Poleward decrease in the isotope effect of nitrate assimilation across the Southern Ocean

Recent studies provide seasonally and spatially resolved information on the isotopic characteristics of nitrate supply and N cycling in Southern Ocean surface waters. The new data improve our understanding of the nitrate supply to the Antarctic surface and its isotopic characteristics, especially wi...

Full description

Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: DiFiore, PJ, Sigman, DM, Karsh, K, Trull, T, Dunbar, RB, Robinson, RS
Format: Article in Journal/Newspaper
Language:English
Published: Amer Geophysical Union 2010
Subjects:
Earth Sciences
Oceanography
Chemical Oceanography
Antarctic
Southern Ocean
The Antarctic
Antarc*
Online Access:https://doi.org/10.1029/2010GL044090
http://ecite.utas.edu.au/70487
Description
Summary:Recent studies provide seasonally and spatially resolved information on the isotopic characteristics of nitrate supply and N cycling in Southern Ocean surface waters. The new data improve our understanding of the nitrate supply to the Antarctic surface and its isotopic characteristics, especially with regard to the summertime subsurface minimum temperature (T min ) layer in the Antarctic. We use these findings to update and compile estimates of the N isotope effect of nitrate assimilation, ε, in the Southern Ocean near Australia. A poleward decrease in ε emerges, from 8-9‰ in the Subantarctic Zone (SAZ, 40-52°S) to similar to 5‰ in the Polar Antarctic Zone (PAZ, ~66°S). ε is strongly correlated with mixed layer depth at the time of sampling. We hypothesize that the correlation is driven by the physiological response of diatoms to light availability, with light limitation leading to higher cellular efflux of nitrate and thus higher ε.

Similar Items