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At least 991 records · Page 55Linked to original sources
USGS1997

The Areal Extent of Continuous Type Gas Accumulations in Lower Silurian Clinton Sands and Medina Group Sandstones of the Appalachian Basin and the Environments Affected by Their Development

In order to best preserve and manage our energy and natural resources we must understand the relationships between these resources and the impacts of their development. To further this understanding the U.S. Geological Survey is studying unconventional continuous-type and, to a lesser extent, conventional oil and gas accumulations and the environmental impacts associated with their development. Continuous-type gas accumulations are generally characterized by low matrix permeabilities, large areal extents, and no distinct water contacts. This basin scale map shows the overall extent of these accumulations and the general land use types that may be impacted by their development. The Appalachian Basin has the longest history of oil and gas exploration and production in the United States. Since Drake's Titusville discovery well was drilled in 1859, oil and gas has been continuously produced in the basin. While there is still a great deal of oil and gas production, new field discoveries are rare and relatively small. For most of the second half of the 20th century the Appalachian basin has been considered a mature petroleum province because most of the large plays have already been discovered and developed. One exception to this trend is the Lower Silurian Clinton Sands and Medina Group Gas play which is being developed in New York, Pennsylvania, and Ohio. This continuous-type gas play has been expanding since the early 1970's (see inset maps). In the 1980's economic incentives such as large increases in wellhead prices further stimulated continuous-type gas resource development. Continuous-type gas plays can be large in areal extent and in thickness. 'Sweetspots' (areas of greater prodcution) are hard to predict and generally associated with better than average permeabilities, and enhanced by natural fracture systems. With an overall success rate often approaching 90%, drilling most of the play with closely spaced wells is often the best way to maximize gas recovery. Some positive economic characteristics associated with the development of these continuous-type accumulations are high success rates, low drilling and development costs, and low water production, which results in low water disposal costs. Large areas within the Appalachian basin with good potential for this type of gas accumulation remain to be tested. Positive environmental characteristics include, a clean energy source, low water production, and relatively low surface impact. Some negative characteristics associated with these continuous -type accumulations are low individual well production rates and small well drainage area. Negative environmental characteristics are primarily related to the dense well spacing used to develop the resource to its full potential. Often negative environmental impacts such as surface disturbance can be greatly reduced. The number of well sites can be decreased by using a single centrally located surface location and associated facilities for several directionally or horizonatally drilled wells. This also minimizes the transportation infrastructure (access roads and pipelines) required to maintain the wells and deliver the gas. Visual impacts can be reduced by selecting well locations visible only over short distances. While the prospective area is large, potential decreases basin- ward and toward the northeast and southwest. These areas are represented by the lower potential plays 6727, 6730, and 6731. The U.S. Geological Survey landuse and landcover data was derived from USGS 1:250,000 and 1:100,000 scale maps. This information was collected between the mid 1970s to mid 1980s. The land use and land cover data was mapped and coded using the Anderson classification system (Anderson, 1975) which is a hierarchical system of general (level 1) to more specific (level 2) characterization. Level 1 characterization was used for this map; the land use and land cover designations are displayed below in the Explanation. T

Open-File Report↗
USGS2016

Theory and application of semiochemicals in nuisance fish control

Controlling unwanted, or nuisance, fishes is becoming an increasingly urgent issue with few obvious solutions. Because fish rely heavily on semiochemicals, or chemical compounds that convey information between and within species, to mediate aspects of their life histories, these compounds are increasingly being considered as an option to help control wild fish. Possible uses of semiochemicals include measuring their presence in water to estimate population size, adding them to traps to count or remove specific species of fish, adding them to waterways to manipulate large-scale movement patterns, and saturating the environment with synthesized semiochemicals to disrupt responses to the natural cue. These applications may be especially appropriate for pheromones, chemical signals that pass between members of same species and which also have extreme specificity and potency. Alarm cues, compounds released by injured fish, and cues released by potential predators also could function as repellents and be especially useful if paired with pheromonal attractants in “push-pull” configurations. Approximately half a dozen attractive pheromones now have been partially identified in fish, and those for the sea lamprey and the common carp have been tested in the field with modest success. Alarm and predator cues for sea lamprey also have been tested in the laboratory and field with some success. Success has been hampered by our incomplete understanding of chemical identity, a lack of synthesized compounds, the fact that laboratory bioassays do not always reflect natural environments, and the relative difficulty of conducting trials on wild fishes because of short field seasons and regulatory requirements. Nevertheless, workers continue efforts to identify pheromones because of the great potential elucidated by insect control and the fact that few tools are available to control nuisance fish. Approaches developed for nuisance fish also could be applied to valued fishes, which suffer from a lack of powerful management tools.

Journal of Chemical Ecology↗
USGS2007

Surficial sediment character of the New York-New Jersey offshore continental shelf region: A GIS compilation

Broad continental shelf regions such as the New York Bight are the product of a complex geologic history and dynamic oceanographic processes, dominated by the Holocene marine transgression (>100 m sea-level rise) following the end of the last Pleistocene ice advance ~ 20,000 years ago. The area of the U.S. Exclusive Economic Zone (U.S. EEZ) territory, extending 200 nautical miles seaward from the coast, is larger than the continental U.S. and contains submerged landforms that provide a variety of natural functions and societal benefits, such as: critical habitats for fisheries, ship navigation and homeland security, and engineering activities (i.e. oil and gas platforms, pipeline and cable routes, potential wind-energy-generation sites). Some parts of the continental margins, particularly inner-continental shelf regions, also contain unconsolidated hard-mineral deposits such as sand and gravel that are regarded as potential aggregate resources to meet or augment needs not met by onshore deposits (Williams, 1992). The present distribution of surficial sediment off the northeastern United States is shaped from the deposits left by the last glaciation and reflects the cumulative effects of sediment erosion, transport, sorting, and deposition by storm and tidal processes during the Holocene rise in sea level. As a result, the sediments on the sea floor represent both an historical record of former conditions and a guide to possible future sedimentary environments. The U.S. Geological Survey (USGS) through the Coastal and Marine Geology Program, in cooperation with the University of Colorado and other partners, has compiled extant sediment character and textural data as well as other geologic information on the sea floor from all regions around the U.S. into the usSEABED data system (Reid and others, 2005; Buczkowski and others, 2006; Reid and others, 2006). The usSEABED system, which contains information on sediment grain size and lithology for more than 340,500 stations within the U.S. EEZ. has been developed and populated with data as part of the USGS Marine Aggregate Resources and Processes and the National Benthic Habitats projects in order to provide the base-line data needed to update the current maps of offshore surficial geologic character and sediment distribution. The maps are also used to characterize benthic sea floor environments important for marine ecosystems. U.S. Geological Survey, Data Series 118 (Reid and others, 2005), of the usSEABED data release series, represents the combined efforts of the USGS and several other government agencies to provide a unified resource for accessing and preserving records of U.S. east coast sea floor geologic information and sediment texture data. For this present report, we have chosen to focus on the New York-New Jersey region, an area that has been intensely studied by the USGS for many years to address many complex issues. This report illustrates the uses of the usSEABED database for GIS applications, while offering additional insight into the resources and data available from the USGS and its collaborative institutions. This report is based on data contained in U.S. Geological Survey Data Series 118 (Reid and others, 2005) and shows an assortment of example GIS products that are possible using usSEABED. All data are intended to be GIS-ready and should not require any additional cleanup, formatting, or renaming of fields in order to use the data in a Geographic Information System. This project employs the Environmental Systems Research Institute's (ESRI) ArcView™ software. Many of these maps were made as part of the ongoing USGS study to assess marine aggregate resources offshore New York and New Jersey, but these maps can serve many other purposes. The marine science community, educators, students and others are encouraged to use these data to generate GIS products for their own purposes. The objectives of the Marine Aggregate Resources and Processes project are to produce a series of new geologic maps and reports of the sea floor that will provide scientific insights into the character and geologic development of U.S. continental margins and to use these maps and information to assess the potential availability of offshore sand and gravel resources. The mapping and aggregate resource assessments are being conducted on a national scale using the usSEABED data base as described in Williams and others (2003). Potential uses for these data include: (1) defining the geological variability of the sea floor in relation to benthic habitat diversity; (2) improving our understanding of the processes that control the distribution and transport of bottom sediments and benthic habitats; (3) locating aggregate resources for beach nourishment and industrial applications; and (4) providing a detailed geospatial framework for future marine science research, monitoring, and management activities. The initial assessments are in progress for the New York Bight and Louisiana offshore areas.

New Jersey, New York↗
USGS2001

Mars exploration

An international flotilla of spacecraft are to be sent to Mars over the next decade in an effort to understand the planet's geology and climate history, and to determine whether some form of life ever started there. At least two spacecraft will be sent at each launch opportunity, and at times up to four spacecraft may be operating simultaneously at the planet.

Nature↗
USGS2006

Ammonium transport and reaction in contaminated groundwater: Application of isotope tracers and isotope fractionation studies

Ammonium (NH 4 + ) is a major constituent of many contaminated groundwaters, but its movement through aquifers is complex and poorly documented. In this study, processes affecting NH 4 + movement in a treated wastewater plume were studied by a combination of techniques including large‐scale monitoring of NH 4 + distribution; isotopic analyses of coexisting aqueous NH 4 + , NO 3 − , N 2 , and sorbed NH 4 + ; and in situ natural gradient 15 NH 4 + tracer tests with numerical simulations of 15 NH 4 + , 15 NO 3 − , and 15 N 2 breakthrough data. Combined results indicate that the main mass of NH 4 + was moving downgradient at a rate about 0.25 times the groundwater velocity. Retardation factors and groundwater ages indicate that much of the NH 4 + in the plume was recharged early in the history of the wastewater disposal. NO 3 − and excess N 2 gas, which were related to each other by denitrification near the plume source, were moving downgradient more rapidly and were largely unrelated to coexisting NH 4 + . The δ 15 N data indicate areas of the plume affected by nitrification (substantial isotope fractionation) and sorption (no isotope fractionation). There was no conclusive evidence for NH 4 + ‐consuming reactions (nitrification or anammox) in the anoxic core of the plume. Nitrification occurred along the upper boundary of the plume but was limited by a low rate of transverse dispersive mixing of wastewater NH 4 + and O 2 from overlying uncontaminated groundwater. Without induced vertical mixing or displacement of plume water with oxic groundwater from upgradient sources, the main mass of NH 4 + could reach a discharge area without substantial reaction long after the more mobile wastewater constituents are gone. Multiple approaches including in situ isotopic tracers and fractionation studies provided critical information about processes affecting NH 4 + movement and N speciation.

Water Resources Research↗
USGS2019

Snake River fall chinook salmon life history investigations, 2018 annual report

The following report is divided into three sections each of which describes work conducted by different project cooperators. Chapter One describes smallmouth bass (Micropterus dolomieu) predation on subyearling fall Chinook salmon (Oncorhynchus tshawytscha) in Lower Granite Reservoir in 2018. Smallmouth bass abundance increased seasonally in shoreline habitats and was highest in the lower reach of the reservoir (1,239 fish/km of shoreline). Abundance ranged from 40,743 to 81,595 in 2018. We examined the relationship between smallmouth bass predation and subyearling habitat suitability. Bass abundance was highest in “natural” habitat (i.e., habitat with natural substrate that was not deemed suitable for subyearlings) and fish were generally larger in habitat classified as “suitable” (i.e., habitat deemed suitable rearing) for subyearling Chinook salmon. Subyearlings were present in all habitat types sampled but their abundance was 2–3 times lower in the lower reach of the reservoir. Sand rollers (Percopsis transmontana)—a common prey of smallmouth bass—were present in greatest numbers in “suitable” habitat in the upper reach and “natural” habitat in the middle reservoir reach, but few were observed in the lower reservoir. The total loss of subyearlings to smallmouth bass predation in 2018 (120,023) was slightly less than one-half that of 2016 (266,988) and more than twice that of 2017 (47,830). Total sand roller loss in 2018 (149,106) was slightly more than one-half the losses estimated in 2016 and 2017. Chapter Two describes the feasibility of using stable isotopes of carbon and nitrogen to distinguish hatchery and natural origin subyearling fall Chinook salmon that were consumed by smallmouth bass. A discriminant function was fit from isotopic signatures and fork length from known-origin hatchery and natural subyearlings. The function had an overall correct classification rate of 97.2%. Of subyearlings consumed by smallmouth bass the function correctly classified 94.3% of hatchery fish but only 64.3% of natural fish based on fish origins that were validated with parentage-based tagging (PBT) analysis. Most of the fish consumed by smallmouth bass were of hatchery origin and most of those were of the spring/summer run early in the year and of the fall run later in the year. Based on analysis of known-origin hatchery fish collected at Lower Granite Dam through time following release, using stable isotopes as a discriminatory tool is probably only effective for about two weeks following release, but may have greater utility in unimpounded systems where fish emigrate seaward more quickly. The third section of this report is a Master’s Thesis that covers work conducted under contracts 46273 REL 14 and 79562. The first chapter of the thesis examined growth of subyearling fall Chinook salmon rearing in three sections of the Snake and Clearwater rivers and Lower Granite Reservoir. Growth and food consumption were highest in the reservoir section than in riverine sections, though growth was not significantly higher in the reservoir for the full duration of the study. Julian date was the strongest predictor of growth and consumption, and both growth and consumption decreased over the course of the study, even when accounting for allometric growth effects. Findings suggest that fish rearing in the reservoir section during their early growth period may have an ephemeral energetic advantage relative to fish rearing in natal river sections. The second chapter of the thesis examined the spatial variation in natal river rearing and downstream movement in Snake River fall Chinook salmon. Based on otolith analyses, natal origin was related to differential habitat use with fish from the Clearwater River accruing 48% of their freshwater growth in their natal river compared to 40% for Snake River fish. These differences were associated with different mean size at natal river exit and at ocean entry.

Idaho, Washington, Oregon↗
USGS2004

Stable Isotope Analysis of Water and Aqueous Solutions by Conventional Dual-Inlet Mass Spectrometry

This chapter reviews the recent developments and refinements of analytical methods for preparing waters and other aqueous samples of different origins for the measurement of the oxygen and hydrogen isotopes by conventional dual-inlet, dynamic gas-source isotope-ratio mass spectrometry. The emerging techniques of continuous-flow mass-spectrometry are discussed as they are employed in both dual-inlet and continuous-flow mass-spectrometry. The size, chemical composition, and isotopic abundance of aqueous samples vary widely depending on their type, origin, and history. Automated gas equilibration methods are very suitable and are becoming standard techniques in many isotope hydrology laboratories. The increased analytical precisions are due to the subsequent development of modern gas-source isotope-ratio mass spectrometers with dual-inlets and multi-collectors, have caused the proliferation of new analytical methods and applications for the oxygen and hydrogen isotopic compositions of water. For natural hydrologic samples and new developments of continuous-flow mass spectrometry, it is possible to determine both δD and δ 18 O values, as they can provide two-dimensional information. The most significant progress in analytical techniques for stable isotope analysis of water is witnessed. Hence, overall quality control of isotopic data is becoming an important issue.

Book chapter↗
USGS2014

Geologic assessment of undiscovered oil and gas resources in Aptian carbonates, onshore northern Gulf of Mexico Basin, United States

Carbonate lithofacies of the Lower Cretaceous Sligo Formation and James Limestone were regionally evaluated using established U.S. Geological Survey (USGS) assessment methodology for undiscovered conventional hydrocarbon resources. The assessed area is within the Upper Jurassic–Cretaceous–Tertiary Composite total petroleum system, which was defined for the assessment. Hydrocarbons reservoired in carbonate platform Sligo-James oil and gas accumulations are interpreted to originate primarily from the Jurassic Smackover Formation. Emplacement of hydrocarbons occurred via vertical migration along fault systems; long-range lateral migration also may have occurred in some locations. Primary reservoir facies include porous patch reefs developed over paleostructural salt highs, carbonate shoals, and stacked linear reefs at the carbonate shelf margin. Hydrocarbon traps dominantly are combination structural-stratigraphic. Sealing lithologies include micrite, calcareous shale, and argillaceous lime mudstone. A geologic model, supported by discovery history analysis of petroleum geology data, was used to define a single regional assessment unit (AU) for conventional reservoirs in carbonate facies of the Sligo Formation and James Limestone. The AU is formally entitled Sligo-James Carbonate Platform Oil and Gas (50490121). A fully risked mean undiscovered technically recoverable resource in the AU of 50 million barrels of oil (MMBO), 791 billion cubic feet of natural gas (BCFG), and 26 million barrels of natural gas liquids was estimated. Substantial new development through horizontal drilling has occurred since the time of this assessment (2010), resulting in cumulative production of >200 BCFG and >1 MMBO.

Cretaceous Research↗
USGS2001

A model for lignin alteration - Part II: Numerical model of natural gas generation and application to the Piceance Basin, Western Colorado

The model presented here simulates a network of parallel and sequential reactions that describe the structural and chemical transformation of lignin-derived sedimentary organic matter (SOM) and the resulting generation of mobile species from shallow burial to approximately low-volatile bituminous rank. The model is calibrated to the Upper Cretaceous Williams Fork Formation coal of the Piceance Basin at the Multi-Well Experiment (MWX) Site, assuming this coal is largely derived from lignin. The model calculates the content of functional groups on the residual molecular species, C, H, and O elemental weight percents of the residual species, and moles of residual molecular species and mobile species (including components of natural gas) through time. The model is generally more sensitive to initial molecular structure of the lignin-derived molecule and the H2O content of the system than to initial temperature, as the former affect the fundamental reaction paths. The model is used to estimate that a total of 314 trillion cubic feet (tcf) of methane is generated by the Williams Fork coal over the basin history. ?? 2001 Elsevier Science Ltd. All rights reserved.

Organic Geochemistry↗
USGS1999

Isotopic identification of the source of methane in subsurface sediments of an area surrounded by waste disposal facilities

The major source of methane (CH4) in subsurface sediments on the property of a former hazardous waste treatment facility was determined using isotopic analyses measured on CH4 and associated groundwater. The site, located on an earthen pier built into a shallow wetland lake, has had a history of waste disposal practices and is surrounded by landfills and other waste management facilities. Concentrations of CH4 up to 70% were found in the headspace gases of several piezometers screened at 3 different depths (ranging from 8 to 17 m) in lacustrine and glacial till deposits. Possible sources of the CH4 included a nearby landfill, organic wastes from previous impoundments and microbial gas derived from natural organic matter in the sediments. Isotopic analyses included ??13C, ??D, 14C, and 3H on select CH4 samples and ??D and ??18O on groundwater samples. Methane from the deepest glacial till and intermediate lacustrine deposits had ??13C values from -79 to -82???, typical of natural 'drift gas' generated by microbial CO2-reduction. The CH4 from the shallow lacustrine deposits had ??13C values from -63 to -76???, interpreted as a mixture between CH4 generated by microbial fermentation and the CO2-reduction processes within the subsurface sediments. The ??D values of all the CH4 samples were quite negative ranging from -272 to -299???. Groundwater sampled from the deeper zones also showed quite negative ??D values that explained the light ??D observed for the CH4. Radiocarbon analyses of the CH4 showed decreasing 14C activity with depth, from a high of 58 pMC in the shallow sediments to 2 pMC in the deeper glacial till. The isotopic data indicated the majority of CH4 detected in the fill deposits of this site was microbial CH4 generated from naturally buried organic matter within the subsurface sediments. However, the isotopic data of CH4 from the shallow piezometers was more variable and the possibility of some mixing with oxidized landfill CH4 could not be completely ruled out.

Applied Geochemistry↗
USGS2006

The future of imaging spectroscopy - Prospective technologies and applications

Spectroscopy has existed for more than three centuries now. Nonetheless, significant scientific advances have been achieved. We discuss the history of spectroscopy in relation to emerging technologies and applications. Advanced focal plane arrays, optical design, and intelligent on-board logic are prime prospective technologies. Scalable approaches in pre-processing of imaging spectrometer data will receive additional focus. Finally, we focus on new applications monitoring transitional ecological zones, where human impact and disturbance have highest impact as well as in monitoring changes in our natural resources and environment We conclude that imaging spectroscopy enables mapping of biophysical and biochemical variables of the Earth's surface and atmospheric composition with unprecedented accuracy.

Conference Paper↗
USGS2004

The Pre-Messinian Total Petroleum System of the Provence Basin, Western Mediterranean Sea

The Provence Basin is in that portion of the western Mediterranean Sea that is deeper than 2 kilometers. The basin lies essentially beyond the outer continental shelf, between the countries of France, Italy, and Algeria, the Balearic Islands, and the islands of Sardinia and Corsica. It encompasses nearly 300,000 square kilometers and includes the Rhone River submarine fan on the continental slope of southern France. It is province 4068 in the World Energy study. A single, hypothetical, total petroleum system (TPS), the Pre-Messinian TPS (406801), was described for the Provence Basin. The designation hypothetical is used because there is no hydrocarbon production from the basin. The Provence Basin is a deep-water Tertiary rift basin in which the geothermal gradients vary regionally. The Red Sea Basin shares a similar geologic and thermal history with the rifted western Mediterranean Sea and was used as an analog to better understand the genesis of the Provence Basin and as a guide to estimating possible undiscovered amounts of hydrocarbons. For this assessment the basin was given a potential, at the mean, for undiscovered resources of 51 trillion cubic feet (1.4 trillion cubic meters) gas, 0.42 billion barrels oil, and 2.23 million barrels natural gas liquids.

Bulletin↗
USGS2020

Seafloor change around the Mississippi barrier islands, 1920 to 2016—The influence of storm effects on inlet and island morphodynamics

The Mississippi Barrier Islands in the northern Gulf of Mexico experienced high rates of spatial change over recorded history. Wave-induced sediment transport induced island migration, landward retreat, and inlet evolution. These processes can be measured using repeat bathymetric surveys to analyze elevation change over time. This study analyzes digital elevation models created from three time periods where bathymetric data have been collected: the 1920s, 2009, and 2016. The models are compared to assess volumetric change between surveys and characterize morphologic responses to natural and human-influenced processes. Although all the islands within the study area experienced a loss of area over the period of study, the nearshore and tidal inlets experience both accretion and erosion that vary spatially and temporally. Major morphologic changes include westward island migration, expanding ebb-tidal deltas, and changes in inlet dimensions. This study is a collaboration between the U.S. Geological Survey, the U.S. Army Corps of Engineers, and the National Park Service to establish baseline physical and pre-restoration morphologic conditions preceding a major restoration of the islands as part of the Mississippi Coastal Improvement Project.

Mississippi barrier islands↗
USGS1995

Geochemistry of sediments from coastal marshes of Louisiana

As a part of the U.S. Geological Survey Global Change and Climate History Program we have been studying the biogeochemistry of coastal marshes in Terrebonne Basin, Louisiana. Louisiana has about 40 percent of the coastal wetlands in the conterminous U.S. and it is losing wetlands at one of the highest rates in the U.S. with the conversion of about 65 km2/yr of marsh to open water (Britsch and Dunbar, 1993). The losses have been attributed to human and natural causes including saltwater intrusion through man-made canals, reduced sediment input, and regional subsidence. The net effect of these influences is to change the salinity of interior marshes in a fashion similar to a eustatic sea level rise. We are studying the cycling of carbon, sulfur, and other elements in sediments, waters, and marsh macrophytes in fresh, intermediate/brackish, and saltwater marshes in order to better understand how sea level rise, one aspect of global change, will influence and in turn be influenced by cycling of these elements. By characterizing the critical biogeochemical processes and the recent past environments in these rapidly changing marshes, we can improve predictions of future changes and interpretations of the historic geologic record in similar environments. In this report we describe our coastal marsh study sites in Louisiana, the types of samples collected, the collection methods, the chemical analysis methods, and selected chemical analysis results. Also included are summaries of the project quality control results. The raw chemical analysis results are provided in this report without interpretation. Interpretations will be provided in subsequent reports.

Louisiana↗
USGS1993

Conservation genetics of managed ungulate populations

Natural populations of many species are increasingly impacted by human activities. Perturbations are particularly pronunced for large ungulates due in part to sport and commercial harvest, to reductions and fragmentation of native habitat, and as the result of reintroductions. These perturbations affect population size, sex and age composition, and population breeding structure, and as a consequence affect the levels and partitioning of genetic variation. Three case histories highlighting long-term ecological genetic research on mule deer Odocoileus hemionus (Rafinesque, 1817), white-tailed deer O . virginianus (Zimmermann, 1780), and Alpine ibex Capra i. ibex Linnaeus, 1758 are presented. Joint examinations of population ecological and genetic data from several populations of each species reveal: (1) that populations are not in genetic equilibrium, but that allele frequencies and heterozygosity change dramatically over time and among cohorts produced in successive years, (2) populations are genetically structured over short and large geographic distances reflecting local breeding structure and patterns of gene flow, respectively; however, this structure is quite dynamic over time, due in part to population exploitation, and (3) restocking programs are often undertaken with small numbers of founding individuals resulting in dramatic declines in levels of genetic variability and increasing levels of genetic differentiation among populations due to genetic drift. Genetic characteristics have and will continue to provide valuable indirect sources of information relating enviromental and human perturbations to changes in population processes.

Acta Theriologica↗
USGS2025

Near-surface geophysics: Environmental applications

The field of geophysics encompasses a broad and diverse compilation of methodologies that employs principles of physics to characterize properties of earth materials within the subsurface. While geophysical methods have a long history in resource exploration and studies of Earth’s interior, the subdiscipline of “near-surface geophysics” has evolved in recent decades for examination of the shallow, near-surface environment for a range of purposes ranging from archaeological or forensic investigations to assessment of geologic, hydrologic, biologic, and geochemical properties and processes. “Environmental geophysics” are near-surface geophysical studies and methods that focus on understanding natural systems (e.g., watershed hydrology, groundwater–surface water connections, biophysical processes) as well as research pertaining to anthropogenic impacts and land management, (e.g., contamination and remediation, saltwater intrusion, agricultural practices). This field can be further subdivided into subdisciplines focused on specific topics and applications, such as water resources and hydrology (hydrogeophysics) or biologic and microbial processes (biogeophysics). Studies in environmental geophysics span a range of scales, from pore-scale laboratory tests to watershed-scale or regional field experiments. Methods vary by the nature of physics employed, the specific measurement acquired, and how that data is ultimately processed and analyzed to produce interpretable results. There exists further diversity in the acquisition logistics, geometry, and timing of data collection. Geophysical data can be collected in boreholes (one-dimensional, 1-D, vertical profiles), along survey lines (two-dimensional, 2-D, cross-sections), or in dense sensor arrays or gridded profiles (three-dimensional, 3-D, models). Regarding the temporal aspect, studies can conduct one-time geophysical surveys to obtain detailed imaging of subsurface structure or use timelapse and continuous monitoring to investigate variations in subsurface properties over time. The cumulation of all possible permutations of these factors (method, acquisition geometry, survey design, and target application) results in an immense diversity among environmental geophysical studies. Nevertheless, this field remains unified in the pursuit of understanding natural and human-impacted near-surface environments through geophysical investigations. Here we highlight some key references within environmental geophysics. Resources on geophysical theory, acquisition logistics, processing and inversion workflows, and example case studies are categorized into the most common geophysical classes within Geophysical Methods. Lastly, example references for the dominant types of applications in environmental geophysical studies are catalogued in Environmental Applications.

Book chapter↗
USGS2016

Pockmarks in Passamaquoddy Bay, New Brunswick, Canada

Pockmarks are seafloor depressions associated with fluid escape ( Judd & Hovland 2007 ). They proliferate in the muddy seafloors of coastal Gulf of Maine and Bay of Fundy, where they are associated with shallow natural gas likely of biogenic origin ( Ussler et al. 2003 ; Rogers et al. 2006 ; Wildish et al. 2008 ). In North America, shallow-water pockmark fields are not reported south of Long Island Sound, despite the abundance of gassy, muddy estuaries. The absence of pockmarks south of the limit of North American glaciation suggests that local and regional heterogeneities, possibly related to glacial or sea-level history or bedrock geology, influence pockmark field distribution. In shallow-water embayments, such as Passamaquoddy Bay, New Brunswick, pockmarks can be large (>200 m diameter) and number in the thousands.

New Brunswick↗
USGS2010

The U.S.Geological Survey Energy Resources Program

Energy resources are an essential component of modern society. Adequate, reliable, and affordable energy supplies obtained using environmentally sustainable practices underpin economic prosperity, environmental quality and human health, and political stability. National and global demands for all forms of energy are forecast to increase significantly over the next several decades. Throughout its history, our Nation has faced important, often controversial, decisions regarding the competing uses of public lands, the supply of energy to sustain development and enable growth, and environmental stewardship. The U.S. Geological Survey (USGS) Energy Resources Program (ERP) provides information to address these challenges by supporting scientific investigations of energy resources, such as research on the geology, geochemistry, and geophysics of oil, gas, coal, heavy oil and natural bitumen, oil shale, uranium, and geothermal resources, emerging resources such as gas hydrates, and research on the effects associated with energy resource occurrence, production, and (or) utilization. The results from these investigations provide impartial, robust scientific information about energy resources and support the U.S. Department of the Interior's (DOI's) mission of protecting and responsibly managing the Nation's natural resources. Primary consumers of ERP information and products include the DOI land- and resource-management Bureaus; other Federal, State, and local agencies; the U.S. Congress and the Administration; nongovernmental organizations; the energy industry; academia; international organizations; and the general public.

Fact Sheet↗