scholarly journals The fate of terrigenous dissolved organic carbon on the Eurasian shelves and export to the North Atlantic

2017 ◽  
Vol 122 (1) ◽  
pp. 4-22 ◽  
Author(s):  
K. Kaiser ◽  
R. Benner ◽  
R. M. W. Amon
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
North Atlantic ◽  
The North ◽  
The North Atlantic

Dissolved organic carbon export and subsequent remineralization in the mesopelagic and bathypelagic realms of the North Atlantic basin

2010 ◽  
Vol 57 (16) ◽  
pp. 1433-1445 ◽  
Author(s):  
Craig A. Carlson ◽  
Dennis A. Hansell ◽  
Norman B. Nelson ◽  
David A. Siegel ◽  
William M. Smethie ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
North Atlantic ◽  
Carbon Export ◽  
Atlantic Basin ◽  
North Atlantic Basin ◽  
The North ◽  
The North Atlantic

scholarly journals Impacts of the North Atlantic Oscillation on stream water chemistry in mid-Wales

2004 ◽  
Vol 8 (3) ◽  
pp. 409-421 ◽  
Author(s):  
L. Ness ◽  
C. Neal ◽  
T. D. Davies ◽  
B. Reynolds
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Stream Water ◽  
Stream Chemistry ◽  
The North ◽  
Concentration Changes ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract. Analysis of winter stream chemistry data from the Afon Hafren in mid-Wales reveals links between stream chemistry and the North Atlantic Oscillation (NAO). K, Y, Al and dissolved organic carbon (DOC) concentrations increase during high NAO index months (relatively warm and wet weather), while Ca, Mg and NO3 concentrations increase during low NAO months (relatively cold and dry conditions) with the increased concentrations lasting into the next month. The cause of the concentration changes varies between constituents: Y, Al and DOC are impacted by short term variations in rainfall; Mg and Ca are influenced by flow conditions; and NO3 is temperature controlled. The dominant control mechanism for K concentration seems to be related to rainfall after tree felling has taken place but, prior to felling, the relationships are less certain. Keywords: nitrate, potassium, yttrium, aluminium, Dissolved Organic Carbon, magnesium, calcium, North Atlantic Oscillation, stream chemistry, Plynlimon, Hafren

Dissolved organic carbon as a component of the biological pump in the North Atlantic Ocean

1995 ◽  
Vol 348 (1324) ◽  
pp. 161-167 ◽  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
North Atlantic ◽  
Phytoplankton Bloom ◽  
Classical Model ◽  
Global Ocean ◽  
Data Set ◽  
The North ◽  
Biogenic Carbon ◽  
The North Atlantic

The North Atlantic is characterized by strong seasonality in mixed layer depths, resulting in winter recharge of surface layer nutrients and the spring phytoplankton bloom. This is the classical textbook model of seasonal cycles of oceanic biogeochemical processes, but in fact the North Atlantic is the exception rather than the rule. In much of the temperate and subpolar regions of the basin, the vernal accumulation of biomass is accompanied by a marked drawdown of inorganic carbon in the water column and pulses of particle flux to the seafloor. In the classical model, the decline of the C0 2 is balanced by accumulation of biogenic carbon and particle export. The main export mechanisms include sinking of ungrazed but possibly senescent phytoplankton and zooplankton grazing and egestion. Carbon budgets based on observations from the Joint Global Ocean Flux Study North Atlantic Bloom Experiment and Bermuda Atlantic Time Series cannot be closed using the elements of the classical model. That is, the C0 2 drawdown cannot be balanced by biomass accumulation and exports estimated by sediment traps. There are at least three possible routes toward reconciliation: (i) trap estimates are in error and systematically biased; (ii) spatial variability aliasses the observations making budgeting impossible without recourse to coupled three-dimensional models; and/or (iii) the classical model must be abandoned and replaced by a concept in which the accumulation and export of dissolved organic carbon assumes a major role in the North Atlantic carbon balance. At Bermuda, where the most complete data set exists, the weight of the evidence favours the first and third possibilities.

scholarly journals North Atlantic Western Boundary Currents Are Intense Dissolved Organic Carbon Streams

2020 ◽  
Vol 7 ◽  
Author(s):  
Marcos Fontela ◽  
Fiz F. Pérez ◽  
Herlé Mercier ◽  
Pascale Lherminier
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
North Atlantic ◽  
Gulf Stream ◽  
Western Boundary ◽  
Western Boundary Currents ◽  
Boundary Currents ◽  
The North ◽  
The North Atlantic

In the North Atlantic, there are two main western boundary currents related to the Atlantic Meridional Overturning Circulation (AMOC): the Gulf Stream flowing northward and the Deep Western Boundary Current (DWBC) flowing southward. Here we analyze data from the OVIDE section (GO-SHIP A25 Portugal-Greenland 40–60°N) that crosses the DWBC and the northward extension of the Gulf Stream, the North Atlantic Current. We show that North Atlantic western boundary currents play a key role in the transport of dissolved organic matter, specifically dissolved organic carbon (DOC). Revisited transports and budgets of DOC with new available data identify the eastern Subpolar North Atlantic (eSPNA) as an important source of locally produced organic matter for the North Atlantic and a key region in the supply of bioavailable DOC to the deep ocean. The East Greenland Current, and its upstream source the East Reykjanes Ridge Current on the eastern flank of the mid-Atlantic ridge, are export pathways of bioavailable DOC toward subtropical latitudes. The fast overturning and subsequent remineralization of DOC produced in the autotrophic eSPNA explains up to 38% of the total oxygen consumption in the deep North Atlantic between the OVIDE section and 24°N. Carbon budgets that do not take into account this organic remineralization process overestimates the natural uptake of carbon dioxide (CO2) from the atmosphere by one third. The inclusion of DOC transports in regional carbon budgets reconciles the estimates of CO2 uptake in the North Atlantic between model and observations.

scholarly journals The export flux of particulate organic carbon derived from <sup>210</sup>Po∕<sup>210</sup>Pb disequilibria along the North Atlantic GEOTRACES GA01 transect: GEOVIDE cruise

2019 ◽  
Vol 16 (2) ◽  
pp. 309-327 ◽  
Author(s):  
Yi Tang ◽  
Nolwenn Lemaitre ◽  
Maxi Castrillejo ◽  
Montserrat Roca-Martí ◽  
Pere Masqué ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
North Atlantic ◽  
Study Region ◽  
Vertical Advection ◽  
Export Flux ◽  
The North ◽  
Iberian Basin ◽  
Poc Export ◽  
The North Atlantic

Abstract. The disequilibrium between 210Po activity and 210Pb activity in seawater samples was determined along the GEOTRACES GA01 transect in the North Atlantic during the GEOVIDE cruise (May–June 2014). A steady-state model was used to quantify vertical export of particulate 210Po. Vertical advection was incorporated into one version of the model using time-averaged vertical velocity, which had substantial variance. This resulted in large uncertainties for the 210Po export flux in this model, suggesting that those calculations of 210Po export fluxes should be used with great care. Despite the large uncertainties, there is no question that the deficits of 210Po in the Iberian Basin and at the Greenland Shelf have been strongly affected by vertical advection. Using the export flux of 210Po and the particulate organic carbon (POC) to 210Po ratio of total (> 1 µm) particles, we determined the POC export fluxes along the transect. Both the magnitude and efficiency of the estimated POC export flux from the surface ocean varied spatially within our study region. Export fluxes of POC ranged from negligible to 10 mmol C m−2 d−1, with enhanced POC export in the Labrador Sea. The cruise track was characterized by overall low POC export relative to net primary production (export efficiency < 1 %–15 %), but relatively high export efficiencies were seen in the basins where diatoms dominated the phytoplankton community. The particularly low export efficiencies in the Iberian Basin, on the other hand, were explained by the dominance of smaller phytoplankton, such as cyanobacteria or coccolithophores. POC fluxes estimated from the 210Po∕210Pb and 234Th∕238U disequilibria agreed within a factor of 3 along the transect, with higher POC estimates generally derived from 234Th. The differences were attributed to integration timescales and the history of bloom events.

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