C N P Fluxes in the Coastal Zone The LOICZ Approach to Budgeting and Global Extrapolation

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.

General Background

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

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

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

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

The Global Coastal Ocean: A Narrow, Uneven, Chemically Reactive “Ribbon” LAND OCEAN LOICZ covers only ~5% of the global ocean, but: 18-33% of the global PP ~83% of POM mineralisation Preservation of ~87% of ocean POM Transit for major part of the elements controling Ocean PP (N, P, Si, Fe, etc)

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

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.

Alphabet Soup of the IGBP JGOFSJoint Global Ocean Flux Studies IGACInternational Global Atmospheric Chemistry GCTEGlobal Change and Terrestrial Ecosystems BAHCBiospheric Aspects of the Hydrological Cycle PAGESPast Global Change LOICZLand-Ocean Interactions in the Coastal Zone LUCCLand Use and Cover Change GLOBEC Global Ocean Ecosystem Dynamics __________________________________________________ GAIMGlobal Analysis, Integration and Modelling STARTSystem for Analysis, Research, and Training DIS Data and Information System

Stephen Smith Fred Wulff Vilma Dupra Dennis Swaney Victor Camacho Malou McGlone Laura David LOICZ International Project Office Biogeochemical Modeling Web Page

LOICZ Budgeting Background

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.

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

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).

Water and Salt Budgets Salt budget –Net flows known. –Mixing (V X ) conserves salt content. Water budget –Freshwater flows known. –System residual flow (V R ) conserves volume.

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

LOICZ Strategy Develop a global inventory of these budgets. –Guidelines, a tutorial, and individual site budgets at Use “typology” (classification) techniques to extrapolate from budgeted sites to global coastal zone.

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.

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

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.

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

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

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

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

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.

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

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.

LOICZ Biogeochemical Budgeting Procedures and Examples

INTRODUCTION

Material budget System  outputs  inputs Net Sources or Sinks  [sources – sinks] =  outputs -  inputs LOICZ budgeting assumes that materials are conserved. The difference (  [sources – sinks]) of imported (  inputs) and exported (  outputs) materials may be explained by the processes within the system. Note: Details of the LOICZ biogeochemical budgeting are discussed at loicz and in Gordon et al., 1996.

Three parts of the LOICZ budget approach 1)Estimate conservative material fluxes (i.e. water and salt); 2)Calculate non-conservative nutrient fluxes; and 3)Infer apparent net system biogeochemical performance from non- conservative nutrient fluxes.

Outline of the procedure I.Define the physical boundaries of the system of interest; II.Calculate water and salt balance; III.Estimate nutrient balance; and IV.Derive the apparent net biogeochemical processes.

PROCEDURES AND EXAMPLES

 Locate system of interest Philippine Coastlines Resolution (1:250,000)

 Define boundary of the budget Subic Bay, Philippines Map from Microsoft Encarta Map from Microsoft Encarta

Variables required System area and volume; River runoff, precipitation, evaporation; Salinity gradient; Nutrient loads; Dissolved inorganic phosphorus (DIP); Dissolved inorganic nitrogen (DIN); DOP, DON (if available); and DIC (if available).

SIMPLE SINGLE BOX (well-mixed system)

 Calculate water balance dV syst /dt = V Q +V P +V E +V G +V O +V R V R = -(V Q +V P +V E +V G +V O ) at steady state:

Water balance illustration V P = 1,160V E = 680 V syst = 6 x 10 9 m 3 A syst = 324 x 10 6 m 2 V Q = 870 V G = 10 V R = -1,360 V R = -(V Q +V P +V E +V G +V O ) V R = -(870+1, ) V R = -1,360 x 10 6 m 3 yr -1 V O = 0 (assumed) Fluxes in 10 6 m 3 yr -1

V X = (-V R S R - V G S G )/(S Ocn – S Syst )  Calculate salt balance Eliminate terms that are equal to or near 0.

Salt balance to calculate V X and  V syst = 6 x 10 9 m 3 S syst = 27.0 psu S Q = 0 psu V Q S Q = 0 V R = -1,360 V R S R = -41,480 V X = (-V R S R -V G S G )/(S Ocn – S Syst ) S Ocn = 34.0 psu S R = (S Ocn + S Syst )/2 S R = 30.5 psu V X (S Ocn - S Syst ) = -V R S R -V G S G = 41,420 V X = (41, )/(34.0 – 27.0) V X = 5,917 x 10 6 m 3 yr -1  = V Syst /(V X + |V R |)  = 6,000/(5, ,360)  = 0.8 yr  300 days V X = 5,917  = 300 days S G = 6.0 psu V G S G = 60 Fluxes in 10 6 psu-m 3 yr -1

 Calculate non-conservative nutrient fluxes d(VY)/dt = V Q Y Q + V G Y G +V O Y O +V P Y P + V E Y E + V R Y R + V X (Y ocn - Y syst ) +  Y

System,Y Syst (  Y) River discharge (V Q Y Q ) Residual flux (V R Y R ); Y R = (Y Syst +Y Ocn )/2 Mixing flux (V X Y X ); Y X = (Y Ocn -Y Syst ) Ocean, Y Ocn Other sources (V O Y O ) d(VY)/dt = V Q Y Q + V G Y G + V O Y O +V P Y P + V E Y E + V R Y R + V X (Y ocn - Y syst ) +  Y 0 = V Q Y Q + V G Y G + V O Y O + V R Y R + V X (Y ocn - Y syst ) +  Y  Y = -V Q Y Q - V G Y G - V O Y O - V R Y R - V X (Y ocn - Y syst ) Schematic for a single-box estuary Eliminate terms that are equal to or near 0. Groundwater (V G Y G )

DIP balance illustration  Y = - V R Y R - V X (Y ocn - Y syst ) – V Q Y Q – V G Y G - V O Y O  DIP = - V R DIP R - V X (DIP ocn - DIP syst ) – V Q DIP Q - V G DIP G - V O DIP O  DIP = ,367 – 261 – = -2,115 x 10 3 mole yr -1 DIP syst = 0.2  M DIP Q = 0.3 V Q DIP Q = 261 V R DIP R = -544 DIP Ocn = 0.6  M DIP R = 0.4  M V X (DIP Ocn - DIP Syst ) = 2,367  DIP = -2,115 DIP G = 0.1 V G DIP G = 1 V O DIP O = 30 (other sources, e.g., waste, aquaculture)  DIN = +15,780 x 10 3 mole yr -1 (calculated the same as  DIP) Fluxes in 10 3 mole yr -1

STOCHIOMETIC CALCULATIONS

Stoichiometric linkage of the non- conservative (  Y’s) 106CO H NO H 3 PO H 2 O (CH 2 O) 106 (NH 3 ) 16 H 3 PO O 2 Redfield Equation (p-r) or net ecosystem metabolism, NEM = -  DIPx106(C:P) (nfix-denit) =  DIN obs -  DIN exp =  DIN obs -  DIPx16(N:P) Where: (C:P) ratio is 106:1 and (N:P) ratio is 16:1 (Redfield ratio) Note:Redfield C:N:P is a good approximation where local C:N:P is absent.

Stoichiometric calculations (p-r)= -  DIPx106(C:P) = -(-2,115) x 106 = +224,190 x 10 3 mole yr -1 = +2 mmol m -2 day -1 (nfix-denit) =  DIN obs -  DIN exp =  DIN obs -  DIPx16(N:P) = 15,780 – (-2,115 x 16) = +49,620 x 10 3 mole yr -1 = +0.4 mmol m -2 day -1 Note:Derived net processes are apparent net performance of the system. Other non-biological processes may be responsible for the sum of the uptake or release of the  Y’s.

TWO-LAYER BOX (STRATIFIED SYSTEM)

Stratified system (two-layer box model)

Two-layer water and salt budget model Upper Layer S Syst-s Lower Layer S Syst-d V Q (Runoff) V Q S Q V Z (Volume Mixing) V Z (S Syst-d -S Syst-s ) V Deep’ (Entrainment) V Deep’ S Syst-d V Surf (Surface Flow) V Surf S Syst-s V Deep (Deep Water Flow) V Deep S Ocn-d S Ocn-d V Q +V P + V E + V Surf + V Deep' = 0 V Q S Q + V Surf S Syst-s + V Deep‘ S Syst-d + V Z (S Syst-d - S Syst-s ) = 0 VEVE VPVP

Two-layer budget equations V Q + V Surf + V Deep = 0 V Deep = V R' (S Syst-s )/(S Syst-s -S Ocn-d ) V R’ = -V Q -V P -V E V Z = V Deep (S Ocn-d -S Syst-d )/(S Syst-d -S Syst-s )  = V Syst /(|V Surf |) Note: Visit LOICZ website for detailed derivation of the above equations.

Water and salt budget for stratified system (illustration) Water flux in 10 6 m 3 day -1 and salt flux in 10 6 psu-m 3 day -1. Lower Layer V Syst-d = 55.0x10 9 m 3 S Syst-d = 31.2 psu  = 466 days S Q = 0.1 psu V Q = 10 V Q S Q = 1 V Z = 37 V Z (S Syst-d -S Syst-s ) = 122 V Deep’ = 81 V Deep’ S Syst-d = 2,527 V Surf = 95 V Surf S Syst-s = 2,650 V Deep = 81 V Deep S Ocn-d = 2,649 S Ocn-d = 32.7 psu V E = 0V P = 4 Aysen Sound Upper Layer V syst-s = 11.8x10 9 m 3 S Syst-s = 27.9 psu  = 89 days  Syst = 703 days

Two-layer nutrient budget model Upper Layer Y Syst-s  Y Syst-s Lower Layer Y syst-d  Y Syst-d River discharge (V Q Y Q ) Mixing flux (V Z (Y Syst-d -Y syst-s )) Entrainment flux( V Deep’ Y Syst-d ) Upper layer residual flux (V Surf Y Syst-s ) Lower layer residual flux (V Deep Y Ocn-d ) Ocean lower Layer, Y ocn-d  Y Syst = (  Y Syst-s +  Y Syst- d )

DIP balance for stratified system (illustration) Fluxes in 10 3 mole day -1. Lower Layer DIP Syst-d = 1.7  M  DIP = +32 DIP Q = 0.1  M V Q = 10 V Q DIP Q = 1 V Z = 37 V Z (DIP Syst-d -DIP Syst-s )=7 V Deep’ = 81 V Deep’ DIP Syst-d = 138 V Surf = 95 V Surf DIP Syst-s = 143 V Deep = 81 V Deep DIP Ocn-d = 113 DIP Ocn-d = 1.4  M Aysen Sound Upper Layer DIP Syst-s = 1.5  M  DIP = -3  DIP Syst = +29

COMPLEX SYSTEMS IN SERIES

Pelorus Sound, New Zealand Red dashed lines show segmentation of the system. N UpperPelorus LowerPelorus TawhitinuiReach HavelockArm KenepuruArm

Schematic of systems in series Segmentation for Pelorus Sound Budget.

Water balance for stratified systems in series Complex system like Pelorus Sound can be budgeted as a combination of single-layer and two-layer segments.

TEMPORAL AND SPATIAL VARIATION

Implication of temporal and spatial variation Products of the averages = 5.5(39) = 215 Averages of the products = ( )/4 = 24 X = 15, 6, 1, 0 Y = 1, 5, 50, 100 Systems should be segmented spatially or temporally if there is significant spatial and temporal variation. The algebraic reason is that in general the product of averages does not equal the average of the products. Visit the web site < Methods/spattemp.htm> for a more detailed explanation of this point.

Temporal patterns of the variables The average of the nutrient flux does not equal to the product of the annual average flow and concentration. The budget based on the annual average data is simply not as accurate as the budget on the average fluxes. Temporal gradients of variables will give clue to seasonal division of the data

Gracias

LOICZ-CABARET Computer Assisted Budget Analysis for Research, Education, and Training L.T. David 1, S.V. Smith 2, J. de Leon 1, C. Villanoy 1,V.C. Dupra 1,2, and F. Wulff 3 1 Marine Science Institute, University of the Philippines, Diliman, Quezon City 1101, Philippines 2 School of Ocean and Earth Science and Technology, Honolulu, Hawaii, USA 3 Department of Systems Ecology, Stockholm University, Stockholm, Sweden

Statement of Purpose The Computer Assisted Budget Analysis for Research, Education, and Training or LOICZ-CABARET was designed to simplify the process of calculations in applying the LOICZ approach to biogeochemical budget calculations. This current version can assist in the calculation of the water, salt, and nutrient budget of any single-box or multi-box single-layer or multi-layer system by seasons or monthly. It can also assist in the calculation of the area and volume of a system in its entirely or treated as sub-systems through its on-screen digitization. Finally, to circumvent observed complications of previous users in unit conversions, the LOICZ-CABARET automatically transforms units into m3/yr for easier comparison between systems. Results are displayed in the familiar LOICZ box-diagram format. For questions and suggestion, contact Additional improvements are periodically posted at the LOICZ webpage

The program can be downloaded from the LOICZ webpage as an executable ZIP file. It is best if the downloaded file is placed and unzipped inside a blank folder. All future working files must reside in this folder for the program to work. To unzip, just double click the executable zip. Run program by double-clicking on cabaret.exe The program should work in windows 95/97/2000 and NT.

Sequentially fill in the necessary data. To help guide users through the program, a flow chart can be accessed at any time by clicking on the menu choice named FLOWCHART. Close the flowchart window by clicking DONE. FLOW CHART

ALPHA/PERSON AL In order to be duly recognized as a contributor, make sure to fill in the Contact Person Information Window. Note that the two buttons at the bottom allows the user to go back to the previous window (B) or forward to the next sequential window (N)

ALPHA/DESCRIPTI ON Site description goes inside this window. It is necessary to enter the following fields: ESTUARY NAME COUNTRY THE NORTH, SOUTH, EAST, WEST BORDERS OF THE SYSTEM NO. OF SEASONS & THE START AND END MONTHS OF EACH SEASON

CALIBRATE Choose the type of system The No. of boxes The No. of layers The area per box If the area is unknown, LOICZ- CABARET also allows for the estimation of the area using the on- screen digitization. To use this feature you must have a bmp image of your system. Type in the length of your calibration bar found in most maps or use the latitude lines and then click on the MAP button.

BMP OF MAP A small window asking for the bmp file name opens when you click on MAP. The map image then opens. Click the ends of the calibration bar then click DONE.

ESTIMATING BOX AREA To estimate the area per box, double-click on the corresponding box area. This will once again open the bmp image of your system. Digitize the box area on-screen. The box area polygon is designed to automatically close upon clicking of DONE.

ALPHA/MATERIAL S The water, salt and nutrient data are typed in this window. The minimum fields to be filled are the following: Layer depth At least one freshwater flow At least the salt and nutrient concentration of the outer box and the system box This should be done per box and per layer. Afterwards, click BUILDHTML

RESULT - WATER AND SALT BALANCE Results can be viewed using any web- browser. Make sure to re-load the page after every edit.

RESULT - PHOSPHATE & NITRATE BALANCE

VISION It is hoped that LOICZ-CABARET will not only encourage the users to contribute to the LOICZ endeavor but also experiment with the forcing functions and response sensitivity of their systems. Finally, LOICZ-CABARET is also envisioned to be used as a teaching tool in estuaries and coastal lagoon studies.

Estimation of Waste Load Marine Science Institute University of the Philippines

Coastal Water Body PrecipitationEvaporation Residual flux Mixing flux Runoff Groundwater Sewage/Waste

Sources of Waste (human activity) household activities livestock agriculture urban runoff aquaculture manufacturing

Steps in the Calculation of Waste Load 1. Identify relevant human activities households - solid waste, domestic sewage, detergent livestock - piggery, poultry, cattle agriculture - soil erosion, fertilizer runoff urban runoff - unsewered areas aquaculture - prawns, fish manufacturing - food, textiles, chemicals

2. Determine the level of each human activity from government statistics, preferably at local level household - size of the population livestock - no of pig, chicken, cow aquaculture - tons of prawn, fish urban runoff - urban area agriculture - tons of soil eroded

3. Approximate TN and TP (in effluent discharge) TN = activity level x discharge coefficient TP = activity level x discharge coefficient T

The discharge coefficients for various human activities are given in the following spreadsheet. This spreadsheet calculates TN and TP load in waste generated by various human activities. Knowledge of the activities relevant to the coastal area is necessary and the only input needed in the spreadsheet would be the level of the waste generating activity (fill in white cells).

Sources of Discharge Coefficients

TN and TP (in the spreadsheet) are approximated using the following calculations.

TN = activity level x discharge coefficient Ex. for Domestic Sewage activity level = 2000 persons discharge coefficient = 4 kgN/person/yr TN = 4 kgN/person/yr x 2000 persons TN = 8000 kgN/yr TP = activity level x discharge coefficient discharge coefficient = 1 kgP/person/yr TP = 1 kgP/person/yr x 2000 persons TP = 2000 kgP/yr

If only BOD and COD data are available, TN and TP can be approximated using the following ratios* TN/BOD = 0.5 TP/BOD = COD/BOD = 2.6 Ex if available data is BOD at 5 mg/L TN = 5 mg/L x 0.5 = 2.5 mg/L Ex if available data is COD at 5 mg/L TN = 5 mg/L x 1/26 (BOD/COD) x 0.5 = 1 mg/L

The previous spreadsheet also approximates DIN and DIP. The following calculations illustrate how this is done.

4. Calculate DIN and DIP in the effluent discharge Assumption: 25% of waste enter the bay Use stoichiometric ratio* DIN/TN = 0.38 DIP/TP =0.5 DIN = TN÷atomic wt N x DIN/TN x 25% DIN = 8000 kgN/yr ÷14 g/mole x 0.38 x 0.25 DIN = 54,000 moles/yr DIP = TP÷atomic wt P x DIP/TP x 25% DIP = 2000 kgP/yr÷31 g/mole x 0.5 x 0.25 DIP = 8,000moles/yr

The following N and P budgets of a Philippine bay (LINGAYEN GULF) are given to illustrate how waste is quantified and show that this is an important input to the system.

NITROGEN AND PHOSPHORUS BUDGETS FOR LINGAYEN GULF

Lingayen Gulf Manila Bay South China Sea

Lingayen Gulf divided into three boxes Upper Gulf 1764 km 2, 81 km 3 Bolinao 126 km 2, 0.3 km 3 Nearshore 210 km 2, 3.2 km 3

LINGAYEN GULF Water Budget (fluxes in 10 9 m 3 /yr) Upper Gulf 1764 km 2, 81 km 3 Nearshore 210 km 2, 3.2 km 3 Bolinao 126 km 2, 0.3 km 3 Ocean V R = 1 V R = 8 V R = 11 V Q = 0.2 V G = 0.7 V P = 0.3 V P =4 V Q = 2 V G = 0.4 V Q = 8 V G = 0.2 V P = 0.5 V E = 0.3 V E = 0.4 V E = 4

S 2 = 34.0 S 1N = 31 S 1B = 33.5 LINGAYEN GULF Salt Budget (salt fluxes in 10 9 psu-m3/yr) Upper Gulf 1764 km 2, 81 km 3 Nearshore 210 km 2, 3.2 km 3 Bolinao 126 km 2, 0.3 km 3 Ocean V X = 68 V R S R = 34 S 3 = 34.4 V R S R = 376 V X = 940 V R S R = 260V X = 87  = 2 days  = 27 days  = 12 days

Table 1. Effluents produced by economic activities in Lingayen Gulf (in 10 6 mole yr -1 ).

V O DIP O = 35 V O DIP O = 46 Nearshore LINGAYEN GULF DIP Budget (fluxes in 10 6 moles/yr) Upper Gulf Bolinao Ocean DIP 1B = 0.4 DIP 2 = 0.1µM DIP 1N = 0.4µM V X DIP X = 20 V R DIP R = 2 V R DIP R = 0 V X DIP X = 26 DIP 3 = 0.0µM V R DIP R = 1 V X DIP X = 94 V Q DIP Q = 1 V Q DIP Q = 88 V Q DIP Q = 1 V G DIP G = 1 V G DIP G = 2 V G DIP G = 0  DIP=-27  DIP = +10  DIP = -97

V O DIN O = 262 V O DIN O = 350 DIN 1N = 1.7µM V Q DIN Q = 4 V Q DIN Q = 8 V Q DIN Q =128 Ocean LINGAYEN GULF DIN Budget (fluxes in 10 6 moles/yr) Upper Gulf Nearshore Bolinao DIN 1B = 3.9µM DIN 2 = 0.8µM V X DIN X = 211 V R DIN R = 10 V R DIN R = 2 V X DIN X = 78 DIN 3 = 0.5µM V R DIN R = 7 V X DIN X = 282 V G DIN G = 28 V G DIN G =11 V G DIN G = 39  DIN = -180  DIN = -310  DIN = -313

Stoichiometric Links Net ecosystem metabolism (p-r) or photosynthesis minus respiration, can be calculated using the formulation (p-r ) = -  DIP  (C:P) part Estimates of (nfix-denit) or N-fixation minus denitrification, can be approximated using the formulation (nfix-denit) =  DIN -  DIP  (N:P) part where (C:P) part and (N:P) part are the ratios of organic matter reacting in the system

Table 2. Summary of nonconservative fluxes in three boxes of Lingayen Gulf. +5.9

Table 3. Effects of changing waste load on (p-r) and (nfix-denit).

IMPLICATIONS  The system is able to breakdown waste inputs and export most of these as N and P out of the Gulf with some amount retained, perhaps in the sediments.  Since the average nutrient concentrations of N and P in the upper Gulf have not varied much over the years, this is an indication of the system’s current assimilative capacity.  However, buildup of organic matter is critical for the nearshore and Bolinao boxes and will eventually affect the Gulf’s ability to process these materials.