Tracing Microplastics in Remote Iceland’s Glaciers: A Case Study of Vatnajökull Ice Cap and Mýrdalsjökull Glacier

Abstract

The pervasive accumulation of microplastics (MPs) within the cryosphere represents a significant environmental challenge, yet their occurrence in remote cryospheric environments remains poorly constrained. This study investigates the abundance, size distribution, and polymer composition of microplastics preserved in glacier ice from two Icelandic glaciers, the Vatnajökull ice cap (at Eyjabakkajökull; core E04-02) and Mýrdalsjökull (Black Yellow and Myr Low cores), utilizing high-resolution μ-Raman spectroscopy to provide a detailed baseline of anthropogenic pollution. A rigorous analytical protocol was implemented, including 10% KOH digestion, oil-water separation, and strict blank-correction procedures to ensure data integrity. Microplastics were identified across all glacier samples within the ≥20 μm to ≥1 mm size range. Concentrations were highest in the smallest fraction (20–100 μm), particularly at Vatnajökull (E04-02), where levels reached 988.33 MP/L. At Mýrdalsjökull, the Black Yellow core showed a peak concentration of 76.78 MP/L in the 20–100 μm range, while the Myr Low core exhibited elevated counts of up to 133.33 MP/L in the coarser fraction (≥1 mm). In terms of total abundance, the Vatnajökull E04-02 section recorded approximately 1,028.19 MP/L during the spring of 2021. During the same period, the Mýrdalsjökull Black Yellow sample yielded a total of 102.63 MP/L, while the Myr Low core representing the period from summer 2020 through winter 2021, showed a concentration of 166.67 MP/L. Across all samples, uncategorized polymers (Ethyl cellulose, Methyl cellulose etc), were most abundant, followed by polypropylene (PP), polyvinyl chloride (PVC), and polyurethane (PU), suggesting both diverse sources and weathering-related spectral alteration. Microplastics were also present in blank controls, underscoring the necessity of contamination assessment during processing. Methodological validation highlighted that current optical detection limits (≥20 μm) and spectral range constraints (100–4000 cm ⁻¹) likely lead to an underestimation of the total particle load, particularly regarding Very small microplastics. These findings demonstrate that even remote Icelandic glaciers accumulate microplastics, with the dominance of particles <100 μm indicating likely atmospheric transport and deposition. The presence of MPs in archived ice implies long term storage within the cryosphere and potential downstream release under continued glacier melt. This study provides critical evidence for the necessity of long-term monitoring and atmospheric back-trajectory modeling to better understand the transboundary movement of plastic pollutants in the North Atlantic region.