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USGS2012

Selection of the Mars Science Laboratory landing site

The selection of Gale crater as the Mars Science Laboratory landing site took over five years, involved broad participation of the science community via five open workshops, and narrowed an initial >50 sites (25 by 20 km) to four finalists (Eberswalde, Gale, Holden and Mawrth) based on science and safety. Engineering constraints important to the selection included: (1) latitude (±30°) for thermal management of the rover and instruments, (2) elevation (<-1 km) for sufficient atmosphere to slow the spacecraft, (3) relief of <100-130 m at baselines of 1-1000 m for control authority and sufficient fuel during powered descent, (4) slopes of <30° at baselines of 2-5 m for rover stability at touchdown, (5) moderate rock abundance to avoid impacting the belly pan during touchdown, and (6) a radar-reflective, load-bearing, and trafficable surface that is safe for landing and roving and not dominated by fine-grained dust. Science criteria important for the selection include the ability to assess past habitable environments, which include diversity, context, and biosignature (including organics) preservation. Sites were evaluated in detail using targeted data from instruments on all active orbiters, and especially Mars Reconnaissance Orbiter. All of the final four sites have layered sedimentary rocks with spectral evidence for phyllosilicates that clearly address the science objectives of the mission. Sophisticated entry, descent and landing simulations that include detailed information on all of the engineering constraints indicate all of the final four sites are safe for landing. Evaluation of the traversabilty of the landing sites and target “go to” areas outside of the ellipse using slope and material properties information indicates that all are trafficable and “go to” sites can be accessed within the lifetime of the mission. In the final selection, Gale crater was favored over Eberswalde based on its greater diversity and potential habitability.

Space Science Reviews↗

USGS2024

Rainfall as a driver of post-wildfire flooding and debris flows: A review and synthesis

The increasing threat of post-wildfire hazards creates an imperative for improved post-wildfire flooding and debris flow prediction capabilities. Because rainfall is a primary driver of predictive hydrology and debris flow initiation and inundation models, recent efforts have emphasized the need for interdisciplinary collaboration between meteorology and post-wildfire hazard science that develops more accurate rainfall estimates with longer lead times. In this work, we identified critical knowledge gaps for developing rainfall estimates and filled those gaps by reviewing recent literature and synthesizing pre-existing datasets. Gap areas were organized into the following general topics: a) rainfall intensity-duration-frequency relations, b) time-varying rainfall, c) spatially varying rainfall, and d) rainfall regimes. Recent key research advances include the increasing availability of gridded quantitative rainfall estimates, the expanded use of distributed hydrologic and erosion models that incorporate spatial and temporal variability in rainfall, and the linking of concepts and modeling from the atmospheric and climate sciences with post-wildfire hazard science. We prototype a rainfall regime regionalization schema that captures self-similar properties of rainfall intensity ( k , the maximum rainfall intensity) and temporal scaling ( n , the decay rate). Our k - n relations schema could serve as a framework for organizing, interpreting, and predicting post-wildfire hydrologic and erosional responses. Finally, we summarize salient gaps for implementing spatiotemporally varying rainfall as the driver of post-wildfire hydrologic models designed to improve the prediction of flooding and debris flow hazards to the built environment for emergency managers.

Earth-Science Reviews↗

USGS2012

Origin and diagenesis of K/T impact spherules - from Haiti to Wyoming and beyond

Impact spherules in Cretaceous/Tertiary (K/T) boundary clays and claystones consist of two types; each type is confined to its own separate layer of the boundary couplet in the Western Hemisphere. The form and composition of each of the spherule types result from its own unique mode of origin during the K/T event. Type 1 splash-form spherules occur only in the melt-ejecta (basal) layer of the K/T couplet. This layer was deposited from a ballistic ejecta curtain composed of melt-glass droplets transported mostly within the atmosphere. In contrast, Type 2 spherules are accreted, partially crystalline, spheroidal bodies that formed by condensation of vaporized bolide and target-rock materials in an expanding fireball cloud, from which they settled out of buoyant suspension to form the fireball layer. Dendritic and skeletal Ni-rich spinel crystals are unique to these Type 2 spherules in the fireball layer. Compositions of relict glasses found in Type 1 K/T spherules from Haiti indicate that they were derived from intermediate silicic target rocks. These melt-glass droplets were deposited into an aqueous environment at both continental and marine sites. We propose that the surfaces of the hot melt droplets hydrated rapidly in water and that these hydrated glass rims then altered to palagonite. Subsequent alteration of the palagonite rims to smectite, glauconite, chlorite, kaolinite, or goyazite occurred later during various modes of progressive diagenesis, accompanied by dissolution of some of the glass cores in spherules from continental sections and from marine sections that were subsequently raised above sea level. In many of the nonmarine sections in the Western Interior, the glass cores altered to kaolinite instead of dissolving. Directly comparable spherule morphologies (splash forms), textural features of the altered shells, and scalloping and grooving of relict glass cores or secondary casts demonstrate that the Haitian and Wyoming spherules are equivalent altered Type 1 melt-droplet bodies. The spherules at both locations were deposited in a melt-ejecta layer as part of the K/T impact event. Previously, two types of relict impact glasses had been identified in the Haitian spherule beds: black glass of andesitic composition and high-Ca yellow glass with an unusually high S content. Most workers agree that the latter probably formed by impact melting and mixing of surficial carbonate (and minor anhydrite) rocks with the more deeply-buried crystalline parent rocks of the black glasses. However, some workers have suggested that an intermediate compositional gap exists between the two groups of glasses, implying a different origin than simple mixing of end members during impact. We report glass compositional analyses with values extending throughout this intermediate range, lending support to the impact-mixing model. Inclusions of CaSO 4 found by us in relict yellow glasses further support this model.

Meteoritics↗

USGS2021

Rapid metal pollutant deposition from the volcanic plume of Kīlauea, Hawai’i

Long-lived basaltic volcanic eruptions are a globally important source of environmentally reactive, volatile metal pollutant elements such as selenium, cadmium and lead. The 2018 eruption of Kīlauea, Hawai’i produced exceptionally high discharge of metal pollutants, and was an unprecedented opportunity to track them from vent to deposition. Here we show, through geochemical sampling of the plume that volatile metal pollutants were depleted in the plume up to 100 times faster than refractory species, such as magnesium and iron. We propose that this rapid wet deposition of complexes containing reactive and potentially toxic volatile metal pollutants may disproportionately impact localised areas close to the vent. We infer that the relationship between volatility and solubility is an important control on the atmospheric behaviour of elements. We suggest that assessment of hazards from volcanic emissions should account for heterogeneous plume depletion of metal pollutants.

Hawaii↗

USGS1978

Water resources inventory of Connecticut Part 8: Quinnipiac River basin

The Quinnipiac River basin area in southcentral Connecticut covers 363 square miles, and includes all drainage basins that enter Long Island Sound from the Branford to the Wepawaug Rivers. Its population in 1970 was estimated at 535,000. Precipitation averages 47 inches per year and provides an abundant supply of water. Twenty-one inches returns to the atmosphere as evapotranspiration; the remainder flows directly to streams or percolates to the water table and discharges to Long Island Sound. Small amounts of water are exported from the basin by the New Britain Water Department, and small amounts are imported to the basin by the New Haven Water Company. The amount of water that can be developed at a given place depends upon precipitation, variability of streamflow, hydraulic properties and areal extent of the aquifers, and hydraulic connection between the aquifers and major streams. The quality of the water is determined by the physical environment and the effects of man. Stratified drift is the only aquifer capable of large sustained yields of water to individual wells. Yields of 64 screened wells tapping stratified drift range from 17 to 2,000 gpm (gallons per minute); their median yield is 500 gpm. Till is widespread and generally provides only small amounts of water. Wells in till normally yield only a few hundred gallons of water daily and commonly are inadequate during dry periods. Till is generally used only as an emergency or secondary source of water. Bedrock aquifers underlie the entire report area and include sedimentary, igneous, and metamorphic rock types. These aquifers supply small but reliable quantities of water to wells throughout the basin and are the chief source for many nonurban homes and farms. About 90 percent of the wells tapping bedrock yield at least 2 pgm, and much larger yields are occasionally reported. Maximum well yields of 305 gpm for sedimentary, 75 gpm for igneous, and 200 gpm for metamorphic bedrock have been reported. Water potentially available from stratified drift was estimated on the basis of hydraulic characteristics of the aquifers and evaluation of natural and induced recharge. Long-term yields estimated for 14 favorable areas of stratified drift range from 0.8 to 16.1 mgd (million gallons per day), but detailed verification studies are needed before development. The natural quality of water in the report area is good. The water is generally low in dissolved solid and is soft to moderately hard. Surface water is less mineralized than ground water, especially during high flow when it is primarily surface runoff. A median dissolved-solids concentration of 117 mg/l (milligrams per liter) and a median hardness of 58 mg/l was determined for water samples collected at 20 sites on 16 streams during high flow. A median dissolved-solids concentration of 146 mg/l and a median hardness of 82 mg/l was determined for samples collected at the same sites during low flow. In contrast water from 130 wells had a median dissolved-solids concentration of 188 mg/l and a median hardness of 110 mg/l. Iron and manganese occur in objectionable concentrations in parts of the report area, particularly in water from streams draining swamps and in water from aquifers rich in iron- and manganese-bearing minerals. Concentrations of iron in excess of 0.3 mg/l were found in 40 percent of the high-streamflow samples, 59 percent of the low-streamflow samples and 20 percent of the ground-water samples. Human activities have modified the quality of water in much of the basin. Wide and erratic fluctuations in concentration of dissolved solids in streams, high bacterial content of the Quinnipiac River, and locally high nitrate and chloride concentrations in ground water are evidence of man's influence. Streams, wetlands, and some aquifers along the southern boundary of the basin contain salty water. Overpumping has caused extensive saltwater intrusion in aquifers in the southern and eastern parts of New Haven. The total amount of fresh water used in the area during 1970 is estimated at 35,710 million gallons, or 183 gallons per day per capita. Public water-supply systems met the domestic requirements of about 90 percent of the population; all the systems supplied water that met the drinking water standards of the Connecticut Department of Health.

Connecticut↗

USGS2004

Global climate change and wildlife in North America

It is widely accepted by the scientific community that the earth, which has always experienced climate variation, is now undergoing a period of rapid climate change that is enhanced by anthropogenic atmospheric carbon enrichment during the past 100 years. These climatic changes are accelerating and projections for the next 100 years indicate extensive warming in most (but not all) areas, changing patterns of precipitation, and a significant acceleration of sea level rise. Other likely components of ongoing climate change include changes in season lengths, decreasing range of nighttime versus daytime temperatures, declining snowpack, and increasing frequency and intensity of severe weather events. The many components of climate change, and especially the unprecedented rapid rate of change, are just as important as increasing temperatures. Wildlife species are closely adapted to their environments and readily respond to climate variation. However, as discussed in this technical review, the climate change now underway has extensive potential to affect wildlife throughout North America, either directly or indirectly through responses to changing habitat conditions. When considered in combination with other factors (e.g., pollution, ozone depletion, urbanization, etc.), the potential effect is even greater. The effects of climate change on populations and range distributions of wildlife are expected to be species specific and highly variable, with some effects considered negative and others considered positive. In North America the ranges of habitats and wildlife are predicted to generally move northward as temperatures increase. Variations in this overall pattern will be dependent upon specific local conditions, changing precipitation patterns, and the response of different species to different components of climate change. It follows that the structure of plant–animal communities will also change. Ignoring climate change is likely to increasingly result in failure to reach wildlife management objectives. Wildlife managers need to become knowledgeable about climate change, ways to cope with it, and ways to take advantage of it. Management options currently available include protecting coastal wetlands to allow for sea level rise, reducing the risks to wildlife from potential catastrophic events, adjusting yield and harvest models, accounting for known climatic variations, and taking climate change into consideration when selecting the location and other characteristics of conservation areas. Wildlife managers also need to expect the unexpected and reduce nonclimate stressors on ecosystems. Overall, wildlife managers can minimize negative impacts to wildlife and take advantage of positive aspects by planning ahead and employing adaptive management.

Technical Review↗

USGS2002

Stable isotope composition of waters in the Great Basin, United States 1. Air-mass trajectories

Isentropic trajectories, calculated using the NOAA/Climate Monitoring and Diagnostics Laboratory's isentropic transport model, were used to determine air-parcel origins and the influence of air mass trajectories on the isotopic composition of precipitation events that occurred between October 1991 and September 1993 at Cedar City, Utah, and Winnemucca, Nevada. Examination of trajectories that trace the position of air parcels backward in time for 10 days indicated five distinct regions of water vapor origin: (1) Gulf of Alaska and North Pacific, (2) central Pacific, (3) tropical Pacific, (4) Gulf of Mexico, and (5) continental land mass. Deuterium (??D) and oxygen-18 (??18O) analyses were made of precipitation representing 99% of all Cedar City events. Similar analyses were made on precipitation representing 66% of the precipitation falling at Winnemucca during the same period. The average isotopic composition of precipitation derived from each water vapor source was determined. More than half of the precipitation that fell at both sites during the study period originated in the tropical Pacific and traveled northeast to the Great Basin; only a small proportion traversed the Sierra Nevada. The isotopic composition of precipitation is determined by air-mass origin and its track to the collection station, mechanism of droplet formation, reequilibration within clouds, and evaporation during its passage from cloud to ground. The Rayleigh distillation model can explain the changes in isotopic composition of precipitation as an air mass is cooled pseudo-adiabatically during uplift. However, the complicated processes that take place in the rapidly convecting environment of cumulonimbus and other clouds that are common in the Great Basin, especially in summer, require modification of this model because raindrops that form in the lower portion of those clouds undergo isotopic change as they are elevated to upper levels of the clouds from where they eventually drop to the ground.

Journal of Geophysical Research D: Atmospheres↗

USGS2021

Long-term variation in polar bear body condition and maternal investment relative to a changing environment

In the Arctic, warming air and ocean temperatures have resulted in substantial changes to sea ice, which is primary habitat for polar bears ( Ursus maritimus ). Reductions in extent, duration, and thickness have altered sea ice dynamics, which influences the ability of polar bears to reliably access marine mammal prey. Because nutritional condition is closely linked to population vital rates, a progressive decline in access to prey or an increase in the energetic cost of accessing prey has the potential to adversely affect polar bear population dynamics. We examined long-term (1983–2015) patterns of spring body condition (indexed using residual body mass) and maternal investment (i.e., litter mass of cubs-of-the-year and yearlings; COY and YRL) of polar bears from Alaska’s southern Beaufort Sea to evaluate potential relationships with regional- and circumpolar-scale sea ice conditions and atmospheric patterns. The length of the summer open-water (OW) season (i.e., the period of time the sea ice is mostly absent from the continental shelf) increased at a rate of 18 days decade -1 over the study period. However, the OW season duration was not a strong determinant of spring residual body mass or litter mass. Residual body mass of independent (i.e., subadults and adults) female bears varied relative to age class, reproductive status, and the strength of the prior winter’s Arctic Oscillation (i.e., a circumpolar-scale mode of climate variability driven by long-term atmospheric patterns). Spring residual mass of independent males varied with age class and variation in wind speed (i.e., regional-scale short-term atmospheric patterns) during the winter of the year preceding capture. Over the study period, mean annual body mass of adult females unaccompanied by COY declined by 4 kg/ decade -1 , while no temporal trends were evident in the mean annual body mass of adult females with COY, adult males, and subadults. Litter mass of COY varied relative to capture date, maternal age class and mass, litter size, and year of capture. Litter mass of YRL varied with capture date, maternal age class and mass, litter size, variation in winter wind speed (the year of and year preceding capture), and the strength of the prior winter’s Arctic Oscillation. Mean annual litter mass of COY decreased at a rate of 2.6 kg decade -1 and declined 0.68 kg for every 10 kg reduction in maternal mass. No trend was evident in the mean annual litter mass of yearlings. These findings suggest a nuanced response of the southern Beaufort Sea polar bears to environmental change, where some demographic groups (e.g., adult males and subadults) are presently more resilient than others to changes in the Arctic marine ecosystem.

Alaska↗

USGS2008

Quantitative approaches to characterizing natural chemical weathering rates

Silicate minerals, constituting more than 90% of the rocks exposed at the earth’s surface, are commonly formed under temperature and pressure conditions that make them inherently unstable in surficial environments. Undoubtedly, the most significant aspect of chemical weathering resulting from this instability is the formation of soils which makes life possible on the surface of the earth. Many soil macronutrients in this “critical zone” are directly related to the rate at which primary minerals weather (Huntington, 1995; Chadwick et al., 2003). Chemical weathering also creates economically significant ore deposits, such as those for Al and U (Samma, 1986; Misra, 2000), as well as potentially releasing high concentrations of toxic trace elements such as Se and As (Frankenberger and Benson, 1994). Silicate weathering is a significant buffer to acidification caused by atmospheric deposition (Driscoll et al., 1989) and from land use practices (Farley and Werritty, 1989). Atmospheric CO 2 levels have been primarily controlled by the balance between silicate weathering and the rate of volcanic inputs from the Earth’s interior, a relationship which may explain long-term climate stability (Ruddiman, 1997)

Book chapter↗

USGS2002

Atmospheric transport of pesticides in the Sacramento, California, metropolitan area, 1996-1997

Weekly composite, bulk air was sampled with respect to wind speed and direction from January 1996 through December 1997 in one urban and two agricultural locations in Sacramento County, California. The sampling sites were located along a north-south transect, the dominant directions of the prevailing winds. The samples were analyzed for a variety of current-use pesticides, including dormant orchard spray insecticides and rice herbicides. A variety of pesticides were detected throughout the year, predominantly chlorpyrifos, diazinon, and trifluralin. The data obtained during the winter and spring suggest that some pesticides used in agricultural areas become airborne and may be transported into the urban area. Confirmation of this drift is difficult, however, because these three predominant pesticides, as well as other detected pesticides, also are heavily used in the urban environment. The spring data clearly show that molinate and thiobencarb, two herbicides used only in rice production, do drift into the urban environment.

Water-Resources Investigations Report↗

USGS2006

Atmospheric mercury speciation in Yellowstone National Park

Atmospheric concentrations of elemental mercury (Hg 0 ), reactive gaseous Hg (RGM), and particulate Hg (pHg) concentrations were measured in Yellowstone National Park (YNP), U.S.A. using high resolution, real time atmospheric mercury analyzers (Tekran 2537A, 1130, and 1135). A survey of Hg 0 concentrations at various locations within YNP showed that concentrations generally reflect global background concentrations of 1.5–2.0 ng m − 3 , but a few specific locations associated with concentrated geothermal activity showed distinctly elevated Hg 0 concentrations (about 9.0 ng m − 3 ). At the site of intensive study located centrally in YNP (Canyon Village), Hg 0 concentrations did not exceed 2.5 ng m − 3 ; concentrations of RGM were generally below detection limits of 0.88 pg m − 3 and never exceeded 5 pg m − 3 . Concentrations of pHg ranged from below detection limits to close to 30 pg m −3 . RGM and pHg concentrations were not correlated with any criteria gases (SO 2 , NO x , O 3 ); however pHg was weakly correlated with the concentration of atmospheric particles. We investigated three likely sources of Hg at the intensive monitoring site: numerous geothermal features scattered throughout YNP, re-suspended soils, and wildfires near or in YNP. We examined relationships between the chemical properties of aerosols (as measured using real time, single particle mass spectrometry; aerosol time-of-flight mass spectrometer; ATOFMS) and concentrations of atmospheric pHg. Based on the presence of particles with distinct chemical signatures of the wildfires, and the absence of signatures associated with the other sources, we concluded that wildfires in the park were the main source of aerosols and associated pHg to our sampling site.

Science of the Total Environment↗

USGS2018

Sulfur cycle in the Valles Caldera volcanic complex, New Mexico – Letter 1: Sulfate sources in aqueous system, and implications for S isotope record in Gale Crater on Mars

Initial in situ sulfur (S) isotope measurements of the Martian bedrock in Gale Crater have revealed an unexpectedly wide range of δ 34 S values (−47 to +28%). Generally, it is unclear what processes could have contributed to these large isotope fractionations. Therefore, we studied S sources and aqueous SO 2− 4 cycling in the Valles Caldera volcanic complex, New Mexico to better understand S isotope fractionations related to S degassing, hydrothermal activity, and low-temperature processes in aqueous environment. Overall, our study demonstrates that volcanic systems show large spatial heterogeneity in δ 34 S. Magmatic S sources are obvious in steam-dominated H 2 S degassing and precipitation of secondary minerals from hydrothermal fluids with low δ 34 S values of +0.9 ±3%. Locally, however, hydrothermal processes have resulted in more negative δ 34 S values in sulfide minerals (−18 to −4%) and more positive δ 34 S values in sulfate minerals (−1 to +3%). Major aqueous SO 2− 4 sources are oxidation of H 2 S from modern hydrothermal gas emission, and oxidation and dissolution of sulfide and sulfate minerals present in the hydrothermally altered bedrock and crater-lake sediments. The δ 34 S of aqueous SO 2− 4 in surface water and groundwater varies widely (−8 to +5%) and is similar to major S endmembers that undergo oxidation and/or dissolution by active hydrological system. Minor SO 2− 4 contributions with more positive δ 34 S values (+9 to +14%) come from deeply circulating geothermal fluids and negligible amounts from atmospheric deposition (+5 to +7% in snow). Elevated SO 2− 4 contents are mainly associated with modern and past H 2 S emissions and oxidations near the surface. On regional scale, however, most of the intracaldera bedrock is S-depleted, thus the SO 2− 4 contents are usually low in the surface aquatic system and younger sedimentary lake deposits formed at times of negligible near surface hydrothermal activity. In general, magmatic-hydrothermal processes apparently cause the largest δ 34 S variation in S-bearing minerals on volcanic terrains. Therefore, we infer that the measured wide range of δ 34 S values in the Gale sediments by the Curiosity rover on Mars can be explained by S isotope composition of magmatic-hydrothermal sulfide and sulfate minerals that were present in the initial igneous/volcanic rocks prior to crater formation. Later aqueous processes involved oxidation and dissolution of S minerals initially present in these rocks and led to subsequent formation of diagenetic fluids and alteration products enriched in SO 2− 4 with relatively large δ 34 S variation. Additionally, physical erosion, transport and deposition of detrital hydrothermal S minerals from igneous/volcanic rocks might be in part responsible for the measured wide range of δ 34 S in Gale Crater. These unique S isotope results, measured in situ on another planet for the first time, imply the importance of magmatic-hydrothermal fluids in S transport on early Mars and their subsequent alteration in low-temperature aqueous environments.

New Mexico↗

USGS1976

The dissolution of calcite in CO 2 -saturated solutions at 25°C and 1 atmosphere total pressure

The dissolution of Iceland spar in CO 2 -saturated solutions at 25°C and 1 atm total pressure has been followed by measurement of pH as a function of time. Surface concentrations of reactant and product species have been calculated from bulk fluid data using mass transport theory and a model that accounts for homogeneous reactions in the bulk fluid. The surface concentrations are found to be close to bulk solution values. This indicates that calcite dissolution under the experimental conditions is controlled by the kinetics of surface reaction. The rate of calcite dissolution follows an empirical second order relation with respect to calcium and hydrogen ion from near the initial condition (pH 3.91) to approximately pH 5.9. Beyond pH 5.9 the rate of surface reaction is greatly reduced and higher reaction orders are observed. Calculations show that the rate of calcite dissolution in natural environments may be influenced by both transport and surface-reaction processes. In the absence of inhibition, relatively short times should be sufficient to establish equilibrium.

Geochimica et Cosmochimica Acta↗

USGS2003

The health of glaciers: Recent changes in glacier regime

Glacier wastage has been pervasive during the last century; small glaciers and those in marginal environments are disappearing, large mid-latitude glaciers are shrinking slightly, and arctic glaciers are warming. Net mass balances during the last 40 years are predominately negative and both winter and summer balances (accumulation and ablation) and mass turnover are increasing, especially after 1988. Two principal components of winter balance time-series explain about 50% of the variability in the data. Glacier winter balances in north and central Europe correlate with the Arctic Oscillation, and glaciers in western North America correlate with the Southern Oscillation and Northern Hemisphere air temperature. The degree of synchronization for distant glaciers relates to changes in time of atmospheric circulation patterns as well as differing dynamic responses.

Conference Paper↗

USGS2006

Speciation of volatile arsenic at geothermal features in Yellowstone National Park

Geothermal features in the Yellowstone National Park contain up to several milligram per liter of aqueous arsenic. Part of this arsenic is volatilized and released into the atmosphere. Total volatile arsenic concentrations of 0.5–200 mg/m 3 at the surface of the hot springs were found to exceed the previously assumed nanogram per cubic meter range of background concentrations by orders of magnitude. Speciation of the volatile arsenic was performed using solid-phase micro-extraction fibers with analysis by GC–MS. The arsenic species most frequently identified in the samples is (CH 3 ) 2 AsCl, followed by (CH 3 ) 3 As, (CH 3 ) 2 AsSCH 3 , and CH 3 AsCl 2 in decreasing order of frequency. This report contains the first documented occurrence of chloro- and thioarsines in a natural environment. Toxicity, mobility, and degradation products are unknown.

Idaho, Montana, Wyoming↗

USGS2004

Gold concentrations in abiotic materials, plants, and animals: A synoptic review

Gold (Au) is ubiquitous in the environment and mined commercially at numerous locations worldwide. It is also an allergen that induces dermatitis in sensitive individuals. Gold concentrations were comparatively elevated in samples collected near gold mining and processing facilities, although no data were found for birds and non-human mammals. Maximum gold concentrations reported in abiotic materials were 0.001 μg L -1 in rainwater; 0.0015 μgL -1 in seawater near hydrothermal vents vs. <0.00004–0.0007 μg L -1 elsewhere; 5.0 μg kg -1 dry weight (DW) in the Earth's crust; 19.0 μg L -1 in a freshwater stream near a gold mining site; 440 μg kg -1 DW in atmospheric dust near a high traffic road; 843 μg kg -1 DW in alluvial soil near a Nevada gold mine vs. <29 μg kg -1 DW premining; 2.53 mg kg -1 DW in snow near a Russian smelter vs. <0.35 mg kg -1 DW at a reference site; 4.5 mg kg -1 DW in sewage sludge; 28.7 mg kg -1 DW in polymetallic sulfides from the ocean floor; and 256.0 mg kg -1 DW in freshwater sediments near a gold mine tailings pile vs. <5 μg kg -1 DW prior to mining. In plants, elevated concentrations of 19 μg Au kg -1 DW were reported in terrestrial vegetation near gold mining operations vs. <4 μg kg -1 DW at a reference site; 37 μg kg -1 DW in aquatic bryophytes downstream from a gold mine; 150 μg Au kg -1 DW in leaves of beans grown in soil containing 170 μg kg -1 DW; up to 1.06 mg kg -1 DW in algal mats of rivers receiving gold mine wastes; and 0.1–100 mg kg -1 DW in selected gold accumulator plants. Fish and aquatic invertebrates contained 0.1–38.0 μg Au kg -1 DW. In humans, gold concentrations up to 1.1 μg L -1 were documented in urine of dental technicians vs. 0.002–0.85 μg L -1 in reference populations; 2.1 μg L -1 in breast milk, attributed to gold dental fillings and jewelry of mothers; 1.4 mg kg -1 DW in hair of goldsmiths vs. a normal range of 6–880 μg kg -1 DW; 2.39 mg L -1 in whole blood of rheumatoid arthritis patients receiving gold thiol drugs to reduce inflammation (chrysotherapy) vs. a normal range of 0.2–2.0 μg L -1 ; and 60.0 to 233.0 mg kg -1 fresh weight (FW) in kidneys of rheumatoid arthritis patients undergoing active chrysotherapy vs. <42.0 mg kg -1 FW kidney 140 months posttreatment.

Environmental Monitoring and Assessment↗

USGS2024

Wind-wave climate changes and their impacts

Wind-waves have an important role in Earth system dynamics through air–sea interactions and are key drivers of coastal and offshore hydro-morphodynamics that affect communities, ecosystems, infrastructure and operations. In this Review, we outline historical and projected changes in the wind-wave climate over the world’s oceans, and their impacts. Historical trend analysis is challenging owing to the presence of temporal inhomogeneities from increased numbers and types of assimilated data. Nevertheless, there is general agreement over a consistent historical increase in mean wave height of 1–3 cm yr −1 in the Southern and Arctic Oceans, with extremes increasing by >10 cm yr −1 for the latter. By 2100, mean wave height is projected to rise by 5–10% in the Southern Ocean and eastern tropical South Pacific, and by >100% in the Arctic Ocean. By contrast, reductions in mean wave height up to 10% are expected in the North Atlantic and North Pacific, with regional variability and uncertainty for changes in extremes. Differences between 1.5 °C and warmer worlds reveal the potential benefit of limiting anthropogenic warming. Resolving global-scale climate change impacts on coastal processes and atmospheric–ocean–wave interactions requires a step-up in observational and modeling capabilities, including enhanced spatiotemporal resolution and coverage of observations, more homogeneous data products, multidisciplinary model improvement, and better sampling of uncertainty with larger ensembles.

Nature Reviews Earth & Environment↗

USGS2026

Hybrid particulate matter generated by lava-ignited wildfires at the Litli-Hrutur 2023 eruption, Iceland

Lava flows from the Litli-Hrútur 2023 eruption ignited the largest moss wildfires since modern record keeping in Iceland began. Volcanically ignited wildfires present a cascading and more complex hazard than standalone volcanic eruptions and are likely to become more frequent globally due to climate change. Both volcanic eruptions and wildfire events generate well-characterized air pollution hazards through the emission of gas and particulate matter, but the physicochemical consequences of mixing between end-member emission types during compound events remain poorly understood. In this study, we collected samples of end-member volcanic, wildfire, and mixed plume particulate matter during the Litli-Hrútur 2023 eruption and wildfires. Geochemical and morphological analysis showed that wildfire smoke and lava flow outgassing have distinctive chemical signatures and PM size distributions, but that when mixing occurs between them, either directly at the lava-moss burning interface or during downwind transport, it can result in the formation of hybrid PM. This hybrid PM may be formed through mechanical interactions via well-established processes such as agglomeration and particle scavenging, although interactions are unique in the context of a compound volcanic-wildfire event as they occur between emissions from two different sources (e.g. scavenging of smaller volcanic particles the by larger partially combusted moss particles). We demonstrate that the formation of hybrid PM via these mechanisms may result in altered physicochemical characteristics and suggest that this may have consequences for depositional processes and atmospheric and environmental transport pathways of key species, when compared to stand-alone volcanic eruptions.

Litli-Hrutur volcano↗