Study Of The Plastisphere On Carrier Effect Of Different Plastic Wastes In The Context Of COVID-19

In 2022,while life returned to normal worldwide,the number of masks sold still remained steadily high.Wet wipes were also becoming more accepted and used by consumers as a result of the epidemic.In the post-epidemic era,PP masks and PET wipes had become a significant source of plastic waste due to the continuation of lifestyle habits.Compared to the common plastic wastes that had been the focus of previous studies,such as beverage bottles（PET）and fast food containers（PP）,the emerging plastics in the context of the epidemic may have the same material but a different structure（webbing）than the plastic wastes of traditional concern,and they were more likely to age and break down to form microplastics,thus threatening ecological safety.This paper focused on plastic products（PP masks and takeaway containers,PET non-woven wipes and plastic bottles）and cotton wipes that provided a natural source of organic carbon,and explored the role of the chemical composition and physical structure of these materials in the regulation of microbial and resistance genes in the"plastisphere"ecological niche formed by these materials as unique substrates.The role played by these materials in the regulation of microbial and resistance genes when used as unique substrates in the’plastisphere’ecotone.The analysis was further explored to see how"plastisphere"affects its sorption behaviour.（1）The influence and change of biofilm attachment on the surface characteristics of each plastic sample were analyzed by a series of characterization methods,and the detailed information of the components of extracellular polymeric substances（EPS）of the biofilm was obtained.The results showed that the surface biomass of masks after long film increased significantly,and the biomass in the late long film period could be more than 10 times higher than that in the early stage.It is worth noting that there was a"post-start"phenomenon in mesolayer colonization.There was a significant difference in biomass between the mesh and the smooth surface sample,the former being 3.68 times that of the latter.With the increase of the number of incubation days,the three-dimensional fluorescence spectrum showed that the proportion of humic acid fluorescent components in various samples gradually increased and remained stable.Infrared characterization results showed that new oxygen-containing hydrophilic functional groups were created on the surface of various plastics during biofilm culture,making them more susceptible to adsorption of contaminants.（2）The results of the analysis of the microbial community and antibiotic resistance genes（ARGs）using 16S r RNA gene sequencing and high-throughput quantitative PCR techniques showed that although the composition of the bacterial community on the surface of the plastic showed dynamic changes over time,there were still significant differences with the composition of the environmental water body.It was noteworthy that the physical structure of the plastic had a more significant effect on the microorganisms than the chemical composition.Plastic samples with the same chemical structure of the web were richer in microbial species diversity than those with a smooth surface.For ARGs,the situation of ARGs in plastic samples was significantly different from the aqueous environment,i.e.,plastics were able to selectively adsorb ARGs from the environment,and this function was related to the plastic material.Aminoglycosides were the dominant ARGs in all plastisphere samples at different stages of incubation,and the relative abundance of ARGs varied significantly between plastisphere samples.There was also potential consistency in the composition of microbial species abundance and the composition of antibiotic resistance gene abundance across the plastisphere samples.（3）Batch adsorption experiments were conducted to compare the adsorption processes of heavy metals Cd²⁺and Cu²⁺on virgin plastic debris and plastisphere samples to investigate the adsorption behaviour and mechanistic studies of heavy metals on each plastic sample at different incubation durations.The results showed that biofilms increased the adsorption of heavy metals on plastics.The adsorption was significantly promoted by long films compared to the original samples.The equilibrium adsorption of Cd²⁺and Cu²⁺on the samples showed an overall dynamic trend with the change of incubation time.The adsorption process was well described by the Freundlich model,which showed that the original plastic fragments and the plastisphere samples were multilayered and heterogeneously adsorbed for the heavy metals.The sorption kinetics of both heavy metals on the plastisphere samples were significantly influenced by the biofilm,with chemisorption being the dominant influence mechanism for each plastisphere sample.In addition,complexation of functional groups within the biofilm may contribute to the increase in heavy metal sorption,which involved the involvement of oxygen-containing functional groups.Overall,these results suggested that biofilms enhanced the potential role of plastic fragments as carriers of heavy metals in freshwater.