Spatio-vertical distribution of riverine microplastics: Impact of the textile industry

Microplastics (MPs) contamination in rivers and lakes is of paramount environmental importance as freshwater systems transport MPs from land to ocean. However, information regarding the spatio-vertical distributions of MPs in rivers, and their associations with surrounding industrial activities, is scarce and unclear. This study investigated MPs in the Taipu River, where there is a highly developed textile industry in Yangtze River Delta, China. Results showed a widespread occurrence of MPs particles with concentrations in the range of 0.65-6.07 items/L and 0.30-3.63 items/L in surface and bottom waters. A higher abundance of MPs was observed in surface waters than in bottom waters (t = 5.423, p = 0.024). The MPs distributions varied markedly in space, with the highest abundances being found in textile manufacturing zones as a consequence of industrial release (F = 14.642, p < 0.001). Transparent fibers were the major MPs compositions with 100-500 μm in size. Polyethylene terephthalate (PET) accounted for 71.4% and 59.73% of the total MPs identified in surface and bottom water, respectively. These PET polymers were predominantly presented in "fibrous" shapes, further reflecting the point sources of textile wastewater. Moreover, polyvinyl acetate (PVAC), used as fabric coating and resin matrix to form nonwoven fabrics, was firstly highlighted at a watershed scale. Although risk assessments revealed a light to moderate risks of MPs in the Taipu River, textile wastewater appears to cause a high "grey water" footprint and increase the risks of MPs pollution from textile life-cycle production. This study bridged gaps between field data and policy-making for MPs control and shed insight into the cleaner production of the textile industry.