1. Biogeochemistry of Wetlands
Institute of Food and Agricultural Sciences (IFAS)
Biogeochemistry of Wetlands
Science and Applications
Biogeochemical Indicators
Wetland Biogeochemistry Laboratory
Soil and Water Science Department
University of Florida
Instructor
K. Ramesh Reddy
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2. Biogeochemical Indicators
Topic Outline
Introduction
Concept of indicators
Guidelines for Indicator Development
Levels of Indicators
Sampling protocol an design
Data analysis
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3. Biogeochemical Indicators- Nutrient Impacts/Recovery
What physical, chemical, and biological properties are affected by nutrient impacts?
What biogeochemical processes are affected by nutrient loading to wetlands?
What biogeochemical indicators or endpoints can be measured to determine nutrient impacts/recovery of wetlands?
Is there a sufficient range of values for biogeochemical indicators so that they may serve as sensitive indicators of nutrient impact/recovery?
Does the distribution and central tendency of biogeochemical indicators discriminate between natural spatial variability and anthropogenic impact in wetlands?
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4. Guidelines for Indicator Development
Conceptual Relevance: Is the indicator relevant to the assessment question (management concern) and to the ecological resource or function at risk?
Feasibility of Implementation: Are the methods for sampling and measuring the environmental variables technically feasible, appropriate, and efficient for use in a monitoring program?
Response Variability: Are human errors of measurements and natural variability over time and space sufficiently understood and documented?
Interpretation and Utility: Will the indicator convey information on ecological conditions that is meaningful to environmental decision-making?
(Jackson et al., 2000, USEPA).
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5. Nutrient Cycling in Soil and Water Column
Emergent
macrophyte
Submerged
macrophyte
Periphyton
Water
Soil C N P
Bioavailable
nutrients S
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6. Nutrient Impacts on Detritus, Soil, and Water
Impacted
Unimpacted
Hours to Days
Water
Hours to Days
< 2 years
< 2 years
Detritus
< years
< years
0-10 cm
> years
> years
10-30 cm
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7. Nutrient Impacts in Wetlands
External
Nutrient
Load
Periphyton
Vegetation
Water
Internal
Nutrient
Load
Detritus
0-10 cm
Microbial/Chemical
Processes
10-30 cm
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8. Biogeochemical Indicators
Spatial Resolution
Sensitivity
Cost
Response Time
Micro
Macro
Scale of measurement of a Process or an Indicator,
and it’s influence on cost and response time
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9. Biogeochemical Processes/Indicators
Nutrient
load
Hydrology
Sediment
load
Soil-Water Column
Biogeochemical
Process
Spatial/
Stressors/
Temporal
Regulators
Patterns
Biogeochemical
Indicator
[Endpoint]
Ecological Function
Algae/
Vegetation
Microbial
Fish Diversity
Diversity
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10. Biogeochemical Indicators
The indicators can be measured at three levels:
Level I - low cost, easily measurable, and less sensitive.
Level II - medium cost, moderate complexity, and moderately sensitive.
Level III - high cost, very complex, and highly sensitive.
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11. Biogeochemical Indicators
Level I - Indicators
Water column: Causal variable
Detritus/Soil: Response and Causal variables
Level II – Indicators
Water, detritus, and Soil: Response variables
Level III – Indicators
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12. Level - I Water Column pH Suspended solids Dissolved oxygen
Conductivity
Salinity
Turbidity
Alkalinity
Color
Biochemical oxygen demand
Water depth
Hardness
Conservative tracers
Dissolved oxygen
Bioavailable nutrients
Ammonium N; nitrate N; dissolved reactive P; dissolved total P
Total phosphorus and nitrogen
Chemical composition of periphyton
Total organic carbon and dissolved organic carbon
Carbon-nitrogen ratios
Carbon-phosphorus ratio
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13. Level - I Soil and Detrital/floc Layers Floc depth Bulk density
Soil pH
Soil redox potential
Extractable nutrients (HCl and Mehlich III)
Extractable ammonium
Loss on ignition (LOI)
Total P, N, and S
C:N:P:S ratios
Extractable metals
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14. Level - II Water Column Primary productivity Heterotrophic respiration
Extracellular enzyme activity
Species composition of periphyton
Diel pH and dissolved oxygen
Biological nitrogen fixation
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15. Level - II Soil and Detrital/floc Layers
Microbial biomass C,N,P, and S
Enzyme activities
Soil porewater nutrients
Soil phosphorus forms
Organic nitrogen
Organic and inorganic sulfur
Single point phosphate isotherm
Extractable metals
Total mercury
Pesticides
Soil mineralogical composition
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16. Level - II Soil and Detrital/floc Layers Soil oxygen demand
Soil-water nutrient exchange rates
Organic matter accretion rates
Equilibrium P concentration (EPCo)
Phosphorus partition coefficients
Detrital decomposition rates
Potentially mineralizable P, N, and S
Nitrification, and denitrification
Iron and sulfate reduction
Methyl mercury
Methanogenesis
Microbial respiration
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17. Level - III Water Column Microbial diversity Cellular fatty acids
rRNA sequence analysis
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18. Level - III Soil and detrital layer Substrate Induced:
Microbial respiration
Organic nitrogen mineralization
Organic phosphorus mineralization
Microbial diversity
Cellular fatty acids
rRNA sequence analysis
Phosphate sorption isotherms
Equilibrium phosphorus concentration (EPCo)
Phosphorus sorption coefficients
Mineralogical composition
Stability of phosphate precipitates and minerals
Stable isotopes
Organic P and C characterization (NMR)
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19. Linkage between Level – I Indicators
and Nutrient Load
Level - I
Response Variable
Nutrient Load
Causal Variable
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20. Level - II Level - I Linkage between Level – I
and Level – II Indicators
Level - II
Response Variable
Level - I
Causal Variable
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21. Level - III Level - II Linkage between Level – II
and Level – III Indicators
Level - III
Response Variable
Level - II
Causal Variable
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22. Data Analysis Level I Level II Analyze Data Identify Indicators
Monitor
STA
Performance
Evaluation
Primary Data
Model
Parameters
Hydro -
Biogeochemical/
Statistical Models
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23. Indicator Evaluation ? Complementary Indicators
Ratio of impacted site relative to reference site
Comparison of sensitivity, time and effort
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24. Nutrient Impact Index Impact Index: log [IS/RS] Distance from inflow 2-1 -2 1 2
Impacted Site [IS]
Reference Site [RS]
Impact Index:
log [IS/RS]
Background level
Distance from inflow
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25. Impact Index Impact Index: log [IS/RS] 1 Severe impact 0.5
0.5 1
-0.5 -1
No Impact- background condition
Moderate impact
Severe impact
Impact Index:
log [IS/RS]
Impact Index
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26. Total Phosphorus in WCA-2A soils (0-10 cm)
1990
1998
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27. Extracellular Enzymes
[Water Conservation Area-2A]
Impact Index = log [IS/RS]
Enzymes Detrital Soil
layer cm]
B-D-Glucosidase
Protease
Alkaline Phosphatase
Arylsulfatase
Phenol Oxidase
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28. Organic Matter Decomposition
[Water Conservation Area-2A]
Impact Index = log [IS/RS]
Process/ Detrital Soil
Indicator layer [0-10 cm]
Respiration
Aerobic
Anaerobic
MBC
MBC/TOC
MBC = Microbial biomass carbon
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29. Nitrogen Transformations
[Water Conservation Area-2A]
Impact Index = log [IS/RS]
Process/ Detrital Soil
Indicator layer [0-10 cm]
PMN
SINM (Alanine)
MBN
SINM/MBN
Nitrification
Denitrification
N2 fixation
SINM = Substrate induced nitrogen mineralization
MBN = Microbial biomass nitrogen
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30. Phosphorus Transformations
[Site: WCA-2A]
Impact Index = log [IS/RS]
Process/ Detrital Soil
Indicator layer [0-10 cm]
PMP
SIPM (G-6-P)
MBP
SIPM/MBP
C/P ratio
Labile Pi
PMP = Potentially mineralizable P; SIPM = substrate induced P mineralization
MBP = microbial biomass P
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31. Microbial Biomass N and PMN Floc- Total N and P Ratios
5000
200
MBN
PMN
4000
150
3000
MBN (mg kg-1)
2000
PMN (mg kg-1 d-1)
100
1000 50
100
200
300
400
100
200
300
400
Molar N:P ratio
Molar N:P ratio
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32. Microbial Biomass P and PMP Floc- Total N and P Ratios
MBP (mg kg-1)
100
200
300
400
500
Molar N:P ratio 10 20 30
PMP (mg kg-1 d-1)
MBP
PMP
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33. Impact Index – Detritus/Floc- WCA-2a1
Microbial Populations [ ]
N2 fixation, PMP, Labile Pi
High impact
B-D-Glucosidase
0.5
Microbial Respiration, MBC, MBP, PMN, SINM, TP, and TPi
Moderate impact
Protease, MBN, Phenol Oxidase, nitrification, Denitrification
Impact Index:
log [IS/RS]
Arylsulfatase, TC, TN
No Impact- background condition
Moderate impact
-0.5
Alkaline Phosphatase Activity, C/P ratio, N/P Ratio
High impact -1
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34. Data Analysis and Synthesis
Descriptive statistics to define frequency distribution and central tendency of biogeochemical indicators
Multivariate analyses to evaluate relationships between biogeochemical indicators and ecological condition
Geostatistical analyses to evaluate spatial patterns and spatial structure of biogeochemical indicators
Predictive modeling to forecast evolution of biogeochemical indicators and ecological integrity
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35. Stepwise Canonical Discriminant Analysis: Abiotic Indicators: Everglades –WCA-2a10 8 F1 F4 U3
Site 6 4 2
Canonicla Variate 1 (u1) -2 -4 -6 -4 -3 -2 -1 1 2 3 4 5
Canonical Variate 2 (u2)
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36. Stepwise Canonical Discriminant Analysis: Biotic Indicators: Everglades –WCA-2a4 F1 F4 U3
Site 3 2 1
Canonical Variate 1 (u1) -1 -2 -3 -4 -3 -2 -1 1 2 3 4 5
Canonical Variate 2 (u2)
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37. Biogeochemical Indicators Paradigm Key Challenges
Simultaneous measurements of “processes” and ‘indicators” at various spatial and temporal scales
Integration of these measurements across scales using statistical and process models
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38. Minimum Data – Level I Water column: Detritus/Floc: Soil: Detrital
Water depth
Total Nitrogen
Total Phosphorus
Detritus/Floc:
Total carbon,
Total nitrogen
Total phosphorus
Soil:
Bulk density
Organic matter content,
Total nitrogen,
Total phosphorus,
Extractable nitrogen,
Extractable phosphorus (Mehlich –1 and 3)
Extractable Fe, Al, Ca, Mg, and K
00- cm
Detrital
Floc
0- cm
Soil
10 cm
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39. Soil Sampling in 2003 Stratified random sampling design
Total number of
sampling sites (n):
1,349 (+~10% replicates)
Floc/detritus
0-10 cm
10-20 cm
Area ~ 8,250 km2
Average sampling density:
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40. Biogeochemical Indicators
Summary
Indicators may reflect biological, chemical, or physical attributes that can be used to characterize current status or to predict impact or change.
Such indicators of wetland ecosystem integrity should be sensitive, reliable, accurate, rapid, and inexpensive.
Indicators should be clearly understood and accepted by scientists, environmental managers, and policy makers.
Indicator levels in accessing impact to wetland ecosystem may be based on the ease of measurement and the ability to respond to change.
Level I indicators are easily measurable whereas level II and III indicators provide more scientifi c rigor and are used to support easily measurable indicators
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41. Biogeochemical Indicators
Summary
Wetland can exhibit a high degree of spatial heterogeneity; thus, the sampling protocol should aim to capture the underlying spatial variability of wetland indicators.
The selection of indicator variable, sampling design, data collection, and statistical/geostatistical methods to analyze dataset is linked.
Before using any selected biogeochemical indicator, a sampling design must be established that represents unimpacted and impacted portions of the wetland to assess early warning signals of decline in ecosystem health.
Each sampling protocol, if possible, should compare environmental conditions to a reference or control site.
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