Salinity, oxygen isotope, hydrogen isotope, and radiocarbon of coastal seawater of North Japan

To understand seawater properties, such as water mass structure and mixing, geochemical analyses are useful. However, geochemical datasets for seawater that fully cover coastal areas of Hokkaido, North Japan are lacking. Here we report comprehensive geochemical analyses of seawater (salinity, delta O-18, delta D, and Delta C-14) collected in August-September 2021 from coastal areas of Hokkaido as well as the west coast of Tohoku (Northeast Japan). These datasets are expected to improve our understanding of seawater properties around Hokkaido, thereby contributing to oceanography, climatology, biogeochemical cycles, and fishery science.