Transcript Slide 1
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
[email protected]
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Biogeochemical Indicators
Topic Outline
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Introduction
Concept of indicators
Guidelines for Indicator
Development
Levels of Indicators
Sampling protocol an design
Data analysis
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Biogeochemical IndicatorsNutrient 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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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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Nutrient Cycling in
Soil and Water Column
Emergent
macrophyte
Submerged
macrophyte
Periphyton
Water
Soil
N
C
P
Bioavailable
nutrients
S
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Nutrient Impacts on
Detritus, Soil, and Water
Impacted
Hours to Days
< 2 years
Unimpacted
Water
Detritus
Hours to Days
< 2 years
< 50-100 years
< 10-15 years
>10- 15 years
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0-10 cm
> 50-100 years
10-30 cm
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Nutrient Impacts in Wetlands
External
Nutrient
Load
Periphyton
Vegetation
Water
Internal
Nutrient
Load
Detritus
0-10 cm
10-30 cm
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Microbial/Chemical
Processes
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Response Time
Cost
Sensitivity
Spatial Resolution
Biogeochemical Indicators
Micro
Macro
Scale of measurement of a Process or an Indicator,
and it’s influence on cost and response time
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Biogeochemical
Processes/Indicators
Nutrient
load
Hydrology
Sediment
load
Soil-Water Column
Spatial/
Temporal
Patterns
Biogeochemical
Process
Stressors/
Regulators
Biogeochemical
Indicator
[Endpoint]
Ecological Function
Algae/
Vegetation
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Fish Diversity
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Microbial
Diversity
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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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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
Water, detritus, and Soil: Response
variables
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Level - I
Water Column
• Dissolved oxygen
• Bioavailable nutrients
• Ammonium N; nitrate N;
dissolved reactive P;
dissolved total P
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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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pH
Suspended solids
Conductivity
Salinity
Turbidity
Alkalinity
Color
Biochemical oxygen demand
Water depth
Hardness
Conservative tracers
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Level - I
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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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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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Level - II
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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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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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Level - III
Water Column
• Microbial diversity
• Cellular fatty acids
• rRNA sequence analysis
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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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Level - I
Response Variable
Linkage between Level – I Indicators
and Nutrient Load
Nutrient Load
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Causal Variable
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Level - II
Response Variable
Linkage between Level – I
and Level – II Indicators
Level - I
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Causal Variable
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Level - III
Response Variable
Linkage between Level – II
and Level – III Indicators
Level - II
Causal Variable
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Data Analysis
Primary Data
Monitor
Indicators
STA
Performance
Evaluation
Level I
Analyze
Data
Identify
Indicators
Level II
Model
Parameters
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Hydro-Biogeochemical/
Statistical Models
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Indicator Evaluation
?
Complementary Indicators
Ratio of impacted site relative to
reference site
Comparison of sensitivity, time
and effort
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Nutrient Impact Index
Impact Index:
log [IS/RS]
2
1
Impacted Site
[IS]
Reference Site
[RS]
0
Background level
-1
-2
Distance from inflow
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1
Impact Index
Impact Index:
log [IS/RS]
Severe impact
0.5
Moderate impact
0
No Impact- background condition
Moderate impact
-0.5
Severe impact
-1
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Total Phosphorus in WCA-2A soils (0-10 cm)
1990
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1998
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Extracellular Enzymes
[Water Conservation Area-2A]
Impact Index = log [IS/RS]
Enzymes
Detrital
layer
B-D-Glucosidase
Protease
Alkaline Phosphatase
Arylsulfatase
Phenol Oxidase
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0.56
0.16
-0.70
-0.10
0.19
Soil
0-10 cm]
0.40
0.07
-0.37
-0.12
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Organic Matter Decomposition
[Water Conservation Area-2A]
Impact Index = log [IS/RS]
Process/
Indicator
Detrital
layer
Respiration
Aerobic
Anaerobic
0.21
0.41
0.23
0.28
0.33
0.30
0.11
0.15
MBC
MBC/TOC
Soil
[0-10 cm]
MBC = Microbial biomass carbon
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Nitrogen Transformations
[Water Conservation Area-2A]
Impact Index = log [IS/RS]
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Process/
Indicator
Detrital
layer
Soil
[0-10 cm]
PMN
SINM (Alanine)
MBN
SINM/MBN
Nitrification
Denitrification
N2 fixation
0.40
0.62
0.23
0.39
0.17
0.31
1.0
0.25
0.45
0.12
0.33
0.20
0.31
SINM = Substrate induced nitrogen mineralization
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MBN = Microbial biomass nitrogen
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Phosphorus Transformations
[Site: WCA-2A]
Impact Index = log [IS/RS]
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Process/
Indicator
Detrital
layer
PMP
SIPM (G-6-P)
MBP
SIPM/MBP
C/P ratio
Labile Pi
0.85
0.08
0.33
-0.28
-0.51
1.07
Soil
[0-10 cm]
-0.03
-0.41
0.17
-0.48
-0.51
0.52
PMP = Potentially mineralizable P; SIPM = substrate induced P mineralization
MBP = microbial biomass P
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Microbial Biomass N and PMN
Floc- Total N and P Ratios
200
MBN
4000
PMN (mg kg-1 d-1)
MBN (mg kg-1)
5000
3000
2000
1000
0
0
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100
200
300
Molar N:P ratio
400
PMN
150
100
50
0
0
100
200
300
400
Molar N:P ratio
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Microbial Biomass P and PMP
Floc- Total N and P Ratios
500
30
MBP (mg kg-1)
PMP (mg kg-1 d-1)
MBP
400
300
200
100
PMP
20
10
0
0
0
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100
200
300
Molar N:P ratio
400
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0
100
200
300
Molar N:P ratio
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Impact Index – Detritus/Floc- WCA-2a
1
Microbial Populations [ 1.7 -2.1]
N2 fixation, PMP, Labile Pi
High impact
Impact Index:
log [IS/RS]
B-D-Glucosidase
0.5
Microbial Respiration, MBC, MBP,
PMN, SINM, TP, and TPi
Moderate impact
Protease, MBN, Phenol Oxidase, nitrification, Denitrification
0
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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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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Stepwise Canonical Discriminant Analysis:
Abiotic Indicators: Everglades –WCA-2a
Canonicla Variate 1 (u1)
10
8
Site
F1
F4
U3
6
4
2
0
-2
-4
-6
-4
-3
-2
-1
0
1
2
3
4
5
Canonical Variate 2 (u2)
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Stepwise Canonical Discriminant Analysis:
Biotic Indicators: Everglades –WCA-2a
Canonical Variate 1 (u1)
4
Site
3
F1
F4
U3
2
1
0
-1
-2
-3
-4
-3
-2
-1
0
1
2
3
4
5
Canonical Variate 2 (u2)
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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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Minimum Data – Level I
Water column:
Water depth
Total Nitrogen
Total Phosphorus
00- cm
Detritus/Floc:
Total carbon,
Total nitrogen
Total phosphorus
0- cm
Detrital
Floc
Soil:
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Bulk density
Organic matter content,
Total carbon,
Total nitrogen,
Total phosphorus,
Extractable nitrogen,
Extractable phosphorus (Mehlich –1 and 3)
Extractable Fe, Al, Ca, Mg, and K
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Soil
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Soil Sampling in 2003
Stratified random
sampling design
Total number of
sampling sites (n):
1,349 (+~10% replicates)
Floc/detritus
0-10 cm
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10-20 cm
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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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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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