Material Fluxes on the Surface of the Earth (1994) / Chapter Skim
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Particle Fluxes in the Ocean and Implications for Sources and Preservation of Ocean Sediments
Particle Fluxes in the Ocean and Implications for Sources and Preservation of Ocean Sediments
Pages 125-142
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From page 125... ...
Strong offshore decrease in carbon rain rate and preservation demonstrate the importance of the continental margin as a region of enhanced organic carbon burial. These effects produce a factor of 60 change in carbon burial rate over a 600 km offshore transect in the North East Pacific.
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From page 126... ...
Consequently, the burial rates of elements and compounds generally do not equal the particulate rain rate. A major focus of this paper will be the comparison between the burial rate of materials that form the sediment record and the rain rate of particles that settle through the water column.
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From page 127... ...
We report particle fluxes and burial rates for 11 sites (Figure 9.1; Tables 9.2-9.4~. There are four equatorial Pacific sites (H.
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From page 128... ...
to extrapolate the rain rate to bottom depths. Temporal variations in the particle flux provide another complication to estimating the particulate rain to the bot
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From page 129... ...
For these elements the burial rate should be equal to the rain rate. At most sites fluxes of refractory elements increase with depth in the water column.
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From page 130... ...
Except for HAP the small differences between rain and burial rates for refractory elements are probably a consequence of comparing rain rates from a single year to the 103 to 1os yr time scale that is integrated by sediment accumulation rate measurements. Some differences could be due to imperfect collection efficiencies by sediment traps.
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From page 131... ...
is new production (Platt and Harrison, 1985~. One consequence of higher ratios of new to total primary productivity in more productive sites is that the rain rates of organic matter magnify the pattern of primary productivity variations.
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From page 132... ...
High apparent preservation could be due to deep lateral inputs of particulate organic matter (Jahnke et al., 19901. Other possible explanations for high preservation near the continents include the presence of refractory terrestrial organic matter in the organic fraction, the loss of an extremely labile fraction of organic carbon from the sediment trap material after collection, or a coupling between sedimentary mass accumulation rate and the preservation of the organic carbon fraction.
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From page 133... ...
Thus, if lateral transport has been important for the organic carbon flux, it must be occurring deeper than the deepest traps on our moorings, nominally 500 m above the seafloor. Because the measured rain rates of aluminum in NS and MFZ traps agree within a factor of two with the aluminum burial rates (Table 9.3)
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From page 134... ...
Filled square is Nares Abyssal Plain; open squares are California Current sites; diamonds are Equatorial Pacific Sites. o 1 000 Depth (m)
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From page 135... ...
The effects of metabolic CO2 production are a function of the 135 FIGURE 9.9 The percentage of organic carbon rain rate that is preserved versus the rain rate of organic carbon. Filled square is Nares Abyssal Plain; open squares are California Current sites; diamonds are Equatorial Pacific Sites.
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From page 136... ...
THE RELATIONSHIP BETWEEN ALUMINOSILICATE AND BIOGENIC RAIN RATES 20 1 5 %Opal 10 Preserved The aggregation of clays into larger, more rapidly settling particles is necessary to account for the discrete patterns of clay mineral distributions in deep ocean sediments. The direct relationship between the flux of organic FIGURE 9.1 1 Organic carbon flux versus Al flux for site S samples.
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From page 137... ...
This approach overcomes problems that result from errors in the mass accumulation rate or trap efficiency. It is functionally equivalent to computing a correction factor for the rain rates that would make the rain rates of Al the same as the burial rate in sediments.
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From page 138... ...
Atlantic HAP 1.6 0.1 3.7 23.5 3.0 12.9 3.8 0.4 11 NAP 0.9 0.0 3.5 9.2 0.6 6.7 2.0 0.0 0.83 Pacific MFZ 0.6 0.1 17 2.5 0.2 9.0 3.9 0.4 10.4 JDF 3.6 0.4 12.3 38.2 6.4 17 24 2.5 10.7 NS 0.5 0.2 33 1.6 0.1 6.8 5.1 1.1 22.5 MW 1.1 0.2 15 4.6 0.3 7.1 8.3 0.6 7.8 G 4.5 0.1 2.3 21.0 0.6 2.8 17 0.6 3.9 H 12.7 0.1 1.0 181.3 0.2 0.1 55 2.6 4.6 M 9.1 0.3 2.9 43.6 3.0 6.8 47 2.1 4.5 S 16.70 0.1 0.4 301.1 0.1 0.05 192 2.7 1.4 C 24.0 0.5 2.2 386.9 133.8 35 198 24 11.9 (Table 9.4~. In addition, the mass accumulation rate is more than a factor of two greater than the total rain rate (Table 9.2~.
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From page 139... ...
INFLUENCE OF THE CONTINENTAL MARGINS The biogenic fluxes and preservation rates that we have computed indicate the importance of continental margins as a major removal site of biogenic material from the ocean. The large decrease in rain rate of biogenic material combined with the apparently greater preservation of these components (particularly organic carbon and opal)
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From page 140... ...
Data from the Nares Abyssal Plain suggest that eolian sources are more important here than for any of our Pacific sites. Although this site is more than 1000 km from the nearest continental margin, the aluminum rain rate is higher than that measured for the more near shore HAP site.
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From page 141... ...
(19841. Sediment traps, particle fluxes, and benthic boundary layer processes, in Global Ocean Flux Study, Proceedings of a Workshop, National Academy Press, Washington, D.C., pp.
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From page 142... ...
The fecal pellet fraction of biogeochemical particle fluxes to the deep sea, Global Biogeochemical Cycles 1, 31-48. JACK DYMOND AND MITCHELL LYLE Platt, T., and W
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