Date of Award
Master of Arts
Geological and Environmental Sciences
Dr. Alan E. Kehew
Dr. Richard Passero
Masters Thesis-Open Access
The Michigan Department of Public Health (MDPH) sampled 149 residential wells producing from glacial drift and Saginaw Formation aquifers in Bay, Midland, Saginaw, and Tuscola counties in 1987. These wells were analyzed for 226Ra, 228Ra and general chemistry. Of the 149 samples, 50 exceeded the USEPA MCL of 5 pCi/L or greater for combined 226Ra + 228Ra activities. A geochemical model (WATEQF, Plummer et al., 1976) was used to determine activity coefficients, activities, ionic strength, and mineral saturation. The radium isotopes were statistically analyzed with respect to the chemical data from MDPH and the geochemical model output. The analysis included the Pearson "r" correlation analysis, linear regression analysis of X-Y plots , and R- Mode factor analysis. 226Ra and 228Ra are positively correlated (r = .89) and may be in equilibrium. Also, radium concentrations correlate positively with Na+, Ca2+, K+, Sr2+, and Cl-. Analysis of bedrock cores from Saginaw Formation cores showed 226Ra, Al2O3, Na2O, CaO, and K2O to be elevated in samples of shale relative to sandstone. The source of radium and the oxides appears to be insoluble clay minerals in the Saginaw Formation. If this is the case, elevated radium, Al3+ , Na+ , Ca2+ , and K+ ions in the bedrock and drift aquifers may be derived from deeper strata.
Milejczak, "The Relation of Radium-226 and 228 to the Groundwater Geochemistry of Carbon, Sulfur, and Chlorine near Michigan's Saginaw Bay" (1989). Master's Theses. 4812.