ANALYSIS OF SOIL AND PLANT SAMPLES FOR HEAVY METAL CONTENT IN THE AFTERMATH OF THE GOLD KING MINE SPILL

On August 5^th, 2015, an accident at the Gold King Mine near Silverton, CO led to the release of over three million gallons of heavy metal laden water into Cement Creek, a tributary of the Animas River. This incident has prompted the heavy metal analyses of environmental samples, particularly water and sediment. A greater variety of sample types is necessary to fully understand how metals are accumulating in the Animas watershed in the aftermath of this event. This study aims to quantify the heavy metal content of agricultural soil and plant samples gathered in the Animas river valley following the Gold King Mine spill. Soil and plant samples from five different sites along the Animas river North of Durango, CO are analyzed. The analytes of interest in this study are Zn, Mn, Fe, Co, Al, Ba, Cd, Cr, Cu, and Pb. All samples are prepared for analysis using the standard EPA acid digestion method 3050B. Following acid digestion, samples are analyzed by Microwave Plasma-Atomic Emission Spectrometry (MP-AES), a limit of detection (LOD) and a limit of quantification (LOQ) are determined, and an external calibration is prepared yielding R² > 0.995 for each analyte. Methods are validated using NIST standard soil and plant materials containing known quantities of each analyte. Heavy metal concentrations vary significantly within each sample site, as well as across sample types. The majority of samples studied displayed analyte concentrations in the order soil > mullein > kale with the exception of Ba, which was higher in concentration in several kale samples. Fe was the most highly concentrated analyte observed in the majority of samples.