Laserfiche WebLink
• SOIL SELENIUM ANALYSIS <br /> The presence of too secondary selenium absorbers, curlycup gumweed <br /> (Grindelia squazrosa) and broom snakeweed (Gutierrizia sarothrae) in <br /> grassland and upland sagebrush vegetation wimwnities at the Nucla Mine <br /> suggested the possible presence of seleniferous soils on the study area. <br /> To evaluate ttus possibility, three soil samples from each vegetation type <br /> were collected and suksnitted to Front Range Iabs, Inc., Ft. Collins, <br /> Colorado for selenium analysis. Each sample consisted of a romposite <br /> of several samples and was wllected with anacid-washed stainless steel <br /> trowel from the top 5 cm of surface material. Samples were taken from <br /> azeas where the above species were observed. Samples case double-bagged <br />' in clear polyethylene wntainers and a label placed in the outer bag <br /> to avoid contact with the sample. <br /> In the laboratory, a hot water extract was obtained for each sample by <br /> heating a 100g sub-sale of finely ground air-dry soil in 500 ml of <br />• ~ water at reflux for 30 minutes follaaed by filtration. Selenium was <br /> then determined from the resulting extract by atwnic absorption techniques <br /> using a Per',cin-Elmer 5000 Atomic Absorption Spectrophotometer equipped <br /> with auto sampling capability. The light source was provided by single <br /> element lwllow cathode tubes. Selenium was determined at a wavelength <br /> of 196.0 mn using a sodium borohydride reduction method. The detection <br /> limit was 0.005 mg/ml and results are reported in parts per million (ppm). <br />The results of the selenium analy:.is for soils rollected from grassland <br />and upland sagebrush vegetation a~mrnu~ities are shown below: <br />Sample ~ (ppm) <br />• <br />r. .~..._. i.u <br />Grassland -Sample #1 0.038 <br />Grassland -Sample #2 0.050 <br />Grassland -Sample #3 0.022 <br />Upland Sagebrush - Sample #1 0.007 <br />Upland Sagebrush - Sample #2 0.009 <br />Uplarrl Sagebrush - Sale #3 0.006 <br /> / n <br /> 5 Iy(~ <br /> <br />