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At least 37 records · Page 2Linked to original sources
USGS2014

Understanding thermodynamic relationships and geochemical mass balances from catchment to coast: A tribute to the life and career of Owen P. Bricker III

This special volume of aquatic geochemistry is dedicated to the memory of Owen Peterson Bricker III (1936–2011) and serves as a tribute to his life and career. Owen had a distinguished and productive research career in both academics at Johns Hopkins University (Fig. 1) and as a public servant with the Maryland Geological Survey, the US Environmental Protection Agency, and the US Geological Survey. He was a pioneer and leader in aqueous geochemistry, who applied a study approach that quantified mineral weathering reactions and equilibrium thermodynamic relations to better understand the chemical evolution of stream water in small watersheds. He will be especially remembered for his efforts to establish rigorous field studies in small catchments around the United States as a means of quantifying the sources of acid-neutralizing capacity that affect the chemical status and biological health of natural waters.

Aquatic Geochemistry↗
USGS1990

Geochemistry of reduced gas related to serpentinization of the Zambales ophiolite, Philippines

Methane-hydrogen gas seeps with mantle-like C and noble gas isotopic characteristics issue from partially serpentinized ultramafic rocks in the Zambales ophiolite, Philippines. New measurements of noble gas and 14 C isotope abundances, rock/mixed-volatile equilibrium calculations, and previous chemical and isotopic data suggest that these reduced gases are products of periodotite hydration. The gas seeps are produced in rock-dominated zones of serpentinization, and similar gases may be ubiquitous in ultramafic terranes undergoing serpentinization.

Applied Geochemistry↗
USGS2015

Modeling and management of pit lake water chemistry 1: Theory

Pit lakes are permanent hydrologic/landscape features that can result from open pit mining for metals, coal, uranium, diamonds, oil sands, and aggregates. Risks associated with pit lakes include local and regional impacts to water quality and related impacts to aquatic and terrestrial ecosystems. Stakeholders rely on predictive models of water chemistry to prepare for and manage these risks. This paper is the first of a two part series on the modeling and management of pit lakes. Herein, we review approaches that have been used to quantify wall-rock runoff geochemistry, wall-rock leachate geochemistry, pit lake water balance, pit lake limnology (i.e. extent of vertical mixing), and pit lake water quality, and conclude with guidance on the application of models within the mine life cycle. The purpose of this paper is to better prepare stakeholders, including future modelers, mine managers, consultants, permitting agencies, land management agencies, regulators, research scientists, academics, and other interested parties, for the challenges of predicting and managing future pit lakes in un-mined areas.

Applied Geochemistry↗
USGS2026

Elemental and isotope geochemistry of Smackover Formation brines in Alabama and Arkansas: Implications for fluid mixing and water-rock interaction

This study investigates the geochemical characteristics of brines within the Upper Jurassic Smackover Formation in Alabama and Arkansas through elemental and isotopic analyses and geochemical modeling to reveal the extent and nature of fluid mixing and water-rock interactions. Smackover Formation brines exhibit Na-Cl-Ca hydrogeochemical facies and sulfate depletion relative to seawater. Lower sulfate concentrations, coupled with high H 2 S concentrations in some brines (0-364 mg/L) at temperatures >80°C, suggest that thermochemical sulfate reduction occurred. Cl/Br and Na/Br ratios indicate that salinity was controlled by the mixing of meteoric water with evaporated seawater that had reached halite saturation, rather than by halite dissolution. The δ 18 O and δ 2 H values of the brines also suggest mixing between meteoric water and evaporated seawater that had reached gypsum and halite saturation. Geochemical modeling of seawater evaporation predicts a Cl-Na or Cl-Mg facies after halite saturation, contrasting with the observed Cl-Ca dominance of the Smackover Formation brines. The Ca-enriched brines may have evolved from Cl-Mg-dominated evaporated seawater through dolomitization of limestone. The 87 Sr/ 86 Sr ratios range from 0.70740 to 0.71048, higher than the average of Jurassic seawater (0.707). The non-linear relationship between 87 Sr/ 86 Sr and 1000/Sr suggests alteration of brine geochemistry by fluid mixing or by inputs from Sr and 87 Sr-enriched rock sources. Lithium concentrations are positively correlated with 87 Sr/ 86 Sr ratios and TDS in brines enriched in these constituents. These correlations suggest deeper-seated geogenic sources and have implications for Li exploration in the northern Gulf Coast basin. Normal faults associated with the pre-Jurassic topography may have provided potential pathways for brine migration into the Smackover Formation under the influence of overpressure or thermohaline convection in the Gulf Coast.

Alabama↗
USGS2009

Process recognition in multi-element soil and stream-sediment geochemical data

Stream-sediment and soil geochemical data from the Upper and Lower Coastal Plains of South Carolina (USA) were studied to determine relationships between soils and stream sediments. From multi-element associations, characteristic compositions were determined for both media. Primary associations of elements reflect mineralogy, including heavy minerals, carbonates and clays, and the effects of groundwater. The effects of groundwater on element concentrations are more evident in soils than stream sediments. A "winnowing index" was created using ratios of Th to Al that revealed differing erosional and depositional environments. Both soils and stream sediments from the Upper and Lower Coastal Plains show derivation from similar materials and subsequent similar multi-element relationships, but have some distinct differences. In the Lower Coastal Plain, soils have high values of elements concentrated in heavy minerals (Ce, Y, Th) that grade into high values of elements concentrated into finer-grain-size, lower-density materials, primarily comprised of carbonates and feldspar minerals (Mg, Ca, Na, K, Al). These gradational trends in mineralogy and geochemistry are inferred to reflect reworking of materials during marine transgressions and regressions. Upper Coastal Plain stream-sediment geochemistry shows a higher winnowing index relative to soil geochemistry. A comparison of the 4 media (Upper Coastal Plain soils and stream sediments and Lower Coastal Plain soils and stream sediments) shows that Upper Coastal Plain stream sediments have a higher winnowing index and a higher concentration of elements contained within heavy minerals, whereas Lower Coastal Plain stream sediments show a strong correlation between elements typically contained within clays. It is not possible to calculate a functional relationship between stream sediment-soil compositions for all elements due to the complex history of weathering, deposition, reworking and re-deposition. However, depending on the spatial separation of the stream-sediment and soil samples, some elements are more highly correlated than others. Crown Copyright ?? 2009.

Applied Geochemistry↗
USGS1991

Proposed method of hydrogeochemical exploration for salt deposits using ClBr ratios, Eastern Province, Kingdom of Saudi Arabia

Despite the value of the salt (NaCl) and brine used by the chemical industry, geochemical prospecting techniques are not customarily employed in the search for these raw materials. In this study, Br geochemistry is used as the basis for a proposed hydrogeochemical prospecting technique that was designed to search for shallow halite beds in the Eastern Province of the Kingdom of Saudi Arabia. Near-surface brine samples were collected at Sabkhah Jayb Uwayyid, both directly above and distant from a buried salt bed. Brine samples collected both directly above and offset to the north-west of the salt bed had Cl Br ratios > 8000. The regional background Cl Br ratio of fresh nonmarime ground water is ≈300. The large range in Cl Br ratios and the association of high Cl Br ratios with the buried salt body suggest that the ratio can be useful in hydrogeochemical prospecting for sibakh-associated, shallow salt bodies.

Applied Geochemistry↗
USGS2011

The role of critical zone processes in the evolution of the Prairie Pothole Region wetlands

The Prairie Pothole Region, which occupies 900,000 km2 of the north central USA and south central Canada, is one of the most important ecosystems in North America. It is characterized by millions of small wetlands whose chemistry is highly variable over short distances. The study involved the geochemistry of surface sediments, wetland water, and groundwater in the Cottonwood Lakes area of North Dakota, USA, whose 92 ha includes the dominant wetland hydrologic settings. The data show that oxygenated groundwater interacting with pyrite resident in a component of surficial glacial till derived from the marine Pierre Shale Formation has, over long periods of time, focused SO 4 2 - -bearing fluids from upland areas to topographically low areas. In these low areas, SO 4 2 - -enriched groundwater and wetlands have evolved, as has the CaSO4 mineral gypsum. Sulfur isotope data support the conclusion that isotopically light pyrite from marine shale is the source of SO 4 2 - . Literature data on wetland water composition suggests that this process has taken place over a large area in North Dakota.

North Dakota↗
USGS1990

Hydrocarbon geochemistry of hydrothermally generated petroleum from Escanaba trough, offshore California U.S.A.

In 1986, three samples of sulfide-rich sediments, impregnated with hydrothermally derived, asphaltic petroleum, were recovered in a dredge and by submersible from Escanaba Trough, the sediment-covered, southern end of the Gorda Ridge spreading axis, offshore northern California. The molecular distributions of hydrocarbons in the two pyrrhotite-rich samples recovered by submersible are similar and compare well the hydrocarbon composition of the first pyrrhotite-rich samples containing petroleum discovered at a 1985 dredge site about 30 km to the south of the site of the submersible dive. In contrast, the 1986 dredge sample, composed of a polymetallic assemblage of sulfides, containes petroleum in which the distribution of hydrocarbons indicates a slightly higher of maturity relative to the other samples. The observation that petroleum of variable composition occurs with metallic sulfides at two and probably more distinct site indicates that petroleum generation may be a common process in the hydrothermally active Escanaba Trough.

California↗
USGS2009

Mineralogy of soils from two continental-scale transects across the United States and Canada and its relation to soil geochemistry and climate

Quantitative mineralogy correlates with major-, minor- and trace-element chemistry for 387 samples of A-horizon and deeper soils collected from east-west and north-south transects across the USA and Canada, where the deeper soils were collected beneath the A-horizon samples. Concentrations of the major elements correlate with specific mineral phases. Minor- and trace-element concentrations correlate with the same phases as the major elements with which they share similar geochemical behavior. Concentrations of quartz and feldspar correlate with precipitation trends east of the Rocky Mountains, and are independent of the underlying rock type and age, indicating that the weathering of soils in this region may have reached a steady-state mineralogy. Other trends in mineralogy relate to physiographic province. The combination of quantitative mineralogy and chemical analysis yields a much richer portrait of soils than can be gained from chemistry alone, because the origins of chemical trends and the chemical availability of specific elements are related to mineralogy.

Applied Geochemistry↗
USGS2009

Geological controls on soil parent material geochemistry along a northern Manitoba-North Dakota transect

As a pilot study for mapping the geochemistry of North American soils, samples were collected along two continental transects extending east–west from Virginia to California, and north–south from northern Manitoba to the US–Mexican border and subjected to geochemical and mineralogical analyses. For the northern Manitoba–North Dakota segment of the north–south transect, X-ray diffraction analysis and bivariate relations indicate that geochemical properties of soil parent materials may be interpreted in terms of minerals derived from Shield and clastic sedimentary bedrock, and carbonate sedimentary bedrock terranes. The elements Cu, Zn, Ni, Cr and Ti occur primarily in silicate minerals decomposed by aqua regia, likely phyllosilicates, that preferentially concentrate in clay-sized fractions; Cr and Ti also occur in minerals decomposed only by stronger acid. Physical glacial processes affecting the distribution and concentration of carbonate minerals are significant controls on the variation of trace metal background concentrations.

Applied Geochemistry↗
USGS1994

Geochemistry of thermal fluids on the volcanic isle of Pantelleria, southern Italy

Chemical analyses of thermal springs and gas emissions on the volcanic island of Pantelleria, southern Italy, suggest the presence, at depth, of a Na Cl thermal aquifer near 100°C; 80–90% of the water in this aquifer is fed by rainfall and the remainder of the mixture is seawater. Chemical analyses of the gas emissions reveal that below this shallow aquifer, a deeper hydrothermal degassing system (150°C) may exist. Rising CO 2 causes alterations of the upper aquifer host rocks (mostly pantellerites), favors formation of Na HCO 3 type waters, and causes eventual rpecipitation of CaCO 3 and coprecipitation of MgCO 3 and silica. Comparison of the present chemical data with older data from the literature suggests that the shallow Pantelleria thermal aquifer has increased in salinity and decreased in temperature during the last 25 a. Both effects were apparently caused by increased flow of recent seawater into the system because of increased ground water abstraction in the northern part of the island.

Isle of Pantelleria↗
USGS2019

Organic geochemistry and toxicology of a stream impacted by unconventional oil and gas wastewater disposal operations

Water and sediment extracts samples were analyzed for extractable hydrocarbons by gas chromatography/mass spectrometry (GC/MS) using an Agilent (Agilent Technologies, Palo Alto, CA, USA) 7890 series GC and 5975 electron ionization (EI) mass selective detector (MSD) operated in scan mode. Agilent ChemStation software was used for data acquisition and analysis (version E.02.00.493 on GC/MS computer and version F.01.03.2357 on laptop for data workup). A 30 m x 250 m x 0.25 m HP-5MS column (95% dimethyl 5% diphenyl polydimethylsiloxane) was used for GC/MS under the following conditions: 1.0 L splitless injection, constant flow of 0.7 mL/min, solvent delay of 7.5 min, injector temperature of 280C, interface at 300C, temperature program of 50-150C at 7C/min, 150-230C at 6C/min, and 230-300C at 3C/min with mass scanned from 35-500 Da.

West Virginia↗
USGS1991

Geochemistry of halogens in the Milk River aquifer, Alberta, Canada

Analytical data are presented for Cl, Br and I on a regional scale for the Milk River aquifer. The three halides show strikingly similar spatial distributions and are highly correlated. Concentrations are low in the freshwater portions of the aquifer but increase by as much as two orders of magnitude along the margins. However, halide ratios reach nearly constant values moving down-gradient, suggesting the dominance of a common subsurface source for these ions. Ratios of Cl/I and Cl/Br are less than those of seawater and fit an origin derived from the diagenesis of organic matter in the sediments. Halide ratios rule out leakage and/or diffusion from the underlying Colorado Group as a major influence on the chemistry; the favored hypothesis is altered connate seawater diffusing from low-permeability units within the Milk River Formation as the primary source of salts. This hypothesis of an internal source has important implications for solute sources in other aquifers affected by saline waters because it does not require the importation of a distant fluid.

Alberta↗
USGS2004

Rare earth element partitioning between hydrous ferric oxides and acid mine water during iron oxidation

Ferrous iron rapidly oxidizes to Fe (III) and precipitates as hydrous Fe (III) oxides in acid mine waters. This study examines the effect of Fe precipitation on the rare earth element(REE) geochemistry of acid mine waters to determine the pH range over which REEs behave conservatively and the range over which attenuation and fractionation occur. Two field studies were designed to investigate REE attenuation during Fe oxidation in acidic, alpine surface waters. To complement these field studies, a suite of six acid mine waters with a pH range from 1.6 to 6.1 were collected and allowed to oxidize in the laboratory at ambient conditions to determine the partitioning of REEs during Fe oxidation and precipitation. Results from field experiments document that even with substantial Fe oxidation, the REEs remain dissolved in acid, sulfate waters with pH below 5.1. Between pH 5.1 and 6.6 the REEs partitioned to the solid phases in the water column, and heavy REEs were preferentially removed compared to light REEs. Laboratory experiments corroborated field data with the most solid-phase partitioning occurring in the waters with the highest pH.

Applied Geochemistry↗
USGS2014

Investigation of geochemical indicators to evaluate the connection between inland and coastal groundwater systems near Kaloko-Honokōhau National Historical Park, Hawai‘i

Kaloko-Honokōhau National Historical Park (KAHO) is a coastal sanctuary on the western side of the Island of Hawai‘i that was established in 1978 to preserve, interpret, and perpetuate traditional Native Hawaiian culture and activities. KAHO contains a variety of culturally and ecologically significant water resources and water-related habitat for species that have been declared as threatened or endangered by the U.S. Fish and Wildlife Service, or are candidate threatened or endangered species. These habitats are dependent on coastal unconfined groundwater in a freshwater-lens system. The coastal unconfined-groundwater system is recharged by local infiltration of rainfall but also may receive recharge from an inland groundwater system containing groundwater impounded to high altitudes. The area inland of and near KAHO is being rapidly urbanized and increased groundwater withdrawals from the inland impounded-groundwater system may affect habitat and water quality in KAHO, depending on the extent of connection between the coastal unconfined groundwater and inland impounded-groundwater. An investigation of the geochemistry of surface-water and groundwater samples in and near KAHO was performed to evaluate the presence or absence of a connection between the inland impounded- and coastal unconfined-groundwater systems in the area. Analyses of major ions, selected trace elements, rare-earth elements, and strontium-isotope ratio results from ocean, fishpond, anchialine pool, and groundwater samples were consistent with a linear mixing process between the inland impounded and coastal unconfined-groundwater systems. Stable isotopes of water in many samples from the coastal unconfined-groundwater system require an aggregate recharge altitude that is substantially higher than the boundary between the coastal unconfined and inland impounded systems, a further indication of a hydrologic connection between the two systems. The stable isotope composition of the freshwater component of water samples from KAHO indicates that about 25–70% of the freshwater is derived from the inland impounded system.

Hawaii↗
USGS2009

Application of iron and zinc isotopes to track the sources and mechanisms of metal loading in a mountain watershed

Here the hydrogeochemical constraints of a tracer dilution study are combined with Fe and Zn isotopic measurements to pinpoint metal loading sources and attenuation mechanisms in an alpine watershed impacted by acid mine drainage. In the tested mountain catchment, δ 56 Fe and δ 66 Zn isotopic signatures of filtered stream water samples varied by ∼3.5‰ and 0.4‰, respectively. The inherent differences in the aqueous geochemistry of Fe and Zn provided complimentary isotopic information. For example, variations in δ 56 Fe were linked to redox and precipitation reactions occurring in the stream, while changes in δ 66 Zn were indicative of conservative mixing of different Zn sources. Fen environments contributed distinctively light dissolved Fe (<−2.0‰) and isotopically heavy suspended Fe precipitates to the watershed, while Zn from the fen was isotopically heavy (>+0.4‰). Acidic drainage from mine wastes contributed heavier dissolved Fe (∼+0.5‰) and lighter Zn (∼+0.2‰) isotopes relative to the fen. Upwelling of Fe-rich groundwater near the mouth of the catchment was the major source of Fe ( δ 56 Fe ∼ 0‰) leaving the watershed in surface flow, while runoff from mining wastes was the major source of Zn. The results suggest that given a strong framework for interpretation, Fe and Zn isotopes are useful tools for identifying and tracking metal sources and attenuation mechanisms in mountain watersheds.

Applied Geochemistry↗
USGS2002

Helium and carbon gas geochemistry of pore fluids from the sediment-rich hydrothermal system in Escanaba Trough

Ocean Drilling Program (ODP) Leg 169, which was conducted in 1996 provided an opportunity to study the gas geochemistry in the deeper part of the sediment-rich hydrothermal system in Escanaba Trough. Gas void samples obtained from the core liner were analyzed and their results were compared with analytical data of vent fluid samples collected by a submersible dive program in 1988. The gas geochemistry of the pore fluids consisted mostly of a hydrothermal component and was basically the same as that of the vent fluids. The He isotope ratios (R/RA = 5.6-6.6) indicated a significant mantle He contribution and the C isotopic compositions of the hydrocarbons [??13C(CH4) = -43???, ??13C(C2H6) = -20???] were characterized as a thermogenic origin caused by hydrothermal activity. On the other hand, the pore fluids in sedimentary layers away from the hydrothermal fields showed profiles which reflected lateral migration of the hydrothermal hydrocarbons and abundant biogenic CH4. Helium and C isotope systematics were shown to represent a hydrothermal component and useful as indicators for their distribution beneath the seafloor. Similarities in He and hydrocarbon signatures to that of the Escanaba Trough hydrothermal system were found in some terrestrial natural gases, which suggested that seafloor hydrothermal activity in sediment-rich environments would be one of the possible petroleum hydrocarbon generation scenarios in unconventional geological settings. ?? 2002 Elsevier Science Ltd. All rights reserved.

Applied Geochemistry↗
USGS2011

Effects of slow recovery rates on water column geochemistry in aquitard wells

Monitoring wells are often installed in aquitards to verify effectiveness for preventing migration of surface contaminants to underlying aquifers. However, water sampling of aquitard wells presents a challenge due to the slow recovery times for water recharging the wells, which can take as long as weeks, months or years to recharge depending on the sample volume needed. In this study, downhole profiling and sampling of aquitard wells was used to assess geochemical changes that occur in aquitard wells during water level recovery. Wells were sampled on three occasions spanning 11 years, 1 year and 1 week after they were purged and casing water showed substantial water chemistry variations. Temperature decreased with depth, whereas pH and specific conductance increased with depth in the water column after 11 years of water level recovery. Less stable parameters such as dissolved O 2 (DO) and Eh showed strong zonation in the well column, with DO stratification occurring as the groundwater slowly entered the well. Oxidation of reduced till groundwater along with degassing of CO 2 from till pore water affects mineral solubility and dissolved solid concentrations. Recommendations for sampling slowly recovering aquitard wells include identifying the zone of DO and Eh stratification in the well column and collecting water samples from below the boundary to better measure unstable geochemical parameters.

Iowa↗