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

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

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.

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.

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)

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

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

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

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

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

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

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 (?)

DEPOSITION HINDCASTS AND FUTURE DEPOSITION UNDER DIFFERENT SCENARIOS

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

MEASURED AND MODEL SIMULATED TIME SERIES

MEASURED AND MODEL SIMULATED TIME SERIES

COMPARISON BETWEEN ANNUAL PREDICTED AND MEASURED STREAM DISCHARGE AND SOLUTES

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

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

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

HISTORICAL DEPOSITION AND FUTURE SCENARIO UNDER CONSTANT CURRENT DEPOSITION

HISTORICAL DEPOSITION AND FUTURE DEPOSITION UNDER DIFFERENT SCENARIOS

ANC RESPONSE TO DECREASES IN SULFATE AND NITRATE DEPOSITION

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

LONG-TERM SULFUR AND NITROGEN MASS BALANCES

LONG-TERM CALCIUM MASS BALANCE

SULFATE AND NITRATE DEPOSITION TRADEOFFS

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.

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

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)

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

Model Performance for the two sites