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At least 55 records · Page 3Linked to original sources
USGS2006

Microbial transformations of arsenic in the environment: From soda lakes to aquifers

Arsenic is a highly toxic element that supports a surprising range of biogeochemical transformations. The biochemical basis of these microbial interactions is described, with an emphasis on energy-yielding redox biotransformations that cycle between the As5+ and As3+ oxidation states. The subsequent impact of As3+-oxidising and As 5+-reducing prokaryotes on the chemistry of selected environments is also described, focusing on soda lakes with naturally high concentrations of the metalloid and on Southeast Asian aquifer sediments, where the microbial reduction of sorbed As5+ and subsequent mobilisation of As 3+ into water abstracted for drinking and irrigation threaten the lives of millions.

Elements↗
USGS1977

Reconnaissance examination of the biology, chemistry, and physical characteristics of selected streams in California and Nevada

This report contains hydrological data from several California and Nevada streams. Emphasis is placed upon water-quality data, but stream discharge at the time of making the water-quality measurements also is given. The purpose of the report is to provide personnel of the U.S. Bureau of Land Management with baseline hydrological data from the selected streams and one well. The streams, the stream sites selected for sampling, and the parameters measured, were chosen in consultation with U.S. Bureau of Land Management personnel.

California, Nevada↗
USGS2015

Evaluating connection of aquifers to springs and streams, Great Basin National Park and vicinity, Nevada

Federal agencies that oversee land management for much of the Snake Range in eastern Nevada, including the management of Great Basin National Park by the National Park Service, need to understand the potential extent of adverse effects to federally managed lands from nearby groundwater development. As a result, this study was developed (1) to attain a better understanding of aquifers controlling groundwater flow on the eastern side of the southern part of the Snake Range and their connection with aquifers in the valleys, (2) to evaluate the relation between surface water and groundwater along the piedmont slopes, (3) to evaluate sources for Big Springs and Rowland Spring, and (4) to assess groundwater flow from southern Spring Valley into northern Hamlin Valley. The study focused on two areas—the first, a northern area along the east side of Great Basin National Park that included Baker, Lehman, and Snake Creeks, and a second southern area that is the potential source area for Big Springs. Data collected specifically for this study included the following: (1) geologic field mapping; (2) drilling, testing, and water quality sampling from 7 test wells; (3) measuring discharge and water chemistry of selected creeks and springs; (4) measuring streambed hydraulic gradients and seepage rates from 18 shallow piezometers installed into the creeks; and (5) monitoring stream temperature along selected reaches to identify places of groundwater inflow. The Snake Range was formed by a generally normal-faulted uplift, where late Proterozoic and Cambrian siliciclastic rocks and metamorphic rocks are present at the highest altitudes and younger Paleozoic carbonate rocks are exposed along the flanks. The consolidated rocks are intruded by Jurassic to Tertiary age plutons, which are most common between the Lehman and Snake Creek drainage basins. Older Cenozoic rocks, including Oligocene volcanic rocks and Miocene sedimentary rocks, crop out locally and fill the basins that underlie Snake, Spring, and Hamlin Valleys. Younger Tertiary and Quaternary sedimentary (basin-fill) deposits overlie the older Cenozoic rocks. The rocks and deposits can be divided into three distinct aquifers. These aquifers include (1) basin-fill aquifers that consist of the permeable parts of the Cenozoic basin fill and some fractured or jointed Cenozoic volcanic rocks, (2) an upper carbonate-rock aquifer that consists of upper Paleozoic carbonate rocks overlying a regionally extensive middle Paleozoic siliciclastic confining unit, and (3) a lower carbonate-rock aquifer that consists of lower Paleozoic carbonate rocks. Secondary openings created by faults, shear zones, fractures, and, in the carbonate rocks, karst solution features, largely determine the water-transmitting properties of the volcanic- and carbonate-rock aquifers. The basin-fill aquifers are composed of a wide variety of rock types and have highly variable hydraulic properties. The three aquifers are stratigraphically and structurally heterogeneous, causing large variations in the ability to store and transmit water. The aquifers are separated by confining units in some areas and are in contact with each other in other areas, yet function as a single, composite aquifer system. Basin-fill aquifers most often overlie or adjoin the lower and upper carbonate-rock aquifers. Baker, Lehman and Snake Creek drainage basins were divided into five hydrologic zones on the basis of climate, geology, and topography. The five zones, from highest to lowest altitudes, are the mountain-upland, karst-limestone, upper-piedmont, lower-piedmont, and valley-lowland zones. The primary hydrologic connection between the mountain-upland and the valley-lowland zones is streamflow. Much of the streamflow from the mountain-upland zone is generated above tree line. Groundwater flow increases in the karst-limestone zone because of increased permeability caused by dissolution, which results in increased streamflow losses. Most of the increased groundwater flow is to springs near faults that form the boundary with the upper-piedmont zone. Thus, groundwater flow from the karst-limestone zone to the upper-piedmont zone was only 10 percent of the combined flow of streams and springs that exit the karst-limestone zone. About 60 percent of the water flowing from Rowland Spring in the Lehman Creek drainage basin was from streamflow losses along Baker Creek. The remaining flow from Rowland Spring comes from local recharge in the karst-limestone zone. In the upper-piedmont zone, the water table by Baker, Lehman and Snake Creeks was near the water level in the creeks for several hundred feet downstream from the karst-limestone zone. Water levels in piezometers along Snake Creek downstream from its confluence with Spring Creek were far below the streambed, indicating gravity drainage beneath this section of the creek. Estimated vertical hydraulic conductivity along a 3-mile reach of Snake Creek downstream of this confluence was 0.5 foot per day, which was an order of magnitude less than that estimated for Baker and Lehman Creeks. The low vertical hydraulic conductivity in the streambed along the lower reaches of Snake Creek results from chemical precipitation of calcite caused by off-gassing of carbon dioxide derived from springs at the end of the karst-limestone zone. The younger alluvial deposits thicken rapidly across faults that form the upper boundary of the lower-piedmont zone. The absence of springs or groundwater flow to the creeks upstream of these faults indicates they are not a complete barrier to groundwater flow. The water table was shallow in the valley-lowland zone in the Baker and Lehman Creek drainage basins, whereas the water table was more than 50 feet below land surface in the Snake Creek drainage basin. In contrast to thick basin fill in the valley-lowland zone in the Baker and Lehman Creek drainage basins, fractured and karst limestone underlie basin fill at relatively shallow depths in Snake Creek drainage basin. The underlying limestone acts as a drain for groundwater in the basin fill beneath Snake Creek. A groundwater divide in southern Spring Valley south of Baking Powder Flat separates groundwater flow to the flat from southeastward flow into northern Hamlin Valley. Groundwater flow from southern Spring Valley south of the groundwater divide into northern Hamlin Valley was estimated to range from 6,000 to 11,000 acre-feet per year. This groundwater does not flow to Big Springs in southern Snake Valley; rather, the source of water to Big Springs is groundwater recharge in the Big Spring Wash drainage basin and in nearby smaller drainage basins at the south end of the Snake Range. Groundwater flow from southern Spring Valley continues through the western side of Hamlin Valley before being directed northeast toward the south end of Snake Valley. This flow is constrained by southward-flowing groundwater from Big Spring Wash and northward-flowing groundwater beneath central Hamlin Valley. The redirection to the northeast corresponds to a narrowing of the width of flow in southern Snake Valley caused by a constriction formed by a steeply dipping middle Paleozoic siliciclastic confining unit exposed in the flanks of the mountains and hills on the east side of southern Snake Valley and shallowly buried beneath basin fill in the valley. The narrowing of groundwater flow could be responsible for the large area where groundwater flows to springs or is lost to evapotranspiration between Big Springs in Nevada and Pruess Lake in Utah.

Nevada↗
USGS2008

Potential Chemical Effects of Changes in the Source of Water Supply for the Albuquerque Bernalillo County Water Utility Authority

Chemical modeling was used by the U.S. Geological Survey, in cooperation with the Albuquerque Bernalillo County Water Utility Authority (henceforth, Authority), to gain insight into the potential chemical effects that could occur in the Authority's water distribution system as a result of changing the source of water used for municipal and industrial supply from ground water to surface water, or to some mixture of the two sources. From historical data, representative samples of ground-water and surface-water chemistry were selected for modeling under a range of environmental conditions anticipated to be present in the distribution system. Mineral phases calculated to have the potential to precipitate from ground water were compared with the compositions of precipitate samples collected from the current water distribution system and with mineral phases calculated to have the potential to precipitate from surface water and ground-water/surface-water mixtures. Several minerals that were calculated to have the potential to precipitate from ground water in the current distribution system were identified in precipitate samples from pipes, reservoirs, and water heaters. These minerals were the calcium carbonates aragonite and calcite, and the iron oxides/hydroxides goethite, hematite, and lepidocrocite. Several other minerals that were indicated by modeling to have the potential to precipitate were not found in precipitate samples. For most of these minerals, either the kinetics of formation were known to be unfavorable under conditions present in the distribution system or the minerals typically are not formed through direct precipitation from aqueous solutions. The minerals with potential to precipitate as simulated for surface-water samples and ground-water/surface-water mixtures were quite similar to the minerals with potential to precipitate from ground-water samples. Based on the modeling results along with kinetic considerations, minerals that appear most likely to either dissolve or newly precipitate when surface water or ground-water/surface-water mixtures are delivered through the Authority's current distribution system are carbonates (particularly aragonite and calcite). Other types of minerals having the potential to dissolve or newly precipitate under conditions present throughout most of the distribution system include a form of silica, an aluminum hyroxide (gibbsite or diaspore), or the Fe-containing mineral Fe3(OH)8. Dissolution of most of these minerals (except perhaps the Fe-containing minerals) is not likely to substantially affect trace-element concentrations or aesthetic characteristics of delivered water, except perhaps hardness. Precipitation of these minerals would probably be of concern only if the quantities of material involved were large enough to clog pipes or fixtures. The mineral Fe3(OH)8 was not found in the current distribution system. Some Fe-containing minerals that were identified in the distribution system were associated with relatively high contents of selected elements, including As, Cr, Cu, Mn, Pb, and Zn. However, these Fe-containing minerals were not identified as minerals likely to dissolve when the source of water was changed from ground water to surface water or a ground-water/surface-water mixture. Based on the modeled potential for calcite precipitation and additional calculations of corrosion indices ground water, surface water, and ground-water/surface-water mixtures are not likely to differ greatly in corrosion potential. In particular, surface water and ground-water/surface-water mixtures do not appear likely to dissolve large quantities of existing calcite and expose metal surfaces in the distribution system to substantially increased corrosion. Instead, modeling calculations indicate that somewhat larger masses of material would tend to precipitate from surface water or ground-water/surface-water mixtures compared to ground water alone.

Scientific Investigations Report↗
USGS2009

Analysis of Water-Quality Trends for Selected Streams in the Water Chemistry Monitoring Program, Michigan, 1998-2005

In 1998, the Michigan Department of Environmental Quality and the U.S. Geological Survey began a long-term monitoring program to evaluate the water quality of most watersheds in Michigan. Major goals of this Water-Chemistry Monitoring Program were to identify streams exceeding or not meeting State or Federal water-quality standards and to assess if constituent concentrations reflecting water quality in these streams were increasing or decreasing over time. As part of this program, water-quality data collected from 1998 to 2005 were analyzed to identify potential trends. Sixteen water-quality constituents were analyzed at 31 sites across Michigan, 28 of which had sufficient data to analyze for trends. Trend analysis on the various water-quality data was done using the uncensored Seasonal Kendall test within the computer program ESTREND. The most prevalent trend detected throughout the state was for chloride. Chloride trends were detected at 8 of the 28 sites; trends at 7 sites were increasing and the trend at 1 site was decreasing. Although no trends were detected for various nitrogen species or phosphorus, these constituents were detected at levels greater than the U.S. Environmental Protection Agency recommendations for nutrients in water. The results of the trend analysis will help to establish a baseline to evaluate future changes in water quality in Michigan streams.

Scientific Investigations Report↗
USGS2001

An estimate of chemical loads from ground water to the Grand Calumet River and Indiana Harbor Canal, northwestern Indiana

Chemical loads from ground water to the Grand Calumet River and the Indiana Harbor Canal in northwestern Indiana were estimated to aid in determining the total maximum daily load. Data from two previous studies, completed in 1987 and 1993, were used to compute loads. The first study included a ground-water-flow model. Results from this model were used to determine ground-water fluxes to eight distinct reaches of the Grand Calumet River and the Indiana Harbor Canal at assumed horizontal hydraulic conductivities of 50 and 100 feet per day. In addition, water quality data collected during the first study and a second study that further described the quality of water from wells screened in the Calumet aquifer, were used with the ground-water fluxes to compute estimates of chemical loads for selected constituents contributing to the Grand Calumet River and Indiana Harbor Canal. Constituents included trace elements, polychlorinated biphenyls, pesticides, polynuclear aromatic hydrocarbons, and selected general chemistry properties. Total dissolved solids, sulfate, chloride, and dissolved ammonia as nitrogen had the largest estimated loads to the Grand Calumet River and the Indiana Harbor Canal for any river reach. The estimated loads for total dissolved solids ranged from 239 to 12,800 kilograms per day. Dissolved iron had the largest estimated load for the trace elements and exceeded 1 kilogram per day for all river reaches for which data were available. The majority of ground-water concentrations for polychlorinated biphenyls, pesticides, and polynuclear aromatic hydrocarbons were reported as less than the method reporting limit, resulting in small computed loads to the river and canal.

Indiana↗
USGS1986

Geohydrology of the aquifers that may be affected by the surface mining of coal in the Fruitland Formation in the San Juan Basin, northwestern New Mexico

A monitoring network of 50 wells was installed from 1975 to 1979 in the surface-mineable coal area. The purpose of the network was to collect hydrologic data and to establish a data base. The hydrologic data consist of water level measurements, water chemistry, and selected aquifer characteristics. The four aquifers considered in this study are: (1) The Pictured Cliffs Sandstone; (2) coal seams and interbedded lithologic units of the Fruitland Formation; (3) overburden of the Kirtland Shale and Fruitland Formation; and (4) the alluvium along the Chaco River and its eastern and northeastern tributaries. Five sites were selected for study. Four of these sites, Western Coal Company 's lease near Fruitland, Bisti West, Kimbeto, and Ojo Encino, have surface-mineable coal. The Chaco River alluvium was selected because it is downstream from anticipated mining activity. The specific conductances of the representative water samples from selected wells in the 4 aquifers in the 5 study areas ranged from 800 to 23,000 microsiemens/cm at 25 C. The dominant cation in all samples was sodium. The water is brackish in the Pictured Cliffs Sandstone and in the coal seams and interbedded lithologic units of the Fruitland Formation. It is fresh to saline in the overburden of the Fruitland Shale and Fruitland Formation, and fresh to brackish in the Chaco River alluvium. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1998

Flow and geochemistry along shallow ground-water flowpaths in an agricultural area in southeastern Wisconsin

Water-quality and geohydrologic data were collected from 19 monitor wells and a stream in an agricultural area in southeastern Wisconsin. These sites were located along a 2,700-ft transect from a local ground-water high to the stream. The transect is approximately parallel to the horizontal direction of ground-water flow at the water table. Most of the wells were installed in unconsolidated deposits at five locations along the transect and include an upgradient well nest, a midgradient well nest, a downgradient well nest, wells in the lowland area near the stream, and wells installed in the stream bottom. The data collected from this study site were used to describe the water quality and geohydrology of the area and to explain and model the variations in water chemistry along selected ground-water flowpaths. Water samples from most wells and the stream were analyzed for major ions, nutrients, pesticides, dissolved organic carbon, aluminum, tritium, CFCs, 15N, 18O, and dissolved gases. Measurements of temperature, pH, specific conductance, and dissolved oxygen were made in the field. Concentrations of all dissolved constituents were below Wisconsin ground-water quality enforcement standards. The concentrations of both nitrate and ammonium in precipitation concentrated by evapotranspiration are roughly equal to the concentrations of either in the shallow ground waters. The nitrogen and oxygen isotope data, however, indicate that soil ammonium, ammonium fertilizer, and animal waste are possible nitrate sources. Concentrated precipitation can also supply dissolved sulfate to the shallow ground waters and may be a principal source of pesticides to the ground water. However, some input of dissolved chloride to the ground water from mineral or anthropogenic sources is necessary. X-ray diffraction analyses of samples from 2 cores show the most abundant mineral to be dolomite, with subordinate quartz, microclme, and plagioclase, and minor amounts of mica, hornblende, and chlorite. Hydraulic conductivities determined from slug tests at selected wells range from 0.006 to 55 feet per day, with most values between 0.4 and 12 feet per day. A cross-sectional ground-water flow model, representing the water-table flow system, was developed for the site and was used to identify possible ground-water flowpaths for geocli^mical modeling. The model was calibrated against measured water levels and was most sensitive to variation in recharge and hydraulic conductivity. The calibrated model shows that downward flow from shallow to deeper wells within a nest may occur at the upgradient and midgradient well nests, but that flow from each well nest travels beneath downgradient nests to the stream. Pathline and travel-time analysis performed on the calibrated flow-model output yielded travel times to well screens that range from 5.8 to 59 years with a recharge of 4 inches per yr. Recharge dates based on tritium and CFC concentrations range from pre-1955 to 1986 and are consistent with flowpaths1 and travel times in the calibrated flow model. Changes in water quality along ground-water flowpaths were evaluated using the geochemical model PHREEQC. Geochemical mole balance models of shallow ground-water formation show that the principal reaction, by an order of magnitude, is dissolution of dolomite with CO2 . Concentration factors in the mole-balance models range from 1 to 11, with most values between 5 and 10, which provides independent support for the concentration factor of 8 based on recharge estimates used in the flow model. Ground water recharging at mid- and downgradient wells is oxic and contains dissolved nitrate, whereas the ground water discharging to the stream is anoxic and contains dissolved ammonium. Redox environments were defined at each well on the basis of relative concentrations of various dissolved redox-active species. Chemically permissible flowpaths inferred from the observed sequence of redox environments at well sites are consistent with flowpaths in the ground-water flow model. The transition from nitrate in recharging ground water to ammonium in ground water discharging to the stream suggests the possibility of nitrate reduction along the flowpath. None of the techniques employed in this study, however, were able to prove the occurrence of this reaction.

Michigan, Wisconsin↗
USGS2006

Questa baseline and pre-mining ground-water quality investigation. 20. Water chemistry of the Red River and selected seeps, tributaries, and precipitation, Taos County, New Mexico, 2000-2004

As part of a multi-year project to infer the pre-mining ground-water quality at Molycorp's Questa mine site, surface-water samples of the Red River, some of its tributaries, seeps, and snow samples were collected for analysis of inorganic solutes and of water and sulfate stable isotopes in selected samples. The primary aim of this study was to document diel, storm event, and seasonal variations in water chemistry for the Red River and similar variations in water chemistry for Straight Creek, a natural analog site similar in topography, hydrology, and geology to the mine site for inferring pre-mining water-quality conditions. Red River water samples collected between 2000 and 2004 show that the largest variations in water chemistry occur during late summer rainstorms, often monsoonal in nature. Within hours, discharge of the Red River increased from 8 to 102 cubic feet per second and pH decreased from 7.80 to 4.83. The highest concentrations of metals (iron, aluminum, zinc, manganese) and sulfate also occur during such events. Low-pH and high-solute concentrations during rainstorm runoff are derived primarily from alteration 'scar' areas of naturally high mineralization combined with steep topography that exposes continually altered rock because erosion is too rapid for vegetative growth. The year 2002 was one of the driest on record, and Red River discharge reflected the low seasonal snow pack. No snowmelt peak appeared in the hydrograph record, and a late summer storm produced the highest flow for the year. Snowmelt was closer to normal during 2003 and demonstrated the dilution effect of snowmelt on water chemistry. Two diel sampling events were conducted for the Red River, one during low flow and the other during high flow, at two locations, at the Red River gaging station and just upstream from Molycorp's mill site. No discernible diel trends were observed except for dissolved zinc and manganese at the upstream site during low flow. Straight Creek drainage water was sampled periodically from 2001 to 2004 at the down stream end of surface drainage near the point at which it disappeared into the debris fan. This water has a minimal range in pH (2.7 to 3.2) but a substantial concentration range in many solutes; for example, sulfate concentrations varied from 525 to 2,660 mg/L. Many elements covary with sulfate suggesting that dilution is the primary control of the range in solute concentrations. A transect of water samples higher in the scar area were collected in October of 2003. They had a lower range in pH (2.44 to 3.05) and higher solute concentrations than those collected periodically from lower in the catchment. Water isotopes for the upper transect samples indicated slight evaporation, and in part, may account for the higher solute concentrations. Drainage waters also were collected from Hottentot, Junebug, Hansen, Little Hansen, and Goat Hill Gulch drainages. Most constituents from other scar drainage waters showed ranges of concentration similar to those of the Straight Creek waters. An exception was water collected from Goat Hill Gulch, which has some of the highest concentrations of any surface-water sample collected but also contained waste-rock leachates.

New Mexico↗
USGS2011

Response of lake chemistry to atmospheric deposition and climate in selected Class I wilderness areas in the western United States, 1993-2009

The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture Forest Service, Air Resource Management, conducted a study to evaluate long-term trends in lake-water chemistry for 64 high-elevation lakes in selected Class I wilderness areas in Colorado, Idaho, Utah, and Wyoming during 1993 to 2009. Understanding how and why lake chemistry is changing in mountain areas is essential for effectively managing and protecting high-elevation aquatic ecosystems. Trends in emissions, atmospheric deposition, and climate variables (air temperature and precipitation amount) were evaluated over a similar period of record. A main objective of the study was to determine if changes in atmospheric deposition of contaminants in the Rocky Mountain region have resulted in measurable changes in the chemistry of high-elevation lakes. A second objective was to investigate linkages between lake chemistry and air temperature and precipitation to improve understanding of the sensitivity of mountain lakes to climate variability.

Colorado;Idaho;Utah;Wyoming↗
USGS2004

Assessment of water chemistry, habitat, and benthic macroinvertebrates at selected stream-quality monitoring sites in Chester County, Pennsylvania, 1998-2000

Biological, chemical, and habitat data have been collected from a network of sites in Chester County, Pa., from 1970 to 2003 to assess stream quality. Forty sites in 6 major stream basins were sampled between 1998 and 2000. Biological data were used to determine levels of impairment in the benthic-macroinvertebrate community in Chester County streams and relate the impairment, in conjunction with chemical and habitat data, to overall stream quality. Biological data consisted of benthic-macroinvertebrate samples that were collected annually in the fall. Water-chemistry samples were collected and instream habitat was assessed in support of the biological sampling. Most sites in the network were designated as nonimpacted or slightly impacted by human activities or extreme climatic conditions on the basis of biological-metric analysis of benthic-macroinvertebrate data. Impacted sites were affected by factors, such as nutrient enrichment, erosion and sedimentation, point discharges, and droughts and floods. Streams in the Schuylkill River, Delaware River, and East Branch Brandywine Creek Basins in Chester County generally had low nutrient concentrations, except in areas affected by wastewater-treatment discharges, and stream habitat that was affected by erosion. Streams in the West Branch Brandywine, Christina, Big Elk, and Octoraro Creek Basins in Chester County generally had elevated nutrient concentrations and streambottom habitat that was affected by sediment deposition. Macroinvertebrate communities identified in samples from French Creek, Pigeon Creek (Schuylkill River Basin), and East Branch Brandywine Creek at Glenmoore consistently indicate good stream conditions and were the best conditions measured in the network. Macroinvertebrate communities identified in samples from Trout Creek (site 61), West Branch Red Clay Creek (site 55) (Christina River Basin), and Valley Creek near Atglen (site 34) (Octoraro Creek Basin) indicated fair to poor stream conditions and were the worst conditions measured in the network. Trout Creek is heavily impacted due to erosion, and Valley Creek near Atglen and West Branch Red Clay Creek are influenced by wastewater discharges. Hydrologic conditions in 1999, including a prolonged drought and a flood, influenced chemical concentrations and macroinvertebrate community structure throughout the county. Concentrations of nutrients and ions were lower in 1999 when compared to 1998 and 2000 concentrations. Macroinvertebrate communities identified in samples from 1999 contained lower numbers of individuals when compared to 1998 and 2000 but had similar community structure. Results from chemical and biological sampling in 2000 indicated that the benthic-macroinvertebrate community structure and the concentrations of nutrients and ions recovered to pre-1999 levels.

Pennsylvania↗
USGS1969

Chemical composition of selected Kansas brines as an aid to interpreting change in water chemistry with depth

Chemical analyses of approximately 1,881 samples of water from selected Kansas brines define the variations of water chemistry with depth and aquifer age. The most concentrated brines are found in the Permian rocks which occupy the intermediate section of the geologic column of this area. Salinity decreases below the Permian until the Ordovician (Arbuckle) horizon is reached and then increases until the Precambrian basement rocks are reached. Chemically, the petroleum brines studied in this small area fit the generally accepted pattern of an increase in calcium, sodium and chloride content with increasing salinity. They do not fit the often-predicted trend of increases in the calcium to chloride ratio, calcium content and salinity with depth and geologic age. The calcium to chloride ratio tends to be asymptotic to about 0.2 with increasing chloride content. Sulfate tends to decrease with increasing calcium content. Bicarbonate content is relatively constant with depth. If many of the hypotheses concerning the chemistry of petroleum brines are valid, then the brines studied are anomolous. An alternative lies in accepting the thesis that exceptions to these hypotheses are rapidly becoming the rule and that indeed we still do not have a valid and general hypothesis to explain the origin and chemistry of petroleum brines.

Kansas↗
USGS1999

Inorganic chemistry of water and bed sediment in selected tributaries of the south Umpqua River, Oregon, 1998

Ten sites on small South Umpqua River tributaries were sampled for inorganic constituents in water and streambed sediment. In aqueous samples, high concentrations (concentrations exceeding U.S. Environmental Protection Agency criterion continuous concentration for the protection of aquatic life) of zinc, copper, and cadmium were detected in Middle Creek at Silver Butte, and the concentration of zinc was high at Middle Creek near Riddle. Similar patterns of trace-element occurrence were observed in streambed-sediment samples.The dissolved aqueous load of zinc carried by Middle Creek along the stretch between the upper site (Middle Creek at Silver Butte) and the lower site (Middle Creek near Riddle) decreased by about 0.3 pounds per day. Removal of zinc from solution between the upper and lower sites on Middle Creek evidently was occurring at the time of sampling. However, zinc that leaves the aqueous phase is not necessarily permanently lost from solution. For example, zinc solubility is pH-dependent, and a shift between solid and aqueous phases towards release of zinc to solution in Middle Creek could occur with a perturbation in stream-water pH. Thus, at least two potentially significant sources of zinc may exist in Middle Creek: (1) the upstream source(s) producing the observed high aqueous zinc concentrations and (2) the streambed sediment itself (zinc-bearing solid phases and/or adsorbed zinc). Similar behavior may be exhibited by copper and cadmium because these trace elements also were present at high concentrations in streambed sediment in the Middle Creek Basin.

Oregon↗
USGS2007

Urban-Related Environmental Variables and Their Relation with Patterns in Biological Community Structure in the Fountain Creek Basin, Colorado, 2003-2005

In 2003, the U.S. Geological Survey, in cooperation with Colorado Springs City Engineering, began a study to evaluate the influence of urbanization on stream ecosystems. To accomplish this task, invertebrate, fish, stream discharge, habitat, water-chemistry, and land-use data were collected from 13 sites in the Fountain Creek basin from 2003 to 2005. The Hydrologic Index Tool was used to calculate hydrologic indices known to be related to urbanization. Response of stream hydrology to urbanization was evident among hydrologic variables that described stormflow. These indices included one measurement of high-flow magnitude, two measurements of high-flow frequency, and one measurement of stream flashiness. Habitat and selected nonstormflow water chemistry were characterized at each site. Land-use data were converted to estimates of impervious surface cover and used as the measure of urbanization annually. Correlation analysis (Spearman?s rho) was used to identify a suite of nonredundant streamflow, habitat, and water-chemistry variables that were strongly associated (rho > 0.6) with impervious surface cover but not strongly related to elevation (rho < 0.60). An exploratory multivariate analysis (BIO-ENV, PRIMER ver 6.1, Plymouth, UK) was used to create subsets of eight urban-related environmental variables that described patterns in biological community structure. The strongest and most parsimonious subset of variables describing patterns in invertebrate community structure included high flood pulse count, lower bank capacity, and nutrients. Several other combinations of environmental variables resulted in competing subsets, but these subsets always included the three variables found in the most parsimonious list. This study found that patterns in invertebrate community structure from 2003 to 2005 in the Fountain Creek basin were associated with a variety of environmental characteristics influenced by urbanization. These patterns were explained by a combination of hydrologic, habitat, and water-chemistry variables. Fish community structure showed weaker links between urban-related environmental variables and biological patterns. A conceptual model was developed that showed the influence of urban-related environmental variables and their relation to fish and invertebrate assemblages. This model should prove helpful in guiding future studies on the impacts of urbanization on aquatic systems. Long-term monitoring efforts may be needed in other drainages along the Front Range of Colorado to link urban-related variables to aquatic communities in transition zone streams.

Scientific Investigations Report↗
USGS2011

Trends in lake chemistry in response to atmospheric deposition and climate in selected Class I wilderness areas in Colorado, Idaho, Utah, and Wyoming, 1993-2009

In 2010, the U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture Forest Service, Air Resource Management, began a study to evaluate long-term trends in lake-water chemistry for 64 high-elevation lakes in selected Class I wilderness areas in Colorado, Idaho, Utah, and Wyoming during 1993 to 2009. The purpose of this report is to describe trends in the chemical composition of these high-elevation lakes. Trends in emissions, atmospheric deposition, and climate variables (air temperature and precipitation amount) are evaluated over a similar period of record to determine likely drivers of changing lake chemistry. Sulfate concentrations in precipitation decreased over the past two decades at high-elevation monitoring stations in the Rocky Mountain region. The trend in deposition chemistry is consistent with regional declines in sulfur dioxide emissions resulting from installation of emission controls at large stationary sources. Trends in nitrogen deposition were not as widespread as those for sulfate. About one-half of monitoring stations showed increases in ammonium concentrations, but few showed significant changes in nitrate concentrations. Trends in nitrogen deposition appear to be inconsistent with available emission inventories, which indicate modest declines in nitrogen emissions in the Rocky Mountain region since the mid-1990s. This discrepancy may reflect uncertainties in emission inventories or changes in atmospheric transformations of nitrogen species that may be affecting deposition processes. Analysis of long-term climate records indicates that average annual mean air temperature minimums have increased from 0.57 to 0.75 &deg;C per decade in mountain areas of the region with warming trends being more pronounced in Colorado. Trends in annual precipitation were not evident over the period 1990 to 2006, although wetter than average years during 1995 to 1997 and drier years during 2001 to 2004 caused a notable decline in precipitation in the middle part of the record.

Colorado;Idaho;Utah;Wyoming↗
USGS2007

Nutrient Enrichment in Estuaries from Discharge of Shallow Ground Water, Mt. Desert Island, Maine

Nutrient enrichment from atmospheric deposition, agricultural activities, wildlife, and domestic sources is a concern at Acadia National Park because of the potential problem of water-quality degradation and eutrophication in its estuaries. Water-quality degradation has been observed at the Park?s Bass Harbor Marsh estuary but not in Northeast Creek estuary. Previous studies at Acadia National Park have estimated nutrient inputs to estuaries from atmospheric deposition and surface-water runoff, but the importance of shallow ground water that may contain nutrients derived from domestic or other sources is unknown. Northeast Creek and Bass Harbor Marsh estuaries were studied to (1) identify shallow ground-water seeps, (2) assess the chemistry of the water discharged from selected seeps, and (3) assess the chemistry of ground water in shallow ground-water hyporheic zones. The hyporheic zone is defined here as the region beneath and lateral to a stream bed, where there is mixing of shallow ground water and surface water. This study also provides baseline chemical data for ground water in selected bedrock monitoring wells and domestic wells on Mt. Desert Island. Water samples were analyzed for concentrations of nutrients, wastewater compounds, dissolved organic carbon, pH, dissolved oxygen, temperature and specific conductance. Samples from bedrock monitoring wells also were analyzed for alkalinity, major cations and anions, and trace metals. Shallow ground-water seeps to Northeast Creek and Bass Harbor Marsh estuaries at Acadia National Park were identified and georeferenced using aerial infrared digital imagery. Monitoring included the deployment of continuously recording temperature and specific conductance sensors in the seep discharge zone to access marine or freshwater signatures related to tidal flooding, gradient-driven shallow ground-water flow, or shallow subsurface flow related to precipitation events. Many potential shallow ground-water discharge zones were identified from aerial thermal imagery during flights in May and December 2003 in both estuaries. The occurrence of ground-water seeps was confirmed using continuous and discrete measurements of temperature and specific conductance in selected seeps and in the adjacent estuaries that showed salinity anomalies reflecting the input of freshwater in these complex tidal systems. Analysis of water samples from shallow ground water in the hyporheic zone and from ground-water seeps indicated the presence of elevated concentrations of dissolved nitrogen, compared to concentrations in the adjacent estuaries and surface-water tributaries draining into the estuaries. These findings indicate that shallow ground water is a source of dissolved nitrogen to the estuaries. Orthophosphate levels were low in ground water in the hyporheic zone in Bass Harbor Marsh, but somewhat higher in one hyporheic-zone well in Northeast Creek compared with the concentrations in both estuaries that were at or below detection limits. Household wastewater-related compounds were not detected in ground water in the hyporheic zone. Analysis of water samples from domestic and bedrock monitoring wells developed in fractured bedrock indicated that concentrations of dissolved nitrogen, phosphorus, and household wastewater-related compounds were typically at or below detection, suggesting that the aquifers sampled had not been contaminated from septic sources.

Scientific Investigations Report↗
USGS2001

Effects of stream acidification and habitat on fish populations of a North American river

Water quality, physical habitat, and fisheries at sixteen reaches in the Neversink River Basin were studied during 1991-95 to identify the effects of acidic precipitation on stream-water chemistry and on selected fish-species populations, and to test the hypothesis that the degree of stream acidification affected the spatial distribution of each fish-species population. Most sites on the East Branch Neversink were strongly to severely acidified, whereas most sites on the West Branch were minimally to moderately acidified. Mean density of fish populations ranged from 0 to 2.15 fish/m 2 ; biomass ranged from 0 to 17.5 g/m 2 . Where brook trout were present, their population density ranged from 0.04 to 1.09 fish/m 2 , biomass ranged from 0.76 to 12.2 g/m 2 , and condition (K) ranged from 0.94 to 1.07. Regression analyses revealed strong relations ( r 2 ± 0.41 to 0.99; p ≤ 0.05) between characteristics of the two most common species (brook trout and slimy sculpin) populations and mean concentrations of inorganic monomeric aluminum (Al im ), pH, Si, K + , NO 3 - , NH 4 + , DOC, Ca 2+ , and Na + ; acid neutralizing capacity (ANC); and water temperature. Stream acidification may have adversely affected fish populations at most East Branch sites, but in other parts of the Neversink River Basin these effects were masked or mitigated by other physical habitat, geochemical, and biological factors.

New York↗