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.

Relationships among Tubificid Abundances, Sediment Composition, and Accumulation Rates in Lake Erie

1989 ◽  
Vol 46 (2) ◽  
pp. 223-231 ◽  
Author(s):  
J. A. Robbins ◽  
T. Keilty ◽  
D. S. White ◽  
D. N. Edgington
Keyword(s):  
Organic Carbon ◽  
Carbon Flux ◽  
Lake Erie ◽  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Tubifex Tubifex ◽  
Sediment Reworking ◽  
Organic Carbon Flux ◽  
Limnodrilus Hoffmeisteri

Sediment cores taken at 15 sites within the three main depositional basins of Lake Erie from 1976 to 1982 were sectioned in 1-cm intervals and analyzed for the abundance and vertical distribution of benthic organisms, 137Cs, and 210Pb (in some cores) and for surficial (upper 2 cm) organic and inorganic carbon. Zoobenthos populations were dominated (>85%) by tubificids (Limnodrilus hoffmeisteri, Quistadrilus multisetosus, and Tubifex tubifex) and varied in abundance from 6600 to 55 300 individuals∙m−2. The depth above which 90% of the individuals occurred correlated significantly with their abundance and with radiometrically determined mixed depths. Rates of sediment reworking by tubificids exceeded sedimentation rates by 5–80 times, indicating that worms alone can produce the observed zone of constant tracer activity at the sediment–water interface. Tubificid abundance was not significantly related to organic carbon but instead correlated strongly with the sediment accumulation rate and organic carbon flux. In Lake Erie the abundance of tubificids may be limited by the rate of supply of nutrients as measured roughly in terms of the organic carbon flux.

scholarly journals Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

2009 ◽  
Vol 6 (1) ◽  
pp. 85-102 ◽  
Author(s):  
G. Fischer ◽  
G. Karakaş
Keyword(s):  
Organic Carbon ◽  
Atlantic Ocean ◽  
Sediment Trap ◽  
Carbon Flux ◽  
Coastal Upwelling ◽  
Production Systems ◽  
Deep Ocean ◽  
Biogeochemical Model ◽  
Carbonate Content ◽  
Organic Carbon Flux

Abstract. The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opal-rich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of 0.29 Tg per year down to 3000 m off the NW African upwelling region between 5 and 35° N. Simple parameterisations of remineralisation and sinking rates in such models, however, limit their capability in reproducing the flux variation in the water column.

Mechanism and geochemical implications of the Late Holocene organic carbon burial event: an example from the southwest coast of India

2009 ◽  
Vol 59 (7) ◽  
pp. 1409-1416 ◽  
Author(s):  
B. Ajaykumar ◽  
Mahesh Mohan ◽  
M. S. Shylesh Chandran ◽  
K. K. Jayasooryan ◽  
K. S. Unni ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Late Holocene ◽  
Southwest Coast Of India ◽  
Southwest Coast ◽  
Carbon Burial ◽  
Organic Carbon Burial

scholarly journals Fluvial organic carbon flux from an eroding peatland catchment, southern Pennines, UK

2008 ◽  
Vol 12 (2) ◽  
pp. 625-634 ◽  
Author(s):  
R. R. Pawson ◽  
D. R. Lord ◽  
M. G. Evans ◽  
T. E. H. Allott
Keyword(s):  
Organic Carbon ◽  
Carbon Flux ◽  
Relative Importance ◽  
Carbon Export ◽  
Event Scale ◽  
Organic Carbon Flux ◽  
Poc Export ◽  
Event Based ◽  
First Time ◽  
Annual Flux

Abstract. This study investigates for the first time the relative importance of dissolved organic carbon (DOC) and particulate organic carbon (POC) in the fluvial carbon flux from an actively eroding peatland catchment in the southern Pennines, UK. Event scale variability in DOC and POC was examined and the annual flux of fluvial organic carbon was estimated for the catchment. At the event scale, both DOC and POC were found to increase with discharge, with event based POC export accounting for 95% of flux in only 8% of the time. On an annual cycle, exports of 35.14 t organic carbon (OC) are estimated from the catchment, which represents an areal value of 92.47 g C m−2 a−1. POC was the most significant form of organic carbon export, accounting for 80% of the estimated flux. This suggests that more research is required on both the fate of POC and the rates of POC export in eroding peatland catchments.

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