Changes in the isotopic value of sedimentary nitrogen at California margin site 1010; a record of denitrification changes over the last five million years

Author(s): Jin, J. P. Y.; Batista, F.; Ravelo, A. C.
Author Affiliation(s): Primary:
University of California at Santa Cruz, Santa Cruz, CA, United States
Volume Title: AGU 2014 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2014; American Geophysical Union 2014 fall meeting, San Francisco, CA, Dec. 15-19, 2014. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: Global cooling over the last 5 myrs, from the warm Pliocene to the cold ice ages, is associated with changes in circulation and atmospheric carbon dioxide concentrations. Since primary productivity is limited by bioavailable nitrogen (N), fluctuations in the oceanic fixed N inventory potentially played an important role in these cooling trends. This inventory of fixed N is a balance of fixation and denitrification; both processes impart N isotope effects. Published records of increasing N isotopic values of bulk sediment have been interpreted as indicating intensification of denitrification with global cooling. However, most data, such as from California margin ODP Site 1012 (Liu et al., 2007), are from upwelling regions of the east Pacific where changes in N utilization may have occurred, obscuring the signature of changes in the N isotopic value of source nitrate which is affected by denitrification. Our study focuses on Site 1010, located off-shore from Site 1012 in a region of compete N utilization where we can obtain a record of isotopic values of source N, and thus of the evolution of denitrification during global cooling.
Year of Publication: 2014
Research Program: ODP Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; California; Continental borderland; East Pacific; Leg 167; North Pacific; Northeast Pacific; ODP Site 1010; ODP Site 1012; Ocean Drilling Program; Pacific Ocean; United States
Coordinates: N321658 N321658 W1182302 W1182302
N295754 N295754 W1180602 W1180602
Record ID: 2015108685
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