Plastic leachates lead to long-term toxicity in fungi and promote biodegradation of heterocyclic dye.

The hazardous effects of plastic and plastic leachates on organisms, even bacteria, have attracted widespread attention, but only a limited effort has been devoted to explore the response of fungi to plastic leachate induced by light irradiation. Here, we performed plastic leaching experiments to obtain leachates from polyethylene (PE), polyethylene terephthalate (PET) and polypropylene (PP), and optical properties of plastic leachates were analysed to determine the influence of light conditions and plastic materials on that. The effects of plastic leachates on the production of fungal enzyme and the biodegradation of heterocyclic dye by fungi were evaluated. Results indicated that the UV light greatly enhanced the release of leachates from the three plastics. Both plastic polymers and light irradiation affected the plastic-derived dissolved organic carbon (DOC) and their aromaticity, but the molecular weight of plastic leachates showed no dependency on light irradiation types, and PE was the easiest to photo age and leached more DOC. Plastic leachates had no dose-effect on the production of extracellular enzymes by fungi. PE leachates showed long-term toxicities to fungi, and no manganese peroxidase activities were detected after a 42-day incubation, while that of controls were up to 73.64 ± 8.81 U/L. However, the PE and PP leachates greatly promoted methylene blue degradation by the fungi, but PET leachates relieved the decolouration of methylene blue, probably because of the benzene ring structure in the PET monomer. Fusarium oxysporum had a stronger degradation ability than Phanerochaete chrysosporium. Our results indicate that plastic leachates can influence the production and secretion of fungi ligninolytic extracellular enzymes, and regulate the fungal degradation of heterocyclic dye.

Characteristics and source-pathway of microplastics in freshwater system of China: A review.

China plays a key role in global plastic production, consumption and disposal, which arouses growing concern about microplastics (MPs) contamination in Chinese freshwater systems. However, few reviews have discussed the characteristics of MP pollution in whole freshwater systems at a national scale. In this review, we summarized the characteristics, sources and transport pathways of MPs in Chinese freshwater systems including surface water and sediment. Results showed that current research mainly focused on the middle and lower reaches of the Yangtze River and its tributaries, as well as lakes and reservoirs along the Yangtze River. Large-scale reservoirs, rivers and lakes located in densely populated areas usually showed higher abundances of MPs. The majority of MPs in Chinese surface water and sediment mainly consisted of polyethylene and polypropylene, and the most common morphologies were fibers and fragments. To identify the sources and pathways, we introduced the source-sink-pathway model, and found that sewage system, farmland and aquaculture area were the three most prevalent sinks in freshwater systems in China. The source-sink-pathway model will help to further identify the migration of MPs from sources to freshwater systems.