Production mechanism and global budget of N₂O inferred from its isotopomers in the western North Pacific

We measured the intramolecular distribution of 15 N as well as conventional nitrogen and oxygen isotope ratios in oceanic nitrous oxide (N 2 O) in the western North Pacific for the first time. In contrast to a nearly homogeneous vertical distribution of a bulk nitrogen isotope ratio, a wide variation in site preference for intramolecular 15 N distribution was found, suggesting the subsurface and deep source mixing and the production mechanism in the ocean. The oceanic composition of N 2 O isotopomers quantitatively outlines the ocean as the most significant source after the terrestrial one.