Environmental and Anthropogenic Factors Affecting Solute Concentrations at Shaver's Creek

Open Access
Author:
Duggan, Patrick C
Area of Honors:
Geosciences
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Tess Russo, Thesis Supervisor
  • Maureen Fieneman, Honors Advisor
Keywords:
  • Shaver's Creek
  • Solute concentrations
  • Agriculture
  • Anthropogenic and environmental factors
Abstract:
The Susquehanna Shale Hills Critical Zone Observatory is a mixed land use watershed in central Pennsylvania. While much of the watershed is forested, it also contains acres of farmland. The human population has increased exponentially in the last century and with this growth has come agricultural expansion. While researchers agree that land use impacts watersheds, the extent of this impact is not fully understood. The purpose of this study is to examine the Shaver’s Creek watershed from a broad scale and determine how land use, in addition to varying lithology, seasonal variations, and pH, is related to solute concentrations. The solutes of interest will be common fertilizer constituents – nitrate, sulfate, and potassium – as well as major weathering products – magnesium, calcium, silicon, and sodium. The results showed natural increases and decreases in solute concentrations corresponding to periods of increased runoff and soil alterations from harvesting. With the exception of nitrate, the solutes tended to follow these natural trends regardless of total area of farmland, suggesting agriculture contributed minimally to their total concentrations. Nitrate concentrations increased rapidly as total area of farmland in the drainage basin increased and natural trends were not evident at the location most affected by agriculture. It was also found that lithology significantly affected potassium, calcium, magnesium, and silicon concentrations suggesting weathering plays a key role in the chemistry of Shaver’s Creek. Other site characteristics like temperature and pH showed no significant effect on solute concentrations. Quantifying the relationships between environmental conditions and solute concentrations will contribute to our ability to understand, model, and manage the impacts of human activities on surface water quality.