Environmental Distribution of Styrene Oligomers (SOs) Coupled with Their Source Characteristics: Tracing the Origin of SOs in the Environment

• Published in: Journal of hazardous materials 2020-11, Vol.398, p.122968-122968, Article 122968
• Main Authors: Tian, Zhexi, Kim, Seung-Kyu, Hyun, Jung-Ho
• Format: Article
• Language: English
• Subjects: Expanded polystyrene; Leaching; Plastic debris; Source identification index; Styrene oligomers
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.122968

[Display omitted] •Environmental dilution and source effects on SOs distribution was studied.•∼0.1% styrene oligomer (SO) content in EPS buoy particles with a predominance of STs.•EPS leachate showed much faster leaching of SDs, mostly SD-2.•Decrease in concentration and change in composition of SOs with distance was found.•Ratio of ST-1 to SD-2 was suggested as an index to characterize SOs in the field. Despite growing concerns regarding plastic additives, their environmental fate coupled with leaching from source materials are not well known. Styrene oligomers (SOs), which are unintended additives in expanded polystyrene (EPS), are estrogenic micropollutants. Here, we identified the effects of their potential sources (i.e., EPS buoy and its leachate) and environmental dilution on SO distribution within coastal sediments. SO content in fresh EPS particles was 0.1% (w/w), dominated by 2,4,6-triphenyl-hexene (ST-1), while 2,4-diphenyl-1-butene (SD-2) accounted for most of the SOs in EPS leachate, indicating its faster leachability. In lake and offshore environments, the SO composition profiles from their terrestrial inputs and inner sites were similar to those of EPS leachate; meanwhile, the exponentially decreasing SO concentration and increasing styrene trimers (STs) fraction with distance from the inner to outer sites were evident. These profiles indicated continuous SO leaching from their potential sources in the inland, followed by a change in SOs due to environmental dilution. SOs in beach sediment implied the presence of micro-sized EPS particles. We suggest the ST-1 to SD-2 ratio as an index to differentiate among freshly leached SOs (∼0.02), environmentally diluted SOs after leaching (∼0.1), SOs in fresh EPS (∼1.2), and SOs in aged EPS (> 2).