Simulated marine weathering of PVC: Surface transformations and microbial interactions

Polyvinyl chloride (PVC), well known for its high durability, is widely detected in marine environments. However, its weathering processes under oceanic conditions are not yet fully understood, which limits accurate predictions of its environmental persistence and impacts. Here, we investigated PVC degradation under simulated marine conditions by applying three environmental stressors-mechanical wave action (W), light exposure (L), and microbial activity (M)-individually and in combination. Over a 155-day period, chemical, physical, and biological transformations were characterized via FT-IR, XPS, contact angle, opacity, microscopy, and qPCR analyses. Wave-induced agitation was the dominant single factor promoting oxidative PVC alterations, including chlorine loss, surface hydrophilization, and reduced optical clarity. In contrast, light exposure alone had minimal impact, while microbial activity introduced distinctive nitrogen- and carbon-rich functionalities. Under combined stressors, the W + L + M condition elicited the most pronounced overall changes, with synergistic interactions driving surface oxidation and biofilm development, and spectral features (π-π* shake-up and amide linkages) suggesting biologically mediated transformations in addition to abiotic processes. This multifactorial experimental design offers a practical approach for examining polymer degradation under diverse environmental conditions. It also emphasizes the need for extended timescales and molecular-level analyses to enhance predictions of plastic persistence, fragmentation, and ecological risks in marine environments.