Biogeochemical impacts due to mesoscale eddy activity in the Sargasso Sea as measured at the Bermuda Atlantic Time-series Study (BATS)

Sweeney, Erin; McGillicuddy, Dennis J.; Buesseler, Ken O.

doi:10.1016/j.dsr2.2003.07.008

Cited by 201 publications

(221 citation statements)

References 66 publications

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“…These average 234 Th activities are the same within the error of an individual 234 Th measurement. Thorium-234 activities in this range relative to 238 U (average 238 U = 2.59 dpm L -1 ) indicate low particle export on sinking particles, similar to prior studies at BATS Sweeney et al, 2003). This observation indicates that to first order, particle export in association with both eddies C1 and A4 is not exceptionally high.…”

Section: Vertical Profiles Of Total 234 Th and Ancillary Datasupporting

confidence: 69%

“…Eddies in this region have a life time of several months to a year or more and generally propagate from east to west at speeds of 3-5 km day -1 (Siegel et al, 1999). Depending upon what stage the eddy was in when it passed by BATS, the time-series observations at this fixed site would reveal a different response that would complicate the interpretation of the impact of eddies on local biogeochemistry and particle export (Sweeney et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…These fluxes are thought to be the major loss term with respect to upper ocean C and nutrient cycles at BATS and many other sites. In a prior study on this topic, Sweeney et al (2003) found that during a 3 year period, 4 out of 6 high particle flux events at BATS occurred in association with the passage of eddies. However the export response was variable and the age or biogeochemical state of the eddy appeared to be significant.…”

Section: Introductionmentioning

confidence: 99%

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Particle fluxes associated with mesoscale eddies in the Sargasso Sea

Buesseler

Lamborg

Cai

et al. 2008

Deep Sea Research Part II: Topical Studies in Oceanography

117

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We examined the impact of a cyclonic eddy and mode-water eddy on particle flux in the Sargasso Sea. The primary method used to quantify flux was based upon measurements of the natural radionuclide, 234 Th, and these flux estimates were compared to results from sediment traps in both eddies, and a 210 Po/ 210 Pb flux method in the mode-water eddy. Particulate organic carbon (POC) fluxes at 150m ranged from 1 to 4 mmol C m -2 d -1 and were comparable between methods, especially considering differences in integration times scales of each approach. Our main conclusion is that relative to summer mean conditions at the Bermuda Atlantic Time-series Study (BATS) site, eddy-driven changes in biogeochemistry did not enhance local POC fluxes during this later, more mature stage of the eddy life cycle (>6 months old). The absence of an enhancement in POC flux puts a constraint on the timing of higher POC flux events, which are thought to have caused the local O 2 minima below each eddy, and must have taken place >2 months prior to our arrival. The mode-water eddy did enhance preferentially diatom biomass in its center where we estimated a factor of 3 times higher biogenic Si flux than the BATS summer 2 average. An unexpected finding in the highly depth resolved 234 Th data sets are narrow layers of particle export and remineralization within the eddy. In particular, a strong excess 234 Th signal is seen below the deep chlorophyll maxima which we attribute to remineralization of 234 Th bearing particles. At this depth below the euphotic zone, de novo particle production in the euphotic zone has stopped, yet particle remineralization continues via consumption of labile sinking material by bacteria and/or zooplankton. These data suggest that further study of processes in ocean layers is warranted not only within, but below the euphotic zone.

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Section: Vertical Profiles Of Total 234 Th and Ancillary Datasupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Particle fluxes associated with mesoscale eddies in the Sargasso Sea

Buesseler

Lamborg

Cai

et al. 2008

Deep Sea Research Part II: Topical Studies in Oceanography

117

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show abstract

“…The 234 Th excess at depth at some stations, especially at station PE24, could be indicative of remineralization, suggesting that there might have been a phytoplankton response or particle export event in the past. Similar features were also reported by Sweeney et al (2003) and Owens et al (2015). However, satellite images of Chl-a concentration ( Figure S5) do not indicate the existence of a phytoplankton bloom prior to sampling nor do iron concentrations support remineralization .…”

Section: Oligotrophic (20ºn-35ºn)supporting

confidence: 61%

Latitudinal distributions of particulate carbon export across the North Western Atlantic Ocean

Puigcorbé

Roca‐Martí

Masqué

et al. 2017

Deep Sea Research Part I: Oceanographic Research Papers

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Abstract234 Th-derived carbon export fluxes were measured in the Atlantic Ocean under the GEOTRACES framework to evaluate basin-scale export variability. Here, we present the results from the northern half of the GA02 transect, spanning from the equator to 64°N. As a result of limited site-specific C/ 234 Th ratio measurements, we further combined our data with previous work to develop a basin wide C/ 234 Th ratio depth curve. While the magnitude of organic carbon fluxes varied depending on the C/ 234 Th ratio used, latitudinal trends were similar, with sizeable and variable organic carbon export fluxes occurring at high latitudes and low to negligible fluxes occurring in oligotrophic waters. Our results agree with previous studies, except at the boundaries between domains, where fluxes were relatively enhanced.Three different models were used to obtain satellite-derived net primary production (NPP). In general, NPP estimates had similar trends along the transect, but there were significant differences in the absolute magnitude depending on the model used. Nevertheless, organic carbon export efficiencies were generally < 25%, with the exception of a few stations located in the transition area between the riverine and the oligotrophic domains and between the oligotrophic and the temperate domains. Satellite-derived organic carbon export models from Dunne et al. (2005) The large increase in export data in the Atlantic Ocean derived from the GEOTRACES Program, combined with satellite observations and modeling efforts continue to improve the estimates of carbon export in this ocean basin and therefore reduce uncertainty in the global carbon budget.However, our results also suggest that tuning export models and including biological parameters at a regional scale is necessary for improving satellite-modeling efforts and providing export estimates that are more representative of in situ observations.

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“…Episodic events such as eddies (McGillicuddy et al, 1998(McGillicuddy et al, , 1999Sweeney et al, 2003;Mourino-Carballido and McGillicuddy, 2006;McGillicuddy et al, 2007) may constitute a large fraction of new production and might be missed by bottle experiments or sediment traps.…”

Section: Introductionmentioning

confidence: 99%

A determination of air-sea gas exchange and upper ocean biological production from five noble gases and tritiugenic helium-3

Stanley¹

2007

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The five noble gases (helium, neon, argon, krypton, and xenon) are biologically and chemically inert, making them ideal oceanographic tracers. Additionally, the noble gases have a wide range of solubilities and molecular diffusivities, and thus respond differently to physical forcing. Tritium, an isotope of hydrogen, is useful in tandem with its daughter helium-3 as a tracer for water mass ages. In this thesis, a fourteen month time-series of the five noble gases, helium-3 and tritium was measured at the Bermuda Atlantic Time-series Study (BATS) site. The time-series of five noble gases was used to develop a parameterization of air-sea gas exchange for oligotrophic waters and wind speeds between 0 and 13 m s −1 that explicitly includes bubble processes and that constrains diffusive gas exchange to ± 6% and complete and partial air injection processes to ± 15%. Additionally, the parameterization is based on weeks to seasonal time scales, matching the time scales of many relevant biogeochemical cycles. The time-series of helium isotopes, tritium, argon, and oxygen was used to constrain upper ocean biological production. Specifically, the helium flux gauge technique was used to estimate new production, apparent oxygen utilization rates were used to quantify export production, and euphotic zone seasonal cycles of oxygen and argon were used to determine net community production. The concurrent use of these three methods allows examination of the relationship between the types of production and begins to address a number of apparent inconsistencies in the elemental budgets of carbon, oxygen, and nitrogen.

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Biogeochemical impacts due to mesoscale eddy activity in the Sargasso Sea as measured at the Bermuda Atlantic Time-series Study (BATS)

Cited by 201 publications

References 66 publications

Particle fluxes associated with mesoscale eddies in the Sargasso Sea

Particle fluxes associated with mesoscale eddies in the Sargasso Sea

Latitudinal distributions of particulate carbon export across the North Western Atlantic Ocean

A determination of air-sea gas exchange and upper ocean biological production from five noble gases and tritiugenic helium-3

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