Water column nitrate plus nitrite isotope measurements from seawater collected November 2019 aboard R/V L’Atalante in the Western Tropical South Pacific.

Here we present nitrate plus nitrite isotopic data from the TONGA 2019 research cruise to the Western Tropical South Pacific. These data were collected along a transect focusing on the impacts on biological productivity and the biological carbon pump from shallow hydrothermal sources of trace elements. Notably, these data show that the subsurface nitrate plus nitrite isotopes were low, 2 to 3 per mil, in the vicinity of the hydrothermal vents. Subsurface nitrate plus nitrite isotopes were higher, 4 to 7 per mil, at stations further from the vents.