The release, degradation, and distribution of PVC microplastic-originated phthalate and non-phthalate plasticizers in sediments

This study investigated the leaching of phthalate and non-phthalate plasticizers from polyvinyl chloride microplastics (MPs) into sediment and their degradation over a 30-d period via abiotic and biotic processes. The results showed that 3579% of plasticizers were released into the sediment from the MPs and >99.9% degradation was achieved. Although a significantly higher degradation was found in plasticizer-added microcosms under biotic processes (overall, 94%), there was a noticeable abiotic loss (72%), suggesting that abiotic processes also play a role in plasticizer degradation. Interestingly, when compared with the initial sediment-water partitioning for plasticizers, the partition constants for low-molecular-weight compounds decreased in both microcosms, whereas those for high-molecular-weight compounds increased after abiotic degradation. Furthermore, changes in the bacterial community, abundance of plasticizer-degrading bacterial populations, and functional gene profiles were assessed. In all the microcosms, a decrease in bacterial community diversity and a notable shift in bacterial composition were observed. The enriched potential plasticizer-degrading bacteria were Arthrobacter, Bacillus, Desulfovibrio, Desulfuromonas, Devosia, Gordonia, Mycobacterium, and Sphingomonas, among which Bacillus was recognized as the key plasticizer degrader. Overall, these findings shed light on the factors affecting plasticizer degradation, the microbial communities potentially involved in biodegradation, and the fate of plasticizers in the environment. The study emphasizes leaching of plasticizers from commercial polyvinyl chloride into the sediment and subsequent degradation under abiotic and biotic processes, with microbial communities playing a crucial role. Understanding this is important for evaluating the environmental impact of plastic pollution. While certain bacteria are key in degradation of plasticizers, abiotic processes also play a significant part. This suggests that naturally occurring microbes are capable of mitigate the plasticizers from the environment. Changes in microbial communities and the fate of plasticizers in sediment offer important insights into the lasting environmental effects of microplastic contamination.