Tracing ice-to-coast trace metal pathways in Maxwell Bay, Antarctica

Authors: names of authors including presenter Carolina Duarte (presenter), Ines Oliveira, Luca Szepal, Caio Cesar Ribeiro

Affiliations: for each author ECHO - Ecotoxicology and Chemical Oceanography Group, Centre of Marine Sciences (CCMAR), University of Algarve, Faro, Portugal.

Abstract: maximum 250 words. Antarctic coastal waters receive trace metals from overlapping natural and human-related pathways, including glacial melt, freshwater drainage, sediment exchange, animal inputs and research infrastructure. This study integrates 2026 observations from ice-associated, freshwater and coastal habitats on the Fildes Peninsula with historical seawater and regional ice-metal datasets to investigate how metals may be redistributed into Maxwell Bay. The contemporary survey comprised 42 field observations and 20 dated nutrient records, complemented by 38 visual strip observations. Coastal salinity ranged from 14.15 to 28.09, while freshwater habitats remained near zero, highlighting heterogeneous mixing conditions. Water silicate concentrations (58.54-93.55 µmol L⁻¹) greatly exceeded those in ice-derived material (1.76-7.76 µmol L⁻¹), whereas phosphate was generally higher in ice-associated samples. Historical seawater data showed dissolved Fe concentrations of 4.12-10.99 nM, with dissolved Fe representing a median of only 3.64% of total dissolvable Fe and displaying an inverse association with salinity (Spearman ρ = -0.70). Regional ice records further demonstrated substantial heterogeneity in Fe and Mn inventories among catchments. Together, the results show that trace-metal patterns in Maxwell Bay cannot be explained by simple dilution or attributed to a single source. Glacial melt, sediments, animal-mediated recycling and human activities may contribute overlapping signals, emphasizing the need for contemporaneous source, transport and fraction-specific measurements to resolve metal pathways in Antarctic coastal ecosystems.

Keywords: Antarctica; Maxwell Bay; trace metals; glacial melt; biogeochemical pathways; coastal waters