There are sparse reports on the distribution of microplastics in the ice sheets of freshwater lakes. In this study, the abundance, color, shape, and species of microplastics in the ice sheet of Lake Wuliangsuhai were characterized using field sampling and microscope observations. Fourier-transform infrared spectroscopy (FTIR) and correlation analysis were used to examine the distribution of microplastics contained in the lake and its relationships with salinity and chlorophyll a. The results show that the average abundance of microplastics in the Lake Wuliangsuhai ice sheet is 56.75-141 n·L-1, which is approximately 10-100 times higher than in the surface water of the Lake Wuliangsuhai. Fibers were the most common type of microplastics followed by fragments. Overall abundance showed a decreasing trend in the downstream horizontal direction and was positively correlated with salinity in the vertical direction. The abundance of microplastic in the surface ice and bottom ice was greater than in the middle of the ice and near bottom of the ice. There was no correlation between the abundance of microplastic and the concentration of chlorophyll a. In addition, due to the capturing effect of the ice, microplastic particles are temporarily stored in the ice sheet in winter, which are released into water in spring. This study provides baseline information to inform microplastic pollution control measures in Lake Wuliangsuhai.
Keywords: Lake Wuliangsuhai; correlation analysis; distribution characteristics; frozen period; microplastics.