Mountaintop removal coal mining impacts on structural and functional indicators in Central Appalachian streams

Area of Science:

• Environmental Science
• Ecology
• Water Quality Assessment

Background:

• Mountaintop removal coal mining (MTR) significantly alters landscapes in the Central Appalachians, impacting stream hydrology, geomorphology, and water quality.
• Impaired stream ecological integrity is a major concern, necessitating effective assessment tools under the Clean Water Act (CWA).
• Current CWA assessments primarily use structural indicators; incorporating functional indicators could provide a more holistic evaluation of ecosystem health.

Purpose of the Study:

• To evaluate the effectiveness of carbon and nitrogen cycling and microbial structural and functional indicators for assessing MTR coal mining impacts.
• To determine if these indicators respond predictably to MTR mining stressors.
• To ascertain if functional indicators are more resistant to change than structural indicators in MTR-impacted streams.

Main Methods:

• Seasonal measurements of water quality, sediment organic matter, and microbial activity (functional indicators) were conducted over one year.
• Streams draining MTR-impacted and forested watersheds in West Virginia's Twentymile Creek watershed were compared.
• Eight structural and fourteen functional indicators were analyzed for significant responses to MTR coal mining.

Main Results:

• Five of eight structural indicators showed significant increases in MTR-impacted streams, with nitrate concentration and dissolved inorganic carbon stable isotope ratio being highly effective.
• Only three of fourteen functional indicators responded significantly to MTR mining, with most showing no observable change.
• Structural parameters were altered by MTR mining, likely due to changes in carbon and nitrogen sources, while functional indicators were less affected, possibly due to resource subsidies.

Conclusions:

• Structural indicators, particularly nitrate and stable carbon isotopes, are sensitive to MTR coal mining impacts on stream ecosystems.
• Functional indicators demonstrated greater resistance to MTR mining stressors compared to structural indicators, supporting their potential for more robust ecological integrity assessments.
• While functional indicators show promise, identifying suitable ones that capture the full complexity of ecosystem response to mining remains challenging.