Microplastics in the first-year sea ice of the Novik Bay, Sea of Japan

Sea ice is heavily contaminated with microplastics particles (MPs, <5 mm). First-year sea ice cores (38–41 cm thick) were taken in the beginning of spring in a narrow populated bay of the Sea of Japan. Two ice cores were examined (layer-by-layer, excluding surface) for MPs content: one using μ-FTIR for 25–300 μm (SMPs), and another one – with visual+Raman identification for 300–5000 μm particles (LMPs). The integral (25–5000 μm) bulk mean abundance of MPs was found to be 428 items/L of meltwater, with fibers making 19 % in SMPs size range and 59 % in LMPs. Integral mean mass of MPs was estimated in 34.6 mg/L, with 99.6 % contribution from fragments of LMPs. Comparison with simple fragmentation models confirms deficit of SMPs (especially of fibers in size range 150–300 μm), suggested to result from their leakage with brine. Multivariate statistical analysis indicates strong positive correlation of large fiber (>300 μm) counts and ice salinity.