胶州湾海洋生态系统国家野外研究站知识库

摘  要

微塑料是一种重要的海洋污染物，通常是指尺寸小于5毫米的塑料颗粒、纤维或者薄膜。它们分布广、个体小、危害大、难去除，常被称为“海洋中的PM2.5”。国际上对微塑料的数量、分布、风险、防控等问题极为重视，近年来不断出现在高峰论坛和联合国环境问题议题中。在联合国发布的17个可持续发展目标(Sustainable Development Goals, SDG)中，SDG 14.1就专门提出了减少海洋塑料与微塑料污染的问题。

目前国外内学者围绕海洋环境中的微塑料开展了大量的调查研究，使我们对海洋中微塑料的基本分布和特征有了一定的了解，但由于微塑料问题的复杂性，使得海洋中微塑料的很多问题尚待解决，例如海洋中微塑料“丢失”的问题、海洋中微塑料的迁移特征、海洋食物网中的微塑料等，这些问题的解决需要针对海洋环境和海洋生物开展更为系统、更为精细的观测。从水体微塑料的调查情况看，季节变化的研究较为缺乏，海水中季节变化是否显著需要关注。另外，海水中微塑料的一个重要去向是海洋浮游食物网，受观测方法的影响，海洋浮游动物体内的微塑料通常和水体中的微塑料一起消解而被统计入水体中，导致难以了解真正在海洋浮游食物网中存留的微塑料的数量、特征及其时空变化规律。因此，目前关于浮游动物体内微塑料的研究很少，其季节变化特征及影响因素的研究更为缺乏。针对上述问题，本论文以近海典型海湾胶州湾为代表性区域，分别针对水体和浮游动物体内的微塑料，开展了春夏秋冬四个季节的航次调查，研究了胶州湾水体与不同类群浮游动物体内微塑料的季节变化特征，结合环境因子分析了影响胶州湾水体与浮游动物体内微塑料数量与分布的因素，得到的主要结果和结论如下：

通过采用两种不同孔径的BONGO-NET收集胶州湾表层水体中的微塑料，结果表明两种不同过滤孔径的水平拖网采样结果不同，分别估算出胶州湾表层水体中微塑料的数量分别为：500 μm BONGO-NET采样，胶州湾表层水体中微塑料的数量在0~0.516 MPs/m³之间，平均为0.095 MPs/m³；300 μm BONGO-NET采样，胶州湾表层水体中微塑料的数量变化范围是0.031~1.482 MPs /m³之间，平均为0.275 MPs/m³。经过比较两种网具采样下得出的表层水体数量有显著差异(p< 0.05)，300 μm 拖网获得的微塑料数量明显高于500 μm 拖网获得的结果，平均为2.89倍。胶州湾表层海水中的微塑料以聚丙烯 (Polypropylene, PP)和聚乙烯 (Polyethylene, PE)成分为主，纤维状与碎片状为主要的形状。与采用同样观测方法的其他海域相比，胶州湾水体中微塑料数量略低于黄海，需要进一步结合不同海域的特征开展来源迁移特征等方面的对比研究。

在胶州湾浮游动物体内微塑料的研究方面，首先通过对最具优势的类群桡足类体内微塑料的季节性变化开展研究。结果表明，胶州湾四个季节的单个桡足类个体中微塑料数量为：冬季0.26 ± 0.09 MP/ind.，春季0.23 ± 0.12 MP/ind.，夏季0.14 ± 0.05 MP/ind.，秋季0.16 ± 0.09 MP/ind.，年平均为0.21 ± 0.10 MP/ind.。胶州湾桡足类中微塑料数量存在明显的季节差异 (p< 0.05)。冬季和春季的桡足类中微塑料数量均高于夏季。靠近河口区的桡足类中微塑料数量(MP/ind.)显著高于湾内。桡足类摄食的微塑料尺寸范围为90~2485 μm，平均为454 ± 376 μm，其中 90%以上的微塑料长度小于1 mm。形态主要是纤维状微塑料，在已报导海域中胶州湾桡足类体内纤维状微塑料所占比例最高。主要化学成分为聚酯纤维和赛璐玢。不同季节的微塑料组成特征无显著差异(p> 0.05)。与其他海域相比，胶州湾桡足类中微塑料数量与东海海域、南海北部相近，显著高于南海南部、美国查理斯顿海港和东北太平洋等海域。相关性分析结果表明，温度是影响桡足类体内微塑料数量的关键环境因子。

进一步对浮游动物中肉食性类群毛颚类体内的微塑料数量与特征的季节变化开展研究。结果表明，胶州湾四个季节单个毛颚类体内微塑料数量为：冬季0.19 ± 0.09 MP/ind.，春季0.17 ± 0.06 MP/ind.，夏季0.15 ± 0.07 MP/ind.，秋季0.39 ± 0.31 MP/ind.，年平均为0.18 ± 0.11 MP/ind.。毛颚类中微塑料的数量存在明显的季节性差异(p < 0.05)，秋季的毛颚类中的微塑料数量(MP/ind.)显著高于春季、夏季和冬季。毛颚类中微塑料的数量与环境因子的相关性表明毛颚类中微塑料的数量与环境因子无显著相关关系。胶州湾毛颚类中微塑料的尺寸范围为79~2368 μm，平均为452 ± 391 μm。毛颚类主要摄食的微塑料形态是纤维，与其饵料生物桡足类体内微塑料的形态高度一致，摄食的微塑料大小大部分都在1000 μm以下，聚酯纤维是主要摄食的微塑料。四个季节中毛颚类中的微塑料形态、大小和化学组成等特征均没有显著的差异。与其他海域相比，胶州湾毛颚类个体内微塑料数量微塑料与渤海、黄海、东海、南海北部和东阿拉伯海等海域相当，可能是受人类活动或动力过程的显著影响。

结合胶州湾两大浮游动物优势类群桡足类与毛颚类体内微塑料的研究，进一步分析研究了胶州湾其余五个不同类群浮游动物个体内微塑料数量和特征的季节变化。结果表明短尾类幼体、长尾类幼体、水母、仔稚鱼及其他类群浮游动物体内微塑料的数量范围在0到0.68 MP/ind.之间，其中长尾类幼体内的微塑料平均数量为0.19 MP/ind.，水母与短尾类生物体内的平均数量约为0.23 MP/ind.，仔稚鱼和其他类群中的微塑料分别为0.52和0.43 MP/ind.。胶州湾七个浮游动物类群中的微塑料数量平均约为0.28 ± 0.13 MP/ind.。不同类群中的微塑料数量差异显著，其他类群中的微塑料数量显著高于桡足类、毛颚类及长尾类幼体中的微塑料数量，仔稚鱼中的微塑料数量显著高于毛颚类。春、夏、秋、冬四个季节浮游动物体内微塑料的平均数量分别为0.22 MP/ind.、0.20 MP/ind.及0.37 MP/ind.和0.39 MP/ind.，其中冬季显著高于夏季。胶州湾浮游动物体内微塑料尺寸范围为78 ~3123 μm，平均为491 ± 454 μm，微塑料的形状以纤维状为主，成分以聚酯纤维为主，不同季节间成分组成差异不显著。

基于胶州湾不同浮游动物类群的数量和单个浮游动物个体内微塑料的数量，估算通过大型浮游生物网采集的胶州湾浮游动物群落中的微塑料总体存量在0.34~11.30 MPs/m³之间，平均为5.33 MPs/m³。胶州湾浮游动物微塑料存量与黄海相近，略高于东海、南海，远远高于东北太平洋、巴西戈亚纳河口等海域。受浮游动物数量及海水中的微塑料浓度影响，冬季和春季浮游动物群落中微塑料的赋存量较低，春季和夏季存量较高。

综上，本论文以典型海湾胶州湾为目标海域，系统开展胶州湾表层水体微塑料数量与特征的季节变化研究，揭示风和降水等要素对海湾微塑料分布格局的影响。首次分类群开展胶州湾浮游动物体内微塑料数量、特征与季节变化规律研究，揭示桡足类、毛颚类等典型浮游动物类群体内微塑料特征，并结合环境因子的变化分析影响胶州湾浮游动物体内微塑料变化的关键因子。基于分类群浮游动物数量和浮游动物个体微塑料数量，定量估算胶州湾浮游动物群落内微塑料的赋存量，为深入了解海洋中微塑料的迁移、寻找海洋中缺失的微塑料、评估海洋食物网微塑料的生态风险提供科学依据。

关键词：胶州湾，微塑料，海水，浮游动物，季节变化

Abstract

Plastic pollution is a global environmental issue. Microplastic contamination is a growing threat to marine environment and biota, and represent a great risk for marine ecosystems, society and human health. The sustainable development of coastal areas faces serious challenges. The UN Sustainable Development Goals 14 is life below water. And the Target 14.1 is to Prevent and significantly reduce marine pollution of all kinds by 2025. One of indicators is index of floating plastic debris density.

At present, a large number of investigations and studies have been carried out globally on microplastics in marine environment. However, due to the different sampling and analysis methods of microplastics used in different studies, it is difficult to integrate and compare the observation results of different studies. Moreover, most of these are single sampling rather than seasonal surveys. In addition, an important destination for microplastics in the ocean is the marine food web, and the retention of microplastics in the marine food web is ignored in current estimates. As an intermediate link in the food web, variation of zooplankton abundance and feeding characteristics on microplastic are critical to reveal the microplastic stocks in the marine food web. However, there are few studies on microplastics in zooplankton, and scarcely any studies on their seasonal variation characteristics and influencing factors. Therefore, to systematically understand the distribution and migration and transformation mechanism of microplastics in different media in coastal waters, it is urgent to carry out seasonal characteristics of microplastics in water and zooplankton, using a uniform research method in typical coastal areas.

Jiaozhou Bay is a semi-enclosed temperate bay situated on the western side of the Yellow Sea, surrounded by Qingdao city. It is considered a typical bay in the northern part of China, as is which hosts intensive human activities. For the first time, we conducted the study of MPs in seawater and zooplankton across the four seasons, revealed the characteristics of microplastics in the seawater and zooplankton of Jiaozhou Bay, explored the seasonal variation of microplastics in Jiaozhou Bay and analyzed the factors affecting the seasonal changes of plastics in Jiaozhou Bay. We hope to provide more evidence for the seasonal changes of microplastics and basis for the potential ecological risk of MPs via zooplankton in similar coastal regions. The main results and conclusions are as follows:

The microplastics in surface seawater were collected by two types of BONGO-NET at 14 stations in Jiaozhou Bay in four seasons. Result showed that the average adundance of microplastics in seawater collected by 500 μm BONGO-NET was 0.095 MPs/m³, while that collected by 300 μm BONGO-NET was 0.275 MPs/m³. There was a significat difference in abundance of microplastics collected by the two types of net. The main shapes of microplastics in seawater were fibers and fragments, and the dominant chemical composition was polypropylene (PP) and polyethylene (PE). Compared with other coastal areas, the abundance of microplastics in Jiaozhou Bay is lower than that in other coastal waters in China, and is significantly lower than that in bays of USA and Brazil.

For microplastics in zooplankton in Jiaozhou Bay, we firstly focused on copepods, which are the most abundant group in zooplankton in Jiaozhou Bay. The purposes were to reveal the characteristics of MPs in copepods, explore the seasonal changes in MPs ingested by copepods and evaluate the environmental factors that may affect the ingestion of MPs by copepods in Jiaozhou Bay. The results revealed a significant seasonal difference in MP/ind. values of copepods in Jiaozhou Bay. MP/ ind. values were 0.26, 0.23, 0.14 and 0.16 in February, May, August and November, respectively. The MP/ind. value of copepods was significantly higher in winter and spring than in summer and significantly higher in the estuarine zone than in other zones. Seawater temperature was negatively correlated with the MP/ind. value of copepods. No significant seasonal differences were detected in the characteristics of MPs in copepods in Jiaozhou Bay. The size of MPs in copepods ranged from 90 to 2485 μm, with an average of 454 ± 376 μm. Fiber MPs were the most risky to copepods, accounting for 92% of the total ingested MPs. In terms of the chemical composition of the MPs, a total of 11 polymers were detected in copepods in Jiaozhou Bay in the four seasons. The main components were polyester and cellophane (41.9% and 25.7%, respectively). The results provide the key parameters of the MPs in copepods in Jiaozhou Bay and is an important basis for further ecological risk assessments of MPs.

Furtherly, we studied microplastics in chaetognaths, to reveal the characteristics of MPs in carnivorous zooplankton groups and explore the potential effect by microplastics transferred through food webs. The results showed the MP/ind. values of chaetognaths in Jiaozhou Bay were 0.19, 0.17, 0.15 and 0.39 in February, May, August and November, respectively. The MP/ind. value of chaetognaths was significantly higher in autums than in other seasons. There was no correlation between MP/ind. value of chaetognaths and environmental and biological factors. The size of MPs in chaetognaths ranged from 79 to 2368 μm, with an average of 452± 391 μm. The main shape of MPs were fibers, and the dominante chemical component was polyester. No seasonal differences were detected in the characteristics of MPs in chaetognaths. Compared with other coastal areas, the abundance of microplastics in Jiaozhou Bay is similar with that in other coastal waters in China, and Arabian Sea.

Based on the above analysis, we investigated the abundance and characteristics of microplastis in different zooplankton groups in Jiaozhou Bay, and estimated the stock of microplastics in zooplankton, and provide a basis for ecological risk assessments of MPs in coastal areas. Results showed that, the average MP/ ind. values were 0.19, 0.23, 0.23, 0.52 and 0.43 of shrimp larvae, brachycauda larvae, medusae, fish larvae, and other zooplankton group, respectively. It also revealed that the MP/ind. value of other zooplankton group was significantly higher than that of copepods and chaetognaths. The MP/ind. value of total zooplankton groups were 0.22, 0.20, 0.37 and 0.39 in February, May, August and November, respectively. The MP/ind. value of total zooplankton groups was significantly higher in winter than in summer. The size of MPs in total zooplankton groups ranged from 78 to 3123 μm, with an average of 491± 454 μm. The main shape of MPs were fibers, and the dominante chemical component was polyester. No seasonal differences were detected in the characteristics of MPs in total zooplankton groups.

Estimated by abundance of total zooplankton groups and MPs per zooplankton, the stock of microplastics in zooplankton in Jiaozhou Bay ranged from 0.34 to 11.30 MPs/m³, with the average of 5.33 MPs/m³. Affected by variation of zooplankton abundance, the stock of microplastics in zooplankton were higher in winter and spring than that in summer and autums. Compared with other coastal areas, the Stock of microplastics in zooplankton in Jiaozhou Bay is similar with that in other coastal waters in China, and significantly higher than that in euasty in Brazil and northeast Pacific.

In summary, we took Jiaozhou Bay as a typical coastal area, systematically studied the seasonal variation of the abundance and characteristics of microplastics in the surface water and different zooplankton taxon in Jiaozhou Bay. The influence of wind and precipitation on the distribution pattern of microplastics in the bay. The abundance, characteristics and seasonal variation of microplastics in typical zooplankton taxon groups such as copepods and trichognathus were dipcted. The key factors affecting the change of microplastics in zooplankton in Jiaozhou Bay combined with the changes of environmental factors were analyzed. Based on the abandance of zooplankton and the concertration of microplastics in individual, the stock of microplastics in the zooplankton community in Jiaozhou Bay was quantitatively estimated, which provided a scientific basis for understanding the cycle of microplastics in the ocean, searching for missing microplastics in the ocean, and assessing the ecological risk of microplastics.

Key Words: Jiaozhou Bay,Microplastics,Seawater,Zooplankton,Seasonal Variation

目  录

第1章 绪  论... 1

1.1 海洋微塑料的定义、来源及危害... 1

1.1.1 海洋微塑料的定义与来源... 1

1.1.2 微塑料对海洋生态系统的危害... 2

1.2 海水中微塑料的分布与特征... 4

1.2.1 海水中微塑料的分布格局... 4

1.2.2 海水中微塑料的主要特征... 4

1.2.3 海湾水体中的微塑料... 5

1.3 海洋浮游动物体内的微塑料研究... 8

1.3.1 自然海域浮游动物对微塑料的摄食... 9

1.3.2 微塑料对浮游动物的影响... 11

1.4 本研究目的与意义... 14

第2章 胶州湾表层水体中的微塑料数量与特征的季节变化研究... 15

2.1 前言... 15

2.2 材料与方法... 16

2.2.1 研究区域及站位... 16

2.2.2 表层水体样品采集... 16

2.2.3 样品处理... 18

2.2.4 气象观测... 20

2.2.5 质量控制和质量保证... 20

2.2.6 数据统计及分析... 21

2.3 结果... 21

2.3.1 500 μm BONGO-NET 水平拖网结果... 21

2.3.2 300 μm BONGO-NET 水平拖网结果... 27

2.4 讨论... 32

2.4.1 微塑料的数量和特征... 32

2.4.2   表层海水中微塑料的季节变动... 35

2.5 本章小结... 37

第3章 胶州湾桡足类浮游动物体内微塑料数量与特征的季节变化... 39

3.1  前言... 39

3.2 材料与方法... 40

3.2.1  研究站位与采样方法... 40

3.2.2  桡足类体内微塑料的分离... 40

3.2.3  微塑料分析... 41

3.2.4  污染控制... 41

3.2.5  海洋环境因子的观测... 41

3.2.6  数据分析... 41

3.3 结果与分析... 42

3.3.1  胶州湾桡足类个体微塑料数量的季节变化... 42

3.3.2  胶州湾桡足类体内微塑料的形态特征... 43

3.3.3  胶州湾桡足类体内微塑料的大小组成... 44

3.3.4  胶州湾桡足类体内微塑料的化学成分... 46

3.4 讨论... 47

3.4.1  胶州湾桡足类个体微塑料数量及其与其他海域的比较... 47

3.4.2  胶州湾桡足类体内微塑料的形态特征... 48

3.4.3  胶州湾桡足类体内微塑料的季节变化与关键影响因子... 50

3.5 本章小结... 51

第4章 胶州湾毛颚类浮游动物体内微塑料数量与特征的季节变化... 53

4.1 前言... 53

4.2 材料与方法... 54

4.2.1 研究站位与采样方法... 54

4.2.2 毛颚类体内微塑料的分离... 54

4.2.3 桡足类摄食微塑料对海洋生态系统的潜在影响... 55

4.2.4 微塑料分析... 56

4.2.5 污染控制... 56

4.2.6 海洋环境因子的观测... 56

4.2.7 数据分析... 56

4.3 结果... 56

4.3.1 胶州湾毛颚类个体微塑料数量的季节变化... 56

4.3.2 胶州湾毛颚类体内微塑料的形态特征... 58

4.3.3 胶州湾毛颚类体内微塑料的大小... 59

4.3.4 胶州湾毛颚类体内微塑料的化学成分... 61

4.4 讨论... 62

4.4.1 胶州湾毛颚类与桡足类浮游动物体内微塑料数量与特征的比较... 62

4.4.2 不同海域间毛颚类个体微塑料数量与特征的比较... 63

4.4.3 胶州湾毛颚类体内微塑料的季节变化及其与环境因子关系分析... 65

4.4.4 毛颚类在微塑料沿食物链传递中的作用探讨... 66

4.5 本章小结... 67

第5章 胶州湾浮游动物群落微塑料的赋存量与季节变化... 69

5.1 前言... 69

5.2 材料与方法... 70

5.2.1 研究站位与采样方法... 70

5.2.2 浮游动物类群与丰度分析... 70

5.2.3 浮游动物体内微塑料的分离... 70

5.2.4 浮游动物体内微塑料分析... 71

5.2.5 污染控制... 72

5.2.6 数据分析... 72

5.3 结果... 72

5.3.1 胶州湾不同季节浮游动物的组成与丰度... 72

5.3.2 浮游动物群落中微塑料的特征... 73

5.3.3 四个季节浮游动物群落微塑料赋存量估算... 78

5.4 讨论... 78

5.4.1 胶州湾浮游动物体内的微塑料数量及摄食情况... 78

5.4.2 胶州湾浮游动物中的微塑料数量及特征... 82

5.4.3 微塑料在浮游动物群落中的赋存量及意义... 83

5.5 本章小结... 85

第6章 结论与展望... 87

6.1 主要结论... 87

6.2 创新点... 87

6.3 不足与展望... 88

6.3.1 本论文的不足之处... 88

6.3.2 展望... 88

参考文献... 89

致  谢... 107

作者简历及攻读学位期间发表的学术论文与其他相关学术成果... 109