金山湖沉积物微塑料形态与分布特征

Morphology and distribution characterization of microplastic in sediments of Jinshan Lake

微塑料作为一种新型污染物,对自然环境所造成的潜在风险已成为当前广泛关注的环境问题之一.湖泊沉积物作为淡水生态系统微塑料的“汇”,其分布特征受所在水域自然及人为等多重因素的影响.为探究江苏省镇江市金山湖表层沉积物微塑料的分布特征,在2019年1月(冬季)和7月(夏季)选取了10个点位采集沉积物样品,并使用金相显微镜观察微塑料样品特征并分类,使用拉曼光谱仪对微塑料聚合物类型进行鉴定,使用扫描电子显微镜分析微塑料表面特征.结果表明,金山湖冬季和夏季表层沉积物微塑料平均丰度分别为1368 n·kg^(−1)和1112 n·kg^(−1)干重沉积物,冬季和夏季纤维状微塑料占比分别为70.5%和57.3%为主,冬季沉积物微塑料颜色所占比例分别为透明(29.50%)、黑色(25.90%)、蓝色(24.10%)、白色(9.71%)、绿色(5.76%)和红色(5.04%),夏季沉积物微塑料各颜色所占比例为蓝色(22.81%)、黑色(21.05%)、绿色(18.13%)、透明(18.13%)、白色(14.33%)和红色(5.56%).微塑料以<1 mm的尺寸在冬季和夏季沉积物中占主导地位,其冬季占比71.22%,夏季占比64.62%.冬季和夏季沉积物中微塑料以聚对苯二甲酸乙二醇酯(polyethylene terephthalate,PET)和聚乙烯(polyethylene,PE)为主要的聚合物类型,冬季PET占比为29.86%、PE占比为21.94%,夏季PET占比为33.04%、PE占比为22.81%.在冬季和夏季沉积物微塑料表面均存在粗糙、撕裂、多孔等情况.

Microplastics(MPs),as a new type of environmental pollutant,has received widespread attention owing to their potential risks to the natural environment.Sediments are the"sinks"for MPs in freshwater lake ecosystems and the distribution characteristics of MPs were affected by multiple factors of natural and human.In this paper,total 10 sampling sites from the Jinshan lake of Zhenjiang city were selected and surface sediments were sampled both January(winter)and July(summer)of 2019,respectively.In addition,MPs in sediment samples were classified using metallographic microscopy,and their microplastic polymer and surface characteristics were identified and analyzed using Raman spectroscopy and scanning electron microscopy,respectively,in order to determine the morphology and distribution characterization of MPs in sediments of Jinshan Lake.Results showed that the average abundance of microplastics was 1368 n·kg^(−1)in the winter and 1112 n·kg^(−1)in the summer.Fibrous microplastics were the predominant MPs,which accounted for the higher proportion of 70.5%and 57.3%in winter and summer,respectively.In addition,the colors of microplastics in winter sediments were transparent(29.50%),black(25.90%),blue(24.10%),white(9.71%),green(5.76%)and red(5.04%),respectively.The proportion of microplastics colors in summer sediments were blue(22.81%),black(21.05%),green(18.13%),transparent(18.13%),white(14.33%)and red(5.56%).Small-sized particles(<1 mm)were the predominant size,with the percentage of 71.22%and 64.62%in winter and summer respectively.Polyethylene terephthalate(PET)and polyethylene(PE)were the two main polymer types in this study.PET and PE accounted for 29.86%and 21.94%in winter,whereas,PET accounted for 33.04%and PE accounted for 22.81%in summer.The surface of microplastics in both seasons was rough,torn and porous.