鄱阳湖-饶河入湖段湿地底泥中微塑料的分离及其表面形貌特征

微塑料(粒径5 mm)作为一种新型污染物近年来被社会广泛关注.本文以江西省饶河-鄱阳湖入湖段(龙口)典型湿地表层中底泥沉积物为研究对象,分离提取底泥沉积物中微塑料,确定底泥沉积物中微塑料丰度值,利用扫描电子显微镜-能谱仪(SEM-EDS)和傅里叶红外光谱仪分析微塑料表面形貌特征及组成特征.结果表明:(1)底泥沉积物中微塑料丰度为938个·kg-1,主要包括碎片、薄膜、纤维和发泡等4种类型微塑料,其中以碎片类微塑料比例最高,达到66.7%;薄膜类次之,约占比例25%;发泡类及纤维类微塑料相对较少些,二者比例之和仅占8.3%.(2)不同类型微塑料的红外光谱分析表明,碎片类微塑料主要成分为聚乙烯,薄膜类主要成分为聚丙烯,纤维类主要成分为低密度聚乙烯,发泡类主要成分则为聚苯乙烯.(3)微塑料粒径分布特征表明,粒径小于1 mm的微塑料比例占总量的61.3%,且随着粒径增大微塑料数目呈减少趋势.(4)微塑料表面形貌特征表现为沉积物中的微塑料有不同程度的老化痕迹,表面出现裂痕、孔隙并带有撕裂物等特征.

Separation and microscopic study of microplastics from the sediments of the wetland in the estuary of Raohe River of Poyang Lake

Microplastic particles with the particle size less than 5 mm are of increasing concern in recent years. In this study, the microplastics were sampled from the surface sediments of the estuary of Poyang Lake in Jiangxi Province. The microplastic particles were separated from the sediments using flotation separation methods, and the microplastic abundance were measured. Meanwhile, the surface topography features and composition characteristics were studied using scanning electron microscope equipped with an energy dispersive (SEM-EDS) and Fourier infrared spectrometer. The results showed that microplastic abundance value of the sediments was 938 cell·kg^-1. There are mainly four types of the microplastics in the sediments were identified, including fragments, thin films, fibers and foams. Of the particles analyzed, 66.7% were predominantly microplatic fragment and 25% were microplastic films, while the foam and fiber microplastics accounts for 8.3% of the particles. Fourier transform infrared spectroscopy analysis demonstrated that the major composition of fragments, films, fibers and foams were identified as polyethylene, polypropylene, low density polyethylene and polystyrene, respectively. The studies of the particle size of microplastics also indicated that the microplastics with particle size less than 1 mm accounts for 61.3% of the total particles, and the abundance of microplastics trend to decrease when particle size increased. The SEM-EDS studies showed that microplastics in the sediments presented signs of aging on the surface in different extent, including cracks, pores, and tear properties.