The SOLAS air–sea gas exchange experiment (SAGE) 2004

Harvey, Mike; Law, Cliff S.; Smith, M. J.; Hall, Julie; Abraham, Edward R.; Stevens, Craig L.; Hadfield, Mark G.; Ho, David T.; Ward, Brian; Archer, Stephen D.; Cainey, Jill M.; Currie, Kim; DeVries, Dawn; Ellwood, Michael J.; Hill, Peter; Jones, Graham B; Katz, David R.; Kuparinen, Jorma; Macaskill, Burns; Main, W. de L.; Marriner, Andrew; McGregor, John; McNeil, Craig; Minnett, Peter J.; Nodder, Scott D.; Peloquin, J.; Pickmere, S.; Pinkerton, Matthew H.; Safi, Karl; Thompson, Rona L.; Walkington, Matthew; Wright, Simon W.; Ziolkowski, Lori A.

doi:10.1016/j.dsr2.2010.10.015

Cited by 29 publications

(30 citation statements)

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“…Nevertheless, our results agree with those of SAZ‐SENSE, which reported lower export and greater mesopelagic remineralization in naturally iron‐replete than in iron‐limited low‐Si sub‐Antarctic waters [ Bowie et al ., ; Ebersbach et al ., ; Jacquet et al ., ]. Only a modest response, mostly by nondiatom phytoplankton <20 µm, was found upon iron fertilization of sub‐Antarctic low‐Si waters during SAGE, suggesting that export was probably not greatly enhanced [ Harvey et al ., ; Peloquin et al ., ]. In contrast, POC export at the low‐Si sub‐Antarctic SOFeX North site was enhanced by iron fertilization, with NO 3 − depletion similar to LOHAFEX [ Bishop et al ., ; Coale et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…Only two FeAXs were conducted in low‐silicon (Si) waters (Southern Ocean iron enrichment experiment (SOFeX) North and SOLAS air‐sea gas exchange experiment (SAGE)). However, diatoms were abundant and, apparently, not Si limited during SOFeX North [ Coale et al ., ], while downward particle export was not measured during SAGE [ Harvey et al ., ]. Recent work has suggested that Fe supply to low‐Si Southern Ocean regions may not enhance POC flux, although appreciable POC flux occurs there naturally [ Bowie et al ., ; Henson et al ., ; Trull et al ., ].…”

Section: Introductionmentioning

confidence: 98%

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Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX

Martin

Loeff

Cassar

et al. 2013

Global Biogeochemical Cycles

102

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[1] A closed eddy core in the Subantarctic Atlantic Ocean was fertilized twice with two tons of iron (as FeSO 4 ), and the 300 km 2 fertilized patch was studied for 39 days to test whether fertilization enhances downward particle flux into the deep ocean. Chlorophyll a and primary productivity doubled after fertilization, and photosynthetic quantum yield (F V /F M ) increased from 0.33 to ≥0.40. Silicic acid (<2 μmol L À1 ) limited diatoms, which contributed <10% of phytoplankton biomass. Copepods exerted high grazing pressure. This is the first study of particle flux out of an artificially fertilized bloom with very low diatom biomass. Net community production (NCP) inside the patch, estimated from O 2 :Ar ratios, averaged 21 mmol POC m À2 d À1 , probably ±20%. 234 Th profiles implied constant export of~6.3 mmol POC m À2 d À1 in the patch, similar to unfertilized waters. The difference between NCP and 234 Th-derived export partly accumulated in the mixed layer and was partly remineralized between the mixed layer and 100 m. Neutrally buoyant sediment traps at 200 and 450 m inside and outside the patch caught mostly <1.1 mmol POC m À2 d À1 , predominantly of fecal origin; flux did not increase upon fertilization. Our data thus indicate intense flux attenuation between 100 and 200 m, and probably between the mixed layer and 100 m. We attribute the lack of fertilization-induced export to silicon limitation of diatoms and reprocessing of sinking particles by detritus feeders. Our data are consistent with the view that nitrate-rich but silicate-deficient waters are not poised for enhanced particle export upon iron addition.Citation: Martin, P., et al. (2013), Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX, Global Biogeochem. Cycles, 27,[871][872][873][874][875][876][877][878][879][880][881]

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX

Martin

Loeff

Cassar

et al. 2013

Global Biogeochemical Cycles

102

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“…Here, wind, waves and currents develop unhindered by land, and strong persistent westerlies act over long fetch to generate large swells that propagate northeast influencing the wave climate off New Zealand. While this wave energy is attenuated closer to land in the eastern Chatham Rise, the average wave energy is still 75 % of values south of New Zealand, where annual mean wave heights exceed 4 m. Subantarctic waters south of the Chatham Rise region provided a prime location for a dual tracer release experiment (SAGE; Harvey et al, 2011), aimed at constraining k at high wind speeds. Comparison of the SAGE k-wind-speed parameterization with those generated in other regions and using different techniques showed generally good agreement (Ho et al, 2006); this may be interpreted as indicating that regional influences on exchange may be less important, supporting the application of a universal wind speed parameterization.…”

Section: Regional Contextmentioning

confidence: 99%

Overview and preliminary results of the Surface Ocean Aerosol Production (SOAP) campaign

et al. 2017

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Abstract. Establishing the relationship between marine boundary layer (MBL) aerosols and surface water biogeochemistry is required to understand aerosol and cloud production processes over the remote ocean and represent them more accurately in earth system models and global climate projections. This was addressed by the SOAP (Surface Ocean Aerosol Production) campaign, which examined air-sea interaction over biologically productive frontal waters east of New Zealand. This overview details the objectives, regional context, sampling strategy and provisional findings of a pilot study, PreSOAP, in austral summer 2011 and the following SOAP voyage in late austral summer 2012. Both voyages characterized surface water and MBL composition in three phytoplankton blooms of differing species composition and biogeochemistry, with significant regional correlation observed between chlorophyll a and DMSsw. Surface seawater dimethylsulfide (DMSsw) and associated air-sea DMS flux showed spatial variation during the SOAP voyage, with maxima of 25 nmol L −1 and 100 µmol m −2 d −1 , respectively, recorded in a dinoflagellate bloom. Inclusion of SOAP data in a regional DMSsw compilation indicates that the current climatological mean is an underestimate for this region of the southwest Pacific. Estimation of the DMS gas transfer velocity (k DMS ) by independent techniques of eddy covariance and gradient flux showed good agreement, although both exhibited periodic deviations from model estimates. Flux anomalies were related to surface warming and sea surface microlayer enrichment and also reflected the heterogeneous distribution of DMSsw and the associated flux footprint. Other aerosol precursors measured included the halides and various volatile organic carbon compounds, with first measurements of the short-lived gases glyoxal and methylglyoxal in pristine Southern Ocean marine air indicating an unidentified local source. The application of a real-time clean sector, contaminant markers and a common aerosol inlet facilitated multi-sensor measurement of uncontaminated air. Aerosol characterization identified variable Aitken mode and consistent submicron-sized accumulation and coarse modes. Submicron aerosol mass was dominated by secondary particles containing ammonium sulfate/bisulfate under light winds, with an increase in sea salt under higher wind speeds. MBL measurements and chamber experiments identified a significant organic component in primary and secondary aerosols. Comparison of SOAP aerosol number and size distributionsPublished by Copernicus Publications on behalf of the European Geosciences Union. 13646 C. S. Law et al.: Overview and preliminary results of the SOAP campaign reveals an underprediction in GLOMAP (GLObal Model of Aerosol Processes)-mode aerosol number in clean marine air masses, suggesting a missing marine aerosol source in the model. The SOAP data will be further examined for evidence of nucleation events and also to identify relationships between MBL composition and surface ocean biogeochemistry that may pr...

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“…To test the effects of iron fertilization on marine ecosystems and carbon cycle in actual ocean areas, a number of field experiments have been performed in the HNLC waters in the eastern equatorial Pacific [ Coale et al , 1996] and the subarctic North Pacific Ocean [ Tsuda et al , 2003; Boyd et al , 2004; Law et al , 2006; Wong et al , 2006]. The Southern Ocean has been the site of several fertilization experiments as well, in the Atlantic [ Bakker et al , 2001], Indian [ Boyd et al , 2000; Boyd and Law , 2001; Gervais et al , 2002], and Pacific sectors [ Coale et al , 2004; Harvey et al , 2011]. All but the SOLAS Air‐Sea Gas Exchange Experiment (SAGE) [ Harvey et al , 2011] southeast of New Zealand showed strong increases in the primary productivity and biomass in mixed layer, and depletion of dissolved inorganic carbon and nutrients relative to ambient, unfertilized waters.…”

Section: Introductionmentioning

confidence: 99%

“…The Southern Ocean has been the site of several fertilization experiments as well, in the Atlantic [ Bakker et al , 2001], Indian [ Boyd et al , 2000; Boyd and Law , 2001; Gervais et al , 2002], and Pacific sectors [ Coale et al , 2004; Harvey et al , 2011]. All but the SOLAS Air‐Sea Gas Exchange Experiment (SAGE) [ Harvey et al , 2011] southeast of New Zealand showed strong increases in the primary productivity and biomass in mixed layer, and depletion of dissolved inorganic carbon and nutrients relative to ambient, unfertilized waters.…”

Section: Introductionmentioning

confidence: 99%

Mesoscale biogeochemical responses to iron fertilization in the upper layers of the Southern Ocean Iron Experiment areas

Hales

Takahashi

2012

J. Geophys. Res.

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two iron fertilization experiments were conducted at the south (66.45°S, 171.8°W) and north (56.23°S, 172°W) patches. The south patch was replete with all macronutrients, whereas the north patch was nearly depleted of silicate. Using a towed water sampling/ measurement system, high resolution three-dimensional observations of temperature, salinity, CO 2 partial pressure (pCO 2 ) and the concentrations of total CO 2 (TCO 2 ), nitrate, phosphate and silicate in the upper 100 m were obtained 10 and 28 days after initial iron additions in the south and north patches, respectively. TCO 2 and nutrient drawdowns observed in the south patch were small due to wind events that limited biological response in the early postfertilization period. At the north patch, drawdown signals were stronger, resulting from the longer time since fertilization. The north patch was dispersed along a frontal zone between two distinct waters, with the denser subducted under the lighter. Subduction limited CO 2 uptake from the air, but provided alternative mechanisms for vertical carbon export. Based on the biogeochemical drawdowns and published estimates of the rate of the entrainment of nonfertilized waters into the patch, the mean net community productivity over 28 days was estimated to be 94 AE 12 mmol carbon m À2 day À1, to which the air-to-sea flux contributed only 2%. Despite low silicate concentrations and potential limitation of growth of silicifying plankton in the north patch, our estimates of the enhanced carbon uptake are similar to estimates from higher silicate environments.

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The SOLAS air–sea gas exchange experiment (SAGE) 2004

Abstract: 1The SOLAS air-sea gas exchange experiment (SAGE) was a multiple-objective study investigating 2 gas-transfer processes and the influence of iron fertilisation on biologically driven gas exchange in

Cited by 29 publications

References 56 publications

Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX

Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX

Overview and preliminary results of the Surface Ocean Aerosol Production (SOAP) campaign

Mesoscale biogeochemical responses to iron fertilization in the upper layers of the Southern Ocean Iron Experiment areas

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