Redfield behavior of carbon, nitrogen, and phosphorus depletions in Antarctic surface water

Abstract

Inspired by the recent debate about anomalous nutrient utilization ratios in the surface oceans, we calculated depletions of total carbon dioxide, nitrate, and phosphate for the surface layer of the western Weddell Sea in summer. The depletion ratios, which incorporate all changes over a period of about 3 months starting from the onset of the vegetative season, essentially follow the classical Redfield model. We argue that reliable Redfield ratios can only be obtained when the time interval over which the nutrient utilization ratios are determined is comparable to the length of the vegetative season. Nutrient depletions are perfectly suitable to obtain reliable nutrient consumption ratios. We have good reason to believe that in the surface waters of the Antarctic, as they are nutrient replete, the nutrient consumption ratios comply with the classical Redfield values.