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Tennessee Valley Authority — Technical Presentation (2010)
18 slides from Tennessee Valley Authority's technical presentation, 2010
Slide 1: Fly Ash Geochemistry: Current Course of Investigations
Fly Ash Geochemistry: Current Course of Investigations Dr. Mark Chappell Environmental Laboratory U.S. Army Engineer Research and Development Center (ERDC) 3909 Halls Ferry Road, Vicksburg, MS 39180 BUILDING STRONG®
Slide 2: Geochemistry Overview
Geochemistry Overview Elemental & isotopic Ash stability – dissolution – characterization, stratigraphic leaching potential profiling Fly ash geochemistry Metal/metalloid speciation Mobility - Bioavailability and complexation 2 BUILDING STRONG®
Slide 3: I. Ash Location/Identification
I. Ash Location/Identification Focus is on: ► Boron, strontium, and mercury isotope ratios, 3 Vengosh et al., Duke University
Slide 4: Geomorphology of ash deposits
Geomorphology of ash deposits Emory sediment only Pure ash • Evaluating use of a Sub-Bottom Profiler (SBP) to characterize areas of deposition of ash in the Emory, Clinch, and Tennessee Rivers, • interpreting stratigraphy of cores collected from those areas, and evaluating geochemical speciation of
Slide 5: II. Metal speciation & complexation
II. Metal speciation & complexation Spot 1 Spot 2 µ-XRF maps of fly ash samples collected from the remaining source pile – ERDC, 2009 Steevens et al., 2009; Chappell et al., In preparation BUILDING STRONG®
Slide 6: Bulk XANES of Arsenic & Selenium
Bulk XANES of Arsenic & Selenium Selenium Arsenic Source Pile: mainly Se (IV) Emory River & ARD: Mixture of Se(IV), Source Pile: mainly As(V) organoselenium (-II), Se(IV)-sulfides Emory River & ARD: mostly As(V) with some As-sulfides BUILDING STRONG®
Slide 7: As speciation for DOT classification
As speciation for DOT classification Seiter and Chappell, U.S. Army ERDC 7 BUILDING STRONG®
Slide 8: Time-critical studies (ERDC)
Time-critical studies (ERDC) 120 High-intensity dredge cell EMR-1 100 Dredging EMR-2 ASP-2 80 ASP-1 Sampling Point ARD-1 ASP-3 ARD-100 Cumulative % by volume < ASP-4 ARD-200 EMR-3 60 SLC-200 SLC-2 STP-1 STP-2 ASP-100 ARD-2 PWW-2 ASP-400 STP-3 CWI-1 STP-100 PWW-3 40 STP-4 EMR-2xx SLC-1 PWW-1 CWI-2 20
Slide 9: Aqueous As and Se speciation during high-intensity dredge
Aqueous As and Se speciation during high-intensity dredge Arsenic 0.16 0.14 0.12 Total 0.10 Dissolved Mean Concentration, mg/L 0.08 0.06 0.04 0.02 0.00 Station No. Selenium 0.04 0.03 0.03 Total Dissolved 0.02 Mean Concentration, mg/L 0.02 0.01 0.01 0.00 9 BUILDING STRONG® Station No.
Slide 10: Relating Chemical Speciation to Dissolution Kinetics and Bioaccumulation
Relating Chemical Speciation to Dissolution Kinetics and Bioaccumulation Dean Hesterberg (PI), Owen Duckworth, and David Buchwalter (North Carolina State University) Overall Goal: to determine how chemical forms of metals affect their mobilization to the aqueous phase and their bioavailability to al
Slide 11: III. Ash stability – dissolution potential
III. Ash stability – dissolution potential Elutriate studies: ERDC Bednar et al., 2010, Chemosphere BUILDING STRONG®
Slide 12: Leaching potential
Leaching potential Sedwick and Cutter (Old Dominion University) ► Novel flow-through leaching method ► Estimates of fractional dissolution and/or uptake Ryan (Univ. Colorado) and Aiken (USGS): ► They plan to conduct batch leaching at • different mixing energies (characteristic of rivers), • vary
Slide 13: Thermodynamic analysis: Pourbaix diagrams
Thermodynamic analysis: Pourbaix diagrams 13 BUILDING STRONG® Chappell, Bednar, and Seiter, U.S. Army ERDC
Slide 14: Susceptibility of As (III) and Se(IV) photooxidation in ARD
Susceptibility of As (III) and Se(IV) photooxidation in ARD 14 BUILDING STRONG® Bednar, U.S. Army ERDC
Slide 15: IV. Mobility & Bioavailability
IV. Mobility & Bioavailability Selenium biogeocycling in the river system Atmospheric Input Fly Ash Pond Effluent (SeIV/SeVI) (SeIV>>SeVI) Atmosphere Water Column Primary Producers p Org Se(-II) - phytoplankton, benthic Days microalgae - River Inputs River [p Org Se(-II), p Se(IV+VI)] Outflows d Org
Slide 16: Methylmercury contamination of river sediments near the coal ash spill
SETAC poster presentation: Methylmercury contamination of river sediments near the coal ash spill at the Kingston Fossil Plant, TN Deonarine A., Hsu-Kim H., Ruhl L., and Vengosh A. Duke University Bartov G., Johnson T. University of Illinois, Urbana-Champaign Methylmercury in Emory and Clinch Rivers
Slide 17: Relating Chemical Speciation to Dissolution Kinetics and Bioaccumulation
Relating Chemical Speciation to Dissolution Kinetics and Bioaccumulation Dean Hesterberg (PI), Owen Duckworth, and David Buchwalter (North Carolina State University) Overall Goal: to determine how chemical forms of metals affect their mobilization to the aqueous phase and their bioavailability to al
Slide 18: Summary
Summary Elemental & isotopic Ash stability – characterization, dissolution – leaching stratigraphic profiling potential Fly ash geochemistry Metal/metalloid speciation and Mobility - Bioavailability complexation • Linking geochemistry with potential bioavailability and toxicity • Extrapolation of fi
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