Characteristics of microplastic pollution and temporal-spatial distribution in the sediments of the five rivers in the Lake Poyang Basin

Abstract

As an emerging environmental pollutant, microplastics are receiving increasing attention. In order to explore microplastics pollution in the Lake Poyang, we selected six typical sampling sites in the wetland beach of the five rivers of Lake Poyang Basin as the study area, and collected the sediments in the beach of each sampling sites as the materials and used the sampling profiling method to analyze and identify microplastics in the sediments during the three different hydrological periods of the normal season, wet season and dry season respectively. Flotation separation and metallographic microscopic identification technology are used to study the types, abundance, surface morphology and other characteristics of the microplastics in the sediments of the Lake Poyang wetland, reveal the spatial distribution and temporal dynamic characteristics of the microplastics in the sediments of different wetland beach in Lake Poyang during different water level periods. The results showed that the types of microplastics were debris, foams, films and fibers. Debris-based microplastics were most abundant accounting 51.95% of total microplastics. 70% of the microplastics have a particle size of less than 1 mm, and these tiny microplastics can be easily eaten by organisms and pose a threat to its survival. The average abundance of microplastics is 811.11 n/kg (n denotes the number of microplastics particles and kg denotes the dry weight of sediments), and the abundance value of the spatial distribution of microplastics for the six samples is expressed as in Zhugang > Wucheng > Dutou Village > Longkou > Ruihong Town > Nanji Mountain. The abundance values of microplastics of six samples are consistent with the dynamics of Lake Poyang water level. Highest proportion was found in dry season, reaching 44.41% of the total; lower proportion was found in normal season, reaching 31.52% of the total; and the lowest proportion was found in wet season, and accounting for only 24.07% of the total. The fact of the different pollution problem of microplastics in different sampling sites and different water periods suggests that people should pay attention to the discharge of plastic wastes and the management of the pollution in order to reduce the impact on lakes, rivers and other wetland ecological environment and ecosystems.