Tracing Footprint and Risk of Microplastics and Microfibers in the Lakes across China

Tracing footprint and risk of microplastics and microfibers is crucial to managing plastic and fiber waste. We identified microfibers from microplastics, quantitatively apportioned the sources of microplastics and microplastics in 102 lakes across China by field work, and developed a novel index (IMRI) to assess the risk based on human footprint and the abundance, size, shape, color, and residual monomers and chemical additives. The abundance in the sediments of these lakes ranged from 0.3 to 66.7 items g^-1. Microfibers and fiber-shaped microplastics accounted for 45% and 32% of the abundance. The risk levels assessed by IMRI indicated that microplastics and microfibers in the sediments of 33.3%, 28.4%, 27.5%, and 9.8% of the lakes had moderate, extremely high, high, and low risk, respectively, which was more consistent with the real situation of Chinese lakes compared with PLI, PHI, and RI and independent of background abundance. Secondary and tertiary industry-related activities and aquaculture activities contributed 64% and 36% to the abundance, posing extremely high risk and high risk, respectively. Artificial cellulosic microfibers mainly derived from aquaculture activities contributed 61% to the risk due to the residual toxic chemical additives. Residual monomers and chemical additives and size contributed 42.7% and 42.3% to the risk.