Vertical distribution of microplastics in the sediment profiles of the Lake Taihu, eastern China

Abstract

Microplastics are ubiquitous in the freshwater environment, while its abundance in the sediment profiles has received little attention. The vertical microplastic distribution in the sediment of the North (NTH) and Southwest (SWTH) of Lake Taihu was identified and characterized in this study. Microplastics could be detected at all depths (0–50 cm) at the two sites, with the total abundance of 8100 and 5300 particles kg−1 dry weight sediment at NTH and SWTH, respectively. This indicates that the microplastic storage in the sediment of the Lake Taihu may be underestimated, if only the surface sediment is considered. Microplastics composed of various polymer types were identified in the sediment of the two sites, including polyamide (PA), acrylic acid, polyethylene terephthalate and cellulose acetate, while high density polyethylene and polypropylene were only detected at NTH. The main type of polymers detected at NTH (42%) and SWTH (43%) were PA. The major shape of microplastics was fibers, with a ratio of 76% and 78%, respectively at the site NTH and SWTH. The colors of microplastics were mainly white (accounted for 42 and 43% at NTH and SWTH, respectively), which may be caused by the long-term decomposition of dyestuff in the syngenesis of sediment and/or probably the degradation during sample treatments. The textile industry and fishery activities may provide the source. In summary, our findings in the Lake Taihu provide better understanding of the microplastic pollution and tackle microplastics challenges.