Zhang Yalu, Su Baowei, Shao Shuangshuang, Li Ning, Jiao He, Dan Yang, Zhang Huan, Gao Chao
School of Geography and Ocean Science, Nanjing University, Nanjing 210023, China.
School of Resource and Environment, Henan University of Engineering, Zhengzhou 451191, Henan, China.
Sci Total Environ. 2023 Dec 20;905:167777. doi: 10.1016/j.scitotenv.2023.167777. Epub 2023 Oct 15.
Rare Earth Elements (REEs) are crucial for a low-carbon economy but overuse pollutes ecosystems. Studying their behavior and source in agricultural soils provides vital insights for soil management. To address this, we collected an extensive dataset comprising 2901 topsoil and 733 subsoil samples from an agriculturally dominant region in eastern China, characterized by uniform parent material. This comprehensive dataset enabled a thorough examination of the geochemical behavior and sources of REEs in the region. Our findings revealed the feasibility of utilizing La, Ce, and Y to predict ΣREE, LREE, HREE, and LREE/HREE ratios, thereby enhancing the REEs database for eastern China. The average ΣREE concentration in the study area measured 193.0 μg/g, with LREEs constituting 89 % of this total, representing a slight enrichment relative to the Upper Continental Crust. Notably, the electron-donating ability of Ce exhibited a correlation with Mn, indicating its potential as an indicator of redox reactions. The results obtained through structural equation modeling and random forest analysis identified Al, Ti, and K as the most influential environmental factors affecting ΣREE concentrations. Additionally, the indirect impact of K on ΣREE through pH was established. The strong correlation observed between major elements and Heavy Rare Earth Elements (HREEs) shed light on the mechanisms responsible for the notable fractionation of REEs in topsoil. Furthermore, our investigation underscored the substantial influence of pedogenetic processes on the enrichment and leaching of REEs. Source analysis pinpointed significant contributors to REEs, including fertilizers, pesticides, domestic wastewater, coal fly ash, and the native soil parent material. In conclusion, our study emphasizes the pressing need for judicious control of anthropogenic REE inputs. This step is pivotal not only for ensuring the sustainable utilization of soil but also for ultimately safeguarding ecosystems and environmental quality.
稀土元素（REEs）对低碳经济至关重要，但过度使用会污染生态系统。研究它们在农业土壤中的行为和来源可为土壤管理提供重要见解。为解决这一问题，我们收集了一个广泛的数据集，该数据集包含来自中国东部一个以农业为主的地区的2901个表层土壤和733个下层土壤样本，该地区具有统一的母质。这个全面的数据集使我们能够深入研究该地区稀土元素的地球化学行为和来源。我们的研究结果表明，利用镧、铈和钇来预测总稀土元素、轻稀土元素、重稀土元素和轻稀土元素/重稀土元素比值是可行的，从而增强了中国东部的稀土元素数据库。研究区域内总稀土元素的平均浓度为193.0微克/克，其中轻稀土元素占总量的89%，相对于上地壳略有富集。值得注意的是，铈的供电子能力与锰呈相关性，表明其作为氧化还原反应指标的潜力。通过结构方程建模和随机森林分析获得的结果确定铝、钛和钾是影响总稀土元素浓度的最具影响力的环境因素。此外，还确定了钾通过pH值对总稀土元素的间接影响。主要元素与重稀土元素之间的强相关性揭示了表层土壤中稀土元素显著分馏的机制。此外，我们的调查强调了成土过程对稀土元素富集和淋溶的重大影响。源分析确定了稀土元素的重要贡献者，包括肥料、农药、生活污水、粉煤灰和原生土壤母质。总之，我们的研究强调了明智控制人为稀土元素输入的迫切需要。这一步骤不仅对于确保土壤的可持续利用至关重要，而且对于最终保护生态系统和环境质量也至关重要。
