Leaching and Fluorescence Characteristics of Dissolved Organic Matter Released from Common Consumer Plastics

Abstract

Plastic pollution poses increasing risks to wildlife, human health, and aquatic ecosystems, acting as a source and vector of dissolved compounds. This study investigated the leaching and fluorescence characteristics of dissolved organic matter (DOM) from three common consumer plastics: polypropylene (PP), low-density polyethylene (LDPE), and polyethylene terephthalate (PET). Plastics were incubated under simulated light or dark conditions for 21 days, and dissolved organic carbon (DOC) and fluorescent DOM (FDOM) were measured to quantify leaching amounts and characterize DOM quality. Our results showed that PP released the highest DOC concentrations, while LDPE and PET showed much lower levels. By day 21, average DOC leaching from PP, LDPE, and PET was 10.50, 1.62 and 0.53 mg C·m^-2 of plastic surface, respectively. Corresponding leaching rates were 4.02, 0.56 and <0.10 mg C·m^-2·d^-1. In contrast to differences in DOC quantity, the FDOM of all plastics exhibited similar spectral features, with a major tryptophan-like peak at 295–305 nm excitation and 335–340 nm emission, and a minor peak at 235–254 nm excitation and 335–340 nm emission. These fluorescence signals suggest that plastic-derived DOM is bio-labile and potentially influenced by additives. Overall, the results confirm that common consumer plastics are a reactive source of DOM that may alter carbon cycling and microbial processes in aquatic environments. We suggest that both plastic type and additives likely affect DOM leaching behavior, with implications for understanding the broader ecological impacts of plastic pollution.