Coastal margins

The model-calculated partitioning of the human-induced perturbation fluxes In the global coastal margin of (a) nitrogen and (b) phosphorus for the period from 1850 to the present (2000) and projected to 2035 under the business-as-usual scenario, In units of lO mol/y and Mtons/y. The anthropogenic sources are plotted on the (-) side and the resulting accumulations and enhanced export fluxes are plotted on the +) side. Source-. From Mackenzie, F. T, et al. (2002). Chemical Geology 190, 13-32. 

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

A further area in which sequential extraction continues to be applied successfully is in assessment of the likelihood of mobilisation of metal contaminants from sediment-derived soil. When dredged sediment is used to reclaim land from the coastal margins or applied to arable soil to improve fertility, there is concern that potentially toxic elements accumulated under reducing conditions may be released on exposure to an oxygen-rich environment. Sequential extraction can be used to characterise the sediment prior to application, or to monitor changes in metal availability in the soil with time (e.g. Singh et al, 1998). 

Flux estimates related to the modern carbon cycle require refinement, particularly those involving coastal margin and other shoal-water area inputs and outputs. 

Lignins are a group of macromolecular heteropolymers (600-1000 kDa) found in the cell wall of vascular plants that are made up of phenylpropanoid units. Lignin has proven to be a useful chemical biomarker for vascular-plant inputs to estuarine/coastal margin sediments. Cellulose, hemicellulose, and lignin generally make up > 75% of the biomass of woody plant materials. 

The world s 25 largest rivers transport approximately 40% of the fresh water and particulate materials entering the ocean (Milliman and Meade, 1983 Meade, 1996) (also see tables 4.2 and 4.3). Rivers transport an estimated 20 Pg y 1(l Pg = lO1 = 1 gigaton) of fluvial sediments to the coastal margin (Meybeck, 1982 Meade, 1996) associated with this sediment loading is an estimated 0.21 Pg of POC y-1 (Hedges and Keil,... 

Some of the biological responses to SGD inputs of nutrients to the coastal margin include eutrophication, the occurrence of HABs, and macroalgal invasions. 

Bianchi, T.S., Argyrou, M., and Chipett, H.F. (1999b) Contribution of vascular-plant carbon to surface sediments across the coastal margin of Cyprus (eastern Mediterranean). Org. Geochem. 30, 287-297. 

Bianchi, T.S., Mitra, S., and McKee, M. (2002b) Sources of terrestrially-derived carbon in the Lower Mississippi River and Louisiana shelf Implications for differential sedimentation and transport at the coastal margin. Mar. Chem. 77, 211-223. 

Case Study V - Iodine monoxide chemistry in the coastal margins -Figure 23 shows the measured concentration of iodine monoxide (lO)... 

Figure Fidelity of sedimentary as a recorder of coastal margins. This plot...

OCS (Zhang et al, 1998). A range of factors, such as temperature and biological activity, drive the variability in emission flux, but work at the coastal margins suggests that salinity is a very important control (DeLaune et al, 2002). 

Gohn, G.S., Christopher, R.A., Smith, C.C. and Owens, J.P., 1978. Preliminary stratigraphic cross sections of Atlantic Coastal Plain sediments of the southeastern United States, Part A, Cretaceous sediments along the South Carolina coastal margin. U.S. Geol. Surv, Misc. Field Stud. Map, MF-1015-A. 

Figure 2 Past, present, and predicted fluxes of carbon, nitrogen, and phosphorus into or out of the global coastal margin, in lO molyr ...

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