Distribution of microplastics in surface water of the lower Yellow River near estuary

The composition and distribution of microplastics in surface water of the Yellow River lower reach near estuary were investigated in this work. The major shape types of microplastics can be classified to fibers, fragments and particles, and 93.12% of microplastics in the surface water were fibers. The microplastics <200 μm were most abundant at all sample sites, which accounted for 87.94% of microplastics. The composition of microplastics was identified as polyethylene, polypropylene, and polystyrene according to infrared spectrometer analysis. The amounts of primary microplastics accounted for approximately three-fourths according to scanning electron microscope and microscope photo observing. The microplastics at different weathering processes could be also observed. The average abundances of microplastics in the dry and wet seasons were 930 and 497 item/L, respectively. The abundances of microplastics in the dry season all higher than that in the wet season. The microplastic concentrations in the surface water decreased linearly with the distances from the estuary of Yellow River with rather high positive correlation coefficients at wet season (r = 0.8104, p < .01) and at dry season (r = 0.8333, p < .01). The distribution of microplastics in the river section and the density of microplastics may be the primary factors to influence the microplastic concentrations in the surface water. The researches about distribution of microplastics in the river section might provide useful information that could be used for calculating either mass fluxes or inventories of microplastics.