NUTRIENT UPTAKE

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NUTRIENT UPTAKE
Comparing An Urbanized Stream To A Reference
Stream Ecology
Loren Bausell David Richardson
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Nutrient Uptake Outline

• Introduction
• Water Issues, Intro to Nutrient Cycling
• Methods
• Theory and Protocol
• Results
• Solute Dynamics and Uptake Velocities
• Discussion
• Explanation, Design Flaws, Future Experiments and
  Conclusions

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Introduction-Land Use Changes

• Change in riparian vegetation composition
• Decreased total amount of riparian vegetation
• Increased nutrient and contaminant inputs to
  excessive amounts
• From Palmer et al. 2002

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Introduction- Increase in Urbanization
Sisk, 1998
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Introduction-Nutrient Cycling
Newbold, 1992

• Sspiraling length Sw Uptake Length Sb
  Turnover Length Fw, FB Nutrient Fluxes U, R
  Exchange Fluxes
• From Newbold, 1992

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Introduction-Project Outline

• Nutrient uptake is a good measure of a streams
  ecological processing
• It indicates a streams retentiveness for a given
  nutrient and demonstrates the importance of
  streams in processing nutrients (Hall et al.
  2002)
• Our hypothesis nutrient uptake velocity will be
  smaller at the urbanized and highly degraded
  site, Stewart April Lane
• Uptake velocity level of nutrient demand,
  relative to its supply in the water column (Hall
  et al. 2002)

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Nutrient Uptake Outline

• Introduction
• Water Issues, Intro to Nutrient Cycling
• Methods
• Theory and Protocol
• Results
• Solute Dynamics and Uptake Velocities
• Discussion
• Explanation, Design Flaws, Hopes for the Future
  and Conclusions

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Methods-Site Background
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Methods-Solute Transport

• DConcentration of solute
• advection dispersion inflow and
  dilution net of sources and sinks

Runkel, 2000
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Methods-Assumptions

• Channel and flow characteristics uniform
• Eliminates unwanted dilution effects
• Uptake of Nutrients proportional to nutrients
• Remove potential saturating effects
• Release of nutrients from the bottom must not
  affect the concentration
• Avoid unaccounted for input

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Methods- Steady State Equation

• C(x) Cb C0 Cbe-kC(x/u)
• C(x)Concentration of nutrient
• Cb background concentration of solute
• Co Concentration at injection point
• kC biotic uptake coefficient, x distance
  downstream and u water velocity

Stream Solute Workshop, 1990
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Methods-In Stream Protocol

• Nutrients Ammonium Chloride NH4Cl Potassium
  Dihydrogen Phosphate KH2PO4
• Inject dye to determine travel time
• Measure discharge and average depth
• Inject Nutrients
• Sample
• Process Samples

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Nutrient Uptake Outline

• Introduction
• Water Issues, Intro to Nutrient Cycling
• Methods
• Theory and Protocol
• Results
• Solute Dynamics and Uptake Velocities
• Discussion
• Explanation, Design Flaws, Hopes for the Future
  and Conclusions

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Results-Stream Characteristics
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Results-SAL Solute Concentrations
Diamonds bromide concentrations and are shown
on the left axis. Squares represent ammonium
concentrations and triangles represent phosphate
concentrations, both shown on right axis.
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Results-PB Solute Concentrations
Diamonds bromide concentrations and are shown
on the left axis. Squares represent ammonium
concentrations and triangles represent phosphate
concentrations, both shown on right axis.
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Results-Applying the Math

• a. C(x) Cb C0 Cbe-kC(x/u)

Stream Solute Workshop, 1990
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Results

• kCaverage depth uptake velocity
• Uptake Velocity?average velocity of a nutrient
  toward the benthos

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Nutrient Uptake Outline

• Introduction
• Water Issues, Intro to Nutrient Cycling
• Methods
• Theory and Protocol behind experiment
• Results
• Solute Dynamics and Uptake Velocities
• Discussion
• Explanation, Design Flaws, Hopes for the Future
  and Conclusions

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Discussion-Biotic Factors

• NH4 uptake lengths ? as standing stocks of algae
  and detritus ?
• As biotic mass and ecological processing rates ??
  nutrient uptake velocity ??
• Indirect effects of consumers that can possibly
  ?? or ? nutrient uptake

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Discussion-Abiotic Factors

• Discharge quantity First-order tributary v.
  second-order tributary
• Discharge variability
• Effects of riparian vegetation
• Chemical and nutrient inputs
• Microhabitat and depletion of aquatic life

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Discussion-Transient Storage

• Changes in channel shape and substrate
  composition may decrease opportunities for
  transient storage
• Both sites display transient storage
• May or may not lead to decreased opportunities
  for nutrient uptake

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Discussion-Experimental Challenges

• Physical adsorption of nutrients and biotic
  uptake are indistinguishable especially true of
  PO4
• Nutrient addition experiments tend to
  overestimate uptake length (Mulholland et al.
  1990, 2000, 2002)

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Discussion-Future Experiments

• Increase the number of stations longitudinally
  (Dodds et al. 2002)
• Increase the number of times per year sampling is
  done effects of seasonal variation
• Multiple repetitions within season
• Monitor over a period of years, in order to
  effectively monitor improvement, maintenance, or
  decline in nutrient uptake velocities

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Conclusions

• Nutrient uptake velocity is a good measure of
  ecological processing in streams
• Ecological processing is affected by land use
  changes
• Monitoring stream health and ecosystem function
  is critical to both aquatic and human life

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Citations, Thanks, etc

• Thanks To Chris Swan, Drs Lamp and Palmer,
  Montgomery County DEP, Brooke, Jen
• Dodds, W., A. Lopez, et al. (2002). "N uptake as
  a function of concentration in streams." JOURNAL
  OF THE NORTH AMERICAN BENTHOLOGICAL SOCIETY
  21(2) 206-220.
• Mulholland, P., J. Webster, et al. (2002). "Can
  uptake length in streams be determined by
  nutrient addition experiments? Results from an
  interbiome comparison study." JOURNAL OF THE
  NORTH AMERICAN BENTHOLOGICAL SOCIETY 21(4)
  544-560.
• Newbold, J. (1992). Cycles and Spirals of
  Nutrients. The Rivers Handbook. P. Colow and G.
  Pelts. Oxford, Blackwell Scientific. 1 379-408.
• Stream Solute Workshop (1990). "Concepts and
  Methods for Assessing Solute Dynamics in Stream
  Ecosystems." Journal of North American
  Benthological Society 9 95-119.