果，可降低土壤中可提取镉和糙米中的镉浓度。这些效果并非归因于硫酸盐的添加。单次施用这种剂量的硫酸锌或硫酸锰（例如75 - 150千克/公顷锌或锰）只会使土壤锌或锰浓度略有增加，对谷物产量没有显著影响。综上所述，添加硫酸锌和/或硫酸锰（75 - 150千克/公顷锌和/或锰）形成了一个针对CdS氧化溶解的保护性伏打电池伙伴，因此在减少稻米中镉积累方面非常有效。这项工作提供了一种简单但有效的方法，可在土壤排水期间降低土壤镉有效性并减轻稻米中的镉积累，以确保食品安全。
