A
Site not pictured:
DEN417. AK 68
Fourth Highest Daily Maximum 8-Hour Ozone Concentrations (ppb) for 2008
Clean Air Status and Trends
Network (CASTNET)
2008 Annual Report
120
&100
80
60
Trend in Fourth Highest Daily Maximum 8-Hour Average Ozone Concentrations (ppb) - Eastern United States
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Clean Air Status and Trends Network
(CASTNET)
2008 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.
EPA Contract No. EP-W-09-028
February 2010
-------
Table of Contents
Executive Summary ii
Chapter I CASTNET Overview I
Background I
Cooperating Networks 3
Locations of Monitoring Sites 4
CASTNET Reference Sites 5
Measurements Collected at CASTNET Sites 6
Delivery of CASTNET Ozone Measurements to the EPA Air Quality System 7
Calculating Dry Deposition 8
Sulfur Dioxide and Nitrogen Oxides Emissions 9
2008 Significant Events 12
Chapter 2 Atmospheric Concentrations 13
Sulfur Dioxide I 3
Ammonia Monitoring Network (AMoN) 15
Particulate Sulfate 17
Total Nitrate 18
Particulate Ammonium 19
Trends in Air Quality at CASTNET Western Reference Sites 2 /
Chapter 3 Atmospheric Deposition 22
Sulfur Deposition 23
Using CASTNET Data to Assess Quantity of Atmospheric Deposition Compared with Critical Loads... 27
Nitrogen Deposition 29
Uncertainties in NO] and HN03 Concentrations and Their Effect on Dry Nitrogen Deposition 32
Chapter 4 Ozone Concentrations 34
National Ambient Air Quality Standards for Ozone 35
Eight-Hour Ozone Concentrations 35
Impacts ofNOx Budget Program and Clean Air Interstate Rule on Rural and Urban Ozone
Levels in the Eastern United States 39
Nitrogen Oxides and Ozone 41
Ozone Episode in the Great Smoky Mountains, TN (GRS420) in July 2008 44
Chapter 5 Data Quality 47
Precision 47
Accuracy 54
Completeness 56
Interlaboratory Comparison Results 58
Summary of Data Quality Results 59
References
Appendix A Locational and Operational Characteristics of CASTNET Sites
Appendix B Acronyms and Abbreviations
CASTNET Annual Report - 2008
Table of Contents
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Executive Summary
This report summarizes Clean Air Status and Trends Network (CASTNET) data collected
during 2008 and examines trends in air quality since 1990. The report presents maps of the
geographic distribution of pollutants measured in 2008. The report also discusses significant
network events and presents an analysis of data quality. CASTNET began collecting
measurements in 1991 with the incorporation of 50 sites from the National Dry Deposition
Network, which had been in operation 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.
Key Results through 2008
* The air quality, as represented by CASTNET pollutant measurements, was the best in
the history of the network.
* Mean annual sulfur dioxide and particulate sulfate concentrations declined significantly in
the eastern United States over the 19-year period 1990 through 2008. Sulfur dioxide
levels declined 48 percent while sulfate concentrations declined 26 percent.
* Total (dry + wet) sulfur deposition declined by 38 percent from 1990 through 2008.
* Mean annual concentrations of total nitrate (nitric acid plus particulate nitrate) declined
25 percent in the eastern United States over the 19-year period.
* Total nitrogen deposition declined by 19 percent from 1990 through 2008.
* Ozone levels measured at CASTNET sites in 2008 continue to show a downward trend
that began after a peak in 2002. The mean fourth highest daily maximum 8-hour average
ozone concentration (69 ppb) for 2008 was the lowest in the history of the network.
Only two eastern and four California sites recorded exceedances of the 8-hour
standard of 0.08 ppm during the most recent 3-year period (2006-2008). During 2008,
no eastern site recorded a fourth highest daily maximum 8-hour ozone concentration
above 85 ppb. The recent declines in rural ozone and nitrate levels have been attributed
to the documented decline in nitrogen oxide emissions in the eastern United States.
* Measurements taken during 2008 and historical data collected over the period
1990-2007 were analyzed relative to data quality objectives and their associated
metrics. These analyses demonstrate that CASTNET data can be used with confidence
and that CASTNET continues to produce information of the highest quality.
CASTNET Annual Report-2008 ~ ii ~ Executive Summary
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Chapter I: CASTNET Overview
CASTNET is a national air quality monitoring network designed to provide data to
assess trends in air quality, atmospheric deposition, and ecological effects due to
changes in air pollutant emissions. CASTNET began operation in 1991 to provide
long-term monitoring of air quality in rural areas and to determine trends in
regional atmospheric nitrogen, sulfur, and ozone concentrations and deposition
fluxes of sulfur and nitrogen pollutants. CASTNET was preceded by the National
Dry Deposition Network, which began in 1987. The primary sponsors of
CASTNET are the Environmental Protection Agency and the National Park
Service. As of December 2008, the network operated 84 monitoring stations
throughout the contiguous United States, Alaska, and Canada. Air quality
measurements collected in 2008 show the continuing decline in pollution levels
throughout the network. Mean annual sulfur dioxide concentrations and mean
fourth highest daily maximum 8-hour average ozone concentrations were the
lowest in the history of CASTNET.
Background
The U.S. Congress, under a provision in the 1990 Clean Air Act Amendments (CAAA),
directed the Environmental Protection Agency (EPA) to establish the Clean Air Status and
Trends Network (CASTNET) to assess the effectiveness of the Acid Rain Program (ARP),
which was promulgated to reduce emissions of sulfur dioxide (SO2) and nitrogen oxides (NOX)
from electric generating units (EGUs). Congress recognized the need to assess and track real-
world environmental results as the ARP was implemented, and emission reductions became
effective. Congress mandated that CASTNET provide consistent, long-term measurements for
determining relationships between changes in emissions and any subsequent changes in air
quality, atmospheric deposition, and ecological effects.
The ARP has produced significant reductions in SO2 and NOX emissions from EGUs 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 (1999-2002) and the NOX State Implementation Plan (SIP)
Call/NOx Budget Trading Program (NBP), which operated from 2003 through 2008. The NBP
placed a cap on total NOX emissions from EGUs in the eastern United States during the ozone
season (May I through September 30) when the potential for ozone formation is high. The
Clean Air Interstate Rule (CAIR), which was issued in March 2005, aimed to permanently lower
SO2 and NOX emissions in the eastern United States. CAIR, as promulgated, established three
compliance programs: an annual NOX program, an ozone season NOX program, and an annual
CASTNET Annual Report - 2008 ~ / ~ Chapter I: CASTNET Overview
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SO2 program. Although CAIR was remanded back to EPA in 2008, these programs remain in
effect while EPA works to develop a replacement rule. The first phase of the annual and ozone
season NOX requirements began in 2009. The SO2 requirements will begin in 2010. EPA relies
on CASTNET and other long-term monitoring networks to provide the air quality
measurements used to assess the effectiveness of emission control programs.
CASTNET started as the National Dry Deposition Network (NDDN), which began operation
in 1987. The 50 NDDN sites were transferred to CASTNET in 1991. The network, as of
December 2008, included 84 monitoring stations at 82 site locations throughout the contiguous
United States, Alaska, and Canada. CASTNET is sponsored by EPA and the National Park
Service (NPS). NPS began its participation in CASTNET in 1994 under an agreement with EPA.
With the participation of NPS, the network became a national, rather than a primarily eastern,
network. 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 2008 numbered 25. Additional information on the NPS Air Monitoring program can
be found on the Web site: http://www.nature.nps.gov/air/monitoring/.
CASTNET stations measure rural, regionally representative concentrations of sulfur and
nitrogen pollutants and ozone in order to detect and quantify trends, define the geographic
distribution of rural pollutants, and estimate dry deposition of pollutants. Dry deposition is
calculated from CASTNET concentration measurements and modeled deposition velocities
using the Multi-Layer Model (MLM). The model requires several meteorological parameters and
information on vegetation and land use specific to each site. CASTNET data are also used for
atmospheric model evaluation, e.g., the Community Multiscale Air Quality (CMAQ) modeling
system, and to provide input to ecological models.
This report summarizes CASTNET/NDDN monitoring activities and the resulting
concentration and deposition data collected over the 19-year period from 1990 through
2008. 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 "Download Data" link on EPA's CASTNET Web page.
The Web site provides a complete archive of concentration and deposition data for all EPA and
NPS-sponsored CASTNET sites. Fully validated data are available approximately 10 months
following collection. NPS data collected during 2008 from the NPS-sponsored CASTNET sites
and the NPS Gaseous Pollutant Monitoring Program are available in the NPS 2008 Annual Data
Summary Report (Ray, 2009) and the NPS 2008 Data Quality Assurance Report (ARS, 2009).
CASTNET Annual Report - 2008 ~ 2 ~ Chapter I: CASTNET Overview
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Cooperating Networks
In addition to EPA and NFS, the principal sponsors, CASTNET monitors air quality and
deposition in cooperation with other national networks.
* National Atmospheric Deposition Program (NADP) operates the National
Trends Network (NTN), which includes 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. NADP operates the Mercury Deposition
Network (MDN), which operates samplers to measure mercury in precipitation.
MDN samplers are operated at several CASTNET sites. Additionally, NADP operates
the Ammonia Monitoring Network (AMoN), which operates triplicate passive
ammonia (NH3) samplers at about 20 NTN locations. AMoN has been operating for
two years as a NADP initiative. AMoN provides information on 2-week average NH3
concentrations. Additional information on NADP can be found on its Web site:
http://nadp.sws.uiuc.edu/.
* Canadian Air and Precipitation Monitoring Network (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.
* Interagency Monitoring of Protected Visual Environments (IMPROVE)
measures aerosol pollutants near more than 30 CASTNET sites. IMPROVE measures
particulate air pollutants that affect visibility.
EPA relies on CASTNET and these other long-term national networks to generate the data
needed to assess the effectiveness of promulgated 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.
Although EPA and NPS are the primary sponsors of CASTNET, other organizations, Native
American tribes, universities, and government agencies play a role in sponsoring individual
CASTNET sites. These co-sponsors provide in-kind services that support the overall operation
of a site, including site operation, land use, or both. All of the sites added during recent
expansion of the network (since 2001) have an associated co-sponsor. Three CASTNET
monitoring sites are located on tribal lands: Cherokee Nation in eastern Oklahoma (CHE185),
CASTNET Annual Report - 2008 ~ 3 ~ Chapter I: CASTNET Overview
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Alabama-Coushatta in eastern Texas (ALC188), and Santee Sioux in northern Nebraska
(SAN 189). State agencies also operate special purpose air pollutant measurement devices at
some CASTNET sites.
Locations of Monitoring Sites
Figure l-l shows the locations of CASTNET monitoring sites as of December 2008. Eighty-four
sites were operational at 82 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 of each site by state and includes information on start date,
latitude, longitude, elevation, and the parameters measured. 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
(Ipm) in the east and at a higher rate of 3.0 Ipm in the west due to the lower pollutant
concentrations generally found in the western United States.
Figure l-l CASTNET Sites as of December 2008
ซ
EPA Sponsored
NPS Sponsored
* EPA Collocated Pair
NPS/EPA Collocated Pair
ioow
CASTNET Annual Report - 2008
Chapter I: CASTNET Overview
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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 eastern
reference sites (Figure I -2) 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. 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 to replace
missing or invalid data. Trends in pollutant
concentrations measured at CASTNET
western reference sites (Figure I -3) are also
presented. The 17 western reference sites
have been operating since at least 1996.
In chapters 2 through 4, the data from the
34 eastern reference sites were aggregated
and then presented using box plots for the
period 1990 through 2008. Data from the
17 western reference sites were aggregated
and then presented using box plots for the
period 1996 through 2008.
Figure 1-2 CASTNET Eastern Reference Sites
Eastern Reference Sites
Figure 1-3 CASTNET Western Reference Sites
* Western Reference Sites
CASTNET Annual Report - 2008
Chapter I: 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 to
model depositions over many years. Consequently,
measurement of weekly average (Tuesday to Tuesday)
concentrations was selected as the basic sampling
strategy. Over the course of the week, air is drawn at a
controlled flow rate through an open-face 3-stage filter
pack (Figure I -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 Teflon 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.
CASTNET Ambient
Measurements
Sulfur dioxide (SO2)
Particulate sulfate (SO24)
Particulate nitrate (NO3)
Nitric acid (HNO3)
Particulate ammonium (NH^)
Particulate calcium (Ca2+)
Particulate sodium (Na+)
Particulate magnesium (Mg2+)
Particulate potassium (K+)
Particulate chloride (Cl")
Ozone (O3)
Meteorological variables and
information on land use and
vegetation
Figure I -4 Three-Stage Filter Pack
Cellulose (2)
Gaseous
SO2
Nylon
Gaseous
HNO3 SO2
Teflonฎ
Particulate
so, NOS NH; K+
Ca2+-Mg2+-Na+-Cr
Quick Disconnect
Two
Cellulose Nylon
Filters Filter
Teflon*
Filter
Shipping Cap
(removed during sampling)
Teflon* Spacers
The filter packs are prepared, loaded, shipped, received, extracted, and analyzed at the
MACTEC Gainesville, FL laboratory. Following receipt from the field, exposed Teflon filters and
blanks are extracted and then analyzed for sulfate (SO24), nitrate (NO3), and concentrations of
chloride (Cl") by micromembrane-suppressed ion chromatography (1C). Teflon filter extracts
are also analyzed for ammonium (NH^) by the automated indephenol method with the
CASTNET Annual Report - 2008
Chapter I: CASTNET Overview
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Bran+Luebbe AutoAnalyzer 3. The Teflon filter extracts are additionally analyzed for calcium
(Ca2+), sodium (Na+), magnesium (Mg2+), and potassium (K+) by inductively coupled plasma-
atomic emission spectrometry (ICP-AES) using a Perkin Elmer Optima 3000 Dual View
spectrometer. The cellulose filter extracts are analyzed for SO2 as sulfate using 1C. In
November 2008, the analytical laboratory began using the Dionex AS22 analytical column/AG22
guard column for the impregnated cellulose filter analyses. The nylon filter extracts are analyzed
via 1C for nitric acid (HNO3) and for SO2. The SO2 concentrations from the cellulose and nylon
filters are summed to obtain total SO2.
CASTNET also measures hourly ozone (O3) concentrations, one of the major components of
smog. In addition to the air pollutants, CASTNET sites collect hourly 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 MLM, a
numerical 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.
Delivery of CASTNET Ozone Measurements to
the EPA Air Quality System
CASTNET was not designed to operate as a network for demonstration of compliance
with National Ambient Air Quality Standards (NAAQS) for O3. Instead, CASTNET was
designed to provide information on geographic patterns in regional, rural O3 levels.
However, because of interest in rural O3 concentrations by the regulatory and scientific
communities, EPA has directed MACTEC to prepare EPA-sponsored sites to meet
40 CFR Part 58 monitoring requirements and to ultimately deliver CASTNET O3
measurements to the EPA Air Quality System (AQS). AQS is EPA's repository of ambient
air quality monitoring data from more than 10,000 monitors. State, local, and tribal
agencies and other organizations collect data and submit them to AQS on a periodic
basis. AQS data are flagged with status codes to indicate the type of data (e.g., regulatory
or non-regulatory) submitted.
CASTNET monitoring equipment has been upgraded as one step toward meeting Part 58
criteria. Upgrades include new ozone analyzers, data loggers with improved data
communication, long-term manufacturer support for analyzers and loggers, and internal
shelter temperature sensors. These instrument upgrades support conversion to
regulatory-compliant operating and reporting procedures. The new data loggers and
CASTNET Annual Report - 2008 ~ 7 ~ Chapter I: CASTNET Overview
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analyzers allow more efficient tracking and recording of shelter temperature and
provide system monitoring data that enable remote troubleshooting and optimization
of operations.
The data logger is programmed to control daily zero/span/precision (z/s/p) checks for the
O3 analyzer. The O3 concentration needed for the precision (90 parts per billion [ppb])
and span (400 ppb) checks is produced internally by the onboard ozonator. Zero air is
used for all quality control (QC) checks, including daily zero checks, and as the dilution
medium for the ozonator precision and span checks. Instrument span and precision
checks must be within ฑ 7 percent of reference value and zero checks must be ฑ 15 ppb
for O3 data to be considered valid.
All CASTNET continuous measurements, including the O3 data and supporting
parameters, are collected via the data logger, polled remotely, archived at the CASTNET
Data Management Center (DMC), and uploaded to AIRNow every hour. For sites to
meet Part 58 monitoring criteria, data will be collected in accordance with EPA Quality
Assurance (QA) Handbook Volume II (EPA, 2008b). Multi-point calibrations, which will be
performed every six months, will also be in compliance with the EPA QA handbook.
Ozone transfer standards will be used in accordance with EPA Technical Assistance
Document, "Transfer Standards for the Calibration of Ambient Air Monitoring Analyzers
for Ozone" (EPA, 2009d).
Data will be uploaded to the AQS data submittal Web application in batch format using
text files of raw ozone data and measurement accuracy and precision data. The AQS data
submittal Web application is accessed at http://www.epa.gov/ttn/airs/airsaqs/aqsweb/.
AQS is divided into two parts:
I. CDX-Central Data Exchange: A "Windows Explorer" for AQS. This
component transfers and manages files to and from AQS. Batch data files are
uploaded here and become available in the AQS application for processing.
2. AQS Application: This application is used to interact with, process, and
create reports of data.
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). The
equation to estimate flux is shown in Figure I -5. Measured atmospheric concentrations are
calculated based on the mass of each analyte in each filter extract and the volume of air
CASTNET Annual Report - 2008 ~ 8 ~ Chapter I: CASTNET Overview
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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 for each site are calculated for each hour of each year using the MLM. The MLM
is described by Meyers et a/. (1998) and Finkelstein et a/. (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) 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. The deposition velocities and fluxes presented in Chapter 3 were
calculated using the updated model.
Figure I -5 Multi-Layer Model
Flux = C x VA
l/Vd =
I
cut
+
^a, soil
Resistances
ra = aerodynamic
fa, sou = aerodynamic near soil
rb = boundary layer in thin layer at surface
rcut = cuticular
rs = stomatal
rsoii = soil
\
Wind Speed,
Sigma Theta
'cut
7 ra, soil
? rsoil-ซ
Sulfur Dioxide and Nitrogen Oxides Emissions
The ARP, established under Title IV of the 1990 CAAA, was designed to reduce the adverse
effects of acid deposition by requiring major reductions of SO2 and NOX emissions from the
electric power industry. EPA recently assessed the effects of the ARP and related programs in
CASTNET Annual Report - 2008
Chapter I: CASTNET Overview
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its 2008 progress report (EPA, 2009a). The report summarizes 2008 compliance with the ARP
and reported progress toward achieving environmental goals.
Under the ARP, 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 EGUs in the
contiguous United States. The program began in 1995 and is underway 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. Use of 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 CAAA allocated 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 SO2 emission
reductions, and 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 OTC NOX Budget (1999-
2002) and the NOX SIP Call/NBP, which began in 2003 and continued through 2008. The NBP
placed a cap on total NOX emissions from EGUs during the ozone season (May I through
September 30) when the potential for ozone formation is high. The CAIR NOX ozone season
trading program replaced the NBP in 2009. Although CAIR was remanded back to EPA in 2008,
the CAIR programs remain in effect while EPA works to develop a replacement rule.
The ARP is comprised of two phases for the reduction of SO2 and NOX. Phase I applied
primarily to the largest coal-fired EGUs from 1995 through 1999 for SO2 and from 1996
through 1999 for NOX. Phase II for both pollutants began in 2000. In 2008, the SO2
Phase II requirements affected 3,572 operating units. The Phase II NOX requirements applied to
969 of those operating units that exceed 25 megawatts and burned coal between 1990 and
1995 (EPA, 2009a). Under the ARP's emission reduction requirements, total SO2 emissions
from ARP sources were 7.6 million tons in 2008; total NOX emissions from ARP sources were
3.0 million tons.
Figure 1-6 presents state-by-state total annual SO2 emissions for Phase I and Phase II electric
utility plants for four years (1990, 1995, 2000, and 2008). The most significant reduction in SO2
emissions occurred in and near the Ohio River Valley where many coal-fired power plants are
located. Many of the states with the highest SO2 emissions realized the largest reductions. The
seven states with the greatest annual reductions include Ohio, which decreased emissions by
CASTNET Annual Report - 2008 ~ 10 ~ Chapter I: CASTNET Overview
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1.5 million tons since 1990, and Illinois, Indiana, Kentucky, Missouri, Tennessee, and West
Virginia. Annual NOX emissions by state are depicted in Figure I -7 for the same four years.
States with the highest NOX emissions also produced the most significant declines. Every state
east of the Mississippi River experienced a significant decline in annual NOX emissions from
2000 to 2008. For example, NOX emissions from Illinois power plants declined by 47 percent
from 2000 to 2008.
Figure 1-6 Annual Utility SO2 Emissions (Phase I and Phase II Plants only)
Annual Emissions of Sulfur Dioxid
1990
D 1995
D2000
D2008
Scale: Largest bar equals
2,212 thousand short
tons (Ohio, 1990).
Figure I-7 Annual Utility NOX Emissions (Phase I and Phase II Plants only)
Annual Emissions of Nitrogen Oxides
1990
D 1995
D 2000
D 2008
Scale: Largest bar equals
534 thousand short
tons (Ohio, 1990).
CASTNET Annual Report - 2008
Chapter I: CASTNET Overview
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2008 Significant Events
January
The first Campbell Scientific CR3000 data logger was installed at Palo Duro Canyon State Park, TX.
February
Analog cellular service ended. First installations of the AirLink Raven X cellular Ethernet modems
were completed to provide access and communication to sites without landlines.
May
Due to budget constraints, it was decided that cloud water sampling would not be conducted at
CLD303, TN for the 2008 sampling season under the Mountain Acid Deposition Program
(MADPro). This is the first season without sampling since MADPro began sampling in 1994.
July
MACTEC determined the date and time when model runs initialized with drought and saturated
model runs coalesced for each site for the entire record of MLM simulations. This point of
coalescence is now the starting point for each site's dry deposition record.
September
MACTEC's CASTNET analytical laboratory tied for first place out of 39 participating laboratories in
Environment Canada's laboratory intercomparison Proficiency Test 0092.
October
Yagi directional antennae were installed at select remote sites to boost the cellular signal at each site
and allow use of Raven X Cellular Ethernet modems for Internet Protocol (IP) connections.
Supplemental CASTNET training videos became accessible through a dedicated MACTEC Web site.
Operators can access videos from the sites.
November
MACTEC's CASTNET analytical laboratory began using the Dionex AS22 analytical column/AG22
guard column for the impregnated cellulose filter analyses, replacing the Dionex AS4A analytical
column /AG4A guard column. The new column provides improved peak separation and is less
susceptible to matrix interferences.
NFS produces a biannual CASTNET newsletter called The Monitor that contains information
about some of the changes and important events affecting CASTNET operations. For an
electronic library of current and previous newsletters, go to:
http://www.nature.nps.gov/air/Pubs/theMonitor.cfm.
CASTNET Annual Report - 2008 ~ 12 ~ Chapter I: CASTNET Overview
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Chapter 2: Atmospheric Concentrations
Three-stage filter packs are used to measure 7-day average concentrations of SO2,
SO4, HNO3, NO3, NH4, CI", and four earth metals at 84 CASTNET monitoring
stations. Measured annual mean concentrations of sulfur species have decreased
steadily since 1990. Concentrations of nitrogen species remained relatively steady
from 1990 until 2000 when they began to decline as NOX emission reduction
programs were implemented. Trends in mean annual SO2, SO4, total NO3, and NH4
concentrations aggregated over the 34 eastern reference sites are shown over the
period 1990 through 2008 and for the 17 western sites for the period 1996 through
2008 using box plots for each year. All four parameters declined over the 19-year
period. SO2 and SO24 concentrations declined significantly since 2005. SO2
concentrations measured at the 17 western reference sites also declined.
Concentrations of the other three pollutants measured at the western sites did not
change significantly.
Separate maps depicting the annual mean concentrations of SO2, SO4, total nitrate (HNO3 +
NO3), and NH4 are presented in this chapter. Additional maps are provided in CASTNET
quarterly reports (MACTEC 2008a, 2008d, 2009c, 2009a). The concentration shading used in
the maps in this chapter was prepared using an algorithm based on inverse distance weighting
and the scales specified on each map. In addition, trends in concentrations over the 19-year
period (1990 through 2008) were derived from the 34 eastern CASTNET reference sites
(Figure I -2) and are presented using box plots. Trends in annual mean concentrations were also
estimated from measurements aggregated over the 17 western CASTNET reference sites
(Figure I -3) for the period 1996 through 2008.
Sulfur Dioxide
Sulfur dioxide is a gaseous pollutant emitted during the combustion of coal, oil, and other fossil
fuels that contain sulfur. EGUs constitute the largest source of SO2 in the United States. SO2 is
a criteria pollutant regulated by the NAAQS, which are designed to protect human health and
welfare. To be compliant under the SO2 NAAQS, the annual average concentration must be
below 80 micrograms per cubic meter (|j,g/m3) of air. SO2 gas reacts in the atmosphere to form
various acidic compounds including sulfuric acid (H2SO4), a significant contributor to acid rain,
and ammonium sulfate [(NH4)2SO4], a major component of fine particle matter (PM25). Fine
particles are regulated by the NAAQS since PM25 contributes to negative health effects and also
to degradation of atmospheric visibility, including range and detail. The NAAQS for an annual
average PM2 5 concentration is 15 |j,g/m3.
Annual mean SO2 concentrations measured in 2008 are presented in Figure 2-1. Six states
centered on and downwind of the Ohio River Valley in the eastern United States recorded
CASTNET Annual Report - 2008 ~I3~ Chapter 2: Atmospheric Concentrations
-------
mean concentrations greater than or equal to 5.0 ng/m3 of air. The region covers Indiana, Ohio,
Pennsylvania, New Jersey, Maryland, and western Virginia. Quaker City, OH (QAKI72)
measured the highest concentration in the network with a value of I 1.4 |jg/m3. Only two
western sites (Figure I-I) measured an annual mean SO2 concentration greater than or equal to
1.0 |j,g/m3. The western sites are Palo Duro Canyon State Park, TX (PAL 190) and Theodore
Roosevelt National Park, ND (THR422).
Figure 2-1 Annual Mean SO2 Concentrations (|j,g/m3) for 2008
Site not pictured:
DEN417.AK 0.5
Figure 2-2 shows box plots of annual mean SO2 concentrations aggregated over the 34 eastern
reference sites from 1990 through 2008 (right side) and the 17 western reference sites from
1996 through 2008 (left side). The y-axes on the western and eastern plots have different
scales. The box plots for the eastern sites show a downward trend. The most substantial
reduction in ambient SO2 was recorded in 1995 at the beginning of the ARP. A noteworthy
decline was also recorded from 2005 through 2008. Three-year mean concentrations for 1990-
1992 and 2006-2008 were 8.9 ng/m3 and 4.6 ng/m3, respectively. This change constitutes a
48 percent reduction in 3-year mean SO2 concentrations between the two time periods. The
2008 mean level of 4.1 ng/m3 was the lowest mean value measured by the eastern reference
sites in the history of the network.
The box plots for the western reference sites indicate a decline in annual mean SO2
concentrations aggregated over the 17 sites. Three-year mean SO2 concentrations for 1990-
1992 and 2006-2008 were 0.6 ng/m3 and 0.4 ng/m3, respectively. This change constitutes a
37 percent reduction in 3-year mean SO2 concentrations over the 13 years. The aggregated
mean SO2 concentrations from the western reference sites were more than 10 times lower
than mean concentrations measured at the eastern reference sites.
CASTNET Annual Report - 2008
~ 14-
Chapter 2: Atmospheric Concentrations
-------
Figure 2-2 Trend in Annual Mean SO2 Concentrations (|j,g/m3)
1.5
,1.0 -
0.5 -
o
O
0.0
Western Reference Sites
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
ST-O*ICO^IOlDr^cQ
oooooooo
(M(M(M(M(M(M(M(M(M
20
Eastern Reference Sites
E 8 -I
4 -
t- MO
KS* " '7"<ป0HZ7ซ . *g
'ฐ \. * v
uria -A- '
TX43 Jf
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NC35
2002 Estimated Ammonia
Emisstons as "N" (kg
^H >1 ^ Active Sues
1-3 iV Inactlw Sltป
3-5
S.7
7-10
10-15
1S-20
>30
A 2007 United States-Canada
workshop on NH3 (NADP, 2009)
called for the creation of an
extensive long-term network of
passive NH3 samplers with NADP
serving as the coordinating
organization. The participants
also recommended the use of
Radiello diffusive passive samplers
throughout the network because
of low detection limits and high
reproducibility.
Ammonia Emissions from all sources but soil. 2002
Source: Carnegie Mellon University emissions model described in
http://www.cmu.edu/ammonia.
CASTNET Annual Report - 2008
~ 15-
Chapter 2: Atmospheric Concentrations
-------
Table 2a AMoN Sampling Locations
Site
COI3
ILI 1
IN99
KS24
MI96
MNI8
MN29
MN42
NC30
NC35
NC99
NM98
Name
Fort Collins, CO
Bondville (QAQC), IL
Indianapolis, IN
Glen Elder State Park, KS
Detroit, Ml
Fernberg, MN
Blue Mounds, MN
Great River Bluffs, MN
Duke Forest, NC
Clinton Research Station, NC
Durham, NC
Navajo Lake, NM
4
5
"w 2
rt o
40.5592
40.0520
39.7333
37.0378
42.2500
48.0500
43.6667
44.0500
35.7789
35.0258
35.8106
36.8097
0)
O
Fฐ~
105.0781
88.3725
86.2833
95.6264
83.2000
91.8166
96.2333
91.6333
78.8003
78.2783
76.8978
107.6520
Site
NM99
NYI6
NY67
OH02
OH27
OK99
ON07
PAOO
SC05
TX43
WI07
Name
Farmington, NM
Millbrook, NY
Ithaca, NY
Athens Super Site, OH
Cincinnati, OH
Stilwell, OK
Egbert, ON
Arendtsville, PA
Cape Romain Refuge, SC
Canonceta, TX
Mayville, Wl
a
3 _
11
36.7358
41.7858
42.4014
39.3167
39.1500
35.7514
44.2333
39.9231
32.9419
34.8803
43.4833
0)
O
3
o r
108.2380
73.7414
76.6589
82.1000
84.5167
94.6717
79.7833
77.3078
79.6591
101.6649
88.5300
Note: Collocated CASTNET sites are highlighted in yellow.
In response, NADP initiated AMoN near the end of 2007 as a network of passive NH3
samplers across the United States with a site also operating in Egbert, ON. Table 2a lists the
AMoN locations. In addition to providing data that describe atmospheric NH3 concentrations
over space and time, NADP is evaluating the Radiello passive NH3 sampler against other
passive sampler types and denuder-based measurement systems to record the accuracy,
precision, and repeatability of the passive NH3 samplers in order to determine the best
sampler for the lowest cost.
Figure 2b Average Spring 2008 NH3 Concentrations
Average Spring {Mar.. Apr. May)
Ammonia Concentrations (ug/m3)
Information about AMoN can be
found on NADP NH3 Web site
(http://nadp.sws.uiuc.edu/nh3Net/).
The Web site discusses the
sampling system and related
information. Each site
operates triplicate Radiello
samplers over 2-week periods.
The samplers are removed at the
end of the two weeks and sent to
the NADP Central Analytical
Laboratory at the Illinois
State Water Survey for chemical
analysis. The site also maintains a
database of NH3 measurements.
Figure 2b was constructed from the triplicate 2-week data and shows spring 2008 mean
seasonal NH3 concentrations. The highest concentrations for 2008 were observed during the
spring, perhaps associated with fertilizer application. Nine sites measured NH3 values greater
than 2.5 Lig/m3.
CASTNET Annual Report - 2008
~ 16
Chapter 2: Atmospheric Concentrations
-------
Particulate Sulfate
Participate sulfate is formed in the atmosphere through the transformation of SO2 via both gas
and aqueous (cloud) phase reactions. It typically exists in the atmosphere as (NH4)2SO4, a major
component of PM25. Figure 2-3 provides a map of annual mean particulate SO4 concentrations
measured during 2008. Pennsylvania State University, PA (PSU 106) and QAKI72, OH each
measured a concentration of 4.0 |j,g/m3. The map shows significant geographic gradients in SO4
levels from the monitors in the vicinity of the Ohio River Valley northeastward to sites in
New England and northwestward to sites in Wisconsin and northern Minnesota. Sulfate
concentrations greater than or equal to 1.0 ng/m3 in the western region were measured at four
sites in California, two in Texas, and the monitoring station at THR422, ND.
Figure 2-3 Annual Mean SO4 Concentrations (ng/m3) for 2008
Site not pictured:
DEN417.AK 0.4
Box plots of annual mean SO4 concentrations from the 34 eastern reference sites from 1990
through 2008 are presented in the right half of Figure 2-4. The plots illustrate the trend in
atmospheric SO24 over the 19-year period. The figure shows a substantial decline in SO4 with
some interannual variability. The difference between 3-year means from 1990-1992 to 2006-
2008 represents a 26 percent reduction in SO4 from 5.4 ng/m3 to 3.6 |Jg/m3, respectively. The
2008 mean SO4 level of 3.2 |Jg/m3 was the lowest in the history of the network.
The box plots for the western reference sites are provided on the left side of Figure 2-4. The
boxes show no real change in annual mean SO4 concentrations aggregated over the 17 sites.
Mean sulfate concentrations measured at the western sites were lower than mean values
measured at eastern sites.
CASTNET Annual Report - 2008
~ 17-
Chapter 2: Atmospheric Concentrations
-------
Figure 2-4 Trend in Annual Mean SO24 Concentrations (|j,g/m3)
2.0
C-1-5 -
I 1.0 -
s
0)
o
,9 0.5 -
0.0
Western Reference Sites
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
7 -
O
O
3
2
Eastern Reference Sites
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
Total Nitrate
Total nitrate is the sum of HNO3 and NO3, which are formed from emissions of NOX produced
through the combustion of fossil fuels. Transportation sources are the largest contributors of
NOX emissions in the United States. Nitric acid exists as a gas and contributes to acid
deposition. Nitrate is a component of PM25 in the form of NH4NO3 and as larger particles, e.g.,
sodium nitrate (NaNO3) or calcium nitrate [Ca(NO3)2]. A map of annual mean total nitrate
concentrations for 2008 is shown in Figure 2-5. This chapter discusses data on total nitrate
levels because of the uncertainty in individual species measurements and because total nitrate is
more representative of a response to changes in NOX emissions than either of its constituents
alone. The map of 2008 total nitrate concentrations shows three regions with mean
concentrations greater than or equal to 2.5 |j,g/m3. The largest region extends from eastern
Kansas to Ontario. CASTNET monitors in six states in the Midwest, including Kansas, Illinois,
Indiana, Kentucky, Ohio, and Michigan, measured concentrations greater than or equal to 2.5
Hg/m3. The monitor at Egbert, ON (EGBI8I) also measured an annual mean concentration of
2.5 |j,g/m3. The second, smaller region covers sites in eastern Pennsylvania, New Jersey, and
Maryland. Three sites in California constitute the third region. Three sites, including Stockton, IL
(STKI38); Salamonie Reservoir, IN (SAL133); and Lykens, OH (LYKI23), measured the highest
concentration (3.7 |Jg/m3) in the network.
Box plots of total nitrate levels for 1990 through 2008 are given in Figure 2-6. The data shown
on the right side of the figure were aggregated from the 34 eastern reference sites. The data
show no trend in mean concentrations until 2000 when nitrate levels began to decline in
response to NOX emission control programs. Three-year mean levels declined from 3.0 ng/m3
to 2.3 ng/m3 from 1990-1992 to 2006-2008, producing a 25 percent reduction in total nitrate.
Total nitrate levels measured at the eastern reference sites declined from a 2000 mean value of
3.2 ng/m3 to a 2008 level of 2.1 ng/m3, the lowest in the history of CASTNET.
CASTNET Annual Report - 2008
~ IB-
Chapter 2: Atmospheric Concentrations
-------
Figure 2-5 Annual Mean Total Nitrate (NO3 + HNO3) Concentrations (ng/m3) for 2008
Site not pictured:
DEN417, AK 0.1
>3.31
Data aggregated from the 17 western sites are shown on the left side of Figure 2-6. The 3-year
mean total nitrate concentration for 2006-2008 was lower than the corresponding 1990-1992
level. However, this change is not considered substantive.
Figure 2-6 Trend in Annual Total Nitrate (NO3 + HNO3) Concentrations (ng/m3)
Western Reference Sites
Eastern Reference Sites
3.0
2.5 -
I 2.0-
I 1.5 -
03
| 1.0 -
o
O
0.5 -
0.0
90* Percentile
75* Percentile
Median
Mean
25th Percentile
10th Percentile
7 -
S 4 -
03
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2 -
1 -
0
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8 8
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ST-CMCO^LOCDr^CQ
00000000
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Participate Ammonium
Particulate ammonium is formed when NH3, HNO3, SO24, and NO3 particles interact in the
atmosphere. NH3 is formed through volatilization of farm animal wastes and fertilizers and
some combustion processes. Annual mean NH^ concentrations for 2008 are depicted in
Figure 2-7. No monitors measured concentrations above 2.0 |jg/m3. The data show a flat
geographic distribution across the eastern United States with most sites reporting values
greater than or equal to 1.0 |ig/m3. Higher concentrations were measured in the agricultural
CASTNET Annual Report - 2008
~ 19-
Chapter 2: Atmospheric Concentrations
-------
Midwest, Pennsylvania, and northern Alabama. The NH^ concentrations measured at western
sites were low with all sites measuring concentrations less than 1.0 |j,g/m3.
Figure 2-7 Annual Mean NH^ Concentrations (|j,g/m3) for 2008
Site not pictured:
DEN417.AK 0.1
Box plots of NH^ concentrations are provided in Figure 2-8. The trend diagram for the eastern
sites shows a reduction in mean NH+4 levels from I990-I992 to 2006-2008. The I990-I992
mean concentration was 1.8 |Jg/m3 and the 2006-2008 value was 1.3 |j,g/m3. The box plots
characterizing the western sites show no change.
Figure 2-8 Trend in Annual Mean NH+4 Concentrations (ng/m3)
Western Reference Sites
0.6
0.5 -
,0.4 -
ง0.2 ]
o
O
0.1 -
0.0
ฃ 2 -
O -
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Eastern Reference Sites
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
CM CM CM
CM CO ^ LO CD 1^ CO
8888888
CM CM CM CM CM CM CM
CASTNET Annual Report - 2008
-20-
Chapter 2: Atmospheric Concentrations
-------
Trends in Air Quality at CASTNET Western Reference Sites
Trends in concentrations over the 13-year
period (1996-2008) were derived from the
17 CASTNET western reference sites
(Figure I -3). Box plots constructed from
data aggregated from the 17 sites are given in
Figures 2-2, 2-4, 2-6, and 2-8. Additional
trend plots are shown in this discussion.
Figure 2c presents mean SO2 trend lines for
eight western sites selected to depict a range
of results. Declines in annual mean SO2 levels
were observed at six of the sites. Noticeable
reductions were measured at Chiricahua
National Monument, AZ (CHA467) and
Mesa Verde National Park, CO (MEV405).
The box plots (Figure 2-2) derived from
aggregated data show a 37 percent decline.
Trend lines for annual mean total nitrate
concentrations measured at four California
CASTNET sites are shown in Figure 2d. A
significant decline was measured at Joshua
Tree National Park, CA (JOT403) with about
a 17 percent reduction between 3-year
averages at the beginning and end of the
13-year period. Concentrations measured at
JOT403, which is downwind of the Los
Angeles Basin, were about three times higher
than concentrations measured at Yosemite
National Park, CA (YOS404).
Figure 2e depicts trends in all four annual
mean pollutants measured at Mount Rainier
National Park, WA (MOR409). The figure
shows that all four pollutants declined with
especially noticeable declines in SO2 and SO24
levels during 2000 to 2002. The decline in
sulfur pollutants is attributed to the
installation of SO2 scrubbers at the Centralia
Power Plant and a corresponding reduction
in emissions.
Figure 2c Trends in Mean SO2
Concentrations (|j,g/m3) at Eight
Western Sites
2.0
1.8 -
1.6
1 1.4
D)
5 1.2
ง ฐ'8
o 0.6
O
0.4 -
0.2 -
0.0
-*-CAN407
GLR468
--GRC474
ROM406
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GRB411
-*-MEV405
-ซ-YEL408
ST-CNco^-LOCDr^co
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(M(M(M(M(M(M(M(M(M
Figure 2d Trend in Annual Mean Total
Nitrate Concentrations (|j,g/m3) at Four
California Sites
12
1 -
JOT403 -M-LAV410
PIN414 -ป-YOS404
Figure 2e Trends in Annual Mean Pollutant
Concentrations (|j,g/m3) at Mount Rainier
National Park, WA
1.4
1.2 -
fT 1.0
fo.8
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0)
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0.2 -
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TotalNO3 NH4*
CASTNET Annual Report - 2008
-21
Chapter 2: Atmospheric Concentrations
-------
Chapter 3: Atmospheric Deposition
CASTNET was designed to provide estimates of the dry deposition of sulfur and
nitrogen pollutants across the United States. CASTNET uses a hybrid approach to
estimate dry deposition by combining measured pollutant concentrations and modeled
deposition velocities. The Multi-Layer Model is used to calculate hourly deposition
velocities for each monitoring site based on meteorological measurements and
information on the vegetation within I km of each site. Total deposition is the sum of
estimated dry deposition and measured wet deposition. Total sulfur deposition estimated
for eastern reference sites has declined since 1990. The data show a 38 percent
reduction in 3-year mean sulfur fluxes over the period from 1990-1992 to 2006-2008.
Dry and total sulfur deposition estimated for 17 western sites declined over the period
1996 through 2008. Total nitrogen deposition estimated for the eastern reference sites
declined by 19 percent. Total nitrogen deposition did not change at the western
reference sites over the 13 years. Dry deposition is responsible for a significant
percentage of total deposition, especially in major emission source regions.
Gaseous and particulate sulfur and nitrogen pollutants are deposited through dry and wet
atmospheric processes. A critical objective of CASTNET is to estimate the rate, or flux, of dry
deposition from the atmosphere to sensitive ecosystems based on measured meteorological
and other environmental conditions. Flux values are estimated as the product of measured
concentration data and MLM-modeled dry deposition velocities. Wet deposition measurements
were obtained from NADP/NTN and combined with CASTNET dry deposition data to
estimate total deposition. Dry sulfur, total sulfur, dry nitrogen, and total nitrogen deposition
decreased during 2008. Precipitation-weighted mean concentrations of atmospheric sulfur
declined over the past 19 years. Nitrogen concentrations in precipitation have declined slowly
since 1998.
Dry deposition processes were simulated using the MLM (Figure 1-5) as described by
Meyers et a/. (1998) and Finkelstein et a/. (2000). The most recent version of the MLM
(Schwede, 2006) was used 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 SO2, HNO3, O3, and the particles, SO24,
NO3, and NH^. The deposition velocities were assumed to be identical for all particle species.
Deposition velocity values were calculated for each of the pollutant species for each hour with
valid meteorological data for each CASTNET site for the entire period 1990 through 2008. For
a deposition velocity to be estimated, measurements of temperature, solar radiation, relative
humidity, wind speed, and standard deviation of the wind direction (sigma theta) must all be
CASTNET Annual Report - 2008 ~ 22 ~ Chapter 3: Atmospheric Deposition
-------
valid for the hour. Aggregation rules for CASTNET require three valid quarters for the
calculation of an annual value. If an annual value was not available for a specific site, the results
were not included on the maps presented in this chapter. Sites with no deposition estimates
are shown as dots with no value. For trends analyses, missing values were replaced by
interpolation or extrapolation using valid annual estimates. For example, if an intermediate year
was missing, the value for that year was interpolated from adjacent years. If a 2008 value was
missing, the 2008 value was assumed equal to the value for 2007.
Sulfur Deposition
MLM runs were made separately for SO2 and SO^". The model calculations were summed to
obtain estimates of dry sulfur deposition (as S). A map of dry sulfur deposition fluxes for 2008 is
provided in Figure 3-1. The magnitude of a deposition rate is illustrated by the size of the circle.
The map depicts three CASTNET sites with estimated fluxes greater than 5.0 kilograms per
hectare per year (kg/ha/yr). These sites are located in Ohio at Quaker City (QAKI72) and in
Pennsylvania at Pennsylvania State University (PSU 106) and Arendtsville (ARE128). The highest
deposition rate was estimated for QAKI72, OH with a flux of 8.9 kg/ha/yr. The highest dry
sulfur deposition rates coincided with the major SO2 source region (Figure 1-6) 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 + SO24) Deposition (kg/ha/yr) for 2008
Site not pictured:
DEN417, AK 0.1
CASTNET Annual Report - 2008
-23-
Chapter 3: Atmospheric Deposition
-------
Wet deposition values used to estimate total deposition were based on a combination of
historical CASTNET wet deposition data and NADP/NTN wet deposition data. For CASTNET
sites where wet concentrations were measured prior to January 1999, 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 diameters of 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. Seven CASTNET sites in Indiana, Ohio, and
Pennsylvania had total (dry + wet) sulfur deposition fluxes greater than 10.0 kg/ha/yr. The
highest total sulfur deposition rate was estimated for QAKI72, OH with a value of
17.2 kg/ha/yr. Total sulfur deposition at western sites was less than or equal to 2.0 kg/ha/yr.
Centennial, WY (CNTI69) had the highest estimated flux for the western sites with a value of
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 Morton Station, VA (VPI120) to less than 20 percent at sites
in New England.
Figure 3-3 presents box plots that show the trend in dry sulfur deposition (as S) for the eastern
(right side) and western (left side) reference sites. Figure 3-4 shows the trend in annual total
(dry + wet) sulfur deposition (as S). The box plots were based on data obtained from the 34
CASTNET eastern reference sites (Figure 1-2) for the period 1990 through 2008 and from the
17 western reference sites (Figure I -3) for 1996 through 2008. The y-axes on the two figures
have different scales. Aggregated sulfur deposition declined considerably at the eastern and
western reference sites over their respective periods. Figure 3-5 presents estimates of trends
in dry, wet, and total deposition of sulfur (as S) on the same diagram for the eastern reference
sites only. The trend line for precipitation-weighted mean sulfur concentrations in precipitation
shows a decline in 2008 after small increases during the previous three years.
CASTNET Annual Report -2008 ~ 24 ~ Chapter 3: Atmospheric Deposition
-------
Figure 3-2 Total (Dry + Wet) Sulfur Deposition (kg/ha/yr) for 2008
Site not pictured:
DEN417.AK 0.2
Total Deposition
6
1.6
Dry Deposition
Wet Deposition
Figure 3-3 Trend in Dry Sulfur Deposition (kg/ha/yr)
Western Reference Sites
Eastern Reference Sites
0.8
,0.6 -
'.OA -
&0.2 -
0.0
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
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CASTNET Annual Report - 2008
-25-
Chapter 3: Atmospheric Deposition
-------
Figure 3-4 Trend in Total Sulfur Deposition (kg/ha/yr)
3.0
2.5
f 2.0
|>
.1
01.0 -
0)
Q
0.5 -
0.0
Western Reference Sites
90* Percentile
75th Percentile
Median
Mean
25th Percentile
10* Percentile
25
20 -
i 10 -
5 -
Eastern Reference Sites
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
COOlOt-CMCO^lOCDr^CO
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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 are more representative of changes in SO2
emissions. The relatively wet year 2003 experienced high total sulfur deposition even though
the sulfur concentration in precipitation was relatively low. Overall, total sulfur deposition
declined at the eastern reference sites from a 1990-1992 mean of 13.2 kg/ha/yr to a 2006-2008
mean of 8.2 kg/ha/yr, a 38 percent reduction. Total sulfur deposition declined at the western
reference sites from a 1996-1998 mean of 1. 17 kg/ha/yr to a 2006-2008 mean of 0.83 kg/ha/yr,
a 29 percent reduction.
Figure 3-5 Trend in Sulfur Deposition (kg/ha/yr) with Concentrations in Precipitation (mg/l):
Eastern Reference Sites
16
14
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8 -
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in 6
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[=] Wet Deposition
i i Dry Deposition
Total Deposition
x-Concentration in Precipitation
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h 0.8
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CASTNET Annual Report - 2008
-26-
Chapter 3: Atmospheric Deposition
-------
Using CASTNET Data to Assess Quantity of Atmospheric Deposition
Compared with Critical Loads
A critical load is a measure of the exposure to one or more pollutants found in an
ecosystem, below which significant harmful effects on sensitive members of the ecosystem
do not occur (Nilsson and Grennfelt, 1988). Measures of critical load have been most often
applied to atmospheric deposition of sulfur and nitrogen pollutants. The critical load of
pollutants provides a measure to gauge the extent to which the ecosystem has recovered
from past deposition or is potentially at risk due to current or future deposition loads. For
this reason, the critical load approach has become an important assessment tool for
examining the environmental benefits that result from emission reduction programs. For
example, NFS has specified a goal for a critical load of 1.5 kg/ha/yr of wet nitrogen
deposition (Baron, 2006) for Rocky Mountain National Park. In other words, annual wet
deposition fluxes less than the specified goal will not have harmful effects on the high-
elevation ecosystems in the park.
Rocky Mountain National Park, CO (ROM406/206)
Two EPA-administered monitoring networks, the Temporally Integrated Monitoring of
Ecosystems (TIME) and the Long-Term Monitoring (LTM) programs, provide surface water
chemistry measurements in four regions known to be sensitive to acid precipitation
(EPA, 2009b): New England, the Adirondack Mountains, the Appalachian Plateau, and the
Blue Ridge Mountains (Figure 3a). Sulfate and NO3 ion concentrations, base cation (Ca2+,
Mg2+, K+, Na+) concentrations, acid neutralizing capacity (ANC), and other parameters are
monitored in the TIME/LTM networks in order to track changes in surface water chemistry
and the level of acidification produced in response to changes in acidic deposition. Surface
water chemistry data from TIME/LTM and other programs and deposition loadings from
NADP and CASTNET can be used to determine whether a critical load is exceeded, i.e.,
whether the amount of deposition is greater than the critical level needed to reach and/or
maintain a healthy ecosystem.
CASTNET Annual Report - 2008
27-
Chapter 3: Atmospheric Deposition
-------
Figure 3a Trends in Lake and Stream ANC Concentrations at LTM Sites, 1990-2006
Increasing trend
Increasing non significant trend
0 nซTtMsinj non sijnifirjtii aenii
Source: EPA
CASTNET provides weekly concentration data for acidic pollutants and base cations, which
could be utilized to estimate dry deposition fluxes and gauge exceedances of critical loads.
Figure 3b shows 2008 annual mean Ca2+ concentrations. These data and other CASTNET
ion concentration measurements can be used to model dry deposition loading of base
cations to an ecosystem. This information is typically missing from critical load and
biogeochemical hydrological models. The benefits of using CASTNET data for input to these
models are that CASTNET (I) provides long-term trends of pollutants measured near
sensitive ecosystems and (2) provides a more complete estimate of the ions that contribute
to depositional loading to an ecosystem.
Figure 3b CASTNET 2008 Annual Mean Ca2+ Concentrations (ng/m3)
0.12
0.38
J21 .,.
' -f17ii--^
X 1 9 U.\ \^:
, |>o.s
CASTNET Annual Report - 2008
28-
Chapter 3: Atmospheric Deposition
-------
Nitrogen Deposition
Dry fluxes of nitrogen (as N) for 2008 are shown in Figure 3-6. These fluxes are the sum of
fluxes of HNO3 + NO3 + NH^, based on the individual MLM simulations for the three species.
A majority of CASTNET sites in the eastern United States had estimated dry nitrogen
deposition rates greater than 1.0 kg/ha/yr. Deposition rates greater than 2.0 kg/ha/yr were
calculated for sites in Ohio, Pennsylvania, New Jersey, Kentucky, and at Great Smoky
Mountains National Park (GRS420) in Tennessee. Two monitoring sites in California had fluxes
greater than or equal to 2.0 kg/ha/yr. Locations on the map with no value had insufficient data
to calculate fluxes.
Figure 3-6 Dry Nitrogen (HNO3 + NO3 + NH+4) Deposition (kg/ha/yr) for 2008
Deposition
Site not pictured:
DEN417, AK 0.1
Figure 3-7 presents a map of total nitrogen deposition (as N) for 2008. The map was
constructed by summing the estimates of dry (light shading) and wet (dark shading) deposition.
The figure shows that a majority of the eastern sites recorded deposition rates greater than
5.0 kg/ha/yr. No values above 10.0 kg/ha/yr were estimated for 2008. The highest total nitrogen
flux (9.6 kg/ha/yr) was estimated for Vincennes, IN (VIN 140). The values at the western sites
ranged from 1.0 kg/ha/yr at Yosemite National Park, CA (YOS404) to 3.8 kg/ha/yr in southern
California at Converse Station (CON 186). The contributions of dry nitrogen deposition to
total nitrogen were lower than the corresponding contributions of dry sulfur deposition. Dry
nitrogen deposition contributed less than 50 percent of total deposition in the East. On the
CASTNET Annual Report - 2008
-29-
Chapter 3: Atmospheric Deposition
-------
other hand, dry nitrogen deposition contributed more than half of total nitrogen deposition at
four of five monitoring sites in California, a region with elevated concentrations of nitrogen
species and limited rainfall.
Figure 3-7 Total (Dry + Wet) Nitrogen Deposition (kg/ha/yr) for 2008
Site not pictured:
DEN417.AK 0.2
Total Deposition
10
5
1
Dry Deposition
Wet Deposition
Figure 3-8 presents box plots that were constructed using data from the 34 eastern reference
sites over the period 1990 through 2008 (right side) and 17 western reference sites for 1996
through 2008 (left side). The box plots show the trends in dry nitrogen deposition (as N). The
box plots for the eastern sites in Figure 3-8 show a reduction in dry nitrogen deposition
beginning in 1999. Three-year mean fluxes declined from 2.2 kg/ha/yr in 1990-1992 to
1.6 kg/ha/yr in 2006-2008, a 27 percent reduction over the 19 years. The box plots for the
western sites show a smaller IS percent decline, a change from 0.90 kg/ha/yr in 1996-1998 to a
mean of 0.76 kg/ha/yr in 2006-2008.
CASTNET Annual Report - 2008
-30-
Chapter 3: Atmospheric Deposition
-------
Figure 3-8 Trend in Dry Nitrogen Deposition (kg/ha/yr)
Western Reference Sites
Eastern Reference Sites
,1.5 -
0.0
1 -
Ir-fW
Figure 3-9 shows the trends in annual total (dry + wet) nitrogen deposition for the eastern
(right side) and western (left side) reference sites. Total nitrogen deposition aggregated over
the eastern sites 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 1996 with a
substantial decline over the last five years. Total nitrogen flux for the western sites shows a
relatively flat distribution. Estimates of trends in wet, dry, and total deposition of atmospheric
nitrogen (as N) are presented in Figure 3-10 for the eastern reference sites only. The trend line
(dotted) for precipitation-weighted mean nitrogen concentrations in precipitation shows a slow
downward trend since 1998 with a drop in 2008. This trend line is reasonably representative of
the effect of changes in NOX emissions because it does not depend on precipitation amounts.
Total nitrogen deposition declined 19 percent in the East over the 19 years.
Figure 3-9 Trend in Total Nitrogen Deposition (kg/ha/yr)
Western Reference Sites
Eastern Reference Sites
6
5 -
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
14
12 -
10 -
6 -
90th Percentile
75* Percentile
Median
Mean
25th Percentile
10th Percentile
CASTNET Annual Report - 2008
-31
Chapter 3: Atmospheric Deposition
-------
Figure 3-10 Trend in Nitrogen Deposition (kg/ha/yr) with Concentrations in Precipitation
(mg/l): Eastern Reference Sites
12
10 -
6 -
(/)
8. 4H
2 -
1=1 Wet Deposition
1=1 Dry Deposit ion
Total Deposition
--x- Concentration in Precipitation
- 1.0
1.2
- 0.2
0.0
^-
8 8
8
(N(N(N(N(N(N(N(N(N
Uncertainties in NO"3 and HNO3 Concentrations
and Their Effect on Dry Nitrogen Deposition
The uncertainties of NO3 and HNO3 concentrations were estimated using results of the
Maryland Aerosol Research and Characterization (MARCH)/CASTNET data
intercomparison (Lavery et o/., 2009). MARCH data were collected at Fort Meade, MD,
and the CASTNET measurements were taken at Beltsville, MD (BELI 16). The CASTNET
filter pack technology causes uncertainty in the measured nitrogen species. The effects of
these uncertainties on weekly and annual dry deposition fluxes of NO3, HNO3, and total
nitrogen deposition (NO3+HNO3+NH4, as N) were analyzed by adjusting the HNO3 and
NO3 concentration values for BELI 16, MD based on the MARCH/CASTNET
intercomparison results and then recalculating the total nitrogen flux.
NO3 concentrations were decreased by a factor of 3.5 to characterize the fact that filter-
sampled NO3 was comprised primarily of larger particles. HNO3 concentrations were
increased by a factor of 1.15 based on the MARCH/CASTNET intercomparison results.
Total nitrogen deposition values were then remodeled using the MLM based on
measurements collected at BELI 16, MD for the years 1998 through 2007.
As Table 3a shows, differences from the recalculated concentrations are relatively small
(approximately 10 percent or less) reflecting the fact that the HNO3 component
dominates the total nitrogen dry deposition. Dry deposition of particulate NO3 has a
CASTNET Annual Report - 2008
-32
Chapter 3: Atmospheric Deposition
-------
relatively small contribution to the total nitrogen flux, and thus, the large decrease in
NO3 concentrations does not have a significant effect on total deposition.
Table 3a Changes to Dry Deposition of Total Measured Nitrogen after Adjustments to
NO3 and HNO3 Fluxes
Site ID Year
BELII6 1998
BELII6 1999
BELII6 2000
BELII6 2001
BELII6 2002
BELII6 2003
BELII6 2004
BELII6 2005
BELII6 2006
BELII6 2007
Total
Measured N
2.62
3.00
1.85
2.41
2.57
2.23
2.56
2.25
2.63
2.40
NO3
Adjustment Only
2.58
2.94
1.77
2.36
2.53
2.18
2.50
2.18
2.59
2.38
HNO3
Adjustment Only
2.93
3.35
2.05
2.68
2.87
2.49
2.85
2.51
2.94
2.69
Both
Adjustments
2.89
3.29
1.97
2.64
2.84
2.44
2.79
2.44
2.90
2.66
Beltsville, MD (BELI 16)
CASTNET Annual Report - 2008
-33-
Chapter 3: Atmospheric Deposition
-------
Chapter 4: Ozone Concentrations
CASTNET provides the primary platform for monitoring rural, ground-level ozone
(O3) concentrations in the United States and for providing information on geographic
patterns in rural O3 levels. CASTNET was not designed to operate as a network for
demonstration of compliance with O3 NAAQS. However, the network provides data
on the extent to which rural areas potentially exceed concentration values mandated
by NAAQS. Ozone measurements collected during 2006-2008 were used evaluate
both the 1997 (EPA, 1997) and 2008 (EPA, 2008a) O3 standards. To attain the 1997
standard, the 3-year average of the fourth-highest daily maximum 8-hour average O3
concentrations measured at each monitor within a specified area over each year must
not exceed 0.08 parts per million (ppm) or be greater than or equal to 85 ppb in
practice. The 2008 standard is achieved when the 3-year average of the fourth-highest
daily maximum 8-hour average O3 concentrations measured at each monitor within a
specified area over each year do not exceed 0.075 ppm (75 ppb in practice). The year
2008 is the first year when no eastern CASTNET sites measured 8-hour average O3
concentrations greater than or equal to 85 ppb.
Almost all CASTNET sites operate an O3 analyzer that measures hourly concentrations. 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 NAAQS. The 8-hour O3 standard is a useful measure for
assessing the status and trends in rural O3 levels in order to gauge the success of EPA emission
reduction programs such as the NOX SIP Call/NBP and CAIR. The analyses presented in this
section provide maps and examine trends in the fourth highest daily maximum 8-hour average
O3 concentrations measured annually.
Ground-level O3 is an air pollutant that can cause harmful effects to the human respiratory
system and damage to vegetation and ecosystems. Ground-level O3 is formed in the lower
atmosphere when volatile organic compounds (VOCs) and NOX react in the presence of
sunlight. Emissions from motor vehicle exhaust, industrial facilities, chemical solvents, gasoline
vapors, and power plants are the major anthropogenic sources of NOX and VOCs. Also,
biogenic VOC emissions from trees and other vegetation contribute to O3 formation in rural
areas. VOC 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,
implementation of the NOX emission reductions that were mandated by the ARP and other
NOX emission control programs contributed to reductions in O3 concentrations, especially in
CASTNET Annual Report - 2008 ~ 34 ~ Chapter 4: Ozone Concentrations
-------
rural areas with elevated 8-hour average levels, because regional transport of pollutants
contributes to ozone formation.
Meteorological conditions play a significant role in O3 formation. Dry, hot, and sunny days are
most conducive to O3 production. Ozone concentrations typically increase during daylight and
peak in the late afternoon after peak temperature and sunlight intensity. Concentrations then
drop in the evening. The warm months in spring, summer, and fall typically define the O3
season. EPA has defined a specific ozone season for each state and has proposed recently that
the ozone season be designated as year round in most locations.
On May I, 2009, the CAIR NOXozone season trading program began, replacing the NBP in
states covered under the CAIR NOX ozone season program, requiring further NOX emission
reductions from the power sector.
National Ambient Air Quality Standards for Ozone
Ozone
Primary Standards
Level
0.075 ppm
0.08 ppm
Averaging Time
8-hour i
8-hour2
Secondary Standards
Level
Averaging Time
Same as Primary
Notes: I (a) On September 5, 2009, EPA announced that it is reconsidering the current levels of the ozone
primary and secondary standards.
(b) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average O3
concentrations measured at each monitor within a specified area over each year must not exceed
0.075 ppm (effective May 27, 2008).
2 (a) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average O3
concentrations measured at each monitor within an area over each year must not exceed 0.08 ppm
(effective 1997).
(b) The 1997 standardand the implementation rules for that standardwill remain in place for
implementation purposes as EPA undertakes rulemaking to address the transition from the 1997 O3
standard to the 2008 O, standard.
The concentration shading for the figures used in this chapter was prepared using the scales
shown on each map. Additional maps of ozone concentrations can be viewed on the Web
site for the NPS Air Atlas (http://science.nature.nps.gov/AirAtlas/AirAtlasOI05/viewer.htm).
The Air Atlas incorporates all ozone monitoring reporting to AQS plus the CASTNET
ozone measurements.
Eight-Hour Ozone Concentrations
Figure 4-1 presents 3-year averages of the fourth highest daily maximum 8-hour average O3
concentrations for 2006-2008. During this period, 3-year averages of the fourth highest daily
CASTNET Annual Report - 2008
-35-
Chapter 4: Ozone Concentrations
-------
maximum 8-hour average O3 concentrations were greater than or equal to 85 ppb at Beltsville,
MD (BELI 16), Great Smoky Mountains National Park, TN (GRS420), and four sites in
California. Figure 4-1 also shows the geographic distribution of fourth highest daily maximum
8-hour average O3 concentrations greater than 75 ppb, which exceed the revised NAAQS
(0.075 ppm). The number of CASTNET sites with 8-hour average O3 levels greater than the
new standard is much larger than for values greater than or equal to 85 ppb. Eleven eastern and
eight western CASTNET sites exceeded the new standard. These 3-year average O3
concentrations constitute the current design values for achieving the 8-hour O3 NAAQS. For
example, the value of 107 ppb at Converse Station, CA (CON 186) would have to be reduced
to 84 ppb to achieve the old standard and to 75 ppb to achieve the new standard. A design
value is a statistic that describes the air quality status of a given area relative to the level of the
NAAQS. Design values are typically used to classify nonattainment areas, assess progress
towards meeting the NAAQS, and develop control strategies to achieve the NAAQS. Design
values change as a new 3-year database of monitored O3 concentrations becomes available.
Figure 4-1 Three-Year Average of Fourth Highest Daily Maximum 8-Hour Average Ozone
Concentrations (ppb) for 2006-2008
Site not pictured:
DEN417, AK 58
For comparison to current design values, 3-year averages of the fourth highest daily maximum
8-hour average O3 concentrations for 2000-2002 are presented in Figure 4-2. This period was
selected for comparison because the NOX SIP Call/NBP began in 2003 for the eastern United
States. A comparison of O3 data for these two 3-year periods (2000-2002 and 2006-2008)
illustrates the effectiveness of the emission reduction programs. Using the 84 ppb standard,
19 eastern and 3 California sites recorded 3-year averages greater than or equal to 85 ppb
during 2000-2002. The regions with elevated concentrations were located along the East Coast
CASTNET Annual Report - 2008
36-
Chapter 4: Ozone Concentrations
-------
from northern Virginia to Connecticut, extending almost to Maine, and in the central states of
Pennsylvania, Ohio, Michigan, Indiana, and Illinois. Exceedances were also recorded in Kentucky,
Tennessee, and greater Atlanta. Using the 75 ppb standard, the map in Figure 4-2 shows that
most of the eastern sites measured O3 concentrations greater than 75 ppb, as well as five
monitors in California and the site at Rocky Mountain National Park (ROM406). The period
2006-2008 represents a significant improvement in air quality and is one of the best periods of
air quality since the inception of CASTNET in terms of having the fewest sites with
exceedances of the 8-hour O3 NAAQS. However, sites in California, Maryland, and at
GRS420, TN continued to measure elevated ozone levels.
Figure 4-2 Three-Year Average of Fourth Highest Daily Maximum 8-Hour Average Ozone
Concentrations (ppb) for 2000-2002
Site not pictured:
DEN417, AK 49
Measurements of 8-hour average O3 concentrations during 2008 (Figure 4-3) were lower than
2007 and considerably lower than concentrations measured over the period 2000-2002. Five
sites in California measured O3 concentrations greater than or equal to 85 ppb. The five
California sites include Yosemite National Park (YOS404), Pinnacles National Monument
(PIN4I4), Sequoia National Park (SEK430), Converse Station (CON 186), and Joshua Tree
National Park (JOT403). The monitor at SEK430, CA measured the highest value (I 12 ppb) in
the network during 2008. The year 2008 is the first year when no eastern CASTNET sites
measured 8-hour average O3 concentrations greater than or equal to 85 ppb.
Figure 4-3 also depicts the geographic distribution of fourth highest daily maximum 8-hour
average O3 concentrations greater than 75 ppb. Eleven eastern sites in eight states and six
California monitors measured ozone concentrations above 75 ppb. The monitor at
CASTNET Annual Report - 2008
37-
Chapter 4: Ozone Concentrations
-------
ROM406, CO measured a concentration of 76 ppb. The eastern states include Pennsylvania,
New Jersey, Maryland, Virginia, North Carolina, Tennessee, Georgia, and Texas. In addition to
the five California sites already mentioned, Lassen Volcanic National Park (LAV4IO) measured a
fourth highest daily maximum 8-hour average O3 concentration of 83 ppb.
Figure 4-3 Fourth Highest Daily Maximum 8-Hour Average Ozone Concentrations (ppb)
for 2008
/"~56
Site not pictured:
DEN417, AK 68
Figure 4-4 provides box plots depicting trends in fourth highest daily maximum 8-hour average
O3 concentrations from the 34 CASTNET eastern reference sites (right side) and 17 western
reference sites (left side). The eastern ozone data show a decline since 2002. The mean
aggregated value (69 ppb) for 2008 was the lowest in the history of the network. It represents
an improvement over the mean value of 90 ppb measured in 1998. The box plots constructed
from the aggregated western O3 concentrations show no trend. The 2006-2008 average of the
fourth highest daily maximum 8-hour average O3 concentrations for the western reference sites
was 72 ppb.
CASTNET Annual Report - 2008
Chapter 4: Ozone Concentrations
-------
Figure 4-4 Trend in Fourth Highest Daily Maximum 8-Hour Average Ozone Concentrations (ppb)
110
90 -
o
O
70 -
50
Western Reference Sites
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
CDr^COOlOt-CNCO
1111ฐฐฐฐ
SLO CD l1^ CO
0000
CN CN CN CN CN
110
90 -
70 -
50
Eastern Reference Sites
90th Percentile
75th Percentile
Median
Mean
25th Percentile
10th Percentile
Impacts of NOX Budget Program and Clean Air Interstate Rule
on Rural and Urban Ozone Levels in the
Eastern United States
Researchers at Cornell University and
the Cary Institute of Ecosystem Studies
used random coefficient models to
assess the impact of reduced NOX
emissions during the O3 season on daily
maximum 8-hour average O3
concentrations for various regions of the
eastern United States for the period
1997 through 2007. This assessment
extended previous analyses by Butler et
a/. (2003, 2005) that investigated the
impact of reduced NOX emissions on
NO3 concentrations in precipitation and
ambient concentrations of HNO3.
Random coefficient models were used
because O3 concentration values are not
independent but clustered for each site.
In addition, the models can examine
monitoring sites on a regional basis (e.g.,
the Northeast) or in other combinations
(e.g., urban versus rural sites). In this
Figure 4a Locations of Ozone
Monitoring Sites
Sile Type
Regions
Ml l.'.-'l [ I MOItlMBSl
Slates Covered Under NBP
Gซitn
-------
analysis, O3 data from 95 CASTNET and AQS sites were evaluated for the I I-year time
period for (a) the Eastern United States as a whole, (b) by region (Northeast, Mid-
Atlantic, Southeast, and Midwest), and (c) by rural CASTNET sites (32 sites) versus urban
AQS sites (63 sites). Figure 4a shows the locations of the sites and the defined regions
used in this analysis, as well as the NBP regulated states/areas.
Source regions for NOX emissions were derived from multiyear 24-hour air mass back
trajectories at 500 meters above ground level (AGL) and 1,000 meters AGL The Hybrid
Single-Particle Lagrangian Integrated Trajectory (HYSPLIT)-4 model was applied to
generate the trajectories. State-level emissions for stationary sources, which were
derived from the EPA ARP emissions database, provided the most complete record of O3
season emissions for the period 1997 through 2007 and are considered the best estimate
of NOX emission changes from stationary sources before and after NBP implementation.
CAIR, as promulgated, was designed to further reduce power plant pollutant emissions,
including a 2 million ton (61 percent) reduction in NOX emissions, from 2003 levels. The
models were used to estimate the impact of CAIR in terms of reducing O3 concentrations
in the eastern United States in 2015.
Ozone season O3 concentrations were meteorologically-adjusted to account for year-to-
year variations in humidity and temperature, which influence the production of O3.
Statistical model results were generated by dividing each region into rural and urban sites.
The models were used to evaluate how reduced NOX emissions would impact the sites.
Figure 4b illustrates the declines in daily maximum 8-hour average O3 concentrations for
the different regions and for rural and urban sites for pre-NBP (1997-2000) and
post-NBP (2004-2007) implementation, as well as for projected 2015 NOX emissions.
Figure 4b Declines (ppb) in Daily Maximum 8-Hour Average O3 Concentrations for
Urban (red) and Rural (blue) Sites
16
14
I 10
ฃ 8
0)
I 5
4
2
0
Eastern US
Northeast
Mid-Atlantic
Southeast
Midwest
** **
** **
CL
CD
o_ CL in in
CD CD TT TT
D. CL in in
CO CO TT TT
CL CL in in
CO CO TT TT
CL in in
CO TT TT
s
D
o:
Source: T. J. Butler
CASTNET Annual Report - 2008
-40-
Chapter 4: Ozone Concentrations
-------
The double asterisk (**) indicates the urban and rural site differences for a region are
statistically significant at p < 0.05. Similarly, a single asterisk (*) indicates statistically
significant differences between rural and urban sites in a region at p < 0.10. Error bars are
based on the standard error of the slope of the model regression lines. For the eastern
United States as a whole, O3 data from rural and urban sites are statistically different
(p < 0.05). Greater declines in ozone concentrations occurred at the rural sites, which
show a 7 ppb (12 percent) decline, while urban sites show a 5 ppb (8 percent) decline.
The Northeast region also shows statistically different (p < 0.05) daily maximum 8-hour
average O3 concentrations between rural and urban sites and the greatest difference
between declines in O3 levels at these sites. Urban sites show a post-NBP decline of
4 ppb (9 percent) while the rural sites show a decline of 9 ppb (18 percent). Modeled
differences between rural and urban sites for the Southeast and the Midwest regions
were less statistically significant (p < 0.10), with urban declines of 9 percent and 8 percent
for the two regions and rural declines of 12 percent and I I percent. The difference
between urban and rural sites in the Mid-Atlantic region was not statistically significant.
Rural monitoring sites are typically affected little by local emissions. They are likely more
affected by transported emissions such as those from large stationary sources (EGUs).
The greater declines at rural sites, except for the Mid-Atlantic region, may be explained
by the fact that stationary source emissions have been controlled to a larger extent than
comparable urban and transportation NOX sources. Urban sites are more affected by a
variety of local sources such as vehicular NOX emissions, which are more difficult to
regulate and control. The Northeast had the greatest decline in rural O3 concentrations.
The Northeast rural monitoring sites are "downwind" of a large number of stationary
sources that are now being regulated. Further ozone reductions at urban locations may
require a greater emphasis on controlling local NOX and VOC emissions.
Nitrogen Oxides and Ozone
In May 2009, EPA published The NOX Budget Trading Program: 2008 Emission, Compliance, and
Market Analyses. The report analyzed changes in NOX emissions from 1990 through 2008.
Figure 4-5, which was taken from the EPA report, depicts O3 season NOX emissions from all
NBP sources in the eastern United States from 1990 through 2008. The NBP was in effect from
2003 through 2008. The CAIRNOXozone season program began on May I, 2009 and replaced
the NBP in affected states. The OTC NOX Budget was in effect from 1999 through 2002. Other
emission control programs such as mobile source controls, VOC Reasonably Available Control
Technology (RACT) and Maximum Available Control Technology (MACT), new source review,
and the ARP contributed to NO,, and VOC emission reductions.
CASTNET Annual Report - 2008 ~ 41 ~ Chapter 4: Ozone Concentrations
-------
NBP sources emitted 481,420 tons of NOX in the 2008 O3 season (EPA, 2009c). Emissions in
2008 decreased 24,880 tons from 2007 and were 62 percent below 2000 levels and 75 percent
below 1990 emissions. NBP regulated 2,568 units in 2008. EGUs constituted 88 percent of the
regulated units; industrial sources constituted most of the remaining 12 percent.
Figure 4-5 Ozone Season NOx Emissions from All NBP Sources
2,200
~ 2.000
U)
E
1990 2000 2003 2004 2005 2006
Ozone Season
2007 2008
Notes:
Ozone Season NO* Emissions (thousand tons)
Total State Trad ing Budgets
Data reflect full ozone season emissions in all years for all states. The year 2000 baseline value has been adjusted to correct a
misprint in Figure 5 of the 2007 NBP report.
The 2008 total state trading budgets include opt-in allowances, where applicable (New York, Ohio, and West Virginia).
Source: EPA (2009c)
Trends in CASTNET measurements of total nitrate concentrations (Figure 4-6) measured
during the ozone season (May through September) at the 34 eastern reference sites show
almost no change from 1990 through 1999 followed by a decline as the emission reductions
from the OTC and NBP became effective. Three-year median concentrations before (2000-
2002) and after (2003-2005) the implementation of the NBP were 2.43 ng/m3 and 1.87 ng/m3,
respectively. The most recent three-year (2006-2008) median value was 1.67 |j,g/m3. Figure 4-7,
which was taken from the EPA report on NBP compliance (EPA, 2009c), shows the relationship
between NOX emission reductions from power industry sources and changes in O3 levels at
CASTNET and EPA AQS-compliant sites in the eastern United States over the period 2002-
2008. The figures show declines in concentrations in all NBP states. The figure also shows a
strong association between regions with the greatest emission reductions and downwind
monitoring sites showing the greatest improvement in O3 levels.
CASTNET Annual Report - 2008
-42
Chapter 4: Ozone Concentrations
-------
Figure 4-6 Trend in Ozone Season (May through September) Mean Total Nitrate
(NO3 + HNO3) Concentrations (|j,g/m3) - Eastern Reference Sites
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8
CM
Figure 4-7 Reductions in Ozone Season Power Industry NOX Emissions and Changes in
8-Hour Average Ozone, (2002 versus 2008)
Notes:
From 1999 to 2002, states in the Northeast reduced emissions from EGUs and industrial boilers under the OTC NOX Budget
Program. OTC states include Connecticut, Delaware, the District of Columbia, Main, Maryland, Massachusetts, New Hampshire,
New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Virginia.
Meteorologically-adjusted ozone data are from AQS and CASTNET sites that met completeness criteria.
Google Earth was used to display the information shown in this figure. To access the data layers shown here as well as other data,
including unite-level emissions and controls, visit the Clean Air Market Division's interactive mapping site at
.
Source: EPA (2009c)
CASTNET Annual Report - 2008
43-
Chapter 4: Ozone Concentrations
-------
Great Smoky Mountains National Park, TN
Source: NFS
Figure 4c Surface Weather Map for
July 20, 2008
Ozone Episode in the Great Smoky Mountains, TN
(GRS420) in July 2008
Periods with extended high ozone
concentrations have occurred
occasionally over the last 10 years at the
Look Rock site in Great Smoky Mountains
National Park, TN (GRS420). Measured
fourth highest daily maximum 8-hour
average O3 concentrations have exceeded
85 ppb causing potential contravention of
both the 1997 0.08 ppm and 2008 0.075
ppm NAAQS. A four-day O3 episode was
observed at the park during July 17-20,
2008. Surface weather conditions are
illustrated in Figure 4c, which shows a
Bermuda High off the East Coast and
Tropical Storm Cristobal off the coast of
North Carolina. The circulation around
the tropical storm was sufficiently
developed to produce northeasterly
winds along the East Coast from New
Jersey to the park However, the cloud
pattern produced by the storm was
limited and did not inhibit O3 formation.
A time series of hourly O3 concentrations
observed at GRS420, TN during
July 13-24, 2008 is provided in Figure 4d.
Daily maximum 8-hour O3 average
concentrations are also shown. The
8-hour levels are plotted at 0000 local
time for each day. Figure 4d shows the
gradual buildup of O3 beginning on
July 15th with a subsequent peak hourly
value of 90 ppb on the 19th and a peak
daily 8-hour value of 87 ppb, shown at
0000 on July 19th. The episode was
terminated by a shift to westerly winds on
July 20th.
WteMlw M>B M 7110 AJJ. F.S.T,
Figure 4d Time Series of Ozone
Concentrations
CASTNET Annual Report - 2008
Chapter 4: Ozone Concentrations
-------
Figure 4e Composite Diurnal Ozone
Concentrations
Figure 4d shows a fairly steady increase in peak hourly O3 values during the ozone
buildup. The peak I-hour concentration during the episode was not much higher than the
peak 8-hour value. The figure also shows a diurnal cycle daily with lower O3
concentrations observed around 0900. Figure 4e shows two plots of composite O3
concentrations. The top curve was
constructed by averaging all hours for
each hour of the day for the four-day
episode. The bottom curve was created
from a composite of the remaining hours in
July. The two daytime O3 peaks in the top
curve might have been produced by
pollutants from two different source regions
or by recirculated pollutants. The minimum
concentrations around 0900 to 1000 can be
explained by the end of nighttime dry
deposition or by fresh NOX emissions that
scavenge O3 around that time.
i-Ozone Event (7/17-20)
Remainderof July
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Figure 4f Backward Trajectories Ending
at lOOOEDTJuly 19,2008
NOAAHYSPLIT MODEL
Backward trajectories ending at 1400 UTC 19 Jul 08
G DAS Meteorological Data
Figure 4g Backward Trajectories Ending at
lOOOEDTJuly 20, 2008
NOAAHYSPLIT MODEL
Backward trajectories ending at 1400 UTC 20 Jul 08
GDAS Meteorological Data
2500
2000
1500
1000
500
06 00 IB 12 06 00 16 12 06 00 18
07/19 07:18 07/17
JobID 3919&5 Jo: '-i.iil I'.- 'MM I! ' .!',.'. A.IT 2009
JoblU:391857 Job Start: lueAug 11 15:51:49 GM I 2009
Source 1 lat 35633099 Ion -839422 hgls 500, 200, TOOmAGL
Source 1 lat 35633099 Ion -83 942S n:,;: 500, 200, 100 mAGL
Trajectory Direction Backward Duration 72 hrs MeteoData GDAS1
Vertical Motion Calculation Method Mcdel Vertical Velccity
Produced with HYSPUT from the NOAA ARL Website Ihttp./'www arl.noaa.gov/ready/)
MeteoData:GDAS1
Velocity
Produced wllh HYSPLIT from the NOAA ARl Websile [http://www arl.noaa.gov/ready/]
rrahctory Direction HBdnwd
Vertical Motion Calculation Method Mcdel Vertical Velocity
COSINE! Annual Report - 2008
45-
Chapter 4: Ozone Concentrations
-------
Backward trajectories from the National Oceanic and Atmospheric Administration
(NOAA) HYSPLIT Model for July 19, 2008 at 1400 UTC (1000 EDT) and for July 20, 2008
at 1400 UTC are provided in Figures 4f and 4g, respectively. Trajectories ending at
GRS420, TN are given for 100 m, 200 m, and 500 m AGL The three trajectories ending
at GRS420, TN at 1000 EDT on July 19th show similar origins. The 100 m and 200 m
trajectories originated in Maryland. The 500 m trajectory originated in New Jersey. All
three trajectories show significant subsidence and recirculation of air near their endpoint
at the park. The 100 m trajectory originated at an altitude of approximately 500 m three
days earlier. Hourly ozone concentrations reached 90 ppb during the afternoon of
July 19th, and the highest 8-hour average daily maximum level was recorded at 0000 on
the 19th. The recording of high concentrations in the afternoon suggests the transport of
ozone and its precursors along the trajectory pathways. The episode ended on July 20,
2008 when the winds switched to westerly as shown by the trajectories in Figure 4g.
The occurrence of northeasterly winds with significant atmospheric subsidence is
somewhat unusual during the summer in eastern Tennessee. Evidently, the northeasterly
winds transported precursor pollutants to the park from the Mid-Atlantic states, and the
pollutants were trapped under a subsidence inversion. These pollutants produced
relatively high ozone concentrations over the 4-day period, which ended with the
wind shift.
Views from the Look Rock (GRS420, TN) air quality monitoring station.
Photo on left shows a day with 83 mile visual range. Haziness (16 mile visual range) in
the photo on right is caused primarily by tiny sulfate particles.
July 14, 2008 - 83 mile visual range
Source: NFS
July 19, 2008 - 16 mile visual range
CASTNET Annual Report - 2008
46-
Chapter 4: Ozone Concentrations
-------
Chapter 5: Data Quality
CASTNET measurements and supporting activities are assessed routinely in order to
provide high-quality information to meet project objectives. The CASTNET Quality
Assurance program is based on specific data quality objectives that are evaluated using
data quality indicators (DQI) such as precision, accuracy, and completeness.
Measurements taken during 2008 and historical data collected over the period 1990-
2007 were analyzed relative to DQI and their associated metrics. These analyses
demonstrate that CASTNET data can be used with confidence and that CASTNET
continues to produce information of the highest quality.
v
The CASTNET 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 2008 QA
program elements are documented in the CASTNET Quality Assurance Project Plan (QAPP),
Revision 4.1 (MACTEC, 2008c). 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 2008 data were analyzed and compared with
historical data collected during the period 1990 through 2007. The information in this report is
supplemented by analyses that are discussed in quarterly CASTNET Quality Assurance Reports
(MACTEC, 2008b; 2008e; 2008f; 2009b). These QA reports are produced four times per year
with the fourth quarter report including an annual summary.
Precision
Figure 5-1 provides a bar chart in which the bars represent precision estimates for five
CASTNET analytes. Table 5-1 lists the precision and accuracy criteria for laboratory filter pack
measurements. Precision is defined as the mean absolute relative percent difference (MARPD).
CASTNET Annual Report - 2008 ~ 47 ~ Chapter 5: Data Quality
-------
Figure 5-1 Historical and 2008 Precision Data for Atmospheric Concentrations
22
20 -
18 -
16 -
14 -
Overall - 1990 through 2007
nMackville,KY-2008
n Rocky Mtn, CO - 2008
Table 5-1 Data Quality Indicator Criteria for CASTNET Laboratory Measurements
Analyte
Ammonium (NH^)
Sodium (Na+)
Potassium (K+)
Magnesium (Mg2+)
Calcium (Ca2+)
Chloride (CI')
Nitrate (NO3)
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
0.006* mg/L
0.003 mg/L
0.006* 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 relative percent difference (RPD) criterion changed from 10 percent to 5
percent at the onset of the CASTNET III 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 I: if(vl or v2 < RL and the absolute value of (v I -v2) 5*RL and RPD < 5%) = OK
Status: one of the conditions is OK = Precision QC Passes
2 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 90-1 10 percent recovery to 95-105 percent for continuing calibration verification spikes
beginning on July 30, 2003. The criterion remains 90-1 10 percent for ICP-AES reference standards.
* Effective September 26, 2007, changed to 0.006 mg/L from 0.003 mg/L for calcium and 0.005 mg/L for potassium
MARPD
SI
S2
k
Where:
: The value for the primary sampler
: The value for the collocated sampler
: The number of pairs of valid data
Percent recovery = SI
jtlOO
RPD
S2
= (si-s:
S1 + S2
Equation 5-1
Equation 5-2
Equation 5-3
For more information on the analytical methods and associated precision and accuracy criteria used for 2007, see the CASTNET QAPP
Revision 4. 1 (MACTEC, 2008c).
CASTNET Annual Report - 2008
-48-
Chapter 5: Data Quality
-------
Historical (1990 through 2007) data for all I I collocated site pairs operated over the history of
the network and the 2008 data for the current collocated sites at Mackville, KY (MCKI3 1/23 I)
and Rocky Mountain National Park, CO (ROM406/206) are provided. The two sites at Rocky
Mountain National Park are operated independently. ROM206 is operated on behalf of EPA and
ROM406 on behalf of NPS. Trace cations and chloride are excluded from this figure but are
shown later in Figure 5-2. The historical results vary from just over 4 percent for particulate
SO24 to more than 12 percent for particulate NO3. The historical MARPD for SO24 met the
criterion for the CASTNET filter pack measurements shown in Table 5-1. The historical results
for SO2 and HNO3 were above the 5 percent criterion but are considered reasonable. The
results for NH4 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 a/., 2009).
The 2008 precision results shown in Figure 5-1 indicate that the MARPD data for MCKI 3 1/23 I
were lower than (i.e., more precise than) the historical results for all five parameters. Four
parameters (SO2, SO24, HNO3, and NH4) met precision criteria. The 2008 results for
ROM406/206 showed better precision than historical results for HNO3, and the result for NH4
met the DQI criteria. The precision criterion for NO3 was not met at either site during 2008.
The precision results were worse for ROM406/206 because of lower concentrations measured
at this site. Overall, the filter pack precision results for 2008 were about the same as the
2007 results.
Historical and 2008 precision statistics for four cations and chloride (G~) are summarized in
Figure 5-2. The historical MARPD statistics for both MCKI31/231 and ROM406/206 did not
meet the DQI criterion of 5 percent. As discussed in earlier CASTNET annual reports
(e.g., MACTEC, 2004 and MACTEC, 2003), the very high historical MARPD for Na+ was the
result of sample bottle contamination. These bottles are no longer purchased. Also, acceptance
testing of the Teflon filters was instituted for the trace cations and CI" in 2003. The 2008
precision results show that CI" met the precision criterion at MCK13 I /23 I, and the results for
the four cations were reasonable. The 2008 precision results for MCKI 3 1/23 I showed some
improvement over the 2007 results. The 2008 precision data for ROM406/206 are somewhat
worse than 2007.
Table 5-2 summarizes 2008 precision results by quarter for the two sets of collocated sites. See
the 2008 Quarterly Data Reports (MACTEC, 2008a; 2008d; 2009a; 2009c) and QA Quarterly
Reports (MACTEC, 2008b; 2008e; 2008f; 2009b) for discussions of quarterly precision data.
CASTNET Annual Report - 2008 ~ 49 ~ Chapter 5: Data Quality
-------
Figure 5-2 Historical and 2008 Precision Data for Cation and CI" Concentrations
Overall - 2000 through 2007
Mackville, KY-2008
0 Rocky Mtn, CO - 2008
Table 5-2 Collocated Precision Results (MARPD) for 2008 Filter Pack Data by Quarter
Site Pairs
MCKI3I/23I,
Quarter 1
Quarter 2
Quarter 3
Quarter 4
2008
ROM406/206,
Quarter 1
Quarter 2
Quarter 3
Quarter 4
2008
S024
KY
1.78
2.01
2.36
2.64
2.20
CO
7.03
6.74
7.76
4.84
6.59
NO,
4.68
13.16
9.40
4.80
8.01
10.22
12.77
17.79
15.66
14.11
NH+4
2.00
1.65
2.38
2.69
2.18
5.82
6.67
7.74
4.40
6.16
Ca2
7.67
12.21
3.78
5.97
7.41
9.08
8.22
11.55
12.88
10.43
Mg2+
4.66
11.67
3.73
3.82
5.97
11.34
11.46
10.26
14.00
11.76
Na+
2.39
8.88
4.10
4.86
5.06
9.05
8.13
10.82
16.72
11.18
K
2.45
6.94
4.39
17.11
7.72
14.60
11.20
7.29
29.56
15.66
HNO3
2.66
3.18
3.91
4.99
3.68
6.45
4.18
8.63
6.77
6.51
S02
1.89
2.86
1.94
4.40
2.77
5.14
8.04
9.25
7.59
7.50
Total
NO,
2.17
4.26
3.25
3.31
3.25
6.73
6.13
8.06
4.65
6.39
cr
5.04
5.04
4.63
4.79
4.87
4.38
5.28
6.70
6.46
5.71
The 2008 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 - 2008
-50-
Chapter 5: Data Quality
-------
Figure 5-3 Precision Results for Laboratory Replicate Samples (2008)
3 -
,0
ll Mil
Nylon Cellulose Teflon Nylon Teflon Teflon Teflon Teflon Teflon Teflon Teflon
SO42- SO42- SO42- NO3- NO3- NH4* Na* K* Mg2* Ca2* Cl-
contributeto SO?
HNO3
Ozone Concentrations
CASTNET QA procedures for the EPA-sponsored O3 analyzers are different from the EPA QA
requirements for State and Local Monitoring Stations (SLAMS) monitoring (EPA, 1998).
However, as discussed in Chapter I, MACTEC is preparing CASTNET monitoring shelters to
meet the 40 CFR Part 58 monitoring requirements. The QA procedures for the O3 analyzers at
the NPS-sponsored CASTNET sites also do not meet the SLAMS requirements, but the NPS
sites utilize the appropriate procedures and equipment, including an on-site O3 transfer
standard. In any event, the operation of the collocated EPA and NPS 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 MCKI3I/23I, KY and ROM406/206, CO during 2008. In addition, quarterly historical
precision statistics were compiled for all collocated sites. Quarterly precision results are
summarized in Figure 5-4. Table 5-4 provides precision results for O3 concentrations by quarter
for 2008. The data show the historical and 2008 results met the 10 percent criterion. The
historical data are based on the operation of I I collocated site pairs over the history of the
network. The 2008 O3 precision data for ROM406/206 were excellent and demonstrate the
comparability of the two independent O3 sampling systems.
CASTNET Annual Report - 2008
Chapter 5: Data Quality
-------
Table 5-3 Data Quality Indicator Criteria for CASTNET Field Measurements
Measi
Parameter
Wind Speed
Wind Direction
Sigma Theta
Relative Humidity
Solar Radiation
Precipitation
Ambient
Temperature
Delta Temperature
Surface Wetness
Ozone
Filter Pack Flow
jrement
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
Crit
Precision
+ 0.5 m/s
+ 5ฐ
Undefined
+ 10% (of full scale)
+ 1 0% (of reading taken
at local noon)
+ 1 0% (of reading)
+ I.OฐC
+ 0.5ฐC
Undefined
+ 1 0% (of reading)
+ 10%
eria*
Accuracy
The greater of + 0.5 m/s for winds <
5 m/s or + 5% for winds > 5 m/s
+ 5ฐ
Undefined
+ 5%, relative humidity > 85%
+ 20%, relative humidity < 85%
+ 10%
+ 0.05 inchf
+ 0.5ฐC
+ 0.5ฐC
Undefined
+ 10%
+ 5%
Note: Mean Absolute Difference (MAD) is the precision measure for difference criteria such as for wind speed.
MARPD is the precision measure for percentage criteria such as for relative humidity.
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.
f For target value of 0.50 inch.
Figure 5-4 Historical and 2008 Precision Data by Quarter for Ozone Concentrations
22
20 -
18 -
16 -
14 -
Overall - 1990 through 2007
nMackville,KY-2008
n Rocky Mtn, CO - 2008
Second
Quarter
Third
Quarter
Fourth
Quarter
CASTNET Annual Report - 2008
-52
Chapter 5: Data Quality
-------
Table 5-4 Collocated Precision Results (MARPD) for 2008 Ozone Concentrations by Quarter
Sampling
Period
Quarter 1
Quarter 2
Quarter 3
Quarter 4
2008
MCK131/231, KY ROM406/206, CO
8.57
6.49
3.91
1.71
1.16
2.90
6.19 1.51
6.29 1.82
Continuous Measurements
Precision criteria for the continuous measurements are listed in Table 5-3. Precision was
calculated in terms of the MARPD or mean absolute difference (MAD) of hourly measurements
collected at all collocated pairs operated over the history of the network and also for
MCKI3I/23I, KYand ROM406/206, CO for 2008. Figure 5-5 provides precision results for
historical data through 2007 and precision statistics for the two collocated sites for 2008. All
historical precision results met the DQI criteria. Table 5-5 gives precision data by quarter for
2008 for the two collocated sites. The results show excellent instrument precision. All 2008
annual and quarterly precision data met the DQI criteria. The first quarter MAD value for wind
direction at ROM 406/206, CO was not available because of invalid data from ROM206, CO
during that quarter. Precipitation measurements were invalid from MCK23 I, KY during the
second and third quarters and delta temperature data were invalid for the second quarter from
ROM406, CO.
Figure 5-5 Historical and 2008 Precision Data for Continuous Measurements
c IU
o
~ 9 -
2 8-
Q
"c
5 6 -
ฃ 5 -
< 4 -
^ 3 -
ฃ 2-
Se 1 -
n
MARPD: Overall - 1 990 through 2007
DMARPD: Mackville,KY-2008
D MARPD: Rocky Mtn, CO - 2008
fl
1
1
-| DM AD: Overall- 1990 through 2007
DMAD: Mac
ฃ ง S S c
K > B n _ S S^S0'
t S % S a.
8 S ง CO
i 11 l! ll l! f 1| ! | |1 1
u_ o:icoi-coa:Qi- o. cos i- 3 so 3
CASTNET Annual Report - 2008
-53-
Chapter 5: Data Quality
-------
Table 5-5 Collocated Precision Results for 2008 Continuous Measurements by Quarter
ฃ
"5
Q.
$
ISl
MARPD
01
3
K
li.
Relative
Humidity
Sigma Theta
Solar
Radiation
MAD
Delta
Temperature
Precipitation
Scalar Wind
Speed
Temperature
Wetness
Wind
Direction
D
01
1
10
u
c
ฃ
MCK 13 1/231, KY
Quarter 1
Quarter 2
Quarter 3
Quarter 4
2008
1.31
9.66
2.22
4.46
4.41
2.87
2.47
0.83
2.03
2.05
2.21
2.97
4.21
2.29
2.92
1.96
3.03
4.33
2.96
3.07
0.34
0.08
0.08
0.26
0.19
0.04
na
na
0.02
0.03
0.10
0.09
0.08
0.05
0.08
0.12
0.09
0.04
0.18
0.11
0.05
0.07
0.05
0.03
0.05
1.32
1.01
1.36
2.60
1.57
0.09
0.08
0.07
0.05
0.07
ROM406/206, CO
Quarter 1
Quarter 2
Quarter 3
Quarter 4
2008
0.90
0.91
1.28
5.33
2.11
8.19
7.51
4.86
9.18
7.44
4.53
4.49
4.74
3.88
4.41
4.59
5.56
3.58
2.65
4.10
O.I 1
na
0.23
0.28
0.21
0.02
0.04
0.01
0.01
0.02
0.28
0.23
0.17
0.20
0.22
0.49
0.35
0.36
0.36
0.39
0.23
0.05
0.09
0.06
O.I 1
na
2.96
4.82
1.66
3.14
0.19
0.15
0.11
0.14
0.15
Accuracy
Laboratory Filter Concentrations
Accuracy of laboratory measurements is assessed through the analysis of reference and
continuing calibration verification (CCV) samples. Reference samples and CCV are procured
from independent suppliers and are traceable to the National Institute of Standards and
Technology (NIST). 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 2008, the CCV were analyzed every
tenth sample to verify that instrument calibration had not drifted beyond established limits.
Table 5-6 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 2008. Table 5-6 corroborates the precision results that were shown in Figure 5-3.
CASTNET Annual Report - 2008
-54-
Chapter 5: Data Quality
-------
Table 5-6 Filter Pack Quality Control Summary for 2008
c
3
o
U
In-Run Replicate2
(RPD)
a
(0
Z
717 0.71
717 1.18
696 0.63
710 1.84
710 1.58
710 1.21
710 1.73
717 1.67
692 1 .58
692 0.87
686 2.3 1
Standard
Deviation
1.29
1.87
0.71
2.90
1.97
2.31
1.90
3.11
1.99
1.07
3.04
"=
3
O
U
331
331
326
332
332
332
332
327
317
317
318
Note: % R = percent recovery (see Equation 5-2)
RPD = relative percent difference (see Equation 5-3)
1 Results of reference sample analyses provide accuracy estimates
2 Results of replicate analyses provide precision estimates
3 Number of QC Samples
Continuous
Table 5-7 presents field accuracy results for 2008 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 87.3 percent and solar radiation at 85.0 percent. However, these results did not adversely
affect data collection because data are not considered invalid unless criteria are exceeded by
more than two times the criterion. Using the two times standard, the two parameters passed
with 98.2 and 98.1 percent frequency, respectively.
CASTNET Annual Report - 2008
-55-
Chapter 5: Data Quality
-------
Table 5-7 Accuracy Results for 2008 Field Measurements
Parameter
Percent Within
Criterion
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
98.3 percent
99.1 percent
98.3 percent
96.6 percent
87.3 percent
99.1 percent
85.0 percent
92.2 percent
92.2 percent
98.2 percent
98.2 percent
100.0 percent
99.1 percent
97.2 percent
98.2 percent
100.0 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 was about
98 percent.
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 5-6 presents historical
(black) and 2008 completeness data for all sites for measured filter concentrations and
continuous measurements and calculated parameters. The figure shows that the 2008 direct
measurements met the 90 percent completeness goal, and five continuous measurements
exceeded 95 percent, including filter pack flow. Atmospheric concentrations also exceeded 95
percent. The four parameters derived from model results exceeded 89 percent completeness
for 2008. Completeness results for 2008 are better than historical results for all parameters
except delta temperature and precipitation.
CASTNET Annual Report - 2008
-56-
Chapter 5: Data Quality
-------
Figure 5-6 Historical and 2008 Percent Completeness of Measurements and Modeled
Estimates (black bars are 1990-2007)
Atmospheric Concentrations
Vector Wind Speed
Scalar Wind Speed
Wind Direction
Sigma Theta
Relative Humidity
Solar Radiation
Meteorological Precipitation
Parameters
Am bient Tern perature
Delta Temperature
Ozone
Filter Pack Flow
Surf ace Wetness
Hourly Flux Estimates
Model Annual Mean Atm. Concentrations
Results Annual Mean Deposition Velocities
Annually Aggregated Flux Estimates
6
1 1
1 1
i
1 1
1 1
1 1
1 1
M ,
1 1
.!
1 1
1 1
1 1
1 1
pr
i
^^^^=
1 1
1 * i !
[ * | DQI Measurement Criterion | *
1 1 1 1
1 1
1 1 1
i ' 1 1
i
i
\
I
1
-i
iiiiPiiiiliiiiliiiiliiiiliiiilii.il
5 70 75 80 85 90 95 100
Percent Completeness
CASTNET Annual Report - 2008
-57-
Chapter 5: Data Quality
-------
Inter laboratory Comparison Results
The MACTEC laboratory is one of eight laboratories that participate in the US 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. The laboratory reported the eight CASTNET parameters for a total of 104
samples during 2008. Results for the 44 synthetically prepared samples are depicted in the
figure below, which presents results as percent recoveries of the median value for
all laboratories.
As shown below, only 3 of 352 reported values were more than 10 percent from their
corresponding median. All values shown are within two standard deviations of their
corresponding median.
Figure 5a Results from Intercomparison of Synthetic and Natural Samples
115
110
>,105
0
ง100
ce
^ 95
90
85
xMg2+
*Na+
NH;
cr
NO3
10
20
30
40
50
Additionally, precision results for the 52 natural wet deposition samples were reported as
absolute percent differences for replicate analyses. None of the paired natural wet
deposition sample data points exceeded 10 percent difference. These results are
presented in the USGS report (USGS, 2008).
The laboratory generally participates in two to three studies each year through
Environment Canada's National Water Research Institute (NWRI) Proficiency Testing
QA Program in addition to interlaboratory comparison studies for the USGS. MACTEC's
laboratory was rated free of systemic bias for all eight parameters for the two NWRI
2008 studies and was tied for first place out of 39 participating laboratories at the end of
2008 (Environment Canada, 2008).
CASTNET Annual Report - 2008
-58-
Chapter 5: Data Quality
-------
Summary of Data Quality Results
DQI results demonstrate that field and laboratory processes were adequately monitored
through QA/QC procedures and were generally free of systemic bias during 2008. Accuracy
data met the established criteria for field and laboratory parameters with the exception of
relative humidity > 85 percent and solar radiation. 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 SO2, SO24, HNO3, and NH^ 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 uncertain nature of the
gas-particle equilibrium of the nitrate species.
The 2008 precision data for O3 concentrations met the 10 percent DQI criterion. The 2008
precision data for ROM406/206 were excellent and demonstrate the comparability of the two
independent O3 sampling systems. Completeness criteria were met for all parameters in 2008.
Completeness results for 2008 were better than historical results for all but two parameters.
The precision of continuous measurements for 2008 was excellent. Quarterly and annual
precision results for 2008 met the DQI criteria.
The laboratory intercomparison results show the CASTNET analytical chemistry laboratory
was rated free of systematic bias and was tied for first place out of 39 participating laboratories
at the end of 2008 in Environment Canada's NWRI Proficiency Testing QA Program.
CASTNET Annual Report - 2008 ~ 59 ~ Chapter 5: Data Quality
-------
References
Air Resource Specialists, Inc. (ARS). 2009. 2008 Data Quality Assurance Report. Prepared for
National Park Service, Denver, CO.
http://www.nature.nps.gov/air/Pubs/pdf/ads/2008DataQualityAssurance.pdf (accessed
November 2009).
Baron, J. S. 2006. Hindcasting Nitrogen Deposition to Determine an Ecological Critical Load.
Ecological Applications, 16(2), 433-439.
Butler, T. J., Likens, G. E., Vermeylen, F. M., and Stunder, B. J. B. 2005. The Impact of Changing
Nitrogen Oxide Emissions on Wet and Dry Nitrogen Deposition in the Northeastern
USA. Atmospheric Environment 39(27):4851-4862.
Butler, T. J., Likens, G. E., Vermeylen, F. M., and Stunder, B. J. B. 2003. The Relation Between
NOX Emissions and Precipitation NO3 in the Eastern USA. Atmospheric Environment
37(I5):2093-2I04.
Environment Canada. 2008. Water Science and Technology Directorate. Proficiency Testing
Program. Rain and Soft Waters PT Studies 0092 and 0093 Report. Prepared for
MACTEC Engineering and Consulting, Inc.
Finkelstein, P.L, Ellestad, T.G., Clarke, J.F., Meyers, T.P., Schwede, D.B., Hebert, E.O., and Neal,
J.A. 2000. Ozone and Sulfur Dioxide Dry Deposition to Forests: Observations and
Model Evaluation. J. Geophys. Res. 105:D 12:15,365-15,377.
Lavery, T.F., Rogers, C.M., Baumgardner, R., and Mishoe, K.P. 2009. Intercomparison of
CASTNET Nitrate and Nitric Acid Measurements with Data from Other Monitoring
Programs. Journal of Air & Waste Management Association (JAWMA) ISSN: 1047-3289,
59:214-226.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2009a. Clean Air Status and Trends
Network (CASTNET) Fourth Quarter 2008 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
CASTNET Annual Report - 2008 ~l~ References
-------
References (continued)
MACTEC Engineering and Consulting, Inc. (MACTEC). 2009b. Clean Air Status and Trends
Network (CASTNET) Fourth Quarter 2008 Quality Assurance Report with 2008 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
MACTEC Engineering and Consulting, Inc. (MACTEC). 2009c. Clean Air Status and Trends
Network (CASTNET) Third Quarter 2008 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). 2008a. Clean Air Status and Trends
Network (CASTNET) First Quarter 2008 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). 2008b. Clean Air Status and Trends
Network (CASTNET) First Quarter 2008 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). 2008c. Clean Air Status and Trends
Network (CASTNET) Quality Assurance Project Plan (QAPP), Revision 4.1. Prepared for U.S.
Environmental Protection Agency (EPA), Research Triangle Park, NC, Contract No.
68-D-98-II2. Gainesville, FL.
MACTEC Engineering and Consulting, Inc. (MACTEC). 2008d. Clean Air Status and Trends
Network (CASTNET) Second Quarter 2008 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). 2008e. Clean Air Status and Trends
Network (CASTNET) Second Quarter 2008 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.
CASTNET Annual Report - 2008 ~2~ References
-------
References (continued)
MACTEC Engineering and Consulting, Inc. (MACTEC). 2008f. Clean Air Status and Trends
Network (CASTNET) Third Quarter 2008 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). 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,]., Ellestad, T.G., and Sims, P.F. 1998. A Multilayer Model
for Inferring Dry Deposition Using Standard Meteorological Measurements. J. Geophys.
Res. 103D17:22,645-22,661.
National Atmospheric Deposition Program (NADP). 2009. Ammonia Monitoring Network
(AMoN). Passive Ammonia Monitoring Network, http://nadp.sws.uiuc.edu/nh3net/
(accessed July 2009).
Nilsson, J. and Grennfelt, P. (Eds). 1988. Critical Loads for Sulphur and Nitrogen. Report from a
workshop held at Skokloster, Sweden, 19-24 March 1988. NORD Miljorapport 1988:
15, Nordic Council of Ministers, Copenhagen, pp. 225-268.
Ray, J.D. 2009. Annual Data Summary 2008: Gaseous Pollutant Monitoring Program. Natural
Resource Data Series, NPS/NRPC/ARD/NRDS - 2009/01 I. National Park Service,
Denver, CO.
Schwede, D.B. 2006. A Comparison of the Deposition Velocity Estimates from the CASTNET and
CAPMoN Networks. (Working paper). Research Triangle Park, NC.
U.S. Environmental Protection Agency (EPA). 2009a. Acid Rain and Related Programs:
2008 Emission, Compliance, and Market Data.
http://www.epa.gov/airmarkets/progress/ARP_2008_ECM_Data.pdf (accessed
August 14,2009).
CASTNET Annual Report - 2008 ~3~ References
-------
References (continued)
U.S. Environmental Protection Agency (EPA). 2009b. Acid Rain and Related Programs: 2007
Progress Report. EPA-430-K-08-OIO, Washington, DC.
http://www.epa.gov/airmarkt/progress/docs/2007ARPReport.pdf (accessed
August 2009).
U.S. Environmental Protection Agency (EPA). 2009c. NOX Budget Trading Program: 2008
Emission, Compliance, and Market Analyses.
http://www.epa.gov/airmarkets/progress/NBP_2/NBP_2008_ECM_Analyses.pdf
(accessed August 14, 2009).
U.S. Environmental Protection Agency (EPA). 2009d. "Transfer Standards for the Calibration
of Ambient Air Monitoring Analyzers for Ozone." Draft Technical Assistance
Document, EPA-OAQPS, Research Triangle Park, NC.
U.S. Environmental Protection Agency (EPA). 2008a. National Ambient Air Quality Standards
for Ozone; Final Rule, Federal Register 73, no. 60 (March 2008). EPA-HQ-OAR-2005-
0172.
U.S. Environmental Protection Agency (EPA). 2008b. Quality Assurance Handbook for Air
Pollution Measurement Systems, Volume II, Ambient Air Quality Monitoring Program.
EPA-454/B-08-003.
U.S. Environmental Protection Agency (EPA). 2000. National Air Quality and Emissions
Trends Report, 1998. EPA-454-R-00-003. OAQPS, RTP, NC 2771 I.
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). 2008. Office of Water Quality. Branch of Quality Systems.
Interlaboratory Comparison Program
http://bqs.usgs.gov/precip/new/frontpage_home.htm (accessed July 28, 2008).
CASTNET Annual Report -2008 ~4~ References
-------
Appendix A
Locational and Operational Characteristics of CASTNET Sites
CASTNET Annual Report - 2008 Appendix A
-------
Table A-1 Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
3
C1 ฃ ^
a. TJ o *^ C
c3 "tS o irr1 u S o !
.ฃ2 W Q HM V 55 JJj ^4 *
^5 hJ hJ t^ C3 C^ ^5 r^J C^
o
I
"a 5
a %
a3 ง" aj
H ซ
i
ฐ
I fl
\ a
! 1
Alabama
SND152
Sand Mountain
12/27/88 34.2894 85.9704 352 Agri.
Rolling Y
EPA
Alaska
DEN417
Denali National Park and Preserve
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 32.0092 109.3892 1570 Range
05/16/89 36.0597 112.1822 2073 Forested
09/24/02 34.8225 109.8919 1723 Desert
Complex N
Complex M
Flat Y
NPS
NPS
NPS
Arkansas
CAD150
Caddo Valley
10/04/88 34.1792 93.0989 71 Forested
Rolling N
EPA
California
CON186
JOT403
LAV410
PIN414
SEK430
YOS404
Converse Station
Joshua Tree National Park
Lassen Volcanic National Park
Pinnacles National Monument
Sequoia National Park
Yosemite National Park
06/17/03 34.1941 116.9130 1837 Agri./Forested
02/16/95 34.0714 116.3906 1244 Desert
07/25/95 40.5403 121.5764 1756 Forested
05/16/95 36.4850 121.1556 335 Forested
04/07/05 36.4894 118.8269 457 Forested
09/25/95 37.7133 119.7061 1605 Forested
Complex N
Complex M
Complex M
Complex M
Mountaintop N
Complex N
EPA
NPS
NPS
NPS
NPS
NPS
CASTNET Annual Report - 2008
Appendix A
-------
Table A-1 Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
Ol
0 ซ ฃ
^ & s-^ % f, "ฐ
ฃ g E >> a
! 1 ! I i i! i
73 S S -H ป> 01 0 03
s -s g> > ง.-* ง 2 s
to -J -J w Q Q. O ^ a.
g
Ol
H
3resentative to
MLM3
ซ y
X -S
0
ft
a
&
to
Colorado
GTH161
MEV405
ROM206
ROM406
Gothic
Mesa Verde National Park
Rocky Mountain National Park
Rocky Mountain National Park
05/16/89 38.9573 106.9854 2926 Range
01/10/95 37.1983 108.4903 2165 Forested
07/03/01 40.2778 105.5453 2743 Forested
12/20/94 40.2778 105.5453 2743 Forested
Complex
Complex
Complex
Complex
N
M
M
M
EPA
NPS
EPA
NPS
Connecticut
ABT147
Abington
12/28/93 41.8402 72.0111 209 Urban-Agri.
Rolling
M
EPA
Florida
EVE419
IRL141
SUM156
Everglades National Park
Indian River Lagoon
Sumatra
10/06/98 25.3911 80.6806 2 ซ4 Swamp
07/09/01 30.1065 80.4554 2 Beach
12/28/88 30.1065 84.9938 14 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 38.8690 89.6229 164 Agri.
02/09/88 40.0520 88.3725 212 Agri.
12/28/93 42.2872 89.9998 274 Agri.
Flat
Flat
Rolling
Y
Y
M
EPA
EPA
EPA
CASTNET Annual Report - 2008
Appendix A
-------
Table A-1 Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
S
03
a
ฃ
-S
to
ฃ
O
4>
o
3
3
s.
^"\ 1*
t I 1
8 ^ I
3 .2 ซ
tS " ฐ5
a I 8.^
O
-------
Table A-1 Locational and Operational Characteristics of CASTNET Sites
Site ID Site Name
^ ^
z s.^
u S-, u
*^ QJ "^
1 1 t
- 'S gj
1 3 J
Elevation (m)
*" bfj
ฐS U o 03
O ^ fl 4ป g
Terrain
Representative to
the MLM3
0
ft
a
O
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
Forested
Forested
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 - 2008
Appendix A
-------
Table A-1 Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
Start date
Latitude (ฐN)
Longitude (ฐW)
Elevation (m)
*" bfj
ฐS U o 03
o j^ a i> a
& ^ o *^ ^
Q &> & ซl ฃ
_a
01
H
o
Representative
the MLM3
0
ft
a
O
o.
to
New York
CAT175
CTH110
HWF187
Claryville
Connecticut Hill
Huntington Wildlife Forest
05/10/94
09/28/87
05/28/02
41.9423
42.4010
43.9732
74.5519
76.6535
74.2232
765
515
502
4| 5 Forested
Forested
Forested
Complex
Rolling
Complex
N
N
N
EPA
EPA
EPA
North Carolina
BFT142
CND125
COW137
PNF126
Beaufort
Candor
Coweeta
Cranberry
12/28/93
09/25/90
11/04/87
12/27/88
34.8843
35.2643
35.0605
36.1040
76.6213
79.8382
83.4302
82.0448
2
198
686
1250
Agri.
Forested
Forested
Forested
Flat
Rolling
Complex
Mountaintop
Y
M
N
M
EPA
EPA
EPA
EPA
North Dakota
THR422
Theodore Roosevelt National Park
10/06/98
46.8947
103.3778
850
Range
Rolling
Y
NPS
Ohio
DCP114
LYK123
OXF122
QAK172
Deer Creek State Park
Lykens
Oxford
Quaker City
09/28/88
01/10/89
08/18/87
09/28/93
39.6358
40.9169
39.5314
39.9431
83.2600
82.9981
84.7231
81.3378
267
303
284
372
Agri.
Agri.
Agri.
Agri.
Rolling
Flat
Rolling
Rolling
Y
M
N
M
EPA
EPA
EPA
EPA
Oklahoma
CHE185
Cherokee Nation
04/02/02
35.7507
94.6700
299
Agri.
Rolling
Y
EPA
Ontario
EGB181
Egbert, Ontario
12/27/94
44.2317
79.7840
251
ซ4 Agri.
Rolling
Y
EPA
CASTNET Annual Report - 2008
Appendix A
-------
Table A-1 Locational and Operational Characteristics of CASTNET Sites
Site ID
Site Name
Start date
Latitude (ฐN)
Longitude (ฐW)
Elevation (m)
o
*" bfj
a -a | j
3 ง "g ฃ>
'x O> O 03
o -ฃ & Q a
_a
01
H
o
Representative
the MLM3
0
a
o
o.
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
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
Agri.
Rolling
Complex
Rolling
N
N
Y
EPA
NPS
EPA
Texas
ALC188
BBE401
PAL190
Alabama-Coushatta
Big Bend National Park
Palo Duro Canyon State Park
04/02/04
07/18/95
04/24/07
30.4210
29.3022
34.8803
94.4045
103.1772
101.6649
101
1052
1050
Forested
Forested
Prairie
Rolling
Complex
Complex
Y
M
M
EPA
NPS
EPA
Utah
CAN407
Canyonlands National Park
01/24/95
38.4586
109.8211
1809
Desert
Complex
M
NPS
CASTNET Annual Report - 2008
Appendix A
-------
Table A-1 Locational and Operational Characteristics of CASTNET Sites
Site ID Site Name
o
1 ^
1 3
1 ซ
ED -J
*"" bfj
^ ^ 5 <=
x "" Nฃ" bn C?
QJ C O taJ
3 a 2 a "S ^,
3 .2 S a 2 &
a | s-i- a s ง
a ฃ 0.-3 o ซ .S
o
o>
ซ ง o>
H X -S
-
0
a
o
o.
Virginia
PED108 Prince Edward
SHN418 Shenandoah National Park
VPI120 Morton Station
11/03/87 37.1653
06/28/88 38.5231
06/02/87 37.3300
78.3070 150 Forested
78.4347 1073 Forested
80.5573 920 Forested
Rolling M
Mountaintop M
Mountaintop N
EPA
NPS
EPA
Washington
MOR409 Mount Rainier National Park
08/29/95 46.7583
122.1244 415 Forested
Complex N
NPS
West Virginia
CDR119 Cedar Creek State Park
PAR107 Parsons
11/10/87 38.8794
01/19/88 39.0906
80.8478 234 Forested
79.6614 510 Forested
Complex N
Complex N
EPA
EPA
Wisconsin
PRK134 Perkinstown
09/27/88 45.2066
90.5972 472 Agri.
Rolling M
EPA
Wyoming
CNT169 Centennial
PND165 Pinedale
YEL408 Yellowstone National Park
08/19/91 41.3722
12/27/88 42.9214
06/26/96 44.5597
1 . The dry deposition filters are analyzed for the following constituents!
Teflon = SO2, NO3, NH*4, Cl", K+, Na+, Mg2*, Ca2*
Nylon = SO2, NO; (reported as HNO3)
Cellulose = 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.
106.2422 3178 Range
109.7900 2388 Range
110.4006 2400 Forested
3. N = No; Y = Yes; M = Marginal.
4. O3 not measured.
5. Solar-powered site.
Indicates current monitoring.
100 and 200 series = EPA-
400 series = NPS-
Complex M
Rolling M
Rolling N
Operated Sites
Operated Sites
EPA
EPA
NPS
CASTNET Annual Report - 2008
7~
Appendix A
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Appendix B
Acronyms and Abbreviations
CASTNET Annual Report - 2008 Appendix 8
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List of Acronyms and Abbreviations
AGL above ground level
AMoN Ammonia Monitoring Network
ANC acid neutralizing capacity
AQS EPA's Air Quality System
ARP Acid Rain Program
Ca2+ particulate calcium ion
CAAA Clean Air Act Amendments
Ca(N03)2 calcium nitrate
CAIR Clean Air Interstate Rule
CMAQ Community Multiscale Air Quality
CAPMoN Canadian Air and Precipitation Monitoring Network
CASTNET Clean Air Status and Trends Network
CCV continuing calibration verification samples
CDX AQS Central Data Exchange
CI" particulate chloride ion
CO carbon monoxide
DMC Data Management Center
DQI data quality indicator
EAC Early Action Compact areas
ECU electric generating unit
EPA U.S. Environmental Protection Agency
EDT Eastern Daylight Time
H2S04 sulfuric acid
HN03 nitric acid
HYSPLIT Hybrid Single-Particle Lagrangian Integrated Trajectory
1C ion chromatography
ICP-AES inductively coupled plasma-atomic emission spectrometry
IMPROVE Interagency Monitoring of Protected Visual Environments
IP Internet protocol
K+ particulate potassium ion
K2C03 potassium carbonate
kg/ha/yr kilograms per hectare per year
km kilometer
LAI leaf area index
Ipm liters per minute
LTM Long-Term Monitoring program
m meters
MACTEC MACTEC Engineering and Consulting, Inc.
MACT Maximum Available Control Technology
MAD mean absolute difference
CASTNET Annual Report - 2008 ~ / ~
Appendix 8
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List of Acronyms and Abbreviations (continued)
MADPro Mountain Acid Deposition Program
MARCH Maryland Aerosol Research and Characterization
MARPD mean absolute relative percent difference
MDN Mercury Deposition Network
Mg2+ particulate magnesium ion
mg/l milligrams per liter
MLM Multi-Layer Model
N nitrogen
Na+ particulate sodium ion
NAAQS National Ambient Air Quality Standards
NADP National Atmospheric Deposition Program
NaN03 sodium nitrate
NAPAP National Acid Precipitation Assessment Program
NBP NOX Budget Trading Program
NDDN National Dry Deposition Network
NH3 ammonia
NH4 particulate ammonium
NH4N03 ammonium nitrate
(NH4)2S04 ammonium sulfate
NIST National Institute of Standards and Technology
N03 particulate nitrate
NOX nitrogen oxides
NOAA National Oceanic and Atmospheric Administration
NPS National Park Service
NTN National Trends Network
NWRI Environment Canada's National Water Research Institute
03 ozone
OTC Ozone Transport Commission
PM2.s fine particle matter
ppb parts per billion
ppm parts per million
QA quality assurance
QAPP Quality Assurance Project Plan
QC quality control
RACT Reasonably Available Control Technology
RPD relative percent difference
S sulfur
SIP State Implementation Plan
CASTNET Annual Report - 2008
Appendix 8
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List of Acronyms and Abbreviations (continued)
SLAMS State and Local Monitoring Stations
S02 sulfur dioxide
S024 particulate sulfate
TIME Temporally Integrated Monitoring of Ecosystems
total N03 gaseous nitric acid (HN03) + particulate nitrate (N03)
u,g/m3 micrograms per cubic meter
USGS U.S. Geological Survey
Vd deposition velocity
VOCs volatile organic compounds
z/s/p zero/span/precision
CASTNET Annual Report - 2008 ~3~ Appendix 8
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For More Information:
U.S. Environmental Protection Agency
Office of Air and Radiation
Clean Air Markets Division
Washington, DC
On the Web:
CASTNET Home Page:
Clean Air Markets
Division Home Page:
EPA Home Page:
www.epa.gov/castnet
www.epa.gov/airmarkets
www.epa.gov
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