Hyunook Kim

Microplastic source attribution remains a major challenge because conventional analytical techniques primarily identify polymer types while providing limited information on the origin and environmental history of plastic materials. This study evaluates the potential and limitations of stable carbon isotope analysis (δ¹³C) for tracing common plastic polymers at the global scale. A total of 460 commercial plastic samples, including 233 polyethylene terephthalate (PET) bottles and 227 polyethylene (PE) caps, were collected from 59 countries across six continents and analysed by Elemental Analyzer - Isotope Ratio Mass Spectrometry (EA-IRMS). A preliminary thermal additive removal experiment showed systematic but minor isotopic shifts (~0.3‰ for PET and ~0.5‰ for PE), indicating a minor influence of additives on bulk δ¹³C values. Across all samples, PE exhibited a broad δ¹³C range from -35.2 ‰ to -24.0 ‰, with significant interregional variability and country-averaged values ranging from -33.88 ± 0.02‰ (Tunisia) to -25.93 ± 0.07‰ (New Zealand). Continental-scale comparisons revealed significant differences between several regions, consistent with regional differences in petrochemical feedstocks and production pathways. In contrast, PET displayed a narrower δ¹³C range (-33.1‰ to -26.2‰) and no significant interregional differences, consistent with a more homogeneous and globally integrated production system. Overall, the results demonstrate that stable carbon isotopes provide useful first-order constraints on broad PE source domains, while also highlighting important limitations related to overlapping isotopic domains and the globalization of polymer supply chains. Stable isotope analysis therefore represents a promising complementary tool for improving microplastic source attribution within multi-tracer environmental forensic frameworks.

Atmospheric wet deposition is a critical scavenger of microplastics (MPs); yet, its contribution to urban hydrologic cycles remains under-quantified. In this study, we investigated the MP characteristics and flux in rainfall across 21 events in Seoul, South Korea, utilizing a cascade filtration protocol coupled with dual-spectroscopy (Fourier Transform-Infrared for ≥20 µm and Raman Spectroscopy for 5–20 µm). Results revealed an average MP abundance of 197 MPs L-1 with a dominance of fragments (> 96%). A critical "mass-count paradox" was observed: while fine particles (< 50 µm) were numerically dominant, larger particles (> 50 µm) accounted for approximately 90% of the total mass. Polymer composition also exhibited size-dependence, with brittle polymers (polystyrene and polyethylene terephthalate) prevalent in the finer fraction detected by Raman, whereas polypropylene and polyethylene dominated the larger fraction. The Conditional Fragmentation Model showed a fragmentation exponent (α) of approximately 1.08, characterizing the particles as an extensively weathered “aged atmospheric pool”. Furthermore, a strong correlation (r = 0.87) between MP flux and Antecedent Dry Days confirmed a "first-flush" mechanism, whereas meteorological analysis identified inertial impaction as the dominant scavenging driver (r = 0.97 with rainfall depth). Box model simulations demonstrated that although wet deposition contributes a minor fraction (1.8%–8.8%) of the annual load, it generates acute "shock loading" during storm events, accounting for up to 81% of the total influx. The findings underscore the necessity of integrating atmospheric deposition into urban water quality management strategies.

It is expected that about 600-GT CO2 is expected to be emitted by the industrial sector for the next 50 years. In order to achieve the goal to reduce the industrial CO2 emission by 75%, an innovative carbon capture and utilization technology should be urgently developed and implemented. From 2050, all the flights taking off from any airport in the Europe should be fueled with jet-oils more than 70% of which should be sustainable aviation fuel (SAF). By the same year, all the petrol-based jet-fuel consumed in the US will be replaced with SAF. Therefore, 190 private companies located in 330 cities, 73% of which are in the EU or the US, are planning to produce SAF. As one of the most important jet-fuel providers in the world, Korea is finding a stable biomass source for producing SAF. Growing algae for oil extraction has attracted interest from engineers, since its lipid content is 40-60%. If CO2 is supplemented to the algae-growing farm, a higher yield is expected. Moreover, CO2 is supplied to the farm as HCO3-, the yield can double. In this presentation, an innovative and economical strategy to produce SAF via utilizing CO2 from industry will be presented. The feasibility of the strategy will evaluated in a holistic way.