Semester

Spring

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

Dorothy Vesper

Committee Member

Aaron Maxwell

Committee Member

Kyle Fredrick

Committee Member

Michael Harman

Abstract

A fundamental driver of the adverse effects associated with coal mining is the interplay of water and oxygen within mined sites, leading to the creation of coal mine drainage (CMD). One often overlooked consequence of CMD is the release of geologically-bound carbon as carbon dioxide (CO2). The interaction of CMD with carbonate rocks, specifically the presence of sulfuric acid driving the dissolution of these rocks, leads to the release of dissolved inorganic carbon (DIC). This study examined 25 CMD locations in an approximately 2,370 km2 area within the bituminous coal field region of Pennsylvania (PA), specifically in Fayette, Washington, Westmoreland, and Allegheny Counties. Sample locations included discharge pipes, mine portals, and seeps within the Monongahela River watershed. Direct measurements of DIC, CO2, pH, and discharge were measured along with major ions to gain insights into the carbon flux of this region. Additionally, one sample location was monitored monthly to capture seasonal variability.

Water quality analysis revealed significant variability in hydrochemical profiles with carbonate-sulfate systems dominating. Dissolved concentrations of CO2 in CMD measured in this study ranged from 15 to 312 times greater than the current atmospheric equilibrium concentration, aligning with ranges from previous studies within the region and across the bituminous coal field region of PA. Flux of DIC loss as both CO2 evasion and bicarbonate export from CMD were measured for this study to be on average about 6 t-C/year and 8 t-C/year, respectively. Estimated cumulative CO2-evasion fluxes are approximately 570 t-CO2/year for the study area and 14,340 t-CO2/year for the bituminous coal field region of PA, equivalent to a small fraction of emissions from a coal-fired power plant in PA. This study addresses limitations including the use of CMD location density in the study area as a proxy for regional estimates, potentially leading to overestimation or underestimation of fluxes. Additionally, not all CMD locations within the study area were accessible and insufficient temporal data may have led to underestimations of fluxes. Overall, the flux estimates are approximate and may be biased high or biased low due to these limitations.

By quantifying cumulative CO2-evasion flux and bicarbonate-export flux from the sample locations, this study captures the variability in CMD locations typical in bituminous coal mining regions. Understanding the extent of CMD as a CO2 emissions source is crucial, offering a different perspective on the carbon cycle within coal-mining affected areas.

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