Fig. 2

Measurements of physicochemical parameters along a hydrographic section over the southern Chukchi Sea. a Map of sampling stations (red arrow in the panel represents the orientation of the section). b, c Hydrographic parameters, temperature (T) and salinity (S), respectively. d Dissolved O₂ concentrations (in μmol L⁻¹). e–g Concentrations of N species, \({\text{NO}}_{3}{^{ - }}\), \({\text{NO}}_{2}{^{ - }}\) and \({\text{NH}}_{4}{^{ + }}\), respectively (all in μmol L⁻¹). h Excess N (N *, calculated as \({\text{NO}}_{3}{^{ -}}\) + \({\text{NO}}_{2}{^{ -}}\) + \({\text{NH}}_{4}{^{ + }}\) − 16 × \({\text{PO}}_{4}{^{3 - }}\) + 2.9, in μmol L⁻¹)