The whole core squeezing method was used to simultaneously obtain profiles of nitrous oxide (N
2O), nitrogenous nutrients, and dissolved oxygen in sediments of Koaziro Bay, Japan (coastal water), the East China Sea (marginal sea), and the central Pacific Ocean (open ocean). In the spring of Koaziro Bay, subsurface peaks of interstitial N
2O (0.5–3.5 cm depth) were observed, at which concentrations were higher than in the overlying water. This was also true for nitrate (NO
3−) and nitrite (NO
2−) profiles, suggesting that the transport of oxic overlying water to the depth through faunal burrows induced in situ N
2O production depending on nitrification. In the summer of Koaziro Bay, sediment concentrations of N
2O, NO
3− and NO
2− were lower than in the overlying water. In most East China Sea sediments, both N
2O and NO
3− decreased sharply in the top 0.5–2 cm oxic layer (oxygen: 15–130
μM), which may have indicated N
2O and NO
3− consumption by denitrification at anoxic microsites. N
2O peaks at subsurface depth (0.5–6.5 cm) implied in situ production of N
2O and/or its supply from the overlying water through faunal burrows. However, the occurrence of the latter process was not confirmed by the profiles of other constituents. In the central Pacific Ocean, the accumulation of N
2O and NO
3− in the sediments likely resulted from nitrification. Nitrous oxide fluxes from the sediments, calculated using its gradient at the sediment–water interface and the molecular diffusion coefficient, were −45 to 6.9 nmolN m
−2 h
−1 in Koaziro Bay in the spring, −29 to −21 nmolN m
−2 h
−1 in the summer, −46 to 37 nmolN m
−2 h
−1 in the East China Sea, 0.17 to 0.23 nmolN m
−2 h
−1 in the equatorial Pacific, and <±0.2 nmolN m
−2 h
−1 in the subtropical North Pacific, respectively.
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