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NUTRIENT UPTAKE

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Explanation, Design Flaws, Future Experiments and Conclusions ... Uptake Velocity average velocity of a nutrient toward the benthos. Nutrient Uptake: Outline ... – PowerPoint PPT presentation

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Title: NUTRIENT UPTAKE


1
NUTRIENT UPTAKE
Comparing An Urbanized Stream To A Reference
Stream Ecology
Loren Bausell David Richardson
2
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

3
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

4
Introduction- Increase in Urbanization
Sisk, 1998
5
Introduction-Nutrient Cycling
Newbold, 1992
  • Sspiraling length Sw Uptake Length Sb
    Turnover Length Fw, FB Nutrient Fluxes U, R
    Exchange Fluxes
  • From Newbold, 1992

6
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)

7
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

8
Methods-Site Background
9
Methods-Solute Transport
  • DConcentration of solute
  • advection dispersion inflow and
    dilution net of sources and sinks

Runkel, 2000
10
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

11
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
12
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

13
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

14
Results-Stream Characteristics
15
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.
16
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.
17
Results-Applying the Math
  • a. C(x) Cb C0 Cbe-kC(x/u)

Stream Solute Workshop, 1990
18
Results
  • kCaverage depth uptake velocity
  • Uptake Velocity?average velocity of a nutrient
    toward the benthos

19
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

20
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

21
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

22
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

23
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)

24
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

25
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

26
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.
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