Biogeochemical
Processes and Implications for
Nutrient Cycling
Chapter 3:
Loading
Plant Community
Hydroperiod
Carbon (productivity)
Nitrogen
Cycle
Nitrogen
Sulfur
Cycle
Cycle
Phosphorus
Phosphorus
Cycle
Cycle
Stable Organic Matter
Species/Ecosystem Stability
(P Accretion/Stability)
Biogeochemical Hotspots
Water column
Watercolumn
Watercolumn
Watercolumn
Algal mat
Biofilm/periphyton
Algal mat
Snag/Debris
SAV Leaf
Sediment
Sediment
Benthic Fluxes
(Stevenson et al., 2007)
Sediment Processes
(hyporheic exchange)
Water column
H
H
OM
OM
GW
GW
Limestone Bedrock
Sediment/Water
Interface
Sediments
Sediment Composition:
Chassahowitzka River
Near Boil
Riverside
(Saunders, T. 2007. Dissertation. University of Florida)
Sediment Composition:
Organic Matter Sources
Downstream Trends:
Wekiva
(from Inglett et al., 2007)
Downstream Trends:
Wekiva
1.5
1%
NH4+
NO3DON
2%
mg N L-1
1.0
3%
83 %
0.5
0.0
16 %
0.0
2%
75 %
55 %
50 %
23 %
42 %
48 %
1.8
10.2
14.6
Distance from boil (mi)
(from Inglett et al., 2007)
Nitrate Assimilation:
Wekiva
Head spring
(from Inglett et al., 2007)
Denitrification:
Wekiva
Head spring
1.8
mi
10.2
mi
14.8
mi
(from Inglett et al., 2007)
Fates of NO3C
N22
H
4
2-
S
C
or
g
Fe 2 +
/Mn 2
+
NH44++
O2/Fe3+
NO22-Corg
S 2-
CH4?
NO33--
Fates of NO3-
(From Burgin and Hamilton, 2007)
Sediment P Storage
(Wekiva, Rock Springs, Juniper, Alexander)
Sediment Organic C
(% DW)
2.5
2.0
1.5
1.0
0.5
y = 7.05x + 0.61
2
R = 0.13
0.0
0.00
0.02
0.04
0.06
0.08
0.10
0.12
Sediment TP (% DW)
(based on data from: Wetland Solutions, Inc., 2005)
Sediment N Storage
(Wekiva, Rock Springs, Juniper, Alexander)
Sediment Organic C
(% DW)
2.5
2.0
1.5
1.0
y = 9.7x - 0.02
R2 = 0.80
0.5
0.0
0.00
0.05
0.10
0.15
0.20
0.25
Sediment TN (% DW)
(based on data from: Wetland Solutions, Inc., 2005)
Water Column
POP
DOP
Epiphyte/SAV/ Algal
Mat Biomass (Org-P)
Ca
DIP
Ca-P
POP
DIP
Fe-P
Fe(III)
Fe(II)
Fe-P
Org-C
S2-
DIP
Microbial
DIP Biomass
DOP
AEROBIC
Sediment
Ca-P
ANAEROBIC
Sediment
Research Needs
General
ƒ Data collection
ƒ More than physicochemical parameters
ƒ Spatial/temporal patterns
ƒ Different spring types
ƒ Sediment characterization
Nitrogen
ƒ Assimilation vs. denitrification
ƒ Alternate pathways?
Research Needs
Phosphorus
ƒ Role in limitation (coupling to N)
ƒ Sediment storages/release
Sulfur
ƒ Sulfate reduction/Sulfide toxicity
ƒ Coupling to Fe/P….N
Indicators of Change
ƒ Nutrient ratios
ƒ Response threshhold
ƒ Enzyme activities
ƒ Nutrient limitation
ƒ Process rates
ƒ Stable Isotopic ratios
ƒ Sources
ƒ C,N processes