Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information

Fluorometric chlorophyll from SCUFA underway sampling apparatus

When mapping, use Antarctic view (from 'Map Options' pulldown).

 dates:           19 January 2002 to 20 February 2002  (20020119-20020220) 
 location:        N: -46.6233  S: -66.3606  W: 179.7417  E: -178.8283 
 project/cruise:  SOFeX/MV

Contact: Anna Hilting (Duke University Marine Laboratory)

R/V Melville Extracted Chlorophyll Methodology

Please direct questions to Sara Tanner (tanner@mlml.calstate.edu) or Jodi Brewster (jbrewster@mlml.calstate.edu)

Water samples were collected from 12 depths on the CTD Rosette and 8 depths on the TM Rosette. The TM Rosette depths were chosen at the 100, 45, 30, 16, 10, 5, 1, and 0.1 percent light levels (so phytoplankton production can be related to phytoplankton biomass) (Evans et al 1987). The CTD also had 2 more depths scattered between .1 and 100 percent and one each at 200m and 300m. The water from the CTD and TM rosettes was collected using opaque brown bottles in 250, 500, 1000, and 2000 ml or white 100 ml bottles. The differing volumes depended upon the depth of the sample and whether the samples were taken within the patch or not. Sampling from the TM Rosette was done with gloves. Each bottle was rinsed three times with the sample water before filling to the neck of the bottle.

A Whatman G/FF glass Fiber Filter, (~0.7um) Polycarbonate 5 um filter, or Polycarbonate 20 micron filter was placed in a 25 mm diameter Gelman filter holder. Water was pumped through the filter, being careful the vacuum pressure did not get above 6 psi to avoid cell lyse. After filtration, the vacuum was turned off and the filter was added with forceps to a tube filled with 8 ml of 90% acetone. The tube was labeled and stored in a freezer for a minimum of 24 hours.

After the minimum 24 hours extraction time, the filter was removed from the tube and the tube was wiped down with Chem Wipes. The fluorescence of the chlorophyll extracts were read on a 10AU Turner Designs fluorometer. Two drops of 10 % HCl was added and the fluorescence was reread and recorded again. The "before" and "after" readings were plugged into equation chl-a = K * (Rb-Ra) * (vol ext/vol filtered)*dil to calculate chlorophyll a values.

A standard made from Sigma Chl-a in 90% acetone was calibrated on a spectrophotometer and used to calibrate the fluorometer at the beginning, mid and end of the cruise. Due to the fact the fluorometer drifted both ± according to the solid standard, and a high correlation was found between the low solid standard and the calibration curve, Chlorophyll-a values were corrected using the ratio of the low solid standard.

PI Notes
from Richard Barber (rbarber@duke.edu) and Anna Hilting (ahilting@duke.edu)

Chlorophyll a was determined by fluorometric methods. Fresh samples were extracted in 90% acetone at -20 degrees C for 24-30 h (Venrick and Hayward, 1984) and quantified using a Turner Designs fluorometer (Holm-Hansen et al., 1965; Lorenzen, 1966). Contact A. Hilting (Duke) for information.

These data have been edited for quality control but will be processed further for size-fraction analysis and integration using the Morel Model. See Barber et al., 1997 and Hiscock et al., 2002. Incubated depth will be calculated using the Morel model and added later.

SCUFA Underway Chlorophyll Survey Data

OCB DMO Note: Worked primarily with 'calc' worksheet from chlaSCUFA.xls. Combined elements from MelvilleChlorophyll.xls. Included data for cast_scufa U059 and 20 micron filter SCUFA samples in cast_scufa range S159-S179 from MelvilleChlorophyll.xls as well. A summary worksheet of corrected chlorophyll-a and SCUFA fluorescence data 'Chlorophyll' is found in chlaSCUFA.xls as well as a worksheet on blanks, 'Blanks'. Placement of cast_scufa U059 based on placement in cruise event log. U059 values for date, lon, lat, and notes added from cruise event log.

SCUFA or Self-Contained Underwater Fluorescence Apparatus
SCUFA brochure from Turner Designs

Original Excel file
of SCUFA chlorophyll calibration work for underway surface extracted chlorophyll

Change history:
    070423: downloaded original data (chlaSCUFA.xls) and original zipped data (raw_SCUFA.zip)
            from SOFeX project data website and extracted data 
    080813: added to OCB database by Cyndy Chandler, OCB DMO, (cchandler@whoi.edu)

13 August 2008: Prepared for OCB data system by Dave DuBois (WHOI) Cyndy Chandler, OCB DMO (WHOI) from documentation contributed by originating PI, data analysts and technicians.

Original Excel file downloaded from MBARI: copy of original Excel file

Embedded comments:
from original Excel data file: 'Cast' U059 and column 'Chl (mg Chl m-3)'
embedded comment "ahilting: error =.08*dilution=.16 ug"

PI notes regarding Chlorophyll samples from SCUFA flow-thru:
N is sample number, coincides with other samples taken during evening transects. Date and Time GMT from SCUFA file. Obs. Time from Observer taking Chlorophyll sample. The Filename denotes the SCUFA file that continual fluorescence was logged for cholorophyll sample. If you have any questions, please contact Jodi Brewster (jbrewster@mlml.calstate.edu) or Sara Tanner (tanner@mlml.calstate.edu).

For underway Survey data, please note that the Year Day and patch day values do not agree with Hiscock's event log, nor do most of the 'Landry' Cast Types, so integration of these data with other types from this cruise will be difficult without further work.

Before he passed away in 1993, John Martin suggested that an increase in the flow of iron-rich dust to the ocean causes phytoplankton (single celled algae) to grow. The increased photosynthesis removes carbon dioxide from surface waters as the algae create biomass. This carbon dioxide is replaced by carbon dioxide gas that flows into the sea from the atmosphere. Reduced carbon dioxide in the atmosphere cools the planet (CO2 is a greenhouse gas that warms the earth). The results of this work, funded by the National Science Foundation, the Department of Energy, and the US Coast Guard, will be a much better understanding of how biological processes may regulate climate. (see Related Info: Fe cycle)

A direct test of the 'Martin Hypothesis' that trace concentrations of Fe are responsible for phytoplankton's ability to grow by direct experimental addition of Fe to the surface waters. Consequently the distribution of bioavailable Fe in the surface waters determines large geographical areas primary production and the following flux of fixed organic matter to the deep sea. The aim of the SOFeX project is to investigate the effects of iron fertilization on the productivity of the Southern Ocean. The results of this work will contribute significantly to our understanding of important biogeochemical processes which bear directly on the global carbon cycle, atmospheric carbon dioxide concentration, and climate control.

The SOFeX-N and SOFeX-S designations are sometimes used to distinguish between two iron enriched patches - one in low silicate waters north of the polar front (SOFEX-N), and the other in high silicate waters south of the polar front (SOFEX-S). All three ships, Melville (MV), Revelle (RR) and Polar Star (PS), worked in SOFEX-S, but only the Revelle and Melville worked in the SOFeX N patch and shuttled between the two patches.

The Ocean Carbon and Biogeochemistry (OCB) program focuses on the ocean's role as a component of the global Earth system, bringing together research in geochemistry, ocean physics, and ecology that inform on and advance our understanding of ocean biogeochemistry. The overall program goals are to promote, plan, and coordinate collaborative, multidisciplinary research opportunities within the U.S. research community and with international partners. Important OCB-related activities currently include: the Ocean Carbon and Climate Change (OCCC) and the North American Carbon Program (NACP); U.S. contributions to IMBER, SOLAS, CARBOOCEAN; and numerous U.S. single-investigator and medium-size research projects funded by U.S. federal agencies including NASA, NOAA, and NSF.

The scientific mission of OCB is to study the evolving role of the ocean in the global carbon cycle, in the face of environmental variability and change through studies of marine biogeochemical cycles and associated ecosystems.

The overarching OCB science themes include improved understanding and prediction of: 1) oceanic uptake and release of atmospheric CO2 and other greenhouse gases and 2) environmental sensitivities of biogeochemical cycles, marine ecosystems, and interactions between the two.

The OCB Research Priorities (updated January 2012) include: ocean acidification; terrestrial/coastal carbon fluxes and exchanges; climate sensitivities of and change in ecosystem structure and associated impacts on biogeochemical cycles; mesopelagic ecological and biogeochemical interactions; benthic-pelagic feedbacks on biogeochemical cycles; ocean carbon uptake and storage; and expanding low-oxygen conditions in the coastal and open oceans.

The two main objectives of the Iron Synthesis program (SCOR Working Group proposal, 2005), are:
1. Data compilation: assembling a common open-access database of the in situ iron experiments, beginning with the first period (1993-2002; Ironex-1, Ironex-2, SOIREE, EisenEx, SEEDS-1; SOFeX, SERIES) where primary articles have already been published, to be followed by the 2004 experiments where primary articles are now in progress (EIFEX, SEEDS-2; SAGE, FeeP); similarly for the natural fertilizations S.O.JGOFS (1992), CROZEX (2004/2005) and KEOPS (2005).

2. Modeling and data synthesis of specific aspects of two or more such experiments for various topics such as physical mixing, phytoplankton productivity, overall ecosystem functioning, iron chemistry, CO2 budgeting, nutrient uptake ratios, DMS(P) processes, and combinations of these variables and processes.

SCOR Working Group proposal, 2005. "The Legacy of in situ Iron Enrichments: Data Compilation and Modeling".
http://www.scor-int.org/Working_Groups/wg131.htm

See also: SCOR Proceedings Vol. 42 Concepcion, Chile October 2006, pgs: 13-16 2.3.3 Working Group on The Legacy of in situ Iron Enrichments: Data Compilation and Modeling.

The first objective of the Iron Synthesis program involves a data recovery effort aimed at assembling a common, open-access database of data and metadata from a series of in-situ ocean iron fertilization experiments conducted between 1993 and 2005. Initially, funding for this effort is being provided by the Scientific Committee on Oceanic Research (SCOR) and the U.S. National Science Foundation (NSF).

Through the combined efforts of the principal investigators of the individual projects and the staff of Biological and Chemical Oceanography Data Management Office (BCO-DMO), data currently available primarily through individuals, disparate reports and data agencies, and in multiple formats, are being collected and prepared for addition to the BCO-DMO database from which they will be freely available to the community.

As data are contributed to the BCO-DMO office, they are organized into four overlapping categories:
1. Level 1, basic metadata
(e.g., description of project/study, general location, PI(s), participants);
2. Level 2, detailed metadata and basic shipboard data and routine ship's operations
(e.g., CTDs, underway measurements, sampling event logs);
3. Level 3, detailed metadata and data from specialized observations
(e.g., discrete observations, experimental results, rate measurements) and
4. Level 4, remaining datasets
(e.g., highest level of detailed data available from each study).

Collaboration with BCO-DMO staff began in March of 2008 and initial efforts have been directed toward basic project descriptions, levels 1 and 2 metadata and basic data, with detailed and more detailed data files being incorporated as they become available and are processed.

Related file

Program Documentation

The Iron Synthesis Program is funded jointly by the Scientific Committee on Oceanic Research (SCOR) and the U.S. National Science Foundation (NSF).