Microplastics (MPs), defined as plastic particles smaller than 5 mm, have emerged as a significant environmental concern due to their persistence and widespread distribution across terrestrial and aquatic ecosystems. Their sources are predominantly anthropogenic, including landfill waste, agricultural plastic films, biosolids from wastewater treatment plants (WWTPs), and direct discharge from industrial and domestic effluents. Once released into the environment, MPs undergo complex weathering processes—mechanical fragmentation, photo-degradation, thermal-degradation, and biodegradation—that alter their physical and chemical properties. These transformations influence their transport, fate, and interactions with coexisting environmental constituents.
The weathering of MPs is driven by both abiotic and biotic factors. In aquatic environments, UV radiation plays a dominant role in initiating photo-oxidation, breaking polymer chains through radical-based reactions. The energy from UV light (290–400 nm) is sufficient to cleave C–C and C–H bonds, leading to chain scission and the formation of oxygen-containing functional groups such as carbonyl (C=O) and hydroxyl (–OH).IL-8 Antibody custom synthesis This process increases surface roughness and specific surface area, promoting further degradation. In contrast, terrestrial environments experience higher temperatures and greater mechanical stress from wind, soil movement, and human activity, accelerating mechanical fragmentation and thermal degradation. However, water’s superior heat dissipation capacity results in lower ambient temperatures compared to dry land, slowing thermal weathering in aquatic systems.
A key outcome of weathering is the increased surface reactivity of MPs. As they degrade, MPs develop more polar functional groups, enhancing their hydrophilicity and ability to adsorb pollutants such as heavy metals and organic contaminants. For example, UV-aged polyethylene terephthalate (PET) MPs show a 1.6-fold increase in Zn²⁺ adsorption capacity due to enhanced surface charge and active sites. Similarly, aged polystyrene (PS) MPs exhibit stronger electrostatic attraction for metal ions and improved hydrogen bonding with hydrophilic organic compounds like tetracycline. Conversely, hydrophobic interactions weaken, reducing the sorption of nonpolar pollutants such as BDE-47, a brominated flame retardant.CD223/LAG-3 Antibody manufacturer
Weathering also alters aggregation behavior.PMID:35233930 Increased surface charge and hydrophilicity inhibit homo-aggregation in saline or neutral conditions due to enhanced electrostatic repulsion. However, in calcium-rich environments, oxygenated groups on MPs can bridge with Ca²⁺ ions, promoting aggregation. Biofilm formation further modulates this behavior: while biofilms can enhance aggregation via sticky extracellular polymeric substances (EPS), they may also shield MPs from UV and shear forces, slowing degradation.
Despite extensive laboratory studies, most research remains under controlled conditions that do not fully replicate natural complexity. Field-based investigations are scarce, especially in soils and sediments where multiple weathering pathways occur simultaneously. Moreover, existing studies often focus on single MP types (e.g., PE, PS), neglecting real-world mixtures with varying shapes, sizes, and chemical structures. Irregularly shaped or functionalized MPs—such as carboxyl-modified PS or biodegradable polymers—are increasingly present but poorly understood in terms of degradation kinetics.
Future research must prioritize in-situ studies under realistic environmental conditions, incorporating dynamic variables such as fluctuating temperature, salinity, dissolved organic matter, microbial communities, and ion composition. Understanding how these factors interact during long-term weathering will improve predictive models for MP fate. Additionally, the role of biofilms in mediating pollutant transport and the potential for reabsorption of leached additives onto weathered surfaces remain critical knowledge gaps.
In conclusion, weathering transforms microplastics into more reactive, mobile, and environmentally impactful forms. While it may reduce particle size and eventually lead to mineralization, it simultaneously enhances their capacity to carry toxic substances and alter ecosystem dynamics. Comprehensive, multidisciplinary approaches are essential to unravel the full implications of MP aging and inform effective mitigation strategies.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com