DIMIZA: A DISPERSION MODELING BASED IMPACT ZONE ASSESSMENT OF MERCURY (HG) EMISSIONS FROM COAL-FIRED POWER PLANTS AND RISK EVALUATION FOR INHALATION EXPOSURE

Abstract

Coal-fired combined heat and power plants (CHPPs) serving large districts areamong the major sources of mercury (Hg) emissions globally, including Cen-tral Asia. Most CHPPs reside on the outskirts of urban areas, thus creating riskzones. The impact of atmospheric Hg levels on health is complex to establishdue to the site-specific nature of the relationship between CHPP emissions andhotspots (i.e., localized areas where Hg concentrations greatly exceed its back-ground value). However, a methodological identification of “emission impactzones” for atmospheric Hg emissions from CHPPs with potential adverse publichealth outcomes has not yet been fully studied. The present work suggests aneasy-to-use and cost-free impact zone identification method based on HYSPLITdispersion modeling for atmospheric Hg emissions from CHPPs. The dispersionmodeling based impact zone assessment, DiMIZA, merges short-term disper-sion runs (e.g., hourly) into long-term emission impacts (e.g., yearly), whichallows to identify the source impact zones. To perform a case study using thesuggested method, a CHPP plant in Nur-Sultan (capital of Kazakhstan) wasselected. First, traditional ad-hoc measurements were performed to identify thelevel of dispersions at ground level in different atmospheric stability character-istics. Then, HYSPLIT dispersion model was run for the same days and timesof those particular periods when the field measurements were performed. Themodel results were evaluated via a comparison with the ground measurementsand assessed for their atmospheric stability and diel conditions. Due to differ-ent emission loads in heating and non-heating periods, two separate pairs ofimpact zone maps were generated, and public Hg exposure health risks (acuteand chronic) were assessed.