TY  - JOUR
A1  - Ren, Haojia
A1  - Studer, Anja S.
A1  - Serno, Sascha
A1  - Sigman, Daniel M.
A1  - Winckler, Gisela
A1  - Anderson, Robert F.
A1  - Oleynik, Sergey
A1  - Gersonde, Rainer
A1  - Haug, Gerald H.
T1  - Glacial-to-interglacial changes in nitrate supply and consumption in the subarctic North Pacific from microfossil-bound N isotopes at two trophic levels
JF  - Paleoceanography
N2  - Reduced nitrate supply to the subarctic North Pacific (SNP) surface during the last ice age has been inferred from coupled changes in diatom-bound delta N-15 (DB-delta N-15), bulk sedimentary delta N-15, and biogenic fluxes. However, the reliability of bulk sedimentary and DB-delta N-15 has been questioned, and a previously reported delta N-15 minimum during Heinrich Stadial 1 (HS1) has proven difficult to explain. In a core from the western SNP, we report the foraminifera-bound delta N-15 (FB-delta N-15) in Neogloboquadrina pachyderma and Globigerina bulloides, comparing them with DB-delta N-15 in the same core over the past 25 kyr. The delta N-15 of all recorders is higher during the Last Glacial Maximum (LGM) than in the Holocene, indicating more complete nitrate consumption. N. pachyderma FB-delta N-15 is similar to DB-delta N-15 in the Holocene but 2.2% higher during the LGM. This difference suggests a greater sensitivity of FB-delta(15)NZ to changes in summertime nitrate drawdown and delta N-15 rise, consistent with a lag of the foraminifera relative to diatoms in reaching their summertime production peak in this highly seasonal environment. Unlike DB-delta N-15, FB-delta N-15 does not decrease from the LGM into HS1, which supports a previous suggestion that the HS1 DB-delta N-15 minimum is due to contamination by sponge spicules. FB-delta N-15 drops in the latter half of the Bolling/Allerod warm period and rises briefly in the Younger Dryas cold period, followed by a decline into the mid-Holocene. The FB-delta N-15 records suggest that the coupling among cold climate, reduced nitrate supply, and more complete nitrate consumption that characterized the LGM also applied to the deglacial cold events.
Y1  - 2015
U6  - https://doi.org/10.1002/2014PA002765
SN  - 0883-8305
SN  - 1944-9186
VL  - 30
IS  - 9
SP  - 1217
EP  - 1232
PB  - American Geophysical Union
CY  - Washington
ER  -