Carbon accumulation rates

Figure 8A. Rates of sulfur and carbon accumulation are highly correlated in surface sediments of 11 Swiss lakes (23). The solid line is the regression line and the dotted lines represent 95% confidence intervals. Variations in the carbon accumulation rates represent differences in trophic status and...

As a closing remark, if we accept the carbon isotopic record of carbonates and organic carbon through geologic time as an index of the relative accumulation rates of inorganic and organic carbon on the sea floor, the carbonate carbon accumulation rate has been remarkably constant (Chapter 10). This near constancy has been maintained despite changes in Earth s surface physical and chemical environment and biotic evolution. 

An estimate of the calcium carbonate accumulation rate based on pilot unit experience is shown as the dashed line in Figure 7. This concept for calcium carbonate control is to be demonstrated in the 250 T/D pilot plant during operations on a subbituminous coal. 

Turekian K. K. and Stuiver M. (1964) Clay and carbonate accumulation rates in three South Atlantic deep-sea cores. Science 146, 55-56. 

Ruhlemann M., Frank M., Hale W., Mangini A., Multiza P., and Wefer G. (1996) Late Quaternary productivity changes in the western equatorial Atlantic evidence from h-normahzed carbonate and organic carbon accumulation rates. A/ar. Geol. 135, 127—152. 

The role of these marshes as a major carbon sink has been determined from the carbon content of the sediment, vertical accretion rates, and the bulk density of the sediment (Smith et al, 1983b). Accretion rates were calculated from depth in sediment of the horizon for 1963, the year of peak Cs fallout (DeLaune et al., 1978). Net carbon accumulation was essentially the same in all three marshes 183, 296, and 224 g C m year from the saltwater, brackish, and freshwater marshes, respectively. A large percentage of hxed carbon, immobilized in accretionary processes, remained on the marshes (Table 18.4). Hatton et al. (1983) found similar carbon accumulation rates in these marshes. 

It was found that both sediment and organic carbon accumulation rates are the highest in the inner shelf area (1.8 g C/(cm -yr) and 3.1 mg C/(cm -yr) for sediment and organic carbon accumulation rates, respectively). Sediment accumulation rates decreased offshore, whereas organic carbon accumulation... 

Event II was the main plankton extinction and productivity crisis coimected to the rapid collapse of the surface-to-deep water carbon isotope gradient and drops in barium and carbonate accumulation rates. Curiously, there was a hundredfold increase in the concentration of foraminifera relative to total carbonate. It could be due to intensified deep circulation with winnowing of the fine fraction. Or possibly to better the preservation of the dissolution-prone planktonic forms through deepening of the CCD and/or lowered rates of in situ dissolution caused by decreased decay of organic carbon in sediment pore waters. There is support for this idea from the fact that coccoHths tend to be more dissolution-resistant than foraminifera, also from calcite dissolution above the calcite saturation horizon is driven mainly by titration by metabolic carbon dioxide derived from organic carbon decay at or near the sediment-water interface. 

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