)
I.
Project Team and Contact Information
I.a.
Principal Investigators: Dr. Johann Engelbrecht (PI), Dr. Alan Gertler (Co-I), Dr. Tony
VanCuren (Co-I)
I.b.
Institution: Desert Research Institute (DRI) with subcontract to University of California
Davis
I.c.
Address: 2215 Raggio Parkway, Reno, NV 89512
I.d.
Phone: (775) 674 7027 Fax: (775) 674 7009 Email: johann@dri.edu
I.e.
Business Manager: Lycia Ronchetti; Phone: (775) 673 7175, Fax: (775) 674 7060, Email:
lycia@dri.edu
I.f.
Project Theme: Theme 6. Cross Cutting All Science Areas. Sub-Theme A. Analyze,
evaluate, and synthesize existing data for any of the theme areas listed above.
II.
Justification Statement
This proposal seeks funding for a Receptor Modeling Study to determine the sources of
observed ambient particulate matter (PM) in the Lake Tahoe Basin. The proposed study addresses the
needs outlined in Theme 6, Sub-theme A of the request for proposals (RFP). In order to accomplish
this goal we will make use of previously collected but never analyzed Lake Tahoe Atmospheric
Depositional Study (LTADS) and Lake Tahoe Source Characterization Study (supported by CARB
and performed by DRI) data sets. A significant amount of resources was expended to perform these
studies but very little use was made of the resultant data. This study will integrate the two data sets
and apply receptor modeling techniques to determine the sources of PM in the basin. This important
result will enable management agencies to develop efficient and effective control strategies to reduce
ambient PM and the resultant deposition of nitrogen (N), phosphorous (P), and sediment to the lake.
Deposition of ambient PM has been implicated as a major source of N, P, and sediment to the
lake. Thus knowledge of the sources contributing to the observed PM is crucial if we are to develop an
approach to reduce the impact of atmospheric deposition on water quality in Lake Tahoe. We propose
to demonstrate that multivariate receptor modeling techniques, including Principal Components
Analysis (PCA), Positive Matrix Factorization (PMF) and Chemical Mass Balance (CMB) can be
successfully applied to previously reported ambient (Chang M.-C. et al., 2005) and source (Kuhns H.
et al., 2004) data sets, in order to assess the sources of air pollution in the Lake Tahoe Basin.
Modeling procedures for future similar source attribution studies will simultaneously be established
and will provide management agencies in the basin with decision making information on the source
types contributing to the observed ambient particulate matter, as well as their relative contributions and
uncertainties. This will include identifying sources of the particulate associated nutrients and sediment
being deposited into the water of the lake, as well as upon the surface soils of the surrounding
mountains.
III.
Background/Problem Statement
To address the issue of atmospheric particulate matter in the Lake Tahoe Basin, the year-long
LTADS was conducted (Chang M.-C. et al., 2005) (Figure 1). For the same reason and to chemically
characterize the major sources within the Tahoe airshed, the parallel DRI Lake Tahoe Source
Characterization Study (Kuhns H. et al., 2004) was undertaken. No follow-up research to close the gap
between the source and ambient sampling and analyses has yet been performed. This is crucial if
agencies in the basin are to develop strategies to reduce the impact of the deposition of ambient
pollutants on Lake Tahoe’s water quality. This proposed study is a logical and much needed extension
of the previously completed ambient and source sampling projects and will include data analysis and
1
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receptor modeling performed on the LTADS and DRI data sets, with the prime goal to identify and
quantify the source types contributing to ambient particulate matter, which is deposited within the
Lake Tahoe Basin
IV.
Goals, Objective(s), and statement of hypotheses to be tested
As stated above, the primary goal of this proposed study is to determine the sources of
observed PM in the Lake Tahoe Basin. This is critical if basin management agencies are to develop
effective strategies to reduce the ambient concentrations of PM and reduce the deposition of this
pollutant to the lake.
Specific objectives include:
•
Analyze the LTADS and DRI data to distinguish sub-sets of site and seasonal data to
assess seasonal trends.
•
Use multivariate statistical procedures, including Principal Components Analysis (PCA)
and Positive Matrix Factorization (PMF) to identify factors and groups of chemical
species of relevance within the measured data set.
•
Compile a set of chemical source profiles applicable to the receptor modeling of the
LTADS ambient results.
•
Apply the CMB receptor model to the LTADS data to determine the sources of the
observed PM.
Hypotheses that will be tested include:
•
Resuspended road dust is the major source of PM10 in the basin.
•
Local residential wood burning is an important source of PM2.5 during the winter
months.
•
Mobile source tailpipe emissions are the major source of PM2.5 in the basin.
•
Secondary pollutants from outside the basin are minor sources of PM2.5 and PM10.
•
Emissions from controlled burns inside the basin and wildfires outside the basin are
minor sources of the observed PM.
•
Emissions from restaurants can be an important source of PM at some locations.
•
Overall, the most important sources to control are emissions related to light-duty motor
vehicles.
•
The major source of phosphorous is from soil sources, while the contribution from
wood burning is small.
•
Phosphorous concentrations in the coarse fraction are elevated and is indicative of
mechanically resuspended soil.
•
Phosphorous from mobile source tailpipe emissions is small.
•
Nitrogen is a minor component of the coarse PM fraction. Hence the PM contribution
to the atmospheric deposition of N is small.
•
Soil is the major contributor to atmospheric sediment deposition to the lake.
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V.
Approach, Methodology, and Geographic Location of Research
This data analysis and receptor modeling study will be on the gravimetry and chemical results
from the two types of ambient samplers:
•
The Two Week Samplers (TWS) operated for 14 consecutive day durations, collecting
integrated samples of total suspended particulates (TSP), PM10 and PM2.5, as well as
nitric acid and ammonia by denuders. The TWS were operated at a nominal flow rate
of 1.3 liters per minute (lpm), from 11/20/02 to 01/06/04, and at five sites chosen by the
California Air Resources Board (CARB) (Fig 1). A total of 127, 129, and 128 of TWS
samples were collected for TSP, PM10, and PM2.5, respectively for the LTADS.
•
The MiniVol samplers equipped with TSP inlets and stationed on lake buoys/piers (four
sites) and on land (non-buoys/piers). Buoy samplers were operated for the duration of
the sampler battery (typically 24 hours) and the duration of the non-buoy samplers’
operation varied, depending on the availability of AC power (~24 hours on batteries and
generally ~1 week with an AC power source). The MiniVol samplers were operated at
a nominal flow rate of 5.0 lpm, from 09/26/02 to 04/26/04. A total of 36 buoy MiniVol
TSP samples, and 160 non-buoy MiniVol TSP samples were collected in the course of
the LTADS.
The Chemical Mass Balance (CMB) receptor model (Friedlander S.K., 1973) is to be applied to
sub-sets of the ambient results from the LTADS, together with the chemical source profiles from DRI
Lake Tahoe Source Characterization Study and the DRI’s source profile data base. We will apply
Version 8.2 of the DRI/EPA CMB receptor model (Coulter C.T., 2004; Watson J.G. et al., 1997) to
apportion major sources of TSP, PM10, and PM2.5. The receptor modeling approach requires accurate
and precise measurements of the chemical composition of emissions from sources that are likely to
contribute to high ambient PM concentrations(Watson J.G. et al., 1998). Source composition profiles
were developed by DRI for various past studies, and comprise the most comprehensive and current set
of profiles available for application in CMB receptor modeling. Source profiles also to be included in
the model are those taken as part of the DRI Lake Tahoe Source Characterization Study (Kuhns H. et
al., 2004).
Approximately 384 sequential, two-weekly ambient aerosol samples (TSP, PM10, PM2.5) for
receptor modeling purposes were collected at five Lake Tahoe Atmospheric Depositional Study sites
To these are added the 196 MiniVol TSP samples, giving s total of 580 ambient samples. Appropriate
source samples, including wood combustion, motor vehicle emissions and re-suspended road dust were
collected at Lake Tahoe, as part of the DRI Lake Tahoe Source Characterization Study (Kuhns H. et
al., 2004). A total of 12 individual PM2.5 residential wood combustion emission samples were
obtained from the following sources: a non-EPA certified woodstove burning juniper (also known as
cedar) and almond at Camp Richardson, CA; an EPA-certified wood-burning stove for kindling and
for steady wood burning at Sierra Nevada College, NV; and a fireplace burning oak and juniper at
Incline Village, NV. Five PM2.5 roadside motor vehicle emission profiles (corrected for road dust)
were collected alongside paved road intersections of Southwood/Mays Blvds and Lakeside/Village
Blvds, during July, 2003. At each of these two sites, grab samples of geological dust were collected
for re-suspension (PM10 and PM2.5) onto filters and analysis. A set of PM10 and PM2.5 samples were
also collected at a downwind Flux Tower alongside Highway 28 near Sand Harbor State Park, during
03/12/2003 to 07/29/2003.
3
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All ambient and source sample sets were chemically analyzed by the DRI’s Environmental
Analysis Facility (EAF). The Teflon filters were analyzed by XRF for Na, Mg, Al, Si, P, S, Cl, K, Ca,
Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, As, Se, Br, Rb, Sr, Y, Zr, Mo, Pd, Ag, Cd, In, Sn, Sb, Ba, La,
Au, Hg, Tl, Pb and U. Water-soluble ions, including Na+, K+ and Ca2+ (by AA), Cl-, NO3-and
SO42- (by IC) and NH4+ (by AC) were analyzed for on quartz fiber filters. The eight carbon species,
OC1, OC2, OC3, OC4, OP, EC1, EC2, and EC3 were analyzed for by TOR, on quartz fiber filters.
For the CMB modeling, the chemical source profiles from the Lake Tahoe Source
Characterization Study, will be complemented by profiles from the DRI’s data base of more than 1000
chemical source profiles of different source types.
Statistical techniques will be applied to the ambient data set so as to assess species means,
standard deviations and correlations, and also identify outliers. Graphical representations of the most
important species will provide information on the seasonal trends over the sampling year as well as
spatial differences amongst the five sites. Multivariate statistical procedures such as Principal
Components Analysis (PCA) (Le Maitre R.W., 1982) and Positive Matrix Factorization (PMF)
(Paatero P. and Tapper, 1994) will be applied so as to better understand the structure of the ambient
data set, and identify seasonal subsets. This will also provide a measure of the variability within the
data set. The factors generated by both PCA and PMF will provide information on chemical source
profiles and chemically similar clusters. These techniques also provide assessments of the chemical
species to be considered for subsequent CMB receptor modeling.
The CMB receptor model will be applied to the ambient samples, in order to provide a source
attribution estimate for each of the sites on each sampling day, and for each of the three measured size
fractions (TSP, PM10, PM2.5). (Figure 2 presents an example of similar CMB results.).
Details of the tasks involved with the project are as follows:
Task 1. Drafting and approval of Technical Work Plan.
Task 2. Initial data analysis to distinguish sub-sets of seasonal and site data that can be
composited. Graphical representations of the most important species can provide information on the
seasonal trends over the sampling year as well as spatial similarities and differences amongst the sites.
Multivariate statistical procedures, including Principal Components Analysis (PCA) and Positive
Matrix Factorization (PMF) identify factors and groups of chemical species of importance within the
measured data set.
Task 3. Compile a set of chemical source profiles applicable to the receptor modeling of the
LTADS ambient results, from DRI Lake Tahoe Source Characterization Study (Kuhns H. et al., 2004),
the DRI’s source profile data base, and other DRI projects.
Task 4. The CMB receptor model (Watson J.G. et al., 1997) will be applied to monthly and
other selected groups of ambient samples from each site, as identified under Task 2.
Task 5. All results, conclusions and recommendations are to be compiled into a Draft Report,
and after sponsor’s review into a Final Report.
Task 6. Project management to include meetings, visits, presentations, conference calls and
general project management tasks.
4
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VI.
Deliverables/Products
The products per task are described in the previous section. Towards the end of the year long
study a Draft Report on the study will be submitted to the sponsors, and after their review will be
followed by a Final Report. The reports will document the results from data analysis, including tables
and charts of the PCA and PMF analyses. Tables of the chemical source profiles applied in the study,
as well as pie-plots of the CMB results will be included in the body of the report, while appendices will
contain the tabulated results.
This proposed study will provide basin management agencies and the public with a better
understanding of the major sources of PM as well as their contribution to the pollutant levels in the
Lake Tahoe air basin. Of importance is the knowledge of what proportion and from which sources the
PM originates.
Information on PM levels at each of the sampling sites as well as seasonal variations will be
provided. It may be of interest to know what proportion of the pollution comes from residential wood
combustion during winter, or if road dust makes a large contribution to the summer aerosol and water
clarity. Comparisons amongst the sampling sites can be drawn. For example, it can be expected that
motor vehicle emissions and road dust will be less at Big Hill than at the four in-basin sites. A
question of importance is to establish how much of the nutrients such as phosphates and nitrates are
carried by aerosols being generated within or outside the basin. This study will highlight the local
sources of particulates, in contrast to remote sources that have the potential of landing in the lake.
The report will provide necessary information to take better decisions towards remediation. In
order to effectively manage the air quality in the Lake Tahoe Basin, the measurement of and
contributions from various particulate source types such as wood smoke, mobile sources, and road
dust. Any remediation strategy will rely on identifying and quantifying the source types. This study
will answer many of the questions required for a control strategy to be included in an environmental
management plan. Procedures developed from this receptor modeling project can be applied in future
development planning. Receptor modeling will provide a measure of source-types contributing to the
deteriorating visibility in the ambient atmosphere as well as to the deteriorating clarity of Lake Tahoe.
Improvements or otherwise over time can be assessed by regular ambient air sampling and CMB
receptor modeling, as is proposed here.
VII.
Schedule of Events/Reporting and Deliverables
A schedule for tasks to be performed and reports/deliverables is provided in the attached Table
1.
VIII. Budget
The proposed budget is presented in Table 2, as per the requested categories. The total
requested amount is $94,918.
IX.
Abbreviated CV(s)
Abbreviated CVs for Drs. Johann Engelbrecht, Alan Gertler, and Tony VanCuren are attached.
References
CARB, 2003, Lake Tahoe atmospheric deposition study interim report: Sacramento, CA, Research
Division California Air Resources Board, p. 98.
5
)
Chang M.-C., J.C.Chow, S.Kohl, Voepel, H., and J.G., W., 2005, Sampling and analysis for the Lake
Tahoe atmospheric deposition study: Reno, Nevada, Desert Research Institute, p. 81.
Coulter C.T., 2004, EPA-CMB8.2 Users Manual: Research Triangle Park, NC.
Engelbrecht J.P., Green, M., H, H. K., and Tropp, R., 2005, Source apportionment analysis of air
quality monitoring data: Phase II Prepared for the Mid-Altlantic/Northeast Visibility Union
(MANE-VU) by the Desert Research Institute, Reno, NV, p. 71.
Engelbrecht J.P., and Kohl, S. D., 2004, Pinal County Source Apportionment Study in Staff, P. C. A.
Q., ed.: Florence, Arizona, Pinal County Air Quality Control District, p. 55-78.
Friedlander S.K., 1973, Chemical element balances and identification of air pollution sources.:
Environmental Science and Technology, v. 7, p. 235-240.
Kuhns H., Chang, M.-C., Chow, J. C., Etymezian, V., Chen, L.-W. A., Nussbaum, N.,
Nathagoundenpalayam, S. K. K., Trimble, D., MacLaren, M., M.Abu-Aliban, Gillies, J., and
Gertler, A., 2004, DRI Lake Tahoe source characterization study: Final report: Sacramento,
CA, Report prepared for California Air Resources Board (CARB) by the Desert Research
Institute, Reno, NV, p. 138.
Le Maitre R.W., 1982, Numerical petrology, Statistical interpretation of geochemical data, Elsevier
Scientific, 281 p.
Paatero P., and Tapper, U., 1994, Positive matrix factorization: A non-negative factor model with
optimal utilization of error estimates of data values: Environmetrics, v. 5, p. 111-126.
Watson J.G., Robinson, N. F., Fujita, E. M., J.C.Chow, T.G.Pace, Lewis, C., and Coulter, T., 1998,
CMB8 applications and validation protocol for PM2.5 and VOCS: Reno NV, Desert Research
Institute.
Watson J.G., Robinson, N. F., Lewis, C., and Coulter, T., 1997, Chemical Mass Balance Receptor
Model Version 8 (CMB8) User's Manual: Reno, NV, p. 56.
Attachments
Figure 1. Site locations for TWS and MiniVol samplers during the Lake Tahoe Atmospheric
Deposition Study (LTADS) (from California Air Resources Board).
Figure 2. Example from Pinal County, AZ of CMB receptor modeling output (Engelbrecht J.P. and
Kohl, 2004). Soil = agricultural and dirt road dust, Feedlot = Feedlot dust, MvEmi = motor vehicle
emissions, VgBrn = vegetative burning smoke, ColPP = coal fired power plant emissions, AmSulf =
secondary ammonium sulfate, AmNitr = secondary ammonium nitrate, Other = unaccounted sources
Table 1. Proposed Schedule for the Lake Tahoe Source Attribution Study.
Table 2. Proposed Budget for the Lake Tahoe Source Attribution Study.
Resumes
Johann Engelbrecht
Alan Gertler
Tony VanCuren
6
)
Lake Tahoe Atmospheric Deposition Study
Map of LTADS Sites with TWS & MVS Sampling Identified
10
9
8
11
8
14
7
14
14
17 (2)
12
14
16
6
5
14
4
3
1
2
13
1. Big Hill
2. Echo Summit
3. Tahoe Airport
4. SLT-Sandy Way
5. SLT - SOLA
6. DL Bliss SP
7. Tahoe City
8. Lake Forest
9. Incline Village – AQ
10. Incline Village – Met
11. Thunderbird Lodge
12. Cave Rock SP
13. Stateline Harvey
14. Buoys/Piers
15. Grass Valley
16. TDR2
17. Wallis Tower & Pier
(Ward Lake Level)
LTADS SITE
MINI-VOLUME SAMPLER
TWO-WEEK SAMPLER
Figure 1. Site locations for TWS and MiniVol samplers during the Lake Tahoe Atmospheric
Deposition Study (LTADS) (from California Air Resources Board).
7
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Pinal County Housing PM10
5.6%
Pinal County Housing PM2.5
2.9%
2.0%
2.9%
3.0%
19.5%
67.0%
Soil
Feedlot
MvEmi
VgBrn
ColPP
AmSulf
AmNitr
Other
PM10 60ug/m3
6.7%
17.1%
50.0%
7.2%
8.3%
7.8%
PM2.5 25ug/m3
Figure 2. Example from Pinal County, AZ of CMB receptor modeling output (Engelbrecht J.P.
and Kohl, 2004). Soil = agricultural and dirt road dust, Feedlot = Feedlot dust, MvEmi = motor
vehicle emissions, VgBrn = vegetative burning smoke, ColPP = coal fired power plant emissions,
AmSulf = secondary ammonium sulfate, AmNitr = secondary ammonium nitrate, Other =
unaccounted sources
8
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Table 1. Proposed Schedule for the Lake Tahoe Source Attribution Study.
2007
Jul
Year
Month
Task 1
Drafting and Approval of Technical Work Plan
Task 2
Initial Data Analysis
Statistics
Graphical Representations
Principal Components Analysis (PCA)
Positive Matrix Factorization (PMF)
Task 3
Compilation of Chemical Source Profiles
Task 4
Chemical Mass Balance (CMB) Receptor Modeling
Task 5
Reporting
Draft Report
Final Report
Task 6
JE
AG
TC
Project Management
JE
AG
2007
Aug
JE
2007
Sep
2007
Oct
2007
Nov
2007
Dec
2008
Jan
2008
Feb
2008
Mar
2008
Apr
TC
TC
JE
JE
JE
JE
JE
TC
TC
JE
JE
JE
AG
JE
AG
JE
AG
JE
JE
AG
JE
2008
Jun
AG
JE
JE
JE
JE
JE
JE
2008
May
AG
JE
AG
JE
AG
Scheduled period of activity for Dr. Johann Engelbrecht
Scheduled period of activity for Dr. Alan Gertler
Scheduled period of activity for Dr. Tony VanCuren (CARB)
9
JE
AG
JE
AG
JE
AG
JE
AG
JE
AG
JE
AG
AG
AG
JE
JE
AG
AG
JE
AG
JE
AG