I
Clean Air Status and Trends Network
(CASTNET)
i
2006 Annual Report
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Clean Air Status and Trends Network
(CASTNET)
2006 Annual Report
Prepared by:
MACTEC Engineering and Consulting, Inc.
Prepared for:
U.S. Environmental Protection Agency
Office of Air and Radiation
Clean Air Markets Division
Washington, D.C.
November 2007
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Table of Contents
Executive Summary ii
Chapter 1 CASTNET Overview 1
Background 1
Partnerships 2
Twenty Years of Network Monitoring 4
NFS Air Monitoring Program 5
Locations of Monitoring Sites 6
CASTNET Monitoring at Long Term Ecological Research Sites 7
Measurements Collected at CASTNET Sites 9
Calculating Dry Deposition 10
CASTNET Reference Sites 11
SO2 and NOX Emissions 12
Significant Events during 2006 14
Chapter 2 Atmospheric Concentrations 15
Sulfur Dioxide 15
Particulate Sulfate 17
Total Nitrate 19
Air Quality Concerns in the Four Corners Region 21
Particulate Ammonium 22
Chapter 3 Atmospheric Deposition 24
Sulfur Deposition 25
Uncertainties in Estimates of Dry Nitrogen Deposition 28
Nitrogen Deposition 30
Chapter 4 Ozone Concentrations 33
National Ambient Air Quality Standard for Ozone 35
Elevated Ozone Concentrations in Atlanta during 2006 39
Chapter 5 Data Quality 41
Precision 42
Accuracy 47
Completeness 49
Laboratory Intercomparison Studies 50
Conclusion 51
References R-l
Appendix A Locational and Operational Characteristics of CASTNET Sites A-l
Appendix B Acronyms and Abbreviations B-l
CASTNET Annual Report - 2006
Table of Contents
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Executive Summary
This report summarizes Clean Air Status and Trends Network (CASTNET) data collected during
2006 and examines trends in air quality and deposition on regional and national scales.
CASTNET began operation in 1991 with the incorporation of the National Dry Deposition
Network (NDDN), which had been in existence since 1987. CASTNET measures rural,
regionally representative concentrations of sulfur and nitrogen species and ozone in order to
evaluate the effectiveness of national and regional air pollution control programs.
' :% '
* Mean annual sulfur dioxide and particulate sulfate concentrations have declined
significantly over the 17-year period 1990 through 2006. Sulfur dioxide levels have
declined 37 percent while sulfate concentrations have declined 25 percent.
* Total sulfur deposition has declined by 28 percent from 1990 to 2006.
* Mean annual concentrations of total nitrate (nitric acid plus particulate nitrate) have
declined by approximately 18 percent over the 17-year period.
* Total nitrogen deposition has declined by 12 percent from 1990 to 2006.
* Ozone levels measured in 2006 continue to show a downward trend that began after a
peak in 2002. The median fourth highest daily maximum 8-hour ozone concentration for
2006 (72 ppb) was the second lowest in the history of the network. For the most recent 3-
year period (2004-2006), only two eastern and four California sites recorded exceedances
of the 8-hour standard. This 3-year period is notable as it had the fewest exceedances (six
total) in the history of the network. The recent decline in rural ozone and nitrate levels
has been attributed to the documented decline in nitrogen oxides emissions as well as
changes in weather conditions.
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Chapter 1: CABINET Overview
CASTNET is a national air monitoring network that provides data for determining
relationships between emissions, air quality,
deposition, and ecological effects.
Santee Sioux, NE (SAN189)
Background
The United States Environmental Protection Agency (EPA) established the Clean Air Status and
Trends Network (CASTNET) to provide data for determining relationships between changes in
emissions and any subsequent changes in air quality, atmospheric deposition, and ecological
effects. The rural monitoring network was mandated by the 1990 Clean Air Act Amendments
(CAAA) to assess the effectiveness of requirements promulgated to reduce emissions of sulfur
dioxide (SO2) and nitrogen oxides (NOX) as Congress recognized the need to track real-world
environmental results as the Acid Rain Program was implemented.
Under the CAAA, the Acid Rain Program has produced significant reductions in SO2 and NOX
emissions from electric generating plants since 1995. More recent NOX emission control
programs also produced substantive declines in NOX emissions in the eastern United States.
These programs include the Ozone Transport Commission (OTC) NOX Budget, NOX State
Implementation Plan (SIP) Call, and NOX Budget Trading Program. EPA relies on CASTNET
and other long-term monitoring networks to generate the data and information used to assess the
effectiveness of these emission control programs under several different mandates including the
Government Performance and Results Act, The National Acid Precipitation Assessment Program
(NAPAP), Title IX of the CAAA, and the United States - Canada Air Quality Agreement. This
report summarizes CASTNET monitoring activities and the resulting concentration and
deposition data collected over the 17-year period from 1990 through 2006.
CASTNET Annual Report - 2006
Chapter 1: CASTNET Overview
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Additional information, previous annual reports, and other CASTNET documents can be found
on the EPA Web site, http://www.epa.gov/castnet. The CASTNET database is also available to
the public by accessing the "Data" link on EPA's CASTNET Web page. The Web site provides
archives of the concentration and deposition data. Fully validated data are available
approximately 10 months following collection.
CASTNET is sponsored by EPA and the National Park Service (NPS). NPS began its
participation in CASTNET in 1994 under an agreement with EPA. NPS is responsible for the
protection and enhancement of air quality and related values in national parks and wilderness
areas. The CASTNET sites sponsored by NPS as of December 2006 numbered 27. In addition to
EPA and NPS, the principal sponsors, CASTNET operates in partnership with other rural long-
term monitoring networks:
* (NADP/NTN)
operates monitoring stations with wet deposition samplers to measure the concentrations
and deposition rates of air pollutants removed from the atmosphere by precipitation.
NADP/NTN operates wet deposition samplers at or near virtually every CASTNET site.
* Air (CAPMoN) operates 28
measurement sites throughout Canada and one in the United States. CASTNET and
CAPMoN both operate samplers at monitoring stations in Ontario, Canada and at
Pennsylvania State University.
* of (IMPROVE) measures
aerosol pollutants near more than 30 CASTNET sites. IMPROVE measures particulate
air pollutants that affect visibility and visual air quality.
* is a Web site designed to allow the public to view air quality data for a specific
area in real-time. Ten CASTNET sites send 1-hour ozone data to the AIRNow database.
The data have not gone through the full quality assurance process and, therefore, should
not be used for publication or regulation.
Although EPA and NPS are the primary sponsors of CASTNET, other organizations, tribes,
universities, and government agencies play a role in sponsoring individual CASTNET sites.
These groups, or co-sponsors, provide an in-kind service that supports the operation of a site.
The types of assistance offered may include site operation, land use, or both. Table 1-1 lists all
current co-sponsors for the network. All of the sites added during the recent expansion of the
network (since 2001) have an associated co-sponsor. Some of the co-sponsors listed in Table 1-1
have maintained long-term relationships with CASTNET sites. For example, Pennsylvania State
University, co-sponsor of PSU106, PA, and the University of Michigan, co-sponsor of ANA115,
MI, have been involved with the network since the late 1980s.
CASTNET Report - 2 Chapter 1: CASTNET Overview
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Three CASTNET monitoring sites are
located on tribal lands (Figure 1-1) as a
result of a unique cooperative effort among
EPA Headquarters, EPA Regions, tribal
governments, and the Inter-Tribal
Environmental Council (ITEC). This
collaborative effort has resulted in
monitoring sites operating on the tribal
lands of the Cherokee Nation in eastern
Oklahoma (CHE 185), the Alabama-
Coushatta in eastern Texas (ALC188), and
the Santee Sioux in northern Nebraska
(SAN189). State agencies also operate
special purpose air pollutant measurement
devices at some CASTNET sites.
Figure 1-1 Native American Participation in
CASTNET Operations
Santee Sioux Tribe
Nebraska
Kansas
Cherokee Nation
4,
Oklahoma
Texas
Alabama-Coushatta Tribe
Table 1-1 Co-Sponsors for CASTNET
Site
Co-sponsor
ALC188, TX
ANA115, MI
CAD150, AR
CHE185, OK
CON186, CA
EGB181/
EGB281, ON
EVE419, FL
HWF187,NY
IRL141,FL
KNZ184, KS
PND165, WY
PSU106, PA
SAN189,NE
SND152, AL
Alabama-Coushatta Tribe of Texas
University of Michigan
United States Army
Cherokee Nation
U.S. Department of Agriculture-Forest Service Pacific Southwest
Research Laboratory
Environment Canada
Environmental Protection Agency
State University of New York
St. Johns River Water Management District
Konza Prairie Long Term Ecological Research Program
U. S. Department of Interior-Bureau of Land Management
Pennsylvania State University
Santee Sioux Tribe of Nebraska
Tennessee Valley Authority
CASTNET Annual Report - 2006
Chapter 1: CASTNET Overview
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PSU106, PA
Twenty Years of Network Monitoring
CASTNET was designed primarily to measure seasonal and annual
average concentrations and depositions over many years.
Consequently, measurements of weekly average concentrations were
selected as the basic sampling strategy. An open-face, three-stage
filter pack was employed to measure gaseous and particulate sulfur
and nitrogen pollutants as well as concentrations of other pollutant
species. The filter pack technology and sampling protocol have been
used consistently over the 20 years, providing a comparable data set
each year and allowing for the analysis of long-term trends. Any
future sampling methods will be examined with respect to
comparability with the filter pack so the information obtained will
continue to be available for long-term trends in pollutant species.
As of December 2006, the network
included 87 monitoring stations at
84 site locations throughout the
continental United States, Alaska,
and Canada. CASTNET sites
measure rural, regionally
representative concentrations of
sulfur and nitrogen species and
ozone in order to detect and
quantify trends, define the spatial
distribution of rural pollutants, and
estimate dry deposition fluxes. The
goal of estimating dry deposition
also requires the measurement of
several meteorological parameters
and information on vegetation and
land use.
20-Year Trend in SO2 Concentrations (ng/m3)
atPSU106,PA
1 (J
16 -
12-
10-
6 -
4 -
2 -
n
[
1
i
n -ซJ
CH Annual Mean SO2 Cone
-- 3-Year Mean SO2 Cone
r
r
n
r
~\
r
cncncn
^r in CD r- co en g
0) 0) 0) 0) 0) 0) O
o o o
o o o o o o o
Note: Annual mean SO2 concentrations have declined by 39 percent
at PSU106, PA over the 20 years.
CASTNET has its origins with the National Dry Deposition Network (NDDN), which
was established in 1986 and began operation in 1987. Many of the original NDDN sites
are still operational after 20 years and provide useful information on trends in air quality.
The site at Pennsylvania State University, PA (PSU106) began collecting samples in
January 1987 and is the longest running site.
CASTNET Annual Report - 2006
Chapter 1: CASTNET Overview
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NPS Air Monitoring Program
The NPS Air Resources Division administers an extensive air monitoring program that measures
air pollution levels in national parks. The purpose of the program is to establish current air
quality conditions and assess long-term trends of air pollutants that affect park resources. These
data are also used to determine compliance with the National Ambient Air Quality Standards
(NAAQS) and to assess the effectiveness of national and regional air pollution control programs.
Measuring air pollution levels in parks is an essential part of the NPS air resource management
program that provides vital information to Congress, air pollution control agencies, academia,
and the public (NPS, 2007).
The NPS air monitoring program consists of an extensive network of air monitoring stations in
almost 70 national parks across the country. Twenty-seven of these sites are also CASTNET
sites. Several NPS sites have been in operation for over 20 years. The program has three primary
components: visibility (IMPROVE), gaseous pollutants (mainly ozone), and atmospheric
deposition (wet - NADP/NTN, NADP/MDN and dry - CASTNET). Meteorological monitoring
is also conducted at most locations to aid in the interpretation of measured air pollution levels. In
addition to long-term monitoring, NPS is involved in many special studies that tend to be short-
term and more intensive in nature. These studies are often initiated to explore specific local and
regional research topics, such as identifying sources of air pollution or assessing the potential
risk to natural resources in parks (NPS, 2007).
Assessing how air quality is changing is a prime function of the NPS air monitoring program.
Monitoring data on visibility, ozone, and atmospheric deposition show that air pollution is
affecting some park resources nationwide. Consistent with the Government Performance and
Results Act, NPS has established the air quality goal of stable or improved air quality in 70
percent of reporting park areas by September 30, 2008. An area meets the goal if it does not
show statistically significant deterioration in any of the performance indicators (NPS, 2007).
Additional information on the NPS Air Monitoring program can be found on the Web site:
http://www2.nature.nps.gov/air/monitoring/.
CASTNET Annual Report - 2006
Chapter 1: CASTNET Overview
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Locations of Monitoring Sites
Figure 1-2 shows the locations of CASTNET monitoring sites as of December 2006. Eighty-
seven sites were operational at 84 distinct locations. Most CASTNET sites are located in rural or
remote locations away from pollutant emission sources and heavily populated areas. Appendix A
provides the location and operational characteristics of each site by state including information
on start date, latitude, longitude, elevation, and the types of measurements taken at each site. For
the purposes of this report, CASTNET sites are called "western" or "eastern" depending on
whether they are west or east of 100 degrees west longitude. In general, sample flow rates are set
to 1.5 liters per minute (1pm) in the east and at a higher rate of 3.0 1pm in the west due to lower
pollutant concentrations in the western United States.
Figure 1-2 CASTNET Sites as of December 2006
PRKtM EGBI81,
BHOX148 ^
SANm *
ASH! 35
HOW 132
EGB281
SW.133 .
LYK123
QAKI72
BVL1WB OXF122 .
ALHI57 WJ140 COR1t9
CKT136
MCKI31.MCK231 -
MAC4277* spm)t
cozm
CHE1B5 ESP127"
CADI 50
m. ,-~
GRS420, CND125 BFT142
COW137
* Collocated Pair
EPA Sponsored
NPS Sponsored
1000'0'W
CASTNET Annual Report - 2006
Chapter 1: CASTNET Overview
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CASTNET Monitoring at Long Term Ecological Research Sites
The National Science Foundation's (NSF) Long Term Ecological Research (LTER) Program
was established in 1980 to support research on long-term ecological phenomena across a wide
range of geographical scales. The network consists of 26 field sites representing diverse
ecosystems in continental North America, the Caribbean, the Pacific, and Antarctica. The sites
represent most of the Earth's major ecosystems and include forests, grasslands, deserts, urban
areas, tundra, agricultural systems, freshwater lakes, coastal estuaries and salt marshes, coral
reefs, and coastal ocean zones. Disturbances often shape ecosystems by periodically reorganizing
or destroying them, providing opportunities for significant changes in
plant and animal populations and communities. Disturbances include,
for example, hurricanes, land use changes, changes in climate and
atmospheric chemistry, or forest harvesting (NSF, 2005).
Three CASTNET monitoring systems are located on LTER field sites.
CASTNET provided early support to LTER by establishing sites at
Coweeta, NC (COW 137) in 1987 and Hubbard Brook, NH (WST109)
in 1988. The third LTER CASTNET site was established at Konza
Prairie, KS (KNZ184) in 2002. CASTNET monitors are also located
near other LTER sites, e.g., Florida Coastal Everglades, Baltimore
Ecosystem Study, Niwot Ridge in Colorado, and North Temperate
Lakes in Wisconsin.
The Coweeta LTER research program centers on
the effects of disturbances and environmental
gradients on biogeochemical cycling and the
underlying watershed ecosystem processes that
regulate and respond to those cycles. It now
represents one of the longest continuous
environmental studies in North America
(LTER, 2004a). This LTER research project is a
continuing long-term study concentrating on
recovery from phenomena that are of major
consequence in the southern Appalachians, such as
drought, weather (Figure 1-3), and altered
atmospheric deposition.
Figure 1-3 Annual Mean Temperature
(ฐC) and Precipitation (mm) Data for
COW 13 7, NC
15 T r 250
14
12
I 11
10
g
200
Temperature
- Precipitation
150 =
3
100
50
The Hubbard Brook Experimental Forest was established by the U.S. Department of Agriculture
Forest Service, Northeastern Research Station in 1955 as a major center for hydrologic research
in New England. In 1963, the Hubbard Brook Ecosystem Study was initiated in order to use the
small watershed approach at Hubbard Brook to study linkages between hydrologic processes and
nutrient flux and cycling in response to natural and human disturbances such as air pollution,
CASTNET Annual Report - 2006
Chapter 1: CASTNET Overview
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forest cutting, land-use changes, increases in insect populations, and climatic factors
(LTER, 2004b).
The Konza Prairie Biological Station was founded in 1971. The
Konza Prairie LTER Program is a comprehensive,
interdisciplinary research program designed to provide an
understanding of ecological processes in mesic grasslands,
particularly tallgrass prairie, and to contribute to conceptual and
theoretical advances in the field of ecology (LTER, 2004c). Some
current areas of research include grassland ecology and the
effects of fire, grazing, and climatic variability on the structure
and function of mesic grass-land ecosystems.
CASTNET supports the three LTER sites by providing information
on air pollutant concentrations, dry deposition fluxes of pollutants
to the ecosystems, and meteorological conditions. These data
contribute to an assessment of disturbances related to air pollution,
atmospheric deposition, and climate change.
KNZ184, KS
LONG TERM ECOLOGICAL RESEARCH NETWORK
LTER Network Office
1 University of New Mexico,
UNM Biology Department, MSC03-2020
Albuquerque, NM 87131-0001
Ph 505.277.2597 Fax 505.277.2541
Email Office@lternet.edu Web www.lternet.edu
CASTNET Annual Report - 2006
Chapter 1: CASTNET Overview
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Measurements Collected at CASTNET Sites
CASTNET was designed primarily to measure trends in
seasonal and annual average concentrations and
depositions over many years. Consequently,
measurement of weekly average concentrations was
selected as the basic sampling strategy. Over the course
of the week, air is drawn at a controlled flow rate
through a three-stage filter pack (Figure 1-4) mounted
atop a 10 meter tower to collect air pollutants in the
form of gases and particles. The first stage of the filter
pack encloses a Teflonฎ filter, the second a nylon filter,
and the third holds two potassium carbonate (K2CO3)-
impregnated cellulose filters. The filter pack is changed
out each Tuesday and shipped to the analytical
chemistry laboratory for analysis.
Figure 1-4 Three-Stage Filter Pack
CASTNET Ambient
Measurements
Sulfur dioxide (SO2)
Particulate sulfate (SO2;)
Paniculate nitrate (NO,)
Nitric acid (HNO3)
Particulate ammonium (Nit,)
Paniculate calcium (Ca2+)
Paniculate sodium (Na+)
Paniculate magnesium (Mg2+)
Paniculate potassium (K+)
Paniculate chloride (Cl")
Ozone (O3)
Meteorological variables and
information on land use and
vegetation
Cellulose (2)
Gaseous
SO2
Nylon
Gaseous
HNO3 SO2
Teflonฎ
Particulate
so2; NO3 NH; K+
Ca2+ Mg2+ Na+ Cl"
Quick Disconnect
Cellulose Nylon Teflonฎ
Filters Filter Filter
Shipping Cap
Jremoved during sampling)
Teflonฎ Spacers
CASTNET Annual Report - 2006
Chapter 1: CASTNET Overview
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CASTNET measures concentrations of sulfur in the form of sulfur dioxide (SO2) and sulfate
(SO2;) and nitrogen as nitrate (NO3), nitric acid (HNO3), and ammonium (NH+4). In addition, it
measures concentrations of chloride (Cl"), calcium (Ca2+), sodium (Na+), magnesium (Mg2+), and
potassium (K+). Sulfate, NEt,, NO3, Cl", and the earth metals are collected on the Teflonฎ filter.
The nylon filter collects HNO3and some SO2. The cellulose filters collect the remaining SO2.
CASTNET also measures ozone, one of the major components of smog. In addition to the air
pollutants, CASTNET sites record meteorological measurements of temperature, solar radiation,
relative humidity, precipitation, wind speed and direction, standard deviation of wind direction
(sigma theta), and surface wetness. These meteorological measurements are used to gauge the
transport of air pollutants and as input to the Multi-Layer Model (MLM), a mathematical model
used for estimating dry deposition to ecosystems in the atmospheric boundary layer. The ozone
and meteorological measurements are recorded continuously and archived as hourly averages.
Calculating Dry Deposition
Dry deposition processes are modeled as resistances to deposition. The original network design
was based on the assumption that dry deposition or flux could be estimated as the linear product
of measured pollutant concentration (C) and modeled deposition velocity (Vd). Measured
atmospheric concentrations are calculated based on the mass of each analyte in each filter extract
and the volume of air sampled. The rate of deposition of a pollutant, also known as deposition
velocity, is influenced by meteorological conditions, vegetation, and atmospheric and plant
chemistry. The deposition velocity values are calculated for each hour of each year using the
MLM. The MLM was described by Meyers et al. (1998) and Finkelstein et al. (2000). The data
used in the MLM to estimate dry deposition are derived from meteorological measurements and
pollutant concentrations taken at the site together with an estimation of the vegetation leaf-out
and leaf area index (LAI).
The schematic of the MLM in Figure 1-5 shows the relationships among the various resistances
and illustrates the meteorological and other data that are required as model input. An improved
version of the MLM (Schwede, 2006) was delivered by EPA's Office of Research and
Development (ORD) to MACTEC during 2006. This version includes changes to the soil
moisture factor, which affects the stomatal and soil resistances, and to the radiation algorithm,
which also affects the stomatal resistance. All deposition velocities and fluxes for the entire
network were recalculated using the updated model.
CASTNET Annual Report - 2006
Chapter 1: CASTNET Overview
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Figure 1-5 Multi-Layer Model
Flux = CxV
l/Vd =
1
1
1
+ r
' a
1 a, soil
r-\- If Tf-|-Tf Tf -\~ V
s ' b ' cut ' b I a,soil ' soi
= turbulence
= turbulence near soil
= thin layer at surface
rcut = cuticular
rs = stomatal
r-, = soil
'cut
F*
a, soil
Wetaess>
Precip
CASTNET Reference Sites
Chapters 2 through 4 present maps illustrating the
magnitude of pollutant concentrations and
deposition fluxes across the United States. In
addition, measurements from 34 CASTNET
reference sites (Figure 1-6) were analyzed for
each pollutant in order to determine trends in
concentrations and trends in rates of dry, wet, and
total deposition. These 34 sites have been
reporting CASTNET measurements since at least
1990 and are used for determining long-term
trends. The reference sites were selected using
criteria similar to those used by EPA in its
National Air Quality and Emissions Trends
Report (2000). The criteria include site longevity
and data completeness. EPA's procedures to
interpolate and extrapolate quarterly mean data
were also used. In chapters 2 through 4, the data
from the 34 reference sites were aggregated and
then presented using box plots for the period
1990 through 2006.
Figure 1-6 CASTNET Reference Sites
Reference Sites
CASTNET Annual Report - 2006
11
Chapter 1: CASTNET Overview
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The Acid Rain Program (ARP), established under Title IV of the 1990 Clean Air Act
Amendments, requires major reductions of sulfur dioxide (SO2) and nitrogen oxides (NOX)
emissions from the electric power industry. Under the Acid Rain Program, SO2 reductions are
achieved using a cap and trade program that sets a permanent cap on the total amount of SO2 that
may be emitted by all regulated electric generating units in the contiguous United States. The
program began in 1995 and is being phased in with the final 2010 SO2 cap set at 8.95 million
tons, a level equal to about one-half of the emissions from the power sector in 1980.
Using a market-based cap and trade mechanism to reduce SO2 emissions allows flexibility for
individual combustion units to select their own methods of compliance. Currently, one allowance
provides a regulated unit limited authorization to emit one ton of SO2. The Clean Air Act
Amendments of 1990 allocate allowances to regulated units based on historic fuel consumption
and specific emission rates prior to the start of the program. The total allowances allocated for
each year equal the SO2 emission cap. The program encourages early reductions by allowing
sources to bank unused allowances in one year and use them in a later year.
The ARP uses a more traditional approach to achieve NOX emission reductions. Rate-based
limits apply to most of the coal-fired electric utility boilers subject to the ARP. No nationwide
cap has been placed on NOX emissions. Other NOX emission control programs have resulted in
significant reductions in NOX emissions during the ozone season (see Chapter 4). Two prominent
control programs are the Ozone Transport Commission NOX Budget (1999-2002) and the NOX
State Implementation Plan Call, which began in 2003 and will continue through 2007.
The ARP is comprised of two phases for the reduction of SO2 and NOX. Phase I applied primarily
to the largest coal-fired electric generation sources from 1995 through 1999 for SO2 and from
1996 through 1999 for NOX. Phase II for both pollutants began in 2000. In 2005, the SO2 Phase II
requirements affected 3,391 operating units; the Phase IINOX requirements applied to 989 of
those operating units that exceed 25 megawatts and burned coal between 1990 and 1995
(EPA, 2005a).
The recently promulgated Clean Air Interstate Rule (CAIR) (EPA, 2007b) will establish regional
caps on SO2 and NOX emissions for affected generating units. Annual SO2 emissions will be
capped at 3.7 million tons in 2010 and NOX emissions will be capped at 1.5 million tons in 2009.
CASTNET will be used to assess baseline and program milestones.
Figure 1-7 presents state-by-state total annual SO2 emissions for Phase I and Phase II electric
utility plants for four years (1990, 1995, 2000, and 2006). The heaviest emissions occurred in the
eastern United States with major SO2 sources centered around the Ohio River Valley. The most
significant reduction in SO2 emissions occurred in 1995 when the ARP began. Many of the states
with the highest SO2 emissions realized the largest reductions in emissions. For example, Ohio
12
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emitted 2,212 tons in 2000. This total dropped to 962 tons in 2006, a 57 percent reduction.
Annual NOX emissions by state are depicted in Figure 1-8 for the same four years. States with the
higher NOX emissions also produced significant declines.
Figure 1-7 Annual Utility SO2 Emissions (Phase I and Phase II Plants only)
Annual Emissions of Sulfur Dioxide
(thousand short tons)
n 2,300
1990
D 1995
D2000
D2006
Figure 1-8 Annual Utility NOX Emissions (Phase I and Phase II Plants only)
Annual Emissions of Nitrogen Oxides
(thousand short tons)
n 540
1990
D 1995
D2000
D2006
CASTNET Annual Report - 2006
13
Chapter 1: CASTNET Overview
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Significant Events during 2006
January
Element DataSystem replaced Chemical Laboratory Analysis and Scheduling System
(CLASS ) as the laboratory information management system used for CASTNET.
March
EPA approved the CASTNET Quality Assurance Project Plan (QAPP), Revision 3.0 on
March 6.
EPA and the Tennessee Valley Authority began operating collocated ozone monitors at the
EPA-sponsored CASTNET site Cadiz, KY (CDZ171).
A field study began at three CASTNET sites to determine the size and distribution of
particulate nitrate collected by the CASTNET open-face filter pack sampling system.
A new EPA-sponsored site, Santee Sioux, NE (SAN189), began collecting samples on
July 5. The site is operated in cooperation with the Santee Sioux Tribe, part of the
Great Sioux Nation.
Use of a routine laboratory control sample (LCS) with all analyses was implemented as an
additional quality assurance/quality control mechanism to monitor for potential sample
handling artifacts and possible analyte loss between extractions.
The annual "floor-to-ceiling" audit of CASTNET property was conducted by EPA and the
Defense Contract Management Agency at MACTEC's Gainesville, FL location. The
property management system was approved by the audit.
MACTEC conducted a two-day site operator refresher training course for 10 site
operators^ackup operators from seven sites. The training session took place in
Somerset, PA and at the nearby CASTNET site Laurel Hill State Park, PA (LRL1 17).
_^^l
New Thermo Fisher Scientific Model 49i ozone analyzers were purchased for replacement
of the older analyzers.
Field calibrations began utilizing portable relative humidity chambers instead of aqueous
saturated salts to verify the accuracy of the relative humidity sensors.
Statistical analyses were completed to support acceptance testing of the nylon filters.
October
Sponsorship of the CASTNET site at Indian River Lagoon, FL (IRL141) passed from the
St. Johns River Water Management District to EPA.
The draft of the CASTNET QAPP, Revision 4.0 was submitted to EPA.
November
Version 2.5 of the Multi-Layer Model (MLM) was received from EPA.
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Chapter 2:
Atmospheric Concentrations
Georgia Station, GA (GAS153)
Three-stage filter packs are used to measure concentrations of sulfur dioxide (SO2), sulfate
(SO24"), nitric acid (HNO3), nitrate (NO3), ammonium (NH!,), chloride (Cl"), and several
earth metals. Since 1990, measured concentrations of sulfur species have decreased
significantly. Concentrations of nitrogen species remained relatively steady from 1990 until
2000 when they began to show a slight decline. Trends in mean annual SO2, SO24", total
nitrate, and NH^, concentrations are discussed in this chapter.
The geographic distribution and magnitude of annual mean concentrations across the United
States are presented for sulfur dioxide (SO2), sulfate (SO24"), total nitrate (HNO3 + NO3), and
ammonium (NFT4) concentrations. A map is provided for each pollutant. Maps of other filter
pack measurements are provided in CASTNET quarterly reports (MACTEC, 2006b; 2006d;
2007a; 2007c). The concentration shading in the figures in this chapter was prepared using an
algorithm based on inverse distance cubed weighting with a radius of influence of 500 kilometers
(km). In addition, trends in concentration data from the 34 CASTNET reference sites
(Figure 1-6) are presented using box plots for each year of the 17-year period from 1990
through 2006.
Sulfur Dioxide
Figure 2-1 presents annual mean sulfur dioxide (SO2) concentrations for 2006. The map shows a
large region in the eastern United States with concentrations greater than or equal to
5.0 micrograms per cubic meter (|j,g/m3). The region extends from western Kentucky
northeastward along the Ohio River Valley to Pennsylvania and to New Jersey, Maryland, and
Virginia. The Ohio River Valley is the major SO2 emission source region (see Figure 1-7) in the
United States. A concentration of 5.5 |J,g/m3 was observed at Georgia Station, GA (GAS 153).
Two sites in West Virginia - Parsons (PAR107) and Cedar Creek State Park (CDR119) -
recorded concentrations slightly less than 5.0 ng/m3. The single highest SO2 concentration
(13.1 |J,g/m3) was measured in eastern Ohio at Quaker City (QAK172). Only two western sites
(i.e., sites west of 100 degrees west longitude) measured an annual mean SO2 concentration
greater than 1.0 ng/m3. These sites were Theodore Roosevelt National Park, ND (THR422) and
Petrified Forest National Park, AZ (PET427).
CASTNET Annual Report - 2006 15 Chapter 2: Atmospheric Concentrations
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Figure 2-2 provides box plots that show the 1990-2006 trend in annual mean SO2 concentrations
aggregated over the 34 reference sites. The diagram shows a significant downward trend with
small interannual changes. Three-year means for 1990-1992 and 2004-2006 were 9.0 |J,g/m3 and
5.6 ng/m3, respectively. This change demonstrates a significant reduction of 37 percent in 3-year
mean SO2 concentrations for the two time periods. Annual mean SO2 concentrations measured in
2006 were the lowest measured by CASTNET reference sites.
Figure 2-1 Annual Mean SO2 Concentrations (ng/m3) for 2006
Site not pictured:
DEN417, AK 0.6
Figure 2-2 Trend in Annual Mean SO2 Concentrations (ng/m3)
20
m^ Concentration
"high: 13.1
1.8 I Low: 0.2
J6 -
12 -
o
^4-*
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Note: All trend diagrams are based on data collected at 34 reference sites.
CASTNET Annual Report - 2006
16
Chapter 2: Atmospheric Concentrations
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Particulate Sulfate
Sulfate is formed in the atmosphere through the transformation of SO2, which is emitted directly
from sources burning fossil fuels. Sulfate is formed via both gas and aqueous (cloud) phase
reactions. Since SO2 can be transported by the winds away from the emission source,
meteorological conditions and atmospheric chemical constituents determine the path by which
sulfate is formed. Sulfur dioxide gas can have a lifetime of up to a week in the atmosphere before
it is subsequently oxidized by hydroxyl (OH) radicals to form sulfur trioxide. In the presence of
water vapor, sulfur trioxide quickly forms sulfuric acid (H2SO4). In turn, H2SO4 reacts with
particles to form particulate sulfate. These gas phase reactions are relatively slow, approximately
equivalent to a SO2 conversion rate of 1.0 percent per hour.
On the other hand, SO2 is a soluble gas and can dissolve in cloud droplets during transport if they
are present. These droplets act as cloud condensation nuclei for sulfate formation. As SO2 is
dissolved in cloud droplets, it is oxidized by hydrogen peroxide to form sulfate. Dissipating
clouds produce ambient particulate SO24".
Sulfate can also be formed directly in stack gases before release to the atmosphere. This type of
production results in a direct emission of SO24". However, a typical emission rate of SO4 is
significantly smaller than an emission rate of SO2.
Sulfate concentrations were generally lower in 2006 than in 2005. A map of annual mean sulfate
(SO4) concentrations for 2006 is presented in Figure 2-3. The map shows a complex region of
concentrations greater than or equal to 4.0 ng/m3. The region extends from Georgia northward to
Kentucky and along the Ohio River Valley to Pennsylvania, Maryland, Virginia, and central
North Carolina. In 2006, the Quaker City, OH (QAK172) site recorded the highest concentration
of 4.7 ng/m3. Sulfate concentrations greater than or equal to 1.0 ng/m3 were measured at three
sites in California - Pinnacles National Monument (PIN414), Sequoia National Park (SEK430),
and Joshua Tree National Monument (JOT403) - and along the southern tier to Chiricahua
National Monument, AZ (CHA467) and Big Bend National Park, TX (BBE401). The CASTNET
site in North Dakota (THR422) measured a SO4 level of 1.1 ng/m3.
Figure 2-4 provides box plots of annual mean SO4 data from 1990 through 2006 for the 34
CASTNET eastern reference sites. Overall, the figure depicts a significant reduction in SO4 over
the last 17 years with some interannual changes. The 2006 mean level was lower than the 2005
value. The difference between 3-year means from 1990-1992 to 2004-2006 is 25 percent, a
change from 5.4 ng/m3 to 4.1 ng/m3, respectively. Over the 2005 to 2006 time period CASTNET
recorded the largest single year drop in sulfate concentrations.
CASTNET Annual Report - 2006 \~J Chapter 2: Atmospheric Concentrations
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Figure 2-3 Annual Mean SO24" Concentrations (ng/m3) for 2006
1.4
Site not pictured:
DEN417,AK 0.5
Concentration
high: 4.7
Low: 0.5
Figure 2-4 Trend in Annual Mean SO24" Concentrations (ng/m3)
7 -
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75th Percentile
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CASTNET Annual Report - 2006
18
Chapter 2: Atmospheric Concentrations
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A map of annual mean total nitrate concentrations for 2006 is given in Figure 2-5. Total nitrate
is defined as the sum of gaseous nitric acid (HNO3) and particulate nitrate (NO3). Measurement
of total nitrate concentrations measures the response to changes in nitrogen oxides (NOX)
emissions more accurately than measurement of either of its constituents alone. Also,
measurements of the individual constituents are thought to include measurement uncertainties.
See the call out box in Chapter 3 (page 28) for a discussion of the uncertainties in CASTNET
HNO3 and NO3 measurements.
The map in Figure 2-5 shows a complex pattern of total nitrate concentrations in the eastern
United States. Most CASTNET monitors recorded values greater than 2.0 |J,g/m3. The geographic
variability in concentrations is caused by changes in the elevation and location of the monitoring
stations and the associated differences in deposition velocities, inversion heights, and exposure to
fresh NOX emissions. The highest annual mean total nitrate values were recorded in Illinois,
Indiana, and Ohio. Three CASTNET sites in California measured total nitrate concentrations
above 3.0 ng/m3. Two sites - Converse Station (CON186) and JOT403 - are located downwind
of the Los Angeles Basin. The third California site, SEK430, is located in the Sierra Nevada
Mountains adjacent to the agricultural region known as the Central Valley.
Box plots of annual total nitrate values from the 34 CASTNET reference sites are provided in
Figure 2-6. The data show a decline in total nitrate from 2000 to 2006. The 2006 mean
concentration was the lowest in the history of the network. The overall trend depicts an 18
percent reduction in total nitrate from 1990 to 2006.
-------
Figure 2-5 Annual Mean Total Nitrate (NO3 + HNO3) Concentrations (ng/m3) for 2006
Site not pictured:
DEN417,AK 0.1
Concentration
I High : 3.9
Figure 2-6 Trend in Annual Total Nitrate (NO3 + HNO3) Concentrations (ng/m3)
O)
atio
-------
Air Quality Concerns in the Four Corners Region
The Four Corners region of Colorado, New
Mexico, Arizona, and Utah is experiencing
significant energy development including new
oil and gas wells, more power plants, and
an increasing population. The Bureau of Land
Management has expressed concern that Class I
areas in the region may experience a deterioration
in visibility and air quality in addition to an
increase in ozone (O3) concentrations as a result
of the growth in energy development. This led to
the formation of a multi-stakeholder task force to
focus on air quality in the region (NM
Environment Dept, 2007).
Mesa Verde National Park, CO (MEV405)
The states of Colorado and New Mexico convened the task force in 2005. The efforts of this
task force are shared by federal, tribal, state, and local air quality management agencies in
the Four Corners region. The public is also participating, and NFS has been actively
involved since 2005. The task force is assessing existing conditions and developing options
for improving air quality in the area. The goal is to create options that will consider
accommodating energy growth and the associated economic development without
compromising air quality (NM Environment Dept., 2007). For more information on the task
force, visit http://www.nmenv.state.nm.us/aqb/4C/index.html.
Data from the CASTNET site at Mesa Verde National Park, CO (MEV405), which is
located in the Four Corners region, provide information on changes in sulfur and nitrogen
pollutants and ozone over the period 1995 through 2006. The figure shows annual mean
concentrations of sulfur dioxide (SO2)
Trend in Pollutant Concentrations at MEV405, CO and total nitrate (NO'3) and fourth
highest daily maximum 8-hour average
ozone (O3) concentrations for the
12 years. The data suggest increases in
total nitrate concentrations and an
overall decline in SO2. However, SO2
values have increased over the last two
years. Three-year average fourth
highest daily maximum 8-hour average
O3 concentrations increased by about
10 percent from 1995 to 2006.
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CASTNET Annual Report - 2006
Chapter 2: Atmospheric Concentrations
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Particulate Ammonium
A map of annual mean ammonium (NFT4) concentrations is presented in Figure 2-7. The map
shows no annual concentrations greater than 2.0 |J,g/m3. The NFt, concentrations measured at
western sites were low with all sites measuring concentrations below 1.0 |J,g/m3. The trend
diagram for annual mean NFT4 values is provided in Figure 2-8. The box plots show a 20 percent
decline in 3-year mean NFt, concentrations from 1990 to 2006 (1.79 |J,g/m3 to 1.43 |j,g/m3). The
2006 mean was the lowest in CASTNET history. It is important to note that these mean values
were based only on data from the 34 CASTNET reference sites (Figure 1-6), which include only
one site west of the Mississippi River. Additional studies using wet deposition data from
NADP/NTN have shown an increase in NEt, concentrations in the Great Plains where the
geographic coverage of CASTNET sites is less in extent (i.e., fewer sites) than the coverage
provided by NTN (NADP, 2003).
Figure 2-7 Annual Mean NFT4 Concentrations (ng/m3) for 2006
Site not pictured:
DEN417.AK 0.1
Concentration
I High: 1.8
Low : 0.2
CASTNET Annual Report - 2006
22
Chapter 2: Atmospheric Concentrations
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Figure 2-8 Trend in Annual Mean MT4 Concentrations (ng/m3)
D)
O -I I
O1 "
Petrified Forest National Park (PET427), AZ
CASTNET Annual Report - 2006
23
Chapter 2: Atmospheric Concentrations
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Chapter3:
Atmospheric Deposition
Denali National Park, AK (DEN417)
One of the principal objectives of CASTNET is to provide estimates of the dry deposition
of sulfur and nitrogen pollutants across the United States. CASTNET uses a hybrid
approach to estimating dry deposition by combining measured pollutant concentrations and
modeled deposition velocities. The Multi-Layer Model (MLM) is the computer model used
to calculate site-by-site deposition velocities based on meteorological measurements and
information on the surrounding vegetation. Total deposition is the sum of estimated dry
deposition and measured wet deposition. Since 1990, total sulfur deposition has declined
significantly. The data show a 28 percent reduction in 3-year mean sulfur fluxes over
the period from 1990-1992 to 2004-2006. Total nitrate deposition declined by 12 percent
over the same period. Dry deposition is responsible for approximately 20 to 80 percent of
total deposition depending on location and climate. The percentage is higher in major
source regions.
Gaseous and aerosol sulfur and nitrogen pollutants are deposited into ecosystems through dry
and wet atmospheric processes. One of the most critical objectives of CASTNET is to estimate
the rate, or flux, of dry deposition from measured meteorological and other environmental
conditions. Flux values are estimated as the product of measured concentration data and MLM-
modeled dry deposition velocities. For this report, wet deposition measurements were obtained
from NADP/NTN and combined with CASTNET dry deposition data to estimate total
deposition. Dry sulfur and nitrogen deposition rates decreased slightly during 2006 while total
deposition stayed about the same. Precipitation-weighted mean concentrations in precipitation of
total atmospheric sulfur have declined over the past 17 years. Nitrogen concentrations in
precipitation have declined slowly since 1996.
Dry deposition processes were simulated using the MLM (Figure 1-5) as described by
Meyers et al. (1998) and Finkelstein et al. (2000). An improved version of the MLM
(Schwede, 2006) was provided to MACTEC in 2006. For this report, the MLM was run using
CASTNET filter pack concentrations and meteorological measurements with information on
land use, vegetation, and surface conditions to calculate deposition velocities for sulfur dioxide
CASTNET Annual Report - 2006 24 Chapter 3: Atmospheric Deposition
-------
(SO2), nitric acid (HNO3), ozone (O3), and the particles sulfate (SO24"), nitrate (NO3), and
ammonium (NH^). The deposition velocities were assumed to be identical for all particle species.
Deposition velocity values were calculated for each pollutant species for each hour with valid
meteorological data for each CASTNET site for the entire period 1990 through 2006. For a
deposition velocity to be estimated, temperature, solar radiation, relative humidity, wind speed,
and standard deviation of the wind direction (sigma theta) must all be valid for the hour.
Aggregation rules for CASTNET require three valid quarters for the calculation of an annual
value. If an annual value is not available for a specific site, the results are not included on maps
presented in this chapter. For trends analyses, missing values are replaced by interpolation or
extrapolation using valid annual estimates.
Sulfur Deposition
MLM simulations were run separately for sulfur dioxide (SO2) and sulfate (SO24"). The model
calculations were summed to obtain estimates of dry sulfur deposition [as sulfur (S)]. Figure 3-1
provides a map of estimates of dry sulfur deposition for 2006. The magnitude of a deposition rate
is illustrated by the size of the circle. The map shows a narrow region with fluxes greater than
5.0 kilograms per hectare per year (kg/ha/yr) centered around and downwind of the Ohio River
Valley from southern Indiana and central Kentucky to eastern Pennsylvania. Locations on the
map with no value had insufficient data to calculate fluxes. The highest deposition rate was
estimated for Quaker City, OH (QAK172) with a flux of 11.0 kg/ha/yr. The highest dry sulfur
deposition rates were coincidental to the major SO2 source region (Figure 1-7) and declined
sharply with distance. The dry deposition rates for the western sites were all less than
1.0 kg/ha/yr with the majority of sites less than 0.5 kg/ha/yr.
Figure 3-1 Dry Sulfur (SO2 + SO2;) Deposition (as S) (kg/ha/yr) for 2006
Site not pictured:
DEN417, AK 0.2
CASTNET Annual Report - 2006
25
Chapter 3: Atmospheric Deposition
-------
Wet deposition values used to estimate total deposition represent a combination of historical
CASTNET wet deposition data with NADP/NTN wet deposition data. For CASTNET sites
where wet concentrations were measured prior to January 1999 (when responsibility for wet
deposition monitoring activities at CASTNET sites was transferred to NADP/NTN), those values
were used in the data set. For sites where no wet concentrations were measured and for all sites
after January 1999, values were obtained from a grid of concentration estimates derived from
available NADP/NTN sites by using an inverse distance weighting function. Estimated
concentrations were multiplied by the precipitation measured at the CASTNET sites to obtain
estimates of wet deposition.
Figure 3-2 provides a map of estimates of total sulfur deposition. The map was constructed by
adding dry and wet deposition. The circles in the figure illustrate the magnitude of total sulfur
deposition and also the relative contributions from wet and dry deposition. The dark shading
(blue) signifies the percent wet deposition and the light shading (tan) shows the percent dry
deposition. A region with total (dry + wet) sulfur deposition (kg/ha/yr) greater than 10.0 kg/ha/yr
extended from southwestern Indiana and central Kentucky along the Ohio JAiver Valley and into
Ontario, Canada. Sites in Virginia, Tennessee, and Alabama also had total sulfur fluxes greater
than or equal to 10.0 kg/ha/yr. Sulfur deposition at western sites was less than 2.0 kg/ha/yr. The
contribution of dry deposition was much more significant in and near major source regions. For
example, the contribution of dry sulfur deposition ranged from about half of total sulfur
deposition at Oxford, OH (OXF122) to less than 25 percent at sites in New England.
Figure 3-2 Total (Dry + Wet) Sulfur Deposition (as S) (kg/ha/yr) for 2006
Site not pictured:
DEN417, AK
0.4
Total Deposition
16
8
1.6
H Dry Deposition
Wet Deposition
CASTNET Annual Report - 2006
26
Chapter 3: Atmospheric Deposition
-------
Figure 3-3 presents box plots that show the
trend in dry sulfur deposition (as S), and
Figure 3-4 shows the trend in annual total
(dry + wet) sulfur deposition (as S) over the
17 years, 1990 through 2006. The box plots
were based on data obtained from the 34
eastern CASTNET reference sites
(Figure 1-6). Sulfur deposition at these sites
declined significantly over the 17 years.
Figure 3-5 presents estimates of trends in
dry, wet, and total deposition of sulfur (as S)
on the same diagram. The trend line for
precipitation-weighted mean sulfur
concentrations in precipitation shows a
continuing decrease over the last several
years with small increases in 2005 and 2006.
The influence of precipitation on total sulfur
deposition is illustrated by comparing the
solid (top) line to the dotted blue line in
Figure 3-5. The solid line shows total
deposition, which depends on sulfur
concentrations in precipitation and
precipitation amounts. The dotted line
shows concentrations in precipitation,
which reflect changes in SO2 emissions. The
year 2003 experienced relatively high total
sulfur deposition even though the sulfur
concentration in precipitation was relatively
low. Above average precipitation produced
the relatively high total flux of sulfur.
Nonetheless, total sulfur deposition
declined from a 1990-1992 mean of
13.2 kg/ha/yr to a 2004-2006 mean of 9.5,
a 28 percent reduction.
Figure 3-3 Trend in Dry Sulfur Deposition
(kg/ha/yr)
12
25
2 -
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
CMCMCMCM
Figure 3-4 Trend in Total Sulfur Deposition
(kg/ha/yr)
20 -
b15-
110-
5 -
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
ฐ ฐ ฐ ฐ ฐ ฐ ฐ
Figure 3-5 Trend in Sulfur Deposition
(kg/ha/yr) with Concentrations in Precipitation
(mg/1)
16
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Total Deposition
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-------
Uncertainties in Estimates of Dry Nitrogen Deposition
EPA's National Exposure Research
Laboratory (NERL), which is part of the
Office of Research and Development (ORD),
recently sponsored a short, warm-season
study to investigate the measurement
uncertainties for CASTNET nitrogen species.
The study examined the size distribution of
CASTNET particle measurements through
additional sampling in 2006 at three Mid-
Atlantic CASTNET sites: Beltsville, MD
(BEL116), Arendtsville, PA (ARE128), and
Blackwater Wildlife Refuge, MD (BWR139).
Weekly concentrations were measured with
and without cyclone particle size separators
for six measurement cycles over the period
March 28, 2006 through August 22, 2006.
BEL116 utilized cyclones with three different
size cut off points: 10.0, 5.0, and 2.5
micrometers (|J,m). The other two sites
operated cyclones with a 2.5 |j,m cut off.
The results are summarized in the three bar
charts shown to the right. Mean, maximum,
and minimum concentrations from the six
samples are provided for ammonium (NH!,),
nitric acid (HNO3), and nitrate (NO3) for each
sampling configuration. The measurements
show that the NH^, concentrations at the three
sites were not affected by the cyclones and
existed as small (<2.5|j,m) particles. NH^
results were very similar to those of SO24" (not
shown) because during the warm season (i.e.,
the time of the study) most NH^ exists as
ammonium sulfate [(NEL^SO^]. However,
HNO3 and particulate NO3 concentrations
were affected by the presence of cyclones.
Higher HNO3 concentrations were measured
Ammonium Special Study Results
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Nitrate Special Study Results
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with the standard CASTNET open-face filter packs. Considerably higher particulate NO3
concentrations were measured with the open face configurations, and the concentrations
decreased substantially as the cyclone cut-off points decreased (Lavery et al, 2007).
Although limited in both temporal and spatial coverage, analysis of the study results
provides new information on the measurement of nitrogen species using the standard
CASTNET sampling protocol. The CASTNET open-face filter pack measures particles with
a range of sizes from more than 10.0 |j,m to less than 2.5 |j,m. The larger particles are
comprised of salts and trace metals, which are produced by sea spray and soil dust. Sodium
nitrate (NaNO3) and calcium nitrate [Ca(NO3)2] constitute a significant fraction of the coarse
particles. These nitrate particles are produced by the reaction of HNO3 with sodium chloride
(NaCl) and calcium carbonate (CaCO3) in ambient air, on the Teflonฎ filter, or both. The
fine particles are comprised of ammonium nitrate (NH4NO3), which is produced by the
reaction of ammonia (NH3) with HNO3.
A comparison of CASTNET measurements with data from other studies suggests that the
right combination of atmospheric conditions (e.g., temperature, relative humidity, and solar
radiation) causes the volatilization and conversion of NH4NO3 to HNO3 and NH3 during the
CASTNET weekly sampling period. These reactions result in a decrease in NO3 and an
increase in HNO3 on the filters. These NO3 > HNO3 concentration changes were
corroborated by Teflonฎ and nylon filter measurements that were part of the Midwest
Ammonia Monitoring Project (Sweet et al., 2005). The relative loss of NO3 and gain of
HNO3 are unknown and vary significantly based on the geographic location of the
monitoring site and on the season (Ames and Malm, 2001).
One of the goals of CASTNET is to estimate dry deposition of particles and gases. The
collection of coarse nitrate particles complicates the calculation of deposition velocities. The
coarse particles are affected by the meteorological and biochemical processes that are
simulated by the MLM. However, these particles are also subject to gravitational settling,
which is not simulated. The net effect is likely an underestimation of the dry deposition of
nitrate particles. Since dry deposition is directly proportional to the concentration of the
pollutant, an uncertainty in the concentration measurement produces an uncertainty in the
flux estimate. In the case of nitrogen species, an overestimation of HNO3 or NO3 affects
the modeled dry nitrogen deposition. Since HNO3 deposition velocities are significantly
higher than that of NO3, bias in the HNO3 concentration is amplified in the total nitrogen
deposition reported.
CASTNET Annual Report - 2006 29 Chapter 3: Atmospheric Deposition
-------
Nitrogen Deposition
Figure 3-6 presents a map of dry fluxes of nitrogen [as nitrogen (N)] for 2006. Nitrogen fluxes
are comprised of nitric acid (HNO3) + nitrate (NO3) + ammonium (NFj,). This map was
constructed by summing the individual MLM simulations for the three species. Almost all of the
CASTNET sites in the eastern United States had estimated dry nitrogen deposition rates greater
than 1.0 kg/ha/yr. Other than the relatively low deposition rates at Cedar Creek State Park, WV
(CDR119) and Coweeta, NC (COW 137), the nitrogen fluxes were fairly uniform geographically,
reflecting a wide distribution of nitrogen oxides (NOX) sources (such as motor vehicles). The flux
values ranged from 0.4 kg/ha/yr in upstate New York to 3.1 kg/ha/yr in eastern Ohio. The values
at the western sites ranged from 0.2 kg/ha/yr at Mount Rainier National Park, WA (MOR409) to
3.0 kg/ha/yr at Sequoia National Park, CA (SEK430). Locations on the map with no value had
insufficient data to calculate fluxes.
Figure 3-6 Dry Nitrogen (HNO3 + NO3 + NlT4) Deposition (as N) (kg/ha/yr) for 2006
Site not pictured:
DEN417.AK 0.1
Deposition
CASTNET Annual Report - 2006
30
Chapter 3: Atmospheric Deposition
-------
Figure 3-7 presents a map of total nitrogen deposition (as N) for 2006. The map was constructed
by summing the estimates of dry (light shading) and wet (dark shading) deposition. The figure
shows that a large majority of the eastern sites recorded deposition rates greater than
5.0 kg/ha/yr. No values above 10.0 kg/ha/yr were observed in 2006. The highest total nitrogen
flux (9.2 kg/ha/yr) was estimated for Vincennes, IN (VIN140) and Quaker City, OH (QAK172).
Fluxes with values less than 5.0 kg/ha/yr in the eastern United States were estimated for New
England, upstate New York, Minnesota, Florida, and Texas. The values at the western sites
ranged from 1.2 kg/ha/yr at Yosemite National Park, CA (YOS404), Pinedale, WY (PND165),
and MOR409, WA to 5.1 kg/ha/yr in southern California at Converse Station (CON186). The
contributions of dry nitrogen deposition to total nitrogen were lower than the corresponding
contributions of dry sulfur deposition. Dry nitrogen deposition typically contributed less than 50
percent of total deposition in the East. Interestingly, dry nitrogen deposition contributed more
than half of total nitrogen deposition at sites in California, a region with elevated concentrations
of nitrogen species and limited rainfall. The CASTNET site at QAK172, OH had the distinction
of measuring both the highest total sulfur and total nitrogen deposition rates.
Figure 3-7 Total (Dry + Wet) Nitrogen Deposition (as N) (kg/ha/yr) for 2006
Site not pictured:
DEN417, AK
0.2
Total Deposition
10
5
1
H Dry Deposition
Wet Deposition
CASTNET Annual Report - 2006
31
Chapter 3: Atmospheric Deposition
-------
Figure 3-8 presents box plots that show the
17-year trend in dry nitrogen deposition
(as N), and Figure 3-9 shows the trend in
annual total (dry + wet) nitrogen deposition
over the 17 years, 1990 through 2006. The
box plots in Figure 3-8 show little overall
trend although the data suggest a decline in
dry nitrogen deposition since 1999. Total
nitrogen deposition (Figure 3-9) is more
variable because the annual wet and total
fluxes depend on the amount of
precipitation. The figure suggests that total
flux has decreased since perhaps 1996.
Again, the total flux in 2003 was relatively
high because of unusually high precipitation.
Estimates of trends in wet, dry, and total
deposition of atmospheric nitrogen (as N)
are presented in Figure 3-10. The trend in
precipitation-weighted mean nitrogen
concentrations in precipitation is also
provided on the same figure. The trend line
for precipitation-weighted mean nitrogen
concentrations in precipitation shows a
slight downward trend since 1998. This
trend line reflects the effect of changes in
NOX emissions. Total nitrogen deposition
declined 12 percent over the 17 years.
Figure 3-8 Trend in Dry Nitrogen
Deposition (kg/ha/yr)
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1.2
1.0
0.8
0.6 '
0.4
<
0.2
0.0
c
o
O
O
CASTNET Annual Report - 2006
32
Chapter 3: Atmospheric Deposition
-------
Chapter 4:
Ozone Concentrations
Gothic, CO (GTH161)
CASTNET provides the primary means for monitoring rural, ground-level ozone (O3)
concentrations in the United States. Fourth highest daily maximum 8-hour average O3
concentrations represent the critical metric for evaluating compliance with National
Ambient Air Quality Standards (NAAQS). These annual fourth highest daily maximum
concentrations are averaged over 3-year periods to determine potential areas of
nonattainment. If the average ozone concentration for an area exceeds 0.08 ppm or
reaches 85 ppb in practice, the area is designated as a "nonattainment area." For the
most recent 3-year period (2004-2006), only two eastern and four California sites
recorded exceedances of the 8-hour standard. This represents the fewest number of sites
with exceedances over a 3-year period in the history of the network.
Most CASTNET sites operate an ozone (O3) analyzer that provides information on
ozone concentrations. Ozone data are recorded and archived as hourly averages. While
CASTNET is not a compliance network, the data collected provide useful information on
geographic patterns in regional O3 and the extent to which rural areas potentially exceed
concentration values mandated by the National Ambient Air Quality Standards (NAAQS). The
8-hour O3 standard is a useful metric for assessing status and trends in rural O3 in order to gauge
the success of EPA emission reduction programs such as the NOX Budget Program. The analyses
presented in this section provide maps and examine trends in the fourth highest daily maximum
8-hour average O3 concentrations.
Ozone is an allotrope of oxygen (made up of three oxygen atoms). At ground level, it is an air
pollutant that can cause harmful effects on the human respiratory system as well as damage to
vegetation and ecosystems. Ozone is formed in the troposphere when volatile organic
compounds (VOC), nitrogen oxides (NOX), and carbon monoxide (CO) react in the presence of
sunlight. Ozone is a result of the photolysis of nitrogen dioxide (NO2):
NO2 + hv -> NO + O (4-1)
O + O2 -> O3+M (4-2)
Where hv represents incoming solar radiation and M represents any body [e.g., nitrogen (N2) or
oxygen (O2) molecules] present during the reaction to absorb energy. Reaction 4-2 is the only
CASTNET Annual Report - 2006 oo Chapter 4: Ozone Concentrations
-------
significant source of ozone in the atmosphere. Once formed, O3 reacts with nitric oxide (NO) to
regenerate NO2:
O3 + NO -> NO2 + O2 (4-3)
Measured O3 concentrations frequently exceed those predicted by Reactions 4-1 through 4-3.
Other reactions involving carbon-containing species enhance the production of O3 by
producing free radicals that oxidize NO to NO2 and subsequently to O3 via Reaction 4-2. In the
"background" troposphere, O3 concentrations are produced by methane and CO oxidation,
transport from the stratosphere, and very long-range transport. In more polluted locations, the
chemical reactions of VOC such as alkanes, alkenes, and aromatic hydrocarbons and NOX
dominate over methane and CO chemistry. Biogenic VOC emissions from trees and other
vegetation contribute to O3 formation in rural areas (EPA, 2007c). Volatile organic compound
emission reduction strategies have been successful in reducing higher short-term O3
concentrations in and downwind of urban areas. However, as discussed in this chapter, NOX
emission reductions that were mandated by the Acid Rain Program and other NOX emission
control programs were necessary to reduce O3 concentrations, especially elevated 8-hour
levels in rural areas. These reductions will continue to be required for additional declines in
8-hour O3 levels.
During the period 2004-2006, 3-year averages of the fourth highest daily maximum 8-hour
average O3 concentrations were greater than or equal to 85 parts per billion (ppb) at four sites in
California, one in New Jersey, and one in Maryland. Measurements of 8-hour concentrations
during 2006 were somewhat lower than 2005 and were considerably lower than concentrations
measured over the period 1990-2002. Following a peak in ozone levels in 2002, there has been a
downward trend that has continued through 2006.
The concentration shading for the figures used in this chapter was prepared based on rural ozone
concentration data using an algorithm inverse distance cubed weighting with a radius of
influence of 500 km. Consequently, concentration estimates for areas with limited monitoring
site coverage, such as much of Texas, and concentrations depicted for urban areas, such as
Atlanta, are approximations. Additional maps of ozone concentrations can be viewed on the Web
site for the NFS Air Atlas (http://science.nature.nps.gov/AirAtlas/AirAtlas0105/viewer.htm).
Figure 4-1 presents 3-year averages of the fourth highest daily maximum 8-hour O3
concentrations for 2004-2006. Two eastern and four California sites measured 3-year average
concentrations greater than or equal to 85 ppb. These 3-year average concentrations constitute
current design values for achieving the 8-hour NAAQS for O3. For example, the estimated value
of 117 ppb at Converse Station, CA (CON186) would have to be reduced to 84 ppb to achieve
the standard. Design values change as a new 3-year database becomes available.
CASTNET Annual Report - 2006 34 Chapter 4: Ozone Concentrations
-------
National Ambient Air Quality Standard for Ozone
8-Hour Ozone Standard
To better protect public health, EPA (1997) revised its national air quality standards for
ozone in 1997, establishing an 8-hour standard. The 8-hour standard is 0.08 parts per
million (ppm). An area meets the standard if the 3-year average of the annual fourth
highest daily maximum 8-hour average concentration is less than or equal to 0.08 ppm.
The 3-year average reduces the influence that meteorological conditions have on the
extent and magnitude of ozone formation. Recently, EPA proposed strengthening the
8-hour standard to a level within the range of 0.07 ppm to 0.075 ppm (EPA, 2007a). For
more information on the 8-hour ozone standard and ozone nonattainment areas in the
United States, visit http://www.epa.gov/ozonedesignations/.
What Does It Mean?
EPA collects ozone data on an hourly basis. Essentially, 8-hour average ozone
concentrations at a monitor cannot exceed 0.08 ppm more than three days during the
ozone season. For compliance purposes:
* Hourly ozone measurements are used to compute 8-hour average concentrations.
* The daily maximum 8-hour average is recorded for each day.
* For each year, the fourth highest daily maximum concentration is calculated.
* These annual fourth highest daily maximum concentrations are averaged over
3-year periods.
* If the fourth highest daily 8-hour average exceeds 0.084 ppm (0.085 rounds up to
0.09 thus exceeding the standard criteria) or reaches 85 ppb in practice, the area is
designated as a "nonattainment area" and is held accountable for reaching the
attainment status.
For comparison to current data, 3-year averages of the fourth highest daily maximum 8-hour
average O3 concentrations for 2001-2003 are presented in Figure 4-2. Sixteen eastern and the
same four California sites recorded 3-year averages greater than or equal to 85 ppb. The regions
with elevated concentrations were located along the East Coast from northern Virginia to Maine
and in Pennsylvania, Ohio, and Michigan. A value of 92 ppb was measured at Great Smoky
Mountains National Park, TN (GRS420). The period 2004-2006 represents a significant
improvement in air quality. In fact, the period 2004-2006 represents the best period of air quality
since the inception of CASTNET in terms of having the fewest sites with exceedances of the
8-hour O3NAAQS.
CASTNET Annual Report - 2006 QK Chapter 4: Ozone Concentrations
-------
Figure 4-1 Fourth Highest Daily Maximum 8-Hour Ozone Concentrations (ppb) for
2004-2006
Site not pictured:
DEN417.AK 51
Concentration
High: 117
Figure 4-2 Fourth Highest Daily Maximum 8-Hour Ozone Concentrations (ppb) for
2001-2003
64-64
Site not pictured:
DEN417.AK 54
Concentration
High: 128
69 Low : 34
CASTNET Annual Report - 2006
Chapter 4: Ozone Concentrations
-------
Fourth highest daily maximum 8-hour O3 concentrations for 2006 are shown in Figure 4-3.
Concentrations greater than or equal to 85 ppb were recorded at three sites in the East including
GRS420, TN; Georgia Station, GA (GAS 153); and Beltsville, MD (BEL 116). In addition, four
California CASTNET sites monitored exceedances of the 8-hour ozone NAAQS. The California
sites include CON186, Joshua Tree National Monument (JOT403), Sequoia National Park
(SEK430), and Yosemite National Park (YOS404). The 8-hour level of 108 ppb at CON186, CA
was the highest value that was measured in the network during 2006.
Figure 4-3 Fourth Highest Daily Maximum 8-Hour Ozone Concentrations (ppb) for 2006
Site not pictured:
DEN417.AK 53
v
. Concentration
High : 108
73 | B Low : 51
Since 2002, CASTNET ozone measurements have shown a significant decline in annual fourth
highest daily maximum 8-hour average concentrations throughout the 34 eastern reference sites
(see Figure 1-6) used to track trends in concentrations. During 2002, 24 reference sites measured
fourth highest daily maximum 8-hour O3 concentrations greater than or equal to 85 ppb. The
number of reference sites with exceedances was reduced to six in 2003, followed by a further
reduction to none in 2004, and five in 2005. As shown in Figure 4-3, two eastern reference sites
(BEL116, MD and GAS153, GA) recorded elevated 8-hour concentrations in 2006.
Figure 4-4 shows the 17-year trend in 8-hour O3 concentrations aggregated over the 34 reference
stations. The box plots show a significant decline from 2002 to 2004. The 2005 data show a
small increase, and the 2006 data show a decrease from 2005. Median values for the aggregated
measurements for the five years 2002 through 2006 were 88 ppb, 79 ppb, 70 ppb, 76 ppb, and
72 ppb, respectively.
CASTNET Annual Report - 2006
Chapter 4: Ozone Concentrations
-------
Figure 4-4 Trend in Fourth Highest Daily
Maximum 8-Hour Ozone Concentrations (ppb)
Figure 4-5 Trend in Ozone Season Mean
Total Nitrate Concentrations (|j,g/m3)
120
o
O
80 -
60
90th Percentile
75" Percentile
Median
Mean
25" Percentile
10" Percentile
3
1 -
CM CM CM CM CM CM CM
O <- CM CO
CM CM CM CM CM CM
The median O3 concentration for 2006 was the second lowest in the 17-year period. Additional
information on ozone measurements can be found in the NFS annual reports on O3 monitoring
and O3 trends (http://www2.nature.nps.gov/air/Monitoring/network.cfm#procedures).
The CASTNET 2005 Annual Report (MACTEC, 2006a) discussed the relationship between
changes in O3 concentrations and changes in emissions of nitrogen oxides (NOX). EPA (2005b,
2006) attributed the decline in NOX emissions to several effective control programs:
t Mobile source controls,
t Volatile Organic Compound Reasonably Available Control Technology and Maximum
Available Control Technology,
t New Source Review,
t Acid Rain Program,
* Ozone Transport Commission NOX Budget (1999-2002), and
* NOX State Implementation Plan Call (2003-current).
These programs continue to produce reductions in NOX emissions in the eastern United States.
The trend in CASTNET measurements of total nitrate concentrations (Figure 4-5) shows a
relationship between the decline in ozone and a decline in atmospheric nitrogen. The box plots
show a significant reduction in total nitrate concentrations during the ozone season since 1999.
The ozone season varies between states but is typically from the beginning of April through the
end of September or October in the eastern United States.
CASTNET Annual Report - 2006
38
Chapter 4: Ozone Concentrations
-------
Elevated Ozone Concentrations in Atlanta during 2006
The CASTNET site at Georgia Station, GA (GAS 153) recorded its 2006 fourth highest daily
maximum ozone (O3) concentration of 92 ppb on June 9, 2006. This site had not recorded an
exceedance since 2002. The GAS 153 O3 level was part of an ozone episode that occurred in the
greater Atlanta region over the period June 8 through June 11, 2006. Daily maximum 1-hour O3
concentrations for State and Local Ambient Monitoring Stations (SLAMS) ozone sites operated
by the State of Georgia and for the GAS 153 and Sand Mountain, AL (SND152) CASTNET sites
are presented by four maps, one for each day from June 8 through June 11, 2006. The Atlanta
Metropolitan Statistical Area, which consists of 20 counties, is shown on the four maps using
gray outlines. The SLAMS data provide information on urban O3 concentrations, which
supplement the rural CASTNET measurements. The use of both SLAMS and CASTNET data
provides a detailed depiction of the geographic pattern of ozone levels in the greater Atlanta area.
The use of daily maximum 1-hour O3 levels illustrates the evolution and extent of the episode
over the four days. The circles on the maps designate the two CASTNET sites.
Daily Maximum i-Hour O3 Concentrations for CASTNET and SLAMS
Daily Maximum 1 -Hour
Ozone Concentration
CASTNET Annual Report - 2006
Chapter 4: Ozone Concentrations
-------
The beginning of the episode was signaled by ozone concentrations in excess of 80 ppb in
southeast Atlanta on June 8. The levels increased on June 9 with concentrations as high as
107 ppb at the McDonough SLAMS site southeast of downtown Atlanta. The peak 1-hour value
at GAS153 on June 9 was 101 ppb.
Backward trajectories from the National Oceanic and Atmospheric Administration (NOAA)
Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) Model for June 9, 2006 are
provided. Trajectories ending at GAS 153 are given for 100 meters (m), 500 m, and 2000 m
above ground level (AGL). The three trajectories on June 9 indicate advection through the area
of highest ozone concentrations and an area of dense, low-level precursor emissions.
Concentrations increased on June 10 with several daily maximum values in excess of 90 ppb and
six stations with levels greater than or equal to 100 ppb. Backward trajectories are also provided
for this day. High ozone values were widespread on June 10 because of air mass subsidence and
higher temperatures. The 100 m trajectory ending at GAS 153 originated at an elevation of almost
2000 m 24 hours earlier. Evidently, a localized high ozone event was observed on June 9, and the
episode became more widespread on June 10 with prevalent high pressure and warm
temperatures favorable to production of high ozone concentrations. Daily maximum hourly O3
concentrations were significantly lower on June 11 with only two values above 85 ppb.
Trajectory June 9, 2006
Trajectory June 10, 2006
MOAA HYSPLIT MODEL
Backward trajectories ending at 19 UTC 09 Jun 06
EDAS Meteorological Data
500
H^?5
Job ID HK1E.03 Jar. SlHtt
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/ yn Li? lfcGMT?OD/
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NOAA HYSPLIT MODEL
Backward trajectories ending at 19 UTC 10 Jun 06
EDAS Meteorological Data
?4 ti/H MBIHO Daia f DASlo
Vefoclty
-:. '.V--" -' !,- .i '!;.. y.ww V r'i,33 'J'. v
CASTNET Annual Report - 2006
40
Chapter 4: Ozone Concentrations
-------
Chapter 5:
Data Quality
Claryville, NY (CAT175)
CASTNET measurements are assessed routinely in terms of providing high-quality
information to meet CASTNET objectives. The CASTNET quality assurance program is
based on specified data quality objectives, which are evaluated using data quality indicators
(DQI). Measurements taken during 2006 and historical data collected over the period
1990-2005 were analyzed relative to DQI and their numerical measures. These analyses
demonstrate that CASTNET data can be used with confidence and that CASTNET continues
to produce data of the highest quality.
The CASTNET Quality Assurance (QA) program was designed to ensure that all reported data
are of known and documented quality in order to meet CASTNET objectives and to be
reproducible and comparable with data from other monitoring networks and laboratories. The
QA program elements are documented in the Quality Assurance Project Plan (QAPP),
Revision 3.0 (MACTEC, 2005). The QAPP is comprehensive and includes standards and
policies for all components of project operation from site selection through final data reporting.
It includes major sections on field measurements, chemical analysis of field samples, data
management, and assessments and response actions. Standard operating procedures are included
as appendices.
Data quality indicators (DQI) are quantitative statistics and qualitative descriptors used in
interpreting the degree of acceptability and utility of the data collected. The DQI for CASTNET
are precision, accuracy, completeness, bias, representativeness, and comparability. Precision,
accuracy, and completeness for CASTNET 2006 data were analyzed and compared with
historical data collected during the period 1990-2005. The information in this report is
supplemented by analyses that are discussed in quarterly CASTNET Quality Assurance Reports
(e.g., MACTEC, 2007b). These QA reports are produced four times per year with the fourth
quarter report including an annual summary.
CASTNET Annual Report - 2006 41 Chapter 5: Data Quality
-------
Figure 5-1 Historical and 2006 Precision Data for Atmospheric Concentrations
Overall- 1990 to 2005
DMackville, KY-2006
D Rocky Mtn, CO - 2006
HNO,
NO,
NH,
Precision
Exposed Filter Concentrations
Figure 5-1 provides a bar chart in which the bars represent precision estimates for five
CASTNET analytes. Precision is defined as the mean absolute relative percent difference
(MARPD) for both the historical (1990-2005) data for all collocated site pairs and the 2006 data
for the current collocated sites at Mackville, KY (MCK131/231) and Rocky Mountain National
Park, CO (ROM406/206). Trace cations and chloride are excluded from this figure but are shown
later in Figure 5-2. The historical results vary from about 4 percent for particulate sulfate (SO24")
to about 12 percent for particulate nitrate (NO3). The historical MARPD for SO24" met the
criterion for the CASTNET filter pack measurements shown in Table 5-1. The historical results
for sulfur dioxide (SO2) and nitric acid (HNO3) were above the 5 percent criterion but are
considered reasonable. The results for ammonium (NFT4) met the goal of 10 percent. The results
for NO3 were significantly above the 5 percent goal. Historically, the precision of NO3
measurements has been consistently worse than for the other analytes, possibly because NO3
concentrations are the lowest of all the pollutants and nitrate species include sampling artifacts
(Lavery et al., 2007).
The 2006 precision results shown in Figure 5-1 indicate that the MARPD data for MCK131/231
were lower than (i.e., more precise than) the historical results for all five parameters. Four
parameters (SO2, SO24", HNO3, and NFT4) met precision criteria. The 2006 results for
ROM406/206 showed greater precision than historical results for SO4, HNO3, and NO3; the
CASTNET Annual Report - 2006
42
Chapter 5: Data Quality
-------
results for SO24", HNO3, and NEt, met the DQI criteria. Overall, the filter pack precision results for
2006 showed some improvement over 2005.
Table 5-1 Data Quality Indicator Criteria for CASTNET Laboratory Measurements
Analyte
Ammonium (NH4)
Sodium (Na+)
Potassium (K )
Magnesium (Mg +)
Calcium (Ca2+)
Chloride (CL)
Nitrate (NO"3)
Sulfate (SO24")
Method
Automated colorimetry
ICP-AES
ICP-AES
ICP-AES
ICP-AES
Ion chromatography
Ion chromatography
Ion chromatography
Precision1
(MARPD)
10
5
5
5
5
5
5
5
Accuracy2
(%)
90-
95-
95-
95-
95-
95-
95-
95-
110
105
105
105
105
105
105
105
Nominal
Reporting Limits
0.020 mg-N/L
0.005 mg/L
0.005 mg/L
0.003 mg/L
0.003 mg/L
0.020 mg/L
0.008 mg-N/L
0.040 mg/L
Note: This column lists precision goals for both network precision calculated from collocated filter samples and laboratory precision based
on replicate samples. The goal for the ICP-AES precision RPD criterion changed from 10 percent to 5 percent at the onset of the
current contract beginning on July 30, 2003. The precision criterion is applied as described below:
QC conditions: (vl = initial response; v2 = replicate response; RL = nominal reporting limit)
Condition 1: if (v 1 or v2 < RL and the absolute value of (v 1 - v2) < RL) = OK
Condition 2: if (vl-v2) < RL and vl < 5 x RL) = OK
Condition 3: if (vl > 5*RL and RPD < 5%) = OK
Status: one of the conditions is OK = Precision QC Passes
This column lists laboratory accuracy goals based on reference standards and continuing calibration verification spikes. The goal for
the ICP-AES accuracy criterion changed from 90 - 110 percent to 95-105 percent for continuing calibration verification spikes at
the onset of the current contract beginning on July 30, 2003. The criterion remains 90 - 110 percent for ICP-AES reference standards.
ICP-AES = inductively coupled plasma-atomic emission spectrometry
MARPD = mean absolute relative percent difference
N = as nitrogen
For more information on analytical methods and associated precision and accuracy criteria, see the CASTNET QAPP - Revision 3.0
(MACTEC, 2005).
Precision statistics for 2006 for four cations and chloride (Cl~) are summarized in Figure 5-2.
The historical MARPD statistics for both MCK131/231 and ROM406/206 did not meet the DQI
criterion of 5 percent, except for Cl~, which had a MARPD of approximately 5 percent. As
discussed in earlier CASTNET reports (e.g., MACTEC, 2004 and MACTEC, 2003), the very
high historical MARPD for sodium (Na+) was the result of sample bottle contamination. These
bottles are no longer purchased. Also, acceptance testing of the Teflonฎ filters was instituted for
the trace cations and CP in 2003. The 2006 precision results show thatNa+ and CP met the
precision criterion at MCK131/231. The MARPD for Cl" calculated for ROM406/206 met the
criterion for 2006. The 2006 results are similar to the precision data for 2005.
Table 5-2 summarizes 2005 precision results by quarter for the two sets of collocated sites. See
the 2006 Quarterly Data Reports (MACTEC, 2006b; 2006d; 2007c; 2007a; ) and QA Quarterly
Reports (MACTEC, 2006c; 2006e; 2006f; 2007b; ) for discussions of quarterly precision data.
CASTNET Annual Report - 2006
Chapter 5: Data Quality
-------
Figure 5-2 Historical and 2006 Precision Data for Cation and Cl Concentrations
Overall-2000 to 2005
DMackville, KY-2006
D Rocky Mtn, CO-2006
Ca
Na+
cr
Table 5-2 Collocated Precision Results for 2006 Filter Pack Data by Quarter (MARPD)
Site Pairs
MCK 131/231,
Quarter 1
Quarter 2
Quarter 3
Quarter 4
2006
ROM 406/206,
Quarter 1
Quarter 2
Quarter 3
Quarter 4
2006
so2,
KY
3.22
0.96
1.35
1.96
1.87
CO
4.68
5.66
3.70
2.89
4.23
NO3
8.71
7.49
6.36
6.30
7.21
3.64
8.03
12.13
13.26
9.26
NH4
3.86
1.70
1.62
4.03
2.80
2.43
4.84
3.09
15.16
6.38
Ca2
12.17
4.79
2.86
8.33
7.03
7.52
5.86
5.89
5.99
6.31
Mg2+
10.49
5.20
2.33
6.61
6.16
8.07
11.10
5.28
7.44
7.97
Na +
6.40
4.28
3.03
4.00
4.43
6.38
6.17
10.74
9.15
8.11
K
10.30
11.16
1.85
5.09
7.10
9.21
14.89
7.56
11.69
10.84
HNO3
2.90
3.90
2.37
2.74
2.98
4.55
2.36
2.54
4.63
3.52
SO2
2.98
1.81
2.35
2.86
2.50
8.64
4.97
13.00
11.78
9.60
Total
NO3
4.74
3.82
2.26
2.89
3.43
2.63
3.56
1.65
2.11
2.49
Cl
3.46
2.06
0.46
5.05
2.76
1.32
1.14
1.76
2.89
1.78
Note: Shaded values exceed DQI criterion
The 2006 analytical precision results for five analytes and the three filter types are presented in
Figure 5-3. The results were based on analysis of 5 percent of the samples that were randomly
selected for replication in each batch. The results of in-run replicate analyses were compared
to the results of the original concentrations. The laboratory precision data met the 5 percent
measurement criterion listed in Table 5-1.
CASTNET Annual Report - 2006
44
Chapter 5: Data Quality
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Figure 5-3 Precision Results for Laboratory Replicate Samples (2006)
SO4
^1^1^
Teflon Teflon Teflon Teflon
K+ Mg2+ Ca2+ Cf
contribute to SO2
Table 5-3 Data Quality Indicator Criteria for CASTNET Field Measurements
Measurement
Criteria*
Parameter
Wind Speed
Wind Direction
Sigma Theta
Relative Humidity
Solar Radiation
Precipitation
Ambient Temperature
Delta Temperature
Surface Wetness
Ozone
Filter Pack Flow
Method
Anemometer
Wind Vane
Wind Vane
Thin Film Capacitor
Pyranometer
Tipping Bucket Rain Gauge
Platinum RTD
Platinum RTD
Conductivity Bridge
UV Absorbance
Mass Flow Controller
Precision
ฑ 0.5 m/s
ฑ5ฐ
Undefined
ฑ 10% (of full scale)
ฑ 10% (of reading taken at local
noon)
ฑ 10% (of reading)
ฑ 1.0ฐC
ฑ0.5ฐC
Undefined
ฑ 10% (of reading)
ฑ 10%
Accuracy
The greater of ฑ 0.5 m/s for winds < 5
m/s or ฑ 5% for winds > 5 m/s
ฑ5ฐ
Undefined
ฑ 5%, relative humidity > 85%
ฑ 20%, relative humidity < 85%
ฑ 10%
ฑ 0.05 inclvj-
ฑ0.5ฐC
ฑ0.5ฐC
Undefined
ฑ 10%
ฑ5%
Note:
ฐC = degrees Celsius
m/s = meters per second
RTD = resistance-temperature device
UV = ultraviolet
Precision criteria apply to collocated instruments, and accuracy criteria apply to calibration of instruments.
For target value of 0.50 inch.
CASTNET Annual Report - 2006
Chapter 5: Data Quality
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Ozone Concentrations
CASTNET QA procedures for the EPA-sponsored ozone (O3) analyzers are different from the
EPA QA requirements for SLAMS monitoring (EPA, 1998). The QA procedures for the O3
analyzers at the NFS-sponsored sites also do not meet the SLAMS requirements. While NFS
utilizes the appropriate procedures and equipment, the NFS sites are calibrated twice per year
versus the SLAMS requirements of four times per year. In any event, the operation of the
collocated O3 analyzers at ROM406/206, CO provides an opportunity to evaluate the precision of
the independent systems. Table 5-3 provides the DQI criteria for the CASTNET continuous
measurements including O3. The precision criterion for the collocated O3 data is 10 percent.
MARPD statistics were calculated from hourly O3 measurements obtained from the collocated
sites MCK131/231, KY and ROM406/206, CO during 2006. In addition, quarterly historical
precision statistics were compiled for all collocated sites. Quarterly precision results are
summarized in Figure 5-4. The data show the historical results met the 10 percent criterion. The
2006 precision data also met the 10 percent criterion for the second and third quarters for both
MCK131/231 and ROM406/206. The results for ROM406/206 did not meet the criterion during
the first quarter. The high MARPD was caused by unusually low O3 concentrations. Many hourly
levels were less than 10 ppb. MARPD was not calculated for MCK131/231 fourth quarter O3
data. The MCK131 analyzer exhibited significant drift that began near the end of October, and
the data are considered suspect and are undergoing additional review.
Figure 5-4 Historical and 2006 Precision Data by Quarter for Ozone Concentrations
30
25 -
20 -
Overall- 1990 to 2005
DMackville, KY-2006
D Rocky Mtn, CO - 2006
First
Quarter
Second
Quarter
Third
Quarter
Fourth
Quarter
CASTNET Annual Report - 2006
46
Chapter 5: Data Quality
-------
Laboratory Filter Concentrations
Accuracy of laboratory measurements is assessed through the analysis of reference samples and
continuing calibration verification (CCV) samples. Reference samples and CCV are procured
from independent suppliers and are National Institute of Standards and Technology (NIST)
traceable. Reference samples are analyzed at the beginning and end of each analytical batch to
verify the accuracy and stability of the calibration curve. The target value of the CCV solution is
set to the midrange of the calibration curve. In 2006, the CCV were analyzed every tenth sample
to verify that instrument calibration had not drifted beyond established limits. Table 5-4 presents
the percent recoveries and standard deviations for reference samples and CCV relative to target
concentrations. The table shows that the DQI goals (see Table 5-1) were met in 2006. Table 5-4
also lists the precision results that were shown in Figure 5-3.
1
, Filter Pack QC Summary for 2(
Reference
Sample1 Recovery
tH
P-H
Teflonฎ
Nylon
Cellulose
Parameter
so2;
NO;
NH+4
Ca2+
Mg2+
Na+
K+
cr
so2;
NO;
so2;
c
98.50
101.81
100.71
103.02
101.61
94.43
100.79
100.97
101.01
99.95
101.46
>
Q
GO
1.67
1.07
1.73
2.73
1.85
1.69
2.44
1.39
1.45
1.46
0.59
on
"S
O
O
506
Continuing Calibration
Verification Samples
c
155 99.74
155 99.10
153 99.48
194 100.72
194 99.96
194 100.23
194 100.50
155 99.25
144 99.90
144 99.53
182 99.16
(%R)
>
Q
GO
1.21
1.21
1.73
1.10
0.74
1.00
0.98
2.41
1.99
1.96
0.80
on
"S
O
O
In-Run Replicate2
c
781 0.48
781 1.21
751 0.58
797 1.58
797 2.48
797 2.38
797 3.40
781 1.17
730 2.12
730 0.52
740 3.75
(RPD)
>
Q
GO
0.57
1.48
0.63
2.34
2.95
4.51
3.29
1.48
2.82
0.88
5.87
on
"S
O
O
322
322
266
324
324
324
324
322
305
306
257
Note: % R = percent recovery
RPD = relative percent difference
1 Results of reference sample analyses provide accuracy estimates
2 Results of replicate analyses provide precision estimates
3 Number of QC Samples
47
-------
Continuous Measurements
Table 5-5 presents field accuracy results for 2006 based on instrument challenges performed
using independent reference standards during site calibration visits. CASTNET sites were
calibrated every six months with NIST-traceable standards. The calibration results were
evaluated using the accuracy criteria listed in Table 5-3. Each parameter was within its criterion
with at least 90 percent frequency with the exception of high (> 85 percent) relative humidity at
72.8 percent, solar radiation at 88.1 percent, wind direction north at 88.0 percent, and wind
direction south at 88.9 percent. However, these results did not adversely affect data collection
because data are not considered invalid unless criteria are exceeded by more than their own
magnitude. Using the two times standard, the four parameters ranged from 92.6 percent to 98.0
percent frequency.
; ', Accuracy Results for 2006 Field Measurements
umeter
Temperature (0ฐC)
Temperature (ambient)
Delta Temperature (0ฐC)
Delta Temperature (ambient)
*Relative Humidity > 85%
Relative Humidity < 50%
* Solar Radiation
*Wind Direction North
*Wind Direction South
Wind Speed < 5 m/s
Wind Speed > 5 m/s
Precipitation
Wetness (w/in 0.5 volts)
Ozone Slope
Ozone Intercept
Flow Rate
Criterion
99.0 percent
98.1 percent
100.0 percent
97.1 percent
72.8 percent
94.3 percent
88.1 percent
88.0 percent
88.9 percent
100.0 percent
95.3 percent
99.1 percent
100.0 percent
96.8 percent
100.0 percent
97.1 percent
Note: ฐC = degrees Celsius.
m/s = meters per second.
* Per CASTNET project protocols, data are flagged as "suspect" (S) but still considered valid if the calibration criterion is not
exceeded by more than its magnitude (i.e., if within 2x the criterion). The percent within 2x criterion for these parameters ranged
from 92.6 percent to 98 percent.
48
-------
Completeness
Completeness is defined as the percentage of valid data points obtained from a measurement
system relative to total possible data points. The CASTNET measurement criterion for
completeness requires a minimum completeness of 90 percent for every measurement for each
quarter. In addition, data aggregation procedures require approximately 70 percent completeness
for hourly fluxes and weekly concentrations/fluxes. Figure 5-5 presents historical and 2006
completeness data for all sites for measured filter concentrations, continuous measurements, and
calculated parameters. The figure shows that the 2006 direct measurements met the 90 percent
goal. The 2006 results show that data completeness exceeded 95 percent for six continuous
measurements, including filter pack flow. The four parameters derived from model results
exceeded 83 percent completeness for 2006. Completeness results for 2006 are better than
historical results for all parameters except sigma theta and ozone.
Figure 5-5 Historical and 2006 Percent Completeness of Measurements and Modeled
Estimates (black bars are 1990-2005)
Atmospheric Concentrations
Vector Wind Speed
Scalar Wind Speed
Wind Direction
Sigma Theta
Relative Humidity
Solar Radiation
Meteorological Precipitation
Parameters
Ambient Temperature
Delta Temperature
Ozone
Filter Pack Flow
Surface Wetness
Hourly Flux Estimates
Model Annual Mean Atm. Concentrations
Results Annual Mean Deposition Velocities
Annually Aggregated Flux Estimates
6
i
i,
i
i
i
"3
p
i
i
.
I ^ | DQI Measurement Criterion
i
i
i
1
~*
i
^^
i
i
i
i
5 70 75 80 85 90 95 100
Percent Completeness
CASTNET Annual Report - 2006
Chapter 5: Data Quality
-------
Laboratory Intercomparison Studies
The MACTEC laboratory is one of eight laboratories that participate in the U.S. Geological
Survey (USGS) interlaboratory comparison program. The laboratory receives four samples for
chemical analysis from USGS every two weeks. The samples are a mix of 44 synthetically
prepared samples, 8 deionized water samples, and 52 natural wet deposition samples. MACTEC
reported the eight CASTNET parameters for 104 samples during 2006. Results for only the 44
synthetically prepared samples are depicted in the figure below as the absolute percent difference
of the MACTEC value from the median value for all laboratories.
Results from Intercomparison of 44 Synthetic Samples
1005
995,
60,
50
0) 30
o
1 11'
ฃ 10,
ฐ 9
| 8
0) 7
Q. '
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3
2
1
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m
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M
n
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L
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r A o
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\
ni
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i *'
*
i
^
iA
*^B
??
"A"
/
i i
cฐ *,
5^1
,
s ;A<
1000
_
A
-
A
l
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>4*
?
n *
H
n A
s A
0
!S
^Aw*i
!
v* 8
A
v"
W wl" i ^t" "?S5>i*^^
o&Aซ**ฅ ซ> v* W ป
* ****- f ***^* A
oS|^^p**JortJ
Tffฑw 1 ~ _A^A
Tซ* ' -TT^^iiA
,
OCa
Cl
KK
A"Mg
ANa
-NH4
ON03
4S04
) 5 10 15 20 25 30 35 40 ' 45
Synthetic Sample Number
As shown above, a single sodium result was very high. Internal investigation led to the
conclusion that this sample had been contaminated. The probable timing and mechanism for the
contamination event are indeterminate. The results for the eight ultra-pure deionized water
samples analyzed during the year were all below the laboratory reporting limits for
every parameter.
Additionally, precision results for the 52 natural wet deposition samples were reported as
absolute percent differences for replicate analyses. By parameter, less than 4 percent of
approximately 208 paired natural wet deposition sample data points exceeded 10 percent
difference. These results are presented in the USGS report (USGS, 2006).
MACTEC generally participates in two to three studies by the National Water Research Institute
(NWRI) of Canada's Proficiency Testing QA Program each year in addition to interlaboratory
comparison studies for the USGS. MACTEC's laboratory was rated free of systemic bias for all
eight parameters for the three NWRI 2006 studies. MACTEC was ranked number six out of 37
participating laboratories at the end of 2006 (Environment Canada, 2006).
CASTNET Annual Report - 2006
50
Chapter 5: Data Quality
-------
Conclusion
DQI results demonstrate that field and laboratory processes were adequately monitored through
QA/QC procedures and were generally free of systemic bias during 2006. Accuracy data met the
established criteria for field and laboratory parameters with the exception of relative humidity
> 85 percent, solar radiation, wind direction north, and wind direction south. However, since the
criterion was exceeded by a value less than its own magnitude, the associated continuous data
collected are considered valid.
Precision data for sulfur constituents, HNO3, and ammonium are considered acceptable.
Precision data for nitrate analyses of collocated field samples have not met the established
criterion due, most likely, to the low concentrations generally measured and the unpredictable
nature of the gas-particle equilibrium of the nitrate species.
Precision data for ozone concentrations measured at ROM406/206 did not meet the 10 percent
goal during the first quarter because of unusually low levels. MARPD was not calculated for
MCK131/231 fourth quarter ozone data because the analyzer at MCK131 exhibited significant
drift that began near the end of October. Results for other quarters are considered acceptable.
Completeness criteria were met for all parameters in 2006. Completeness results for 2006 were
generally better than historical results.
Rocky Mountain National Park, CO (ROM406/206)
CASTNET Annual Report - 2006
Chapter 5: Data Quality
-------
References
Ames, R.B. and Malm, W.C. 2001. Comparison of Sulfate and Nitrate Particle Mass
Concentrations Measured by IMPROVE and the CDN. Atmospheric Environment.
Vol. 35(5)905-916.
Environment Canada. 2006. Water Science and Technology Directorate. Proficiency Testing
Program. Rain and Soft Waters PT Studies 0087, 0088, and 0089.
http://www.nwri.ca/nlet-lnee/ptp-pec/prof-e.html (accessed November 1, 2007).
Finkelstein, P.L., Ellestad, T.G., Clarke, J.F., Meyers, T.P., Schwede, D.B., Hebert, E.G., and
Neal, J.A. 2000. Ozone and Sulfur Dioxide Dry Deposition to Forests: Observations and
Model Evaluation. J. Geophys. Res. 105:D12:15,365-15,377.
Lavery, T.F., Rogers, C.M., Baumgardner, R., and Mishoe, K.P. 2007 (in press).
Intercomparison of CASTNET NO"3 and FDSTO3 Measurements with Data from Other
Monitoring Programs. Journal of Air & Waste Management Association (JAWMA).
Long Term Ecological Research (LTER) Program. 2004a. Coweeta LTER - CWT.
http://www.lternet.edu/sites/cwt/ (accessed June 5, 2007).
Long Term Ecological Research (LTER) Program. 2004b. Hubbard Brook LTER - HER.
http://www.lternet.edu/sites/cwt/ (accessed June 5, 2007).
Long Term Ecological Research (LTER) Program. 2004c. Konza Prairie LTER - KNZ.
http://www.lternet.edu/sites/knz/ (access June 5, 2007).
MACTEC Engineering and Consulting, Inc. (MACTEC). 2007a. Clean Air Status and Trends
Network (CASTNET) Fourth Quarter 2006 Data Report. Prepared for U. S.
Environmental Protection Agency (EPA), Office of Air and Radiation, Clean Air Markets
Division, Washington, D.C. Contract No. 68-D-03-052. Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2007b. Clean Air Status and Trends
Network (CASTNET): Fourth Quarter 2006 Quality Assurance Report with 2006 Annual
Summary. Prepared for U.S. Environmental Protection Agency (EPA), Office of Air and
Radiation, Clean Air Markets Division, Washington, D.C. Contract No. 68-D-03-052.,
Gainesville, FL.
CASTNET Annual Report - 2006 R-l References
-------
References (continued)
MACTEC Engineering and Consulting, Inc. (MACTEC). 2007c. Clean Air Status and Trends
Network (CASTNET) Third Quarter 2006Data Report. Prepared for U.S. Environmental
Protection Agency (EPA), Office of Air and Radiation, Clean Air Markets Division,
Washington, D.C. Contract No. 68-D-03-052., Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2006a. Clean Air Status and Trends
Network (CASTNET) 2005 Annual Report. Prepared for U.S. Environmental Protection
Agency (EPA), Office of Air and Radiation, Clean Air Markets Division, Washington,
D.C. Contract No. 68-D-03-052. Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2006b. Clean Air Status and Trends
Network (CASTNET) First Quarter 2006Data Report. Prepared for U.S. Environmental
Protection Agency (EPA), Office of Air and Radiation, Clean Air Markets Division,
Washington, D.C. Contract No. 68-D-03-052. Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2006c. Clean Air Status and Trends
Network (CASTNET) First Quarter 2006 Quality Assurance Report. Prepared for U. S.
Environmental Protection Agency (EPA), Office of Air and Radiation, Clean Air Markets
Division, Washington, D.C. Contract No. 68-D-03-052. Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2006d. Clean Air Status and Trends
Network (CASTNET) Second Quarter 2006 Data Report. Prepared for U. S.
Environmental Protection Agency (EPA), Office of Air and Radiation, Clean Air Markets
Division, Washington, D.C. Contract No. 68-D-03-052. Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2006e. Clean Air Status and Trends
Network (CASTNET) Second Quarter 2006 Quality Assurance Report. Prepared for U. S.
Environmental Protection Agency (EPA), Office of Air and Radiation, Clean Air Markets
Division, Washington, D.C. Contract No. 68-D-03-052. Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2006f. Clean Air Status and Trends
Network (CASTNET) Third Quarter 2006 Quality Assurance Report. Prepared for U. S.
Environmental Protection Agency (EPA), Office of Air and Radiation, Clean Air Markets
Division, Washington, D.C. Contract No. 68-D-03-052. Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2005. Clean Air Status and Trends
Network (CASTNET) Quality Assurance Project Plan (QAPP), Revision 3.0. Prepared
for U.S. Environmental Protection Agency (EPA), Research Triangle Park, NC, Contract
No. 68-D-98-112. Gainesville, FL.
CASTNET Annual Report - R-2 References
-------
References (continued)
MACTEC Engineering and Consulting, Inc. (MACTEC). 2004. Clean Air Status and Trends
Network (CASTNET) 2002 Quality Assurance Report. Prepared for U. S. Environmental
Protection Agency (EPA), Research Triangle Park, NC, Contract No. 68-D-03-052.
Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2003. Clean Air Status and Trends
Network (CASTNET) 2002 Annual Report. Prepared for U.S. Environmental Protection
Agency (EPA), Research Triangle Park, NC, Contract No. 68-D-03-052. Gainesville, FL.
Meyers, T. P., Finkelstein, P., Clarke, 1, Ellestad, T.G., and Sims, P.F. 1998. A Multilayer
Model for Inferring Dry Deposition Using Standard Meteorological Measurements.
J. Geophys.Res. 103017:22,645-22,661.
National Atmospheric Deposition Program, 2003. National Atmospheric Deposition Program
2002 Annual Summary. NADP Data Report 2003-01. Illinois State Water Survey,
Champaign, IL.
National Park Service (NPS). 2007. Air Quality Monitoring & Access to Data. NFS Air
Quality Monitoring. http://www2.nature.nps.gov/air/Monitoring/ (accessed June 5,
2007).
National Science Foundation (NSF). 2005. Translating Science for Society: Broader Impacts of
NSF's Long-Term Ecological Research Program, http://intranet.lternet.edu/archives/
documents/ Publications/brochures/nsf0533.pdf (accessed June 5, 2007).
New Mexico Environment Department. 2007. Four Corners Air Quality Task Force.
http://www.nmenv.state.nm.us/aqb/4C/ (accessed June 1, 2007).
Schwede, D.B. 2006. A Comparison of the Deposition Velocity Estimates from the CASTNET
and CAPMoNNetworks. (Working paper). Research Triangle Park, NC.
Sweet, C., Caughey, M., and Gay, D. 2005. Midwest Ammonia Monitoring Project, Summary
for October 2003 through November 2004. http://www.ladco.org/reports/rpo/
MWRPOprojects/Monitoring/YearOneReport(Final).pdf (accessed November 5, 2007).
U.S. Environmental Protection Agency (EPA). 2007a. 8-Hour Ground-level Ozone
Designations, http://www.epa.gov/ozonedesignations/(accessed March 1, 2007).
CASTNET Annual Report - R-3 References
-------
References (continued)
U.S. Environmental Protection Agency (EPA). 2007b. Clean Air Interstate Rule.
http://www.epa.gov/cair/index.html (accessed March 1, 2007).
U.S. Environmental Protection Agency (EPA). 2007c. Vegetation and Air Quality.
http://www.epa.gov/heatisland/strategies/!evel3_vegairquality.html (accessed
December 6, 2007).
U.S. Environmental Protection Agency (EPA). 2006. NOX Budget Trading Program. 2005
Program Compliance and Environmental Results. EPA430-R-06-013. September 2006.
U.S. Environmental Protection Agency (EPA). 2005a. Acid Rain Program 2004 Progress
Report. EPA430-R-05-012. October 2005.
U.S. Environmental Protection Agency (EPA). 2005b. Evaluating Ozone Control Programs in
the Eastern United States. EPA454-K-05-001. August 2005.
U.S. Environmental Protection Agency (EPA). 2000. National Air Quality and Emissions
Trends Report, 1998. EPA-454-R-00-003. OAQPS, RTF, NC 27711.
U.S. Environmental Protection Agency (EPA). 1998. Quality Assurance Requirements for State
and Local Air Monitoring Stations (SLAMS). 40 CFR 50, Appendix L.
U.S. Environmental Protection Agency (EPA). 1997. National Ambient Air Quality Standards
for Ozone. 40 CFR 50.
U.S. Geological Survey (USGS). 2006. Office of Water Quality. Branch of Quality Systems.
Interlaboratory Comparison Program http://bqs.usgs.gov/precip/new/frontpage_home.htm
(accessed November 1, 2007).
CASTNET Annual Report - R-4 References
-------
Appendix A
-------
A-l. Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
Start date
Latitude (ฐN)
Longitude (ฐW)
Elevation (m)
O>
$ = S
1 =1 I I
2 s ฐ & ฃ
i> 11 2 a
II li 1 1
Terrain
Representative to
the MLM3
s.
i
=
0
o.
to
Alabama
SND152
Sand Mountain
12/27/88
34.2894
85.9704
352
Agri.
Rolling
Y
EPA
Alaska
DEN417
Denali National Park
10/06/98
63.7258
148.9633
661
Forested
Complex
N
NPS
Arizona
CHA467
GRC474
PET427
Chiricahua National Monument
Grand Canyon National Park
Petrified Forest National Park
04/25/89
05/16/89
09/24/02
32.0092
36.0597
34.8225
109.3892
112.1822
109.8919
1570
2073
1723
0 Range
Forested
Desert
Complex
Complex
Flat
N
M
Y
NPS
NPS
NPS
Arkansas
CAD150
Caddo Valley
10/04/88
34.1792
93.0989
71
Forested
Rolling
N
EPA
California
CON186
DEV412
JOT403
LAV410
PIN414
SEK430
YOS404
Converse Station
Death Valley National Monument
Joshua Tree National Monument
Lassen Volcanic National Park
Pinnacles National Monument
Sequoia National Park
Yosemite National Park
06/17/03
02/21/95
02/16/95
07/25/95
05/16/95
04/07/05
09/25/95
34.1941
36.5092
34.0714
40.5403
36.4850
36.4894
37.7133
116.9130
116.8481
116.3906
121.5764
121.1556
118.8269
119.7061
1837
125
1244
1756
335
457
1605
Agri./Forested
Desert
Desert
Forested
Forested
Forested
Forested
Complex
Complex
Complex
Complex
Complex
Mountaintop
Complex
N
Y
M
M
M
N
N
EPA
NPS
NPS
NPS
NPS
NPS
NPS
CASTNET Annual Report -
Appendix A
-------
A-l. Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
Start date
Latitude (ฐN)
Longitude (ฐW)
1
o _ B5
O '-C 03 P
'5 '*>~ V 0
1 11 il
W 0 PH O ง
(K
_ P
0 "O
a a
'^ T
0 M
o ^
S a
01 -P
^ &
Terrain
Representative to
the MLM3
1
=
0
c.
to
Colorado
GTH161
MEV405
ROM206
ROM406
Gothic
Mesa Verde National Park
Rocky Mountain National Park
Rocky Mountain National Park
05/16/89
01/10/95
07/03/01
12/20/94
38.9573
37.1983
40.2778
40.2778
106.9854
108.4903
105.5453
105.5453
2926
2165
2743
2743
0 Range
Forested
Forested
Forested
Complex
Complex
Complex
Complex
N
M
M
M
EPA
NPS
EPA
NPS
Connecticut
ABT147
Abington
12/28/93
41.8402
72.0111
209
0 Urban-Agri.
Rolling
M
EPA
Florida
EVE419
IRL141
SUM156
Everglades National Park
Indian River Lagoon
Sumatra
10/06/98
07/09/01
12/28/88
25.3911
30.1065
30.1065
80.6806
80.4554
84.9938
2
2
14
Swamp
Beach
0 Forested
Flat
Flat
Flat
Y
Y
Y
NPS
EPA
EPA
Georgia
GAS153
Georgia Station
06/28/88
33.1812
84.4100
270
Agri.
Rolling
M
EPA
Illinois
ALH157
BVL130
STK138
Alhambra
Bondville
Stockton
06/28/88
02/09/88
12/28/93
38.8690
40.0520
42.2872
89.6229
88.3725
89.9998
164
212
274
0 Agri.
Agri.
Agri.
Flat
Flat
Rolling
Y
Y
M
EPA
EPA
EPA
CASTNET Annual Report -
Appendix A
-------
A-l. Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
ฃ
03
a
ฃ
03
-t^
to
ฃ
a
3
3
0^
o>
a
s
a
5
s-*,
=
_O
03
ฃ
3
!. J
2 a ฃ
1 ll 1 fc-
S-* s ง ฐ g
II II 1 1
=
'8
o
H
2
resentative
MLM3
ง o.
ซ 5
=
0
c.
to
Indiana
SAL133
VIN140
Salamonie Reservoir
Vincennes
06/28/88
08/04/87
40.8164
38.7406
85.6608
87.4844
250
134
Agri.
Agri.
Flat
Rolling
Y
M
EPA
EPA
Kansas
KNZ184
Konza Prairie
03/26/02
39.1021
96.6096
348
Prairie
Flat
Y
EPA
Kentucky
CDZ171
CKT136
MAC426
MCK131
Cadiz
Crockett
Mammoth Cave National Park
Mackville
10/01/93
08/24/93
07/24/02
07/31/90
36.7841
37.9211
37.1319
37.7044
87.8500
83.0658
86.1478
85.0483
189
455
243
353
Agri.
Agri.
Agri./Forested
Agri.
Rolling
Rolling
Rolling
Rolling
M
Y
M
M
EPA
EPA
NPS
EPA
Maine
ACA416
ASH135
HOW132
Acadia National Park
Ashland
Howland
12/01/98
12/20/88
11/24/92
44.3769
46.6039
45.2158
68.2608
68.4142
68.7085
158
235
69
Forested
Agri.
Forested
Complex
Flat
Rolling
M
Y
Y
NPS
EPA
EPA
Maryland
BEL116
BWR139
Beltsville
Blackwater National Wildlife Refuge
11/01/88
07/04/95
39.0283
38.4448
76.8175
76.1115
46
4
Urban-Agri.
Forest-Marsh
Flat
Coastal
N
M
EPA
EPA
CASTNET Annual Report -
Appendix A
-------
A-1. Locational and Operational Characteristics of CASTNET Sites
Site ID Site Name
/ \
z I
D S^ o>
I i I
^" *c fl
5 a q
;/)-]-]
Elevation (m)
o>
Silt!
i"^ a 8 0 ซ
II II 1 1
Terrain
Representative to
the MLM3
1
=
0
o.
to
Michigan
ANA115 Ann Arbor
HOX148 Hoxeyville
UVL124 Unionville
06/28/88 42.4164 83.9019
10/31/00 44.1809 85.7390
06/28/88 43.6139 83.3597
267
298
201
0 Forested
Forested
0 Agri.
Flat
Flat
Flat
M
Y
Y
EPA
EPA
EPA
Minnesota
VOY413 Voyageurs National Park
06/13/96 48.4128 92.8292
429
Forested
Rolling
M
NPS
Mississippi
CVL151 Coffeeville
12/27/88 34.0028 89.7989
134
Forested
Rolling
M
EPA
Montana
GLR468 Glacier National Park
12/27/88 48.5103 113.9956
976
Forested
Complex
N
NPS
Nebraska
SAN189 Santee Sioux
07/05/06 42.8292 97.8541
429
Agri.
Rolling
N
EPA
Nevada
GRB411 Great Basin National Park
05/16/95 39.0053 114.2158
2060
Forested
Complex
M
NPS
New Hampshire
WST109 Woodstock
12/27/88 43.9446 71.7008
258
Forested
Complex
N
EPA
New Jersey
WSP144 Washington's Crossing
12/27/88 40.3133 74.8726
61
Urban -Agri.
Rolling
M
EPA
CASTNET Annual Report -
A J
r\!
Appendix A
-------
A-1. Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
Start date
Latitude (ฐN)
Longitude (ฐW)
Elevation (m)
O)
fe M^ *n a
1-^ a | 0 1
Q &
-------
A-l. Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
ฃ
03
a
ฃ
03
-t^
to
ฃ
a
3
3
0^
o>
a
s
a
5
s-*,
=
_O
03
ฃ
3
!. J
2 a ฃ
1 ll 1 fc-
S-* s ง ฐ g
II II 1 1
=
'8
o
H
2
resentative
MLM3
ง o.
ป 5
=
0
c.
to
Pennsylvania
ARE128
KEF112
LRL117
MKG113
PSU106
Arendtsville
Kane Experimental Forest
Laurel Hill State Park
M.K. Goddard State Park
Penn. State University
06/28/88
01/03/89
12/15/87
01/12/88
01/06/87
39.9231
41.5981
39.9883
41.4250
40.7209
77.3078
78.7683
79.2522
80.1447
77.9316
269
622
615
384
376
0 Agri.
Forested
Forested
Forested
Agri.
Rolling
Rolling
Complex
Rolling
Rolling
M
Y
N
N
M
EPA
EPA
EPA
EPA
EPA
South Dakota
WNC429
Wind Cave National Park
11/18/03
43.5578
103.4839
1292
Prairie
Rolling
M
NPS
Tennessee
ESP127
GRS420
SPD111
Edgar Evins State Park
Great Smoky Mountains National Park
Speedwell
03/22/88
10/06/98
06/12/89
36.0389
35.6331
36.4698
85.7330
83.9422
83.8265
302
793
361
Forested
Forested
0 Agri.
Rolling
Complex
Rolling
N
N
Y
EPA
NPS
EPA
Texas
ALC188
BBE401
Alabama-Coushatta
Big Bend National Park
04/02/04
07/18/95
30.4210
29.3022
94.4045
103.1772
101
1052
Forested
Forested
Rolling
Complex
Y
M
EPA
NPS
Utah
CAN407
Canyonlands National Park
01/24/95
38.4586
109.8211
1809
Desert
Complex
M
NPS
Vermont
LYE145
Lye Brook
03/30/94
43.0510
73.0613
730
ซ5 0 Forested
Mountaintop
N
EPA
CASTNET Annual Report -
Appendix A
-------
A-l. Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
ฃ
03
a
ฃ
03
-t^
to
ฃ
a
3
3
0^
o>
a
s
a
5
s-*,
=
_O
03
ฃ
3
!. J
2 a ฃ
1 ll 1 fc-
S-* S S ฐ g
II II 1 1
=
'8
o
H
2
resentative
MLM3
ง o.
ซ 5
=
0
c.
to
Virginia
PED108
SHN418
VPI120
Prince Edward
Shenandoah National Park
Morton Station
11/03/87
06/28/88
06/02/87
37.1653
38.5231
37.3300
78.3070
78.4347
80.5573
150
1073
920
0 Forested
Forested
Forested
Rolling
Mountaintop
Mountaintop
M
M
N
EPA
NPS
EPA
Washington
MOR409
NCS415
Mount Rainier National Park
North Cascades National Park
08/29/95
02/14/96
46.7583
48.5397
122.1244
121.4472
415
109
Forested
Forested
Complex
Complex
N
M
NPS
NPS
West Virginia
CDR119
PAR107
Cedar Creek State Park
Parsons
11/10/87
01/19/88
38.8794
39.0906
80.8478
79.6614
234
510
0 Forested
Forested
Complex
Complex
N
N
EPA
EPA
Wisconsin
PRK134
Perkinstown
09/27/88
45.2066
90.5972
472
0 Agri.
Rolling
M
EPA
Wyoming
CNT169
PND165
YEL408
Centennial
Pinedale
Yellowstone National Park
08/19/91
12/27/88
06/26/96
41.3722
42.9214
44.5597
106.2422
109.7900
110.4006
3178
2388
2400
Range
Range
Forested
Complex
Rolling
Rolling
M
M
N
EPA
EPA
NPS
CASTNET Annual Report -
Appendix A
-------
1 . The dry deposition filters are analyzed for the following constituents!
Teflonฎ
Nylon
Cellulose
SO2, N03, NH*4,Cr, K+, Na+, Mg2*, Ca2*
SO2, NO; (reported as HNO3)
SO2 (reported as SO2)
2. Meteorological sensors: temperature, delta temperature, relative humidity, solar radiation,
vector wind speed, scalar wind speed, wind direction, sigma theta, surface wetness, and
precipitation via tipping bucket rain gauge.
3. N = No; Y = Yes; M = Marginal.
4. O3 not measured.
5. Solar-powered sites.
6. Composite filter pack, day filter pack, and night filter pack.
CASTNET Annual Report -
Indicates current monitoring.
0 Indicates discontinued monitoring.
Measurements were discontinued at the various sites because of several reasons
including:
(1) rotate limited number of instruments;
(2) redundant measurements (e.g., with IMPROVE and NADP/NTN); and
(3) funding limitations.
100 and 200 series = EPA - Operated Sites
400 series = NPS - Operated Sites
Appendix A
-------
Appendix B
-------
AGL above ground level
ARP Acid Rain Program
BLM Bureau of Land Management
ฐC degrees Celsius
Ca2+ particulate calcium ion
CAAA Clean Air Act Amendments
CaCO3 calcium carbonate
CAIR Clean Air Interstate Rule
Ca(NO3)2 calcium nitrate
CAPMoN Canadian Air and Precipitation Monitoring Network
CASTNET Clean Air Status and Trends Network
CCV continuing calibration verification samples
Cl" particulate chloride ion
CLASS Chemical Laboratory Analysis and Scheduling System
CO carbon monoxide
DQI data quality indicator
EPA U.S. Environmental Protection Agency
H2SO4 sulfuric acid
HNO3 nitric acid
HYSPLIT HYbrid Single-Particle Lagrangian Integrated Trajectory
IMPROVE Interagency Monitoring of Protected Visual Environments
ITEC Inter-Tribal Environmental Council
K+ particulate potassium ion
K2CO3 potassium carbonate
kg/ha/yr kilograms per hectare per year
km kilometer
LAI leaf area index
LCS laboratory control sample
1pm liters per minute
LTER Long Term Ecological Research Program
m meter
MACTEC MACTEC Engineering and Consulting, Inc.
MARPD mean absolute relative percent difference
Mg2+ particulate magnesium ion
mg/1 milligrams per liter
MLM Multi-Layer Model
mm millimeter
MSA Metropolitan Statistical Area
N nitrogen
N2 nitrogen gas in atmosphere
-------
List of Acronyms and Abbreviations (continued)
Na+
NAAQS
NaCl
NADP/NTN
NADP/MDN
NaNO3
NAPAP
NERL
NDDN
NH3
NH;
NH4NO3
(NH4)2S04
NIST
NO
NO2
NO3
NOX
NOAA
NFS
NSF
NWRI
02
03
OH
ORD
OTC
ppb
ppm
QA
QAPP
QC
S
SIP
SLAMS
SO2
so2;
total NO3
Hg/m3
particulate sodium ion
National Ambient Air Quality Standards
sodium chloride
National Atmospheric Deposition Program/National Trends Network
National Atmospheric Deposition Program/Mercury Deposition Network
sodium nitrate
National Acid Precipitation Assessment Program
National Exposure Research Laboratory
National Dry Deposition Network
ammonia
particulate ammonium
ammonium nitrate
ammonium sulfate
National Institute of Standards and Technology
nitric oxide
nitrogen dioxide
particulate nitrate
nitrogen oxides [nitric oxide (NO) + nitrogen dioxide (NO2)]
National Oceanic and Atmospheric Administration
National Park Service
National Science Foundation
Environment Canada's National Water Research Institute
oxygen gas in atmosphere
ozone
hydroxyl
EPA's Office of Research and Development
Ozone Transport Commission
parts per billion
parts per million
quality assurance
Quality Assurance Project Plan
quality control
sulfur
State Implementation Plan
State and Local Monitoring Stations
sulfur dioxide
particulate sulfate
gaseous nitric acid (HNO3) + particulate nitrate (NO3)
micrograms per cubic meter
CASINE! Annual Report - 2006
B-2
Appendix I
-------
List of Acronyms and Abbreviations (continued)
|im micrometer
USGS U.S. Geological Survey
Vd deposition velocity
VOC volatile organic compounds
CASTNET Annual Report - p^ Appendix B
-------
For More Information
U.S. Environmental Protection Agency
Office of Air and Radiation
Clean Air Markets Division
Washington, D.C.
On the Web:
CASTNET Home Page: Clean Air Markets EPA Home Page:
Division Home Page:
www.epa.gov/castnet www.epa.gov/airmarkets www.epa.gov
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