1. Great Smoky Mountains national ParkBy
Charles Driscoll & Qingtao Zhou
Syracuse University
November 23, 2010
Great Smoky Mountains national Park

2. Agenda Time Activity Speaker 1:00-1:10 Introductions Steve Moore
1:10-1:30
Project overview and PnET-BGC
Charley Driscoll
1:30-2:00
Model calibration and testing
Qingtao Zhou
2:00-2:30
Model application for CL/TMDL calculations
2:30-2:50
Next steps
2:50-3:10
Break
3:30-5:00
Discussion
All

3. Objective
The overarching objective of this study is: To provide a framework to assess the response of soils and streams in watersheds of the GRSM to decreases in acidic deposition, through analysis of existing data and application of the biogeochemical model PnET-BGC.

4. Specific Objectives
Compile and analyze existing data available for the GRSM on atmospheric deposition, soils, forest vegetation, hydrology, stream chemistry and aquatic biota to provide inputs, parameter values, and ecosystem observations for application of PnET-BGC;
Parameterize, calibrate and test PnET-BGC for a suite of stream- watersheds at the GRSM;
Simulate the response of the study stream-watersheds to a range of decreases in atmospheric deposition of sulfate, nitrate and ammonium, evaluate the TMDLs/critical loads of sulfur and nitrogen for these ecosystems, and determine the time required to reach critical levels of chemical indicators of acidification stress; and
Interact with National Park Service personnel and interested stakeholders on results of model calculations, and conduct outreach activities, including developing a web site for project results, presentation of findings at professional meetings, publication of results in peer-reviewed journals, and translation/communication of results to stakeholders and the general public.

5. Site Data Atmospheric deposition (temporal, spatial; largely acquired)
Historical deposition (acquired, but might be improved)
Meteorological data (temporal; spatial; largely acquired)
Land disturbance (some acquired)
Soil and soil solution data (acquired)
Stream discharge and chemistry (acquired)

6. Measurement
Basis
Use
Priority
INPUTS
Max-min air temperature
oC; Monthly or finer timescale; long time series
Model input 1
Precipitation quantity
cm/mo; Monthly or finer timescale; long time series
Incident solar radiation (PAR)
Monthly or finer (mmol/m2-s) 2
Soil bulk density
(Soil mass per unit area)
Once (kg m-2)
Wet deposition
g/m2-mo; all major solutes; Monthly or finer; long time series
Dry to wet ratio
Molar ratio; all major solutes; once
Forest disturbance (logging, fire, storm)
Year; Intensity: the fraction of the watershed that is disturbed by the disturbance event;
Removal Fraction: the fraction of the forest biomass removed from the watershed during the disturbance event;
Soil loss fraction: Quantity of soil forest floor removal during disturbance event
Watershed area and latitude m2
Model calculations
Major tree species
e.g.,
Northern Hardwoods, Spruce-Fir, Red Oak-Red Maple, Red Pine
Model calculation

7. Measurement
Basis
Use
Priority
PARAMETER
Vegetation chemistry
Vegetation stoichiometry
(Element Organic Content and Element Plant Tissue)
g/g DW; g/g N; Once 3
Soil exchangeable cations
eq/kg; Once
Soil selectivity coefficients; test model 2
Soil solution chemistry
µmol/L; Once
Soil selectivity
Adsorbed anions; or anion adsorption isotherms
Once
Anion adsorption
Foliar exchange/uptake (H, Mg, K, Ca, NH4)
Regulating net throughfall flux
Weathering
g / m2 - mo; Once
Model Input

8. Measurement
Basis
Use
Priority
OUTPUTS
Stream discharge
mm/m2-mo; Monthly or finer; long time series
Model testing 1
Stream chemistry
µmol/L; monthly or finer; long time series
Litterfall and chemistry
g/m2-mo; g/g; once or whenever available 3
N mineralization rates
g N/m2-mo; once or whenever available
Nitrification rates
Aboveground biomass
g/m2 ; once or whenever available 2
Aboveground biomass increment
NPP / NEP
g C/m2-yr
Elements in different soil pools (Humus, litterfall, solid phase, mineralization, uptake)
g element/m2-mo

9. Climatic data Solar radiation Precipitation Temperature Deposition
Wet
Deposition
Dry
Deposition
Climatic data
Solar radiation
Precipitation
Temperature
PnET
Water balance
Photosynthesis
Living biomass
Litterfall
Net Mineralization
Uptake
BGC
Aqueous reactions
Surface reactions
Cation exchange
Adsorption
Humic binding
Aluminum dissolution/precipitation
Shallow water flow
BGC – Surface water
Aqueous reactions
Deep water flow
Weathering

10. Initial Model application Sites
Noland Divide (initiated)
Road Prong (initiated)
Rock Creek (not initiated)

11. Model testing Agreement between measured and predicted values
Time series analysis
Mass balance calculations
pH predictions (ANC, DIC, DOC, Al)
Comparison of model results across sites

13. Model application
Prediction of time series of watershed biogeochemical responses following future changes in sulfate, nitrate and ammonium deposition
Examination of tradeoffs concerning sulfate vs nitrate and nitrate vs ammonium deposition
Determination of ANC and pH response to changes in deposition
Model application to TMDL stream sites
Model application to Park (?)

14. DEPOSITION HINDCASTS AND FUTURE DEPOSITION UNDER DIFFERENT SCENARIOS

15. MODEL TESTING AND APPLICATION
Model Results
Noland Divide Watershed
Model Performance
Mass balance
Hindcast and forecasts of model simulations
Trade offs SO42- vs NO3- deposition

16. MEASURED AND MODEL SIMULATED TIME SERIES

17. MEASURED AND MODEL SIMULATED TIME SERIES

18. COMPARISON BETWEEN ANNUAL PREDICTED AND MEASURED STREAM DISCHARGE AND SOLUTES

19. MODEL PREDICTED ELEMENT FLUXES (1993-2008)
NH4-N(kg/ha-yr)
NO3-N
SO4-S Ca
Deposition
4.08
12.7
29.1
19.6
Weathering
1.2
12.8
Mineralization
34.2
14.8
36.4
Nitrification
-25.7
25.7
Plant Uptake
-11.6
-31.8
-14.7
-46.7
Sorption
-12.5
-14.5
Drainage losses
-4.92
-9.31
-19.3
Note: Positive=Input; Negative=Output

20. COMPARISION OF MODELED AND MEASURED FLUXES
NH4-N(kg/ha-yr）
NO3-N(kg/ha-yr）
IFS
UTM
Model
Throughfall Deposition
0.28
4.08
16.8
12.7
Weathering
Mineralization
34.2
Nitrification
-25.7
25.7
Plant Uptake
-11.6
-26.4
-31.8
Sorption
Drainage losses
0.3
-9.92
-4.92

21. COMPARISON OF MEASURED AND MODELED FLUXES
SO4-S (kg/ha-yr)
Ca (kg/ha-yr）
IFS
UTM
Model
Throughfall Deposition 40 32
29.1
18.76
19.6
Weathering
1.2
5.4
12.8
Mineralization
14.8
36.4
Nitrification
Plant Uptake
-3.5
-14.7
8.65
-46.7
Sorption
12.5
-14.5
Drainage losses
-10.24
-9.31
-16.54
-19.3

22. HISTORICAL DEPOSITION AND FUTURE SCENARIO UNDER CONSTANT CURRENT DEPOSITION

25. HISTORICAL DEPOSITION AND FUTURE DEPOSITION UNDER DIFFERENT SCENARIOS

26. ANC RESPONSE TO DECREASES IN SULFATE AND NITRATE DEPOSITION

27. DIFFERENTIAL ANC RESPONSE TO SULFATE vs. NITRATE DEPOSITION
DCL2050
0.0023
0.11
CL2200
0.032
0.14 9

28. LONG-TERM SULFUR AND NITROGEN MASS BALANCES

29. LONG-TERM CALCIUM MASS BALANCE

30. SULFATE AND NITRATE DEPOSITION TRADEOFFS

31. Future Activities Complete model testing for intensive study sites
Model testing pH-ANC relationships
Future scenario testing for TMDL sites
Model application for entire Park (?)
Project communication activities.

32. Project issues TMDL/CLs for 303d streams vs Park-wide stream classes
Additional intensive stream sites
Establishment of critical chemical limits pH >6.0; ANC >20, 50 µeq/L

33. Additional data needs Sulfate adsorption isotherms
Information on land disturbance history
Park deposition GIS (requested from K. Weathers)
Park temperature, precipitation GIS (working with J. Fridley)

34. Project communication
Establishment of project web site to post results (password protected)
Professional presentations and papers

35. Model Performance for the two sites