Carbonate continental shelf

Mayer, L.M. 1994. Surface area control of organic carbon accumulation in continental shelf sediments. Geochimica et Cosmochimica Acta 58 1271-1284. 

Continental shelf pump Export processes that serve to transport carbon from the coastal margins to the open ocean. 

Gustafsson, O., and P. M. Gschwend, The flux of black carbon to surface sediments on the New England continental shelf , Geochim. Cosmochim. Acta, 62,465-472 (1998). 

Snohvit will also be the first major development on the Norwegian continental shelf without support from a floating unit. A sub sea production system on the seabed will feed the land-based LNG plant via a 0.68 m ID, 160 km two-phase pipeline. In addition two chemical lines, an umbilical and a separate pipeline for the transport of carbon dioxide will be included. The unprocessed well stream from Snohvit is separated and the gas is treated and cooled to a temperature below the boiling point (-162 °C) to form LNG. This operation employs a large cold box (40 m high and a footprint of 15x17 meter). 

Longhurst, A.R., 1983. Benthic-pelagic coupling and export of organic carbon from a tropical Atlantic continental shelf - Sierra Leone. Estuar. coastl. Shelf Sci., 17 261-285. 

Curl, H., Standing crops of carbon, nitrogen, phosphorus and transfer between trophic levels in continental shelf waters south of New York, Rapp. Proc.-Verb. Cons. Int. Explor. Men, 153, 183, 1962. 

Other reactions of probable less importance than those above leading to undersaturated conditions with respect to calcium carbonate near the sediment-water interface include nitrate reduction and fermentation (e.g., Aller, 1980). Such reactions may also be important near the sediment-water interface of continental shelf and slope sediments, where bioturbation and bioirrigation can result in enhanced transport of reactants. Generally, as water depth increases over continental slope sediments, the depth within the sediment at which significant sulfate reduction commences also increases. It is probable that the influence of reactions other than sulfate reduction on carbonate chemistry may increase with increasing water depth. 

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. 

While the coastal ocean has been largely ignored in global carbon budgets, recent work has shown that shelf regions may actually be CO2 sinks recently referred to as the continental shelf pump, that may account for as much as -0.95 Pg C y 1. 

Aller, R. C., N. E. Blair, Q. Xia, and P. D. Rude. 1996. "Remineralization rates, recycling, and storage of carbon in Amazon shelf sediments." Continental Shelf Research 16 753-786. 

DeMaster, D. J., W. O. Smith, Jr., D. M. Nelson, and J. Y. Alien 1996. "Biogeochemical processes in Amazon shelf waters chemical distributions and uptake rates of silicon, carbon, and nitrogen." Continental Shelf Research 16 617-643. 

Showers, W. J., and D. G. Angle. 1986. "Stable isotopic chaiacterization of organic carbon accumulation on the Amazon continental shelf." Continental Shelf Research 6, 227-244. 

Laursen, A. E., and Seitzinger, S. P. (2002). The role of denitrification in nitrogen removal and carbon mineralization in Mid-Atlantic Bight sediments. Continental Shelf Research 22, 1397—1416. 

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... 

Rao, A. M. P., McCarthgy, M. J., Gardner, W. S., andjahnke, R. (2007). respiration and denitrification in permeable continental shelf deposits on the South Atlantic Bight Rates of Carbon and nitrogen cycling from sediment column experiments. Continental shey Res. 27, 1801—1819. 

Shiah, P. K., Gong, G. C., and Chen, C. C. (2003). Seasonal and spatial variation of bacterial production in the continental shelf of the East China Sea Possible controlhng mechanisms and potential roles in carbon cycling. Deep Sea Res. Part II—Top. Stud. Oceanogr. 50, 1259—1309. 

Marine DOC has stable carbon isotope values between —21%o and —22%o (Dmtfel et al., 1992) consistent with a largely marine source. While these data seem to exclude a significant contribution from C3 terrestrial plants, there is increasing evidence for an important contribution from C4 plants to persistent POM in marine sediments on the continental shelf and slope (see below). Desorption of C4 plant carbon and incorporation into oceanic DOC would be difficult to detect by isotopic or molecular biomarker analyses. 

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