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At least 343 records · Page 19Linked to original sources
USGS1992

The stable isotope geochemistry of acid sulfate alteration

Acid sulfate wall-rock alteration, characterized by the assemblage alunite + kaolinite + quartz + or - pyrite, results from base leaching by fluids concentrated in H 2 SO 4 . Requisite amounts of H 2 SO 4 can be generated by different mechanisms in three principal geologic environments: (1) by atmospheric oxidation of sulfides in the supergene environment, (2) by atmospheric oxidation at the water table in the steam-heated environment of H 2 S released by deeper, boiling fluids, and (3) by the disproportionation of magmatic SO 2 to H 2 S and H 2 SO 4 during condensation of a magmatic vapor plume at intermediate depths in magmatic hydrothermal environments in silicic and andesitic volcanic terranes. In addition, coarse vein alunite may form in a magmatic steam environment from rapid release of an SO 2 -rich magmatic vapor phase at high temperature and low pressure or from the oxidation of a more reduced magmatic vapor by entrained atmospheric oxygen in the carapace of a volcanic edifice.Alunite [KAl 3 (SO 4 ) 2 (OH) 6 ] contains four stable isotope sites and complete analyses (delta D, delta 18 O (sub SO 4 ) , delta 18 O OH , and delta 34 S) are now possible. Except for delta 18 O OH in magmatic hydrothermal alunites, primary values are usually retained. In cooperation with many colleagues, over 500 measurements have been made on nearly 200 samples of alunite and associated minerals from 23 localities, and 55 additional analyses have been taken from the literature. This survey confirms that kinetic factors play an important role in the stable isotope systematics of alunite and acid sulfate alteration. To a very large extent they form the isotopic basis for distinguishing between environments of acid sulfate alteration, and they provide important insights into attendant processes. Stable isotope analyses of alunite, often in combination with those on associated sulfides and kaolinite, permit recognition of environments of formation and provide information on origins of components, processes (including rates), physical-chemical environments, and temperatures of formation.Supergene acid sulfate alteration may form over any sulfide zone when it is raised above the water table by tectonics or exposed by erosion. It may overprint earlier acid sulfate assemblages, particularly the magmatic hydrothermal assemblages which are pyrite rich such as at El Salvador, Chile; Rodalquilar, Spain; and Goldfield, Nevada. Supergene alunite normally has delta 34 S values virtually identical to precursor sulfides unless bacteriogenic reduction of aqueous sulfate takes place in standing pools of water. delta D values are close to that of local meteoric water unless extensive evaporation occurs. delta D and delta 18 O OH values of supergene alunites from a range of latitudes fall in a broad zone parallel to the meteoric water line much the way delta D and delta 18 O values of associated halloysite-kaolinite fall near the kaolinite line of Savin and Epstein (1970). delta 18 O (sub SO 4 ) values are kinetically controlled and will reflect the hydro-geochemistry of the environment. delta 18 O (sub SO 4 -OH) alues are grossly out of equilibrium and large negative values are definitive of a supergene origin.In steam-heated environments, such as those at the Tolfa district, Italy, and Marysvale, Utah, and numerous modern geothermal systems, acid sulfate alteration zones are characterized by pronounced vertical zoning. Such acid sulfate alteration may occur over adularia-sericite-type base and precious metal ore deposits such as the one at Buckskin, Nevada. Initial delta 18 O (sub SO 4 ) and delta 34 S values are kinetically controlled, but delta 18 O (sub SO 4 ) values usually reach equilibrium with fluids, and even delta 34 S values may reflect partial exchange with H 2 S where the residence time of aqueous sulfate is sufficient. Most alunites of steam-heated origin have delta 34 S values the same as those of precursor H 2 S (and as related sulfides, if present) and delta D values similar to that of local meteoric water. In the samples analyzed, most delta 18 O (sub SO 4 -OH) values give reasonable temperatures of 90 degrees to 160 degrees C, indicating that delta 18 O (sub SO 4 ) and delta 18 O OH values reflect a close approach to equilibrium with the fluid. The delta 18 O (sub SO 4 ) and delta 18 O OH values also reflect the degree of exchange of the meteoric fluids with wall rock. Coeval kaolinites typically have delta 18 O and delta D values to the left of the kaolinitc line.Magmatic hydrothermal, acid sulfate alteration zones in near-surface epithermal deposits such as Summitville, Colorado. Julcani, Peru, and Red Mountain and Lake City, Colorado, are characterized by vertical orientation and horizontal zoning, the presence of coeval pyrite, PO 4 analogues of alunite, zunyite, and later gold, pyrite and enargite, and often other Cu-As-Sb-S minerals. Acid sulfate alteration assemblages also occur as late stages in the porphyry-copper deposit at E1 Salvador, Chile. In the examples studied, magmatic hydrothermal alunites have delta D values close to those for magmatic water. delta 34 S values are 16 to 28 per mil larger than those for associated pyrite, reflecting equilibrium between aqueous H 2 S and SO 4 formed by the disproportionation of magmatically derived SO 2 . delta 18 O (sub SO 4 ) values are usually 8 to 18 per mil and vary systematically with delta 34 S values, reflecting variations in temperature and/or H 2 S/SO 4 fluid ratios. Further variation in delta 18 O (sub SO 4 ) values may result if SO 2 condenses in mixed magmatic meteoric water fluids. delta 18 O (sub SO (sub 4-) OH) values of magmatic hydrothermal alunites are generally unsuitable for temperature determinations because of retrograde exchange in the OH site, but delta 34 S (sub alunite-pyrite) values provide reliable temperature estimates.Magmatic steam environments appear to occur over a range of depths and are characterized by monomineralic veins of coarse alunite in variably alunitized and kaolinized wall rocks containing minor pyrite. Alunite formed in the magmatic steam environment can usually be recognized by delta 34 S near delta 34 S (sub Sigma S) values and delta D and delta 18 O (sub SO 4 ) values near magmatic values. Magmatic steam alunite differs from magmatic hydrothermal alunite by having delta 34 S close to delta 34 S (sub Sigma S) values of the system. delta 18 O (sub SO (sub 4-) OH) values of most magmatic steam alunite give temperatures ranging from 90 degrees to 210 degrees C but, for reasons which are not understood, some temperatures as well as calculated delta 18 O (sub H 2 O) values are too low for presumed precipitation from a magmatic vapor phase. Magmatic steam environments may occur over porphyry-type mineralization as at Red Mountain, Colorado, and Alunite Ridge, Utah, and over or adjacent to adularia-sericite-type deposits in volcanic domes as at Cactus, California.

Economic Geology↗
USGS2008

Whole-stream response to nitrate loading in three streams draining agricultural landscapes

Physical, chemical, hydrologic, and biologic factors affecting nitrate (NO 3 &minus; ) removal were evaluated in three agricultural streams draining orchard/dairy and row crop settings. Using 3-d &ldquo;snapshots&rdquo; during biotically active periods, we estimated reach-level NO 3 &minus; sources, NO 3 &minus; mass balance, in-stream processing (nitrification, denitrification, and NO 3 &minus; uptake), and NO 3 &minus; retention potential associated with surface water transport and ground water discharge. Ground water contributed 5 to 11% to stream discharge along the study reaches and 8 to 42% of gross NO 3 &minus; input. Streambed processes potentially reduced 45 to 75% of ground water NO 3 &minus; before discharge to surface water. In all streams, transient storage was of little importance for surface water NO 3 &minus; retention. Estimated nitrification (1.6&ndash;4.4 mg N m &minus;2 h &minus;1 ) and unamended denitrification rates (2.0&ndash;16.3 mg N m &minus;2 h &minus;1 ) in sediment slurries were high relative to pristine streams. Denitrification of NO 3 &minus; was largely independent of nitrification because both stream and ground water were sources of NO 3 &minus; Unamended denitrification rates extrapolated to the reach-scale accounted for <5% of NO 3 &minus; exported from the reaches minimally reducing downstream loads. Nitrate retention as a percentage of gross NO 3 &minus; inputs was >30% in an organic-poor, autotrophic stream with the lowest denitrification potentials and highest benthic chlorophyll a , photosynthesis/respiration ratio, pH, dissolved oxygen, and diurnal NO 3 &minus; variation. Biotic processing potentially removed 75% of ground water NO 3 &minus; at this site, suggesting an important role for photosynthetic assimilation of ground water NO 3 &minus; relative to subsurface denitrification as water passed directly through benthic diatom beds.

Journal of Environmental Quality↗
USGS2000

Estuaries of the northeastern United States: Habitat and land use signatures

Geographic signatures are physical, chemical, biotic, and human-induced characteristics or processes that help define similar or unique features of estuaries along latitudinal or geographic gradients. Geomorphologically, estuaries of the northeastern U.S., from the Hudson River estuary and northward along the Gulf of Maine shoreline, are highly diverse because of a complex bedrock geology and glacial history. Back-barrier estuaries and lagoons occur within the northeast region, but the dominant type is the drowned-river valley, often with rocky shores. Tidal range and mean depth of northeast estuaries are generally greater when compared to estuaries of the more southern U.S. Atlantic coast and Gulf of Mexico. Because of small estuarine drainage basins, low riverine flows, a bedrock substrate, and dense forest cover, sediment loads in northeast estuaries are generally quite low and water clarity is high. Tidal marshes, seagrass meadows, intertidal mudflats, and rocky shores represent major habitat types that fringe northeast estuaries, supporting commercially-important fauna, forage nekton and benthos, and coastal bird communities, while also serving as links between deeper estuarine waters and habitats through detritus-based pathways. Regarding land use and water quality trends, portions of the northeast have a history of over a century of intense urbanization as reflected in increased total nitrogen and total phosphorus loadings to estuaries, with wastewater treatment facilities and atmospheric deposition being major sources. Agricultural inputs are relatively minor throughout the northeast, with relative importance increasing for coastal plain estuaries. Identifying geographic signatures provides an objective means for comparing the structure function, and processes of estuaries along latitudinal gradients.

Connecticut, Maine, Massachusetts, New Hampshire, ↗
USGS2007

Restoration technology branch

The mission of Leetown Science Center (LSC), Restoration Technology Branch (RTB) is to conduct research needed to restore or protect the chemical, physical and biological integrity of desirable aquatic systems.

Fact Sheet↗
USGS1977

Analysis of street sweepings, Portland, Oregon

A brief study involving collection and analysis of street sweepings was undertaken to provide the U.S. Army Corps of Engineers with data on physical, chemical, and biological characteristics of dust and dirt accumulating on Portland streets. Most of the analyses selected were based on the pollutant loads predicted by the Storage, Treatment, Overflow, and Runoff Model (STORM). Five different basins were selected for sampling, and samples were collected three times in each basin. Because the literature reports no methodology for analysis of dust and dirt, the analytical methodology is described in detail. Results of the analyses are summarized in table 1.

Oregon↗
USGS1960

Beryl-bearing pegmatites in the Ruby Mountains and other areas in Nevada and northwestern Arizona

Pegmatite occurs widely in Nevada and northwestern Arizona, but little mining has been done for such pegmatite minerals as mica, feldspar, beryl, and lepidolite. Reconnaissance for beryl-bearing pegmatite in Nevada and in part of Mohave County, Ariz., and detailed studies in the Dawley Canyon area, Elko County, Nev., have shown that beryl occurs in at least 11 districts in the region. Muscovite has been prospected or mined in the Ruby and Virgin Mountains, Nev., and in Mohave County, Ariz. Feldspar has been mined in the southern part of the region near Kingman, Ariz., and in Clark County, Nev. The pegmatites in the region range in age from Precambrian to late Mesozoic or Tertiary. Among the pegmatite minerals found or reported in the districts studied are beryl, chrysoberyl, scheelite, wolframite, garnet, tourmaline, fluorite, apatite, sphene, allanite, samarskite, euxenite, gadolinite, monazite, autunite, columbite-tantalite, lepidolite, molybdenite, and pyrite and other sulflde minerals. The principal beryl-bearing pegmatites examined are in the Oreana and Lakeview (Humboldt Canyon) areas, Pershing County; the Dawley Canyon area in the Ruby Mountains, Elko County, Nev.; and on the Hummingbird claims in the Virgin Mountains, Mohave County, Ariz. Beryl has also been reported in the Marietta district, Mineral County; the Sylvania district, Esmeralda County; near Crescent Peak and near Searchlight, Clark County, Nev.; and in the Painted Desert near Hoover Dam, Mohave County, Ariz. Pegmatites are abundant in the Ruby Mountains, chiefly north of the granite stock at Harrison Pass. In the Dawley Canyon area of 2.6 square miles at least 350 pegmatite dikes more than 1 foot thick were mapped, and beryl was found in small quantities in at least 100 of these dikes. Four of these dikes exceed 20 feet in thickness, and 1 is 55 feet thick. A few pegmatites were also examined in the Corral Creek, Gilbert Canyon, and Hankins Canyon areas in the Ruby Mountains. The pegmatite dikes in the Dawley Canyon area intrude granite and metamorphic rocks which consist chiefly of quartzite and schist of probable Early Cambrian age. The granite is of two types: a biotite-muscovite granite that forms the main mass of the stock and albite granite that occurs in the metamorphic rocks near the borders of the stock. The pegmatites were emplaced chiefly along fractures in the granite and along schistosity or bedding planes in the metamorphic rocks. Many of the Dawley Canyon pegmatite dikes are zoned, having several rock units of contrasting mineralogy or grain size formed successively from the walls inward. Aplitic units occur either as zones or in irregular positions in the pegmatite dikes and are a distinctive feature of the Dawley Canyon pegmatites. Some of the aplitic and fine-grained pegmatite units are characterized by thin layers of garnet crystals, forming many parallel bands on outcrop surfaces. The occurrence of aplitic and pegmatitic textures in the same dike presumably indicates abrupt changes in physical-chemical conditions during crystallization, such as changes in viscosity and in content of volatile constituents. Concentrations of 0.1 percent or more beryl, locally more than 1 percent, occur in certain zones in the Dawley Canyon pegmatites. Spectrographic analyses of 23 samples indicate that the BeO content ranges from 0.0017 to 0.003 percent in the albite granite, from ,0.0013 to 0.039 percent in aplitic units in pegmatite, from 0.0005 to 0.10 percent in coarse-grained pegmatite, and from less than 0.0001 to 0.0004 percent in massive quartz veins. The scheelite-beryl deposits at Oreana and in Humboldt Canyon, Pershing County, are rich in beryllium. Twelve samples from the Lakeview (Humboldt Canyon) deposit range from 0.018 to 0.11 percent BeO, but underground crosscuts have failed to intersect similar rock at depth. Beryl locally constitutes as much as 10 percent of the pegmatitic ore at Oreana. The beryl was not recovered during tungsten mining at Oreana and is now in the tailings of the mill at Toulon, Nev. The percentage of beryl is lower than the Oreana ore because of dilution by tailings from other ores milled at Toulon. Beryl has been found in many pegmatite dikes in the Virgin Mountains. Both beryl and chrysoberyl occur in dikes on the Hummingbird claims, north of Virgin Peak, in Mohave County, Ariz. Spectrographic analyses of 5 representative samples of the principal dike on the Hummingbird claims range from 0.055 to 0.11 percent BeO.

Arizona, Nevada↗
USGS1982

Water-data program of the U.S. Geological Survey

The U.S. Geological Survey is the principal Federal agency responsible for the collection of hydrologic data needed for the planning, development, use, and management of the Nation 's water resources. These data are the foundation necessary for conducting analytical and interpretive appraisals describing the occurrence and availability of surface and ground waters, and their physical, chemical, and biological characteristics. The data are likewise required for basic and problem-oriented research in hydraulics, hydrology, and related fields. Hydrologic data collection by the Geological Survey began in 1894. Current operations include about 17,000 stations for collection of river, lake, and reservoir data; about 27,000 wells for collection of ground-water data; and almost 17,000 stations for collection of water-quality information. These activities are described as well as the means by which the data are made available, and how the program is coordinated with other agencies. (USGS)

Circular↗
USGS2011

Geophysical, geochemical, mineralogical, and enivronmental data for rock samples collected in a mineralized volcanic environment, upper Animas River watershed, Colorado

This report provides analyses of 90 rock samples collected in the upper Animas River watershed near Silverton, Colo., from 2001 to 2007. The samples are analyzed for geophysical, geochemical, mineralogical, and environmental rock properties of acid neutralizing capacity and net acid production. The database is derived from both published (n=68) and unpublished (n=32) data. New for all samples are geophysical measurements of electrical resistivity, density, and porosity. Rock samples were acquired from 12 geologic units that include key Tertiary volcanic and plutonic lithologies, all with varying degrees of alteration. The purpose of this study is to * provide a comprehensive and complete record of U.S. Geological Survey rock samples collected and similarly analyzed in the upper Animas River watershed for various physical, chemical, and geoenvironmental properties; * provide measurements of geophysical rock properties of lithologic units to establish ground truth with respect to watershed-scale airborne magnetic and electrical survey data; * use the data to interpret the airborne geophysical anomalies to characterize rocks in terms of acid neutralizing capacity or net acid production; and * provide measurements to study the geochemical, mineralogical, and geophysical characteristics of rocks having weak to extreme degrees of alteration and to develop an understanding of how these characteristics change with alteration type. Data are provided in two digital formats: an Arc/Info geodatabase and a Microsoft Excel spreadsheet.

Data Series↗
USGS1998

Simulating transport of volatile organic compounds in the unsaturated zone using the computer model R-UNSAT

Subsurface spills of gasoline and other petroleum products are a common environmental problem throughout the industrialized world. The U.S. Environmental Protection Agency has estimated that 40 percent of the more than 200,000 retail service stations in the United States have had accidental releases of petroleum hydrocarbons to the subsurface (U.S. Environmental Protection Agency, 1991). Restoration of a contaminated aquifer to regulatory standards is a technically difficult problem even when best engineering strategies are applied. Natural attenuation, a remediation strategy that relies on intrinsic physical, chemical, and biological processes to decrease contaminant concentrations, is gaining widespread acceptance in aquifer restoration efforts (Tremblay and others, 1995). The potential for successful remediation by natural attenuation depends on the fate of the organic constituents of the spilled product, which may include additives such as methyl tert-butyl ether (MTBE). These compounds can dissolve in ground water, adsorb to subsurface sediments, volatilize and diffuse through the unsaturated zone, or undergo chemical and biological reactions (fig. 1). Volatilization and biodegradation near the water table are two processes that can contribute significantly to the natural attenuation of volatile organic compounds (VOCs) in shallow ground water (McAllister and Chiang, 1994). To date, quantitative information on the rates at which these processes occur has been limited. R-UNSAT, a computer model designed for quantifying rates of volatilization and biodegradation of organic compounds near the water table, was developed and documented by the U.S. Geological Survey (USGS) and is now available to the public. R-UNSAT also can be applied, however, to other unsaturated-zone transport problems that involve gas diffusion, such as radon migration, and the deposition of compounds from the atmosphere to shallow ground water. This fact sheet describes the transport model and demonstrates its capabilities through applications to point- and nonpoint-source contamination.

Fact Sheet↗
USGS2003

Surface Water in Hawaii

Surface water in Hawaii is a valued resource as well as a potential threat to human lives and property. The surface-water resources of Hawaii are of significant economic, ecologic, cultural, and aesthetic importance. Streams supply more than 50 percent of the irrigation water in Hawaii, and although streams supply only a few percent of the drinking water statewide, surface water is the main source of drinking water in some places. Streams also are a source of hydroelectric power, provide important riparian and instream habitats for many unique native species, support traditional and customary Hawaiian gathering rights and the practice of taro cultivation, and possess valued aesthetic qualities. Streams affect the physical, chemical, and aesthetic quality of receiving waters, such as estuaries, bays, and nearshore waters, which are critical to the tourism-based economy of the islands. Streams in Hawaii pose a danger because of their flashy nature; a stream's stage, or water level, can rise several feet in less than an hour during periods of intense rainfall. Streams in Hawaii are flashy because rainfall is intense, drainage basins are small, basins and streams are steep, and channel storage is limited. Streamflow generated during periods of heavy rainfall has led to loss of property and human lives in Hawaii. Most Hawaiian streams originate in the mountainous interiors of the islands and terminate at the coast. Streams are significant sculptors of the Hawaiian landscape because of the erosive power of the water they convey. In geologically young areas, such as much of the southern part of the island of Hawaii, well-defined stream channels have not developed because the permeability of the surface rocks generally is so high that rainfall infiltrates before flowing for significant distances on the surface. In geologically older areas that have received significant rainfall, streams and mass wasting have carved out large valleys.

Fact Sheet↗
USGS2001

Discharge between San Antonio Bay and Aransas Bay, southern Gulf Coast, Texas, May-September 1999

Along the Gulf Coast of Texas, many estuaries and bays are important habitat and nurseries for aquatic life. San Antonio Bay and Aransas Bay, located about 50 and 30 miles northeast, respectively, of Corpus Christi, are two important estuarine nurseries on the southern Gulf Coast of Texas (fig. 1). According to the Texas Parks and Wildlife Department, “Almost 80 percent of the seagrasses [along the Texas Gulf Coast] are located in the Laguna Madre, an estuary that begins just south of Corpus Christi Bay and runs southward 140 miles to South Padre Island. Most of the remaining seagrasses, about 45,000 acres, are located in the heavily traveled San Antonio, Aransas and Corpus Christi Bay areas” (Shook, 2000). Population growth has led to greater demands on water supplies in Texas. The Texas Water Development Board, the Texas Parks and Wildlife Department, and the Texas Natural Resource Conservation Commission have the cooperative task of determining inflows required to maintain the ecological health of the State’s streams, rivers, bays, and estuaries. To determine these inflow requirements, the three agencies collect data and conduct studies on the need for instream flows and freshwater/ saline water inflows to Texas estuaries. To assist in the determination of freshwater inflow requirements, the U.S. Geological Survey (USGS), in cooperation with the Texas Water Development Board, conducted a hydrographic survey of discharge (flow) between San Antonio Bay and Aransas Bay during the period May–September 1999. Automated instrumentation and acoustic technology were used to maximize the amount and quality of data that were collected, while minimizing personnel requirements. This report documents the discharge measured at two sites between the bays during May–September 1999 and describes the influences of meteorologic (wind and tidal) and hydrologic (freshwater inflow) conditions on discharge between the two bays. The movement of water between the bays is controlled primarily by prevailing winds, tidal fluctuations, and freshwater inflows. An adequate understanding of mixing and physical exchange in the estuarine waters is fundamental to the assessment of the physical, chemical, and biological processes governing the aquatic system.

Texas↗
USGS1996

What affects water quality in the Upper Colorado River basin?

The Upper Colorado River Basin is 1 of 60 study units selected for water-quality assessment by the U.S. Geological Survey as part of the National Water-Quality Assessment program. Understanding the environmental setting of the Upper Colorado River Basin study unit is important in evaluating water-quality issues in the basin. Information about the environmental setting identifies the basin characteristics and includes natural and human factors that affect the physical, chemical, and biological quality of water in the basin. This information has been used to design surface-water- and ground-water-quality sampling networks in the basin to assess overall water quality of the basin

Colorado↗
USGS2004

Fort Collins Science Center: Aquatic Systems and Technology Applications

Land and water management agencies are responsible for restoring and conserving our nation's natural resources. However, they face increasing, often competing demands for those resources, which can result in alteration or loss of critical riverine, riparian, wetland, and terrestrial habitats. Land and resource managers may be in federal, state, or local government, but all have the same need for quantitative, objective, science-based information that helps them plan, manage, and conserve the natural resources within their purview. The Aquatic Systems and Technology Applications Branch (ASTA) of the Fort Collins Science Center (FORT) encompasses a wide variety of studies, investigations, and activities that are related to providing tools and capabilities for natural resource managers. ASTA's mission is to provide managers with credible science-based information on the interrelationships among the physical, chemical, aquatic, and biological natural resources in river basins for resource management decision-making. Branch goals are to: develop and apply specific models and analysis tools for resource management issues, identify habitat and biological linkages in river corridor environments, design and evaluate specific water quality improvement features, define economic measures for natural resource benefits, investigate altered flow regime effects on native fish populations, characterize sediment transport effects in river corridor environments, and utilize advanced technology to evaluate landscape-scale changes in river basins.

Fact Sheet↗
USGS2007

Harmful algal blooms

What are Harmful Algal Blooms (HABs)? Freshwater and marine harmful algal blooms (HABs) can occur anytime water use is impaired due to excessive accumulations of algae. HAB occurrence is affected by a complex set of physical, chemical, biological, hydrological, and meteorological conditions making it difficult to isolate specific causative environmental factors. Potential impairments include reduction in water quality, accumulation of malodorous scums in beach areas, algal production of toxins potent enough to poison both aquatic and terrestrial organisms, and algal production of taste-and-odor compounds that cause unpalatable drinking water and fish. HABs are a global problem, and toxic freshwater and (or) marine algae have been implicated in human and animal illness and death in over 45 countries worldwide and in at least 27 U.S. States (Yoo and others, 1995; Chorus and Bartram, 1999; Huisman and others, 2005).

Fact Sheet↗
USGS2009

Fort Collins Science Center Ecosystem Dynamics Branch

Complex natural resource issues require understanding a web of interactions among ecosystem components that are (1) interdisciplinary, encompassing physical, chemical, and biological processes; (2) spatially complex, involving movements of animals, water, and airborne materials across a range of landscapes and jurisdictions; and (3) temporally complex, occurring over days, weeks, or years, sometimes involving response lags to alteration or exhibiting large natural variation. Scientists in the Ecosystem Dynamics Branch of the U.S. Geological Survey, Fort Collins Science Center, investigate a diversity of these complex natural resource questions at the landscape and systems levels. This Fact Sheet describes the work of the Ecosystems Dynamics Branch, which is focused on energy and land use, climate change and long-term integrated assessments, herbivore-ecosystem interactions, fire and post-fire restoration, and environmental flows and river restoration.

Fact Sheet↗
USGS2010

Estuaries of the Greater Everglades Ecosystem: Laboratories of Long-term Change

Restoring the greater Everglades ecosystem of south Florida is arguably the largest ecosystem restoration effort to date. A critical goal is to return more natural patterns of flow through south Florida wetlands and into the estuaries, but development of realistic targets requires acknowledgement that ecosystems are constantly evolving and changing in response to a variety of natural and human-driven stressors. Examination of ecosystems over long periods of time requires analysis of sedimentary records, such as those deposited in the wetlands and estuaries of south Florida. As sediment accumulates, it preserves information about the animals and plants that lived in the environment and the physical, chemical, and climatic conditions present. One of the methods used to interpret this information is paleoecology-the study of the ecology of previously living organisms. Paleoecologic investigations of south Florida estuaries provide quantitative data on historical variability of salinity and trends that may be applied to statistical models to estimate historical freshwater flow. These data provide a unique context to estimate future ecosystem response to changes related to restoration activities and predicted changes in sea level and temperature, thus increasing the likelihood of successful and sustainable ecosystem restoration.

Fact Sheet↗
USGS2014

Effects of wastewater effluent discharge on stream quality in Indian Creek, Johnson County, Kansas

Contaminants from point and other urban sources affect stream quality in Indian Creek, which is one of the most urban drainage basins in Johnson County, Kansas. The Johnson County Douglas L. Smith Middle Basin and Tomahawk Creek Wastewater Treatment Facilities discharge to Indian Creek. Data collected by the U.S. Geological Survey, in cooperation with Johnson County Wastewater, during June 2004 through June 2013 were used to evaluate stream quality in Indian Creek. This fact sheet summarizes the effects of wastewater effluent discharge on physical, chemical, and biological conditions in Indian Creek downstream from the Douglas L. Smith Middle Basin and Tomahawk Creek Wastewater Treatment Facilities.

Kansas↗