Water column nitrate plus nitrite d15N measurements from seawater collected in November 2019 and November 2020 in the Western Tropical South Pacific

Here we present nitrate plus nitrite isotopic data from the TONGA research cruises to the Western Tropical South Pacific in 2019 and a reoccupation in 2020. 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. While subsurface nitrate plus nitrite isotopes were low higher, 4 to 7 per mil, at stations further from the vents.