Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Zhengzhou University of Light Industry, Zhengzhou 45000, China.
Institute of Geographical Sciences and Natural Resource Research, Chinese Academy of Sciences, Beijing 100101, China.
Sci Total Environ. 2022 Apr 20;818:151832. doi: 10.1016/j.scitotenv.2021.151832. Epub 2021 Nov 21.
Lead (Pb) pollution in wheat has received considerable research attention globally due to its persistence and ease of accumulation, posing severe health risks to humans. This study explored the relative contribution of the environmental medium (atmospheric deposition and soil) and wheat internal organs to Pb accumulation in wheat grains, using field experiments by contrasting treatments. The concentration and bioavailability of Pb in the soil were significantly lower than those of atmospherically deposited Pb (P < 0.05). Pb accumulation rate in wheat grains was consistent with the grain filling rate, which first increased and then decreased, reaching the highest level at the middle filling stage. Pb isotope analysis showed that atmospheric deposition was the main source of Pb in the shoots of wheat plants, contributing more than 80.0% of Pb in grains. Although the roots had the highest Pb concentration, the spikes had the greatest relative contribution (58.4%) to Pb accumulation in the wheat grains, followed by that of the leaves (24.5%), whereas the contribution of roots was the lowest (17.1%) among all plant organs. In addition, among all leaves, the contribution of flag leaves to Pb accumulation in the grain was higher than the cumulative contribution of all other leaves, where flag leaves and other leaves contributed 13.8% and 10.7%, respectively. Collectively, the absorption of atmospherically deposited Pb by wheat spikes is the leading cause of Pb pollution in wheat grains. These results may aid in formulating strategies to reduce Pb concentration in grains and ensure food quality and safety.
由于铅（Pb）具有持久性和易于积累的特点，其在小麦中的污染已引起全球范围内的广泛关注，对人类健康构成了严重威胁。本研究通过对比处理的田间实验，探讨了环境介质（大气沉降和土壤）和小麦内部器官对小麦籽粒中 Pb 积累的相对贡献。土壤中 Pb 的浓度和生物有效性明显低于大气沉降 Pb（P<0.05）。小麦籽粒中 Pb 的积累速率与籽粒灌浆速率一致，呈先增加后减少的趋势，在灌浆中期达到最高水平。Pb 同位素分析表明，大气沉降是小麦植株地上部分 Pb 的主要来源，对籽粒中 Pb 的贡献率超过 80.0%。尽管根部的 Pb 浓度最高，但穗部对小麦籽粒中 Pb 积累的相对贡献率（58.4%）最大，其次是叶片（24.5%），而根部的贡献率最低（17.1%）。此外，在所有叶片中，旗叶对籽粒中 Pb 积累的贡献高于所有其他叶片的累积贡献，旗叶和其他叶片的贡献率分别为 13.8%和 10.7%。总之，小麦穗部对大气沉降 Pb 的吸收是导致小麦籽粒 Pb 污染的主要原因。这些结果可能有助于制定降低籽粒中 Pb 浓度、确保粮食质量和安全的策略。
