Phosphorus coastal fluxes

Human activity has an enormous influence on the global cycling of nutrients, especially on the movement of nutrients to estuaries and other coastal waters. For phosphorus, global fluxes are dominated by the essentially one way flow of phosphorus carried in eroded materials and wastewater from the land to the oceans, where it is ultimately buried in ocean sediments. The size of this flux is currently estimated at 22 x 106 tons per year. Prior to increased human agricultural and industrial activity,... 

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. 

Coelho, J.P., Flindt, M.R., Jensen, H.S., Lillebo, A.I., and Pardal, M.A. (2004) Phosphorus speciation and availability in intertidal sediments of a temperate estuary relation to eutrophication and annual P-fluxes. Estuar. Coastal Shelf Sci. 61, 583-590. 

Mobilization of sedimentary phosphorus by microbial activity during diagenesis causes dissolved phosphate buildup in sediment pore waters, promoting benthic efflux of phosphate to bottom waters or incorporation in secondary authigenic minerals. The combined benthic flux from coastal (sFcbf) and abyssal (sFabf) sediments is estimated to exceed the total riverine-P flux (F24(d+p>) to the ocean. Reprecipitation of diagenetically mobilized phosphorus in secondary phases significantly enhances phosphorus burial efficiency, impeding return of phosphate to the water column (see Section 8.13.3.3.2). Both processes impact the... 

One recent example is The Land Ocean Interactions in the Coastal Zone (LOICZ) Project, a core project of the International Geosphere-Biosphere Program (IGBP), whose stated goals include a determination of nutrient fluxes between land and sea (with emphasis on carbon, phosphorus, and nitrogen), and an assessment of how coastal systems respond to varying terrestrial inputs of nutrients (Gordon et al., 1996 Smith, 2001). 

Smith S. V. (2001) Carbon-nitrogen-phosphorus fluxes in the coastal zone the LOICZ approach to global assessment, and scaling issues with available data. LOICZ Newsletter, December 2001, no. 21, pp 1-3. 

The difference the field methodology makes to the estimation of the nutrient flux between a saltmarsh and coastal water can be illustrated using studies conducted on North Inlet marsh. South Carolina. Wolaver Spurrier (1988), used the flume technique to estimate the budget for a whole marsh. They concluded that North Inlet marsh imported both phosphate and particulate phosphorus. However, an earlier direct tidal... 

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

Both fossil fuel combustion and agricultural practices contribute significantly to atmospheric fluxes of nitrogen but not phosphorus. The magnitude of the contribution of these atmospheric fluxes to coastal nutrient pollution remains uncertain, and understudied. Nonetheless, atmospheric deposition is clearly an important contributor to coastal nutrient pollution. This source... 

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