Stream Biogeochemistry

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• Stream Biogeochemistry
• What is it and why should you care?
• Autotrophy, Heterotrophy and Nutrient Limitation
• Measuring Nutrient Cycling in Streams
• Experiments Cool Frontiers

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INPUTS OUTPUTS
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Streams are the gutters down which flow the
ruins of continents --Leopold, Wolman and
Miller, 1964
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Water Sources
Precipitation
Stream Segment
Lateral Inflow groundwater and tributaries
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Water Losses
Evaporation
Stream Segment
Groundwater Seepage
outflow
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Autochthonous Allochthonous
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Fisher and Likens 1973
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OUTFLOW
INFLOW
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Traditional view of a nutrient cycle
biotic
abiotic
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dissolved
particulate
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FLOW
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Spiraling Length
Sw
SB
FLOW
R
U
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Biological Uptake by algae Immobilization by
bacteria and fungi Nutrient Transformations Abio
tic Coprecipitation Sorption Hydrologic
Storage (short-term)
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What Limits Primary Productivity
(P)? Light Nutrients Grazers Disturbance
(scouring floods) Competition (with microbes)
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What limits heterotrophic metabolism
(R)? Organic Matter inputs allochthonous autoch
thonous Organic Matter Quality conditioning vs.
original composition Organic Matter
losses speed of mechanical breakdown presence
of retention structures Nutrients
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Bilby 1981
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• Measuring Nutrient Retention in Streams
• input-output budgets
• nutrient uptake length measurements
• isotopic nutrient tracers

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Inputs
Outputs
Outputs - Inputs Retention
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Fisher and Likens 1973
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Triska et al. 1984
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Meyer and Likens 1979
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Newbold et al. 1983
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Measuring Uptake Lengths
Nutrient
Distance from Addition Site
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Measuring Uptake Lengths
Nutrient
P Br
Distance from Addition Site
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Measuring Uptake Lengths
Conservative Tracer
Nutrient
P Br
Nonconservative Solute
Distance from Addition Site
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Measuring Uptake Lengths
slope k, 1/k Sw
Nutrient Tracer
P/Br
Distance from Addition Site
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FLOW
Uptake Velocity Vf (vd) / Sw
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FLOW
Uptake Rate (Q ) (Sw
w)
U
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Conservative Tracer Concentration
Injection Starts
Injection Ends
travel time
Time
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Hall et al. 2002
Main channel
Side Pool
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Hall et al. 2002
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Greater contact time between water column and
sediments gt greater opportunity for uptake
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Grimm 1987
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Grimm 1987
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Dent and Grimm 2000
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Mulholland et al. 1985
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Meyer 1979
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Whole-stream manipulations
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Elwood et al. 1981
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Peterson et al. 1985
Added 10?g/L
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Scaling Up -- moving out from the reach
perspective
Longitudinal Surveys Regional Models
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Dent and Grimm 2000
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