Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; Key Laboratory of Petroleum Resources, Gansu Province, Lanzhou, 730000, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; Key Laboratory of Petroleum Resources, Gansu Province, Lanzhou, 730000, China.
Ecotoxicol Environ Saf. 2021 Jan 1;207:111234. doi: 10.1016/j.ecoenv.2020.111234. Epub 2020 Sep 9.
The activity and fate of heavy metals (HMs) from mining and smelting activities in farmland soil is of great significance to effectively prevent the excessive enrichment of HMs in crops. This study focuses on Baiyin area, a typical mining city in northwest China. In this example, the sources, speciation, and fate of HMs in the farmland soil, and the migration and enrichment characteristics of HMs in the different parts of crops planted in different areas were studied in detail combining the chemical sequential extraction and Pb isotope approaches. Results showed that the mean anthropogenic contributions of HMs in farmland soils were approximately 85%, 88%, 76%, and 41% for the ore district (OD), Xidagou sewage irrigation area (XSIA), Dongdagou sewage irrigation area, and the Yellow River irrigation area, respectively, and the risk that HMs were excessively accumulated in crops in OD and XSIA was high. Compared with soil residual fractions, the isotope ratios Pb/Pb in non-residual fractions (1.1304-1.1669) were closer to the values of local ores, suggesting that anthropogenic HMs from mining and smelting activities were mainly enriched in the non-residual fractions. The isotope ratios Pb/Pb in crops (1.1398-1.1686) further confirmed that those anthropogenic HMs were more easily absorbed and concentrated by crops. HMs contents in leaves from OD and XSIA were generally higher than that in roots, suggesting that atmospheric deposition in OD and XSIA had a greater impact on the HMs concentration of crop leaves，while the excess rate of HMs in grain/fruit was the lowest in all parts of crops. The division and classification of crop planting in mining area can effectively help minimize the risk that HMs from anthropogenic source enter the human body through the food chain.
采矿和冶炼活动中重金属（HMs）在农田土壤中的活性和归宿，对于有效防止 HMs 在作物中过度富集具有重要意义。本研究以中国西北典型矿业城市——白银地区为例，结合化学连续提取和 Pb 同位素方法，详细研究了农田土壤中 HMs 的来源、形态、归宿，以及不同区域种植的不同作物各部位中 HMs 的迁移和富集特征。结果表明，矿区（OD）、洗地沟污水灌溉区（XSIA）、东大沟污水灌溉区和黄河灌溉区农田土壤中 HMs 的人为贡献率分别约为 85%、88%、76%和 41%，OD 和 XSIA 区作物中 HMs 过度积累的风险较高。与土壤残留态相比，非残留态的同位素比值 Pb/Pb（1.1304-1.1669）更接近当地矿石的值，表明采矿和冶炼活动中的人为 HMs 主要富集在非残留态。作物中同位素比值 Pb/Pb（1.1398-1.1686）进一步证实了这些人为 HMs 更容易被作物吸收和浓缩。OD 和 XSIA 区叶片中的 HMs 含量普遍高于根部，表明 OD 和 XSIA 区的大气沉降对作物叶片中 HMs 浓度的影响较大，而各部位中谷物/果实中 HMs 的超标率最低。矿区作物种植分区分类可以有效帮助降低人为源 HMs 通过食物链进入人体的风险。
