Nutrient assimilation, export production and 234 Th scavenging in the eastern equatorial Pacific
Journal
Deep Sea Research Part A, Oceanographic Research Papers
Journal Volume
36
Journal Issue
10
Pages
1471-1489
Date Issued
1989
Author(s)
Abstract
Primary productivity, nitrogen uptake using 15N-labeled NH4+ and NO3-, and the distribution and vertical fluxes of POC, PON, chlorophyll, phaeopigments and 234Th have been analysed at four stations in the eastern equatorial Pacific. Two stations were north and two stations were south of the equatorial front. Most analyses show little variation across the front, which is a boundary between cold, nutrient-rich surface water to the south and warm, nutrient-poor surface water to the north. New production and the f-ratio has been calculated using several approaches, including nitrogen uptake rates, export fluxes of POC and PON and the residence time of 234Th. At three of the four stations these independent estimates agree to within a factor of 2. All estimates of the f-ratio (0.1-0.3) are lower than would be predicted from published fvs NO3- concentration or fvs primary production curves. The ammonia concentration may be the controlling factor in this case. The residence time of 234Th is about a factor of three less than the residence time of carbon but agrees well with the residence time of total suspended matter. The residence time of nitrogen is about 50% longer than that of carbon. © 1989.
Type
journal article