Redfield ratios of remineralization determined by nutrient data analysis

Abstract

A nonlinear inverse method is applied to nutrient data upon approximately 20 neutral surfaces in each of the South Atlantic, Indian, and Pacific basins, between 400 and 4000 m depth. By accounting for the gradients in nutrients due to the mixing of “preformed” concentrations of the major water masses, the nutrient changes due to biological activity are examined, and the time‐mean, basin‐wide Redfield ratios calculated. It is found that the P/N/C org/−O 2 ratios of nutrient regeneration between 400 and 4000 m (corrected for the effect of denitrification) are approximately constant with depth and basin, at a value of 1/16 ± 1/117 ± 14/170 ± 10. These ratios agree with those of fresh organic matter, suggesting that the flux of organic material to the deep ocean may be dominated by fast‐sinking matter produced by sporadic, high‐productivity events. Sedimentary denitrification reduces the N/P utilization ratio to 12 ± 2 between 1000 and 3000 m. In the Indian and Pacific basins the C org/C inorg regeneration ratio decreases from approximately 7 ± 3 at 400 m to 3 ± 1 at 1000 m and to 1 ± 0.5 at 4000 m, suggesting a significant amount of calcium carbonate dissolution above the calcite lysoclines in the Indian and Pacific oceans.