Cloud Deposition Monitoring Clingmans Dome, TN Summary Report, October 2012 Great Smoky Mountains National Park Summary Report, October 2012


Clingmans Dome, TN

Great Smoky Mountains National Park



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Summary Report, October 2012

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Cloud Deposition Monitoring
Clingmans Dome, TN
Great Smoky Mountains National Park

Summary Report

Prepared for:

U.S. Environmental Protection Agency
Clean Air Markets Division
Office of Air and Radiation
Washington, DC

EPA Contract Number: EP-W-09-028

Prepared by:

AMEC Environment & Infrastructure, Inc.
Gainesville, FL

AMEC Project Number: 6064110217

October 2012

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

Table of Contents

1.0 Introduction	1

2.0 Project Description and Methods	2

2.1	Field Operations	2

2.2	Laboratory Operations	3

2.3	Data Management	4

2.4	Quality Assurance	5

3.0 Project Results	6

3.1	Liquid Water Content and Cloud Frequency	6

3.2	Sample Collection and Acceptance	7

3.3	Cloud Water Chemistry	8

3.4	Cloud Water Deposition	12

3.5	Total Deposition	15

4.0 Conclusions	17

4.1	Cloud Water Concentrations and Deposition Estimates	17

4.2	Future Studies	19

5.0 References	21

List of Tables
List of Figures

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List of Tables

Table 3-1. Number of Cloud Water Samples Accepted for Analyses
Table 4-1. Power Plant Emission Reductions (percent) from 2000 through 2011 for
Tennessee and Nearby States

List of Figures

Figure 3-1. Monthly Cloud Frequency Statistics (1995-2007, 2009-2011)

Figure 3-2. Monthly Mean Liquid Water Content Statistics (1995-2007, 2009-2011)

Figure 3-3. Mean Major Ion Concentrations of Cloud Water Samples (1995-2007,
2009-2011)

Figure 3-4. Mean Minor Ion Concentrations of Cloud Water Samples (Cations and Chloride)

1995-2007, 2009-2011
Figure 3-5. Mean Seasonal Cloud Water versus Mean Seasonal Precipitation Sulfate

Concentrations, 1995-2011
Figure 3-6. Mean Seasonal Cloud Water versus Mean Seasonal Precipitation Nitrate

Concentrations, 1995-2011
Figure 3-7. Seasonal Deposition Estimates for Major Ions (1999-2007, 2009-2011)

Figure 3-8. Seasonal Deposition Estimates for Hydrogen (1999-2007, 2009-2011)

Figure 3-9. Mean 3-year Seasonal Deposition Estimates for Major Ions, 1999-2001
and 2009-2011

Figure 3-10. Cloud Water and Wet Sulfate Deposition Estimates (June through September,
1995-2011)

Figure 3-11. Cloud Water and Wet Nitrate Deposition Estimates (June through September,
1995-2011)

Figure 3-12. Seasonal Sulfur Deposition (2000-2011)

Figure 3-13. Seasonal Nitrogen Deposition (2000-2011)

Figure 4-1. Seasonal Cloud Water S024 Concentrations and Depositions and TVA Annual

SO, Emissions (2000-2011)

Figure 4-2. Seasonal Cloud Water NOj Concentrations and Depositions and TVA Annual
NOx Emissions (2000-2011)

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List of Acronyms and Abbreviations

AMEC

AMEC Environment & Infrastructure, Inc.

°C

degrees Celsius

Ca2+

calcium ion

CASTNET

Clean Air Status and Trends Network

CCV

continuing calibration verification spikes

CLOUD

cloud water deposition computer model

cr

chloride ion

CLD303

Clingmans Dome, TN sampling site

cm

centimeter

DAS

data acquisition system

EPA

U.S. Environmental Protection Agency

g/m3

grams per cubic meter

GRS420

Great Smoky Mountains National Park, TN dry deposition sampling site

ft

hydrogen ion

HNO,

nitric acid

K+

potassium ion

kg/ha

kilograms per hectare

Lpm

liters per minute

LWC

liquid water content

m

meters

MADPro

Mountain Acid Deposition Program

MCCP

Mountain Cloud Chemistry Program

Mg2+

magnesium ion

N

nitrogen

Na+

sodium ion

NADP

National Atmospheric Deposition Program

NTN

National Trends Network

NAPAP

National Acid Precipitation Assessment Program

nh4+

ammonium ion

no3

nitrate ion

NOx

oxides of nitrogen

NPS

National Park Service

pH

p(otential of) H(ydrogen)

PVM

particle volume monitor

QA

quality assurance

QAPP

Quality Assurance Project Plan

QC

quality control

RPD

relative percent difference

Hi

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List of Acronyms and Abbreviations (continued)

S	sulfur

SO4	sulfate ion

SO,	sulfur dioxide

TN 11	Elkmont, TN NADP/NTN wet deposition sampling site

TVA	Tennessee Valley Authority

|ieq/L	microequivalents per liter

|ig/filter	micrograms per filter

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

1.0 Introduction

The Mountain Acid Deposition Program (MADPRO) began in 1993 as part of the Environmental
Protection Agency's (EPA) Clean Air Status and Trends Network (CASTNET) and operated
through September 2011. MADPRO data contributed to CASTNET's objective of determining
the status and trends in air quality and pollutant deposition as well as relationships among
emissions, air quality, and ecological effects. The program accomplished this by updating the
cloud water concentration and deposition data collected by the Mountain Cloud Chemistry Project
(MCCP) during the National Acid Precipitation Assessment Program (NAPAP) of the 1980s.

Cloud water samples were collected at Clingmans Dome, TN (CLD303) in the Great Smoky
Mountains National Park during the warm season (usually May through October) and analyzed for
their pollutant constituents. The cloud water concentrations were then used for estimation of cloud
deposition of these pollutants.

CLD303 was operated under the direction and funding of EPA and the Tennessee Valley
Authority (TVA) with infrastructure support provided by the National Park Service (NPS). For
more details on the operating history of MADPRO, as well as the MCCP, please refer to
previous MADPRO reports (http://java.epa.gov/castnet/documents.do) andMADPro: Cloud
Deposition to the Appalachian Mountains, 1994 to 1999 (EPA, 2000).

The MADPRO task order under EPA Contract No. EP-W-09-028 will end 31 October 2012. To
date, the collection site has been decommissioned, all samples have been analyzed, and the 2011
results reported in the 2011 annual report (AMEC, 2012). The purpose of this report is to provide
a summary of project results and conclusions with suggestions for future cloud water research.

GRS420

GREAT SMOKY MOUNTAINS

NATIONAL PARK

CLD303

For 2011, cloud water and meteorological parameters were measured at the CLD303 site.
Atmospheric pollutant concentrations for estimating dry deposition were obtained from the
nearest CASTNET site (GRS420, TN). Wet deposition data were obtained from Elkmont,
TN (TN 11), which is operated by NPS for the National Atmospheric Deposition Program
(NADP)/National Trends Network (NTN).

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2.0 Project Description and Methods

Clingmans Dome (35'33'47"N, 83'29'55"W) is the highest mountain [summit 2,025 meters (m)]
in the Great Smoky Mountains National Park. The solar-powered CLD303 site was situated at an
elevation of 2,014 m approximately 100 m southeast of the summit tourist observation tower.
Electronic instrumentation was housed in a small NPS building, and the cloud water collector,
particle volume monitor (PVM), and meteorological sensors were positioned on top of a 50-foot
scaffold tower. Collection of cloud water samples was initiated each spring, as soon as local
conditions would allow, and continued through the warm season, generally ending in October.

2.1 Field Operations

The cloud collection system consisted of an automated cloud water collector for bulk cloud water
sampling, a PVM for continuous determination of cloud liquid water content (LWC) and cloud
frequency, and a data acquisition system (DAS) for collection and storage of electronic
information from the various monitors and sensors. Continuous measurements of wind speed,
wind direction, temperature, solar radiation, relative humidity, wetness, and precipitation were
collected through 2004. Beginning in 2005, only those sensors essential for the operati on of the
cloud collector (namely, temperature and precipitation sensors and a rain gauge) were deployed.
The scalar wind speed data required for calculation of cloud deposition estimates were obtained
from the NPS instrument situated on a tower located next to the cloud collection tower. Prior to
2005, the site deployed the same 3-stage filter pack system for dry deposition estimation that is
used at all CASTNET sites. Starting in 2005, these data were obtained from the Great Smoky
Mountains National Park, TN, CASTNET site (GRS420), which is located 26 miles west,
northwest of the Clingmans Dome cloud water sampling site.

The core of the automated cloud collection system is a passive string collector previously used in
the MCCP study. The development and design of the original system is described in detail in
Baumgardner etal. (1997).

Cloud Water Collector

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The PVM-100 by Gerber Scientific (Gerber, 1984) measures LWC and effective droplet radius
of ambient clouds by directing a diode-emitted 780-nanometer wavelength laser beam along a
40-centimeter (cm) path. The forward scatter of the cloud droplets in the open air along the path
is measured, translated, and expressed as water in grams per cubic meter (g/m3) of air. The data
logger was programmed so that the collector was activated and projected out of the protective
housing when threshold levels for LWC (0.05 g/m3) and ambient air temperature [> 2 degrees
Celsius (°C)] were reached. Within the context of MADPro, a cloud was defined by a LWC of
0.05 g/m' or higher, as measured by the PVM. In addition, the system was activated only when
no precipitation was measured.

Filter packs for collection of dry deposition samples at the nearby GRS420 site were prepared
and shipped to the field on a weekly basis and exchanged at the site every Tuesday. For a
description of the filter pack set-up, types of filters used, and the fraction collected on each filter,
refer to the CASTNET Quality Assurance Project Plan (QAPP) Revision 7.0 (AMEC, 2011). A
discussion of filter pack sampling artifacts can be found in Anlauf et a/. (1986) and Lavery et al.
(2007). Filter pack flow at the CASTNET GRS420 site is maintained at 3.0 liters per minute
(Lpm) with a mass flow controller.

Particle Volume Monitor

2.2 Laboratory Operations

Cloud water samples for the project were analyzed for sodium (Na+), potassium (K ),
ammonium (NII[), calcium (Ca2+), magnesium (Mg2+), chloride (CI"), nitrate (NO,), and sulfate
(SO4) ions in the AMEC Environment & Infrastructure, Inc. (AMEC) CASTNET laboratory in
Gainesville, FL. All samples were analyzed for pH and conductivity in the AMEC CASTNET
laboratory for comparison with the field values.

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Cloud Deposition Monitoring — Clingmans Dome, IN — Great Smoky Mountains National Park — Summary Report

Concentrations of the three anions (SO2,", NOj, and CI") were determined by micromembrane-
suppressed ion chromatography. Analysis of samples for Na+, Mg2+, Ca', and K was performed
with a Perkin-Elmer Optima 7300 Dual View inductively coupled argon plasma-atomic emission
spectrometer. The automated indophenol method using a Bran+Luebbe Autoanalyzer 3 was used
to determine NH4f concentrations.

Filter pack samples were loaded, shipped, received, extracted, and analyzed at the CASTNET
laboratory. For specific extraction procedures refer to Anlauf et al. (1986) and the CASTNET
QAPP (AMEC, 2011). Filter packs contain three filter types in sequence: a Teflon filter for
collection of aerosols, a nylon filter for collection of nitric acid (HN03) and SO,, and dual
potassium carbonate-impregnated cellulose filters for collection of SO,. Following receipt from
the field, exposed filters and unexposed blanks were extracted and analyzed for SO2",. NO,, CI",
and the cations, MI •*. Na+, Mg2+, Ca2+, and K , as described previously for cloud water samples.
Refer to the CASTNET QAPP (AMEC, 2011) for detailed descriptions of laboratory receipt,
breakdown, storage, extraction, and analytical procedures.

3-Stage Filter Pack

Atmospheric concentrations derived from filter extracts were calculated based on the volume of
air sampled following validation of the hourly flow data. Atmospheric concentrations of
particulate SO2,", N03, NFI4, Na+, K+, Ca , Mg , and CI" were calculated based on analysis of
Teflon filter extracts; UNO, was calculated based on the N03 found in the nylon filter extracts;
some SO, was trapped by the nylon filter, so SO, was calculated based on the sum of SO4 found
in nylon and cellulose filter extracts.

2.3 Data Management

Continuous data (temperature, precipitation, LWC, and cloud collector status information) were
collected in hourly and 5-minute averages. Hourly data were collected daily via Internet
protocol-based polling. The hourly data and associated status flags were ingested into Microsoft
Excel spreadsheets. The PVM data were validated based on the end-of-season calibration results,
periodic calibration check results, and information provided by status flags and logbook entries.

Discrete data for cloud water sample results and filter pack sample results were managed by
Element, the laboratory information management system. In Element, the analytical batches were

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Cloud Deposition Monitoring — Clingmans Dome, IN — Great Smoky Mountains National Park — Summary Report

processed through an automated quality control (QC) check routine. For each analytical batch, an
alarm flag was generated if any of the following occurred:

• Insufficient QC data were ran for the batch;

• Sample response exceeded the maximum standard response in the standard curve
(i.e., sample required dilution);

• Continuing calibration verification (CCV) spikes exceeded recovery limits; or

• Reference samples exceeded accuracy acceptance limits.

A batch with one or more flags was accepted only if written justification was provi ded by the
Laboratory Operations Manager or his designee.

For cloud water samples, an additional check involved calculating the percent difference of
cations versus anions (ion balance), which provided another diagnostic for determining whether
the analysis should be repeated or verified.

Atmospheric concentrations for filter pack samples were calculated by merging validated
continuous flow data with the laboratory data [micrograms per filter (jig/filter)].

2.4 Quality Assurance

The quality assurance (QA) program consisted of the same routine audits performed for
CASTNET, if applicable, and testing/comparison of instruments unique to cloud water sampling.
QA procedures are documented in greater detail in the MADPro Quality Assurance Plan, which
is Appendix 10 to the CASTNET QAPP (AMEC, 2011).

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

3.0 Project Results

3.1 Liquid Water Content and Cloud Frequency

The cloud LWC is an important measurement for the determination of deposition of cloud water.
The LWC value also defines when the site is in cloud and is, therefore, integral in calculating the
cloud frequency at the site. Monthly cloud frequencies for the project were determined by
calculating the relative percent of all hourly LWC values equal to or greater than 0.05 g/m3, or:

100* (# of valid hourly LWC values > 0.05 g in ' j

C r =

where: n is the number of valid hourly LWC values per month and

CF is cloud frequency

Any month with less than 70 percent valid LWC data was not considered representative of the
monthly weather conditions for that month. Cloud frequencies varied substantially from month
to month, year to year, and from location to location. Figure 3-1 presents the mean monthly
project cloud frequency statistics from 1995 through 2011 and illustrates the wide range of cloud
frequency values from the project monthly minimum value of 12.9 percent in September 2005 to
the maximum value of 67.9 percent for June 2004.

Figure 3-1. Monthly Cloud Frequency Statistics (1995-2007, 2009-2011)

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

The project monthly mean, minimum, and maximum LWC values for the months of June
through September for 1994 through 2007 and 2009 through 2011 are shown in Figure 3-2.
Mean LWC was calculated by taking the average of all hourly LWC values equal to or greater
than 0.05 g/m3 during the month. Only valid values passing the 70 percent completeness
criterion were plotted. LWC values varied from a project minimum of 0.157 g/m3 in August
2007 to a project maximum of 0.418 g/m3 in September 2002.

Figure 3-2. Monthly Mean Liquid Water Content Statistics (1995-2007, 2009-2011)

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l-H

100 percent; or

• Either the anion sum or the cation sum was >100 |ieq/L, and the absolute value of the
RPD was > 25 percent.

The RPD was calculated from the following formula:

RPD = 200* (cations - anions|/(cations + anions)

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On occasion, samples exceeding these criteria were accepted and used for analyses. In most of
these cases, a low field pH value [high hydrogen (H ) concentration] caused the cation sum to be
larger, which in turn caused exceedance of the criteria.

Table 3-1. Number of Cloud Water Samples Accepted for Analyses

Total Number of

Number of Samples

Year

Samples

Accepted

Percent Accepted

1994*

1995a

142

136

1996a

122

105

I997*

334

324

1998a

341

269

I999*

174

100

2000b

104

102

2oor

2002c

2003c

100

2004c

100

2005c

2006c

100

2007c

100

2009c

2010c

201 lc

Total

1876

1717

92%

Note: a Hourly samples — sample collection bottle changed every hour.

b Hourly + daily samples (62 hourly and 42 24-hour samples in year 2000)
c Daily samples — sample collection bottle changed every 24 hours.

3.3 Cloud Water Chemistry

Seasonal mean concentrations of the major ions (S024, H , NH4, and NO,) are presented in
Figure 3-3 where a "season" is defined as the period June through September. The seasonal
concentrations of these major ions basically exhibit the same pattern of increases and decreases
with respect to each other with a few exceptions over the years. In general, after a period of
increase from 1995 to 2001, the major ion concentrations in cloud water have decreased except
for a 3-year period from 2005 through 2007 when all seasonal concentrations, except for
hydrogen, increased. There appears to be a rather precipitous decline in concentrations after
2007. However, the project did not operate in 2008, and the decrease in concentrations may not
have been as steep if data had been available for 2008. Nevertheless, the major ion
concentrations do not exhibit much of a trend since 1995. This lack of a discernible trend is
partially explained by the climatic and ecological factors unique to high-elevation ecosystems.

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

Figure 3-3. Mean Major Ion Concentrations of Cloud Water Samples (1995-2007, 2009-2011)

100

0 H 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

V##1

—~—Sulfate
—¦—Nitrate
—*— Ammo nium
—•—Hydrogen

600
550
500
450
400
350
300
250
200
150

Note: * Laboratory pH data instead of field pH data were used for calculating the 2001, 2006, 2007, 2009, 2010. and 2011 hydrogen
concentration values.

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

The seasonal mean concentrations of the minor ions of (Ca , Mg2+, Na+, K", and CI") are
presented in Figure 3-4. As with the major ions, there is no discernible trend in these
concentrations other than perhaps an upward trend in Ca concentrations after the project low
concentration of 27.07 |ieq/L in 2004.

Figure 3-4. Mean Minor Ion Concentrations of Cloud Water Samples (Cations and Chloride)
1995-2007, 2009-2011

100 n

60 -

40 -

20 ¦

x x x-

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

-Calcium
Magnesium
-Sodium
- Potassium
-Chloride

Seasonal mean cloud water
concentrations for SO7 and NOj
were compared to seasonal mean
precipitation concentrations for
SO • and NO,. The precipitation
concentration data were obtained
from the NADP/NTN site at
Elkmont, TN (TNI 1). Figures 3-5
and 3-6 present these
comparisons for SO and NO,,
respectively, from 1995 through
2011. Precipitation concentrations
do not show a discernible trend

but follow, with a few exceptions (in particular for S024), the same general pattern of increases
and decreases as the cloud water concentrations, especially since 2004.

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

Figure 3-5. Mean Seasonal Cloud Water versus Mean Seasonal Precipitation Sulfate
Concentrations, 1995-2011

Figure 3-6. Mean Seasonal Cloud Water versus Mean Seasonal Precipitation Nitrate
Concentrations, 1995-2011

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3.4 Cloud Water Deposition

Cloud water depositions were estimated by applying the CLOUD model (Lovett, 1984),
parameterized with site-specific cloud water chemistry, LWC, and wind speed data from
CLD303 for 1994 through 2007 and 2009 through 2011.These data were screened by AMEC and
provided to G.M. Lovett. The reports by Lovett, which discuss CLOUD and the CLOUD
deposition modeling results for individual years, were included as an appendix in each
corresponding MADPro annual report (e.g., AMEC, 2012). For a detailed description of the
CLOUD model and Lovett's procedures please see recent MADPro reports at
http://java.epa.gov/castnet/documents.do under "Cloud Deposition," and MADPro: Cloud
Deposition to the Appalachian Mountains, 1994-1999 (EPA, 2000).

Data sets from 1997, 1999 through 2007, and 2009 through 2011 were sufficiently complete to
estimate a seasonal value. A season is defined as June through September, and three of the four
months were required to calculate the seasonal deposition. Figure 3-7 presents the seasonal
deposition estimates as kilograms per hectare (kg/ha) for the major ions from 1999 through 2007
and from 2009 through 2011, and, unlike the cloud water concentrations (Figure 3-3), depicts an
overall decrease in seasonal deposition estimates. Because the ft deposition estimates are much
lower with respect to the other three ions, only H+ deposition estimates are plotted in Figure 3-8
to better illustrate the decrease in these values over the years.

Figure 3-7. Seasonal Deposition Estimates for Major Ions (1999-2007, 2009-2011)

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Figure 3-8. Seasonal Deposition Estimates for Hydrogen (1999-2007, 2009-2011)

The information in Figure 3-7 was also compared by averaging the data in 3-year increments from
1999 through 2001 and from 2009 through 2011 (Figure 3-9). The decreases in average S024, NOj,
NH4, and H+ deposition estimates were 77 percent (84.2 kg/ha versus 19.6 kg/ha), 74 percent
(48.8 kg/ha versus 12.6 kg/ha), 56 percent (13.7 kg/ha versus 6.0 kg/ha), and 92 percent (1.58 kg/ha
versus 0.13 kg/ha), respectively.

Figure 3-9. Mean 3-year Seasonal Deposition Estimates for Major Ions, 1999-2001
and 2009-2011

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Wet deposition data from 1995 through 2011 were obtained from the NADP/NTN site TNI 1 for
comparison to cloud water deposition estimates for 2000 through 2007 and 2009 through 2011.
Figures 3-10 and 3-11 show the seasonal SO2, and N03 deposition estimates, respectively, for
both cloud water and precipitation data. The cloud water deposition estimates are plotted against
the left y-axis, and the wet deposition values are plotted against the right y-axis. Starting in 2004,
cloud water and wet deposition follow a similar pattern with some exceptions.

Figure 3-10. Cloud Water and Wet Sulfate Deposition Estimates (June through September,
1995-2011)

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S-H

3
a

T3
jC>
O

—i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

J3 S" ^ ^ ^

14
12
10

-Cloud Water
Sulfate

Wet Sulfate

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

Figure 3-11. Cloud Water and Wet Nitrate Deposition Estimates (June through September,
1995-2011)

S-H

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- 6

- 5

- 4

off3 cpf° cP% cf? # ^ ^ ^ ^ ^ 0\s

VVVVV'V^'V^V'k'k'k'k'k'k'k'k'k

¦Cloud Water
Nitrate

-Wet Nitrate

3.5 Total Deposition

The total deposition components (dry, wet, and cloud) for sulfur (S) and nitrogen (N) are
presented in Figures 3-12 and 3-13 for 2000 through 2011. The dry deposition component was
estimated from the filter pack concentrations obtained from the GRS420 CASTNET site. For
detailed information on the derivation of these components please refer to previous MADPRO
reports (http://java.epa.gov/castnet/documents.do) and the CASTNET QAPP (AMEC, 2011).
The figures show that both sulfur and nitrogen total deposition fluxes have decreased since 2000
with the biggest reductions in cloud deposition.

Cloud water sulfur deposition decreased by 79 percent since 2000 while dry and wet sulfur
depositions decreased by 70 and 33 percent, respectively. Cloud water sulfur deposition
accounted for approximately 71 to 89 percent of the total sulfur deposition to CLD303 from
2000 through 2011.

Cloud water nitrogen deposition decreased by 63 percent since 2000, and dry nitrogen deposition
decreased by 48 percent. However, wet nitrogen deposition has not shown a discernible change
since 2000. Cloud water nitrogen deposition contributed approximately 69 to 90 percent to the
total nitrogen deposition from 2000 through 2011.

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Figure 3-12. Seasonal Sulfur Deposition (2000-2011)

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4.0 Conclusions

4.1 Cloud Water Concentrations and Deposition Estimates

The steady decline in dry sulfur and nitrogen species concentrations measured by filter pack
sampling at the lower elevation C ASTNET sites and in estimates of total (dry + wet) deposition in
the eastern United States have also been measured in cloud water sample concentrations and
depositions from CLD303 over the 10-year period from 2000 through 2009.

Similarly, emissions from TVA-operated power plants (Figures 4-1 and 4-2) also declined from
2000 through 2009. Emissions increased in 2010, and although emissions decreased in 2011,
they were higher than 2009 levels (TVA, 2012). Seasonal cloud water concentrations measured
in 2007 and 2009 mirrored these emission reductions, as well as the increase in 2010. However,
seasonal cloud water concentrations of both sulfate and nitrate increased again in 2011 when
emissions decreased. One possible reason for cloud water concentrations not always tracking
emissions trends may be the influence of cloud LWC and weather conditions, which can vary
substantially from one collection season to another (Figure 3-2) and affect the concentration of
pollutants within a cloud.

Figure 4-1. Seasonal Cloud Water S024 Concentrations and Depositions and TVA Annual
Sulfur Dioxide (SO,) Emissions (2000-2011)

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

Figure 4-2. Seasonal Cloud Water NOj Concentrations and Depositions and TVA Annual
Oxides of Nitrogen (N0X) Emissions (2000-2011)

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m qj
£

-fa

350
300
250
200
150
100
50
0

70.0

60.0 g

80.0

¦Nitrate Ion
Concentration

¦Oxides of
Nitrogen
Emissions

Nitrate Ion
Deposition

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Power plant emissions have been reduced significantly in nearby states, as shown in Table 4-1
(EPA, in press), and, depending on weather patterns, have also had an impact on cloud water
concentrations at CLD303.

Table 4-1. Power Plant Emission Reductions (percent) from 2000 through 2011 for Tennessee
and Nearby States

so2

NOx

Kentucky

Virginia

Tennessee

North Carolina

South Carolina

Georgia

Alabama

Source: EPA (in press)

In general, cloud water sulfur and nitrogen depositions correspond closely with TVA emissions,
as well as emissions from power plants from neighboring states. Cloud water depositions are also
affected by cloud LWC and its frequency, local wind speeds, and other meteorological
conditions. Deposition rates can, therefore, exhibit an opposite trend relative to concentrations
and emissions. Since cloud water is the major contributor to total deposition at high elevation
sites such as CLD303, and because cloud water deposition can be significantly influenced by
cloud LWC, complex terrain, local wind speeds etc., the sensitive high-elevation ecosystems of

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

the Great Smoky Mountains and other similar locations can continue to experience damage from
acidification because of poorly buffered soils and other ecological factors well after sulfur and
nitrogen emissions decrease.

The cloud water concentration and deposition data compiled from this study show that both
concentrations and depositions have declined since 2000. The decline in concentrations is more
variable from year to year than the decline in depositions. Deposition estimates correspond
relatively well with emission reductions at TVA power plants and from power plants in
neighboring states. The data show that high-elevation ecosystems are subject to different stresses
than lower elevation areas as shown by the much greater deposition of sulfur and nitrogen
species from cloud water at CLD303 compared to the lower elevation CASTNET sites. Lower
elevation sites experience deposition only in the forms of dry and wet deposition.

4.2 Future Studies

The MADPRO project was instrumental in demonstrating that sensitive high-elevation
ecosystems can continue to experience damage from acidification well after emission reductions
have occurred. Since all the complex factors that determine deposition rates to these types of
ecosystems are not completely understood, it is recommended that similar studies be initiated in
the near future. One of the biggest obstacles to conducting this type of research is that study sites
are often remote, difficult to access, and have no ready source of power. The CLD303 site was
battery operated using solar panels with access to a generator when needed. However, generator
power had to be manually initiated and, as a result, was not always available. The cloud collection
system would shut down if the site experienced a several day duration cloud event and manpower
was not available to turn on the generator.

Recommendations for future projects include having a reliable source of power for operations as
well as dedicated, physically capable, technically competent, and readily available site operators
for troubleshooting, maintenance, and laboratory activities. Being a site operator for a cloud
collection site is a very demanding job, and without the appropriate personnel, collection of
meaningful data can be compromised. Due to the logistics and instrumentation involved in cloud
water sampling, this type of research is more complicated and, therefore, more expensive with
respect to filter pack or precipitation sampling. Sponsorship with ample funding is highly
recommended for successful operation of cloud water sampling efforts.

AMEC Environment & Infrastructure, Inc.

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Cloud Deposition Monitoring — Clingmans Dome, IN — Great Smoky Mountains National Park — Summary Report

AMEC Environment & Infrastructure, Inc.

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Cloud Deposition Monitoring — Clingmans Dome, TN — Great Smoky Mountains National Park — Summary Report

5.0 References

AMEC Environment & Infrastructure, Inc. (AMEC). 2012. Cloud Deposition Monitoring,
Clingmans Dome, TN, Great Smoky Mountains National Park -2011. Prepared for
the U.S. Environmental Protection Agency (EPA), Office of Air and Radiation, Clean Air
Markets Division, Washington, DC. Contract No. EP-W-09-028. Gainesville, FL.

AMEC Environment & Infrastructure, Inc. (AMEC)*. 2011. Clean Air Status and Trends

Network (CASTNET) Quality Assurance Project Plan Revision 7.0. Prepared for the U.S.
Environmental Protection Agency (EPA), Office of Air and Radiation, Clean Air Markets
Division, Washington, DC. Contract No. EP-W-09-028. Gainesville, FL.

Anlauf, K.G., Wiebe, H.A., and Fellin, P. 1986. Characterization of Several Integrative Sampling
Methods for Nitric Acid, Sulfur Dioxide, and Atmospheric Particles. JAPCA,

36:715-723.

Baumgardner, R.E., Kronmiller, K.G., Anderson, J.B., Bowser, J. J., and Edgerton, E.S. 1997.
Development of an Automated Cloud Water Collection System for Use in Atmospheric
Monitoring Networks. Atmospheric Environment, 31(13):2003-2010.

Gerber, H. 1984. Liquid Water Content of Fogs and Hazes from Visible Light Scattering
Journal of Climatology and Applied Meteorology, 23:1247-1252.

Lavery, T.F., Rogers, C.M., Baumgardner, R., and Mishoe, K.P. 2007. Intercomparison of

CASTNET NOj and HN03 Measurements with Data from Other Monitoring Programs.
Journal of Air & Waste Management Association (JAWMA).

Lovett, G.M. 1984. Rates and Mechanisms of Cloud Water Deposition to a Subalpine Balsam Fir
Forest. Atmospheric Environment. 18:361-371.

Tennessee Valley Authority (TVA). 2012. Air Quality.

http://www.tva.com/environment/air/index.htm. Accessed October 2012.

U.S. Environmental Protection Agency (EPA). In press. Clean Air Interstate Ride, Acid Rain
Program, and Former NOx Budget Trading Program 2011 Progress Report.
http://www.epa.gov/airmarkets/progress/progress-reports.html.

U.S. Environmental Protection Agency (EPA). 2000. Mountain Acid Deposition Program

(MADPro): Cloud Deposition to the Appalachian Mountains, 1994 1999. EPA/600/R-
01/016.

* Formerly known as MACTEC Engineering and Consulting, Inc.

AMEC Environment & Infrastructure, Inc.

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