Microplastic degradations in simulated UV light, natural light and natural water body: A comparison investigation

Microplastics (MPs) degradation due to light radiation, weathering, water erosion and biodegradation might change MPs physical and chemical characteristics and thereby change MPs behaviors in natural environments. This study conducted a comparison investigation on polyvinyl chloride (PVC), polyethylene (PE) and polyamide (PA) degradation in three different environmental conditions, namely simulated UV light, natural light and natural water body. The results showed that degradation of MPs in natural environments is more complex than the case in a controlled experimental condition (such as simulated UV light). In the conditions of natural light and natural water body, MPs are more easily covered by sediments/microorganisms. Particularly in the natural water body, biofilm development is an important factor for MPs degradation and this is dependent on where MPs are located. PVC in the water surface adsorbed more prokaryotes and eukaryotes than those in the water bottom while PE and PA showed the opposite. The research outcomes also show that a complex interaction between MPs and heavy metals in different environments. In simulated UV light, heavy metals tended to leach from MPs while in the natural light and natural water body, heavy metal concentrations of MPs had a higher variability caused by continuous leaching-adsorption behaviors. Those outcomes were expected to contribute to an in-depth understanding of MP degradations and their environmental behaviors.