USGS Science⌕ Search

SEARCH · USGS Science

Results for “Experimental Results”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources
USGS1969

Well logging with californium-252

Californium 252 is an isotopic neutron source that has only recently become available for experimental well logging. One curie of 252Cf emits 4.4 x 109 neutrons per second by spontaneous fission, 300 times the emission rate of any other one curie radioisotopic source. California 252 has several other advantages as a high yield source for well logging: very small physical size, low gamma and heat emission, and expected low cost relative to other sources. A 50-millicurie 252Cf source fabricated at the Savannah River Laboratory was made available by the U. S. Atomic Energy Commission to the U. S. Geological Survey for a feasibility study on well logging. The nuclear and physical characteristics of this source and some of the health physics aspects of its use in the field are discussed. The source was used to make epithermal neutron logs, which are compared with logs made with plutonium beryllium and americium beryllium sources in the same well. The high neutron flux available from 252Cf permitted the use of longer than usual spacing while maintaining a high count rate and excellent sensitivity. In addition, continuous activation logs were made utilizing a spacing of 5. 5 feet from the source to detector. Aluminum 28 was identified as the chief radioisotope contributing to the log response. This new technique may provide a log more closely related to clay content than the natural gamma log. Stationary irradiation experiments were also carried out in boreholes, and sodium 24 and manganese 56 were readily produced and identified. Suggestions for additional research on logging applications and problems resulted from this feasibility study. Potential well logging applications not investigated include the activation of temporary depth markers and the use of stable tracers that can be activated at the site or in the well. The high neutron yield of californium 252 will facilitate in situ activation analysis for many elements as an aid to exploration for oil, water, and other minerals.

Conference Paper↗
USGS2013

Crystallization of oxidized, moderately hydrous arc basalt at mid- to lower-crustal pressures: Implications for andesite genesis

This study focuses on the production of convergent margin calc-alkaline andesites by crystallization–differentiation of basaltic magmas in the lower to middle crust. Previous experimental studies show that dry, reduced, subalkaline basalts differentiate to tholeiitic (high Fe/Mg) daughter liquids, but the influences of H 2 O and oxidation on differentiation are less well established. Accordingly, we performed crystallization experiments at controlled oxidized fO 2 (Re–ReO 2 ≈ ΔNi–NiO + 2) on a relatively magnesian basalt (8.7 wt% MgO) typical of mafic magmas erupted in the Cascades near Mount Rainier, Washington. The basalt was synthesized with 2 wt% H2O and run at 900, 700, and 400 MPa and 1,200 to 950 °C. A broadly clinopyroxenitic crystallization interval dominates near the liquidus at 900 and 700 MPa, consisting of augite + olivine + orthopyroxene + Cr-spinel (in decreasing abundance). With decreasing temperature, plagioclase crystallizes, Fe–Ti-oxide replaces spinel, olivine dissolves, and finally amphibole appears, producing gabbroic and then amphibole gabbroic crystallization stages. Enhanced plagioclase stability at lower pressure narrows the clinopyroxenitic interval and brings the gabbroic interval toward the liquidus. Liquids at 900 MPa track along Miyashiro’s (Am J Sci 274(4):321–355, 1974) tholeiitic versus calc-alkaline boundary, whereas those at 700 and 400 MPa become calc-alkaline at silica contents ≥56 wt%. This difference is chiefly due to higher temperature appearance of magnetite (versus spinel) at lower pressures. Although the evolved liquids are similar in many respects to common calc-alkaline andesites, the 900 and 700 MPa liquids differ in having low CaO concentrations due to early and abundant crystallization of augite, with the result that those liquids become peraluminous (ASI: molar Al/(Na + K + 2Ca) > 1) at ≥61 wt% SiO 2 , similar to liquids reported in other studies of the high-pressure crystallization of hydrous basalts (Müntener and Ulmer in Geophys Res Lett 33(21):L21308, 2006). The lower-pressure liquids (400 MPa) have this same trait, but to a lesser extent due to more abundant near-liquidus plagioclase crystallization. A compilation of >6,500 analyses of igneous rocks from the Cascades and the Sierra Nevada batholith, representative of convergent margin (arc) magmas, shows that ASI increases continuously and linearly with SiO2 from basalts to rhyolites or granites and that arc magmas are not commonly peraluminous until SiO 2 exceeds 69 wt%. These relations are consistent with plagioclase accompanying mafic silicates over nearly all the range of crystallization (or remelting). The scarcity of natural peraluminous andesites shows that progressive crystallization–differentiation of primitive basalts in the deep crust, producing early clinopyroxenitic cumulates and evolved liquids, does not dominate the creation of intermediate arc magmas or of the continental crust. Instead, mid- to upper-crustal differentiation and/or open-system processes are critical to the production of intermediate arc magmas. Primary among the open-system processes may be extraction of highly evolved (granitic, rhyolitic) liquids at advanced degrees of basalt solidification (or incipient partial melting of predecessor gabbroic intrusions) and mixing of such liquids into replenishing basalts. Furthermore, if the andesitic-composition continents derived from basaltic sources, the arc ASI–SiO 2 relation shows that the mafic component returned to the mantle was gabbroic in composition, not pyroxenitic.

Contributions to Mineralogy and Petrology↗
USGS2024

Immunomodulation in adult largemouth bass (Micropterus salmoides) exposed to a model estrogen or mixture of endocrine disrupting contaminants during early gonadal recrudescence

Disease outbreaks, skin lesions, fish kill events, and reproductive abnormalities have been observed in wild populations of Centrarchids in watersheds throughout the United States. Occurrence of synthetic and natural hormones from wastewater treatment plants and livestock operations, pesticides from agricultural land use, and phytoestrogens have been implicated as potential causes of these adverse effects. Our objective was to investigate possible immunomodulation in adult largemouth bass ( Micropterus salmoides ) in response to a seasonal exposure to environmentally relevant contaminants in outdoor experimental ponds. Exposures included 17α-ethinylestradiol (EE2; 3.6 ng/L) or a binary mixture of endocrine-active substances commonly detected in surface waters, estrone (E1; 85.6 ng/L) and atrazine (ATR; 5.4 µg/L). The 4-month exposure was conducted from July to November. Functional immune responses of anterior kidney-derived leukocytes were evaluated in December in the week following the end of the dosing period, and in the following April, four months after dosing ended and just prior to spawning. Concentrations of EE2 and E1 in the ponds fell below detectable levels in December, but detectable concentrations of ATR (2.9 µg/L) persisted at least through May. For each sampling time, anterior kidney leukocytes were isolated and grown in primary culture for the assessment of zymosan-stimulated respiratory burst and lectin-stimulated mitogenic responses. We observed seasonal differences in respiratory burst stimulation over time and treatment with a significantly greater response in April relative to December. Respiratory burst activity was also significantly greater in April for fish exposed to the E1+ATR relative to control. In April, prior to spawning, we observed a significantly dampened mitogenic response to PHAP (a T cell mitogen) and LPS (a B cell mitogen) in the EE2 treatment relative to control fish. There were no significant differences in mitogenic responses or respiratory burst between sexes. However, there was significantly higher alternative complement pathway hemolytic activity in males compared to females in both the control and E1+ATR treatment groups. Our results demonstrate that environmentally relevant concentrations of contaminants can alter immune function in a socioeconomically important fish species.

Comparative Immunology Reports↗
USGS2024

Outmigration behavior and survival of juvenile Chinook salmon (Oncorhynchus tshawytscha) in response to deep drawdown of the Lookout Point Project, Middle Fork Willamette River, Oregon

An acoustic telemetry study was conducted during August 2023–February 2024 to evaluate outmigration behavior and survival of juvenile Chinook salmon (Oncorhynchus tshawytscha) in the Middle Fork Willamette River, Oregon, during an experimental operation that was designed to facilitate downstream passage through two reservoirs and two dams. The experimental operation consisted of lowering the water surface elevation of Lookout Point Reservoir by nearly 100 feet between August and December 2023, and passing water through regulating outlets at Lookout Point Dam. This operation was intended to reduce residence time for juvenile Chinook salmon in Lookout Point Reservoir so that these fish would enter the free-flowing Willamette River as quickly as possible. During our study, acoustic-tagged juvenile Chinook salmon were released weekly during late August to late October to determine how fish responded to the drawdown. Data collected during the study were analyzed using a temporally stratified multistate mark-recapture model. We found that Lookout Point Reservoir became isothermic during the drawdown and water temperature exceeded 18 degrees Celsius during most of September 2023. This appeared to adversely affect juvenile Chinook salmon because the proportion of tagged fish that were subsequently detected in the forebay of Lookout Point Dam following release at the head of Lookout Point Reservoir during August 30–September 29 ranged from 0.01 to 0.05 for weekly release groups. Detections increased to 0.44–0.52 for fish released later in the year when water temperatures decreased. We found that fish size was a significant predictor of survival as fork length was positively related to survival probability in reservoir and free-flowing river reaches of our study area, but negatively related to survival probability for fish passing Lookout Point Dam. We also found that increased regulating outlet flow at Lookout Point Dam resulted in increased survival probability for juvenile Chinook salmon and water temperature was inversely related to survival. Results from this study suggest that the drawdown failed to create conditions that facilitated downstream passage and survival of juvenile Chinook salmon through the Lookout Point Project. Our analysis provides insights into several key factors that influence survival. This information can be used by resource managers when considering revised operations that may lead to improved outmigration survival in the future.

Oregon↗
USGS2010

Augustine Volcano - The influence of volatile components in magmas erupted A.D. 2006 to 2,100 years before present: Chapter 16 in The 2006 eruption of Augustine Volcano, Alaska

The petrology and geochemistry of 2006 eruptive products of Augustine Volcano, Alaska, have been investigated through analyses of whole-rock samples, phenocrysts, silicate melt inclusions, and matrix glasses to constrain processes of magma evolution, eruption, and degassing. Particular attention was directed toward the concentrations and geochemical relationships involving the magmatic volatile components H 2 O, CO 2, S, and Cl. The analytical results for 2006 samples have been integrated with data for samples of Pleistocene basalt, prehistoric andesites, and 1986 andesites from Augustine to provide a broad view of volatile behavior in Augustine magmas. The observation of generally similar geochemical features for this range of eruptions indicates that magmatic and volatile degassing processes have been relatively consistent during the past 2,100 years. Augustine andesites range from low-silica to high-silica compositions and contain phenocrysts of plagioclase, orthopyroxene, and clinopyroxene, with lesser olivine, amphiboles, iron-titanium oxides, and apatite. The groundmass varies from strongly crystallized and/or oxidized to comparatively clear, microlite-poor vesicular glass. Coexisting iron-titanium oxides of 2006 rock samples, which are generally consistent with those of prior eruptive materials, indicate ƒ O2 values of approximately NNO+1.5 to NNO+2.5 and oxide crystallization temperatures of 835 to 1,052°C. The compositions of matrix and melt-inclusion glasses range from rhyodacite to rhyolite and show relationships that reflect magma evolution involving fractional crystallization and multiple stages of mingling and/or mixing. In particular, melt inclusions of low-silica andesites express mixing of magmas with more widely varying compositions, than do melt inclusions of high-silica andesites and dacites. The melt inclusions of 2006, 1986, and prehistoric andesites contain moderate to high concentrations of H 2 O and Cl and lesser CO 2 and SO 2 . Comparing the abundances of H 2 O, CO 2 , and Cl in these melt inclusions with experimentally established volatile solubilities for felsic melts indicates that the 2006 and prehistoric samples are most consistent with the ascent of fluid-saturated magmas containing 1 weight percent of H 2 O-enriched vapor under closed-system conditions and that pressures of volatile phase exsolution range from 150 to less than 20 MPa. This closed-system behavior was maintained to quite shallow depths prior to eruption, and this pressure range is consistent with constraints derived from 2006 geodetic measurements indicating magma storage and crystallization at 4 to 6 km and upwards to near-surface depths. The magmatic fluids were relatively oxidizing and included H 2 O-enriched and HCl-, H 2 S-, S 2 -, and SO 2 ± CO 2 -bearing vapors; hydrosaline aqueous liquids largely enriched in Cl - , SO 4 2- , alkalis, and H 2 O; and moderately saline, H 2 O-poor liquids containing Cl - , SO 4 2- , and alkali elements.

Alaska↗
USGS2012

Ecological impacts of non-native species

Non-native species are considered one of the greatest threats to freshwater biodiversity worldwide (Drake et al. 1989; Allen and Flecker 1993; Dudgeon et al. 2005). Some of the first hypotheses proposed to explain global patterns of amphibian declines included the effects of non-native species (Barinaga 1990; Blaustein and Wake 1990; Wake and Morowitz 1991). Evidence for the impact of non-native species on amphibians stems (1) from correlative research that relates the distribution or abundance of a species to that of a putative non-native species, and (2) from experimental tests of the effects of a non-native species on survival, growth, development or behaviour of a target species (Kats and Ferrer 2003). Over the past two decades, research on the effects of non-native species on amphibians has mostly focused on introduced aquatic predators, particularly fish. Recent research has shifted to more complex ecological relationships such as influences of sub-lethal stressors (e.g. contaminants) on the effects of non-native species (Linder et al. 2003; Sih et al. 2004), non-native species as vectors of disease (Daszak et al. 2004; Garner et al. 2006), hybridization between non-natives and native congeners (Riley et al. 2003; Storfer et al. 2004), and the alteration of food-webs by non-native species (Nystrom et al. 2001). Other research has examined the interaction of non-native species in terms of facilitation (i.e. one non-native enabling another to become established or spread) or the synergistic effects of multiple non-native species on native amphibians, the so-called invasional meltdown hypothesis (Simerloff and Von Holle 1999). Although there is evidence that some non-native species may interact (Ricciardi 2001), there has yet to be convincing evidence that such interactions have led to an accelerated increase in the number of non-native species and cumulative impacts are still uncertain (Simberloff 2006). Applied research on the control, eradication, and management of non-native species has only just begun but some promising results have already emerged (see below), giving hope to a very difficult conservation issue. This chapter provides an overview of the role of non-native species in amphibian declines and summarizes the current state of knowledge of non-native species that are known, or considered to be, a threat to amphibian species and populations. The biological and socio-economic issues of non-native species control are examined and brief case studies of successful eradication programmes are provided.

Book chapter↗
USGS2012

Ecological impacts of non-native species

Non-native species are considered one of the greatest threats to freshwater biodiversity worldwide (Drake et al. 1989; Allen and Flecker 1993; Dudgeon et al. 2005). Some of the first hypotheses proposed to explain global patterns of amphibian declines included the effects of non-native species (Barinaga 1990; Blaustein and Wake 1990; Wake and Morowitz 1991). Evidence for the impact of non-native species on amphibians stems (1) from correlative research that relates the distribution or abundance of a species to that of a putative non-native species, and (2) from experimental tests of the effects of a non-native species on survival, growth, development or behaviour of a target species (Kats and Ferrer 2003). Over the past two decades, research on the effects of non-native species on amphibians has mostly focused on introduced aquatic predators, particularly fish. Recent research has shifted to more complex ecological relationships such as influences of sub-lethal stressors (e.g. contaminants) on the effects of non-native species (Linder et al. 2003; Sih et al. 2004), non-native species as vectors of disease (Daszak et al. 2004; Garner et al. 2006), hybridization between non-natives and native congeners (Riley et al. 2003; Storfer et al. 2004), and the alteration of food-webs by non-native species (Nystrom et al. 2001). Other research has examined the interaction of non-native species in terms of facilitation (i.e. one non-native enabling another to become established or spread) or the synergistic effects of multiple non-native species on native amphibians, the so-called invasional meltdown hypothesis (Simerloff and Von Holle 1999). Although there is evidence that some non-native species may interact (Ricciardi 2001), there has yet to be convincing evidence that such interactions have led to an accelerated increase in the number of non-native species and cumulative impacts are still uncertain (Simberloff 2006). Applied research on the control, eradication, and management of non-native species has only just begun but some promising results have already emerged (see below), giving hope to a very difficult conservation issue. This chapter provides an overview of the role of non-native species in amphibian declines and summarizes the current state of knowledge of non-native species that are known, or considered to be, a threat to amphibian species and populations. The biological and socio-economic issues of non-native species control are examined and brief case studies of successful eradication programmes are provided.

Book chapter↗
USGS2014

Lesser prairie-chicken nest site selection, microclimate, and nest survival in association with vegetation response to a grassland restoration program

Climate models predict that the region of the Great Plains Landscape Conservation Cooperative (GPLCC) will experience increased maximum and minimum temperatures, reduced frequency but greater intensity of precipitation events, and earlier springs. These climate changes along with different landscape management techniques may influence the persistence of the lesser prairie-chicken (Tympanuchus pallidicinctus), a candidate for protection under the Endangered Species Act and a priority species under the GPLCC, in positive or negative ways. The objectives of this study were to conduct (1) a literature review of lesser prairie-chicken nesting phenology and ecology, (2) an analysis of thermal aspects of lesser prairie-chicken nest microclimate data, and (3) an analysis of nest site selection, nest survival, and vegetation response to 10 years of tebuthiuron and/or grazing treatments. We found few reports in the literature containing useful data on the nesting phenology of lesser prairie-chickens; therefore, managers must rely on short-term observations and measurements of parameters that provide some predictive insight into climate impacts on nesting ecology. Our field studies showed that prairie-chickens on nests were able to maintain relatively consistent average nest temperature of 31 °C and nest humidities of 56.8 percent whereas average external temperatures (20.3–35.0 °C) and humidities (35.2–74.9 percent) varied widely throughout the 24 hour (hr) cycle. Grazing and herbicide treatments within our experimental areas were designed to be less intensive than in common practice. We determined nest locations by radio-tagging hen lesser prairie-chickens captured at leks, which are display grounds at which male lesser prairie-chickens aggregate and attempt to attract a female for mating. Because nest locations selected by hen lesser prairie-chicken are strongly associated with the lek at which they were captured, we assessed nesting habitat use on the basis of hens captured at individual leks, and then for all leks pooled. There was no clear pattern of selection for treatment type for nest placement among hens associated with individual leks; however, when hens from all leks were pooled, we found nesting lesser prairie-chickens selected control plots for nesting over plots that were grazed, treated with tebuthiuron, or were both grazed and treated with tebuthiuron. Overall, the probability of a nest surviving the incubation period was 0.57 for this study and did not vary significantly among treatment types. In contrast to nesting preference for untreated habitats, lek use exhibited no noticeable selection of treatment type. Over the 10 years of the habitat management study, there was 91 percent less sand shinnery oak (Quercus havardii) in treated areas than untreated areas. The removal of sand shinnery oak made environmental soil moisture more available for grasses and forbs to germinate and grow. Grasses increased by 149 percent and forbs increased by 257 percent in treated areas as compared to untreated areas throughout the study period. Our combined results, including our habitat selection analysis at the individual lek level, indicated that reduced rates of herbicide and short-duration grazing treatments were not detrimental to nesting lesser prairie-chickens and that populations of lesser prairie-chickens in shrub-dominated ecosystems may benefit from reduced rates of herbicide application and short duration of grazing that results in increased habitat heterogeneity.

New Mexico;Texas↗
USGS2005

Development of thiamine deficiencies and early mortality syndrome in lake trout by feeding experimental and feral fish diets containing thiaminase

We conducted a laboratory investigation on the consequences of feeding predatory salmonids either experimental diets low in thiamine or diets containing alewife Alosa pseudoharengus . In experiment 1, adult lake trout Salvelinus namaycush were fed experimental diets containing bacterial thiaminase. In experiment 2, adult lake trout were fed natural prey species, alewives, and bloaters Coregonus hoyi . The diets consisted of four combinations of alewives and bloaters from Lake Michigan (100% alewives, 65% alewives–35% bloaters, 35% alewives–65% bloaters, and 100% bloaters), alewives from Cayuga Lake, a casein bacterial thiaminase, and a commercial trout diet. We assessed the effects of each diet on egg thiamine concentration and incidence of an embryonic early mortality syndrome (EMS). In experiment 1, incidence of EMS ranged from 0% to 100%. Significant relationships were found between the incidence of EMS and thiamine. In experiment 2, adult lake trout fed 100% alewives from either Lake Michigan or Cayuga Lake or fish fed the casein bacterial thiaminase diet produced eggs with low thiamine and swim-up fry with EMS. At either 35% or 65% alewives in the diet, egg thiamine was significantly lowered. The number of females that produced offspring that died from EMS were low but demonstrated the negative potential if feral lake trout foraged on either 35% or 65% alewives. Depleted egg thiamine and the onset of EMS required diets containing thiaminase for a minimum of 2 years in lake trout initially fully thiamine replete. We conclude that EMS can be caused by extensive feeding on 100% alewives and dietary levels of 35% or greater may prove detrimental to sustainable reproduction of salmonids in the Great Lakes. The data are consistent with that observed in feral lake trout, and it is concluded that EMS is the result of a thiamine deficiency.

Journal of Aquatic Animal Health↗
USGS2024

Pliocene Model Intercomparison Project Phase 3 (PlioMIP3) – Science plan and experimental design

The Pliocene Model Intercomparison Project (PlioMIP) was initiated in 2008. Over two phases PlioMIP has helped co-ordinate the experimental design and publication strategy of the community, which has included an increasing number of climate models and modelling groups from around the world. It has engaged with palaeoenvironmental scientists to foster new data synthesis supporting the construction of new model boundary conditions, as well as to facilitate new data-model comparisons. The work has advanced our understanding of Pliocene climates and environments, enhanced our knowledge regarding the ability of complex climate and Earth System models to accurately simulate climate change, and helped to refine our estimates of how sensitive the climate system is to forcing conditions. In this community protocol paper, we outline the scientific plan for PlioMIP Phase 3 (PlioMIP3). This plan provides the required guidance to participating modelling groups from around the world to successfully set up and perform PlioMIP3 climate model experiments. The project is open to new participants from the scientific community (both from the climate modelling and geosciences communities). In PlioMIP3, we retain the PlioMIP2 Core experiments ( Eoi 400 , E 280 ) and extend the Core requirements to include either an experiment focussed on the Early Pliocene or an alternative Late Pliocene simulation (or both). These additions (a) allow a comparison of Early and Late Pliocene warm intervals and help build research connections and synergy with the MioMIP (Miocene Model Intercomparison Project - also known as DeepMIP-Miocene) and PlioMioVAR projects (Pliocene-Miocene Variability Working Group), and (b) create an alternative time slice simulation for 3.205 Ma (MIS KM5c) through removal of some of the largest palaeogeographic differences introduced between PlioMIP1 and 2 resulting in minimal land-sea mask variations from the modern. In addition, we present ten optional experiments designed to enhance our assessment of climate sensitivity and to explore the uncertainty in greenhouse gas-related forcing. For the first time, we introduce orbital sensitivity experiments into the science plan, as well as simulations incorporating dynamic vegetation-climate feedbacks and an experiment designed to examine the potential significance of East Antarctic Ice Sheet boundary condition uncertainty. These changes enhance palaeo-to-future scientific connections and enable an exploration of the significance of palaeogeographic uncertainties on climate simulations.

Global and Planeatary Change↗
USGS1982

Eruptive history, petrology, and petrogenesis of the Joe Lott Tuff Member of the Mount Belknap Volcanics, Marysvale volcanic field, west-central Utah

The Joe Lott Tuff Member of the Mount Belknap Volcanics is the largest rhyolitic ash-flow tuff sheet in the Marysvale volcanic field. It was erupted 19 m.y. ago, shortly after the changeover from intermediate-composition calc-alkalic volcanism to bimodal basalt-rhyolite volcanism. Eruption of the tuff resulted in the formation of the Mount Belknap Caldera whose pyroclastic intracaldera stratigraphy parallels that in the outflow facies. The Joe Loft Tuff Member is a composite ash-flow sheet that changes laterally from a simple cooling unit near the source to four distinct cooling units toward the distal end. The lowest of these units is the largest and most widespread; it is 64 m thick and contains a basal vitrophyre. Eruption of the lower unit led to the initial collapse of the caldera. The lower unit is followed upward by a 43 m middle unit, a 26 m pink-colored unit which is separated by a prominent air- fall layer, and a 31 m upper unit. The Joe Loft Tuff Member is an alkali rhyolite with 75.85-77.31 wt. % silica and 8.06-9.32 wt. % K2O+Na2O; the agpaitic index (Na2O+ K2O/Al2O3) is .77-.98. The tuff contains about I% phenocrysts of quartz, sanidine, oligoclase, augite, apatite, zircon, sphene, biotite, and oxidized Fe-Ti oxides. The basal vitrophyre contains accessory allanite, chevkinite, and magnesiohastingsite. The main cooling units are chemically and mineralogically zoned indicating that the magma chamber restratified prior to each major eruption. Within each of the two thickest cooling units, the mineralogy changes systematically upwards; the Or content and relative volume of sanidine decreases and An content of plagioclase increases. The basal vitrophyre of the lower unit has a bulk composition that lies in the thermal trough near the minima of Or-Ab-Q at 1 kb PH2O. Microprobe analyses of feldspar and chemical modeling on experimental systems indicate that pre-eruption temperatures were near 750?C and that the temperature increased during the eruption of the cooling units. The chemical gradients in the apatite and whole-rock data in the Joe Loft Tuff Member and the consistent mineral assemblages throughout the ash-flow cannot be explained by crystal settling. The fractionation of the Joe Lott Tuff Member appears to closer fit the model of convection-driven thermogravitational diffusion.

Open-File Report↗
USGS2018

Energetic costs of locomotion in bears: is plantigrade locomotion energetically economical?

Ursids are the largest mammals to retain a plantigrade posture. This primitive posture has been proposed to result in reduced locomotor speed and economy relative to digitigrade and unguligrade species, particularly at high speeds. Previous energetics research on polar bears ( Ursus maritimus ) found locomotor costs were more than double predictions for similarly sized quadrupedal mammals, which could be a result of their plantigrade posture or due to adaptations to their Arctic marine existence. To evaluate whether polar bears are representative of terrestrial ursids or distinctly uneconomical walkers, this study measured the mass-specific metabolism, overall dynamic body acceleration, and gait kinematics of polar bears and grizzly bears ( Ursus arctos ) trained to rest and walk on a treadmill. At routine walking speeds, we found polar bears and grizzly bears exhibited similar costs of locomotion and gait kinematics, but differing measures of overall dynamic body acceleration. Minimum cost of transport while walking in the two species (2.21 J kg −1 m −1 ) was comparable to predictions for similarly sized quadrupedal mammals, but these costs doubled (4.42 J kg −1 m −1 ) at speeds ≥5.4 km h −1 . Similar to humans, another large plantigrade mammal, bears appear to exhibit a greater economy while moving at slow speeds.

Journal of Experimental Biology↗
USGS2023

Mangrove habitat persistence and carbon vulnerability associated with increased nutrient loading and sea-level rise at Ding Darling National Wildlife Refuge (Sanibel Island, Florida, USA)

J.N. “Ding” Darling National Wildlife Refuge (DDNWR) is located on Sanibel Island along the southwestern coast of Florida, USA. Sanibel Island is heavily developed, but DDNWR provides protection for a large mangrove area that supports biodiversity and recreational opportunity. However, nitrogen (N) and phosphorus (P) eutrophication attributed to agriculture discharge along the Caloosahatchee River has affected the area’s aquatic habitat with algal blooms and may be causing untimely degradation of Sanibel’s mangrove forests. We launched a series of studies to understand how additional nutrient loading to the levels expected in the future might affect DDNWR’s mangrove resource. We experimentally fertilized selected mangrove forest areas with N fertilizer (+N; NH4) and P fertilizer (+P; P 2 O 5 ) for three years, and monitored soil surface elevation change, soil and pneumatophore CO 2 fluxes from respiration, mangrove tree sap flow from two species ( Avicennia germinans , Rhizophora mangle ), and individual tree and stand water use, from which we developed carbon (C) budgets for +N and +P vs. control simulations as applied to DDNWR’s 1112 ha mangrove area. Many of the measured response variables provided hints of subtle changes in response to +P rather than +N, which were compounded when scaled. From this, we found that additional P loading is expected to stimulate CO 2 uptake via net ecosystem exchange of C, likely pressing the system beyond metabolic capacity and leading to a projected 41% increase in lateral C export to the estuary. Additional lateral C export is concomitant to a reduction in vertical soil surface elevation with +P. Furthermore, an inability of DDNWR’s mangroves to bury additional P and a release of P-bound ions to lateral export may exacerbate estuarine eutrophication. We also modelled the effect of sea-level rise influences on DDNWR’s mangroves through 2100 using a soil cohort model (WARMER-Mangroves) and found that the mangroves may be resilient to current rates of sea-level rise into the future but may also be susceptible to moderate accelerations. Greater eutrophication could create additional vulnerabilities to mangrove submergence, especially to basin mangroves where P concentrations are high and already reducing soil surface elevations in some mangroves. Our results suggest that amelioration of current P concentrations and avoidance of additional P loading to Sanibel Island’s mangroves are management options to consider.

Florida↗
USGS2019

Beneath the arctic greening: Will soils lose or gain carbon or perhaps a little of both?

Ecosystem shifts related to climate change are anticipated for the next decades to centuries based on a number of conceptual and experimentally derived models of plant structure and function. Belowground, the potential responses of soil systems are less well known. We used geochemical steady state models, soil density fractionation, and soil radiocarbon data to constrain changes in soil carbon based on measurements from detrital (free light), aggregate-bound (occluded) and complexed or chemically bound (mineral associated) carbon pools and for bulk soil. We explored a space-for-time sequence of soils along a cold-to-warm climatic gradient from Alaskan Black Spruce forest soil with permafrost (Gelisols; 50 cm Mean Annual Temperature −1.5 ºC), Alaskan White Spruce forest soil lacking permafrost (Inceptisols; 50 cm MAT +3 ºC ), and Iowa Grassland soil lacking permafrost (Mollisols; 50 cm MAT +9 ºC) developed on similar geologic substrates (wind-blown loess deposits). These temperature ranges were also representative of temperatures at 50 cm soil depth from model output by the Community Land Model for the years 2014, 2100, and 2300 for Interior Alaska. Fitting an exponential equation to depth trends in soil C down to 2 m depths, we found that depth distributions of organic C were related mainly to depths of rooting and changes in bulk density. Using output from the geochemical steady state model, the direction and magnitude of the C loss or gain upon ecosystem shift was dictated by the C stocks of initial and final ecosystems. Radiocarbon measurements specific to each soil fraction (free light, occluded, and mineral associated) allowed us to constrain the timing of the potential loss or gain of C in each fraction driven by climatic shifts. Thawing from the Gelisol to Inceptisol in loess parent materials from present day to year 2100 resulted in small net gains to soil C, reflecting the net balance between loss of detrital and gain into occluded and mineral associated C. Greater warming and shifts from Inceptisol to Mollisol analogous to predicted warming from circa 2100 to 2300 resulted in net C losses from both occluded and mineral associated C, although small gains to the free light C fraction occurred throughout the depth profile. Gains to occluded and mineral associated C post- thaw likely reflect aggregate formation and physical protection of C as well as formation of organo-mineral compounds that accompany microbial processing. Greater warming and shifts from Inceptisol to Mollisol, which are analogous to predicted warming circa 2100 to 2300, resulted in net C losses from both occluded and mineral associated C resulting from enhanced decomposition, small gains to the free light C fraction occurred throughout the transition to Mollisol reflecting deeper rooting of the tallgrass prairie system.

SOIL↗
USGS1986

The heat capacity of a natural monticellite and phase equilibria in the system CaO-MgO-SiO2-CO2

The heat capacity of a natural monticellite (Ca 1.00 Mg .09 Fe .91 Mn .01 Si 0.99 O 3.99 ) measured between 9.6 and 343 K using intermittent-heating, adiabatic calorimetry yields C p 0 (298) and S 298 0 of 123.64 ± 0.18 and 109.44 ± 0.16 J · mol −1 K −1 respectively. Extrapolation of this entropy value to end-member monticellite results in an S 0 298 = 108.1 ± 0.2 J · mol −1 K −1 . High-temperature heat-capacity data were measured between 340–1000 K with a differential scanning calorimeter. The high-temperature data were combined with the 290–350 K adiabatic values, extrapolated to 1700 K, and integrated to yield the following entropy equation for end-member monticellite (298–1700 K): S T 0 ( J · mol −1 K −1 ) = S 298 0 + 164.79 In T + 15.337 · 10 −3 T + 22.791 · 10 5 T −2 − 968.94. Phase equilibria in the CaO-MgO-SiO 2 system were calculated from 973 to 1673 K and 0 to 12 kbar with these new data combined with existing data for akermanite ( Ak ), diopside ( Di ), forsterite ( Fo ), merwinite ( Me ) and wollastonite ( Wo ). The location of the calculated reactions involving the phases Mo and Fo is affected by their mutual solid solution. A best fit of the thermodynamically generated curves to all experiments is made when the S 0 298 of Me is 250.2 J · mol −1 K −1 less than the measured value of 253.2 J · mol −1 K −1 . A best fit to the reversals for the solid-solid and decarbonation reactions in the CaO-MgO-SiO 2 -CO 2 system was obtained with the ΔG 0 298 ( kJ · mole −1 ) for the phases Ak (−3667), Di (−3025), Fo (−2051), Me (−4317) and Mo (−2133). The two invariant points − Wo and − Fo for the solid-solid reactions are located at 1008 ± 5 K and 6.3 ± 0.1 kbar, and 1361 ± 10 K and 10.2 ± 0.2 kbar respectively. The location of the thermodynamically generated curves is in excellent agreement with most experimental data on decarbonation equilibria involving these phases.

Geochimica et Cosmochimica Acta↗
USGS2009

Derivation of habitat-specific dissolved oxygen criteria for Chesapeake Bay and its tidal tributaries

The Chesapeake 2000 Agreement committed its state and federal signatories to “define the water quality conditions necessary to protect aquatic living resources” in the Chesapeake Bay (USA) and its tidal tributaries. Hypoxia is one of the key water quality issues addressed as a result of the above Agreement. This paper summarizes the protection goals and specific criteria intended to achieve those goals for addressing hypoxia. The criteria take into account the variety of Bay habitats and the tendency towards low dissolved oxygen in some areas of the Bay. Stressful dissolved oxygen conditions were characterized for a diverse array of living resources of the Chesapeake Bay by different aquatic habitats: migratory fish spawning and nursery, shallow-water, open-water, deep-water, and deep-channel. The dissolved oxygen criteria derived for each of these habitats are intended to protect against adverse effects on survival, growth, reproduction and behavior. The criteria accommodate both spatial and temporal aspects of low oxygen events, and have been adopted into the Chesapeake Bay states – Maryland, Virginia, and Delaware – and the District of Columbia's water quality standards regulations. These criteria, now in the form of state regulatory standards, are driving an array of land-based and wastewater pollution reduction actions across the six-watershed.

Maryland, Virginia, Washington, D.C.↗
USGS2025

Relationships between water quality, stream metabolism, and water stargrass growth in the lower Yakima River, 2018 to 2020

Since the early 2000s, water clarity on the lower Yakima River has improved. Changes in best management practices combined with a total maximum daily load for suspended sediment led to these improved conditions. As water clarity improved, so did conditions for aquatic plants; the clearer the water, the better the light penetration, and dramatic increases in plant biomass were observed. In the lower Yakima River, beds of native water stargrass (grass-leaf mud-plantain, Heteranthera dubia) are prolific and can extend bank to bank in some locations. Increased primary productivity can alter local water quality by increasing daily swings of dissolved oxygen (DO) and pH from photosynthesis. In this study, we collected continuous water quality data for 2.5 years at three sites on the lower Yakima River to provide a detailed examination of water quality conditions. These sites were located just below the Prosser Dam (Prosser site, USGS station 12509489), at a long-term USGS streamgage in Benton County (Kiona site, USGS station 12510500), and in West Richland, WA (Van Giesen site; USGS station 12511800). In addition to the continuous water quality data collected, estimates of water stargrass biomass were made through the growing season (June through September) during water years 2018–2020. The main objectives of this study were to document water quality conditions on the lower Yakima River and to analyze if there was a statistical relation between the amount of water stargrass biomass and the observed daily cycles of water quality. During summer, frequent exceedances of established water quality criteria were documented each year during this study. Maximum daily temperatures exceeded 21o C, minimum DO concentrations were below 8 milligrams per liter (mg/L), and maximum pH surpassed 8.5 almost every day from June through August each water year across all three monitoring locations. Water stargrass biomass tended to increase from June through August and September but was ‘reset’ by the following summer likely from high winter and spring streamflows and natural die-off. Results from this study suggest that spring peak discharge and average spring discharge affects late-season water stargrass biomass. In 2018, the highest peak discharge of the study took place, and the August water stargrass biomass values were lower in 2018 than in 2019 and 2020. Seven different water quality metrics were computed for a 7-day and 28-day period prior to each water stargrass sample to examine possible correlations between the plant biomass and water quality. We examined daily maximum temperature, DO minimum, DO range, pH maximum, pH range, mean nitrate, and nitrate range. While there were some statistically significant correlations among the seven water quality metrics and median water stargrass biomass, the correlations were not consistent across all three sites. At the Prosser site, the 7-day average daily maximum pH and average daily pH range showed significant correlations with median water stargrass biomass. At the Kiona site, both the 7-day and 28-day mean nitrate values showed a significant relationship to median water stargrass biomass. At the Van Giesen site, there were no significant correlations between the seven water quality metrics and median water stargrass biomass. However, whole-stream estimates of gross primary productivity at the Kiona site, which incorporate the entire river community, were related to temperature, DO, and pH indicating the whole river community is influencing surface water quality to some extent. Additional data on water stargrass biomass and continuous water quality could help elucidate the complex interactions between growth and water quality. At a minimum, collection of water stargrass biomass data near the end of the growing season (mid to late August) could be added to locations where continuous water quality and streamflow discharge measurements are also being collected. In addition, experimental removal of water stargrass and its effects on local water quality could provide insight into the complex relationships between water stargrass growth and water quality. Finally, further investigations into streamflow and its effects on water stargrass could be improved. Our data showed a qualitative relationship between spring peak discharge, average spring discharge, and August water stargrass biomass, but more data are needed to confirm this. If spring high streamflows are important for late-season biomass, then targeted flow releases from reservoirs in the upper watershed could be used to slow down water stargrass growth during summer months.

EarthArXiv↗
USGS2011

Networks - The assessment of marine reserve networks: Guidelines for ecological evaluation

As marine ecosystems are plagued by an ever-increasing suite of threats including climate change, pollution, habitat degradation, and fisheries impacts (Roessig et al ., 2004; Lotze et al ., 2006; Jackson, 2008), there are now no ocean areas that are exempt from anthropogenic impacts (Halpern et al ., 2008). In order to preserve marine biodiversity, ecosystem function, and the goods and services provided by resistant and/or resilient systems, marine reserves have been increasingly recommended as part of an ecosystem-based approach to management (Browman and Stergiou, 2004; Levin et al ., 2009). Marine reserves are defined as “areas of the ocean completely protected from all extractive and destructive activities” (Lubchenco et al ., 2003) and can be experimental controls for evaluating the impact of these activities on marine ecosystems. Growing scientific information has shown consistent increases in species density, biomass, size, and diversity in response to full protection inside reserves of varying sizes and ages located in diverse regions (Claudet et al ., 2008; Lester et al ., 2009; Molloy et al ., 2009). However, most of these data are from individual marine reserves and therefore have inherently limited transferability to networks of marine reserves, which when properly designed can outperform single marine reserves for a variety of ecological, economic, and social management goals (Roberts et al ., 2003; Almany et al ., 2009; Gaines et al ., 2010). The concept of marine reserve networks grew out of a desire to achieve both conservation and fishery management goals by minimizing the potential negative economic, social, and cultural impacts of a single large reserve while still producing similar or even greater ecological and economic returns (Murray et al ., 1999; Gaines et al ., 2010). In addition, reserves networks can provide insurance by protecting areas across a region and spreading the risk that these sites may be impacted by localized catastrophes such as hurricanes or oil spills (Allison et al ., 2003). The World Conservation Union's Marine Programme defines a network as “a collection of individual marine protected areas (MPAs) or reserves operating co-operatively and synergistically, at various spatial scales and with a range of protection levels that are designed to meet objectives that a single reserve cannot achieve” (IUCN–WCPA, 2008). However, general terms such as “co-operatively” and “synergistically” can have myriad meanings. Without a clear definition of a network, it becomes difficult to identify attainable management goals and design a process for evaluating whether the network achieves those goals. Besides, different management goals may in turn result in the need for different types of networks. The use of MPAs with varying protection levels together with no-take zones in multiple-zoning schemes adds another layer of complexity to network design and evaluation; however, partially protected areas are generally used to manage coastal uses and avoid conflicts (rather than for strict ecological purposes) and are therefore a function of the local social, economic, and cultural context. As we are here interested in the ecological effects of networks, for the purposes of this chapter, we focus on marine reserves because these areas are no-take and therefore offer greater ecological benefits than other types of MPAs that allow some forms of extraction (Lester and Halpern, 2008).

Book chapter↗