Williams, P. University of Wales, Bangor, email@example.com
Bowers, D. University of Wales, Bangor, oss063
CARBON BALANCE IN THE OPEN OCEANS: CAN IT BE DETERMINED FROM REGRESSION ANALYSIS OF FIELD OBSERVATIONS
Three recent papers have taken field data of photosynthesis (P) and respiration (R) and analysed them with a view of determining regional carbon balance in the oceans. Two studies (del Giorgio et al. 1997, Nature, 385, 148; Duarte and Agusti, 1998, Science 281 234) have used regression analysis of scatter plots of photosynthesis (or net photosynthesis) and respiration (or bacterial respiration) to fit the data to the classical allometric equation R = aP(super)b. The photosynthetic rate at the point where P = R is used as a threshold to determine the parts of the oceans where heterotrophy dominates over autotrophy. This type of analysis leads to the conclusion that substantial areas of the ocean, or the oceans as a whole, are in carbon deficit. By contrast, when integrated profiles are calculated for P and R using very similar or identical data sets, no evidence for substantial regional carbon deficits are found (Williams, 1998, Nature, 394, 55).
Using essentially the simplest model for the depth distribution of photosynthesis (Pz = Po*e(super)-kz) and the above allometric equation for respiration, it can be shown for a particular site with a balanced water column (i.e. depth integrated P= depth integrated respiration) that the coefficient
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