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At least 811 records · Page 45Linked to original sources
USGS1999

Design approaches in quarrying and pit-mining reclamation

Reclaimed mine sites have been evaluated so that the public, industry, and land planners may recognize there are innovative designs available for consideration and use. People tend to see cropland, range, and road cuts as a necessary part of their everyday life, not as disturbed areas despite their high visibility. Mining also generates a disturbed landscape, unfortunately one that many consider waste until reclaimed by human beings. The development of mining provides an economic base and use of a natural resource to improve the quality of human life. Equally important is a sensitivity to the geologic origin and natural pattern of the land. Wisely shaping out environment requires a design plan and product that responds to a site's physiography, ecology, function, artistic form, and publication perception. An examination of selected sites for their landscape design suggested nine approaches for mining reclamation. The oldest design approach around is nature itself. Humans may sometimes do more damage going to an area in the attempt to repair it. Given enough geologic time, a small-site area, and stable adjacent ecosystems, disturbed areas recover without mankind's input. Visual screens and buffer zones conceal the facility in a camouflage approach. Typically, earth berms, fences, and plantings are used to disguise the mining facility. Restoration targets social or economic benefits by reusing the site for public amenities, most often in urban centers with large populations. A mitigation approach attempts to protect the environment and return mined areas to use with scientific input. The reuse of cement, building rubble, macadam meets only about 10% of the demand from aggregate. Recognizing the limited supply of mineral resources and encouraging recycling efforts are steps are steps in a renewable resource approach. An educative design approach effectively communicates mining information through outreach, land stewardship, and community service. Mine sites used for art show a celebration of beauty and experience -- abstract geology. The last design approach combines art and science in a human-nature ecosystem termed integration. With environmental concerns, an operating or reclaimed mine site can no longer be considered isolated from its surroundings. Site analysis of mine works needs to go beyond site-specific information and relate to the regional context of the greater landscape. Understanding design approach can turn undesirable features (mines and pits) into something perceived as desirable by the public.

Book↗
USGS2014

Report of the committee on chemistry of natural waters, 1938–39

The membership of this Committee is as follows: C. S. Howard (Chairman), United States Geological Survey, Washington, D.C. I. A. Denison, National Bureau of Standards, Washington, D.C. W. P. Kelley, 119 Hilgard Hall, University of California, Berkeley, California A. C. Lane, 22 Arlington Street, Cambridge, Massachusetts C. S. Scofield, Bureau of Plant Industry, United States Department of Agriculture, Washington, D.C. D. G. Thompson, United States Geological Survey, Washington, D.C. T. G. Thompson, University of Washington, Seattle, Washington Studies on the corrosion of metals and soils have been continued at the National Bureau of Standards and a report of the recent findings was published under the title “Correlation of the electrolytic corrosion test with the active corrosiveness of soils,” by I. A. Denison and R. B. Darnielle [J. Res., Nation. Bur. Stan., No. 21, pp. 819‐830, December, 1938], Another paper on this subject by Kirk H. Logan was published under the title “Engineering significance of National Bureau of Standards soil corrosion data” [J. Res. Nation. Bur. Stan., pp. 109–125, January. 1939].

Eos, Transactions, American Geophysical Union↗
USGS2015

Nutrient-enhanced decomposition of plant biomass in a freshwater wetland

We studied soil decomposition in a Panicum hemitomon (Schultes)-dominated freshwater marsh located in southeastern Louisiana that was unambiguously changed by secondarily-treated municipal wastewater effluent. We used four approaches to evaluate how belowground biomass decomposition rates vary under different nutrient regimes in this marsh. The results of laboratory experiments demonstrated how nutrient enrichment enhanced the loss of soil or plant organic matter by 50%, and increased gas production. An experiment demonstrated that nitrogen, not phosphorus, limited decomposition. Cellulose decomposition at the field site was higher in the flowfield of the introduced secondarily treated sewage water, and the quality of the substrate (% N or % P) was directly related to the decomposition rates. We therefore rejected the null hypothesis that nutrient enrichment had no effect on the decomposition rates of these organic soils. In response to nutrient enrichment, plants respond through biomechanical or structural adaptations that alter the labile characteristics of plant tissue. These adaptations eventually change litter type and quality (where the marsh survives) as the % N content of plant tissue rises and is followed by even higher decomposition rates of the litter produced, creating a positive feedback loop. Marsh fragmentation will increase as a result. The assumptions and conditions underlying the use of unconstrained wastewater flow within natural wetlands, rather than controlled treatment within the confines of constructed wetlands, are revealed in the loss of previously sequestered carbon, habitat, public use, and other societal benefits.

Louisiana↗
USGS2025

Soil-microbial communities respond less than plant communities to synthetic- or bio-herbicides applied to address the exotic grass-fire cycle in rangelands

The exotic grass-fire cycle is degrading semiarid rangelands, such as the vast areas of shrub-steppe in North America now invaded by fire-promoting cheatgrass. Chemical- or bio-herbicides are sprayed onto soils to inhibit the invaders, but information on chemical- or bio-herbicide impacts to soil microbial communities is limited. We asked how the soil-microbiome responded to the bioherbicide Pseudomonas fluorescens strain ACK55 in comparison to the separate and combined effects of a conventional pre-emergent chemical herbicide, imazapic, in two cheatgrass-invaded sagebrush-steppe sites. First-year microbial responses were evaluated using targeted sequencing of the 16S and LSU rRNA genes for bacteria+archaea and fungi, respectively, and were related to plant-community responses. A strong cheatgrass reduction with imazapic at one site was accompanied by a small shift in bacteria+archaea (16S) community composition with no effect on microbial alpha diversity, and this shift was small in comparison to natural microbiome variation between sites. ACK55 was not detected in soil a year after application, and it caused only transient and marginally significant reductions in annual grass cover accompanied by small reductions in soil fungi species richness. Full-length sequencing of the ACK55 16S rRNA gene and phylogenetic analyses revealed that ACK55 is more likely P. salmonii than P. fluorescens . Knowledge gaps remain on the duration and consequences of microbial-community shifts with imazapic and why molecular analyses showed ACK55 did not persist in soils. Confusion regarding microbial biopesticides can result where isolation, effectiveness testing, commercial release, and regulation are not guided by molecular taxonomic analyses.

Idaho↗
USGS2021

Nonlinear shifts in infectious rust disease due to climate change

Range shifts of infectious plant disease are expected under climate change. As plant diseases move, emergent abiotic-biotic interactions are predicted to modify their distributions, leading to unexpected changes in disease risk. Evidence of these complex range shifts due to climate change, however, remains largely speculative. Here, we combine a long-term study of the infectious tree disease, white pine blister rust, with a six-year field assessment of drought-disease interactions in the southern Sierra Nevada. We find that climate change between 1996 and 2016 moved the climate optimum of the disease into higher elevations. The nonlinear climate change-disease relationship contributed to an estimated 5.5 (4.4–6.6) percentage points (p.p.) decline in disease prevalence in arid regions and an estimated 6.8 (5.8–7.9) p.p. increase in colder regions. Though climate change likely expanded the suitable area for blister rust by 777.9 (1.0–1392.9) km 2 into previously inhospitable regions, the combination of host-pathogen and drought-disease interactions contributed to a substantial decrease (32.79%) in mean disease prevalence between surveys. Specifically, declining alternate host abundance suppressed infection probabilities at high elevations, even as climatic conditions became more suitable. Further, drought-disease interactions varied in strength and direction across an aridity gradient—likely decreasing infection risk at low elevations while simultaneously increasing infection risk at high elevations. These results highlight the critical role of aridity in modifying host-pathogen-drought interactions. Variation in aridity across topographic gradients can strongly mediate plant disease range shifts in response to climate change.

California↗
USGS2015

Metagenomic analysis of planktonic microbial consortia from a non-tidal urban-impacted segment of James River

Knowledge of the diversity and ecological function of the microbial consortia of James River in Virginia, USA, is essential to developing a more complete understanding of the ecology of this model river system. Metagenomic analysis of James River's planktonic microbial community was performed for the first time using an unamplified genomic library and a 16S rDNA amplicon library prepared and sequenced by Ion PGM and MiSeq, respectively. From the 0.46-Gb WGS library (GenBank:SRR1146621; MG-RAST:4532156.3), 4 × 10 6 reads revealed >3 × 10 6 genes, 240 families of prokaryotes, and 155 families of eukaryotes. From the 0.68-Gb 16S library (GenBank:SRR2124995; MG-RAST:4631271.3; EMB:2184), 4 × 10 6 reads revealed 259 families of eubacteria. Results of the WGS and 16S analyses were highly consistent and indicated that more than half of the bacterial sequences were Proteobacteria , predominantly Comamonadaceae . The most numerous genera in this group were Acidovorax (including iron oxidizers, nitrotolulene degraders, and plant pathogens), which accounted for 10 % of assigned bacterial reads. Polaromonas were another 6 % of all bacterial reads, with many assignments to groups capable of degrading polycyclic aromatic hydrocarbons. Albidiferax (iron reducers) and Variovorax (biodegraders of a variety of natural biogenic compounds as well as anthropogenic contaminants such as polycyclic aromatic hydrocarbons and endocrine disruptors) each accounted for an additional 3 % of bacterial reads. Comparison of these data to other publically-available aquatic metagenomes revealed that this stretch of James River is highly similar to the upper Mississippi River, and that these river systems are more similar to aquaculture and sludge ecosystems than they are to lakes or to a pristine section of the upper Amazon River. Taken together, these analyses exposed previously unknown aspects of microbial biodiversity, documented the ecological responses of microbes to urban effects, and revealed the noteworthy presence of 22 human-pathogenic bacterial genera (e.g., Enterobacteriaceae , pathogenic Pseudomonadaceae , and ‘ Vibrionales' ) and 6 pathogenic eukaryotic genera (e.g., Trypanosomatidae and Vahlkampfiidae). This information about pathogen diversity may be used to promote human epidemiological studies, enhance existing water quality monitoring efforts, and increase awareness of the possible health risks associated with recreational use of James River.

Virginia↗
USGS2013

Relationships between the health of Alaska Native communities and our environment -- phase 1, exploring and communicating

Alaska Natives depend on local natural resources for nutritional and, for many, spiritual health. As a result, public health in Alaska is strongly influenced by the relationship between people and their surrounding physical, chemical, and biological environments. Alaska is vast with diverse wildlife and plant communities that are valued as subsistence foods (fig. 1). These resources are supported by equally diverse ecosystems and their underpinning landforms and geologies. The U.S. Geological Survey (USGS) is attempting to integrate physical, chemical, and biological information to better describe current (2013) environments and project scenarios for the future. Integrating ecological data into the public health dialogue is challenging for the more than 280 rural communities of Alaska. This fact sheet reviews a recent USGS effort, the Geographic Information System (GIS) Native Health Project, to better incorporate scientific information into such dialogue.

Alaska↗
USGS2015

Fire history of Everglades National Park and Big Cypress National Preserve, southern Florida

Fire occurs naturally in the environment on most continents, including Africa (Ryan and Williams, 2011), Asia (Kauhanen, 2008), Australia (Kutt and Woinarski, 2007), Europe (Eshel and others, 2000), South America (Fidelis and others, 2010), and North America (Van Auken, 2000). Antarctica appears to be the only continent that has no reported natural fires, although fire is common in grasslands of Patagonia and on islands in the Subantarctic region (Gonzalez and others, 2005; McGlone and others, 2007). Natural fires also have occurred over thousands of years, and the frequencies of these natural fires have changed (Power and others, 2008). This has resulted in altered ecosystems at landscape scales. Recent evidence suggests that the treeless desert pastures of Tibet once were forests and woodlands, and charcoal deposits indicate that fire was more frequent in the past (Miehe and others, 2006). Human cultural development has been influenced by changes in natural fire frequencies. Zong and others (2007) reported that human suppression of fires in coastal areas of China allowed the development of rice paddy cultivation and, thus, increased the size of human populations. In addition to its almost world-wide occurrence, fire plays a role in a wide variety of ecosystem types. Grassland, savanna, steppe, woodland, forest, and wetland ecosystems all have fire as part of their natural ecology (Veblen and Lorenz, 1988; Chokkalingam and others, 2007; Miller and others, 2009, Keith and others, 2010; Staver and others, 2011). Fires affect these ecosystems in various ways, the most obvious of which is the direct effect on plant biomass (for example, Van Wilgen, 1982; Mack and others, 2008). However, fire has many other effects on ecosystems. Plant species richness, diversity, and functional types can change in response to fire (Peterson and Reich, 2008). All properties of the surface soils (such as bulk density, particle size distribution, pH, and organic carbon and nitrogen content) can be altered by the frequency and severity of fire (Boerner and others, 2009). Faunal communities will respond to fire, with some species increasing (Fuhlendorf and others, 2006) and other species decreasing, after the fire (Vasconcelos and others, 2009).The position of the ecotone between differing ecosystems also is influenced by fire occurrence (Heisler and others, 2003; Briggs and others, 2005; Smith and others, 2013). Fire has been used as a management tool in various ecosystems around the world. Prairies, grasslands, and savannas are fire-maintained ecosystems where fire is used to deter invasion by shrubs and trees (Grant and others, 2009; Scheintaub and others, 2009). Similarly, fire plays an important role in woodlands and forests by influencing species composition and succession such, as the use of fire in coniferous forests to prevent encroachment by hardwoods (Phillippe and others, 2011). Fire also has been used to manage wetland ecosystems for more than 50 years (Lynch, 1941; Frost, 1995). Uses have included returning marshes to early successional states, increasing forage for wildlife (Lynch, 1941). In all fire-influenced ecosystems, prescribed burns are routinely used to reduce fuel loads, reducing the possibility of catastrophic fires.

Florida↗
USGS1970

Geologic evaluation of 3-5 micrometer infrared imagery and color photography in southern Utah

A comparison of 3-5 micrometer, afternoon and midnight infrared (IR) imagery and color photography with conventional aerial photography shows that IR imagery and color photography have some unique capabilities. In general, the IR imagery provides in shades of gray a record of the relative ground temperature at the time the image was taken. It has day or night capabilities for imaging large areas of terrain. In sparsely vegetated areas, midnight IR imagery shows some tonal variations that may be relate to specific rock type based on temperature differences. In heavily vegetated areas, any temperature difference that might exist between rock units is masked by the temperature difference associated with different vegetation communities; although, isolated outcrops in such areas are generally apparent because they are brighter (warmer) on the afternoon IR. On the midnight IR they may or may not be brighter according to their differences in thermal inertia. The afternoon IR image showed one fault that was not visible on the aerial photographs. In contrast, only some of the faults visible in the stereoscopic model were recognized on the IR imagery. The interpreter using IR imagery must be aware of changes in heat patterns resulting from modification of the land by man and from the effect of cloud shadows. Apparent anomalies on IR image resulting from such factors might be misinterpreted. Compared to conventional photography with the added ability of stereoscopic viewing the day and night IR provided less geologic information in the area of study. IR imagery may be useful in hydrologic studies such as the relative temperatures of alpine lakes, ponds, and marshes during the night. and day. It should prove valuable in ecological studies involving the relative temperatures of different plant communities. Roads in heavily wooded areas are easier to see on the IR image, than on conventional photography because of their temperature differences. Color photography, as might be expected, shows the terrain in a close approximation to its natural color, and delineates some stratigraphic units and rock alterations that are indistinguishable on black and white photography.

Utah↗
USGS2008

Water quality in the Arthur R. Marshall Loxahatchee National Wildlife Refuge — Trends and spatial characteristics of selected constituents, 1974-2004

Water quality in the interior marsh of the Arthur R. Marshall Loxahatchee National Wildlife Refuge is characterized by low concentrations of major ions, principally sodium and chloride, and is affected primarily by natural seasonal processes, such as evapotranspiration, rainfall, and biological activity. During the dry season, evapotranspiration exceeds precipitation, and specific conductance and conservative ion concentrations at marsh background sites typically increase by 40-70 percent between the end of the rainy season in September and the end of the dry season in May. Water enters the Refuge mainly from rainfall and perimeter canals. Water is pumped into the perimeter canals from large pumping stations, such as S-5A and S-6. In recent years, much of the water pumped into the Refuge passes through Stormwater Treatment Areas (STAs) before being released into the perimeter canals that surround the Refuge. Since 2001, water at S-6 has been diverted south toward STA-2, away from the Refuge perimeter canals. Water from S-5A and S-6 flows through agricultural lands with intense agricultural activity and typically contains relatively high concentrations of major ions, nutrients, and pesticides. Specific conductance, major-ion concentrations, and nutrient concentrations are an order of magnitude higher at S-5A and S-6 canal sites than at interior marsh sites. Water quality in the marsh bordering the canals can be affected substantially by the canal water, and these effects can extend several miles or more into the marsh depending on location in the Refuge and on the water level in the canals. As canal water flows into the marsh, processes such as uptake by periphyton and rooted vegetation and settling of particulate matter reduce the concentrations of nutrients to a greater extent than conservative ions such as chloride. Long- and short-term trends for specific conductance, chloride ion, sulfate ion, total phosphorus, and total nitrogen at five sites were evaluated primarily using an uncensored seasonal Kendall test with a water-level adjustment to reduce the effects of long wet or dry periods. Significant long-term trends (1974-2003) for specific conductance, chloride, total phosphorus, and total nitrogen at canal sites S-5A and S-6 were generally downward. Of the five sites, S-5A had the most pronounced decline for specific conductance at about -340 microsiemens per centimeter (?S/cm), followed by S-6 with a decline of about -280 ?S/cm. The two internal marsh sites, LOX8 and LOX13, had significant long-term trends in specific conductance of about +37 and -36 ?S/cm, respectively. Long-term trends for other constituents at the two internal marsh sites were generally small in magnitude or not measurable between 1978 and 2003. Marsh site LOX15 near the Hillsboro Canal showed no long-term trends, although specific conductance and sulfate concentration increased about 560 ?S/cm and 30 milligrams per liter, respectively, from 1998 to 2002. Site LOX15 is influenced strongly by intrusions of canal water, and increases in specific conductance and sulfate at this site coincided with increased canal-water inflows from STA-1W between 2001 and 2003. Median concentrations at LOX13 and S-5A were used to represent background and canal concentrations, respectively. Based on these values, the median chloride concentration at LOX15 indicates that the water is typically about 31 percent canal water and 69 percent ?natural? background water. Using median sulfate concentrations, similarly to chloride, the fraction of water at LOX15 was estimated to be 17 percent from canals and 83 percent from ?natural? background water. This finding suggests that in the low sulfate environment of the Refuge, sulfate is not conservative and only about half of the sulfate from canal water typically reaches LOX15; the rest presumably is removed by marsh plants, algae, and bottom sediments. Concentrations of pesticides and other organic compounds were measured

Florida↗
USGS2016

Desert Scrublands

Desert scrublands comprise the lower to mid-elevation portions of four different ecosystems including the Chihuahuan, Great Basin, Mojave and Sonoran Deserts. Together the area inside their outer boundaries includes over 8% of the surface area of the United States. Despite significant differences in the flora and fauna of these bioregions they all share the common trait of being arid shrub-steppe ecosystems, receiving, on average, less than 254 mm of rain per year. The austere nature of these landscapes belies their significant biodiversity, the amazing behavioral and physiological adaptations of the biota, and the fragility of the ecosystems to human disturbances. For example, the Mojave Desert alone has at least 250 species of ephemeral plants, mostly winter annuals, and up to 90% are endemic.

Arizona, California, Colorado, Nevada, New Mexico,↗
USGS2024

Global assessment of aquatic Isoëtes species ecology

Isoëtes are iconic but understudied wetland plants, despite having suffered severe losses globally mainly because of alterations in their habitats. We therefore provide the first global ecological assessment of aquatic Isoëtes to identify their environmental requirements and to evaluate if taxonomically related species differ in their ecology. The assessment resulted in an extensive new database on aquatic Isoëtes , ecological niche analyses, and descriptive species accounts. We compiled a global database that includes all known environmental data collected from 1935 to 2023 regarding aquatic Isoëtes. We then evaluated the environmental drivers of 16 species using 2,179 global records. Additionally, we used hypervolume analysis to quantify the ecological niches of the two species with the greatest number of records, finding significant differences and evidence that Isoëtes echinospora occupies a wider ecological niche than Isoëtes lacustris . Fifty-nine species (30% of the c. 200 Isoëtes species known today) were categorised as aquatic and were mainly reported in the Americas and northern Europe. About 38% of the aquatic species are threatened with extinction or are endemic to a small region, according to the International Union for Conservation of Nature's Red List in 2023. Many species were determined to be sensitive to certain water physical and chemical factors, generally preferring oligotrophic conditions such as low total phosphorus, moderate total nitrogen, moderate to low pH, and low conductivity. This analysis includes ecological data in the assessment of rare/threatened aquatic plants globally. This new database and the ecological analyses completed defined the ecological requirements of several species and identified knowledge gaps, which can aid management actions and future research. This paper highlights ecological significance and environmental sensitivities of aquatic Isoëtes . The current level of knowledge is inadequate for a large proportion of known taxa. We affirm the extreme need to support global, collaborative initiatives on which to build future conservation strategies.

Freshwater Biology↗
USGS2007

Ecological Investigations of the Federally Endangered Shivwits Milk-Vetch (Astragalus ampullarioides)--2006 Annual Report

Astragalus ampullarioides (Welsh) Welsh, the Shivwits milk-vetch, is an herbaceous perennial legume that was listed as federally endangered in September 2001. Known populations of this edaphic endemic species are restricted to Washington County, Utah, with the majority of occurrences found on gently sloping outcrops of the Triassic Petrified Forest Member of the Chinle Formation at the edge of the Mojave Desert. At the time of listing in 2001, surveys estimated a total of 1000 individuals for the species. In April-May 2006, surveys estimated approximately 4205 individuals distributed among six populations. Of the total number of individuals estimated in spring 2006, over 75 percent were distributed among three subpopulations in Zion National Park and approximately 60 percent occurred at a single 0.3-ha site in the Park. In addition to small population sizes and limited geographic distributions, the species is threatened to varying degrees by urbanization, livestock grazing, off-road vehicle use, and invasive exotic plants. In April 2006, the U.S. Geological Survey (USGS) initiated ecological investigations of the Shivwits milk-vetch to support conservation management and recovery of the species by the National Park Service (NPS; Zion National Park), the U.S. Fish and Wildlife Service (USFWS), the Bureau of Land Management (BLM), the Shivwits Band of the Paiute Tribe, and other cooperators such as The Nature Conservancy of Utah (TNC). To date, funding for this research has been provided by the Southwest Biological Science Center of the USGS Biological Resources Discipline, the USGS-NPS Park-Oriented Biological Support Project, and the Earth Surface Dynamics Program of the USGS Geologic Discipline. Additional logistical support has been provided by the Bureau of Land Management, Grand Staircase-Escalante National Monument. General objectives of this research are (1) to develop a better understanding of species-environment relations to support habitat modelling, future surveys for additional recovery populations, and potential efforts to establish new recovery populations; and (2) to evaluate effects of invasive exotic plants on habitat conditions and measures of milk-vetch performance. Specific objectives are to: Describe the distribution and abundance of milk-vetch populations and associated invasive exotic plant species within and outside of Zion National Park (Zion NP) in relation to geologic / geomorphic setting, soil properties, and plant community composition. In a field setting in Zion NP, conduct experiments to evaluate effects of invasive exotic plants on reproductive output and seedling establishment of A. ampullarioides across a gradient of exotic species biomass. Conduct greenhouse studies and analyze soils to evaluate effects of invasive exotic plants on soil biological properties (including mycorrhizal inocculation potential) that affect cycling and plant uptake of essential mineral nutrients. Based on environmental characteristics of known population locations, use Geographic Information System (GIS) tools to prepare a predictive habitat model that can be used to guide future surveys and efforts to evaluate sites for reintroduction efforts. This report describes 2006 progress and future plans for achieving these four objectives.

Open-File Report↗
USGS2000

Hydrogeology and simulation of ground-water flow at the Gettysburg Elevator Plant Superfund Site, Adams County, Pennsylvania

Ground water in Triassic-age sedimentary fractured-rock aquifers in the area of Gettysburg, Pa., is used as drinking water and for industrial and commercial supply. In 1983, ground water at the Gettysburg Elevator Plant was found by the Pennsylvania Department of Environmental Resources to be contaminated with trichloroethene, 1,1,1-trichloroethane, and other synthetic organic compounds. As part of the U.S. Environmental Protection Agency?s Comprehensive Environmental Response, Compensation, and Liability Act, 1980 process, a Remedial Investigation was completed in July 1991, a method of site remediation was issued in the Record of Decision dated June 1992, and a Final Design Report was completed in May 1997. In cooperation with the U.S. Environmental Protection Agency in the hydrogeologic assessment of the site remediation, the U.S. Geological Survey began a study in 1997 to determine the effects of the onsite and offsite extraction wells on ground-water flow and contaminant migration from the Gettysburg Elevator Plant. This determination is based on hydrologic and geophysical data collected from 1991 to 1998 and on results of numerical model simulations of the local ground-water flow-system. The Gettysburg Elevator Site is underlain by red, green, gray, and black shales of the Heidlersburg Member of the Gettysburg Formation. Correlation of natural-gamma logs indicates the sedimentary rock strike about N. 23 degrees E. and dip about 23 degrees NW. Depth to bedrock onsite commonly is about 6 feet but offsite may be as deep as 40 feet. The ground-water system consists of two zones?a thin, shallow zone composed of soil, clay, and highly weathered bedrock and a thicker, nonweathered or fractured bedrock zone. The shallow zone overlies the bedrock zone and truncates the dipping beds parallel to land surface. Diabase dikes are barriers to ground-water flow in the bedrock zone. The ground-water system is generally confined or semi-confined, even at shallow depths. Depth to water can range from flowing at land surface to more than 71 feet below land surface. Potentiometric maps based on measured water levels at the Gettysburg Elevator Plant indicate ground water flows from west to east, towards Rock Creek. Multiple-well aquifer tests indicate the system is heterogeneous and flow is primarily in dipping beds that contain discrete secondary openings separated by less permeable beds. Water levels in wells open to the pumped bed, as projected along the dipping stratigraphy, are drawn down more than water levels in wells not open to the pumped bed. Ground-water flow was simulated for steady-state conditions prior to pumping and long-term average pumping conditions. The three-dimensional numerical flow model (MODFLOW) was calibrated by use of a parameter estimation program (MODFLOWP). Steady-state conditions were assumed for the calibration period of 1996. An effective areal recharge rate of 7 inches was used in model calibration. The calibrated flow model was used to evaluate the effectiveness of the current onsite and offsite extraction well system. The simulation results generally indicate that the extraction system effectively captures much of the ground-water recharge at the Gettysburg Elevator Plant and, hence, contaminated ground-water migrating from the site. Some of the extraction wells pump at low rates and have very small contributing areas. Results indicate some areal recharge onsite will move to offsite extraction wells.

Pennsylvania↗
USGS2017

Aridity increases below-ground niche breadth in grass communities

Aridity is an important environmental filter in the assembly of plant communities worldwide. The extent to which root traits mediate responses to aridity, and how they are coordinated with leaf traits, remains unclear. Here, we measured variation in root tissue density (RTD), specific root length (SRL), specific leaf area (SLA), and seed size within and among thirty perennial grass communities distributed along an aridity gradient spanning 190–540 mm of climatic water deficit (potential minus actual evapotranspiration). We tested the hypotheses that traits exhibited coordinated variation (1) among species, as well as (2) among communities varying in aridity, and (3) functional diversity within communities declines with increasing aridity, consistent with the “stress-dominance” hypothesis. Across communities, SLA and RTD exhibited a coordinated response to aridity, shifting toward more conservative (lower SLA, higher RTD) functional strategies with increasing aridity. The response of SRL to aridity was more idiosyncratic and was independent of variation in SLA and RTD. Contrary to the stress-dominance hypothesis, the diversity of SRL values within communities increased with aridity, while none of the other traits exhibited significant diversity responses. These results are consistent with other studies that have found SRL to be independent of an SLA–RTD axis of functional variation and suggest that the dynamic nature of soil moisture in arid environments may facilitate a wider array of resource capture strategies associated with variation in SRL.

Plant Ecology↗
USGS1988

Use of "specific" inhibitors in biogeochemistry and microbial ecology

The above statement, although meant to be tongue in cheek, contains an essential truism: all work with inhibitors is inherently suspect. This fact has been known by biochemists for some time. However, use of chemical inhibitors of enzymic systems and membranes continues to be a common approach taken toward unraveling the biochemistry and biophysics of plants, animals, and microorganisms. Various types of “broad-spectrum” biochemical inhibitors (e.g., poisons, respiratory inhibitors, and uncouplers) have been employed by ecologists for many years in order to demonstrate the active participation of microbes in chemical reactions occurring in natural samples (e.g., soils, sediments, and water). In recent years, considerable advances have been made in our understanding of the biochemistry of microorganisms of biogeochemical interest. Concurrent with these advances have been the discoveries of novel types of compounds that will block the metabolism of one particular group of microbes, but have little disruptive effect on other physiological types. Thus, the term “specific inhibitor” has been applied to these types of compounds when they are used to probe the functions of mixed populations of microorganisms. These substances provide powerful experimental tools for investigating the activity and function of certain types of microorganisms in natural samples.

Book chapter↗
USGS1998

Determination of methane concentrations in shallow ground water and soil gas near Price, Utah

Methane gas, commonly referred to as "natural gas," is being produced from coal beds in central Utah (fig. 1) at an increasing rate since the early 1990s. The methane was generated over millions of years during the formation of coal in the area. Coal originates as plant matter that has been deposited in a swamp-like environment and then decays as it is buried and compressed over geologic time. Giant fossilized footprints in the coal provide evidence that dinosaurs roamed and fed among the plentiful plants in these swamps (Hintze, 1979). Methane and carbon dioxide gas and water are produced in the coal as byproducts of coal formation (Sommer and Gloyn, 1993).

Utah↗
USGS2009

Northern Prairie Wildlife Research Center

The Northern Prairie Wildlife Research Center (NPWRC) conducts integrated research to fulfill the Department of the Interior's responsibilities to the Nation's natural resources. Located on 600 acres along the James River Valley near Jamestown, North Dakota, the NPWRC develops and disseminates scientific information needed to understand, conserve, and wisely manage the Nation's biological resources. Research emphasis is primarily on midcontinental plant and animal species and ecosystems of the United States. During the center's 40-year history, its scientists have earned an international reputation for leadership and expertise on the biology of waterfowl and grassland birds, wetland ecology and classification, mammalian behavior and ecology, grassland ecosystems, and application of statistics and geographic information systems. To address current science challenges, NPWRC scientists collaborate with researchers from other U.S. Geological Survey centers and disciplines (Biology, Geography, Geology, and Water) and with biologists and managers in the Department of the Interior (DOI), other Federal agencies, State agencies, universities, and nongovernmental organizations. Expanding upon its scientific expertise and leadership, the NPWRC is moving in new directions, including invasive plant species, restoration of native habitats, carbon sequestration and marketing, and ungulate management on DOI lands.

Fact Sheet↗