Hebei Key Laboratory of Strategic Critical Mineral Resources, Hebei GEO University, Shijiazhuang, 050031, China; Institute of Resource and Environmental Engineering, Hebei GEO University, Shijiazhuang, 050031, Hebei, China.
Hebei Key Laboratory of Strategic Critical Mineral Resources, Hebei GEO University, Shijiazhuang, 050031, China.
J Environ Manage. 2024 Nov;370:122909. doi: 10.1016/j.jenvman.2024.122909. Epub 2024 Oct 13.
Given the research situation of toxic metals (TMs) pollution in farmland soil, it is very critical to study the clay influence on TMs environmental behavior to meet the aim of lowering TMs pollution. This research explores the association among clay minerals and TMs and the health risks in TMs combined polluted farmland of northern China. In this study, agricultural soil, wheat grain, and atmospheric sediments from nonferrous metal smelting (NMS) areas were collected and investigated to determine the effect of clay minerals on TMs. The results show that the content ranges of Cd (0.199 mg/kg ∼1.98 × 10 mg/kg), Pb (0.228 × 10 mg/kg ∼ 4.87 × 10 mg/kg), Cu (0.187 × 10 mg/kg ∼ 4.57 × 10 mg/kg), and Zn (0.559 × 10 mg/kg ∼ 3.04 × 10 mg/kg) in the agricultural soil. In particular, Cd has reached heavy pollution by the high pollution index (6.74). The findings indicate that Cd and Pb in wheat grain were influenced by their exchangeable fractions in soil, according to a significant relationship between Cd and Pb in soil and wheat grain. XRD-SEM suggests that TMs come from atmospheric sediments associated with NMS emissions by microsphere signatures with surface burn marks. Meanwhile, Geographical detector indicated that clay was the primary contributor to spatial distribution of Cd and Pb. In addition, XRD results showed that I/S (a mixed layer of illite and smectite), illite, chlorite, and kaolinite co-existed. Whereas the clay minerals with this ratio did not demonstrate better adsorption capacities for Cd and Pb due to the Cd percentage of the residual fraction being less than 9%. The result of negative correlation between exchangeable Cd and clay minerals implies that illite, chlorite, and kaolinite may preferentially adsorb Cd and Pb. It is similar to the relationship between Cd and Pb in wheat grain and illite, chlorite, and kaolinite. In addition, the health assessment result show that the negative correlation between clay minerals and the noncarcinogenic hazard quotient (HQ) and indicate that clay minerals could reduce the noncarcinogenic risk of Pb and Cd for children. Our findings provide a potential mechanism and application of clay minerals for the remediation of soil contaminated with TMs.
鉴于农田土壤中有毒金属 (TMs) 污染的研究现状，研究粘土对 TMs 环境行为的影响以降低 TMs 污染非常关键。本研究探讨了粘土矿物与 TMs 的关系以及中国北方重金属复合污染农田的健康风险。本研究采集并调查了有色金属冶炼 (NMS) 区的农业土壤、小麦籽粒和大气沉积物，以确定粘土矿物对 TMs 的影响。结果表明，Cd（0.199mg/kg∼1.98×10mg/kg）、Pb（0.228×10mg/kg∼4.87×10mg/kg）、Cu（0.187×10mg/kg∼4.57×10mg/kg）和 Zn（0.559×10mg/kg∼3.04×10mg/kg）在农业土壤中的含量范围。特别是 Cd 的高污染指数（6.74）达到重度污染。研究结果表明，小麦籽粒中的 Cd 和 Pb 受到土壤中可交换态分数的影响，土壤和小麦籽粒中的 Cd 和 Pb 之间存在显著关系。XRD-SEM 表明，TMs 来自与 NMS 排放相关的大气沉积物，其特征是带有表面烧伤痕迹的微球。同时，地理探测器表明，粘土是 Cd 和 Pb 空间分布的主要贡献者。此外，XRD 结果表明，I/S（伊利石和蒙脱石的混合层）、伊利石、绿泥石和高岭石共存。然而，由于残留相中 Cd 的百分比小于 9%，这种比例的粘土矿物对 Cd 和 Pb 没有表现出更好的吸附能力。可交换态 Cd 与粘土矿物之间的负相关关系表明，伊利石、绿泥石和高岭石可能优先吸附 Cd 和 Pb。这与小麦籽粒中 Cd 和 Pb 以及伊利石、绿泥石和高岭石之间的关系相似。此外，健康评估结果表明，粘土矿物与非致癌危害商 (HQ) 呈负相关，表明粘土矿物可以降低儿童对 Pb 和 Cd 的非致癌风险。我们的研究结果提供了粘土矿物用于修复 TMs 污染土壤的潜在机制和应用。
