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Intensifying agricultural production and coastal urbanization are increasing nitrogen (N) loads to estuaries, potentially increasing emissions of the greenhouse gas nitrous oxide (N₂O). Here we present a first assessment of how changes in land use intensity affect estuarine N₂O fluxes. We measured N₂O concentrations over marine‐freshwater transects in the wet and dry seasons in eight subtropical estuaries selected for differences in land use intensity. Daily estuary N loads ranged from 0.5 ± 0.4 kg N km⁻² d⁻¹ (minimally impacted) to 51 ± 30 kg N km⁻² d⁻¹ (highly impacted), corresponding to higher concentrations of all inorganic N species (nitrate, ammonium, and N₂O) in the highly impacted estuaries. Net N₂O fluxes from the eight estuaries ranged from −20 μg N₂O‐N m⁻² d⁻¹ (sink) to +300 μg N₂O‐N m⁻² d⁻¹ (source). However, neither N concentrations nor N loads explained the variations in N₂O fluxes …