Atmospheric Deposition in Pennsylvania
& Impacts on Watersheds
Collaborations
Pennsylvania atmospheric deposition research program:
Penn State Faculty: Jason Bennett, Dave DeWalle, Pat Drohan,
Jim Lynch, Mike Naber; Staff: Matt Borden, Jeff Grimm, Kevin
Horner; Grads: Chris Grant, Lidiia Iavorivska, Dan Lawler.
Elizabeth W. Boyer, Ph.D.
Associate Professor of Water Resources,
Department of Ecosystem Science & Management,
Pennsylvania State University
Email: [email protected]
Web: http://water.psu.edu/boyerlab/
Outline
National Atmospheric Deposition Program -- Mercury
Deposition Network: Bob Brunette, David Gay, Jason Karlstrom,
Martin Risch, Gerard van Der Jagt.
Pennsylvania Department of Environmental Protection,
Bureau of Air Quality: Michael Hopko, Nick Lazor, Donald
Torsello, Joyce Epps.
Atmospheric Deposition
Atmospheric Deposition in Pennsylvania
& Impacts on Watersheds
• Background
• Acid Deposition
– Background, monitoring, research
• Mercury Deposition
– Background, monitoring, research
• Emissions can be transported for short or long distances (e.g.,
up to hundreds of miles) before being deposited.
• Individual emissions sources can affect broad regions.
Atmospheric Deposition
Acid Deposition
• Wet deposition is the fraction contained in precipitation— such
as rain, snow, and fog.
• Dry deposition is the fraction contained in dry fallout – such as
particles, aerosols, and gases.
What is acid rain acid deposition?
Wet & dry deposition from the
atmosphere, containing higherthan-normal amounts of nitric
acids & sulfuric acids
Info source: USEPA, http://www.epa.gov/acidrain/
What is acid deposition?
• The "acid" in acid rain stems primarily from sulfur oxides
(SOx) and nitrogen oxides (NOx).
• SOx and NOx occur from both natural sources (e.g., decaying
vegetation, volcanoes, lightning) & anthropogenic sources
(e.g., emissions from fossil fuel combustion & agriculture).
• Acid rain occurs when
these gases react in the
atmosphere with water,
oxygen, and other
chemicals to form various
acidic compounds (e.g.,
sulfuric acid (H2SO4) and
nitric acid (H2NO3).
Info source: USEPA, http://www.epa.gov/acidrain/
Acid deposition impacts soils & vegetation
• Soil S and N enrichment
• Nutrient cation (Ca2+, Mg2+) depletion
• Al mobilization
Acid deposition impacts water quality
• Acidification of lakes
and streams (lowering
pH levels, decreasing
acid-neutralizing
capacity, increasing
aluminum
concentrations).
• Has reduced species diversity and abundance of aquatic life
(e.g., fish) in many waters.
See: Hubbard Brook Research Foundation, “Acid Rain Revisited”
http://hubbardbrookfoundation.org/acid-rain-revisited/
Trends in SOx emissions
Scale: Largest
bar equals 2.2
million tons of
SO2 emissions
in Ohio, 1990.
Source:
US EPA
See: Hubbard Brook Research Foundation, “Acid Rain Revisited”
http://hubbardbrookfoundation.org/acid-rain-revisited/
Trends in NOx emissions
Scale: Largest bar equals
500,000 tons of NOx emissions
in Ohio, 1990. Source:
US EPA
How much deposition is there, anyway?
How much deposition is there, anyway?
• National Atmospheric Deposition Program National
Trends Network (NADP/NTN)
Wet deposition measured weekly at a
network of sites across the country.
• Clean Air Status & Trends Network (CASTNET)
Dry deposition measured weekly at a
network of sites across the country.
National
monitoring
networks of wet
deposition
(NADP/NTN) and
dry deposition
(CASTNET).
http://nadp.sws.uiuc.edu/
Wet + Dry N&S deposition
Sulfur
Progress in wet deposition as f (CAAA)
Sulfur
Nitrogen
Source: EPA Castnet
Nitrogen
Wet Deposition Flux = Concentration x Volume
Precipitation Volume
– Precipitation collectors
Concentration
Monitoring
– Wet/Dry collectors
– Collected away from vegetation, in open clearing
– Closed when there is no precipitation
Sponsored primarily by the Pennsylvania Department of
Environmental Protection, Bureau of Air Quality,
http://www.dep.state.pa.us/dep/deputate/airwaste/aq/
Upgraded precipitation monitoring equipment
Samplers at Leading Ridge,PA
Upgraded wet / dry
collectors
Goddard
Leading Ridge
Pennsylvania atmospheric deposition monitoring network
Atmospheric Deposition @ Kane
Base “acid rain” sites – measure NH4, NO3, SO4, pH, Ca, Mg, K, Na, Cl
Dry & Wet Sulfur
Dry & Wet Nitrogen
Data are available from the National Atmospheric Deposition
Program, National Trends Network, http://nadp.sws.uiuc.edu/ntn/
Source: EPA Castnet
Long term monitoring of water quality across Pennsylvania
Research Results
(preliminary)
EPA
Sulfate response in streams & lakes
Nitrate response in streams & lakes
• SO4 concentrations are
declining at almost all sites
Nitrate
concentrations are
decreasing in most
regions, but several
lakes and streams
indicate flat or
slightly increasing
nitrate trends.
• In the Southern Blue Ridge
SO4 increasing in many
streams
• Highly weathered soils that
can store large amounts of
deposited sulfate.
• As long-term sulfate
deposition exhausts the
soil’s ability to store sulfate,
a decreasing proportion of
the deposited sulfate is
retained in the soil and an
increasing proportion is
exported to surface waters
EPA
EPA
Mercury Emissions - Globally
Mercury Deposition
• Global mercury
emissions in 2005.
• Mercury emissions come
from a variety of sources
• Individual emissions
sources can affect broad
regions.
From Pacyna et al. 2010
Mercury Emissions in the US
Mercury Emissions in the US
• Mercury emissions come from a variety of sources
• But mostly from coal-fired power plants, in recent decades
Source: EPA report on the environment 2011
Mercury Emissions in the US
Total wet atmospheric mercury deposition, 2011
• Mercury emissions
mostly in the eastern
USA
• PA is a hotspot of Hg
emissions
• Dec. 2011: USEPA
issued the Mercury &
Air Toxics Standards;
1st national standards
to decrease Hg
emissions from
coal/oil power plants.
Shmeltz et al. 2011; 2002 EPA National Emissions Inventory
Source: National Atmospheric Deposition Program, Mercury Deposition Network
Total wet+DRY atmospheric mercury deposition, 2004
Contributions (%) of non-US sources to US total mercury deposition
• EPRI modeled atmospheric wet+dry mercury deposition for 2004.
Source: Krish Vijayaraghavan, AER, EPRI 200X, using advanced modeling system for transport,
emissions, reactions and deposition of atmospheric matter (AMSTERDAM) model.
Mercury emissions
and deposition.
The distance that
mercury can travel in
the air before being
deposited varies, and is
related to the form of
mercury emitted.
• Elemental: relatively
inert
• Reactive gaseous:
more easily dissolved
in water
Figure from Driscoll et
al. 2007.
Statewide freshwater advisories for mercury
How much Hg deposition does PA get, anyway?
Wet mercury deposition monitoring at 11 MDN sites
Monitoring
Sponsored primarily by the Pennsylvania Department of
Environmental Protection, Bureau of Air Quality,
http://www.dep.state.pa.us/dep/deputate/airwaste/aq/
ID
PA00
PA13
PA21
PA29
PA30
PA37
PA42
PA47
PA52
PA60
PA72
weekly monitoring data of wet Hg in PA are available
Annual volume-weighted total mercury concentrations (ng/L) in precipitation
2000 2001 2002 2003 2004 2005 2006 2007 2008
pa00
----10.74 8.31
8.76
7.68
7.67
7.55
10.18 8.4
pa13
9.37
15.26 9.29
8.53
8.12
7.06
7.87
8.36
9.17
pa30
----10.1
9.02
10.27 8.75
8.73
8.47
8.05
7.8
pa37
10.99 9.88
8.68
10.02 8.27
7.42
8.98
8.46
----pa42
------------------------------------pa47
-----------7.59
8.68
7.85
7.72
8.36
8.07
pa52
--------------------------------7.97
pa60
10.14 11.27 9.34
8.31
8.81
8.22
9.75
11.4
9.74
pa72
---9.11
8.8
7.89
9.29
5.71
6.91
6.68
8.02
pa90
9.41
6.79
7.52
7.33
6.88
6.71
7.77
8.99
7.59
2009
6.38
7.3
7.39
--------7.04
6.65
6.13
8.37
6.71
2010
5.81
5.99
9.06
--------6.12
7.12
5.85
5.83
6.58
2011
8.18
8.15
8.24
10.92
6.87
6.71
7.65
7.51
5.85
6.36
Annual total wet mercury depositions (μg/m2)
2000 2001 2002 2003 2004
pa00
----7.118 8.192 10.681 10.138
pa13
8.639 11.818 9.732 11.315 11.387
pa30
----7.678 10.222 10.374 10.197
pa37
9.536 9.224 9.558 12.895 10.363
pa42
--------------------pa47
------------10.273 10.725
pa52
--------------------pa60
11.842 9.051 9.06
13.16 12.962
pa72
----8.778 10.306 11.42 12.674
pa90
7.239 4.964 6.323 8.033 8.287
2009
7.914
7.34
7.827
--------8.216
6.287
7.813
9.428
5.556
2010
6.668
7.167
10.232
--------7.255
7.777
7.79
8.783
6.029
2011
12.729
11.928
10.971
16.268
9.256
9.721
10.251
11.168
11.827
8.518
2005
7.756
6.629
9.188
7.689
----8.142
----9.586
8.108
6.721
2006
8.461
9.521
8.894
9.045
----9.951
----13.426
10.37
8.853
2007
9.216
8.805
8.237
8.7
----7.515
----13.87
8.941
7.367
2008
10.03
10.232
9.169
--------8.601
8.268
11.771
11.127
7.248
Site
Arendtsville
Allegheny Portage NHS
Goddard State Park
Kane Experimental Forest
Erie
Waynesburg
Leading Ridge watershed
Millersville
Little Pine State Park
Valley Forge
Milford
Started
Nov-00
Jan-97
Mar-10
Jun-10
Jun-00
May-99
Mar-10
Nov-02
Jul-07
Nov-99
Sep-00
How much DRY Hg deposition is there, anyway?
• Pilot studies and initial
development of passive
sampling of reactive
gaseous mercury
• Bob Brunette and
colleagues, Frontier Global
Sciences
Our PA
study
How much DRY Hg deposition is there, anyway?
How much DRY Hg deposition is there, anyway?
Preliminary results from PA42, Leading Ridge watershed
• Pilot study of dry Hg variation in PA
over space & time
• 16 sites: 8 Lake Erie, 8 other sites
across the state
• How reliable is a passively-sampled dry
Hg measurement?
On‐date
Off‐date
dry Hg deposition (ng/m2)
wet Hg deposition (ng/m2)
% dry depo
8/30/2011
9/13/2011
9/27/2011
10/11/2011
10/25/2011
9/13/2011
9/27/2011
10/11/2011
10/25/2011
11/8/2011
61.7
24.4
18.8
21.7
54.6
257.0
176.6
186.5
205.6
104.6
24
14
10
11
52
Boyer & Bennett & others, in prep.
How much DRY Hg deposition is there, anyway?
How much DRY Hg deposition is there, anyway?
1st dry mercury
deposition results,
autumn 2009
From Risch et al. 2011
Trends: wet mercury deposition in PA
Trends: mercury concentration in precipitation
• Though precipitation Hg concentrations
declined significantly, there are not
statistically-significant changes in overall wet
Hg deposition, given that it is driven to a large
degree by precipitation rates (↓)
wet atmospheric mercury: deposition trends
Site
# years % per year
pa00 arendsville
11
-0.25
pa13 allegheny portage 15
-0.91
pa30 erie
11
-0.14
pa37 holbrook
8
-1.19
pa47 millersville
10
-3.93
pa60 valley forge
12
-1.58
pa72 milford
11
-0.4
pa90 hills creek
15
-0.2
p value
0.865
0.2545
0.9274
0.5428
0.0159
0.248
0.8039
0.7278
• Example from PA00 at Arendtsville (→)
Annual wet Hg deposition
wet atmospheric mercury: concentration trends
Site
# years % per year p value
pa00 arendsville
11
-3.12
0.0098
pa13 allegheny portage 15
-2.78
0.0001
pa30 erie
11
-1.94
0.0218
pa37 holbrook
8
-3.74
0.0018
pa47 millersville
10
-1.71
0.0876
pa60 valley forge
12
-3.15
0.0119
pa72 milford
11
-4.58
0.0004
pa90 hills creek
15
-2.29
0.0001
• Applied a standard seasonal linear trend model, e.g., PA00 Arendtsville above.
• Statistically significant decreases in concentrations of Hg in precipitation are
observed at most of the PA monitoring sites
Annual precipitation
• Suggests progress due to Hg emissions reductions.
Trends: wet mercury deposition in PA
Research Results
(preliminary)
Mercury deposition: interpolation of monitoring data
Highest mean seasonal
total mercury
concentrations
generally occur during
the summer months
(June-August)
Mercury deposition: interpolation with modeling
High-resolution modeling addresses:
• Influences of local topography on wet
deposition patterns
• Contributions of industrial point-source
emissions to mercury wet deposition
• Bearing of precipitation event trajectories on
the local flux of mercury compounds
• Relationships of mercury wet deposition to
the deposition of ionic species that are better
represented by other precipitation chemistry
monitoring programs
Interpolating measurements from a sparse network of monitoring stations is
inadequate to accurately resolve Hg inputs to the landscape.
Mercury accumulation in PA soils
Wet atmospheric
mercury predictions,
quarterly since 2002 for
PA & region (2009 here)
• Cyan: archived soil pedons from circa
1970 that we re-analyzed for HgT
• Aim to analyze the rest; and
resample contemporary conditions at
forest sites.
500
• Mercury accumulation in these
soils and its variation with
depth is consistent with the
notion that atmospheric
deposition was major source of
mercury to watersheds.
Top: Summer range
<1.50 to >7.0 ug/m2
Bottom: Winter range
<0.25 to >3.25 ug/m2
Hg ng/g
400
300
200
100
0
O
A
E
B
C
R
Master Horizon
Grimm & Boyer., in prep.
Drohan & Boyer & others, preliminary data, pilot study
Mercury variation in PA forested streams
Mercury variation in PA forested streams
• 36 forested streams of PA
•New inputs primarily by atmospheric Deposition
• Sampled streams, mosses, sediments @ baseflow
• Full water chemistry characterization
• Fish tissues @ 7 sites
Led by PhD student Chris Grant
Mercury variation in PA forested streams
Concentrations of mercury
increased among
compartments (stream
water<< stream sediments <
brook trout < aquatic
mosses).
Samples from six
streams (in varying
media) exceeded wildlife
consumption advisory
guidelines for Hg
concentrations.
Concentrations of Hg in water samples from these forested watersheds
were generally low and did not exceed guidelines for human consumption.
Summary
• Boyer Lab group is measuring rates of atmospheric
deposition (of N, S, Hg, and more) in PA (and beyond), and
is exploring the impacts on forested watersheds in
Pennsylvania.
• The rate and extent of surface water recovery from
atmospheric deposition are related to the timing and degree
of atmospheric emissions reductions.
• Long term monitoring of atmospheric deposition and water
quality in PA provides a scientific basis for evaluating the
benefits and effectiveness of changes in emissions.
Questions
Elizabeth W. Boyer
Email: [email protected]
Web: http://water.psu.edu/boyerlab/