SEARCH · Geology Reports

Results for “Studies in Maine Geology”

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

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources

USGS2013

Long-range hazard assessment of volcanic ash dispersal for a Plinian eruptive scenario at Popocatépetl volcano (Mexico): implications for civil aviation safety

Popocatépetl is one of Mexico’s most active volcanoes threatening a densely populated area that includes Mexico City with more than 20 million inhabitants. The destructive potential of this volcano is demonstrated by its Late Pleistocene–Holocene eruptive activity, which has been characterized by recurrent Plinian eruptions of large magnitude, the last two of which destroyed human settlements in pre-Hispanic times. Popocatépetl’s reawakening in 1994 produced a crisis that culminated with the evacuation of two villages on the northeastern flank of the volcano. Shortly after, a monitoring system and a civil protection contingency plan based on a hazard zone map were implemented. The current volcanic hazards map considers the potential occurrence of different volcanic phenomena, including pyroclastic density currents and lahars. However, no quantitative assessment of the tephra hazard, especially related to atmospheric dispersal, has been performed. The presence of airborne volcanic ash at low and jet-cruise atmospheric levels compromises the safety of aircraft operations and forces re-routing of aircraft to prevent encounters with volcanic ash clouds. Given the high number of important airports in the surroundings of Popocatépetl volcano and considering the potential threat posed to civil aviation in Mexico and adjacent regions in case of a Plinian eruption, a hazard assessment for tephra dispersal is required. In this work, we present the first probabilistic tephra dispersal hazard assessment for Popocatépetl volcano. We compute probabilistic hazard maps for critical thresholds of airborne ash concentrations at different flight levels, corresponding to the situation defined in Europe during 2010, and still under discussion. Tephra dispersal mode is performed using the FALL3D numerical model. Probabilistic hazard maps are built for a Plinian eruptive scenario defined on the basis of geological field data for the “Ochre Pumice” Plinian eruption (4965 14 C yr BP). FALL3D model input eruptive parameters are constrained through an inversion method carried out with the semi-analytical HAZMAP model and are varied by sampling them using probability density functions. We analyze the influence of seasonal variations on ash dispersal and estimate the average persistence of critical ash concentrations at relevant locations and airports. This study assesses the impact that a Plinian eruption similar to the Ochre Pumice eruption would have on the main airports of Mexico and adjacent areas. The hazard maps presented here can support long-term planning that would help minimize the impacts of such an eruption on civil aviation.

Popocatépetl Volcano↗

USGS2012

Groundwater quality in the Delaware and St. Lawrence River Basins, New York, 2010

Water samples were collected from 10 production and domestic wells in the Delaware River Basin in New York and from 20 production and domestic wells in the St. Lawrence River Basin in New York from August through November 2010 to characterize groundwater quality in the basins. The samples were collected and processed by standard U.S. Geological Survey procedures and were analyzed for 147 physiochemical properties and constituents, including major ions, nutrients, trace elements, pesticides, volatile organic compounds (VOCs), radionuclides, and indicator bacteria. The Delaware River Basin covers 2,360 square miles in New York, and is underlain mainly by shale and sandstone bedrock with other types of bedrock present locally. The bedrock is overlain by till in much of the basin, but surficial deposits of saturated sand and gravel are present in some areas. Five of the wells sampled in the Delaware study area are completed in sand and gravel deposits, and five are completed in bedrock. Groundwater in the Delaware study area was typically neutral or slightly acidic; the water typically was soft. Bicarbonate, chloride, and calcium were the major ions with the greatest median concentrations; the dominant nutrient was nitrate. Strontium, barium, iron, and boron were the trace elements with the highest median concentrations. Radon was detected in all samples with activities greater than 300 picocuries per liter; the greatest radon activities were in samples from bedrock wells. Four pesticides, all herbicides or their degradates, were detected in four samples at trace levels; five VOCs, including four trihalomethanes and tetrachloromethane, were detected in two samples. Coliform bacteria were detected in five samples, but fecal coliform bacteria and Escherichia coli ( E. coli ) were not detected in any samples from the Delaware study area. The St. Lawrence River Basin covers 5,650 square miles in New York. The St. Lawrence River Basin in New York is underlain by crystalline, carbonate, and sandstone bedrock. The bedrock is overlain by till or lacustrine and marine deposits in much of the basin. Surficial deposits of saturated sand and gravel are present locally, but most wells in the basin are completed in bedrock. Five of the wells sampled in the St. Lawrence study area are completed in sand and gravel deposits, and 15 are completed in bedrock. Groundwater in the St. Lawrence study area was typically neutral or slightly basic; the water typically was hard. Bicarbonate, sulfate, and calcium were the major ions with the greatest median concentrations; the dominant nutrient was nitrate. Strontium, iron, barium, and boron were the trace elements with the highest median concentrations. Radon was detected in two-thirds of samples with activities greater than 300 picocuries per liter; the greatest radon activities were in samples from bedrock wells. Seven pesticides, including 5 herbicides, an herbicide degradate, and an insecticide, were detected in 11 samples at trace levels; 3 VOCs (tetrachloroethene, toluene, and trichloromethane, or chloroform) were detected in 2 samples. Coliform bacteria were detected in 7 samples, and E. coli were detected in two samples in the St. Lawrence study area. Water quality in both study areas is generally good, but concentrations of some constituents equaled or exceeded current or proposed Federal or New York State drinking-water standards. The standards exceeded are color (one sample in the St. Lawrence study area), pH (three samples in the Delaware study area), sodium (one sample in the St. Lawrence study area), total dissolved solids (one sample in the St. Lawrence study area), aluminum (one sample in the Delaware study area and one sample in the St. Lawrence study area), iron (seven samples in the St. Lawrence study area), manganese (one sample in the Delaware study area and five samples in the St. Lawrence study area), gross alpha radioactivity (one sample in the St. Lawrence study area), radon-222 (10 samples in the Delaware study area and 14 samples in the St. Lawrence study area), and bacteria (5 samples in the Delaware study area and 10 samples in the St. Lawrence study area). E. coli bacteria were detected in samples from two wells in the St. Lawrence study area. Concentrations of chloride, fluoride, sulfate, nitrate, nitrite, antimony, arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury, selenium, silver, thallium, zinc, and uranium did not exceed existing drinking-water standards in any of the samples collected.

New York↗

USGS2009

Water-Table and Potentiometric-Surface Altitudes in the Upper Glacial, Magothy, and Lloyd Aquifers beneath Long Island, New York, March-April 2006

The U.S. Geological Survey (USGS), in cooperation with State and local agencies, systematically collects ground-water data at varying measurement frequencies to monitor the hydrologic situation on Long Island, New York. Each year during March and April, the USGS conducts a synoptic survey of hydrologic conditions to define the spatial distribution of the water table and potentiometric surfaces within the three main water-bearing units underlying Long Island - the upper glacial, Magothy, and Lloyd aquifers. These data and the maps constructed from them are commonly used in studies of Long Island's hydrology, and by water managers and suppliers for aquifer management and planning purposes. Water-level measurements made in 502 wells across Long Island during March-April 2006, were used to prepare the maps in this report. Measurements were made by the wetted-tape method to the nearest hundredth of a foot. Water-table and potentiometric-surface altitudes in these aquifers were contoured using these measurements. The water-table contours were interpreted using water-level data collected from 341 wells screened in the upper glacial aquifer and (or) shallow Magothy aquifer; the Magothy aquifer's potentiometric-surface contours were interpreted from measurements at 102 wells screened in the middle to deep Magothy aquifer and (or) contiguous and hydraulically connected Jameco aquifer; and the Lloyd aquifer's potentiometric-surface contours were interpreted from measurements at 59 wells screened in the Lloyd aquifer or contiguous and hydraulically connected North Shore aquifer. Many of the supply wells are in continuous operation and, therefore, were turned off for a minimum of 24 hours before measurements were made so that the water levels in the wells could recover to the level of the potentiometric head in the surrounding aquifer. Full recovery time at some of these supply wells can exceed 24 hours; therefore, water levels measured at these wells are assumed to be less accurate than those measured at observation wells, which are not pumped. In this report, all water-level altitudes are referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).

Scientific Investigations Map↗

USGS1968

Records of wells, water levels, and chemical quality of water in the lower Santiam River basin, middle Willamette Valley, Oregon

Basic water data on the lower Santiam River basin is preliminary to a comprehensive hydrologic study of this productive and intensely irrigated area where expanding population and industry increases the demand for water . Highest yielding wells are in shallow alluvial aquifers near the main streams; yields range from several hundred to more than a thousand gpm. Wells in lacustrine and older alluvial aquifers that underlie low, flat terraces have yields from a few tens to a few hundred gpm. Wells in the Salem Hills and in the Cascade Range foothills yield moderate to small quantities of water and tap a variety of geologic units. Tabulated material includes records of representative wells , drillers' logs, and chemical and spectrographic analyses of the ground water .

Oregon↗

USGS2001

Quantification of mine-drainage inflows to Little Cottonwood Creek, Utah, using a tracer-injection and synoptic-sampling study

Historic mining in Little Cottonwood Canyon in Utah has left behind many mine drainage tunnels that discharge water to Little Cottonwood Creek. To quantify the major sources of mine drainage to the stream, synoptic sampling was conducted during a tracer injection under low flow conditions (September 1998). There were distinct increases in discharge downstream from mine drainage and major tributary inflows that represented the total surface and subsurface contributions. The chemistry of stream water determined from synoptic sampling was controlled by the weathering of carbonate rocks and mine drainage inflows. Buffering by carbonate rocks maintained a high pH throughout the study reach. Most of the metal loading was from four surface-water inflows and three subsurface inflows. The main subsurface inflow was from a mine pool in the Wasatch Tunnel. Natural attenuation of all the metals resulted in the formation of colloidal solids, sorption of some metals, and accumulation onto the streambed. The deposition on the streambed could contribute to chronic toxicity for aquatic organisms. Information from the study will help to make decisions about environmental restoration.

Utah↗

USGS2002

Geologic map of the Eagle Quadrangle, Eagle County, Colorado

The Eagle quadrangle covers an area that straddles the Eagle River and Interstate 70 (I-70) and it includes the town of Eagle, Colo., which is located in the southwestern part of the quadrangle, just south of I-70 and the Eagle River, about 37 km west of Vail, Colo. The map area is part of the I-70 urban corridor, which is experiencing rapid and escalating urban growth. Geologic mapping along this corridor is needed for ongoing land-use planning. A variety of rocks and deposits characterize the map area and areas nearby. Sedimentary rocks present in the map area range in age from Pennsylvanian rocks, which were deposited in the ancestral Eagle basin during the formation of the ancestral Rocky Mountains, to Late Cretaceous rocks that were deposited just prior to the formation of the present Rocky Mountains. The Pennsylvanian rocks in the map area include a thick sequence of evaporitic rocks (Eagle Valley Evaporite). These evaporitic rocks are commonly complexly folded throughout the southern part of the quadrangle where they are exposed. In general, in the central and northern parts of the quadrangle, the sedimentary rocks overlying the evaporite dip gently to moderately northward. Consequently, the youngest sedimentary rocks (Late Cretaceous rocks) are exposed dipping gently to the north in the northern part of the quadrangle; landslide complexes are widespread along the northerly dipping, dip slopes in shaly rocks of the Cretaceous sequence in the northeastern part of the map area. During the Early Miocene, basaltic volcanism formed extensive basaltic flows that mantled the previously deformed and eroded sedimentary rocks. Erosional remnants of the basaltic flows are preserved in the southeastern, west-central, and north-central parts of the map area. Some of these basaltic flows are faulted and downdropped in a manner that suggests they were downdropped in areas where large volumes of the underlying evaporitic rocks were removed from the subsurface, beneath the basaltic rocks, by dissolution or flowage of the evaporite in the subsurface. Quaternary and late Tertiary(?) surficial deposits in the map area consist mainly of Quaternary alluvium and colluvium, late and middle Pleistocene terrace gravels of the Eagle River, Miocene(?) gravel remnants of the ancestral Eagle River and its tributaries, and Pleistocene to recent mass movement deposits that include landslides and debris flows. Potential geologic hazards in the map area include landslides, debris flows, rockfalls, local flooding, ground subsidence, and expansive and corrosive soils.

Colorado↗

USGS2005

Physical and chemical characteristics of Knowles, Forgotten, and Moqui Canyons, and effects of recreational use on water quality, Lake Powell, Arizona and Utah

Side canyons of Lake Powell are the most popular recreation areas of the Glen Canyon National Recreation Area in Arizona and Utah. There are more than 90 side canyons that are tributaries to the main lake body of Lake Powell. Near Bullfrog and Halls Crossing marinas in Utah, visitors frequent Knowles, Forgotten, and Moqui Canyons to fish, boat, camp, and hike the sandstone formations for which Lake Powell is famous. Areas of recreational activity are greatest near beaches in side canyons. Emissions from houseboats, personal watercraft, speedboats, and from some nonboating recreational activities introduce contaminants to the lake and to beach areas. The U.S. Geological Survey documented concentrations of trace elements, volatile organic compounds, organic wastewater contaminants, and other byproducts of fuel-based contaminants in water and bed material in Knowles, Forgotten, and Moqui Canyons during the summers of 2001 and 2002. Field work was conducted during four trips when recreational use was at a minimum (before Memorial Day in May) and when it was at a maximum (near Labor Day in September). Knowles Canyon was treated as a control; therefore, public access by motorcraft was not permitted during the study. Electric-powered or oar-powered research boats were used to collect samples and measure properties in Knowles Canyon. Record-low reservoir elevations during 2000-2002 limited the availability of camping and day-use beaches in Forgotten and Moqui Canyons. Although more beach areas were exposed during this period, the steep slopes of the beaches made it difficult to use the beaches for camping purposes. Side canyon waters of Knowles, Forgotten, and Moqui Canyons were similarly stratified (physically and chemically) during the study from natural advective and convective reservoir processes. Metalimnetic oxygen minimas were observed in September 2001 and 2002 in the side canyons and the main body of Lake Powell. Chemical concentrations of several organic constituents were elevated in Forgotten and Moqui Canyons during the high-use period in September of 2001 and 2002 compared with concentrations during the low-use period in May of 2001 and 2002. Concentrations of some constituents decreased from the mouth of each canyon to the canyon's headwaters, indicating that there could be a mechanism for constituent removal or that the main body of Lake Powell is not in equilibrium with the headwaters of the side canyons. Concentrations of volatile organic compounds, such as benzene, toluene, ethylbenzene, and xylene (BTEX compounds), were highest in the upper reaches of Forgotten and Moqui Canyons where visitor use was greatest. Trace amounts of some organic wastewater compounds, including cholesterol, N,N-diethyl-meta-toluamide (DEET), and ethylenediaminetetraacetic acid (EDTA), were measured in Forgotten and Moqui Canyons. Except for minor concentrations of some volatile organic compounds and cholesterol, contamination from visitor use in Knowles Canyon was not detected, most likely because the canyon was closed to access. Concentrations of some organic compounds in bed material sampled in the side canyons near popular beach areas, including polyaromatic hydrocarbons, were above the laboratory detection limits. Several other constituents were present in trace amounts. Benzyl n-butylphthalate and bis (2 ethyl)-phthalate were detected at concentrations above laboratory detection limits. Numerous trace elements were detected above laboratory detection limits in Knowles, Forgotten, and Moqui Canyons. All water samples from the side canyon transects had low colony counts of Escherichia coli (E. coli); the highest count was less than one-fourth of the U.S. Environmental Protection Agency recommended limit for recreational water. Four water samples collected near beaches in Moqui Canyon had E. coli colony counts that exceeded the U.S. Environmental Protection Agency recommended limit.

Arizona, Utah↗

USGS2009

Hydrochemical analysis of groundwater using multivariate statistical methods - The Volta region, Ghana

Q and R-mode multivariate statistical analyses were applied to groundwater chemical data from boreholes and wells in the northern section of the Volta region Ghana. The objective was to determine the processes that affect the hydrochemistry and the variation of these processes in space among the three main geological terrains: the Buem formation, Voltaian System and the Togo series that underlie the area. The analyses revealed three zones in the groundwater flow system: recharge, intermediate and discharge regions. All three zones are clearly different with respect to all the major chemical parameters, with concentrations increasing from the perceived recharge areas through the intermediate regions to the discharge areas. R-mode HCA and factor analysis (using varimax rotation and Kaiser Criterion) were then applied to determine the significant sources of variation in the hydrochemistry. This study finds that groundwater hydrochemistry in the area is controlled by the weathering of silicate and carbonate minerals, as well as the chemistry of infiltrating precipitation. This study finds that the ??D and ?? 18 O data from the area fall along the Global Meteoric Water Line (GMWL). An equation of regression derived for the relationship between ??D and ?? 18 O bears very close semblance to the equation which describes the GMWL. On the basis of this, groundwater in the study area is probably meteoric and fresh. The apparently low salinities and sodicities of the groundwater seem to support this interpretation. The suitability of groundwater for domestic and irrigation purposes is related to its source, which determines its constitution. A plot of the sodium adsorption ratio (SAR) and salinity (EC) data on a semilog axis, suggests that groundwater serves good irrigation quality in the area. Sixty percent (60%), 20% and 20% of the 67 data points used in this study fall within the medium salinity - low sodicity (C2-S1), low salinity -low sodicity (C1-S1) and high salinity - low sodicity (C3-S1) fields, which ascribe good irrigation quality to groundwater from this area. Salinities range from 28.1 to 1956 ??S/cm, whilst SAR values fall within the range 0-3. Extremely low sodicity waters of this kind, with salinities lower than 600 ??S/cm, have the tendency to affect the dispersive properties of irrigation soils when used for irrigation. About 50% of the groundwater in the study area fall within this category and need prior treatment before usage. ?? 2009 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg GmbH.

KSCE Journal of Civil Engineering↗

USGS2008

Introduction to the special section northeast Japan: A case history of subduction

Subduction-related tectonic events such as strike-slip faulting, uplift of high-pressure metamorphic rocks in the forearc, back arc spreading, arc magmatism, and continental collisions have shaped northeast Japan, making it a case history for subduction. Much of the record of these events is preserved and can be used to reconstruct the tectonic history of the region. Although many geological, geophysical, and geochemical data have been collected in Japan for the last 30 years, interpretation of these data into a plate tectonic context did not really begin until about 10 years ago. Much of the data and interpretation on northeast Japan have been published in Japanese or as individual local studies. The primary goal of this special section is to present new investigations covering a wide range of topics and scales and place them in a tectonic framework. The papers in this special section focus on three main subjects: Mesozoic aspects of northeast Japan; the relation of Japan Sea opening with the tectonics and geochemistry of northeast Japan in the Tertiary; and the geophysical setting. The purpose of this overview is to link these subjects and provide a tectonic framework for north- east Japan and eastern Asia since the Mesozoic.

Journal of Geophysical Research B: Solid Earth↗

USGS1988

Thermochronology of economic mineral deposits: Dating the stages of mineralization at Panasqueira, Portugal, by high-precision 40Ar/ 39Ar age spectrum techniques on muscovite

40 Ar/ 39 Ar age spectrum dates for 13 muscovites have been used to reconstruct the thermal history (thermochronology) of the Panasqueira, Portugal, tin-tungsten deposit, a deposit spatially associated with a belt of Hercynian plutons. Muscovite samples with an age difference as small as 2.2 m.y. (0.7% of the age) are statistically distinct. Statistics are even better for comparison of multiple samples from separate events; that is, a difference of 0.9 m.y. (0.3%) can be resolved in this approximately 300-m.y.-old deposit. The major tin and tungsten ore-forming stages, which are the oxide-silicate stage, the main sulfide stage, and greisenization, occurred between 296.3 + or - 0.8 (1 Sigma ) and 291.6 + or - 0.8 m.y. (1 Sigma ). The first substage of the oxide-silicate stage was a short-lived thermal pulse at 296.3 + or - 0.6 m.y.; the fluids responsible may have emanated from the known granite cupola. The main sulfide stage was active at 294.5 + or - 0.9 m.y. as a slightly longer lived pulse with oldest evidence for this stage (295.8 + or - 0.6 m.y.) coming from areas farthest away from the known cupola and youngest evidence (293.5 + or - 0.8 m.y.) closest to the cupola. A second substage of the oxide-silicate stage occurred as a short-lived thermal pulse at 292.9 + or - 0.7 m.y., synchronous with greisenization of the cupola and alteration of the silica cap at 292.1 + or - 0.4 m.y. The duration of activity of the oxide-silicate stage, the main sulfide stage, greisenization, and alteration of the silica cap based on the ages of all 13 muscovites was greater than 4.2 + or - 0.5 m.y. (1 Sigma ). Minor argon loss from all dated muscovites occurred during later reheating, probably during the longer lived pyrrhotite alteration stage. A single center, the known cupola, had a prolonged role and was the source for main sulfide stage, oxide-silicate stage II, greisenization, and alteration of the silica cap and possibly oxide-silicate stage I and the pyrrhotite alteration stage; however, a separate source for these latter two stages cannot be ruled out.This study is an example of a new and powerful application of 40 Ar/ 39 Ar age spectrum dating of muscovite. Because of the high precision demonstrated in this study, it is now possible to establish time constraints necessary for solving some of the long-standing problems in economic geology. Beyond this, the unique geologic situation of Panasqueira has allowed us to quantify the thermal characteristics of muscovite. Published fluid inclusion data have been used to estimate a muscovite argon closure temperature of approximately 325 degrees C during rapid cooling or short reheating and a temperature of approximately 270 degrees C during slow cooling or extended reheating. Argon-loss patterns displayed by all dated muscovites resulted from reheating after original closure; the mechanism for this argon loss appears to have been argon transport by volume diffusion. Thus, 40 Ar/ 39 Ar age spectrum dating of muscovite can be used to evaluate thermal conditions controlling argon diffusion as well as age, duration, and number of episodes of mineralization.

Economic Geology↗

USGS2018

Geologic framework and hydrogeology of the Rio Rico and Nogales 7.5’ quadrangles, upper Santa Cruz Basin, Arizona, with three-dimensional hydrogeologic model

Rapid population growth and declining annual recharge to aquifers in the upper Santa Cruz Basin area of southern Arizona, have increased the demand for additional groundwater resources. This demand is predicted to escalate in the future because of higher temperatures, longer droughts, less aquifer recharge, and decreased river and stream base flow. We conducted geologic studies to help evaluate and better understand groundwater resources in the basin. Results of these studies are presented in this report, which summarizes the basin geologic framework and hydrogeology, and presents a threedimensional (3D) hydrogeologic model for the Rio Rico and Nogales 7.5′ quadrangles. Three major hydrogeologic units are displayed in the 3D model; a lower basement confining unit, consisting of Jurassic, Cretaceous, and Tertiary (Paleocene and Oligocene) rocks; a middle unit composed entirely of the Miocene Nogales Formation; and an upper unit consisting of late Miocene to Holocene surficial deposits. The Nogales Formation and the late Miocene to Holocene sediments are the main aquifers in the upper Santa Cruz Basin. The 3D model integrates the hydrogeologic units and faults to define the geometry, structure, and thickness of the aquifer system that provides water to Nogales and surrounding communities of southernmost Arizona. The report includes an EarthVision 3D Viewer, consisting of software enabling the user to view data interactively in 3D space to help explain the internal complexities of the basin geometry, structure, stratigraphy, and hydrology. The 3D model is a synthesis of geologic data from geologic maps, cross sections, and lithologic descriptions and interpretations; and geophysical data including gravity, magnetic data, and airborne electromagnetic data.

Arizona↗

USGS2011

A petroleum system model for gas hydrate deposits in northern Alaska

Gas hydrate deposits are common on the North Slope of Alaska around Prudhoe Bay, however the extent of these deposits is unknown outside of this area. As part of a United States Geological Survey (USGS) and the Bureau of Land Management (BLM) gas hydrate research collaboration, well cutting and mud gas samples have been collected and analyzed from mainly industry-drilled wells on the Alaska North Slope for the purpose of prospecting for gas hydrate deposits. On the Alaska North Slope, gas hydrates are now recognized as an element within a petroleum systems approach or TPS (Total Petroleum System). Since 1979, 35 wells have been samples from as far west as Wainwright to Prudhoe Bay in the east. Geochemical studies of known gas hydrate occurrences on the North Slope have shown a link between gas hydrate and more deeply buried conventional oil and gas deposits. Hydrocarbon gases migrate from depth and charge the reservoir rock within the gas hydrate stability zone. It is likely gases migrated into conventional traps as free gas, and were later converted to gas hydrate in response to climate cooling concurrent with permafrost formation. Gas hydrate is known to occur in one of the sampled wells, likely present in 22 others based gas geochemistry and inferred by equivocal gas geochemistry in 11 wells, and absent in one well. Gas migration routes are common in the North Slope and include faults and widespread, continuous, shallowly dipping permeable sand sections that are potentially in communication with deeper oil and gas sources. The application of this model with the geochemical evidence suggests that gas hydrate deposits may be widespread across the North Slope of Alaska.

Alaska↗

USGS2015

Geospatial compilation and digital map of centerpivot irrigated areas in the mid-Atlantic region, United States

To evaluate water availability within the Northern Atlantic Coastal Plain, the U.S. Geological Survey, in cooperation with the University of Delaware Agricultural Extension, created a dataset that maps the number of acres under center-pivot irrigation in the Northern Atlantic Coastal Plain study area. For this study, the extent of the Northern Atlantic Coastal Plain falls within areas of the States of New York, New Jersey, Delaware, Maryland, Virginia, and North Carolina. The irrigation dataset maps about 271,900 acres operated primarily under center-pivot irrigation in 57 counties. Manual digitizing was performed against aerial imagery in a process where operators used observable center-pivot irrigation signatures—such as irrigation arms, concentric wheel paths through cropped areas, and differential colors—to identify and map irrigated areas. The aerial imagery used for digitizing came from a variety of sources and seasons. The imagery contained a variety of spatial resolutions and included online imagery from the U.S. Department of Agriculture National Agricultural Imagery Program, Microsoft Bing Maps, and the Google Maps mapping service. The dates of the source images ranged from 2010 to 2012 for the U.S. Department of Agriculture imagery, whereas maps from the other mapping services were from 2013. Most of the irrigation in the study area is on the Delmarva Peninsula, where about 75 percent of the total acreage was delineated and where corn and soy bean are the main crops. The methods used to develop this dataset focused primarily on identifying center-pivot irrigation systems. In some instances (such as in in Suffolk County, New York), irrigated rectangular fields were observed through the aerial imagery, and these were included within the dataset. Other irrigation methods included subsurface drip and flood irrigation, which are commonly used on vegetable crops such as peppers and tomatoes and forage crops such as alfalfa in parts the western United States. Some fruit and nursery stock crops also use subsurface drip and flood irrigation. Drip irrigation is especially apparent in New Jersey where large plantings of truck crops are common. Subsurface drip and flood irrigation methods were not accounted for in this dataset. The U.S. Geological Survey collected these data to enhance the understanding of irrigation water demand and associated groundwater withdrawals for the Northern Atlantic Coastal Plain. The digitized acreage totals were compared with the irrigation estimates provided by the U.S. Department of Agriculture farm and ranch irrigation survey, which is the most comprehensive source of information on irrigation water use within the agricultural industry. This survey collects information on a wide range of topics, including the amount of water used, total acres irrigated, crop specific data, and even energy costs. The U.S. Department of Agriculture samples data for both entire States and individual counties.

Data Series↗

USGS2009

Spatial pattern of groundwater arsenic occurrence and association with bedrock geology in greater augusta, maine

In New England, groundwater arsenic occurrence has been linked to bedrock geology on regional scales. To ascertain and quantify this linkage at intermediate (10 0 -10 1 km) scales, 790 groundwater samples from fractured bedrock aquifers in the greater Augusta, Maine area are analyzed, and 31% of the sampled wells have arsenic concentrations >10 ??g/L. The probability of [As] exceeding 10 ??g/L mapped by indicator kriging is highest in Silurian pelite-sandstone and pelite-limestone units (???40%). This probability differs significantly (p < 0.001) from those in the Silurian - Ordovician sandstone (24%), the Devonian granite (15%), and the Ordovician - Cambrian volcanic rocks (9%). The spatial pattern of groundwater arsenic distribution resembles the bedrock map. Thus, bedrock geology is associated with arsenic occurrence in fractured bedrock aquifers of the study area at intermediate scales relevant to water resources planning. The arsenic exceedance rate for each rock unit is considered robust because low, medium, and high arsenic occurrences in four cluster areas (3-20 km 2 ) with a low sampling density of 1-6 wells per km 2 are comparable to those with a greater density of 5-42 wells per km 2 . About 12,000 people (21% of the population) in the greater Augusta area (???1135 km 2 ) are at risk of exposure to >10 ??g/L arsenic in groundwater. ?? 2009 American Chemical Society.

Environmental Science & Technology↗

USGS2026

Season and antecedent conditions impact concentration-discharge relationships for dissolved organic carbon and alkalinity in southeast Alaskan watershed

Fluvial export of dissolved carbon plays an important role in watershed-scale biogeochemistry. Predicted changes in climate are expected to impact watershed hydrologic regimes, and in turn, the sources and export of dissolved carbon from watersheds. Here, we utilize high resolution measurements of discharge and dissolved carbon concentration to examine how concentration-discharge (CQ) relationships vary seasonally and during high flow events over the main runoff season (May–October) in a temperate forested watershed in Southeast Alaska. Concentration-discharge relationships for dissolved organic carbon (DOC) and alkalinity demonstrated strong seasonal patterns, with more linear relationships in May and June versus other months. Changing power law model slopes ( b values; the exponent in a power law regression between runoff and carbon yields) indicated potentially shifting watershed sources (biogenic vs. geologic) and contrasting dominant flowpaths (shallow vs. deeper groundwater) for DOC and alkalinity over the sampling period. During the largest storm event of the study, DOC and alkalinity b values shifted from an overall pattern of transport (mean b = 1.58 values >1.0 indicate transport limitation) and source limitation (mean b = 0.48, values <1.0 indicate source limitation) to chemostatic (DOC, b = 0.99; alkalinity, b = 1.019). In June through August, patterns in hysteresis index suggest that CQ relationships were altered when storms followed in close succession to each other. Together, these findings indicate that seasonal and antecedent flow conditions play a role in dissolved carbon export from forested watersheds. Understanding these dynamics, particularly during winter months, will become increasingly important as changes to hydroclimate impact riverine carbon export.

Alaska↗

USGS2012

AquaPathogen X--A template database for tracking field isolates of aquatic pathogens

AquaPathogen X is a template database for recording information on individual isolates of aquatic pathogens and is available for download from the U.S. Geological Survey (USGS) Western Fisheries Research Center (WFRC) website (http://wfrc.usgs.gov). This template database can accommodate the nucleotide sequence data generated in molecular epidemiological studies along with the myriad of abiotic and biotic traits associated with isolates of various pathogens (for example, viruses, parasites, or bacteria) from multiple aquatic animal host species (for example, fish, shellfish, or shrimp). The simultaneous cataloging of isolates from different aquatic pathogens is a unique feature to the AquaPathogen X database, which can be used in surveillance of emerging aquatic animal diseases and clarification of main risk factors associated with pathogen incursions into new water systems. As a template database, the data fields are empty upon download and can be modified to user specifications. For example, an application of the template database that stores the epidemiological profiles of fish virus isolates, called Fish ViroTrak (fig. 1), was also developed (Emmenegger and others, 2011).

Fact Sheet↗

USGS2004

Effects of Abandoned Coal-Mine Drainage on Streamflow and Water Quality in the Mahanoy Creek Basin, Schuylkill, Columbia, and Northumberland Counties, Pennsylvania, 2001

This report assesses the contaminant loading, effects to receiving streams, and possible remedial alternatives for abandoned mine drainage (AMD) within the Mahanoy Creek Basin in east-central Pennsylvania. The Mahanoy Creek Basin encompasses an area of 157 square miles (407 square kilometers) including approximately 42 square miles (109 square kilometers) underlain by the Western Middle Anthracite Field. As a result of more than 150 years of anthracite mining in the basin, ground water, surface water, and streambed sediments have been adversely affected. Leakage from streams to underground mines and elevated concentrations (above background levels) of acidity, metals, and sulfate in the AMD from flooded underground mines and (or) unreclaimed culm (waste rock) degrade the aquatic ecosystem and impair uses of the main stem of Mahanoy Creek from its headwaters to its mouth on the Susquehanna River. Various tributaries also are affected, including North Mahanoy Creek, Waste House Run, Shenandoah Creek, Zerbe Run, and two unnamed tributaries locally called Big Mine Run and Big Run. The Little Mahanoy Creek and Schwaben Creek are the only major tributaries not affected by mining. To assess the current hydrological and chemical characteristics of the AMD and its effect on receiving streams, and to identify possible remedial alternatives, the U.S. Geological Survey (USGS) began a study in 2001, in cooperation with the Pennsylvania Department of Environmental Protection and the Schuylkill Conservation District. Aquatic ecological surveys were conducted by the USGS at five stream sites during low base-flow conditions in October 2001. Twenty species of fish were identified in Schwaben Creek near Red Cross, which drains an unmined area of 22.7 square miles (58.8 square kilometers) in the lower part of the Mahanoy Creek Basin. In contrast, 14 species of fish were identified in Mahanoy Creek near its mouth at Kneass, below Schwaben Creek. The diversity and abundance of fish species in Mahanoy Creek decreased progressively upstream from 13 species at Gowen City to only 2 species each at Ashland and Girardville. White sucker (Catostomus commersoni), a pollution-tolerant species, was present at each of the surveyed reaches. The presence of fish at Girardville was unexpected because of the poor water quality and iron-encrusted streambed at this location. Generally, macroinvertebrate diversity and abundance at these sites were diminished compared to Schwaben Creek and other tributaries draining unmined basins, consistent with the observed quality of streamwater and streambed sediment. Data on the flow rate and chemistry for 35 AMD sources and 31 stream sites throughout the Mahanoy Creek Basin were collected by the USGS during high base-flow conditions in March 2001 and low base-flow conditions in August 2001. A majority of the base-flow streamwater samples met water-quality standards for pH (6.0 to 9.0); however, few samples downstream from AMD sources met criteria for acidity less than alkalinity (net alkalinity = 20 milligrams per liter as CaCO3) and concentrations of dissolved iron (0.3 milligram per liter) and total manganese (1.0 milligram per liter). Iron, aluminum, and various trace elements including cobalt, copper, lead, nickel, and zinc, were present in many streamwater samples at concentrations at which continuous exposure can not be tolerated by aquatic organisms without an unacceptable effect. Furthermore, concentrations of sulfate, iron, manganese, aluminum, and (or) beryllium in some samples exceeded drinking-water standards. Other trace elements, including antimony, arsenic, barium, cadmium, chromium, selenium, silver, and thallium, did not exceed water-quality criteria for protection of aquatic organisms or human health. Nevertheless, when considered together, concentrations of iron, manganese, arsenic, cadmium, chromium, copper, lead, nickel, and zinc in a majority of the streambed sediment samples from Mahanoy Creek and

Scientific Investigations Report↗

USGS2014

Palila restoration research, 1996−2012

The Palila Restoration Project was initiated in 1996 by the U.S. Geological Survey to assist government agencies mitigate the effects of realigning Saddle Road (Highway 200) through Palila Critical Habitat (U.S. Fish and Wildlife Service 1998, Federal Highway Administration 1999). Ecological research on the palila (Loxioides bailleui), an endangered Hawaiian forest bird, carried out by the U.S. Geological Survey (formerly organized as the Research Division of U.S. Fish and Wildlife Service) since 1987 and research conducted by the Palila Restoration Project provided the scientific bases for developing a recovery strategy (U.S. Fish and Wildlife Service 2006) and its adaptive implementation. The main objectives of the Palila Restoration Project were to develop techniques for reintroducing the palila to a portion of its former range, investigate the biological threats to the palila and its habitat, and synthesize the existing body of ecological knowledge concerning the palila. Five broad study themes formed the research framework: 1. Population reintroduction and restoration 2. Demography and breeding ecology 3. Habitat use and food ecology 4. Vegetation ecology 5. Predator ecology and management An element that was not included in the research program of the project was the ecology and management of introduced ungulates, which has historically constituted the single greatest threat to Palila Critical Habitat (Banko et al. 2009). The absence of ungulate studies should not be interpreted to mean that we believe ungulates no longer damage palila habitat. Other research has already established that removing alien browsers and grazers from Mauna Kea is essential for the recovery of the subalpine forest on which palila now depend (Scowcroft and Giffin 1983; Scowcroft and Sakai 1983; Scowcroft and Conrad 1988, 1992; Hess et al. 1999). Moreover, the Federal District Court of Hawai‘i has ordered the state of Hawai‘i to remove browsing ungulates from Palila Critical Habitat (Banko et al. 2009, Hess and Banko 2011). This final report summarizes results of Palila Restoration Project research from December 1996 to December 2012. Even though some results contained in this report have been published in scientific journals and other technical reports (Appendix I), they are included here to provide a comprehensive chronicle of all project activities.

Hawaii↗