Mercury Speciation in Coal-fired Power Plant Plumes Observed at Three Surface Sites in the Southeastern U.S.
- 29 June 2006
- journal article
- research article
- Published by American Chemical Society (ACS) in Environmental Science & Technology
- Vol. 40 (15), 4563-4570
- https://doi.org/10.1021/es0515607
Abstract
Elemental Hg (Hg0), reactive gaseous Hg (RGM) and fine particulate Hg (HgP) were measured intermittently at three sites in the southeastern U.S. from June 2001 through November 2004. Simultaneous measurements of SO2 and NOy were used to identify plumes from coal fired power plants (CFPPs). Emission signatures and back trajectories were used to identity specific CFPPs, and to compare observed (i.e., at the site) versus expected (i.e., at the stack) Hg speciation. Results for 41 precipitation-free plume events show that observed RGM:SO2 is substantially lower (by a factor of 2−4) than expected RGM:SO2. HgP represented 2%, or less, of total-Hg in CFPP plumes, in general agree- ment with emission estimates. Results for 21 events, where both RGM and Hg0 could be estimated, show that total-Hg (i.e., RGM + Hg0) was essentially conserved from the point of emission to the site, and that Hg0 was the dominant form (average 84%). Emission estimates, based on coal analyses and the EPRI−ICR Hg speciation model, indicate that Hg0 should represent about 42% of Hg in the observed plumes. Possible explanations for these differences include, but are not limited to, in-plume reduction of RGM to Hg0, measurement error, errors in emission estimates, and depositional losses. Further work is needed to confirm these results and to determine if they apply to CFPPs in general, or the limited set of observed CFPPs.Keywords
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