Synthesis & Modeling Project
R. M. Key
L. I. Gordon
C. L. Sabine
N. Gruber
C. W. Mordy
Determination of the Redfield remineralization ratios based on neutral surface analysis of the new global data set

NSF OCE-9819144 / OCE-9903391 06/99 - 05/02 

PROJECT DESCRIPTION: Synthesis of primary nutrients by marine organisms and subsequent remineralization of organic matter is frequently represented by Equation 1

(eq. 1)

where the coefficients are known as the "Redfield" ratios. Redfield ratios have been particularly useful in estimating the utilization of one nutrient from another and in deriving dynamically passive conservative tracers such as "NO" and "PO".  More recently PO4*, C* and N* have been used to study air-sea oxygen fluxes, large scale mixing problems, anthropogenic CO2 and nitrogen biogeochemistry.  The value of the ratios and their large scale variability are also important because they are a critical component in the application of computer models to study ocean biogeochemistry and global climate change.

The traditional P:N:Corg Redfield ratios of 1:16:106 were based on planktonic decomposition studies.  Recent studies have reevaluated the ratios.  Significant disagreement still exists, however. In large part the disagreement stems from various weaknesses in the approaches and in the overall quality and quantity of the data sets used.

The goal of this project is to redetermine the Redfield ratios of remineralization.  Specific improvements over previous efforts include the availability of a new global high quality nutrient data set and application of an optimal multi-parameter technique to determine endpoints.  The technique will be applied on approximately 20 neutral density layers in each ocean basin.  A significant improvement over previous work will be the inclusion of the recently completed global CO2 survey results along with the new nutrient data.  In the analysis corrections for the potential bias caused by anthropogenic CO2 invasion, nitrogen fixation and denitrification will be made.  Preliminary investigations have demonstrated that small systematic offsets exist in the nutrient data.  Therefore, prior to calculation of the Redfield ratios, a comprehensive global calibration of the nitrate, phosphate and silicate data sets will be completed.  The analytical procedures for this calibration have already been developed.  The results of this work will directly address specific research trajectory elements 1 and 2 outlined in the JGOFS SMP implementation plan and will benefit several collaborative efforts.


DATA: GLODAP (GLobal Ocean Data Analysis Project) provides many datasets from this project via (anthropogenic carbon, delta CO2 1995-1978, total alkalinity, total carbon)


PUBLICATIONS: Keller, K., R.D. Slater, M. Bender, R.M. Key. (submitted) Possible biological or physical explanations for decadal scale trends in North Pacific nutrient concentrations and oxygen utilization. DSR II, First Special Issue of the U.S. JGOFS Synthesis and Modeling Project.

Additional publications related to this project are listed via http://geoweb.princeton.edu/bigscience/GLODAP/nutrients/GLODAP.ref.html


RELATED PROJECTS: Gruber  "Analyzing and modeling interannual to decadal variability in the carbon cycle of the subtropical and subpolar gyres."

Najjar; Doney; Key; Sabine; Sarmiento; Caldeira  "Evaluation and intercomparison of three-dimensional marine carbon cycle models"

Sabine; Key; Feely; Bullister; Millero; Wanninkhof; Peng; Kozyr  "Synthesis and interpretation of the NOAA/DOE global CO2 survey data"

Gruber; Sabine; Sonnerup; Bullister; Key "Global Assessment and Synthesis of Data Based Estimates of Anthropogenic CO2 in the Ocean"


Robert M. Key
Program in Atmospheric and Ocean Sciences
Department of Geosciences, Guyot Hall
Princeton University
Princeton, NJ 08544-1003
tel: (609) 258-3595
fax: (609) 258-1274

Louis I. Gordon
College of Oceanic & Atmospheric Sciences
Oregon State University
104 Ocean Admin Bldg
Corvallis, OR 97331-5503
tel: (541) 737-2161
fax: (541) 737-2064

Christopher Sabine
7600 Sandpoint Way NE
Seattle, WA 98115
tel: (206) 526-4809
fax: (206) 526-6744

Nicolas Gruber
Inst. Geophysics and Planetary Physics & Dept Atmos. Sci.
University of California, Los Angeles
5853 Slichter Hall
Los Angeles, CA 90095-1567
tel: 310-825-4772
fax: 310-206-3051

C.W. Mordy
7600 Sand Point Way N.E.
Seattle, WA 98115-0070
tel: (206) 526-6870
fax: (206) 526-6744