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USGS2003

GCIP water and energy budget synthesis (WEBS)

As part of the World Climate Research Program's (WCRPs) Global Energy and Water-Cycle Experiment (GEWEX) Continental-scale International Project (GCIP), a preliminary water and energy budget synthesis (WEBS) was developed for the period 1996-1999 fromthe "best available" observations and models. Besides this summary paper, a companion CD-ROM with more extensive discussion, figures, tables, and raw data is available to the interested researcher from the GEWEX project office, the GAPP project office, or the first author. An updated online version of the CD-ROM is also available at http://ecpc.ucsd.edu/gcip/webs.htm/. Observations cannot adequately characterize or "close" budgets since too many fundamental processes are missing. Models that properly represent the many complicated atmospheric and near-surface interactions are also required. This preliminary synthesis therefore included a representative global general circulation model, regional climate model, and a macroscale hydrologic model as well as a global reanalysis and a regional analysis. By the qualitative agreement among the models and available observations, it did appear that we now qualitatively understand water and energy budgets of the Mississippi River Basin. However, there is still much quantitative uncertainty. In that regard, there did appear to be a clear advantage to using a regional analysis over a global analysis or a regional simulation over a global simulation to describe the Mississippi River Basin water and energy budgets. There also appeared to be some advantage to using a macroscale hydrologic model for at least the surface water budgets. Copyright 2003 by the American Geophysical Union.

Journal of Geophysical Research D: Atmospheres↗

USGS2007

Insights on geochemical cycling of U, Re and Mo from seasonal sampling in Boston Harbor, Massachusetts, USA

This study examined the removal of U, Mo, and Re from seawater by sedimentary processes at a shallow-water site with near-saturation bottom water O 2 levels (240–380 μmol O 2 /L), very high organic matter oxidation rates (annually averaged rate is 880 μmol C/cm 2 /y), and shallow oxygen penetration depths (4 mm or less throughout the year). Under these conditions, U, Mo, and Re were removed rapidly to asymptotic pore water concentrations of 2.2–3.3 nmol/kg (U), 7–13 nmol/kg (Mo), and 11–14 pmol/kg (Re). The depth order in which the three metals were removed, determined by fitting a diffusion-reaction model to measured profiles, was Re < U < Mo. Model fits also suggest that the Mo profiles clearly showed the presence of a near-interface layer in which Mo was added to pore waters by remineralization of a solid phase. The importance of this solid phase source of pore water Mo increased from January to October as the organic matter oxidation rate increased, bottom water O 2 decreased, and the O 2 penetration depth decreased. Experiments with in situ benthic flux chambers generally showed fluxes of U and Mo into the sediments. However, when the overlying water O 2 concentration in the chambers was allowed to drop to very low levels, Mn and Fe were released to the overlying water along with the simultaneous release of Mo and U. These experiments suggest that remineralization of Mn and/or Fe oxides may be a source of Mo and perhaps U to pore waters, and may complicate the accumulation of U and Mo in bioturbated sediments with high organic matter oxidation rates and shallow O 2 penetration depths. Benthic chamber experiments including the nonreactive solute tracer, Br − , indicated that sediment irrigation was very important to solute exchange at the study site. The enhancement of sediment–seawater exchange due to irrigation was determined for the nonreactive tracer (Br − ), TCO 2 , NH 4 + "> NH 4 + , U and Mo. The comparisons between these solutes showed that reactions within and around the burrows were very important for modulating the Mo flux, but less important for U. The effect of these reactions on Mo exchange was highly variable, enhancing Mo (and, to a lesser extent, U) uptake at times of relatively modest irrigation, but inhibiting exchange when irrigation rates were faster. These results reinforce the observation that Mo can be released to and removed from pore waters via sedimentary reactions. The removal rate of U and Mo from seawater by sedimentary reactions was found to agree with the rate of accumulation of authigenic U and Mo in the solid phase. The fluxes of U and Mo determined by in situ benthic flux chamber measurements were the largest that have been measured to date. These results confirm that removal of redox-sensitive metals from continental margin sediments underlying oxic bottom water is important, and suggest that continental margin sediments play a key role in the marine budgets of these metals.

Geochimica et Cosmochimica Acta↗

USGS2010

Simulation of fluid distributions observed at a crude oil spill site incorporating hysteresis, oil entrapment, and spatial variability of hydraulic properties

Subsurface oil, water, and air saturation distributions were determined using 146 samples collected from seven boreholes along a 120-m transect at a crude oil spill site near Bemidji, Minnesota. The field data, collected 10 years after the spill, show a clearly defined oil body that has an oil saturation distribution that appears to be influenced by sediment heterogeneities and water table fluctuations. The center of the oil body has depressed the water-saturated zone boundary and the oil appears to have migrated laterally within the capillary fringe. A multiphase cross-sectional flow model was developed and used to simulate the movement of oil and water at the spill site. Comparisons between observed and simulated oil saturation distributions serve as an indicator of the appropriateness of using such models to predict the actual spread of organic immiscible liquids at spill sites. Sediment hydraulic properties used in the model were estimated from particle size data. The general large-scale features of the observed oil body were reproduced only when hysteresis with oil entrapment and representations of observed spatial variability of hydraulic properties were incorporated into the model. The small-scale details of the observed subsurface oil distribution were not reproduced in the simulations. The discrepancy between observed and simulated oil distributions reflects the considerable uncertainty in model parameter estimates and boundary conditions, three-phase capillary pressure-saturation-relative permeability functions, representations of spatial variability of hydraulic properties, and hydrodynamics of the groundwater flow system at the study site.

Water Resources Research↗

USGS2015

Rethinking the longitudinal stream temperature paradigm: region-wide comparison of thermal infrared imagery reveals unexpected complexity of river temperatures

Prevailing theory suggests that stream temperature warms asymptotically in a downstream direction, beginning at the temperature of the source in the headwaters and leveling off downstream as it converges to match meteorological conditions. However, there have been few empirical examples of longitudinal patterns of temperature in large rivers due to a paucity of data. We constructed longitudinal thermal profiles (temperature versus distance) for 53 rivers in the Pacific Northwest (USA) using an extensive dataset of remotely sensed summertime river temperatures and classified each profile into one of five patterns of downstream warming: asymptotic (increasing then flattening), linear (increasing steadily), uniform (not changing), parabolic (increasing then decreasing), or complex (not fitting other classes). We evaluated (1) how frequently profiles warmed asymptotically downstream as expected, and (2) whether relationships between river temperature and common hydroclimatic variables differed by profile class. We found considerable diversity in profile shape, with 47% of rivers warming asymptotically, and 53% having alternative profile shapes. Water temperature did not warm substantially over the course of the river for coastal parabolic and uniform profiles, and for some linear and complex profiles. Profile classes showed no clear geographical trends. The degree of correlation between river temperature and hydroclimatic variables differed among profile classes, but there was overlap among classes. Water temperature in rivers with asymptotic or parabolic profiles was positively correlated with August air temperature, tributary temperature and velocity, and negatively correlated with elevation, August precipitation, gradient, and distance upstream. Conversely, associations were less apparent in rivers with linear, uniform, or complex profiles. Factors contributing to the unique shape of parabolic profiles differed for coastal and inland rivers, where downstream cooling was influenced locally by climate or cool water inputs, respectively. Potential drivers of shape for complex profiles were specific to each river. These thermal patterns indicate diverse thermal habitats that may promote resilience of aquatic biota to climate change. Without this spatial context, climate change models may incorrectly estimate loss of thermally suitable habitat.

California, Idaho, Oregon, Washington↗

USGS2001

Detection and measurement of land subsidence using Global Positioning System and interferometric synthetic aperture radar, Coachella Valley, California, 1996-98

Land subsidence associated with ground-water-level declines has been recognized as a potential problem in Coachella Valley, California. Since the early 1920s, ground water has been a major source of agricultural, municipal, and domestic supply in the valley, resulting in water-level declines as large as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the lower Coachella Valley began, resulting in a reduction in ground-water pumping and a recovery of water levels from the 1950s through the 1970s. Since the late 1970s, the demand for water in the valley has exceeded the deliveries of imported surface water, again resulting in increased pumping and ground-water-level declines. The magnitude and temporal occurrence of land subsidence in the lower Coachella Valley are not well known; data are sparse and accuracy varies. Also, the area is tectonically active and has subsided during the past several million years, which further complicates interpretations of the data. Land-surface-elevation data have been collected by many agencies using various methods and different geographic scales; because of this, the -150 millimeters (-0.5 foot) of subsidence determined for the southern parts of the valley for 1930-96 may have a possible error of plus or minus (?)90 millimeters (?0.3 foot). The location, extent, and magnitude of vertical land-surface changes from 1996 to 1998 were determined using Global Positioning System (GPS) and interferometric synthetic aperture radar (InSAR) methods. GPS measurements for 14 monuments in the lower Coachella Valley indicate that the vertical land-surface changes from 1996 to 1998 ranged from -13 to -67 millimeters ? 40 millimeters (-0.04 to -0.22 foot ?0.13 foot). Changes at seven of the monuments exceeded the measurement error of ?40 millimeters (?0.13 foot), which indicates that small amounts of land subsidence occurred at these monuments between 1996 and 1998. Some of the water levels measured in wells near several of these monuments during 1996-98 were the lowest water levels in the recorded histories of the wells. The possible relation between the stresses caused by historically low water levels and the measured vertical changes in land surface suggests that the preconsolidation stress of the aquifer system may have been exceeded during this period and that subsidence may be permanent. Comparisons of several paired monuments and wells indicated that the relation between short-term ground-water-level changes and vertical changes in land surface in the lower Coachella Valley is not clearly defined. Results of InSAR measurements made between 1996 and 1998 indicate that vertical changes in land surface, ranging from about -20 to -70 millimeters ? 5-10 millimeters (-0.07 to -0.23 foot ? 0.02-0.03 foot), occurred in three areas of the Coachella Valley--near Palm Desert, Indian Wells, and Lake Cahuilla. The areas of subsidence near Palm Desert and Indian Wells coincide with areas of substantial ground-water production during 1996-98. The Coachella Valley Water District reported that they had no ground-water production wells in the Lake Cahuilla area but that there may be private production wells in the area. Production from these wells or possibly tectonic activity may be contributing to or causing the subsidence. The geodetic network used for the GPS measurements described in this report covers the area from the Salton Sea on the south to just northwest of Indio. The maps processed using InSAR overlap the part of the geodetic network west of Coachella and north of Lake Cahuilla, and include the Palm Desert area. Both methods of measuring vertical land-surface changes, GPS and InSAR, were used to characterize vertical land-surface changes from the Palm Desert area to the Salton Sea. Because InSAR produces more spatially detailed data over large areas, it generally was useful where vertical land-surface changes were previously unrecognized, such as the

California↗

USGS1972

The martian atmosphere: Mariner 9 television experiment progress report

Atmospheric phenomena appearing in the Mariner 9 television pictures are discussed in detail. The surface of the planet was heavily obscured by a global dust storm during the first month in orbit. Brightness data during this period can be fitted by a semi-infinite scattering and absorbing atmosphere model with a single-scattering albedo in the range 0.70–0.85. This low value suggests that the mean radius of the particles responsible for the obscuration was at least 10 μm. By the end of the second month, this dust storm had largely dissipated, leaving a residual optical depth ∼0.1. Much of the region north of 45°N was covered by variable clouds comprising the north polar hood. The cloud structures revealed extensive systems of lee waves generated by west-to-east flow over irregular terrain. Extensive cloud systems in this region resembled baroclinic wave cyclones. Clouds were also observed over several of the large calderas; these clouds are believed to contain water ice. Several localized dust storms were seen after the global dust storm cleared. These dust clouds appeared to be intensely convective. The convective nature of these storms and the stirring of large dust particles to great heights can be explained by vertical velocities generated by the absorption of solar radiation by the dusty atmosphere.

Icarus↗

USGS1999

Ordovician meteoric carbon and oxygen isotopic values: Implications for the latitudinal variations of ancient stable isotopic values

Columnar and clear blocky calcite cement from a Middle Ordovician carbonate succession in east Tennessee is interpreted as meteoric in origin. Columnar and clear blocky calcite from this succession does not show extremely large 13C depletions reported from meteoric phases of younger rocks. Meteoric fluid ??18O values calculated from clear blocky calcite are ??? 2 to 3??? more negative than approximately coeval sea water; a relationship typical of modern, low-latitude, coastal meteoric water. Comparison with meteoric ??18O values from Ordovician units elsewhere suggests that the geographic distribution of these values may be broadly similar to that observed today. Therefore, we tentatively suggest that geographic distribution of meteoric ??18O values during both icehouse and greenhouse eras are similar.

Palaeogeography, Palaeoclimatology, Palaeoecology↗

USGS1973

Species diversity: Patterns in modern and Miocene foraminifera of the eastern margin of North America

Patterns of foraminiferal species diversity were examined along the eastern margin of North America by utilizing the number of species, S, the information function, H(S), and species equitability, E. The 350 modern samples we studied extended from the Arctic to the Gulf of Mexico at depths ranging from a few meters to more than 5,000 m. In addition, 29 samples from Miocene strata of the Atlantic Coastal Plain and continental shelf were studied. Modern species diversity as measured by S and H(S) generally increases as depth increases and latitude decreases. Some notable exceptions occur, however, which are difficult to explain. For example, species diversity in the Arctic depth interval of 0 to 100 m is as high or higher than that found immediately south of Nova Scotia, in the Gulf of Maine, on Browns and Georges Banks, and even off the Gulf of Mexico deltas. At the moderate depth interval of 100 to 1,000 m, however, the entire margin north of Browns and Georges Banks has lower diversities than that to the south. The highest diversity by far in this depth interval occurs in the northeastern Gulf of Mexico. At the depth interval greater than 1,000 m, the more southern areas studied generally have a higher species diversity than the more northern Cape Cod to Maryland area. An exception to this is the northwestern Gulf of Mexico; this area is also an exception in that species diversity is significantly lower in the deeper waters than in the shallower waters in the same area. The measure of species equitability, E, showed no clear pattern with depth or latitude. This may be so because no simple pattern of species proportions exists or because the sampling was inadequate to measure it. Samples from the Miocene strata show a striking resemblance in species diversity to modern samples at similar depths and latitudes. Our observations indicate that species diversity and equitability have not increased during the last 15 × 10 6 yrs. The fossil and modern data indicate that each environment has its own carrying capacity and that this capacity is reached rather quickly. Although time and environmental stability are undoubtedly important in determining species diversity, as presently defined they are inadequate to explain all observed patterns. Long-term observations in various environments will be required to determine the relative importance of variables that affect species diversity.

Geological Society of America Bulletin↗

USGS2012

Water-quality data from Upper Klamath and Agency Lakes, Oregon, 2009-10

The U.S. Geological Survey Upper Klamath Lake water-quality monitoring program collected data from multiparameter continuous water-quality monitors, weekly water-quality samples, and meteorological stations during 2009 and 2010 from May through November each year. The results of these measurements and sample analyses, as well as quality-control data for the water-quality samples, are presented in this report for 14 sites on Upper Klamath Lake and 2 sites on Agency Lake. These 2 years of data demonstrate a contrast in the seasonal bloom of the dominant cyanobacterium, Aphanizomenon flos-aquae , that can be related to differences in the measured water quality and meteorological variables. Some of the significant findings from 2009 and 2010 are listed below. * Both 2009 and 2010 were characterized by two cyanobacteria blooms, but the blooms differed in timing and intensity. The first bloom in 2009 peaked in late June and at higher chlorophyll a concentrations at most sites than the first bloom in 2010, which peaked in mid-July. A major decline in the first 2009 bloom occurred in late July and was followed by a second bloom that peaked at most sites in mid-August and persisted through September. The decline of the weaker first bloom in 2010 occurred in early August and was followed by a more substantial second bloom that peaked between late August and early September at most sites. * Dissolved oxygen minima associated with bloom declines occurred approximately 2 weeks earlier in 2009 (mid-July) than in 2010 (early August). pH maxima associated with rapid bloom growth occurred in late June and again in mid-August in 2009 and in mid-July and late August in 2010. * In both years, the maxima for total phosphorus and total nitrogen concentrations coincided with the chlorophyll a maximum. The maxima for dissolved nutrient concentrations (orthophosphate, ammonia, and nitrite plus nitrate) coincided with the declines of the first blooms. * Total particulate carbon, total particulate nitrogen, and total particulate phosphorus concentrations were measured in 2009 only. The ratios of carbon to phosphorus and nitrogen to phosphorus in particulates were the highest of the entire season during the rapid growth phase of the first bloom and were the lowest of the season during the decline of the first bloom. These ratios increased with the onset of the second bloom in that year, but to a lesser degree. * Meteorological data show that 2009 was warmer (particularly in June and July), less windy, and more humid early in the season than 2010. The difference in water temperatures reflected the difference in air temperatures in that the lakes were warmer in 2009 than in 2010 starting in early May, when the sensors were deployed, through most of June. Water temperature peaked at a higher value in 2009, and there were more clear days in June 2009 than in June 2010.

Oregon↗

USGS1963

Effects of drought along Pacific Coast in California: Chapter G in Drought in the Southwest, 1942-56

The drought 1945-56 in California affected principally the southern part of the State, and was one of a series that has been recorded in the past century. Although the precipitation in any individual year is not predictable, the pattern of alternating wetter and drier periods is consistent enough that there is clearly a- need for storing the surpluses of wetter periods to provide adequate water supplies in dry years. This cyclic storage is a basic element in the California water plan. Wherever the storage increments in wet years provide adequate supplies throughout the periods of precipitation deficiency, the effect of drought upon mankind has been overcome, or at least minimized. However, whenever the deficiency is greater than has been experienced in past droughts, some downward revisions may be necessary in previous estimates of the firm supply available for man's use.

California↗

USGS2010

Mercury in Indiana watersheds: Retrospective for 2001–2006

Information about total mercury and methylmercury concentrations in water samples and mercury concentrations in fish-tissue samples was summarized for 26 watersheds in Indiana that drain most of the land area of the State. Mercury levels were interpreted with information on streamflow, atmospheric mercury deposition, mercury emissions to the atmosphere, mercury in wastewater, and landscape characteristics. Unfiltered total mercury concentrations in 411 water samples from streams in the 26 watersheds had a median of 2.32 nanograms per liter (ng/L) and a maximum of 28.2 ng/L. When these concentrations were compared to Indiana water-quality criteria for mercury, 5.4 percent exceeded the 12-ng/L chronic-aquatic criterion, 59 percent exceeded the 1.8-ng/L Great Lakes human-health criterion, and 72.5 percent exceeded the 1.3-ng/L Great Lakes wildlife criterion. Mercury concentrations in water were related to streamflow, and the highest mercury concentrations were associated with the highest streamflows. On average, 67 percent of total mercury in streams was in a particulate form, and particulate mercury concentrations were significantly lower downstream from dams than at monitoring stations not affected by dams. Methylmercury is the organic fraction of total mercury and is the form of mercury that accumulates and magnifies in food chains. It is made from inorganic mercury by natural processes under specific conditions. Unfiltered methylmercury concentrations in 411 water samples had a median of 0.10 ng/L and a maximum of 0.66 ng/L. Methylmercury was a median 3.7 percent and maximum 64.8 percent of the total mercury in 252 samples for which methylmercury was reported. The percentages of methylmercury in water samples were significantly higher downstream from dams than at other monitoring stations. Nearly all of the total mercury detected in fish tissue was assumed to be methylmercury. Fish-tissue samples from the 26 watersheds had wet-weight mercury concentrations that exceeded the 0.3 milligram per kilogram (mg/kg) U.S. Environmental Protection Agency (USEPA) methylmercury criterion in 12.4 percent of the 1,731 samples. The median wet-weight concentration in the fish-tissue samples was 0.13 mg/kg, and the maximum was 1.07 mg/kg. A coarse-scale analysis of all fish-tissue data in each watershed and a fine-scale analysis of data within 5 kilometers (km) of the downstream end of each watershed showed similar results overall. Mercury concentrations in fish-tissue samples were highest in the White River watershed in southern Indiana and the Fall Creek watershed in central Indiana. In fish-tissue samples within 5 km of the downstream end of a watershed, the USEPA methylmercury criterion was exceeded by 45 percent of mercury concentrations from the White River watershed and 40 percent of the mercury concentration from the Fall Creek watershed. A clear relation between mercury concentrations in fish-tissue samples and methylmercury concentrations in water was not observed in the data from watersheds in Indiana. Average annual atmospheric mercury wet-deposition rates were mapped with data at 156 locations in Indiana and four surrounding states for 2001–2006. These maps revealed an area in southeastern Indiana with high mercury wet-deposition rates—from 15 to 19 micrograms per square meter per year (µg/m 2 /yr). Annual atmospheric mercury dry-deposition rates were estimated with an inferential method by using concentrations of mercury species in air samples at three locations in Indiana. Mercury dry deposition-rates were 5.6 to 13.6 µg/m 2 /yr and were 0.49 to 1.4 times mercury wet-deposition rates. Total mercury concentrations were detected in 96 percent of 402 samples of wastewater effluent from 50 publicly owned treatment works in the watersheds; the median concentration was 3.0 ng/L, and the maximum was 88 ng/L. When these concentrations were compared to Indiana water-quality criteria for mercury, 12 percent exceeded the 12-ng/L chronic-aquatic criterion, 68 percent exceeded the 1.8-ng/L Great Lakes human-health criterion, and 81 percent exceeded the 1.3-ng/L Great Lakes wildlife criterion. Annual stream mercury yields were calculated with a model by using the mercury concentrations in water samples and daily average streamflows for 2002–2006, normalized to the watershed drainage areas. The average annual total mercury stream yields ranged from 0.73 to 45.2 µg/m 2 /yr and were highest in two White River watersheds in central Indiana. Median methylmercury stream yield was 1.9 percent of the median total mercury stream yield. In most watersheds, average annual stream yields of total mercury were a fraction of the combined average annual atmospheric mercury wet-deposition and estimated annual dry-deposition loading rates, indicating that much of the stream mercury was attributable to atmospheric deposition. In two watersheds, average annual stream yields of total mercury were approximately twice the atmospheric mercury loading, indicating that some of the stream mercury apparently was not attributable to atmospheric deposition. Rather, some of the stream mercury yield potentially was contributed by mercury in wastewater discharges. Land-cover type corresponded with the mercury levels in three watersheds: (1) A watershed of the White River in central Indiana with a high percentage of urban land cover had some of the highest total mercury concentrations and stream mercury yields. The urban land cover and numerous permitted wastewater outfalls with mercury in treated effluent potentially contributed mercury to this watershed. (2) A monitoring station on the Maumee River in northeastern Indiana, downstream from a large area of urban land cover, recorded the highest stream mercury concentrations. The urban land cover and mercury detected in treated effluent potentially contributed to the high mercury concentrations at this station. (3) A watershed of the Patoka River in southern Indiana with a high percentage of forest land cover had the highest atmospheric mercury dry-deposition rate. The high dry-deposition rate from the forest land cover potentially contributed to the high mercury concentrations in this watershed. From a retrospective view, mercury concentrations in Indiana watersheds routinely exceeded criteria protective of humans and commonly exceeded criteria protective of wildlife. Atmospheric mercury wet deposition was a predominant factor, but not the single factor, affecting mercury in Indiana watersheds. Mercury in wastewater discharges and atmospheric mercury dry deposition apparently contributed a substantial part of the mercury yield from some watersheds. Dams and impoundments increased the percentage of methylmercury in downstream waters. Long-term monitoring of mercury in wet and dry atmospheric deposition, and in streams and reservoirs, coordinated with monitoring of mercury in fish, will be needed to detect whether mercury levels in Indiana watersheds change in the future.

Indiana↗

USGS2026

Distribution, abundance, breeding activities, and habitat use of the Least Bell's Vireo at Marine Corps Base Camp Pendleton, California—2020–24 summary report

Executive Summary The purpose of this report is to provide the Marine Corps with a summary of abundance, breeding activity, demography, and habitat use of endangered Least Bell’s Vireos ( Vireo bellii pusillus ) at Marine Corps Base Camp Pendleton, California (MCBCP or Base). The report presents results of vireo surveys and monitoring in 2024 and summarizes a subset of data collected from 2020 through 2024. Surveys for the Least Bell's Vireo were completed at MCBCP between April 4 and July 9, 2024. Core survey areas and a subset of non-core areas in drainages containing riparian habitat suitable for vireos were surveyed two to four times. We detected 542 territorial male vireos and 17 transient vireos in core survey areas. An additional 102 territorial male vireos and 2 transients were detected in non-core survey areas. Transient vireos were detected on 5 of the 10 drainages/sites surveyed (core and non-core areas). In core survey areas, 87 percent of vireo territories were on the four most populated drainages, with the Santa Margarita River containing 67 percent of all territories in core areas surveyed on Base. In core areas, 77 percent of male vireos were confirmed as paired; 76 percent of male vireos in non-core areas were confirmed as paired. The number of documented Least Bell’s Vireo territories in core survey areas on MCBCP decreased 3 percent from 2023. In five core survey area drainages, the number of territories increased by at least two, and in two core survey area drainages, the Santa Margarita River and Las Flores Creek, the number of vireo territories decreased by at least nine between 2023 and 2024. The number of vireo territories at Marine Corps Air Station, Camp Pendleton did not change from 2023 to 2024. The proportion of surveys during which Brown-headed Cowbirds ( Molothrus ater ) were detected decreased to 0.03 from a peak of 0.45 in 2022. Cowbirds were detected in April and June in 2024. Most core-area vireos (58 percent, including transients) used mixed willow ( Salix spp.) riparian habitat. An additional 9 percent of birds occupied willow habitat co-dominated by Western sycamores ( Platanus racemosa ). Riparian scrub dominated by mule fat ( Baccharis salicifolia ), sandbar willow ( S. exigua ), or blue elderberry ( Sambucus mexicana ) was used by 33 percent of vireos. Habitat dominated by non-native vegetation was used by 1 percent of vireos. Since 2020, the number of vireos detected in each of the non-core survey groups was greater than expected, based on the change in vireo numbers in core survey areas. Although, the number of vireo territories on Base decreased from 2020–24, from approximately 1,224 to approximately 960, the trend in vireo territory numbers on Base since 2005 has been positive. In 2019, MCBCP began operating an artificial seep along the Santa Margarita River; then, in 2021, two additional artificial seeps became operational. The artificial seeps pumped water to the surface during daylight hours starting in mid-April and ending in August each year and were designed to increase the amount of surface water to enhance Southwestern Willow Flycatcher ( Empidonax traillii extimus ) breeding habitat. Although this enhancement was designed to benefit flycatchers, few flycatchers have inhabited MCBCP, including the seep areas, within the past several years; therefore, vireos were selected as a surrogate species to determine effects of the habitat enhancement. This report presents the fifth year of annual monitoring and analyses summarizing all 5 years of vireo and vegetation response to the artificial seeps. In 2020, we established four study sites along the Santa Margarita River, two surrounding and extending downstream from existing and proposed seep pumps at the Old Treatment Ponds and along Pump Road and two Reference sites in similar habitat downstream from the Seep sites. Seep pumps began operating at the Old Treatment Ponds in 2020 and along Pump Road in 2021. In 2023, seep pumps at the Pump Road Seep site did not function, and we recategorized that study site as Intermediate. We sampled vegetation at Seep, Intermediate, and Reference sites to determine the effects of surface-water enhancement by seep pumps. In 2024, vegetation cover was highest near the ground and decreased with increasing height. Woody vegetation made up most of the cover at all height categories. We determined that Seep and Intermediate sites differed from each other in addition to differing from Reference sites, which likely is, in part, because seep-pump operation at the Intermediate site was inconsistent compared to the Seep site. Soil saturation in 2024 was high at the Intermediate site and was associated with high native herbaceous cover and low non-native herbaceous cover. Sites differed, with the Intermediate site having more upper canopy cover in general, the Seep site having more low woody cover, and the Reference sites having more mid-canopy non-native vegetation cover. Soil saturation significantly increased from 2020 through 2024 at the Seep site and was significantly higher at Seep and Intermediate sites than at their paired Reference sites in all years. Soil saturation likely was increased by the supplemental surface water at the Seep site. However, soil saturation at the Intermediate site was not clearly associated with seep pumps but likely affected by soil saturation at the site before seep-pump installation and flooding from high precipitation. Canopy height increased at the Intermediate site from 2020 through 2024 and increased with increasing soil saturation at the Intermediate and Reference sites. The canopy at the Seep site was shorter than at the Intermediate and Reference sites and decreased from 2020 through 2024 because tall trees were damaged and killed by shothole borer beetles ( Euwallacea spp.). We used Redundancy Analysis to discover associations among vegetation types, plant species, and other environmental variables (soil saturation, site, precipitation, and seep operation, defined as the site and year seep pumps were operating). These associations explained less than 15 percent of the variability in the vegetation, with the remaining 85 percent of variation unexplained. Generally, as soil saturation increased, understory vegetation increased and non-native cover decreased in the mid-and upper canopy. Non-native herbaceous plant species decreased in wetter soil. The Seep site was characterized by more understory and less canopy, contrasting with the Intermediate site, which was characterized by less understory and more higher canopy cover. The addition of surface water via seep pumps or precipitation was associated with more vegetation near the ground. Higher early winter precipitation was associated with taller canopy and more woody vegetation in the upper canopy. We also created a Redundancy Analysis model isolating the components of Southwestern Willow Flycatcher habitat, as identified by Howell and others (2018). In this model, increased soil saturation resulted in increased cover of stinging nettle ( Urtica dioica ) and black willow ( Salix gooddingii ) below 3 meters (m), total cover 3–6 m, and black willow above 6 m. Cover of poison hemlock ( Conium maculatum ) and stinging nettle below 3 m was higher at the Seep site and lower at the Intermediate site. Vireo territory density among the Seep, Intermediate, and Reference sites was similar before the seep pumps were installed. However, vireo territory density at Seep and Intermediate sites combined was significantly higher than at Reference sites after the seep pumps were installed. We banded and resighted color banded vireos as part of a long-term evaluation of vireo survival, site fidelity, between-year movement, and the effect of surface-water enhancement on vireo return rate and between-year movement. We banded 164 Least Bell's Vireo nestlings during the 2024 season. In 2024, we resighted 31 Least Bell's Vireos on Base that had been banded before the 2024 breeding season, and we were able to identify 25 of them. Of the 25 that we could identify, 24 were banded on Base and 1 was originally banded on the San Luis Rey River. Adult birds of known age ranged from 1 to 9 years old. Base-wide survival of vireos was affected by sex, age, and year. Males had significantly higher annual survival than females (60 percent versus 47 percent, respectively). Adults had higher annual survival than first-year vireos (61 percent versus 11 percent, respectively). The return rate of adult vireos to Seep, Intermediate, or Reference sites was not affected by the original banding site (Seep versus Intermediate versus Reference). Most returning adult vireos, predominantly males, showed strong between-year site fidelity. Of the adults present in 2023, 92 percent (all males) returned in 2024 to within 100 m of their previous territory. The average between-year movement for returning adult vireos was 0.4±0.03 kilometers (km). The average movement of first-year vireos detected in 2024 that fledged from a known nest on MCBCP in 2023 was 2.4±3.1 km. We monitored 47 Least Bell's Vireo pairs to evaluate the effects of surface-water enhancement on nest success and breeding productivity. Breeding productivity in 2024 was similar among Seep, Intermediate, and Reference sites (2.8, 3.0, and 3.0 young fledged per pair, respectively), and the percentage of pairs that fledged at least one young was not significantly different among sites (83, 91, and 96 percent, respectively). According to the best model, daily nest survival from 2020–24 was not related to site. Other measures of breeding productivity were also similar among Seep, Intermediate, and Reference site pairs. Between 2020 and 2024, the number of vireo fledglings produced per pair increased with increasing native herbaceous cover under 3 m and decreasing cover of all herbaceous vegetation under 5 m and was not affected by precipitation, site, or seep operation. The number of vireo fledglings produced per egg was lower at the Seep and Intermediate sites than at the Reference sites and increased with decreasing late winter precipitation, cover of poison hemlock, black mustard, non-native vegetation above 2 m, and all vegetation over 2 m. Vireo pairs at Seep and Intermediate sites were less likely to fledge young than vireo pairs at Reference sites. All vireo pairs were more likely to fledge young with less cover of poison hemlock and more cover of poison oak. From 2020 through 2024, vireos placed their nests in 24 plant species. The most used plants in all years were willows, mostly red ( S. laevigata ), or arroyo ( S. lasiolepis ). The fate of a vireo nest (whether it successfully fledged young or not) was not affected by placement in native or non-native vegetation, by site, or by year, but nests were more likely to be successful if they were placed in woody plants than in herbaceous plants. Successful nests were placed higher in the host plant and farther from the outer edge of the nest clump than unsuccessful nests.

California↗

USGS2007

Application of environmental groundwater tracers at the Sulphur Bank Mercury Mine, California, USA

Boron, chloride, sulfate, ??D, ??18O, and 3H concentrations in surface water and groundwater samples from the Sulphur Bank Mercury Mine (SBMM), California, USA were used to examine geochemical processes and provide constraints on evaporation and groundwater flow. SBMM is an abandoned sulfur and mercury mine with an underlying hydrothermal system, adjacent to Clear Lake, California. Results for non-3H tracers (i.e., boron, chloride, sulfate, ??D, and ??18O) identify contributions from six water types at SBMM. Processes including evaporation, mixing, hydrothermal water input and possible isotopic exchange with hydrothermal gases are also discerned. Tritium data indicate that hydrothermal waters and other deep groundwaters are likely pre-bomb (before ???1952) in age while most other waters were recharged after ???1990. A boron-based steady-state reservoir model of the Herman Impoundment pit lake indicates that 71-79% of its input is from meteoric water with the remainder from hydrothermal contributions. Results for groundwater samples from six shallow wells over a 6-month period for ??D and ??18O suggests that water from Herman Impoundment is diluted another 3% to more than 40% by infiltrating meteoric water, as it leaves the site. Results for this investigation show that environmental tracers are an effective tool to understand the SBMM hydrogeologic regime. ?? Springer-Verlag 2007.

Hydrogeology Journal↗

USGS2015

Normalization of stable isotope data for carbonate minerals: implementation of IUPAC guideline

Carbonate minerals provide a rich source of geochemical information because their δ 13 C and δ 18 O values provide information about surface and subsurface Earth processes. However, a significant problem is that the same δ 18 O value is not reported for the identical carbonate sample when analyzed in different isotope laboratories in spite of the fact that the International Union of Pure and Applied Chemistry (IUPAC) has provided reporting guidelines for two decades. This issue arises because (1) the δ 18 O measurements are performed on CO 2 evolved by reaction of carbonates with phosphoric acid, (2) the acid-liberated CO 2 is isotopically fractionated (enriched in 18 O) because it contains only two-thirds of the oxygen from the solid carbonate, (3) this oxygen isotopic fractionation factor is a function of mineralogy, temperature, concentration of the phosphoric acid, and δ 18 O value of water in the phosphoric acid, (4) researchers may use any one of an assortment of oxygen isotopic fractionation factors that have been published for various minerals at various reaction temperatures, and (5) it sometimes is not clear how one should calculate δ 18 O VPDB values on a scale normalized such that the δ 18 O value of SLAP reference water is −55.5 &permil; relative to VSMOW reference water. To enable researchers worldwide to publish the same δ 18 O value (within experimental uncertainty) for the same carbonate sample, we have re-evaluated reported acid fractionation factors for calcite at 25, 50, and 75 °C and propose a revised relation for the temperature dependence of oxygen isotopic acid fractionation factor, α CO 2 ( ACID ) -calcite αCO2(ACID)-calcite , of 1000ln α CO 2 ( ACID ) -calcite=3.48(10 3 /T)-1.47 1000lnαCO2(ACID)-calcite=3.48(103/T)-1.47 Turn MathJax on where T is temperature in kelvin. At 25 °C, α CO 2 ( ACID ) -calcite=1.01025 αCO2(ACID)-calcite=1.01025 , the most commonly accepted value for this quantity. We propose a normalization protocol in which (1) the internationally distributed carbonate isotopic reference materials NBS 18 and NBS 19 are interspersed among carbonate samples analyzed by treatment with phosphoric acid, (2) the δ 18 O values of the calcite reference materials and the carbonate samples are calculated, respectively, by using the α CO 2 ( ACID ) -calcite αCO2(ACID)-calcite relation above and oxygen-isotope acid fractionation factors appropriate for the sample mineralogy and reaction temperature, (3) the δ 18 O values of solid carbonate samples are determined on the VPDB scale ( δ 18 O VPDB ) with IUPAC-recommended scale expansion such that the δ 18 O of SLAP reference water is −55.5 &permil; relative to VSMOW reference water by normalizing δ 18 O values of carbonate samples with 2014-IUPAC-recommended δ 18 O values of NBS 18 and NBS 19, and (4) δ 18 O values on the VPDB scale are converted to δ 18 O values on the VSMOW-SLAP scale by using IUPAC recommendations. To ease calculations in the protocol, a software application titled “Carbon and Oxygen Isotopic Normalization Tool for Carbonates” is available that relies upon IUPAC-recommended δ 13 C and δ 18 O values of carbonate isotopic reference materials ( http://isotopes.usgs.gov/research/topics/carbonatesnormalizationtool.html ).

Geochimica et Cosmochimica Acta↗

USGS1957

Magmatic, connate, and metamorphic waters

Some major types of water of “deep” origin are believed to be recognizable from their chemical and isotopic compositions. Oil-field brines dominated by sodium and calcium chlorides differ markedly from average ocean water. In general, the brines are believed to be connate in origin (“fossil” sea water) with a negligible to high proportion of meteoric water. Many brines, particularly in pre-Tertiary rocks, are much higher in salinity than sea water and are greatly enriched in calcium as well as sodium chloride. Brines near the salinity of sea water are generally higher, relative to sea water, in bicarbonate, iodine, boron, lithium, silica, ammonium, and water-soluble organic compounds, and lower in sulfate, potassium, and magnesium. Many changes take place after sea water is entrapped in newly deposited marine sediments: (1) Iodine, silicon, boron, nitrogen, and other elements have been selectively concentrated in organisms that decompose during and after burial in sediments. Many of the elements may redissolve in the interstitial water. (2) Bacteria are active in the sediments and reduce sulfate to sulfide and produce methane, ammonia, carbon dioxide, and other products. (3) Some elements have been selectively removed from sea water by inorganic processes, such as adsorption on clays and colloidal matter. When this matter is reconstituted by diagenetic and other changes, some components are redissolved. The abundance of lithium and possibly boron and other elements may be controlled to a considerable extent by these inorganic processes. (4) The interstitial water may react chemically with enclosing sediments and produce dolomite, reconstituted clays, and other minerals. The high loss of magnesium relative to calcium in most connate waters is probably caused by such reactions. Volcanic hot-spring waters of different compositions have been discussed in an accompanying paper (White, 1957). The most significant type is believed to be dominated by sodium chloride, and is best explained as originating from dense gases driven at high temperature and pressure from magma and containing much matter of low volatility that is in solution because of the solvent properties of high-density steam. This dense vapor is condensed in and greatly diluted by deeply circulating meteoric water. Most other types of volcanic water are believed to be derived from the sodium-chloride type. Volcanic sodium-chloride waters are similar in many respects to connate waters but are believed to be distinguishable by relatively high lithium, fluorine, silica, boron, sulfur, CO 2 , arsenic, and antimony; by relatively low calcium and magnesium; and by lack of hydrocarbons, water-soluble organic compounds, and perhaps ammonia and nitrate. Relatively high boron and combined CO 2 are alone not reliable indicators of a volcanic origin. During compaction, rocks lose most of their interstitial high-chloride water; much additional water may then be lost during progressive metamorphism, and the content changes from about 5 per cent in shale to perhaps 1 per cent in gneiss. This expelled water is here called metamorphic. Because of pressure and permeability gradients, it must normally escape upward and mix with connate and meteoric water. Even though large quantities must exist, no example of metamorphic water has been positively identified. Some thermal springs in California are high in salinity and relatively low in temperature and apparent associated heat flow. Some are clearly connate in origin. Other springs are characterized by very high combined carbon dioxide and boron, relative to chloride. Their compositions are considerably different from known connate and volcanic waters and are believed to be best explained by a metamorphic origin. Although some major types of deep water seem to be recognizable, there is much danger of oversimplifying the problems. Many waters are no doubt mixtures of different types, and some of high salinity result from dissolution of salts by meteoric water.

GSA Bulletin↗

USGS1981

Natural occurrence and significance of fluids indicating high pressure and temperature

Most natural minerals have formed from a fluid phase such as a silicate melt or a saline aqueous solution. Fluid inclusions are tiny volumes of such fluids that were trapped within the growing crystals. These inclusions can provide valuable but sometimes ambiguous data on the temperature, pressure, and composition of these fluids, many of which are not available from any other source. They also provide “visual autoclaves” in which it is possible to watch, through the microscope, the actual phase changes take place as the inclusions are heated. This paper reviews the methods of study and the results obtained, mainly on inclusions formed from highly concentrated solutions, at temperatures ≥500°C. Many such fluids have formed as a result of immiscibility with silicate melt in igneous or high-temperature metamorphic rocks. These include fluids consisting of CO 2 , H 2 O, or hydrosaline melts that were <50% H 2 O. From the fluid inclusion evidence it is clear that a boiling, very hot, very saline fluid was present during the formation of most of the porphyry copper deposits in the world. Similarly, from the inclusion evidence it is clear that early (common) pegmatites formed from essentially silicate melts and that the late, rare-element-bearing and chamber-type pegmatites formed from a hydrosaline melt or a more dilute water solution. The evidence on whether this change in composition from early to late solutions was generally continuous or involved immiscibility is not as clear.

Physics and Chemistry of the Earth↗

USGS2011

Development of soil properties and nitrogen cycling in created wetlands

Mitigation wetlands are expected to compensate for the loss of structure and function of natural wetlands within 5–10 years of creation; however, the age-based trajectory of development in wetlands is unclear. This study investigates the development of coupled structural (soil properties) and functional (nitrogen cycling) attributes of created non-tidal freshwater wetlands of varying ages and natural reference wetlands to determine if created wetlands attain the water quality ecosystem service of nitrogen (N) cycling over time. Soil condition component and its constituents, gravimetric soil moisture, total organic carbon, and total N, generally increased and bulk density decreased with age of the created wetland. Nitrogen flux rates demonstrated age-related patterns, with younger created wetlands having lower rates of ammonification, nitrification, nitrogen mineralization, and denitrification potential than older created wetlands and natural reference wetlands. Results show a clear age-related trajectory in coupled soil condition and N cycle development, which is essential for water quality improvement. These findings can be used to enhance N processing in created wetlands and inform the regulatory evaluation of mitigation wetlands by identifying structural indicators of N processing performance.

Wetlands↗

USGS2006

Monitoring changes in the Platte River riparian corridor with serial LiDAR surveys

The Platte River in central Nebraska is a wide, sand-bedded river that provides habitat for migratory water birds along the North American flyway. The central Platte River functions as critical habitat for the endangered whooping crane (Grus americana) and also is an important habitat for the endangered least tern (Sterna antillarum) and the threatened piping plover (Charadrius melodus). Upstream water-resource development over the last century has decreased the water and sediment supplied to the central Platte River. This has resulted in vegetation encroachment and narrowing of Platte River channels. The National Academy of Sciences' National Research Council, in a recent review of these critical habitat designations, concluded that the current morphology of Platte River channels is limiting the recovery of the endangered and threatened avian species. Habitat-enhancement efforts along the Platte River currently (2006) are focused on the clearing of vegetation from in-channel and riparian areas, whereas future plans propose the release of water from upstream dams as a means to prevent vegetation from encroaching on the active river channel. For this reason, monitoring the physical response of the river channel to these management treatments is an important component of a proposed habitat recovery program. Understanding the effects of management strategies on Platte River riparian habitat also is a key objective of the U.S. Geological Survey's Platte River Priority Ecosystem Program (http://mcmcweb.er.usgs.gov/platte/). This fact sheet describes applications of LiDAR to monitor changes in the Platte River riparian corridor.

Fact Sheet↗