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At least 253 records · Page 14Linked to original sources
USGS2024

From exploration to production: Understanding the development dynamics of lithium mining projects

Recently, there has been considerable recent controversy whether current and new lithium mines will be able to supply the rapidly growing needs of the electromobility transition. Mineral exploration projects are typically active for many years, and only some become operational mines. From exploration to production, the projects go through several stages of characterisation and evaluation. At each stage, decisions are made by companies and stakeholders to advance, continue or stop the project. This is a complex process, and even projects with very similar geological and technical characteristics may take very different trajectories, depending on external factors such as global market conditions and local regulatory environments. The present study investigates the dynamics of this process for lithium exploration projects. A global database of 397 lithium projects was compiled, covering their progression through major development stages between 2004 and 2022. Ordinal logistic regression was used for the statistical analysis of this data. Different explanatory variables were tested, including economic, geological, technical, and geographic factors, to identify the best predictors for project progress at each development stage. The results suggest an essential role for lithium carbonate prices, and a variable role for other factors at each stage. Critically, the already elapsed lead time and project economics, which are traditionally considered important for the prediction of the start-up of individual mines, do not appear to be relevant in all cases. The results provide important insights into the dynamics of lithium supply and may eventually allow more realistic forecasts to be made for future lithium market dynamics.

Resources Policy↗
USGS2008

Geologic controls on the growth of petroleum reserves

The geologic characteristics of selected siliciclastic (largely sandstone) and carbonate (limestone and dolomite) reservoirs in North America (largely the continental United States) were investigated to improve our understanding of the role of geology in the growth of petroleum reserves. Reservoirs studied were deposited in (1) eolian environments (Jurassic Norphlet Formation of the Gulf Coast and Pennsylvanian-Permian Minnelusa Formation of the Powder River Basin), (2) interconnected fluvial, deltaic, and shallow marine environments (Oligocene Frio Formation of the Gulf Coast and the Pennsylvanian Morrow Formation of the Anadarko and Denver Basins), (3) deeper marine environments (Mississippian Barnett Shale of the Fort Worth Basin and Devonian-Mississippian Bakken Formation of the Williston Basin), (4) marine carbonate environments (Ordovician Ellenburger Group of the Permian Basin and Jurassic Smackover Formation of the Gulf of Mexico Basin), (5) a submarine fan environment (Permian Spraberry Formation of the Midland Basin), and (6) a fluvial environment (Paleocene-Eocene Wasatch Formation of the Uinta-Piceance Basin). The connection between an oil reservoir's production history and geology was also evaluated by studying production histories of wells in disparate reservoir categories and wells in a single formation containing two reservoir categories. This effort was undertaken to determine, in general, if different reservoir production heterogeneities could be quantified on the basis of gross geologic differences. It appears that reserve growth in existing fields is most predictable for those in which reservoir heterogeneity is low and thus production differs little between wells, probably owing to relatively homogeneous fluid flow. In fields in which reservoirs are highly heterogeneous, prediction of future growth from infill drilling is notably more difficult. In any case, success at linking heterogeneity to reserve growth depends on factors in addition to geology, such as engineering and technological advances and political or cultural or economic influences.

Bulletin↗
USGS2021

Wetlands in intermittently closed estuaries can build elevations to keep pace with sea-level rise

Sea-level rise is a threat to coastal ecosystems, which have important conservation and economic value. While marsh response to sea-level rise has been well characterized for perennially open estuaries, bar-built intermittently-closed estuaries and their sea-level rise response are seldom addressed in the literature – despite being common globally. We seek to advance the conceptual understanding of sea-level rise response of marshes by incorporating the unique nature of intermittently-closed estuaries in a marsh model. We hypothesize that intermittently-closed-estuary marshes may be more resilient to sea-level rise than open-estuary marshes due to greater initial elevation capital and higher accretion rates due to closure events. Using California, USA as a case study, spatial analysis shows that marshes in intermittently-closed-estuaries had significantly greater elevations (x̄ = 1.93 m ± 0.2 standard error, n = 14) than marshes in permanently open estuaries (x̄ = 0.94 m ± 0.1 standard error, n = 8; P = 0.003). We then used a process-based model to determine marsh elevation change under 840 simulated responses to sea-level rise to 2100. Our modeling shows that regular annual mouth closure can promote accretion rates and increase marsh elevations fast enough to match even high rates of sea-level rise, as fluvial sediment pulses can be captured in the estuary. Modeled suspended sediment concentration had the strongest effect on accretion, followed by probability of annual mouth closure. Intermittently closed estuaries are critical environments where marshes may be sustained under high rates of sea-level rise, thus reducing the anticipated global loss of these important ecosystems. Our results begin to fill an important gap in the knowledge about marsh accretion and identify research needs to inform coastal management.

Estuarine, Coastal and Shelf Science↗
USGS2015

Evaluating the status of individuals and populations: Advantages of multiple approaches and time scales

The assessment of population status is a central goal of applied wildlife research and essential to the field of wildlife conservation. “Population status” has a number of definitions, the most widely used having to do with the current trajectory of the population (i.e., growing, stable, or declining), or the probability of persistence (i.e., extinction risk), perhaps without any specific knowledge as to the factors driving a population’s dynamics. In contrast, a population’s status relative to the carrying capacity of the environment ( K ) is an ecologically-based definition that explicitly provides information about a major mechanism of population control. That is, it relates to the relative per capita availability of resources to individuals in a population, which can also be used to infer the state of the environment itself. Sea otters in the North Pacific provide an excellent system with which to examine various approaches to assessing population status relative to K . This is because sea otters were nearly extirpated by historic commercial overexploitation in the eighteenth and nineteenth centuries, followed by natural and translocation-aided population recovery during the twentieth century, and this decline and recovery has been relatively well documented. This provided a unique opportunity to study populations at the extremes of the population status spectrum. Here we describe and review the approaches that have been utilized in sea otter research to understand the status of populations relative to resource abundance. Specifically, we will illustrate the utility of various indices of population status for understanding population dynamics using the case study of a second precipitous sea otter decline in the Western Aleutians. The indices or “tools” described here fit into several broad categories including (1) energetic, (2) morphological, and (3) demographic as well as a fourth category of emerging tools that have not yet been employed in many other situations including dietary diversity, community structure, spatial distribution, and gene expression. Overall, a variety of indices used to measure population status throughout the sea otter’s range have provided insights for understanding the mechanisms driving the trajectory of various sea otter populations, which a single index could not, and we suggest using multiple methods to measure a population’s status at multiple spatial and temporal scales. The work described here also illustrates the usefulness of long-term data sets and/or approaches that can be used to assess population status retrospectively, providing information otherwise not available. While not all systems will be as amenable to using all the approaches presented here, we expect innovative researchers could adapt analogous multi-scale methods to a broad range of habitats and species including apex predators occupying the top trophic levels, which are often of conservation concern.

Book chapter↗
USGS2017

Land area change in coastal Louisiana (1932 to 2016)

Coastal Louisiana wetlands are one of the most critically threatened environments in the United States. These wetlands are in peril because Louisiana currently experiences greater coastal wetland loss than all other States in the contiguous United States combined. The analyses of landscape change presented here have utilized historical surveys, aerial, and satellite data to quantify landscape changes from 1932 to 2016. Analyses show that coastal Louisiana has experienced a net change in land area of approximately -4,833 square kilometers (modeled estimate: -5,197 +/- 443 square kilometers) from 1932 to 2016. This net change in land area amounts to a decrease of approximately 25 percent of the 1932 land area. Previous studies have presented linear rates of change over multidecadal time periods which unintentionally suggest that wetland change occurs at a constant rate, although in many cases, wetland change rates vary with time. A penalized regression spline technique was used to determine the model that best fit the data, rather than fitting the data with linear trends. Trend analyses from model fits indicate that coastwide rates of wetland change have varied from -83.5 +/- 11.8 square kilometers per year to -28.01 +/- 16.37 square kilometers per year. To put these numbers into perspective, this equates to long-term average loss rates of approximately an American football field’s worth of coastal wetlands within 34 minutes when losses are rapid to within 100 minutes at more recent, slower rates. Of note is the slowing of the rate of wetland change since its peak in the mid- 1970s. Not only have rates of wetland loss been decreasing since that time, a further rate reduction has been observed since 2010. Possible reasons for this reduction include recovery from lows affected by the hurricanes of 2005 and 2008, the lack of major storms in the past 8 years, a possible slowing of subsidence rates, the reduction in and relocation of oil and gas extraction and infrastructure since the peak of such activities in the late 1960s, and restoration activities. In addition, many wetlands in more exposed positions in the landscape have already been lost. Most notable of the factors listed above is the lack of major storms over the past 8 years. The observed coastwide net “stability” in land area observed over the past 6–8 years does not imply that loss has ceased. Future disturbance events such as a major hurricane impact could change the trajectory of the rates. Sea-level rise is projected to increase at an exponential rate, and that would also expedite the rate of wetland loss.

Louisiana↗
USGS2010

The power to detect trends in Missouri River fish populations within the Pallid Sturgeon Population Assessment Program

As with all large rivers in the United States, the Missouri River has been altered, with approximately 32.5 percent of the main stem length impounded and 32.5 percent channelized. These physical alterations to the environment have had effects on the fisheries, but studies examining the effects of alterations have been localized and for short periods of time. In response to the U.S. Fish and Wildlife Service biological opinion, the U.S. Army Corps of Engineers initiated monitoring of the fish community of the Missouri River in 2003. The goal of the Pallid Sturgeon Population Assessment Program is to provide information to detect changes in populations and habitat preferences with time for pallid sturgeon (Scaphirhynchus albus) and native target species in the Missouri River Basin. To determine statistical power of the Pallid Sturgeon Population Assessment Program, a power analysis was conducted using a normal linear mixed model with variance component estimates based on the first 3 years of data (2003 to 2005). In cases where 3 years of data were unavailable, estimates were obtained using those data. It was determined that at least 20 years of data, sampling 12 bends with 8 subsamples per bend, would be required to detect a 5 percent annual decline in most of the target fish populations. Power varied between Zones. Zone 1 (upstream from Lake Sakakawea) did not have any species/gear type combinations with adequate power, whereas Zone 3 (downstream from Gavins Point Dam) had 19 species/gear type combinations with adequate power. With a slight increase in the sampling effort to 12 subsamples per bend, the Pallid Sturgeon Population Assessment Program has adequate power to detect declines in shovelnose sturgeon (S. platorynchus) throughout the entire Missouri River because of large catch rates. The lowest level of non-occurrence (in other words, zero catches) at the bend level for pallid sturgeon was 0.58 using otter trawls in Zone 1. Consequently, the power of the pallid sturgeon models was not as high as other species at the current level of sampling, but an increase in the sampling effort to 16 subsamples for each of 24 bends for 20 years would generate adequate power for the pallid sturgeon in all Zones. Since gear types are selective in their species efficiency, the strength of the Pallid Sturgeon Population Assessment Program approach is using multiple gears that have statistical power to detect population trends at the same time in different fish species within the Missouri River. As often is the case with monitoring studies involving endangered species, the data used to conduct the analyses exhibit some departures from the parametric model assumptions; however, preliminary simulations indicate that the results of this study are appropriate.

Open-File Report↗
USGS2024

A strategic and science-based framework for management of invasive annual grasses in the sagebrush biome

In the last 20 years, the North American sagebrush biome has lost over 500,000 ha of intact and largely intact sagebrush plant communities on an annual basis. Much of this loss has been associated with expansion and infilling of invasive annual grasses (IAGs). These species are highly competitive against native perennial grasses in disturbed environments, and create fuel conditions that increase both the likelihood of fire ignition and the ease of wildfire spread across large landscapes. Given the current rate of IAG expansion in both burned and unburned rangelands, ameliorating the IAG threat will involve a range-wide paradigm shift from opportunistic and reactive management, to a framework that spatially prioritizes maintenance of largely intact, uninvaded areas and improvement of invaded habitats in strategic locations. We created a framework accompanied by biome-wide priority maps using geospatial overlays that target areas to MAINTAIN large, uninvaded areas as natural resource anchors through activities to prevent IAGs and IMPROVE areas to reduce invasions with the highest potential for management efforts to succeed in restoring large, intact landscapes. We then offer three case studies to illustrate the use of these concepts and map products at multiple scales. Our map products operate at the biome scale using regional data sources but additional data sources may be needed to inform local conservation planning. However, the basic strategic management principles of a) maintaining the intact and uninvaded areas that we can least afford to lose to IAGs and b) improving areas where we have a higher likelihood of restoration success, is timely, relevant, and scalable from the biome to local levels.

Rangeland Ecology & Management↗
USGS2016

Exploring climate niches of ponderosa pine (Pinus ponderosa Douglas ex Lawson) haplotypes in the western United States: Implications for evolutionary history and conservation

Ponderosa pine ( Pinus ponderosa Douglas ex Lawson) occupies montane environments throughout western North America, where it is both an ecologically and economically important tree species. A recent study using mitochondrial DNA analysis demonstrated substantial genetic variation among ponderosa pine populations in the western U.S., identifying 10 haplotypes with unique evolutionary lineages that generally correspond spatially with distributions of the Pacific ( P . p . var. ponderosa ) and Rocky Mountain ( P . p . var. scopulorum ) varieties. To elucidate the role of climate in shaping the phylogeographic history of ponderosa pine, we used nonparametric multiplicative regression to develop predictive climate niche models for two varieties and 10 haplotypes and to hindcast potential distribution of the varieties during the last glacial maximum (LGM), ~22,000 yr BP. Our climate niche models performed well for the varieties, but haplotype models were constrained in some cases by small datasets and unmeasured microclimate influences. The models suggest strong relationships between genetic lineages and climate. Particularly evident was the role of seasonal precipitation balance in most models, with winter- and summer-dominated precipitation regimes strongly associated with P . p . vars. ponderosa and scopulorum , respectively. Indeed, where present-day climate niches overlap between the varieties, introgression of two haplotypes also occurs along a steep clinal divide in western Montana. Reconstructed climate niches for the LGM suggest potentially suitable climate existed for the Pacific variety in the California Floristic province, the Great Basin, and Arizona highlands, while suitable climate for the Rocky Mountain variety may have existed across the southwestern interior highlands. These findings underscore potentially unique phylogeographic origins of modern ponderosa pine evolutionary lineages, including potential adaptations to Pleistocene climates associated with discrete temporary glacial refugia. Our predictive climate niche models may inform strategies for further genetic research (e.g., sampling design) and conservation that promotes haplotype compatibility with projected changes in future climate.

PLoS ONE↗
USGS2026

3D semantic mapping of surface geological features

Semantic mapping in 3D is fundamental to a wide range of geoscientific studies and applications, including geomorphology, hazard assessment, and environmental monitoring. However, automatically segmenting geological features from large-scale photogrammetric datasets remains a significant challenge. We present a methodology to address this gap. Using overlapping images collected over environments of interest, Structure-from-Motion (SfM) produces georeferenced point clouds and estimates camera poses. Existing large vision models, such as Segment Anything Model, segment objects in the images, generating pixel-segmentation associations. To produce pixel-point associations, we project the points back onto the camera image planes. As objects are independently segmented across multiple images with different perspectives, we develop a segmentation mosaicking algorithm to build probabilistic point-segmentation associations that combines the pixel-segmentation associations and pixel-point associations. Our methodology is validated using both synthetic data generated by Kubric and real-world UAV-SfM data. The implementation is designed to be compatible with existing SfM software, including Agisoft and OpenDroneMap, for photogrammetry mapping in geoscience studies. As a case study, we apply our method to the semantic mapping of precariously balanced rocks (PBRs), which provide upper-bound constraints on historical ground motion shaking intensity. To support object-level identification of PBRs, we additionally integrated Grounding DINO, enabling text-prompted segmentation of features of interest within UAV imagery. This case study demonstrates the effectiveness of our method in generating a 3D semantic map of PBRs, enabling spatial distribution of PBR fragility for earthquake hazard analysis.

Computers & Geosciences↗
USGS2016

Relations between rainfall–runoff-induced erosion and aeolian deposition at archaeological sites in a semi-arid dam-controlled river corridor

Process dynamics in fluvial-based dryland environments are highly complex with fluvial, aeolian, and alluvial processes all contributing to landscape change. When anthropogenic activities such as dam-building affect fluvial processes, the complexity in local response can be further increased by flood- and sediment-limiting flows. Understanding these complexities is key to predicting landscape behavior in drylands and has important scientific and management implications, including for studies related to paleoclimatology, landscape ecology evolution, and archaeological site context and preservation. Here we use multi-temporal LiDAR surveys, local weather data, and geomorphological observations to identify trends in site change throughout the 446-km-long semi-arid Colorado River corridor in Grand Canyon, Arizona, USA, where archaeological site degradation related to the effects of upstream dam operation is a concern. Using several site case studies, we show the range of landscape responses that might be expected from concomitant occurrence of dam-controlled fluvial sand bar deposition, aeolian sand transport, and rainfall-induced erosion. Empirical rainfall-erosion threshold analyses coupled with a numerical rainfall–runoff–soil erosion model indicate that infiltration-excess overland flow and gullying govern large-scale (centimeter- to decimeter-scale) landscape changes, but that aeolian deposition can in some cases mitigate gully erosion. Whereas threshold analyses identify the normalized rainfall intensity (defined as the ratio of rainfall intensity to hydraulic conductivity) as the primary factor governing hydrologic-driven erosion, assessment of false positives and false negatives in the dataset highlight topographic slope as the next most important parameter governing site response. Analysis of 4+ years of high resolution (four-minute) weather data and 75+ years of low resolution (daily) climate records indicates that dryland erosion is dependent on short-term, storm-driven rainfall intensity rather than cumulative rainfall, and that erosion can occur outside of wet seasons and even wet years. These results can apply to other similar semi-arid landscapes where process complexity may not be fully understood.

Arizona↗
USGS2006

Fertilizer-derived uranium and sulfur in rangeland soil and runoff: A case study in central Florida

Fertilizer applications to rangeland and pastures in central Florida have potential impact on the nutrient-sensitive ecosystems of Lake Okeechobee and the Northern Everglades. To investigate the effects of fertilizer applications, three soil profiles from variably managed and improved rangeland, and four samples of surface runoff from both fertilized and unfertilized pasture were collected. In addition to determining nutrient concentrations, isotopic analyses of uranium (U) and sulfur (S) were performed to provide isotopic evidence for U derived from historically applied phosphate (P)-bearing fertilizer ( 234 U 238U activity ratio =1.0 ?? 0.05), and Sderived from recently applied ammonium sulfate fertilizer(??34 S=3.5permil).The distribution and mobility of fertilizer-derived U in these samples is considered to be analogous to that of fertilizer-derived phosphate.Variations of U concentrations and 234 U/238 U activity ratios in soils indicate contribution of fertilizer-derived U in the upper portions of the fertilized soil (15-}34 percent of total U). The U isotope data for runoff from the fertilized field also are consistent with some contribution from fertilizer-derived U. Parallel investigations of S showed no consistent chemical or isotopic evidence for significant fertilizer-derived sulfate in rangeland soil or runoff. Relatively abundant and isotopically variable S present in the local environment hinders detection of fertilizer-derived sulfate. The results indicate a continuing slow-release of fertilizer-derived U and, by inference, P, to the P-sensitive ecosystem, and a relatively rapid release of sulfate of possible natural origin. ?? Springer 2006.

Water, Air, & Soil Pollution↗
USGS2024

Disease-smart climate adaptation for wildlife management and conservation

Climate change is a well-documented driver and threat multiplier of infectious disease in wildlife populations. However, wildlife disease management and climate-change adaptation have largely operated in isolation. To improve conservation outcomes, we consider the role of climate adaptation in initiating or exacerbating the transmission and spread of wildlife disease and the deleterious effects thereof, as illustrated through several case studies. We offer insights into best practices for disease-smart adaptation, including a checklist of key factors for assessing disease risks early in the climate adaptation process. By assessing risk, incorporating uncertainty, planning for change, and monitoring outcomes, natural resource managers and conservation practitioners can better prepare for and respond to wildlife disease threats in a changing climate.

Frontiers in Ecology and the Environment↗
USGS2012

Use of a storm water retention system for conservation of regionally endangered fishes

Maintaining aquatic biodiversity in urban or suburban areas can be problematic because urban landscapes can be nearly devoid of aquatic habitats other than engineered basins for storm water management. These areas are usually of questionable value for fish, but we examined a case study in which five regionally imperiled fish species were reintroduced into an artificial storm water detention pond and subsequently thrived. Although not a formal experiment, postintroduction survey data suggested that three of the five species maintained high population densities for 10 years after initial stocking, and two persisted in lower numbers. Success was likely due to a combination of unique design features and prior habitat preparation that resulted in clear water conditions that supported dense vegetation. Stocked fish persisted despite occasional bouts of low dissolved oxygen and increased chloride levels resulting from road salt application within the watershed. Transplanted fish served as a source population for both research and further reintroduction experiments. We suggest that, for some fish species, habitat preservation has a middle ground between natural habitats and completely artificial environments that require constant husbandry and that storm water systems could be used to create engineered sanctuaries within the human landscape that have many potential benefits for both humans and fish.

Fisheries↗
USGS2014

Cross-scale interactions: Quantifying multi-scaled cause–effect relationships in macrosystems

Ecologists are increasingly discovering that ecological processes are made up of components that are multi-scaled in space and time. Some of the most complex of these processes are cross-scale interactions (CSIs), which occur when components interact across scales. When undetected, such interactions may cause errors in extrapolation from one region to another. CSIs, particularly those that include a regional scaled component, have not been systematically investigated or even reported because of the challenges of acquiring data at sufficiently broad spatial extents. We present an approach for quantifying CSIs and apply it to a case study investigating one such interaction, between local and regional scaled land-use drivers of lake phosphorus. Ultimately, our approach for investigating CSIs can serve as a basis for efforts to understand a wide variety of multi-scaled problems such as climate change, land-use/land-cover change, and invasive species.

Frontiers in Ecology and the Environment↗
USGS1972

Documentation and environment of the Apollo 16 samples a preliminary report

This catalog is a working document that shows the locations from which samples were collected during the Apollo 16 mission, and that provides a descriptive geologic context for each sample. It is a compilation of notes from work in progress, and supersedes an earlier report prepared by the Apollo Lunar Geology Investigation Team. The information in this report was obtained from the Air-to-Ground transcript from the astronaut crew, from lunar surface television, from 60 mm Hasselblad camera photographs, and from available LRL "mugshot" photographs of the samples. The sample descriptions are based on these sources of data, and do not reflect the more detailed examination that is presently underway in the LRL. The report is still a preliminary study due to the short time available to review the rather copious data. The rocks have yet to be examined under collimated light and checked against the lunar surface photographs to make identification certain in all cases. The original orientation of the samples will, in time, as ascertained and photographically documented, and will be the subject of a final report on sample documentation. The reader will find inconsistencies in the format throughout the report (and probably some errors). But we believe that it is more important to disseminate these data early rather than to delay with detailed editing sufficient to completely standardize the format.

Open-File Report↗
USGS2015

Remote sensing systems – Platforms and sensors: Aerial, satellites, UAVs, optical, radar, and LiDAR

The American Society of Photogrammetry and Remote Sensing defined remote sensing as the measurement or acquisition of information of some property of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object or phenomenon under study (Colwell et al., 1983). Environmental Systems Research Institute (ESRI) in its geographic information system (GIS) dictionary defines remote sensing as “collecting and interpreting information about the environment and the surface of the earth from a distance, primarily by sensing radiation that is naturally emitted or reflected by the earth’s surface or from the atmosphere, or by sending signals transmitted from a device and reflected back to it (ESRI, 2014).” The usual source of passive remote sensing data is the measurement of reflected or transmitted electromagnetic radiation (EMR) from the sun across the electromagnetic spectrum (EMS); this can also include acoustic or sound energy, gravity, or the magnetic field from or of the objects under consideration. In this context, the simple act of reading this text is considered remote sensing. In this case, the eye acts as a sensor and senses the light reflected from the object to obtain information about the object. It is the same technology used by a handheld camera to take a photograph of a person or a distant scenic view. Active remote sensing, however, involves sending a pulse of energy and then measuring the returned energy through a sensor (e.g., Radio Detection and Ranging [RADAR], Light Detection and Ranging [LiDAR]). Thermal sensors measure emitted energy by different objects. Thus, in general, passive remote sensing involves the measurement of solar energy reflected from the Earth’s surface, while active remote sensing involves synthetic (man-made) energy pulsed at the environment and the return signals are measured and recorded.

Book chapter↗
USGS2012

State of the Earth’s cryosphere at the beginning of the 21st century: Glaciers, global snow cover, floating ice, and permafrost and periglacial environments

This chapter is the tenth in a series of 11 book-length chapters, collectively referred to as “this volume,” in the series U.S. Geological Survey Professional Paper 1386, Satellite Image Atlas of Glaciers of the World. In the other 10 chapters, each of which concerns a specific glacierized region of Earth, the authors used remotely sensed images, primarily from the Landsat 1, 2, and 3 series of spacecraft, in order to analyze that glacierized region and to monitor changes in its glaciers. Landsat images, acquired primarily during the period 1972 through 1981, were used by an international team of glaciologists and other scientists to study the various glacierized regions and (or) to discuss related glaciological topics. In each glacierized region, the present distribution of glaciers within its geographic area is compared, wherever possible, with historical information about their past areal extent. The atlas provides an accurate regional inventory of the areal extent of glacier ice on our planet during the 1970s as part of an expanding international scientific effort to measure global environmental change on the Earth’s surface. However, this chapter differs from the other 10 in its discussion of observed changes in all four elements of the Earth’s cryosphere (glaciers, snow cover, floating ice, and permafrost) in the context of documented changes in all components of the Earth System. Human impact on the planet at the beginning of the 21st century is pervasive. The focus of Chapter A is on changes in the cryosphere and the importance of long-term monitoring by a variety of sensors carried on Earth-orbiting satellites or by a ground-based network of observatories in the case of permafrost. The chapter consists of five parts. The first part provides an introduction to the Earth System, including the interrelationships of the geosphere (cryosphere, hydrosphere, lithosphere, and atmosphere), the biosphere, climate processes, biogeochemical cycles, and the critically important hydrologic cycle, in which glacier ice is the second largest reservoir of water after the oceans. The second part assesses the state of glaciers in all of the glacierized regions of the planet, primarily as drawn in the other 10 chapters. It includes sections on ice cores and the climate record they contain, volumetric changes in glaciers, harnessing spaceborne sensors to measure changes in glaciers, and related topics. The third part summarizes trends in global snow cover. The fourth part summarizes long-term changes in area and thickness of floating ice, including polar sea ice and freshwater (lake and river) ice. The fifth part assesses the loss of permafrost and changes in periglacial environments at high latitudes and high altitudes.

Professional Paper↗
USGS2001

Use of 17 O/ 16 O to trace atmospherically-deposited sulfate in surface waters: A case study in alpine watersheds in the Rocky Mountains

Building on the discovery of excess 17 O in atmospheric sulfate by Lee et al. (2001), we have carried out a case study to determine whether 17 O might provide a new tool for quantifying the impact of atmospheric deposition on surface-water sulfate loads. In Rocky Mountain alpine regions, excess 17 O was found to be characteristics of atmospheric sulfate deposited in snow. Excess 17 O was also evident in stream sulfate in one of two high-elevation watersheds where analyses were made. Isotope mass balance calculations gave surprizingly low atmospheric contributions to stream sulfate suggesting that (1) despite abundant outcrop and sparse soil in these areas, significant sulfate may be taken up and released by soil microbes before being exported in streams, and (2) surface waters can carry multiple non-atmospheric sulfate types, some possibly anthropogenic. Measurements of 17 O may prove very useful in studies of sulfate behavior in a variety of surficial environments.

Geophysical Research Letters↗