鄱阳湖五河流域入湖口沉积物中微塑料的赋存特征

Occurrence of microplastics in the sediments of the five rivers estuaries in Poyang Lake Basin

微塑料是指直径小于5mm的塑料颗粒,因其性质稳定,在环境中易大量积累,已成为新型环境污染物.本研究在鄱阳湖流域重点区域设置6个样点,于3月、7月、12月等3个不同水期采集底泥沉积物样品,利用连续流动分离浮选装置分离得到微塑料,借助金相显微镜进行鉴定,按照形态特征划分微塑料类型,分析微塑料的赋存特征.结果表明,依据不同样点微塑料的形态特征可将鄱阳湖流域的微塑料主要类型划分为碎片、薄膜、纤维和发泡类等4种类型,且4种不同类型的微塑料在各样点中均有分布,但不同类型微塑料的丰度存在差异,以碎片类微塑料占主体.鄱阳湖流域的微塑料丰度值在不同时段存在显著差异,枯水期微塑料的平均丰度值最高,达1105.0ng·kg^-1;平水期的平均丰度值为729.5ng·kg^-1;而丰水期的平均丰度值为599.0ng·kg^-1.鄱阳湖流域不同区域微塑料的丰度值也存在显著差异,以赣江中支微塑料的平均丰度值最高,达到1455ng·kg^-1;以南矶山自然保护区内的微塑料丰度最低,仅54.6ng·kg^-1.

Microplastics refer to plastic particles less than 5 mm in diameter.They are stable and can accumulate into large amount in the environment,and thus have become a new class of environmental pollutants.In this study,six sampling sites were set up in the key areas of Poyang Lake Basin,and sediment samples were taken in March,July,and December of the same year.The microplastics were separated from the samples by a continuous flow separation flotation device,and then examined with a metallographic microscope.The microplastics in the basin of Poyang Lake were classified according to their morphological characteristics,and the occurrence characteristics of microplastics were analyzed.The results showed that all the microplastics in the basin of Poyang Lake could be divided into four different types according to the morphological classification,including fragments,films,fibers,and foams.The above four different microplastics were found in all the sampling sites,but the amounts of different microplastics in different sampling sites were different,and fragments were the most abundant microplastics.The distribution characteristic of different microplastics in the sediments of Poyang Lake Basin were different significantly.The abundance of microplastics was the highest in the dry season,the average abundance value was 1105.0 ng·kg^-1,the abundance of microplastics was 729.5 ng·kg^-1 in the normal season,and the abundance of microplastics was the least in the wet season,the average abundance value was 599.0 ng·kg^-1.The abundances of microplastics in different regions of the Poyang Lake Basin were also significantly different.The abundance of microplastics was the highest in the sampling sites at the middle branch of Ganjiang River,where the average abundance value was 1455 ng·kg^-1.The abundance of microplastics was the lowest in the sampling sites at Nanjishan Nature Reserve,where the average abundance value was 54.6 ng·kg^-1.