摘要
微塑料污染已成为全球高度关注的海陆环境问题.微塑料的大气污染研究在国际上鲜见报道,在中国尚属空白.本文基于大气沉降样品的收集和分析,报道了中国滨海城市大气环境中微塑料的类型、沉降通量及季节性变化的研究成果.分离和鉴定结果表明,采样点大气环境中微塑料有4种形貌类型,即纤维类、碎片类、薄膜类和发泡类,绝大部分为纤维类,占95%;这些微塑料的主要成分为聚酯(纤维类)、聚氯乙烯(纤维类和薄膜类)、聚乙烯(碎片类)和聚苯乙烯(发泡类).在粒径上,春、夏、秋、冬四季均以小于0.5 mm的颗粒为主,占50%以上.大气微塑料沉降通量可达1.46×10~5个/(m^2 a),其中纤维类达1.38×10~5个/(m^2 a);不同类型微塑料的沉降通量变幅在0~6.02×10~2个/(m^2 d),以纤维类的最高.微塑料沉降通量存在季节性差异,春、夏、冬季较高,秋季最低.本研究认为滨海城市大气环境中微塑料可能会通过沉降进入陆海环境,成为海洋和海岸环境中微塑料的重要来源,未来需要加强大气环境微塑料污染特征、沉降规律及生态效应的系统研究.
Pollution by microplastics has become a major global issue affecting the marine environment. However, there has been little research on microplastics in the atmosphere. Here, we study microplastics in precipitation samples collected in Yantai, a coastal city in Shandong Province, East China. This paper is the first report on the different shapes, deposition fluxes and seasonal variation in microplastics in the coastal urban atmospheric environment. The samples collected were pre-filtered using a set of stainless steel sieves with mesh sizes of 5 and 1 mm. Residues, such as insects and plant debris retained on a stainless steel sieve of mesh size 5 mm were discarded or archived. Residues retained on a stainless steel sieve of mesh size 1 mm were air-dried and placed under a stereomicroscope to select and count putative microplastics with different morphologies and different size fractions of 1-2, 2-3 and 3-5 mm. Samples that had passed through a mesh size of 1 mm were filtered again using a 5-μm pore size nitrocellulose filter for further microscopic observation and the selection and enumeration of smaller microplastics. Some of these samples containing organisms were digested with hydrogen peroxide （30%） to avoid interference during the observation and selection of the microplastics. Putative microplastics were identified using Fourier transform infrared spectroscopy. Four shape types of microplastics, namely fibers, fragments, films and foams were found in the atmospheric samples. The majority were fibers of different colors （white, black, red and transparent） that accounted for about 95% of the microplastics. Fragments accounted for about 4% and films and foams accounted for fewer than 1%. The main polymers were polyethylene terephthalate in the case of most of the fibers, polyvinyl chloride in the case of some fibers and films, polyethylene for the fragments, and polystyrene for the foams. Microplastics with sizes below 0.5 mm accounted for more than 50% throughout the year, followed by the size ranges 0.5-1 mm, 1-2 mm and then 2-3 mm. Microplastics with size range of 3-5 mm appeared only in the spring samples at low abundance. In general, the amount of microplastics decreased dramatically with increasing particle size. The 100-300 μm size fraction formed the highest proportion of microplastics below 0.5 mm in size, accounting for about 62%, and those below 50 μm showed the lowest abundance. The annual site deposition flux of atmospheric microplastics attained a maximum of 1.46×105 n/（m2 a）, that of the fibers up to 1.38×105 n/（m2 a）, and those of the fragments, films and foams up to 6.29×103, 7.65×102 and 2.45×102 n/（m2 a）, respectively. Deposition fluxes of different shape types ranged from 0.0 to 6.02×102 n/（m2 d）, and the fibers were also the commonest of the four shape types. The deposition flux of microplastics showed some seasonal variation, being higher in the spring, summer and winter and lowest in the autumn. Based on the observation site （1.6 km from the coast- line）, the length of Yantai urban coastline （100 km） and the annual deposition flux in this study, it was estimated that the total number of microplastics deposited in the urban area was about 2.33×1013 particles, equivalent to about 0.9 to 1.4 tonnes. We suggest that atmospheric microplastics, through precipitation to land and sea, be a key source of microplastics in the coastal and oceanic environments. Moreover, a systematic study is urgently required in the future for a better understanding of pollution and precipitation of atmospheric microplastics and their environmental impact.
出处
《科学通报》
EI
CAS
CSCD
北大核心
2017年第33期3902-3909,共8页
Chinese Science Bulletin
基金
中国科学院前沿科学重点研究项目(QYZDJ-SSW-DQC015)
科技部重点专项(2016YFC1402202)资助
关键词
微塑料
滨海城市
大气环境
形貌类型
沉降通量
季节性变化
microplastics, coastal city, atmospheric environment, shape types, deposition flux, seasonal variation
