Martina Pulido ’22 Assesses Geochemical Characteristics of Dam Impounded Waters
Martina Pulido ’22 is an Environmental Geology major working with thesis advisor Jim Rougvie. Her research focuses on assessing geochemical characteristics of dam impounded waters in the James River Basin of Virginia.
Assessing dam usage and its influence on heavy metals in water systems is important in addressing changes in water quality to sustain safe drinking water, and aquatic ecosystems. Metals, such as manganese (Mn) and iron (Fe), along with the contaminant phosphorus (P), are detrimental to human health, and to aquatic life. Children that are chronically exposed to Mn²⁺ are more likely to develop learning impairments. Increased phosphorus leads to eutrophication, creating anoxic water conditions ideal for Mn²⁺ solubility, as well as causing fish kills and algal blooms. Anoxic waters can also be found in mill ponds, or stratified reservoirs, found behind dams. Seasonally stratified reservoirs allow metals such as Mn and Fe to accumulate in the water column due to reducing conditions in sediments, and be released to downstream rivers through dam discharge. Additionally, dam removal can remobilize and release soluble contaminants from impounded sediments to water systems. The dam tailrace transports and accumulates the remobilized sediments, impounded waters, and soluble metals, allowing the downstream water and ecosystems to be polluted with Mn²⁺ and P. Could dam reservoirs in Rockbridge County react in a similar way, and how are they impacting water quality?
Through my research the aqueous geochemistry of mill ponds were assessed to determine the potential risk for contamination of Mn²⁺ and other contaminants as a result of dam presence. The hypothesis will test dam system potential to create an increased risk for Mn²⁺ contamination due to water stratification and the mobilization of contaminants in sediments and water through dams.The area of focus is the Maury River in Rockbridge County, Virginia (VA), located in the James Basin of the Chesapeake Bay Watershed. The Maury River holds approximately 10 structures; our focus is a combination of six demolished and operating dams. Furthermore, there will be an evaluation of change in water geochemistry with depth to evaluate the importance of stratification in reservoirs, and how these reservoirs change seasonally.