Total Organic Carbon as a Quantitative Index of Micro- and Nano-Plastic Pollution

The global pollution of micro- and nano-plastics (MNPs) calls for monitoring methods. As diverse mixtures of various sizes, morphologies, and chemical compositions in the environment, MNPs are currently quantified based on mass or number concentrations. Here, we show total organic carbon (TOC) as an index for quantifying the pollution of total MNPs in environmental waters. Two parallel water samples are respectively filtered with a carbon-free glass fiber membrane. Then, one membrane with the collected particulate substances is treated by potassium peroxodisulfate oxidation and Fenton digestion in sequence for quantifying the sum of MNPs and particulate black carbon (PBC) as TOC_MNP&PBC using a TOC analyzer, another membrane is treated by sulfonation and Fenton digestion for quantifying PBC as TOC_PBC, and the TOC of MNPs is calculated by subtracting TOC_PBC from TOC_MNP&PBC. The feasibility of our method is demonstrated by determination of various MNPs of representative plastic types and sizes (0.5-100 μm) in tap, river, and sea water samples, with low detection limits (∼7 μg C L^-1) and high spiked recoveries (83.7-114%). TOC is a powerful index for routine monitoring of MNP pollution.