Li Jia, Xu Zehua, Dai Liming, Cui Min, Chen Yajun, Song Yang, Wang Shengsen
College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, PR China.
State Key Laboratory of Soil & Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, PR China.
Environ Sci Technol. 2025 Sep 9;59(35):18948-18956. doi: 10.1021/acs.est.5c09806. Epub 2025 Aug 27.
The aging of microplastics (MPs) depends on their surrounding environment and has significant implications for their environmental behavior and ecological risks. However, there are limited data on the long-term aging of MPs in different natural environments. The natural aging characteristics of polyethylene MPs (PE-MPs) and polylactic acid MPs (PLA-MPs) exposed to air, soil surface, and subsurface conditions for 6 and 12 months, respectively, were evaluated. The results showed that PE-MPs and PLA-MPs exhibited distinct aging characteristics under identical conditions. Photolysis represents the primary aging mechanism for PE-MPs, and prolonged solar radiation significantly reduces their stability ( < 0.05). Notably, soil minerals (e.g., Illite and quartz) formed armor-like coatings encapsulating PE-MP surfaces through chemical interfacial interactions (C-Si-O, Si-O-C, and Al-O-C)─a novel mechanism enhancing PE stability in soils. However, the stable interfacial adhesion between soil minerals and PLA-MPs is minimal. Microbial degradation as the primary aging mechanism renders PLA-MPs in soil more susceptible to aging compared to those in air, consequently exhibiting lower stability. This study highlights the mineral-mediated aging of MPs in soil and demonstrates how mineral coatings enhance the stability of PE-MPs. This underscores the necessity of incorporating mineral-mediated aging processes into MP risk assessments for soil ecosystems.
微塑料（MPs）的老化取决于其周围环境，对其环境行为和生态风险具有重要影响。然而，关于微塑料在不同自然环境中长期老化的数据有限。分别评估了聚乙烯微塑料（PE-MPs）和聚乳酸微塑料（PLA-MPs）在空气、土壤表面和地下条件下暴露6个月和12个月后的自然老化特性。结果表明，在相同条件下，PE-MPs和PLA-MPs表现出不同的老化特性。光解是PE-MPs的主要老化机制，长时间的太阳辐射会显著降低其稳定性（<0.05）。值得注意的是，土壤矿物质（如伊利石和石英）通过化学界面相互作用（C-Si-O、Si-O-C和Al-O-C）在PE-MP表面形成类似铠甲的涂层，这是一种增强PE在土壤中稳定性的新机制。然而，土壤矿物质与PLA-MPs之间的稳定界面附着力极小。微生物降解作为主要老化机制，使土壤中的PLA-MPs比空气中的PLA-MPs更容易老化，因此稳定性较低。本研究强调了土壤中矿物质介导的微塑料老化，并展示了矿物涂层如何增强PE-MPs的稳定性。这突出了将矿物介导的老化过程纳入土壤生态系统微塑料风险评估的必要性。
