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Updated: May 23, 2025
14:10
Separation and Identification of Conventional Microplastics from Farmland Soils
Published on: March 21, 2025
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Insight into the interactions between microplastics and heavy metals in agricultural soil solution: adsorption
Yu-Liang Liao1,2, Chun-Dan Gan1,3, Xue Zhao4
1College of Architecture and Environment, Sichuan University, Chengdu 610065, China. yanyang@scu.edu.cn.
Environmental Science. Processes & Impacts
|May 22, 2025
Summary
Environmental-simulating microplastics (EMPs) and aged commercial microplastics (MPs) show enhanced heavy metal (HM) adsorption. Aged MPs, especially polylactic acid (PLA), exhibit higher capacities, impacting soil HM concentrations.
Area of Science:
- Environmental Science
- Environmental Chemistry
- Soil Science
Background:
- Microplastics (MPs) are ubiquitous soil contaminants, frequently co-occurring with heavy metals (HMs).
- Assessing the combined impact of MPs and HMs on soil ecosystems is complex due to their interactions.
- Understanding MP-HM adsorption-desorption dynamics is crucial for evaluating soil contamination risks.
Purpose of the Study:
- To compare the cadmium (Cd) and chromium (Cr) adsorption-desorption properties of environmental-simulating microplastics (EMPs) with commercial MPs.
- To investigate the influence of aging treatments on MP surface characteristics and HM adsorption.
- To evaluate the potential of MPs to accumulate and immobilize soil HMs.
Main Methods:
- Preparation of EMPs simulating environmental conditions.
- Aging treatments applied to commercial MPs to alter surface properties.
- Adsorption-desorption experiments conducted in artificial soil solutions for Cd and Cr.
- Analysis of adsorption kinetics and HM accumulation factors.
Main Results:
- Aging increased oxygen-containing functional groups and reduced particle size on MPs, enhancing HM adsorption.
- EMPs exhibited higher Cd and Cr adsorption capacities than single-type commercial MPs.
- Degradable polylactic acid (PLA) showed the highest maximum adsorption capacities for Cd and Cr among commercial MPs.
- Chemisorption and intraparticle diffusion were identified as key rate-limiting steps in MP-HM adsorption.
- Cd desorption was more pronounced than Cr desorption, indicating higher Cd activity on MP surfaces.
- Aged MPs demonstrated higher HM accumulation factors, suggesting potential for soil HM immobilization.
Conclusions:
- Environmental-simulating microplastics and aged commercial MPs significantly enhance heavy metal adsorption.
- The characteristics of MPs, including aging and type (e.g., PLA), influence their capacity for HM adsorption and potential for transport.
- Mixed MPs, particularly aged ones, may have a greater impact on soil total and bioavailable heavy metal concentrations than single-type MPs.
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