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At least 631 records · Page 35Linked to original sources
USGS2019

Monitoring the Riverine Pulse: Applying high-frequency nitrate data to advance integrative understanding of biogeochemical and hydrological processes

Widespread deployment of sensors that measure river nitrate (NO3-) concentrations has led to many recent publications in water resources journals including review papers focused on data quality assurance, improved load calculations, and better nutrient management. The principal objective of this paper is to review and synthesize studies of high-frequency NO3- data that have aimed to improve understanding of the hydrologic and biogeochemical processes underlying episodic, diel, and long-term stream NO3- dynamics. Investigations have provided unprecedented detail on hysteresis and flushing patterns during high flow, seasonal variation during baseflow, and responses to multi-year climate variation. Analyses of high-frequency data have led to notable advances in understanding how climate variation affects spatial and temporal NO3- patterns, especially dry-wet cycles and antecedent moisture. Further advances have been limited by few investigations that include high-frequency measurements outside the channel and the short duration of many records. High-frequency data for multiple constituents have provided new insight to the relative roles of hydrology and biogeochemistry as highlighted by studies of the roles of autotrophic uptake, denitrification, riparian evapotranspiration, and temperature-driven changes in viscosity as drivers of diel patterns. Comparisons of short-duration high-frequency data with long-duration low frequency data have described similarities and differences in concentration – discharge patterns and highlighted the role of legacy stores. Investigators have applied innovative analysis approaches not previously possible with low-frequency or temporally-irregular data. Future availability of long-duration high-frequency data will provide new insight to processes, resulting in improved conceptual models and a deeper understanding of the role of climate variation.

WIREs Water↗
USGS1994

Drainage investment and wetland loss: an analysis of the national resources inventory data

The United States Soil Conservation Service (SCS) conducts a survey for the purpose of establishing an agricultural land use database. This survey is called the National Resources Inventory (NRI) database. The complex NRI land classification system, in conjunction with the quantitative information gathered by the survey, has numerous applications. The current paper uses the wetland area data gathered by the NRI in 1982 and 1987 to examine empirically the factors that generate wetland loss in the United States. The cross-section regression models listed here use the quantity of wetlands, the stock of drainage capital, the realty value of farmland and drainage costs to explain most of the cross-state variation in wetland loss rates. Wetlands preservation efforts by federal agencies assume that pecuniary economic factors play a decisive role in wetland drainage. The empirical models tested in the present paper validate this assumption.

Journal of Environmental Management↗
USGS2011

Topographic mapping data semantics through data conversion and enhancement

This paper presents research on the semantics of topographic data for triples and ontologies to blend the capabilities of the Semantic Web and The National Map of the U.S. Geological Survey. Automated conversion of relational topographic data of several geographic sample areas to the triple data model standard resulted in relatively poor semantic associations. Further research employed vocabularies of feature type and spatial relation terms. A user interface was designed to model the capture of non-standard terms relevant to public users and to map those terms to existing data models of The National Map through the use of ontology. Server access for the study area triple stores was made publicly available, illustrating how the development of linked data may transform institutional policies to open government data resources to the public. This paper presents these data conversion and research techniques that were tested as open linked data concepts leveraged through a user-centered interface and open USGS server access to the public.

Book chapter↗
USGS1989

On inter-tidal transport equation

The transports of solutes, sediments, nutrients, and other tracers are fundamental to the interactive physical, chemical, and biological processes in estuaries. The characteristic time scales for most estuarine biological and chemical processes are on the order of several tidal cycles or longer. To address the long-term transport mechanism meaningfully, the formulation of an inter-tidal conservation equation is the main subject of this paper. The commonly used inter-tidal conservation equation takes the form of a convection-dispersion equation in which the convection is represented by the Eulerian residual current, and the dispersion terms are due to the introduction of a Fickian hypothesis, unfortunately, the physical significance of this equation is not clear, and the introduction of a Fickian hypothesis is at best an ad hoc approximation. Some recent research results on the Lagrangian residual current suggest that the long-term transport problem is more closely related to the Lagrangian residual current than to the Eulerian residual current. With the aid of additional insight of residual current, the inter-tidal transport equation has been reformulated in this paper using a small perturbation method for a weakly nonlinear tidal system. When tidal flows can be represented by an M 2 system, the new intertidal transport equation also takes the form of a convective-dispersion equation without the introduction of a Fickian hypothesis. The convective velocity turns out to be the first order Lagrangian residual current (the sum of the Eulerian residual current and the Stokes’ drift), and the correlation terms take the form of convection with the Stokes’ drift as the convective velocity. The remaining dispersion terms are perturbations of lower order solution to higher order solutions due to shear effect and turbulent mixing.

Book chapter↗
USGS2021

Introduction to limnogeology: Progress, challenges, and opportunities: A tribute to Elizabeth Gierlowski-Kordesch

Elizabeth Gierlowski-Kordesch (1956–2016) was a leader and innovator in the specialty field of limnogeology since its beginnings in the late 1980s. Her excitement for field work and examining sediments was contagious, and she was always testing new research ideas. Beth would have been thrilled with the diversity of papers presented in the volume and the wide array of techniques used to determine the history, geochemistry, paleontology, and paleoclimate preserved in the sediments in basins that are located on every continent except Australia and Antarctica. She would also have been delighted that half the chapters were first authored by highly cited women scientists. Beth spent her career teaching, mentoring, conducting research with students and colleagues, and planning limnogeology conferences, books, and field trips. Her contributions span deep-time lakes from North and South America, Africa, Asia, and Europe, starting with her work on the Lower Jurassic East Berlin Formation where she conducted her Ph.D. research. Her work with Kerry Kelts at the University of Minnesota produced two books summarizing global lake research. These volumes are still used by many researchers, particularly as a starting point in their limnogeological studies. Her collaboration with Springer Nature® resulted in the series entitled Syntheses in Limnogeology , a publication that likely would not exist without her enthusiasm and perseverance. The papers in this second volume in the series describe a variety of Jurassic to modern lakes that range from fresh to hypersaline, shallow to deep, vary in size from <1 km 2 to 100s of km 2 , and are found in a number of tectonic settings. Various proxies, including microfossils and trace fossils and analyses of lacustrine sedimentology, stratigraphy, and stable isotopes are used to evaluate the sediment cores and stratigraphic sections to evaluate human and climate influences on the environment, the effects of tectonic, seismic, and volcanic activity, and variations in hydrology. The contributions in this volume reflect the diverse research that Beth conducted herself and we hope is a fitting honor to one of the founding scientists of Limnogeology.

Book chapter↗
USGS2010

Real-time seismic monitoring of structures: Data handling and case studies

Within the last decade, advances in the acquisition, processing and transmission of data from real-time seismic monitoring systems has contributed to the growth in the number structures instrumented with such systems. An equally important factor for such growth can be attributed to the demands by stakeholders to find rapid answers to important questions related to the functionality (or “state of health”) of structures during and immediately following a seismic event. Hence, rapid and accurate assessment of the damage condition or performance of a building or a lifeline structure is of paramount importance to stakeholders, including owners, leasers, permanent and/or temporary occupants, users of infrastructures, city officials and rescue teams that are concerned with safety of those in the building, and those that may be affected in nearby buildings and infrastructures. In earlier papers, we described how observed data from sensors deployed in structures can be configured to establish seismic health monitoring of structures. In these configurations, drift ratios are the main parametric indicator of damage condition of a building. The process described for buildings can be applied directly for bridges as well. For bridges, the term, “drift ratio” is not generally used; however, relative displacements of critical elements of a bridge can be construed as such. While real-time data from structural arrays indicate that these methods are reliable and provide requisite information for owners and other parties to make informed decisions and to choose among pre-defined actions following significant events, there are several issues related to data ownership, transmission and archiving. This paper examines the real-time seismic monitoring systems deployed mainly in the United States, with particular attention to data issues – handling, dissemination, storage, and archiving. In most cases, due to the numerous channels involved, the deployments in each one of the real-time structures can be considered to be an individual array. Two detailed cases are described that demonstrate the variability in data ownership and dissemination.

Book chapter↗
USGS2014

210Pb dating

Roughly fifty years ago, a small group of scientists from Belgium and the United States, trying to better constrain ice sheet accumulation rates, attempted to apply what was then know about environmental lead as a potential geochronometer. Thus Goldberg (1963) developed the first principles of the 210 Pb dating method, which was soon followed by a paper by Crozaz et al. (1964), who examined accumulation history of Antarctic snow using 210 Pb. Shortly thereafter, Koide et al. (1972, 1973) adapted this technique to unravel sediment deposition and accumulation records in deep-sea environments. Serendipitously, they chose to work in a deep basin off California, where an independent and robust age model had already been developed. Krishanswami et al. (1971) extended the use of this technique to lacustrine deposits to reconstruct depositional histories of lake sediment, and maybe more importantly, contaminant inputs and burial. Thus, the powerful tool for dating recent (up to about one century old) sediment deposits was established and soon widely adopted. Today almost all oceanographic or limnologic studies that address recent depositional reconstructions employ 210 Pb as one of several possible geochronometers (Andrews et al., 2009; Gale, 2009; Baskaran, 2011; Persson and Helms, 2011). This paper presents a short overview of the principles of 210 Pb dating and provides a few examples that illustrate the utility of this tracer in contrasting depositional systems. Potential caveats and uncertainties (Appleby et al., 1986; Binford, 1990; Binford et al., 1993; Smith, 2001; Hancock et al., 2002) inherent to the use and interpretation of 210 Pb-derived age-models are also introduced. Recommendations as to best practices for most reliable uses and reporting are presented in the summary.

Book chapter↗
USGS2003

Managing a subsidized predator population: Reducing common raven predation on desert tortoises

Human communities often are an inadvertent source of food, water, and other resources to native species of wildlife. Because these resources are more stable and predictable than those in a natural environment, animals that subsist on them are able to increase in numbers and expand their range, much to the detriment of their competitors and species they prey upon. In the Mojave Desert, common ravens (Corvus corax) have benefited from human-provided resources to increase in population size precipitously in recent years. This trend has caused concern because ravens prey on juvenile desert tortoises (Gopherus agassizii), a federally threatened species. In this paper, I discuss management strategies to reduce raven predation on desert tortoises. The recommendations fall into three categories: (1) managing raven populations by reducing access to anthropogenic resources; (2) removing offending ravens or other birds in specially targeted tortoise management zones; and (3) continuing research on raven ecology, raven behavior, and methods of reducing raven predation on tortoises. I also recommend approaching the problem within an adaptive management framework: management efforts should first be employed as scientific experiments - with replicates and controls - to yield an unbiased assessment of their effectiveness. Furthermore, these strategies should be implemented in concert with actions that reduce other causes of desert tortoise mortality to aid the long-term recovery of their populations. Overall, the approaches outlined in this paper are widely applicable to the management of subsidized predators, particularly where they present a threat to a declining species of prey.

Environmental Management↗
USGS2024

A framework for estimating economic impacts of ecological restoration

Ecological restoration projects are designed to improve natural and cultural resources. Spending on restoration also stimulates economic impacts to the restoration economy through the creation or support of jobs and business activity. This paper presents accessible methods for quantifying the economic impacts supported by restoration spending and is written to be a guide and toolbox for an interdisciplinary audience of restoration practitioners and economists. Measuring the economic impacts of restoration can be challenging due to lacking or limited data. The complex, collaborative, and heterogeneous nature of restoration projects can make it difficult to clearly track costs, contributing to limited availability and inconsistency in restoration cost data. And business classification systems, such as the North American Industrial Classification System (NAICS), do not include restoration-sectors that consistently describe the patterns of restoration spending. The aims of this paper are to (1) provide restoration practitioners and program managers with a clear understanding of the application of economic impact analyses to restoration, (2) provide a framework for collecting project cost data for economic impact analyses, and (3) provide modeling best practices and an example application of the framework.

Environmental Management↗
USGS2000

Chemical characteristics of urban stormwater sediments and implications for environmental management, Maricopa County, Arizona

Investigations of the chemical characteristics of urban stormwater sediments in the rapidly growing Phoenix metropolitan area of Maricopa County, Arizona, showed that the inorganic component of these sediments generally reflects geologic background values. Some concentrations of metals were above background values, especially cadmium, copper, lead, and zinc, indicating an anthropogenic contribution of these elements to the sediment chemistry. Concentrations, however, were not at levels that would require soil remediation according to guidelines of the U.S. Environmental Protection Agency. Arsenic concentrations generally were above recommended values for remediation at a few sites, but these concentrations seem to reflect geologic rather than anthropogenic factors. Several organochlorine compounds no longer in use were ubiquitous in the Phoenix area, although concentrations generally were low. Chlordane, DDT and its decay products DDE and DDD, dieldrin, toxaphene, and PCBs were found at almost all sites sampled, although some of the pesticides in which these compounds are found have been banned for almost 30 years. A few sites showed exceptionally high concentrations of organochlorine compounds. On the basis of published guidelines, urban stormwater sediments do not appear to constitute a major regional environmental problem with respect to the chemical characteristics investigated here. At individual sites, high concentrations of organic compounds - chlordane, dieldrin, PCBs, and toxaphene - may require some attention. The possible environmental hazard presented by low-level organochlorine contamination is not addressed in this paper; however, high levels of toxicity in urban sediments are difficult to explain. Sediment toxicity varied significantly with time, which indicates that these tests should be evaluated carefully before they are used for management decisions.Investigations of the chemical characteristics of urban stormwater sediments in the rapidly growing Phoenix metropolitan area of Maricopa County, Arizona, showed that the inorganic component of these sediments generally reflects geologic background values. Some concentrations of metals were above background values, especially cadmium, copper, lead, and zinc, indicating an anthropogenic contribution of these elements to the sediment chemistry. Concentrations, however, were not at levels that would require soil remediation according to guidelines of the U.S. Environmental Protection Agency. Arsenic concentrations generally were above recommended values for remediation at a few sites, but these concentrations seem to reflect geologic rather than anthropogenic factors. Several organochlorine compounds no longer in use were ubiquitous in the Phoenix area, although concentrations generally were low. Chlordane, DDT and its decay products DDE and DDD, dieldrin, toxaphene, and PCBs were found at almost all sites sampled, although some of the pesticides in which these compounds are found have been banned for almost 30 years. A few sites showed exceptionally high concentrations of organochlorine compounds. On the basis of published guidelines, urban stormwater sediments do not appear to constitute a major regional environmental problem with respect to the chemical characteristics investigated here. At individual sites, high concentrations of organic compounds - chlordane, dieldrin, PCBs, and toxaphene - may require some attention. The possible environmental hazard presented by low-level organochlorine contamination is not addressed in this paper; however, high levels of toxicity in urban sediments are difficult to explain. Sediment toxicity varied significantly with time, which indicates that these tests should be evaluated carefully before they are used for management decisions.

Environmental Management↗
USGS2010

Geomorphology of mesophotic coral ecosystems: Current perspectives on morphology, distribution, and mapping strategies

This paper presents a general review of the distribution of mesophotic coral ecosystems (MCEs) in relationship to geomorphology in US waters. It was specifically concerned with the depth range of 30–100 m, where more than 186,000 km2 of potential seafloor area was identified within the US Gulf of Mexico/Florida, Caribbean, and main Hawaiian Islands. The geomorphology of MCEs was largely inherited from a variety of pre-existing structures of highly diverse origins, which, in combination with environmental stress and physical controls, restrict the distribution of MCEs. Sea-level history, along with depositional and erosional processes, played an integral role in formation of MCE settings. However, mapping the distribution of both potential MCE topography/substrate and existing MCE habitat is only beginning. Mapping techniques pertinent to understanding morphology and MCE distributions are discussed throughout this paper. Future investigations need to consider more cost-effective and remote methods (such as autonomous underwater vehicles (AUVs) and acoustics) in order to assess the distribution and extent of MCE habitat. Some understanding of the history of known MCEs through coring studies would help understand their initiation and response to environmental change over time, essential for assessing how they may be impacted by future environmental change.

Alabama, Florida, Georgia, Hawai'i, Louisiana, Mis↗
USGS2014

Volcanic history of El Chichon Volcano (Chiapas, Mexico) during the Holocene, and its impact on human activity

Before its devastating eruption in 1982, El Chichon Volcano was little known and did not appear on any listings of hazardous volcanoes. Subsequent geologic studies, based on stratigraphic and radiocarbon investigations, showed that at least three explosive eruptions had occurred previously at this volcano. In this paper, we present the result of recent studies on the stratigraphy of the volcano and new radiocarbon ages which show that at least 11 eruptions have taken place at El Chichon in the past 8000 years. Explosive events, most of them producing block-and-ash flow and surge deposits, occurred around 550, 900, 1250, 1500, 1600, 1900, 2000, 2500, 3100, 3700 and 7700 years BP. The juvenile products of these eruptions have a trachyandesitic composition with similar degree of evolution, as evidenced from their SiO2 abundance and depletion in MgO, CaO, TiO2, as well as trace and rare earth elements. This suggests segregation of olivine and orthopyroxene from the melt. Since human settlements in southeast Mexico and Central America can be traced as far back as approximately 2500 years BP, most of these events probably affected human activity. In fact, there are reports of pottery shards and other artifacts in deposits from the eruption of 1250 BP. Pottery fragments in deposits of an eruption that took place 2500 BP are also reported in this paper. Thus, the impact of the volcano on human activities has been frequent, with most of the repose intervals lasting between 100 to 600 years. The impact of the eruptions was probably of greater than local extent, because airfall tephra could reach distant sites and possibly even affect weather. The eruptive history of El Chichon also offers clues in the investigation of the Maya civilization. Several researchers have considered the volcano as an important factor in the answer to some intriguing questions such as the extensive use of volcanic ash in Late Classic Maya ceramics or, of greater importance, the causes of the collapse of the Classic Maya civilization.

Bulletin of Volcanology↗
USGS2014

Pyroclast/snow interactions and thermally driven slurry formation. Part 1: Theory for monodisperse grain beds

Lahars are often produced as pyroclastic flows move over snow. This phenomenon involves a complicated interplay of mechanical and thermal processes that need to be separated to get at the fundamental physics. The thermal physics of pyroclast/snow interactions form the focus of this paper. A theoretical model is developed of heat- and mass transfer at the interface between a layer of uniformly sized pyroclasts and an underlying bed of snow, for the case in which there is no relative shear motion between pyroclasts and snow. A microscale view of the interface is required to properly specify boundary conditions. The physical model leads to the prediction that the upward flux of water vapor - which depends upon emplacement temperature, pyroclast grain size, pyroclast-layer thickness, and snow permeability - is sometimes sufficient to fluidize the pyroclasts. Uniform fluidization is usually unstable to bubble formation, which leads to vigorous convection of the pyroclasts themselves. Thus, predicted threshold conditions for fluidization are tantamount to predicted thresholds for particle convection. Such predictions are quantitatively in good agreement with results of experiments described in part 2 of this paper. Because particle convection commonly causes scour of the snow bed and transformation of the pyroclast layer to a slurry, there exists a 'thermal scour' process for generating lahars from pyroclastic flows moving over snow regardless of the possible role of mechanical scour.

Bulletin of Volcanology↗
USGS2015

Differences in ecosystem carbon distribution and nutrient cycling linked to forest tree species composition in a mid-successional boreal forest

In the boreal forest of Alaska, increased fire severity associated with climate change is expanding deciduous forest cover in areas previously dominated by black spruce ( Picea mariana ). Needle-leaf conifer and broad-leaf deciduous species are commonly associated with differences in tree growth, carbon (C) and nutrient cycling, and C accumulation in soils. Although this suggests that changes in tree species composition in Alaska could impact C and nutrient pools and fluxes, few studies have measured these linkages. We quantified C, nitrogen, phosphorus, and base cation pools and fluxes in three stands of black spruce and Alaska paper birch ( Betula neoalaskana ) that established following a single fire event in 1958. Paper birch consistently displayed characteristics of more rapid C and nutrient cycling, including greater aboveground net primary productivity, higher live foliage and litter nutrient concentrations, and larger ammonium and nitrate pools in the soil organic layer (SOL). Ecosystem C stocks (aboveground + SOL + 0–10 cm mineral soil) were similar for the two species; however, in black spruce, 78% of measured C was found in soil pools, primarily in the SOL, whereas aboveground biomass dominated ecosystem C pools in birch forest. Radiocarbon analysis indicated that approximately one-quarter of the black spruce SOL C accumulated prior to the 1958 fire, whereas no pre-fire C was observed in birch soils. Our findings suggest that tree species exert a strong influence over C and nutrient cycling in boreal forest and forest compositional shifts may have long-term implications for ecosystem C and nutrient dynamics.

Ecosystems↗
USGS2003

Hydrogeology Journal in 2002

Hydrogeology Journal appeared in six issues containing a total of 674 pages and 47 major articles, including 22 Papers and 24 Reports, as well as Technical Notes and Book Reviews. The final issue of 2002 also contained the annual volume index. Hydrogeology Journal (HJ) is an international forum for hydrogeology and related disciplines. Authors in 2002 were from about 30 countries. Articles advanced hydrogeologic science and described hydrogeologic systems in many regions worldwide. These articles focused on 22 countries: Afghanistan, Argentina, Australia, Austria, Belgium, Brazil, Canada, China, India, Israel, Japan, Jordan, Mexico, New Zealand, Nigeria, Portugal, Qatar, Switzerland, Syria, Turkey, UK, and the USA. The Guest Editors of the 2002 HJ theme issue on "Groundwater Recharge", Bridget R. Scanlon and Peter G. Cook, assembled a highly relevant and sought-after collection of papers from eminent authors on wide-ranging aspects of the subject.

Hydrogeology Journal↗
USGS2004

Editors' message: Hydrogeology Journal in 2003

Hydrogeology Journal appeared in six issues containing a total of 710 pages and 48 major articles, including 31 Papers and 14 Reports, as well as some Technical Notes and Book Reviews. The number of submitted manuscripts continues to increase. The final issue of 2003 also contained the annual volume index. Hydrogeology Journal ( HJ ) is an international forum for hydrogeology and related disciplines and authors in 2003 were from about 28 countries. Articles advanced hydrogeologic science and described hydrogeologic systems in many regions worldwide. These articles focused on a variety of general topics and on studies of hydrogeology in 24 countries: Afghanistan, Algeria, Argentina, Australia, Bangladesh, Belgium, Canada, Chile, China, Denmark, France, India, Italy, Mexico, Netherlands, New Zealand, Nigeria, Norway, Portugal, Russia, South Africa, Switzerland, Turkey, and U.S.A. The Guest Editor of the 2003 HJ theme issue on “Hydromechanics in Geology and Geotechnics”, Ove Stephansson, assembled a valuable collection of technical reviews and research papers from eminent authors on important aspects of the subject area.

Hydrogeology Journal↗
USGS2019

Envisioning a national invasive species information framework

With a view toward creating a national Early Detection and Rapid Response Program (EDRR) program, the United States National Invasive Species Council Management Plan for 2016–2018 calls for a series of assessments of federal EDRR capacities, including the evaluation of “relevant federal information systems to provide the data and other information necessary for risk analyses/horizon scanning, rapid specimen identification, and rapid response planning.” This paper is a response to that directive. We provide an overview of information management needs for enacting EDRR and discuss challenges to meeting these needs. We then review the history of relevant US policy directives for advancing invasive species information systems and provide an overview of federal invasive species information system capacities, including current gaps and inconsistencies. We conclude with a summary of key principles and needs for establishing a national invasive species information framework. Our findings are consistent with earlier studies and, thus, emphasize the need to act on long-recognized needs. As a supplement to this paper, we have cataloged federal invasive species databases and information tools identified through this work.

Biological Invasions↗
USGS2007

Representing general theoretical concepts in structural equation models: The role of composite variables

Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically-based probabilistic models. In this paper we discuss the interface between theory and data in SEM and the use of an additional variable type, the composite. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling heterogeneous concepts of the sort commonly of interest to ecologists. While long recognized as a potentially important element of SEM, composite variables have received very limited use, in part because of a lack of theoretical consideration, but also because of difficulties that arise in parameter estimation when using conventional solution procedures. In this paper we present a framework for discussing composites and demonstrate how the use of partially-reduced-form models can help to overcome some of the parameter estimation and evaluation problems associated with models containing composites. Diagnostic procedures for evaluating the most appropriate and effective use of composites are illustrated with an example from the ecological literature. It is argued that an ability to incorporate composite variables into structural equation models may be particularly valuable in the study of natural systems, where concepts are frequently multifaceted and the influence of suites of variables are often of interest. ?? Springer Science+Business Media, LLC 2007.

Environmental and Ecological Statistics↗