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