YIC-IR  > 中科院海岸带环境过程与生态修复重点实验室
Alternative TitleSeparation of microplastics from a coastal soil and their surface microscopic features
周倩; 章海波; 周阳; 李远; 薛勇; 付传城; 涂晨; 骆永明; 章海波,骆永明 E-mail: hbzhang@yic.ac.cn; ymluo@yic.ac.cn
Source Publication科学通报
Keyword微塑料污染 表面微形貌 丰度 连续流动-气浮分离 海岸带土壤

微塑料(<5 mm)作为海岸带地区的新型污染物正越来越受到关注. 本研究以我国河北省曹妃甸围填海区潮滩土壤为例, 采用自行改进设计的连续流动-气浮分离一体化装置, 有效分离和提取了潮滩土壤样品中微塑料,并结合扫描电子显微镜-能谱仪(SEM-EDS)对微塑料表面的微观特性进行了表征. 研究结果表明, 供试土壤中微塑料丰度达到317 n/500 g(其中n表示微塑料个数), 平均粒径为1.56±0.63 mm, 其中<1 mm的微塑料占49.8%; 微塑料丰度上整体呈现随粒径变小而增加的趋势. 在土壤中分离到碎片、颗粒、纤维和薄膜四类微塑料, 其中, 黑色碎片类微塑料为首次报道的类型. 颗粒类微塑料丰度最大但平均粒径最小. 土壤中微塑料表面均有不同程度的风化痕迹, 具有不同形态和大小的微孔结构. 在部分微塑料中还发现其表面附着稳定的铁氧化物. 未来需要深入研究了解基于微塑料表面特性的污染物结合机制、生物积累与生态毒性, 尤其更需关注丰度较高、颗粒更细的<1 mm的这部分微塑料(MP1).

Other Abstract

Microplastics (<5 mm) are emerging pollutants in the coastal zone and are of worldwide concern. Previous studies have shown the importance of surface features of microplastics on the adsorption and transport of chemical pollutants in the ocean and coastal environment. The objective of this study was therefore to characterize the surface properties of the microplastic samples from a reclamation area polluted by plastic debris in Chaofeidian, Hebei Province. A surface (0–2 cm) soil composite sample was collected from several square plots each with an area of 1 m×1 m. The microplastics were separated in two steps. Firstly, 500 g (dry weight) soil sample was reduced to <100 g soil which contained most of the microplastics using continuous air-flow flotation separation apparatus designed by our own group. Secondly, the microplastics were separated from the soil by density separation using NaI solution (1.8 g cm3 ) followed by visual selection. All the microplastics were photographed and image analysis was performed using the program Nano Measurer 1.2 for counting and size measurement. The microscopic features of the microplastic surfaces were characterized using a scanning electron microscope equipped with an energy dispersive spectrometer (SEM-EDS). Four types of microplastics, namely fragments, granules, fibers and films, were separated from the test soil and black film is a new type of microplastic reported here for the first time. The abundance of all the microplastics was 317 n (500 g)1 (dry weight) at this site with granulate microplastics accounting for 75% of the total abundance followed by fragments accounting for 20%. The size of the microplastics was 1.56±0.63 mm on average and the <1 mm size fraction accounted for 49.8% of the material. The abundance of the different size fractions of the microplastics was negatively correlated with their size in general. Granules were the most abundant type with the smallest average size on the whole. The abundance and size of the microplasitcs found at this site were comparable to those in other study areas such as a coastal sand beach in Belgium and mangrove sediment in Singapore. The SEM results show weathering features on the microplastic surfaces which were characterized by various porous morphologies and structures. The surface of microplastic samples from the soil was rough with pronounced cavities and similar to previous results observed in coastal environments. However, the surface morphology was distinctly different from that of the virgin plastics. The uneven surface of the microplastics might increase fouling due to changes in surface area and other properties as reported in other studies. We used two solutions (H2O and 2 mol L1 HCl) to distinguish the foulants between stable and loose combinations. The adhering soil particles were easily removed by washing with water and HCl. However, iron oxides were observed adhering tightly to the surfaces of some of the microplastics and could not be removed by washing with 2 mol L1 HCl. Since there are several types of iron oxides with different surface properties, their stable combination with the mciroplastics might have a pronounced impact on the surface alteration of the microplastics. Moreover, the complicated surfaces of the weathered microplastics likely have very different adsorption characteristics for chemical pollutants compared with the unaltered virgin plastic surfaces. More surface properties of weathered mciroplastics (including pore volume, crystalline structure, and functional groups) must therefore be identified. Moreover, further studies are required to explore the binding mechanisms of chemical pollutants on the microplastic surfaces and the bioaccumulation and ecological toxicity of these combined pollutants with respect to the different surface morphologies and other characteristics of the microplastics with special concern regarding microplastics that are dominated by the <1 mm fraction (MP1).

Funding Organization中国科学院重点部署项目(KZZD-EW-14),中国科学院战略先导专项(XDA11020402)资助
Indexed ByEI ; CSCD
EI KeywordsAir ; Biochemistry ; Coastal zones ; Flotation ; Granulation ; Iron oxides ; Marine pollution ; Morphology ; Pollution ; Scanning electron microscopy ; Soils ; Spectrometers ; Surface morphology ; Surface properties ; Washing
EI Accession Number20162502515409
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Document Type期刊论文
Corresponding Author章海波,骆永明 E-mail: hbzhang@yic.ac.cn; ymluo@yic.ac.cn
Recommended Citation
GB/T 7714
周倩,章海波,周阳,等. 滨海潮滩土壤中微塑料的分离及其表面微观特征[J]. 科学通报,2016,61(14):1604-1611.
APA 周倩.,章海波.,周阳.,李远.,薛勇.,...&ymluo@yic.ac.cn.(2016).滨海潮滩土壤中微塑料的分离及其表面微观特征.科学通报,61(14),1604-1611.
MLA 周倩,et al."滨海潮滩土壤中微塑料的分离及其表面微观特征".科学通报 61.14(2016):1604-1611.
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