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
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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
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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
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 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
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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
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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
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-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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