Organic matter continental shelf

Ransom, B., Bennett, R. J., Baerwald, R., and Shea, K. (1997). TEM study of in situ organic matter on continental shelf margins Occurrence and the monolayer hypothesis. Marine Geol. 138,1-9. 

Burrows, and transport of solute in them, may contribute to dissolution by enhancing oxic degradation of organic matter near the burrow walls. However, the situation is complex, and depending on factors such as the type of burrow wall produced, cementation rather than dissolution of carbonates may be promoted. Aller s observation that the best carbonate preservation takes place in the most physically disturbed and biologically underdeveloped environments points to the need for studies of continental shelf and slope environments where carbonate dissolution could be even more intense than that observed at the sites studied in Long Island Sound. 

Shum, K.T., and Sundby, B. (1996) Organic matter processing in continental shelf sediments—the subtidal pump revisited. Mar. Chem. 53, 81-87. 

Alongi, D. M. 1995. "Decomposition and recycling of organic matter in muds of the Gulf of Papua, northern Coral Sea." Continental Shelf Research 15 1319-1337. 

Pore-water nitrate profiles in marine sediments typically show one of three profile shapes. In sediment with rapid rates of organic matter oxidation relative to rates of solute supply from the overlying water, both oxygen and nitrate concentrations decrease more or less exponentially from overlying water concentrations at the sediment—water interface to zero, with oxygen depletion preceding or simultaneous with nitrate depletion at shallow sediment depth (see 105 m and 440 m profiles in Fig. 6.12). These types of profiles are common in continental shelf and upper slope sediments, and are due to relatively large carbon rain to the sediments (relatively... 

Kristensen, E., Devol, A. H., and Hartnett, H. E. (1999). Organic matter diagenesis in sediments on the continental shelf and slope of the eastern tropical and temprate North Pacific. Cont. Shelf Res. 19, 1331-1351. 

Romankevich, Ye.A. and Baturin, G.N., 1972. Composition of the organic matter in phosphorites from the continental shelf of southwest Africa. Geochem. Int., 9 464— 470. 

The surface runoff from the World s land plays an important role in the global carbon mass exchange. The continental runoff supply of HCO is 2.4 x 10 tons/year, that is, 0.47 x 10 tons/year for carbon. Besides, the stream water contains dissolved organic matter at 6.9 mg/L, which makes up to an annual loss of 0.28 x 10 tons/year. The average carbon concentration of suspended insoluble organic matter in the stream discharge is 5 mg/L, which gives the loss of about 0.2 x 10 tons/year. Most of this mass fails to reach the open ocean and becomes deposited in the shelf and the estuarine delta of rivers. We can see that equal amounts of Cc and Co (0.5 x 10 tons for each) are annually lost from the World s land surface (Dobrovolsky, 1994). 

Deposition of organic-rich sediments further down the shelf and on to the continental slope and rise often occurs as a result of turbidite flows, redistributing organic-rich sediments from delta fronts or from further up the shelf and slope (Summerhayes 1983). While there is a certain amount of pelagic sedimentation, primary production decreases away from the coastline as nutrient levels decline, and detritus is largely recycled before it settles to the sea floor. However, this may not always have been so in the past, when the thermohaline circulation (Box 3.2) did not operate and there may have been widespread anoxia in bottom waters, aiding preservation of sedimentary organic matter (e.g. Cretaceous oceanic anoxic events Section 6.3.4). 

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