The Influence of CaCO<sub>3</sub> Dissolution on Core Top Radiocarbon Ages for Deep‐Sea Sediments

Broecker, Wallace S.; Klas, Mieczyslawa; Clark, Elizabeth; Bonani, Georges; Ivy, Susan; Wölfli, W.

doi:10.1029/91pa01768

Cited by 66 publications

(60 citation statements)

References 29 publications

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“…Similar distributions of foraminiferal core-top ages, i.e. older ages in more corrosive waters, have been reported by Broecker et al (1991). These authors, however, have not offered a steady-state explanation for this observation.…”

supporting

confidence: 57%

Rapid lateral particle transport in the Argentine Basin: Molecular 14C and 230Thxs evidence

Mollenhauer

McManus

Benthien

et al. 2006

Deep Sea Research Part I: Oceanographic Research Papers

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Recent studies have revealed that lateral transport and focusing of particles strongly influences the depositional patterns of organic matter in marine sediments. Transport can occur in the water column prior to initial deposition or following sediment re-suspension. In both cases, fine-grained particles and organic-rich aggregates are more susceptible to lateral transport than coarse-grained particles (e.g. foraminiferal tests) because of the slower sinking velocities of the former. This may lead to spatial and, in the case of redistribution of resuspended sediments, temporal decoupling of organic matter from coarser sediment constituents. Prior studies from the Argentine Basin have yielded evidence that suspended particles are displaced significant distances (100 -1000 km) northward and downslope by strong surface and/or bottom currents. These transport processes result in anomalously cold alkenone-derived sea surface temperature (SST) estimates (up to 6°C colder than measured SST) and in the presence of frustules of Antarctic diatom species in surface sediments from Thxs-based focusing factors of 1.4 to 3.2 at sites where alkenone-based SST estimates were 4 -6 °C colder than measured values. In contrast, alkenone radiocarbon data suggest coeval deposition of marine biomarkers and planktic foraminifera, as alkenones in core-tops were younger than, or similar in age to, foraminifera. We therefore infer that the transport processes leading to the lateral displacement of these sediment components are rapid, and hence probably occur in the upper water column (< 1500 m).

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supporting

confidence: 57%

Rapid lateral particle transport in the Argentine Basin: Molecular 14C and 230Thxs evidence

Mollenhauer

McManus

Benthien

et al. 2006

Deep Sea Research Part I: Oceanographic Research Papers

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“…In spite of the scarcity of data, the preceding discussion clearly indicates that the variance in the estimates of respiration rates in the bathypelagic ocean and sediments, where mixing is a minor source of error, is considerablly lower than that in the mesopelagic zone. Fiadeiro and Craig (1978) calculated a rate of respiration for the whole water column below 1000 m of 2 µl O 2 l −1 a −1 (0.24 µmol O 2 m −3 d −1 ), similar to other estimates available for the ocean interior based on oxygen fields and large-scale models (Riley 1951;Munk 1966;Broecker et al 1991). These rates are comparable in magnitude to the deep-water estimates derived from oxygen consumption in sediments (Table 10.5), but considerablly lower than estimates derived from ETS measurements (Table 10.3).…”

Section: Synthesis: Budgeting Respiration In Dark Oceanmentioning

confidence: 71%

Respiration in the mesopelagic and bathypelagic zones of the oceans

Arı́stegui¹,

Agustı́²,

Middelburg³

et al. 2005

Respiration in Aquatic Ecosystems

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OutlineIn this chapter the mechanisms of transport and remineralization of organic matter in the dark water-column and sediments of the oceans are reviewed. We compare the different approaches to estimate respiration rates, and discuss the discrepancies obtained by the different methodologies. Finally, a respiratory carbon budget is produced for the dark ocean, which includes vertical and lateral fluxes of organic matter. In spite of the uncertainties inherent in the different approaches to estimate carbon fluxes and oxygen consumption in the dark ocean, estimates vary only by a factor of 1.5. Overall, direct measurements of respiration, as well as indirect approaches, converge to suggest a total dark ocean respiration of 1.5-1.7 Pmol C a −1 . Carbon mass balances in the dark ocean suggest that the dark ocean receives 1.5-1.6 Pmol C a −1 , similar to the estimated respiration, of which >70% is in the form of sinking particles. Almost all the organic matter (∼92%) is remineralized in the water column, the burial in sediments accounts for <1%. Mesopelagic (150-1000 m) respiration accounts for ∼70% of dark ocean respiration, with average integrated rates of 3-4 mol C m −2 a −1 , 6-8 times greater than in the bathypelagic zone (∼0.5 mol C m −2 a −1 ). The results presented here renders respiration in the dark ocean a major component of the carbon flux in the biosphere, and should promote research in the dark ocean, with the aim of better constraining the role of the biological pump in the removal and storage of atmospheric carbon dioxide.

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“…The age of the C 16 FA in the mixed layer mainly reflects the balance between the bioturbation rate and degradation rate of this compound. Using a model analogous to the CaCO 3 dissolution and mixing (Broecker et al 1991), the 14 C age of the FA will correspond with the post-bomb DIC reservoir age if the FA reaching the sea floor is rapidly (within a few yr) mixed and if its half-life in the mixed layer is less than 30 yr. The latter is a reasonable assumption based on studies of FA degradation in marine sediments (Canuel and Martens 1996).…”

Section: Resultsmentioning

confidence: 99%

Radiocarbon Dating of Individual Fatty Acids as a Tool for Refining Antarctic Margin Sediment Chronologies

Ohkouchi

Eglinton

Hayes³

2003

Radiocarbon

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ABSTRACT. We have measured the radiocarbon contents of individual, solvent-extractable, short-chain (C 14 , C 16 , and C 18 ) fatty acids isolated from Ross Sea surface sediments. The corresponding 14 C ages are equivalent to that of the post-bomb dissolved inorganic carbon (DIC) reservoir. Moreover, molecular 14 C variations in surficial (upper 15 cm) sediments indicate that these compounds may prove useful for reconstructing chronologies of Antarctic margin sediments containing uncertain (and potentially variable) quantities of relict organic carbon. A preliminary molecular 14 C chronology suggests that the accumulation rate of relict organic matter has not changed during the last 500 14 C yr. The focus of this study is to determine the validity of compound-specific 14 C analysis as a technique for reconstructing chronologies of Antarctic margin sediments.

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The Influence of CaCO₃ Dissolution on Core Top Radiocarbon Ages for Deep‐Sea Sediments

Cited by 66 publications

References 29 publications

Rapid lateral particle transport in the Argentine Basin: Molecular 14C and 230Thxs evidence

Rapid lateral particle transport in the Argentine Basin: Molecular 14C and 230Thxs evidence

Respiration in the mesopelagic and bathypelagic zones of the oceans

Radiocarbon Dating of Individual Fatty Acids as a Tool for Refining Antarctic Margin Sediment Chronologies

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The Influence of CaCO3 Dissolution on Core Top Radiocarbon Ages for Deep‐Sea Sediments

Cited by 66 publications

References 29 publications

Rapid lateral particle transport in the Argentine Basin: Molecular 14C and 230Thxs evidence

Rapid lateral particle transport in the Argentine Basin: Molecular 14C and 230Thxs evidence

Respiration in the mesopelagic and bathypelagic zones of the oceans

Radiocarbon Dating of Individual Fatty Acids as a Tool for Refining Antarctic Margin Sediment Chronologies

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The Influence of CaCO₃ Dissolution on Core Top Radiocarbon Ages for Deep‐Sea Sediments