Sources of oceanic freshwater content along the western Antarctic Peninsula (PAL-LTER Study Region) determined by the stable isotope composition (d18O) of seawater.

• Main Authors: LTER, Palmer Station Antarctica, Ducklow, Hugh, Meredith, Micheal
• Format: Dataset
• Language: English
• Published: Environmental Data Initiative 2019
• Subjects: Antarctic; Antarctic Peninsula; Meredith; The Antarctic; Antarc*; Sea ice
• Online Access: https://dx.doi.org/10.6073/pasta/a3e66702fe0ea704af82a813dbfa5b74; https://portal.edirepository.org/nis/mapbrowse?packageid=knb-lter-pal.278.1

The oceanic distribution of d18O is determined largely by the same processes that control salinity. Surface d18O reflects the magnitude and spatial distribution of freshwater inputs, and it is a conservative tracer in the ocean interior. The great benefit of d18O is obtained from the circumstances under which it exhibits behavior different to that of salinity. One such circumstance derives from the salinity and d18O values in precipitation, with salinity being constant with latitude (typically zero), while in general d18O in precipitation becomes progressively isotopically lighter toward the poles. This results in glacial ice (which derives from high-latitude precipitation) being very isotopically light, enabling d18O to be a useful tracer of glacial discharge to the ocean (e.g., Schlosser et al. 1990; Weiss et al. 1979). Another difference occurs in regions influenced by sea ice, which greatly affects salinity during its formation/melt cycle but has only minimal impact on d18O. This decoupling of the two tracers allows them to be used in tandem to quantitatively separate freshwater inputs from sea ice melt and those from meteoric sources (precipitation plus glacial discharge). For this, a simple three-endmember mass balance can be used. For details please see Meredith, M. P., H. J. Venables, A. Clarke, H. W. Ducklow, M. Erickson, M. J. Leng, J. T. M. Lenaerts, and M. R. van den Broeke. 2013. The freshwater system west of the Antarctic Peninsula: Spatial and temporal changes. Journal of Climate 26:1669-1684.