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At least 1,207 records · Page 67Linked to original sources

USGS2008

Cathodoluminescence, laser ablasion inductively coupled plasma mass spectrometry, electron probe microanalysis and electron paramagnetic resonance analyses of natural sphalerite

Natural sphalerite associated with copper, silver, lead-zinc, tin and tungsten deposits from various world-famous mineral deposits have been studied by cathodoluminescence (CL), laser ablasion inductively coupled plasma mass spectrometry (LA-ICP-MS), electron probe microanalysis (EPMA) and electron paramagnetic resonance (EPR) to determine the relationship between trace element type and content and the CL properties of sphalerite. In general, sphalerite produces a spectrum of CL colour under electron bombardment that includes deep blue, turquoise, lime green, yellow-orange, orange-red and dull dark red depending on the type and concentration of trace quantities of activator ions. Sphalerite from most deposits shows a bright yellow-orange CL colour with ??max centred at 585 nm due to Mn2+ ion, and the intensity of CL is strongly dependent primarily on Fe2+ concentration. The blue emission band with ??max centred at 470-490 nm correlates with Ga and Ag at the Tsumeb, Horn Silver, Balmat and Kankoy mines. Colloform sphalerite from older well-known European lead-zinc deposits and late Cretaceous Kuroko-type VMS deposits of Turkey shows intense yellowish CL colour and their CL spectra are characterised by extremely broad emission bands ranging from 450 to 750 nm. These samples are characterised by low Mn (<10 ppm) and Ag (<1 ppm), and they are enriched in Tl (1-30 ppm) and Pb (80-1500 ppm). Strong green CL is produced by sphalerite from the Balmat-Edwards district. Amber, lime-green and red-orange sphalerite produced weak orange-red CL at room temperatures, with several emission bands centred at 490, 580, 630, 680, 745, with ??max at 630 nm being the strongest. These emission bands are well correlated with trace quantities of Sn, In, Cu and Mn activators. Sphalerite from the famous Ogdensburg and Franklin mines exhibited brilliant deep blue and orange CL colours and the blue CL may be related to Se. Cathodoluminescence behaviour of sphalerite serves to characterise ore types and help detect technologically important trace elements.

Conference Paper↗

USGS2011

Effects of wind energy production on growth, demography, and survivorship of a Desert Tortoise (Gopherus agassizii) population in Southern California with comparisons to natural populations

We studied a Desert Tortoise (Gopherus agassizii) population at a large wind energy generation facility near Palm Springs, California over six field seasons from 1997 to 2010. We compared growth and demographic parameters to populations living in less disturbed areas; as well as populations of the closely-related and newly-described G. morafkai elsewhere in the Sonoran Desert of Arizona. We marked 69 individuals of all size classes and estimated a population size of 96 tortoises, or about 15.4/km 2 . Growth rates for males were lower than reported elsewhere, although maximum body size was larger. The smallest female with shelled eggs was 221 mm and males mature at over 200 mm. Mean male size was greater than that of females. The adult sex ratio was not significantly different from unity. Size frequency histograms were similar over time and when compared to most, but not all, G. morafkai populations in the Sonoran Desert. For a cohort of adult females, we estimated mortality at 8.4% annually due, in part, to site operations. This value was low in comparison to many other populations during the same time period. Other than possible differences in growth rate of males and the high survivorship of females, there appear to be few differences between this population and those in more natural areas. The high productivity of food plants at the site and its limited public access may contribute to the overall stability of the population. However, the effects of utility-scale renewable energy development on tortoises in other, less productive, areas are unknown. Additional research (especially controlled and replicated before and after studies) is urgently needed to address this deficiency because of forecasted expansion of utility-scale renewable energy development in the future.

California↗

USGS1974

Evaluation of hydraulic characteristics of a deep artesian aquifer from natural water-level fluctuations, Miami, Florida

Knowledge of tho hydraulic characteristics of aquifer systems is fundamental to defining the vertical and horizontal controls on fluid movement, information which is needed for assessing the environmental impact of subsurface waste storage. To meet this objective, natural water-level fluctuations in the 2,947-foot deep Peninsula Utilities disposal well near Miami, Florida were analyzed to obtain estimates of the hydraulic diffusivity, hydraulic conductivity, specific storage, transmissivity, and the storage coefficient of the Boulder Zone. The fluctuations are caused chiefly by oceanic and earth tides, and by changes in atmospheric pressure. The oceanic tidal fluctuations probably result from loading due to tides in Biscayne Bay.

Florida↗

USGS2013

Natural ecosystems

Natural Ecosystems analyzes the association of observed changes in climate with changes in the geographic distributions and phenology (the timing of blossoms or migrations of birds) for Southwestern ecosystems and their species, portraying ecosystem disturbances—such as wildfires and outbreaks of forest pathogens—and carbon storage and release, in relation to climate change.

Book chapter↗

USGS1997

Natural attenuation of chlorinated hydrocarbons in a freshwater wetland

Natural attenuation of chlorinated volatile organic compounds (VOC's) occurs as ground water discharges from a sand aquifer to a freshwater wetland at Aberdeen Proving Ground, Md. Field and laboratory results indicate that biotransformation in the anaerobic wetland sediments is an important attenuation process. Relatively high concentrations of the parent compounds trichloroethylene (TCE) and 1,1,2,2-tetrachloroethane (PCA) and low or undetectable concentrations of daughter products were measured in the aquifer. In contrast, relatively high concentrations of the daughter products cis- and trans-1,2-dichloroethylene (12DCE); vinyl chloride (VC); 1,1,2-trichloroethane (112TCA); and 1,2-dichloroethane (12DCA) were measured in ground water in the wetland sediments, although total VOC concentrations decreased upward from about 1 mu mol/L (micromoles per liter) at the base of the wetland sediments to less than 0.2 near the surface. Microcosm experiments showed that 12DCE and VC are produced from anaerobic degradation of both TCE and PCA; PCA degradation also produced 112TCA and 12DCA.

Maryland↗

USGS1985

Information needs for natural fire management planning

The development and implementation of an effective natural fire management program require a clear definition of goals and objectives, an ever-expanding information base, and effective program evaluation. Examples are given from Sequoia and Kings Canyon National Parks.

Book↗

USGS1987

Below-ground herbivory in natural communities: a review emphasizing fossorial animals

Roots, bulbs, corms, and other below-ground organs are almost universally present in communities containing vascular plants. A large and taxonomically diverse group of herbivores uses these below-ground plant parts as its sole or primary source of food. Important within this group are plant-parasitic nematodes and several fossorial taxa that affect plants through their soil-disturbing activities as well as by consuming plant tissue. The fossorial taxa are probably best exemplified by fossorial rodents, which are distributed on all continents except Australia. All other fossorial herbivores are insects. The impact of below-groud herbivory on individual plant fitness will depend upon the extent to which, and under what circumstances, the consumption of plant tissue disrupts one or more of the six functions of below-ground plant parts. Below-ground herbivory is probably more often chronic than acute. Indirect evidence suggests that plants have responded evolutionarily to herbivory by enhancing the functional capacities of below-ground organs, thus developing a degree of tolerance, and by producing compounds that serve as feeding deterrents. Many plant species respond to the removal of root tissues by increasing the growth rate of the remaining roots and initiating new roots. Soil movement and mixing by fossorial rodents infleuce the environment of other below-ground herbivores as well as that of plants and plant propagules. The relationships among the various groups of below-ground herbivores, and between below-ground herbivores and plants, are at best poorly known, yet they appear to have major roles in determining the structure and regulating the functioning of natural communities.

The Quarterly Review of Biology↗

USGS2006

Impacts on water quality and biota from natural acid rock drainage in Colorado's Lake Creek watershed

Colorado's Lake Creek watershed hosts natural acid rock drainage that significantly impacts surface water, streambed sediment, and aquatic life. The source of the ARD is a group of iron-rich springs that emerge from intensely hydrothermally altered, unexploited, low-grade porphyry copper mineralization in the Grizzly Peak Caldera. Source water chemistry includes pH of 2.5 and dissolved metal concentrations of up to 277 mg/L aluminum, 498 mg/L iron, and 10 mg/L copper. From the hydrothermally altered area downstream for 27 kilometers to Twin Lakes Reservoir, metal concentrations in streambed sediment are elevated and the watershed experiences locally severe adverse impacts to aquatic life due to the acidic, metal-laden water. The water and sediment quality of Twin Lakes Reservoir is sufficiently improved that the reservoir supports a trout fishery, and remnants of upstream ARD are negligible.

Colorado↗

USGS2010

Challenges to natural resource monitoring in a small border park: terrestrial mammals at Coronado National Memorial, Cochise County, Arizona

Long-term monitoring in national parks is essential to meet National Park Service and other important public goals. Terrestrial mammals are often proposed for monitoring because large mammals are of interest to visitors and small mammals are important as prey. However, traditional monitoring strategies for mammals are often too expensive and complex to sustain for long periods, particularly in small parks. To evaluate potential strategies for long-term monitoring in small parks, we conducted an intensive one-year inventory of terrestrial mammals at Coronado National Memorial, located in Arizona on the U.S.-Mexico international border, then continued less-intensive monitoring at the site for 7 additional years. During 1996-2003 we confirmed 44 species of terrestrial mammals. Most species (40) were detected in the intensive first year of the study, but we continued to detect new species in later years. Mark-recapture data on small mammals indicated large inter-annual fluctuations in population size, but no significant trend over the 7-year period. Issues associated with the international border affected monitoring efforts and increased sampling costs. Our study confirms that sustained annual monitoring of mammals is probably not feasible in small park units like Coronado. However, comparisons of our data with past studies provide insight into important changes in the mammal community since the 1970s, including an increase in abundance and diversity of grassland rodents. Our results suggest that intensive inventories every 10-20 years may be a valuable and cost-effective approach for detecting long-term trends in terrestrial mammal communities in small natural areas.

Arizona↗

USGS1977

Solubility of natural fluorite at 25°C

The solubility products of two samples of natural fluorite from Rosiclare, Ill., and from Madoc, Ontario, were determined at 25°C by analyses of calcium and fluoride in sodium perchlorate solutions of varying ionic strength over a period of 3 years. Calcium concentrations were analyzed by atomic absorption spectrophotometry, fluoride concentrations were measured colorimetrically, and fluoride activities were measured using a specific ion electrode. The solubility products at the end of 3 years were determined by extrapolation to zero ionic strength. The final solubility product was found to be 10 -10.58±0.17 .

Journal of Research of the U.S. Geological Survey↗

USGS1976

Gamma-ray spectrometer measurement of 238 U/ 235 U in uranium ore from a natural reactor at Oklo, Gabon

About 20 years ago, Kuroda theorized that a high-grade uranium deposit emplaced about 2x10 9 years ago could achieve criticality and sustain a nuclear chain reaction, given a sufficient thickness of high-grade ore and an appropriate water content. Such a natural reactor was found in 1972 at the Oklo deposit, Gabon. The ore contains as much as 60 percent uranium, but the isotopic abundance of 235 U is as little as 0.4 percent in contrast to the normal abundance of 0.7110 percent 235 U. A sample from the Oklo deposit containing about 0.51 atom percent 235 U (by mass spectrometer) was analyzed by a gamma-ray spectrometer system, using a high-purity planar germanium detector. The 235 U was determined from its daughter's ( 234 Th) 63.3 keV photopeak; the 235 U was determined from its 143.8 and 163.4 keV photopeaks. The ratios of these photopeaks were compared with that from a standard having normal uranium isotopic content; the resulting calculations give a 235 U abundance of 0.54 atom percent in the Oklo sample. The gamma-ray spectrum also contains lines from five other isotopes in the uranium series, which indicate the Oklo sample to be at or near secular equilibrium, as the time elapsed since the nuclear reaction ended was sufficient to permit the daughters to achieve equilibrium.

Journal of Research of the U.S. Geological Survey↗

USGS1973

The fractionation of humic acids from natural water systems

Humic acids, the most abundant organic components of natural water systems, are complex mixtures of molecular aggregates of different chemical and physical properties. The first step in the study of such a mixture is the fractionation of the mixture. The most common approach with humic acids is to attempt to obtain a molecular weight fractionation by gel-permeation chromatography. However, since the preponderance of evidence indicates that the components of humic acid do not fulfill the basic criteria of uniform shape and chemical structure necessary for obtaining a molecular fractionation on gel-permeation media, molecular weight distributions in humic acids cannot be evaluated by this method. A fractionation dependent upon chemical structure can be obtained by the manipulation of elution conditions on a gel-permeation column. This procedure provides a beginning in the isolation and identification of discrete components of humic acids.

Journal of Research of the U.S. Geological Survey↗

USGS1990

Will the 1990’s be a decade of increasingly destructive natural disasters?

Today, there is a considerable body of knowledge about natural hazards that laso enables us to devise effective means to limit the damage they cause. Yet, the reality of the situation is that disasters are increasing in number worldwide, and their social and economic impacts are becoming more nad more difficult to hear.

Earthquakes & Volcanoes (USGS)↗

USGS1993

Slumgullion; Colorado’s natural landslide laboratory

The mammoth Slumgullion landslide in southwestern Colorado is the largest actively moving landslide in Colorado and, perhaps, the entire country. To learn more about how and why landslides move the way they do, scientists at the U.S Geological Survey (USGS) have observed and monitored the remarkably regular movement of this landslide for more than 30 years. Located near Lake City in the San Juan Mountains, Slumgullion was chosen for a comprehensive study of landslide processes because part of the landslide appears to have been moving continuously for the past 300 years, transporting material hundreds of meters downslope, and because the slide has the potential to threaten life and property. Surface features of the landslide, such as folds and faults within the sliding mass, are constantly changing, either being created or destroyed by the continuous movement of the landslide. Current evaluation of hazards includes possible landslide. Current evaluation of hazards includes possible landslide damage to State Highway 149 and recreational areas in the vicinity of Lake San Cristobal. The mountains of Colorado, and the Rocky Mountains in general, have one of the highest levels of landslide hazard in the nation. In a typical year, landslides hazard in the nation. In a typical year, landslides cause several fatalities and millions of dollars in damage to highways, pipelines, buildings, and forests in Colorado. To reduce such losses we need to understand why landslides occur and how they behave once they form. The Slumgullion landslide, an ideal natural laboratory, offers a unique opportunity to carefully observe and monitor the movement of a large, active landslide. In 1990, soon after the State of Colorado assigned high priority to hazard evaluation of the Slumgullion landslide, the USGS began an intensive study as part of its Landslide Hazards Reduction Program.

Colorado↗

USGS1979

A “natural and legitimate ambition . . . .”

Grove Karl Gilbert (1843-1918) was Chief Geologist for the U.S Geological Survey from 1889 to 1892. Still working for the Survey, he was in Berkeley when the 1906 earthquake struck San Francisco. Immediately on waking, he began to study the motion of the light fixture hanging from the ceiling, trying to decipher the direction of Earth waves and to time the intervals between tremors and hoping to gain some insight into the quake's magnitude. What Gilbert called a "tumult of motions and noises" brought him "unalloyed pleasure." He later announced that it was the "natural and legitimate ambition of properly constituted geologist to see a glacier, witness an eruption and feel an earthquake..." Having narrowly missed the 1872 Inyo earthquake (while with the Wheeler Survey) and the 1899 Alaska earthquake (while with the Harriman Expedition), the 63-year-old Gilbert considered the 1906 earthquake to be one fo the highlights of his career. He was to be comissioned by both the State and Federal committees that investigated the earthquake.

Earthquake Information Bulletin (USGS)↗

USGS1985

Natural hazards activities of the National Geophysical Data Center

The National Geophysical Data Center (NGDC), a part of the National Oceanic and Atmospheric Administration, has been given the task of collecting, managing, and disseminating the great mass of inofmation produced by scientific observations of the geophysical environment. This article describes NGDC data bases that speifically relate to natural hazards.

Earthquake Information Bulletin (USGS)↗

USGS1980

The natural food habits of grizzly bears in Yellowstone National Park, 1973-74

The natural food habits of grizzly bears ( Ursus arctos horribilis Ord) in Yellowstone National Park were investigated in 1973-74 to identify the grizzly's energy sources and trophic level(s), nutrient use, and distribution. Food consumption was determined by scat analysis and field observations. Food quality and digestibility were estimated by chemical analysis. Grizzlies were distributed in 3 distinctive feeding economies: valley / plateau , a grass/rodent economy where grizzlies were intensive diggers; mountain , primarily a grass/springbeauty/root economy where grizzlies were casual diggers; and lake , primarily a fish/grass economy where grizzlies were fishers. The economies occurred in areas with fertile soils; distribution of bears within each was related to the occurrence of succulent plants. The feeding cycle in the valley/plateau and mountain economies followed plant phenology. Grizzlies fed primarily on meat before green-up and on succulent herbs afterwards; meat, corms, berries, and nuts became important during the postgrowing season. Succulent grasses and sedges with an importance value percentage of 78.5 were the most important food items consumed. Protein from animal tissue was more digestible than protein from plant tissue. Storage fats were more digestible than structural fats. Food energy and digestibility were directly related. Five principle nutrient materials (listed with their percentage digestibilities) contributed to total energy intake: protein from succulent herbs, 42.8; protein and fat from animal material, 78.1; fat and protein from pine nuts, 73.6; starch, 78.8; and sugar from berries and fruits, digestibility undetermined. Protein from succulent herbs, with a nutritive value percentage of 77.3, was the grizzlies' primary energy source. Because succulent, preflowering herbs had higher protein levels than dry, mature herbs, grizzly use of succulent herbs guaranteed them the highest source of herbaceous protein. Low protein digestibility of succulent herbs was compenstated for by high intake. Grizzlies were digestively flexible and maximized use of protein from plant and animal sources. They were adapted to the most constant and abundant sources of protein: succulent herbs and animal material from open, fertile grasslands. Competition among grizzlies for animal food during the pregrowing season may be regulatory for the grizzly population. The grizzly population level can be partially accounted for by the grizzlies' status as secondary consumers during pregreen-up periods and primary consumers during the growing and postgrowing seasons. The essential environmental requirement was the availability of fertile grasslands and herblands interspersed with cover and capable of maintaining artiodactyls, rodents, and abundant nutritious herbs as sources of food.

Yellowstone National Park↗

USGS2009

Systematic approaches to comprehensive analyses of natural organic matter

The more that is learned of the chemistry of aquatic natural organic matter (NOM) the greater is the scientific appreciation of the vast complexity of this subject. This complexity is due not only to a multiplicity of precursor molecules in any environment but to their associations with each other and with other components of local environments such as clays, mineral acids and dissolved metals. In addition, this complex system is subject to constant change owing to environmental variables and microbial action. Thus, there is a good argument that no two NOM samples are exactly the same even from the same source at nearly the same time. When ubiquity of occurrence, reaction with water treatment chemicals, and subsequent human exposure are added to the list of NOM issues, one can understand the appeal that this subject holds for a wide variety of environmental scientists.

Annals of Environmental Science↗