Plain language summary
Multi-year landfast sea ice (fast ice) is abundant around the coast of
Antarctica. Fast ice is an important component of Antarctic coastal
marine ecosystems, providing a prolific habitat for ice algal
communities. Although nutrients are essential for biological
productivity within sea ice, the status of nutrients and processes
affecting nutrient concentrations were previously not known for
multi-year fast ice. Here, we collected sea-ice cores from multi-year
fast ice in Lützow-Holm Bay, East Antarctica, and we analyzed nutrient
concentrations using physical and biogeochemical parameters. Nutrient
concentrations in the upper parts of the sea ice decreased due to the
accumulation of clean (nutrient-free) snow through melting and
refreezing processes, contributing to upward ice growth. In deeper parts
of the sea ice, nutrient concentrations were greatly affected by
biological processes such as remineralization during the degradation of
organic matter within sea ice.