城市湖泊沉积物微塑料污染特征

近年来,出现在环境中的微塑料日益受到重视.本文选择马鞍山市雨山湖和南湖等典型城市湖泊,研究春夏两季沉积物中微塑料的物理形貌特征和时空分布特征,并探究湖泊中微塑料的来源.结果表明,春季沉积物中微塑料平均含量为(0.028 4±0.059 7)g·kg~(-1),平均丰度为(278.9±529.1)n·kg~(-1);夏季微塑料平均含量(0.031 7±0.077 8)g·kg~(-1),平均丰度为(277.1±395.6)n·kg~(-1),利用配对样品T检验法发现春夏两季沉积物中微塑料的含量(N=22,t=-0.269,P=0.791)与丰度(N=22,t=0.035,P=0.973)无明显相关差异性.根据形状将研究区域沉积物中的微塑料分为纤维、薄膜和颗粒这3种类型,相应占比分别为52.9%、 28.9%和18.2%.粒径统计结果表明,绝大部分微塑料的粒径小于1 mm,可占总数量的83.9%,微塑料主要为聚乙烯和聚丙烯且表面严重风化.人流量大、车流量大和水上活动多的区域污染较为严重,揭示了湖泊沉积物微塑料的空间分布与人类活动的密切相关性.大气沉降(纤维类)、地表径流、衣服洗涤(纤维类)、湖内大塑料降解和渔业活动(渔网、发泡类)等为湖泊沉积物中微塑料的主要来源.

Characterization of Microplastic Pollution of Sediments from Urban Lakes

In recent years, microplastics (MPs) in the environment has become a topic of increasing concern. In this study, typical urban lakes, such as Yushan Lake and Nanhu Lake in Maanshan City, were selected to study the physical morphology and spatial distribution characteristics of MPs in sediments in spring and summer and to explore the sources of MPs in the lakes. On average, MPs in sediments occurred with a content of (0.0284±0.0597) g·kg^-1 and abundance of (278.9±529.1) n·kg^-1 in spring, and (0.0317±0.0778) g·kg^-1 and (277.1±395.6) n·kg^-1 in summer, respectively. Using a paired sample T-test, it was found that there was no significant correlation difference between the content (N=22, t=-0.269, P=0.791) and the abundance (N=22, t=0.035, P=0.973) of MPs in the spring and summer sediments. Regarding shape, the MPs in the sediments in the study area were divided into three types:fiber, film, and particle, accounting for 52.9%, 28.9%, and 18.2%, respectively. Size-fraction analysis indicated MPs<1 mm made up the majority, accounting for 83.9% of the total number. It was found that the MPs were mainly polyethylene (PE) and polypropylene (PP) polymers with seriously weathered surfaces. The sediments, which were adjacent either to land with a large stream of people and vehicles or to areas with frequent watersports, had notably high abundance of MPs, revealing the close correlation between the spatial distribution of MPs in lake sediments and human activities. It is thought that atmospheric precipitation (fiber), stormwater, washing of clothes (fiber), degradation of large plastics in the lake, and fishing activities (fishing nets, foam) are the main sources of MPs in lake sediments.