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Ecological Engineering: Nutrient Uptake Patrick Corbitt Kerr University of Notre Dame It has been said that streams are the gutters down which flow the ruins of continents. L.B. Leopold et al. 1964. Slide 2 Stormwater Management: The Industry Direction Quantity (-) Water Supply (Irrigation, Drinking Water,) (+) Flooding (Rate or Volume?) Quality Importance Safe for humans (Acute vs Chronic) Ecosystem Conscious Aesthetics Components Groundwater vs Surface Water Type of Pollutants Pollutant Source: Urban or Rural Sediment & Watercourse Stability Image from http://www.the-macc.org/wp-content/uploads/2009/04/storm2.jpg Slide 3 Stormwater Pollutants Sediment Nutrients (Nitrogen, Phosphorus, Organic Matter) Microorganisms (e.g. Coliform Bacteria) Toxic Substances Pesticides Salt (Chloride) Oil and Grease (e.g. Polycyclic aromatic hydrocarbons (PAHs)) Heavy Metals (e.g. Lead, Zinc, Copper) Heat Litter Slide 4 Nutrients Nutrients: Chemicals that an organism needs to live and grow. Macronutrients: Carbon (C) Nitrogen (N) Phosphorus (P) If the aquatic ecosystem requires nutrients, why then are nutrients considered a pollutant? An oversupply of nutrients to a certain species can result in excessive growth; thereby choking out other species. The Solution is . Balance. Slide 5 Algae (Phytoplankton) Blooms Upper left: Cyanobacterial (blue-green algal) bloom in the Gulf of Finland region of the Baltic Sea. Upper right: Dinoflagellate red tide bloom near the Japanese Coastline (Sea of Japan). Lower left: Cyanobacterial bloom in the St Johns River Estuary, near Jacksonville, Florida. Lower right: Mixed cyanobacterial-chlorophyte bloom in North Island, New Zealand Image from http://lepo.it.da.ut.ee/~olli/eutr/html/htmlBook_78.html Slide 6 Hypoxia Means Low Oxygen Algae blooms consume oxygen (0 mg/L) is anoxia Called Dead Zones because animals cant survive Kills mobile animals like fish Kills shellfish and other less mobile animals Nursery habitat is destroyed Releases stored pollutants Chemical reaction between hypoxic water and bottom sediments Overall ecosystem is stressed (Birds, mammals, too!) Image from: srwqis.tamu.edu/hot-topics/hypoxia.aspx Slide 7 Gulf of Mexico Hypoxia Image from: http://water.usgs.gov/nawqa/sparrow/gulf_findings/hypoxia.html Slide 8 The Mississippi River Basin: N & P Yield Image from: http://water.usgs.gov/nawqa/sparrow/gulf_findings/delivery.html Slide 9 Percent N & P Contribution by State Image from: http://water.usgs.gov/nawqa/sparrow/gulf_findings/by_state.html Slide 10 Sources: Nitrogen & Phosphorus Image from: http://water.usgs.gov/nawqa/sparrow/gulf_findings/primary_sources.html Slide 11 Macro-Scale vs Micro-Scale: Hydrosphere, Lithosphere, Atmosphere, Biosphere Water Cycle Conservation of Mass & Energy Ecosytem Components: Solar Energy ( Light / Temperature ) Producers Consumers Decomposers Water Soil / Water / Air Chemistry The Nutrient (Biogeochemical) Cycle Image from: ga.water.usgs.gov/edu/watercyclehi.html Slide 12 Nutrient Cycling: Carbon Organic (O) Has C Inorganic(I) Dissolved (D) Particulate (P) Image from: http://www.epa.qld.gov.au/wetlandinfo/site/ScienceAndResearch/ConceptualModels/Conceptintromore/Palustrine/MainFloodplainHeath/FloodplainHeathNutrientCycling.html Slide 13 Nutrient Cycling: Nitrogen State Changes Nitrification(Gain O) De-Nitrification (Lose O) Fixation ( N 2 Uptake) Assimilation( NH 4, NO 3 Uptake) Mineralization Assimilatory Uptake Structural Synthesis Dissimilatory Uptake Bacteria obtain Energy Image from: http://www.epa.qld.gov.au/wetlandinfo/site/ScienceAndResearch/ConceptualModels/Conceptintromore/Palustrine/MainFloodplainHeath/FloodplainHeathNutrientCycling.html Slide 14 Nutrient Cycling: Phosphorus Uptake Autotrophic Heterotrophic Mineralization Bacterial Activity Adsorption Balance Water Column Sediment Imagefrom: http://www.epa.qld.gov.au/wetlandinfo/site/ScienceAndResearch/ConceptualModels/Conceptintromore/Palustrine/MainFloodplainHeath/FloodplainHeathNutrientCycling.html Slide 15 Nutrient Transport: Spiraling Concepts and Methods for Assessing Solute Dynamics in Stream Ecosystems Stream Solute Workshop Journal of the North American Benthological Society, Vol. 9, No. 2. (Jun., 1990), pp. 95-119. Slide 16 Ecosystems change spatially Seeks a dynamic balance between form & function The watercourse changes Width, Depth, Velocity, Sediment Load, Canopy Cover, Temperature, Flow Characteristics The stream community & biogeochemical processes conform to the new structure. River Continuum Concept (RCC) www.tcnj.edu/~bshelley/EcolTCNJ.htm Slide 17 Nutrient Uptake (U) Image from: http://www.biol.vt.edu/faculty/benfield/freshwater/freshwaterlocked/fredfigs.html Definition: The total flux of nutrient from the water column to the stream bottom, expressed on the basis of stream bottom area (e.g., mg/m/hr) Biotic & Abiotic Element Cycling Rate Pathways Residence Time Slide 18 Biotic Uptake Stoichiometry of Organic Matter Redfield Ratio: C:N:P = 106:16:1 Not Phytoplankton Silica Diatoms Image from: labs.psc.riken.jp/pnbmrt/Research_English.html Slide 19 Abiotic Uptake Some nutrients adsorb to sediment particles. Adsorption capacity varies By nutrient and chemical state: Phosphorus (H 2 PO - 4 ) is most adsorptive By Media: Capacity dependent on makeup and chemical properties pH, total and reactive calcium, total and reactive Fe, Al oxide Capacity also increases as: Size & Density decreases Porosity and Surface Area increases Not Permanent -> Desorption Image from: http://www.phosphoreduc.com/fr/our-technology/technical-info/25-phosphorus-adsorption-capacity.html Slide 20 How does this relate to us as Professional Civil Engineers? Slide 21 The Design Process: What conditions are we considering? Existing or Pre-Existing Proposed or Ultimate What is our design criteria? Quantity: Typically: Peak Discharge (Match -yr Post to -yr Pre) But sometimes .Volume Recharge (Re V ), Channel Protection (CP V ), Overbank Flood Protection (Q p ), Extreme Flood (Q f ) Quality: Water Quality Standards: What Format? Waterbody Type or Waterbody Specific? Concentration, Load, or Indicator (Clarity or Chl-a)? Slide 22 The Water Quality Challenge Whos leading the charge? Environmental Groups EPA Coastal States: Maryland, Florida, etc. Who/What is being targeted? Point versus Non-Point Sources Urban Areas (Agricultural/Rural has largely been avoided) Construction Practices: Erosion & Sediment Control Stormwater BMPs: New Construction & Retrofits Stream Restoration How do we design stormwater BMPs? Uniform Sizing Criteria: (Performance Based?) Water Quality Volume (WQ V ) Slide 23 WQv ( A Standard Solution?) Methods: Post-Conditions vs Pre-Conditions Difference Post-Conditions Total Regression Equation: function of P, I, and A WQ V = [(P)(R V )(A)]/12 Where: WQ V = Water Quality volume (acre-feet) P = Precipitation (inches) Rainfall necessary to facilitate full movement of pollutants (First Flush) A = Drainage Area (acres) R V = Volumetric Runoff Coefficient = 0.05 + 0.009(I) I = Percent Impervious Area (%) Function of Load and BMP Performance (Pollutant Specific) Slide 24 The Water Quality Volume Issues: Regression equation doesnt account for non-impervious area Are nutrient-laden areas being considered? For storms greater than P, can WQ V be targeted? Consider a 100% Impervious Site, designed for P = 1: P is a function of Duration, Time of Concentration, and Land Cover Peak Water Quality Flowrate (Q WV ) P = 1P > 1 100% Treated Any Duration Duration Dependent WQV Slide 25 What to do with the Water Quality Volume? Suppose we account for the First Flush and can isolate all the pollutants by that WQ V, what are our goals? Ideally we wish to TREAT the water? In Water/Wastewater: We have effluent criteria defined by concentration and load We measure (sample) both influent and effluent We alter it chemically and mechanically But, most importantly, though, we can remove mass (SLUDGE) Why is sludge removal so important? Some pollutants can be broken down but unless N, P, Heavy Metals, etc. are removed from the system and assuming steady flow the load in will equal the load out. If removal is the ultimate goal, then how? Slide 26 Removing N & P N & P come in many different forms. Which do we target? Perhaps, we should first identify ways to remove nutrients, and maybe that will decide for us Image from: http://www.biol.vt.edu/faculty/benfield/freshwater/freshwaterlocked/fredfigs.html Slide 27 General Ways to Remove Pollutants Separation is the first step to pollutant removal. Methods of separation we know from water/wastewater treament: 1) Screening 2) Skimming 3) Settling 4) Filtering Cant use active treatment systems or mechanical means Typically referred to as a Pre-Treatment. Pollutants are separated WITHIN the system. Full Removal requires maintenance (Typically considerable). These methods will often FAIL under HIGH flows. Slide 28 Screening Typically refer to as trash racks We focus on the Inlet Image from: http://www.waterwatchadelaide.net.au/index.php?page=how-does-a-wetland-work Image from: http://www.mitchamcouncil.sa.gov.au/site/page.cfm?u=1496 Slide 29 Skimming Solution: Submerged Outlets High flow overflow? Use Bypass Control Structures Reduces both size of structure and effectiveness Image from: http://www.ene.gov.on.ca/envision/gp/4329eimages/ figure4.41.gif Image from: http://www.baysaver.com/products/BaySeparators/index.html Slide 30 Settling Theoretical Solutions: Force it with a vortex Inhibit (re-)suspension Slow Flow (Long Release Time) Not Turbulent (Wide/Deep) Long Paths (Baffles, Islands, L:W) Design Options: SW Manual Criteria Length to Width Ratio 1.5:1 to 3:1 Forebay (Typically at least 10% WQ v ) Use Stokes Law Need to know influent load Slide 31 Stokes Law Equation: V S = settling velocity (cm/s) g = gravity (m/s) S and W = densities of the particle and water (g/cm) = dynamic viscosity d = effective particle diameter Particle TypeDensity (g/cm)Diameter (m) Settling Velocity (m/d) Phytoplankton1.0272 840.08 1.9 Particulate Organic Carbon1.02 1.271 >64,0.2 - >2.3 Clay2.652-40.3-1 Silt2.6510-203-30 Slide 32 Applying Stokes Law Solids Budgeting Simple Solution Complex Solution Slide 33 Resuspension Bed Scour is a function of shear stress Shear Stress is a function of velocity gradient, therefore consider the : Velocity of the flow path Orbital Velocity (from wind forced waves) Wind Velocity Depth Fetch Affects both aeration and suspension Image from: http://www.ozcoasts.org.au/glossary/images/resuspension.jpg Slide 34 Sediment Transport Sediment Balance Bed Load Suspended Load Costly to Model Image from: cals.arizona.edu/.../riparian/chapt4/p7.html Image from: medinaswcd.org/streams.htm Slide 35 Fluvial Geomorphology www.fgmorph.com/fg_8_5.php Image from: http://www.thecottagekey.com/waterlevels_andflows_diagram2.gif Slide 36 Transient Storage A) Surface Transient Storage (STS) B) Hyporheic Transient Storage (HTS) Nutrient Uptake Increases as: Transient Storage Increases Geomorphic Features Hydralic Gradient Velocity/Flow Decreases Turbulence Increases Depth Decreases Residence Time Increases Slide 37 Surface Transient Storage Non- Advective: Stagnant Turbulent Boundary Layer Receives Light Aerobic Slide 38 Hyporheic Zone Underground No Light Driven by Hydraulic Gradient Moves Oxygen into Bed/Bank Leaves Bed/Bank as anaerobic Image from: http://www.pc.ctc.edu/coe/images/Hyporheic.jpg Slide 39 Filtration versus Infiltration Filters Not Vegetated Replaceable Media Infiltration Groundwater Recharge Reduces Nutrient Load Leaches Pollutants into GW Slide 40 Outlet Filters Vertical Perforated Riser Slow release (Essentially orifice equation times # of holes) Concentric (Not Focused) Image from: http://www.ene.gov.on.ca/envision/gp/4329eimages/figure4.24.gif Slide 41 Example of an Underground Sand Filter Montrose Parkway Phase I Urban Setting: No room for pond or above ground BMPs Solution: Underground Sand Filter Quality Solution: Quantity SSF: Separator Sand Filter Slide 42 Choosing the best method Slide 43 BMP Performance How do we measure performance? Load or Concentration How do we rate performance? Reduction % or Final Effluent Result Slide 44 Comparing Pollutant Removal Efficiencies among Different BMPs Slide 45 Dry versus Wet methods Dry > Wet Filtration/Infiltration Groundwater Recharge In-basin vegetation in addition to perimeter BioRetention Dry < Wet Less effective for oils, greases, & hydrocarbons Disturbance of Bottom Sediments Leaching Slide 46 Combination Facilities 2+ facilities Target different pollutants Pre-Treat for Next BMP Start at Source Grass Channels instead of Curb, Gutter, & Sewers Image from: http://h2o.enr.state.nc.us/wswp/images/wet_pond.gif Image from: www.fhwa.dot.gov/environment/ultraurb/3fs5.htm Slide 47 Pond Depth (Shallow or Deep) Shallow: Pros: More Vegetation Higher oxygen content Greater Wetted Contact Area Cons: More bottom disturbance -> Greater Turbidity Thermal Increase Wider Pond: Less Canopy Cover Deep Pros: Cooler Water Less Disturbance Cons: Stratification and Anoxia Less Wetted Contact Area Less Vegetation Slide 48 State Requirements (Min, Max) (GA) Max Depth: (GA: 8 ft ) Min Depth: (GA: 3ft to 4ft) Design for maximum depth to avoid Anoxia (FL) If TP is known, calculate chyl-a: TP = total P concentration (g/l) Chyl-a = chlorophyll-a (mg/m) Calculate Mean Secchi Disk Depth SD = Secchi disk depth (m) Calculate Depth of DO For Deeper Depths Aeration or Mixing is Required Pond Depth Design Slide 49 Maximizing Nutrient Uptake Summary Pre-Treat Screen, Skim, Settle, Filter (abiotic Uptake) Treat (Biotic Uptake) Healthy Ecosystem Biodiversity Vegetation (Diversify) Plan Form Features (Abnormal Geometry) Habitat (In-Pond Features) Pore Diffusivity Bed/Bank Material Construction Methods Cant rely on maintenance! Slide 50 Case Studies: Austin, TX Slide 51 Case Studies: Auckland, New Zealand Slide 52 Case Studies: St. Paul, MN Slide 53 Case Studies: Aurora, CO Slide 54 Case Studies: Runaway Bay, NC Slide 55 Case Studies: 91 Slide 56 Case Studies: 90 Slide 57 Case Studies: 77 Slide 58 Case Studies: Mosquitos Slide 59 Case Studies: 98 Slide 60 Resources Slide 61 National Aquarium