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Results for “Radiation Measurements”

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

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At least 343 records · Page 19Linked to original sources

USGS1999

Methods for developing time-series climate surfaces to drive topographically distributed energy- and water-balance models

Topographically distributed energy- and water-balance models can accurately simulate both the development and melting of a seasonal snowcover in the mountain basins. To do this they require time-series climate surfaces of air temperature, humidity, wind speed, precipitation, and solar and thermal radiation. If data are available, these parameters can be adequately estimated at time steps of one to three hours. Unfortunately, climate monitoring in mountain basins is very limited, and the full range of elevations and exposures that affect climate conditions, snow deposition, and melt is seldom sampled. Detailed time-series climate surfaces have been successfully developed using limited data and relatively simple methods. We present a synopsis of the tools and methods used to combine limited data with simple corrections for the topographic controls to generate high temporal resolution time-series images of these climate parameters. Methods used include simulations, elevational gradients, and detrended kriging. The generated climate surfaces are evaluated at points and spatially to determine if they are reasonable approximations of actual conditions. Recommendations are made for the addition of critical parameters and measurement sites into routine monitoring systems in mountain basins.

Hydrological Processes↗

USGS1998

Radionuclides in fly ash and bottom ash: Improved characterization based on radiography and low energy gamma-ray spectrometry

Two radiation-based techniques for determining the distribution and relative abundance of radionuclides are described, and applied to a suite of fly ash and bottom ash samples from a Kentucky power plant. The technique of fission-track radiography provides new observations of the variety of uranium hosts and of uranium distribution in individual particles of fly ash, and thus aids prediction of the leachability of uranium during long-term disposal or utilization of fly ash. Uranium is largely dispersed within glassy components of fly ash particles and shows little evidence for obvious surface enrichment that could be attributed to secondary adsorption. The technique of low energy gamma-ray spectrometry provides simultaneous, non-destructive determination of the relative abundance of 238 U, 226 Ra, 228 Ra and 210 Pb in representative 150–250 g samples. The measurements provide a means for screening samples to determine if the combustion process causes significant preferential redistribution of radionuclides that could affect their subsequent mobility. Results indicate that radium isotopes are not significantly (within 10–15%) fractionated from parent 238 U and 232 Th during coal combustion. In contrast, 210 Pb appears to be preferentially enriched in some samples of fly ash, and depleted in bottom ash relative to 238 U and 226 Ra. In this application 210 Pb acts as a tracer for elemental lead, and confirms the expected greater volatility of Pb compared to more refractory elements during coal combustion.

Fuel↗

USGS2012

Carbon dioxide and methane emissions from the Yukon River system

Carbon dioxide (CO 2 ) and methane (CH 4 ) emissions are important, but poorly quantified, components of riverine carbon (C) budgets. This is largely because the data needed for gas flux calculations are sparse and are spatially and temporally variable. Additionally, the importance of C gas emissions relative to lateral C exports is not well known because gaseous and aqueous fluxes are not commonly measured on the same rivers. We couple measurements of aqueous CO 2 and CH 4 partial pressures ( p CO 2 , p CH 4 ) and flux across the water-air interface with gas transfer models to calculate subbasin distributions of gas flux density. We then combine those flux densities with remote and direct observations of stream and river water surface area and ice duration, to calculate C gas emissions from flowing waters throughout the Yukon River basin. CO 2 emissions were 7.68 Tg C yr −1 (95% CI: 5.84 −10.46), averaging 750 g C m −2 yr −1 normalized to water surface area, and 9.0 g C m −2 yr −1 normalized to river basin area. River CH 4 emissions totaled 55 Gg C yr −1 or 0.7% of the total mass of C emitted as CO 2 plus CH 4 and ∼6.4% of their combined radiative forcing. When combined with lateral inorganic plus organic C exports to below head of tide, C gas emissions comprised 50% of total C exported by the Yukon River and its tributaries. River CO 2 and CH 4 derive from multiple sources, including groundwater, surface water runoff, carbonate equilibrium reactions, and benthic and water column microbial processing of organic C. The exact role of each of these processes is not yet quantified in the overall river C budget.

Yukon River Basin↗

USGS1980

Lithologic log of drill cuttings for DOGAMI heat flow hole CR-SB, Mount Hood, Oregon

CR-SB is one of three shallow (-82.0 m) heat flow holes drilled in 1976 at Mount Hood, Oregon by the Oregon Department of Geology and Mineral Industries (DOGAMI). Drill hole CR-SB was located on the southern flank of the mountain near the Snow Bunny ski lodge at an elevation of 1167.7 m (T 3 S, R 8.5 E, Sec. 25 AA) (Fig. 1). Temperatures, measured at 5.0 m intervals, and geothermal gradient data for the drill hole are given in Hull, Blackwell, and Black (1978) and are reproduced in Table 1 and Figures 2 and 3 in this report. Blackwell and Steele (1979) give an average thermal conductivity, based upon 6 samples of drill cuttings, of 4.53 (standard error =0.26) but indicated that the data obtained from the drill hole are unsuitable for heat flow calculations. Splits of the drill cuttings were obtained courtesy of J. F. Riccio (DOGAMI). The drill cuttings were wet sieved through a 200 mesh (0.074 mm) screen and both fractions were air dried and saved. Representative rock types and alteration material were hand-picked from the coarse fraction using a binocular microscope. Slurry slides of finely-ground cuttings were routinely run at 1/2°/min. from 3° to 37° 20 using unfiltered CuK radiation on a Norelco 1/ X-ray diffractometer equipped with a focusing monochrometer.

Oregon↗

USGS2014

Iron oxide minerals in dust of the Red Dawn event in eastern Australia, September 2009

Iron oxide minerals typically compose only a few weight percent of bulk atmospheric dust but are important for potential roles in forcing climate, affecting cloud properties, influencing rates of snow and ice melt, and fertilizing marine phytoplankton. Dust samples collected from locations across eastern Australia (Lake Cowal, Orange, Hornsby, and Sydney) following the spectacular “Red Dawn” dust storm on 23 September 2009 enabled study of the dust iron oxide assemblage using a combination of magnetic measurements, Mössbauer spectroscopy, reflectance spectroscopy, and scanning electron microscopy. Red Dawn was the worst dust storm to have hit the city of Sydney in more than 60 years, and it also deposited dust into the Tasman Sea and onto snow cover in New Zealand. Magnetization measurements from 20 to 400 K reveal that hematite, goethite, and trace amounts of magnetite are present in all samples. Magnetite concentrations (as much as 0.29 wt%) were much higher in eastern, urban sites than in western, agricultural sites in central New South Wales (0.01 wt%), strongly suggesting addition of magnetite from local urban sources. Variable temperature Mössbauer spectroscopy (300 and 4.2 K) indicates that goethite and hematite compose approximately 25–45% of the Fe-bearing phases in samples from the inland sites of Orange and Lake Cowal. Hematite was observed at both temperatures but goethite only at 4.2 K, thereby revealing the presence of nanogoethite (less than about 20 nm). Similarly, hematite particulate matter is very small (some of it d < 100 nm) on the basis of magnetic results and Mössbauer spectra. The degree to which ferric oxide in these samples might absorb solar radiation is estimated by comparing reflectance values with a magnetic parameter (hard isothermal remanent magnetization, HIRM) for ferric oxide abundance. Average visible reflectance and HIRM are correlated as a group ( r 2 = 0.24), indicating that Red Dawn ferric oxides have capacity to absorb solar radiation. Much of this ferric oxide occurs as nanohematite and nanogoethite particles on surfaces of other particulate matter, thereby providing high surface area to enhance absorption of solar radiation. Leaching of the sample from Orange in simulated human-lung fluid revealed low bioaccessibility for most metals.

Aeolian Research↗

USGS2006

Effects of permafrost melting on CO2 and CH4 exchange of a poorly drained black spruce lowland

[1] Permafrost melting is occurring in areas of the boreal forest region where large amounts of carbon (C) are stored in organic soils. We measured soil respiration, net CO 2 flux, and net CH 4 flux during May–September 2003 and March 2004 in a black spruce lowland in interior Alaska to better understand how permafrost thaw in poorly drained landscapes affects land‐atmosphere CO 2 and CH 4 exchange. Sites included peat soils underlain by permafrost at ∼0.4 m depth (permafrost plateau, PP), four thermokarst wetlands (TW) having no permafrost in the upper 2.2 m, and peat soils bordering the thermokarst wetlands having permafrost at ∼0.5 m depth (thermokarst edges, TE). Soil respiration rates were not significantly different among the sites, and 5‐cm soil temperature explained 50–91% of the seasonal variability in soil respiration within the sites. Groundcover vegetation photosynthesis (calculated as net CO 2 minus soil respiration) was significantly different among the sites (TW > TE > PP), which can be partly attributed to the difference in photosynthetically active radiation reaching the ground at each site type. Methane emission rates were 15 to 28 times greater from TW than from TE and PP. We modeled annual soil respiration and groundcover vegetation photosynthesis using soil temperature and radiation data, and CH 4 flux by linear interpolation. We estimated all sites as net C gas sources to the atmosphere (not including tree CO 2 uptake at PP and TE), although the ranges in estimates when accounting for errors were large enough that TE and TW may have been net C sinks.

Journal of Geophysical Research G: Biogeosciences↗

USGS2016

Greenhouse gas emissions from a created brackish marsh in eastern North Carolina

Tidal marsh creation helps remediate global warming because tidal wetlands are especially proficient at sequestering carbon (C) in soils. However, greenhouse gas (GHG) losses can offset the climatic benefits gained from C storage depending on how these tidal marshes are constructed and managed. This study attempts to determine the GHG emissions from a 4–6 year old created brackish marsh, what environmental factors governed these emissions, and how the magnitude of the fluxes relates to other wetland ecosystems. The static flux chamber method was used to measure GHG fluxes across three distinct plant zones segregated by elevation. The major of soil GHG fluxes from the marsh were from CO 2 (−48–192 mg C m -2 h -1 ), although it was near the lower end of values reported from other wetland types having lower salinities, and would mostly be offset by photosynthetic uptake in this created brackish marsh. Methane flux was also low (−0.33–0.86 mg C m -2 h -1 ), likely inhibited by the high soil SO 4 2− and soil redox potentials poised above −150 mV in this in this created brackish marsh environment. Low N 2 O flux (−0.11–0.10 mg N m -2 h -1 ) was due to low soil NO 3 − and soil redox conditions favoring complete denitrification. GHG fluxes from this created brackish marsh were generally lower than those recorded from natural marshes, suggesting that C sequestration may not be offset by the radiative forcing from soil GHG emissions if projects are designed properly.

North Carolina↗

USGS2001

Earthquake stress drop and laboratory-inferred interseismic strength recovery

We determine the scaling relationships between earthquake stress drop and recurrence interval t r that are implied by laboratory-measured fault strength. We assume that repeating earthquakes can be simulated by stick-slip sliding using a spring and slider block model. Simulations with static/kinetic strength, time-dependent strength, and rate- and state-variable-dependent strength indicate that the relationship between loading velocity and recurrence interval can be adequately described by the power law V L ∝ t r n where n≈−1. Deviations from n=−1 arise from second order effects on strength, with n>−1 corresponding to apparent time-dependent strengthening and n<−1 corresponding to weakening. Simulations with rate and state-variable equations show that dynamic shear stress drop Δτ d scales with recurrence as d Δτ d / d ln t r ≤σ e ( b-a ), where σ e is the effective normal stress, μ=τ/σ e , and ( a-b )= d μ ss / d ln V is the steady-state slip rate dependence of strength. In addition, accounting for seismic energy radiation, we suggest that the static shear stress drop Δτ s scales as d Δτ s / d ln t r ≤σ e (1 +ζ)( b-a ), where ζ is the fractional overshoot. The variation of Δτ s with ln t r for earthquake stress drops is somewhat larger than implied by room temperature laboratory values of ζ and b-a . However, the uncertainty associated with the seismic data is large and the discrepancy between the seismic observations and the rate of strengthening predicted by room temperature experiments is less than an order of magnitude.

Journal of Geophysical Research B: Solid Earth↗

USGS2003

Hydrogeology of shallow basin-fill deposits in areas of Salt Lake Valley, Salt Lake County, Utah

A study of recently developed residential/commercial areas of Salt Lake Valley, Utah, was done from 1999 to 2001 in areas in which shallow ground water has the potential to move to a deeper aquifer that is used for public supply. Thirty monitoring wells were drilled and sampled in 1999 as part of the study. The ground water was either under unconfined or confined conditions, depending on depth to water and the presence or absence of fine-grained deposits. The wells were completed in the shallowest water-bearing zone capable of supplying water. Monitoring-well depths range from 23 to 154 feet. Lithologic, geophysical, hydraulic-conductivity, transmissivity, water-level, and water-temperature data were obtained for or collected from the wells. Silt and clay layers noted on lithologic logs correlate with increases in electrical conductivity and natural gamma radiation shown on many of the electromagnetic-induction and natural gamma logs. Relatively large increases in electrical conductivity, determined from the electromagnetic-induction logs, with no major changes in natural gamma radiation are likely caused by increased dissolved-solids content in the ground water. Some intervals with high electrical conductivity correspond to areas in which water was present during drilling. Unconfined conditions were present at 7 of 20 monitoring wells on the west side and at 2 of 10 wells on the east side of Salt Lake Valley. Fine-grained deposits confine the ground water. Anthropogenic compounds were detected in water sampled from most of the wells, indicating a connection with the land surface. Data were collected from 20 of the monitoring wells to estimate the hydraulic conductivity and transmissivity of the shallow ground-water system. Hydraulic-conductivity values of the shallow aquifer ranged from 30 to 540 feet per day. Transmissivity values of the shallow aquifer ranged from 3 to 1,070 feet squared per day. There is a close linear relation between transmissivity determined from slug-test analysis and transmissivity estimated from specific capacity. Water-level fluctuations were measured in the 30 monitoring wells from 1999 to July 2001. Generally, water-level changes measured in wells on the west side of the valley followed a seasonal trend and wells on the east side showed less fluctuation or a gradual decline during the 2-year period. This may indicate that a larger percentage of recharge to the shallow ground-water system on the west side is from somewhat consistent seasonal sources, such as canals and unconsumed irrigation water, as compared to sources on the east side. Water levels measured in monitoring wells completed in the shallow ground-water system near large-capacity public-supply wells varied in response to ground-water withdrawals from the deeper confined aquifer. Water temperature was monitored in 23 wells. Generally, little or no change in water temperature was measured in monitoring wells with a depth to water greater than about 40 feet. The shallower the water level in the well, the greater the water-temperature change measured during the study. Comparison of water levels measured in the monitoring wells and deeper wells in the same area indicate a downward gradient on the east side of the valley. Water levels in the shallow and deeper aquifers in the secondary recharge area on the west side of the valley were similar to those on the east side. Water levels measured in the monitoring wells and nearby wells completed in the deeper aquifer indicate that the vertical gradient can change with time and stresses on the system.

Utah↗

USGS2004

A formulation of directivity for earthquake sources using isochrone theory

A functional form for directivity effects can be derived from isochrone theory, in which the measure of the directivity-induced amplification of an S body wave is c, the isochrone velocity. Ground displacement of the near-, intermediate-, and far-field terms of P and S waves is linear in isochrone velocity for a finite source in a whole space. We have developed an approximation c-tilde-prime of isochrone velocity that can easily be implemented as a predictor of directivity effects in empirical ground motion prediction relations. Typically, for a given fault surface, hypocenter, and site geometry, c-tilde-prime is a simple function of the hypocentral distance, the rupture distance, the crustal shear wave speed in the seismogenic zone, and the rupture velocity. c-tilde-prime typically ranges in the interval 0.44, for rupture away from the station, to about 4, for rupture toward the station. In this version of the theory directivity is independent of period. Additionally, we have created another functional form which is c-tilde-prime modified to include the approximate radiation pattern of a finite fault having a given rake. This functional form can be used to model the spatial variations of fault-parallel and fault-normal horizontal ground motions. The strengths of this formulation are 1) the proposed functional form is based on theory, 2) the predictor is unambiguously defined for all possible site locations and source rakes, and 3) it can easily be implemented for well-studied important previous earthquakes. We compare predictions of our functional form with synthetic ground motions calculated for finite strike-slip and dip-slip faults in the magnitude range 6.5 - 7.5. In general our functional form correlates best with computed fault-normal and fault-parallel motions in the synthetic motions calculated for events with M6.5. Correlation degrades but is still useful for larger events and for the geometric average horizontal motions. We have had limited success applying it to geometrically complicated faults.

Open-File Report↗

USGS1999

XAFS measurements on zinc chloride aqueous solutions from ambient to supercritical conditions using the diamond anvil cell

The structure and bonding properties of metal complexes in subcritical and supercritical fluids are still largely unknown. Conventional high pressure and temperature cell designs impose considerable limitations on the pressure, temperature, and concentration of metal salts required for measurements on solutions under supercritical conditions. In this study, we demonstrate the first application of the diamond anvil cell, specially designed for x-ray absorption studies of first-row transition metal ions in supercritical fluids. Zn K-edge XAFS spectra were measured from aqueous solutions of 1-2 m ZnCl 2 and up to 6 m NaCl, at temperatures ranging from 25-660 °C and pressures up to 800 MPa. Our results indicate that the ZnCl 4 2- complex is predominant in the 1 m ZnCl 2 /6 m NaCl solution, while ZnCl 2 (H 2 O) 2 is similarly predominant in the 2 m ZnCl 2 solution, at all temperatures and pressures. The Zn-Cl bond length of both types of chlorozinc(II) complexes was found to decrease at a rate of about 0.01 Å/100 °C.

Journal of Synchrotron Radiation↗

USGS2016

Geologic map of the Valdez D-1 and D-2 quadrangles (Mount Wrangell Volcano), Alaska

Geologic Note Mount Wrangell (elev. 4,317 m) is the youngest and only active volcano in the Oligocene to Holocene-aged Wrangell volcanic field that extends from beyond the Alaska-Yukon border northwest through the Wrangell Mountains to the Copper River Basin. The volcano is a very large (900 km 3 ) broad shield containing an ice-filled, nonexplosive, collapse caldera measuring 3.2 by 5.6 kilometers. Three known craters, the West, North, and East occur along the north and west margins of the caldera; the caldera is open to the southeast. The volcano is best exposed on its southwest flank (this map area) where a number of deep glaciated canyons cut through hundreds of meters of shield lava flows creating routes for younger, valley-filling lava flows. The shield extends north into the Gulkana A-1 quadrangle, northeast into the Nabesna A-6 quadrangle, and east into the McCarthy quadrangle where it is almost entirely covered by ice. The present extent of the Mount Wrangell shield showing the entire caldera and locations of the three summit craters is depicted in figure 1. Mount Wrangell was built rapidly beginning about 650 ka by the outpourings of hundreds of voluminous lava flows from a vent, or vents, apparently in the present summit area. By 200 ka to 300 ka, activity waned and only an occasional lava flow coursed down the glacially carved valleys radiating from the summit or flowed over the upper summit area above the heads of the glacial valleys. The youngest dated valley-fill lava flow is approximately 25,000 years old; one or two undated flows may be younger. In historical times there have been several reports of lava flows issuing from the summit area. The most reliable and convincing of these were two independent observations from Copper Center, Alaska on September 3, 1899 that described great earth movements (the 1899 Yakutat Bay earthquake) followed by an eruption at Mount Wrangell’s summit, consisting of vigorous ash emission and flowing lava on the volcano’s northwest flank. This eruptive activity apparently continued for several years after the earthquake, as a photo taken around 1901–02 shows a large part of Mount Wrangell’s summit blanketed by ash. During this study, no evidence of young lava flows in the region were found, although it is very possible that a small-volume flow could be entirely hidden by snow and ice in the 100 years since the event. However, abundant juvenile andesitic pumice was found on the upper Chetaslina Glacier, strongly supporting a very young pyroclastic eruption. In addition to the 1899–1902 eruptions there have been accounts of strong ash-producing activity on at least four different occasions: 1912, July 3, 1921, April 6, 1930, and February 20, 1982. Of these, the 1921 activity was the most spectacular, and possibly erupted from the northeast side of the summit caldera. Present activity is limited to fumaroles in North and West Crater at the summit, at the summit ridge near East Crater, and at two localities at an elevation of 3,657 m on the southwest flank. The summit fumaroles frequently give rise to visible steam plumes, and occasionally sporadic explosive phreatic activity in North and West Crater will put a thin dusting of ash on the summit ice. This study was directed toward Mount Wrangell volcano and the older Wrangell volcanic field rocks that underlie the volcano. These older lavas include the Chetaslina lavas (867 ka–1,650 ka) and a basaltic andesite–dacite center (1,590 ka–1,640 ka) whose source areas are not well defined. Older Paleozoic and Mesozoic sedimentary, igneous, and metamorphic rocks of the Wrangellia terrane underlie the entire Wrangell volcanic field.

Alaska↗

USGS2008

Wildfire effects on water temperature and selection of breeding sites by the Boreal Toad (Bufo boreas) in seasonal wetlands

Disturbances can significantly affect the thermal regime and community structure of wetlands. We investigated the effect of a wildfire on water temperature of seasonal, montane wetlands after documenting the colonization of recently burned wetlands by the Boreal Toad (Bufo boreas boreas). We compared the daily mean temperature, daily maximum temperature, and accumulated growing degree days measured on the north shore of three classes of wetlands: unburned wetlands, burned wetlands that were colonized by breeding toads, and burned wetlands that were not colonized. We hypothesized that toads colonized burned wetlands because they were warmer than unburned wetlands and selected specific burned wetlands because they were warmer than neighboring burned sites. There was weak evidence that toads selected burned wetlands with higher temperature maxima; however, the differences were small (???1??C) and were not supported when accounting for geography and wetland features. We also found no evidence that burning the forest around wetlands increased water temperatures two and three years after the fire. Unburned wetlands had higher daily mean and maximum temperatures and accrued more growing degree days than either class of burned wetlands. Temperature differences among groups of wetlands seemed to be driven by subtle differences in geography. We suspect we did not find warmer temperatures in burned wetlands because all of the wetlands we monitored already had open canopies and the fire likely resulted in only small increases in incident radiation. Copyright ?? 2008. Blake R. Hossack. All rights reserved.

Herpetological Conservation and Biology↗

USGS2017

Characterizing the Kathmandu Valley sediment response through strong motion recordings of the 2015 Gorkha earthquake sequence

We analyze strong motion records and high-rate GPS measurements of the M 7.8 Gorkha mainshock, M 7.3 Dolakha, and two moderate aftershock events recorded at four stations on the Kathmandu basin sediments, and one on rock-outcrop. Recordings on soil from all four events show systematic amplification relative to the rock site at multiple frequencies in the 0.1–2.5 Hz frequency range, and de-amplification of higher frequencies ( >2.5–10 Hz). The soil-to-rock amplification ratios for the M 7.8 and M 7.3 events have lower amplitude and frequency peaks relative to the ratios of the two moderate events, effects that could be suggestive of nonlinear site response. Further, comparisons to ground motion prediction equations show that 1) both soil and rock mainshock recordings were severely depleted of high frequencies, and 2) the depletion at high frequencies is not present in the aftershocks. These observations indicate that the high frequency deamplification is additionally related to characteristics of the source that are not captured by simplified ground motion prediction equations, and allude to seismic hazard analysis models being revised – possibly by treating isolated high frequency radiation sources separately from long period components to capture large magnitude near-source events such as the 2015 Gorkha mainshock.

Kathmandu Valley↗

USGS2025

Spatial stream network modeling of water temperature within the White River Basin, Mount Rainier National Park, Washington

Water temperature is a primary control on the occurrence and distribution of fish and other ectothermic aquatic species. In the Pacific Northwest, cold-water species such as Pacific salmon ( Oncorhynchus spp.) and bull trout ( Salvelinus confluentus ) have specific temperature requirements during different life stages that must be met to ensure the viability of their populations. Rivers draining Mount Rainier in western Washington, including the White River along its northern flank, support a number of cold-water fish populations, but the spatial distribution of water temperatures, particularly during late-summer baseflow during August and September, and the climatic, hydrologic, and physical processes regulating it are not well constrained. Spatial stream network (SSN) models, which are generalized linear models that incorporate streamwise spatial autocovariance structures, were fit to mean and 7-day average daily maximum water temperature for August and September for the White River Basin. The SSN models were calibrated using water temperature measurements collected in 2010 through 2020. The extent of the models included the White River and its tributaries upstream from its confluence with Silver Creek in Mount Rainier National Park, Washington. SSN models incorporated covariates hypothesized to represent the climatic, hydrologic, and physical processes that influence water temperature. SSN models were fit to the measured data and compared to generalized linear models that lacked spatial autocovariance structures. Statistically significant covariates within the best-fit models included the proportion of ice cover and forest cover within the basin, mean August air temperature, the proportion of consolidated geologic units, and snow-water equivalent. Statistical models that included spatial autocovariance structures had better predictive performance than those that did not. Additionally, models of mean August and September water temperature had better predictive performance than those of 7-day average daily maximum temperature in August and September. Predictions of the spatial distribution of water temperature were similar between August and September with a general warming in the downstream part of the mainstem White River compared to cooler water temperatures in the high-elevation headwater streams. The proportion of ice cover emerged as an inversely related significant covariate to both mean August and September water temperature because streams that receive glacial meltwater are colder than non-glaciated streams. Water temperatures of the upper White River increased downstream and are attributed to warming of water temperature from accumulated solar radiation and inflow of non-glaciated tributaries. Estimated water temperatures for the upper White River model are 3–4 degrees Celsius (°C) warmer for tributaries, but 1–2 °C cooler for the mainstem compared to the regional-scale model. Differences between the upper White River SSN model and the regional-scale NorWeST model are attributed to the fact that the upper White River SSN included water temperature observations specific to the upper White River, whereas water temperature observations from lower elevation streams and downstream from the Mount Rainer National Park boundary were used in the regional scale model.

Washington↗

USGS2016

Variation of energy and carbon fluxes from a restored temperate freshwater wetland and implications for carbon market verification protocols

Temperate freshwater wetlands are among the most productive terrestrial ecosystems, stimulating interest in using restored wetlands as biological carbon sequestration projects for greenhouse gas reduction programs. In this study, we used the eddy covariance technique to measure surface energy carbon fluxes from a constructed, impounded freshwater wetland during two annual periods that were 8 years apart: 2002–2003 and 2010–2011. During 2010–2011, we measured methane (CH 4 ) fluxes to quantify the annual atmospheric carbon mass balance and its concomitant influence on global warming potential (GWP). Peak growing season fluxes of latent heat and carbon dioxide (CO 2 ) were greater in 2002–2003 compared to 2010–2011. In 2002, the daily net ecosystem exchange reached as low as −10.6 g C m −2  d −1 , which was greater than 3 times the magnitude observed in 2010 (−2.9 g C m −2  d −1 ). CH 4 fluxes during 2010–2011 were positive throughout the year and followed a strong seasonal pattern, ranging from 38.1 mg C m −2  d −1 in the winter to 375.9 mg C m −2  d −1 during the summer. The results of this study suggest that the wetland had reduced gross ecosystem productivity in 2010–2011, likely due to the increase in dead plant biomass (standing litter) that inhibited the generation of new vegetation growth. In 2010–2011, there was a net positive GWP (675.3 g C m −2  yr −1 ), and when these values are evaluated as a sustained flux, the wetland will not reach radiative balance even after 500 years.

California↗

USGS2008

Ground-water quality data in the southeast San Joaquin Valley, 2005–2006— Results from the California GAMA program

Ground-water quality in the approximately 3,800 square-mile Southeast San Joaquin Valley study unit (SESJ) was investigated from October 2005 through February 2006 as part of the Priority Basin Assessment Project of Ground-Water Ambient Monitoring and Assessment (GAMA) Program. The GAMA Statewide Basin Assessment project was developed in response to the Ground-Water Quality Monitoring Act of 2001 and is being conducted by the California State Water Resources Control Board (SWRCB) in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory (LLNL). The SESJ study was designed to provide a spatially unbiased assessment of raw ground-water quality within SESJ, as well as a statistically consistent basis for comparing water quality throughout California. Samples were collected from 99 wells in Fresno, Tulare, and Kings Counties, 83 of which were selected using a spatially distributed, randomized grid-based method to provide statistical representation of the study area (grid wells), and 16 of which were sampled to evaluate changes in water chemistry along ground-water flow paths or across alluvial fans (understanding wells). The ground-water samples were analyzed for a large number of synthetic organic constituents (volatile organic compounds [VOCs], pesticides and pesticide degradates, and pharmaceutical compounds), constituents of special interest (perchlorate, N-nitrosodimethylamine, and 1,2,3-trichloropropane), naturally occurring inorganic constituents (nutrients, major and minor ions, and trace elements), radioactive constituents, and microbial indicators. Naturally occurring isotopes (tritium, and carbon-14, and stable isotopes of hydrogen, oxygen, nitrogen, and carbon), and dissolved noble gases also were measured to help identify the source and age of the sampled ground water. Quality-control samples (blanks, replicates, samples for matrix spikes) were collected at approximately 10 percent of the wells, and the results for these samples were used to evaluate the quality of the data for the ground-water samples. Assessment of the quality-control data resulted in censoring of less than 1 percent of the detections of constituents measured in ground-water samples. This study did not attempt to evaluate the quality of drinking water delivered to consumers; after withdrawal from the ground, water typically is treated, disinfected, and (or) blended with other waters to maintain acceptable drinking-water quality. Regulatory thresholds apply to the treated water that is served to the consumer, not to raw ground water. However, to provide some context for the results, concentrations of constituents measured in the raw ground water were compared with regulatory and other health-based thresholds established by the U.S. Environmental Protection Agency and California Department of Public Health (CDPH) and thresholds established for aesthetic concerns by CDPH. Two VOCs were detected above health-based thresholds: 1,2-dibromo-3-chloropropane (DBCP), and benzene. DBCP was detected above the U.S. Environmental Protections Agency’s maximum contaminant level (MCL-US) in three grid wells and five understanding wells. Benzene was detected above the CDPH’s maximum contaminant level (MCL-CA) in one grid well. All pesticide detections were below health-based thresholds. Perchlorate was detected above its maximum contaminate level for California in one grid well. Nitrate was detected above the MCL-US in six samples from understanding wells, of which one was a public supply well. Two trace elements were detected above MCLs-US: arsenic and uranium. Arsenic was detected above the MCL-US in four grid wells and two understanding wells; uranium was detected above the MCL-US in one grid well and one understanding well. Gross alpha radiation was detected above MCLs-US in five samples; four of them understanding wells, and uranium isotope activity was greater than the MCL-US for one understanding well. Radon-222 was detected above the proposed MCL-US in all wells sampled. Total coliforms were detected in two wells and somatic coliphage was detected in one well.

California↗

USGS1986

Effect of height and orientation (microclimate) on geomorphic degradation rates and processes, late-glacial terrace scarps in central Idaho

Skip Nav Destination RESEARCH ARTICLE | JULY 01, 1986 Effect of height and orientation (microclimate) on geomorphic degradation rates and processes, late-glacial terrace scarps in central Idaho KENNETH L. PIERCE ; STEVEN M. COLMAN Author and Article Information GSA Bulletin (1986) 97 (7): 869–885. https://doi.org/10.1130/0016-7606(1986)97<869:EOHAOM>2.0.CO;2 Article history Standard View 2.0.CO;2" data-doctype="contentPdf" data-article-id="188507" data-mce-href="https://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/97/7/869/3434736/i0016-7606-97-7-869.pdf"> Open the PDF for in another window Cite Share Icon Share Permissions Abstract Terrace scarps can serve as a nearly ideal natural laboratory for the study of the evolution of slopes. This paper examines the effects of scarp size (height) and orientation (microclimate) by keeping constant variables such as age, lithology, and regional climate. If a scarp degrades as a closed system, and downslope movement is directly proportional to surface gradient , the evolution of the scarp is modeled by the diffusion equation. For a group of scarps of same age and known starting angle, the diffusion-equation model predicts the relation between maximum scarp angle (𝛉) and scarp height ( h ). Late Pleistocene terrace scarps now as steep as 33.25°, as well as measured angles of repose for sand and gravel, require a starting angle as steep as 33.5°. For latest Pleistocene Idaho and Utah scarps, as h increases, 𝛉 is gentler (more degraded) than modeled by the diffusion equation with a constant rate coefficient. The degradation-rate coefficient ( c ) increases tenfold with scarp height; it should not change with scarp height if downslope movement is solely determined by surface gradient (to the first power). Soil wash appears to be responsible for this departure from the diffusion-equation model, for transport rate by soil wash is a function of scarp size (height). South-facing scarps are less vegetated and more degraded than north-facing scarps. For scarps 2 m high, the degradation rate ( c *) on S-facing scarps is 2 times that on N-facing scarps; for 10-m scarps, it is 5 times. The observed dependence of the rate coefficient c * on scarp height can be removed by normalizing c * to values for west-facing scarps of the same height. The residual c * values calculated by this method correlate well with differences in incident solar radiation resulting from the different scarp orientations and maximum gradients. This correlation demonstrates the importance of orientation on slope processes and their rates through the differences in freeze-thaw cycles, soil moisture, and vegetative cover. Scarp morphology may be used to estimate age, if one accounts for the effects of climate and for scarp height, orientation, and lithology. For example, using the dated Bonneville shoreline scarps for calibration and comparing only scarps of equal height, we estimate the Drum Mountains fault scarps to be 9,000 yr old. This age is about twice that produced by previous diffusion-equation calculations that have not accounted for the height as we have here, but it is the same as independent geologic estimates of their age.

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