Chemical Evolution and Hydrology of Northern Sierra Nevadan Mineral Springs
Poster Number
49
Format
Poster Presentation
Abstract/Artist Statement
Mineral springs in the Sierra Nevada of California provide small but unique montane habitats which support rare biota. The geochemical evolution and hydrology of groundwater discharging in these springs provides insight into the stability of these rare environments in a changing climate. General geochemical, stable isotope, and chlorofluorocarbon age tracer measurements were collected from thirteen springs in the Northern Sierra Nevada. A GIS database was created to study geologic substrates and hydrology, and NETPATH was utilized to perform mass balance calculations. Five sites are located in Yosemite National Park, and eight are in the headwaters of the North Fork of the American River (NFA). All samples exhibited high levels of conductivity. All springs are bicarbonate waters, but the dominant cation varied between sites. Mineral waters of Yosemite are of sodium-potassium type. NFA waters are dominated by calcium, with an isolated two spring subset exhibiting the highest values of calcium, sodium, and chloride. Although these two springs are associated with granitic geology, a yet unidentified source of chloride influences their geochemistry. Mineral spring waters range in apparent ages from 40 to 60 years. Oxygen and hydrogen isotopes suggest a meteoric origin for all waters sampled. The Yosemite spring waters are more isotopically depleted than the Placer County waters due to a higher recharge elevation. Stable isotope values negatively correlated with geochemical age at each site, suggesting changing environmental conditions. This study provides insight on a slowly circulating hydrologic system which is responsible for producing important microhabitats.
Location
DeRosa University Center, Ballroom B
Start Date
1-5-2010 1:00 PM
End Date
1-5-2010 3:00 PM
Chemical Evolution and Hydrology of Northern Sierra Nevadan Mineral Springs
DeRosa University Center, Ballroom B
Mineral springs in the Sierra Nevada of California provide small but unique montane habitats which support rare biota. The geochemical evolution and hydrology of groundwater discharging in these springs provides insight into the stability of these rare environments in a changing climate. General geochemical, stable isotope, and chlorofluorocarbon age tracer measurements were collected from thirteen springs in the Northern Sierra Nevada. A GIS database was created to study geologic substrates and hydrology, and NETPATH was utilized to perform mass balance calculations. Five sites are located in Yosemite National Park, and eight are in the headwaters of the North Fork of the American River (NFA). All samples exhibited high levels of conductivity. All springs are bicarbonate waters, but the dominant cation varied between sites. Mineral waters of Yosemite are of sodium-potassium type. NFA waters are dominated by calcium, with an isolated two spring subset exhibiting the highest values of calcium, sodium, and chloride. Although these two springs are associated with granitic geology, a yet unidentified source of chloride influences their geochemistry. Mineral spring waters range in apparent ages from 40 to 60 years. Oxygen and hydrogen isotopes suggest a meteoric origin for all waters sampled. The Yosemite spring waters are more isotopically depleted than the Placer County waters due to a higher recharge elevation. Stable isotope values negatively correlated with geochemical age at each site, suggesting changing environmental conditions. This study provides insight on a slowly circulating hydrologic system which is responsible for producing important microhabitats.