Crack Patterns of Environmental Plastic Fragments

作者：Deng, Hua; Su, Lei; Zheng, Yifan; Du, Fangni; Liu, Quan-Xing; Zheng, Jia; Zhou, Zhiwei; Shi, Huahong^*

来源：Environmental Science and Technology, 2022, 56(10): 6399-6414.

DOI：10.1021/acs.est.1c08100?

• weathering
• microplastic
• ragmentation
• environmental stress
• line density

:secondary microplastics usually come from the breakdown of larger plastics dueto weathering and environmental stress cracking of plastic wastes. In the present study, 5013plastic fragments were collected from coastal beaches, estuary dikes, and lake banks in China.The fragment sizes ranged from 0.2 to 17.1 cm, and the dominant polymers were polypropyleneand polyethylene. Cracks were observed on the surfaces of 49-56% of the fragments. Based onthe extracted crack images, we proposed a general crack pattern system including four cracktypes with specificdefinitions, abbreviations, and symbols. The two-dimensional spectralanalysis of the cracks suggests that thefirst three patterns showed good regularity and supportedthe rationality of the pattern system. Some crack metrics (e.g., line density) were closelycorrelated with the carbonyl index and additives (e.g., phthalate esters) of fragments. For crackinvestigation infield, we proposed a succinct protocol, in whichfive crack ranks were established to directly characterize the degreeof cracking based on the line density values. The system was successfully applied to distinguish the differences in crack features attwo representative sites, which indicates that crack pattern is a useful tool to describe the morphological changes of plastic surfaces inthe environment