Atmospheric samples and surface seawater collected on a Chinese Antarctic Research Expedition (CHINARE) transect are used to investigate sources and production of nitrate (${\mathrm{NO}}_3^{-}$) in the atmosphere and its contribution to the surface ${\mathrm{NO}}_3^{-}$ pool in the ocean. Most atmospheric ${\mathrm{NO}}_3^{-}$ is concentrated on intermediate size particles, and much higher concentrations were observed in the northern hemisphere than in the high southern latitudes. Isotopes of ${\mathrm{NO}}_3^{-}$ (${\delta }^{15}\mathrm{N}$, ${\delta }^{18}\mathrm{O}$ and ${\mathrm{\Delta }}^{17}\mathrm{O}$) suggest that elevated atmospheric ${\mathrm{NO}}_3^{-}$ in coastal areas was associated with human activities, while ${\mathrm{NO}}_3^{-}$ in the high southern latitudes tends to be influenced by precursor Antarctic snowpack emissions driven by photolysis. In general, no clear association was found between the isotopes of surface seawater and atmospheric ${\mathrm{NO}}_3^{-}$, suggesting that the ocean is unlikely to be an important direct source of atmospheric NO_x on this transect. A significant linear relationship between ${\delta }^{18}\mathrm{O}$ and ${\mathrm{\Delta }}^{17}\mathrm{O}$ of ${\mathrm{NO}}_3^{-}$ is used to interpret important pathways for ${\mathrm{NO}}_3^{-}$ production. In the tropics, >59% of atmospheric ${\mathrm{NO}}_3^{-}$ is produced via OH oxidation of NO₂, while the elevated oxygen isotopic ratios (${\delta }^{18}\mathrm{O}$ and ${\mathrm{\Delta }}^{17}\mathrm{O}$) in the high southern latitudes suggest increased ${\mathrm{NO}}_3^{-}$ production via BrO and/or DMS pathways assuming a minor contribution of the N₂O₅ channel. In surface seawater, high ${\mathrm{NO}}_3^{-}$ concentrations are present in the coastal areas and in the Southern Ocean. In coastal areas of China, positive ${\mathrm{\Delta }}^{17}\mathrm{O}$ values in seawater ${\mathrm{NO}}_3^{-}$ (1.7 ± 1.0‰) provide direct evidence of uncycled atmospheric deposition contribution, with a calculated contribution of at least 2-3% to total surface ${\mathrm{NO}}_3^{-}$. A ${\mathrm{\Delta }}^{17}\mathrm{O}=0$ was found everywhere else in seawater, suggesting that atmospheric deposition has a minimal presence in the surface ${\mathrm{NO}}_3^{-}$ pool. Near Antarctica, deposition of atmospheric ${\mathrm{NO}}_3^{-}$ with extremely low ${\delta }^{15}\mathrm{N}$ ($<-30\mathrm{‰}$) could lower ${\delta }^{15}\mathrm{N}$ found in sea ice, and this process could be isotopically important to evaluate nitrogen cycling in sea ice.