KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 黄河口海岸环境中微塑料生物膜的特征、时空变化和表面效应 | |
| Alternative Title | Characteristics, Spatiotemporal Changes and Surface Effects of Biofilm on Microplastics in Coastal Environment of the Yellow River Estuary |
| 张晨捷 | |
| Subtype | 硕士 |
| Thesis Advisor | 潘响亮 ; 骆永明 ; 纪灵 |
| 2020-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 工程硕士 |
| Keyword | 黄河口 海岸带 PE 薄膜 PP 扁丝 微塑料 生物膜 风化 Yellow River Estuary Coastal zone PE film PP flake Microplastics Biofilm Weathering |
| Abstract | 微塑料污染已成为仅次于气候变化的全球第二大环境问题，受到广泛关注。海岸带是受人类活动和气候变化双重影响的陆海交互作用地带，也是环境中微塑料的重要汇集区。国内外已有针对海岸带区域的微塑料污染研究，但大多研究是在海水环境介质中开展，缺乏海岸带环境中由陆到海的空间梯度上微塑料及其表面生物膜的长期原位暴露及动态变化研究。因此，本研究针对长期暴露于黄河口海岸带潮上带、潮间带和潮下带环境后，微塑料表面生物膜特征的时空动态变化及其对微塑料表面理化性质的影响，开展了（ 1）海岸带环境中微塑料表面生物膜形貌、总量和物理结构的时空动态变化；（ 2）海岸带环境中微塑料表面生物膜的微生物群落结构时空动态变化；（ 3）海岸带环境中微塑料表面生物膜形成与表面理化性质变化等方面的研究，取得的主要结果如下：（ 1）掩埋在海岸带不同区域的微塑料样品表面有多种微生物附着， 球菌和杆菌出现在大多数微塑料表面， 聚乙烯（ Polyethylene， PE） 薄膜表面以球菌为主， 聚丙烯（ Polypropylene， PP） 扁丝表面以杆菌为主。微塑料表面生物膜总量在空间上呈现出潮上带空气暴露处理最高的规律，在时间尺度上表现为夏季（ 12个月）高于冬季（ 18 个月）；对同一类型聚合物而言，尺寸对生物膜总量变化无显著效应；在不同类型聚合物间， PP 扁丝单位面积上生物膜总量更高。在结构分布上，潮上带微塑料的生物膜以菌体为主，潮间带和潮下带的生物膜以胞外多聚物（ Extracellular polymeric substances, EPS）为主；生物膜平均厚度在时间尺度上的变化与生物膜总量变化基本一致。（ 2）高通量测序结果表明，微塑料表面物种丰度从潮上带、潮间带至潮下带呈梯度递减，有少数潮上带、潮间带和潮下带环境中普遍存在且可以在微塑料表面定殖的物种。变形菌门（ Proteobacteria）、拟杆菌门（ Bacteroidete）和放线菌门（ Actinobacteria）是微塑料表面最主要的菌群，三类菌群在时间尺度上的变化规律并不显著，放线菌门则在空间尺度上有明显变化规律，呈潮上带、潮间带、潮下带梯度递减。潮上带地下部微塑料表面微生物与土壤微生物物种组成高度重叠，在聚合物类型间存在一定差异；潮间带和潮下带微塑料表面的微生物丰度介于沉积物与海水之间，其表面微生物主要来源于沉积物。微塑料与环境介质样本中微生物的物种丰度存在显著差异，潮下带微塑料表面的硫卵菌属（ Sulfurovum）和假单胞菌属（ Pseudomonas）丰度远高于海水和沉积物。（ 3）微塑料在黄河口潮上带、潮间带和潮下带等不同海岸环境中暴露 12 个月和 18 个月后，表面出现胞外多聚物的红外特征峰，理化性质也发生改变，出现风化痕迹。暴露于潮上带地上部的微塑料表面裂化现象和密度下降最为显著，除潮上带地上部外，微塑料密度随着暴露时间出现先增长后下降的趋势。潮上带和潮间带暴露微塑料疏水性仅在暴露初期出现下降，之后在时间上没有显著变化。所有野外暴露处理的微塑料表面均有羰基产生，且羰基指数呈潮上带 > 潮间带 >潮下带的趋势。综合微塑料的表面微形貌特征、密度、疏水性以及化学官能团（羰基指数）的动态变化等指标表明，黄河口潮上带地上部暴露的微塑料风化特征随时间变化最为显著。微塑料风化程度总体呈潮上带至潮间带、潮下带下降趋势，这一结果与微塑料表面生物膜总量的变化规律相一致。本学位论文的研究结果将为揭示海岸带环境中微塑料的生物风化过程提供科学依据，同时可应用于海洋微塑料污染监测需求方面。 |
| Other Abstract | Microplastic pollution has become the second important global environmentalissue in world besides climate change, which has caused widespread concern. Coastalzone is a region of land-ocean interaction under the dual impacts of human activitiesand climate change. It is also an important sink for microplastics in the environment.There have been some studies on microplastic pollution in the coastal zone. But mostof the researches were conducted in seawater. There is a lack of studies on thelong-term in situ exposure of microplastics and the dynamic changes of biofilms onmicroplastics on the spatial gradient from land to sea in the coastal environment.Therefore, this study aimed at the spatiotemporal dynamic changes of biofilmcharacteristics on microplastics and their effects on the physical and chemicalproperties of microplastics after long-term exposure in the supratidal, intertidal andsubtidal environments of the Yellow River Estuary. The following researches wereconducted: (1) The spatiotemporal dynamics of morphology, amounts and physicalstructure of biofilm on the microplastics in the coastal environment; (2) Thespatiotemporal dynamics of the microbial community structure of biofilm on themicroplastics in the coastal environment; (3) Formation of biofilm and changes ofphysical and chemical properties on the surface of microplastics in coastalenvironment. The main results are as follows:(1) Many kinds of microorganisms were identified attaching on surface of themicroplastics buried in different tidal zones of the coastal environment. The coccusand bacilli attached on surface of most microplastics. The dominant colonizedmicrobes were coccus and bacilli for Polyethylene (PE) films and Polypropylene (PP)flakes, respectively. The amounts of biofilm on microplastics showed the highestbiomass with air exposure in the supratidal zone, and the amounts of biofilm insummer (12 months) was higher than in winter (18 months) on the time scale. For thesame type of microplastics, the size has no significant effects on the amounts of biofilm. For different type of microplastics, the amounts of biofilm per unit area of PPflake was higher than the PE film. For structure of biofilm, the biofilm was mainlycomposed of bacteria on microplastics exposed in the supratidal zone, while it wasmainly composed of extracellular polymeric substances (EPS) on microplasticsexposed in the intertidal and subtidal zones. The changes of average biofilm thicknesswas almost consistent with the changes of amounts of biofilm on the time scale.(2) The results of high-throughput sequencing showed that the species abundanceon the microplastics decreased gradually from the supratidal zone to intertidal zoneand subtidal zone. There were a few species that are universal in the different tidalenvironments and can colonize the surface of microplastics. Proteobacteria,Bacteroidete and Actinobacteria were the dominating microbes attached on thesurface of microplastics. The succession of these above microbes was not significanton the time scale. The Actinobacteria showed a significant rule of succession on thespatial scale, showing a decreasing gradient in the supratidal zone, intertidal zone andsubtidal zone.The microbes of microplastics and the soil in the supratidal underground were highlyoverlapped, and there were some differences between PE film and PP flake. Themicrobial abundance of microplastics was between the sediment and the seawater inthe intertidal zone and subtidal zone, and the microbes of microplastics mainlyoriginated from the sediment. The microbial abundance of microplastics andenvironmental media was significantly different. The abundances of Sulfurovum andPseudomonas on the microplastics were much higher than in seawater and sedimentin the subtidal zone.(3) Infrared peaks of EPS appeared and physicochemical properties changed onthe surface of microplastics exposed in different tidal zones after 12 months and 18months. Meanwhile, microplastics showed marked signs of weathering. Themicroplastics in the supratidal aboveground exhibited the highest degree of crackingand decrease in density. The density of microplastics increased first and thendecreased in the time, with the exception of microplastics in supratidal aboveground.The hydrophobicity of the microplastics exposed in the supratidal and intertidal zones decreased at the beginning, but without any significant change afterwards. Carbonylgroups were also observed on the surface of the microplastics from all the tidal zones.The carbonyl index of the microplastics, from three tidal zones displayed an order ofsupratidal zone > intertidal zone > subtidal zone. The dynamic changes inmorphological characteristics, density, hydrophobicity and chemical functional groups(carbonyl index) of the microplastics indicate that the microplastics in the supratidalzone varied sharply with time in weathering characteristics. The weathering degree ofthe microplastics varying with the tidal zone showed a declining order of supratidalzone > intertidal zone > subtidal zone. This result was consistent with the changeorder of the amounts of biofilm on the microplastics.The results of this research will provide a scientific basis for revealing thebiological weathering process of microplastics in the coastal environment, and canalso be applied to the monitoring needs of marine microplastic pollution. |
| Subject Area | 环境工程 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15471 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 张晨捷. 黄河口海岸环境中微塑料生物膜的特征、时空变化和表面效应[D]. 北京. 中国科学院大学,2020. |
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