Transcript AcidDepGay.ppt

Acid Deposition
is “Acid Rain” still a problem?
David Gay
Coordinator
National Atmospheric Deposition Program
University of Illinois, Champaign, IL
217.244.0462, [email protected]
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 1
What is
Acid Deposition?
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 2
Definition
• Precipitation (rain, snow, sleet and so
forth) that is more acidic than normal,
generally due to human-produced air
pollutants
• Acidic precipitation or “acid rain” is
defined by precipitation with a pH <
5.0, to reflect human-induced pollution
Why?
• Carbon dioxide in air
–
–
CO2,g + H2Ol = H2CO3,aq (carbonic acid)
PCO2@350 ppm  pH ~ 5.6
• Naturally occurring acid species also
reduce the pH of rain
–
–
sulfate from oceans
organic acids
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 4
Acid Deposition (in one slide)
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How does pollution get into precipitation?
rainout
washout
sampler
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“Acid Rain” is still an issue
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Frequency of Acidic Precipitation
1985 vs. 2009
Frequency of Acidic Precipitation, %
100
80
60
40
20
0
1984-1986
N = 172
2008-2010
Period
N = 242
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Where are Anthropogenic
Acids Coming From?
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 10
Sulfate (SO42-) &
Nitrate (NO3-)
Smog Formation (HNO3, organic acids)
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 12
Anthropogenic
Gas
Sources
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 13
Trends in US Emissions
SO2
1990 Clean Air Act
Amendments
power plant and
mobile source
emissions reduced
NOx
Source: U.S. EPA
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SO2 Control (and Mercury too)
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 15
Why is Acid
Deposition
Important?
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 16
Human
Irritant
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Environmental Impacts
• Stream and lake acidification
• Increased fish mortality (eggs)
• Damage to vegetation
• Damage to buildings, structures,
statues
• Corrosion of materials
• Contributes to wetland nutrient loads
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 18
Environmental Impacts
• Stream and lake acidification
• Increased fish mortality (eggs)
• Damage to vegetation
• Damage to buildings, structures,
statues
• Corrosion of materials
• Contributes to wetland nutrient loads
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 19
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 20
Environmental Impacts
• Stream and lake acidification
• Increased fish mortality (eggs)
• Damage to vegetation
• Damage to buildings, structures,
statues
• Corrosion of materials
• Contributes to wetland nutrient loads
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 21
pH Effects on Fish Population
MO03
5.0
OH49
4.3
Source: HBRF, Acid Rain Revisited, 2001
pH Effects on Species Abundance
EPA, 2007
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Environmental Impacts
• Stream and lake acidification
• Increased fish mortality (eggs)
• Damage to vegetation
• Damage to buildings, structures,
statues
• Corrosion of materials
• Contributes to wetland nutrient loads
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 24
Damage to Forests
Mt. Mitchell, North Carolina
Spruce Forest, Poland
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Acid deposition effects
Source: HBRF,
Acid Rain Revisited, 2001
Environmental Impacts
• Stream and lake acidification
• Increased fish mortality (eggs)
• Damage to vegetation
• Damage to buildings, structures,
statues
• Corrosion of materials
• Contributes to wetland nutrient loads
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 29
Limestone statue of George Washington first put outside in
New York City in 1944
Source: ACS, Chemistry in Context, 200630
D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 30
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Environmental Impacts
• Stream and lake acidification
• Increased fish mortality (eggs)
• Damage to vegetation
• Damage to buildings, structures,
statues
• Corrosion of materials
• Contributes to wetland nutrient loads
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 34
Nitrogen
Effects
Nitrogen
Damage to
Aquatic Systems
Add Nitrogen to lake or ocean…
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Nitrogen Effects
-Adverse effects on health and the environment
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Chemistry Lesson
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 38
Precipitation Acidity: pH
pH is the power of hydrogen, a measurement of the
hydrogen ion concentration
pH = -log10 [H+]
in moles/liter
H2Ol 
acid
H+aq
+
base
OH-aq
pH 7 is NEUTRAL: [H+] = [OH-]
@pH 7, [H+]=1x10-7 moles per liter
In other words
H2Ol  H+aq + OH-aq
pH 7 is NEUTRAL: [H+] = [OH-]
@pH 7, [H+]=1x10-7 moles per liter
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 40
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 41
Conversion of Sulfur Dioxide to Sulfate
1. Sulfur dioxide conversion to sulfite:
SO2,g
SO42-aq
SO2 + H2O ↔ SO2∙ H2O
SO2∙ H2O ↔ H+ + HSO3HSO3- ↔ H+ + SO32-
2. Oxidation of sulfite to sulfate:
SO32- + O3 ↔ SO42- + O2
also OH -, NOx, formaldehyde, radicals, etc
Seinfeld and Pandis, 1998
Conversion of Nitrogen Dioxide to Nitrate
NO2,g  HNO3,g
HNO3,g
NO3-aq
NO2 + OH∙ + M ↔ HNO3 + M
HNO3 + H2O ↔ H+ + NO3-
Seinfeld and Pandis, 1998
How Do Pollutants Get
into Rain?
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Deposition vs Concentration?
Concentration x rainfall = deposition
CONCENTRATION
Mass of pollutants per unit volume of water collected
(nanograms/liter, milligrams/liter)
DEPOSITION
Mass of pollutant that falls on a fixed unit of area
(kilograms/m2 year)
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 45
SAMPLE
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Concentration x Rainfall = Deposition
Precipitation
9 million Liters precip. /yr
( 35.4 inches rainfall/yr)
100 m
1 ha = 104 m2
100 m
Concentration
1.91 mg/L sulfate ion
Bondville, IL in 2005 (average)
Deposition
17,190,000 mg/ha year
17.2 kg/ha sulfate ion
Bondville, IL in 2005 (total)
Other Depositional Processes…
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What Is the National
Atmospheric
Deposition Program?
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• A Cooperative Research Support Project @UI (USDA)
– measure wet deposition of pollutants (“precipitation”)
– pollution flux out of the atmosphere/into the biosphere
– over North America
• now South America, Asia
– ~ 450,000 precipitation samples
• Started in 1978, 37th year
– “acid rain network”
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NADP’s Goal
To monitor the chemistry of
precipitation (rain and snow) and in
the atmosphere, as consistently and
accurately as we can, for long periods
to determine changes over time
(trends).
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1. National Trends
Network (NTN)
6. Partnership with Clean
Air Status and Trends
Network (CASTNET)
2. Atmospheric Integrated
Research and Monitoring
Network (AIRMoN)
5. Ammonia Monitoring
Network (AMoN)
3. Mercury Deposition
Network (MDN)
4. Atmospheric Mercury
Network (AMNet)
Wet Deposition
Dry Deposition 52
NADP - All Network Sites
Hawaii
Alert Nunavut, Canada
Argentina, South America
Taiwan
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Network #1: National Trends Network (NTN)
Collects one-week precipitation-only samples
concentration and deposition
Analyses
Acids (H+, conductivity)
SO4=, NO3-, NH4+
Na+, Cl-, Ca2+, K+, Mg+
Ortho-phosphate
Weekly mg/L and mg/ha-week
Since 1978
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National Trends Network (NTN)
Currently 256 sites
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Who is NADP?
(100+ total agencies)
Tribal
Organizations
Federal
Agency
Members
Universities
EPA
Taiwan
US
States
Other
Organizations
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Where
Do We Measure Wet
Deposition?
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Where Does NADP Make
Measurements?
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New York City
NTNPass
NV05
CO97, Buffalo
NTN IL11
AIRMoN
PA15 Park
Great
Basin
National
Bondville,
IL
CO02,
Niwot
Saddle
Alert, Nunavut, Canada
MDN FL11
Penn State Univ., PA
Everglades N.P., FL
Alert
Washington DC
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NTN NV05
Great Basin National Park
NTN IL11
Bondville, IL
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 60
AIRMoN PA15
Penn State Univ., PA
MDN FL11
Everglades N.P., FL
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 62
Results
of All This?
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 70
Ammonium (NH4+)
Conversion of Ammonia to Ammonium
NH3,g
NH3 + H2O ↔ NH3∙H2O
NH4+aq
NH3∙H2O ↔ NH4+ + OH-
Seinfeld and Pandis, 1998
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 73
Crustal Cations:
Calcium (Ca2+), Magnesium (Mg2+) &
Potassium (K+)
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 74
What is the role of base cations in
precipitation chemistry?
Base cations neutralize the affects of acidic precipitation
anion sum(1)
MN = 74
NY = 74
cation sum(2)
pH
88
22
6.31
4.34
anions = sulfate, nitrate, and chloride
(2) cations = ammonium, calcium, magnesium,
potassium, and sodium
(1)
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Sulfate, Nitrate and Ammonium
Ion Trends
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 80
Sulfate Deposition Trends
3-year running average
1985 – 2008
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 81
Animation
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Sulfate Trend in Precipitation
1985-2009
INCREASING
Trend
DECREASING
Trend
Number of
Sites
Number
Significant
Number of Sites
Number
Significant
2
0
149
144
Trends
Emissions
Concentration
-51%
-58%
83
100
Sulfate Concentration
Sulfate Deposition
80
60
40
40
20
20
Trend , %
60
0
0
-20
-20
SO2 Emissions-40Reductions
-40
-60
-60
-80
-80
-100
-100
Eastern
Eastern
Sites
Sites
Eastern
Eastern
Sites
Sites
W estern
Western
Sites
Sites
All
All
Sites
Sites
All
All
Sites
Sites
W estern
Western
Sites
Sites
100
Precipitation
80
60
40
20
Trend , %
Trend , %
80
100
0
-20
-40
-60
-80
-100
Eastern
Eastern
Sites
Sites
All
All
Sites
Sites
W estern
Western
Sites
Sites
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Nitrate Deposition Trends
3-year running average
1985 – 2008
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 85
Animation
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Nitrate Trend in Precipitation
1985-2009
INCREASING
Trend
DECREASING
Trend
Number of
Sites
Number
Significant
Number of Sites
Number
Significant
29
9
122
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Trends
Emissions
Concentration
-37%
-22%
87
100
100
Nitrate Concentration
Nitrate Deposition
80
60
60
40
40
20
20
Trend , %
Trend , %
80
0
0
NOx Emissions-20Reductions
-20
-40
-40
-60
-60
-80
-80
-100
-100
Eastern
Sites
Eastern
Sites
All
Sites
All
Sites
W estern
Sites
Western
Sites
Eastern
Eastern
Sites
Sites
All
Sites
All
Sites
W estern
Western
Sites
Sites
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Ammonium Deposition
Trends
3-year running average
1985 – 2008
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 89
Animation
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Animation
Total N dep
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Gaseous Ammonia Observations vs Wet Deposition Observations
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Measurements in Argentina
(AG01)
Enrique H. Bucher
Centro de Zoologia Aplicada
Universidad Nacional de Córdoba
Argentina
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Other Deposition Networks
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 94
Clean Air Status And Trends
(CASTNET)
•
•
•
US’s primary source for data on dry
acidic deposition and rural, groundlevel ozone
Operating since 1987
80 sites across the eastern and western
United States (with NPS)
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 95
Clean Air Status And Trends
(CASTNET)
• Measures
– weekly average atmospheric concentrations of
sulfate, nitrate, ammonium, sulfur dioxide,
and nitric acid
– hourly concentrations of ambient ozone levels
– meteorological conditions required for
calculating dry deposition rates.
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 96
Total Deposition, Sulfate
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 97
Total Deposition, Nitrate
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 98
CASTNET Data
• http://www.epa.gov/castnet/site.html
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Questions?
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 100
Acid Deposition
is “Acid Rain” still a problem?
David Gay
Coordinator
National Atmospheric Deposition Program
University of Illinois, Champaign, IL
217.244.0462, [email protected]
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D. Gay, ITEP Training, Las Vegas, NV 4-7 March 2008, Slide 101