TY - JOUR
T1 - Poleward decrease in the isotope effect of nitrate assimilation across the Southern Ocean
AU - Difiore, Peter J.
AU - Sigman, Daniel Mikhail
AU - Karsh, Kristen L.
AU - Trull, Thomas W.
AU - Dunbar, Robert B.
AU - Robinson, Rebecca S.
PY - 2010/9/1
Y1 - 2010/9/1
N2 - 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 (Tmin) 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, 40-52S) to ∼5‰ in the Polar Antarctic Zone (PAZ, ∼66S). 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.
AB - 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 (Tmin) 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, 40-52S) to ∼5‰ in the Polar Antarctic Zone (PAZ, ∼66S). 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.
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U2 - 10.1029/2010GL044090
DO - 10.1029/2010GL044090
M3 - Article
AN - SCOPUS:77956431099
SN - 0094-8276
VL - 37
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 17
M1 - L17601
ER -