Overview of LOICZ Approach to Estimating CNP Fluxes in the Coastal Ocean

S. V. Smith

March 2000

            This website aims to lay out a robust, widely applicable, uniform methodology that has minimal data requirements and that can work with secondary data. Details are spelled out in Gordon et al. (1996). In broad summary, water and salt budgets are used to estimate water exchange in coastal systems. Nutrient budgets (as a minimum, dissolved inorganic phosphorus and dissolved inorganic nitrogen) are also developed, and departure of the nutrient budgets from conservative behaviour is a measure of net system biogeochemical fluxes. Nonconservative flux of dissolved inorganic phosphorus, scaled by an estimate of the carbon:phosphorus ratio of the reacting material, is used to estimate primary production minus respiration (p-r). The discrepancy between the observed nonconservative flux of dissolved nitrogen, scaled by the N:P ratio of the reacting organic matter, is used as an estimate of nitrogen fixation minus denitrification (nfix-denit). While this is clearly a great simplification of the details of processes and reaction pathways in ecosystems, it provides some insight into possible net reactions accounting for nutrient uptake and release. This approach is preferred to estimates based on carbon flux, because carbon data are available for relatively few systems. Similarly, “direct estimates” of production, respiration, nitrogen fixation, and denitrification are difficult to obtain at system scales.

            The LOICZ strategy to deal with estimating these CNP fluxes for the global coastal zone is to develop a global inventory of these budgets. To date, about 110 sites have been budgeted, and a total number of 200 seems to be a feasible final number. A global “typology” (or classification) of the coastal zone, or perhaps a series of typologies, will be used to extrapolate from the budget sites to the remainder of the coastal zone. Literature research, workshops, and information sharing via the World Wide Web are the major tools being used to develop the budget database. These workshops are being funded by UNEP/GEF, LOICZ, and other sources. UNEP/GEF has provided funds for a series of local budget, regional typology, and global synthesis workshops. The South Asia workshop held in Goa, India, marked the third workshop to be completed in this series.

            The interested reader is encouraged to browse these pages.  A short summary of the LOICZ CNP budgeting procedure in a Microsoft PowerPoint presentation may be viewed or downloaded by clicking here. (en español)  A presentation of a simple approach for estimating river discharge may be seen here. (en español)  A more detailed PowerPoint tutorial on aspects of the budgeting methodology including some examples is available here . Here is a bit of background on the modeling methodology in Spanish (Antecedentes Generales del Modelo en español).  A PowerPoint tutorial on estimating nutrient loads to coastal areas from the waste streams of various human activities can be found here.  The associated spreadsheet for use in estimating these loads is here.

        Cabaret (Computer Assisted Budget Analysis for Research, Education, and Training) is a stand-alone program  for computer platforms runnning MS-Windows developed to assist the user to create nutrient budgets for coastal ecosystems.  An introduction to Cabaret  in PowerPoint format is available here.  A compressed version of  Cabaret V2001 (cb042001.exe) can be downloaded by clicking here.   It is an executable file which can be unpacked by double-clicking on the icon.   The file Cabaret.exe can then be run by double-clicking on its icon.

Back to [Node Introduction] [Table of Contents] [LOICZ]

Last Updated 12 May 2009 by DPS