Korea Institute of Ocean Science and Technology, Geoje-shi 53201, South Korea.
Korea Institute of Ocean Science and Technology, Geoje-shi 53201, South Korea; University of Science and Technology, Daejeon 34113, South Korea.
Environ Pollut. 2022 Oct 15;311:119847. doi: 10.1016/j.envpol.2022.119847. Epub 2022 Aug 12.
The plastic debris that washes ashore and litters the shoreline often undergoes weathering under sunlight exposure, such that it fragments to form nanoplastics and microplastics, but the fragmentation rate for many thermoplastics is unknown. In this study, three major thermoplastics were exposed to simulated sunlight in an accelerated weathering chamber to evaluate the speed of photooxidation-induced fragmentation. The initiation of photooxidation-induced fragmentation extrapolated from the accelerated weathering chamber to real sunlight exposure in South Korea followed the order of PS (< 1 year) > PP (< 2 years) > LDPE (> 3 years). The surface cracks created by photooxidation were not directly reflected in the initiation of fragmentation of thermoplastics. The initiation of fragmentation was faster in PS than other polymers, but the total abundance of particles produced, and increasing ratio (exposure/non-exposure) were comparable or lower than those of PP. The increasing ratio pattern between nanoplastics and small microplastics of PP differed noticeably from other polymers. The initiation of nanoplastic and small-microplastic fragmentation determined in this study will be useful for the further estimation of secondary microplastic production by weathering and thus for decision-making regarding methods for the timely removal of plastic litter in the environment.
海滩上的塑料碎片和垃圾经常在阳光照射下经历风化，从而碎裂成纳米塑料和微塑料，但许多热塑性塑料的碎裂速度是未知的。在这项研究中，三种主要的热塑性塑料在加速风化室中暴露于模拟阳光下，以评估光氧化诱导碎裂的速度。从加速风化室到韩国真实阳光暴露的光氧化诱导碎裂起始时间的顺序为 PS（<1 年）> PP（<2 年）> LDPE（>3 年）。光氧化产生的表面裂纹并没有直接反映在热塑性塑料碎裂的起始上。PS 比其他聚合物的碎裂起始更快，但产生的颗粒总量和增加比例（暴露/非暴露）与 PP 相当或更低。PP 中小微塑料纳米塑料和小型微塑料碎片的增加比例模式与其他聚合物明显不同。本研究中确定的纳米塑料和小型微塑料碎裂的起始时间将有助于进一步估计风化引起的次生微塑料的产生，从而为及时清除环境中的塑料垃圾的方法做出决策。
