Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Civil and Environmental Engineering


Joan E. McLean


Laurie S. McNeill


R. Ryan Dupont


Arsenic (As) is a poison historically used to great effect before modern detection methods rendered it obsolete. However, the largest mass poisoning in human history occurred due to groundwater in the Bengal Basin contaminated by natural sources of As. Since that time, research has determined that As is found in groundwater worldwide. This includes aquifers located in basin-filled valleys of the western United States. One of these valleys is the Cache Valley Basin located in Northern Utah. This semi-arid region contains carbonate-rich soils and is heavily influenced by snowmelt and seasonal runoff. Previous studies have found that 15% of private wells in the valley have As concentrations above the USEPA Maximum Contamination Level (MCL) of 10 μg/L.

This study used groundwater samples collected over a 2-year period from three adjacent wells in the Cache Valley Basin, in conjunction with laboratory columns, to determine the effects of temporal and redox changes on As concentrations and associated carbonate minerals. Although it was determined that As concentrations fluctuated due to changes in water levels and seasonal runoff, column experiments determined that As associated with carbonate minerals remained constant. This indicates the potential for using carbonates as a means of preventing As contamination in groundwater.