Ecological and Chemical Analysis of Heavy Metal Transduction in Salix exigua on the Animas and Florida Rivers

Fort Lewis College, Durango, Colorado USA

Abstract: On August 5th, 2015, an accident from the Gold King Mine in Silverton, Colorado initiated the release of three million gallons of heavy metals into the Animas River. As heavy metals have toxic effects in high concentrations over time, it is extremely important to quantify the amounts of heavy metals in both the water itself, as well as surrounding riparian zones. This study inquired as to whether heavy metals were present in Salix exigua, or coyote willow, which makes up a large portion of the riparian biota in Southwest Colorado. Samples were taken from three sites, at Oxbow Park and Preserve and Trimble Lane on the Animas River, as well as from a control site on the Florida River. Six metals, including aluminum, zinc, cadmium, manganese, barium, and iron, were quantified in root and leaf samples to account for the fate and transport into riparian plants. As bioaccumulation of metals in ecosystems can have effects in many organisms, assessing the concentrations in the flora surrounding the river is essential to accounting for all aspects of river health. Metals were found to be significantly higher in roots compared to shoots, across all sites. Furthermore, the Animas River had significantly higher concentrations of heavy metals than the control site. Specifically, Oxbow Park and Preserve had the highest levels resulting from the specific geomorphology of the river section. This pilot study was essential for the quantification of heavy metal concentrations in the Animas River and will gain insight to the current ecological health post-mine spill reflecting short-term effects. It may also serve as baseline data for future studies accounting for plant health in this area that could quantify long-term effects of acid mine drainage after the Gold King mine spill.