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Searcher Bias and Scavenging Rates in Bird/Wind Energy Studies

Description: Estimates of animal fatalities in wind developments are biased to unknown degrees by inefficiencies of observers and by the removal of carcasses by scavenging animals or other actions before their detection by observers. This report summarizes results of searcher efficiency and scavenging, thus providing a guide for workers designing or interpreting bird/wind energy studies. Searcher efficiency is highly variable, with several studies reporting relatively low rates (i.e., 35%-50%) and several studies reporting relatively high rates (i.e., 75%-85%) of recovery. The few studies that tested vegetation type indicated that efficiency is influenced by the height and type of vegetation present. It is evident that relatively small birds are being missed at high rates, with most studies likely underestimating the fatality of small birds by 50%-75%. Results also indicate that corrections for observer efficiency need to be based on vegetation type, plant phenology (season), and bird (or bat) size . Studies of scavenging rates were also highly variable and were influenced by bird size and season. Results did show a trend toward a substantial (50%-75%) loss of carcasses of small to midsize birds within one to four weeks; even large raptors will disappear after a month or so.
Date: June 1, 2002
Creator: Morrison, M.
Partner: UNT Libraries Government Documents Department

An improved criterion for new particle formation in diverse environments

Description: A dimensionless theory for new particle formation (NPF) was developed, using an aerosol population balance model incorporating recent developments in nucleation rates and measured particle growth rates. Based on this theoretical analysis, it was shown that a dimensionless parameter Lg, characterizing the ratio of the particle scavenging loss rate to the particle growth rate, exclusively determined whether or not NPF would occur on a particular day. This parameter determines the probability that a nucleated particle will grow to a detectable size before being lost by coagulation with the pre-existing aerosol. Cluster-cluster coagulation was shown to contribute negligibly to this survival probability under conditions pertinent to the atmosphere. Data acquired during intensive measurement campaigns in Tecamac (MILAGRO), Atlanta (ANARChE), Boulder, and Hyytiala (QUEST II, QUEST IV, and EUCAARI) were used to test the validity of Lg as an NPF criterion. Measurements included aerosol size distributions down to 3 nm and gas-phase sulfuric acid concentrations. The model was applied to 77 NPF events and 19 non-events (characterized by growth of pre-existing aerosol without NPF) measured in diverse environments with broad ranges in sulfuric acid concentrations, ultrafine number concentrations, aerosol surface areas, and particle growth rates (nearly two orders of magnitude). Across this diverse data set, a nominal value of Lg = 0.7 was found to determine the boundary for the occurrence of NPF, with NPF occurring when Lg < 0.7 and being suppressed when Lg > 0.7. Moreover, nearly 45% of measured Lg values associated with NPF fell in the relatively narrow range of 0.1 < Lg < 0.3.
Date: March 15, 2010
Creator: Kuang, C.; Riipinen, I.; Sihto, S.-L.; Kulmala, M.; McCormick, A. & McMurry, P.
Partner: UNT Libraries Government Documents Department

Spatial variations of particle scavenging rates within the central and northern Adriatic Sea: use of U--Th disequilibria

Description: Dissolved and particlulate Thorium-234 ({sup 234}Th) were measured in near surface waters from the Central and Northern Adriatic Sea in order to gain an insight into the intensity and variability of active scavenging and particle removal processes. Dissolved {sup 234}Th to Uranium-238 ({sup 238}U) activity ratios vary from 0.21 to 0.75 and clearly imply that {sup 234}Th is being actively scavenged from sea water on a timescale of <3 months. The scavenging rate of dissolved {sup 234}Th with respect to scavenging onto particles appears to correlate with primary productivity measurements. Scavenging and rapid removal of particulate {sup 234}Th from the water column is best explained by a mechanism of zooplankton grazing and fecal pellet production. At one sight in the Jabuka Pit, particulate {sup 234}Th residence times below the pycnocline are long (30-40 days) suggesting that particles are being more readily recycled at these depths. By comparison, in a seawater profile collected near the Po outflow region, {sup 234}Th is depleted with respect to {sup 238}U through the entire water column. We conclude from this assessment that particles in waters near the Po River outflow will be more efficiently transported to bottom sediments compared with those in deeper waters over the Jabuka Pit.
Date: April 1, 1998
Creator: Hamilton, T. F.
Partner: UNT Libraries Government Documents Department

Estimation of Particle Flux and Remineralization Rate from Radioactive Disequilibrium

Description: Reactive radionuclides, such as the thorium isotopes, show measurable deficiencies in the oceanic water column because of their removal by chemical scavenging due to the particle flux. Measurement of the deficiency, coupled with measurement of the radionuclide concentration in particles, allows a determination of the effective particle sinking velocity. Results to date suggest that the effective particle sinking velocity is remarkably invariant with depth. This leads to the tentative suggestion that POC concentration profiles may, to a good approximation, be used directly to determine length scales for the remineralization of sinking organic matter. Further measurements are in progress to test this idea and to evaluate its limitations. Knowledge of the remineralization length scale is essential to an evaluation of the efficiency of the biological pump as a means for deep sequestering of carbon in the ocean.
Date: May 24, 2004
Creator: Bacon, Michael P. & Francois, Roger
Partner: UNT Libraries Government Documents Department

Influences of Flow Transients and Porous Medium Heterogeneity on Colloid Associated Contaminant Transport in the Vadose Zone

Description: We are investigating the role of colloids in the movement of radionuclides through water unsaturated porous media. This research is guided by a key objective of the Environmental Management Science Program (EMSP), which is to improve conceptual and predictive models for contaminant movement in complex vadose zone environments. In the report entitled National Roadmap for Vadose Zone Science and Technology [DOE, 2001], increases in the understanding of colloid-contaminant interactions, colloid mobilization, and colloid deposition within unsaturated soils are cited as requisite needs for predicting contaminant fate and distribution in the vadose zone. We seek to address these needs by pursuing three overarching goals: (1) identify the mechanisms that govern colloid mobilization, transport, and deposition within unsaturated porous media; (2) quantify the role of colloids in scavenging and facilitating the transport of radionuclides; and (3) develop and test a mathematical model suitable for simulating the movement of colloid associated radionuclides through variably saturated porous media.
Date: June 1, 2003
Creator: Ryan, Joseph
Partner: UNT Libraries Government Documents Department

Drop Dynamics and Speciation in Isolation of Metals from Liquid Wastes by Reactive Scavenging

Description: Computational and experimental studies of the motion and dynamics of liquid drops in gas flows were conducted with relevance to reactive scavenging of metals from atomized liquid waste. Navier-Stoke's computations of deformable drops revealed a range of conditions from which prolate drops are expected, and showed how frajectiones of deformable drops undergoing deceleration can be computed. Experimental work focused on development of emission fluorescence, and scattering diagnostics. The instrument developed was used to image drop shapes, soot, and nonaxisymmetric departures from steady flow in a 22kw combustor
Date: August 30, 2002
Creator: Pearlstein, Arne J. & Scheeline, Alexander
Partner: UNT Libraries Government Documents Department

PBX 9501 Outgas Analysis by SPME/GC/MS

Description: The authors used equilibrium headspace gas chromatography/mass spectrometry (GC/MS) to monitor volatile and semivolate species that are expected to migrate through PBX 9501 under environmentally relevant conditions. In this work they screened 11 samples taken from deployed parts. Although a number of chemical permeates were identified, the antioxidant signature provided the most information with regard to decomposition aging. Specifically, they were able to monitor butylated hydroxytoluene (BHT) and other antioxidants, which are apparently added to either the Estane adipate or MDI precursor by the manufacturer. They found that in those parts where diphenylamine (DPA) was used as a stabilizer, BHT response was significantly lower than in those formulations stabilized with Irganox 1010 (Irganox). These results imply that DPA is less efficient as a radical scavenger than Irganox. This lower efficiency might be related to the lack of oxygen in the weapon environment, which is initially &lt; 0.1%. With regard to DPA, it has been reported that radical scavenging activity is proportional to the oxygen pressure. At this time they are uncertain whether the low DPA efficiency is mainly attributed to the oxygen level or if there is another rate limiting step that would lead to the preferential consumption of BHT.
Date: December 11, 2000
Creator: Chambers, D.M.
Partner: UNT Libraries Government Documents Department

Influences of Flow Transients and Porous Medium Heterogeneity on Colloid-Associated Contaminant Transport in the Vadose Zone

Description: We are investigating the role of colloids in the movement of radionuclides and metals through water unsaturated porous media. This research is guided by a key objective of the Environmental Management Science Program (EMSP), which is to improve conceptual and predictive models for contaminant movement in complex vadose zone environments. In the report entitled National Roadmap for Vadose Zone Science and Technology [DOE, 2001], increases in the understanding of colloid-contaminant interactions, colloid mobilization, and colloid deposition within unsaturated soils are cited as requisite needs for predicting contaminant fate and distribution in the vadose zone. We seek to address these needs by pursuing three overarching goals: (1) identify the mechanisms that govern colloid mobilization, transport, and deposition within unsaturated porous media; (2) quantify the role of colloids in scavenging and facilitating the transport of contaminants; and (3) develop and test a mathematical model suitable for simulating the movement of colloid-associated radionuclides and metals through variably saturated porous media.
Date: June 1, 2003
Creator: Saiers, James E.
Partner: UNT Libraries Government Documents Department

Influences of Flow Transients and Porous Medium Heterogeneity on Colloid-Associated Contaminant Transport in the Vadose Zone

Description: We are investigating the role of colloids in the movement of radionuclides through water unsaturated porous media. This research is guided by a key objective of the Environmental Management Science Program (EMSP), which is to improve conceptual and predictive models for contaminant movement in complex vadose zone environments. In the report entitled National Roadmap for Vadose Zone Science and Technology [DOE, 2001], increases in the understanding of colloid-contaminant interactions, colloid mobilization, and colloid deposition within unsaturated soils are cited as requisite needs for predicting contaminant fate and distribution in the vadose zone. We seek to address these needs by pursuing three overarching goals: (1) identify the mechanisms that govern colloid mobilization, transport, and deposition within unsaturated porous media; (2) quantify the role of colloids in scavenging and facilitating the transport of radionuclides; and (3) develop and test a mathematical model suitable for simulating the movement of colloid-associated radionuclides through variably saturated porous media.
Date: June 1, 2003
Creator: Saiers, James & Ryan, Joseph
Partner: UNT Libraries Government Documents Department

In-Cylinder Gas Velocity Measurements Comparing Crankcase and Blower Scavenging in a Fired Two-Stroke Cycle Engine

Description: The in-cylinder flow field of a Schnuerle (loop) scavenged two-stroke engine has been examined under conditions simulating both blower and crankcase driven scavenging. Measurements of the radial component of velocity were obtained along the cylinder centerline during fired operation at delivery ratios of 0.4, 0.6, and 0.8. Both mean velocity profiles and root mean square velocity fluctuations near top center show a strong dependence on the scavenging method. Complementary in-cylinder pressure measurements indicate that combustion performance is better under blower driven scavenging for the engine geometry studied.
Date: January 1, 1994
Creator: Miles, P. C.; Green, R. M. & Witze, P. O.
Partner: UNT Libraries Government Documents Department

Hydrogen catalysis and scavenging action of Pd-POSS nanoparticles

Description: Prompted by the need for a self-supported, chemically stable, and functionally flexible catalytic nanoparticle system, we explore a system involving Pd clusters coated with a monolayer of polyhedral oligomeric silsesquioxane (POSS) cages. With an initial theoretical focus on hydrogen catalysis and sequestration in the Pd-POSS system, we report Density Functional Theory (DFT) results on POSS binding energies to the Pd(110) surface, hydrogen storing ability of POSS, and possible pathways of hydrogen radicals from the catalyst surface to unsaturated bonds away from the surface.
Date: February 1, 2007
Creator: Maiti, A; Gee, R H; Maxwell, R & Saab, A
Partner: UNT Libraries Government Documents Department

Biological Applications of a Strongly Luminescent Platinum (II) Complex in Reactive Oxygen Species Scavenging and Hypoxia Imaging in Caenorhabditis elegans

Description: Phosphorescent transition metal complexes make up an important group of compounds that continues to attract intense research owing to their intrinsic bioimaging applications that arise from bright emissions, relatively long excited state lifetimes, and large stokes shifts. Now for biomaging assay a model organism is required which must meet certain criteria for practical applications. The organism needs to be small, with a high turn-over of progeny (high fecundity), a short lifecycle, and low maintenance and assay costs. Our model organism C. elegans met all the criteria. The ideal phosphor has low toxicity in the model organism. In this work the strongly phosphorescent platinum (II) pyrophosphito-complex was tested for biological applications as a potential in vivo hypoxia sensor. The suitability of the phosphor was derived from its water solubility, bright phosphorescence at room temperature, and long excited state lifetime (~ 10 ┬Ás). The applications branched off to include testing of C. elegans survival when treated with the phosphor, which included lifespan and fecundity assays, toxicity assays including the determination of the LC50, and recovery after paraquat poisoning. Quenching experiments were performed using some well knows oxygen derivatives, and the quenching mechanisms were derived from Stern-Volmer plots. Reaction stoichiometries were derived from Job plots, while percent scavenging (or antioxidant) activities were determined graphically. The high photochemical reactivity of the complex was clearly manifested in these reactions.
Date: December 2015
Creator: Kinyanjui, Sophia Nduta
Partner: UNT Libraries

Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

Description: Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.
Date: January 12, 2010
Creator: Hadley, O.L.; Corrigan, C.E.; Kirchstetter, T.W.; Cliff, S.S. & Ramanathan, V.
Partner: UNT Libraries Government Documents Department

Wireless Sensor Network for Electric Transmission Line Monitoring

Description: Generally, federal agencies tasked to oversee power grid reliability are dependent on data from grid infrastructure owners and operators in order to obtain a basic level of situational awareness. Since there are many owners and operators involved in the day-to-day functioning of the power grid, the task of accessing, aggregating and analyzing grid information from these sources is not a trivial one. Seemingly basic tasks such as synchronizing data timestamps between many different data providers and sources can be difficult as evidenced during the post-event analysis of the August 2003 blackout. In this project we investigate the efficacy and cost effectiveness of deploying a network of wireless power line monitoring devices as a method of independently monitoring key parts of the power grid as a complement to the data which is currently available to federal agencies from grid system operators. Such a network is modeled on proprietary power line monitoring technologies and networks invented, developed and deployed by Genscape, a Louisville, Kentucky based real-time energy information provider. Genscape measures transmission line power flow using measurements of electromagnetic fields under overhead high voltage transmission power lines in the United States and Europe. Opportunities for optimization of the commercial power line monitoring technology were investigated in this project to enable lower power consumption, lower cost and improvements to measurement methodologies. These optimizations were performed in order to better enable the use of wireless transmission line monitors in large network deployments (perhaps covering several thousand power lines) for federal situational awareness needs. Power consumption and cost reduction were addressed by developing a power line monitor using a low power, low cost wireless telemetry platform known as the ''Mote''. Motes were first developed as smart sensor nodes in wireless mesh networking applications. On such a platform, it has been demonstrated in this project that ...
Date: June 30, 2009
Creator: Alphenaar, Bruce
Partner: UNT Libraries Government Documents Department

Isolation of Metals from Liquid Wastes: Reactive Scavenging by Sorbents in Turbulent Reactors

Description: The objective of this work is to develop the fundamental knowledge base for the design of a broad class of high temperature reactive capture processes to treat metals-bearing liquid waste in the DOE inventory. The major thrust is devoted to understanding phenomena that govern process performance and are critical to achieving emission specifications.
Date: June 1, 2000
Creator: Wendt, Jost O.L.; Kerstein, Alan R.; Linak, William P.; Peatlstein, Arne J. & Scheeline, Alexander
Partner: UNT Libraries Government Documents Department

Reductive immobilization of U(VI) in Fe(III) oxide-reducing subsurface sediments: Analysis of coupled microbial-geochemical processes in experimental reactive transport systems

Description: Although the fundamental microbiological and geochemical processes underlying the potential use of dissimilatory metal-reducing bacteria (DMRB) to create subsurface redox barriers for immobilization of uranium and other redox-sensitive metal/radionuclide contaminants are well-understood (Lovley et al., 1991; Gorby and Lovley, 1992; Lovley and Phillips, 1992; Lovley, 1995; Fredrickson et al., 2000; Wielinga et al., 2000; Wielinga et al., 2001), several fundamental scientific questions need to be addressed in order to understand and predict how such treatment procedures would function under in situ conditions in the subsurface. These questions revolve around the dynamic interactions between hydrologic flux and the coupled microbial-geochemical processes which are likely to occur within a redox barrier treatment zone. A brief summary of such questions includes the following: (1) What are the kinetic limitations to the efficiency of microbial U(VI) scavenging in subsurface sediments? (2) Is U(VI) sorbed to Fe(III) oxide and other solid-phase surfaces subject to enzymatic reduction? If so, what are the relative kinetics of aqueous vs. sorbed U(VI) reduction? (3) What are the relative kinetics of direct, enzymatic U(VI) reduction vs. abiotic reduction of U(VI) by surface-bound biogenic Fe(II)? (4) Can coupled Fe(III) oxide/U(VI) reduction be sustained long-term in subsurface environments? What are the kinetic relationships between Fe(III) oxide reduction, DMRB growth, and U(VI) reduction in advectively open sedimentary systems? The overall objective of our research is to address the questions listed above through laboratory-based batch and reactive transport experiments with natural Fe(III) oxide-bearing subsurface materials and a representative pure culture DMRB. A unique feature of our research is that we are using levels of total uranium (ca. 10{sup -6} to 10{sup -4} mol per dm{sup 3} bulk volume) and aqueous/solid-phase ratios ({le} ca. 10{sup -3} mol U per kg sediment) which are much closer to those present in contaminated subsurface environments compared to levels ...
Date: July 8, 2004
Creator: Roden, Eric E. & Barnett, Mark O.
Partner: UNT Libraries Government Documents Department