Spatial variability of δ18O and δ2H in North Pacific and Arctic Oceans surface seawater

This study presents new observations of stable isotopic composition (δ18O, δ2H and deuterium excess) in surface waters of the North Pacific and Arctic Oceans that were collected during the sixth Chinese National Arctic Research Expedition (CHINARE) from mid-summer to early autumn 2014. Seawater δ18O and δ2H decrease with increasing latitudes from 39°N to 75°N, likely a result of spatial variability in evaporation/precipitation processes. This explanation is further confirmed by comparing the δ18O–δ2H relationship of seawater with that of precipitation. However, effects of freshwater inputs on seawater stable isotopic composition are also identified at 30°N–39°N. Furthermore, we find a non-significant relationship between the isotopic parameters (δ2H and δ18O) and salinity from 73°N northwards in the Arctic Ocean, implying that sea ice melting/formation may have some effect. These results suggest that the isotopic parameters δ2H and δ18O are useful for tracing marine hydrological processes.