Origins and Biological Accumulation of Small Plastic Particles in Fur Seals From Macquarie Island

From the abstract of the referenced paper:

One hundred and sixty four plastic particles (mean length 4.1 mm) recovered from the scats of fur seals (Arctocephalus spp.) on Macquarie Island were examined.

Electron micrographs of 41 of the plastic particles showed that none could be identified as plastic pellet feedstock from their shapes. Commonly, such pellets are cylindrical and spherical. Instead, all the 164 plastic particles from the seal scats were angular particles of 7 colors (feedstock particles are normally opaque or white) and could be classified into 2 categories: i) fragmented along crystal lines and likely to be the result of UV breakdown; and ii) worn by abrasion (where striations were clearly visible) into irregular shapes with rounded corners. White, brown, green, yellow and blue were the most common colors. In composition, they came from 5 polymer groups; polyethylene 93%, polypropylene 4%, poly(1-Cl-1-butenylene) polychloroprene 2%, melamine-urea (phenol) (formaldehyde) resin 0.5%, and cellulose (rope fiber) 0.5%. The larger groups are buoyant with a specific gravity less than that of seawater. These small plastic particles are formed from the breakdown of larger particles (fragments). Their origin seems to be from the breakdown of user plastics washed ashore and ground down on cobbled beaches.

Certainly most particles (70%) had attained their final form by active abrasion. It is hypothesized that the plastic particles were washed out to sea and then selected by size and consumed by individuals of a pelagic fish species, Electrona subaspera, who in turn were consumed by the fur seals. Thus, the particles were accumulated both by the fish and the seals in the usual process of their feeding.

The download file contains a pdf of the paper listed in the reference section below, as well as 48 scanning electron micrograph images of plastics recovered from fur seal scats.

引自所引用论文的摘要：
本研究对麦夸里岛（Macquarie Island）毛皮海狮（Arctocephalus spp.）粪便中采集的164颗塑料颗粒（平均长度4.1mm）开展了检测分析。
对其中41颗塑料颗粒的电子显微图像分析表明，从形态上无法将任意一颗归类为塑料颗粒原料（plastic pellet feedstock）。此类原料颗粒通常呈圆柱状或球状。与之相反，所有取自海狮粪便的164颗塑料颗粒均为棱角状颗粒，涵盖7种颜色（原料颗粒通常为不透明或白色），可分为两类：① 沿晶界碎裂，推测为紫外线降解所致；② 经磨蚀作用（可见清晰条纹痕迹）形成带圆角的不规则形状。其中白色、棕色、绿色、黄色与蓝色为最常见的颜色。从成分组成来看，这些颗粒分属5类聚合物：聚乙烯（polyethylene）占比93%、聚丙烯（polypropylene）占比4%、聚氯丁二烯（poly(1-Cl-1-butenylene) polychloroprene）占比2%、三聚氰胺-尿素（苯酚）甲醛树脂（melamine-urea (phenol) (formaldehyde) resin）占比0.5%，以及纤维素（绳纤维，cellulose (rope fiber)）占比0.5%。其中多数大尺寸颗粒的比重低于海水，具备漂浮性。这类小型塑料颗粒由更大的塑料碎片经降解碎裂形成，其源头大概率为被冲至卵石滩并经磨蚀破碎的废弃塑料制品。
研究表明，70%的颗粒最终形态均由主动磨蚀作用形成。研究人员提出假说：这些塑料颗粒被冲入海洋后，按尺寸被远洋鱼类物种南极灯笼鱼（Electrona subaspera）滤食，随后这些鱼类又被毛皮海狮捕食，因此塑料颗粒通过鱼类与海狮的常规摄食过程在二者体内累积。
本次提供的下载文件包含下文参考文献部分列出的论文PDF，以及48张取自毛皮海狮粪便的塑料颗粒扫描电子显微图像（scanning electron micrograph）。