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USGS2004

Quality of water from shallow wells in the rice-growing area in southwestern Louisiana, 1999 through 2001

In 1999-2001, the U.S. Geological Survey installed and sampled 27 shallow wells in the rice-growing area in southwestern Louisiana as part of the Acadian-Pontchartrain Study Unit of the National Water-Quality Assessment Program. The purpose of this report is to describe the waulity of water from shallow wells in the rice-growing area and to relate that water quality to natural and anthropogenic activities, particularly rice agriculture. Ground-water samples were analyzed for general ground-water properties and about 150 water-quality constituents, including major inorganic ions, trace elements, nutrients, dissolved organic carbon (DOC), pesticides, radon, chloroflourocarbons, and selected stable isotopes. Dissolved solids concentrations for 17 wells exceeded the U.S. Environmental Protection Agency secondary minimum containment level of 500 milligrams per liter (mg/L) for drinking water. Concentrations for major pesticides generally were less than the maximum contaminant levels for drinking water. Two major inorganic ions, sulfate and chloride, and two trace elements, iron and manganese, had concentrations that were greater than the secondary maximum containment levels. Three nutrient concentrations were greater than 2 mg/L, a level that might indicate contamination from human activities, and one nutrient concentration (that for nitrite plus nitrite as nitrogen) was greater than the maximum contaminant level of 10 mg/L for drinking water. The median concentration for DOC was 0.5 mg/L, indicating naturally-occurring DOC conditions in the study area. Thirteen pesticides and 7 pesticide degradation products were detected in 14 of the 27 wells sampled. Bentazon, 2, 4-D, and molinate (three rice herbicides) were detected in water from four, one, and one wells, respectively, and malathion (a rice insecticide) was deteced in water fromone well. Low-level concentrations and few detections of nutrients and pesticides indicated that ground-water quality was affected slightly by anthropogenic activities. Quality-control samples, including field blanks, replicates, and spikes, indicated no bias in ground-water data from collection on analysis. Radon concentrations for 22 of the 24 wells sampled wer at or greater than the U.S. Environmental Protection Agency proposed maximum contaminant level of 300 picocuries per liter. Chlorofluorocarbon concentrations in selected wells indicated the apparent ages of the ground water varied with depth water level and ranged from about 17 to 49 years. The stable isotopes of hydrogen and oxygen in water molecules indicated the origin of ground water in the study area was rainwater that originated near the study area and that few geochemical or physical processes influenced the stable isotopic composition of the shallow ground water. The Spearman rank correlation was used to detemrine whther significant correlations existed between physical properties, selected chemical constituents, the number of pesticides detected, and the apparent age of water. The depth to ground water was positively correlated to the well depth and inversely correlated to dissolved solids and other constituents, such as radon, indicating the ground water was under unconfined or semiconfined conditions and more dilute with increasing depth. As the depth to ground water increased, the concentrations of dissolved solids and other constituents decreased, possibly because the deeper sands had a greater transmittal of ground water, which, over time, would flush out, or dilute, the concentrations of dissolved solids in the natural sediments. The apparent age of water was correlated inversely with nitrite plus nitrite concentration, indicating that as apparent age increased, the nitrite plus nitrite concentration decreased. No significant correlations existed between the number of pesticides detected and any of the physical or chemica

Water-Resources Investigations Report↗

USGS2004

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of organochlorine pesticides and polychlorinated biphenyls in bottom and suspended sediment by gas chromatography with electron-capture detection

A method applicable for the determination of 19 organochlorine (OC) pesticides, including total toxaphene as a complex mixture, and 3 polychlorinated biphenyl (PCB) mixtures as Aroclor equivalents--Aroclor 1016/1242, 1254, and 1260--in soil, aquatic bottom sediment, and suspended sediment is described. Method performance data are presented. The solvent system is designed to extract simultaneously selected OC pesticides and PCBs from the same sample matrix. The compounds are extracted by conventional Soxhlet extraction with dichloromethane, followed by partial isolation using gel permeation chromatography (GPC) to remove inorganic sulfur and large naturally present molecules from the sediment extract. The aliquot of extract collected from the GPC for OCs (OC pesticides and PCBs) is split into two sample fractions by alumina/silica combined-column chromatography, followed by Florisil adsorption chromatography to remove interfering compounds in the second fraction. The OC fractions are analyzed by dual capillary-column gas chromatography with electron-capture detection (GC/ECD). This report is limited to the determination of selected OC pesticides and PCBs by GC/ECD using this method. Interim reporting levels (IRLs) have been set at 0.400 to 3.12 micrograms per kilogram for 18 individual OC pesticides, 200 micrograms per kilogram for toxaphene, and 4.04 to 4.68 micrograms per kilogram for the PCBs, based on a sample size of 25-gram equivalent dry weight. These reporting levels may change following additional determinations of method detection limits.

Water-Resources Investigations Report↗

USGS1998

Hydrogeology and simulation of ground-water flow in the Paluxy aquifer in the vicinity of Landfills 1 and 3, U.S. Air Force Plant 4, Fort Worth, Texas

Ground-water contamination of the surficial terrace alluvial aquifer has occurred at U.S. Air Force Plant 4, a government-owned, contractor-operated facility, northwest of Fort Worth, Texas. A poorly constructed monitoring well, P–22M, open to the underlying middle zone of the Paluxy aquifer was installed at landfill 3, October 1987, allowing leakage of contaminated ground water to reach the Paluxy aquifer. This well was plugged and abandoned in November 1995. Additionally, volatile organic compounds have been detected in fractures in the Goodland-Walnut confining unit, the hydrogeologic unit separating the terrace alluvial aquifer from the underlying Paluxy aquifer, beneath the western part of landfill 1. Volatile organic compounds in concentrations near the analytical detection limit were detected in the upper Paluxy prior to the drilling of well P–22M. The ground-water-flow simulation model described in this report was developed to examine the best logistically feasible location to install recovery wells to capture the low concentration (less than 100 micrograms per liter) trichloroethylene plume beneath landfills 1 and 3 (west Paluxy plume). Once the recovery wells were installed (1996), the simulation model was recalibrated with new data. This report documents the capture area of the installed recovery wells. Four geologic units are pertinent to this site-specific model. From oldest to youngest, these are the Glen Rose Formation, Paluxy Formation, Walnut Formation, and Goodland Limestone. The Glen Rose Formation is relatively impermeable in the study area and forms the confining unit underlying the Paluxy Formation. The Paluxy Formation forms the Paluxy aquifer, which is a public drinking water supply for the City of White Settlement. The Walnut Formation and Goodland Limestone form the Goodland-Walnut confining unit overlying the Paluxy aquifer. Near landfill 3, gamma-ray logs indicate three distinct zones of the Paluxy Formation; upper, middle, and lower. The formation is about 170-feet thick near landfill 3, and each zone is about 57-feet thick. Two steady-state simulations using the computer program MODFLOW were analyzed using the particle-tracking computer program, MODPATH. One simulation is the calibration simulation using Paluxy aquifer water-level data for May 1993. The second simulation includes the installed recovery wells. A variably spaced grid was designed for the model. The smallest grid cells, 25 by 25 feet, are in the vicinity of landfills 1 and 3. The largest cells, 4,864.5 by 1,441.5 feet, are at the northwestern corner of the model grid near the Parker-Tarrant County line. The modeling was accomplished with three layers representing the upper, middle, and lower zones of the Paluxy aquifer. Particles, which represent contaminant molecules moving in solution with the ground water, were tracked from well P–22M and an area below landfill 1, at the top of the upper zone of the Paluxy aquifer, for 9 years (forward tracking). The forward tracking estimates where contaminants might move by advection from 1987 to 1996. Analysis of backward tracking from the new recovery wells indicates that the simulated contributing area to the recovery wells intercepts the contaminant plume, minimizing off-site migration of the west Paluxy plume. To determine the effectiveness of the recovery wells, monitoring wells southeast of Building 14 have been installed (1996–97) for sampling.

Texas↗

USGS1967

Form and stability of aluminum hydroxide complexes in dilute solution

Laboratory studies of solutions 4.53 x 10 -4 to 4.5 x 10 -5 molal (12.2-1.2 ppm) in aluminum, in 0.01 molal sodium perchlorate, were conducted to obtain information as to the probable behavior of aluminum in natural water. When the solutions were brought to pH 7.5-9.5 and allowed to stand for 24 hours, a precipitate was obtained which was virtually amorphous as shown by X-rays, and which had a solubility equivalent to that of boehmite. This precipitate had a hydrolysis constant (*Ks4) of 1.93 x 10 -13a. When solutions were allowed to stead at this pH range for 10 days, their precipitates gave the X-ray pattern of bayerite (*Ks4 = 1.11 > (10- 4). These hydrolysis constants were obtained at 25?C. and corrected to zero ionic strength and are in close agreement with other published values. The predominant dissolved form in this pH range is Al(OH) -4. Below neutral pH (7.0) the dissolved aluminum species consist of octahedral units in which each aluminum ion is surrounded by six water molecules or hydroxide ions. Single units such as Al(OH2)6 + 3 and AlOH(OH2)5+2 are most abundant below pH 5.0, and where the molar ratio (r) of combined hydroxide to total dissolved aluminum is low. When r is greater than 1.0, polymerization of the octahedral units occurs. When r is between 2.0 and 3.0, solutions aged for 10 days or more contained colloidal particles between 0.10 and 0.45 ? in diameter. Particles whose diameters were greater than 0.10 ? were identified by X-ray diffraction as gibbsite. Particles smaller than 0.10 ? were also present and were shown by means of the electron microscope to have a hexagonal crystal pattern. Structured material consisting of sheets of coalesced six-membered rings of aluminum ions held together by double OH bridges has a distinctive kinetic behavior. This property was used to determine amounts of polymerized material in solutions having r between 1.0 and 3.0 after aging times ranging from a few hours to more than 4 months. Aging increased the size and orderliness of the polymeric aggregates and was accompanied by a decrease in the pH of the solution. The kinetic experiments and stoichiometric data for solutions aged for long periods provided a means of determining activities of polymerized aluminum. From these values the solubility product for microcrystalline gibbsite was determined to be 2.24 x 10 -3, and its free energy of formation, -? 272.3 0.4 kcal per mole. Where polymerization was observed, the process did not stop with small polynuclear complexes containing a few aluminum ions, but proceeded with aging until macromolecules or colloidal-sized particles were formed.

Water Supply Paper↗

USGS1993

Water and tritium movement through the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Illinois, 1981-85

The movement of water and tritium through the unsaturated zone was studied at a low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois, from 1981 to 1985. Water and tritium movement occurred in an annual, seasonally timed cycle; recharge to the saturated zone generally occurred in the spring and early summer. Mean annual precipitation (1982-85) was 871 mm (millimeters); mean annual recharge to the disposal trenches (July 1982 through June 1984) was estimated to be 107 mm. Average annual tritium flux below the study trenches was estimated to be 3.4 mCi/yr (millicuries per year). Site geology, climate, and waste-disposal practices influenced the spatial and temporal variability of water and tritium movement. Of the components of the water budget, evapotranspiration contributed most to the temporal variability of water and tritium movement. Disposal trenches are constructed in complexly layered glacial and postglacial deposits that average 17 m (meters) in thickness and overlie a thick sequence of Pennsylvanian shale. The horizontal saturated hydraulic conductivity of the clayey-silt to sand-sized glacial and postglacial deposits ranges from 4.8x10 -1 to 3.4x10 4 mm/d (millimeters per day). A 120-m-long horizontal tunnel provided access for hydrologic measurements and collection of sediment and water samples from the unsaturated and saturated geologic deposits below four disposal trenches. Trench-cover and subtrench deposits were monitored with soil-moisture tensiometers, vacuum and gravity lysimeters, piezometers, and a nuclear soil-moisture gage. A cross-sectional, numerical ground-water-flow model was used to simulate water movement in the variably saturated geologic deposits in the tunnel area. Concurrent studies at the site provided water-budget data for estimating recharge to the disposal trenches. Vertical water movement directly above the trenches was impeded by a zone of compaction within the clayey-silt trench covers. Water entered the trenches primarily at the trench edges where the compacted zone was absent and the cover was relatively thin. Collapse holes in the trench covers that resulted from inadequate compaction of wastes within the trenches provided additional preferential pathways for surface-water drainage into the trenches; drainage into one collapse hole during a rainstorm was estimated to be 1,700 L (liters). Till deposits near trench bases induced lateral water and tritium movement. Limited temporal variation in water movement and small flow gradients (relative to the till deposits) were detected in the unsaturated subtrench sand deposit; maximum gradients during the spring recharge period averaged 1.62 mm/mm (millimeter per millimeter). Time-of-travel of water moving from the trench covers to below the trenches was estimated to be as rapid as 41 days (assuming individual water molecules move this distance in one recharge cycle). Tritium concentrations in water from the unsaturated zone ranged from 200 (background) to 10,000,000 pCi/L (picocuries per liter). Tritium concentrations generally were higher below trench bases (averaging 91,000 pCi/L) than below intertrench sediments (averaging 3,300 pCi/L), and in the subtrench Toulon Member of the Glasford Formation (sand) (averaging 110,000 pCi/L) than in the Hulick Till Member of the Glasford Formation (clayey silt) (averaging 59,000 pCi/L). Average subtrench tritium concentration increased from 28,000 to 100,000 pCi/L during the study period. Within the trench covers, there was a strong seasonal trend in tritium concentrations; the highest concentrations occurred in late summer when soil-moisture contents were at a minimum. Subtrench tritium movement occurred in association with the annual cycle of water movement, as well as independently of the cycle, in apparent response to continuous water movement through the subtrench sand deposits and to the deterioration of trench-waste containers. The increase in concen

Water Supply Paper↗

USGS2017

Pufferfish mortality associated with novel polar marine toxins in Hawaii

Fish die-offs are important signals in tropical marine ecosystems. In 2010, a mass mortality of pufferfish in Hawaii (USA) was dominated by Arothron hispidus showing aberrant neurological behaviors. Using pathology, toxinology, and field surveys, we implicated a series of novel, polar, marine toxins as a likely cause of this mass mortality. Our findings are striking in that (1) a marine toxin was associated with a kill of a fish species that is itself toxic; (2) we provide a plausible mechanism to explain clinical signs of affected fish; and (3) this epizootic likely depleted puffer populations. Whilst our data are compelling, we did not synthesize the toxin de novo, and we were unable to categorically prove that the polar toxins caused mortality or that they were metabolites of an undefined parent compound. However, our approach does provide a template for marine fish kill investigations associated with marine toxins and inherent limitations of existing methods. Our study also highlights the need for more rapid and cost-effective tools to identify new marine toxins, particularly small, highly polar molecules.

Hawaii↗

USGS1999

Antigenic and functional characterization of p57 produced by Renibacterium salmoninarum

Renibacterium salmoninarum , the causative agent of bacterial kidney disease, produces large quantities of a 57-58 kDa protein (p57) during growth in broth culture and during infection of salmonid fish. Biological activities of secreted p57 include agglutination of salrnonid leucocytes and rabbit erythrocytes. We define the location of epitopes on p57 recognized by agglutination-blocking monoclonal antibodies (MAbs) 4Cl1, 4H8 and 4D3, and demonstrate that the majority of secreted p57 is a nlonomer that retains salrnonid leucocyte agglutinat~ng activity. The 3 MAbs bound a recombinant, amino-terminal fragment of p57 (211 aa) but not a carboxy-terminal fragment (315 aa) demonstrating that the neutralizing epitopes are located within the amino-terminal portion of p57. When combinations of the MAbs were used in an antigen capture ELISA. the epitopes recognized by the 3 MAbs were shown to be sterically separate. However, when the same MAb was used as both the coating and detection MAb, binding of the biotinylated detection MAb was not observed. These data indicate that the epitopes recognized by the 3 agglutination-blocking antibodies are functionally available only once per molecule and that native p57 exists as a monomer Similar ELISA results were obtained when kidney tissues from 3 naturally infected chinook salmon were assayed. Finally, a p57 monomer was purified using anion exchange and size exclusion chromatography that retained in vitro agglutinating activity. A model in which p57 is released from R. salmoninarum as a biologically active monomer during infection of salmonid fish is proposed.

Diseases of Aquatic Organisms↗

USGS2002

Spring viremia of carp

pring viremia of carp (SVC) is an important disease affecting cyprinids, mainly common carp Cyprinus carpio . The disease is widespread in European carp culture, where it causes significant morbidity and mortality. Designated a notifiable disease by the Office International des Epizooties, SVC is caused by a rhabdovirus, spring viremia of carp virus (SVCV). Affected fish show destruction of tissues in the kidney, spleen and liver, leading to hemorrhage, loss of water-salt balance and impairment of immune response. High mortality occurs at water temperatures of 10 to 17°C, typically in spring. At higher temperatures, infected carp develop humoral antibodies that can neutralize the spread of virus and such carp are protected against re-infection by solid immunity. The virus is shed mostly with the feces and urine of clinically infected fish and by carriers. Waterborne transmission is believed to be the primary route of infection, but bloodsucking parasites like leeches and the carp louse may serve as mechanical vectors of SVCV. The genome of SVCV is composed of a single molecule of linear, negative-sense, single-stranded RNA containing 5 genes in the order 3¹-NPMGL-5¹ coding for the viral nucleoprotein, phosphoprotein, matrix protein, glycoprotein, and polymerase, respectively. Polyacrylamide gel electrophoresis of the viral proteins, and sequence homologies between the genes and gene junctions of SVCV and vesicular stomatitis viruses, have led to the placement of the virus as a tentative member of the genus Vesiculovirus in the family Rhabdoviridae . These methods also revealed that SVCV is not related to fish rhabdoviruses of the genus Novirhabdovirus . In vitro replication of SVCV takes place in the cytoplasm of cultured cells of fish, bird and mammalian origin at temperatures of 4 to 31°C, with an optimum of about 20°C. Spring viremia of carp can be diagnosed by clinical signs, isolation of virus in cell culture and molecular methods. Antibodies directed against SVCV react with the homologous virus in serum neutralization, immunofluorescence, immunoperoxidase, or enzyme-linked immunosorbent assays, but they cross-react to various degrees with the pike fry rhabdovirus (PFR), suggesting the 2 viruses are closely related. However, SVCV and PFR can be distinguished by certain serological tests and molecular methods such as the ribonuclease protection assay.

Diseases of Aquatic Organisms↗

USGS2018

Surveys of environmental DNA (eDNA): a new approach to estimate occurrence in Vulnerable manatee populations

Environmental DNA (eDNA) detection is a technique used to non-invasively detect cryptic, low density, or logistically difficult-to-study species, such as imperiled manatees. For eDNA measurement, genetic material shed into the environment is concentrated from water samples and analyzed for the presence of target species. Cytochrome b quantitative PCR and droplet digital PCR eDNA assays were developed for the 3 Vulnerable manatee species: African, Amazonian, and both subspecies of the West Indian (Florida and Antillean) manatee. Environmental DNA assays can help to delineate manatee habitat ranges, high use areas, and seasonal population changes. To validate the assay, water was analyzed from Florida’s east coast containing a high-density manatee population and produced 31564 DNA molecules l -1 on average and high occurrence (ψ) and detection (p) estimates (ψ = 0.84 [0.40-0.99]; p = 0.99 [0.95-1.00]; limit of detection 3 copies µl -1 ). Similar occupancy estimates were produced in the Florida Panhandle (ψ = 0.79 [0.54-0.97]) and Cuba (ψ = 0.89 [0.54-1.00]), while occupancy estimates in Cameroon were lower (ψ = 0.49 [0.09-0.95]). The eDNA-derived detection estimates were higher than those generated using aerial survey data on the west coast of Florida and may be effective for population monitoring. Subsequent eDNA studies could be particularly useful in locations where manatees are (1) difficult to identify visually (e.g. the Amazon River and Africa), (2) are present in patchy distributions or are on the verge of extinction (e.g. Jamaica, Haiti), and (3) where repatriation efforts are proposed (e.g. Brazil, Guadeloupe). Extension of these eDNA techniques could be applied to other imperiled marine mammal populations such as African and Asian dugongs.

Endangered Species Research↗

USGS2018

Volcanic ash activates the NLRP3 inflammasome in murine and human macrophages

Volcanic ash is a heterogeneous mineral dust that is typically composed of a mixture of amorphous (glass) and crystalline (mineral) fragments. It commonly contains an abundance of the crystalline silica (SiO 2 ) polymorph cristobalite. Inhalation of crystalline silica can induce inflammation by stimulating the NLRP3 inflammasome, a cytosolic receptor complex that plays a critical role in driving inflammatory immune responses. Ingested material results in the assembly of NLRP3, ASC, and caspase-1 with subsequent secretion of the interleukin-1 family cytokine IL-1β. Previous toxicology work suggests that cristobalite-bearing volcanic ash is minimally reactive, calling into question the reactivity of volcanically derived crystalline silica, in general. In this study, we target the NLRP3 inflammasome as a crystalline silica responsive element to clarify volcanic cristobalite reactivity. We expose immortalized bone marrow-derived macrophages of genetically engineered mice and primary human peripheral blood mononuclear cells (PBMCs) to ash from the Soufrière Hills volcano as well as representative, pure-phase samples of its primary componentry (volcanic glass, feldspar, cristobalite) and measure NLRP3 inflammasome activation. We demonstrate that respirable Soufrière Hills volcanic ash induces the activation of caspase-1 with subsequent release of mature IL-1β in a NLRP3 inflammasome-dependent manner. Macrophages deficient in NLRP3 inflammasome components are incapable of secreting IL-1β in response to volcanic ash ingestion. Cellular uptake induces lysosomal destabilization involving cysteine proteases. Furthermore, the response involves activation of mitochondrial stress pathways leading to the generation of reactive oxygen species. Considering ash componentry, cristobalite is the most reactive pure-phase with other components inducing only low-level IL-1β secretion. Inflammasome activation mediated by inhaled ash and its potential relevance in chronic pulmonary disease was further evidenced in PBMC using the NLRP3 small-molecule inhibitor CP-456,773 (CRID3, MCC950). Our data indicate the functional activation of the NLRP3 inflammasome by volcanic ash in murine and human macrophages in vitro . Cristobalite is identified as the apparent driver, thereby contesting previous assertions that chemical and structural imperfections may be sufficient to abrogate the reactivity of volcanically derived cristobalite. This is a novel mechanism for the stimulation of a pro-inflammatory response by volcanic particulate and provides new insight regarding chronic exposure to environmentally occurring particles.

Frontiers in Immunology↗

USGS2019

Comparison of methods for modeling fractional cover using simulated satellite hyperspectral imager spectra

Remotely sensed data can be used to model the fractional cover of green vegetation (GV), non-photosynthetic vegetation (NPV), and soil in natural and agricultural ecosystems. NPV and soil cover are difficult to estimate accurately since absorption by lignin, cellulose, and other organic molecules cannot be resolved by broadband multispectral data. A new generation of satellite hyperspectral imagers will provide contiguous narrowband coverage, enabling new, more accurate, and potentially global fractional cover products. We used six field spectroscopy datasets collected in prior experiments from sites with partial crop, grass, shrub, and low-stature resprouting tree cover to simulate satellite hyperspectral data, including sensor noise and atmospheric correction artifacts. The combined dataset was used to compare hyperspectral index-based and spectroscopic methods for estimating GV, NPV, and soil fractional cover. GV fractional cover was estimated most accurately. NPV and soil fractions were more difficult to estimate, with spectroscopic methods like partial least squares (PLS) regression, spectral feature analysis (SFA), and multiple endmember spectral mixture analysis (MESMA) typically outperforming hyperspectral indices. Using an independent validation dataset, the lowest root mean squared error (RMSE) values were 0.115 for GV using either normalized difference vegetation index (NDVI) or SFA, 0.164 for NPV using PLS, and 0.126 for soil using PLS. PLS also had the lowest RMSE averaged across all three cover types. This work highlights the need for more extensive and diverse fine spatial scale measurements of fractional cover, to improve methodologies for estimating cover in preparation for future hyperspectral global monitoring missions.

Remote Sensing↗

USGS2020

Disk-integrated thermal properties of Ceres measured at the millimeter wavelengths

We observed Ceres at three epochs in 2015 November and 2017 September and October with Atacama Large Millimeter/submillimeter Array (ALMA) 12 m array and in 2017 October with the ALMA Compact Array (ACA), all at ~265 GHz continuum (wavelengths of ~1.1 mm) to map the temperatures of Ceres over a full rotation at each epoch. We also used 2017 October ACA observations to search for HCN. The disk-averaged brightness temperature of Ceres is measured to be between 170 and 180 K during our 2017 observations. The rotational light curve of Ceres shows a double-peaked shape with an amplitude of about 4%. Our HCN search returns a negative result with an upper limit production rate of ~2 × 10 24 molecules s −1 , assuming globally uniform production and a Haser model. A thermophysical model suggests that Ceres's top layer has higher dielectric absorption than lunar-like materials at a wavelength of 1 mm. However, previous observations showed that the dielectric absorption of Ceres decreases toward longer wavelengths. Such distinct dielectric properties might be related to the hydrated phyllosilicate composition of Ceres and possibly abundant micrometer-sized grains on its surface. The thermal inertia of Ceres is constrained by our modeling as likely being between 40 and 160 thermal inertia units, much higher than previous measurements at infrared wavelengths. Modeling also suggests that Ceres's light curve is likely dominated by spatial variations in its physical or compositional properties that cause changes in Ceres's observed thermal properties and dielectric absorption as it rotates.

Astronomical Journal↗

USGS1979

Membrane immunoglobulin is present on thymic and splenic lymphocytes of the trout Salmo gairdneri

Three rabbit antisera raised to trout IgM showed positive immunofluorescent reactions with lymphocytes of trout spleen and thymus. These antisera showed no detectable cross-reactivity with keyhole limpet hemocyanin, as determined by direct radioimmune precipitation and adsorption, and did not appeare to react significantly with carbohydrate moieties on trout IgM, as determined by the failure of proteolytic digests of trout IgM to inhibit in radioimmunoassay against intact trout IgM. Membrane immunoglobulin determinants were detectable on the membrane of both thymocytes and splenocytes with the lactoperoxidase-catalyzed iodination reaction. Radioimmunoassay of lysates of lymphocytes confirmed the association of immunoglobulin with trout thymocytes. By radioimmunoassay, lysates of thymic and splenic lymphocytes contained similar amounts of immunoglobulin, equivalent to approximately 8 × 10 4 molecules of IgM per cell (calculated as the monomer µ 2 L 2 ).

Journal of Immunology↗

USGS2004

Cloning, expression, cellular distribution, and role in chemotaxis of a C5a receptor in rainbow trout: The first identification of a C5a receptor in a nonmammalian species

C3a, C4a, and C5a anaphylatoxins generated during complement activation play a key role in inflammation. C5a is the most potent of the three anaphylatoxins in eliciting biological responses. The effects of C5a are mediated by its binding to C5a receptor (C5aR, CD88). To date, C5aR has only been identified and cloned in mammalian species, and its evolutionary history remains ill-defined. To gain insights into the evolution, conserved structural domains, and functions of C5aR, we have cloned and characterized a C5aR in rainbow trout, a teleost fish. The isolated cDNA encoded a 350-aa protein that showed the highest sequence similarity to C5aR from other species. Genomic analysis revealed the presence of one continuous exon encoding the entire open reading frame. Northern blot analysis showed significant expression of the trout C5a receptor (TC5aR) message in PBLs and kidney. Flow cytometric analysis showed that two Abs generated against two different areas of the extracellular N-terminal region of TC5aR positively stained the same leukocyte populations from PBLs. B lymphocytes and granulocytes comprised the majority of cells recognized by the anti-TC5aR. More importantly, these Abs inhibited chemotaxis of PBLs toward a chemoattractant fraction purified from complement-activated trout serum. Our data suggest that the split between C5aR and C3aR from a common ancestral molecule occurred before the emergence of teleost fish. Moreover, we demonstrate that the overall structure of C5aR as well as its role in chemotaxis have remained conserved for >300 million years.

Journal of Immunology↗

USGS2021

Endophytic bacteria in grass crop growth promotion and biostimulation

Plants naturally carry microbes on seeds and within seeds that may facilitate development and early survival of seedlings. Some crops have lost seed-vectored microbes in the process of domestication or during seed storage and seed treatment. Biostimulant microbes from wild plants were used by pre-modern cultures to re-acquire beneficial seed microbes. Today some companies have developed or are developing the use of microbes obtained from soils or plant sources to stimulate plant development and growth. Many of these biostimulant microbes are endophytic in plants. Biostimulant products also include humic substances, which appear to function as signal molecules in plants, triggering increased internalization of soil microbes into root cells and tissues. In addition, protein coatings on seeds fuel the growth of seed surface-vectored microbes, increasing microbial activity around and within roots. In this article, we provide evidence of the endophytic nature of many biostimulant microbes, and suggest that many of the beneficial effects of microbial biostimulants stem from their action as endophytes or as participants or stimulants of rhizophagy cycle activity.

Grass Research↗

USGS2011

Early in-flight detection of SO 2 via Differential Optical Absorption Spectroscopy: A feasible aviation safety measure to prevent potential encounters with volcanic plumes

Volcanic ash constitutes a risk to aviation, mainly due to its ability to cause jet engines to fail. Other risks include the possibility of abrasion of windshields and potentially serious damage to avionic systems. These hazards have been widely recognized 5 since the early 1980s, when volcanic ash provoked several incidents of engine failure in commercial aircraft. In addition to volcanic ash, volcanic gases also pose a threat. Prolonged and/or cumulative exposure to sulphur dioxide (SO 2 ) or sulphuric acid (H 2 SO 4 ) aerosols potentially affects e.g. windows, air frame and may cause permanent damage to engines. SO 2 receives most attention among the gas species commonly found in 10 volcanic plumes because its presence above the lower troposphere is a clear proxy for a volcanic cloud and indicates that fine ash could also be present. Up to now, remote sensing of SO 2 via Differential Optical Absorption Spectroscopy (DOAS) in the ultraviolet spectral region has been used to measure volcanic clouds from ground based, airborne and satellite platforms. Attention has been given to vol- 15 canic emission strength, chemistry inside volcanic clouds and measurement procedures were adapted accordingly. Here we present a set of experimental and model results, highlighting the feasibility of DOAS to be used as an airborne early detection system of SO 2 in two spatial dimensions. In order to prove our new concept, simultaneous airborne and ground-based measurements of the plume of Popocatepetl volcano, Mexico, were conducted in April 2010. The plume extended at an altitude around 5250 m above sea level and was approached and traversed at the same altitude with several forward looking DOAS systems aboard an airplane. These DOAS systems measured SO 2 in the flight direction and at ±40 mrad (2.3◦) angles relative to it in both, horizontal and vertical directions. The approaches started at up to 25 km distance to 25 the plume and SO 2 was measured at all times well above the detection limit. In combination with radiative transfer studies, this study indicates that an extended volcanic cloud with a concentration of 1012 molecules cm−3 at typical flight levels of 10 km can be detected unambiguously at distances of up to 80 km away. This range provides enough time (approx. 5 min) for pilots to take action to avoid entering a volcanic cloud in the flight path, suggesting that this technique can be used as an effective aid to prevent dangerous aircraft encounters with potentially ash rich volcanic clouds.

Popocatepetl volcano↗

USGS2025

Ageing of organic materials at the surface of Mars: A Raman study aboard Perseverance

The Perseverance rover is exploring Jezero crater on Mars, one of its goals being to collect samples to be returned to Earth to search for organic remains of ancient Martian life. However, the organic content of these rocks has likely suffered from the radiation environment on the surface of Mars to an extent yet to be quantified. For the first time, a 1000 sols long ageing experiment was conducted at the surface of Mars, i.e. under actual Martian conditions, relying on the 100 % organic Ertalyte target carried by Perseverance. White at landing, the Ertalyte target has turned brown with time, while its Raman signal changed, with a modification of the background (its maximum has shifted from 1500 to 2000 cm −1 ) and a reduction of the contribution of the Raman signal of Ertalyte (by a factor of 5 over the first 500 sols). Given the intrinsic resistance of the Ertalyte to UV exposure, which is not anticipated for most Martian organic materials, these results suggest that exposure at the surface of Mars will make the detection of Martian organic molecules challenging.

Geochemical Perspectives Letters↗

USGS2023

Isothermal recombinant polymerase amplification and CRIPSR (CAS12A) assay detection of Renibacterium salmoninarum as an example for wildlife pathogen detection in environmental DNA samples

Improving rapid detection methods for pathogens is important for research as we collectively aim to improve the health of ecosystems globally. In the northern hemisphere, the success of salmon ( Oncorhynchus spp.) populations is vitally important to the larger marine, aquatic, and terrestrial ecosystems they inhabit. This has led to managers cultivating salmon in hatcheries and aquaculture to bolster their populations, but young salmon face many challenges, including diseases such as bacterial kidney disease (BKD). Early detection of the BKD causative agent, Renibacterium salmoninarum , is useful for managers to avoid outbreaks in hatcheries and aquaculture stocks to enable rapid treatment with targeted antibiotics. Isothermal amplification and CRIPSR-Cas12a systems may enable sensitive, relatively rapid, detection of target DNA molecules from environmental samples compared to quantitative PCR (qPCR) and culture methods. We used these technologies to develop a sensitive and specific rapid assay to detect R. salmoninarum from water samples using isothermal recombinase polymerase amplification (RPA) and an AsCas12a RNA-guided nuclease detection. The assay was specific to R. salmoninarum (0/10 co-occurring or closely related bacteria detected) and sensitive to 0.0128 pg/µL of DNA (approximately 20–40 copies/µL) within 10 min of Cas activity. This assay successfully detected R. salmoninarum environmental DNA in 14/20 water samples from hatcheries with known quantification for the pathogen via previous qPCR (70% of qPCR-positive samples). The RPA-CRISPR/AsCas12a assay had a limit of detection (LOD) of >10 copies/µL in the hatchery water samples and stochastic detection below 10 copies/µL, similar to but slightly higher than the qPCR assay. This LOD enables 37 C isothermal detection, potentially in the field, of biologically relevant levels of R. salmoninarum in water. Further research is needed to develop easy-to-use, cost-effective, sensitive RPA/CRISPR-AsCas12a assays for rapidly detecting low concentrations of wildlife pathogens in environmental samples.

Journal of Wildlife Diseases↗