N Emissions, Air Quality & N Deposition: Past Trends and Future Projections

Transcription

1 6/18/2010

2 N Emissions, Air Quality & N Deposition: Past Trends and Future Projections Robin L. Dennis National Exposure Research Laboratory Atmospheric Modeling and Analysis Division, US EPA Workshop on Nitrogen Assessment Science in the USA Boulder, CO May 18-20, /18/2010

3 N Emissions and N Deposition Organization of Talk: How nitrogen is involved in deposition Where do the emissions go? Basic estimates of Nr deposition budgets What does inorganic Nr deposition look like? Component contributions Sector contributions Trends Past Anticipated Gaps and Issues 2

4 VOC CO Stationary Sources, Cars, Trucks, Power Plants N2O5 HO2 RO2 NO3 OH H2O O3 Heterogeneous O3 NO NO2 HNO3 NO3 OH PMfine hv O3 Agricultural Sources Power Plants The Partitioning Between Gases and NH3 Gas Phase Fine Particles SO2 OH H2SO4 SO4 PMfine H2O2 O3 Fe Particles, Which Is Determined by Ammonia Availability, Greatly Affects Dry Deposition Rates and Concentrations of ano 3- and aso 4 = 3

5 N fertilizer CMAQ Chemical Fertilizer NHX Deposition county level N Fertilizer Input (kg/km2/yr) < ,000 1,001-3,000 3,001-5,000 5,001-7,000 >7,000 Fertilizer data compiled from:ruddy, B. C., D. L. Lorenz, and D. K. Mueller (2006), County-level estimates of nutrient inputs to the land surface of the conterminous United States, , National Water-Quality Assessment Program Scientific Investigations Report , 17 pp, U.S. Geological Survey, Reston, VA, USA. 4

6 2002 NH 3 Emissions 2002 CMAQ NH X or Reduced-N Deposition 5

7 2002 NO X Emissions 2002 CMAQ Oxidized-N Deposition 6

8 Same Deposition Patterns for Either 12km or 36km Model Grids km Reduced-N Deposition km Oxidized-N Deposition km Reduced-N Deposition km Oxidized-N Deposition 7

9 Where do the Emissions Go? Specie Emitted Percent of Emissions Depositing Reduced Nitrogen (NH 3 ) 76 % Sulfur (SO 2 ) 65 % Oxidized Nitrogen (NO X ) 55 % Budget Calculated for the Eastern 2/3rds of US with CMAQ 8

10 Estimate of Nr Deposition Budget Total N: % 49.2% 33.3% 1.8% Ox-N DIN Anthro Ox-N DIN Lgtng Red-N DIN DON Assumes 25% of wet N deposition is DON and 7.5% of dry N deposition is DON 9

11 What Are Some Features of Inorganic Nr Deposition? Features Ratio Dry Inorganic N to Wet DIN 1.31 Dry Ox-N to Wet Ox-N 1.76 Dry Red-N to Wet Red-N 0.86 Ox-N to Total Inorganic N 0.60 Red-N to Total Inorganic N 0.40 Wet Ox-N to Wet DIN 0.50 Wet Red-N to Wet DIN

12 Features The Dry:Wet Ratio is Not Uniformly Ratio of Dry to Wet Inorganic Nitrogen 11

13 Features The Dry:Wet Ratio of 0.86 for Reduced N Varies Greatly Across Space 2002 Ratio of Dry to Wet Reduced Nitrogen 12

14 Features Local Hot Spots of Reduced N Are Dominant Even Though Overall 60% Is Oxidized N 2002 Ratio of Ox-N to Total Inorganic Nitrogen Deposition 13

15 Budgets by Sector: Base 2002 Deposition Total 2002 Oxidized N Deposition Total 2002 Reduced N Deposition 14

16 Budget Attribution by Sector: Geographically Different 2002 Oxidized-N Deposition U.S Off Road Mobile 9% 0.56 Mobile: On Road 31% 0.40 Industry 10% 0.56 EGU s: Power Plants 19% 15

17 Budget Attribution by Sector: Geographically Different 2002 Reduced-N Deposition U.S. On Road Mobile 6% Poultry 10% Dairy+Beef 19% Chemical Fertilizer % Manure 11% Swine 9%

18 Tons/Year (millions) NO X, SO 2 and NH 3 National Emissions Trends NOx and SO2 and NH3 National Emissions Trends Total NO X Total SO Power Plant SO Power Plant NO X 5.0 Total NH Year Method Change 17

19 Past Trends: NO 3 wet decreases east, increases west NH 4 wet flat in east, increases mid-west and west NO 3 NH 4 Linear Percent Change in Wet Nitrate Concentrations (Dec 1984 Nov 2002) Linear Percent Change in Wet Ammonium Concentrations (Dec 1984 Nov 2002) 18

20 Current Trends NO 3 wet continues down; NH 4 wet little change 2002 NO NH

21 Estimated Future Trends: Oxidized-N deposition decreases significantly Reduced-N deposition increases slightly (not shown) 2002 Oxidized N Deposition Scale at ½ 2020 Oxidized N Deposition

22 Estimated Future Trends: 22% Reduction in Inorganic N Deposition But Hot Spots Remain (NH 3 going up and SO 4= going down) 2002 Total N Deposition 2020 Total N Deposition

23 Estimated Future Trends: 42% Reduction in oxidized-n for eastern 2/3rds of US Ratio of 2020 to 2002: Total N Deposition Ratio of 2020 to 2002: Oxidized N Deposition 22

24 % Mobile: On Road 16% 2020 Budget Attribution Changes by Sector: 2002 to 2020 for Oxidized Nitrogen % 10% EGU s: Power Plants Industry 14% 19% 23

25 Observations on Where We Are Headed Expect to move to an overall dominance of reduced-n deposition in the eastern half of the US as oxidized-n deposition is reduced 2002 Ox-N/Red-N estimated at 60/ Ox-N/Red-N estimated at 44/56 The Nr deposition in the western half of the US outside of coastal states (CA, OR, WA) is expected to increase The atmospheric deposition model can provide great insights and fill in many gaps of information, but it still needs improvement and better inputs. There are under predictions of concern in the great western basin. Estimation inconsistencies exist between the different sources of data and DON is an unknown to be deciphered 24

26 Adjusted CMAQ (kg/ha) Gaps / Issues / New Work: Continue to Improve Emission Inventories Adjusted CMAQ (kg/ha) Adjusted CMAQ (kg/ha) Ox-N: Inclusion of lightning NO X emissions will nearly eliminate the bias in east but still under predictions remain in the west, leaving uncertainties in national estimates Red-N: Incorporation of bi-directional flux of NH 3 will help in the mid-west but still under predictions remain in the west, leaving uncertainties in national estimates SO4 Wet: Model values adjusted with NADP precipitation. NO3 Wet: Model values adjusted with NADP precipitation. NH4 Wet: Model values adjusted with NADP precipitation. R 2 =0.88 R 2 =0.84 R 2 =0.68 Corrected for precipitation errors Corrected for precipitation errors Corrected for precipitation errors Observed SO4 Wet Deposition (kg/ha) Observed NO3 Wet Deposition (kg/ha) Observed NH4 Wet Deposition (kg/ha) 25

27 Gaps / Issues / New Work: Bi-directional Surface Exchange of NH 3 Sensitivity study shows that bi-directional flux algorithms make a difference in the NH 3 budget partitioning calculated by the regional air deposition model Model Development Implementation in CMAQ of bi-directional NH 3 exchange parameterizations Regional implementation of USDA EPIC to estimate NH 3 fertilizer applications for NH 3 bi-directional flux calculations Cumulative regional NH3 budget of advection, wet- and dry-deposition, calculated for an expanding box starting at a high-emitting Sampson County, NC cell 26

28 Gaps / Issues / New Work: Monitor Complete N Air Concentration Budget Fraction of Total-N Dry Deposition Associated with Species Measured by Networks (CASTNet) km CMAQ Several gas species important to model evaluation and understanding of the full inorganic system and the partitioning affecting deposition are not currently being monitored, with NH 3, PAN and NO/NO 2 being the most significant omissions. There is no routine monitoring of DON 27

29 Gaps / Issues / New Work: Consistent Agriculture/Fertilizer Budget Current Development Activities Estimation of regional commercial N application with USDA EPIC, plant uptake of N from the air, and NH 3 emission to air (NH 3 bi-directional flux calculations) Estimation of resulting transformation (including denitrification) and edge-of field surface and sub-surface losses (to narrow the N budget) Future ORD Development Refine estimates of agriculture-dominated emissions of NO and N 2 O associated with denitrification Create an Emissions Budget for DON How important is it? What is it? What are the sources? Does it track with NO X and NH 3 emissions? How do we create an emissions inventory? Evaluate/Improve Uni-directional deposition algorithms Special, collaborative field work (modelers and measurers) 28

30 Acknowledgements The collaboration with colleagues in AMAD: Wyat Appel Kristen Foley Ellen Cooter Jesse Bash Jon Pleim Data and Information from NADP PRISM data: PRISM Climate Group, Oregon State University, created 5 May

31 EXTRA SLIDES 30

32 VOC CO N2O5 Stationary Sources, Cars, Trucks, Power Plants HO2 RO2 NO3 OH H2O O3 Heterogeneous O3 NO NO2 HNO3 NO3 OH PMfine hv O3 Agricultural Sources NH3 Gas Phase Fine Particles Power Plants SO2 OH H2SO4 SO4 PMfine H2O2 O3 Fe Fossil Fuel Combustion that Produces Nitrogen and Sulfur Oxides (NO X and SO X ) and Agricultural Production that Produces Ammonia are are the Main Sources of Inorganic PM 2.5 and Nitrogen Deposition 31

33 A Shift in Form is also Expected Today Ox-N is Dominant Form of N-Deposition in Most Non-Agricultural Places However, Ammonia Deposition will Increase in Importance in the Future Fraction of Total Deposition as Ox-N Deposition 2001 Base CMAQ 36-km 2020 CAIR CMAQ 36-km 32

34 Fraction of Oxidized-N Dry Deposition Associated with Species Measured by Networks (CASTNet) km CMAQ Fraction of Reduced-N Dry Deposition Associated with Species Measured by Networks (CASTNet) km CMAQ 33

35 Past Trends Linear Percent Change in Wet Nitrate Concentrations (Dec 1984 Nov 2002) 34

36 Past Trends Linear Percent Change in Ammonium Wet Concentrations (Dec 1984 Nov 2002) 35

37 NH 3 Emissions in Eastern US Dominated by Animal Operations Fraction of Total NH 3 Emissions as Emissions from Animal Operations 36

38 NH 3 Air-Surface Exchange is Bi-Directional a R a c R ac R bg g Bi-directional Model soil R b R b R st R w plants s Compensation Points: Internal Levels of NH 4+ /H + => Air-Plant/Soil Levels of NH 3 If ambient NH 3 A then NH 3 will be taken up by the plant stomata or deposited to the soil If ambient NH 3 A then NH 3 will be emitted by the plant stomata or emitted by the soil s,g s,g 37

39 Average ammonia flux over soybeans in Eastern NC Model Observed Hour (LT) 38

40 Range of Influence: Single NC Maximum Cell BaseVd NH 3 as SO 2 Vd NH 3 Bi-Dir The Range of Influence of NH 3 Emissions is Influenced by the Dry Deposition Formulation. It Increases With a Change from the Base CMAQ M3dry to the Bi-directional Flux Formulation for NH 3 39