Poster Title

Pathways for Environmental Sulfuric Acid Contamination from Disturbance of Geologic Materials

Grade Level at Time of Presentation

*Select One*

Institution

Western Kentucky University

KY House District #

91 & 20

KY Senate District #

21 & 32

Department

Geography and Geology

Abstract

Cayla Baughn, Caleb Stickney, Chris Harkins, and Katherine Losekamp

Advisor: Dr. Chris Groves

Crawford Hydrology Laboratory

Department of Geography and Geology

WKU Applied Research and Technology Program

Western Kentucky University

Bowling Green, KY 42101

Faculty Advisors: Dr. Chris Groves and Dr. Cate Webb

Air and water quality in the southeastern US have been impacted by sulfuric acid (H2SO4) formed by oxidation of sulfur in the mineral pyrite (FeS2) exposed to the environment through disturbance of Pennsylvanian-aged coals by mining or construction. Two case studies here illustrate pathways by which such H2SO4 can move through the environment. Coals of western Kentucky contain relatively high concentrations of pyrite that when burned produces strong “acid rain” that can have impacts on vegetation and water quality. Mammoth Cave National Park (MCNP) has been impacted by such sulfuric acid rain. Rainfall data from just outside MCNP show that from 2002 to 2005 rainfall pH averaged 4.7, some ten times as acidic as unpolluted rainfall. Beginning in 2005, due to regional changes in coal burning technology, rainfall pH began increasing. Rainfall pH from 2014 to 2016 averaged 5.2, representing a drop in acidity of about 68%. During the same period dissolved SO42- in the rainfall dropped by about 55%.

H2SO4 from pyrite-bearing coal can also contaminate surface streams with so-called Acid Mine Drainage (AMD). In 2012 residents along Freeman Branch Creek near Eldridge Alabama observed orange and black discoloration along the stream which had not previously been seen. Inspection of geological maps showed that the Pennsylvanian Pottsville Formation underlying the area contains coal and appeared to be a likely source of the contamination. Although we hypothesized that coal mining may have been responsible, subsequent field investigation instead suggested that blasting associated with recent highway construction upstream from where the discoloration had been observed may have enhanced pyrite weathering, along with buffering by limestone bedrock used as fill material. This highlights how construction activities in sulfide-bearing geologic materials can influence water quality. Understanding of geochemical conditions and processes in such settings can be informed by the extensive existing literature on AMD.

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Pathways for Environmental Sulfuric Acid Contamination from Disturbance of Geologic Materials

Cayla Baughn, Caleb Stickney, Chris Harkins, and Katherine Losekamp

Advisor: Dr. Chris Groves

Crawford Hydrology Laboratory

Department of Geography and Geology

WKU Applied Research and Technology Program

Western Kentucky University

Bowling Green, KY 42101

Faculty Advisors: Dr. Chris Groves and Dr. Cate Webb

Air and water quality in the southeastern US have been impacted by sulfuric acid (H2SO4) formed by oxidation of sulfur in the mineral pyrite (FeS2) exposed to the environment through disturbance of Pennsylvanian-aged coals by mining or construction. Two case studies here illustrate pathways by which such H2SO4 can move through the environment. Coals of western Kentucky contain relatively high concentrations of pyrite that when burned produces strong “acid rain” that can have impacts on vegetation and water quality. Mammoth Cave National Park (MCNP) has been impacted by such sulfuric acid rain. Rainfall data from just outside MCNP show that from 2002 to 2005 rainfall pH averaged 4.7, some ten times as acidic as unpolluted rainfall. Beginning in 2005, due to regional changes in coal burning technology, rainfall pH began increasing. Rainfall pH from 2014 to 2016 averaged 5.2, representing a drop in acidity of about 68%. During the same period dissolved SO42- in the rainfall dropped by about 55%.

H2SO4 from pyrite-bearing coal can also contaminate surface streams with so-called Acid Mine Drainage (AMD). In 2012 residents along Freeman Branch Creek near Eldridge Alabama observed orange and black discoloration along the stream which had not previously been seen. Inspection of geological maps showed that the Pennsylvanian Pottsville Formation underlying the area contains coal and appeared to be a likely source of the contamination. Although we hypothesized that coal mining may have been responsible, subsequent field investigation instead suggested that blasting associated with recent highway construction upstream from where the discoloration had been observed may have enhanced pyrite weathering, along with buffering by limestone bedrock used as fill material. This highlights how construction activities in sulfide-bearing geologic materials can influence water quality. Understanding of geochemical conditions and processes in such settings can be informed by the extensive existing literature on AMD.