Identification and quantification of microplastics in the Antarctic coastal waters using laser direct infrared (LDIR)

Microplastics (MPs) are widespread marine pollutants, even in remote environments like Antarctica. Most regional studies have focused on particles >300 μm, leaving smaller MPs largely unexamined. This study was the first to assess MPs down to 20 μm in surface waters near an Antarctic research station, extending the size range covered in previous Antarctic surveys (e.g., Cincinelli et al., 2017; Lacerda et al., 2019). Eighteen surface water samples were collected near Carlini Station (25 de Mayo/King George Island), with MPs detected in all cases. Samples were analyzed using Laser Direct Infrared (LDIR) spectroscopy, a high-throughput method combining automated particle detection with precise chemical identification, enabling size-resolved quantification without subsampling. The median abundance was 17.4 MP L, a value comparable to or exceeding levels in more populated coastal areas globally. Notably, 53.0 % of all particles were in the 20-50 μm range, underscoring the importance of including smaller MPs in future assessments. Polyamide, polyethylene terephthalate, and polyurethane dominated the polymer composition (73.8 %), commonly associated with textiles, packaging and industrial uses. While temporal variability was observed, no significant spatial differences were found between the 6 stations or between inside and outside Potter Cove (3 stations each), possibly reflecting hydrodynamic mixing and wind-driven resuspension. MP composition remained consistent across sites and aligned with prior studies, suggesting persistent local inputs. These findings offer critical baseline data for environmental monitoring and management. Such data could inform updates to environmental management plans under the Madrid Protocol, especially regarding waste handling and discharge practices at polar research stations.