Oceanic deposits

The ocean plays a central role in the hydro-spheric cycling of sulfur since the major reservoirs of sulfur on the Earth s surface are related to various oceanic depositional processes. In this section we consider the reservoirs and the fluxes focusing on the cycling of sulfur through this oceanic node. 

Consolidated ocean deposits, 17 691-694 Consolidation Synthetic Fuels (CSF) process, 6 848... 

Unconsolidated ocean deposits, 17 686-691 Uncontrolled variables, 3 388-389 Uncouplers, 14 349 Uncoupling proteins... 

There is other evidence that montmorillonites are not always stable at shallower levels of ocean deposition environments. The following conversions have been observed or deduced ... 

Oceanic Deposits and Guanos.—Guano.—This valuable natural manure is produced from the excrement of sea-birds, and occasionally of other animals, which has been chemically altered by ex-1 Pietvkowsky, NaMmoiss., 1922, lo, 350. 2 Chemical Age, 1931, p. 2S1. 

The broad implication of these observations is that somewhere between upper continental margins and the deep ocean, depositional conditions lead to greatly increased exposure times of sedimentary organic matter to O2 that are... 

A limited amount of work has been done on the dating of shallow-water nodules, which, because of diagenetic remobihzation of manganese within the sediment column, generally form more rapidly than deep-ocean deposits. Unlike deep-water nodules, the rapidly growing shallow-water nodules do not contain excess °Th or Pa but instead contain, initially, quantities of °Th and Pa that are less than their equilibrium... 

The Global Mercury Cycle A recent review (Mason et al., 1994) on the global Hg cycling is diagrammed in Figure 10.24. The evasion of Hg from the ocean is balanced by the total oceanic deposition of Hg(II) from the atmosphere. The mechanisms, whereby reactive Hg species are reduced to volatile Hg in the oceans, are poorly known, but reduction appears to be biologically mediated. Deposition on land is the dominant sink for atmospheric Hg. Mason et al. (1994) estimate that over the last century anthropogenic emissions have tripled the concentration of Hg in the atmosphere and in the surface ocean. 

Baranov, V.l. and Khristianova, L.A., 1966. Radioactivity of ocean deposits. Chemistry of the Earth s Crust, pp. 425-432 (translated from Russian). 

Fig. 7.9 Titanium concentrations in the ocean deposits of the Cariaco Basin, Venezuela, annually laminated marine sediments (left) and gypsum concentration in the sediments from Lake Chichancanab in the Northern Yucatan (right). Higher amounts of titanium and increased gypsum concentrations reflect decreased rainfall. The time period is from approximately ad 730-930. Three major episodes of drought are observed at ad 810, 860, and 910...

If the oceanic deposition of carbonate minerals plays a significant role in the removal of anthropogenic CO2 from the atmosphere, then it is unlikely that the process would saturate. Thus, the relations on which the FAC Model are based would continue over the duration that the FAC Model has been applied and longer. If ocean carbonate deposition is a removal mechanism, it would assure that the FAC Model is valid and its projections reasonable if the projections of future anthropogenic CO2 emissions are reasonable. 

Most, but not all, of this carbonate has been an oceanic deposit, deriving the necessary CO2 from the atmospheric-oceanic CO2 store. The amount that is at present in this store is, however, only a very small fraction of the amount required to lay down the carbonates present in the geological record. The atmospheric-oceanic reservoir at present holds only about 0.05% of the earth s carbon (cf Table 2.12). 

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