Table of Contents

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

SOIREE Sediment Traps - Water column POC and PON results METHOD
Two litre samples filtered through preweighed, precombusted (450°C for 4 hours) GF/F filters;
assumed negligible carbonate so samples non-acidified; whole filters analysed on CHN analyser

Corrected values were calculated based on a filtered volume of 2 litres, rather than 500 ml
as reported for the initial values

NOTES
1. The initial and OUTSIDE PATCH water column integrated POC values from SOIREE are higher
than expected for Southern Ocean HNLC waters. For example, unpublished data provided by
Wilford Gardner (USA) from the US JGOFS AESOPS transect, show that between 52-72°S 170°W
integrated POC standing stocks (0-50 m) in summer ranged from 3002-14413 mgC/m2 in Dec 1997
and 3603-10209 mgC/m2 in Jan 1998 SOIREE POC (MLD integrated) range from 4500-6200 mgC/m2
outside the iron-fertilised patch which were not substantially different from that measured
inside the patch during the SOIREE bloom (5100-8500 mgC/m2)

2. There is no obvious indication from either sampling or analytical techniques that the POC
values are artificially inflated due to sample handling, etc.

3. Charette & Buesseler (2000, G3) suggest that a previous export event must have occurred prior
to SOIREE due to a substantial 234Th deficit relative to 238U, which might explain the SOIREE POC
results. Since there is no indication from daily SeaWiFS images of a surface bloom from Nov 1998-Jan 1999
(C. Law pers. comm., 1999), nor any "memory" of such an event in the pCO2 data (Watson et al., 2000, Nature),
Charette & Buesseler (2000) suggested that such a bloom is likely to have been a subsurface feature,
or that there was a significant delay in export

4. "Live" biological carbon in HNLC waters outside the patch represented a significant or similar
amount of the organic carbon that was measured in the water column, ranging from 78-100% of the
MLD-integrated POC (see Table A below). If we assume that the water column samples would have sampled
only the phytoplankton and the microzooplankton (and not heterotrophic bacteria and mesozooplankton)
then this proportion decreases to 40-60% but is still relatively substantial.

5. POC values inside and outside the SOIREE patch were similar despite 6-fold and 3-fold increases in
chlorophyll a concentrations and phytoplankton abundance, respectively, inside the iron-fertilised patch
(Boyd et al., 2000, Nature)

6. Therefore, we conclude that perhaps there was a significant POC component in the water column at
the time that the SOIREE site was occupied, representing relict organic material derived from a previous
bloom/export event.

7. Given the uncertainties, however, it is wise to treat the interpretation of the above POC data with caution.
 

Table A				mixed layer (0-65 m)						
				col integrated POC 						
		OUT stations only 	mg C m-2				mg C m-2		%			%
									
		STATION	phyto	hbact	microzoo	mesozoo 	total 	POC water column	Difference (ALL)	Diff (phyto + micro only)
12-Feb-99	T1141/1	1595	504	772		1600		4471	5615			79.6			42.2
16-Feb-99	T1152/1	2023	346	620		1600		4589	5881			78.0			44.9
18-Feb-99	T1157/1	1595	290	616		1600		4101	5157			79.5			42.9
21-Feb-99	T1168/1	1885	374	706		1600		4565	4564			100.0			56.8

See SOIREE Preliminary Voyage Report

METHOD
Two litre samples filtered through preweighed, precombusted (450°C for 4 hours) GF/F filters;
assumed negligible carbonate so samples non-acidified; whole filters analysed on CHN analyser

Corrected values were calculated based on a filtered volume of 2 litres, rather than 500 ml
as reported for the initial values

NOTES
1. The initial and OUTSIDE PATCH water column integrated POC values from SOIREE are higher
than expected for Southern Ocean HNLC waters. For example, unpublished data provided by
Wilford Gardner (USA) from the US JGOFS AESOPS transect, show that between 52-72°S 170°W
integrated POC standing stocks (0-50 m) in summer ranged from 3002-14413 mgC/m2 in Dec 1997
and 3603-10209 mgC/m2 in Jan 1998 SOIREE POC (MLD integrated) range from 4500-6200 mgC/m2
outside the iron-fertilised patch which were not substantially different from that measured
inside the patch during the SOIREE bloom (5100-8500 mgC/m2)

2. There is no obvious indication from either sampling or analytical techniques that the POC
values are artificially inflated due to sample handling, etc.

3. Charette & Buesseler (2000, G3) suggest that a previous export event must have occurred prior
to SOIREE due to a substantial 234Th deficit relative to 238U, which might explain the SOIREE POC
results. Since there is no indication from daily SeaWiFS images of a surface bloom from Nov 1998-Jan 1999
(C. Law pers. comm., 1999), nor any "memory" of such an event in the pCO2 data (Watson et al., 2000, Nature),
Charette & Buesseler (2000) suggested that such a bloom is likely to have been a subsurface feature,
or that there was a significant delay in export

4. "Live" biological carbon in HNLC waters outside the patch represented a significant or similar
amount of the organic carbon that was measured in the water column, ranging from 78-100% of the
MLD-integrated POC (see Table A below). If we assume that the water column samples would have sampled
only the phytoplankton and the microzooplankton (and not heterotrophic bacteria and mesozooplankton)
then this proportion decreases to 40-60% but is still relatively substantial.

5. POC values inside and outside the SOIREE patch were similar despite 6-fold and 3-fold increases in
chlorophyll a concentrations and phytoplankton abundance, respectively, inside the iron-fertilised patch
(Boyd et al., 2000, Nature)

6. Therefore, we conclude that perhaps there was a significant POC component in the water column at
the time that the SOIREE site was occupied, representing relict organic material derived from a previous
bloom/export event.

7. Given the uncertainties, however, it is wise to treat the interpretation of the above POC data with caution.
 

Table A				mixed layer (0-65 m)						
				col integrated POC 						
		OUT stations only 	mg C m-2				mg C m-2		%			%
									
		STATION	phyto	hbact	microzoo	mesozoo 	total 	POC water column	Difference (ALL)	Diff (phyto + micro only)
12-Feb-99	T1141/1	1595	504	772		1600		4471	5615			79.6			42.2
16-Feb-99	T1152/1	2023	346	620		1600		4589	5881			78.0			44.9
18-Feb-99	T1157/1	1595	290	616		1600		4101	5157			79.5			42.9
21-Feb-99	T1168/1	1885	374	706		1600		4565	4564			100.0			56.8

See SOIREE Preliminary Voyage Report
See NOTES in Dataset description and Methods & Sampling description
 

Generated from original file SOIREE_Export_final.xls, Tab: PONPNwatercolumn
provided on the Deep-Sea Research II 48 (2001) accompanying CD-Rom

BCO-DMO Edits
- parameter names modified to conform to BCO-DMO convention
- date_UTC, time_UTC, lat, lon added from files:
SOIREE_Stations_MasterStationList.xls
SOIREE_CTD_Summary
- Blank rows in original sheet removed
- 'nd' added to blank cells
- Added Sum_[Client_Id] to Client_Id field in summation rows
- Moved Averages to three sets of rows/columns at end

Project in the Southern Ocean aimed at maintaining a coherent patch of iron-enriched seawater for the duration of project and to interpret any iron-mediated effects on the patch by conducting measurements and performing experiments during this period of the project.

The Southern Ocean Iron RElease Experiment (SOIREE), was the first in situ iron fertilization experiment performed in the polar waters of the Southern Ocean. SOIREE was an interdisciplinary study involving participants from six countries, and took place in February 1999 south of the Polar Front in the Australasian-Pacific sector of the Southern Ocean.

Approximately 3800 kg of acidified FeSO4.7H2O and 165 g of the tracer sulphur hexafluoride (SF6) were added to a 65-m deep surface mixed layer over an area of ~50 km2. Initially, mean dissolved iron concentrations were ~2.7 nM, but decreased to ambient levels within days, requiring subsequent additions of 1550-1750 kg of acidified FeSO4.7H2O on days 3, 5 and 7 of the experiment.

During the 13-day site occupation, there were iron-mediated increases in phytoplankton growth rates, with marked increases in chlorophyll a (up to 2 µgl-1) and production rates (up to 1.3 gCm-2d-1). These resulted in subsequent changes in the pelagic ecosystem structure, and in the cycling of carbon, silica and sulphur, such as a 10% drawdown of surface CO2.

The SOIREE bloom persisted for >40 days following our departure from the site, as observed via SeaWiFS remotely sensed observations of Ocean Colour.

BCO-DMO Note:
All original data and metadata provided on a CD-Rom accompanying the Deep-Sea Research II 48 (2001) volume. The CD-Rom contains the main SOIREE datasets and ancillary information including the pre-experiment 'desktop' database study for site-selection, and satellite images of the SOIREE bloom.
© 2001 Elsevier Science Ltd. All rights reserved.

Related files

SOIREE Preliminary Voyage Report
SOIREE Introduction and Summary, Deep-Sea Research II 48 (2001) 2425-2438
SOIREE Cruise Track

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).