Data for "Contrasting associations of sea-ice meltwater and meteoric water with nitrogen uptake patterns in the summer Cosmonaut Sea, Antarctica"

Here, ¹⁵N tracer incubations and a <i>δ</i>¹⁸O-salinity mixing model were combined to examine nitrogen uptake in the early-summer Cosmonaut Sea. Depth-integrated nitrate (<i>ρ</i>NO₃) and ammonium uptake (<i>ρ</i>NH₄) rates averaged 8.0 and 1.3 mmol m^‑2 d^-1, respectively, yielding a mean <i>f</i>-ratio of 0.80.

Meteoric water (MW) fractions were positively correlated with chlorophyll <i>a</i> (Chl-a) concentration, the micro-sized (>20 μm) Chl-<i>a</i> fraction, and <i>ρ</i>NO₃, suggesting that MW-influenced waters were associated with higher biomass, larger size structure, and enhanced nitrate uptake. Sea-ice meltwater (SIM) fractions were positively correlated with ambient NH₄⁺ and <i>ρ</i>NH₄, consistent with greater regenerated nitrogen availability following sea-ice retreat and post-bloom recycling.