Fall AGU Meeting (Dec. 2002) COAST abstracts:

• Allen
  
• Bane et al.
  
• Barth et al.
  
• Carney et al.
  
• Couch et al.
  
• Cowles et al.
  
• Dale et al.
  
• Durski et al.
  
• Egbert et al.
  
• Gan et al.
  
• Hales et al.
  
• Kosro et al.
  
• Kuebel et al.
  
• Kurapov et al.
  
• Perlin et al.
  
• Pierce et al.
  
• Ruttenberg et al.
  
• Samelson
  
• Spitz et al.
  
• Wheeler
  

Abstracts should be cited as:

EOS Trans. AGU, 83 (47),
Fall Meet. Suppl.,
Abstract XXXXX-XX, 2002

OS61D-03

Upwelling Along the Oregon Coast is a Sink for Atmospheric CO2

B Hales, T Takahashi, L Bandstra, and P Covert

High-resolution cross-shelf sections of nutrient and PCO2
measurements made during May and August of 2001 off the Oregon
Coast show the effects of strong upwelling of nutrient-and
CO2- rich water, followed by rapid uptake of these chemicals by
biological productivity.  Photosynthetic production draws nitrate
from over 30 micro mol/kg to undetectable levels; along with this
nitrate uptake, PCO2 is drawn down from values of 300 micro atm
above, to 200 micro atm below, atmospheric saturation. High PCO2
surface waters are confined to a narrow region near the coast; low
PCO2 conditions persist seaward over areas covering most of the
shelf. If these conditions are representative of other upwelling
areas in the Eastern North Pacific over the duration of the upwelling
season, CO2 transfer into such waters may represent a significant
contribution to the total summer-time uptake of CO2 by the entire
North Pacific. This phenomenon makes the Oregon Coast unique among
upwelling regions of the world oceans, which are typically sources
of CO2 to the atmosphere. Three factors appear to contribute to this
singularity: 1) Upwelled source waters have high preformed nitrate
relative to total CO2 (TCO2), which allows for the necessarily
high alkalinity:TCO2 ratios implied by the observed low PCO2;
2) Productivity is able to rapidly consume all upwelled nitrate,
along with a stoichiometric proportion of TCO2; and 3) upwelled
waters are only moderately warmed in comparison to lower-latitude
upwelling regions.