Application of the CMAQ Particle and Precursor Tagging Methodology (PPTM) to Support Water Quality Planning for the Virginia Mercury
Study
6th Annual CMAS ConferenceChapel Hill, NC
1-3 October 2007
Presented by Sharon Douglas ICF International, San Rafael, CA
Co-Authors:
Tom Myers Yihua Wei Jay Haney Mike Kiss Patty Buonviri
ICF
Virginia DEQ
Presentation Outline
Background & objectives
Overview of CMAQ/PPTM
Application of CMAQ/PPTM modeling for the Virginia Mercury Study
Background
Atmospheric deposition of mercury is a source of mercury contamination in surface waters
In the U.S., more than 8,500 bodies of water have been identified as mercury impaired
Within Virginia, fish consumption advisories have been issues for several bodies of water located primarily along the coastal plain susceptible to mercury methylation & bioaccumulation of
mercury in fish
Virginia Mercury Study Air Quality Modeling
Objectives
Review & update the Virginia mercury point source inventory
Prepare “conceptual description” of mercury deposition characteristics for Virginia
Conduct air quality modeling to simulate and quantify the contribution of regional and local emissions, and to provide information for TMDL assessments
Evaluate the effectiveness of future national and state control measures to meet water quality goals
Mercury Deposition Modeling Approach: Baseline Modeling
2001 Meteorological Inputs 2002 Criteria Pollutant & Mercury Emissions
Community Multiscale Air
Quality (CMAQ) Model, Version 4.6
AERMOD Gaussian Model
CMAQ Performance Evaluation
CMAQ Sensitivity Analysis
CMAQ Particle & Precursor Tagging Methodology (PPTM)
Identification of Sources with Significant Local
Contributions
AERMOD Sensitivity Analysis
Assessment of Global, National, Regional, and
Source-Specific Contributions
Mercury Deposition Modeling Approach: Future-Year
Modeling
2001 Meteorological InputsFuture-Year Criteria Pollutant & Mercury Emissions
2010, 2015 & 2018
CMAQ, Version 4.6 w/PPTM
AERMOD
Expected Future Changes in Local Contributions
Assessment of Future Control Measure
Effectiveness
Future-Year Projections
Future-Year Mercury
Contribution Analysis
Information for Water Quality Modeling, TMDL…
CMAQ Version 4.6 w/Mercury
Three species: elemental mercury (Hg0), reactive gaseous mercury (RGM or Hg2+), and particulate mercury (PHg)
Gaseous & aqueous reactions involving mercury (Bullock & Breme, 2002)
Recent enhancements include: improved dry deposition algorithm & natural emissions
Overview of the CMAQ Particle & Precursor Tagging Methodology
(PPTM)
PPTM can be applied for all PM species and for mercury (OPTM for ozone)
Emissions (or initial/boundary condition) species are tagged in the emissions (or IC/BC) files and continuously tracked throughout the simulation
Tags can be applied to source regions, source categories, individual sources, and/or IC/BCs
PPTM quantifies the contribution of tagged sources to simulated species concentrations & deposition
Overview of PPTM
For mercury, tagged elements include HG, HGIIGAS, HGIIAER, APHGI, APHGJ
Within the model, tagging is accomplished by the addition of duplicate species (e.g., HG_t1, HG_t2)
Tagged species have the same properties and are subjected to the same processes (e.g., advection, chemical transformation, deposition) as the actual species
Base simulation results not affected by tagging
Application of CMAQ/PPTM for the Virginia Mercury Study
PPTM #1 Tag 1: All anthropogenic Hg sources in VA Tag 2: All other Hg sources in the 12-km grid
PPTM #2 Tag 1: EGU sources in VA Tag 2: Other EGU sources in the 12-km grid Tag 3: All other Hg sources in the 12-km grid
Virginia Mercury Study CMAQ Modeling Domain
36 km
12 km
CMAQ Base Results: Total Hg Deposition
Results shown here are for July
CMAQ Base Results: Wet & Dry Hg Deposition
Results shown here are for July
DryWet
Results for PPTM#1: Total Hg Deposition
Results shown here are for July
VA Other
Regional Mercury Emissions
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
VA KY MD+DC NC PA TN WV
lbs/yr
Based on 2002 VDEQ and NEI Version 3 emissions
Results for PPTM#2: Total Hg Deposition
Results shown here are for July
VA EGU Other EGU
Results for PPTM#2: Total Hg Deposition
Results shown here are for JulyOther
Summary
CMAQ/PPTM can be used to track the fate of mercury emissions from selected sources & quantify their contribution to CMAQ-derived concentration and deposition estimates
Preliminary results for the Virginia Mercury Study indicate that Wet & dry deposition vary with meteorology and
have distinctly different patterns Both local and regional sources contribute to Hg
deposition in VA Transport from outside of the 12-km domain is an
important contributor to mercury deposition in VA