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USGS2013

Abundance, size distributions and trace-element binding of organic and iron-rich nanocolloids in Alaskan rivers, as revealed by field-flow fractionation and ICP-MS

Water samples were collected from six small rivers in the Yukon River basin in central Alaska to examine the role of colloids and organic matter in the transport of trace elements in Northern high latitude watersheds influenced by permafrost. Concentrations of dissolved organic carbon (DOC), selected elements (Al, Si, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Ba, Pb, U), and UV-absorbance spectra were measured in 0.45 μm filtered samples. ‘Nanocolloidal size distributions’ (0.5–40 nm, hydrodynamic diameter) of humic-type and chromophoric dissolved organic matter (CDOM), Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb were determined by on-line coupling of flow field-flow fractionation (FFF) to detectors including UV-absorbance, fluorescence, and ICP-MS. Total dissolved and nanocolloidal concentrations of the elements varied considerably between the rivers and between spring flood and late summer base flow. Data on specific UV-absorbance (SUVA), spectral slopes, and the nanocolloidal fraction of the UV-absorbance indicated a decrease in aromaticity and size of CDOM from spring flood to late summer. The nanocolloidal size distributions indicated the presence of different ‘components’ of nanocolloids. ‘Fulvic-rich nanocolloids’ had a hydrodynamic diameter of 0.5–3 nm throughout the sampling season; ‘organic/iron-rich nanocolloids’ occurred in the <8 nm size range during the spring flood; whereas ‘iron-rich nanocolloids’ formed a discrete 4–40 nm components during summer base flow. Mn, Co, Ni, Cu and Zn were distributed between the nanocolloid components depending on the stability constant of the metal (+II)–organic complexes, while stronger association of Cr to the iron-rich nanocolloids was attributed to the higher oxidation states of Cr (+III or +IV). Changes in total dissolved element concentrations, size and composition of CDOM, and occurrence and size of organic/iron and iron-rich nanocolloids were related to variations in their sources from either the upper organic-rich soil or the deeper mineral layer, depending on seasonal variations in hydrological flow patterns and permafrost dynamics.

Alaska↗

USGS2010

Source and fate of inorganic solutes in the Gibbon River, Yellowstone National Park, Wyoming, USA. II. Trace element chemistry

The Gibbon River in Yellowstone National Park receives inflows from several geothermal areas, and consequently the concentrations of many trace elements are elevated compared to rivers in non-geothermal watersheds. Water samples and discharge measurements were obtained from the Gibbon River and its major tributaries near Norris Geyser Basin under the low-flow conditions of September 2006 allowing for the identification of solute sources and their downstream fate. Norris Geyser Basin, and in particular Tantalus Creek, is the largest source of many trace elements (Al, As, B, Ba, Br, Cs, Hg, Li, Sb, Tl, W, and REEs) to the Gibbon River. The Chocolate Pots area is a major source of Fe and Mn, and the lower Gibbon River near Terrace Spring is the major source of Be and Mo. Some of the elevated trace elements are aquatic health concerns (As, Sb, and Hg) and knowing their fate is important. Most solutes in the Gibbon River, including As and Sb, behave conservatively or are minimally attenuated over 29 km of fluvial transport. Some small attenuation of Al, Fe, Hg, and REEs occurs but primarily there is a transformation from the dissolved state to suspended particles, with most of these elements still being transported to the Madison River. Dissolved Hg and REEs loads decrease where the particulate Fe increases, suggesting sorption onto suspended particulate material. Attenuation from the water column is substantial for Mn, with little formation of Mn as suspended particulates.

Wyoming↗

USGS2020

Assessment of leachable elements in volcanic ashfall: A review and evaluation of a standardized protocol for ash hazard characterization

Volcanic ash presents a widespread and common hazard during and after eruptions. Complex interactions between solid ash surfaces and volcanic gases lead to the formation of soluble salts that may be mobilized in aqueous environments. A variety of stakeholders may be concerned about the effects of ash on human and animal health, drinking water supplies, crops, soils and surface runoff. As part of the immediate emergency response, rapid dissemination of information regarding potentially hazardous concentrations of soluble species is critical. However, substantial variability in the methods used to characterize leachable elements makes it challenging to compare datasets and eruption impacts. To address these challenges, the International Volcanic Health Hazard Network ( www.ivhhn.org ) organized a two-day workshop to define appropriate methods for hazard assessment. The outcome of this workshop was a ‘consensus protocol’ for analysis of volcanic ash samples for rapid assessment of hazards from leachable elements, which was subsequently ratified by leading volcanological organizations. The purpose of this protocol is to recommend clear, standard and reliable methods applicable to a range of purposes during eruption response, such as assessing impacts on drinking-water supplies and ingestion hazards to livestock, and also applicable to research purposes. Where possible, it is intended that the methods make use of commonly available equipment and require little training. To evaluate method transferability, an interlaboratory comparison exercise was organized among six laboratories worldwide. Each laboratory received a split of pristine ash, and independently analyzed it according to the protocol for a wide range of elements. Collated results indicate good repeatability and reproducibility for most elements, thus indicating that the development of this protocol is a useful step towards providing standardized and reliable methods for ash hazard characterization. In this article, we review recent ash leachate studies, report the outcomes of the comparison exercise and present a revised and updated protocol based on the experiences and recommendations of the exercise participants. The adoption of standardized methods will improve and facilitate the comparability of results among studies and enable the ongoing development of a global database of leachate information relevant for informing volcanic health hazards assessment.

Journal of Volcanology and Geothermal Research↗

USGS2018

Mapping elemental contamination on Palmyra Atoll National Wildlife Refuge

Palmyra Atoll, once a WWII U.S. Navy air station, is now a U.S. National Wildlife Refuge with nearly 50 km 2 of coral reef and 275 ha of emergent lands with forests of Pisonia grandis trees and colonies of several bird species. Due to the known elemental and organic contamination from chemicals associated with aviation, power generation and transmission, waste management, and other air station activities, a screening survey to map elemental concentrations was conducted. A map of 1944 Navy facilities was georeferenced and identifiable features were digitized. These data informed a targeted survey of 25 elements in soils and sediment at locations known or suspected to be contaminated, using a hand-held X-ray fluorescence spectrometer. At dozens of locations, concentrations of elements exceeded established soil and marine sediment thresholds for adverse ecological effects. Results were compiled into a publicly available geospatial dataset to inform potential remediation and habitat restoration activities.

Marine Pollution Bulletin↗

USGS2020

Apatite trace element geochemistry and cathodoluminescent textures—Acomparison between regional magmatism and the Pea Ridge IOA-REE andBoss IOCG deposits, southeastern Missouri iron metallogenic province, USA

The southeast Missouri iron metallogenic province contains a remarkable wealth of historically important Fe, Cu, Au, and rare earth element (REE) deposits including the Pea Ridge iron oxide-apatite-rare earth element (IOA-REE) deposit and the Boss iron oxide-copper-gold (IOCG) deposit. These deposits are coeval with silicic and intermediate composition magmatism in the St. Francois Mountains terrane. Magmatism, iron-oxide (±Cu, Au, Co) and apatite formation, and REE mineralization overlapped in space and time, but the specific role of regional magmatism in the metallogenesis of these deposits remains unclear and basic petrogenetic models are still debated. We report results from high-spatial resolution textural and geochemical analyses of apatite from regional igneous and ore rocks to elucidate their petrogenetic histories and evaluate deposit models. Backscattered electron and spectral cathodoluminescence imaging of apatite reveal no primary igneous zoning, but show different domains with intricate rims and dissolution/reprecipitation textures, each with distinctive REE patterns in many samples. Apatite from all samples are nearly endmember fluorapatite containing up to ~1.3 wt% Cl and F/Cl ratios span nearly three orders of magnitude. Fresh igneous fluorapatite contain low Na2O (0.15 wt%) while most Pea Ridge ore samples contain higher Na2O (up to ~0.45 wt%), and concentrations of sulfur in fluorapatite of all types are generally moderate to low (0.3 wt% SO3). Significant amounts of Fe (60,000 ppm), Mg (30,000 ppm), Mn (7,000 ppm), and Sr (12,000 ppm) are contained in fluorapatite of all sample types, and they also have moderate amounts of As (4,000 ppm), Ba (2,000 ppm), Th (400 ppm), and U (80 ppm). Fluorapatite show an extraordinarily large range of REE (~0.1-2.0 wt%) and Y (~100-7000 ppm) concentrations. While fresh igneous fluorapatite share many geochemical features with metasomatized igneous fluorapatite and ore-stage fluorapatite from the Pea Ridge IOA and Boss IOCG ore zones, they also have distinct geochemical signatures that are indicative of unique trace element partitioning and substitution mechanisms. These distinguishing textural and geochemical signatures preclude ore-zone fluorapatite genesis directly from a magma (i.e., crystallization directly from a silicate melt) but are permissive of ore-zone fluorapatite formation by magmatic-hydrothermal fluids derived from the regional magmas. Basinal brines may play an important role in the formation of fluorapatite, especially from the Pea Ridge hematite and Boss magnetite-rich zones. Fluorapatite from different ore zones likely formed by crystallization during pulses of hydrothermal fluids with varying Cl-, Na-, and F-contents, which fundamentally controlled the carrying capacity and solubility of REE+Y and generated geochemically distinctive generations of fluorapatite. Exploration geologists using fluorapatite trace element geochemistry to identify IOA and IOCG deposits should proceed with caution, as more high-quality data from these deposits are needed to improve multivariate discrimination analysis. Fluorapatite from IOA/IOCG deposits can be reasonably discriminated from that of other mineral deposit types (e.g., porphyry/epithermal, skarn, orogenic), but no criteria successfully discriminate yet between IOA and IOCG deposits.

Missouri↗

USGS2004

Trace elements in moose (Alces alces) found dead in Northwestern Minnesota, USA

The moose ( Alces alces ) population in bog and forest areas of Northwestern Minnesota has declined for more than 25 years, and more recently the decline is throughout Northwestern Minnesota. Both deficiencies and elevations in trace elements have been linked to the health of moose worldwide. The objective of this study was to evaluate whether trace element toxicity or deficiency may have contributed to the decline of moose in Northwestern Minnesota. Livers of 81 moose found dead in Northwestern Minnesota in 1998 and 1999 were analyzed for trace elements. With the exception of selenium (Se) and copper (Cu), trace elements were not at toxic or deficient levels based on criteria set for cattle. Selenium concentrations in moose livers based on criteria set for cattle were deficient in 3.7% of livers and at a chronic toxicity level in 16% of livers. Copper concentrations based on criteria set for cattle were deficient in 39.5% of livers, marginally deficient in 29.5% of livers and adequate in 31% of livers. Moose from agricultural areas had higher concentrations, on average, of Cd, Cu, Mo and Se in their livers than moose from bog and forest areas. Older moose had higher concentrations of Cd and Zn, and lower concentrations of Cu than younger moose. Copper deficiency, which has been associated with population declines of moose in Alaska and Sweden, may be a factor contributing to the decline of moose in Northwestern Minnesota. (C) 2004 Elsevier B.V. All rights reserved.

Minnesota↗

USGS2009

Selenium and trace element mobility affected by periodic displacement of stratification in the Great Salt Lake, Utah

The Great Salt Lake (GSL) is a unique ecosystem in which trace element activity cannot be characterized by standard geochemical parameters due to the high salinity. Movement of selenium and other trace elements present in the lake bed sediments of GSL may occur due to periodic stratification displacement events or lake bed exposure. The water column of GSL is complicated by the presence of a chemocline persistent over annual to decadal time scales. The water below the chemocline is referred to as the deep brine layer (DBL), has a high salinity (16.5 to 22.9%) and is anoxic. The upper brine layer (UBL) resides above the chemocline, has lower salinity (12.6 to 14.7%) and is oxic. Displacement of the DBL may involve trace element movement within the water column due to changes in redox potential. Evidence of stratification displacement in the water column has been observed at two fixed stations on the lake by monitoring vertical water temperature profiles with horizontal and vertical velocity profiles. Stratification displacement events occur over periods of 12 to 24 h and are associated with strong wind events that can produce seiches within the water column. In addition to displacement events, the DBL shrinks and expands in response to changes in the lake surface area over a period of months. Laboratory tests simulating the observed sediment re-suspension were conducted over daily, weekly and monthly time scales to understand the effect of placing anoxic bottom sediments in contact with oxic water, and the associated effect of trace element desorption and (or) dissolution. Results from the laboratory simulations indicate that a small percentage (1%) of selenium associated with anoxic bottom sediments is periodically solubilized into the UBL where it potentially can be incorporated into the biota utilizing the oxic part of GSL.

Science of the Total Environment↗

USGS2003

Highly siderophile elements in chondrites

The abundances of the highly siderophile elements (HSE), Re, Os, Ir, Ru, Pt and Pd, were determined by isotope dilution mass spectrometry for bulk samples of 13 carbonaceous chondrites, 13 ordinary chondrites and 9 enstatite chondrites. These data are coupled with corresponding 187Re-187Os isotopic data reported by Walker et al. [Geochim. Cosmochim. Acta, 2002] in order to constrain the nature and timing of chemical fractionation relating to these elements in the early solar system. The suite of chondrites examined displays considerable variations in absolute abundances of the HSE, and in the ratios of certain HSE. Absolute abundances of the HSE vary by nearly a factor of 80 among the chondrite groups, although most vary within a factor of only 2. Variations in concentration largely reflect heterogeneities in the sample aliquants. Different aliquants of the same chondrite may contain variable proportions of metal and/or refractory inclusions that are HSE-rich, and sulfides that are HSE-poor. The relatively low concentrations of the HSE in CI1 chondrites likely reflect dilution by the presence of volatile components. Carbonaceous chondrites have Re/Os ratios that are, on average, approximately 8% lower than ratios for ordinary and enstatite chondrites. This is also reflected in 187Os/188Os ratios that are approximately 3% lower for carbonaceous chondrites than for ordinary and enstatite chondrites. Given the similarly refractory natures of Re and Os, this fractionation may have occurred within a narrow range of high temperatures, during condensation of these elements from the solar nebula. Superimposed on this major fractionation are more modest movements of Re or Os that occurred within the last 0-2 Ga, as indicated by minor open-system behavior of the Re-Os isotope systematics of some chondrites. The relative abundances of other HSE can also be used to discriminate among the major classes of chondrites. For example, in comparison to the enstatite chondrites, carbonaceous and ordinary chondrites have distinctly lower ratios of Pd to the more refractory HSE (Re, Os, Ir, Ru and Pt). Differences are particularly well resolved for the EH chondrites that have Pd/Ir ratios that average more than 40% higher than for carbonaceous and ordinary chondrite classes. This fractionation probably occurred at lower temperatures, and may be associated with fractionation processes that also affected the major refractory lithophile elements. Combined, 187Os/188Os ratios and HSE ratios reflect unique early solar system processing of HSE for each major chondrite class. ?? 2002 Elsevier Science B.V. All rights reserved.

Chemical Geology↗

USGS1960

Minor element abundance in a part of the Brazilian shield

Thirty-nine samples of granitic rocks from the Quadrilátero Ferrifero, Minas Gerais, Brazil, representing "mixed" ages and at least three distinct Pre-Cambrian ages were analysed for seventeen minor elements. The rocks are placed in five groups:, (1) 2400 million year old group;, (2) Bacao complex younger, a group of mixed rocks derived from, (1) and, (3);, (3) 1350 million year old group;, (4) a 500 million year old gneissic group;, (5) a 500 million year old silicic group, a later differentiate of a 500 million year old magma. Compared to granitic rocks elsewhere, these Brazilian rocks are about average in Ba, So, Zr, Pb, Nb, Co, Ni, Be and Mo; above average in La and Y; and below average in Cu, Sr, Ga, Sn, V and Cr. Compared to metasedimentary rocks elsewhere in the world., metasedimentary rocks of this region are about average in all seventeen minor elements. Sr has its greatest abundance in the 2400 million year old rocks; Ba, V, Co, Sc, Cr, Ni and Cu in the 1350 million year; and La, Nb, Sn, Zr, Y and Ga in the 500 million year silicic. These abundances are in accord with the petrology and chemistry of the rocks. The 1350 million year rocks are the most mafic of the group and should logically concentrate Ba, V, Co, So, Or, Ni and Cu which are most abundant in earlier crystallates. The 500 million year old silicic rocks are the most felsic and should concentrate La, Nb, Sn, Zr, Y and Ga, which are all most abundant in the latest fractions of granitic magna crystallization. The trace elements also lend support to the idea that the Bacao complex rocks developed by anatexis of 2400 million year rocks during the 1350 -pillion year orogeny. Cu, Sc, Ga, Zr, Sn and Nb have about the same magnitude in the Bagao and the 2400 million year rocks and Sr, V, Co, Or and Ni are lower in the BagAo than either the 2400 or the 1350 million yoar old rocks. This lower abundance is a probable effect of "debasif-cation" which is also brought out by the analysis of major constituents. The effects of a geochemical migration of the elements in this part of the earth's crust may be indicated by the increased abundance of Y in successivol y younger rock types. The increase of La, Nb, Pb, Sn, Y and Zr in the 1350 million year rocks compared to the 2,100 million year rocks might also be an effect of a secular migration.

southeast Brazil↗

USGS2000

16-year trends in elements of lichens at Theodore Roosevelt National Park, ND

An epiphytic lichen and a soil lichen in two very closely related genera (Parmelia sulcata and Xanthoparmelia chlorochroa, respectively) were sampled 16 years apart at Theodore Roosevelt National Park in North Dakota and measured for their elemental content. Mercury and cadmium decreased approximately 30% over the time period in both species. Sulfur decreased 8% in the epiphytic species, but increased 20% in the soil lichen. Factor analysis revealed that soil elements were higher in the soil lichen, indicating there was some soil contamination in that species. A relationship between iron and titanium was found only in the soil lichen. Sulfur and mercury were highly enriched in both species relative to the soil, which suggests that the atmosphere is a contributing source of these elements. New baseline values were calculated, 22 elements for both species, although it is not recommended that the soil lichen be sampled in the future.

North Dakota↗

USGS2006

Chapter 13 Petrogenesis of the Campanian Ignimbrite: Implications for crystal-melt separation and open-system processes from major and trace elements and Th isotopic data

The Campanian Ignimbrite is a large-volume trachytic to phonolitic ignimbrite that was deposited at ≈39.3 ka and represents one of a number of highly explosive volcanic events that have occurred in the region near Naples, Italy. Thermodynamic modeling using the MELTS algorithm reveals that major element variations are dominated by crystal-liquid separation at 0.15 GPa. Initial dissolved H 2 O content in the parental melt is ∼3 wt.% and the magmatic system fugacity of oxygen was buffered along QFM+1. Significantly, MELTS results also indicate that the liquid line of descent is marked by a large change in the proportion of melt (from 0.46 to 0.09) at ∼884°C, which leads to a discontinuity in melt composition (i.e., a compositional gap) and different thermodynamic and transport properties of melt and magma across the gap. Crystallization of alkali feldspar and plagioclase dominates the phase assemblage at this pseudo-invariant point temperature of ∼884°C. Evaluation of the variations in the trace elements Zr, Nb, Th, U, Rb, Sm, and Sr using a mass balance equation that accounts for changing bulk mineral-melt partition coefficients as crystallization occurs indicates that crystal-liquid separation and open-system processes were important. Th isotope data yield an apparent isochron that is ∼20 kyr younger than the age of the deposit, and age-corrected Th isotope data indicate that the magma body was an open system at the time of eruption. Because open-system behavior can profoundly change isotopic and elemental characteristics of a magma body, these Th results illustrate that it is critical to understand the contribution that open-system processes make to magmatic systems prior to assigning relevance to age or timescale information derived from such systems. Fluid-magma interaction has been proposed as a mechanism to change isotopic and elemental characteristics of magma bodies, but an evaluation of the mass and thermal constraints on such a process suggests large-scale interaction is unlikely. In the case of the magma body associated with the Campanian Ignimbrite, the most likely source of the open-system signatures is assimilation of partial melts of compositionally heterogeneous basement composed of cumulates and intrusive equivalents of volcanic activity that has characterized the Campanian region for over 300 kyr.

Developments in Volcanology↗

USGS2004

Chapter 14 Rex Chert member of the Permian Phosphoria Formation: Composition, with emphasis on elements of environmental concern

We present bulk chemical and mineralogical compositions, as well as petrographic and outcrop descriptions, of rocks collected from three measured outcrop sections of the Rex Chert Member of the Phosphoria Formation in southeast Idaho. The three measured sections were chosen from 10 outcrops of Rex Chert that were described in the field. The Rex Chert overlies the Meade Peak Phosphatic Shale Member of the Phosphoria Formation, the source of phosphate ore in the region. Rex Chert removed as overburden constitutes part of the material transferred to waste-rock piles during phosphate mining. It is also used to surface roads in the mining district. It has been proposed that the chert be used to cap and isolate waste piles, thereby inhibiting the leaching of potentially toxic elements into the environment. The rock samples studied here are from individual chert beds representative of each stratigraphic section sampled. The Cherty Shale Member of the Phosphoria Formation that overlies the Rex Chert in measured section 1 and the upper Meade Peak and the transition zone to the Rex Chert in section 7 were also described and sampled. The cherts are predominantly spiculite composed of granular and mosaic quartz, and sponge spicules, with various but minor amounts of other fossils and detrital grains. The Cherty Shale Member and transition rocks between the Meade Peak and Rex Chert are siliceous siltstones and argillaceous cherts with ghosts of sponge spicules and somewhat more detrital grains than the chert. The dominant mineral is quartz. Carbonate beds are rare in each section and are composed predominantly of calcite and dolomite in addition to quartz. Feldspar, mica, clay minerals, calcite, dolomite, and carbonate fluorapatite are minor to trace minerals in the chert. The concentration of SiO 2 in the chert averages 94.6 wt.%. Organic-carbon content is generally very low, but can be as much as 1.8% in Cherty Shale Member samples and as much as 3.3% in samples from the transition between the Meade Peak and Rex Chert. Likewise, phosphate (P 2 O 5 ) is generally low in the chert, but can be as much as 3.1% in individual chert beds. Selenium concentrations in Rex Chert and Cherty Shale Member samples vary from <0.2 to 138 ppm, with a mean concentration of 7.0 ppm. This mean Se content is heavily dependent on two values of 101 and 138 ppm for siliceous siltstone from the lower part of the Rex Chert, which contains rocks that are transitional in character between the Meade Peak and Rex Chert Members. Without those two samples, the mean Se concentration is < 1.0 ppm. Other elements of environmental interest, As, Cr, V, Zn, Hg, and Cd, generally occur in concentrations near or below that in average continental shale. Stratigraphic changes, equivalent to temporal changes in the depositional basin, in chemical composition of rocks are notable either as uniform changes through the sections or as distinct differences in the mean composition of rocks that comprise the upper and lower halves of the sections. Q-mode factors are interpreted to represent the following rock and mineral components: chert-silica component consisting of Si (±Ba); phosphorite-carbonate fluorapatite component composed of P, Ca, As, Y, V, Cr, Sr, and La (± Fe, Zn, Cu, Ni, Li, Se, Nd, Hg); shale component composed of Al, Na, Zr, K, Ba, Li, and organic C (± Ti, Mg, Se, Ni, Fe, Sr, V, Mn, Zn); carbonate component (dolomite, calcite, silicified carbonates) composed of carbonate C, Mg, Ca, and Si (±Mn); and, tentatively, organic matter-hosted elements (and/or sulfide-sulfate phases) composed of Cu (± organic C, Zn, Mn, Si, Ni, Hg, Li). Selenium shows a dominant association with organic matter and to lesser degrees associations with other shale components and carbonate fluorapatite. Consideration of larger numbers of factors in Q-mode analysis indicates that native Se (a factor containing Se (± Ba)) may also comprise a minor component of the Se complement. Comparison of our data with those from newly exposed outcrops in active phosphate mines indicates that weathering of typical Rex Chert outcrops likely plays an important role in removing environmentally sensitive elements.

Idaho↗

USGS2010

Accuracy of an estuarine hydrodynamic model using smooth elements

A finite element model which uses triangular, isoparametric elements with quadratic basis functions for the two velocity components and linear basis functions for water surface elevation is used in the computation of shallow water wave motions. Specifically addressed are two common uncertainties in this class of two-dimensional hydrodynamic models: the treatment of the boundary conditions at open boundaries and the treatment of lateral boundary conditions. The accuracy of the models is tested with a set of numerical experiments in rectangular and curvilinear channels with constant and variable depth. The results indicate that errors in velocity at the open boundary can be significant when boundary conditions for water surface elevation are specified. Methods are suggested for minimizing these errors. The results also show that continuity is better maintained within the spatial domain of interest when ‘smooth’ curve-sided elements are used at shoreline boundaries than when piecewise linear boundaries are used. Finally, a method for network development is described which is based upon a continuity criterion to gauge accuracy. A finite element network for San Francisco Bay, California, is used as an example.

California↗

USGS1998

Potentially hazardous elements in coal: Modes of occurrence and summary of concentration data for coal components

Mode-of-occurrence data are summarized for 13 potentially hazardous elements (Be, Cr, Mn, Co, Ni, As, Se, Cd, Sb, Hg, Pb, Th, U) in coal. Recent work has refined mode-of-occurrence data for Ni, Cr, and As, as compared to previous summaries. For Cr, dominant modes of occurrence include the clay mineral iliite, an amorphous CrO(OH) phase, and Cr-bearing spinels. Nickel is present in Fe-sulfides (pyrite and marcasite) and is also organically bound. Arsenic-bearing pyrite may be the dominant host of As in bituminous coals. Concentration data for the 13 HAPs, obtained primarily by quantitative microanalysis techniques, are compiled for mineral and organic portions of coal. HAPs element concentrations are greatest in Fe-sulfides, and include maxima of 2,300 ppm (Co), 4,500ppm (Ni), 4.9wt.% (As), 2,000ppm (Se), 171 ppm (Hg), and 5,500ppm (Pb). Trace-element microanalysis is a significant refinement over bulk methods, and shows that there is considerable trace-element variation on a fine scale for a given coal, and from one coal to another.

Coal Preparation↗

USGS2008

Mercury, trace elements and organic constituents in atmospheric fine particulate matter, Shenandoah National Park, Virginia, USA: A combined approach to sampling and analysis

Compliance with U.S. air quality regulatory standards for atmospheric fine particulate matter (PM 2.5 ) is based on meeting average 24 hour (35 μ m −3 ) and yearly (15 μg m −3 ) mass‐per‐unit‐volume limits, regardless of PM 2.5 composition. Whereas this presents a workable regulatory framework, information on particle composition is needed to assess the fate and transport of PM 2.5 and determine potential environmental/human health impacts. To address these important non‐regulatory issues an integrated approach is generally used that includes (1) field sampling of atmospheric particulate matter on filter media, using a size‐limiting cyclone, or with no particle‐size limitation; and (2) chemical extraction of exposed filters and analysis of separate particulate‐bound fractions for total mercury, trace elements and organic constituents, utilising different USGS laboratories optimised for quantitative analysis of these substances. This combination of sampling and analysis allowed for a more detailed interpretation of PM 2.5 sources and potential effects, compared to measurements of PM 2.5 abundance alone. Results obtained using this combined approach are presented for a 2006 air sampling campaign in Shenandoah National Park (Virginia, USA) to assess sources of atmospheric contaminants and their potential impact on air quality in the Park. PM 2.5 was collected at two sampling sites (Big Meadows and Pinnacles) separated by 13.6 km. At both sites, element concentrations in PM 25 were low, consistent with remote or rural locations. However, element/Zr crustal abundance enrichment factors greater than 10, indicating anthropogenic input, were found for Hg, Se, S, Sb, Cd, Pb, Mo, Zn and Cu, listed in decreasing order of enrichment. Principal component analysis showed that four element associations accounted for 84% of the PM 2.5 trace element variation; these associations are interpreted to represent: (1) crustal sources (Al, REE); (2) coal combustion (Se, Sb), (3) metal production and/or mobile sources (Mo, Cd, Pb, Cu, Zn) and (4) a transient marine source (Sr, Mg). Concentrations of Hg in PM 2.5 at background levels in the single pg m −3 were shown by collection and analysis of PM 2.5 on filters and by an automated speciation analyser set up at the Big Meadows air quality site. The speciation unit revealed periodic elevation of reactive gaseous mercury (RGM) that co‐occurred with peaks in SO 2 , indicating an anthropogenic source. GC/MS total ion current chromatograms for the two sites were quite similar indicating that organic signatures were regional in extent and/or that the same compounds were present locally at each site. Calculated carbon preference index values for n ‐alkanes indicated that plant waxes rather than anthropogenic sources, were the dominant alkane source. Polycyclic aromatic hydrocarbons (PAHs) were detected, with a predominance of non‐alkylated, and higher molecular weight PAHs in this fraction, suggestive of a combustion source (fossil fuel or forest fires).

Virginia↗

USGS1989

Selenate reduction to elemental selenium by anaerobic bacteria in sediments and culture: Biogeochemical significance of a novel, sulfate-independent respiration

Interstitial water profiles of SeO 4 2− , SeO 3 2− , SO 4 2− , and Cl − in anoxic sediments indicated removal of the seleno-oxyanions by a near-surface process unrelated to sulfate reduction. In sediment slurry experiments, a complete reductive removal of SeO 4 2− occurred under anaerobic conditions, was more rapid with H 2 or acetate, and was inhibited by O 2 , NO 3 − , MnO 2 , or autoclaving but not by SO 4 2− or FeOOH. Oxidation of acetate in sediments could be coupled to selenate but not to molybdate. Reduction of selenate to elemental selenium was determined to be the mechanism for loss from solution. Selenate reduction was inhibited by tungstate and chromate but not by molybdate. A small quantity of the elemental selenium precipitated into sediments from solution could be resolublized by oxidation with either nitrate or FeOOH, but not with MnO 2 . A bacterium isolated from estuarine sediments demonstrated selenate-dependent growth on acetate, forming elemental selenium and carbon dioxide as respiratory end products. These results indicate that dissimilatory selenate reduction to elemental selenium is the major sink for selenium oxyanions in anoxic sediments. In addition, they suggest application as a treatment process for removing selenium oxyanions from wastewaters and also offer an explanation for the presence of selenite in oxic waters.

California↗

USGS2009

Visualizing fossilization using laser ablation-inductively coupled plasma-mass spectrometry maps of trace elements in Late Cretaceous bones

Elemental maps generated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) provide a previously unavailable high-resolution visualization of the complex physicochemical conditions operating within individual bones during the early stages of diagenesis and fossilization. A selection of LA-ICP-MS maps of bones collected from the Late Cretaceous of Montana (United States) and Madagascar graphically illustrate diverse paths to recrystallization, and reveal unique insights into geochemical aspects of taphonomic history. Some bones show distinct gradients in concentrations of rare earth elements and uranium, with highest concentrations at external bone margins. Others exhibit more intricate patterns of trace element uptake related to bone histology and its control on the flow paths of pore waters. Patterns of element uptake as revealed by LA-ICP-MS maps can be used to guide sampling strategies, and call into question previous studies that hinge upon localized bulk samples of fossilized bone tissue. LA-ICP-MS maps also allow for comparison of recrystallization rates among fossil bones, and afford a novel approach to identifying bones or regions of bones potentially suitable for extracting intact biogeochemical signals. ?? 2009 Geological Society of America.

Geology↗

USGS2022

Standard atomic weights of the elements 2021 (IUPAC Technical Report)

Following the reviews of atomic-weight determinations and other cognate data in 2015, 2017, 2019 and 2021, the IUPAC (International Union of Pure and Applied Chemistry) Commission on Isotopic Abundances and Atomic Weights (CIAAW) reports changes of standard atomic weights. The symbol A r °(E) was selected for standard atomic weight of an element to distinguish it from the atomic weight of an element E in a specific substance P, designated A r (E, P). The CIAAW has changed the values of the standard atomic weights of five elements based on recent determinations of terrestrial isotopic abundances: Ar (argon): from 39.948 ± 0.001 to [39.792, 39.963] Hf (hafnium): from 178.49 ± 0.02 to 178.486 ± 0.006 Ir (iridium): from 192.217 ± 0.003 to 192.217 ± 0.002 Pb (lead): from 207.2 ± 0.1 to [206.14, 207.94] Yb (ytterbium): from 173.054 ± 0.005 to 173.045 ± 0.010 The standard atomic weight of argon and lead have changed to an interval to reflect that the natural variation in isotopic composition exceeds the measurement uncertainty of A r (Ar) and A r (Pb) in a specific substance. The standard atomic weights and/or the uncertainties of fourteen elements have been changed based on the Atomic Mass Evaluations 2016 and 2020 accomplished under the auspices of the International Union of Pure and Applied Physics (IUPAP). A r ° of Ho, Tb, Tm and Y were changed in 2017 and again updated in 2021: Al (aluminium), 2017: from 26.981 5385 ± 0.000 0007 to 26.981 5384 ± 0.000 0003 Au (gold), 2017: from 196.966 569 ± 0.000 005 to 196.966 570 ± 0.000 004 Co (cobalt), 2017: from 58.933 194 ± 0.000 004 to 58.933 194 ± 0.000 003 F (fluorine), 2021: from 18.998 403 163 ± 0.000 000 006 to 18.998 403 162 ± 0.000 000 005 (Ho (holmium), 2017: from 164.930 33 ± 0.000 02 to 164.930 328 ± 0.000 007) Ho (holmium), 2021: from 164.930 328 ± 0.000 007 to 164.930 329 ± 0.000 005 Mn (manganese), 2017: from 54.938 044 ± 0.000 003 to 54.938 043 ± 0.000 002 Nb (niobium), 2017: from 92.906 37 ± 0.000 02 to 92.906 37 ± 0.000 01 Pa (protactinium), 2017: from 231.035 88 ± 0.000 02 to 231.035 88 ± 0.000 01 Pr (praseodymium), 2017: from 140.907 66 ± 0.000 02 to 140.907 66 ± 0.000 01 Rh (rhodium), 2017: from 102.905 50 ± 0.000 02 to 102.905 49 ± 0.000 02 Sc (scandium), 2021: from 44.955 908 ± 0.000 005 to 44.955 907 ± 0.000 004 (Tb (terbium), 2017: from 158.925 35 ± 0.000 02 to 158.925 354 ± 0.000 008) Tb (terbium), 2021: from 158.925 354 ± 0.000 008 to 158.925 354 ± 0.000 007 (Tm (thulium), 2017: from 168.934 22 ± 0.000 02 to 168.934 218 ± 0.000 006) Tm (thulium), 2021: from 168.934 218 ± 0.000 006 to 168.934 219 ± 0.000 005 (Y (yttrium), 2017: from 88.905 84 ± 0.000 02 to 88.905 84 ± 0.000 01) Y (yttrium), 2021: from 88.905 84 ± 0.000 01 to 88.905 838 ± 0.000 002

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