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Response of Freshwater and Saltwater Toxicity Test Species to Calcium and Salinity Concentrations Encountered in Toxicity Tests

Description: The responses of freshwater (Daphnia magna. Pimephales promelas) and saltwater (Mysidopsis bahia. Cyprinodon variegatus) toxicity test species to elevated calcium concentrations and changing salinity conditions were investigated. The use of salinity as a criterion for selection between saltwater and freshwater test species was investigated by conducting both calcium and salinity toxicity tests. Salinity was determined to be an inappropriate criterion under conditions encountered in this study.
Date: 1989
Creator: Price, Edmund E., 1954-
Partner: UNT Libraries

An Analysis of Salinity in Streams of the Green River Basin

Description: Abstract: Dissolved-solids concentrations and loads can be estimated from streamflow records using a regression model derived from chemical analyses of monthly samples. The model takes seasonal effects into account by the inclusion of simple-harmonic time functions. Monthly mean dissolved-solids loads simulated for a 6-year period at U.S. Geological Survey water-quality stations in the Green River Basin of Wyoming agree closely with corresponding loads estimated from daily specific-conductance records. In a demonstration of uses of the model, an average gain of 114,000 tons of dissolved solids per year was estimated for 6-year period in a 70-mile reach of the Green River from Fontemelle Reservoir to the town of Green River, including the lower 30-mile reach of the Big Sandy River.
Date: October 1977
Creator: DeLong, Lewis L.
Partner: UNT Libraries Government Documents Department

Arsenic Water Technology Partnership Final Technical Report

Description: Congress created the Arsenic Water Technology Partnership (AWTP) in 2002 to develop and provide solutions for the cost-effective removal of arsenic from drinking water. The AWTP was funded by four congressional appropriations (FY03-FY06) to evaluate and develop new technologies that could significantly reduce compliance costs associated with the new 0.010 mg/L maximum contaminant level (MCL) for arsenic in drinking water. Initially focused on arsenic research, in FY06 the AWTP was expanded to include desalination research upon recognition that the research challenges were similar. The funding for the research and subsequent transfer of technology was made available by Congress through the Department of Energy (DOE). The AWTP was a collaborative effort between DOE’s Sandia National Laboratories (Sandia), Water Research Foundation (WaterRF, formerly Awwa Research Foundation) and WERC: A Consortium for Environmental Education and Technology Development based at New Mexico State University (WERC). Key features of the AWTP included technology development, technology implementation/testing and technology transfer. Each of the partners evaluated and oversaw development of new arsenic and desalination treatment technologies, and the technology transfer program ensured that successful technologies were transferred to the water supply community. Through the use of an arsenic treatment cost model, training sessions and a web site, information on arsenic removal and desalination technologies was transferred to stakeholders. KEY ACCOMPLISHMENTS The AWTP partnership funded research on, and deployment and testing of, innovative arsenic and desalination removal technologies; education for small and large water system operators; and development of a comprehensive web-based tool for arsenic treatment technology selection using site-specific data. As water becomes scarcer, and potable water supplies become increasingly vulnerable to contamination, the development of affordable water treatment systems is critical. Choosing the best available treatment system can be difficult. The AWTP has developed and evaluated improved arsenic and desalination treatment systems and provided that information ...
Date: December 31, 2010
Creator: Ilges, A., Thompson, R., Campbell, C.
Partner: UNT Libraries Government Documents Department

Low-Salinity Waterflooding to Improve Oil Recovery - Historical Field Evidence

Description: Waterflooding is by far the most widely applied method of improved oil recovery. Crude oil/brine/rock interactions can lead to large variations in the displacement efficiency of wa-terfloods. Laboratory water-flood tests and single-well tracer tests have shown that injection of dilute brine can increase oil recovery, but work designed to test the method on a field scale has not yet been undertaken. Historical waterflood records could unintentionally provide some evidence of improved recovery from waterflooding with lower salinity brine. Nu-merous fields in the Powder River basin of Wyoming have been waterflooded using low salinity brine (about 500 ppm) obtained from the Madison limestone or Fox Hills sandstone. Three Minnelusa formation fields in the basin were identified as potential candidates for waterflood comparisons based on the salinity of the connate and injection water. Historical pro-duction and injection data for these fields were obtained from the public record. Field waterflood data were manipulated to be displayed in the same format as laboratory coreflood re-sults. Recovery from fields using lower salinity injection wa-ter was greater than that using higher salinity injection wa-ter—matching recovery trends for laboratory and single-well tests.
Date: November 1, 2007
Creator: Robertson, Eric P.
Partner: UNT Libraries Government Documents Department

Desalination of brackish ground waters and produced waters using in-situ precipitation.

Description: The need for fresh water has increased exponentially during the last several decades due to the continuous growth of human population and industrial and agricultural activities. Yet existing resources are limited often because of their high salinity. This unfavorable situation requires the development of new, long-term strategies and alternative technologies for desalination of saline waters presently not being used to supply the population growth occurring in arid regions. We have developed a novel environmentally friendly method for desalinating inland brackish waters. This process can be applied to either brackish ground water or produced waters (i.e., coal-bed methane or oil and gas produced waters). Using a set of ion exchange and sorption materials, our process effectively removes anions and cations in separate steps. The ion exchange materials were chosen because of their specific selectivity for ions of interest, and for their ability to work in the temperature and pH regions necessary for cost and energy effectiveness. For anion exchange, we have focused on hydrotalcite (HTC), a layered hydroxide similar to clay in structure. For cation exchange, we have developed an amorphous silica material that has enhanced cation (in particular Na{sup +}) selectivity. In the case of produced waters with high concentrations of Ca{sup 2+}, a lime softening step is included.
Date: August 1, 2004
Creator: Krumhansl, James Lee; Pless, Jason; Nenoff, Tina Maria; Voigt, James A.; Phillips, Mark L. F.; Axness, Marlene et al.
Partner: UNT Libraries Government Documents Department

Baltimore Harbor and Channels Deepening Study: Chesapeake Bay Hydraulic Model Investigation

Description: From abstract: Tests on the Chesapeake Bay hydraulic model were conducted to specifically investigate possible changes in the hydrodynamic characteristics of velocity, salinity, and tidal elevations associated with the proposed channel enlargements.
Date: February 1982
Creator: Granat, Mitchell A. & Gulbrandsen, Leif F.
Partner: UNT Libraries Government Documents Department

Seasonally Resolved Surface Water (delta)14C Variability in the Lombok Strait: A Coralline Perspective

Description: We have explored surface water mixing in the Lombok Strait through a {approx}bimonthly resolved surface water {Delta}{sup 14}C time-series reconstructed from a coral in the Lombok Strait that spans 1937 through 1990. The prebomb surface water {Delta}{sup 14}C average is -60.5{per_thousand} and individual samples range from -72{per_thousand} to 134{per_thousand}. The annual average post-bomb maximum occurs in 1973 and is 122{per_thousand}. The timing of the post-bomb maximum is consistent with a primary subtropical source for the surface waters in the Indonesian Seas. During the post-bomb period the coral records regular seasonal cycles of 5-20{per_thousand}. Seasonal high {Delta}{sup 14}C occur during March-May (warm, low salinity), and low {Delta}{sup 14}C occur in September (cool, higher salinity). The {Delta}{sup 14}C seasonality is coherent and in phase with the seasonal {Delta}{sup 14}C cycle observed in Makassar Strait. We estimate the influence of high {Delta}{sup 14}C Makassar Strait (North Pacific) water flowing through the Lombok Strait using a two endmember mixing model and the seasonal extremes observed at the two sites. The percentage of Makassar Strait water varies between 16 and 70%, and between 1955 and 1990 it averages 40%. During La Nina events there is a higher percentage of Makassar Strait (high {Delta}{sup 14}C) water in the Lombok Strait.
Date: April 23, 2008
Creator: Guilderson, T P; Fallon, S J; Moore, M D; Schrag, D P & Charles, C D
Partner: UNT Libraries Government Documents Department

Heat Extraction from the ANL Research Salt Gradient Solar Pond

Description: This report documents the design considerations and test results of two heat extraction systems for the ANL Research Salt Gradient Solar Pond (RSGSP). Since operation began in November 1980, the RSGSP has been used to study a wide variety of solar pond phenomena, and the behavior of the RSGSP without heat extraction has been well characterized. Heat extraction equipment was installed in the spring of 1984, with heat extraction experiments conducted the following summer and fall and in the fall of 1985. The experiments simulated the use of the solar pond for grain drying. The effects of both heat extraction methods on the stability of the salt gradient are investigated.
Date: February 1986
Creator: Hull, John R.; Scranton, A. B.; Mehta, J. M.; Cho, S. H. & Kasza, Kenneth Edmund
Partner: UNT Libraries Government Documents Department

Multi-rate flowing Wellbore electric conductivity logging method

Description: The flowing wellbore electric conductivity logging method involves the replacement of wellbore water by de-ionized or constant-salinity water, followed by constant pumping with rate Q, during which a series of fluid electric conductivity logs are taken. The logs can be analyzed to identify depth locations of inflow, and evaluate the transmissivity and electric conductivity (salinity) of the fluid at each inflow point. The present paper proposes the use of the method with two or more pumping rates. In particular it is recommended that the method be applied three times with pumping rates Q, Q /2, and 2Q. Then a combined analysis of the multi-rate data allows an efficient means of determining transmissivity and salinity values of all inflow points along a well with a confidence measure, as well as their inherent or far-field pressure heads. The method is illustrated by a practical example.
Date: April 22, 2003
Creator: Tsang, Chin-Fu & Doughty, Christine
Partner: UNT Libraries Government Documents Department

Application of Multi-rate Flowing Fluid Electric ConductivityLogging Method to Well DH-2, Tono Site, Japan

Description: The flowing fluid electric conductivity (FEC) logging method, wellbore fluid is replaced with de-ionized water, following which FEC profiles in the wellbore are measured at a series of times while the well is pumped at a constant rate. Locations were fluid enters the wellbore show peaks in the FEC logs, which may be analyzed to infer inflow strengths and salinities of permeable features intersected by the wellbore. In multi-rate flowing FEC logging, the flowing FEC logging method is repeated using two or more pumping rates, which enables the transmissivities and inherent pressure heads of these features to be estimated as well. We perform multi-rate FEC logging on a deep borehole in fractured granitic rock, using three different pumping rates. Results identify 19 hydraulically conducting fractures and indicate that transmissivity, pressure head, and salinity vary significantly among them. By using three pumping rates rather than the minimum number of two, we obtain an internal consistency check on the analysis that provides a measure of the uncertainty of the results. Good comparisons against static FEC profiles and against independent chemical, geological, and hydrogeological data have further enhanced confidence in the results of the multi-rate flowing FEC logging method.
Date: October 4, 2004
Creator: Doughty, Christine; Takeuchi, Shinji; Amano, Kenji; Shimo, Michito & Tsang, Chin-Fu
Partner: UNT Libraries Government Documents Department

Oil Recovery Increases by Low-Salinity Flooding: Minnelusa and Green River Formations

Description: Waterflooding is by far the most widely used method in the world to increase oil recovery. Historically, little consideration has been given in reservoir engineering practice to the effect of injection brine composition on waterflood displacement efficiency or to the possibility of increased oil recovery through manipulation of the composition of the injected water. However, recent work has shown that oil recovery can be significantly increased by modifying the injection brine chemistry or by injecting diluted or low salinity brine. This paper reports on laboratory work done to increase the understanding of improved oil recovery by waterflooding with low salinity injection water. Porous media used in the studies included outcrop Berea sandstone (Ohio, U.S.A.) and reservoir cores from the Green River formation of the Uinta basin (Utah, U.S.A.). Crude oils used in the experimental protocols were taken from the Minnelusa formation of the Powder River basin (Wyoming, U.S.A.) and from the Green River formation, Monument Butte field in the Uinta basin. Laboratory corefloods using Berea sandstone, Minnelusa crude oil, and simulated Minnelusa formation water found a significant relationship between the temperature at which the oil- and water-saturated cores were aged and the oil recovery resulting from low salinity waterflooding. Lower aging temperatures resulted in very little to no additional oil recovery, while cores aged at higher temperatures resulted in significantly higher recoveries from dilute-water floods. Waterflood studies using reservoir cores and fluids from the Green River formation of the Monument Butte field also showed significantly higher oil recoveries from low salinity waterfloods with cores flooded with fresher water recovering 12.4% more oil on average than those flooded with undiluted formation brine.
Date: September 1, 2010
Creator: Robertson, Eric P.
Partner: UNT Libraries Government Documents Department

Entrainment of Dungeness Crab in the Desdemona Shoals Reach of the Lower Columbia River Navigation Channel

Description: Proposed dredging of the Columbia River has raised concerns about related impacts on Dungeness crab in the Columbia River Estuary (CRE). This study follows two major efforts, sponsored by the Portland District of the U. S. Army Corps of Engineers (USACE) to quantify the number of crabs entrained by a hopper dredge working in the CRE. From June 2002 through September 2002, Pacific Northwest National Laboratory (PNNL) conducted direct measurements of crab entrainment in the CRE from the mouth of the Columbia River (MCR, river mile -3 to +3) upriver as far as Miller Sands (river mile 21 to 24). These studies constituted a major step in quantifying crab entrainment in the CRE, and allowed statistically bounded projections of adult equivalent loss (AEL) for Dungeness crab populations under a range of future construction dredging and maintenance dredging scenarios (Pearson et al. 2002, 2003). In 2004, PNNL performed additional measurements to improve estimates of crab entrainment at Desdemona Shoals and at Flavel Bar, a reach near Astoria that had not been adequately sampled in 2002 (Figure 1). The 2004 data were used to update the crab loss projections for channel construction to 43 ft MLLW. In addition, a correlation between bottom salinity and adult (age 2+ and 3+, >100 mm carapace width) crab entrainment was developed using 2002 data, and elaborated upon with the 2004 data. This crab salinity model was applied to forecasting seasonal (monthly) entrainment rates and AEL using seasonal variations in salinity (Pearson et al. 2005). In the previous studies, entrainment rates in Desdemona Shoals were more variable than in any of the other reaches. Pearson et al. (2005) concluded that ?the dynamics behind the variable entrainment rates at Desdemona Shoals are not fully understood,? as well as finding that juvenile crab entrainment was not significantly correlated with ...
Date: September 30, 2006
Creator: Pearson, Walter H.; Kohn, Nancy P. & Skalski, J. R.
Partner: UNT Libraries Government Documents Department

Bottom-up, decision support system development : a wetlandsalinity management application in California's San Joaquin Valley

Description: Seasonally managed wetlands in the Grasslands Basin ofCalifornia's San Joaquin Valley provide food and shelter for migratorywildfowl during winter months and sport for waterfowl hunters during theannual duck season. Surface water supply to these wetland contain saltwhich, when drained to the San Joaquin River during the annual drawdownperiod, negatively impacts downstream agricultural riparian waterdiverters. Recent environmental regulation, limiting discharges salinityto the San Joaquin River and primarily targeting agricultural non-pointsources, now addresses return flows from seasonally managed wetlands.Real-time water quality management has been advocated as a means ofmatching wetland return flows to the assimilative capacity of the SanJoaquin River. Past attempts to build environmental monitoring anddecision support systems to implement this concept have failed forreasons that are discussed in this paper. These reasons are discussed inthe context of more general challenges facing the successfulimplementation of environmental monitoring, modelling and decisionsupport systems. The paper then provides details of a current researchand development project which will ultimately provide wetland managerswith the means of matching salt exports with the available assimilativecapacity of the San Joaquin River, when fully implemented. Manipulationof the traditional wetland drawdown comes at a potential cost to thesustainability of optimal wetland moist soil plant habitat in thesewetlands - hence the project provides appropriate data and a feedback andresponse mechanism for wetland managers to balance improvements to SanJoaquin River quality with internally-generated information on the healthof the wetland resource. The author concludes the paper by arguing thatthe architecture of the current project decision support system, whencoupled with recent advances in environmental data acquisition, dataprocessing and information dissemination technology, holds significantpromise to address some of the problems described earlier in the paperthat have limited past efforts to improve Basin water qualitymanagement.
Date: May 10, 2006
Creator: Quinn, Nigel W.T.
Partner: UNT Libraries Government Documents Department

The San Joaquin Valley Westside Perspective

Description: Salt management has been a challenge to westside farmerssince the rapid expansion of irrigated agriculture in the 1900 s. Thesoils in this area are naturally salt-affected having formed from marinesedimentary rocks rich in sea salts rendering the shallow groundwater,and drainage return flows discharging into the lower reaches of the SanJoaquin River, saline. Salinity problems are affected by the importedwater supply from Delta where the Sacramento and San Joaquin Riverscombine. Water quality objectives on salinity and boron have been inplace for decades to protect beneficial uses of the river. However it wasthe selenium-induced avian toxicity that occurred in the evaporationponds of Kesterson Reservoir (the terminal reservoir of a planned but notcompleted San Joaquin Basin Master Drain) that changed public attitudesabout agricultural drainage and initiated a steady stream ofenvironmental legislation directed at reducing non-point source pollutionof the River. Annual and monthly selenium load restrictions and salinityand boron Total Maximum Daily Loads (TMDLs) are the most recent of thesepolicy initiatives. Failure by both State and Federal water agencies toconstruct a Master Drain facility serving mostly west-side irrigatedagriculture has constrained these agencies to consider only In-Valleysolutions to ongoing drainage problems. For the Westlands subarea, whichhas no surface irrigation drainage outlet to the San Joaquin River,innovative drainage reuse systems such as the Integrated Farm DrainageManagement (IFDM) offer short- to medium-term solutions while morepermanent remedies to salt disposal are being investigated. Real-timesalinity management, which requires improved coordination of east-sidereservoir releases and west-side drainage, offers some relief toGrasslands Basin farmers and wetland managers - allowing greater salinityloading to the River than under a strict TMDL. However, currentregulation drives a policy that results in a moratorium on all drainagereturn flows.
Date: March 27, 2006
Creator: Quinn, Nigel W.T.; Linneman, J. Christopher & Tanji, Kenneth K.
Partner: UNT Libraries Government Documents Department

Predictability and Diagnosis of Low Frequency Climate Processes in the Pacific, Final Technical Report

Description: The report summarized recent findings with respect to Predictability and Diagnosis of Low Frequency Climate Processes in the Pacific, with focus on the dynamics of the Pacific Decadal Oscillation, oceanic adjustments and the coupled feedback in the western boundary current of the North and South Pacific, decadal dynamics of oceanic salinity, and tropical processes with emphasis on the Indonesian Throughflow.
Date: June 17, 2009
Creator: Schneider, Niklas
Partner: UNT Libraries Government Documents Department

Genetic Adaptation to Salt Stress in Experimental Evolution of Desulfovibrio vulgaris Hildenborough

Description: High salinity is one of the most common environmental stressors. In order to understand how environmental organisms adapt to salty environment, an experiment evolution with sulfate reducing bacteria Desulfovibrio vugaris Hildenborough was conducted. Control lines and salt-stressed lines (6 lines each) grown in minimal medium LS4D or LS4D + 100 mM NaCl were transferred for 1200 generations. The salt tolerance was tested with LS4D supplemented with 250 mM NaCl. Statistical analysis of the growth data suggested that all lines adapted to their evolutionary environment. In addition, the control lines performed better than the ancestor with faster growth rate, higher biomass yield and shorter lag phase under salty environment they did not evolve in. However, the salt-adapted lines performed better than the control lines on measures of growth rate and yield under salty environment, suggesting that the salt?evolved lines acquired mutations specific to having extra salt in LS4D. Growth data and gene transcription data suggested that populations tended to improve till 1000 generations and active mutations tended to be fixed at the stage of 1000 generations. Point mutations and insertion/deletions were identified in isolated colonies from salt-adapted and control lines via whole genome sequencing. Glu, Gln and Ala appears to be the major osmoprotectant in evolved salt-stressed line. Ongoing studies are now characterizing the contribution of specific mutations identified in the salt-evolved D. vulgaris.
Date: May 17, 2010
Creator: Zhou, Aifen; Hillesland, Kristina; He, Zhili; Joachimiak, Marcin; Zane, Grant; Dehal, Paramvir et al.
Partner: UNT Libraries Government Documents Department

New results on the resistivity structure of Merapi Volcano(Indonesia), derived from 3D restricted inversion of long-offsettransient electromagnetic data

Description: Three long-offset transient electromagnetic (LOTEM) surveyswerecarried out at the active volcano Merapi in Central Java (Indonesia)during the years 1998, 2000, and 2001. The measurements focused on thegeneral resistivity structure of the volcanic edifice at depths of 0.5-2km and the further investigation of a southside anomaly. The measurementswere insufficient for a full 3D inversion scheme, which could enable theimaging of finely discretized resistivity distributions. Therefore, astable, damped least-squares joint-inversion approach is used to optimize3D models with a limited number of parameters. The mode ls feature therealistic simulation of topography, a layered background structure, andadditional coarse 3D blocks representing conductivity anomalies.Twenty-eight LOTEM transients, comprising both horizontal and verticalcomponents of the magnetic induction time derivative, were analyzed. Inview of the few unknowns, we were able to achieve reasonable data fits.The inversion results indicate an upwelling conductor below the summit,suggesting hydrothermal activity in the central volcanic complex. Ashallow conductor due to a magma-filled chamber, at depths down to 1 kmbelow the summit, suggested by earlier seismic studies, is not indicatedby the inversion results. In conjunction with an anomalous-density model,derived from arecent gravity study, our inversion results provideinformation about the southern geological structure resulting from amajor sector collapse during the Middle Merapi period. The density modelallows to assess a porosity range andthus an estimated vertical salinityprofile to explain the high conductivities on a larger scale, extendingbeyond the foothills of Merapi.
Date: June 14, 2006
Creator: Commer, Michael; Helwig, Stefan, L.; Hordt, Andreas; Scholl,Carsten & Tezkan, Bulent
Partner: UNT Libraries Government Documents Department

ECO2N - A New TOUGH2 Fluid Property Module for Studies of CO2Storage in Saline Aquifers

Description: ECO2N is a fluid property module for the TOUGH2 simulator (Version 2.0) that was designed for applications to geologic storage of CO{sub 2} in saline aquifers. It includes a comprehensive description of the thermodynamics and thermophysical properties of H{sub 2}O-NaCl-CO{sub 2} mixtures, that reproduces fluid properties largely within experimental error for the temperature, pressure and salinity conditions of interest(10 C {le} T {le} 110 C; P {le} 600 bar; salinity up to full halite saturation). Flow processes can be modeled isothermally or non-isothermally, and phase conditions represented may include a single (aqueous or CO{sub 2}-rich) phase, as well as two-phase mixtures. Fluid phases may appear or disappear in the course of a simulation, and solid salt may precipitate or dissolve. ECO2N can model super- as well as sub-critical conditions, but it does not make a distinction between liquid and gaseous CO{sub 2}. This paper highlights significant features of ECO2N, and presents illustrative applications.
Date: April 17, 2006
Creator: Pruess, Karsten & Spycher, Nicholas
Partner: UNT Libraries Government Documents Department

Investigation of Phase and Emulsion Behavior, Surfactant Retention and Condensate Recovery for Condensate/Water/Ethanol Mixtures

Description: This semi-annual technical progress report describes work performed at Morehouse College under DOE Grant No. DE-FG26-02NT15447 during the period October 01, 2002 to April 01, 2003 which covers the first six months of the project. Presently work is in progress to characterize phase and emulsion behavior for condensate/water/ethanol system. Temperature and salinity scans are planned to identify the optimal salinity and temperature, and the temperature and salinity intervals in which all three phases coexist for this system. Test matrix to perform salinity and temperature scans has been established. Supply requests to obtain hydrocarbons, surfactant, etc., were processed and supplies obtained. Current literature in the subject area, and modeling efforts that were established in our previous studies to predict electrical conductivities and inversion phenomena were reviewed. Based on the review a computer model to predict electrical conductivities of the ethylbenzene (that has the equivalent carbon number of the condensate)/water/ethanol system is being developed. These activities resulted in one published conference abstract during this reporting period.
Date: March 31, 2003
Creator: Sampath, Ramanathan
Partner: UNT Libraries Government Documents Department

Identification of saline soils with multi-year remote sensing of crop yields

Description: Soil salinity is an important constraint to agricultural sustainability, but accurate information on its variation across agricultural regions or its impact on regional crop productivity remains sparse. We evaluated the relationships between remotely sensed wheat yields and salinity in an irrigation district in the Colorado River Delta Region. The goals of this study were to (1) document the relative importance of salinity as a constraint to regional wheat production and (2) develop techniques to accurately identify saline fields. Estimates of wheat yield from six years of Landsat data agreed well with ground-based records on individual fields (R{sup 2} = 0.65). Salinity measurements on 122 randomly selected fields revealed that average 0-60 cm salinity levels > 4 dS m{sup -1} reduced wheat yields, but the relative scarcity of such fields resulted in less than 1% regional yield loss attributable to salinity. Moreover, low yield was not a reliable indicator of high salinity, because many other factors contributed to yield variability in individual years. However, temporal analysis of yield images showed a significant fraction of fields exhibited consistently low yields over the six year period. A subsequent survey of 60 additional fields, half of which were consistently low yielding, revealed that this targeted subset had significantly higher salinity at 30-60 cm depth than the control group (p = 0.02). These results suggest that high subsurface salinity is associated with consistently low yields in this region, and that multi-year yield maps derived from remote sensing therefore provide an opportunity to map salinity across agricultural regions.
Date: October 17, 2006
Creator: Lobell, D; Ortiz-Monasterio, I; Gurrola, F C & Valenzuela, L
Partner: UNT Libraries Government Documents Department

Dungeness Crab Dredging Entrainment Studies in the Lower Columbia River, 2002 – 2004: Loss Projections, Salinity Model, and Scenario Analysis

Description: Dungeness crab studies conducted in 2002 for the Portland District of the U.S. Army Corps of Engineers (Corps) constituted a major step forward in quantifying crab entrainment through statistical projections of adult equivalent loss (AEL) and loss to the fishery (LF) from proposed construction and maintenance dredging in the Columbia River navigation channel (Pearson et al. 2002, 2003). These studies also examined the influence of bottom salinity on crab abundance and entrainment rates. Additional sampling was conducted in 2004 to tighten loss projections, further develop the crab salinity model, and apply the model to assess correlations of entrainment rates and projected losses with seasonal salinity changes.
Date: January 1, 2005
Creator: Pearson, Walter H.; Williams, Greg D. & Skalski, John R.
Partner: UNT Libraries Government Documents Department


Description: Weathering characteristics of minesoils and rooting patterns of key shrub and grass species were evaluated at sites reclaimed for 6 to 14 years from three surface coal mine operations in northwestern New Mexico and northeastern Arizona. Non-weathered minesoils were grouped into 11 classifications based on electrical conductivity (EC) and sodium adsorption ratio (SAR). Comparisons of saturated paste extracts, from non-weathered and weathered minesoils show significant (p < 0.05) reductions in SAR levels and increased EC. Weathering increased the apparent stability of saline and sodic minesoils thereby reducing concerns of aggregate slaking and clay particle dispersion. Root density of four-wing saltbush (Atriplex canascens), alkali sacaton (Sporobolus airoides), and Russian wildrye (Psathyrostachys junceus) were nominally affected by increasing EC and SAR levels in minesoil. Results suggest that saline and sodic minesoils can be successfully reclaimed when covered with topsoil and seeded with salt tolerant plant species.
Date: May 1, 2006
Creator: Musslewhite, Brent & Jin, Song
Partner: UNT Libraries Government Documents Department

Secular Trends and Climate Drift in Coupled Ocean-Atmosphere General Circulation Models

Description: Coupled ocean-atmosphere general circulation models (coupled GCMs) with interactive sea ice are the primary tool for investigating possible future global warming and numerous other issues in climate science. A long-standing problem with such models is that when different components of the physical climate system are linked together, the simulated climate can drift away from observations unless constrained by ad hoc adjustments to interface fluxes. However, eleven modern coupled GCMs--including three that do not employ flux adjustments--behave much better in this respect than the older generation of models. Surface temperature trends in control run simulations (with external climate forcing such as solar brightness and atmospheric carbon dioxide held constant) are small compared with observed trends, which include 20th century climate change due to both anthropogenic and natural factors. Sea ice changes in the models are dominated by interannual variations. Deep ocean temperature and salinity trends are small enough for model control runs to extend over 1000 simulated years or more, but trends in some regions, most notably the Arctic, are inconsistent among the models and may be problematic.
Date: November 23, 2004
Creator: Covey, C C; Gleckler, P J; Phillips, T J & Bader, D C
Partner: UNT Libraries Government Documents Department