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USGS1999

A robust, finite element model for hydrostatic surface water flows

A finite element scheme is introduced for the 2-dimensional shallow water equations using semi-implicit methods in time. A semi-Lagrangian method is used to approximate the effects of advection. A wave equation is formed at the discrete level such that the equations decouple into an equation for surface elevation and a momentum equation for the horizontal velocity. The convergence rates and relative computational efficiency are examined with the use of three test cases representing various degrees of difficulty. A test with a polar-quadrant grid investigates the response to local grid-scale forcing and the presence of spurious modes, a channel test case establishes convergence rates, and a field-scale test case examines problems with highly irregular grids.A finite element scheme is introduced for the 2-dimensional shallow water equations using semi-implicit methods in time. A semi-Lagrangian method is used to approximate the effects of advection. A wave equation is formed at the discrete level such that the equations decouple into an equation for surface elevation and a momentum equation for the horizontal velocity. The convergence rates and relative computational efficiency are examined with the use of three test cases representing various degrees of difficulty. A test with a polar-quadrant grid investigates the response to local grid-scale forcing and the presence of spurious modes, a channel test case establishes convergence rates, and a field-scale test case examines problems with highly irregular grids.

Communications in Numerical Methods in Engineering↗

USGS2014

Trace element geochemistry (Li, Ba, Sr, and Rb) using Curiosity's ChemCam: early results for Gale crater from Bradbury Landing Site to Rocknest

The ChemCam instrument package on the Mars rover, Curiosity, provides new capabilities to probe the abundances of certain trace elements in the rocks and soils on Mars using the laser-induced breakdown spectroscopy technique. We focus on detecting and quantifying Li, Ba, Rb, and Sr in targets analyzed during the first 100 sols, from Bradbury Landing Site to Rocknest. Univariate peak area models and multivariate partial least squares models are presented. Li, detected for the first time directly on Mars, is generally low (<15 ppm). The lack of soil enrichment in Li, which is highly fluid mobile, is consistent with limited influx of subsurface waters contributing to the upper soils. Localized enrichments of up to ~60 ppm Li have been observed in several rocks but the host mineral for Li is unclear. Bathurst_Inlet is a fine-grained bedrock unit in which several analysis locations show a decrease in Li and other alkalis with depth, which may imply that the unit has undergone low-level aqueous alteration that has preferentially drawn the alkalis to the surface. Ba (~1000 ppm) was detected in a buried pebble in the Akaitcho sand ripple and it appears to correlate with Si, Al, Na, and K, indicating a possible feldspathic composition. Rb and Sr are in the conglomerate Link at abundances >100 ppm and >1000 ppm, respectively. These analysis locations tend to have high Si and alkali abundances, consistent with a feldspar composition. Together, these trace element observations provide possible evidence of magma differentiation and aqueous alteration.

Journal of Geophysical Research E: Planets↗

USGS1997

Trace-element accumulation by Hygrohypnum ochraceum in the upper Rio Grande Basin, Colorado and New Mexico, USA

Transplanted bryophytes can provide an indication of bioavailability. Rates of accumulation were related to the magnitude of ambient trace-element concentrations; maximal uptake occurred during the first 10 d of exposure. Trace-element concentrations in transplanted bryophytes could potentially be used to predict water and sediment concentrations that represent an integration of conditions over short to intermediate lengths of time, rather than instantaneous conditions as measured using water samples.

Environmental Toxicology and Chemistry↗

USGS2000

Organochlorine and trace element contamination in wintering and migrating diving ducks in the southern Great Lakes, USA, since the zebra mussel invasion

Because of the potential for increased trophic transfer of contaminants by zebra mussels ( Dreissena sp. ) to higher trophic levels, we collected four species of waterfowl (n = 65 ducks) from four locations in Lake Erie, Lake St. Clair, and Lake Michigan, USA, between 1991 and 1993 for organochlorine contaminant and trace element analyses. Geometric mean concentrations of total polychlorinated biphenyls (PCBs) and p , p ′-dichlorodiphenyldichloroethylene (DDE) were 1.35 and 0.15 μg/g wet weight in lesser scaup ( Aythya affinis ) carcasses and were below known effect levels. Total PCBs in 80% of carcasses, however, were above the U.S. Food and Drug Administration's threshold of 3.0 μg/g lipid weight for consumption of poultry. With the exception of selenium, trace elements were also at background or no-effect levels. Selenium concentrations in livers of 95% of lesser scaup, 90% of bufflehead ( Bucephala albeola ), and 72% of common goldeneye ( Bucephala clangula ) were in the elevated (>10 μg/g dry wt) or potentially harmful range (>33 μg/g dry wt). The effects of these high selenium concentrations are unknown but should be investigated further based on reproductive effects observed in field and laboratory studies of dabbling ducks and because lesser scaup populations are declining. Concentrations of total PCBs in dreissenid mussels in western Lake Erie were 10 times higher than in the upper Mississippi River but were similar to concentrations in other industrialized rivers in Europe and the United States. Metal concentrations were similar to other industrialized sites where zebra mussels have been sampled.

Indiana, Michigan, Ohio↗

USGS2024

The role of sediment ingestion in exposing bottom-feeding fish to chemical elements

Digesta were collected from the intestines of seven species of bottom-feeding fish to better understand the role of incidental ingestion of sediment in exposing fish to inorganic contaminants. A composite sediment tracer variable, based on concentrations of Co, Cr, Ni, Ti, V, and Y in digesta and in sediment, was calculated to estimate sediment content of digesta. Concentration factors (mg/kg in digesta divided by mg/kg in sediment) of eight elements of interest were linearly regressed on this tracer variable. The relative importance of sediment ingestion to oral exposure was quantified. Zinc, Cd, and Cu were ingested mainly from sediment-free food. Arsenic, Cr, Ni, Al, and Pb, in contrast, were ingested mainly from sediment. As an example, 93% of the Ni in digesta from a brown bullhead ( Ameiurus nebulosus ) was from sediment and only 7% from food. Regressions of Al and Pb in digesta of suckers (Catostomidae) suggested an additional oral source, possibly from oxides coating biotic or abiotic surfaces. Overall, concentrations of 12 of 21 elements studied were positively correlated with sediment content ( p < 0.005). Including sediment ingestion as a pathway for bottom-feeding fish is essential for accurately estimating exposures in toxicological studies.

Environmental Toxicology and Chemistry↗

USGS2001

The effect of mining and related activities on the sediment-trace element geochemistry of Lake Coeur d'Alene, Idaho, USA. Part III. Downstream effects: The Spokane River Basin

During 1998/1999, surface and subsurface sediment samples were collected along the entire length of the Spokane River from its outlet at the northern end of Lake Coeur d'Alene (CDA), Idaho, to Lake Roosevelt on the Columbia River, Washington. The study was conducted to determine if the trace element enrichments observed in Lake CDA and on the floodplain and in the CDA River extend through the Spokane River Basin (SRB). As in Lake CDA, surface sediments in the SRB are enriched in Pb, Zn, As, Cd, Sb and Hg relative to local background levels. Pb, Cd and Zn are the most elevated, with maximum enrichment occurring in the upper Spokane River in close proximity to Lake CDA. On average, enrichment decreases downstream, apparently reflecting both increased distance from the inferred source (the CDA River Basin), as well as increased dilution by locally derived but unenriched materials. Only Cd and Zn display marked enrichment throughout the SRB. Pb, Zn and Cd seem to be associated mainly with an operationally defined iron oxide phase, whereas the majority of the As and Sb seem to be matrix-held. Subsurface sediments also are enriched in Pb, Zn, As, Cd, Sb and Hg relative to background levels. Based on 137Cs and excess 210Pb dating, trace element enrichment began in the middle part of the SRB (Long Lake) between 1900 and 1920. This is contemporaneous with similar enrichments observed in Lake CDA, as well as the completion of Long Lake Dam (1913). In the most downstream part of the basin (Spokane River Arm of Lake Roosevelt), enrichment began substantially later, between 1930 and 1940. The temporal difference in enrichment between Long Lake and the River Arm may reflect the latter's greater distance from the presumed source of the enrichment (the CDA River Basin); however, the difference is more likely the result of the completion of Grand Coulee Dam (1934-1941), which formed Lake Roosevelt, backed up the Spokane River, and increased water levels in the River Armby about 30 m.

Hydrological Processes↗

USGS2013

A domain decomposition approach to implementing fault slip in finite-element models of quasi-static and dynamic crustal deformation

We employ a domain decomposition approach with Lagrange multipliers to implement fault slip in a finite-element code, PyLith, for use in both quasi-static and dynamic crustal deformation applications. This integrated approach to solving both quasi-static and dynamic simulations leverages common finite-element data structures and implementations of various boundary conditions, discretization schemes, and bulk and fault rheologies. We have developed a custom preconditioner for the Lagrange multiplier portion of the system of equations that provides excellent scalability with problem size compared to conventional additive Schwarz methods. We demonstrate application of this approach using benchmarks for both quasi-static viscoelastic deformation and dynamic spontaneous rupture propagation that verify the numerical implementation in PyLith.

Journal of Geophysical Research B: Solid Earth↗

USGS1971

Distribution of elements in biotite-hornblende pairs and in an orthopyroxene-clinopyroxene pair from zoned plutons, northern Sierra Nevada, California

Distribution of major and minor elements has been determined for five hornblende-biotite pairs from hornblende-biotite quartz diorite and monzotonalite and for a clinopyroxene-orthopyroxene pair from pyroxene diorite collected from the border zones and centers of zoned plutons in the northern Sierra Nevada, California. The distribution coefficients K d [Mg/Fe] for biotite/hornblende are of the same magnitude (0.61–0.67) for both the mafic border zone and the silicic center. For comparison, K D [Mg/Fe] values for biotite/hornblende from plutonic rocks of the central Sierra Nevada and the southern California batholith were calculated from data published by others. Rocks of the oldest age group (ca. 150 m.y.) in the central Sierra Nevada have an average distribution coefficient, K D , of 0.64, close to the average K D in the study area, where K-Ar dates are 143 to 129 m.y. The intermediate age group has an average K D =0.81, and the youngest group has K D =0.77. K D [Mg/Fe] for biotite/hornblende from the southern California batholith is 0.83, close to the average of the intermediate age group in the central Sierra Nevada. The calculated difference in pressure of crystallization between rocks of the Feather River area and the southern California batholith is 1 kb; the rocks of the Feather River area being crystallized at a higher pressure. This is in good agreement with the low-pressure contact metamorphism in the south (pyroxene hornfels facies), as compared with a medium-pressure metamorphism around the northern plutons, where andalusitesillimanite-cordierite and andalusite-staurolite subfacies of the amphibolite facies indicate pressures of about 4 kb. Trace elements Cr, V, Ni, Co, Ga are distributed equally between biotite and hornblende, whereas Ba and possibly Cu are concentrated in biotite and Sr and Sc and possibly Zr in hornblende.

California↗

USGS1978

Minor-element and Sr-isotope geochemistry of tertiary stocks, Colorado mineral belt

Rocks of the northeast portion of the Colorado mineral belt form two petrographically, chemically and geographically distinct rock suites: (1) a silica oversaturated granodiorite suite; and (2) a silica saturated, high alkali monzonite suite. Rocks of the granodiorite suite generally have Sr contents less than 1000 ppm, subparallel REE patterns and initial 87Sr/ 86Sr ratios greater than 0.707. Rocks of the monzonite suite are restricted to the northeast part of the mineral belt, where few rocks of the granodiorite suite occur, and generally have Sr contents greater than 1000 ppm, highly variable REE patterns and 87Sr/86Sr initial ratios less than 0.706. Despite forming simple, smooth trends on major element variation diagrams, trace element data for rocks of the granodiorite suite indicate that they were not derived from a single magma. These rocks were derived from magmas having similar REE patterns, but variable Rb and Sr contents, and Rb/Sr ratios. The preferred explanation for these rocks is that they were derived by partial melting of a mixed source, which yielded pyroxene granulite or pyroxenite residues. The monzonite suite is chemically and petrographically more complex than the granodiorite suite. It is subdivided here into alkalic and mafic monzonites, and quartz syenites, based on the textural relations of their ferromagnesian phases and quartz. The geochemistry of these three rock types require derivation from separate and chemically distinct magma types. The preferred explanation for the alkalic monzonites is derivation from a heterogeneous mafic source, leaving a residue dominated by garnet and clinopyroxene. Early crystallization of sphene from these magmas was responsible for the severe depletion of the REE observed in the residual magmas. The lower Sr content and higher Rb/Sr ratios of the mafic monzonites requires a plagioclase-bearing source. The Sr-isotope systematics of the majority of these rocks are interpreted to be largely primary, and not the result of crustal contamination. The positive correlation of Rb/Sr and 87Sr/86Sr ratios for the least fractionated samples indicate that the sources from which parent magmas of both the granodiorite and monzonite suites were derived are Precambrian in age. ?? 1978 Springer-Verlag.

Contributions to Mineralogy and Petrology↗

USGS1993

Trace elements and organochlorines in the shoalgrass community of the lower Laguna Madre Texas

Our objectives were to measure concentrations of seven trace elements and 14 organochlorine compounds in sediment and biota of the shoalgrass ( Halodule wrightii ) community of the lower Laguna Madre of south Texas and to determine whether chemicals associated with agriculture (e.g. mercury, arsenic, selenium, organochlorine pesticides) were highest near agricultural drainages. Arsenic, mercury, selenium, lead, cadmium, and organochlorines were generally at background concentrations throughout the lower Laguna Madre. Nickel and chromium concentrations were exceptionally high in shrimp and pinfish ( Lagodon rhomboides ), which is difficult to explain because of no known anthropogenic sources for these trace elements. For sediment and blue crabs ( Callinectes sapidus ), mercury was highest near agricultural drainages. Also, DDE was more frequently detected in blue crabs near agricultural drainages than farther away. In contrast, selenium concentrations did not differ among collecting sites and arsenic concentrations were lowest in shoalgrass, blue crabs, and brown shrimp ( Penaeus aztecus ) near agricultural drainages.

Texas↗

USGS1996

The effect of membrane filtration on dissolved trace element concentrations

The almost universally accepted operational definition for dissolved constituents is based on processing The almost universally accepted operational definition for dissolved constituents is based on processing whole-water samples through a 0.45-μm membrane filter. Results from field and laboratory experiments indicate that a number of factors associated with filtration, other than just pore size (e.g., diameter, manufacturer, volume of sample processed, amount of suspended sediment in the sample), can produce substantial variations in the ‘disolved’ concentrations of such elements as Fe, Al, Cu, Zn, Pb, Co, and Ni. These variations result from the inclusion/exclusion of colloidally-associated trace elements. Thus, 'dissolved' concentrations quantitated by analyzing filtrates generated by processing whole-water through similar pore-sized membrane filters may not be equal/comparable. As such, simple filtration through a 0.45-μm membrane filter may no longer represent an acceptable operational definition for dissolved chemical constituents. This conclusion may have important implications for environmental studies and regulatory agencies.

Water, Air, & Soil Pollution↗

USGS1984

Accumulation of trace elements, pesticides, and polychlorinated biphenyls in sediments and the clam Corbicula manilensis of the Apalachicola River, Florida

A survey of trace element and synthetic organic compound concentrations in bottom materials was conducted on the Apalachicola River in northwest Florida in 1979–80 as part of the Apalachicola River Quality Assessment. Substances analyzed included trace elements (predominantly heavy metals), organochlorine insecticides, organophosphorus insecticides, chlorinated phenoxy-acid herbicides, and poly chlorinated biphenyls (PCBs). Three kinds of materials were surveyed: finegrained sediments, whole-body tissue of the Asiatic clam Corbicula manilensis , and bottom-load organic detritus. No hazardous levels of any of the substances were found. Concentrations in the finegrained sediments and clams were generally at least ten times lower than maximum limits considered safe for biota of aquatic systems. A comparison of trace-substance data from the Apalachicola River with data from Lake Seminole (upstream) and Apalachicola Bay (downstream) showed lower concentrations in riverine clams. Sediment concentrations in all parts of the system were comparable. Most trace substances in the Apalachicola River enter the river from the upstream part of the basin (the Chattahoochee and Flint Rivers in Georgia and Alabama) and from nonpoint sources throughout the basin. There are no major point discharges along the Apalachicola. Trend analysis was limited by the scope of the study, but did not reveal any spatial or temporal trends in concentrations of any of the substances analyzed. Concentrations of organic compounds and most metals in Corbicula manilensis did not correlate with those in sediments.

Florida↗

USGS1990

Selenium and other elements in juvenile striped bass from the San Joaquin Valley and San Francisco Estuary, California

Concentrations of selenium and other trace elements were determined in 55 whole body samples of juvenile anadromous striped bass ( Morone saxatilis ) from the San Joaquin Valley and San Francisco Estuary, California. The fish (≤1 yr old—the predominant life stage in the San Joaquin Valley) were collected in September–December 1986 from 19 sites in the Valley and 3 sites in the Estuary, and analyzed for the following elements: aluminum (Al), arsenic (As), boron (B), barium (Ba), beryllium (Be), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), magnesium (Mg), molybdenum (Mo), nickel (Ni), lead (Pb), selenium (Se), strontium (Sr), vanadium (V), and zinc (Zn). When compared to concentrations in whole freshwater fish measured by surveys from other waters, a few samples contained higher levels, of As, Cd, Cu, Pb, and Se. The median concentrations of Al, As, Cu, Fe, Mg, Se, and Sr also differed significantly ( P ⩽0.05) among sites. However, only Se concentrations were highest (up to 7.9 μg/g dry weight) in samples from Valley sites exposed to agricultural subsurface (tile) drainwater; concentrations were lower in samples collected elsewhere. Water quality variables—especially those strongly influenced by tile drainwater (conductivity, total dissolved solids, total alkalinity, and total hardness)—were also significantly correlated ( P ⩽0.05) with Se concentrations in fish. Selenium concentrations in striped bass from the Estuary were only one-fourth to one-half the concentrations measured in the most contaminated fish from the San Joaquin River.

California↗

USGS1980

Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites

This paper is the entire report of the IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites, including three annexes. Tables give the recemmended values for the directions of the north poles of rotation and the prime meridians of the planets and satellites. Reference surfaces for mapping these bodies are described. The annexes discuss the guiding principles, given in the body of the report, present explanatory notes, and provide a bibliography of the rotational elements and reference surfaces of the planets and satellites, definitions, and algebraic expressions of relevant parameters. ?? 1980 D. Reidel Publishing Co.

Celestial Mechanics↗

USGS1977

Survey of trace elements in coals and coal-related materials by neutron activation analysis

Utilizing primarily instrumental neutron activation analysis (INAA) and other analytical methods as many as 61 elements were quantitatively surveyed in 170 U.S. whole coals, 70 washed coals, and 40 bench samples. Data on areal and vertical distributions in various regions were obtained along with extensive information on the mode of occurrence of various elements in the coal matrix itself. ?? 1977 Akade??miai Kiado??.

Journal of Radioanalytical Chemistry↗

USGS2007

Mercury and trace elements in crayfish from northern California

We collected two species of crayfish, Pacifastacus leniusculus and Procambarus clarkii, from Cache and Putah Creeks, California, and analyzed them for mercury and trace elements. Trace elements were higher in carcasses in 40 cases, higher in tails in 5 cases, and not different in 35 cases; no concentration exceeded levels considered harmful. Mercury concentrations were similar among sites, with no overall sex or species effect in tails. Mercury and methylmercury concentrations were higher in tails at all sites. Methylmercury concentrations in crayfish tails (0.156-0.256 ??g/g) exceeded concentrations reported in health advisories for consumption of fish and crayfish from these watersheds. ?? Springer Science+Business Media, LLC 2007.

Bulletin of Environmental Contamination and Toxico↗

USGS2013

Magma mixing and the generation of isotopically juvenile silicic magma at Yellowstone caldera inferred from coupling 238 U– 230 Th ages with trace elements and Hf and O isotopes in zircon and Pb isotopes in sanidine

The nature of compositional heterogeneity within large silicic magma bodies has important implications for how silicic reservoirs are assembled and evolve through time. We examine compositional heterogeneity in the youngest (~170 to 70 ka) post-caldera volcanism at Yellowstone caldera, the Central Plateau Member (CPM) rhyolites, as a case study. We compare 238 U– 230 Th age, trace-element, and Hf isotopic data from zircons, and major-element, Ba, and Pb isotopic data from sanidines hosted in two CPM rhyolites (Hayden Valley and Solfatara Plateau flows) and one extracaldera rhyolite (Gibbon River flow), all of which erupted near the caldera margin ca. 100 ka. The Hayden Valley flow hosts two zircon populations and one sanidine population that are consistent with residence in the CPM reservoir. The Gibbon River flow hosts one zircon population that is compositionally distinct from Hayden Valley flow zircons. The Solfatara Plateau flow contains multiple sanidine populations and all three zircon populations found in the Hayden Valley and Gibbon River flows, demonstrating that the Solfatara Plateau flow formed by mixing extracaldera magma with the margin of the CPM reservoir. This process highlights the dynamic nature of magmatic interactions at the margins of large silicic reservoirs. More generally, Hf isotopic data from the CPM zircons provide the first direct evidence for isotopically juvenile magmas contributing mass to the youngest post-caldera magmatic system and demonstrate that the sources contributing magma to the CPM reservoir were heterogeneous in 176 Hf/ 177 Hf at ca. 100 ka. Thus, the limited compositional variability of CPM glasses reflects homogenization occurring within the CPM reservoir, not a homogeneous source.

Wyoming↗

USGS2019

Unravelling the complexity of magma plumbing at Mount St. Helens: A new trace element partitioning scheme for amphibole

Volcanoes at subduction zones reside above complex magma plumbing systems, where individual magmatic components may originate and interact at a range of pressures. Because whole-rock compositions of subduction zone magmas are the integrated result of processes operating throughout the entire plumbing system, processes such as mixing, homogenisation and magma assembly during shallow storage can overprint the chemical signatures of deeper crustal processes. Whereas melt inclusions provide an effective way to study the uppermost 10–15 km of the plumbing system, challenges remain in understanding magma intrusion, fractionation and hybridisation processes in the middle to lower crust (15–30 km depth), which commonly involves amphibole crystallisation. Here, we present new insights into the mid-crustal plumbing system at Mount St. Helens, USA, using multiple regression methods to calculate trace element partition coefficients for amphibole phenocrysts, and thus infer the trace element compositions of their equilibrium melts. The results indicate vertically distributed crystal fractionation, dominated by amphibole at higher pressures and in intermediate melts, and by plagioclase at lower pressures. Variations in Nb, Zr and REE concentrations at intermediate SiO 2 contents suggest repeated scavenging of partially remelted intrusive material in the mid-crust, and mixing with material from geochemically diverse sources. Amphibole is an effective probe for deep crustal magmatism worldwide, and this approach offers a new tool to explore the structure and chemistry of arc magmas, including those forming plutonic or cumulate materials that offer no other constraints on melt composition.

Contributions to Mineralogy and Petrology↗