Trends in the Wet and Dry Deposition of Nitrogen and

Sulfur Species

Christopher Lehmann

Atmospheric Deposition

EMISSIONS

REMOVAL

Precipitation volume/time

WET DEPOSITIONPRECIPITATION

DRY DEPOSITIONAEROSOL PARTICLES

& GASES

Deposition velocity

ATMOSPHERIC TRANSPORT & TRANSFORMATION

REACTIONS

ADVERSEENVIRONMENTAL

EFFECTS

Atmospheric Emissions

0

5

10

15

20

25

30

1970 1975 1980 1985 1990 1995 2000 2005

Em

issi

on

s, T

erag

ram

s

Ammonia Nitrogen Oxides Sulfur Dioxide

2010

8.1 Tg

1990 Clean Air Act Amendments9.1 Tg reduction (1980-2000)

Source: U.S. EPA

Atmospheric Emissions

0

5

10

15

20

25

30

1970 1975 1980 1985 1990 1995 2000 2005

Em

issi

on

s, T

erag

ram

s

Ammonia Nitrogen Oxides Sulfur Dioxide

1990 Clean Air Act Amendmentspower plant and mobile source emissions reduced

Source: U.S. EPA

Atmospheric Emissions

0

5

10

15

20

25

30

1970 1975 1980 1985 1990 1995 2000 2005

Em

issi

on

s, T

erag

ram

s

Ammonia Nitrogen Oxides Sulfur Dioxide

Ammonia Increases?

Source: U.S. EPA

…or not?

National Trends Network (NTN)

Source: NADP

Sulfate Ion Concentrations1985-2004

1985 19861984

Source: NADP

2004 20052003

Sulfate Ion Concentrations1985-2004

Source: NADP

Sulfate Trend in Precipitation1985-2004

INCREASING

Trend

DECREASING

TrendNumber of

SitesNumber

SignificantNumber of Sites Number

Significant

5 0 154 141

Seasonal Kendall Trend Test, α = 90%Sen’s Median Estimator of Trend

Sulfate Trend in Precipitation1985-2004

INCREASING

Trend

DECREASING

TrendNumber of

SitesNumber

SignificantNumber of Sites Number

Significant

5 0 154 141

Trends Emissions Concentration

-45% -46%

Nitrate Ion Concentrations1985-2004

1985 19861984

Source: NADP

Nitrate Ion Concentrations1985-2004

2004 20052003

Source: NADP

INCREASING

Trend

DECREASING

TrendNumber of

SitesNumber

SignificantNumber of Sites Number

Significant

71 36 88 45

Nitrate Trend in Precipitation1985-2004

Seasonal Kendall Trend Test, α = 90%Sen’s Median Estimator of Trend

INCREASING

Trend

DECREASING

TrendNumber of

SitesNumber

SignificantNumber of Sites Number

Significant

71 36 88 45

Nitrate Trend in Precipitation1985-2004

Trends Emissions Concentration

-17% -3%

Ammonium Ion Concentrations1985-2004

1985 19861984

Source: NADP

2004 20052003

Ammonium Ion Concentrations1985-2004

Source: NADP

Ammonium Trend in Precipitation1985-2004

INCREASING

Trend

DECREASING

TrendNumber of

SitesNumber

SignificantNumber of Sites Number

Significant

142 101 17 3

Seasonal Kendall Trend Test, α = 90%Sen’s Median Estimator of Trend

Ammonium Trend in Precipitation1985-2004

INCREASING

Trend

DECREASING

TrendNumber of

SitesNumber

SignificantNumber of Sites Number

Significant

142 101 17 3

Trends Emissions Concentration

+24% +29%

Atmospheric Deposition

EMISSIONS

REMOVAL

Precipitation volume/time

WET DEPOSITIONPRECIPITATION

DRY DEPOSITIONAEROSOL PARTICLES

& GASES

Deposition velocity

ATMOSPHERIC TRANSPORT & TRANSFORMATION

REACTIONS

ADVERSEENVIRONMENTAL

EFFECTS

CASTNET Filter Pack

Images provided by Clean Air Status and Trends Network (U.S. EPA)

Clean Air Status & TrendsNetwork (CASTNET)

• Weekly 3-stage filter pack samples– Teflon filter: particulate sulfate and nitrate– Nylon filter: nitric acid, sulfur dioxide– Impregnated cellulose: sulfur dioxide

CASTNET

Source: www.epa.gov/castnet

NTN NV05Great Basin National Park

CASTNET CTH110Connecticut Hill, NY

Precipitation Sulfate Concentrations, 2003-2005

(NADP)

Particulate SulfateConcentrations, 2003-2005

(CASTNET)

Particulate Sulfate Concentration Trend

Precipitation Sulfate Concentration Trend

NADP/NTNCASTNET

Precipitation Nitrate Concentrations, 2003-2005

(NADP)

Particulate NitrateConcentrations, 2003-2005

(CASTNET)???

???

Precipitation Ammonium Concentrations, 2003-2005

(NADP)

Particulate AmmoniumConcentrations, 2003-2005

(CASTNET)

???

Particulate AmmoniumConcentration Trend

Precipitation AmmoniumConcentration Trend

NADP/NTNCASTNET

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

2000 - 1990 Emissions Differences

???

??? Ammonia Emissions vs.

Ammonium Trends1985 – 2004 Ammonium Trend

Why do trends in ammonia emissions and ammonium

deposition differ?

Sulfate, Ammonium & Nitrate Reactions

Transport Distance

NH4+ HSO4

-+ ⇌ NH4+ NH4

+ SO4=

Seinfeld and Pandis, 1998

NH4+ +

Ammonium Sulfate

Sulfate, Ammonium & Nitrate Reactions

Transport Distance

NH4+ HSO4

-+ ⇌ NH4+ NH4

+ SO4=

NH3,g HNO3,g+ ⇌ NH4 NO3

Seinfeld and Pandis, 1998

NH4+ +

Ammonium Sulfate

Ammonium Nitrate

Sulfate, Ammonium & Nitrate Reactions

Transport Distance

NH4+ HSO4

-+ ⇌ NH4+ NH4

+ SO4=

NH3,g HNO3,g+ ⇌ NH4 NO3

NH3,g

Seinfeld and Pandis, 1998

NH4+ +

Ammonium Sulfate

Ammonium Nitrate

Ammonia Gas

Ammonium vs. Sulfate TrendsBondville, IL

Particulate Concentrations

Precipitation Concentrations

Ammonia vs. Ammonium ConcentrationsBondville, IL

LOESS of Raw Data180-day window

0

20

40

60

80

100

1-Nov-04 6-Nov-04 11-Nov-04 16-Nov-04 21-Nov-04 26-Nov-04 1-Dec-04 6-Dec-04 11-Dec-04

Am

moniu

m c

once

ntr

atio

n in

Pre

cipitat

ion,u

eq/L

0

5

10

15

20

Am

monia

Conce

ntr

atio

n in

Gas

,ppb

Ammonium in Precipitation Ammonia in Gas

Ammonia Gas vs. Precipitation AmmoniumBondville, 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

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.

S. Larson, V. Bowersox, T. Bond, D. Wuebbles

Colleagues at:

National Atmospheric Deposition Program

Illinois State Water Survey