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T. F. Harms

Publications and source records attributed to T. F. Harms.

At least 19 recordsLinked to original sources
USGS1988

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

Big sagebrush — a cold-desert species that dominates the terrain over large parts of western United States — was sampled along several traverses that crossed thermally metamorphosed limestone, phyllitic shale, and schist of the Middle and Upper Cambrian Preble Formation that host skarn-, disseminated gold and silver-, and hot springs gold-type mineral occurrences. Patterns of detectable levels of gold (8 to 28 ppb or ng g −1 ) in ash of new growth were consistent with areas affected by known or suspected gold mineralization. Soils collected along one of the traverses where a selenium-indicator plant was common contained no gold above background levels of 2ppb, but were consistently high in As, Sb, and Zn, and several samples were unusually high in Se (maximum 11 ppm or μg g −1 ). Sagebrush along this traverse contained Li at levels above norms for this species. We also found a puzzling geochemical anomaly at a site basinward from active hot springs along a range-front fault scarp. Sagebrush at this site contained a trace of gold and an unusually high concentration of Cd (13 ppm) and the soil had anomalous concentrations of Cd and Bi (3.2 and 6 ppm, respectively). The source of this anomaly could be either metal-rich waters from an irrigation ditch or leakage along a buried fault. Despite the limited nature of the study, we conclude that gold in sagebrush could be a cost-effective guide to drilling locations in areas where the geology seems favorable for disseminated and vein precious metals.

Journal of Geochemical Exploration↗
USGS1986

Selenium concentrations in leaf material from Astragalus Oxyphysus (diablo locoweed) and Atriplex Lentiformis (quail bush) in the interior Coast Ranges and the western San Joaquin Valley, California

Leaf material from selenium accumulating plants was collected and analyzed for selenium to obtain a relative indication of selenium concentrations in soils and identify sites suitable for further soil study. Selenium concentrations of 14 samples of leaf material from Astragalus oxyphysus ranged from 0.08 to 3.5 microg/g dry weight and had a median concentration of 0.25 microg/g. Five replicate samples of A. oxyphysus had a mean selenium concentration of 0.22 microg/g and a standard deviation of 0.07. Selenium concentrations of 17 samples of leaf material from Atriplex lentiformis ranged from 0.08 to 7.5 microg/g and had a median concentration of 0.35 microg/g. As a general guideline, the National Academy of Sciences recommends a maximum safe tolerance level of 2 microg/g of selenium in animal feeds. One sample of A. oxyphysus, collected in the Panoche Creek drainage, exceeded 2 mcirog/g. Three samples of A. lentiformis, collected in Klipstein Canyon, Tumey Fan, and Panoche Fan, equaled or exceeded 2 microg/g. These sites may be suitable. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1985

Comparison of digestion methods for total elemental analysis of peat and separation of its organic and inorganic components

In order to find the most efficient digestion method for the total elemental recovery in peat, ten samples were subjected to different techniques and analysed for Ca, Mg, Fe, AI, Na, K, Mn, P, Zn, Cu, Li, Cd, Co, Ni, Pb and Si using atomic-absorption spectrophotometry. The most satisfactory procedures were dry ashing followed by hydrofluoric acid treatment and wet digestion using a mixture of hot nitric, perchloric and hydrofluoric acids. The wet digestion offers the advantage of a single decomposition method for the determination of Ca, Mg, Fe, AI, K, Na, Mn, Cu, Li, Zn and P. An alkaline fusion technique was required for the determination of Si. Hydrogen peroxide was used to separate the peat into its organic and inorganic components, leading to the total recovery of the elements for both fractions.

The Analyst↗
USGS1981

Laser fluorometric analysis of plants for uranium exploration

A preliminary test of biogeochemical exploration for locating uranium occurrences in the Marfa Basin, Texas, was conducted in 1978. Only 6 of 74 plant samples (mostly catclaw mimosa, Mimosa biuncifera ) contained uranium in amounts above the detection limit (0.4 ppm in the ash) of the conventional fluorometric method. The samples were then analyzed using a Scintrex UA-3 uranium analyzer ∗ - an instrument designed for direct analysis of uranium in water, and which can be conveniently used in a mobile field laboratory. The detection limit for uranium in plant ash (0.05 ppm) by this method is almost an order of magnitude lower than with the fluorometric conventional method. Only 1 of the 74 samples contained uranium below the detection limit of the new method. Accuracy and precision were determined to be satisfactory. Samples of plants growing on mineralized soils and nonmineralized soils show a 15-fold difference in uranium content; whereas the soils themselves (analyzed by delayed neutron activation analysis) show only a 4-fold difference. The method involves acid digestion of ashed tissue, extraction of uranium into ethyl acetate, destruction of the ethyl acetate, dissolution of the residue in 0.005% nitric acid, and measurement.

Texas↗