Trends in the Wet and Dry Deposition of Nitrogen and Sulfur Species Christopher Lehmann

Atmospheric Deposition REMOVAL ATMOSPHERIC TRANSPORT & TRANSFORMATION REACTIONS DRY DEPOSITION AEROSOL PARTICLES & GASES Deposition velocity Precipitation volume/time WET DEPOSITION PRECIPITATION EMISSIONS ADVERSE ENVIRONMENTAL EFFECTS

Atmospheric Emissions 1990 Clean Air Act Amendments 9.1 Tg reduction (1980-2000) 2010 8.1 Tg Source: U.S. EPA

Atmospheric Emissions 1990 Clean Air Act Amendments power plant and mobile source emissions reduced Source: U.S. EPA

Atmospheric Emissions Ammonia Increases? …or not? Source: U.S. EPA

National Trends Network (NTN) Source: NADP

Sulfate Ion Concentrations 1985-2004 1985 1986 1984 Source: NADP

Sulfate Ion Concentrations 1985-2004 2004 2005 2003 Source: NADP

Seasonal Kendall Trend Test, α = 90% Sen’s Median Estimator of Trend Sulfate Trend in Precipitation 1985-2004 INCREASING Trend DECREASING Number of Sites Number Significant 5 154 141 Seasonal Kendall Trend Test, α = 90% Sen’s Median Estimator of Trend

Emissions Concentration Sulfate Trend in Precipitation 1985-2004 INCREASING Trend DECREASING Number of Sites Number Significant 5 154 141 Trends Emissions Concentration -45% -46%

Nitrate Ion Concentrations 1985-2004 1985 1986 1984 Source: NADP

Nitrate Ion Concentrations 1985-2004 2004 2005 2003 Source: NADP

Seasonal Kendall Trend Test, α = 90% Sen’s Median Estimator of Trend Nitrate Trend in Precipitation 1985-2004 INCREASING Trend DECREASING Number of Sites Number Significant 71 36 88 45 Seasonal Kendall Trend Test, α = 90% Sen’s Median Estimator of Trend

Emissions Concentration Nitrate Trend in Precipitation 1985-2004 INCREASING Trend DECREASING Number of Sites Number Significant 71 36 88 45 Trends Emissions Concentration -17% -3%

Ammonium Ion Concentrations 1985-2004 1985 1986 1984 Source: NADP

Ammonium Ion Concentrations 1985-2004 2004 2005 2003 Source: NADP

Seasonal Kendall Trend Test, α = 90% Sen’s Median Estimator of Trend Ammonium Trend in Precipitation 1985-2004 INCREASING Trend DECREASING Number of Sites Number Significant 142 101 17 3 Seasonal Kendall Trend Test, α = 90% Sen’s Median Estimator of Trend

Emissions Concentration Ammonium Trend in Precipitation 1985-2004 INCREASING Trend DECREASING Number of Sites Number Significant 142 101 17 3 Trends Emissions Concentration +24% +29%

Atmospheric Deposition REMOVAL ATMOSPHERIC TRANSPORT & TRANSFORMATION REACTIONS DRY DEPOSITION AEROSOL PARTICLES & GASES Deposition velocity Precipitation volume/time WET DEPOSITION PRECIPITATION EMISSIONS ADVERSE ENVIRONMENTAL EFFECTS

Clean Air Status & Trends Network (CASTNET) Weekly 3-stage filter pack samples Teflon filter: particulate sulfate and nitrate Nylon filter: nitric acid, sulfur dioxide Impregnated cellulose: sulfur dioxide CASTNET Filter Pack Images provided by Clean Air Status and Trends Network (U.S. EPA)

CASTNET Source: www.epa.gov/castnet

Great Basin National Park NTN NV05 Great Basin National Park CASTNET CTH110 Connecticut Hill, NY

Precipitation Sulfate  Concentrations, 2003-2005 (NADP) Particulate Sulfate Concentrations, 2003-2005  (CASTNET)

Particulate Sulfate Concentration Trend Precipitation Sulfate CASTNET NADP/NTN

Precipitation Nitrate  Concentrations, 2003-2005 (NADP) Particulate Nitrate Concentrations, 2003-2005  (CASTNET) ???

Precipitation Ammonium ??? Precipitation Ammonium  Concentrations, 2003-2005 (NADP) Particulate Ammonium Concentrations, 2003-2005  (CASTNET) ???

Precipitation Ammonium Particulate Ammonium Concentration Trend Precipitation Ammonium Concentration Trend CASTNET NADP/NTN

CMU-model Ammonia-N Emissions 2002 (includes soil emissions)

??? ??? Ammonia Emissions vs. Ammonium Trends 2000 - 1990 Emissions Differences ??? Ammonia Emissions vs. Ammonium Trends ??? 1985 – 2004 Ammonium Trend Why do trends in ammonia emissions and ammonium deposition differ?

Sulfate, Ammonium & Nitrate Reactions Transport Distance Ammonium Sulfate NH4+ + NH4+ + HSO4- ⇌ NH4+ SO4= Seinfeld and Pandis, 1998

Sulfate, Ammonium & Nitrate Reactions Transport Distance Ammonium Sulfate NH4+ + NH4+ + HSO4- ⇌ NH4+ SO4= Ammonium Nitrate NH3,g + HNO3,g ⇌ NH4 NO3 Seinfeld and Pandis, 1998

Sulfate, Ammonium & Nitrate Reactions Transport Distance Ammonium Sulfate NH4+ + NH4+ + HSO4- ⇌ NH4+ SO4= Ammonium Nitrate NH3,g + HNO3,g ⇌ NH4 NO3 Ammonia Gas NH3,g Seinfeld and Pandis, 1998

Ammonium vs. Sulfate Trends Bondville, IL Particulate Concentrations Precipitation Concentrations

Ammonia vs. Ammonium Concentrations Bondville, IL LOESS of Raw Data 180-day window

Ammonia Gas vs. Precipitation Ammonium Bondville, IL

Conclusion There is a need for a network of ammonia gas monitoring sites in the U.S. (nitric acid too….) Compare with precipitation ammonium measurements from the NADP/NTN, particulate ammonium from CASTNET Validate ammonia emissions inventories Improves evaluation of nitrogen dry deposition with measurements not currently included in existing networks.

How to Monitor Ammonia Gas Source: www.ogawausa.com

Source: Minutes, NADP Joint Subcommittee, Fall 2005 (attachments)

Acknowledgements S. Larson, V. Bowersox, T. Bond, D. Wuebbles Colleagues at: National Atmospheric Deposition Program Illinois State Water Survey The NADP receives support from the U.S. Geological Survey; Environmental Protection Agency; National Park Service; National Oceanic and Atmospheric Administration; U.S. Department of Agriculture-Forest Service; U.S. Fish & Wildlife Service; Bureau of Land Management; Tennessee Valley Authority; and U.S. Department of Agriculture - Cooperative State Research, Education, and Extension Service via cooperative agreement. Additional support is provided by other federal, state, local, and tribal agencies, State Agricultural Experiment Stations, universities, and nongovernmental organizations. Any findings or conclusions in this presentatoin do not reflect the views of the U.S. Department of Agriculture or other NADP sponsors.