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C N P Fluxes in the Coastal Zone

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Presentation on theme: "C N P Fluxes in the Coastal Zone"— Presentation transcript:


2 C N P Fluxes in the Coastal Zone
The LOICZ Approach to Budgeting and Global Extrapolation S. V. Smith U. Hawaii March 2000

3 What is the role of the coastal ocean in global CNP cycles?
Easier to quantify globally than locally: Via global loading budgets; Little understanding of distribution or controls. Function of biota and inorganic reactions; Function of environmental conditions: F(land inputs, oceanic exchanges); F(human pressures); F(regional, global environmental change). An environmentally important question that can be approached via geochemical reasoning.

4 General Background

5 Only a small portion lies in the “LOICZ domain.”
Global Elevation Only a small portion lies in the “LOICZ domain.”

6 Coastal Zone (+200 to –200 m) This domain is nominally m to -200 meters, or about 18% of global area.

7 Coastal Ocean (0 to –200 m) The coastal ocean, being budgeted by LOICZ, is about 5% of global area.

8 The Global Coastal Ocean: A Narrow, Uneven, Chemically Reactive “Ribbon”
LAND OCEAN This ribbon is ~ 500,000 km long and averages about 50 km in width. Most materials entering the ocean from land pass through this ribbon. Most net biogeochemical reaction is thought to occur in the landward, estuarine, portion of the ribbon.

9 LOICZ and IGBP IGBP is the “International Geosphere-Biosphere Programme.” Part of ICSU, the International Council of Scientific Unions LOICZ is “Land-Ocean Interactions in the Coastal Zone.” A key project element of IGBP

10 IGBP: International Geosphere-Biosphere Programme
IGBP aim --To describe and understand the interactive physical, chemical and biological processes that regulate the Earth System, the environment provided for life, the changes occurring in the system, and the influences of human actions. LOICZ aim -- About the same as IGBP aim —for the coastal zone.

11 Alphabet Soup of the IGBP
JGOFS Joint Global Ocean Flux Studies IGAC International Global Atmospheric Chemistry GCTE Global Change and Terrestrial Ecosystems BAHC Biospheric Aspects of the Hydrological Cycle PAGES Past Global Change LOICZ Land-Ocean Interactions in the Coastal Zone LUCC Land Use and Cover Change GLOBEC Global Ocean Ecosystem Dynamics __________________________________________________ GAIM Global Analysis, Integration and Modelling START System for Analysis, Research, and Training DIS Data and Information System

12 LOICZ Budgeting Background

13 Develop a “Globally Applicable” Method of Flux Estimation
Ability to work with secondary data; Minimal data requirements; Widely applicable, uniform methodology; Robust; Informative about processes of CNP flux.

14 LOICZ Budgeting Procedure
Conservation of mass is one of the most fundamental concepts of ecology and geochemistry.

15 Water, Salt, and “Stoichiometrically Linked” Nutrient Budgets
Water and salt budgets are used to estimate water exchange in coastal systems. Departure of nutrient budgets from conservative behavior measures “system biogeochemical fluxes.” Nonconservative DIP flux is assumed proportional to (primary production – respiration). Mismatch from “Redfield expectations” for DIP and DIN flux is assumed proportional to (nitrogen fixation – denitrification).

16 Water and Salt Budgets Water budget Salt budget
Freshwater flows known. System residual flow (VR) conserves volume. Salt budget Net flows known. Mixing (VX) conserves salt content.

17 Nutrient Budgets Nutrient (Y) budgets
Internal dissolved nutrient net source or sink (Y) to conserve Y. Calculations based on simple system stoichiometry Assume Redfield C:N:P ratio (106:16:1) (production - respiration) = -106 x DIP (Nitrogen fixation - denitrification) = DINobs - 16 x DIP

18 LOICZ Strategy Develop a global inventory of these budgets.
Guidelines, a tutorial, and individual site budgets at Under direction of S. V. Smith, F. Wulff Major emphasis of this presentation. Use “typology” (classification) techniques to extrapolate from budgeted sites to global coastal zone. Under direction of R. W. Buddemeier Tools and examples available at (B. Maxwell)

19 LOICZ Budgeting Research
New, or “primary,” data collection is not a primary aim of LOICZ budgeting research. There is heavy reliance on available secondary data to insure widespread (“global”) coverage. Workshops and information sharing via the World Wide Web are the major tools for adding information to the LOICZ budgeting data base. Funding for workshops has come from UNEP/GEF, LOICZ, WOTRO, local sponsorship. Develop analytical tools to assist in budgeting.

20 LOICZ budget workshops to date
September 1995—Guidelines Development (Halifax, Canada) December 1995—Introduce guidelines to SWOL (Penang, Malaysia) October 1996—LOICZ/JGOFS Continental Margins (Lagos, Nigeria) June 1997—Mexico lagoons (Ensenada, Mexico) October 1997—LOICZ/JGOFS Continental Margins (Texel, The Netherlands)

21 LOICZ budget workshops, cont.
October 1998—Australasia estuaries (Canberra, Australia) January 1999—Mexico, C. America lagoons II (Merida, Mexico) July 1999—South China Sea estuaries (Manila, Philippines) November 1999—South America estuaries (Bahia Blanca, Argentina) February 2000—South Asia estuaries (Goa, India)

22 The Global Environment Facility (GEF) of the United Nations Environment Programme (UNEP) has funded LOICZ to conduct a series of local budget, regional typology and global synthesis workshops.

23 LOICZ-UNEP/GEF Tentative Workshop Schedule
July Budget--South China Sea; November Budget--South America; February Budget--South Asia; June Budget--East Asia; September Budget—Africa. November Regional—Asia; March Regional—Americas; May Regional—Africa/Europe. November Global Synthesis. One more, as needed.

24 LOICZ Biogeochemical Modelling Web Page



27 Preliminary Budgeting Results

28 LOICZ Budget Sites to Date
>100 sites so far; > 200 sites desired.

29 Latitude, Longitude of Budget Sites
Present site distribution Poor cover at high latitudes (N & S). Poor cover from 10N to 15S. Poor cover in Africa. S. Asia sites not yet posted.

30 Nutrient Load v Latitude
Load variation most obvious with DIP. High loads near 15N are in SE Asia. High loads near 30S are in Australia

31 Internal Nutrient Flux v Latitude
DIP response to load may differ in the N and S hemispheres. DIN response to load seems weaker than DDIP.

32 DIP, DDIN v DIP Load DIP and DDIN both increase (+ or -) at high DIP loads. Responses more prominent for DIP than for DIN.

33 DIP, DDIN v DIN Load No clear effect of DIN load on DDIP.
DIN appears to become negative at high DIN load.

34 Net Ecosystem Metabolism (production – respiration)
Remember: Rates are apparent, based on stoichiometric assumptions. No clear overall trend; most values cluster near 0. Extreme values (beyond  10) are questionable.

35 (Nitrogen Fixation – Denitrification)
Although values cluster near 0, clear dominance of apparent denitrification. Apparent N fixation >5 seems too high.

36 Some Cautionary Notes Individual budgets may suffer from data quality or other analytical problems. Stoichiometry is “apparent,” and not always reliable. Simple averaging of budgets is not a legitimate estimate of global average performance; the coastal zone is too heterogeneous and sampling is too biased for such averaging. Also, system size, or relative geographic importance, not accounted for in simple averaging. “Upscaling” must take these factors into account.

37 Introduction to Typology
DEFINITION Typology: The study of types, as in systematic classification.

38 e. g., N. American Budget Sites and River Flow
There are many considerations in developing a “coastal zone typology.” e. g., N. American Budget Sites and River Flow It is important to relate sites to characteristics of freshwater inflow. Most of coastline characterized by small coastal watersheds.

39 Natural and Anthropogenic Controls on Fluxes to the Ocean
What is carried in river inflow, and why? Other Factors Population density; Economic drivers; Fertilizer use; Atmospheric deposition; Et cetera. Land use, vegetation type, and budget sites

40 Statistical Clustering of “Types” in the Global Coastal Zone

41 Example of newly developed statistical clustering techniques Australasia—10 Clusters
Distinguish separate clusters OR Emphasize similar clusters

42 What is the link between typology and the budgets?
How do budget characteristics conform with clusters? and compare with Budget Sites We tune the with Expert typology Similar clusters

43 Conclusions and Comments about Budgeting and Typology
We are accumulating coverage of global CNP fluxes in much of the coastal zone. Some trends are beginning to emerge. Extrapolating from individual budget sites to the “global coastal zone” remains a challenge. This extrapolation is being approached via a “global typology.” Natural influences and human dimension must be addressed by both budgets and typology.

44 Need help or advice about biogeochemical budgeting or setting up a budgeting workshop?
Stephen Smith Fred Wulff Vilma Dupra Dennis Swaney Victor Camacho  Malou McGlone  Laura David LOICZ International Project Office  Biogeochemical Modeling Web Page

45 Thank you!


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