Concentration of Hydroxylamine in the water column during Meteor cruise M90. Hydroxylamine was measured as N2O after chemical conversion to N2O by addition of Fe(III). N2O concentrations from hydroxylamine conversion (after subtraction of background N2O) is provided as separate column. The conversion efficiency (recovery factor) was determined for each station by standard addition at one sampling depth. Corresponding background N2O concentrations are available at: https://doi.org/10.1594/PANGAEA.857760.