Dataset: Carbon Survey Redfield Ratios

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:C_org 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 addressspecific research trajectory elements 1 and 2 outlined in the JGOFS SMP implementation plan and will benefit several collaborative efforts.