High Definition Elemental Analysis of Lake Helena Sediments
Lake Helena has been impacted by heavy metal contamination as a result of historic mining and ore processing impacts on surrounding streams. Located in the northeastern area of the Helena Valley, Lake Helena is primarily fed by Prickly Pear Creek and Tenmile Creeks, and was formed when Hauser Dam was installed on the Missouri River in the early 1900s. Lake sediment cores are used to study changes in sediments over time, which in turn, reflect climate change as well as human impacts on a landscape. Previous studies, on core samples taken from near the delta on the west end of the lake, focused on flood history. This study uses cores taken from areas where historic wetlands possibly existed, closer to the northeast corner of the lake. These pre-Lake Helena wetlands may provide a longer sediment record (pre-dam), and will examine the lake sediments for differences in heavy metal concentrations pre- and post- mining activity. The Environmental Landscape Analysis class (ES 382) obtained several sediment cores from the NE fishing access of Lake Helena using a Livingston square rod position corer. Using X-ray fluorescence spectroscopy (XRF) the cores will be analyzed at one centimeter intervals to determine the concentrations of heavy metals such as copper, lead, cadmium, nickel, selenium, and iron. These longer cores will then be compared with the previous cores from the west end of the lake. The results of this study will quantify the changes in heavy metal contamination over time and space within the lake.