scholarly journals The effect of typhoon on particulate organic carbon flux in the southern East China Sea

2010 ◽  
Vol 7 (10) ◽  
pp. 3007-3018 ◽  
Author(s):  
C.-C. Hung ◽  
G.-C. Gong ◽  
W.-C. Chou ◽  
C. -C. Chung ◽  
M.-A. Lee ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
East China Sea ◽  
Carbon Flux ◽  
Euphotic Zone ◽  
Phytoplankton Blooms ◽  
Export Production ◽  
Biogenic Carbon ◽  
Poc Flux ◽  
Southern East China Sea

Abstract. Severe tropical storms play an important role in triggering phytoplankton blooms, but the extent to which such storms influence biogenic carbon flux from the euphotic zone is unclear. In 2008, typhoon Fengwong provided a unique opportunity to study the in situ biological responses including phytoplankton blooms and particulate organic carbon fluxes associated with a severe storm in the southern East China Sea (SECS). After passage of the typhoon, the sea surface temperature (SST) in the SECS was markedly cooler (∼25 to 26 °C) than before typhoon passage (∼28 to 29 °C). The POC flux 5 days after passage of the typhoon was 265 ± 14 mg C m−2 d−1, which was ∼1.7-fold that (140–180 mg C m−2 d−1) recorded during a period (June–August, 2007) when no typhoons occurred. A somewhat smaller but nevertheless significant increase in POC flux (224–225 mg C m−2 d−1) was detected following typhoon Sinlaku which occurred approximately 1 month after typhoon Fengwong, indicating that typhoon events can increase biogenic carbon flux efficiency in the SECS. Remarkably, phytoplankton uptake accounted for only about 5% of the nitrate injected into the euphotic zone by typhoon Fengwong. It is likely that phytoplankton population growth was constrained by a combination of light limitation and grazing pressure. Modeled estimates of new/export production were remarkably consistent with the average of new and export production following typhoon Fengwong. The same model suggested that during non-typhoon conditions approximately half of the export of organic carbon occurs via convective mixing of dissolved organic carbon, a conclusion consistent with earlier work at comparable latitudes in the open ocean.

scholarly journals The effect of typhoon on particulate organic carbon flux in the southern East China Sea

2010 ◽  
Vol 7 (3) ◽  
pp. 3521-3550 ◽  
Author(s):  
C.-C. Hung ◽  
G.-C. Gong ◽  
W.-C. Chou ◽  
C.-C. Chung ◽  
M.-A. Lee ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
East China Sea ◽  
Carbon Flux ◽  
Euphotic Zone ◽  
East China ◽  
Phytoplankton Blooms ◽  
Export Production ◽  
Poc Flux ◽  
Southern East China Sea

Abstract. Severe tropical storms play an important role in triggering phytoplankton blooms, but the extent to which such storms influence carbon flux from the euphotic zone is unclear. In 2008, typhoon Fengwong provided a unique opportunity to study the in situ biological responses including phytoplankton blooms and particulate organic carbon fluxes associated with a severe storm in the southern East China Sea (SECS). After passage of the typhoon, the sea surface temperature (SST) in the SECS was markedly cooler (~25 to 26 °C) than before typhoon passage (~28 to 29 °C). The POC flux 5 days after passage of the typhoon was 265 ± 14 mg-C m−2 d−1, which was ~1.7-fold that (140–180 mg-C m−2 d−1) recorded during a period (June–August, 2007) when no typhoons occurred. A somewhat smaller but nevertheless significant increase in POC flux (224–265 mg-C m−2 d−1) was detected following typhoon Sinlaku which occurred approximately 1 month after typhoon Fengwong, indicating that typhoon events can increase biogenic carbon flux efficiency in the SECS. Remarkably, phytoplankton uptake accounted for only about 5% of the nitrate injected into the euphotic zone by typhoon Fengwong and it is likely that phytoplankton population growth was presumably constrained by a combination of light limitation and grazing pressure. Modeled estimates of new/export production were remarkably consistent with the average of new and export production following typhoon Fengwong. The same model suggested that during non-typhoon conditions approximately half of the export of organic carbon occurs via convective mixing of dissolved organic carbon, a conclusion consistent with earlier work at comparable latitudes in the open ocean.

scholarly journals Dynamics of particulate organic carbon flux in a global ocean model

2013 ◽  
Vol 10 (9) ◽  
pp. 14715-14767 ◽  
Author(s):  
I. D. Lima ◽  
P. J. Lam ◽  
S. C. Doney
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Relative Abundance ◽  
Sediment Trap ◽  
Euphotic Zone ◽  
Transfer Efficiency ◽  
Global Ocean ◽  
Biogeochemical Model ◽  
Test Model ◽  
Poc Flux

Abstract. The sinking of particulate organic carbon (POC) is a key component of the ocean carbon cycle and plays an important role in the global climate system. However, the processes controlling the fraction of primary production that is exported from the euphotic zone (export ratio) and how much of it survives respiration in the mesopelagic to be sequestered in the deep ocean (transfer efficiency) are not well understood. In this study, we use a three-dimensional, coupled physical-biogeochemical model (CCSM-BEC) to investigate the processes controlling the export of particulate organic matter from the euphotic zone and its flux to depth. We also compare model results with sediment trap data and other parameterizations of POC flux to depth to evaluate model skill and gain further insight into the causes of error and uncertainty in POC flux estimates. In the model, export ratios are mainly a function of diatom relative abundance and temperature while absolute fluxes and transfer efficiency are driven by mineral ballast composition of sinking material. The temperature dependence of the POC remineralization length scale is modulated by denitrification under low O2 concentrations and lithogenic (dust) fluxes. Lithogenic material is an important control of transfer efficiency in the model, but its effect is restricted to regions of strong atmospheric dust deposition. In the remaining regions, CaCO3 content of exported material is the main factor affecting transfer efficiency. The fact that mineral ballast composition is inextricably linked to plankton community structure results in correlations between export ratios and ballast minerals fluxes (opal and CaCO3), and transfer efficiency and diatom relative abundance that do not necessarily reflect ballast or direct ecosystem effects, respectively. This suggests that it might be difficult to differentiate between ecosystem and ballast effects in observations. The model's skill at reproducing sediment trap observations is equal to or better than that of other parameterizations. However, the sparseness and relatively large uncertainties of sediment trap data makes it difficult to accurately evaluate the skill of the model and other parameterizations. More POC flux observations, over a wider range of ecological regimes, are necessary to thoroughly evaluate and test model results and better understand the processes controlling POC flux to depth in the ocean.

scholarly journals Dynamics of particulate organic carbon flux in a global ocean model

2014 ◽  
Vol 11 (4) ◽  
pp. 1177-1198 ◽  
Author(s):  
I. D. Lima ◽  
P. J. Lam ◽  
S. C. Doney
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Relative Abundance ◽  
Sediment Trap ◽  
Euphotic Zone ◽  
Climate System ◽  
Transfer Efficiency ◽  
Global Ocean ◽  
Test Model ◽  
Poc Flux

Abstract. The sinking of particulate organic carbon (POC) is a key component of the ocean carbon cycle and plays an important role in the global climate system. However, the processes controlling the fraction of primary production that is exported from the euphotic zone (export ratio) and how much of it survives respiration in the mesopelagic to be sequestered in the deep ocean (transfer efficiency) are not well understood. In this study, we use a three-dimensional, coupled physical–biogeochemical model (CCSM–BEC; Community Climate System Model–ocean Biogeochemical Elemental Cycle) to investigate the processes controlling the export of particulate organic matter from the euphotic zone and its flux to depth. We also compare model results with sediment trap data and other parameterizations of POC flux to depth to evaluate model skill and gain further insight into the causes of error and uncertainty in POC flux estimates. In the model, export ratios are mainly a function of diatom relative abundance and temperature while absolute fluxes and transfer efficiency are driven by mineral ballast composition of sinking material. The temperature dependence of the POC remineralization length scale is modulated by denitrification under low O2 concentrations and lithogenic (dust) fluxes. Lithogenic material is an important control of transfer efficiency in the model, but its effect is restricted to regions of strong atmospheric dust deposition. In the remaining regions, CaCO3 content of exported material is the main factor affecting transfer efficiency. The fact that mineral ballast composition is inextricably linked to plankton community structure results in correlations between export ratios and ballast minerals fluxes (opal and CaCO3), and transfer efficiency and diatom relative abundance that do not necessarily reflect ballast or direct ecosystem effects, respectively. This suggests that it might be difficult to differentiate between ecosystem and ballast effects in observations. The model's skill in reproducing sediment trap observations is equal to or better than that of other parameterizations. However, the sparseness and relatively large uncertainties of sediment trap data makes it difficult to accurately evaluate the skill of the model and other parameterizations. More POC flux observations, over a wider range of ecological regimes, are necessary to thoroughly evaluate and test model results and better understand the processes controlling POC flux to depth in the ocean.

scholarly journals Fluxes of particulate organic carbon in the East China Sea in summer

2013 ◽  
Vol 10 (10) ◽  
pp. 6469-6484 ◽  
Author(s):  
C.-C. Hung ◽  
C.-W. Tseng ◽  
G.-C. Gong ◽  
K.-S. Chen ◽  
M.-H. Chen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
East China Sea ◽  
Sediment Resuspension ◽  
Vertical Mixing ◽  
Outer Shelf ◽  
East China ◽  
The East China Sea ◽  
Inner Shelf ◽  
Poc Flux

Abstract. To understand carbon cycling in marginal seas better, particulate organic carbon (POC) concentrations, POC fluxes and primary production (PP) were measured in the East China Sea (ECS) in summer 2007. Higher concentrations of POC were observed in the inner shelf, and lower POC values were found in the outer shelf. Similar to POC concentrations, elevated uncorrected POC fluxes (720–7300 mg C m−2 d−1) were found in the inner shelf, and lower POC fluxes (80–150 mg C m−2 d−1) were in the outer shelf, respectively. PP values (~ 340–3380 mg C m−2 d−1) had analogous distribution patterns to POC fluxes, while some of PP values were significantly lower than POC fluxes, suggesting that contributions of resuspended particles to POC fluxes need to be appropriately corrected. A vertical mixing model was used to correct effects of bottom sediment resuspension, and the lowest and highest corrected POC fluxes were in the outer shelf (58 ± 33 mg C m−2 d−1) and the inner shelf (785 ± 438 mg C m−2 d−1), respectively. The corrected POC fluxes (486 to 785 mg C m−2 d−1) in the inner shelf could be the minimum value because we could not exactly distinguish the effect of POC flux from Changjiang influence with turbid waters. The results suggest that 27–93% of the POC flux in the ECS might be from the contribution of resuspension of bottom sediments rather than from the actual biogenic carbon sinking flux. While the vertical mixing model is not a perfect model to solve sediment resuspension because it ignores biological degradation of sinking particles, Changjiang plume (or terrestrial) inputs and lateral transport, it makes significant progress in both correcting the resuspension problem and in assessing a reasonable quantitative estimate of POC flux in a marginal sea.

The benthic geochemical record of late Holocene carbon flux in the northeast Atlantic

1995 ◽  
Vol 348 (1324) ◽  
pp. 221-227 ◽  
Keyword(s):  
Organic Carbon ◽  
Carbon Flux ◽  
Late Holocene ◽  
Sediment Accumulation ◽  
Euphotic Zone ◽  
Natural Uranium ◽  
Water Interface ◽  
Northeast Atlantic ◽  
Organic Carbon Flux ◽  
Organic Carbon Burial

This study centered around a transect of high-resolution (multi) cores from the 20° W meridian, 60-18° N in the northeast Atlantic. It spans a range of primary productivity zones, and was used to quantify and examine the vertical flux of organic carbon from the euphotic zone (50 m deep) to the sediment—water interface, through the sediment mixed layer, to burial in late Holocene sediment. The disequilibrium between members of the natural uranium decay series ( 226 Ra, 210 Pb and 210 Po) - which track the biogenic flux through scavenging of the particle-reactive nuclides —was employed. Together with experimentally and observationally derived factors, these data were used to convert nuclide flux to organic carbon flux resulting in an estimate of the water column flux of organic carbon. At the sediment-water interface micro-oxygen electrodes were used to quantify the consumption of organic carbon by aerobic respiration. It was noted that the estimated organic carbon flux is strongly dependent on the intensity of bioturbation. The late Holocene organic carbon burial flux was calculated for selected cores from measured organic carbon profiles and sediment accumulation rates over approximately the last 10000 years. This combined approach reveals a strong spatial and temporal signal in the flux of organic carbon through the deep sea in the northeast Atlantic, and provides additional insight into the fate of carbon in this area of the ocean.

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