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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 91 records · Page 5Linked to original sources
USGS2006

A landscape perspective of the stream corridor invasion and habitat characteristics of an exotic (Dioscorea oppositifolia) in a pristine watershed in Illinois

The spatial distribution of exotics across riparian landscapes is not uniform, and research elaborating the environmental constraints and dispersal behavior that underlie these patterns of distribution is warranted. This study examined the spatial distribution, growth patterns, and habitat constraints of populations of the invasive Dioscorea oppositifolia in a forested stream corridor of a tributary of Drury Creek in Giant City State Park, IL. The distribution of D. oppositifolia was determined at the watershed scale mainly by floodplain structure and connectivity. Populations of D. oppositifolia were confined to the floodplain, with overbank flooding from the stream. Dioscorea oppositifolia probably originates in disturbed areas upstream of natural corridors, and subsequently, the species disperses downstream into pristine canyons or ravines via bulbils dispersing in the water. In Giant City State Park, populations of D. oppositifolia were distributed on the floodplain across broad gradients of soil texture, light, slope, and potential radiation. The study also examined the longevity of bulbils in various micro-environments to illuminate strategies for the management of the species in invaded watersheds. After 1 year, the highest percentages of bulbils were viable under leaves, and much lower percentages were viable over leaves, in soil, and in the creek (76.0±6.8, 21.2±9.6, 21.6±3.6, and 5.2±5.2%), respectively. This study suggests that management procedures that reduce leaf litter on the forest floor (e.g., prescribed burning) could reduce the number of bulbils of D. oppositifolia stored in the watershed.

Illinois↗
USGS2021

Michigan and Landsat

Water means a lot to Michigan, often called the Great Lakes State. The name “Michigan” comes from an Ojibwe word meaning large, or great, water or lake. As the only State touching four of the five Great Lakes—Michigan, Superior, Huron, and Erie—it claims the longest freshwater coastline in the United States. Yet Michigan is not just about water—forests, agriculture, mines, cities, and even sand dunes stretch across the State’s landscape. Much of what happens on the land does connect in some way with Michigan’s inland and coastal waters. Michigan relies on a healthy environment to support its residents, abundant tourists, and diverse species of wildlife that call the State and its surrounding waters home. From hundreds of miles above, Landsat satellites provide a clearer picture of the connections among land, water, and the people and wildlife that inhabit the State.

Michigan↗
USGS1996

Geohydrology of the shallow aquifers in the Denver metropolitan area, Colorado

The Denver metropolitan area is underlain by shallow layers of water-bearing sediments (aquifers) consisting of unconsolidated gravel, sand, silt, and clay. The depth to water in these aquifers is less than 20 feet in much of the area, and the aquifers provide a ready source of water to numerous shallow, small-capacity wells. The shallow depth to water also makes the aquifers susceptible to contamination from the land surface. Water percolating downward from residential, commercial, and industrial property, spills of hazardous materials, and leaks from underground storage tanks and pipelines can cause contaminants to enter the shallow aquifers. Wet basements, unstable foundation materials, and waterlogged soils also are common in areas of very shallow ground water. Knowledge of the extent, thickness, and water-table altitude of the shallow aquifers is incomplete. This, coupled with the complexity of development in this large metropolitan area, makes effective use, management, and protection of these aquifers extremely difficult. Mapping of the geologic and hydrologic characteristics of these aquifers would provide the general public and technical users with information needed to better use, manage, and protect this water resource. A study to map the geohydrology of shallow aquifers in the Denver metropolitan area was begun in 1994. The work was undertaken by the U.S. Geological Survey in cooperation with the U.S. Army-Rocky Mountain Arsenal, U.S. Department of Energy-Rocky Flats Field Office, Colorado Department of Public Health and Environment, Colorado Department of Natural Resources-State Engineers Office, Denver Water Department, Littleton-Englewood Wastewater Treatment Plant, East Cherry Creek Valley Water and Sanitation District, Metro Wastewater Reclamation District, Willows Water District, and the cities of Aurora, Lakewood, and Thornton. This report presents the results of a systematic mapping of the extent, thickness, and water-table altitude of the shallow aquifers in a 700-square-mile part of the greater Denver metropolitan area (fig. 1). The five sheets in this report (figs. 2-7) show (1) the thickness and extent of the unconsolidated sediments that overlie bedrock formations in the area, (2) the altitude and configuration of the buried bedrock surface, (3) the altitude of the water table and direction of ground-water movement, (4) the saturated thickness of the shallow aquifers, and (5) the depth to the water table in the shallow aquifers. The maps primarily are intended to indicate the general trends in altitude and thickness of the aquifers and are not intended to define conditions at specific sites.

Hydrologic Atlas↗
USGS2026

Urbanization alters riverine fluorescent dissolved organic matter characteristics in a forested city – metropolitan Atlanta, Georgia (USA)

Streams and rivers in urban watersheds are predicted to export more bioreactive, autochthonous dissolved organic matter (DOM) relative to forested watersheds. However, the spatial and temporal variations of DOM quality in forested urban watersheds remain uncertain, and their relationships with socioeconomic conditions, biological characteristics, and the built environment are understudied. We measured optical properties of fluorescent DOM (FDOM) in 93 streams spanning a gradient of land-use and land cover during four seasons in metropolitan Atlanta, Georgia, USA. Streamwater FDOM was dominated by humic substances from anthropogenic (41%) and terrestrial origin (41.5%). Impervious surface cover was the strongest predictor, which was positively correlated with anthropogenically- and autochthonously-derived FDOM. Overwater canopy cover was positively associated with autochthonous FDOM, and housing age increased diagenetic FDOM. FDOM was more proteinaceous during low-flow conditions (fall, winter), and more allochthonous humic-like FDOM was detected during periods of higher flows (spring, summer). Interestingly, wastewater-related FDOM proxies were highest during low flows, suggesting that sewer exfiltration is a pervasive source and is diluted by other inputs during high flows. Overall, seasonal patterns in FDOM quality were associated with changes in hydrology, and FDOM was primarily humic throughout the year, a pattern likely driven by ubiquitous forest canopy cover. Our results highlight the importance of urban forests in mediating aquatic carbon cycling and provide a template for future studies that integrate sociodemographic and infrastructure information into studies of watershed biogeochemistry, especially in regions undergoing rapid, intense, and localized urban development.

Georgia↗
USGS2009

Report from Ground Zero: How geoscientists aid in the aftermath of environmental disasters

People around the world remember when they first learned of the attacks on New York City’s World Trade Center towers on Sept. 11, 2001. For me, the memories are vivid — my feelings of shock, horror and sadness were similarly etched on the faces of all the attendees of a mining and the environment workshop in Buenos Aires, Argentina, where I was speaking. At that time, I had no idea that our small research group at the U.S. Geological Survey in Denver, Colo., would soon be called upon to help public officials understand the potential health and environmental implications of the disaster and the ensuing rescue, recovery and cleanup efforts.

Earth Magazine↗
USGS1979

Upper Cenozoic deposits of the central Delmarva Peninsula, Maryland and Delaware

The surface and shallow subsurface sediments of the lower Delmarva Peninsula include beds ranging in age from Miocene to Holocene. The oldest beds appear to be typical shelf deposits of the Chesapeake Group (Calvert-Choptank age). These marine units are overlain by deltaic deposits, which range from fluviatile facies in the north (Pensauken Formation) to marginal marine and marine beds in the south ('Yorktown(?) and Cohansey(?)' Formations as used by Rasmussen and Slaughter in 1955). This large deltaic mass underlies most of the Delmarva Peninsula. Fossil age determinations supplemented by some radiometric dates indicate the delta to be largely late Miocene in age. The nonmarine facies of the delta, the Pensauken Formation, previously was considered to be Pleistocene in age. The late Miocene delta and possibly the Yorktown Formation (lower to middle Pliocene) are overlain by a feldspathic sand, the Beaverdam, which is at least in part marginal marine. Microflora recovered from this formation include species no longer indigenous to the Delmarva region ('exotics'). On the basis of existing information, microfloral assemblages containing 'exotics' are pre-Pleistocene in age. The Beaverdam therefore is pre-Pleistocene in age, probably late Pliocene. A highly dissected and weathered unit, the Walston Silt, caps the uplands of the central Delmarva Peninsula, where it overlies the Beaverdam. The Walston has a microflora containing 'exotics' and therefore is considered to be the youngest Tertiary unit (uppermost Pliocene) in this area. Sediments forming a barrier-back-barrier sequence fringe most of the southern Maryland-Delaware part of the Delmarva Peninsula and are found at altitudes of as much as 15 m (50 ft) above sea level. This sequence, the Omar Formation, is Sangamon in age and has been dated radiometrically as 60,000 to about 100,000 years old. The microflora in these beds contains no 'exotics,' and the assemblage suggests a warm-temperate environment. The Omar represents the highest stand of the Quaternary seas in the Delmarva region. The Ironshire and Kent Island Formations overlie or cut into the Omar Formation and are probably late Sangamon and middle Wisconsin, respectively, in age. Near Ocean City, the Ironshire forms a seaward-facing scarp with a toe nearly 4.5 m (15 ft) above sea level. A warm-temperate microfloral assemblage from the fluviatile-estuarine facies of the Ironshire Formation in the Delaware Bay region suggests that the formation is interglacial, probably late Sangamon in age. The Ironshire and Omar Formations are overlain unconformably by the Sinepuxent Formation. The top of this marine unit is slightly above present sea level and has been dated by radiocarbon as about 30,000 years old or middle Wisconsin. The microflora from this formation is a cold to cool-temperate assemblage (high proportion of spruce pollen). The outer fringes of the Delmarva Peninsula are being overlapped by deposits of a Holocene marine transgression.

Professional Paper↗
USGS2017

Are exposure predictions, used for the prioritization of pharmaceuticals in the environment, fit for purpose?

Prioritization methodologies are often used for identifying those pharmaceuticals that pose the greatest risk to the natural environment and to focus laboratory testing or environmental monitoring toward pharmaceuticals of greatest concern. Risk-based prioritization approaches, employing models to derive exposure concentrations, are commonly used, but the reliability of these models is unclear. The present study evaluated the accuracy of exposure models commonly used for pharmaceutical prioritization. Targeted monitoring was conducted for 95 pharmaceuticals in the Rivers Foss and Ouse in the City of York (UK). Predicted environmental concentration (PEC) ranges were estimated based on localized prescription, hydrological data, reported metabolism, and wastewater treatment plant (WWTP) removal rates, and were compared with measured environmental concentrations (MECs). For the River Foss, PECs, obtained using highest metabolism and lowest WWTP removal, were similar to MECs. In contrast, this trend was not observed for the River Ouse, possibly because of pharmaceutical inputs unaccounted for by our modeling. Pharmaceuticals were ranked by risk based on either MECs or PECs. With 2 exceptions (dextromethorphan and diphenhydramine), risk ranking based on both MECs and PECs produced similar results in the River Foss. Overall, these findings indicate that PECs may well be appropriate for prioritization of pharmaceuticals in the environment when robust and local data on the system of interest are available and reflective of most source inputs.

City of York↗
USGS2014

Limnogeology, news in brief

We've invited Michael R. Rosen, water quality specialist within the USGS Water Science Field Team in Carson City and Elizabeth Gierlowski-Kordesch, professor of geology at Ohio University, to take a look at the intriguing new developments that are emerging in limnogeologic studies. These studies are increasing our understanding of how climate and movements of the Earth's surface influence terrestrial environments, as well as how contaminants are distributed and retained in the environment. They present a selection of recent significant research on sediments, rock, and biota that have been preserved in modern and ancient lake basins.

Environmental Earth Sciences↗
USGS2017

Mechanisms associated with an advance in the timing of seasonal reproduction in an urban songbird

The colonization of urban environments by animals is often accompanied by earlier breeding and associated changes in seasonal schedules. Accelerated timing of seasonal reproduction in derived urban populations is a potential cause of evolutionary divergence from ancestral populations if differences in physiological processes that regulate reproductive timing become fixed over time. We compared reproductive development in free-living and captive male dark-eyed juncos deriving from a population that recently colonized a city (~35 years) and ceased migrating to that of conspecifics that live in sympatry with the urban population during winter and spring but migrate elsewhere to breed. We predicted that the earlier breeding sedentary urban birds would exhibit accelerated reproductive development in the spring along the hypothalamic-pituitary-gonadal (HPG) axis as compared to migrants. We found that free-living sedentary urban and migrant juncos differed at the level of the pituitary when measured as baseline luteinizing hormone (LH) levels, but not in increased LH when challenged with Gonadotropin-Releasing Hormone (GnRH). Among captives held in a common garden, and at the level of the gonad, we found that sedentary urban birds produced more testosterone in response to GnRH than migrants living in the same common environment, suggesting greater gonadal sensitivity in the derived urban population. Greater gonadal sensitivity could arise from greater upstream activation by LH or FSH or from reduced suppression of gonadal development by the adrenal axis. We compared abundance of gonadal transcripts for LH receptor (LHR), follicle stimulating hormone receptor (FSHR), glucocorticoid receptor (GR), and mineralocorticoid receptor (MR) in the common-garden, predicting either more abundant transcripts for LHR and FSHR or fewer transcripts for GR and MR in the earlier breeding sedentary urban breeders, as compared to the migrants. We found no difference in the expression of these genes. Together these data suggest that advanced timing of reproduction in a recently derived urban population is facilitated by earlier increase in upstream baseline activity of the HPG and earlier release from gonadal suppression by yet-to-be-discovered mechanisms. Evolutionarily, our results suggest that potential for gene flow between seasonally sympatric populations may be limited due to urban-induced advances in the timing of reproduction and resulting allochrony with ancestral forms.

California↗
USGS2020

Stratigraphic units of shallow unconsolidated deposits in Deadwood, South Dakota, delineated by real-time kinematic surveys

The City of Deadwood, South Dakota, has been working on a new archeological investigation in preparation for economic growth and expansion within the city limits, through the Deadwood Historic Preservation Office. During the excavation process, buried artifacts and historical features from the late 1800s have been uncovered. The stratigraphy of shallow unconsolidated deposits in the city of Deadwood, S. Dak., was surveyed on January 29, 2020, using real-time kinematic survey methods and described to identify variations in geologic material, thickness, and depth from the land surface in support of archeological studies by the city. The findings of the study will provide city managers and the public with reliable and impartial information for their use by advancing field or analytical methodology and understanding of hydrologic processes in the study area. The primary excavation site was surveyed, and stratigraphic units were delineated from changes in material properties or depositional environment. The primary excavation site consisted of nine stratigraphic units; however, some units were not consistent along the length of the excavation and pinched out along the cross section. Survey data points also were collected for artifacts and other sites of interest. The shallow surficial geology in the study area was affected by human construction, fires, and flooding.

South Dakota↗
USGS1969

Geology and regional metamorphism of some high-grade cordierite gneisses, Front Range, Colorado

Cordierite is common in regional metamorphic gneisses of Precambrian age in the central part of the Front Range. It occurs in discontinuous stratigraphic units that are structurally a minor component, except locally, of the thick succession of biotite gneisses that comprise the widespread Idaho Springs Formation. The rocks have mineral assemblages, that are characteristic of the sillimanite grade of metamorphism. The cordierite occurs in three principal rock types: (1) potassic feldspar-bearing cordierite-garnet-sillimanite-biotite gneiss, (2) cordierite-biotite gneiss, and (3) cordierite-gedrite-biotite gneiss; each type contains several characteristic mineral assemblages. The rock types are gradational and overlap in areal distribution, and mainly owe their diversity in mineralogy to differences in bulk chemical composition. The field relations are consistent with an interpretation that the diverse cordierite rocks were derived from original sedimentary rocks, largely pelitic sediments. The potassic feldspar-bearing cordierite-garnet gneisses were formed from shales that contained more MgO and FeO than the more abundant sedimentary facies that yielded sillimanitic biotite gneisses. Cordierite-gedrite-biotite gneisses contain much aluminum, iron, and magnesium and little sodium and potassium as compared to the other biotite gneisses; they have an extremely low content of minor elements. Although their chemical compositions are unlike those of known modern sediments, the cordierite-gedrite gneisses are considered also to have been derived from sedimentary rocks. The physical properties and chemical compositions of the mineral phases vary somewhat from one rock type to another. Biotite varies systematically in composition, and the changes are closely related to rock type and thus to bulk composition; the MgO/FeO ratios range from 1.7 in the more mafic cordierite-gedrite rocks to 0.49 in potassic feldspar-bearing cordierite-garnet gneisses. Cordierite is magnesium-rich and intermediate in the range of composition of all analyzed cordierites (Leake, 1960); its MgO/FeO ratio is higher in the gedrite-bearing gneisses than in the potassic feldspar-bearing gneisses. The garnets consist dominantly of the almandine and pyrope molecules, and range from 64 to 75 percent almandine and from 14 to 27 pyrope. These crystals are zoned; their rims are slightly more ferrous and less magnesian than their cores. Both monoclinic and triclinic alkali feldspars coexist in the potassic feldspar-bearing cordierite-garnet gneisses. The potassic feldspars contain from 18 to 27 weight percent NaAlSi 3 O 8 . Plagioclase (oligoclase-andesine) is uncommon in the rocks. Gedrite has an MgO/FeO ratio ranging from 1 to 1.2. Associated minor minerals include iron oxides, andalusite, spinel and its alteration product högbomite, and corundum. The mineral assemblages can be correlated imperfectly with episodes of deformation and metamorphism. Relict staurolite and associated garnet occur locally as remnants of an assemblage formed early in regional metamorphism, presumably early in the first period of deformation. The dominant assemblage biotite-cordierite-garnet-magnetite-plagioclase-potassic feldspar-quartz-sillimanite and associated assemblages having fewer phases, were formed during period one and period two deformations, the principal episodes of regional dynamothermal metamorphism in the central part of the Front Range. A minor assemblage andalusite-biotite-magnetite-plagioclase-quartz was formed later, possibly coincident with a third period of deformation, largely cataclastic in effects, which was more local than the earlier deformations and metamorphism. Phase equilibria studies of the assemblage biotite-cordierite-garnet-magnetite-plagioclase-potassic feldspar-quartz-sillimanite and associated assemblages are interpreted to indicate that the cordierite assemblages approach a state of chemical equilibrium. The scatter of points in a distribution diagram can be interpreted in terms of at least two sets of equilibrium conditions that prevailed during the major plastic deformations. Other discrepancies indicating departure from a homogeneous equilibrium can be explained as a result of mosaic equilibrium involving limited diffusion of iron and magnesium for short distances. The mineral assemblages and the compositions of the ferromagnesian minerals in the cordierite rocks of this region are dependent primarily on the bulk composition of the rocks and variations in the mineral species that comprise the rocks and, to a lesser degree, on the grade of metamorphism. Biotite and cordierite are markedly more magnesian in the more mafic cordierite-gedrite-biotite gneiss than in the potassic feldspar-bearing cordierite-garnet-sillimanite-biotite gneiss. Associated microcline gneiss and biotite-sillimanite gneiss that contains muscovite as a primary stable mineral provides a means to define the metamorphic grade in the area of study. It is concluded from analyses of the assemblages with respect to theoretical phase relations in the system SiO 2 -Al 2 O 3 -Na 2 O-K 2 O-H 2 O that at least some of the rocks in the Central City-Nederland area are above the sillimanite-potassic feldspar isograd as defined by Evans and Guidotti (1966). In rocks of appropriate composition, muscovite is a stable phase in assemblages containing potassic feldspar and sillimanite. The cordierite assemblages and associated rocks are inferred to have formed in an environment having a load pressure of 3–5 kilobars (fluid pressure equaled load pressure) and a temperature somewhat in excess of 620° C.

Colorado↗
USGS2022

Connecticut and Landsat

Connecticut, the third-smallest State by land area, is the fourth most densely populated in the United States. Connecticut’s tightly packed cities serve as international hubs for the finance and insurance industries. These same urban enclaves host highly regarded institutions of higher learning, such as Yale, the University of Connecticut, and Quinnipiac and Wesleyan Universities. Yet Connecticut has surprisingly varied natural features. Its residents are never far from pristine environments that teem with wildlife and convey the sounds, scents, and scenery of the natural world. The Connecticut River, the longest in New England at 407 miles, cuts through the State’s center and drains into Long Island Sound, as do the Thames and Housatonic Rivers. Together, these rivers form an estuary spawning ground for hundreds of freshwater and saltwater aquatic species. North and east of the coastal lowlands that hug the estuary are the highlands of the Southern Taconic Range and the Berkshires. North and west of the coastline, smaller rivers and valleys weave through densely forested landscapes dotted with State parks and scenic lakes. Imagery from the U.S. Geological Survey Landsat archive, a trusted public resource with more than 50 years of worldwide Earth observations, provides a powerful tool for analyzing the interplay of human habitation and natural landscapes in Connecticut. Landsat data also offer land managers a critical information source for managing damage from invasive species and monitoring the local landscape effects of changing environmental conditions .

Connecticut↗
USGS1997

Stratigraphy, sedimentology, and volume of sediments behind a dam relic on the Muskegon River, Big Rapids, Michigan

The proposed removal of the remnants of a hydroelectric dam in the Muskegon River at Big Rapids, Michigan, will potentially affect flow of the river at the city's water intake system. Fifteen boreholes were augered in bottom sediments in the river just upstream from the dam relic, and streambottom profiles were made using ground-penetrating radar. Data from boreholes show that sediments captured by the dam foundation were deposited in two distinctly different sedimentary environments. Sediments that overlie the pre-dam channel surface consist of lacustrine clay, wood chips, silt, and sand. These lacustrine sediments are interbedded in a cyclical fashion, and they were deposited under low flow to stagnant water conditions during 1916-66, when a 17-foot-tall hydroelectric dam was in place. Demolition of the upper 13 feet of this dam in 1966 resulted in erosion of most of the lacustrine sediments, and subsequent deposition of coarser alluvium in the impoundment behind the remaining dam foundation. Lacustrine sediments are present in the active part of the stream channel and extend from the dam foundation to about 1,300 feet upstream. The composite thickness of lacustrine sediments and overlying coarser alluvium was determined from sediment cores collected from the boreholes. The volume of these sediments is estimated to be about 19,000 cubic yards.

Michigan↗
USGS2009

Longitudinal patterns in flathead catfish relative abundance and length at age within a large river: Effects of an urban gradient

We investigated the spatial variation of flathead catfish (Pylodictis olivaris) relative abundance and growth in the 274 km long Kansas River to determine if population dynamics of catfish are related to urbanization. Electrofishing was conducted at 462 random sites throughout the river in summer, 2005-2006 to collect fish. Relative abundance of age 1 fish (???200mm), subadult (>200-400mm) and adult fish (>400 mm) ranged from 0.34 to 14.67 fish h -1 , mean length at age 1 was 165 (range: 128-195) mm total length (TL) and mean length at age 3 was 376 mm TL (range: 293-419mm TL). The proportion of land use within 200 m of the river edge was between 0 and 0.54 urban. River reaches with high relative abundance of age 1 flathead catfish had high relative abundance of subadult and adult catfish. River reaches with fast flathead catfish growth to age 1 had fast growth to age 3. High urban land use and riprap in the riparian area were evident in river reaches near the heavily populated Kansas City and Topeka, Kansas, USA. Reaches with increased number of log jams and islands had decreased riparian agriculture. Areas of low urbanization had faster flathead catfish growth (r = 0.67, p = 0.005). Relative abundance of flathead catfish was higher in more agricultural areas (r = -0.57, p = 0.02). Changes in land use in riverine environments may alter population dynamics of a fish species within a river. Spatial differences in population dynamics need to be considered when evaluating riverine fish populations. Published in 2008 by John Wiley & Sons Ltd.

River Research and Applications↗
USGS2025

High-resolution multi-pollutant mapping in Denver, Colorado

Characterizing traffic-related air pollutants (TRAPs), which significantly impact health, and greenhouse gases (GHGs) can be challenging in urban environments. Mobile monitoring has the potential to capture the spatial distribution of these pollutants. We present results from a campaign using the Denver Mobile Monitoring Laboratory (DMML) in the summer of 2023 when we measured ultrafine particles (UFPs), black carbon (BC), ozone (O 3 ), methane (CH 4 ) , and carbon dioxide (CO 2 ) concentrations in Denver, CO. Despite our campaign being brief, we obtained several interesting results. We observed elevated UFP and BC concentrations on major roads. In contrast, O 3 concentrations were higher on neighborhood streets and roads and in the industrial neighborhood of Commerce City. We consistently observed elevated CH 4 concentrations (>2.5 ppm) on highway I-70, suggesting the presence of a previously unknown major source of CH 4 . The CH 4 concentrations measured in our campaign did not align with those from an overlapping aerial campaign, suggesting that mobile monitoring is crucial to capture important, potentially intermittent CH 4 hotspots in cities. We evaluated if trees mitigated pollution concentrations, as planting trees is a key policy initiative of the city of Denver. We observed significant negative associations between tree canopy coverage and UFPs, BC, and CH 4 , and a positive association with O 3 when using linear mixed-effects regression models. Our work highlights the importance of investigating the role of tree canopy coverage to mitigate TRAPs.

Colorado↗
USGS2004

Urban growth in American cities : glimpses of U.S. urbanization

The Earth's surface is changing rapidly. Changes are local, regional, national, and even global in scope. Some changes have natural causes, such as earthquakes or drought. Other changes, such as urban expansion, agricultural intensification, resource extraction, and water resources development, are examples of human-induced change that have significant impact upon people, the economy, and resources. The consequences that result from these changes are often dramatic and widespread (Buchanan, Acevedo, and Zirbes, 2002) It is the role of the U.S. Geological Survey (USGS) to provide useful and relevant scientific information both to the agencies within the Department of the Interior and to the Nation in general. In an effort to comply with this task, USGS scientists are assessing the status of, and the trends in, the Nation's land surface. This assessment provides useful information for regional and national land use decisionmaking. This knowledge can be used to deal with issues of significance to the Nation, such as quality-of-life, ecology of urban environments, ecosystem health, ecological integrity, water quality and quantity concerns, resource availability, vulnerability to natural hazards, safeguards to human health, air and land quality, and accessibility to scientific information. Results of these assessments can also be analyzed to reveal rates and trends in land use change. Results from urban growth studies provide a firm foundation for continuing research that explores the consequences of human modification of the landscape. The USGS seeks to illustrate and explain the spatial history of urban growth and corresponding land use change. Scientists are studying urban environments from a regional perspective and a time scale of decades to measure the changes that have occurred in order to help understand the impact of anticipated changes in the future. Within this booklet are pairs of images of selected urbanized regions from across the Nation. These image pairs illustrate the transformation that these areas have undergone over two decades. Specifically, they depict changes in the extent of urban land. Each change pair is composed of one image from the 1970s and one image from the 1990s. Accompanying each image pair is a brief historical geography of factors that helped facilitate major changes that have occurred since the founding of the main city and the consequences and challenges of regional urban growth. The goal of this publication is to provide an illustration of urban change that is easily understood by a broad audience. The images used throughout this booklet were generated from land cover data developed by the USGS. The data sources include the Geographic Information Retrieval and Analysis System (GIRAS) for the 1970s images and the National Land Cover Dataset (NLCD) for the 1990s images. GIRAS digital maps are based on photointerpretations completed in the mid-1970s. The NLCD is a land cover dataset for the conterminous United States based on 1992 Landsat thematic mapper (TM) satellite imagery and supplemental data (fig. 1a and fig. 1b). The USGS distributes both of these land use and land cover digital datasets. The images were developed by using a geographic information system (GIS). The GIRAS and NLCD datasets were used to identify urban land within each region. In the final images all urban areas are shown in red. A shaded-relief map of each region was used to display the topographic context of the red polygon coverage. For all of these images, urban land is defined as areas transformed into a built-up environment for human use. It includes residential areas, commercial and industrial developments, transportation features, and institutions.

Circular↗
USGS2018

Temporal and spatial variation in pharmaceutical concentrations in an urban river system

Many studies have quantified pharmaceuticals in the environment, few however, have incorporated detailed temporal and spatial variability due to associated costs in terms of time and materials. Here, we target 33 physico-chemically diverse pharmaceuticals in a spatiotemporal exposure study into the occurrence of pharmaceuticals in the wastewater system and the Rivers Ouse and Foss (two diverse river systems) in the city of York, UK. Removal rates in two of the WWTPs sampled (a conventional activated sludge (CAS) and trickling filter plant) ranged from not eliminated (carbamazepine) to >99% (paracetamol). Data comparisons indicate that pharmaceutical exposures in river systems are highly variable regionally, in part due to variability in prescribing practices, hydrology, wastewater management, and urbanisation and that select annual median pharmaceutical concentrations observed in this study were higher than those previously observed in the European Union and Asia thus far. Significant spatial variability was found between all sites in both river systems, while seasonal variability was significant for 86% and 50% of compounds in the River Foss and Ouse, respectively. Seasonal variations in flow, in-stream attenuation, usage and septic effluent releases are suspected drivers behind some of the observed temporal exposure variability. When the data were used to evaluate a simple environmental exposure model for pharmaceuticals, mean ratios of predicted environmental concentrations (PECs), obtained using the model, to measured environmental concentrations (MECs) were 0.51 and 0.04 for the River Foss and River Ouse, respectively. Such PEC/MEC ratios indicate that the model underestimates actual concentrations in both river systems, but to a much greater extent in the larger River Ouse.

River Foss, River Ouse↗
USGS1979

Analysis of borehole geophysical information across a uranium deposit in the Jackson Group, Karnes County, Texas

Borehole geophysical studies across a uranium deposit in the Jackson Group, South Texas, show the three geochemical environments often associated with uranium roll-type deposits: an altered (oxidized) zone, an ore zone, and an unaltered (reduced) zone. Mineralogic analysis of the total sulfides contained in the drill core shows only slight changes in the total sulfide content among the three geochemical regimes. However, induced polarization measurements on the core samples indicate that samples obtained from the reduced side of the ore zone are more electrically polarizable than those from the oxidized side of the ore zone, and therefore probably contain more pyrite. Analysis of the clay-size fraction in core samples indicates that montmorillonite is the dominant clay mineral. High resistivity values within the ore zone indicate the presence of calcite cement concentrations that are higher than those seen outside of the ore zone. Between-hole resistivity and induced polarization measurements show the presence of an extensive zone of calcite cement within the ore zone, and electrical polarizable material (such as pyrite) within and on the reduced side of the ore zone. A quantitative analysis of the between-hole resistivity data, using a layered-earth model, and a qualitative analysis of the between-hole induced polarization measurements showed that mineralogic variations among the three geochemical environments were more pronounced than were indicated by the geophysical and geologic well logs. Uranium exploration in the South Texas Coastal Plain area has focused chiefly in three geologic units: the Oakville Sandstone, the Catahoula Tuff, and the Jackson Group. The Oakville Sandstone and the Catahoula Tuff are of Miocene age, and the Jackson Group is of Eocene age (Eargle and others, 1971). Most of the uranium mineralization in these formations is low grade (often less than 0.02 percent U3O8) and occurs in shallow deposits that are found by concentrated exploratory drilling programs. The sporadic occurrence of these deposits makes it desirable to develop borehole geophysical techniques that will help to define the depositional environments of the uranium ore, which is characterized by geochemical changes near the uranium deposits. Geochemical changes are accompanied by changes in the physical characteristics of the rocks that can be detected with borehole geophysical tools. This study is concerned with a uranium deposit within the Jackson Group that is located just east of Karnes City, Tex. Five holes were drilled on this property to obtain borehole geophysical data and cores. The cores were analyzed for mineralogic and electrical properties. The borehole geophysical information at this property included induced polarization, resistivity, gamma-gamma density, neutron-neutron, gamma-ray, caliper, and single-point-resistance logs. Between-hole resistivity and induced polarization measurements were made between hole pairs across the ore deposit and off the ore deposit.

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