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Application of the CMAQ Particle and Precursor Tagging Methodology (PPTM) to Support Water Quality Planning for the Virginia Mercury Study. 6 th Annual CMAS Conference Chapel Hill, NC 1-3 October 2007 Presented by Sharon Douglas ICF International, San Rafael, CA. Co-Authors:. Tom Myers
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Application of the CMAQ Particle and Precursor Tagging Methodology (PPTM) to Support Water Quality Planning for the Virginia Mercury Study 6th Annual CMAS Conference Chapel 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 AERMOD Sensitivity Analysis CMAQ Sensitivity Analysis Identification of Sources with Significant Local Contributions CMAQ Performance Evaluation Assessment of Global, National, Regional, and Source-Specific Contributions CMAQ Particle & Precursor Tagging Methodology (PPTM)
Mercury Deposition Modeling Approach: Future-Year Modeling Future-Year Criteria Pollutant & Mercury Emissions 2010, 2015 & 2018 2001 Meteorological Inputs AERMOD CMAQ, Version 4.6 w/PPTM Expected Future Changes in Local Contributions Future-Year Projections Future-Year Mercury Contribution Analysis Assessment of Future Control Measure Effectiveness 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 Wet Dry Results shown here are for July
Results for PPTM#1: Total Hg Deposition VA Other Results shown here are for July
Regional Mercury Emissions Based on 2002 VDEQ and NEI Version 3 emissions
Results for PPTM#2: Total Hg Deposition VA EGU Other EGU Results shown here are for July
Results for PPTM#2: Total Hg Deposition Other Results shown here are for July
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