Baseline Elemental Concentrations for Big Sagebrush from Western U.S.A.

Abstract

The analysis of samples of big sagebrush from 190 sites in 8 western physiographic provinces resulted in measurable concentrations of 30 elements. Except for Sb, U, and V, whose concentrations were generally below the analytical detection limits, the expected (baseline) concentration range of each element was defmed. The variability in the concentration of Ba, Ca, Li, Pb, Se, Sr, and Zn among the 8 provinces was found to be nonsignificant and therefore a mean and deviation (for all provinces combined) for these elements was used to define their baseline. For concentrations of 20 of the elements (including the environmentally important metals As, Cd, Cr, Co, Cu, Hg, and MO), significant variability was found among provhrce populations so that baseline values are reported for each province or group of provinces. Physiographic provinces were incorporated in the study design as a convenient natural unit in presenting the element baselines and we anticipate that these data may be useful in assessing biogeochemical changes brought about by the activities of energy development, mineral processing, and other anthropogenic disturbances. The major goal of this study is to establish baselines for the elemental composition of big sagebrush (Arremisiu rridenrata Nutt.) throughout the western U.S.A. Big sagebrush is one of the most widely distributed and easily recognized shrubs of this vast region and of southern British Columbia, Canada. The importance of this species as a component in natural ecosystems and in regions dominated by livestock production was the subject of a recent symposium (Utah State Univ., 1979). At the beginning of this study, baseline elemental composition data were seen as being useful primarily in assessing the consequences of energy development in the western U.S.A. Such activities include the surface-mining of coal and the attendant geochemical and biogeochemical changes following land reclamation (e.g., Munshower and Neuman 1980) as well as point-source contamination from coal-fired power plants and mineral processing facilities (e.g., Connor et al. 1976, Severson and Gough 1976). Elemental composition data, however, may be equally useful in evaluating contamination from natural events (e.g., the Mount St. Helens eruption) or assessing the value of sagebrush as a browse plant for livestock or for wildlife (e.g., Alvarez-Corder0 and McKell 1979, Welch and McArthur 1979). In addition, big sagebrush has had limited use as a sampling medium for geochemical exploration (Warren et al. 1949, Cannon 1952, Anderson and Kurtz 1956, and Erdman and Harrach 1981) and the data in the present report should be useful in helping to identify anomalous samples from potentially mineralized areas. The use of big sagebrush as a biogeochemical exploration medium is attractive not only because of its wide distribution but also because it grows in vast regions where alluvial and colluvial surfaces (as in the Basin and Range province) Authors are botanists, U.S. Geological Survey, Box 25046, Denver Federal Center, Denver, Co...

Gold in big sagebrush (Artemisia tridentata Nutt) as an exploration tool, Gold Run District, Humboldt County, Nevada

“…Concentrations of Mn and Fe are within ranges judged normal and are therefore not given in Table 1. However, the Li concentrations generally exceed the 50 ppm upper limit of the normal range given by Gough and Erdman (1983) and correspond to the high As, Sb, and Zn levels in soils throughout the traverse (Table 1). Uncommonly high Li levels are often found in geothermal waters and Li is easily taken up by plants affected by such areas (Erdman, unpublished data).…”

“…Stems, leaves, and flowering parts were combined into a composite sample for several reasons: (1) norms have been published for similar samples from the eight physiographic provinces of the western U.S. in which big sagebrush occurs (Gough and Erdman, 1983), (2) comparisons by Levering and Hedal (1983) of element levels of stems versus leaves and blossoms showed no appreciable differences, and (3) such composite samples are simply more efficient to collect and process. The total number of sagebrush samples from the traverse sites was 60.…”

“…Anomalous element concentrations in the sagebrush samples (Table 1) were judged from a combination of sources: baselines reported for this species by Gough and Erdman (1983); scan of the raw data; visual inspection of the histograms for the Cd, Cu, Mo, and Zn data; and from geologic inferences based on where the samples were collected. Gough and Erdman (1983) defined baseline as the expected (central) 95% range of the concentration data.…”

“…Gough and Erdman (1983) defined baseline as the expected (central) 95% range of the concentration data. The means (norms) derived from Gough and Erdman (1983) are given in Table 1.…”

“…Gough and Erdman (1983) defined baseline as the expected (central) 95% range of the concentration data. The means (norms) derived from Gough and Erdman (1983) are given in Table 1. Norms for Au and Ag concentrations in sagebrush are not available in the literature and therefore are only estimates based on our experience with Au and Ag concentrations in plant samples.…”