College of Geography and Environment, Shandong Normal University, Jinan, 250358, PR China.
State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, PR China.
Environ Pollut. 2024 Nov 1;360:124634. doi: 10.1016/j.envpol.2024.124634. Epub 2024 Jul 29.
Microplastics (MPs) have the potential to adsorb heavy metals (HMs), resulting in a combined pollution threat in aquatic and terrestrial environments. However, due to the complexity of MP/HM properties and experimental conditions, research on the adsorption of HMs onto MPs often yields inconsistent findings. To address this issue, we conducted a comprehensive meta-analysis assisted with machine learning by analyzing a dataset comprising 3340 records from 134 references. The results indicated that polyamide (PA) (ES = -1.26) exhibited the highest adsorption capacity for commonly studied HMs (such as Pb, Cd, Cu, and Cr), which can be primarily attributed to the presence of C=O and N-H groups. In contrast, polyvinyl chloride (PVC) demonstrated a lower adsorption capacity, but the strongest adsorption strength resulting from the halogen atom on its surface. In terms of HMs, metal cations were more readily adsorbed by MPs compared with metalloids and metal oxyanions, with Pb (ES = -0.78) exhibiting the most significant adsorption. As the pH and temperature increased, the adsorption of HMs initially increased and subsequently decreased. Using a random forest model, we accurately predicted the adsorption capacity of MPs based on MP/HM properties and experimental conditions. The main factors affecting HM adsorption onto MPs were HM and MP concentrations, specific surface area of MP, and pH. Additionally, surface complexation and electrostatic interaction were the predominant mechanisms in the adsorption of Pb and Cd, with surface functional groups being the primary factors affecting the mechanism of MPs. These findings provide a quantitative summary of the interactions between MPs and HMs, contributing to our understanding of the environmental behavior and ecological risks associated with their correlation.
微塑料（MPs）有可能吸附重金属（HMs），从而在水生和陆地环境中造成联合污染威胁。然而，由于 MPs/HM 性质和实验条件的复杂性，关于 HMs 吸附到 MPs 上的研究结果往往不一致。为了解决这个问题，我们通过分析包含 134 个参考文献的 3340 条记录的数据集，进行了全面的元分析，并借助机器学习。结果表明，聚酰胺（PA）（ES=-1.26）对常见研究的 HMs（如 Pb、Cd、Cu 和 Cr）具有最高的吸附能力，这主要归因于 C=O 和 N-H 基团的存在。相比之下，聚氯乙烯（PVC）表现出较低的吸附能力，但由于其表面的卤原子，其吸附强度最强。就 HMs 而言，金属阳离子比类金属和金属含氧阴离子更容易被 MPs 吸附，其中 Pb（ES=-0.78）的吸附最为显著。随着 pH 值和温度的升高，HMs 的吸附最初增加，随后减少。我们使用随机森林模型，根据 MPs/HM 性质和实验条件，准确预测了 MPs 的吸附能力。影响 HMs 吸附到 MPs 上的主要因素是 HM 和 MP 的浓度、MP 的比表面积和 pH 值。此外，表面络合和静电相互作用是 Pb 和 Cd 吸附的主要机制，表面官能团是影响 MPs 机制的主要因素。这些发现提供了 MPs 与 HMs 之间相互作用的定量总结，有助于我们理解它们之间相关性相关的环境行为和生态风险。
