Critical raw material concentrations in the Antarctic Peninsula and recalibration of the potential ecological risk index for polar regions

Critical raw materials (CRMs) are emerging inorganic pollutants because of their technological use and release into remote marine environments. However, their occurrence, distribution, and ecological significance in Antarctic waters remain poorly understood, and existing risk indices have not been adapted for CRMs in these systems. This study investigated selected CRMs in surface waters collected from 21 stations across the Antarctic Peninsula and Horseshoe Island during three consecutive Turkish Antarctic Expeditions (2023-2025). Trace and ultra-trace concentrations were measured by inductively coupled plasma mass spectrometry under contamination-controlled conditions. CRM distributions were heterogeneous: B, Ga, Li, Nd, and Ti were detected at all stations; Ce, Gd, Ge, La, Pd, and Pt remained below detection limits; and Y exhibited a more localised abundance. To complement concentration-based analysis, normalised contamination indices were integrated with CRM-specific response coefficients in a recalibrated potential ecological risk index (r-PERI) adapted to Antarctic surface waters. The r-PERI values ranged from 35 to 104 across years and stations, indicating very low-to-low relative ecological prioritisation. By integrating element-specific occurrence, release-related weighting, and experimentally informed toxicity responses, r-PERI provides a structured approach to comparing the relative ecological significance of CRMs under data-limited polar conditions. Because the toxicity coefficients are experimental and the normalisation baseline is internal to this dataset, r-PERI should be interpreted as a screening-level, dataset-specific prioritisation rather than a definitive ecological-hazard assessment. This study establishes the first multi-year baseline for CRM occurrence in Antarctic Peninsula surface waters and introduces an r-PERI approach for future assessments in vulnerable polar marine ecosystems.