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Published byHarvey Ball Modified over 8 years ago
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Estuary Eutrophication Models: Essential Components and Material Exchanges
By Jim Bowen, UNC Charlotte presented at Multi-Media Modeling Workshop March 23, 1999
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Talk Addresses Three Questions
1. What are the Essential Components of an Estuary Eutrophication Model? 2. What are the Cross-Media Exchanges? 3. Which Exchanges are Important in the Neuse River?
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Common Components of Estuary Eutrophication Models
Based on review of existing models Numerical model development started in 70’s All models include hydrodynamic and water quality components Focus here is on the water quality component
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Define Essential Capabilities of Model
Predict impact of pollutant loadings suspended solids, nutrients, oxygen consuming wastes (C & N), Common endpoints of concern dissolved oxygen, algal abundance Other endpoints may also be desired (e.g. harmful algal blooms, fish kills, toxic organics)
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Eutro. Models - Common Components
Predation, Mortality Living & Non-Living Organic Matter Phytoplankton Photosynthesis Respiration Remineralization Recycling Oxygen, Other Oxidants Nutrients Settling, Denitrification, Organic Matter Remineralization Benthos
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Multi-Element Components
Phytoplankton Living & Non-Living Organic Matter = C N Si P = C N Si P Benthos
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Examples: Qual2E, WASP Living & Non-Living Phytoplankton
Organic Matter Phytoplankton 1. Phyto as chl-a 2. BOD Org. P 3. Org. N Oxygen, Other Oxidants Nutrients 5. Dissolved Oxygen 6. NH NO3 7. NO Ortho P Benthos
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Examples: CE-Qual-W2, V3 (NEEM)
Living & Non-Living Organic Matter Phytoplankton 1. Diatoms, Dinoflagg’s 2. B-G Algae 3. Mixed Summer Phyto. 4. Labile Partic. OM 5. Refrac. Partic. OM 6, 7. L & R Diss. OM 8. Part. Si Oxygen, Other Oxidants Nutrients 10. NH Diss. Si 11. NO2+ NO Ortho P 9. Dissolved Oxygen 14. Benthic Organic Matter Benthos
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Examples: Hydroqual, CE-Qual-ICM
Living & Non-Living Organic Matter Phytoplankton 4,5,6. Lab-Par-Org C,N,P 7,8,9. Ref-Par-Org C,N,P 10,11,12. Lab-Dis-Org C,N,P 13,14,15. Ref-Dis-Org C,N,P 16,17. Reactive, Exuded DOC 18. Biogenic Silica 1. Diatoms, Dinoflagg’s 2. B-G Algae 3. Mixed Summer Phyto. Oxygen, Other Oxidants Nutrients 19. Dissolved Oxygen 20. NH Diss. Si 21. NO2 +NO Ortho P React, Refr, Inert Part. C,N,P Benthos
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Divide Estuary into Segments
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X-section Representation
UNC Charlotte X-section Representation trapezoidal cross-sections for each segment Layer 1 Layer 4 S1 S2 S3 S4 Sediment Compartments 22
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Exchanges with Other Media
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Neuse Estuary Eutrophication Model
Physical Processes
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Modeled Salinities - September 1991
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Nitrogen Cycling Organic Matter Phytoplankton Nutrients RDON NO3 LDON
Dia-Dino Sum. Phyto. B-G Algae NH4 LPON RPON Benthic ON Benthos
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Component Analysis - Summer 1997
Based on the NEEM simulations Calibrated/Verified to 1991 and 1997 monitoring data Summer conditions (June - September)
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Carbon Distribution by Component
0.676% 0.0374% 0.678% 0.0209% 5.17% 46.5% 0.411% LDOM RDOM LPOM RPOM Dia-Dino Sum. Phy. B-G Alg. BOD Benthic OC = 500% Relative Mass
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Nitrogen Distribution by Component
0.602% 0.0333% 0.604% 0.0186% 4.61% 41.4% 2% 9.33% LDOM RDOM LPOM RPOM Dia-Dino Sum. Phy. B-G Alg. NH3 NOX Relative Mass
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Phosphorus Distribution by Component
0.583% 0.0322% 0.585% 0.0181% 4.46% 40.1% 14.1% LDOM RDOM LPOM RPOM Dia-Dino Sum. Phy. B-G Alg. PO4 Relative Mass
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Estuary Exchanges Looked at loadings:
freshwater loading to estuary NH4 and NO3 loading to estuary Combines monitoring and modeling results Examined June - September 1997
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Estuary Loadings: Freshwater
Neuse R. Trent R. Weyer. WWTP Swift Ck. Bachelor Ck. 62% 8.5% 1.2% 3.31% 1.05% 23.9% Precipitation Relative Flow
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Estuary Loadings: Nitrogen
Riverine NH4 Riverine NOx Precipita. NH4 Precipita. NOx Sediment Release Pamlico NH4 Pamlico NOx DOM recycle 0.899% 21.3% 1.07% 2.24% 30.9% 18% 3.06% 22.6% Relative Amount
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Summary All estuary eutrophication models have 4 components in common
phytoplankton, organic matter, nutrients, oxidants In Neuse, most water-column C, N, & P is in phytoplankton pool Important freshwaater exchanges occur w/ Neuse & Trent R., atmosphere Internal recycling important to nutrient exchange
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