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23 October 2007: Prepared for OCB data system by Cyndy Chandler, BCO-DMO (MCG Dept, WHOI).
This doumentation relates to the oxygen evolution experiments and "NCP rates"
data sets including community production and respiration rate calculations.
Original MS Word file downloaded from EDDIES Web site: copy of original data file
Contact: Dennis McGillicuddy
NCP Methodology taken from Mouriño-Carballido and McGillicuddy (2006)
Mouriño-Carballido, B., and D.J. McGillicuddy Jr, 2006. Mesoscale Variability in the Metabolic Balance of the Sargasso Sea. Limnology and Oceanography, 51, 2675-2689.
Net community production (NCP) and respiration experiments based on in vitro changes in dissolved oxygen (24-hour light/dark bottle incubations) were conducted during the EDDIES R/V Oceanus cruises (OC404-1 and OC404-4) in the Sargasso Sea in June, July, and August 2004.
Water samples were collected from a 24-bottle rosette (10-dm3 PVC Niskin bottles) through silicon tubing into calibrated borosilicate glass bottles, with a nominal volume of 120 cm3. Four or five bottle sampling depths were chosen at each station according to the profiles of fluorescence and photosynthetically available radiation (PAR). Water samples from each depth were collected from three different Niskin bottles to minimize exchange of oxygen with the head space in the bottle. When ship logistics precluded predawn sampling, precautions were taken to minimize exposure of samples to light and temperature greater than those experienced in situ.
From each depth, ten to fourteen clear and dark bottles were incubated for 24 hours in a light- and temperature-controlled on-deck incubator. The average standard deviation of incubator temperature from the target temperature for each experiment was about 0.5uC. Five to seven replicates bottles were fixed immediately after the incubation experiments started in order to quantify the initial oxygen concentrations (initial Sample Type). Measurements of dissolved oxygen were made with an automated Winkler titration system on the basis of a potentiometric end-point detector, as described in Williams and Jenkinson (1982).
The O2 evolution experimental results (NCP data replicates) are included in the online database » view the data
Net community production (NCP), community respiration (respir), and gross primary production (GPP) rates were calculated from light and dark incubated and time zero replicates. Standard errors associated with NCP (NCP_se), community respiration (respir_se), and gross primary production (GPP_se) rates for each sample (incubation) type are also reported.
For comparative purposes, GPP, NCP, and respiration rates were integrated to the 1% light depth measured during the cruises (about 100 meters), and these data are reported at depth "int".
The calculated rates are reported in the online database as NCP rates » view the rates
Additional information is available for these data (PDF files created from the original tables
contributed in NCP_OC404.doc):
Table 2 is an explanation of the discarded values
Table 3 shows a statistical summary of the rate calculations
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