Clean Air Status and Trends Network (CASTNET)
Quarterly Data Summary for Second Quarter 2022 (April through June)
Prepared for: U.S. Environmental Protection Agency (EPA), Clean Air Markets Division
EPA Contract No.: 68HERH21D0006, CASTNET Base Program (1003)
Prepared by: Wood Environment & Infrastructure Solutions, Inc. (Wood), Gainesville, Florida
Wood Project No.: 6064226103
Submitted: September 29, 2022
Introduction
This quarterly report summarizes the Clean Air Status and Trends Network (CASTNET) data
collected during second quarter 2022. Trends in pollutants measured at eastern and western
reference sites are shown. Results from the quality assurance/quality control (QA/QC) program are
presented for second quarter data and include completeness and precision of filter concentrations
and hourly 03 concentrations. This report also analyzes data for continuous, trace-level NOy from
eight sites and continuous S02 concentrations from three sites. Other QC statistics are given in the
CASTNET Second Quarter 2022 Quality Assurance Report (Wood, 2022).
Figure 1. Fourth Highest Daily Maximum 8-hour Average 03 Concentrations (ppb) through
Second Quarter 2022
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 1 shows fourth highest daily maximum 8-hour average (DM8A) 03 concentrations measured
through second quarter 2022. Four sites exceeded the 0.070 parts per million (ppm) National
Ambient Air Quality Standard for 03.
Trends
Trend analyses were performed based on filter pack pollutant concentrations measured in
micrograms per cubic meter (|jg/m3) of air at the 34 eastern and 16 western reference sites during
second quarter. Trends in quarterly mean filter pack and 03 concentrations are shown using box
plots in Figures 2 through 13.
Second Quarter Concentrations
Quarterly mean HN03, NH4, total N03, S02, S024, Ca2+, and K+ concentrations decreased at eastern
sites in 2022, and N03, CI , Mg2+, and Na+ concentrations increased. Quarterly mean HN03, NH4,
total N03, and S02 concentrations decreased at western sites in 2022 while N03, S024, CI - Ca2+, K+,
Mg2+, and Na+ concentrations increased.
Quarterly 03 concentrations were analyzed using box plots constructed by averaging all valid
hourly 03 concentrations within second quarter 2022 by site and then averaging those averages for
all eastern and western reference sites (Figure 13). The figure shows an overall reduction in
quarterly mean 03 concentrations at eastern and western sites and a slight increase in 2022 levels
at eastern sites. Quarterly mean concentrations were higher at the western reference sites than at
the eastern sites.
The box plots show an especially significant increase in Ca2+ and Mg2+ concentrations (Figures 9
and 11) at western reference sites. These two cations are measures of particulate matter (PM) in
atmosphere. Figure 14 provides a map of quarterly mean Ca2+ concentrations. The high cation
concentrations are attributed to wildfires, drought, and incursion of Saharan dust. In 2022, wildfires
occurred earlier than usual in the West and covered the most area since 2018. Wildfires produce
large amounts of PM that affect air quality. The Southwest, California, and parts of the Northwest
have been mired in a major drought for more than 20 years, influenced by climate change. While
this drought has improved or worsened at times, the last two years have been particularly dry for
the West. Drought conditions expose farmland and soil to wind erosion and produce fugitive dust,
which, in turn, affects air quality. About 100 million tons of dust from the Sahara Desert are
transported out over the Atlantic each year. The Saharan dust plumes are frequently visible in
satellite photos, e.g., NASA MODIS. The dust contributes to air pollution and yet can provide
natural fertilizer. Seasonal wind patterns can transport the dust from Africa to the Caribbean and
the Gulf of Mexico. Plumes of Saharan dust reached Florida, Texas, and other southern U.S. states in
spring 2022.
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 2. Trends in Second Quarter Mean UNO, Concentrations
Western Reference Sites
Eastern Reference Sites
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Figure 3. Trends in Second Quarter Mean NO, Concentrations
Western Reference Sites
Eastern Reference Sites
1.0
0.8-
0.6
0.4
0.2-
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90th Percentile
75th Percentile
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Figure 4. Trends in Second Quarter Mean NHt Concentrations
Western Reference Sites
Eastern Reference Sites
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 5. Trends in Second Quarter Mean Total NCK Concentrations
Western Reference Sites
Eastern Reference Sites
90th Percentile
75th Percentile
Mean
Median
25th Percentile
10th Percentile
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Figure 6. Trends in Second Quarter Mean S02 Concentrations
Western Reference Sites
Eastern Reference Sites
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75th Percentile
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Figure 7. Trends in Second Quarter Mean SO. Concentrations
Western Reference Sites
Eastern Reference Sites
2.0
1.5
1.0
0.5
0.0
90th Percentile
75th Percentile
Mean
Median
25th Percentile
10th Percentile
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 8. Trends in Second Quarter Mean CI Concentrations
Western Reference Sites
Eastern Reference Sites
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75th Percentile
Mean
Median
25th Percentile
10th Percentile
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Figure 9. Trends in Second Quarter Mean Ca" Concentrations
Western Reference Sites
Eastern Reference Sites
90th Percentile
75th Percentile
Mean
Median
25th Percentile
10th Percentile
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90th Percentile
75th Percentile
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Median
25th Percentile
10th Percentile
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Figure 10. Trends in Second Quarter Mean K+ Concentrations
Western Reference Sites
Eastern Reference Sites
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0.05-
0.00-
90th Percentile
75th Percentile
Mean
Median
25th Percentile
10th Percentile
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 11. Trends in Second Quarter Mean Mg2+ Concentrations
Western Reference Sites
Eastern Reference Sites
90th Percentile
75th Percentile
Mean
Median
25th Percentile
10th Percentile
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Figure 12. Trends in Second Quarter Mean Na+ Concentrations
Western Reference Sites
Eastern Reference Sites
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0.3-
0.2
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90th Percentile
75th Percentile
Mean
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25th Percentile
10th Percentile
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75th Percentile
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25th Percentile
10th Percentile
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Figure 13. Trends in Second Quarter Mean 03 Concentrations
Western Reference Sites
Eastern Reference Sites
90th Percentile
75th Percentile
Mean
Median
25th Percentile
10th Percentile
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Figure 14. Quarterly Mean Ca2+ Concentrations (|jg/m3) for Second Quarter 2022
Changes in 3-year Average Second Quarter Concentrations
Three-year averages of quarterly mean concentrations of total N03, NH4, S02, S024, and 03 were
reduced over the period 1990-1992 through 2020-2022 for eastern reference sites (Table 1) and
1996-1998 through 2020-2022 for western reference sites (Table 2). Ca2+, K+, and Mg2+ levels
declined at eastern sites from 2004-2006 through 2020-2022 while CI and Na+ values increased.
At western sites, CI and all base cation concentrations increased.
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CASTNET Quarterly Data Summary - Second Quarter 2022
Table 1. Eastern Reference Sites: 3-Year Mean 03, Nitrogen, Sulfur, Base Cations, and CI Pollutant
Concentrations
1990-1992
2004-2006
2020-2022
Percent
Parameter
(Mg/m3)
(|jg/m3)
(|jg/m3)
Change
03 (ppb)
41
35
-15
Total N03
3.1
1.1
-65
nh;
2.0
0.4
-82
SO,
6.5
0.4
-94
so24
6.1
1.0
-84
Ca2+
0.32
0.27
-17
K+
0.08
0.07
-12
Mg2+
0.06
0.05
-11
Na+
0.11
0.12
7
cr
0.04
0.08
73
Note: Ozone concentrations are given as ppb. Concentrations for all other parameters are in Mg/m3 •
Table 2. Western Reference Sites: 3-Year Mean 03, Nitrogen, Sulfur, Base Cations, and CI Pollutant
Concentrations
1996-1998
2004-2006
2020-2022
Percent
Parameter
(Mg/m3)
(Mg/m3)
(Mg/m3)
Change
03 (ppb)
49
45
-7
Total N03
1.1
0.7
-37
nh;
0.3
0.2
-41
SO,
0.5
0.2
-58
sot
0.9
0.6
-35
Ca2+
0.23
0.31
31
K+
0.05
0.05
7
Mg2+
0.04
0.05
17
Na+
0.14
0.17
22
cr
0.06
0.13
97
Note: Ozone concentrations are given as ppb. Concentrations for all other parameters are in Mg/m3 •
Time Series of Laboratory Analysis Parameters for All Sites
Figures 15 through 25 give time series of laboratory-analyzed concentrations of field samples and
field blanks in milligrams per liter (mg/L) of 11 parameters from July 2019 through July 2022 These
figures provide indications of potential issues with concentration measurements relative to
detection and reporting limits.
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Figure 15. Concentrations of NO. (as N) from Nylon Filters
•v* q^ q^ q^ q^ q^ q1^ q^ q*^ q^ q^ q^- q^ q^ q^ q^ q'V q'Vq'V q*V ql' q'Vq'V q'V
#############################
Note: Nominal reporting limit is 0.008 mg/L.
Figure 16. Concentrations of NO, (as N) from Teflon Filters
•V* "V* •v' ^ />5^ q^ q^ q^ q^ q^ q^ q^ q^ q^ q^ q^ q^> q*^ q*1" q^ q^ q1^ q^ q1^ q1^ q1^ q^ q1^ qNs q'V q'Vq'T- q'VqT'q'Vq'V q*V
Note: Nominal reporting limit is 0.008 mg/L.
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Figure 17. Concentrations of NHj (as N) from Teflon Filters
• All Samples • Median ~ Field Blanks
•v* n5^ q^ q^> q^ q^ ri^ rf^ q^ q^ q^q^ q*^ q*^ q*"- q*^ qN' q'V r/VnV q'Vq'V q^q'"^ q*V
Note: Nominal reporting limit is 0.020 mg/L.
Figure 18. Concentrations of S02 from K2C03-impregnated Cellulose Filters
• All Samples • Median * Field Blanks
K°> n5^ i-3 k5^ n5^ q^ q^ q^ q^ q^ q^ r& r$ rf^ rfc q^r& q^ q^q^ q*^ q^ q*"1 q^ q^ q*^ q*^ q^ q*^ q'Vq'Vq'Vq'Vq'V q'Vq'V q*V
Note: Nominal reporting limit is 0.040 mg/L.
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Figure 19. Concentrations of S024 from Nylon Filters
CASTNET Quarterly Data Summary - Second Quarter 2022
• All Samples • Median ~ Field Blanks
•v* q<> cfc r& rp q^ q^ q^ q^ rf^> c& q*^ q^ q^ q*"" q*^ q^ q^ q^" q^ q^ q^ q^ q'V q'Vq'V q'V q'V q'Vq'V q'V
Note: Nominal reporting limit is 0.040 mg/L.
Figure 20. Concentrations of SO., from Teflon Filters
• All Samples • Median * Field Blanks
Q Q ,„ t* J # M nil - M in,,? mm — 11 n n n iiVim i mi nt mmn-n »mm iim* 1m m» «* m* •
N°> k5^ q^ q^ q^> q^ q^ q^ q^ q^ q^ q^ q^ q*^ q^~ q^ q^ q*^ q1^ q1^ q*^ q*^ q*^ q*^ q^ q'V q'Vq'V q'V q'V q'V q'V q'V
Note: Nominal reporting limit is 0.040 mg/L.
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Figure 21. Concentrations of CI from Teflon Filters
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&& V S«v o<
Note: Nominal reporting limit is 0.020 mg/L.
Figure 22. Concentrations of Cd ' from Teflon Filters
• All Samples • Median * Field Blanks
N°> k5^ k5^ N°> q^ q^ q^ q^ q^ q^> q^ q^ q^ q^ q^ q^ q1^ q*^ q*^ q^ q^ q1^ q*^ q1^ q*^ q^ q^ q^ q'V q'Vq^V q*^ q*^ q^ q^ q^"
§>'S* V NV^QV^ NV ^C,VcK*§>'^ NV &cF<3*&&$>'
Note: Nominal reporting limit is 0.006 mg/L.
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Figure 23. Concentrations of K° from Teflon Filters
• All Samples • Median • Field Blanks
• •! 8
• • \ -Vl*
•* . v* * •
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Note: Nominal reporting limit is 0.006 mg/L.
Figure 24. Concentrations of Mg ' from Teflon Filters
All Samples • Median • Field Blanks
N°> *5^ >3 ^ >>5^ »3 q^ eft q^> q^> q^ q^ q^> q^ q^ q^ q^ q^ q^ q^q*^ q^ q*^ q*1" q^ q^ q^ q^ q*^ q*^ q'V q'Vq'VqT'q'Vn\rq'T-f/V
Note: Nominal reporting limit is 0.003 mg/L.
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 25. Concentrations of Na+ from Teflon Filters
~ All Samples • Median
Field Blanks
k5^ rP rP rp ci^ n*^ n*^ cf^ r/Vf/Vr/V
#######################################
Note: Nominal reporting limit is 0.005 mg/L.
Time Series of Concentration Differences from Co-located Sites
Figures 26 and 27 show times series of concentration differences between the two sets of co-
located sites.
Figure 26. Time Series of Filter Concentration Differences between MCK131 and MCK231, KY
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 27. Time Series of Filter Concentration Differences between ROM406 and ROM206, CO
0.20
CD
0
c
CD
1
c
o
U—'
CO
-t—'
c
CD
O
c
o
O
0.15
3 0.10
§ 0.05
CO
J2 0.00
^ -0.05
^-0.10
E
-0.15
-0.20
cnj
CNI
a>
CNj
CO
Teflon SO2
-Teflon Ca2'
-Nylon SO2
cnj
CNI
CNJ
CNI
C\j
Teflon N03
Teflon Mg2+
-Nylon HN03
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CD
CO
CO
CNj
LO
CNJ
CNI
O
CNJ
CNI
LO LO
Teflon NH*
•Teflon Na+
•Cellulose SO,
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
CNJ
T—
T—
CO
CO
T—
LO
LO
CO
CO
Teflon CI
-Teflon K+
Precision of Filter Pack Concentrations
Table 3 shows mean absolute relative percent differences (MARPD) for concentrations measured at
MCK131/231 and ROM406/206 during second quarter 2022. The MARPD values met the 20 percent
criterion.
Table 3. Precision (MARPD) for Co-located Filter Pack Data during Second Quarter 2022
Total
no3
hno3
no3
NH+4
S02
S024
2+
Ca
» A 2 +
Mg
Na+
K+
CI"
MCK131/231
KY
X(|ag/m3)
1.35
0.83
0.53
0.42
0.41
1.10
0.32
0.06
0.12
0.09
0.05
Y (M-g/m3)
1.35
0.83
0.54
0.42
0.43
1.11
0.32
0.06
0.13
0.09
0.05
MAD
0.04
0.02
0.02
0.01
0.06
0.01
0.01
0.00
0.00
0.01
0.00
MARPD
3.19
2.89
5.05
1.95
14.00
1.34
4.44
5.44
2.99
6.40
1.88
ROM406/206, CO
X (M-g/m3)
0.79
0.41
0.38
0.18
0.14
0.53
0.33
0.05
0.08
0.05
0.03
Y (M-g/m3)
0.81
0.41
0.41
0.18
0.16
0.54
0.33
0.05
0.08
0.06
0.03
MAD
0.04
0.03
0.04
0.01
0.01
0.02
0.02
0.01
0.00
0.01
0.00
MARPD
5.69
11.57
9.73
7.99
10.29
3.93
6.80
12.98
3.29
18.54
3.29
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CASTNET Quarterly Data Summary - Second Quarter 2022
Completeness for Filter Pack Concentrations
Table 4 shows CASTNET sites with less than 90 percent completeness for weekly filter pack concentrations. Comments are included to
provide information on why these sites experienced low data completeness.
Table 4. Sites with less than 90 Percent Data Completeness for Filter Concentrations for Second Quarter 2022 (1 of 2)
Nylon
Teflon
Teflon
Teflon
Nylon
Cellulose
Teflon Minor
Teflon
Site ID
hno3
no3
nh;
sot
sot
SO,
Cations
cr
Comment
EGB181, ON
23
23
23
23
23
23
23
23
The site restarted filter pack sampling on
June 15, 2022.
SAN 189, NE
23
23
23
23
23
23
23
23
Tribal partner decided to pause filter pack
samplinq until October 1, 2022.
ASH135, ME
31
31
31
31
31
31
31
31
Site was mothballed due to EPA's FY2022
budget.
CDR119, WV
31
31
31
31
31
31
31
31
Site was mothballed due to EPA's FY2022
budget.
DCP114, OH
31
31
31
31
31
31
31
31
Site was mothballed due to EPA's FY2022
budget.
PNF126, NC
31
31
31
31
31
31
31
31
Site was mothballed due to EPA's FY2022
budget.
ANA115, Ml
38
38
38
38
38
38
38
38
Site was mothballed due to EPA's FY2022
budget.
CDZ171, KY
38
38
38
38
38
38
38
38
Site was mothballed due to EPA's FY2022
budget.
HWF187, NY
38
38
38
38
38
38
38
38
Site was mothballed due to EPA's FY2022
budget.
PS U106, PA
38
38
38
38
38
38
38
38
Site was mothballed due to EPA's FY2022
budget.
UND002, VT
38
38
38
38
38
38
38
38
Site was mothballed due to EPA's FY2022
budget.
WST109, NH
38
38
38
38
38
38
38
38
Site was mothballed due to EPA's FY2022
budget.
LAV410, CA
54
54
54
54
54
54
54
54
Flow system leak affected six samples
between 5/3/22 and 6/15/22.
PIN414, CA
54
54
54
54
54
54
54
54
Flow system leak affected six samples
between 4/26/22 and 6/7/22.
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CASTNET Quarterly Data Summary - Second Quarter 2022
Table 4. Sites with less than 90 Percent Data Completeness for Filter Concentrations for Second Quarter 2022 (2 of 2)
Nylon
Teflon
Teflon
Teflon
Nylon
Cellulose
Teflon Minor
Teflon
Site ID
hno3
no3
nh;
so24
so24
SO,
Cations
cr
Comment
NEC602, WY
77
77
77
77
77
77
77
77
There was one 2-week sample and one
3-week sample during the quarter.
CAT 175, NY
85
85
85
85
85
85
85
85
Power failures affected two samples.
DEN417, AK
85
85
85
85
85
85
85
85
Flow system leak affected one sample.
Another sample had not been received
by the laboratory in time for this report.
FOR605, WY
85
85
85
85
85
85
85
85
Analyses for one sample were cancelled
due to equipment issues onsite. Flow
data are missing from 7/1/22 forward,
affecting a second sample.
THR422, ND
85
85
85
85
85
85
85
85
One sample was lost in shipping, and the
following sample was not installed due to
blizzard conditions.
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CASTNET Quarterly Data Summary - Second Quarter 2022
Precision of Ozone Concentrations
Time series of co-located hourly 03 concentration differences for second quarter 2022 are provided
in Figures 28 and 29 for MCK131/231 and ROM406/206, respectively. The figures indicate no
consistent bias between the co-located analyzers at these site locations.
Figure 28. Time Series of the Differences in Co-located 03 Concentrations for MCK131/231, KY
4
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EPA Contract No. 68HERH21D0006
CASTNET Quarterly Data Summary - Second Quarter 2022
Table 5 gives MARPD data for 03 data measured at the two co-located sites.
Table 5. Quarterly Precision (MARPD) for Co-located 03 Concentrations
Site Pair
Quarter
Start Date
MARPD
Records
MCK131/231, KY
3
7/1/21
0.8
2082
4
10/1/21
1.0
2086
1
1/1/22
1.1
2046
2
4/1/22
0.6
2066
ROM406/206, CO
3
7/1/21
1.4
2078
4
10/1/21
1.7
2075
1
1/1/22
2.0
1970
2
4/1/22
1.5
1932
Completeness for 03 Concentrations
Calculation of an annual 03 value requires 75 percent completeness. However, calculation of the
3-year design value used for regulatory purposes requires 90 percent completeness. Table 6 shows
CASTNET sites with less than 90 percent completeness for DM8A 03 concentrations. Comments are
provided for these sites.
Table 6. Sites with less than 90 Percent Data Completeness for DM8A Concentrations during
Second Quarter 2022
Percent
Site ID
Completeness
Comments
ASH135, ME
36
Site was mothballed due to EPA's FY2022 budget.
HWF187, NY
41
Site was mothballed due to EPA's FY2022 budget.
WST109, NH
43
Site was mothballed due to EPA's FY2022 budget.
PNF126, NC
43
Site was mothballed due to EPA's FY2022 budget.
CDZ171, KY
43
Site was mothballed due to EPA's FY2022 budget.
DCP114, OH
43
Site was mothballed due to EPA's FY2022 budget.
CDR119, WV
43
Site was mothballed due to EPA's FY2022 budget.
PAL190, TX
74
Most of June was invalidated due to QC failures. The analyzer was
replaced on June 30.
GRB411, NV
77
Data were invalidated from late March to late April for a failed sample
pump.
QAK172, OH
88
Data were invalidated because of site polling issues in early April and
early June.
GRC474, AZ
88
Data were invalidated from late April to early May for a failed sample
pump.
SUM156, FL
89
Data were invalidated because of site polling issues in early May and
analyzer malfunction mid-June. Analyzer was replaced 6/18/22.
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CASTNET Quarterly Data Summary - Second Quarter 2022
Table 7 shows CASTNET sites with less than 90 percent completeness for hourly 03 concentrations.
Comments are provided for these sites. The annual average for each of these sites is included for
reference.
Table 7. Sites with less than 90 Percent Data Completeness for 03 Concentrations
Site ID
Q2 2022
Q3 2021-
Q2 2022
Comments
ASH135, ME
37
82
Site was mothballed due to EPA's FY2022 budget.
HWF187, NY
43
84
Site was mothballed due to EPA's FY2022 budget.
DCP114, OH
43
85
Site was mothballed due to EPA's FY2022 budget.
PNF126, NC
43
84
Site was mothballed due to EPA's FY2022 budget.
WST109, NH
43
84
Site was mothballed due to EPA's FY2022 budget.
CDZ171, KY
43
85
Site was mothballed due to EPA's FY2022 budget.
CDR119, WV
44
79
Site was mothballed due to EPA's FY2022 budget.
PAL190, TX
75
92
Most of June data were invalidated due to QC failures. The
analyzer was replaced June 30.
GRB411, NV
77
92
Data were invalidated late March to late April for a failed
sample pump.
Filter Pack Total Nitrate and Continuous Trace-level NOy Concentrations at Eight CASTNET Sites
Figures 30 through 37 show a comparison of weekly average continuous NOy measurements with
weekly filter pack total N03 concentrations collected at the eight sites with NOy measurements. The
NOy concentrations were consistently higher than the total N03 levels at all sites except for
PND165 during first half of the quarter. The average weekly NOy levels, the weekly total N03
concentrations, and their ratios for the eight sites with available data are shown in Table 8. Ratios of
NOy to total N03 varied from 3.43 at PND165 to 7.65 at PNF126.
Table 8. Summary of Total N03 and NOy Measurements for Second Quarter 2022
Site ID
Elevation
Total NOs (ppb)
NOy (ppb)
Ratio
DUK008, NC
164*
0.47
2.01
4.42
BVL130, IL
213
0.76
4.52
5.23
MAC426, KY
243
0.50
1.95
3.91
HWF187, NY*
497
0.14
0.75
5.77
GRS420, TN
793
0.39
1.46
3.97
PNF126, NC*
1216
0.28
1.29
7.65
PND165, WY
2386
0.15
0.48
3.43
ROM206, CO
2742
0.24
1.10
4.86
Note: * The inlet of the enhanced NOy monitor is located at the top of the 30-meter tower.
+ Site was mothballed due to EPA's FY2022 budget. This summary represents only the first six weeks of the quarter
when sampling was active.
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 31. Comparison of BVL130 Weekly Mean NOy and Total N03 Concentrations
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 32. Comparison of MAC426 Weekly Mean NOy and Total N03 Concentrations
Mean Continuous NOy
Filter Pack Total Nitrate
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 34. Comparison of GRS420 Weekly Mean NOy and Total N03 Concentrations
2.5
Mean Continuous NOy
Filter Pack Total Nitrate
Figure 35. Comparison of PNF126 Weekly Mean NOy and Total N03 Concentrations
Mean Continuous NOy
Filter Pack Total Nitrate
Site mothballed due to EPA's FY2022 budget. 0.6
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CASTNET Quarterly Data Summary - Second Quarter 2022
Figure 36. Comparison of PND165 Weekly Mean NOy and Total N03 Concentrations
Mean Continuous NOy
Filter Pack Total Nitrate
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CASTNET Quarterly Data Summary - Second Quarter 2022
Filter Pack and Continuous Trace-level Gas Sulfur Dioxide Concentrations
Figures 38 through 40 provide diagrams that compare weekly filter pack S02 concentrations with
continuous trace-level gas data measured at BVL130, MAC426, and GRS420. The continuously
measured trace-level concentrations were higher than filter pack concentrations at BVL130 and
were comparable at MAC426 and GRS420.
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CASTNET Quarterly Data Summary - Second Quarter 2022
Completeness for Continuous Trace-level Gas Measurements
Table 9 shows the percent completeness for CASTNET trace-level gas measurements. Comments
are provided for sites with less than 90 percent completeness for hourly trace-level gas
concentrations during second quarter 2022. The average for third quarter 2021 through second
quarter 2022 for each of the sites is included for reference.
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CASTNET Quarterly Data Summary - Second Quarter 2022
Table 9. Percent Data Completeness for Continuous Trace-level Gas Measurements (1 of 2)
Site ID
Parameter*
Q2 2022
Q3 2021 -
Q2 2022
Comments
BVL130, IL
CO
44
52
The CO analyzer experienced QC check failures
in May and June. A loose Ethernet cable was
fixed in July and resolved the issue.
NO
92
89
NOY
92
93
NOYDIF
92
89
S02_GA
91
89
CHC432, NM
NO
97
97
NOX
97
97
NOXDIF
97
97
DUK008, NC
HN03
85
~ Monitoring restarted August 2021, but QC
activities were not fully operational until
December 2021. As a result, the average for Q3
2021 through Q2 2022 was not calculated.
~ The QC check runs for NH3 result in three to
six hours of invalid data every two days for all
parameters.
~ Data for all parameters were invalidated for
4/1/22 to 4/5/22 due to calibration activities.
~ NH3 and TNX had several QC check failures
in June.
NH3
62
NO
85
N02 TRUE
85
NOX TRUE
85
NOY
85
NOY MINUS
85
NOYDIF
85
TNX
62
GRS420, TN
CO
88
85
The CO analyzer failed QC checks in mid-April.
Numerous calibrations and maintenance
checks throughout the quarter also affected
data completeness.
NO
93
88
NOY
93
88
NOYDIF
93
88
S02_GA
93
87
HWF187, NY
NO
40
79
Site was mothballed due to EPA's FY2022
budget.
NOY
40
79
NOYDIF
40
79
MAC426, KY
CO
96
96
NO
97
97
NOY
97
97
NOYDIF
97
97
S02_GA
97
97
PND165, WY
NO
92
86
The analyzer drifted out of calibration in May
and was re-calibrated.
NOY
88
84
NOYDIF
88
84
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CASTNET Quarterly Data Summary - Second Quarter 2022
Table 9. Percent Data Completeness for Continuous Trace-level Gas Measurements (2 of 2)
Q3 2021 -
Site ID
Parameter*
Q2 2022
Q2 2022
Comments
PNF126, NC
NO
38
75
Site was mothballed due to EPA's FY2022
NOY
38
74
budget.
NOYDIF
38
74
ROM206, CO
NO
94
95
NOY
94
95
NOYDIF
94
95
Note: * See Table 10
The parameters listed in Table 9 are both calculated and measured. Table 10 provides information
on how the parameters listed in Table 9 are obtained.
Table 10. CASTNET Trace-level Gas Measurements
Parameter Name
How Obtained
Description of Process
CO
Measured
Gas filter correlation
HN03
Calculated
NOY minus NOY_MINUS
NH3
Calculated
TNX minus NOY
NO
Measured
Chemiluminescence reaction/no converter used
N02_TRUE
Calculated
NOX_TRUE minus NO
NOX_TRUE
Measured
Photolytic converter
NOY
Measured
Molybdenum converter at 315° Celsius
NOYDIF
Calculated
NOY minus NO
NOY_MINUS
Measured
Sodium carbonate denuder followed by molybdenum converter
at 315° Celsius
NOX
Measured
Molybdenum converter at 325° Celsius
NOXDIF
Calculated
NOX minus NO
S02_GA
Measured
Ultraviolet fluorescence
TNX
Measured
Platinum/stainless steel converter at 825° Celsius followed by
molybdenum converter at 315° Celsius
References
Wood Environment & Infrastructure Solutions, Inc. 2022. Clean Air Status and Trends Network
(CASTNET) Second Quarter 2022 Quality Assurance Report.
https://java.epa.gov/castnet/documents.do
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