Selenium distributions in kanawha formation rocks from boone county west virginia
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Selenium Distributions in Kanawha Formation Rocks from Boone County, West Virginia. WEST VIRGINIA MINE DRAINAGE TASK FORCE SYMPOSIUM April 22-23, 2008. Dr. Dorothy Vesper West Virginia University Department of Geology & Geography WV WRI Hydrogeology Research Center DOE-NETL Research Fellow .

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Selenium distributions in kanawha formation rocks from boone county west virginia l.jpg
Selenium Distributions in Kanawha Formation Rocks from Boone County, West Virginia

WEST VIRGINIA MINE DRAINAGE TASK FORCE SYMPOSIUM

April 22-23, 2008

Dr. Dorothy Vesper

West Virginia University

Department of Geology & Geography

WV WRI Hydrogeology Research Center

DOE-NETL Research Fellow

Hydrogeology Research Center WV Water Research Institute


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Selenium distribution and mode of occurrence in the Kanawha Formation, southern West Virginia, USA

Vesper DJ, M Roy and CL Rhoads (2008) International Journal of Coal Geology73: 237-249.


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Se in rock core Formation, southern West Virginia, USA

Overall Purpose

  • Better understand the chemistry of Se in coals and related strata

  • Help predict where Se is most likely to be found

Two topics

  • Distribution in rock cores - stratigraphy

  • Mode of occurrence in rocks

2004 – 1 core, mostly mode of occurrence


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Location of cores Formation, southern West Virginia, USA

WVGES


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Selenium by coal bed Formation, southern West Virginia, USA

WVGES, 2002(coals only)

Stratigraphy

Coal

Se (ppm dry wt)

Pittsburgh

Kittanning

Coalburg &

Winifrede


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Distribution in rock core Formation, southern West Virginia, USA

Bull Creek Mine (Coal River watershed)

5 rock cores

  • Coal, shale, mudstone, sandstone, carbolith

  • Kanawha Formation (Coalburg – Winifrede coal beds)


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Distribution in rock core Formation, southern West Virginia, USA

287 Samples

  • 191 had Se > 0.2 mg/kg

  • Max 11.9 mg/kg in a mudstone

    Sample prep by Research Environmental & Industrial Consultants

  • Lithology described

  • Ground/composited to <60 mesh by lithology

  • Total digestion using nitric acid and hydrogen peroxide (EPA Method 3050B)

  • Analysis for total Se using Graphite Furnace Atomic Absorption Spectroscopy (GFAA) (EPA Method 270.2)


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2004 Formation, southern West Virginia, USA

Bull Creek Mine

Coalburg

Coalburg (upper line)

Winifrede (lower line)

Winifrede

Bull Creek

Coal River

1 km

Lick Creek


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Distribution in rock core Formation, southern West Virginia, USA

How is the Se distributed?

  • Stratigraphy

    • Rock type

    • Formation

    • Location relative to coal bed

  • Other chemical parameters

    • Sulfur (S)

    • Total organic carbon (TOC)


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Distribution in rock core Formation, southern West Virginia, USA

Do Se concentrations change with rock type?


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Distribution in rock core Formation, southern West Virginia, USA

Do Se concentrations change by core?


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Distribution in rock core Formation, southern West Virginia, USA

For non-coal units – distance to the coal matters

  • Proximate distance – shortest distance from bed to coal

  • 0 distance = adjacent to coal

  • Trends agree with Mullenex (2005) for a similar section in WV


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Distribution in rock core Formation, southern West Virginia, USA

What is the relationship between Se & sulfur?

All data (R2 = 0.21)

Coal only

Shale

Agrees with Coleman et al. (1993), Mullenex (2005), Neuzil et al. (2005) – FOR THIS REGION. Only Mullenex looked at multiple rock types


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Distribution in rock core Formation, southern West Virginia, USA

What is the relationship between Se & total organic carbon (TOC)?

All data

Coal

Mudstone &Shale

(only core 2)


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Multivariate analysis Formation, southern West Virginia, USA

Principle component analysis (PCA)

  • Multivariate

  • Looks for commonalities between variables

  • Identifies “factors” which are groups of variables


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PCA Results Formation, southern West Virginia, USA

  • PC1– Sulfur, acidic, non-carbonate, strongly related to sulfur concentration

  • PC2 –Carbonate, some acid, limited S

  • Se loads onto both the sulfur and non-sulfur PCs

  • Similar results obtained for PCA of coals in WV, based on WVGES database(2003)

169 samples; acidity and neutralization potential as calcium carbonate equivalent tons per 1000 tons


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PCA Results Formation, southern West Virginia, USA

Map Se and S concentrations for each sample against

PC1 and PC2 scores for each sample

PC1

Scores

(Sulfur-rich)

R2 = 0.87

R2 = 0.36

PC2

Scores

(more neutral)

R2 = 0.36

R2 = 0.01

Scores provide the weighting of that sample on that principle component

Selenium

Sulfur


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PCA Results Formation, southern West Virginia, USA

Mudstone, shale, sandstone

Neutral. potential more controlling

Carboliths

Coal

Sulfur more controlling


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Conclusions of rock core study Formation, southern West Virginia, USA

  • Distribution of total Se:

  • Se highest in coals; rocks adjacent to coals

  • Not all units close to coal are high in Se; but the layers that are high in Se are typically found with two feet of the coals

  • Se probably present in more than 1 mode

    • No strong correlations with S, TOC

    • Extraction data indicates both organic & sulfide

    • PCA analysis shows no single trend for Se

    • Sulfide more important for coals & organic-bound for shales (?)


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Possible Interpretation Formation, southern West Virginia, USA

  • Why these patterns in the rock record?

  • Steps to preservation:

    • Changing source through time

    • Immobile – during/after rock formation

    • (Se less mobile at low pH)


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Possible Interpretation Formation, southern West Virginia, USA

  • Depositional environment for Kanawha Formation

  • Domed swamp

  • (Rain water fed,

  • Typically acidic,

  • Low in nutrients)

Planar swamp

(Ground water fed, neutral pH)

Modified from USGS Circular 1143 (2003),

Coal—A Complex Natural Resource


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Possible Interpretation Formation, southern West Virginia, USA

  • Why these patterns in the rock record?

  • 1. Less S-associated Se

    • Deposition in domed peat swamp, more oxidizing

    • Less total S in system (no source vs. loss)

    • Se reduction vs. S reduction


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Possible Interpretation Formation, southern West Virginia, USA

  • 2. Possible redistribution after deposition

    • Se conc. above & below coal have similar trends

    • From compaction or later fluids


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A final thought Formation, southern West Virginia, USA

Depositional environments


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Selected References Formation, southern West Virginia, USA

Cecil, CB, RW Stanton, SG Neuzil, FT Dulong, LF Ruppert and BS Pierce (1985). "Paleoclimate controls on the late Paleozoic sedimentation and peat formation in the central Appalachian Basin (U.S.A.)." International Journal of Coal Geology5: 195-230.

Coleman, L, LJ Bragg and RB Finkelman (1993). "Distribution and mode of occurrence of selenium in US coals." Environmental Geochemistry and Health15(4): 215-227.

Mullennex R (2005) Stratigraphic Distribution of Selenium in Upper Kanawha-Lower Allegheny Formation Strata at a Location in Southern West Virginia. The 23rd Annual Intern Pitt Coal Conf

Neuzil, SG, FT Dulong and CB Cecil (2005). Spatial trends in ash yield, sulfur, selenium, and other selected trace element concentrations in coal beds of the Appalachian Plateau Region, U.S.A. (preliminary report). Reston, VA, U.S. Geological Survey.

USGS (2005). Coal—A Complex Natural Resource, An overview of factors affecting coal quality and use in the United States with a contribution on coal quality and public health. Circular 1143.

WVGES (2003) Trace Elements in West Virginia Coals. Selenium. Online graphs and data

Acknowledgements

U.S. Department of Interior Office of Surface Mining (OSM)

West Virginia Water Research Institute

REIC (Tim Keeney)

Decota Consulting

Pritchard Mining

Questions?


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