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At least 1,225 records · Page 68Linked to original sources

USGS2015

Variables and potential models for the bleaching of luminescence signals in fluvial environments

Luminescence dating of fluvial sediments rests on the assumption that sufficient sunlight is available to remove a previously obtained signal in a process deemed bleaching. However, luminescence signals obtained from sediment in the active channels of rivers often contain residual signals. This paper explores and attempts to build theoretical models for the bleaching of luminescence signals in fluvial settings. We present two models, one for sediment transported in an episodic manner, such as flood-driven washes in arid environments, and one for sediment transported in a continuous manner, such as in large continental scale rivers. The episodic flow model assumes that the majority of sediment is bleached while exposed to sunlight at the near surface between flood events and predicts a power-law decay in luminescence signal with downstream transport distance. The continuous flow model is developed by combining the Beer–Lambert law for the attenuation of light through a water column with a general-order kinetics equation to produce an equation with the form of a double negative exponential. The inflection point of this equation is compared with the sediment concentration from a Rouse profile to derive a non-dimensional number capable of assessing the likely extent of bleaching for a given set of luminescence and fluvial parameters. Although these models are theoretically based and not yet necessarily applicable to real-world fluvial systems, we introduce these ideas to stimulate discussion and encourage the development of comprehensive bleaching models with predictive power.

Quaternary International↗

USGS2022

Bathymetric map, surface area, and stage-capacity for the U.S. part of Lake Koocanusa, Lincoln County, Montana, 2016–18

The U.S. Geological Survey and U.S. Army Corps of Engineers collected high-resolution multibeam sonar data during 2016–18 to compute stage-area and stage-capacity tables for the U.S. part of Koocanusa Reservoir in Lincoln County, northwestern Montana. Koocanusa Reservoir is a transboundary reservoir extending about 48 miles from Libby Dam upstream to the U.S. international boundary with Canada and another 42 miles within Canada to near Wardner, British Columbia. The upstream extent of the reservoir within Canada, where much of the sedimentation was previously documented, was not included in this study. Previously developed stage-area and stage-capacity tables were developed for the entire reservoir and could not be directly compared to the stage-area and stage-capacity tables from this study. Two discrete stage-area and stage-capacity values from the original survey (unknown survey date prior to 1980) were available for parts of the reservoir within the United States at the normal full-pool and normal minimum-pool elevations (2,459 and 2,287 U.S. survey feet above the National Geodetic Vertical Datum of 1929, respectively). At the normal full-pool elevation, the stage-area relation resulted in a 0.06-percent increase in surface-water acreage. Conversely, a 0.03-percent decrease in storage capacity at the normal full-pool elevation occurred. At the normal-minimum-pool elevation, the stage-area relation showed a 1.21-percent decrease in surface water from 14,487 to 14,314 acres. The usable storage capacity, defined as the volume of water between the normal full-pool and normal minimum-pool elevations, decreased by 0.39 percent (15,353 acre-feet). Results from this study indicate that a relatively minimal amount of sedimentation has occurred since initial filling in Koocanusa Reservoir for parts of the reservoir within the United States. Updated stage-area and stage-capacity tables for the entire reservoir will require additional bathymetric and topographic surveys for the parts of Koocanusa Reservoir within Canada.

Montana↗

USGS2016

The Bear River's history and diversion: Constraints, unsolved problems, and implications for the Lake Bonneville record: Chapter 2

The shifting course of the Bear River has influenced the hydrologic balance of the Bonneville basin through time, including the magnitude of Lake Bonneville. This was first recognized by G.K. Gilbert and addressed in the early work of Robert Bright, who focused on the southeastern Idaho region of Gem Valley and Oneida Narrows. In this chapter, we summarize and evaluate existing knowledge from this region, present updated and new chronostratigraphic evidence for the Bear River's drainage history, and discuss implications for the Bonneville record as well as future research needs. The Bear River in Plio-Pleistocene time joined the Snake River to the north by following the present-day Portneuf or Blackfoot drainages, with it likely joining the Portneuf River by middle Pleistocene time. An episode of volcanism in the Blackfoot-Gem Valley volcanic field, sparsely dated to ~ 100–50 ka, diverted the Bear River southward from where the Alexander shield volcano obstructed the river's path into Gem Valley. Previous chronostratigraphic and isotopic work on the Main Canyon Formation in southern Gem Valley indicates internal-basin sedimentation during the Quaternary, with a possible brief incursion of the Bear River ~ 140 ka. New evidence confirms that the Bear River's final diversion at 60–50 ka led to its integration into the Bonneville basin by spillover at a paleo-divide above present-day Oneida Narrows. This drove rapid incision before the rise of Lake Bonneville into the canyon and southern Gem Valley. Bear River diversion at 60–50 ka coincides with the end of the Cutler Dam lake cycle, at the onset of marine isotope stage 3. The Bear River subsequently contributed to the rise of Lake Bonneville, the highest pluvial lake known in the basin, culminating in the Bonneville flood. Key research questions include the prior path of the upper Bear River, dating and understanding the complex geologic relations within the Gem Valley-Blackfoot volcanic field, resolving evidence for possible earlier incursions of Bear River water into the Bonneville basin, and interpreting the sedimentology of the Main Canyon Formation.

Book chapter↗

USGS2023

Fishes of Harney Basin revisited: An assessment of the distribution of native and nonnative fishes over a half century

The Harney Basin is Oregon's largest internally draining basin and contains a unique native fish assemblage. The first and only comprehensive study of the origin and distribution of Harney Basin fishes occurred in 1971. Here, we update this study and identify potential threats to the basin's native fishes a half century later. Our assessment documents that all species of native fishes are still present, and with some exceptions distributed as originally reported. The distinctive fish assemblages in each of the 3 major subbasins within the Harney Basin (Silvies River, Silver Creek, and Donner und Blitzen River) support the hypothesis that terminal lakes in the Harney Basin (Malheur, Mud, and Harney Lakes) act as dispersal barriers, at least for native species. More than half of the fish species in the basin at present are introduced, primarily inhabiting low-elevation sites. We suggest that native non-salmonid species cohabiting these sites face the most immediate threats from climate change, water demands, and impacts from introduced fishes. Overall, our results show that native fish are still relatively widespread across the Harney Basin, but also face increasing threats despite the basin having experienced less development than many other areas in the Pacific Northwest. Improved understanding of the unique fishes of the Harney Basin, along with more detailed assessments of likely future trajectories of environmental risks are proactive measures that could improve conservation outcomes.

Oregon↗

USGS2019

Conservation status of the world’s swan populations, Cygnus sp. and Coscoroba sp.: a review of current trends and gaps in knowledge

Recent estimates of the world’s swan Cygnus sp. populations indicate that there are currently between 1.5–1.6 million birds in 8 species, including the Coscoroba Swan Coscoroba coscoroba as an honorary swan. Monitoring programmes in Europe and North America indicate that most populations increased following the introduction of national and international legislation to protect the species during the early- to mid-20th century. A switch from feeding primarily on aquatic vegetation to foraging on farmland (especially high-energy arable crops) in winter during the second half of the 20th century, is also considered a contributing factor. Trumpeter Swans Cygnus buccinator famously increased from just 69 individuals known to exist in 1935 (although small numbers were missed) to c. 76,000 at the present time, and most of the northern hemisphere swan populations have continued to show increasing/stable trends over the last 20 years. The exception to this pattern is a decline since 1995 in the Northwest European Bewick’s Swan population, following an increase in its population size during the 1970s–1980s, which is now being addressed through implementation of an International Single Species Action Plan. A proposal to change enforcement regulations of the Migratory Bird Treaty Act in the United States is also of concern, as potentially undermining protection for Trumpeter Swans in North America, illustrating the importance of politics and legislation as well as on-the-ground measures for species conservation. Elsewhere, less is known about the trends and conservation status for swans in central and eastern Asia, though count and research programmes introduced in China, added to those underway in Japan and Korea, have recently greatly enhanced our knowledge of swan populations on the East Asian flyway. Trends for the Black Swan Cygnus atratus in Australia and for the Black-necked Swan Cygnus melancoryphus in South America are also poorly known, because of the large numbers involved for the former and a lack of coordinated counts across difficult terrain for the latter. These southern hemisphere species are considered vulnerable to water resource developments ( i.e . where diversion of water is shrinking wetlands), and to droughts associated with El Nino events and climate change. More extensive monitoring is therefore required to determine whether swan populations and species are stable, fluctuating or in decline.

Wildfowl↗

USGS2023

A conceptual framework for estimation of initial emergency food and water resource requirements in disasters

Many households lack the necessary food and water supplies to sustain themselves for more than three days during a disaster. Community vulnerability assessments can be used to identify households with more pressing needs for emergency food and water resources. It is critical that these assessments include the interaction between physical impacts to lifeline infrastructure and the social vulnerabilities of food and water insecurity to prioritize, allocate, and distribute emergency resources. In this paper, we review and synthesize relevant literature to propose a new multidisciplinary conceptual framework of community vulnerability assessment for estimating initial emergency food and water resource requirements in a developed country. Using the framework as a guide, we illustrate its practical application through a simplified, deterministic model of initial resource requirements in disaster response, and offer a quantitative, comprehensive description of its application within the geophysical hazard context of the “ShakeOut” scenario—a major M w 7.8 earthquake on California's San Andreas fault , occurring within the Los Angeles Basin, CA (USA) region. Model results estimate that 999,027 households (2,947,130 residents) will require initial emergency food and water resource requirements. Estimates include about 6 million meals and 9 million liters of water, concentrated in Lancaster-Palmdale, El Monte-Baldwin Park, East Los Angeles-Downey in Los Angeles County, the Coachella Valley (Riverside County), and in populated areas of San Bernardino County. A sensitivity analysis of social vulnerability interactions with utility service outages investigates the influence of food insecurity on the amplification of resource needs. This study establishes fundamental knowledge at the nexus of natural hazards, critical infrastructure disruptions, and social vulnerability by providing initial estimates of emergency resource demand while advancing the understanding of social inequity in emergency resource access.

International Journal of Disaster Risk Reduction↗

USGS1991

Shoreline deposits and diagenesis resulting from two Late Pleistocene highstands near +5 and +6 metres, Durban, South Africa

In exposures of Pleistocene rocks on the east coast of South Africa, eight sedimentary facies were distinguished on the basis of petrology, grain size, internal structures and field relationships. These are interpreted as deposits of surf zone, breaker zone, swash zone, backbeach, boulder beach and dune environments. Three phases of deposition and diagenesis are recognized. As a result of the stabilising effect of pre-existing coastal facies, the deposits from successive sea level stands are stacked vertically in a narrow coast-normal strip. Early cementation prevented erosion of the deposits during subsequent transgressions. Deposition of subsequent facies took place on an existing coastal dune (Facies 1). A terrace was cut into this dune at a sea level 4.5 to 5 m above present. At this sea level, clastic shoreline sediments were deposited which make up the main sedimentary sequence exposed (Facies 2–7). The steep swash zone, coarse grain size, and comparison with modern conditions in the study area indicate clastic deposition on a high-energy, wave-dominated, microtidal coastline. Vertical stacking of progressively shallower water facies indicates progradation associated with slightly regressive conditions, prior to stranding of the succession above sea level. During a subsequent transgression to 5.5 or 6 m above present sea level, a second terrace was cut across the existing facies, which by then were partly lithified. A boulder beach (Facies 8) deposited on this terrace is indicative of high wave energy and a rocky coastline, formed by existing cemented coastal facies. Comparison with dated deposits from other parts of the South African coast suggest a Late Pleistocene age for Facies 2–8. Deposition was terminated by subsequent regression and continuing low sea levels during the remainder of the Pleistocene. Cementation of the facies took place almost entirely by carbonate precipitation. The presence of isopachous fibrous cements suggests early cementation of Facies 1, 2, 3 and 4 under marine conditions, initially as aragonite which has since inverted to calcite. Facies 5, 6 and 7 are cemented only by equant calcite spar, evidence of cementation in the meteoric phreatic and vadose zones. Lowering of the water table during regression caused the remaining pore space in Facies 1, 2, 3 and 4 to be filled with equant calcite spar. Decementation in a 130 cm wide zone is attributed to water table shifts associated with the later transgression which deposited Facies 8. The vertical stacking of the two depositional sequences may be attributed to rapid cementation of Facies 2, 3, 4, 5, 6 and 7 under humid, subtropical conditions. This lithified sequence then acted as a focus for deposition of coarse-grained shoreline facies (Facies 8) during the subsequent transgression.

Marine Geology↗

USGS1969

Oxygen isotope fractionation in divalent metal carbonates

Equilibrium fractionation factors for the distribution of 18 O between alkaline‐earth carbonates and water have been measured over the temperature range 0–500°C. The fractionation factors α"> α α can be represented by the equations CaCO3–H2O, 1000lnα = 2.78(106T−2)− 3.39,"> CaCO 3 – H 2 O , 1000 ln α = 2.78(10 6 T −2 )− 3.39, CaCO3–H2O, 1000lnα = 2.78(106T−2)− 3.39, SrCO3–H2O, 1000lnα = 2.69(106T−2)− 3.74,"> SrCO 3 – H 2 O , 1000 ln α = 2.69(10 6 T −2 )− 3.74, SrCO3–H2O, 1000lnα = 2.69(106T−2)− 3.74, BaCO3–H2O, 1000lnα = 2.57(106T−2)− 4.73."> BaCO 3 – H 2 O , 1000 ln α = 2.57(10 6 T −2 )− 4.73. BaCO3–H2O, 1000lnα = 2.57(106T−2)− 4.73. Measurements on MnCO 3 , CdCO 3 , and PbCO 3 were made at isolated temperatures. A statistical‐mechanical calculation of the isotopic partition function ratios gives reasonably good agreement with experiment. Both cationic size and mass are important in isotopic fractionation, the former predominantly in its effect on the internal vibrations of the anion, the latter in its effect on the lattice vibrations.

Journal of Chemical Physics↗

USGS2004

SutraGUI, a graphical-user interface for SUTRA, a model for ground-water flow with solute or energy transport

This report describes SutraGUI, a flexible graphical user-interface (GUI) that supports two-dimensional (2D) and three-dimensional (3D) simulation with the U.S. Geological Survey (USGS) SUTRA ground-water-flow and transport model (Voss and Provost, 2002). SutraGUI allows the user to create SUTRA ground-water models graphically. SutraGUI provides all of the graphical functionality required for setting up and running SUTRA simulations that range from basic to sophisticated, but it is also possible for advanced users to apply programmable features within Argus ONE to meet the unique demands of particular ground-water modeling projects. SutraGUI is a public-domain computer program designed to run with the proprietary Argus ONE? package, which provides 2D Geographic Information System (GIS) and meshing support. For 3D simulation, GIS and meshing support is provided by programming contained within SutraGUI. When preparing a 3D SUTRA model, the model and all of its features are viewed within Argus 1 in 2D projection. For 2D models, SutraGUI is only slightly changed in functionality from the previous 2D-only version (Voss and others, 1997) and it provides visualization of simulation results. In 3D, only model preparation is supported by SutraGUI, and 3D simulation results may be viewed in SutraPlot (Souza, 1999) or Model Viewer (Hsieh and Winston, 2002). A comprehensive online Help system is included in SutraGUI. For 3D SUTRA models, the 3D model domain is conceptualized as bounded on the top and bottom by 2D surfaces. The 3D domain may also contain internal surfaces extending across the model that divide the domain into tabular units, which can represent hydrogeologic strata or other features intended by the user. These surfaces can be non-planar and non-horizontal. The 3D mesh is defined by one or more 2D meshes at different elevations that coincide with these surfaces. If the nodes in the 3D mesh are vertically aligned, only a single 2D mesh is needed. For nonaligned meshes, two or more 2D meshes of similar connectivity are used. Between each set of 2D meshes (and model surfaces), the vertical space in the 3D mesh is evenly divided into a user-specified number of layers of finite elements. Boundary conditions may be specified for 3D models in SutraGUI using a variety of geometric shapes that may be located freely within the 3D model domain. These shapes include points, lines, sheets, and solids. These are represented by 2D contours (within the vertically-projected Argus ONE view) with user-defined elevations. In addition, boundary conditions may be specified for 3D models as points, lines, and areas that are located exactly within the surfaces that define the model top and the bottoms of the tabular units. Aquifer properties may be specified separately for each tabular unit. If the aquifer properties vary vertically within a unit, SutraGUI provides the Sutra_Z function that can be used to specify such variation.

Open-File Report↗

USGS1995

Petrography, geochemistry, and depositional setting of the San Pedro and Santo Tomas coal zones: Anomalous algae-rich coals in the middle part of the Claiborne Group (Eocene) of Webb County, Texas

Two coal zones, the San Pedro and the overlying Santo Tomas, are present for nearly 35 km in outcrop, surface and underground mines, and shallow drill holes along the strike of the middle part of the Claiborne Group (Eocene) in Webb County, Texas. A sandstone-dominated interval of 25 to 35 m separates the two coal zones, which range up to 3 m in thickness. Each coal zone contains carbonaceous shales, thin (<0.75 m) impure coal beds, and thin (<0.85 m) but commercially significant nonbanded coal beds. The nonbanded coals are different from other Tertiary coals of the Gulf of Mexico Coastal Plain: unlike lignites that are typical of the older Wilcox Group (Paleocene-Eocene) and younger Jackson Group (Eocene), nonbanded coals of the Claiborne Group have high vitrinite-reflectance values (0.53 R max ) and high calorific yields (average 6670 kcal/kg or 12,000 Btu, dry basis). The coals are weakly agglomerating (free-swelling index is 1.5–2.0) and have an apparent rank of high-volatile bituminous. The coal-bearing portion of the middle Claiborne Group in the Rio Grande area represents a fining-upward transition from sandstone-dominated, marine-influenced, lower delta plain depositional environments to more inland, mudstone-rich, predominantly freshwater deltaic settings. Discontinuities within the San Pedro coal zone are attributed mainly to the influence of contemporaneous deposition of distributary mouth-bar sand bodies. The less variable nature of the Santo Tomas coal zone reflects its origin in the upper part of an interlobe basin that received only minor clastic influx. Petrographic attributes of the nonbanded coals indicate that they formed subaqueously in fresh to possibly brackish waters. A highly degraded groundmass composed of eugelinite is the main petrographic component (approximately 71%, mineral-matter-free basis). An enriched liptinite fraction (approximately 23%) probably accounts for unusually high calorific values. There is negligible inertinite. Petrographic study of polished blocks indicates that approximately 10 percent of the nonbanded coal from both coal zones is composed of green algae fructifications, which also occur in clastic rocks of the coal-bearing interval. Such algal material cannot be identified or quantified by conventional coal petrographic techniques that utilize particle pellets or by palynological analyses that include acid preparation.

International Journal of Coal Geology↗

USGS2011

On the terminology of the spectral vegetation index (NIR – SWIR)/(NIR + SWIR)

The spectral vegetation index (ρNIR – ρSWIR)/(ρNIR + ρSWIR), where ρNIR and ρSWIR are the near-infrared (NIR) and shortwave-infrared (SWIR) reflectances, respectively, has been widely used to indicate vegetation moisture condition. This index has multiple names in the literature, including infrared index (II), normalized difference infrared index (NDII), normalized difference water index (NDWI), normalized difference moisture index (NDMI), land surface water index (LSWI), and normalized burn ratio (NBR), etc. After reviewing each term’s definition, associated sensors, and channel specifications, we found that the index consists of three variants, differing only in the SWIR region (1.2–1.3 µm, 1.55–1.75 µm, or 2.05–2.45 µm). Thus, three terms are sufficient to represent these three SWIR variants; other names are redundant and therefore unnecessary. Considering the spectral representativeness, the term’s popularity, and the “rule of priority” in scientific nomenclature, NDWI, NDII, and NBR, each corresponding to the three SWIR regions, are more preferable terms.

International Journal of Remote Sensing↗

USGS1979

Seismic refraction profile, Kingdom of Saudi Arabia: field operations, instrumentation, and initial results

In February 1978 a seismic deep-refraction profile was recorded by the USGS along a 1000-km line across the Arabian Shield in western Saudi Arabia. The line begins in Paleozoic and Mesozoic cover rocks near Riyadh on the Arabian Platform, leads southwesterly across three major Precambrian tectonic provinces, traverses Cenozoic rocks of the coastal plain near Jizan (Tihamat Asir), and terminates at the outer edge of the Farasan Bank in the southern Red Sea. More than 500 surveyed recording sites were occupied, including 19 in the Farasan Islands. Six shot points were used--five on land, with charges placed mostly below water table in drill holes, and one at sea, with charges placed on the sea floor and fired from a ship. The total charge consumed was slightly in excess of 61 metric tons in 21 discrete firings. Seismic energy was recorded by means of a set of 100 newly developed portable seismic stations. Each station consists of a standard 2-Hz vertical geophone coupled to a self-contained analog recording instrument equipped with a magnetic-tape cassette. The stations were deployed in groups of 20 by five observer teams, each generally consisting of two scientist-technicians and a surveyor-guide. On the day prior to deployment, the instruments were calibrated and programmed for automatic operation by means of a specially designed device called a hand-held tester. At each of ten pre-selected recording time windows on a designated firing day, the instruments were programmed to turn on, stabilize, record internal calibration signals, record the seismic signals at three levels of amplification, and then deactivate. After the final window in the firing sequence, all instruments were retrieved and their data tapes removed for processing. A specially designed, field tape- dubbing system was utilized at shot point camps to organize and edit data recorded on the cassette tapes. The main functions of this system are to concatenate all data from each shot on any given day onto a single shot tape, and to provide hard copy for monitoring recorder performance so that any problems can be corrected prior to the next deployment. Composite digital record sections were produced from the dubbed tapes for each shot point by a portable processing and plotting system. The heart of this system is a DEC PDP 11VO3 computer, which controls a cassette playback unit identical to those used in the recorders and dubbers, a set of discriminators, a time-code translator, a digitizer, and a digital plotter. The system was used to maintain various informational data sets and to produce tabulations and listings of various sorts during the field operations, in addition to its main task of producing digital record sections. Two master clocks, both set to time signals broadcast by the British Broadcasting Corporation, provided absolute time for the recording operations. One was located on the ship and the other was stationed at a base camp on the mainland. The land-based master clock was used to set three additional master clocks located at the other active shot points a few days in advance of each firing, and these clocks were then used to set the internal clocks in the portable seismic stations via the hand-held tester. A master clock signal was also linked to the firing system at each shot point for determination of the absolute shot instant. It is possible to construct a generalized crustal model from examination of the six shot point composite record sections obtained in the field. Such a model rests upon a number of simplifying assumptions and will almost certainly be modified at a later stage of interpretation. The main assumptions are that the crust consists of two homogeneous isotropic layers having no velocity inversion,, that the Mohorovicic discontinuity is sharp, and that effects of surface inhomogeneities and elevation changes can be ignored. The main characteristics of the tentative model are the following: (1) The thickness of th

Open-File Report↗

USGS2019

Social equity shapes zone-selection: Balancing aquatic biodiversity conservation and ecosystem services delivery in the transboundary Danube River Basin

Freshwater biodiversity is declining, despite national and international efforts to manage and protect freshwater ecosystems. Ecosystem-based management (EBM) has been proposed as an approach that could more efficiently and adaptively balance ecological and societal needs. However, this raises the question of how social and ecological objectives can be included in an integrated management plan. Here, we present a generic model-coupling framework tailored to address this question for freshwater ecosystems, using three components: biodiversity, ecosystem services (ESS), and a spatial prioritisation that aims to balance the spatial representation of biodiversity and ESS supply and demand. We illustrate this model-coupling approach within the Danube River Basin using the spatially explicit, potential distribution of (i) 85 fish species as a surrogate for biodiversity as modelled using hierarchical Bayesian models, and (ii) four estimated ESS layers produced by the Artificial Intelligence for Ecosystem Services (ARIES) platform (with ESS supply defined as carbon storage and flood regulation, and demand specified as recreation and water use). These are then used for (iii) a joint spatial prioritisation of biodiversity and ESS employing Marxan with Zones, laying out the spatial representation of multiple management zones. Given the transboundary setting of the Danube River Basin, we also run comparative analyses including the country-level purchasing power parity (PPP)-adjusted gross domestic product (GDP) and each country's percent cover of the total basin area as potential cost factors, illustrating a scheme for balancing the share of establishing specific zones among countries. We demonstrate how emphasizing various biodiversity or ESS targets in an EBM model-coupling framework can be used to cost-effectively test various spatially explicit management options across a multi-national case study. We further discuss possible limitations, future developments, and requirements for effectively managing a balance between biodiversity and ESS supply and demand in freshwater ecosystems.

Science of the Total Environment↗

USGS2010

The CEOS-Land Surface Imaging Constellation Portal for GEOSS: A resource for land surface imaging system information and data access

The Committee on Earth Observation Satellites is an international group that coordinates civil space-borne observations of the Earth, and provides the space component of the Global Earth Observing System of Systems (GEOSS). The CEOS Virtual Constellations concept was implemented in an effort to engage and coordinate disparate Earth observing programs of CEOS member agencies and ultimately facilitate their contribution in supplying the space-based observations required to satisfy the requirements of the GEOSS. The CEOS initially established Study Teams for four prototype constellations that included precipitation, land surface imaging, ocean surface topography, and atmospheric composition. The basic mission of the Land Surface Imaging (LSI) Constellation [1] is to promote the efficient, effective, and comprehensive collection, distribution, and application of space-acquired image data of the global land surface, especially to meet societal needs of the global population, such as those addressed by the nine Group on Earth Observations (GEO) Societal Benefit Areas (SBAs) of agriculture, biodiversity, climate, disasters, ecosystems, energy, health, water, and weather. The LSI Constellation Portal is the result of an effort to address important goals within the LSI Constellation mission and provide resources to assist in planning for future space missions that might further contribute to meeting those goals.

earthzine, an IEEE online publication↗

USGS2023

Broadscale distribution, abundance and habitat associations of the invasive Asian clam (Corbicula fluminea) in the lower Columbia River, USA

The Asian clam, Corbicula fluminea , is an invasive freshwater bivalve that has established populations across the globe and is known to have deleterious effects on natural and human systems. Yet, despite being present in the Columbia River (CR) for nearly a century, little is known about this invader's basic biology and ecology in this large river system. Thus, we undertook a field study to assess its i) broadscale distribution and abundance, and ii) associations with habitat characteristics in the lower CR. During 2019-20, C. fluminea were collected from 27 shore-based stations spanning 481 river kilometers of the lower CR, along with several habitat characteristics (bank slope, temperature, dissolved oxygen, pH, salinity, conductivity, chlorophyll- a concentration, and sediment composition and % organic matter). C. fluminea abundance ranged from 0-430 ind. m -2 . Most sites with abundances >100 ind. m -2 were located downstream of Bonneville Dam, while most sites with abundances < 100 ind. m -2 were located upstream. Generalized linear models predicting the abundance of C. fluminea indicated significantly positive correlations with water temperature and % sand, and negative correlations with bank slope and sedimentary % organic matter. We also reviewed the global literature on abundance and habitat associations of C. fluminea and compared this with our own results. Our investigation represents the greatest spatial extent at which C. fluminea has been studied in the CR and our results provide a better understanding of the basic biology and ecology of this global invader, as well as provide natural resource managers with information on habitat conditions favorable for this invasive bivalve within temperate river ecosystems.

Oregon, Washington↗

USGS2014

A new analysis of Mars "Special Regions": findings of the Second MEPAG Special Regions Science Analysis Group (SR-SAG2)

A committee of the Mars Exploration Program Analysis Group (MEPAG) has reviewed and updated the description of Special Regions on Mars as places where terrestrial organisms might replicate (per the COSPAR Planetary Protection Policy). This review and update was conducted by an international team (SR-SAG2) drawn from both the biological science and Mars exploration communities, focused on understanding when and where Special Regions could occur. The study applied recently available data about martian environments and about terrestrial organisms, building on a previous analysis of Mars Special Regions (2006) undertaken by a similar team. Since then, a new body of highly relevant information has been generated from the Mars Reconnaissance Orbiter (launched in 2005) and Phoenix (2007) and data from Mars Express and the twin Mars Exploration Rovers (all 2003). Results have also been gleaned from the Mars Science Laboratory (launched in 2011). In addition to Mars data, there is a considerable body of new data regarding the known environmental limits to life on Earth—including the potential for terrestrial microbial life to survive and replicate under martian environmental conditions. The SR-SAG2 analysis has included an examination of new Mars models relevant to natural environmental variation in water activity and temperature; a review and reconsideration of the current parameters used to define Special Regions; and updated maps and descriptions of the martian environments recommended for treatment as "Uncertain" or "Special" as natural features or those potentially formed by the influence of future landed spacecraft. Significant changes in our knowledge of the capabilities of terrestrial organisms and the existence of possibly habitable martian environments have led to a new appreciation of where Mars Special Regions may be identified and protected. The SR-SAG also considered the impact of Special Regions on potential future human missions to Mars, both as locations of potential resources and as places that should not be inadvertently contaminated by human activity.

Astrobiology↗

USGS1985

Paleoclimate controls on late paleozoic sedimentation and peat formation in the central appalachian basin (U.S.A.)

In the central Appalachian basin, at least two major climate changes affected sedimentation during the late Paleozoic. Stratigraphically, these two changes are indicated by the distribution of coal beds, the variation in coal quality, and the variation in rock lithologies. In latest Mississippian or earliest Pennsylvanian time, the climate changed from dry-seasonal tropical to ever-wet (equable) tropical. The equable climate prevailed into the Middle Pennsylvanian, influencing the morphology and geochemistry in peat-forming environments. Many of the peat deposits, which formed under the equable climate, were probably domed (raised bogs); low concentrations of dissolved solids in peat formation water resulted in low buffering capacity. Organic acids caused acidic (pH < 4), antiseptic conditions that resulted in intense leaching of mineral matter, minimal degradation of organic matter, and low-ash and low-sulfur peat deposits; the resulting coal beds are also low in ash and sulfur. Associated rocks are noncalcareous and consist of sequences of interbedded shale, siltstone, and sandstone including quartz arenite. Another climate change occurred in late Middle Pennsylvanian time when evapopation periodically exceeded rainfall resulting in an increase of both dissolved solids and pH (4 to ∼ 7) in surface and near-surface water. Throughout the remainder of the Pennsylvanian, the surfaces of peat deposits were probably planar (not domed); water in peat-forming and other depositional environments became more nearly neutral. The coal beds derived from these peats are highly variable in both ash and sulfur contents. Drier or more seasonal climates are also indicated by sequences of (1) calcareous sandstone and shale, (2) nonmarine limestone that shows shallow-water and subaerial exposure features, and (3) calcareous paleosols that have caliche characteristics. Our data and observations indicate that physical depositional environment models for the origin of coal do not adequately explain variations in mineral matter content and composition in commercial quality coal beds in the central Appalachian basin. Stratigraphic variation in mineral matter in coal beds, and in syngenetic and early diagenetic minerals in rocks associated with the coal beds, appears to be better explained by changes in geochemical conditions of nonmarine sedimentation. Paleoclimate was a principle control on these geochemical conditions.

International Journal of Coal Geology↗

USGS2014

The offshore benthic fish community

Lake Ontario’s offshore benthic fish community includes primarily slimy sculpin, lake whitefish, rainbow smelt, lake trout, burbot, and sea lamprey. Of these, lake trout have been the focus of an international restoration effort for more than three decades (Elrod et al. 1995; Lantry and Lantry 2008). The deepwater sculpin and three species of deepwater ciscoes (Coregonus spp.) that were historically important in the offshore benthic zone became rare or were extirpated by the 1960s (Christie 1973; Owens et al. 2003; Lantry et al. 2007b; Roth et al. 2013). Ecosystem changes continue to influence the offshore benthic fish community, including the effects of dreissenid mussels, the near disappearance of burrowing amphipods (Diporeia spp.) (Dermott et al. 2005; Watkins et al. 2007), and the increased abundance and expanded geographic distribution of round goby (see Nearshore Fish Community chapter) (Lantry et al. 2007b). The fish-community objectives for the offshore benthic fish community, as described by Stewart et al. (1999), are: The offshore benthic fish community will be composed of self-sustaining native fishes characterized by lake trout as the top predator, a population expansion of lake whitefish from northeastern waters to other areas of the lake, and rehabilitated native prey fishes.

New York↗