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At least 1,693 records · Page 94Linked to original sources
USGS1993

Geologic research in support of sustainable agriculture

The importance and role of the geosciences in studies of sustainable agriculture include such traditional research areas as, agromineral resource assessments, the mapping and classification of soils and soil amendments, and the evaluation of landscapes for their vulnerability to physical and chemical degradation. Less traditional areas of study, that are increasing in societal importance because of environmental concerns and research into sustainable systems in general, include regional geochemical studies of plant and animal trace element deficiencies and toxicities, broad-scale water quality investigations, agricultural chemicals and the hydrogeologic interface, and minimally processed and ion-exchange agrominerals. We discuss the importance and future of phosphate in the US and world based on human population growth, projected agromineral demands in general, and the unavailability of new, high-quality agricultural lands. We also present examples of studies that relate geochemistry and the hydrogeologic characteristics of a region to the bioavailability and cycling of trace elements important to sustainable agricultural systems.

Agriculture, Ecosystems and Environment↗
USGS1993

Anaerobes into heavy metal: Dissimilatory metal reduction in anoxic environments

Within the last decade, a novel form of microbial metabolism of major environmental significance has been elucidated. In this process, known as dissimilatory metal reduction, specialized microorganisms, living in anoxic aquatic sediments and ground water, oxidize organic compounds to carbon dioxide with metals serving as the oxidant. Recent studies have demonstrated that this metabolism explains a number of important geochemical phenomena in ancient and modern sedimentary environments, affecting not only the cycling of metals but also the fate of organic matter. Furthermore, this metabolism may have practical application in remediation of environments contaminated with toxic metals and/or organics.

Trends in Ecology and Evolution↗
USGS1987

Concentrations of metals in mink and other mammals from Washington and Idaho

From 1981 to 1983, concentrations dfof metals were determined in mink Mustela vison , muskrats Ondatra zibethica , and small mammals at one contaminated site in Idaho and at two less contaminated sites in Idaho and Washington. The highest concentrations of Pb and Cd occurred in samples from the Coeur d'Alene River system near or downstream from an extensive mining—smelting complex in northern Idaho. Maximum concentrations of Pb in the liver of a mink (22 μg g −1 ) and in pooled liver samples of both voles ( Microtus spp. , 5·8 μg g −1 ) and deer mice ( Peromyscus maniculatus , 10·5 μg g −1 ) were higher than those inducing serious problems, including mortality, in experimental mammals on Pb-contaminated diets. Concentrations of Cd, Cu, Hg, and Zn were generally low. Declines in certain mammal populations have probably occurred in northern Idah as a result of direct toxicity of metals and associated secondary effects on cover and food supply.

Idaho, Washington↗
USGS1989

Distribution and bioaccumulation of selenium in aquatic microcosms

Closed-system microcosms were used to study factors affecting the fate of selenium (Se) in aquatic systems. Distribution and bioaccumulation of Se varied among sediment types and Se species. A mixture of dissolved 75 Se species (selenate, selenite and selenomethionine) was sorbed more rapidly to fine-textured, highly organic pond sediments than to sandy riverine sediments. Sulfate did not affect the distribution and bioaccumulation of 75 Se over the range 80–180 mg SO 4 liter −1 . When each Se species was labeled separately, selenomethionine was lost from the water column more rapidly than selenate or selenite. Selenium lost from the water column accumulated primarily in sediments, but volatilization was also an important pathway for loss of Se added as selenomethionine. Loss rates of dissolved Se residues were more rapid than rates reported from mesocosm and field studies, suggesting that sediment: water interactions are more important in microcosms than in larger test systems. Daphnids accumulated highest concentrations of Se, followed by periphyton and macrophytes. Selenium added as selenomethionine was bioaccumulated preferentially compared to that added as selenite or selenate. Organoselenium compounds such as selenomethione may thus contribute disproportionately to Se bioaccumulation and toxicity in aquatic organisms.

Environmental Pollution↗
USGS1989

Rise and fall of endrin usage in Washington state fruit orchards: Effects on wildlife

A study of the effects of endrin on wildlife was conducted from 1981 to 1983 in fruit orchards in central Washington State. The single post-harvest application of endrin as a rodenticide resulted in both acute and chronic toxicity to a variety of avian species. Of 194 birds found dead, brains of 125 were analysed; endrin toxicosis accounted for >24% of the total and 37% of those analysed. Most mortality occurred soon after application, but several raptors died during the spring and summer. Most wildlife sampled in the orchard system contained residues of endrin. There was no evidence that endrin depressed reproductive success. Use of endrin abruptly declined during this study and its use is currently limited to emergency situations. Wildlife mortality from endrin also decreased; only six endrin-related mortalities were detected the last year of the study and there have been no reports of die-offs since the study ended.

Washington↗
USGS1993

Morphological, biochemical, and histopathological indices and contaminant burdens of cotton rats (Sigmodon hispidus) at three hazardous waste sites near Houston, Texas, USA

Male cotton rats (Sigmodon hispidus) were studied at three industrial waste sites near Houston, Texas, to determine whether various morphological, biochemical, and histopathological indices provided evidence of contaminant exposure and toxic insult. Only modest changes were detected in cotton rats residing at waste sites compared with reference sites. No single parameter was consistently altered, except hepatic cytochrome P-450 concentration which was lower ( [Formula: see text] ) at two waste sites, and tended to be lower ( [Formula: see text] ) at a third waste site. Elevated petroleum hydrocarbon concentrations were detected in rats at one waste site, but contaminant burdens of rats from the other sites were unremarkable. Unlike rats captured in summer, those trapped in winter exhibited hepatocellular hypertrophy and up to a 65% increase in liver: body weight ratio, cytochrome P-450 concentration, and activities of aniline hydroxylase, aryl hydrocarbon hydroxylase, and glutathione S-transferase. Although genotoxicity has been previously documented in cotton rats residing at two of the waste sites, biomarkers in the present study provided little evidence of exposure and damage

Environmental Pollution↗
USGS1996

Metal concentrations of tadpoles in experimental ponds

Anuran tadpoles are found in a variety of habitats, many of which are acidified or have high ambient concentrations of metals from anthropogenic sources. A few studies that have been conducted on metals in tadpoles demonstrate that they can contain high concentrations of some metals but have not demonstrated clear relationships between ambient conditions and metal concentrations. This study examines the influence of soil, water treatment, amphibian species, and body portion analyzed on metal concentration in tadpoles. In northern cricket frogs, gray treefrogs, and green frogs, concentrations of Al and Fe exceeded 10 000 μg·g −1 and Mg and Mn exceeded 1000 μg g −1 . Body concentrations of Ba, Be, Fe, Mg, Mn, Ni, Pb, and Sr increased with soil concentrations. Acidification reduced body concentrations of Be and Sr, and pH correlated with Be, Mg, and Sr. Gray treefrogs had significantly lower concentrations of most metals compared to northern cricket frogs, possibly because of differences in microhabitats and soil ingestion. More than half of most metals was sequestered in the gut coil of green frog tadpoles, probably mixed with soil. Depending on bioavailablity, many of the metals in gut coils and whole bodies of these tadpoles could be potentially toxic to predators.

Maryland↗
USGS1979

Elimination of endrin by mallard ducks

Endrin is very toxic to birds and has been implicated in the deaths of birds in nature. However, it is not known how rapidly birds eliminate endrin, a factor important in determining how much is accumulated in tissues. In this study, the loss rate of endrin was followed for 64 days in mallard (Anas platyrhynchos) drakes that had been fed 20 ppm endrin for 13 days. The loss from carcass and blood was described by the equation Y = a e b square root of x where Y = the concentration of endrin in ppm, a = the concentration at day 0, e = the base of natural logarithms, b = the first order rate constant for the elimination process, and x = the number of days after cessation of endrin treatment. Endrin was lost rapidly at first; concentrations in carcasses on a wet-weight basis decreased by 50% in the first 3 days. Thereafter, endrin was eliminated more slowly; elimination of 50% of the remainder required 8.9 days, and it took 32.9 days to lose 90% of the original amount.

Toxicology↗
USGS1984

Effects of dietary excesses of branched-chain amino acids on the metabolism and tissue composition of lake trout ( Salvelinus namaycush )

1. Excesses of either leucine, isoleucine or valine were fed in separate experiments to determine if the branched-chain amino acid antagonism reported in other animals occur in trout ( Salvelinus namaycush ). 2. Parameters measured include growth rate, feed utilization efficiency, plasma and muscle-free amino acids, carcass composition and branched-chain amino acid aminotransferase. 3. Dietary excesses of leucine or isoleucine caused an increase in the valine requirement. 4. The inability of leucine and isoleucine supplementations to ameliorate the effects of excess dietary valine are interpreted as a valine toxicity rather than an antagonism.

Comparative Biochemistry and Physiology, Part A: P↗
USGS1987

Estimating threshold values for the land disposal of organic solvent-contaminated wastes

This paper describes conceptual and mathematical modeling approaches to evaluate environmentally suitable waste management practices that prevent ground water pollution from landfill disposal of solid wastes contaminated with organic solvents. Threshold values for disposal of solid wastes contaminated with acetone, nitrobenzene, chlorobenzene, and carbon tetrachloride were estimated using a disposal site model using a two-dimensional advection-,dispersion solute transport computer code. For example, the threshold value for disposal of carbon tetrachloride at the site model was approximately 600 g/acre, while the value for acetone was limited only by the characteristics of the waste to prevent free drainage of liquid solvent. The study indicated that the toxicity, mass loading rate, and the mass of solvent initially disposed are critical parameters determining the relative success of a given site to attenuate contaminants to environmentally acceptable levels.

Journal of Hazardous Materials↗
USGS1985

Sorption of lead onto two gram-negative marine bacteria in seawater

Laboratory adsorption experiments performed at environmentally significant lead (Pb) and cell concentrations indicate that the marine bacteria examined have significant binding capacities for Pb. However, the behavior governing Pb sorption onto gram-negative bacteria in seawater may be quite complex. The sorption kinetics appear to involve two distinct phases, i.e., a rapid removal of Pb from solution within the first few minutes, followed by a slow but nearly constant removal over many hours. Also, the average binding coefficient, calculated for Pb sorption onto bacteria and a measure of binding intensity, increases with decreasing sorption density (amounts of bacteria-associated Pb per unit bacterial surface) at low cell concentrations (10 5 cells ml −1 ), but decreases with decreasing sorption density at higher cell concentrations (10 7 cells ml −1 ). The latter effect is apparently due to the production of significant amounts of extra-cellular organics at high cell concentrations that compete directly with bacterial surfaces for available lead. Lead toxicity and active uptake by marine bacteria did not appear significant at the Pb concentrations used.

Marine Chemistry↗
USGS1980

Effects of petroleum hydrocarbons on hepatic function in the duck

1. The indocyanine green dye clearance test for hepatic function was determined in mallard ducks before and during the chronic ingestion (7 months) of representative paraffinic or aromatic petroleum hydrocarbons (PH). 2. No mortality or visible symptoms of toxicity occurred in any of the tests. Ingestion of 4000 ppm aromatic PH produced significant increases in liver (25%), plasma clearance of indocyanine green (33%) and hepatic blood flow (30%). 3. Although the aromatics elicited a greater hepatic stress response than the paraffins, the ducks tolerated high concentrations of PH for extended periods.

Comparative Biochemistry and Physiology, Part C: C↗
USGS1990

Geochemical evidence for Se mobilization by the weathering of pyritic shale, San Joaquin Valley, California, U.S.A.

Acidic (pH 4) seeps issue from the weathered Upper Cretaceous-Paleocene marine sedimentary shales of the Moreno Formation in the semi-arid Coast Ranges of California. The chemistry of the acidic solutions is believed to be evidence of current reactions ultimately yielding hydrous sodium and magnesium sulfate salts, e.g. mirabilite and bloedite, from the oxidation of primary pyrite. The selenate form of Se is concentrated in these soluble salts, which act as temporary geological sinks. Theoretically, the open lattice structures of these hydrous minerals could incorporate the selenate (SeO 4 −2 ) anion in the sulfate (SO 4 −2 ) space. When coupled with a semi-arid to arid climate, fractional crystallization and evaporative concentration can occur creating a sodium-sulfate fluid that exceeds the U.S. Environmental Protection Agency limit of 1000 μg l −1 for a toxic Se waste. The oxidative alkaline conditions necessary to ensure the concentration of soluble selenate are provided in the accompanying marine sandstones of the Panoche and Lodo Formations and the eugeosynclinal Franciscan assemblage. Runoff and extensive mass wasting in the area reflect these processes and provide the mechanisms which transport Se to the farmlands of the west-central San Joaquin Valley. Subsurface drainage from these soils consequently transports Se to refuge areas in amounts elevated to cause a threat to wildlife.

California↗
USGS1977

Effects of external applications of fuel oil on hatchability of mallard eggs

An experiment was performed to determine the toxicity of oil to incubating eggs. Number 2 fuel oil, a mixture of 9 paraffin compounds, and propylene glycol were applied to the surface of artificially incubated mallard ( Anas platyrhynchos ) eggs. Seven groups of 50 eggs each were treated with 1, 5, 10, 20, and 50 μl of fuel oil, 50 μ1 of the paraffin mixture, and 50 μl of propylene glycol. Fifty untreated eggs served as a control. Microliter syringes were used to apply the liquid around the air cell end of the egg on the 8th day of incubation. Embryonic mortality was significantly greater (P ≤ 0.01) in all oil treated groups and the paraffin mixture group than in the control group. Most of the embryonic mortality for the oiled eggs occurred within 72 hours of treatment. Hatching and post-hatching (4 weeks) weights of the ducklings in all treatment groups were not significantly different (P > 0.01) from the control. Thus, the transfer of even small quantities of oil to the egg surface is sufficient to reduce hatchability.

Book chapter↗
USGS2014

The environmental and medical geochemistry of potentially hazardous materials produced by disasters

Many natural or human-caused disasters release potentially hazardous materials (HM) that may pose threats to the environment and health of exposed humans, wildlife, and livestock. This chapter summarizes the environmentally and toxicologically significant physical, mineralogical, and geochemical characteristics of materials produced by a wide variety of recent disasters, such as volcanic eruptions, hurricanes and extreme storms, spills of mining/mineral-processing wastes or coal extraction by-products, and the 2001 attacks on and collapse of the World Trade Center towers. In describing these characteristics, this chapter also illustrates the important roles that geochemists and other earth scientists can play in environmental disaster response and preparedness. In addition to characterizing in detail the physical, chemical, and microbial makeup of HM generated by the disasters, these roles also include (1) identifying and discriminating potential multiple sources of the materials; (2) monitoring, mapping, and modeling dispersal and evolution of the materials in the environment; (3) understanding how the materials are modified by environmental processes; (4) identifying key characteristics and processes that influence the materials' toxicity to exposed humans and ecosystems; (5) estimating shifts away from predisaster environmental baseline conditions; and (6) using geochemical insights learned from past disasters to help estimate, prepare for, and increase societal resilience to the environmental and related health impacts of future disasters.

Book chapter↗
USGS2014

Bioavailability and bioaccumulation of metal-based engineered nanomaterials in aquatic environments: Concepts and processes

Bioavailability of Me-ENMs to aquatic organisms links their release into the environment to ecological implications. Close examination shows some important differences in the conceptual models that define bioavailability for metals and Me-ENMs. Metals are delivered to aquatic animals from Me-ENMs via water, ingestion, and incidental surface exposure. Both metal released from the Me-ENM and uptake of the nanoparticle itself contribute to bioaccumulation. Some mechanisms of toxicity and some of the metrics describing exposure may differ from metals alone. Bioavailability is driven by complex interaction of particle attributes, environmental transformations, and biological traits. Characterization of Me-ENMs is an essential part of understanding bioavailability and requires novel methodologies. The relative importance of the array of processes that could affect Me-ENM bioavailability remains poorly known, but new approaches and models are developing rapidly. Enough is known, however, to conclude that traditional approaches to exposure assessment for metals would not be adequate to assess risks from Me-ENMs.

Book chapter↗
USGS2021

Radionuclides in surface water and groundwater

Unique among all the contaminants that adversely affect surface- and groundwater quality, radioactive compounds pose a double threat from toxicity and ionizing radiation. The high energy potential of many of these materials makes them both useful and hazardous. The unique properties of radioactive materials make them invaluable for medical and energy applications. However, mining, production, use, and disposal of compounds and their byproducts provide potential pathways for their release into the environment, posing a risk to both humans and ecosystems. This chapter presents an overview of the sources and uses of radioactive compounds in the United States, biogeochemical processes that control mobility in the environment, examples of radionuclide contamination, and an overview of remediation strategies.

Book chapter↗
USGS2018

Environmental characteristics and utilization potential of metallurgical slag

Slag, an abundant byproduct from the pyrometallurgical processing of ores, can be an environmental liability or a valuable resource. The most common environmental impact of slag is from the leaching of potentially toxic elements, acidity, or alkalinity that may impact nearby soils and surface water and groundwater. Factors that influence its environmental behavior include physical characteristics, such as grain size and porosity, chemical composition with some slag being enriched in certain elements, the mineralogy and partitioning of elements in more or less reactive phases, water-slag interactions, and site conditions. Many of these same factors also influence its resource potential. For example, crystalline ferrous slag is most commonly used as construction aggregate, whereas glassy (i.e., granulated) slag is used in cement. Also, the calcium minerals found in ferrous slag result in useful applications in water treatment. In contrast, the high trace-element content of some base-metal slags makes the slags economically attractive for extraction of residual elements. An evaluation tool is used to help categorize a particular slag as an environmental hazard or valuable byproduct. Results for one type of slag, legacy steelmaking slag from the Chicago area in the USA, suggest the material has potential to be used for treating phosphate-rich or acidic waters; however, the pH and trace-element content of resulting solutions may warrant further examination.

Book chapter↗