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渤海微塑料分布及其影响因素研究
代振飞
Subtype硕士
Thesis Advisor章海波 ; 骆永明
2018-05-21
Training institution中国科学院烟台海岸带研究所
Degree Grantor中国科学院大学
Place of Conferral中国科学院烟台海岸带研究所
Degree Name工学硕士
Degree Discipline环境科学
Keyword微塑料 渤海 分布 密度 表面变化 影响因素 Microplastic the Bohai Sea Distribution Density Surface Change Influencing Factors
Abstract海洋环境中的微塑料污染日益严峻。微塑料在潮汐、波浪、河流输送等作用下可以远距离迁移,并在各层海水、海底沉积物中分布。目前对海洋环境中微塑料的调查大多关注表层水体;国内对海洋水柱中微塑料分布研究尚未有报道,国际上的研究也相当有限。因此,本研究主要关注微塑料在海洋环境中的垂直分布状况及影响因素,主要包括以下内容:(1)开展了渤海各层海水和海底沉积物中微塑料分布的航次调查;(2)选择不同类型的微塑料进行了近海试验,观察、分析微塑料的密度和表面形貌随时间的变化;(3)开展了光照、生物、海水等因素影响下的实验室模拟研究,探讨了人类活动和自然条件交互作用对微塑料的含量和垂直分布的影响。 通过对渤海各层海水和海底沉积物中微塑料分布调查,渤海水体中微塑料的丰度在0.2-23 N/L,平均丰度为4.4±5.0 N/L;在渤海表层沉积物中,微塑料丰度为31.1-256.3 N/kg(沉积物干重),平均值为102.0 (±73.4) N/kg。渤海表层水体微塑料污染主要受到海上行船排污和沿岸居民生产生活的直接影响;有一半的渤海航次站点的中层和底层海水微塑料因受到不同深度海流流速、流向的差异而在5-10 m水体聚集,其他站点微塑料在海洋各水层的分布与其垂直迁移速度和排放入海的速度相关;沉积物中的微塑料的丰度与上层水体浊度以及叶绿素a含量密切相关,较高水体浊度和浮游植物生物量有利于微塑料在沉积物中积累。 渤海环境中的微塑料类型总体以纤维类为主。在表层海水、近海水柱和海底沉积物中发现的最大密度纤维类微塑料均为聚酯类,而最大密度碎片类微塑料依次是聚苯乙烯、聚对苯二甲酸乙二醇酯和聚氯乙烯,最大密度随深度递增;微塑料的密度大小影响着碎片类微塑料在不同水层中的分布情况。微塑料的颗粒大小也随着深度的增加呈规律性分布。近海水层中,粒径小于300 μm和纤维类的微塑料比例有递增的趋势,这表明较小的微塑料和纤维类微塑料更容易迁移至下层水体。同时也说明对于目前在海洋微塑料调查中普遍使用的330 μm浮游生物网采样可能会低估中下层水体中微塑料的丰度。 通过实验室模拟研究表明,光照老化会使微塑料表面变粗糙,出现裂痕和裂纹,并且使聚乙烯微塑料的密度出现小幅升高,但尼龙颗粒和聚苯乙烯颗粒的密度未出现变化;而海水中培养的微塑料表面可以观察到细菌。通过对硅藻共培养的微塑料表面检测发现,微塑料表面出现了胞外聚合物的红外特征峰,电镜照片也显示胞外聚合物在微塑料表面粘结成小片或形成块;纤维类微塑料与硅藻共培养后密度的增加幅度要明显高于颗粒类微塑料,这与渤海调查中纤维类微塑料比例随深度增加而递增的结果相一致。 通过对放置于实际海水环境中的微塑料进行分析,发现微塑料的密度变化总体要大于其在实验室模拟环境中的变化,密度均有不同程度的增加,其中微塑料类型和海洋环境条件是影响微塑料密度改变的主要因素。微塑料的密度变化在不同海水深度上变化有明显差异。放置于表层和中层海水中的微塑料主要受到海流的影响,密度变化较为相近;而放置于底层海水中的微塑料除受到海流影响外,还受到底层沉积物的再悬浮影响,微塑料变化特征与表层、中层海水不同。总体上,稳定的海况有利于微塑料与悬浮颗粒物、藻类等形成相对稳定的复合物,从而改变微塑料的密度。通过扫描电镜和傅里叶变换红外光谱分析表明,微塑料表面粘附的物质包括藻类残体和悬浮颗粒物,这与渤海水体与沉积物调查中发现的微塑料样品表面存在藻类与颗粒物附着的情况一致,进一步证明水体中颗粒物和生物质可能对微塑料在水体中的垂直分布具有一定的贡献。
Other AbstractThe microplastic pollution of marine environment has become quite severe and microplastics are readily transported long distance from source areas by wind and water, and distributed across coastal zone, surface water and sediments in the marine environment. The studies of microplastic distribution always paid attention to surface seawater, there were few studies reported of the microplastic in sea water column in China. The studies of distribution of microplastic in the seawater column were also rare internationally. Therefore, this study mainly focused on the distribution and influencing factors of microplastics in the marine environment. First, the distribution of microplastics in different seawater layer and surface sediments at the Bohai Sea was investigated. Second, different types of microplastics were selected to conduct field experiments in the seawater, density and surface topography changes were analyzed at different times. Thrid, The laboratory experiments under UV light, biology and sea water were also conducted. The effects of human activities and natural conditions on the horizontal and vertical migration of microplastics and their influencing factors and changes were discussed. According to the investigation of microplastics in the seawater and surface sediments in the Bohai Sea, it was found that the microplastic concentrations ranged from 0.2-23 N/L in the Bohai seawater, with an average of 4.4 (±5.0) N/L. In the surface sediments, the average microplastic concentration was 102.0 (±73.4) pieces/kg dry sediments, in the range of 31.1-256.3 N/kg. The microplastics contamination of the surface waters in the Bohai Sea was mainly affected by the discharging of boats in the sea and the anthropogenic activities of the coastal residents. In half of the sampling stations,microplastics accumulated in the 5-10 m because the discrepancy of flow velocity direction in different water layer currents. The distribution of microplastics in other sites in the ocean was related to their vertical migration velocity and the discharge velocity into the sea. There was a corresponding relationship between the contents of turbidity, chlorophyll a in the upper water and the concentration in the sediments at the same site. Higher turbidity and higher chlorophyll a contents were favorable for the sedimentation of microplastics, which reflected the contribution of particulates and biomass in the water to the vertical migration of microplastics. The microplastics in the Bohai Sea were dominated by fibers. The maximum density fibers microplastics found in surface seawater, water column and seabed sediments were all polyesters, while the maximum density microplastics were in the order of polystyrene, polyethylene terephthalate, and polyvinyl chloride, the maximum density increased with depth;the vertical distribution of microplastic fragments in different water layers was affected by the densities of microplastics. The particle size of microplastics also showed a regular distribution as the depth increases. In the seawater, the proportion of microplastics less than 300 μm and fibers was increasing with depth, which indicated that smaller microplastics and fibers were more likely to migrate to deeper water bodies. At the same time, this also indicated that the sampling of the 330 μm plankton net used in marine microplastics surveys may underestimate the abundance of microplastics in the middle and bottom layers of water. In the laboratory experiments, the surface of microplastics under UV light was rough, cracks appeared, the densities of polyethylene microplastics increased slightly, while the densities of nylon and polystyrene remained unchanged. Bacteria were observed on the microplastic surface in sea water. The characteristic peaks of the extracellular polymers were detected on the surfaces of the diatom co-cultured microplastics by FTIR, as a result of forming small pieces blocks showed by the SEM. The changes in the densities of fibers were significantly higher than that of granular microplastics, which was consistent with the increasing proportion of fiber as the depth increaseed in the surveys. By analyzing the changes of microplastics placed in seawater, it was found that the changes in the density of the microplastics were greater than that in the laboratory experiments. The densities of microplastics were increased. The type of microplastics and the state of the marine environment were the main factors affecting the density changes of microplastics. The changes in densities of microplastics varied significantly between the depths. Because the surface and middle seawater were mainly affected by currents, the density changes were similar, while the bottom water body was also not only affected by the currents, but also the resuspension of the bottom sediments, The density changes of microplastic put in bottom water were different with the surface and middle seawater. It was conducive to form a solid aggregate structure between microplastics and environmental substances such as suspended particles and algae when the sea was stable, which changed the densities of microplastics. The SEM and FTIR showed that substances adhered to the surfaces of microplastics include algae residues and suspended particles, which was accompanied with the algae residues and suspended particles found in the microplastics sampled in the Bohai sea water and surface sediments, and the corresponding relationship between the contents of turbidity, chlorophyll a in the upper water and the concentration in the sediments, reflected the contribution of particulates and biomass in water to the vertical migration of microplastics altogether.
Pages82
Language中文
Document Type学位论文
Identifierhttp://ir.yic.ac.cn/handle/133337/25312
Collection中科院烟台海岸带研究所知识产出_学位论文
Recommended Citation
GB/T 7714
代振飞. 渤海微塑料分布及其影响因素研究[D]. 中国科学院烟台海岸带研究所. 中国科学院大学,2018.
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