Improved arterial blood oxygenation following intravenous infusion of cold supersaturated dissolved oxygen solution.

PubMed

Grady, Daniel J; Gentile, Michael A; Riggs, John H; Cheifetz, Ira M

2014-01-01

One of the primary goals of critical care medicine is to support adequate gas exchange without iatrogenic sequelae. An emerging method of delivering supplemental oxygen is intravenously rather than via the traditional inhalation route. The objective of this study was to evaluate the gas-exchange effects of infusing cold intravenous (IV) fluids containing very high partial pressures of dissolved oxygen (>760 mm Hg) in a porcine model. Juvenile swines were anesthetized and mechanically ventilated. Each animal received an infusion of cold (13 °C) Ringer's lactate solution (30 mL/kg/hour), which had been supersaturated with dissolved oxygen gas (39.7 mg/L dissolved oxygen, 992 mm Hg, 30.5 mL/L). Arterial blood gases and physiologic measurements were repeated at 15-minute intervals during a 60-minute IV infusion of the supersaturated dissolved oxygen solution. Each animal served as its own control. Five swines (12.9 ± 0.9 kg) were studied. Following the 60-minute infusion, there were significant increases in PaO2 and SaO2 (P < 0.05) and a significant decrease in PaCO2 (P < 0.05), with a corresponding normalization in arterial blood pH. Additionally, there was a significant decrease in core body temperature (P < 0.05) when compared to the baseline preinfusion state. A cold, supersaturated dissolved oxygen solution may be intravenously administered to improve arterial blood oxygenation and ventilation parameters and induce a mild therapeutic hypothermia in a porcine model.

Dissolution flowsheet for high flux isotope reactor fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foster, T.

2016-09-27

As part of the Spent Nuclear Fuel (SNF) processing campaign, H-Canyon is planning to begin dissolving High Flux Isotope Reactor (HFIR) fuel in late FY17 or early FY18. Each HFIR fuel core contains inner and outer fuel elements which were fabricated from uranium oxide (U 3O 8) dispersed in a continuous Al phase using traditional powder metallurgy techniques. Fuels fabricated in this manner, like other SNF’s processed in H-Canyon, dissolve by the same general mechanisms with similar gas generation rates and the production of H 2. The HFIR fuel cores will be dissolved and the recovered U will be down-blendedmore » into low-enriched U. HFIR fuel was previously processed in H-Canyon using a unique insert in both the 6.1D and 6.4D dissolvers. Multiple cores will be charged to the same dissolver solution maximizing the concentration of dissolved Al. The objective of this study was to identify flowsheet conditions through literature review and laboratory experimentation to safely and efficiently dissolve the HFIR fuel in H-Canyon. Laboratory-scale experiments were performed to evaluate the dissolution of HFIR fuel using both Al 1100 and Al 6061 T6 alloy coupons. The Al 1100 alloy was considered a representative surrogate which provided an upper bound on the generation of flammable (i.e., H 2) gas during the dissolution process. The dissolution of the Al 6061 T6 alloy proceeded at a slower rate than the Al 1100 alloy and was used to verify that the target Al concentration in solution could be achieved for the selected Hg concentration. Mass spectrometry and Raman spectroscopy were used to provide continuous monitoring of the concentration of H 2 and other permanent gases in the dissolution offgas allowing the development of H 2 generation rate profiles. The H 2 generation rates were subsequently used to evaluate if a full HFIR core could be dissolved in an H-Canyon dissolver without exceeding 60% of the calculated lower flammability limit (LFL) for H 2 at a given Hg

Improved Arterial Blood Oxygenation Following Intravenous Infusion of Cold Supersaturated Dissolved Oxygen Solution

PubMed Central

Grady, Daniel J; Gentile, Michael A; Riggs, John H; Cheifetz, Ira M

2014-01-01

BACKGROUND One of the primary goals of critical care medicine is to support adequate gas exchange without iatrogenic sequelae. An emerging method of delivering supplemental oxygen is intravenously rather than via the traditional inhalation route. The objective of this study was to evaluate the gas-exchange effects of infusing cold intravenous (IV) fluids containing very high partial pressures of dissolved oxygen (>760 mm Hg) in a porcine model. METHODS Juvenile swines were anesthetized and mechanically ventilated. Each animal received an infusion of cold (13 °C) Ringer’s lactate solution (30 mL/kg/hour), which had been supersaturated with dissolved oxygen gas (39.7 mg/L dissolved oxygen, 992 mm Hg, 30.5 mL/L). Arterial blood gases and physiologic measurements were repeated at 15-minute intervals during a 60-minute IV infusion of the supersaturated dissolved oxygen solution. Each animal served as its own control. RESULTS Five swines (12.9 ± 0.9 kg) were studied. Following the 60-minute infusion, there were significant increases in PaO2 and SaO2 (P < 0.05) and a significant decrease in PaCO2 (P < 0.05), with a corresponding normalization in arterial blood pH. Additionally, there was a significant decrease in core body temperature (P < 0.05) when compared to the baseline preinfusion state. CONCLUSIONS A cold, supersaturated dissolved oxygen solution may be intravenously administered to improve arterial blood oxygenation and ventilation parameters and induce a mild therapeutic hypothermia in a porcine model. PMID:25249764

Thermodynamic properties of gases dissolved in electrolyte solutions.

NASA Technical Reports Server (NTRS)

Tiepel, E. W.; Gubbins, K. E.

1973-01-01

A method based on perturbation theory for mixtures is applied to the prediction of thermodynamic properties of gases dissolved in electrolyte solutions. The theory is compared with experimental data for the dependence of the solute activity coefficient on concentration, temperature, and pressure; calculations are included for partial molal enthalpy and volume of the dissolved gas. The theory is also compared with previous theories for salt effects and found to be superior. The calculations are best for salting-out systems. The qualitative feature of salting-in is predicted by the theory, but quantitative predictions are not satisfactory for such systems; this is attributed to approximations made in evaluating the perturbation terms.

Partly standing internal tides in a dendritic submarine canyon observed by an ocean glider

NASA Astrophysics Data System (ADS)

Hall, Rob A.; Aslam, Tahmeena; Huvenne, Veerle A. I.

2017-08-01

An autonomous ocean glider is used to make the first direct measurements of internal tides within Whittard Canyon, a large, dendritic submarine canyon system that incises the Celtic Sea continental slope and a site of high benthic biodiversity. This is the first time a glider has been used for targeted observations of internal tides in a submarine canyon. Vertical isopycnal displacement observations at different stations fit a one-dimensional model of partly standing semidiurnal internal tides - comprised of a major, incident wave propagating up the canyon limbs and a minor wave reflected back down-canyon by steep, supercritical bathymetry near the canyon heads. The up-canyon internal tide energy flux in the primary study limb decreases from 9.2 to 2.0 kW m-1 over 28 km (a dissipation rate of 1 - 2.5 ×10-7 Wkg-1), comparable to elevated energy fluxes and internal tide driven mixing measured in other canyon systems. Within Whittard Canyon, enhanced mixing is inferred from collapsed temperature-salinity curves and weakened dissolved oxygen concentration gradients near the canyon heads. It has previously been hypothesised that internal tides impact benthic fauna through elevated near-bottom current velocities and particle resuspension. In support of this, we infer order 20 cm s-1 near-bottom current velocities in the canyon and observe high concentrations of suspended particulate matter. The glider observations are also used to estimate a 1 °C temperature range and 12 μmol kg-1 dissolved oxygen concentration range, experienced twice a day by organisms on the canyon walls, due to the presence of internal tides. This study highlights how a well-designed glider mission, incorporating a series of tide-resolving stations at key locations, can be used to understand internal tide dynamics in a region of complex topography, a sampling strategy that is applicable to continental shelves and slopes worldwide.

What is the critical pH and why does a tooth dissolve in acid?

PubMed

Dawes, Colin

2003-12-01

This paper discusses the concept of critical pH for dissolution of enamel in oral fluids. The critical pH does not have a fixed value but rather is inversely proportional to the calcium and phosphate concentrations in the solution. The paper also discusses why teeth dissolve in acid, why remineralization of white-spot caries lesions is possible and why remineralization of teeth eroded by acid is not possible.

NEUTRALIZATIONS OF HIGH ALUMINUM LOW URANIUM USED NUCLEAR FUEL SOLUTIONS CONTAINING GADOLINIUM AS A NEUTRON POISON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor-Pashow, K.

2011-06-08

H-Canyon will begin dissolving High Aluminum - Low Uranium (High Al/Low U) Used Nuclear Fuel (UNF) following approval by DOE which is anticipated in CY2011. High Al/Low U is an aluminum/enriched uranium UNF with small quantities of uranium relative to aluminum. The maximum enrichment level expected is 93% {sup 235}U. The High Al/Low U UNF will be dissolved in H-Canyon in a nitric acid/mercury/gadolinium solution. The resulting solution will be neutralized and transferred to Tank 39H in the Tank Farm. To confirm that the solution generated could be poisoned with Gd, neutralized, and discarded to the Savannah River Site (SRS)more » high level waste (HLW) system without undue nuclear safety concerns the caustic precipitation of simulant solutions was examined. Experiments were performed with three simulant solutions representative of the H-Canyon estimated concentrations in the final solutions after dissolution. The maximum U, Gd, and Al concentration were selected for testing from the range of solution compositions provided. Simulants were prepared in three different nitric acid concentrations, ranging from 0.5 to 1.5 M. The simulant solutions were neutralized to four different endpoints: (1) just before a solid phase was formed (pH 3.5-4), (2) the point where a solid phase was obtained, (3) 0.8 M free hydroxide, and (4) 1.2 M free hydroxide, using 50 wt % sodium hydroxide (NaOH). The settling behavior of the neutralized solutions was found to be slower compared to previous studies, with settling continuing over a one week period. Due to the high concentration of Al in these solutions, precipitation of solids was observed immediately upon addition of NaOH. Precipitation continued as additional NaOH was added, reaching a point where the mixture becomes almost completely solid due to the large amount of precipitate. As additional NaOH was added, some of the precipitate began to redissolve, and the solutions neutralized to the final two endpoints mixed easily and had

A novel bioactive haemodialysis system using dissolved dihydrogen (H2) produced by water electrolysis: a clinical trial.

PubMed

Nakayama, Masaaki; Nakano, Hirofumi; Hamada, Hiromi; Itami, Noritomo; Nakazawa, Ryoichi; Ito, Sadayoshi

2010-09-01

Chronic inflammation in haemodialysis (HD) patients indicates a poor prognosis. However, therapeutic approaches are limited. Hydrogen gas (H(2)) ameliorates oxidative and inflammatory injuries to organs in animal models. We developed an HD system using a dialysis solution with high levels of dissolved H(2) and examined the clinical effects. Dialysis solution with H(2) (average of 48 ppb) was produced by mixing dialysate concentrates and reverse osmosis water containing dissolved H(2) generated by a water electrolysis technique. Subjects comprised 21 stable patients on standard HD who were switched to the test HD for 6 months at three sessions a week. During the study period, no adverse clinical signs or symptoms were observed. A significant decrease in systolic blood pressure (SBP) before and after dialysis was observed during the study, and a significant number of patients achieved SBP <140 mmHg after HD (baseline, 21%; 6 months, 62%; P < 0.05). Changes in dialysis parameters were minimal, while significant decreases in levels of plasma monocyte chemoattractant protein 1 (P < 0.01) and myeloperoxidase (P < 0.05) were identified. Adding H(2) to haemodialysis solutions ameliorated inflammatory reactions and improved BP control. This system could offer a novel therapeutic option for control of uraemia.

GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pierce, R. A.

2012-03-12

HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into themore » H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 °C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. At 25 °C, for 6 M HNO{sub 3}, 11 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2.5 g/L and 0.8 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}. The solubility of Gd in 4 M HNO{sub 3} with 0.15 M oxalate at 10 °C is about 1.5 g/L. For 6 M HNO{sub 3} with 0.15 M oxalate, the solubility of

Bulk Dissolution Rates of Cadmium and Bismuth Tellurides As a Function of pH, Temperature and Dissolved Oxygen.

PubMed

Biver, Marc; Filella, Montserrat

2016-05-03

The toxicity of Cd being well established and that of Te suspected, the bulk, surface-normalized steady-state dissolution rates of two industrially important binary tellurides-polycrystalline cadmium and bismuth tellurides- were studied over the pH range 3-11, at various temperatures (25-70 °C) and dissolved oxygen concentrations (0-100% O2 in the gas phase). The behavior of both tellurides is strikingly different. The dissolution rates of CdTe monotonically decreased with increasing pH, the trend becoming more pronounced with increasing temperature. Activation energies were of the order of magnitude associated with surface controlled processes; they decreased with decreasing acidity. At pH 7, the CdTe dissolution rate increased linearly with dissolved oxygen. In anoxic solution, CdTe dissolved at a finite rate. In contrast, the dissolution rate of Bi2Te3 passed through a minimum at pH 5.3. The activation energy had a maximum in the rate minimum at pH 5.3 and fell below the threshold for diffusion control at pH 11. No oxygen dependence was detected. Bi2Te3 dissolves much more slowly than CdTe; from one to more than 3.5 orders of magnitude in the Bi2Te3 rate minimum. Both will readily dissolve under long-term landfill deposition conditions but comparatively slowly.

Strategic guidelines for street canyon geometry to achieve sustainable street air quality

NASA Astrophysics Data System (ADS)

Chan, Andy T.; So, Ellen S. P.; Samad, Subash C.

This paper is concerned with the motion of air within the urban street canyon and is directed towards a deeper understanding of pollutant dispersion with respect to various simple canyon geometries and source positions. Taking into account the present days typical urban configurations, three principal flow regimes "isolated roughness flow", "skimming flow" and "wake interference flow" (Boundary Layer Climates, 2nd edition, Methuen, London) and their corresponding pollutant dispersion characteristics are studied for various canopies aspect ratios, namely relative height ( h2/ h1), canyon height to width ratio ( h/ w) and canyon length to height ratio ( l/ h). A field-size canyon has been analyzed through numerical simulations using the standard k- ɛ turbulence closure model. It is found that the pollutant transport and diffusion is strongly dependent upon the type of flow regime inside the canyon and exchange between canyon and the above roof air. Some rules of thumbs have been established to get urban canyon geometries for efficient dispersion of pollutants.

Pollutant Dilution and Diffusion in Urban Street Canyon Neighboring Streets

NASA Astrophysics Data System (ADS)

Sun, Z.; Fu, Zh. M.

2011-09-01

In the present study we investigated the airflow patterns and air quality of a series of typical street canyon combinations, developed a mass balance model to determine the local pollutant dilution rate, and discuss the impact of upstream canyon on the air quality of downstream canyon. The results indicated that the geometrical size of upstream and downstream buildings have significant impacts on the ambient airflow patterns. The pollution distribution within the canyons varies with different building combinations and flow patterns. Within the upstream canyon, pollution always accumulates to the low building side for non-symmetrical canyon, and for symmetrical canyon high level of pollution occurs at the leeward side. The height of the middle and downstream buildings can evidently change the pollutant dispersion direction during the transport process. Within the polluted canyon, the pollutant dilution rate (PDR) also varies with different street canyon combinations. The highest PDR is observed when the upstream buildings are both low buildings no matter the height of downstream building. However, the two cases are likely to contribution pollution to the downstream canyon. The H-L-H combination is mostly against local pollution remove, while the L-H-L case is considered the best optimistic building combination with both the ability of diluting local pollution and not remarkably decreasing air quality of downstream canyon. The current work is expected instructive for city designers to optimize traffic patterns under typical existing geometry or in the development of urban geometry modification for air quality control.

Dissolution Flowsheet for High Flux Isotope Reactor Fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniel, W. E.; Rudisill, T. S.; O'Rourke, P. E.

2016-09-27

As part of the Spent Nuclear Fuel (SNF) processing campaign, H-Canyon is planning to begin dissolving High Flux Isotope Reactor (HFIR) fuel in late FY17 or early FY18. Each HFIR fuel core contains inner and outer fuel elements which were fabricated from uranium oxide (U 3O 8) dispersed in a continuous Al phase using traditional powder metallurgy techniques. Fuels fabricated in this manner, like other SNF’s processed in H-Canyon, dissolve by the same general mechanisms with similar gas generation rates and the production of H 2. The HFIR fuel cores will be dissolved and the recovered U will be down-blendedmore » into low-enriched U. HFIR fuel was previously processed in H-Canyon using a unique insert in both the 6.1D and 6.4D dissolvers. Multiple cores will be charged to the same dissolver solution maximizing the concentration of dissolved Al. The objective of this study was to identify flowsheet conditions through literature review and laboratory experimentation to safely and efficiently dissolve the HFIR fuel in H-Canyon. Laboratory-scale experiments were performed to evaluate the dissolution of HFIR fuel using both Al 1100 and Al 6061 T6 alloy coupons. The Al 1100 alloy was considered a representative surrogate which provided an upper bound on the generation of flammable (i.e., H 2) gas during the dissolution process. The dissolution of the Al 6061 T6 alloy proceeded at a slower rate than the Al 1100 alloy, and was used to verify that the target Al concentration in solution could be achieved for the selected Hg concentration. Mass spectrometry and Raman spectroscopy were used to provide continuous monitoring of the concentration of H 2 and other permanent gases in the dissolution offgas, allowing the development of H 2 generation rate profiles. The H 2 generation rates were subsequently used to evaluate if a full HFIR core could be dissolved in an H-Canyon dissolver without exceeding 60% of the calculated lower flammability limit (LFL) for H 2 at a given Hg

Mega-solubility of quartz resulting from highly alkaline fluids produced by dissolved albite in H2O at deep crustal conditions

NASA Astrophysics Data System (ADS)

Makhluf, A. R.; Manning, C. E.

2017-12-01

Models of H2O-rich fluids equilibrated with rocks at high P and T fail to predict the high solubilities observed experimentally, chiefly because thermodynamic data for the most abundant solutes is lacking. We investigated the effects of dissolved albite (Ab) on the solubility of quartz (Qz) at 1.0 GPa and 675-900 °C using a piston-cylinder apparatus to quantify possible mineral buffering or enhancement effects. We found a very large enhancement effect on the solubility of Qz when dissolved in dilute aqueous Ab solutions. SiO2 concentrations are similar to Qz solubility in strongly alkaline KOH solutions. At the highest temperature of 900 °C, we found that the solubility of Qz in 1.0 molal Ab solution increases by of factor of 4.5 over that in pure H2O, which corresponds to 10.7 molal SiO2. The nearly identical solubility of Qz in KOH(aq) and Ab solutions of the same concentration, P, and T, strongly suggest that NaOH(aq) liberated from NaAlSi3O8 in H2O fluids effects SiO2 solubility in a similar manner to that of KOH(aq). The deprotonated silica dimer was found to be a key species responsible for the high solubility of Qz in KOH(aq) and is likely responsible for the high solubility of Qz in Ab solutions. While the binaries Qz-H2O, Ab-H2O, and Qz-Ab are well known at 1.0 GPa, little data exists on the ternary system. The new results help quantify the ternary relations in the Ab-Qz-H2O system, which can be used as a simple model for liquid-vapor immiscibility granitic magmas. In addition, these highly alkaline solute-rich aqueous fluids suggest a mechanism for Ab-Qz metasomatism in subduction zones, such as in the Catalina schist (Bebout and Barton 1993), which provides an alternative to high P-T magmas. Our results show that subduction zone and metasomatic fluids may be much more alkaline and have significantly higher dissolving power than previously thought.

[Dissolved aluminum and organic carbon in soil solution under six tree stands in Lushan forest ecosystems].

PubMed

Wang, Lianfeng; Pan, Genxing; Shi, Shengli; Zhang, Lehua; Huang, Mingxing

2003-10-01

Different depths of soils under 6 tree stands in Lushan Botany Garden were sampled and water-digested at room temperature. The dissolved aluminum and organic carbon were then determined by colorimetry, using 8-hydroxylquilin and TOC Analyzer, respectively. The results indicated that even derived from a naturally identical soil type, the test soils exhibited a diverse solution chemistry, regarding with the Al speciation. The soil solutions under Japanese cedar, giant arborvitae and tea had lower pH values and higher contents of soluble aluminum than those under Giant dogwood, azalea and bamboo. Under giant arborvitae, the lowest pH and the highest content of total soluble aluminum and monomeric aluminum were found in soil solution. There was a significant correlation between soluble aluminum and DOC, which tended to depress the accumulation of toxic monomeric aluminum. The 6 tree stands could be grouped into 2 categories of solution chemistry, according to aluminum mobilization.

Reclamation of cadmium-contaminated soil using dissolved organic matter solution originating from wine-processing waste sludge.

PubMed

Liu, Cheng-Chung; Chen, Guan-Bu

2013-01-15

Soil washing using an acid solution is a common practice for removing heavy metals from contaminated soil in Taiwan. However, serious loss of nutrients from soil is a major drawback of the washing. Distillery sludge can be used to prepare a dissolved organic matter (DOM) solution by extracting its organic constituents with alkaline solutions. This study employed DOM solutions to remediate Cd-contaminated soil (with concentrations up to 21.5 mg kg(-1)) and determine the factors affecting removal of Cd, such as pH, initial concentration of DOM solution, temperature, and washing frequency. When washing with pH 3.0 and 1250 mg L(-1) DOM solution, about 80% and 81% of Cd were removed from the topsoil at 27 °C and subsoil at 40 °C, respectively. To summarize the changes in fertility during DOM washing with various pH solutions: the increase in organic matter content ranged from 7.7% to 23.7%; cation exchange capacity (CEC) ranged from 4.6% to 13.9%; available ammonium (NNH(4)) content ranged from 39.4% to 2175%; and available phosphorus content ranged from 34.5% to 182%. Exchangeable K, Ca, and Mg remained in the topsoil after DOM washing, with concentrations of 1.1, 2.4, and 1.5 times higher than those treated with HCl solution at the same pH, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparison of various solutions to dissolve critical care diet clots.

PubMed

Parker, Valerie J; Freeman, Lisa M

2013-01-01

Enteral feeding tubes are frequently placed in animals to provide assisted nutritional support; however, one major reported complication is clogging of the tubes. The goal of this study was to determine which solution is most effective at dissolving in vitro clots made using a veterinary canned critical care diet. Various solutions were tested for their ability to dissolve enteral feed clots, including water, meat tenderizers in water, predetermined amounts of pancreatic enzymes (with and without sodium bicarbonate) in water, carbonated beverages, and cranberry juice. The solution that resulted in the greatest dissolution was ¼ teaspoon pancreatic enzymes and 325 mg sodium bicarbonate in 5 mL water, which was significantly better than all other solutions (water: P = 0.03; ¼ teaspoon pancreatic enzymes in water: P = 0.002; all others: P < 0.001). Water was significantly better than all carbonated beverages and cranberry juice (P < 0.001). The least successful solution was ½ teaspoon pancreatic enzymes and sodium bicarbonate in water. Despite anecdotal reports of using carbonated beverages, cranberry juice, and ½ teaspoon pancreatic enzymes to unclog feeding tubes, all were significantly less effective than water. In vivo studies to evaluate the effectiveness of methods to unclog feeding tubes are warranted to further investigate these findings. © Veterinary Emergency and Critical Care Society 2013.

The effect of probe choice and solution conditions on the apparent photoreactivity of dissolved organic matter.

PubMed

Maizel, Andrew C; Remucal, Christina K

2017-08-16

Excited triplet states of dissolved organic matter ( 3 DOM) are quantified directly with the species-specific probes trans,trans-hexadienoic acid (HDA) and 2,4,6-trimethylphenol (TMP), and indirectly with the singlet oxygen ( 1 O 2 ) probe furfuryl alcohol (FFA). Although previous work suggests that these probe compounds may be sensitive to solution conditions, including dissolved organic carbon concentration ([DOC]) and pH, and may quantify different 3 DOM subpopulations, the probes have not been systematically compared. Therefore, we quantify the apparent photoreactivity of diverse environmental waters using HDA, TMP, and FFA. By conducting experiments under ambient [DOC] and pH, with standardized [DOC] and pH, and with solid phase extraction isolates, we demonstrate that much of the apparent dissimilarity in photochemical measurements is attributable to solution conditions, rather than intrinsic differences in 3 DOM production. In general, apparent quantum yields (Φ 1 O 2 ≥ Φ 3 DOM,TMP ≫ Φ 3 DOM,HDA ) and pseudo-steady state concentrations ([ 1 O 2 ] ss > [ 3 DOM] ss,TMP > [ 3 DOM] ss,HDA ) show consistent relationships in all waters under standardized conditions. However, intrinsic differences in 3 DOM photoreactivity are apparent between DOM from diverse sources, as seen in the higher Φ 1 O 2 and lower Φ 3 DOM,TMP of wastewater effluents compared with oligotrophic lakes. Additionally, while conflicting trends in photoreactivity are observed under ambient conditions, all probes observe quantum yields increasing from surface wetlands to terrestrially influenced waters to oligotrophic lakes under standardized conditions. This work elucidates how probe selection and solution conditions influence the apparent photoreactivity of environmental waters and confirms that 3 DOM or 1 O 2 probes cannot be used interchangeably in waters that vary in [DOC], pH, or DOM source.

Dissolved methane concentrations in the water column and surface sediments of Hanna Shoal and Barrow Canyon, Northern Chukchi Sea

NASA Astrophysics Data System (ADS)

Lapham, Laura; Marshall, Kathleen; Magen, Cédric; Lyubchich, Viacheslav; Cooper, Lee W.; Grebmeier, Jacqueline M.

2017-10-01

Current estimates of methane (CH4) flux suggest that Arctic shelves may be a significant source of atmospheric CH4, a potent greenhouse gas. However, little information is known about the CH4 flux from most Arctic shelves, other than the East Siberian Arctic Shelf. We report here dissolved CH4 concentrations in the water column and within surface sediments of the Northern Chukchi Sea. We hypothesized that this area contains high concentrations of CH4 because it receives nutrient rich waters through the Bering Strait, promoting primary production that enhances an organic-rich material flux to the seafloor and eventual microbial methanogenesis in the sediments. In August 2012, as part of the Chukchi Sea Offshore Monitoring in Drilling Area (COMIDA) project, fourteen stations were sampled on Hanna Shoal, a shallow feature on the shelf, and ten stations across the undersea Barrow Canyon. On Hanna Shoal, water column CH4 concentrations ranged from 14 to 74 nM, and surface concentrations were up to 15 times supersaturated in CH4 compared to equilibrium with the average atmospheric concentrations (3 nM). CH4 concentrations at the sediment-water interface were around 1,500 nM, and typically increased with depth in the sediment. At the head of Barrow Canyon, water column CH4 concentrations ranged from 5 to 46 nM, with the highest concentrations in the deepest waters that were sampled (118 m). Overall, the calculated fluxes to the atmosphere ranged from 1 to 80 μmol CH4 m-2 d-1 for Hanna Shoal and 4 to 17 μmol CH4 m-2 d-1 across the Barrow Canyon stations. Although there was a large range in these fluxes, the average atmospheric flux (20 μmol CH4 m-2 d-1) across Hanna Shoal was 12 times lower than the flux reported from the East Siberian Arctic Shelf in summer. We conclude that while there is a positive flux of CH4 to the atmosphere, this part of the Chukchi Sea is not a significant source of atmospheric CH4 compared to the East Siberian Sea shelf.

Data from synoptic water-quality studies on the Colorado River in the Grand Canyon, Arizona, November 1990 and June 1991

USGS Publications Warehouse

Taylor, Howard E.; Peart, D.B.; Antweiler, Ronald C.; Brinton, T.I.; Campbell, W.L.; Barbarino, J.R.; Roth, D.A.; Hart, R.J.; Averett, R.C.

1996-01-01

Two water-quality synoptic studies were made on the Colorado River in the Grand Canyon, Arizona. Field measurements and the collection of water samples for laboratory analysis were made at 10 mainstem and 6 tributary sites every 6 hours for a 48-hour period on November 5-6, 1990, and again on June 18-20, 1991. Field measurements included discharge, alkalinity, water temperature, light penetration, pH, specific conductance, and dissolved oxygen. Water samples were collected for the laboratory analysis of major and minor ions (calcium, magnesium, sodium, potassium, strontium, chloride, sulfate, silica as SiO2), trace elements (aluminum, arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, iron, lead, lithium, manganese, molybdenum, nickel, selenium, thallium, uranium, vanadium and zinc), and nutrients (phosphate, nitrate, ammonium, nitrite, total dissolved nitrogen, total dissolved phosphorus and dissolved organic carbon). Biological measurements included drift (benthic invertebrates and detrital material), and benthic invertebrates from the river bottom.

Identifying sources and processes controlling the sulphur cycle in the Canyon Creek watershed, Alberta, Canada.

PubMed

Nightingale, Michael; Mayer, Bernhard

2012-01-01

Sources and processes affecting the sulphur cycle in the Canyon Creek watershed in Alberta (Canada) were investigated. The catchment is important for water supply and recreational activities and is also a source of oil and natural gas. Water was collected from 10 locations along an 8 km stretch of Canyon Creek including three so-called sulphur pools, followed by the chemical and isotopic analyses on water and its major dissolved species. The δ(2)H and δ(18)O values of the water plotted near the regional meteoric water line, indicating a meteoric origin of the water and no contribution from deeper formation waters. Calcium, magnesium and bicarbonate were the dominant ions in the upstream portion of the watershed, whereas sulphate was the dominant anion in the water from the three sulphur pools. The isotopic composition of sulphate (δ(34)S and δ(18)O) revealed three major sulphate sources with distinct isotopic compositions throughout the catchment: (1) a combination of sulphate from soils and sulphide oxidation in the bedrock in the upper reaches of Canyon Creek; (2) sulphide oxidation in pyrite-rich shales in the lower reaches of Canyon Creek and (3) dissolution of Devonian anhydrite constituting the major sulphate source for the three sulphur pools in the central portion of the watershed. The presence of H(2)S in the sulphur pools with δ(34)S values ∼30 ‰ lower than those of sulphate further indicated the occurrence of bacterial (dissimilatory) sulphate reduction. This case study reveals that δ(34)S values of surface water systems can vary by more than 20 ‰ over short geographic distances and that isotope analyses are an effective tool to identify sources and processes that govern the sulphur cycle in watersheds.

Detection of hydrogen dissolved in acrylonitrile butadiene rubber by 1H nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Nishimura, Shin; Fujiwara, Hirotada

2012-01-01

Rubber materials, which are used for hydrogen gas seal, can dissolve hydrogen during exposure in high-pressure hydrogen gas. Dissolved hydrogen molecules were detected by solid state 1H NMR of the unfilled vulcanized acrylonitrile butadiene rubber. Two signals were observed at 4.5 ppm and 4.8 ppm, which were assignable to dissolved hydrogen, in the 1H NMR spectrum of NBR after being exposed 100 MPa hydrogen gas for 24 h at room temperature. These signals were shifted from that of gaseous hydrogen molecules. Assignment of the signals was confirmed by quantitative estimation of dissolved hydrogen and peak area of the signals.

Analytical method for dissolved-organic carbon fractionation

USGS Publications Warehouse

Leenheer, Jerry A.; Huffman, Edward W. D.

1979-01-01

A standard procedure for analytical-scale dissolved organic carbon fractionation is presented, whereby dissolved organic carbon in water is first fractionated by a nonionic macroreticular resin into acid, base, and neutral hydrophobic organic solute fractions, and next fractionated by ion-exchange resins into acid, base, and neutral hydrophilic solute fractions. The hydrophobic solutes are defined as those sorbed on a nonionic, acrylic-ester macroreticular resin and are differentiated into acid, base, and nautral fractions by sorption/desorption controlled by pH adjustment. The hydrophilic bases are next sorbed on strong-acid ion-exchange resin, followed by sorption of hydrophilic acids on a strong-base ion-exchange resin. Hydrophilic neutrals are not sorbed and remain dissolved in the deionized water at the end of the fractionation procedure. The complete fractionation can be performed on a 200-milliliter filtered water sample, whose dissolved organic carbon content is 5-25 mg/L and whose specific conductance is less than 2,000 μmhos/cm at 25°C. The applications of dissolved organic carbon fractionation analysis range from field studies of changes of organic solute composition with synthetic fossil fuel production, to fundamental studies of the nature of sorption processes.

Macrofaunal Patterns in and around du Couedic and Bonney Submarine Canyons, South Australia

PubMed Central

Dittmann, Sabine; Sorokin, Shirley J.; Hendrycks, Ed

2015-01-01

Two South Australian canyons, one shelf-incising (du Couedic) and one slope-limited (Bonney) were compared for macrofaunal patterns on the shelf and slope that spanned three water masses. It was hypothesized that community structure would (H1) significantly differ by water mass, (H2) show significant regional differences and (H3) differ significantly between interior and exterior of each canyon. Five hundred and thirty-one species of macrofauna ≥1 mm were captured at 27 stations situated in depth stratified transects inside and outside the canyons from 100 to1500 m depth. The macrofauna showed a positive relationship to depth in abundance, biomass, species richness and community composition while taxonomic distinctness and evenness remained high at all depths. Biotic variation on the shelf was best defined by variation in bottom water primary production while sediment characteristics and bottom water oxygen, temperature and nutrients defined biotic variation at greater depth. Community structure differed significantly (p<0.01) among the three water masses (shelf-flowing South Australian current, upper slope Flinders current and lower slope Antarctic Intermediate Water) (H1). Although community differences between the du Couedic and Bonney regions were marginally above significance at p = 0.05 (H2), over half of the species captured were unique to each region. This supports the evidence from fish and megafaunal distributions that the du Couedic and Bonney areas are in different bioregions. Overall, the canyon interiors were not significantly different in community composition from the exterior (H3). However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m), suggestive of heightened currents within the canyons that influence community composition there. At 1000–1500 m, the canyon interiors were

Seasonal monitoring of deep-sea megabenthos in Barkley Canyon cold seep by internet operated vehicle (IOV).

PubMed

Doya, Carolina; Chatzievangelou, Damianos; Bahamon, Nixon; Purser, Autun; De Leo, Fabio C; Juniper, S Kim; Thomsen, Laurenz; Aguzzi, Jacopo

2017-01-01

Knowledge of the processes shaping deep-sea benthic communities at seasonal scales in cold-seep environments is incomplete. Cold seeps within highly dynamic regions, such as submarine canyons, where variable current regimes may occur, are particularly understudied. Novel Internet Operated Vehicles (IOVs), such as tracked crawlers, provide new techniques for investigating these ecosystems over prolonged periods. In this study a benthic crawler connected to the NEPTUNE cabled infrastructure operated by Ocean Networks Canada was used to monitor community changes across 60 m2 of a cold-seep area of the Barkley Canyon, North East Pacific, at ~890 m depth within an Oxygen Minimum Zone (OMZ). Short video-transects were run at 4-h intervals during the first week of successive calendar months, over a 14 month period (February 14th 2013 to April 14th 2014). Within each recorded transect video megafauna abundances were computed and changes in environmental conditions concurrently measured. The responses of fauna to environmental conditions as a proxy of seasonality were assessed through analysis of abundances in a total of 438 video-transects (over 92 h of total footage). 7698 fauna individuals from 6 phyla (Cnidaria, Ctenophora, Arthropoda, Echinodermata, Mollusca, and Chordata) were logged and patterns in abundances of the 7 most abundant taxa (i.e. rockfish Sebastidae, sablefish Anoplopoma fimbria, hagfish Eptatretus stoutii, buccinids (Buccinoidea), undefined small crabs, ctenophores Bolinopsis infundibulum, and Scyphomedusa Poralia rufescens) were identified. Patterns in the reproductive behaviour of the grooved tanner crab (Chionnecetes tanneri) were also indicated. Temporal variations in biodiversity and abundance in megabenthic fauna was significantly influenced by variabilities in flow velocity flow direction (up or down canyon), dissolved oxygen concentration and month of study. Also reported here for the first time are transient mass aggregations of grooved tanner

4. DARK CANYON SIPHON VIEW ACROSS DARK CANYON AT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. DARK CANYON SIPHON - VIEW ACROSS DARK CANYON AT LOCATION OF SIPHON. VIEW TO NORTHWEST - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

Azomethine H colorimetric method for determining dissolved boron in water

USGS Publications Warehouse

Spencer, R.R.; Erdmann, D.E.

1979-01-01

An automated colorimetric method for determining dissolved boron in water is described. The boron is complexed with azomethine H, which is readily available as the condensation product of H acid (8-amino-1-naphthol-3,6-disulfonic acid) and salicylaldehyde. The absorbance of the yellow complex formed is then measured colorimetrically at 410 nm. Interference effects from other dissolved species are minimized by the addition of diethylenetriaminepentaacetic acid (DTPA); however, iron, zinc, and bicarbonate interfere at concentrations above 400 ??g/L, 2000 ??g/L, and 200 mg/L, respectively. The bicarbonate interference can be eliminated by careful acidification of the sample with concentrated HCl to a pH between 5 and 6. Thirty samples per hour can be routinely analyzed over the range of from 10 to 400 ??g/L, boron.

Analysis of the Momentum and Pollutant Transport at the Roof Level of 2D Idealized Street Canyons: a Large-Eddy Simulation Solution

NASA Astrophysics Data System (ADS)

Cheng, Wai Chi; Liu, Chun-Ho

2010-05-01

vigorous turbulent transport and mixing near the windward facade. Budget analyses of the velocity variance, shear stress, pollutant concentration and pollutant flux were also performed. A sharp peak of TKE production is developed at the roof level. Owing to the strong gradient of streamwise velocity, the streamwise velocity fluctuation is promoted first. The TKE is then transferred from the streamwise to the spanwise and vertical velocity fluctuations via the pressure-rate-of-strain tensor. Analogous to the quadrant analyses, the TKE production grows from a sharp peak (~0.1h width, where h is the building height) on the leeward side to a broad one (~0.5h width) on the windward side. This pattern is partly attributed to the growth of the flow instability and the enhanced turbulent processes along the roof of the street canyon in the streamwise direction. The pollutant removal mechanism is clearly illustrated by the budget analysis of the pollutant concentration. The pollutant is carried by the primary recirculation from the ground level to the roof level of the street canyon. The vertical turbulent pollutant flux dominates the pollutant removal in the region right below the roof level (0.8h) while the streamwise advection dominates the pollutant removal in the shear layer (hh). It is thus suggested that the pollutant is initially removed vertically from the street canyon to the shear layer by turbulence before being carried away by the prevalent wind. Moreover, the roof-level flow instability was found to play a major role so a more efficient pollutant removal was observed on the windward side.

Hydrogeology of Middle Canyon, Oquirrh Mountains, Tooele County, Utah

USGS Publications Warehouse

Gates, Joseph Spencer

1963-01-01

Geology and climate are the principal influences affecting the hydrology of Middle Canyon, Tooele County, Utah. Reconnaissance in the canyon indicated that the geologic influences on the hydrology may be localized; water may be leaking through fault and fracture zones or joints in sandstone and through solution openings in limestone of the Oquirrh formation of Pennsylvanian and Permian age. Surficial deposits of Quaternary age serve as the main storage material for ground water in the canyon and transmit water from the upper canyon to springs and drains at the canyon mouth. The upper canyon is a more important storage area than the lower canyon because the surficial deposits are thicker, and any zones of leakage in the underlying bedrock of the upper canyon probably would result in greater leakage than would similar outlets in the lower canyon.The total annual discharge from Middle Canyon, per unit of precipitation, decreased between 1910 and 1939. Similar decreases occurred in Parleys Canyon in the nearby Wasatch Range and in other drainage basins in Utah, and it is likely that most of the decrease in discharge from Middle Canyon and other canyons in Utah is due to a change in climate.Chemical analyses of water showed that the high content of sulfate and other constituents in the water from the Utah Metals tunnel, which drains into Middle Canyon, does not have a significant effect on water quality at the canyon mouth. This suggests that much of the tunnel water is lost from the channel by leakage, probably in the upper canyon, during the dry part of the year.Comparison of the 150 acre-feet of water per square mile of drainage area discharged by Middle Canyon in 1947 with the 623 and 543 acre-feet per square mile discharged in 1948 by City Creek and Mill Creek Canyons, two comparable drainage basins in the nearby Wasatch Range, also suggests that there is leakage in Middle Canyon.A hydrologic budget of the drainage basin results in an estimate that about 3,000 acre

Mineral resources of the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas, Carbon Emery, and Grand counties, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cashion, W.B.; Kilburn, J.E.; Barton, H.N.

1990-09-01

This paper reports on the Desolation Canyon, Turtle Canyon, and Floy Canyon Wilderness Study Areas which include 242,000 acres, 33,690 acres, and 23,140 acres. Coal deposits underlie all three study areas. Coal zones in the Blackhawk and Nelsen formations have identified bituminous coal resources of 22 million short tons in the Desolation Canyon Study Area, 6.3 million short tons in the Turtle Canyon Study Area, and 45 million short tons in the Floy Canyon Study Area. In-place inferred oil shale resources are estimated to contain 60 million barrels in the northern part of the Desolation Canyon area. Minor occurrences ofmore » uranium have been found in the southeastern part of the Desolation Canyon area and in the western part of the Floy Canyon area. Mineral resource potential for the study areas is estimated to be for coal, high for all areas, for oil and gas, high for the northern tract of the Desolation Canyon area and moderate for all other tracts, for bituminous sandstone, high for the northern part of the Desolation Canyon area, and low for all other tracts, for oil shale, low in all areas, for uranium, moderate for the Floy Canyon area and the southeastern part of the Desolation Canyon area and low for the remainder of the areas, for metals other than uranium, bentonite, zeolites, and geothermal energy, low in all areas, and for coal-bed methane unknown in all three areas.« less

Enzymatic hydrolysis of cellulose dissolved in N-methyl morpholine oxide/water solutions.

PubMed

Ramakrishnan, S; Collier, J; Oyetunji, R; Stutts, B; Burnett, R

2010-07-01

In situ hydrolysis of cellulose (dissolving pulp) in N-methyl morpholine oxide (NMMO) solutions by commercially available Accellerase1000 is carried out. The yield of reducing sugars is followed as a function of time at three different temperatures and four different enzyme loadings to study the effect of system parameters on enzymatic hydrolysis. Initial results show that rates of hydrolysis of cellulose and yields of reducing sugars in the presence of NMMO-water is superior initially (ratio of initial reaction rates approximately 4) and comparable to that of regenerated cellulose (for times greater than 5h) when suspended in aqueous solutions. The usage of Accellerase1000 results predominantly in the formation of glucose with minimal amounts of cellobiose. This study proves the ability of cellulases to remain active in NMMO to carry out an in situ saccharification of cellulose thus eliminating the need to recover regenerated cellulose. Thus this work will form the basis for developing a continuous process for conversion of biomass to hydrogen, ethanol and other hydrocarbons. Copyright 2009 Elsevier Ltd. All rights reserved.

Extraction equilibrium of indium(III) from nitric acid solutions by di(2-ethylhexyl)phosphoric acid dissolved in kerosene.

PubMed

Tsai, Hung-Sheng; Tsai, Teh-Hua

2012-01-04

The extraction equilibrium of indium(III) from a nitric acid solution using di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant of organophosphorus compounds dissolved in kerosene was studied. By graphical and numerical analysis, the compositions of indium-D2EHPA complexes in organic phase and stoichiometry of the extraction reaction were examined. Nitric acid solutions with various indium concentrations at 25 °C were used to obtain the equilibrium constant of InR₃ in the organic phase. The experimental results showed that the extraction distribution ratios of indium(III) between the organic phase and the aqueous solution increased when either the pH value of the aqueous solution and/or the concentration of the organic phase extractant increased. Finally, the recovery efficiency of indium(III) in nitric acid was measured.

Water quality and quantity of selected springs and seeps along the Colorado River corridor, Utah and Arizona: Arches National Park, Canyonlands National Park, Glen Canyon National Recreation Area, and Grand Canyon National Park, 1997-98

USGS Publications Warehouse

Taylor, Howard E.; Spence, John R.; Antweiler, Ronald C.; Berghoff, Kevin; Plowman, Terry I.; Peart, Dale B.; Roth, David A.

2004-01-01

The U.S. Geological Survey, in cooperation with the National Park Service conducted an intensive assessment of selected springs along the Colorado River Corridor in Arches National Park, Canyonlands National Park, Glen Canyon National Recreation Area, and Grand Canyon National Park in 1997 and 1998, for the purpose of measuring and evaluating the water quality and quantity of the resource. This study was conducted to establish baseline data for the future evaluation of possible effects from recreational use and climate change. Selected springs and seeps were visited over a study period from 1997 to 1998, during which, discharge and on-site chemical measurements were made at selected springs and seeps, and samples were collected for subsequent chemical laboratory analysis. This interdisciplinary study also includes simultaneous studies of flora and fauna, measured and sampled coincidently at the same sites. Samples collected during this study were transported to U.S. Geological Survey laboratories in Boulder, Colorado, where analyses were performed using state-of-the-art laboratory technology. The location of the selected springs and seeps, elevation, geology, aspect, and onsite measurements including temperature, discharge, dissolved oxygen, pH, and specific conductance, were recorded. Laboratory analyses include determinations for alkalinity, aluminum, ammonium (nitrogen), antimony, arsenic, barium, beryllium, bismuth, boron, bromide, cadmium, calcium, cerium, cesium, chloride, chromium, cobalt, copper, dissolved inorganic carbon, dissolved organic carbon, dysprosium, erbium, europium, fluoride, gadolinium, holmium, iodine, iron, lanthanum, lead, lithium, lutetium, magnesium, manganese, mercury, molybdenum, neodymium, nickel, nitrate (nitrogen), nitrite (nitrogen), phosphate, phosphorus, potassium, praseodymium, rhenium, rubidium, samarium, selenium, silica, silver, sodium, strontium, sulfate, tellurium, terbium, thallium, thorium, thulium, tin, titanium, tungsten

Trees as environmental modifier to improve street canyon for pedestrian activities in Muscat

NASA Astrophysics Data System (ADS)

Khudhayer, Wael A.; Shaaban, Awni K.; Sukor, Nur Sabahiah Abdul

2017-10-01

Street shading efficiency is a function of orientation and profile proportion of its height to width. Under high sun altitude conditions, minimization of solar irradiance within the urban environment may often be a significant criterion in urban design. This reduction in solar irradiance achieved when the obstruction angle is large (high H/W ratio, H=height, W=width). High H/W values often lessen the solar access to streets. The horizontal sprawl of Muscat region is an example of low H/W ratio represented the remarkable challenge that causes the lack of shading rates in the urban street. This characteristic proliferates the negative impact on the pedestrian activities in the urban street. This research aims to improve the morphology of the street to promote the pedestrian behavior. The amendment based on suggesting different configurations of trees to increase effective shading of the urban street in Muscat. The street canyon abstracted into a virtual elongated channel formed of floor and walls of equal heights on both sides. Four street orientations (E/W, N/S, NE/SW, NW/SE) and three H/W ratio (0.5,1 and 2) are considered sufficient representative of street typologies. A mathematical model developed for calculation of shading efficiency of each street canyon. The trees assumed in this study as canyon's modifier to adjust the low H/W ratio of a street canyon to a higher one. Local trees and other plants in Muscat were studied concerning their morphology. The analysis selected two case study in Muscat to investigate the shading performance of their street canyons subsequently propose the modifications to improve it. The research concluded that the suggested changes of the street canyon by using a particular type of trees could increase the H/W ratio of street canyon significantly.

Water-quality data for Walnut Canyon and Wupatki National Monuments, Arizona, 2001-02

USGS Publications Warehouse

Thomas, Blakemore E.

2003-01-01

Water-quality data are provided for four sites in Walnut Canyon and Wupatki National Monuments in north-central Arizona. These data describe the current water quality and provide baseline water-quality information for monitoring future trends. Water samples were collected from a ground-water seep and well in Walnut Canyon and from a spring and a river in Wupatki during September 2001 to September 2002. Water from the four sites is from four different sources. In Walnut Canyon, Cherry Canyon seep is in a shallow local aquifer, and the Little Colorado River contains ground-water discharge from several aquifers and runoff from a 22,000 square-mile drainage area. Concentrations of dissolved solids were similar within the two monuments; the range for water samples from Walnut Canyon was 203 to 248 milligrams per liter, and the range for water samples from Wupatki was 503 to 614 milligrams per liter. Concentrations of trace elements were generally low in water samples from the three ground-water sites--Cherry Canyon seep, Walnut Canyon headquarters well, and Heiser Spring. The water sample collected from the Little Colorado River, however, had high concentrations of aluminum (4,020 micrograms per liter), antimony (54 micrograms per liter), arsenic (14.3 micrograms per liter), and iron (749 micrograms per liter) relative to U.S. Environmental Protection Agency Primary and Secondary Maximum Contaminant Levels. Concentrations of nitrate (as nitrogen) in water samples from the four sites were generally low (0.11 to 1.8 milligrams per liter) and are within the upper 25 percent of nitrate concentrations measured in the regional aquifer near Flagstaff in 1996 and 1997. Water samples from Cherry Canyon seep, Heiser Spring, and the Little Colorado River contained total coliform bacteria. Fecal coliform and Escherichia coli bacteria were found in water samples from Cherry Canyon seep and the Little Colorado River.

Impact of pH, dissolved inorganic carbon, and polyphosphates for the initial stages of water corrosion of copper surfaces investigated by AFM and NEXAFS

EPA Science Inventory

Nanoscale studies at the early stages of the exposure of copper surfaces after systematic treatments in synthesized water solutions can provide useful information about corrosion processes. The corrosion and passivation of copper surfaces as influenced by pH, dissolved inorganic ...

Salivary pH while dissolving vitamin C-containing tablets.

PubMed

Hays, G L; Bullock, Q; Lazzari, E P; Puente, E S

1992-10-01

Vitamin C is packaged in numerous forms which allow protracted exposure of the teeth to ascorbic acid. The repeated use of chewable mega dose tablets of vitamin C as a mint can damage the teeth by dissolving the enamel. In the time it takes to dissolve a chewable vitamin C tablet, a salivary pH drop takes place; salivary calcium and phosphorus ion concentration drops, and enamel dissolution may begin. Although sodium ascorbate, a buffering agent, is present in many vitamin C products, it may be added in insufficient quantity to be effective. With no apparent therapeutic value from topical vitamin C, vitamin C-containing products should be swallowed.

Reclamation of zinc-contaminated soil using a dissolved organic carbon solution prepared using liquid fertilizer from food-waste composting.

PubMed

Chiang, Po-Neng; Tong, Ou-Yang; Chiou, Chyow-San; Lin, Yu-An; Wang, Ming-Kuang; Liu, Cheng-Chung

2016-01-15

A liquid fertilizer obtained through food-waste composting can be used for the preparation of a dissolved organic carbon (DOC) solution. In this study, we used the DOC solutions for the remediation of a Zn-contaminated soil (with Zn concentrations up to 992 and 757 mg kg(-1) in topsoil and subsoil, respectively). We then determined the factors that affect Zn removal, such as pH, initial concentration of DOC solution, and washing frequency. Measurements using a Fourier Transform infrared spectrometer (FT-IR) revealed that carboxyl and amide were the major functional groups in the DOC solution obtained from the liquid fertilizer. Two soil washes using 1,500 mg L(-1) DOC solution with a of pH 2.0 at 25°C removed about 43% and 21% of the initial Zn from the topsoil and subsoil, respectively. Following this treatment, the pH of the soil declined from 5.4 to 4.1; organic matter content slightly increased from 6.2 to 6.5%; available ammonium (NH4(+)-N) content increased to 2.4 times the original level; and in the topsoil, the available phosphorus content and the exchangeable potassium content increased by 1.65 and 2.53 times their initial levels, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of roadside hedgerows on air quality in urban street canyons

NASA Astrophysics Data System (ADS)

Gromke, Christof; Jamarkattel, Nabaraj; Ruck, Bodo

2016-08-01

Understanding pollutant dispersion in the urban environment is an important aspect of providing solutions to reduce personal exposure to vehicle emissions. To this end, the dispersion of gaseous traffic pollutants in urban street canyons with roadside hedges was investigated. The study was performed in an atmospheric boundary layer wind tunnel using a reduced-scale (M = 1:150) canyon model with a street-width-to-building-height ratio of W/H = 2 and a street-length-to-building-height ratio of L/H = 10. Various hedge configurations of differing height, permeability and longitudinal segmentation (continuous over street length L or discontinuous with clearings) were investigated. Two arrangements were examined: (i) two eccentric hedgerows sidewise of the main traffic lanes and (ii) one central hedgerow between the main traffic lanes. In addition, selected configurations of low boundary walls, i.e. solid barriers, were examined. For a perpendicular approach wind and in the presence of continuous hedgerows, improvements in air quality in the center area of the street canyon were found in comparison to the hedge-free reference scenario. The pollutant reductions were greater for the central hedge arrangements than for the sidewise arrangements. Area-averaged reductions between 46 and 61% were observed at pedestrian head height level on the leeward side in front of the building for the centrally arranged hedges and between 18 and 39% for the two hedges arranged sidewise. Corresponding area-averaged reductions ranging from 39 to 55% and from 1 to 20% were found at the bottom of the building facades on the leeward side. Improvements were also found in the areas at the lateral canyon ends next to the crossings for the central hedge arrangements. For the sidewise arrangements, increases in traffic pollutants were generally observed. However, since the concentrations in the end areas were considerably lower compared to those in the center area, an overall improvement remained

Low temperature dissolution flowsheet for plutonium metal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniel, W. E.; Almond, P. M.; Rudisill, T. S.

2016-05-01

The H-Canyon flowsheet used to dissolve Pu metal for PuO 2 production utilizes boiling HNO 3. SRNL was requested to develop a complementary dissolution flowsheet at two reduced temperature ranges. The dissolution and H 2 generation rates of Pu metal were investigated using a dissolving solution at ambient temperature (20-30 °C) and for an intermediate temperature of 50-60 °C. Additionally, the testing included an investigation of the dissolution rates and characterization of the off-gas generated from the ambient temperature dissolution of carbon steel cans and the nylon bags that contain the Pu metal when charged to the dissolver.

Seasonal monitoring of deep-sea megabenthos in Barkley Canyon cold seep by internet operated vehicle (IOV)

PubMed Central

Doya, Carolina; Chatzievangelou, Damianos; Bahamon, Nixon; Purser, Autun; De Leo, Fabio C.; Juniper, S. Kim; Thomsen, Laurenz; Aguzzi, Jacopo

2017-01-01

Knowledge of the processes shaping deep-sea benthic communities at seasonal scales in cold-seep environments is incomplete. Cold seeps within highly dynamic regions, such as submarine canyons, where variable current regimes may occur, are particularly understudied. Novel Internet Operated Vehicles (IOVs), such as tracked crawlers, provide new techniques for investigating these ecosystems over prolonged periods. In this study a benthic crawler connected to the NEPTUNE cabled infrastructure operated by Ocean Networks Canada was used to monitor community changes across 60 m2 of a cold-seep area of the Barkley Canyon, North East Pacific, at ~890 m depth within an Oxygen Minimum Zone (OMZ). Short video-transects were run at 4-h intervals during the first week of successive calendar months, over a 14 month period (February 14th 2013 to April 14th 2014). Within each recorded transect video megafauna abundances were computed and changes in environmental conditions concurrently measured. The responses of fauna to environmental conditions as a proxy of seasonality were assessed through analysis of abundances in a total of 438 video-transects (over 92 h of total footage). 7698 fauna individuals from 6 phyla (Cnidaria, Ctenophora, Arthropoda, Echinodermata, Mollusca, and Chordata) were logged and patterns in abundances of the 7 most abundant taxa (i.e. rockfish Sebastidae, sablefish Anoplopoma fimbria, hagfish Eptatretus stoutii, buccinids (Buccinoidea), undefined small crabs, ctenophores Bolinopsis infundibulum, and Scyphomedusa Poralia rufescens) were identified. Patterns in the reproductive behaviour of the grooved tanner crab (Chionnecetes tanneri) were also indicated. Temporal variations in biodiversity and abundance in megabenthic fauna was significantly influenced by variabilities in flow velocity flow direction (up or down canyon), dissolved oxygen concentration and month of study. Also reported here for the first time are transient mass aggregations of grooved tanner

Injection of sodium borohydride and nzvi solutions into homogeneous sands: H2 gas production and implications

NASA Astrophysics Data System (ADS)

Mohammed, O.; Mumford, K. G.; Sleep, B. E.

2016-12-01

Gases are commonly introduced into the subsurface via external displacement (drainage). However, gases can also be produced by internal drainage (exsolution). One example is the injection of reactive solutions for in situ groundwater remediation, such as nanoscale zero-valent iron (nzvi), which produces hydrogen gas (H2). Effective implementation of nzvi requires an understanding of H2 gas generation and dynamics, and their effects on aqueous permeability, contaminant mass transfer and potential flow diversion. Several studies have reported using excess sodium borohydride (NaBH4) in nzvi applications to promote complete reaction and to ensure uniform nzvi particle growth, which also produces H2 gas. The aim of this study was to visualize and quantify H2 produced by exsolution from the injection of NaBH4 and nzvi solutions into homogeneous sands, and to investigate the reduction of hydraulic conductivity caused by the H2 gas and the subsequent increase in hydraulic conductivity as the gas dissolved. Bench-scale experiments were performed using cold (4 °C) NaBH4 solutions injected in sand packed in a 22 cm × 34 cm × 1 cm flow cell. The injected solution was allowed to warm to room temperature, for controlled production of a uniform distribution of exsolved gas. A light transmission method was used to quantify gas production and dissolution over time. The results indicate a reduction of hydraulic conductivity due to the existence of H2 and increased hydraulic conductivity as H2 gas dissolves, which could be represented using traditional relative permeability expressions. Additional experiments were performed in the flow cell to compare H2 gas exsolving from nzvi and NaBH4 solutions injected as either a point injection or a well injection. The results indicated greater amounts of H2 gas produced when injecting nzvi solutions prepared with high concentrations of excess NaBH4. H2 gas pooling at the top of the flow cell, and H2 gas trapped near the injection point

A Numerical Study on the Effects of Street‒canyon Aspect‒ratio on Reactive Pollutant Dispersion

NASA Astrophysics Data System (ADS)

Park, S. J.; Kim, J.

2014-12-01

In this study, the effects of street‒canyon aspect‒ratio on reactive pollutant dispersion were investigated using the coupled CFD‒chemistry model. For this, flow characteristics were analyzed first in street canyons with different aspect ratios and flow regimes were classified according to the building height. For each flow regime, dispersion characteristics were investigated in views of reactive pollutant concentration and VOCs‒NOX ratio. Finally, the relations between pollutant concentration and aspect ratio in urban street canyons were investigated. In the case of H/S = 1.0 (H is building height and S is street width), one clockwise‒rotating vortex appeared vertically and the reverse and outward flows were dominant near the street bottom. In the case of H/S = 2.0, two counter‒rotating vortices appeared vertically in the street canyon. The primary (secondary) vortex rotating clockwise (counterclockwise) was formed in upper (lower) layer. The flow patterns affected the reactive pollutant concentration in street canyons. As building height increased, mean concentration of NO decreased when one vortex was generated in street canyons and increased when two vortexes appeared in street canyons. O3 concentration showed almost contrasted tendency with those of NO because O3 was depleted by the NO titration.

Characterization of Whole Porewater Dissolved Organic Matter by 1H NMR

NASA Astrophysics Data System (ADS)

Fox, C.; Lewicki, J. P.; Abdulla, H. A.; Burdige, D.; Magen, C.; Chanton, J.; Komada, T.

2014-12-01

Dissolved organic matter (DOM) is a key intermediate in microbial remineralization of organic matter, but only a small percentage of this complex pool has been fully characterized. We present the results of a novel approach to the characterization of DOM in whole porewater samples from the anoxic sediments of the Santa Barbara Basin, California Borderland, using solution state nuclear magnetic resonance (NMR) techniques. Profiles of porewater DOM were obtained by 1H NMR from 95 to 435 cm sediment depth. 1H NMR spectra of each whole porewater sample showed continuous, broad regions from ~0.5 to ~4.5 ppm, indicative of significant signal overlap inherent to complex mixtures, superimposed on a few highly resolved peaks. The individual samples consist of a broad range of chemical environments with varying relative abundances that show a near linear trend with depth. The normalized spectral data were analyzed by principal component analysis to resolve variations in chemical composition of DOM as a function of depth. In addition to detecting the major components such as carbohydrates, cyclic aliphatics and aromatics, our results demonstrate a negative correlation between carbohydrates concurrent with a relative increase in levels of aliphatics. Furthermore, we have identified a decrease in the abundance of alkenes coupled with an increase in a broad region from ~1.9 to ~3.2 ppm, likely corresponding to signals from carboxylic-rich alicyclic molecules. In both trends, the greatest variation occurs between 115 and 135 cm, which straddles the sulfate-methane transition zone (~125 cm), potentially highlighting a region of relatively high DOM transformation. Our work has also identified thiol species which are thought to be formed by dissolved (inorganic) sulfide incorporation into porewater DOM compounds. The implications of these results with respect to carbon cycling in anaerobic sediments will be discussed.

Pollutant Concentrations in Street Canyons of Different Aspect Ratio with Avenues of Trees for Various Wind Directions

NASA Astrophysics Data System (ADS)

Gromke, Christof; Ruck, Bodo

2012-07-01

This study summarizes the effects of avenues of trees in urban street canyons on traffic pollutant dispersion. We describe various wind-tunnel experiments with different tree-avenue models in combination with variations in street-canyon aspect ratio W/ H (with W the street-canyon width and H the building height) and approaching wind direction. Compared to tree-free street canyons, in general, higher pollutant concentrations are found. Avenues of trees do not suppress canyon vortices, although the air ventilation in canyons is hindered significantly. For a perpendicular wind direction, increases in wall-average and wall-maximum concentrations at the leeward canyon wall and decreases in wall-average concentrations at the windward wall are found. For oblique and perpendicular wind directions, increases at both canyon walls are obtained. The strongest effects of avenues of trees on traffic pollutant dispersion are observed for oblique wind directions for which also the largest concentrations at the canyon walls are found. Thus, the prevailing assumption that attributes the most harmful dispersion conditions to a perpendicular wind direction does not hold for street canyons with avenues of trees. Furthermore, following dimensional analysis, an estimate of the normalized wall-maximum traffic pollutant concentration in street canyons with avenues of trees is derived.

Supersaturation of dissolved H(2) and CO (2) during fermentative hydrogen production with N(2) sparging.

PubMed

Kraemer, Jeremy T; Bagley, David M

2006-09-01

Dissolved H(2) and CO(2) were measured by an improved manual headspace-gas chromatographic method during fermentative H(2) production with N(2) sparging. Sparging increased the yield from 1.3 to 1.8 mol H(2)/mol glucose converted, although H(2) and CO(2) were still supersaturated regardless of sparging. The common assumption that sparging increases the H(2) yield because of lower dissolved H(2) concentrations may be incorrect, because H(2) was not lowered into the range necessary to affect the relevant enzymes. More likely, N(2) sparging decreased the rate of H(2) consumption via lower substrate concentrations.

Origin of Florida Canyon and the role of spring sapping on the formation of submarine box canyons

USGS Publications Warehouse

Paull, Charles K.; Spiess, Fred N.; Curray, Joseph R.; Twichell, David C.

1990-01-01

Florida Canyon, one of a series of major submarine canyons on the southwestern edge of the Florida Platform, was surveyed using GLORIA, SeaBeam, and Deep-Tow technologies, and it was directly observed during three DSRV Alvin dives. Florida Canyon exhibits two distinct morphologies: a broad V-shaped upper canyon and a deeply entrenched, flat-floored, U-shaped lower canyon. The flat- floored lower canyon extends 20 km into the Florida Platform from the abyssal Gulf. The lower canyon ends abruptly at an ∼3 km in diameter semicircular headwall that rises 750 m with a >60° slope angle to the foot of the upper canyon. The sides of the lower canyon are less steep than its headwall and are characterized by straight faces that occur along preferred orientations and indicate a strong joint control. The upper canyon is characterized by a gently sloping, straight V-shaped central valley cut into a broad terrace. The flat floor of the upper canyon continues as terraces along the upper walls of the lower canyon. On the flanks of the upper canyon, there are five >50-m-deep, >0.5-km-wide, closed sink-hole-like depressions which indicate subsurface dissolution within the platform. The origin of the lower canyon is difficult to explain with traditional models of submarine canyon formation by external physical processes. The movement of ground water, probably with high salinities and reduced compounds along regional joints, may have focused the corrosive force of submarine spring sapping at the head of the lower canyon to produce the canyon's present shape.

Water chemistry of surface waters affected by the Fourmile Canyon wildfire, Colorado, 2010-2011

USGS Publications Warehouse

McCleskey, R. Blaine; Writer, Jeffrey H.; Murphy, Sheila F.

2012-01-01

In September 2010, the Fourmile Canyon fire burned about 23 percent of the Fourmile Creek watershed in Boulder County, Colo. Water-quality sampling of Fourmile Creek began within a month after the wildfire to assess its effects on surface-water chemistry. Water samples were collected from five sites along Fourmile Creek (above, within, and below the burned area) monthly during base flow, twice weekly during snowmelt runoff, and at higher frequencies during storm events. Stream discharge was also monitored. Water-quality samples were collected less frequently from an additional 6 sites on Fourmile Creek, from 11 tributaries or other inputs, and from 3 sites along Boulder Creek. The pH, electrical conductivity, temperature, specific ultraviolet absorbance, total suspended solids, and concentrations (dissolved and total) of major cations (calcium, magnesium, sodium, and potassium), anions (chloride, sulfate, alkalinity, fluoride, and bromide), nutrients (nitrate, ammonium, and phosphorus), trace metals (aluminum, arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, iron, mercury, lithium, manganese, molybdenum, nickel, lead, rubidium, antimony, selenium, strontium, vanadium, and zinc), and dissolved organic carbon are here reported for 436 samples collected during 2010 and 2011.

Modeling Closed Equilibrium Systems of H2O-Dissolved CO2-Solid CaCO3.

PubMed

Tenno, Toomas; Uiga, Kalev; Mashirin, Alexsey; Zekker, Ivar; Rikmann, Ergo

2017-04-27

In many places in the world, including North Estonia, the bedrock is limestone, which consists mainly of CaCO 3 . Equilibrium processes in water involving dissolved CO 2 and solid CaCO 3 play a vital role in many biological and technological systems. The solubility of CaCO 3 in water is relatively low. Depending on the concentration of dissolved CO 2 , the solubility of CaCO 3 changes, which determines several important ground- and wastewater parameters, for example, Ca 2+ concentration and pH. The distribution of ions and molecules in the closed system solid H 2 O-dissolved CO 2 -solid CaCO 3 is described in terms of a structural scheme. Mathematical models were developed for the calculation of pH and concentrations of ions and molecules (Ca 2+ , CO 3 2- , HCO 3 - , H 2 CO 3 , CO 2 , H + , and OH - ) in the closed equilibrium system at different initial concentrations of CO 2 in the water phase using an iteration method. The developed models were then experimentally validated.

Electrolytic dissolver

DOEpatents

Wheelwright, E.J.; Fox, R.D.

1975-08-26

This patent related to an electrolytic dissolver wherein dissolution occurs by solution contact including a vessel of electrically insulative material, a fixed first electrode, a movable second electrode, means for insulating the electrodes from the material to be dissolved while permitting a free flow of electrolyte therebetween, means for passing a direct current between the electrodes and means for circulating electrolyte through the dissolver. (auth)

The 2.5-dimensional equivalent sources method for directly exposed and shielded urban canyons.

PubMed

Hornikx, Maarten; Forssén, Jens

2007-11-01

When a domain in outdoor acoustics is invariant in one direction, an inverse Fourier transform can be used to transform solutions of the two-dimensional Helmholtz equation to a solution of the three-dimensional Helmholtz equation for arbitrary source and observer positions, thereby reducing the computational costs. This previously published approach [D. Duhamel, J. Sound Vib. 197, 547-571 (1996)] is called a 2.5-dimensional method and has here been extended to the urban geometry of parallel canyons, thereby using the equivalent sources method to generate the two-dimensional solutions. No atmospheric effects are considered. To keep the error arising from the transform small, two-dimensional solutions with a very fine frequency resolution are necessary due to the multiple reflections in the canyons. Using the transform, the solution for an incoherent line source can be obtained much more efficiently than by using the three-dimensional solution. It is shown that the use of a coherent line source for shielded urban canyon observer positions leads mostly to an overprediction of levels and can yield erroneous results for noise abatement schemes. Moreover, the importance of multiple facade reflections in shielded urban areas is emphasized by vehicle pass-by calculations, where cases with absorptive and diffusive surfaces have been modeled.

Interim Report: Field Demonstration Of Permeable Reactive Barriers To Remove Dissolved Uranium From Groundwater, Fry Canyon, Utah

EPA Pesticide Factsheets

The Fry Canyon site in southeastern Utah was selected in 1996 as a long-term field demonstration site to assess the performance of selected permeable reactive barriers for the removal of uranium (U) from groundwater.

Fluid mechanical dispersion of airborne pollutants inside urban street canyons subjecting to multi-component ventilation and unstable thermal stratifications.

PubMed

Mei, Shuo-Jun; Liu, Cheng-Wei; Liu, Di; Zhao, Fu-Yun; Wang, Han-Qing; Li, Xiao-Hong

2016-09-15

The pedestrian level pollutant transport in street canyons with multiple aspect ratios (H/W) is numerically investigated in the present work, regarding of various unstable thermal stratification scenarios and plain surrounding. Non-isothermal turbulent wind flow, temperature field and pollutant spread within and above the street canyons are solved by the realizable k-ε turbulence model along with the enhanced wall treatment. One-vortex flow regime is observed for shallow canyons with H/W=0.5, whereas multi-vortex flow regime is observed for deep canyons with H/W=2.0. Both one-vortex and multi-vortex regimes could be observed for the street canyons with H/W=1.0, where the secondary vortex could be initiated by the flow separation and intensified by unstable thermal stratification. Air exchange rate (AER) and pollutant retention time are adopted to respectively evaluate the street canyon ventilation and pollutant removal performance. A second-order polynomial functional relationship is established between AER and Richardson number (Ri). Similar functional relationship could be established between retention time and Ri, and it is only valid for canyons with one-vortex flow regime. In addition, retention time could be prolonged abruptly for canyons with multi-vortex flow regime. Very weak secondary vortex is presented at the ground level of deep canyons with mild stratification, where pollutants are highly accumulated. However, with the decrease of Ri, pollutant concentration adjacent to the ground reduces accordingly. Present research could be applied to guide the urban design and city planning for enhancing pedestrian environment. Copyright © 2016 Elsevier B.V. All rights reserved.

pH-Dependent dissolving nano- and microparticles for improved peroral delivery of a highly lipophilic compound in dogs.

PubMed

De Jaeghere, F; Allémann, E; Cerny, R; Galli, B; Steulet, A F; Müller, I; Schütz, H; Doelker, E; Gurny, R

2001-01-01

RR01, a new highly lipophilic drug showing extremely low water solubility and poor oral bioavailability, has been incorporated into pH-dependent dissolving particles made of a poly(methacrylic acid-co-ethylacrylate) copolymer. The physicochemical properties of the particles were determined using laser-light-scattering techniques, scanning electron microscopy, high-performance liquid chromatography, and x-ray powder diffraction. Suspension of the free drug in a solution of hydroxypropylcellulose (reference formulation) and aqueous dispersions of pH-sensitive RR01-loaded nanoparticles or microparticles were administered orally to Beagle dogs according to a 2-block Latin square design (n = 6). Plasma samples were obtained over the course of 48 hours and analyzed by gas chromatography/mass spectrometry. The administration of the reference formulation resulted in a particularly high interindividual variability of pharmacokinetic parameters, with low exposure to compound RR01 (AUC0-48h of 6.5 microg x h/mL and coefficient of variation (CV) of 116%) and much higher Tmax, as compared to both pH-sensitive formulations. With respect to exposure and interindividual variability, nanoparticles were superior to microparticles (AUC0-48h of 27.1 microg x h/mL versus 17.7 microg x h/mL with CV of 19% and 40%, respectively), indicating that the particle size may play an important role in the absorption of compound RR01. The performance of pH-sensitive particles is attributed to their ability to release the drug selectively in the upper part of the intestine in a molecular or amorphous form. In conclusion, pH-dependent dissolving particles have a great potential as oral delivery systems for drugs with low water solubility and acceptable permeation properties.

Sulfamethazine Sorption to Soil: Vegetative Management, pH, and Dissolved Organic Matter Effects.

PubMed

Chu, Bei; Goyne, Keith W; Anderson, Stephen H; Lin, Chung-Ho; Lerch, Robert N

2013-01-01

Elucidating veterinary antibiotic interactions with soil is important for assessing and mitigating possible environmental hazards. The objectives of this study were to investigate the effects of vegetative management, soil properties, and >1000 Da dissolved organic matter (DOM) on sulfamethazine (SMZ) behavior in soil. Sorption experiments were performed over a range of SMZ concentrations (2.5-50 μmol L) using samples from three soils (Armstrong, Huntington, and Menfro), each planted to one of three vegetation treatments: agroforestry buffers strips (ABS), grass buffer strips (GBS), and row crops (RC). Our results show that SMZ sorption isotherms are well fitted by the Freundlich isotherm model (log = 0.44-0.93; Freundlich nonlinearity parameter = 0.59-0.79). Further investigation of solid-to-solution distribution coefficients () demonstrated that vegetative management significantly ( < 0.05) influences SMZ sorption (ABS > GBS > RC). Multiple linear regression analyses indicated that organic carbon (OC) content, pH, and initial SMZ concentration were important properties controlling SMZ sorption. Study of the two most contrasting soils in our sample set revealed that increasing solution pH (pH 6.0-7.5) reduced SMZ sorption to the Armstrong GBS soil, but little pH effect was observed for the Huntington GBS soil containing 50% kaolinite in the clay fraction. The presence of DOM (150 mg L OC) had little significant effect on the Freundlich nonlinearity parameter; however, DOM slightly reduced SMZ values overall. Our results support the use of vegetative buffers to mitigate veterinary antibiotic loss from agroecosystems, provide guidance for properly managing vegetative buffer strips to increase SMZ sorption, and enhance understanding of SMZ sorption to soil. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Geomorphic process fingerprints in submarine canyons

USGS Publications Warehouse

Brothers, Daniel S.; ten Brink, Uri S.; Andrews, Brian D.; Chaytor, Jason D.; Twichell, David C.

2013-01-01

Submarine canyons are common features of continental margins worldwide. They are conduits that funnel vast quantities of sediment from the continents to the deep sea. Though it is known that submarine canyons form primarily from erosion induced by submarine sediment flows, we currently lack quantitative, empirically based expressions that describe the morphology of submarine canyon networks. Multibeam bathymetry data along the entire passive US Atlantic margin (USAM) and along the active central California margin near Monterey Bay provide an opportunity to examine the fine-scale morphology of 171 slope-sourced canyons. Log–log regression analyses of canyon thalweg gradient (S) versus up-canyon catchment area (A) are used to examine linkages between morphological domains and the generation and evolution of submarine sediment flows. For example, canyon reaches of the upper continental slope are characterized by steep, linear and/or convex longitudinal profiles, whereas reaches farther down canyon have distinctly concave longitudinal profiles. The transition between these geomorphic domains is inferred to represent the downslope transformation of debris flows into erosive, canyon-flushing turbidity flows. Over geologic timescales this process appears to leave behind a predictable geomorphic fingerprint that is dependent on the catchment area of the canyon head. Catchment area, in turn, may be a proxy for the volume of sediment released during geomorphically significant failures along the upper continental slope. Focused studies of slope-sourced submarine canyons may provide new insights into the relationships between fine-scale canyon morphology and down-canyon changes in sediment flow dynamics.

Impacts of shape and height of upstream roof on airflow and pollutant dispersion inside an urban street canyon.

PubMed

Huang, Yuan-Dong; He, Wen-Rong; Kim, Chang-Nyung

2015-02-01

A two-dimensional numerical model for simulating flow and pollutant dispersion in an urban street canyon is firstly developed using the FLUENT code and then validated against the wind tunnel results. After this, the flow field and pollutant dispersion inside an urban street canyon with aspect ratio W/H = 1 are examined numerically considering five different shapes (vaulted, trapezoidal, slanted, upward wedged, and downward wedged roofs) as well as three different roof height to building height ratios (Z H /H = 1/6, 1/3, and 1/2) for the upstream building roof. The results obtained reveal that the shape and height of an upstream roof have significant influences on flow pattern and pollutant distribution in an urban canyon. A large single clockwise vortex is generated in the canyon for the vaulted upstream roof at Z H /H = 1/6, 1/3, and 1/2, the trapezoidal and downward wedged roofs at Z H /H = 1/6 and 1/3, and the slanted and upward wedged roofs at Z H /H = 1/6, while a main clockwise vortex and a secondary counterclockwise vortex are established for the trapezoidal and downward wedged roofs at Z H /H = 1/2 and the slanted and upward wedged roofs at Z H /H = 1/3 and 1/2. In the one-vortex flow regime, the clockwise vortex moves upward and grows in size with increasing upstream roof height for the vaulted, trapezoidal, and downward wedged roofs. In the two-vortex flow regime, the size and rotational velocity of both upper clockwise and lower counterclockwise vortices increase with the upstream roof height for the slanted and upward wedged roofs. At Z H /H = 1/6, the pollution levels in the canyon are close among all the upstream roof shapes studied. At Z H /H = 1/3, the pollution levels in the canyon for the upward wedged roof and slanted roof are much higher than those for the vaulted, trapezoidal, and downward wedged roofs. At Z H /H = 1/2, the lowest pollution level appears in the canyon for the vaulted upstream roof, while

Photoproduction of hydrogen peroxide in aqueous solution from model compounds for chromophoric dissolved organic matter (CDOM).

PubMed

Clark, Catherine D; de Bruyn, Warren; Jones, Joshua G

2014-02-15

To explore whether quinone moieties are important in chromophoric dissolved organic matter (CDOM) photochemistry in natural waters, hydrogen peroxide (H2O2) production and associated optical property changes were measured in aqueous solutions irradiated with a Xenon lamp for CDOM model compounds (dihydroquinone, benzoquinone, anthraquinone, napthoquinone, ubiquinone, humic acid HA, fulvic acid FA). All compounds produced H2O2 with concentrations ranging from 15 to 500 μM. Production rates were higher for HA vs. FA (1.32 vs. 0.176 mM h(-1)); values ranged from 6.99 to 0.137 mM h(-1) for quinones. Apparent quantum yields (Θ app; measure of photochemical production efficiency) were higher for HA vs. FA (0.113 vs. 0.016) and ranged from 0.0018 to 0.083 for quinones. Dihydroquinone, the reduced form of benzoquinone, had a higher production rate and efficiency than its oxidized form. Post-irradiation, quinone compounds had absorption spectra similar to HA and FA and 3D-excitation-emission matrix fluorescence spectra (EEMs) with fluorescent peaks in regions associated with CDOM. Copyright © 2014 Elsevier Ltd. All rights reserved.

Release kinetics of vanadium from vanadium titano-magnetite: The effects of pH, dissolved oxygen, temperature and foreign ions.

PubMed

Hu, Xingyun; Yue, Yuyan; Peng, Xianjia

2018-02-01

As part of a broader study of the environmental geochemistry behavior of vanadium (V), the release kinetics of V from the dissolution of natural vanadium titano-magnetite under environmentally relevant conditions was investigated. In both the acidic and basic domains, the V release rate was found to be proportional to fractional powers of hydrogen ion and dissolved oxygen activities. The dependence of the rate on dissolved oxygen can also be described in terms of the Langmuir adsorption model. The empirical rate equation is given by: r [Formula: see text] where, α=0.099-0.265, k'=3.2×10 -6 -1.7×10 -5 , K=2.7×10 4 -3.9×10 4 mol/L in acid solution (pH4.1), and α=-0.494-(-0.527), k'=2.0×10 4 -2.5×10 -11 , and K=4.1×10 3 -6.5×10 3 mol/L in basic solution (pH8.8) at 20°C. Based on the effect of temperature on the release rate of V, the activation energies of minerals at pH8.8 were determined to be 148-235kJ/mol, suggesting that the dissolution of vanadium titano-magnetite is a surface-controlled process. The presence of Na + , Ca 2+ , Mg 2+ , K + , NO 3 - , Cl - , SO 4 2- and CO 3 2- was found to accelerate the V release rates. This study improves the understanding of both the V pollution risk in some mine areas and the fate of V in the environment. Copyright © 2017. Published by Elsevier B.V.

1. 'SANTA ANA RIVER IN SANTA ANA CANYON. ORANGE COUNTY.' ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. 'SANTA ANA RIVER IN SANTA ANA CANYON. ORANGE COUNTY.' This is an oblique aerial view to the northeast taken from the northeast extremity of the canyon, showing, in the middle distance, the confluence of Chino Creek and the Santa Ana River, site of the future Prado Dam. File number written on negative: R & H 80 026. - Prado Dam, Santa Ana River near junction of State Highways 71 & 91, Corona, Riverside County, CA

[Effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter in soil solution in a young Cunninghamia lanceolata plantation.

PubMed

Yuan, Xiao Chun; Chen, Yue Min; Yuan, Shuo; Zheng, Wei; Si, You Tao; Yuan, Zhi Peng; Lin, Wei Sheng; Yang, Yu Sheng

2017-01-01

To study the effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter (DOM) in the forest soil solution from the subtropical Cunninghamia lanceolata plantation, using negative pressure sampling method, the dynamics of DOM in soil solutions from 0-15 and 15-30 cm soil layer was monitored for two years and the spectroscopic features of DOM were analyzed. The results showed that nitrogen deposition significantly reduced the concentration of dissolved organic carbon (DOC), and increased the aromatic index (AI) and the humic index (HIX), but had no significant effect on dissolved organic nitrogen (DON) concentration in both soil layers. There was obvious seasonal variation in DOM concentration of the soil solution, which was prominently higher in summer and autumn than in spring and winter.Fourier-transform infrared (FTIR) absorption spectrometry indicated that the DOM in forest soil solution had absorption peaks in the similar position of six regions, being the highest in wave number of 1145-1149 cm -1 . Three-dimensional fluorescence spectra indicated that DOM was mainly consisted of protein-like substances (Ex/Em=230 nm/300 nm) and microbial degradation products (Ex/Em=275 nm/300 nm). The availability of protein-like substances from 0-15 cm soil layer was reduced in the nitrogen treatments. Nitrogen deposition significantly reduced the concentration of DOC in soil solution, maybe largely by reducing soil pH, inhibiting soil carbon mineralization and stimulating plant growth. In particular, the decline of DOC concentration in the surface layer was due to the production inhibition of the protein-like substances and carboxylic acids. Short-term nitrogen deposition might be beneficial to the maintenance of soil fertility, while the long-term accumulation of nitrogen deposition might lead to the hard utilization of soil nutrients.

24. VIEW OF CANYON TAKEN FROM NORTH CANYON RIM AROUND ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

24. VIEW OF CANYON TAKEN FROM NORTH CANYON RIM AROUND 1920. CAMERA FACES SOUTH. VILLAGE IS TREE-COVERED AREA TO LEFT OF DAM AND POWERHOUSE. SUPERINTENDENT SAM GLASS'S ORCHARD IS DOWNSTREAM OF DAM ABOUT A QUARTER OF A MILE. - Swan Falls Village, Snake River, Kuna, Ada County, ID

pH : a key control of the nature and distribution of dissolved organic matter and associated trace metals in soil

NASA Astrophysics Data System (ADS)

Pédrot, M.; Dia, A.; Davranche, M.

2009-04-01

Dissolved organic matter is ubiquitous at the Earth's surface and plays a prominent role in controlling metal speciation and mobility from soils to hydrosystems. Humic substances (HS) are usually considered to be the most reactive fraction of organic matter. Humic substances are relatively small and formed by chemically diverse organic molecules, bearing different functional groups that act as binding sites for cations and mineral surfaces. Among the different environmental physicochemical parameters controlling the metal speciation, pH is likely to be the most important one. Indeed, pH affect the dissociation of functional groups, and thus can influence the HS structure, their ability to complex metals, their solubility degree allowing the formation of aggregates at the mineral surface. In this context, soil/water interactions conducted through batch system experiments, were carried out with a wetland organic-rich soil to investigate the effect of pH on the release of dissolved organic carbon (DOC) and associated trace elements. The pH was regulated between 4 and 7.5 using an automatic pH stat titrator. Ultrafiltration experiments were performed to separate the dissolved organic pool following decreasing pore sizes (30 kDa, 5 kDa and 2 kDa with 1 Da = 1 g.mol-1). The pH increase induced a significant DOC release, especially in heavy organic molecules (size >5 kDa) with a high aromaticity (>30 %). These were probably humic acids (HA). This HA release influenced (i) directly the trace element concentrations in soil solution since HA were enriched in several trace elements such as Th, REE, Y, U, Cr and Cu; and (ii) indirectly by the breaking of clay-humic complexes releasing Fe- and Al-rich nanoparticles associated with V, Pb and Ti. By contrast, at acid pH, most HS were complexed onto mineral surfaces. They also sequestered iron nanoparticles. Therefore, at low pH, most part of DOC molecules had a size < 5 kDa and lower aromaticity. Thus, the DOC was mostly composed

Westernmost Grand Canyon incision: Testing thermochronometric resolution

NASA Astrophysics Data System (ADS)

Fox, M.; Tripathy-Lang, A.; Shuster, D. L.; Winn, C.; Karlstrom, K.; Kelley, S.

2017-09-01

The timing of carving of Grand Canyon has been debated for over 100 years with competing endmember hypotheses advocating for either a 70 Ma ("old") or <6 Ma ("young") Grand Canyon. Several geological constraints appear to support a "young" canyon model, but thermochronometric measures of cooling history and corresponding estimates of landscape evolution have been in debate. In particular, 4He/3He thermochronometric data record the distribution of radiogenic 4He (from the 238U, 235U and 232Th decay series) within an individual apatite crystal and thus are highly sensitive to the thermal history corresponding to landscape evolution. However, there are several complicating factors that make interpreting such data challenging in geologic scenarios involving reheating. Here, we analyze new data that provide measures of the cooling of basement rocks at the base of westernmost Grand Canyon, and use these data as a testbed for exploring the resolving power and limitations of 4He/3He data in general. We explore a range of thermal histories and find that these data are most consistent with a "young" Grand Canyon. A problem with the recovered thermal history, however, is that burial temperatures are under predicted based on sedimentological evidence. A solution to this problem is to increase the resistance of alpha recoil damage to annealing, thus modifying He diffusion kinetics, allowing for higher temperatures throughout the thermal history. This limitation in quantifying radiation damage (and hence crystal retentivity) introduces non-uniqueness to interpreting time-temperature paths in rocks that resided in the apatite helium partial retention zone for long durations. Another source of non-uniqueness, is due to unknown U and Th distributions within crystals. We show that for highly zoned with a decrease in effective U of 20 ppm over the outer 80% of the radius of the crystal, the 4He/3He data could be consistent with an "old" canyon model. To reduce this non-uniqueness, we

The effects of salinity, pH, and dissolved organic matter on acute copper toxicity to the rotifer, Brachionus plicatilis ("L" strain).

PubMed

Arnold, W R; Diamond, R L; Smith, D S

2010-08-01

This paper presents data from original research for use in the development of a marine biotic ligand model and, ultimately, copper criteria for the protection of estuarine and marine organisms and their uses. Ten 48-h static acute (unfed) copper toxicity tests using the euryhaline rotifer Brachionus plicatilis ("L" strain) were performed to assess the effects of salinity, pH, and dissolved organic matter (measured as dissolved organic carbon; DOC) on median lethal dissolved copper concentrations (LC50). Reconstituted and natural saltwater samples were tested at seven salinities (6, 11, 13, 15, 20, 24, and 29 g/L), over a pH range of 6.8-8.6 and a range of dissolved organic carbon of <0.5-4.1 mg C/L. Water chemistry analyses (alkalinity, calcium, chloride, DOC, hardness, magnesium, potassium, sodium, salinity, and temperature) are presented for input parameters to the biotic ligand model. In stepwise multiple regression analysis of experimental results where salinity, pH, and DOC concentrations varied, copper toxicity was significantly related only to the dissolved organic matter content (pH and salinity not statistically retained; alpha=0.05). The relationship of the 48-h dissolved copper LC50 values and dissolved organic carbon concentrations was LC50 (microg Cu/L)=27.1xDOC (mg C/L)1.25; r2=0.94.

Surface Complexation Modeling of Fluoride Adsorption by Soil and the Role of Dissolved Aluminum on Adsorption

NASA Astrophysics Data System (ADS)

Padhi, S.; Tokunaga, T.

2017-12-01

Adsorption of fluoride (F) on soil can control the mobility of F and subsequent contamination of groundwater. Hence, accurate evaluation of adsorption equilibrium is a prerequisite for understanding transport and fate of F in the subsurface. While there have been studies for the adsorption behavior of F with respect to single mineral constituents based on surface complexation models (SCM), F adsorption to natural soil in the presence of complexing agents needs much investigation. We evaluated the adsorption processes of F on a natural granitic soil from Tsukuba, Japan, as a function of initial F concentration, ionic strength, and initial pH. A SCM was developed to model F adsorption behavior. Four possible surface complexation reactions were postulated with and without including dissolved aluminum (Al) and Al-F complex sorption. Decrease in F adsorption with the increase in initial pH was observed in between the initial pH range of 4 to 9, and a decrease in the rate of the reduction of adsorbed F with respect to the increase in the initial pH was observed in the initial pH range of 5 to 7. Ionic strength variation in the range of 0 to 100mM had insignificant effect on F removal. Changes in solution pH were observed by comparing the solution before and after F adsorption experiments. At acidic pH, the solution pH increased, whereas at alkaline pH, the solution pH decreased after equilibrium. The SCM including dissolved Al and the adsorption of Al-F complex can simulate the experimental results quite successfully. Also, including dissolved Al and the adsorption of Al-F complex to the model explained the change in solution pH after F adsorption.

The effect of iron content and dissolved O2 on dissolution rates of clinopyroxene at pH 5.8 and 25°C: Preliminary results

USGS Publications Warehouse

Hoch, A.R.; Reddy, M.M.; Drever, J.I.

1996-01-01

Dissolution experiments using augite (Mg0.87Ca0.85Fe0.19Na0.09Al0.03Si2O6) and diopside (Mg0.91Ca0.93Fe0.07Na0.03Al0.03Si2O6) were conducted in flow-through reactors (5-ml/h flow rate). A pH of 5.8 was maintained by bubbling pure CO2 through a solution of 0.01 M KHCO3 at 25°C. Two experiments were run for each pyroxene type. In one experiment dissolved O2 concentration in reactors was 0.6 (±0.1) ppm and in the second dissolved O2 was 1.5 (±0.1) ppm. After 60 days, augite dissolution rates (based on Si release) were approximately three times greater in the 1.5 ppm. dissolved O2 experiments than in the sealed experiments. In contrast, diopside dissolution rates were independent of dissolved O2 concentrations. Preliminary results from the augite experiments suggest that dissolution rate is directly related to oxidation of iron. This effect was not observed in experiments performed on iron-poor diopside. Additionally, dissolution rates of diopside were much slower than those of augite, again suggesting a relationship between Fe content, Fe oxidation and dissolution rates.

In situ measurements of dissolved oxygen, pH and redox potential of biocathode microenvironments using microelectrodes.

PubMed

Wang, Zejie; Deng, Huan; Chen, Lihui; Xiao, Yong; Zhao, Feng

2013-03-01

Biofilms are the core component of bioelectrochemical systems (BESs). To understand the polarization effects on biocathode performance of BES, dissolved oxygen concentrations, pHs and oxidation-reduction potentials of biofilm microenvironments were determined in situ. The results showed that lower polarization potentials resulted in the generation of larger currents and higher pH values, as well as the consumption of more oxygen. Oxidation-reduction potentials of biofilms were mainly affected by polarization potentials of the electrode rather than the concentration of dissolved oxygen or pH value, and its changes in the potentials corresponded to the electric field distribution of the electrode surface. The results demonstrated that a sufficient supply of dissolved oxygen and pH control of the biocathode are necessary to obtain optimal performance of BESs; a lower polarization potential endowed microorganisms with a higher electrochemical activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

Analysis of In-Canyon Flow Characterisitcs in step-up street canyons

NASA Astrophysics Data System (ADS)

PARK, S.; Kim, J.; Choi, W.; Pardyjak, E.

2017-12-01

Flow characteristics in strep-up street canyons were investigated focusing on in-canyon region. To see the effects of the building geometry, two building height ratios [ratio of the upwind (Hu) to downwind building heights (Hd) = 0.33, 0.6] were considered and eight building length ratios [ratio of the cross-wind building length (L) to street-canyon width (S) from 0.5 to 4 with the increment of 0.5] were systematically changed. For the model validation, the simulated results were compared with the wind- tunnel data measured for Hu/Hd = 0.33, 0.6 and L/S = 1, 2, 3, and 4. In the CFD model simulations, the corner vortices at the downwind side near the ground level and the recirculation zones above the downwind buildings had the relatively small extents, compared with those in the wind-tunnel experiments. However, the CFD model reproduced the main flow features such as the street-canyon vortices, circulations above the building roof, and the positions of the stagnation points on the downwind building walls in the wind-tunnel experiments reasonably well. By further analyzing the three-dimensional flow structures based on the numerical results simulated in the step-up street canyons, we schematically suggested the flow characteristics with different building-height and building-length ratios.

Carbon transport in Monterey Submarine Canyon

NASA Astrophysics Data System (ADS)

Barry, J.; Paull, C. K.; Xu, J. P.; Clare, M. A.; Gales, J. A.; Buck, K. R.; Lovera, C.; Gwiazda, R.; Maier, K. L.; McGann, M.; Parsons, D. R.; Simmons, S.; Rosenberger, K. J.; Talling, P. J.

2017-12-01

Submarine canyons are important conduits for sediment transport from continental margins to the abyss, but the rate, volume, and time scales of material transport have been measured only rarely. Using moorings with current meters, sediment traps (10 m above bottom) and optical backscatter sensors, we measured near-bottom currents, suspended sediment concentrations, and sediment properties at 1300 m depth in Monterey Canyon and at a non-canyon location on the continental slope at the same depth. Flow and water column backscatter were used to characterize "ambient" conditions when tidal currents dominated the flow field, and occasional "sediment transport events" when anomalously high down-canyon flow with sediment-laden waters arrived at the canyon mooring. The ambient sediment flux measured in sediment traps in Monterey Canyon was 350 times greater than measured at the non-canyon location. Although the organic carbon content of the canyon sediment flux during ambient periods was low (1.8 %C) compared to the slope location (4.9 %C), the ambient carbon transport in the canyon was 130 times greater than at the non-canyon site. Material fluxes during sediment transport events were difficult to measure owing to clogging of sediment traps, but minimal estimates indicate that mass transport during events exceeds ambient sediment fluxes through the canyon by nearly 3 orders of magnitude, while carbon transport is 380 times greater. Estimates of the instantaneous and cumulative flux of sediment and carbon from currents, backscatter, and sediment properties indicated that: 1) net flux is down-canyon, 2) flux is dominated by sediment transport events, and 3) organic carbon flux through 1300 m in Monterey Canyon was ca. 1500 MT C per year. The injection of 1500 MTCy-1 into the deep-sea represents ca. 260 km2 of the sediment C flux measured at the continental slope station (5.8 gCm-2y-1) and is sufficient to support a benthic community carbon demand of 5 gCm-2y-1 over 300 km2.

Strategic guidelines for street canyon geometry to achieve sustainable street air quality—part II: multiple canopies and canyons

NASA Astrophysics Data System (ADS)

Chan, Andy T.; Au, William T. W.; So, Ellen S. P.

The flow field and pollutant dispersion characteristics in a three-dimensional urban street canyon are investigated for various building array geometries. The street canyon in consideration is located in a multi-canopy building array that is similar to realistic estate situations. The pollutant dispersion characteristics are studied for various canopy aspect ratios, namely: the canyon height to width ratio, canyon length to height ratio, canyon breadth ratio and crossroad locations are studied. A three-dimensional field-size canyon has been analysed through numerical simulations using k- ɛ turbulence model. As expected, the wind flow and mode of pollutant dispersion is strongly dependent on the various flow geometric configurations and that the results can be different from that of a single canyon system. For example, it is found that the pollutant retention value is minimum when the canyon height-to-width ratio is approximately 0.8, or that the building height ratio is 0.5. Various rules of thumbs on urban canyon geometry have been established for good pollutant dispersion.

Experimental simulation of air quality in street canyon under changes of building orientation and aspect ratio.

PubMed

Yassin, Mohamed F; Ohba, Masaake

2012-09-01

To assist validation of numerical simulations of urban pollution, air quality in a street canyon was investigated using a wind tunnel as a research tool under neutral atmospheric conditions. We used tracer gas techniques from a line source without buoyancy. Ethylene (C(2)H(4)) was used as the tracer gas. The street canyon model was formed of six parallel building rows of the same length. The flow and dispersion field was analyzed and measured using a hot-wire anemometer with split fiber probe and fast flame ionization detector. The diffusion flow field in the boundary layer within the street canyon was examined at different locations, with varying building orientations (θ=90°, 112.5°, 135° and 157.5°) and street canyon aspect ratios (W/H=1/2, 3/4 and 1) downwind of the leeward side of the street canyon model. Results show that velocity increases with aspect ratio, and with θ>90°. Pollutant concentration increases as aspect ratio decreases. This concentration decreases exponentially in the vertical direction, and decreases as θ increases from 90°. Measured pollutant concentration distributions indicate that variability of building orientation and aspect ratio in the street canyon are important for estimating air quality in the canyon. The data presented here can be used as a comprehensive database for validation of numerical models.

Ecological Functioning in Two Mid-Atlantic Bight Submarine Canyons: Macrofauna Community Trends and the Role of Canyon Specific Processes

NASA Astrophysics Data System (ADS)

Robertson, C.; Bourque, J. R.; Davies, A. J.; Duineveld, G.; Mienis, F.; Brooke, S.; Ross, S. W.; Demopoulos, A. W.

2016-02-01

Submarine canyons are complex systems, acting as major conduits of organic matter along continental shelves and promoting gradients in food resources, turbidity flows, habitat heterogeneity, and areas of sediment resuspension and deposition. In the western North Atlantic, a large multidisciplinary program was conducted in two major Mid-Atlantic Bight (MAB) canyons (Baltimore and Norfolk canyons). This Atlantic Deepwater Canyons project was funded by BOEM, NOAA, and USGS. Here we investigate the `canyon effect' on benthic ecosystem ecology and functioning of two canyon systems by defining canyon specific processes influencing MAB shelf benthic community trends. Sediment cores were collected in 2012 and 2013 with a NIOZ box corer along the main axes ( 180-1200m) of Baltimore and Norfolk Canyon and at comparable depths on the adjacent continental slope. Whole community macrofaunal (>300 μm) abundance and biomass data provided insight into community trends across depth and biogeochemical gradients by coupling diversity metrics and biological trait analyses with sediment biogeochemistry and hydrodynamic data. The canyons exhibited clear differences in sediment profiles, hydrodynamic regimes and enrichment depocenters as well as significantly distinct infauna communities. Interestingly, both canyons showed bimodal distributions in abundances and diversity of infauna and a shallowing of species maxima which was not present on adjacent slopes. We hypothesize that physical canyon processes are important regulators in the depth of observed species maxima and community functioning on the MAB shelf, on local and regional scales. Unique sediment dynamics, organic enrichment, and hydrographic conditions were significant factors in structuring benthic community differences in MAB canyons The study provides a complete benthic infaunal appraisal of two canyon systems in the western Atlantic, incorporating biogeochemistry and oceanography to increase our understanding of canyon

Formative flow in bedrock canyons

NASA Astrophysics Data System (ADS)

Venditti, J. G.; Kwoll, E.; Rennie, C. D.; Church, M. A.

2017-12-01

In alluvial channels, it is widely accepted that river channel configuration is set by a formative flow that represents a balance between the magnitude and frequency of flood flows. The formative flow is often considered to be one that is just capable of filling a river channel to the top of its banks. Flows much above this formative flow are thought to cause substantial sediment transport and rearrange the channel morphology to accommodate the larger flow. This idea has recently been extended to semi-alluvial channels where it has been shown that even with bedrock exposed, the flows rarely exceed that required to entrain the local sediment cover. What constitutes a formative flow in a bedrock canyon is not clear. By definition, canyons have rock walls and are typically incised vertically, removing the possibility of the walls being overtopped, as can occur in an alluvial channel at high flows. Canyons are laterally constrained, have deep scour pools and often have width to maximum depth ratios approaching 1, an order of magnitude lower than alluvial channels. In many canyons, there are a sequence of irregularly spaced scour pools. The bed may have intermittent or seasonal sediment cover, but during flood flows the sediment bed is entrained leaving a bare bedrock channel. It has been suggested that canyons cut into weak, well-jointed rock may adjust their morphology to the threshold for block plucking because the rock bed is labile during exceptionally large magnitude flows. However, this hypothesis does not apply to canyons cut into massive crystalline rock where abrasion is the dominant erosion process. Here, we argue that bedrock canyon morphology is adjusted to a characteristic flow structure developed in bedrock canyons. We show that the deeply scoured canyon floor is adjusted to a velocity inversion that is present at low flows, but gets stronger at high flows. The effect is to increase boundary shear stresses along the scour pool that forms in constricted

Let's Bet on Sediments! Hudson Canyon Cruise--Grades 9-12. Focus: Sediments of Hudson Canyon.

ERIC Educational Resources Information Center

National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

These activities are designed to teach about the sediments of Hudson Canyon. Students investigate and analyze the patterns of sedimentation in the Hudson Canyon, observe how heavier particles sink faster than finer particles, and learn that submarine landslides are avalanches of sediment in deep ocean canyons. The activity provides learning…

Transport and fluxes of terrestrial polycyclic aromatic hydrocarbons in a small mountain river and submarine canyon system.

PubMed

Lin, Bing-Sian; Lee, Chon-Lin; Brimblecombe, Peter; Liu, James T

2016-08-01

Polycyclic aromatic hydrocarbon (PAH) concentrations in the Gaoping River were investigated in the wet and dry seasons. PAH characteristics allowed us to trace the particulate matter transported in a river-sea system containing a small mountain river, continental shelf, and submarine canyon. PAH signatures of the Gaoping River showed that particles were rapidly transported from the high mountain to the Gaoping coastal areas in the wet season, even arriving at the deep ocean via the Gaoping Submarine Canyon. By contrast, in the dry season, the particles were delivered quite slowly and included mostly pyrogenic contaminants. The annual riverine flux estimates for PAHs were 2241 kg in the Gaoping river-sea system. Only 18.0 kg were associated with the dissolved phase; the rest was bound onto particles. The fluxes caused by typhoons and their effects accounted for 20.2% of the dissolved and 68.4% of the particulate PAH fluxes from the river. Normalized partition coefficients for organic carbon suggested that PAHs were rigid on the particles. Distinct source characteristics were evident for PAHs on riverine suspended particles and coastal surface sediments: the particles in the wet season (as background signals) were similar to petrogenic sources, whereas the particles in the dry season had characteristics of coal burning and vehicular emissions. The sediments in the northwestern shelf were similar to pyrogenic sources (including vehicular emissions and coal and biomass burning), whereas the sediments in the canyon and southeastern shelf arose from mixed sources, although some diesel signature was also evident. Copyright © 2016 Elsevier Ltd. All rights reserved.

Grand Canyon Monitoring and Research Center

USGS Publications Warehouse

Hamill, John F.

2009-01-01

The Grand Canyon of the Colorado River, one of the world's most spectacular gorges, is a premier U.S. National Park and a World Heritage Site. The canyon supports a diverse array of distinctive plants and animals and contains cultural resources significant to the region's Native Americans. About 15 miles upstream of Grand Canyon National Park sits Glen Canyon Dam, completed in 1963, which created Lake Powell. The dam provides hydroelectric power for 200 wholesale customers in six western States, but it has also altered the Colorado River's flow, temperature, and sediment-carrying capacity. Over time this has resulted in beach erosion, invasion and expansion of nonnative species, and losses of native fish. Public concern about the effects of Glen Canyon Dam operations prompted the passage of the Grand Canyon Protection Act of 1992, which directs the Secretary of the Interior to operate the dam 'to protect, mitigate adverse impacts to, and improve values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established...' This legislation also required the creation of a long-term monitoring and research program to provide information that could inform decisions related to dam operations and protection of downstream resources.

DISSOLVED ORGANIC MATTER AND METALS: EFFECTS OF PH ON PARTITIONING

EPA Science Inventory

Eighteen Dutch soils were extracted in aqueous solutions at varying pH. Extracts were analyzed for Cd, Cu, Ni, Pb, and Zn by ICP-AES. Extract dissolved organic carbon (DOC) was fractionated into three operationally defined fractions: hydrophilic acids (Hyd), fulvic acids (FA), an...

Wintertime Boundary Layer Structure in the Grand Canyon.

NASA Astrophysics Data System (ADS)

Whiteman, C. David; Zhong, Shiyuan; Bian, Xindi

1999-08-01

Wintertime temperature profiles in the Grand Canyon exhibit a neutral to isothermal stratification during both daytime and nighttime, with only rare instances of actual temperature inversions. The canyon warms during daytime and cools during nighttime more or less uniformly through the canyon's entire depth. This weak stability and temperature structure evolution differ from other Rocky Mountain valleys, which develop strong nocturnal inversions and exhibit convective and stable boundary layers that grow upward from the valley floor. Mechanisms that may be responsible for the different behavior of the Grand Canyon are discussed, including the possibility that the canyon atmosphere is frequently mixed to near-neutral stratification when cold air drains into the top of the canyon from the nearby snow-covered Kaibab Plateau. Another feature of canyon temperature profiles is the sharp inversions that often form near the canyon rims. These are generally produced when warm air is advected over the canyon in advance of passing synoptic-scale ridges.Wintertime winds in the main canyon are not classical diurnal along-valley wind systems. Rather, they are driven along the canyon axis by the horizontal synoptic-scale pressure gradient that is superimposed along the canyon's axis by passing synoptic-scale weather disturbances. They may thus bring winds into the canyon from either end at any time of day.The implications of the observed canyon boundary layer structure for air pollution dispersion are discussed.

THE BUBBLE STRIPPING METHOD FOR DETERMINING DISSOLVED HYDROGEN (H2) IN WELL WATER

EPA Science Inventory

The Bubble Strip Method was developed for determining concentrations of dissolved H2 in ground water (1). This information canaid in assessing the viability of employing the strategyof monitored natural attenuation (MNA) to restore sites contaminated with chlorinated hydrocarbon...

Investigation Of In-Line Monitoring Options At H Canyon/HB Line For Plutonium Oxide Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sexton, L.

2015-10-14

H Canyon and HB Line have a production goal of 1 MT per year of plutonium oxide feedstock for the MOX facility by FY17 (AFS-2 mission). In order to meet this goal, steps will need to be taken to improve processing efficiency. One concept for achieving this goal is to implement in-line process monitoring at key measurement points within the facilities. In-line monitoring during operations has the potential to increase throughput and efficiency while reducing costs associated with laboratory sample analysis. In the work reported here, we mapped the plutonium oxide process, identified key measurement points, investigated alternate technologies thatmore » could be used for in-line analysis, and initiated a throughput benefit analysis.« less

78 FR 48670 - Boulder Canyon Project

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-09

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Canyon Project (BCP) electric service provided by the Western Area Power Administration (Western). The... States Department of Energy, Western Area Power Administration, Boulder Canyon Project, 133 FERC ] 62,229...

Feasibility of processing the experimental breeder reactor-II driver fuel from the Idaho National Laboratory through Savannah River Site's H-Canyon facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magoulas, V. E.

Savannah River National Laboratory (SRNL) was requested to evaluate the potential to receive and process the Idaho National Laboratory (INL) uranium (U) recovered from the Experimental Breeder Reactor II (EBR-II) driver fuel through the Savannah River Site’s (SRS) H-Canyon as a way to disposition the material. INL recovers the uranium from the sodium bonded metallic fuel irradiated in the EBR-II reactor using an electrorefining process. There were two compositions of EBR-II driver fuel. The early generation fuel was U-5Fs, which consisted of 95% U metal alloyed with 5% noble metal elements “fissium” (2.5% molybdenum, 2.0% ruthenium, 0.3% rhodium, 0.1% palladium,more » and 0.1% zirconium), while the later generation was U-10Zr which was 90% U metal alloyed with 10% zirconium. A potential concern during the H-Canyon nitric acid dissolution process of the U metal containing zirconium (Zr) is the explosive behavior that has been reported for alloys of these materials. For this reason, this evaluation was focused on the ability to process the lower Zr content materials, the U-5Fs material.« less

Street canyon aerosol pollutant transport measurements.

PubMed

Longley, I D; Gallagher, M W; Dorsey, J R; Flynn, M; Bower, K N; Allan, J D

2004-12-01

Current understanding of dispersion in street canyons is largely derived from relatively simple dispersion models. Such models are increasingly used in planning and regulation capacities but are based upon a limited understanding of the transport of substances within a real canyon. In recent years, some efforts have been made to numerically model localised flow in idealised canyons (e.g., J. Appl. Meteorol. 38 (1999) 1576-89) and stepped canyons (Assimakopoulos V. Numerical modelling of dispersion of atmospheric pollution in and above urban canopies. PhD thesis, Imperial College, London, 2001) but field studies in real canyons are rare. To further such an understanding, a measurement campaign has been conducted in an asymmetric street canyon with busy one-way traffic in central Manchester in northern England. The eddy correlation method was used to determine fluxes of size-segregated accumulation mode aerosol. Measurements of aerosol at a static location were made concurrently with measurements on a platform lift giving vertical profiles. Size-segregated measurements of ultrafine and coarse particle concentrations were also made simultaneously at various heights. In addition, a small mobile system was used to make measurements of turbulence at various pavement locations within the canyon. From this data, various features of turbulent transport and dispersion in the canyon will be presented. The concentration and the ventilation fluxes of vehicle-related aerosol pollutants from the canyon will be related to controlling factors. The results will also be compared with citywide ventilation data from a separate measurement campaign conducted above the urban canopy.

77 FR 48151 - Boulder Canyon Project

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-13

... DEPARTMENT OF ENERGY Western Area Power Administration Boulder Canyon Project AGENCY: Western Area... Canyon Project (BCP) electric service provided by the Western Area Power Administration (Western). The... INFORMATION: Hoover Dam, authorized by the Boulder Canyon Project Act (45 Stat. 1057, December 21, 1928), sits...

Draft environmental assessment: Lavender Canyon site, Utah. Nuclear Waste Policy Act (Section 112). [Contains glossary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1984-12-01

In February 1983, the US Department of Energy (DOE) identified the Lavender Canyon site in Utah, as one of nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Lavender Canyon site and the eight other potentially acceptable sites h

Hyperosmotic Agents and Antibiotics Affect Dissolved Oxygen and pH Concentration Gradients in Staphylococcus aureus Biofilms

PubMed Central

Kiamco, Mia Mae; Atci, Erhan

2017-01-01

ABSTRACT Biofilms on wound surfaces are treated topically with hyperosmotic agents, such as medical-grade honey and cadexomer iodine; in some cases, these treatments are combined with antibiotics. Tissue repair requires oxygen, and a low pH is conducive to oxygen release from red blood cells and epithelialization. We investigated the variation of dissolved oxygen concentration and pH with biofilm depth and the variation in oxygen consumption rates when biofilms are challenged with medical-grade honey or cadexomer iodine combined with vancomycin or ciprofloxacin. Dissolved oxygen and pH depth profiles in Staphylococcus aureus biofilms were measured using microelectrodes. The presence of cadexomer iodine with vancomycin or ciprofloxacin on the surface of the biofilm permitted a measurable concentration of oxygen at greater biofilm depths (101.6 ± 27.3 μm, P = 0.02; and 155.5 ± 27.9 μm, P = 0.016, respectively) than in untreated controls (30.1 μm). Decreases in pH of ∼0.6 and ∼0.4 units were observed in biofilms challenged with medical-grade honey alone and combined with ciprofloxacin, respectively (P < 0.001 and 0.01, respectively); the number of bacteria recovered from biofilms was significantly reduced (1.26 log) by treatment with cadexomer iodine and ciprofloxacin (P = 0.002) compared to the untreated control. Combining cadexomer iodine and ciprofloxacin improved dissolved oxygen concentration and penetration depth into the biofilm, while medical-grade honey was associated with a lower pH; not all treatments established a bactericidal effect in the time frame used in the experiments. IMPORTANCE Reports about using hyperosmotic agents and antibiotics against wound biofilms focus mostly on killing bacteria, but the results of these treatments should additionally be considered in the context of how they affect physiologically important parameters, such as oxygen concentration and pH. We confirmed that the combination of a hyperosmotic agent and an antibiotic

Hyperosmotic Agents and Antibiotics Affect Dissolved Oxygen and pH Concentration Gradients in Staphylococcus aureus Biofilms.

PubMed

Kiamco, Mia Mae; Atci, Erhan; Mohamed, Abdelrhman; Call, Douglas R; Beyenal, Haluk

2017-03-15

Biofilms on wound surfaces are treated topically with hyperosmotic agents, such as medical-grade honey and cadexomer iodine; in some cases, these treatments are combined with antibiotics. Tissue repair requires oxygen, and a low pH is conducive to oxygen release from red blood cells and epithelialization. We investigated the variation of dissolved oxygen concentration and pH with biofilm depth and the variation in oxygen consumption rates when biofilms are challenged with medical-grade honey or cadexomer iodine combined with vancomycin or ciprofloxacin. Dissolved oxygen and pH depth profiles in Staphylococcus aureus biofilms were measured using microelectrodes. The presence of cadexomer iodine with vancomycin or ciprofloxacin on the surface of the biofilm permitted a measurable concentration of oxygen at greater biofilm depths (101.6 ± 27.3 μm, P = 0.02; and 155.5 ± 27.9 μm, P = 0.016, respectively) than in untreated controls (30.1 μm). Decreases in pH of ∼0.6 and ∼0.4 units were observed in biofilms challenged with medical-grade honey alone and combined with ciprofloxacin, respectively ( P < 0.001 and 0.01, respectively); the number of bacteria recovered from biofilms was significantly reduced (1.26 log) by treatment with cadexomer iodine and ciprofloxacin ( P = 0.002) compared to the untreated control. Combining cadexomer iodine and ciprofloxacin improved dissolved oxygen concentration and penetration depth into the biofilm, while medical-grade honey was associated with a lower pH; not all treatments established a bactericidal effect in the time frame used in the experiments. IMPORTANCE Reports about using hyperosmotic agents and antibiotics against wound biofilms focus mostly on killing bacteria, but the results of these treatments should additionally be considered in the context of how they affect physiologically important parameters, such as oxygen concentration and pH. We confirmed that the combination of a hyperosmotic agent and an antibiotic

Transportation Analysis and Feasibility Study : Sabino Canyon Recreation Area, Coronado National Forest

DOT National Transportation Integrated Search

2010-02-28

The goal of this report is to identify potential transportation solutions to issues that have been identified : at Sabino Canyon. Examples of future transportation systems are provided to show a variety of future : transportation conditions within th...

Durable terrestrial bedrock predicts submarine canyon formation

USGS Publications Warehouse

Smith, Elliot; Finnegan, Noah J.; Mueller, Erich R.; Best, Rebecca J.

2017-01-01

Though submarine canyons are first-order topographic features of Earth, the processes responsible for their occurrence remain poorly understood. Potentially analogous studies of terrestrial rivers show that the flux and caliber of transported bedload are significant controls on bedrock incision. Here we hypothesize that coarse sediment load could exert a similar role in the formation of submarine canyons. We conducted a comprehensive empirical analysis of canyon occurrence along the West Coast of the contiguous United States which indicates that submarine canyon occurrence is best predicted by the occurrence of durable crystalline bedrock in adjacent terrestrial catchments. Canyon occurrence is also predicted by the flux of bed sediment to shore from terrestrial streams. Surprisingly, no significant correlation was observed between canyon occurrence and the slope or width of the continental shelf. These findings suggest that canyon incision is promoted by greater yields of durable terrestrial clasts to the shore.

Physical and chemical characteristics of Lake Powell at the forebay and outflows of Glen Canyon Dam, northeastern Arizona, 1990-91

USGS Publications Warehouse

Hart, R.J.; Sherman, K.M.

1996-01-01

The physical and chemical characteristics of Lake Powell have a direct effect on the quality of water below Glen Canyon Dam. Understanding the physical and chemical characteristics of the lake and outflows from the dam is essential in order to effectively manage the operation of the dam. During August 1990 to September 1991, physical and chemical measurements were made and water samples were collected in the forebay of Lake Powell and at the outflows (draft tubes) of Glen Canyon Dam to document the physical and chemical characteristics of water entering the Colorado River. A persistent chemocline in the forebay of Lake Powell fluctuated seasonally during the study. Thermal stratification began in mid-April and persisted into late October. Spatial variation of specific conductance, pH, water temperature, and dissolved-oxygen concentration in the forebay was negligible. Sodium and sulfate were the dominant ions. Major ions, nutrients, and metals generally increased in concentration with depth in the forebay. Concentrations of dissolved nitrogen (as nitrite plus nitrate) in the forebay ranged from less than 0.02 to 0.58 milligrams per liter. Strontium and lithium were the most abundant metals. Dissolved organic carbon ranged from about 2.6 to 4.9 milligrams per. liter with larger concentrations generally occurring in the epilimnion. No diel variations of chemical constituents were observed. Vertical-attenuation coefficients of light penetration in the forebay ranged from 0.058 to 0.080 microeinsteins per meter squared per second, and the euphotic depth ranged from about 82 to 113 feet. Generally, the physical and chemical characteristics of outflows through the draft tubes of Glen Canyon Dam were similar to the physical and chemical characteristics of the water at penstock depth and deeper depths. Specific conductance ranged from 803 to 1,090 microsiemens per centimeter, and pH values ranged from about 7.2 to 8.0. Water temperatures measured in the outflows ranged

Selected hydrologic data for the field demonstration of three permeable reactive barriers near Fry Canyon, Utah, 1996-2000

USGS Publications Warehouse

Wilkowske, Chris D.; Rowland, Ryan C.; Naftz, David L.

2001-01-01

Three permeable reactive barriers (PRBs) were installed near Fry Canyon, Utah, in August 1997 to demonstrate the use of PRBs to control the migration of uranium in ground water. Reactive material included (1) bone-char phosphate, (2) zero-valent iron pellets, and (3) amorphous ferric oxyhydroxide coated gravel. An extensive monitoring network was installed in and around each PRB for collection of water samples, analysis of selected water-quality parameters, and monitoring of water levels. Water temperature, specific conductance, pH, Eh (oxidation-reduction potential), and dissolved oxygen were measured continuously within three different barrier materials, and in two monitoring wells. Water temperature and water level below land surface were electronically recorded every hour with pressure transducers. Data were collected from ground-water monitoring wells installed in and around the PRBs during 1996-98 and from surface-water sites in Fry Creek.

Relative effect of temperature and pH on diel cycling of dissolved trace elements in prickly pear creek, Montana

USGS Publications Warehouse

Jones, Clain A.; Nimick, D.A.; McCleskey, R. Blaine

2004-01-01

Diel (24 hr) cycles in dissolved metal and As concentrations have been documented in many northern Rocky Mountain streams in the U.S.A. The cause(s) of the cycles are unknown, although temperature- and pH-dependent sorption reactions have been cited as likely causes. A light/dark experiment was conducted to isolate temperature and pH as variables affecting diel metal cycles in Prickly Pear Creek, Montana. Light and dark chambers containing sediment and a strand of macrophyte were placed in the stream to simulate instream temperature oscillations. Photosynthesis-induced pH changes were allowed to proceed in the light chambers while photosynthesis was prevented in the dark chambers. Water samples were collected periodically for 22 hr in late July 2001 from all chambers and the stream. In the stream, dissolved Zn concentrations increased by 300% from late afternoon to early morning, while dissolved As concentrations exhibited the opposite pattern, increasing 33% between early morning and late afternoon. Zn and As concentrations in the light chambers showed similar, though less pronounced, diel variations. Conversely, Zn and As concentrations in the dark chambers had no obvious diel variation, indicating that light, or light-induced reactions, caused the variation. Temperature oscillations were nearly identical between light and dark chambers, strongly suggesting that temperature was not controlling the diel variations. As expected, pH was negatively correlated (P < 0.01) with dissolved Zn concentrations and positively correlated with dissolved As concentrations in both the light and dark chambers. From these experiments, photosynthesis-induced pH changes were determined to be the major cause of the diel dissolved Zn and As cycles in Prickly Pear Creek. Further research is necessary in other streams to verify that this finding is consistent among streams having large differences in trace-element concentrations and mineralogy of channel substrate. ?? 2004 Kluwer

Morphology, distribution, and development of submarine canyons on the United States Atlantic continental slope between Hudson arid Baltimore Canyons

NASA Astrophysics Data System (ADS)

Twichell, David C.; Roberts, David G.

1982-08-01

The distribution and morphology of submarine canyons off the eastern United States between Hudson and Baltimore Canyons have been mapped by long-range sidescan sonar. In this area canyons are numerous, and their spacing correlates with overall slope gradient; they are absent where the gradient is less than 3°, are 2 to 10 km apart where the gradient is 3° to 5°, and are 1.5 to 4 km apart where the gradient exceeds 6°. Canyons range from straight to sinuous; those having sinuous axes indent the edge of the continental shelf and appear to be older than those that head on the upper slope and have straighter axes. A difference in canyon age would suggest that canyons are initiated on the continental slope and only with greater age erode headward to indent the shelf. Shallow gullies on the middle and upper slope parts of the canyon walls suggest that submarine erosion has been a major process in a recent phase of canyon development. *Present address: British Petroleum, Moorgate, London EC2Y 9BU, England

Research Furthers Conservation of Grand Canyon Sandbars

USGS Publications Warehouse

Melis, Theodore S.; Topping, David J.; Rubin, David M.; Wright, Scott A.

2007-01-01

Grand Canyon National Park lies approximately 25 km (15 mi) down-river from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border in Glen Canyon National Recreation Area. Before the dam began to regulate the Colorado River in 1963, the river carried such large quantities of red sediment, for which the Southwest is famous, that the Spanish named the river the Rio Colorado, or 'red river'. Today, the Colorado River usually runs clear below Glen Canyon Dam because the dam nearly eliminates the main-channel sand supply. The daily and seasonal flows of the river were also altered by the dam. These changes have disrupted the sedimentary processes that create and maintain Grand Canyon sandbars. Throughout Grand Canyon, sandbars create habitat for native plants and animals, supply camping beaches for river runners and hikers, and provide sediment needed to protect archaeological resources from weathering and erosion. Maintenance of sandbars in the Colorado River ecosystem, the river corridor that stretches from the dam to the western boundary of Grand Canyon National Park, is a goal of the Glen Canyon Dam Adaptive Management Program. The program is a federally authorized initiative to ensure that the mandates of the Grand Canyon Protection Act of 1992 are met through advances in information and resource management. The U.S. Geological Survey's Grand Canyon Monitoring and Research Center has responsibility for scientific monitoring and research efforts for the program. Extensive research and monitoring during the past decade have resulted in the identification of possible alternatives for operating Glen Canyon Dam that hold new potential for the conservation of sand resources.

Algal and water-quality data for Rapid Creek and Canyon Lake near Rapid City, South Dakota, 2007

USGS Publications Warehouse

Hoogestraat, Galen K.; Putnam, Larry D.; Graham, Jennifer L.

2008-01-01

This report summarizes the results of algae and water-quality sampling on Rapid Creek and Canyon Lake during May and September 2007. The overall purpose of the study was to determine the algal community composition of Rapid Creek and Canyon Lake in relation to organisms that are known producers of unwanted tastes and odors in drinking-water supplies. Algal assemblage structure (phytoplankton and periphyton) was examined at 16 sites on Rapid Creek and Canyon Lake during May and September 2007, and actinomycetes bacteria were sampled at the Rapid City water treatment plant intake in May 2007, to determine if taste-and-odor producing organisms were present. During the May 2007 sampling, 3 Rapid Creek sites and 4 Canyon Lake sites were quantitatively sampled for phytoplankton in the water column, 7 Rapid Creek sites were quantitatively sampled for attached periphyton, and 4 lake and retention pond sites were qualitatively sampled for periphyton. Five Rapid Creek sites were sampled for geosmin and 2-methylisoborneol, two common taste-and-odor causing compounds known to affect water supplies. During the September 2007 sampling, 4 Rapid Creek sites were quantitatively sampled for attached periphyton, and 3 Canyon Lake sites were qualitatively sampled for periphyton. Water temperature, dissolved oxygen, pH, and specific conductance were measured during each sampling event. Methods of collection and sample analysis are presented for the various types of biological and chemical constituent samples. Diatoms comprised 91-100 percent of the total algal biovolume in periphyton samples collected during May and September. Cyanobacteria (also called blue-green algae) were detected in 7 of the 11 quantitative periphyton samples and ranged from 0.01 to 2.0 percent of the total biovolume. Cyanobacteria were present in 3 of the 7 phytoplankton samples collected in May, but the relative biovolumes were small (0.01-0.2 percent). Six of seven qualitative samples collected from Canyon Lake

Numerical study on the impact of ground heating and ambient wind speed on flow fields in street canyons

NASA Astrophysics Data System (ADS)

Li, Lei; Yang, Lin; Zhang, Li-Jie; Jiang, Yin

2012-11-01

The impact of ground heating on flow fields in street canyons under different ambient wind speed conditions was studied based on numerical methods. A series of numerical tests were performed, and three factors including height-to-width (H/W) ratio, ambient wind speed and ground heating intensity were taken into account. Three types of street canyon with H/W ratios of 0.5, 1.0 and 2.0, respectively, were used in the simulation and seven speed values ranging from 0.0 to 3.0 m s-1 were set for the ambient wind speed. The ground heating intensity, which was defined as the difference between the ground temperature and air temperature, ranged from 10 to 40 K with an increase of 10 K in the tests. The results showed that under calm conditions, ground heating could induce circulation with a wind speed of around 1.0 m s-1, which is enough to disperse pollutants in a street canyon. It was also found that an ambient wind speed threshold may exist for street canyons with a fixed H/W ratio. When ambient wind speed was lower than the threshold identified in this study, the impact of the thermal effect on the flow field was obvious, and there existed a multi-vortex flow pattern in the street canyon. When the ambient wind speed was higher than the threshold, the circulation pattern was basically determined by dynamic effects. The tests on the impact of heating intensity showed that a higher ground heating intensity could strengthen the vortical flow within the street canyon, which would help improve pollutant diffusion capability in street canyons.

Mineral resources of the Fish Creek Canyon, Road Canyon, and Mule Canyon Wilderness Study Areas, San Juan County, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bove, D.J.; Shawe, D.R.; Lee, G.K.

1989-01-01

This book reports the Fish Creek Canyon (UT-060-204), Road Canyon(UT-060-201), and Mule Canyon (UT-060-205B) Wilderness Study Areas, which comprise 40,160 acres, 52,420 acres, and 5,990 acres, respectively, studied for their mineral endowment. A search of federal, state, and county records showed no current or previous mining-claim activity. No mineral resources were identified during field examination of the study areas. Sandstone and sand and gravel have no unique qualities but could have limited local use for road metal or other construction purposes. However, similar materials are abundant outside the study areas. The three study areas have moderate resource potential for undiscoveredmore » oil and gas and low resource potential for undiscovered metals, including uranium and thorium, coal, and geothermal energy.« less

Methods of deoxygenating metals having oxygen dissolved therein in a solid solution

DOEpatents

Zhang, Ying; Fang, Zhigang Zak; Sun, Pei; Xia, Yang; Zhou, Chengshang

2017-06-06

A method of deoxygenating metal can include forming a mixture of: a metal having oxygen dissolved therein in a solid solution, at least one of metallic magnesium and magnesium hydride, and a magnesium-containing salt. The mixture can be heated at a deoxygenation temperature for a period of time under a hydrogen-containing atmosphere to form a deoxygenated metal. The deoxygenated metal can then be cooled. The deoxygenated metal can optionally be subjected to leaching to remove by-products, followed by washing and drying to produce a final deoxygenated metal.

Transport of Proteins Dissolved in Organic Solvents Across Biomimetic Membranes

NASA Astrophysics Data System (ADS)

Bromberg, Lev E.; Klibanov, Alexander M.

1995-02-01

Using lipid-impregnated porous cellulose membranes as biomimetic barriers, we tested the hypothesis that to afford effective transmembrane transfer of proteins and nucleic acids, the vehicle solvent should be able to dissolve both the biopolymers and the lipids. While the majority of solvents dissolve one or the other, ethanol and methanol were found to dissolve both, especially if the protein had been lyophilized from an aqueous solution of a pH remote from the protein's isoelectric point. A number of proteins, as well as RNA and DNA, dissolved in these alcohols readily crossed the lipidized membranes, whereas the same biopolymers placed in nondissolving solvents (e.g., hexane and ethyl acetate) or in those unable to dissolve lipids (e.g., water and dimethyl sulfoxide) exhibited little transmembrane transport. The solubility of biopolymers in ethanol and methanol was further enhanced by complexation with detergents and poly(ethylene glycol); significant protein and nucleic acid transport through the lipidized membranes was observed from these solvents but not from water.

Relationship between pH and Medium Dissolved Solids in Terms of Growth and Metabolism of Lactobacilli and Saccharomyces cerevisiae during Ethanol Production

PubMed Central

Narendranath, Neelakantam V.; Power, Ronan

2005-01-01

The specific growth rates of four species of lactobacilli decreased linearly with increases in the concentration of dissolved solids (sugars) in liquid growth medium. This was most likely due to the osmotic stress exerted by the sugars on the bacteria. The reduction in growth rates corresponded to decreased lactic acid production. Medium pH was another factor studied. As the medium pH decreased from 5.5 to 4.0, there was a reduction in the specific growth rate of lactobacilli and a corresponding decrease in the lactic acid produced. In contrast, medium pH did not have any significant effect on the specific growth rate of yeast at any particular concentration of dissolved solids in the medium. However, medium pH had a significant (P < 0.001) effect on ethanol production. A medium pH of 5.5 resulted in maximal ethanol production in all media with different concentrations of dissolved solids. When the data were analyzed as a 4 (pH levels) by 4 (concentrations of dissolved solids) factorial experiment, there was no synergistic effect (P > 0.2923) observed between pH of the medium and concentration of dissolved solids of the medium in reducing bacterial growth and metabolism. The data suggest that reduction of initial medium pH to 4.0 for the control of lactobacilli during ethanol production is not a good practice as there is a reduction (P < 0.001) in the ethanol produced by the yeast at pH 4.0. Setting the mash (medium) with ≥30% (wt/vol) dissolved solids at a pH of 5.0 to 5.5 will minimize the effects of bacterial contamination and maximize ethanol production by yeast. PMID:15870306

Specific Conductance in the Colorado River between Glen Canyon Dam and Diamond Creek, Northern Arizona, 1988-2007

USGS Publications Warehouse

Voichick, Nicholas

2008-01-01

The construction of Glen Canyon Dam, completed in 1963, resulted in substantial physical and biological changes to downstream Colorado River environments between Lake Powell and Lake Mead - an area almost entirely within Grand Canyon National Park, Ariz. In an effort to understand these changes, data have been collected to assess the condition of a number of downstream resources. In terms of measuring water quality, the collection of specific-conductance data is a cost-effective method for estimating salinity. Data-collection activities were initially undertaken by the Bureau of Reclamation's Glen Canyon Environmental Studies (1982-96); these efforts were subsequently transferred to the U.S. Geological Survey's Grand Canyon Monitoring and Research Center (1996 to the present). This report describes the specific-conductance dataset collected for the Colorado River between Glen Canyon Dam and Diamond Creek from 1988 to 2007. Data-collection and processing methods used during the study period are described, and time-series plots of the data are presented. The report also includes plots showing the relation between specific conductance and total dissolved solids. Examples of the use of specific conductance as a natural tracer of parcels of water are presented. Analysis of the data indicates that short-duration spikes and troughs in specific-conductance values lasting from hours to days are primarily the result of flooding in the Paria and Little Colorado Rivers, Colorado River tributaries below Glen Canyon Dam. Specific conductance also exhibits seasonal variations owing to changes in the position of density layers within the reservoir; these changes are driven by inflow hydrology, meteorological conditions, and background stratification. Longer term trends in Colorado River specific conductance are reflective of climatological conditions in the upper Colorado River Basin. For example, drought conditions generally result in an increase in specific conductance in Lake

Use of dissolved H2 concentrations to determine distribution of microbially catalyzed redox reactions in anoxic groundwater

USGS Publications Warehouse

Lovley, D.R.; Chapelle, F.H.; Woodward, J.C.

1994-01-01

The potential for using concentrations of dissolved H2 to determine the distribution of redox processes in anoxic groundwaters was evaluated. In pristine aquifers in which standard geochemical measurements indicated that Fe-(III) reduction, sulfate reduction, or methanogenesis was the terminal electron accepting process (TEAP), the H2 concentrations were similar to the H2 concentrations that have previously been reported for aquatic sediments with the same TEAPs. In two aquifers contaminated with petroleum products, it was impossible with standard geochemical analyses to determine which TEAPs predominated in specific locations. However, the TEAPs predicted from measurements of dissolved H2 were the same as those determined directly through measurements of microbial processes in incubated aquifer material. These results suggest that H2 concentrations may be a useful tool for analyzing the redox chemistry of nonequilibrium groundwaters.

Mars Canyon with Los Angeles for Scale

NASA Image and Video Library

2006-03-13

A Grand Canyon of Mars slices across the Red Planet near its equator. This canyon -- Valles Marineris, or the Mariner Valley -- is 10 times longer and deeper than Arizona Grand Canyon, and 20 times wider

Environmental assessment: Davis Canyon site, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOEmore » prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has fond that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization. 181 figs., 175 tabs.« less

Environmental assessment: Davis Canyon site, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high- level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, themore » DOE prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considered for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of the five sites suitable for characterization.« less

Environmental assessment: Davis Canyon site, Utah

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

1986-05-01

In February 1983, the US Department of Energy (DOE) identified the Davis Canyon site in Utah as one of the nine potentially acceptable sites for a mined geologic repository for spent nuclear fuel and high-level radioactive waste. To determine their suitability, the Davis Canyon site and the eight other potentially acceptable sites have been evaluated in accordance with the DOE's General Guidelines for the Recommendation of Sites for the Nuclear Waste Repositories. These evaluations were reported in draft environmental assessments (EAs), which were issued for public review and comment. After considering the comments received on the draft EAs, the DOEmore » prepared the final EA. The Davis Canyon site is in the Paradox Basin, which is one of five distinct geohydrologic settings considering for the first repository. This setting contains one other potentially acceptable site -- the Lavender Canyon site. Although the Lavender Canyon site is suitable for site characterization, the DOE has concluded that the Davis Canyon site is the preferred site in the Paradox Basin. On the basis of the evaluations reported in this EA, the DOE has found that the Davis Canyon site is not disqualified under the guidelines. Furthermore, the DOE has found that the site is suitable for site characterization because the evidence does not support a conclusion that the site will not be able to meet each of the qualifying conditions specified in the guidelines. On the basis of these findings, the DOE is nominating the Davis Canyon site as one of five sites suitable for characterization.« less

Dissolved organic carbon in soil solution of peat-moorsh soils on Kuwasy Mire

NASA Astrophysics Data System (ADS)

Jaszczyński, J.; Sapek, A.

2009-04-01

Key words: peat-moorsh soils, soil solution, dissolved organic carbon (DOC), temperature of soil, redox potential. The objective this study was the dissolved organic carbon concentration (DOC) in soil solution on the background of soil temperature, moisture and redox potential. The investigations were localized on the area of drained and agricultural used Kuwasy Mire, which are situated in the middle basin of Biebrza River, in North-East Poland. Research point was placed on a low peat soil of 110 cm depth managed as extensive grassland. The soil was recognized as peat-moorsh with the second degree of the moorshing process (with 20 cm of moorsh layer). The ceramic suction cups were installed in three replications at 30 cm depth of soil profile. The soil solution was continuously sampled by pomp of the automatic field station. The successive samples comprised of solution collected at the intervals of 21 days. Simultaneously, at the 20, 30 and 40 cm soil depths the measurements of temperature and determination of soil moisture and redox potential were made automatically. The mean twenty-four hours data were collected. The concentrations of DOC were determined by means of the flow colorimeter using the Skalar standard methods. Presented observations were made in 2001-2006. Mean DOC concentration in soil solution was 66 mg.dm-3 within all research period. A significant positive correlation between studied compound concentration and temperature of soil at 30 cm depth was observed; (correlation coefficient - r=0.55, number of samples - n=87). The highest DOC concentrations were observed during the season from July to October, when also a lower ground water level occurred. The DOC concentration in soil solution showed as well a significant correlation with the soil redox potential at 20 cm level. On this depth of describing soil profile a frontier layer between moorshing layer and peat has been existed. This layer is the potentially most active in the respect to

Hanging canyons of Haida Gwaii, British Columbia, Canada: Fault-control on submarine canyon geomorphology along active continental margins

NASA Astrophysics Data System (ADS)

Harris, Peter T.; Barrie, J. Vaughn; Conway, Kim W.; Greene, H. Gary

2014-06-01

Faulting commonly influences the geomorphology of submarine canyons that occur on active continental margins. Here, we examine the geomorphology of canyons located on the continental margin off Haida Gwaii, British Columbia, that are truncated on the mid-slope (1200-1400 m water depth) by the Queen Charlotte Fault Zone (QCFZ). The QCFZ is an oblique strike-slip fault zone that has rates of lateral motion of around 50-60 mm/yr and a small convergent component equal to about 3 mm/yr. Slow subduction along the Cascadia Subduction Zone has accreted a prism of marine sediment against the lower slope (1500-3500 m water depth), forming the Queen Charlotte Terrace, which blocks the mouths of submarine canyons formed on the upper slope (200-1400 m water depth). Consequently, canyons along this margin are short (4-8 km in length), closely spaced (around 800 m), and terminate uniformly along the 1400 m isobath, coinciding with the primary fault trend of the QCFZ. Vertical displacement along the fault has resulted in hanging canyons occurring locally. The Haida Gwaii canyons are compared and contrasted with the Sur Canyon system, located to the south of Monterey Bay, California, on a transform margin, which is not blocked by any accretionary prism, and where canyons thus extend to 4000 m depth, across the full breadth of the slope.

Acid neutralizing processes in an alpine watershed front range, Colorado, U.S.A.-1: Buffering capacity of dissolved organic carbon in soil solutions

USGS Publications Warehouse

Iggy, Litaor M.; Thurman, E.M.

1988-01-01

Soil interstitial waters in the Green Lakes Valley, Front Range, Colorado were studied to evaluate the capacity of the soil system to buffer acid deposition. In order to determine the contribution of humic substances to the buffering capacity of a given soil, dissolved organic carbon (DOC) and pH of the soil solutions were measured. The concentration of the organic anion, Ai-, derived from DOC at sample pH and the concentration of organic anion, Ax- at the equivalence point were calculated using carboxyl contents from isolated and purified humic material from soil solutions. Subtracting Ax- from Ai- yields the contribution of humic substances to the buffering capacity (Aequiv.-). Using this method, one can evaluate the relative contribution of inorganic and organic constituents to the acid neutralizing capacity (ANC) of the soil solutions. The relative contribution of organic acids to the overall ANC was found to be extremely important in the alpine wetland (52%) and the forest-tundra ecotone (40%), and somewhat less important in the alpine tundra sites (20%). A failure to recognize the importance of organic acids in soil solutions to the ANC will result in erroneous estimates of the buffering capacity in the alpine environment of the Front Range, Colorado. ?? 1988.

Late Holocene earthquake history of the Brigham City segment of the Wasatch fault zone at the Hansen Canyon, Kotter Canyon, and Pearsons Canyon trench sites, Box Elder County, Utah

USGS Publications Warehouse

DuRoss, Christopher B.; Personius, Stephen F.; Crone, Anthony J.; McDonald, Greg N.; Briggs, Richard W.

2012-01-01

Of the five central segments of the Wasatch fault zone (WFZ) having evidence of recurrent Holocene surface-faulting earthquakes, the Brigham City segment (BCS) has the longest elapsed time since its most recent surface-faulting event (~2.1 kyr) compared to its mean recurrence time between events (~1.3 kyr). Thus, the BCS has the highest time-dependent earthquake probability of the central WFZ. We excavated trenches at three sites––the Kotter Canyon and Hansen Canyon sites on the north-central BCS and Pearsons Canyon site on the southern BCS––to determine whether a surface-faulting earthquake younger than 2.1 ka occurred on the BCS. Paleoseismic data for Hansen Canyon and Kotter Canyon confirm that the youngest earthquake on the north-central BCS occurred before 2 ka, consistent with previous north-central BCS investigations at Bowden Canyon and Box Elder Canyon. At Hansen Canyon, the most recent earthquake is constrained to 2.1–4.2 ka and had 0.6–2.5 m of vertical displacement. At Kotter Canyon, we found evidence for two events at 2.5 ± 0.3 ka and 3.5 ± 0.3 ka, with an average displacement per event of 1.9–2.3 m. Paleoseismic data from Pearsons Canyon, on the previously unstudied southern BCS, indicate that a post-2 ka earthquake ruptured this part of the segment. The Pearsons Canyon earthquake occurred at 1.2 ± 0.04 ka and had 0.1–0.8 m of vertical displacement, consistent with our observation of continuous, youthful scarps on the southern 9 km of the BCS having 1–2 m of late Holocene(?) surface offset. The 1.2-ka earthquake on the southern BCS likely represents rupture across the Weber–Brigham City segment boundary from the penultimate Weber-segment earthquake at about 1.1 ka. The Pearsons Canyon data result in a revised length of the BCS that has not ruptured since 2 ka (with time-dependent probability implications), and provide compelling evidence of at least one segment-boundary failure and multi-segment rupture on the central WFZ. Our

AFS-2 FLOWSHEET MODIFICATIONS TO ADDRESS THE INGROWTH OF PU(VI) DURING METAL DISSOLUTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crapse, K.; Rudisill, T.; O'Rourke, P.

2014-07-02

In support of the Alternate Feed Stock Two (AFS-2) PuO{sub 2} production campaign, Savannah River National Laboratory (SRNL) conducted a series of experiments concluding that dissolving Pu metal at 95°C using a 6–10 M HNO{sub 3} solution containing 0.05–0.2 M KF and 0–2 g/L B could reduce the oxidation of Pu(IV) to Pu(VI) as compared to dissolving Pu metal under the same conditions but at or near the boiling temperature. This flowsheet was demonstrated by conducting Pu metal dissolutions at 95°C to ensure that PuO{sub 2} solids were not formed during the dissolution. These dissolution parameters can be used formore » dissolving both Aqueous Polishing (AP) and MOX Process (MP) specification materials. Preceding the studies reported herein, two batches of Pu metal were dissolved in the H-Canyon 6.1D dissolver to prepare feed solution for the AFS-2 PuO{sub 2} production campaign. While in storage, UV-visible spectra obtained from an at-line spectrophotometer indicated the presence of Pu(VI). Analysis of the solutions also showed the presence of Fe, Ni, and Cr. Oxidation of Pu(IV) produced during metal dissolution to Pu(VI) is a concern for anion exchange purification. Anion exchange requires Pu in the +4 oxidation state for formation of the anionic plutonium(IV) hexanitrato complex which absorbs onto the resin. The presence of Pu(VI) in the anion feed solution would require a valence adjustment step to prevent losses. In addition, the presence of Cr(VI) would result in absorption of chromate ion onto the resin and could limit the purification of Pu from Cr which may challenge the purity specification of the final PuO{sub 2} product. Initial experiments were performed to quantify the rate of oxidation of Pu(IV) to Pu(VI) (presumed to be facilitated by Cr(VI)) as functions of the HNO{sub 3} concentration and temperature in simulated dissolution solutions containing Cr, Fe, and Ni. In these simulated Pu dissolutions studies, lowering the temperature from near

Reactive Solute Transport in Streams: 2. Simulation of a pH Modification Experiment

NASA Astrophysics Data System (ADS)

Runkel, Robert L.; McKnight, Diane M.; Bencala, Kenneth E.; Chapra, Steven C.

1996-02-01

We present an application of an equilibrium-based solute transport model to a pH-modification experiment conducted on the Snake River, an acidic, metal-rich stream located in the Rocky Mountains of Colorado. During the experiment, instream pH decreased from 4.2 to 3.2, causing a marked increase in dissolved iron concentrations. Model application requires specification of several parameters that are estimated using tracer techniques, mass balance calculations, and geochemical data. Two basic questions are addressed through model application: (1) What are the processes responsible for the observed increase in dissolved iron concentrations? (2) Can the identified processes be represented within the equilibrium-based transport model? Simulation results indicate that the increase in iron was due to the dissolution of hydrous iron oxides and the photoreduction of ferric iron. Dissolution from the streambed is represented by considering a trace compartment consisting of freshly precipitated hydrous iron oxide and an abundant compartment consisting of aged precipitates that are less soluble. Spatial variability in the solubility of hydrous iron oxide is attributed to heterogeneity in the streambed sediments, temperature effects, and/or variability in the effects of photoreduction. Solubility products estimated via simulation fall within a narrow range (pKsp from 40.2 to 40.8) relative to the 6 order of magnitude variation reported for laboratory experiments (pKsp from 37.3 to 43.3). Results also support the use of an equilibrium-based transport model as the predominate features of the iron and pH profiles are reproduced. The model provides a valuable tool for quantifying the nature and extent of pH-dependent processes within the context of hydrologic transport.

The release of dissolved nutrients and metals from coastal sediments due to resuspension

USGS Publications Warehouse

Kalnejais, Linda H.; Martin, William R.; Bothner, Michael H.

2010-01-01

Coastal sediments in many regions are impacted by high levels of contaminants. Due to a combination of shallow water depths, waves, and currents, these sediments are subject to regular episodes of sediment resuspension. However, the influence of such disturbances on sediment chemistry and the release of solutes is poorly understood. The aim of this study is to quantify the release of dissolved metals (iron, manganese, silver, copper, and lead) and nutrients due to resuspension in Boston Harbor, Massachusetts, USA. Using a laboratory-based erosion chamber, a range of typical shear stresses was applied to fine-grained Harbor sediments and the solute concentration at each shear stress was measured. At low shear stress, below the erosion threshold, limited solutes were released. Beyond the erosion threshold, a release of all solutes, except lead, was observed and the concentrations increased with shear stress. The release was greater than could be accounted for by conservative mixing of porewaters into the overlying water, suggesting that sediment resuspension enhances the release of nutrients and metals to the dissolved phase. To address the long-term fate of resuspended particles, samples from the erosion chamber were maintained in suspension for 90. h. Over this time, 5-7% of the particulate copper and silver was released to the dissolved phase, while manganese was removed from solution. Thus resuspension releases solutes both during erosion events and over a longer timescale due to reactions of suspended particles in the water column. The magnitude of the annual solute release during erosion events was estimated by coupling the erosion chamber results with a record of bottom shear stresses simulated by a hydrodynamic model. The release of dissolved copper, lead, and phosphate due to resuspension is between 2% and 10% of the total (dissolved plus particulate phase) known inputs to Boston Harbor. Sediment resuspension is responsible for transferring a significant

Storm Water Quality in Los Alamos Canyon following the Cerro Grande Fire

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. Johansen; B. Enz; B. Gallaher

In May 2000, the Cerro Grande Fire burned about 7400 acres of forest on the Los Alamos National Laboratory (LANL) and about 10,000 acres in watersheds above LANL on Santa Fe National Forest lands. The resulting burned landscapes raised concerns of increased storm water runoff and transport of contaminants by runoff in the canyons traversing LANL. On June 2 and 3, 2000, rain fell in the Los Alamos Canyon watershed generating storm water runoff in the canyon bottom. This event was important in that it was the first significant runoff on LANL following the fire and occurred in a canyonmore » containing known legacy waste sites. Samples from this runoff were analyzed for radionuclide, metal, inorganic, and organic constituents. Results show radionuclide concentrations at or below previous (pre-fire) maximum levels at locations on LANL and downstream. However, greater concentrations of some fallout-associated radionuclides (cesium-137 and strontium-90) were seen arriving on LANL from upstream areas compared to pre-fire conditions. Tests indicate most of the radionuclides in the samples were bound to sediments, not dissolved in water. Most radionuclide concentrations in sediments were below LANL Screening Action Levels, with cesium-137 and strontium-90 as exceptions. Most radionuclide concentrations in samples taken at LANL's downstream boundary were greater than those taken upstream, indicating the presence of contributing sources on LANL. For comparison purposes, doses were calculated on a mrem per liter of unfiltered water basis for 11 radionuclides commonly associated with atmospheric fallout and with LANL operations. The maximum dose was 0.094 mrem per liter unfiltered water and was largely associated with plutonium-239/240. In contrast, all filtered samples had total doses less than 0.001 mrem per liter. Compared to past data, potential doses were not increased by the fire during this initial runoff event. Of the 25 metals tested for, seven were above pre

Measurements of the Activity of dissolved H2O in an Andesite Melt

NASA Astrophysics Data System (ADS)

Moore, G. M.; Touran, J. P.; Pu, X.; Kelley, K. A.; Cottrell, E.; Ghiorso, M. S.

2016-12-01

The large effect of dissolved H2O on the physical and chemical nature of silicate melts, and its role in driving volcanism, is well known and underscores the importance of this volatile component. A complete understanding of the chemical behavior of dissolved H2O in silicate melts requires the quantification of its thermodynamic activity as a function of pressure, temperature, and melt composition, particularly at low H2O contents (i.e. at under-saturated conditions). Knowledge of the activity of H2O in silicate melts at H2O-undersaturated conditions will improve our understanding of hydrous phase equilibria, as well as our models of physical melt properties. Measurement of the activity of any silicate melt component, much less that of a volatile component such as H2O, is a difficult experimental task however. By using a modified double capsule design (Matjuschkin et al, 2015) to control oxygen fugacity in piston cylinder experiments, along with high precision X-ray absorption techniques (XANES) to measure iron oxidation state in silicate glasses (Cottrell et al, 2009), we are able to constrain the H2O activity in silicate melts at under-saturated conditions. Preliminary results on an andesite melt with low H2O content (3 wt%) have been shown (Moore et al, 2016) to match predicted H2O activity values calculated using the H2O equation of state of Duan and Zhang (1996) and the H2O solubility model of Ghiorso and Gualda (2015). More recent results on the same andesite melt containing approximately 5 wt% H2O however show a large negative deviation from the predicted values. Reversal experiments involving an oxidized starting material are ongoing, as well as further characterization of the samples to detect the presence of possible contaminants that would induce reduction of the melt beyond that related to the H2O activity (e.g. graphite contamination).

DOE Office of Scientific and Technical Information (OSTI.GOV)

RHODES, WILLIAM

As part of the HEU Blend Down project, aluminum tape is required to seal aluminum tubes that will hold contaminated Mark 22 fuel tubes for dissolution. From a large field of candidate tapes, Avery Dennison's Fasson 0802 tape (synthetic rubber adhesive system) was found to be acceptable for this application. This tape will disentangle in the normal H-Canyon dissolver solution and have no detrimental effect on the H-Canyon process. Upon placement of Fasson 0802 tape into the dissolver solution, nitric acid will attack and disentangle the block copolymer network and destroy the adhesive nature of the material, resulting in insolublemore » particles that can be removed via centrifuge operations (cake weight increase of no more than 1 percent). The addition of the tape will not generate off-gas products and the resultant solution characteristics (surface tension, viscosity, density, and disengagement time) will be unaffected. Further, the potential effect on the down-stream evaporation system is negligible. Since the tape will not be placed in a high radiation environment, radiation stability is not an issue. Through detailed discussions with Avery Dennison chemists and based on analytical tests, a fairly detailed understanding of the constituents comprising the proprietary adhesive system has been assembled. Most importantly, chlorine was not detected in the aluminum tape (neutron activation analysis detection limit is 16 ppm). Finally, application of this tape will not impact LEU specifications.« less

Submarine sand dunes and sedimentary environments in Oceanographer Canyon.

USGS Publications Warehouse

Valentine, P.C.; Cooper, R.A.; Uzmann, J.R.

1984-01-01

Observations from research submersibles in the northern part of Oceanographer Canyon reveal the presence of an extensive field of large sand dunes on the canyon floor. The dunes are medium to coarse sand, are oriented across the axis, and the largest of them are as high as 3 m and have wavelengths up to 15 m. Their asymmetry, grain size, and height suggest that they are formed by axial currents flowing up- and downcanyon and that the largest dunes require flows of at least 70 cm/sec. Shelf sand, low in silt and clay content, is transported by currents down and along the canyon walls onto the canyon floor. As the sand enters the canyon, it is mixed with immobile gravel deposits on the canyon rim; lower on the walls, the sand is mixed with silt and clay burrowed by organisms from the semiconsolidated sandy silt that underlies the canyon walls and floor. Upon reaching the canyon floor, the sand is sculpted into bed forms by currents, and the fines are winnowed out and transported out of the canyon. At present, the shelf and canyon walls are being eroded by bottom currents and burrowing organisms, whereas the canyon floor is covered by mobile sand that moves both up and down the axis in this part of the canyon.

The Black Canyon of the Gunnison: Today and Yesterday

USGS Publications Warehouse

Hansen, Wallace R.

1965-01-01

Since the early visit of Captain John William Gunnison in the middle of the last century, the Black Canyon of the Gunnison has stirred mixed apprehension and wonder in the hearts of its viewers. It ranks high among the more awesome gorges of North America. Many great western canyons are as well remembered for their brightly colored walls as for their airy depths. Not so the Black Canyon. Though it is assuredly not black, the dark-gray tones of its walls and the hazy shadows of its gloomy depths join together to make its name well deserved. Its name conveys an impression, not a picture. After the first emotional impact of the canyon, the same questions come to the minds of most reflective viewers and in about the following order: How deep is the Black Canyon, how wide, how does it compare with other canyons, what are the rocks, how did it form, and how long did it take? Several western canyons exceed the Black Canyon in overall size. Some are longer; some are deeper; some are narrower; and a few have walls as steep. But no other canyon in North American combines the depth, narrowness, sheerness, and somber countenance of the Black Canyon. In many places the Black Canyon is as deep as it is wide. Between The Narrows and Chasm View in the Black Canyon of the Gunnison National Monument (fig. 15) it is much deeper than wide. Average depth in the monument is about 2,000 feet, ranging from a maximum of about 2,700 feet, north of Warner Point (which also is the greatest depth anywhere in the canyon), to a minimum of about 1,750 feet at The Narrows. The stretch of canyon between Pulpit Rock and Chasm View, including The Narrows, though the shallowest in the monument, is also the narrowest, has some of the steepest walls, and is, therefore, among the most impressive segments of the canyon (fig. 3). Profiles of several well-known western canyons are shown in figure 1. Deepest of these by far is Hells Canyon of the Snake, on the Idaho-Oregon border. Clearly, it dwarfs the

Amphiphilic Fluorinated Polymer Nanoparticle Film Formation and Dissolved Oxygen Sensing Application

NASA Astrophysics Data System (ADS)

Gao, Yu; Zhu, Huie; Yamamoto, Shunsuke; Miyashita, Tokuji; Mitsuishi, Masaya

2016-04-01

Fluorinated polymer nanoparticle films were prepared by dissolving amphiphilic fluorinated polymer, poly (N-1H, 1H-pentadecafluorooctylmethacrylamide) (pC7F15MAA) in two miscible solvents (AK-225 and acetic acid). A superhydrophobic and porous film was obtained by dropcasting the solution on substrates. With higher ratios of AK-225 to acetic acid, pC7F15MAA was densified around acetic acid droplets, leading to the formation of pC7F15MAA nanoparticles. The condition of the nanoparticle film preparation was investigated by varying the mixing ratio or total concentration. A highly sensitive dissolved oxygen sensor system was successfully prepared utilizing a smart surface of superhydrophobic and porous pC7F15MAA nanoparticle film. The sensitivity showed I0/I40 = 126 in the range of dissolved oxygen concentration of 0 ~ 40 mg L-1. The oxygen sensitivity was compared with that of previous reports.

A Layered Solution Crystal Growth Technique and the Crystal Structure of (C 6H 5C 2H 4NH 3) 2PbCl 4

NASA Astrophysics Data System (ADS)

Mitzi, D. B.

1999-07-01

Single crystals of the organic-inorganic perovskite (C6H5C2H4NH3)2PbCl4 have been grown at room temperature using a layered solution approach. The bottom solution layer, contained within a long straight tube, consists of PbCl2 dissolved in concentrated aqueous HCl. A less dense layer of methanol is carefully placed on top of the HCl/PbCl2 solution using a syringe. Finally, a stoichiometric quantity of C6H5C2H4NH2 (relative to the PbCl2) is added to the top of the column. As the layers slowly diffuse together, well-formed crystals of (C6H5C2H4NH3)2PbCl4 appear near the interface between the HCl/PbCl2 and C6H5C2H4NH2 solutions. The thick, plate-like crystals are well suited for X-ray crystallography studies. Room temperature intensity data were refined using a triclinic (Poverline1) cell (a=11.1463(3) Å, b=11.2181(3) Å, c=17.6966(5) Å, α= 99.173(1)°, β=104.634(1)°, γ=89.999(1)°, V=2111.8(1) Å3, Z=4, Rf/Rw=0.031/0.044). The organic-inorganic layered perovskite structure features well-ordered sheets of corner-sharing distorted PbCl6 octahedra separated by bilayers of phenethylammonium cations. Tilting and rotation of the PbCl6 octahedra within the perovskite sheets, coupled with organic cation ordering, leads to the unusual in-sheet 2ap×2ap superstructure, where ap is the lattice constant for the ideal cubic perovskite.

In situ sensor technology for simultaneous spectrophotometric measurements of seawater total dissolved inorganic carbon and pH.

PubMed

Wang, Zhaohui Aleck; Sonnichsen, Frederick N; Bradley, Albert M; Hoering, Katherine A; Lanagan, Thomas M; Chu, Sophie N; Hammar, Terence R; Camilli, Richard

2015-04-07

A new, in situ sensing system, Channelized Optical System (CHANOS), was recently developed to make high-resolution, simultaneous measurements of total dissolved inorganic carbon (DIC) and pH in seawater. Measurements made by this single, compact sensor can fully characterize the marine carbonate system. The system has a modular design to accommodate two independent, but similar measurement channels for DIC and pH. Both are based on spectrophotometric detection of hydrogen ion concentrations. The pH channel uses a flow-through, sample-indicator mixing design to achieve near instantaneous measurements. The DIC channel adapts a recently developed spectrophotometric method to achieve flow-through CO2 equilibration between an acidified sample and an indicator solution with a response time of only ∼ 90 s. During laboratory and in situ testing, CHANOS achieved a precision of ±0.0010 and ± 2.5 μmol kg(-1) for pH and DIC, respectively. In situ comparison tests indicated that the accuracies of the pH and DIC channels over a three-week time-series deployment were ± 0.0024 and ± 4.1 μmol kg(-1), respectively. This study demonstrates that CHANOS can make in situ, climatology-quality measurements by measuring two desirable CO2 parameters, and is capable of resolving the CO2 system in dynamic marine environments.

Hudson Canyon benthic habitats characterization and mapping by integrated analysis of multidisciplinary data

NASA Astrophysics Data System (ADS)

Pierdomenico, Martina; Guida, Vincent G.; Rona, Peter A.; Macelloni, Leonardo; Scranton, Mary I.; Asper, Vernon; Diercks, Arne

2013-04-01

Hudson Canyon, about 180 km SE of New York City, is the largest eastern U.S. submarine canyon and is under consideration for HAPC (Habitat Area of Particular Concern) status, representing a fisheries and biodiversity hot spot. Interest in the area, within the perspective of ecosystem based management, marine spatial planning, habitat and species conservation, led to a joint project between NOAA Northeast Fisheries, U.S. Geological Survey (USGS), Mississippi Mineral Research Institute (MMRI), National Institute for Undersea Science and Technology (NIUST), Stony Brook and Rutgers Universities for the study of benthic habitats, that includes the assembly of existing data with newly collected ones: acoustic mapping, visual ground-truthing, hydrographic, sedimentological, and trawl data collections. Acoustic mapping, performed using AUV-mounted multibeam sonar, provided ultra-high resolution bathymetric and backscatter imagery (3m and 1m respectively) at all water depths for identification of geomorphological features and for the characterization of surficial sediments along the two thirds of the shelf portion of the canyon. Identification of benthic and demersal communities was accomplished by visual ground thruthing with underwater vehicle video and still cameras, and from trawl catch data. A CTD-rosette sampler provided water column salinity-temperature profiles and water samples for dissolved methane analysis in the vicinity of suspected bottom sources. Analysis of data revealed a complex of topographic structures and hydrological patterns that provide a wide range of physical habitats in a relatively small area. A mosaic of sandy and muddy substrates, gravel beds, rock outcrops, and semilithified clay outcrops host rich and varied faunal assemblages, including deepwater corals and sponge communities. Pockmark fields, occurring below 300 m depth, suggest that methane-based chemosynthetic carbonate deposition contributes to creation of specific hard bottom habitats

The Morpho-Acoustic Structure of Sakarya Canyon, Southwestern Black Sea

NASA Astrophysics Data System (ADS)

Nasıf, Aslıhan; Dondurur, Derman

2017-04-01

In this study, Black Sea outlet of Sakarya River in the western Black Sea continental margin is analyzed using a total of 1400 km multichannel seismics, Chirp sub-bottom profiler and multibeam bathymetric datasets. Three scientific cruises between 2012 and 2016 have been conducted in the area to map and reveal the morphological structure of the Sakarya Canyon along the southwestern Black Sea margin. The Western Black Sea Turkey coastal area is also home to many active canyons. These canyons extend from deep shallow shelf areas of about 100 m to deep water depths of 1800-2000 m. The largest and most active of the Western Black Sea canyons is the Sakarya Canyon, which is located at the exit of the Sakarya River. Research on submarine canyons are important for military submarine operations, positioning of marine engineering structures and understanding the sedimentology, ecological and oceanographic functions of canyons. The canyon systems observed on continental slopes lead to the most convenient sedimentary transportation from the shelf platform. The dataset from study area was analyzed to identify the acoustic structure of Sakarya Canyon, the morphology of which is not widely known. Bathymetric data shows that the canyon consists of two separate canyon heads in the shallow continental shelf to the south, both of which coalesce at 867 m water depth. This meandering canyon then deepens along the continental slope towards to north. Another wide canyon from west, named as Kefken Canyon, then conjoins this main canyon at approximately 1000 m water depths to form the deeper structure of the modern Sakarya Canyon. In the distal parts, canyon gets wider and wider, and its thalweg becomes significantly flat eroded by the present day activity of small scale turbidity channels. Multichannel seismic data indicate that the Sakarya Canyon was formed by the activity of hyperphycnal flows and also clearly show the extensive sediment erosion along the canyon.

Assesment of longwave radiation effects on air quality modelling in street canyons

NASA Astrophysics Data System (ADS)

Soucasse, L.; Buchan, A.; Pain, C.

2016-12-01

Computational Fluid Dynamics is widely used as a predictive tool to evaluate people's exposure to pollutants in urban street canyons. However, in low-wind conditions, flow and pollutant dispersion in the canyons are driven by thermal effects and may be affected by longwave (infrared) radiation due to the absorption and emission of water vapor contained in the air. These effects are mostly ignored in the literature dedicated to air quality modelling at this scale. This study aims at quantifying the uncertainties due to neglecting thermal radiation in air quality models. The Large-Eddy-Simulation of air flow in a single 2D canyon with a heat source on the ground is considered for Rayleigh and Reynolds numbers in the range of [10e8-10e10] and [5.10e3-5.10e4] respectively. The dispersion of a tracer is monitored once the statistically steady regime is reached. Incoming radiation is computed for a mid-latitude summer atmosphere and canyon surfaces are assumed to be black. Water vapour is the only radiating molecule considered and a global model is used to treat the spectral dependancy of its absorption coefficient. Flow and radiation fields are solved in a coupled way using the finite element solvers Fluidity and Fetch which have the capability of adapting their space and angular resolution according to an estimate of the solution error. Results show significant effects of thermal radiation on flow patterns and tracer dispersion. When radiation is taken into account, the air is heated far from the heat source leading to a stronger natural convection flow. The tracer is then dispersed faster out of the canyon potentially decreasing people's exposure to pollution within the street canyon.

The State of the Colorado River Ecosystem in Grand Canyon: A Report of the Grand Canyon Monitoring and Research Center 1991-2004

USGS Publications Warehouse

Gloss, Steven P.; Lovich, Jeffrey E.; Melis, Theodore S.

2005-01-01

This report is an important milestone in the effort by the Secretary of the Interior to implement the Grand Canyon Protection Act of 1992 (GCPA; title XVIII, secs. 1801-1809, of Public Law 102-575), the most recent authorizing legislation for Federal efforts to protect resources downstream from Glen Canyon Dam. The chapters that follow are intended to provide decision makers and the American public with relevant scientific information about the status and recent trends of the natural, cultural, and recreational resources of those portions of Grand Canyon National Park and Glen Canyon National Recreation Area affected by Glen Canyon Dam operations. Glen Canyon Dam is one of the last major dams that was built on the Colorado River and is located just south of the Arizona-Utah border in the lower reaches of Glen Canyon National Recreation Area, approximately 15 mi (24 km) upriver from Grand Canyon National Park (fig. 1). The information presented here is a product of the Glen Canyon Dam Adaptive Management Program (GCDAMP), a federally authorized initiative to ensure that the primary mandate of the GCPA is met through advances in information and resource management. The U.S. Geological Survey`s (USGS) Grand Canyon Monitoring and Research Center (GCMRC) has responsibility for the scientific monitoring and research efforts for the program, including the preparation of reports such as this one.

METHOD FOR DISSOLVING LANTHANUM FLUORIDE CARRIER FOR PLUTONIUM

DOEpatents

Koshland, D.E. Jr.; Willard, J.E.

1961-08-01

A method is described for dissolving lanthanum fluoride precipitates which is applicable to lanthanum fluoride carrier precipitation processes for recovery of plutonium values from aqueous solutions. The lanthanum fluoride precipitate is contacted with an aqueous acidic solution containing dissolved zirconium in the tetravalent oxidation state. The presence of the zirconium increases the lanthanum fluoride dissolved and makes any tetravalent plutonium present more readily oxidizable to the hexavalent state. (AEC)

Reactive solute transport in streams: 2. Simulation of a pH modification experiment

USGS Publications Warehouse

Runkel, Robert L.; McKnight, Diane M.; Bencala, Kenneth E.; Chapra, Steven C.

1996-01-01

We present an application of an equilibrium-based solute transport model to a pH-modification experiment conducted on the Snake River, an acidic, metal-rich stream located in the Rocky Mountains of Colorado. During the experiment, instream pH decreased from 4.2 to 3.2, causing a marked increase in dissolved iron concentrations. Model application requires specification of several parameters that are estimated using tracer techniques, mass balance calculations, and geochemical data. Two basic questions are addressed through model application: (1) What are the processes responsible for the observed increase in dissolved iron concentrations? (2) Can the identified processes be represented within the equilibrium-based transport model? Simulation results indicate that the increase in iron was due to the dissolution of hydrous iron oxides and the photoreduction of ferric iron. Dissolution from the streambed is represented by considering a trace compartment consisting of freshly precipitated hydrous iron oxide and an abundant compartment consisting of aged precipitates that are less soluble. Spatial variability in the solubility of hydrous iron oxide is attributed to heterogeneity in the streambed sediments, temperature effects, and/or variability in the effects of photoreduction. Solubility products estimated via simulation fall within a narrow range (pKsp from 40.2 to 40.8) relative to the 6 order of magnitude variation reported for laboratory experiments (pKsp from 37.3 to 43.3). Results also support the use of an equilibrium-based transport model as the predominate features of the iron and pH profiles are reproduced. The model provides a valuable tool for quantifying the nature and extent of pH-dependent processes within the context of hydrologic transport.

Describing the development of submarine canyons using stream-power erosion laws

NASA Astrophysics Data System (ADS)

Mitchell, N. C.

2004-12-01

-432, 2004. Soh, W., and H. Tokuyama, Rejuvination of submarine canyon associated with ridge subduction, Tenryu Canyon, off Tokai, central Japan, Mar. Geol., 187, 203-230, 2002.

Ventilation Processes in a Three-Dimensional Street Canyon

NASA Astrophysics Data System (ADS)

Nosek, Štěpán; Kukačka, Libor; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

2016-05-01

The ventilation processes in three different street canyons of variable roof geometry were investigated in a wind tunnel using a ground-level line source. All three street canyons were part of an urban-type array formed by courtyard-type buildings with pitched roofs. A constant roof height was used in the first case, while a variable roof height along the leeward or windward walls was simulated in the two other cases. All street-canyon models were exposed to a neutrally stratified flow with two approaching wind directions, perpendicular and oblique. The complexity of the flow and dispersion within the canyons of variable roof height was demonstrated for both wind directions. The relative pollutant removals and spatially-averaged concentrations within the canyons revealed that the model with constant roof height has higher re-emissions than models with variable roof heights. The nomenclature for the ventilation processes according to quadrant analysis of the pollutant flux was introduced. The venting of polluted air (positive fluctuations of both concentration and velocity) from the canyon increased when the wind direction changed from perpendicular to oblique, irrespective of the studied canyon model. Strong correlations (>0.5) between coherent structures and ventilation processes were found at roof level, irrespective of the canyon model and wind direction. This supports the idea that sweep and ejection events of momentum bring clean air in and detrain the polluted air from the street canyon, respectively.

Metal Ion Speciation and Dissolved Organic Matter Composition in Soil Solutions

NASA Astrophysics Data System (ADS)

Benedetti, M. F.; Ren, Z. L.; Bravin, M.; Tella, M.; Dai, J.

2014-12-01

Knowledge of the speciation of heavy metals and the role of dissolved organic matter (DOM) in soil solution is a key to understand metal mobility and ecotoxicity. In this study, soil column-Donnan membrane technique (SC-DMT) was used to measure metal speciation of Cd, Cu, Ni, Pb, and Zn in eighteen soil solutions, covering a wide range of metal sources and concentrations. DOM composition in these soil solutions was also determined. Our results show that in soil solution Pb and Cu are dominant in complex form, whereas Cd, Ni and Zn mainly exist as free ions; for the whole range of soil solutions, only 26.2% of DOM is reactive and consists mainly of fulvic acid (FA). The metal speciation measured by SC-DMT was compared to the predicted ones obtained via the NICA-Donnan model using the measured FA concentrations. The free ion concentrations predicted by speciation modelling were in good agreement with the measurements. Diffusive gradients in thin-films gels (DGT) were also performed to quantify the labile metal species in the fluxes from solid phase to solution in fourteen soils. The concentrations of metal species detected by DGT were compared with the free ion concentrations measured by DMT and the maximum concentrations calculated based on the predicted metal speciation in SC-DMT soil solutions. It is concluded that both inorganic species and a fraction of FA bound species account for the amount of labile metals measured by DGT, consistent with the dynamic features of this technique. The comparisons between measurements using analytical techniques and mechanistic model predictions provided mutual validation in their performance. Moreover, we show that to make accurate modelling of metal speciation in soil solutions, the knowledge of DOM composition is the crucial information, especially for Cu; like in previous studies the modelling of Pb speciation is not optimal and an updated of Pb generic binding parameters is required to reduce model prediction uncertainties.

Dissolution of aragonite-strontianite solid solutions in nonstoichiometric Sr (HCO3)2-Ca (HCO3)2-CO2-H2O solutions

USGS Publications Warehouse

Plummer, Niel; Busenberg, E.; Glynn, P.D.; Blum, A.E.

1992-01-01

Synthetic strontianite-aragonite solid-solution minerals were dissolved in CO2-saturated non-stoichiometric solutions of Sr(HCO3)2 and Ca(HCO3)2 at 25??C. The results show that none of the dissolution reactions reach thermodynamic equilibrium. Congruent dissolution in Ca(HCO3)2 solutions either attains or closely approaches stoichiometric saturation with respect to the dissolving solid. In Sr(HCO3)2 solutions the reactions usually become incongruent, precipitating a Sr-rich phase before reaching stoichiometric saturation. Dissolution of mechanical mixtures of solids approaches stoichiometric saturation with respect to the least stable solid in the mixture. Surface uptake from subsaturated bulk solutions was observed in the initial minutes of dissolution. This surficial phase is 0-10 atomic layers thick in Sr(HCO3)2 solutions and 0-4 layers thick in Ca(HCO3)2 solutions, and subsequently dissolves and/or recrystallizes, usually within 6 min of reaction. The initial transient surface precipitation (recrystallization) process is followed by congruent dissolution of the original solid which proceeds to stoichiometric saturation, or until the precipitation of a more stable Sr-rich solid. The compositions of secondary precipitates do not correspond to thermodynamic equilibrium or stoichiometric saturation states. X-ray photoelectron spectroscopy (XPS) measurements indicate the formation of solid solutions on surfaces of aragonite and strontianite single crystals immersed in Sr(HCO3)2 and Ca(HCO3)2 solutions, respectively. In Sr(HCO3)2 solutions, the XPS signal from the outer ~ 60 A?? on aragonite indicates a composition of 16 mol% SrCO3 after only 2 min of contact, and 14-18 mol% SrCO3 after 3 weeks of contact. The strontianite surface averages approximately 22 mol% CaCO3 after 2 min of contact with Ca(HCO3)2 solution, and is 34-39 mol% CaCO3 after 3 weeks of contact. XPS analysis suggests the surface composition is zoned with somewhat greater enrichment in the outer ~25

Geology and biology of Oceanographer submarine canyon.

USGS Publications Warehouse

Valentine, P.C.; Uzmann, J.R.; Cooper, R.A.

1980-01-01

Santonian beds more than 100 m thick are the oldest rocks collected from the canyon. Quaternary silty clay veneers the canyon walls in many places and is commonly burrowed by benthic organisms that cause extensive erosion of the canyon walls, especially in the depth zone (100-1300 m) inhabited by the crabs Geryon and Cancer. Bioerosion is minimal on high, near-vertical cliffs of sedimentary rock, in areas of continual sediment movement, and where the sea floor is paved by gravel. A thin layer of rippled, unconsolidated silt and sand is commonly present on the canyon walls and in the axis. Shelf sediments are transported from Georges Bank over the E rim and in the Canyon by the SW drift and storm currents; tidal currents and internal waves move the sediment downcanyon along the walls and axis.- from Authors

Discovery of two new large submarine canyons in the Bering Sea

USGS Publications Warehouse

Carlson, P.R.; Karl, Herman A.

1984-01-01

The Beringian continental margin is incised by some of the world's largest submarine canyons. Two newly discovered canyons, St. Matthew and Middle, are hereby added to the roster of Bering Sea canyons. Although these canyons are smaller and not cut back into the Bering shelf like the five very large canyons, they are nonetheless comparable in size to most of the canyons that have been cut into the U.S. eastern continental margin and much larger than the well-known southern California canyons. Both igneous and sedimentary rocks of Eocene to Pliocene age have been dredged from the walls of St. Matthew and Middle Canyons as well as from the walls of several of the other Beringian margin canyons, thus suggesting a late Tertiary to Quaternary genesis of the canyons. We speculate that the ancestral Yukon and possibly Anadyr Rivers were instrumental in initiating the canyon-cutting processes, but that, due to restrictions imposed by island and subsea bedrock barriers, cutting of the two newly discovered canyons may have begun later and been slower than for the other five canyons. ?? 1984.

Chapter 12. Canyons microbiology studies

USGS Publications Warehouse

Kellogg, Christina A.; Lawler, Stephanie N.

2017-01-01

Off the eastern coast of the United States, several deep canyons cut through the continental shelf, acting like funnels to move sediment from the shelf out to the deep seafloor. Exposed rock outcrops and ledges along the walls of these canyons provide important habitat for deepsea corals and sponges. Although a few scientific expeditions have visited these canyons in the 1970s (Hecker and Blechschmidt 1979, Hecker et al. 1980), their purpose was mainly to map the contours and capture photographs of the bottom using manned submersibles and towed cameras. Our knowledge of the biodiversity in these complex ecosystems is limited; we know little about the macrofauna (e.g., fishes, crabs, sponges, and deepsea corals) and even less about the microbiota.The research described in this report was conducted from 2011 to 2015 as part of the Bureau of Ocean Energy Management (BOEM) study, entitled “Atlantic Deepwater Canyons” study. This work used molecular and microbiological techniques to examine the microbial ecology and diversity associated with Baltimore and Norfolk canyons. Specifically, this work focused on the microbial ecology of four species of octocorals (Acanthogorgia aspera, Anthothela grandiflora, Paramuricea placomus, and Primnoa resedaeformis), the microbial diversity in sediments within and outside the canyons, and a settling plate experiment designed to characterize microbial biofilm formation on a variety of hard substrates.

36 CFR 7.19 - Canyon de Chelly National Monument.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Canyon de Chelly National... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.19 Canyon de Chelly National Monument. (a) Visitors are prohibited from entering the canyons of Canyon de Chelly National Monument unless...

36 CFR 7.19 - Canyon de Chelly National Monument.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Canyon de Chelly National... INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.19 Canyon de Chelly National Monument. (a) Visitors are prohibited from entering the canyons of Canyon de Chelly National Monument unless...

2008 High-Flow Experiment at Glen Canyon Dam Benefits Colorado River Resources in Grand Canyon National Park

USGS Publications Warehouse

Melis, Theodore S.; Topping, David J.; Grams, Paul E.; Rubin, David M.; Wright, Scott A.; Draut, Amy E.; Hazel, Joseph E.; Ralston, Barbara E.; Kennedy, Theodore A.; Rosi-Marshall, Emma; Korman, Josh; Hilwig, Kara D.; Schmit, Lara M.

2010-01-01

On March 5, 2008, the Department of the Interior began a 60-hour high-flow experiment at Glen Canyon Dam, Arizona, to determine if water releases designed to mimic natural seasonal flooding could be used to improve downstream resources in Glen Canyon National Recreation Area and Grand Canyon National Park. U.S. Geological Survey (USGS) scientists and their cooperators undertook a wide range of physical and biological resource monitoring and research activities before, during, and after the release. Scientists sought to determine whether or not high flows could be used to rebuild Grand Canyon sandbars, create nearshore habitat for the endangered humpback chub, and benefit other resources such as archaeological sites, rainbow trout, aquatic food availability, and riverside vegetation. This fact sheet summarizes research completed by January 2010.

A reconnaissance of the effects of a forest fire on water quality in Kings Canyon National Park, California

USGS Publications Warehouse

Hoffman, Ray J.; Ferreira, Rodger F.

1976-01-01

Following two forest fires in the Roaring River drainage basin, Kings Canyon National Park, Calif., water samples were collected from May to July 1974 to determine water-quality changes resulting from the fires. Field measurements included alkalinity , pH, specific conductance, temperature, and discharge. Samples were analyzed in the laboratory for major dissolved chemical constituents, selected plant nutrients, trace metals, suspended sediment, total organic carbon, and seston. Periphytic algae and benthic invertebrate samples were collected. A noticeable increase in the concentration of nitrogen was found in Roaring River immediately downstream from the Moraine Creek fire. The increase in the concentration of inorganic nitrogen compounds, however, was not great enough to pose a serious threat to the aquatic ecosystem. High total organic nitrogen concentrations may have been due, in part, to factors other than the effect of fire. The results of other water-quality measurements were typical of dilute Sierra Nevada streams and indicate that Roaring River was not adversely affected by the fires. (Woodard-USGS)

VOLATILECALC: A silicate melt-H2O-CO2 solution model written in Visual Basic for excel

USGS Publications Warehouse

Newman, S.; Lowenstern, J. B.

2002-01-01

We present solution models for the rhyolite-H2O-CO2 and basalt-H2O-CO2 systems at magmatic temperatures and pressures below ~ 5000 bar. The models are coded as macros written in Visual Basic for Applications, for use within MicrosoftR Excel (Office'98 and 2000). The series of macros, entitled VOLATILECALC, can calculate the following: (1) Saturation pressures for silicate melt of known dissolved H2O and CO2 concentrations and the corresponding equilibrium vapor composition; (2) open- and closed-system degassing paths (melt and vapor composition) for depressurizing rhyolitic and basaltic melts; (3) isobaric solubility curves for rhyolitic and basaltic melts; (4) isoplethic solubility curves (constant vapor composition) for rhyolitic and basaltic melts; (5) polybaric solubility curves for the two end members and (6) end member fugacities of H2O and CO2 vapors at magmatic temperatures. The basalt-H2O-CO2 macros in VOLATILECALC are capable of calculating melt-vapor solubility over a range of silicate-melt compositions by using the relationships provided by Dixon (American Mineralogist 82 (1997) 368). The output agrees well with the published solution models and experimental data for silicate melt-vapor systems for pressures below 5000 bar. ?? 2002 Elsevier Science Ltd. All rights reserved.

Morphodynamic Model of Submarine Canyon Incision by Sandblasting

NASA Astrophysics Data System (ADS)

Zhang, L.; Parker, G.; Izumi, N.; Cartigny, M.; Li, T.; Wang, G.

2017-12-01

Submarine canyons are carved by turbidity currents under the deep sea. As opposed to subaerial canyons, the relevant processes are not easy to observe directly. Turbidity currents are bottom-hugging sediment gravity flows of that can incise or deposit on the seafloor to create submarine canyons or fans. The triggers of turbidity currents can be storms, edge waves, internal waves, canyon wall sapping, delta failure, breaching and hyperpycnal flows. The formation and evolution mechanisms of submarine canyons are similar to those of subaerial canyons, but have substantial differences. For example, sandblasting, rather than wear due to colliding gravel clasts is more likely to be the mechanism of bedrock incision. Submarine canyons incise downward, and often develop meander bends and levees within the canyon, so defining "fairways". Here we propose a simple model for canyon incision. The starting point of our model is the Macro Roughness Saltation Abrasion Alluviation model of Zhang et al. [2015], designed for bedrock incision by gravel clasts in mixed bedrock-alluvial rivers. We adapt this formulation to consider sandblasting as a means of wear. We use a layer-averaged model for turbidity current dynamics. The current contains a mixture of mud, which helps drive the flow but which does not cause incision, and sand, which is the agent of incision. We show that the model can successfully model channel downcutting, and indeed illustrate the early formation of net incisional cyclic steps, i.e. upstream-migrating undulations on the bed associated with transcritical (in the Froude sense) flow. These steps can be expected to abet the process of incision.

Net acidity indicates the whole effluent toxicity of pH and dissolved metals in metalliferous saline waters.

PubMed

Degens, Bradley P; Krassoi, Rick; Galvin, Lynette; Reynolds, Brad; Micevska, Tina

2018-05-01

Measurements of potential acidity in water are used to manage aquatic toxicity risks of discharge from acid sulfate soils or acid mine drainage. Net acidity calculated from pH, dissolved metals and alkalinity is a common measurement of potential acidity but the relevance of current risk thresholds to aquatic organisms are unclear. Aquatic toxicity testing was carried out using four halophytic organisms with water from four saline sources in southern Western Australia (3 acidic drains and one alkaline river; 39-40 g TDS/L) where acidity was varied by adjusting pH to 4.5-6.5. The test species were brine shrimps (Artemia salina), locally sourced ostracods (Platycypris baueri), microalgae (Dunaliella salina) and amphipods (Allorchestes compressa). Testing found the EC 10 and IC 10 of net acidity ranged from -7.8 to 10.5 mg CaCO 3 /L with no survival or growth of any species at >47 mg CaCO 3 /L. Reduced net acidity indicated reduced whole effluent toxicity more reliably than increased pH alone with organisms tolerating pH up to 1.1 units lower in the absence of dissolved metals. Variation in toxicity indicated by net acidity was mostly attributed to reduced concentrations of dissolved Al and Fe combined with higher pH and alkalinity and some changes in speciation of Al and Fe with pH. These results indicate that rapid in-field assessments of net acidity in acidic, Al dominated waters may be an indicator of potential acute and sub-chronic impacts on aquatic organisms. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Internal wave scattering in continental slope canyons, part 1: Theory and development of a ray tracing algorithm

NASA Astrophysics Data System (ADS)

Nazarian, Robert H.; Legg, Sonya

2017-10-01

When internal waves interact with topography, such as continental slopes, they can transfer wave energy to local dissipation and diapycnal mixing. Submarine canyons comprise approximately ten percent of global continental slopes, and can enhance the local dissipation of internal wave energy, yet parameterizations of canyon mixing processes are currently missing from large-scale ocean models. As a first step in the development of such parameterizations, we conduct a parameter space study of M2 tidal-frequency, low-mode internal waves interacting with idealized V-shaped canyon topographies. Specifically, we examine the effects of varying the canyon mouth width, shape and slope of the thalweg (line of lowest elevation). This effort is divided into two parts. In the first part, presented here, we extend the theory of 3-dimensional internal wave reflection to a rotated coordinate system aligned with our idealized V-shaped canyons. Based on the updated linear internal wave reflection solution that we derive, we construct a ray tracing algorithm which traces a large number of rays (the discrete analog of a continuous wave) into the canyon region where they can scatter off topography. Although a ray tracing approach has been employed in other studies, we have, for the first time, used ray tracing to calculate changes in wavenumber and ray density which, in turn, can be used to calculate the Froude number (a measure of the likelihood of instability). We show that for canyons of intermediate aspect ratio, large spatial envelopes of instability can form in the presence of supercritical sidewalls. Additionally, the canyon height and length can modulate the Froude number. The second part of this study, a diagnosis of internal wave scattering in continental slope canyons using both numerical simulations and this ray tracing algorithm, as well as a test of robustness of the ray tracing, is presented in the companion article.

Associations between benthic flora and diel changes in dissolved arsenic, phosphorus, and related physico-chemical parameters

USGS Publications Warehouse

Kuwabara, James S.

1992-01-01

Diel relationships between physical and chemical parameters and biomass were examined along a 57-km reach of Whitewood Creek, South Dakota, between 29 August and 2 September 1988. A time lag of ∼3-6 h for fluctuations in soluble reactive phosphorus (SRP) concentrations (ranging from 0.1 to 0.5 μM at the downstream sites) relative to dissolved arsenic (ranging from 0.3 to 1.2 μM as arsenate (pentavalent arsenic)) was consistent with our laboratory studies (reported elsewhere) showing preferential cell sorption of orthophosphate over arsenate by creek periphyton. The potential biological effects on SRP diel fluctuations contrasts with abiotic sorption controls for dissolved arsenate (a chemically similar anion). Cycles for pH, like water temperature cycles, lagged irradiance cycles by 1-3 h. Like pH, the amplitude of dissolved arsenic diel cycles was greatest at the site with most abundant biomass. Diel fluctuations in specific conductance (an indicator of groundwater inputs at elevated conductivity relative to the water column) were out of phase with both SRP and dissolved arsenic concentrations suggesting that groundwater was not the direct source of these solutes.

Phenomenological aspects of fatigue cracking in as-received and hardened F82H modified steel exposed to lithiated water with dissolved hydrogen at 240°C

NASA Astrophysics Data System (ADS)

Maday, Marie-Françoise

2000-12-01

The low cycle fatigue (LCF) behaviour of F82H modified steel with three different degrees of hardness produced by specific thermal treatments has been investigated at 240°C under load control, in oxygen-free lithiated solutions containing either no or 2 ppm dissolved hydrogen. In all cases, it was found that the aqueous environments reduced the fatigue life of the material and promoted fracture modes different from those observed in air tests; the fracture modes comprised intergranular and transgranular quasi-cleavage separations as well as microvoid coalescence, which depended on material conditions and water chemistry. All these features were ascribed to a hydrogen-assisted-cracking (HAC) phenomenon, as the basic mechanism for controlling the fatigue behaviour of various F82H heats in lithiated solutions. The observed differences in HAC paths are discussed from the standpoint of material microstructural and substructural parameters.

Surprise and opportunity for learning in Grand Canyon: the Glen Canyon Dam Adaptive Management Program

USGS Publications Warehouse

Melis, Theodore S.; Walters, Carl; Korman, Josh

2015-01-01

With a focus on resources of the Colorado River ecosystem below Glen Canyon Dam, the Glen Canyon Dam Adaptive Management Program has included a variety of experimental policy tests, ranging from manipulation of water releases from the dam to removal of non-native fish within Grand Canyon National Park. None of these field-scale experiments has yet produced unambiguous results in terms of management prescriptions. But there has been adaptive learning, mostly from unanticipated or surprising resource responses relative to predictions from ecosystem modeling. Surprise learning opportunities may often be viewed with dismay by some stakeholders who might not be clear about the purpose of science and modeling in adaptive management. However, the experimental results from the Glen Canyon Dam program actually represent scientific successes in terms of revealing new opportunities for developing better river management policies. A new long-term experimental management planning process for Glen Canyon Dam operations, started in 2011 by the U.S. Department of the Interior, provides an opportunity to refocus management objectives, identify and evaluate key uncertainties about the influence of dam releases, and refine monitoring for learning over the next several decades. Adaptive learning since 1995 is critical input to this long-term planning effort. Embracing uncertainty and surprise outcomes revealed by monitoring and ecosystem modeling will likely continue the advancement of resource objectives below the dam, and may also promote efficient learning in other complex programs.

Nitrogen solutes in an Adirondack forested watershed: Importance of dissolved organic nitrogen

USGS Publications Warehouse

McHale, M.R.; Mitchell, M.J.; McDonnell, Jeffery J.; Cirmo, C.P.

2000-01-01

Nitrogen (N) dynamics were evaluated from 1 June 1995 through 31 May 1996 within the Arbutus Lake watershed in the Adirondack Mountains of New York State, U.S.A. At the Arbutus Lake outlet dissolved organic nitrogen (DON), NO3/- and NH4/+ contributed 61%, 33%, and 6% respectively, to the total dissolved nitrogen (TDN) flux (259 mol ha-1 yr-1). At the lake inlet DON, NO3/-, and NH4/+ constituted 36%, 61%, and 3% respectively, of TDN flux (349 mol ha-1 yr-1). Differences between the factors that control DON, NO3/-, and NH4+ stream water concentrations were evaluated using two methods for estimating annual N flux at the lake inlet. Using biweekly sampling NO3/- and NH4/+ flux was 10 and 4 mol ha-1 yr-1 respectively, less than flux estimates using biweekly plus storm and snowmelt sampling. DON flux was 18 mol ha-1 yr-1 greater using only biweekly sampling. These differences are probably not of ecological significance relative to the total flux of N from the watershed (349 mol ha-1 yr-1). Dissolved organic N concentrations were positively related to discharge during both the dormant (R2 = 0.31; P<0.01) and growing season (R2= 0.09; P<0.01). There was no significant relationship between NO3/- concentration and discharge during the dormant season, but a significant negative relationship was found during the growing season (R2 = 0.29; P<0.01). Biotic controls in the growing season appeared to have had a larger impact on stream water NO3- concentrations than on DON concentrations. Arbutus Lake had a major impact on stream water N concentrations of the four landscape positions sampled, suggesting the need to quantify within lake processes to interpret N solute losses and patterns in watershed-lake systems.

Dissolved and particulate Barium in the Ganga (Hooghly) River estuary, India: Solute-particle interactions and the enhanced dissolved flux to the oceans

NASA Astrophysics Data System (ADS)

Samanta, Saumik; Dalai, Tarun K.

2016-12-01

In this study, the sources and the cycling of Ba have been evaluated in the Ganga (Hooghly) River estuary using the composition of the suspended sediments and the water samples collected during six seasons of contrasting water discharge over two years (2012 and 2013). In addition, the data on the samples of groundwater from areas adjacent to the estuary, and the industrial effluent water and urban wastewater draining into the estuary are presented. Selective extraction experiments were also performed on the suspended particulate matter of two seasons to assess the distribution of exchangeable concentrations of major ions and Ba. In the mixing zone, the variation patterns of the dissolved Ba concentrations show mid-salinity maxima and are similar to the patterns of variation of the particulate Mg/Al and Mg/Fe, suggesting that the production of dissolved Ba is linked to the adsorption of major ions on to the clay minerals and Fe-Mn oxyhydroxides in the particulate matter. The inference of coupled adsorption-desorption processes is supported by the observations that the particulate Ba/Mg and Ba/K ratios exhibit significant to strong negative correlations with the concentrations of Al, Fe and Mn. The observations of mid-salinity maxima for the concentrations of exchangeable Mg and K, and of the exchangeable Ba concentrations that decrease with salinity provide strong evidence that the solute-particle interactions is the major driver in regulating the dissolved Ba distributions in the estuary. The estimates of the quantity of desorbed Ba based on three different approaches suggest that desorption is sufficient to account for the calculated excess Ba (Baxs) concentrations. The contribution of Ba to the dissolved load via dissolution of the particulate carbonate phases is minor, up to 3% of the maximum Baxs concentrations. The estimates of anthropogenic contributions are insignificant, and account for ⩽2% of maximum Baxs in the estuary. Groundwater contributions are

Dually Fluorescent Sensing of pH and Dissolved Oxygen Using a Membrane Made from Polymerizable Sensing Monomers.

PubMed

Tian, Yanqing; Shumway, Bradley R; Youngbull, A Cody; Li, Yongzhong; Jen, Alex K-Y; Johnson, Roger H; Meldrum, Deirdre R

2010-06-03

Using a thermal polymerization approach and polymerizable pH and oxygen sensing monomers with green and red emission spectra, respectively, new pH, oxygen, and their dual sensing membranes were prepared using poly(2-hydroxyethyl methacrylate)-co-poly(acrylamide) as a matrix. The sensors were grafted on acrylate-modified quartz glass and characterized under different pH values, oxygen concentrations, ion strengths, temperatures and cell culture media. The pH and oxygen sensors were excited using the same excitation wavelength and exhibited well-separated emission spectra. The pH-sensing films showed good response over the pH range 5.5 to 8.5, corresponding to pK(a) values in the biologically-relevant range between 6.9 and 7.1. The oxygen-sensing films exhibited linear Stern-Volmer quenching responses to dissolved oxygen. As the sensing membranes were prepared using thermally initiated polymerization of sensing moiety-containing monomers, no leaching of the sensors from the membranes to buffers or medium was observed. This advantageous characteristic accounts in part for the sensors' biocompatibility without apparent toxicity to HeLa cells after 40 hours incubation. The dual-sensing membrane was used to measure pH and dissolved oxygen simultaneously. The measured results correlated with the set-point values.

Reconstructing the evolution of the submarine Monterey Canyon System from Os, Nd, and Pb isotopes in hydrogenetic Fe-Mn crusts

USGS Publications Warehouse

Conrad, T.A.; Nielsen, S.G.; Peucker-Ehrenbrink, Bernhard; Blusztajn, J.; Winslow, D.; Hein, James; Paytan, A.

2017-01-01

The sources of terrestrial material delivered to the California margin over the past 7 Myr were assessed using 187Os/188Os, Nd, and Pb isotopes in hydrogenetic ferromanganese crusts from three seamounts along the central and southern California margin. From 6.8 to 4.5 (± 0.5) Ma, all three isotope systems show more radiogenic values at Davidson Seamount, located near the base of the Monterey Canyon System, than in Fe-Mn crusts from the more remote Taney and Hoss seamounts. At the Taney seamounts, approximately 225 km farther offshore from Davidson Seamount, 187Os/188Os values, but not Pb and Nd isotope ratios, also deviate from the Cenozoic seawater curve towards more radiogenic values from 6.8 to 4.5 (± 0.5) Ma. However, none of the isotope systems in Fe-Mn crusts deviate from seawater at Hoss Seamount located approximately 450 km to the south. The regional gradients in isotope ratios indicate that substantial input of dissolved and particulate terrestrial material into the Monterey Canyon System is responsible for the local deviations in the seawater Nd, Pb, and Os isotope compositions from 6.8 to 4.5 (± 0.5) Ma. The isotope ratios recorded in Fe-Mn crusts are consistent with a southern Sierra Nevada or western Basin and Range provenance of the terrestrial material which was delivered by rivers to the canyon. The exhumation of the modern Monterey Canyon must have begun between 10 and 6.8 ± 0.5 Ma, as indicated by our data, the age of incised strata, and paleo-location of the Monterey Canyon relative to the paleo-coastline.

Reconstructing the Evolution of the Submarine Monterey Canyon System From Os, Nd, and Pb Isotopes in Hydrogenetic Fe-Mn Crusts

NASA Astrophysics Data System (ADS)

Conrad, T. A.; Nielsen, S. G.; Peucker-Ehrenbrink, B.; Blusztajn, J.; Winslow, D.; Hein, J. R.; Paytan, A.

2017-11-01

The sources of terrestrial material delivered to the California margin over the past 7 Myr were assessed using 187Os/188Os, Nd, and Pb isotopes in hydrogenetic ferromanganese crusts from three seamounts along the central and southern California margin. From 6.8 to 4.5 (±0.5) Ma, all three isotope systems show more radiogenic values at Davidson Seamount, located near the base of the Monterey Canyon System, than in Fe-Mn crusts from the more remote Taney and Hoss Seamounts. At the Taney Seamounts, approximately 225 km farther offshore from Davidson Seamount, 187Os/188Os values, but not Pb and Nd isotope ratios, also deviate from the Cenozoic seawater curve toward more radiogenic values from 6.8 to 4.5 (±0.5) Ma. However, none of the isotope systems in Fe-Mn crusts deviate from seawater at Hoss Seamount located approximately 450 km to the south. The regional gradients in isotope ratios indicate that substantial input of dissolved and particulate terrestrial material into the Monterey Canyon System is responsible for the local deviations in the seawater Nd, Pb, and Os isotope compositions from 6.8 to 4.5 (±0.5) Ma. The isotope ratios recorded in Fe-Mn crusts are consistent with a southern Sierra Nevada or western Basin and Range provenance of the terrestrial material which was delivered by rivers to the canyon. The exhumation of the modern Monterey Canyon must have begun between 10 and 6.8 ± 0.5 Ma, as indicated by our data, the age of incised strata, and paleo-location of the Monterey Canyon relative to the paleo-coastline.

Impact of height and shape of building roof on air quality in urban street canyons

NASA Astrophysics Data System (ADS)

Yassin, Mohamed F.

2011-09-01

A building's roof shape and roof height play an important role in determining pollutant concentrations from vehicle emissions and its complex flow patterns within urban street canyons. The impact of the roof shape and height on wind flow and dispersion of gaseous pollutants from vehicle exhaust within urban canyons were investigated numerically using a Computational Fluid Dynamics (CFD) model. Two-dimensional flow and dispersion of gaseous pollutants were analyzed using standard κ- ɛ turbulence model, which was numerically solved based on Reynolds Averaged Navier-Stokes (RANS) equations. The diffusion fields in the urban canyons were examined with three roof heights ( Z H/ H = 0.17, 0.33 and 0.5) and five roof shapes: (1) flat-shaped roof, (2) slanted-shaped roof, (3) downwind wedge-shaped roof, (4) upwind wedge-shaped roof, and (5) trapezoid-shaped roof. The numerical model was validated against the wind tunnels results in order to optimize the turbulence model. The numerical simulations agreed reasonably with the wind tunnel results. The results obtained indicated that the pollutant concentration increased as the roof height decreases. It also decreased with the slanted and trapezoid-shaped roofs but increased with the flat-shaped roof. The pollutant concentration distributions simulated in the present work, indicated that the variability of the roof shapes and roof heights of the buildings are important factors for estimating air quality within urban canyons.

Anatomy of La Jolla submarine canyon system; offshore southern California

USGS Publications Warehouse

Paull, C.K.; Caress, D.W.; Lundsten, E.; Gwiazda, R.; Anderson, K.; McGann, M.; Conrad, J.; Edwards, B.; Sumner, E.J.

2013-01-01

An autonomous underwater vehicle (AUV) carrying a multibeam sonar and a chirp profiler was used to map sections of the seafloor within the La Jolla Canyon, offshore southern California, at sub-meter scales. Close-up observations and sampling were conducted during remotely operated vehicle (ROV) dives. Minisparker seismic-reflection profiles from a surface ship help to define the overall geometry of the La Jolla Canyon especially with respect to the pre-canyon host sediments. The floor of the axial channel is covered with unconsolidated sand similar to the sand on the shelf near the canyon head, lacks outcrops of the pre-canyon host strata, has an almost constant slope of 1.0° and is covered with trains of crescent shaped bedforms. The presence of modern plant material entombed within these sands confirms that the axial channel is presently active. The sand on the canyon floor liquefied during vibracore collection and flowed downslope, illustrating that the sediment filling the channel can easily fail even on this gentle slope. Data from the canyon walls help constrain the age of the canyon and extent of incision. Horizontal beds of moderately cohesive fine-grained sediments exposed on the steep canyon walls are consistently less than 1.232 million years old. The lateral continuity of seismic reflectors in minisparker profiles indicate that pre-canyon host strata extend uninterrupted from outside the canyon underneath some terraces within the canyon. Evidence of abandoned channels and point bar-like deposits are noticeably absent on the inside bend of channel meanders and in the subsurface of the terraces. While vibracores from the surface of terraces contain thin (< 10 cm) turbidites, they are inferred to be part of a veneer of recent sediment covering pre-canyon host sediments that underpin the terraces. The combined use of state of the art seafloor mapping and exploration tools provides a uniquely detailed view of the morphology within an active submarine canyon.

The influence of pH on biotite dissolution and alteration kinetics at low temperature

USGS Publications Warehouse

Acker, James G.; Bricker, O.P.

1992-01-01

Biotite dissolution rates in acidic solutions were determined in fluidized-bed reactors and flowthrough columns. Biotite dissolution rates increased inversely as a linear function of pH in the pH range 3-7, where the rate order n = -0.34. Biotite dissolved incongruently over this pH range, with preferential release of magnesium and iron from the octahedral layer. Release of tetrahedral silicon was much greater at pH 3 than at higher pH. Iron release was significantly enhanced by low pH conditions. Solution compositions from a continuous exposure flow-through column of biotite indicated biotite dissolves incongruently at pH 4, consistent with alteration to a vermiculite-type product. Solution compositions from a second intermittent-flow column exhibited elevated cation release rates upon the initiation of each exposure to solution. The presence of strong oxidizing agents, the mineral surface area, and sample preparation methodology also influenced the dissolution or alteration kinetics of biotite. ?? 1992.

Bottom-trawling along submarine canyons impacts deep sedimentary regimes.

PubMed

Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

2017-02-24

Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons' morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20 th century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities.

Hot Canyon

ScienceCinema

None

2018-05-07

This historical film footage, originally produced in the early 1950s as part of a series by WOI-TV, shows atomic research at Ames Laboratory. The work was conducted in a special area of the Laboratory known as the "Hot Canyon".

Aerodynamic effects of trees on pollutant concentration in street canyons.

PubMed

Buccolieri, Riccardo; Gromke, Christof; Di Sabatino, Silvana; Ruck, Bodo

2009-09-15

This paper deals with aerodynamic effects of avenue-like tree planting on flow and traffic-originated pollutant dispersion in urban street canyons by means of wind tunnel experiments and numerical simulations. Several parameters affecting pedestrian level concentration are investigated, namely plant morphology, positioning and arrangement. We extend our previous work in this novel aspect of research to new configurations which comprise tree planting of different crown porosity and stand density, planted in two rows within a canyon of street width to building height ratio W/H=2 with perpendicular approaching wind. Sulfur hexafluoride was used as tracer gas to model the traffic emissions. Complementary to wind tunnel experiments, 3D numerical simulations were performed with the Computational Fluid Dynamics (CFD) code FLUENT using a Reynolds Stress turbulence closure for flow and the advection-diffusion method for concentration calculations. In the presence of trees, both measurements and simulations showed considerable larger pollutant concentrations near the leeward wall and slightly lower concentrations near the windward wall in comparison with the tree-less case. Tree stand density and crown porosity were found to be of minor importance in affecting pollutant concentration. On the other hand, the analysis indicated that W/H is a more crucial parameter. The larger the value of W/H the smaller is the effect of trees on pedestrian level concentration regardless of tree morphology and arrangement. A preliminary analysis of approaching flow velocities showed that at low wind speed the effect of trees on concentrations is worst than at higher speed. The investigations carried out in this work allowed us to set up an appropriate CFD modelling methodology for the study of the aerodynamic effects of tree planting in street canyons. The results obtained can be used by city planners for the design of tree planting in the urban environment with regard to air quality issues.

Intake of water with high levels of dissolved hydrogen (H2) suppresses ischemia-induced cardio-renal injury in Dahl salt-sensitive rats.

PubMed

Zhu, Wan-Jun; Nakayama, Masaaki; Mori, Takefumi; Nakayama, Keisuke; Katoh, Junichiro; Murata, Yaeko; Sato, Toshinobu; Kabayama, Shigeru; Ito, Sadayoshi

2011-07-01

Hydrogen (H(2)) reportedly produces an antioxidative effect by quenching cytotoxic oxygen radicals. We studied the biological effects of water with dissolved H(2) on ischemia-induced cardio-renal injury in a rat model of chronic kidney disease (CKD). Dahl salt-sensitive rats (7 weeks old) were allowed ad libitum drinking of filtered water (FW: dissolved H(2), 0.00 ± 0.00 mg/L) or water with dissolved H(2) produced by electrolysis (EW: dissolved H(2), 0.35 ± 0.03 mg/L) for up to 6 weeks on a 0.5% salt diet. The rats then underwent ischemic reperfusion (I/R) of one kidney and were killed a week later for investigation of the contralateral kidney and the heart. In the rats given FW, unilateral kidney I/R induced significant increases in plasma monocyte chemoattractant protein-1, methylglyoxal and blood urea nitrogen. Histologically, significant increases were found in glomerular adhesion, cardiac fibrosis, number of ED-1 (CD68)-positive cells and nitrotyrosine staining in the contralateral kidney and the heart. In rats given EW, those findings were significantly ameliorated and there were significant histological differences between rats given FW and those given EW. Consumption of EW by ad libitum drinking has the potential to ameliorate ischemia-induced cardio-renal injury in CKD model rats. This indicates a novel strategy of applying H(2) produced by water electrolysis technology for the prevention of CKD cardio-renal syndrome.

Recreational impacts on Colorado River beaches in Glen Canyon, Arizona

NASA Astrophysics Data System (ADS)

Carothers, Steven W.; Johnson, Robert A.; Dolan, Robert

1984-07-01

Recreational impact was measured on eight beaches in Glen Canyon National Recreation Area and 15 beaches in Grand Canyon National Park using permanently located transects and plots. Recreational impact indices included densities of human trash and charcoal and a measure of sand discoloration due to charcoal. Significant increases in the indices occurred on several Glen Canyon beaches over a seven-month period. Sand discoloration became significantly higher over all Glen Canyon beaches during the same time period. All indices were significantly higher in Glen Canyon than on similar Grand Canyon beaches. These differences are probably due to differences in: (a) level of impacts tolerated by the respective management regimes and, (b) in the number of user days among the two National Park Service administrative units. Management alternatives are presented for reversing the present trends of recreational impact on Glen Canyon beaches.

[Effects of forest regeneration patterns on the quantity and chemical structure of soil solution dissolved organic matter in a subtropical forest.

PubMed

Yuan, Xiao Chun; Lin, Wei Sheng; Pu, Xiao Ting; Yang, Zhi Rong; Zheng, Wei; Chen, Yue Min; Yang, Yu Sheng

2016-06-01

Using the negative pressure sampling method, the concentrations and spectral characte-ristics of dissolved organic matter (DOM) of soil solution were studied at 0-15, 15-30, 30-60 cm layers in Castanopsis carlesii forest (BF), human-assisted naturally regenerated C. carlesii forest (RF), C. carlesii plantation (CP) in evergreen broad-leaved forests in Sanming City, Fujian Pro-vince. The results showed that the overall trend of dissolved organic carbon (DOC) concentrations in soil solution was RF>CP>BF, and the concentration of dissolved organic nitrogen (DON) was highest in C. carlesii plantation. The concentrations of DOC and DON in surface soil (0-15 cm) were all significantly higher than in the subsurface (30-60 cm). The aromatic index (AI) was in the order of RF>CP>BF, and as a whole, the highest AI was observed in the surface soil. Higher fluorescence intensity and a short wave absorption peak (320 nm) were observed in C. carlesii plantation, suggesting the surface soil of C. carlesii plantation was rich in decomposed substance content, while the degree of humification was lower. A medium wave absorption peak (380 nm) was observed in human-assisted naturally regenerated C. carlesii forest, indicating the degree of humification was higher which would contribute to the storage of soil fertility. In addition, DOM characte-ristics in 30-60 cm soil solution were almost unaffected by forest regeneration patterns.

Wind-Flow Patterns in the Grand Canyon as Revealed by Doppler Lidar.

NASA Astrophysics Data System (ADS)

Banta, Robert M.; Darby, Lisa S.; Kaufmann, Pirmin; Levinson, David H.; Zhu, Cui-Juan

1999-08-01

Many interesting flow patterns were found in the Grand Canyon by a scanning Doppler lidar deployed to the south rim during the 1990 Wintertime Visibility Study. Three are analyzed in this study: 1) flow reversal in the canyon, where the flow in the canyon was in the opposite direction from the flow above the canyon rim; 2) under strong, gusty flow from the southwest, the flow inside and above the canyon was from a similar direction and coupled; and 3) under light large-scale ambient flow, the lidar found evidence of local, thermally forced up- and down-canyon winds in the bottom of the canyon.On the days with flow reversal in the canyon, the strongest in-canyon flow response was found for days with northwesterly flow and a strong inversion at the canyon rim. The aerosol backscatter profiles were well mixed within the canyon but poorly mixed across the rim because of the inversion. The gusty southwest flow days showed strong evidence of vertical mixing across the rim both in the momentum and in the aerosol backscatter profiles, as one would expect in turbulent flow. The days with light ambient flow showed poor vertical mixing even inside the canyon, where the jet of down-canyon flow in the bottom of the canyon at night was often either cleaner or dirtier than the air in the upper portions of the canyon. In a case study presented, the light ambient flow regime ended with an intrusion of polluted, gusty, southwesterly flow. The polluted, high-backscatter air took several hours to mix into the upper parts of the canyon. An example is also given of high-backscatter air in the upper portions of the canyon being mixed rapidly down into a jet of cleaner air in the bottom of the canyon in just a few minutes.

Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter.

PubMed

Rowe, E C; Tipping, E; Posch, M; Oulehle, F; Cooper, D M; Jones, T G; Burden, A; Hall, J; Evans, C D

2014-01-01

Increases in dissolved organic carbon (DOC) fluxes may relate to changes in sulphur and nitrogen pollution. We integrated existing models of vegetation growth and soil organic matter turnover, acid-base dynamics, and organic matter mobility, to form the 'MADOC' model. After calibrating parameters governing interactions between pH and DOC dissolution using control treatments on two field experiments, MADOC reproduced responses of pH and DOC to additions of acidifying and alkalising solutions. Long-term trends in a range of acid waters were also reproduced. The model suggests that the sustained nature of observed DOC increases can best be explained by a continuously replenishing potentially-dissolved carbon pool, rather than dissolution of a large accumulated store. The simulations informed the development of hypotheses that: DOC increase is related to plant productivity increase as well as to pH change; DOC increases due to nitrogen pollution will become evident, and be sustained, after soil pH has stabilised. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of pH, dissolved organic matter, and salinity on ibuprofen sorption on sediment.

PubMed

Oh, Sanghwa; Shin, Won Sik; Kim, Hong Tae

2016-11-01

Ibuprofen is well known as one of the most frequently detected pharmaceuticals and personal care products (PPCPs) in rivers. However, sorption of ibuprofen onto sediment has not been considered in spite of its high K ow (3.5). In this study, the effects of various environmental conditions such as pH (4, 5.3, and 7), the concentrations of dissolved organic matters (0 to 1.0 mM citrate and urea), salinity (0, 10, 20, and 30 part per thousand), and presence of other PPCP (salicylic acid) on ibuprofen sorption were investigated. Linear model mainly fitted the experimental data for analysis. The distribution coefficient (K d ) in the linear model decreased from 6.76 at pH 4 to near zero at pH 7, indicating that neutral form of ibuprofen at pH below pKa (5.2) was easily sorbed onto the sediment whereas the sorption of anionic form at pH over pKa was not favorable. To investigate the effect of dissolved organic matters (DOMs) on ibuprofen sorption, citrate and urea were used as DOMs. As citrate concentration increased, the K d value decreased but urea did not interrupt the ibuprofen sorption. Citrate has three carboxyl functional groups which can attach easily ibuprofen and hinder its sorption onto sediment. Salinity also affected ibuprofen sorption due to decrease of the solubility of ibuprofen as salinity increased. In competitive sorption experiment, the addition of salicylic acid also led to enhance ibuprofen sorption. Conclusively, ibuprofen can be more easily sorbed onto the acidified sediments of river downstream, especially estuaries or near-shore environment with low DOM concentration.

The Wide Bay Canyon system: A case study of canyon morphology on the east Australian continental margin

NASA Astrophysics Data System (ADS)

Yu, P. W.; Hubble, T.; Airey, D.; Gallagher, S. J.; Clarke, S. L.

2014-12-01

A voyage was conducted aboard the RV Southern Surveyor in early 2013 to investigate the east Australian continental margin. From the continental slope of the Wide Bay region offshore Fraser Island, Queensland, Australia, remote sensing data and sediment samples were collected. Bathymetric data reveals that the continental slope of the region presents a mature canyon system. Eight dredge samples were recovered from the walls of Wide Bay Canyon and the adjacent, relatively intact continental slope along the entire length of the slope, from the start of the shelf break to the toe, in water depths ranging from 1100-2500 m. For these samples, sediment composition, biostratigraphic age, and bulk mineralogy data are reported. These slope-forming sediments are primarily comprised of calcareous sandy-silts. Occasional terrestrial plant fossils and minerals can be found in a mostly marine-fossiliferous composition, suggesting minor but significant riverine and aeolian input. Biostratigraphic dates extracted from the foraminiferal contents of these samples indicate that the intra-canyon and slope material was deposited between Middle Miocene to Pliocene, implying that the incision of this section of the margin and formation of the erosional features took place no earlier than the Pliocene. In conjunction with bathymetric data of the local continental slope, the depositional origins of this section of the east Australian continental margin, and the timing of major morphological events such as slope failure and canyon incision can be interpreted. The Wide Bay Canyon system can serve as a representative case study of local canyon formation, allowing a better understanding of the past or ongoing processes that are shaping the margin and giving way to similar morphologies.

Grand Canyon Humpback Chub Population Improving

USGS Publications Warehouse

Andersen, Matthew E.

2007-01-01

The humpback chub (Gila cypha) is a long-lived, freshwater fish found only in the Colorado River Basin. Physical adaptations-large adult body size, large predorsal hump, and small eyes-appear to have helped humpback chub evolve in the historically turbulent Colorado River. A variety of factors, including habitat alterations and the introduction of nonnative fishes, likely prompted the decline of native Colorado River fishes. Declining numbers propelled the humpback chub onto the Federal list of endangered species in 1967, and the species is today protected under the Endangered Species Act of 1973. Only six populations of humpback chub are currently known to exist, five in the Colorado River Basin above Lees Ferry, Ariz., and one in Grand Canyon, Ariz. The U.S. Geological Survey's Grand Canyon Monitoring and Research Center oversees monitoring and research activities for the Grand Canyon population under the auspices of the Glen Canyon Dam Adaptive Management Program (GCDAMP). Analysis of data collected through 2006 suggests that the number of adult (age 4+ years) humpback chub in Grand Canyon increased to approximately 6,000 fish in 2006, following an approximate 40-50 percent decline between 1989 and 2001. Increasing numbers of adult fish appear to be the result of steadily increasing numbers of juvenile fish reaching adulthood beginning in the mid- to late-1990s and continuing through at least 2002.

Geoelectrical Response of Surfactant Solutions in a Quartzitic Sand Analog Aquifer

EPA Science Inventory

In this project, the resistivity and phase shift of ten surfactant aqueous solutions in a sand matrix were measured using spectral induced polarization (SIP). In addition, specific conductivity, pH, dissolved oxygen, and dielectric constant measurements of the solutions were also...

Effects of pore size and dissolved organic matters on diffusion of arsenate in aqueous solution.

PubMed

Wang, Yulong; Wang, Shaofeng; Wang, Xin; Jia, Yongfeng

2017-02-01

Presented here is the influence of membrane pore size and dissolved organic matters on the diffusion coefficient (D) of aqueous arsenate, investigated by the diffusion cell method for the first time. The pH-dependent diffusion coefficient of arsenate was determined and compared with values from previous studies; the coefficient was found to decrease with increasing pH, showing the validity of our novel diffusion cell method. The D value increased dramatically as a function of membrane pore size at small pore sizes, and then increased slowly at pore sizes larger than 2.0μm. Using the ExpAssoc model, the maximum D value was determined to be 11.2565×10 -6 cm 2 /sec. The presence of dissolved organic matters led to a dramatic increase of the D of arsenate, which could be attributed to electrostatic effects and ionic effects of salts. These results improve the understanding of the diffusion behavior of arsenate, especially the important role of various environmental parameters in the study and prediction of the migration of arsenate in aquatic water systems. Copyright © 2016. Published by Elsevier B.V.

Effects of canyon geometry on the distribution of traffic-related air pollution in a large urban area: Implications of a multi-canyon air pollution dispersion model

NASA Astrophysics Data System (ADS)

Fu, Xiangwen; Liu, Junfeng; Ban-Weiss, George A.; Zhang, Jiachen; Huang, Xin; Ouyang, Bin; Popoola, Olalekan; Tao, Shu

2017-09-01

Street canyons are ubiquitous in urban areas. Traffic-related air pollutants in street canyons can adversely affect human health. In this study, an urban-scale traffic pollution dispersion model is developed considering street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. In the model, vehicle exhausts generated from traffic flows first disperse inside street canyons along the micro-scale wind field generated by computational fluid dynamics (CFD) model. Then, pollutants leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NOx and CO from traffic emissions were studied over the center of Beijing. We found that an increase in building height leads to heavier pollution inside canyons and lower pollution outside canyons at pedestrian level, resulting in higher domain-averaged concentrations over the area. In addition, canyons with highly even or highly uneven building heights on each side of the street tend to lower the urban-scale air pollution concentrations at pedestrian level. Further, increasing street widths tends to lead to lower pollutant concentrations by reducing emissions and enhancing ventilation simultaneously. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry while considering traffic demand as well as local weather patterns may significantly reduce inhalation of unhealthy air by urban residents.

Characteristics of flow and reactive pollutant dispersion in urban street canyons

NASA Astrophysics Data System (ADS)

Park, Soo-Jin; Kim, Jae-Jin; Kim, Minjoong J.; Park, Rokjin J.; Cheong, Hyeong-Bin

2015-05-01

In this study, the effects of aspect ratio defined as the ratio of building height to street width on the dispersion of reactive pollutants in street canyons were investigated using a coupled CFD-chemistry model. Flow characteristics for different aspect ratios were analyzed first. For each aspect ratio, six emission scenarios with different VOC-NOX ratios were considered. One vortex was generated when the aspect ratio was less than 1.6 (shallow street canyon). When the aspect ratio was greater than 1.6 (deep street canyon), two vortices were formed in the street canyons. Comparing to previous studies on two-dimensional street canyons, the vortex center is slanted toward the upwind building and reverse and downward flows are dominant in street canyons. Near the street bottom, there is a marked difference in flow pattern between in shallow and deep street canyons. Near the street bottom, reverse and downward flows are dominant in shallow street canyon and flow convergence exists near the center of the deep street canyons, which induces a large difference in the NOX and O3 dispersion patterns in the street canyons. NOX concentrations are high near the street bottom and decreases with height. The O3 concentrations are low at high NO concentrations near the street bottom because of NO titration. At a low VOC-NOX ratio, the NO concentrations are sufficiently high to destroy large amount of O3 by titration, resulting in an O3 concentration in the street canyon much lower than the background concentration. At high VOC-NOX ratios, a small amount of O3 is destroyed by NO titration in the lower layer of the street canyons. However, in the upper layer, O3 is formed through the photolysis of NO2 by VOC degradation reactions. As the aspect ratio increases, NOX (O3) concentrations averaged over the street canyons decrease (increase) in the shallow street canyons. This is because outward flow becomes strong and NOX flux toward the outsides of the street canyons increases

7. DARK CANYON SIPHON Photographic copy of construction drawing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. DARK CANYON SIPHON - Photographic copy of construction drawing c1907 (from Record Group 115, Box 17, Denver Branch of the National Archives, Denver) DARK CANYON SIPHON PLAN, ELEVATION, AND SECTIONS - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

Iron traps terrestrially derived dissolved organic matter at redox interfaces

PubMed Central

Riedel, Thomas; Zak, Dominik; Biester, Harald; Dittmar, Thorsten

2013-01-01

Reactive iron and organic carbon are intimately associated in soils and sediments. However, to date, the organic compounds involved are uncharacterized on the molecular level. At redox interfaces in peatlands, where the biogeochemical cycles of iron and dissolved organic matter (DOM) are coupled, this issue can readily be studied. We found that precipitation of iron hydroxides at the oxic surface layer of two rewetted fens removed a large fraction of DOM via coagulation. On aeration of anoxic fen pore waters, >90% of dissolved iron and 27 ± 7% (mean ± SD) of dissolved organic carbon were rapidly (within 24 h) removed. Using ultra-high-resolution MS, we show that vascular plant-derived aromatic and pyrogenic compounds were preferentially retained, whereas the majority of carboxyl-rich aliphatic acids remained in solution. We propose that redox interfaces, which are ubiquitous in marine and terrestrial settings, are selective yet intermediate barriers that limit the flux of land-derived DOM to oceanic waters. PMID:23733946

CESIUM RECOVERY FROM AQUEOUS SOLUTIONS

DOEpatents

Schneider, R.A.

1961-06-20

Cesium may be precipitated from an aqueous solution whose acidity ranges between a pH of 1.5 and a molarity of 5 on cobaltous, zinc, cadmium, nickel, or ferrous cobalticyanide. This precipitation brings about a separation from most fission products. Ruthenium which coprecipitates to a great degree can be removed by dissolving in sulfuric acid and boiling the solution in the presence of periodic acid for volatilization; other coprecipitated fission products can then be precipitated from the sulfuric acid solution with a ferric hydroxide carrier.

RECOVERY OF URANIUM AND THORIUM FROM AQUEOUS SOLUTIONS

DOEpatents

Calkins, G.D.

1958-06-10

>A process is described for the recovery of uranium and thorium from monazite sand, which is frequently processed by treating it with a hot sodium hydroxide solution whereby a precipitate forms consisting mainly of oxides or hydroxides of the rare earths, thorium and uranium. The precipitate is dissolved in mineral acid, and the acid solution is then neutralized to a pH value of between 5.2 and 6.2 whereby both the uranium and thorium precipitate as the hydroxides, while substantially all the rare earth metal values present remain in the solution. The uranium and thoriunn can then be separated by dissolving the precipitate in a solution containing a mixture of alkali carbonate and alkali bicarbonate: and contacting the carbonate solution with a strong-base anion exchange resin whereby the uranium values are adsorbed on the resin while the thorium remains in solution.

ANALYTICAL METHOD FOR THE ABSORPTIOMETRIC DETERMINATION OF BORON IN AMMONIA SOLUTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1962-01-01

ABS>A weighed sample is evaporated to dryness with caustic soda solution on a water bath. The residue is dissolved by addlng a solution of curcumin in acetic acid. After adding a mixture of H/sub 2/SO/sub 4/ and acetic acid, the solution is allowed to stand at room temperature for 15 minutes. The solution is then diluted to 100 ml with ethanol, and a portion is filtered and measured absorptiometrically on the residue as the curcumin complex. (P.C.H.)

Inhibitory Effect of Dissolved Silica on the H2O2 Decomposition by Iron(III) and Manganese(IV) Oxides: Implications for H2O2-based In Situ Chemical Oxidation

PubMed Central

Pham, Anh Le-Tuan; Doyle, Fiona M.; Sedlak, David L.

2011-01-01

The decomposition of H2O2 on iron minerals can generate •OH, a strong oxidant that can transform a wide range of contaminants. This reaction is critical to In Situ Chemical Oxidation (ISCO) processes used for soil and groundwater remediation, as well as advanced oxidation processes employed in waste treatment systems. The presence of dissolved silica at concentrations comparable to those encountered in natural waters decreases the reactivity of iron minerals toward H2O2, because silica adsorbs onto the surface of iron minerals and alters catalytic sites. At circumneutral pH values, goethite, amorphous iron oxide, hematite, iron-coated sand and montmorillonite that were pre-equilibrated with 0.05 – 1.5 mM SiO2 were significantly less reactive toward H2O2 decomposition than their original counterparts, with the H2O2 loss rates inversely proportional to the SiO2 concentration. In the goethite/H2O2 system, the overall •OH yield, defined as the percentage of decomposed H2O2 producing •OH, was almost halved in the presence of 1.5 mM SiO2. Dissolved SiO2 also slows the H2O2 decomposition on manganese(IV) oxide. The presence of dissolved SiO2 results in greater persistence of H2O2 in groundwater, lower H2O2 utilization efficiency and should be considered in the design of H2O2-based treatment systems. PMID:22129132

5. DARK CANYON SIPHON Photographic copy of historic photo, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. DARK CANYON SIPHON - Photographic copy of historic photo, November 11, 1906 (original print located at the Carlsbad Irrigation District offices, Carlsbad, New Mexico) photographer unknown 'LOWER END OF DARK CANYON SIPHON CONSTRUCTION' - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

V OLATILEC ALC: a silicate melt-H 2O-CO 2 solution model written in Visual Basic for excel

NASA Astrophysics Data System (ADS)

Newman, Sally; Lowenstern, Jacob B.

2002-06-01

We present solution models for the rhyolite-H 2O-CO 2 and basalt-H 2O-CO 2 systems at magmatic temperatures and pressures below ˜5000 bar. The models are coded as macros written in Visual Basic for Applications, for use within Microsoft ® Excel (Office'98 and 2000). The series of macros, entitled V OLATILEC ALC, can calculate the following: (1) Saturation pressures for silicate melt of known dissolved H 2O and CO 2 concentrations and the corresponding equilibrium vapor composition; (2) open- and closed-system degassing paths (melt and vapor composition) for depressurizing rhyolitic and basaltic melts; (3) isobaric solubility curves for rhyolitic and basaltic melts; (4) isoplethic solubility curves (constant vapor composition) for rhyolitic and basaltic melts; (5) polybaric solubility curves for the two end members and (6) end member fugacities of H 2O and CO 2 vapors at magmatic temperatures. The basalt-H 2O-CO 2 macros in V OLATILEC ALC are capable of calculating melt-vapor solubility over a range of silicate-melt compositions by using the relationships provided by Dixon (American Mineralogist 82 (1997) 368). The output agrees well with the published solution models and experimental data for silicate melt-vapor systems for pressures below 5000 bar.

A Novel Bat-Shaped Dicyanomethylene-4H-pyran-Functionalized Naphthalimide for Highly Efficient Solution-Processed Multilevel Memory Devices.

PubMed

Zhang, Qi-Jian; Miao, Shi-Feng; Li, Hua; He, Jing-Hui; Li, Na-Jun; Xu, Qing-Feng; Chen, Dong-Yun; Lu, Jian-Mei

2017-06-19

Small-molecule-based multilevel memory devices have attracted increasing attention because of their advantages, such as super-high storage density, fast reading speed, light weight, low energy consumption, and shock resistance. However, the fabrication of small-molecule-based devices always requires expensive vacuum-deposition techniques or high temperatures for spin-coating. Herein, through rational tailoring of a previous molecule, DPCNCANA (4,4'-(6,6'-bis(2-octyl-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)-9H,9'H-[3,3'-bicarbazole]-9,9'-diyl)dibenzonitrile), a novel bat-shaped A-D-A-type (A-D-A=acceptor-donor-acceptor) symmetric framework has been successfully synthesized and can be dissolved in common solvents at room temperature. Additionally, it has a low-energy bandgap and dense intramolecular stacking in the film state. The solution-processed memory devices exhibited high-performance nonvolatile multilevel data-storage properties with low switching threshold voltages of about -1.3 and -2.7 V, which is beneficial for low power consumption. Our result should prompt the study of highly efficient solution-processed multilevel memory devices in the field of organic electronics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toxicity of dissolved and precipitated aluminium to marine diatoms.

PubMed

Gillmore, Megan L; Golding, Lisa A; Angel, Brad M; Adams, Merrin S; Jolley, Dianne F

2016-05-01

Localised aluminium contamination can lead to high concentrations in coastal waters, which have the potential for adverse effects on aquatic organisms. This research investigated the toxicity of 72-h exposures of aluminium to three marine diatoms (Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus and Phaeodactylum tricornutum) by measuring population growth rate inhibition and cell membrane damage (SYTOX Green) as endpoints. Toxicity was correlated to the time-averaged concentrations of different aluminium size-fractions, operationally defined as <0.025μm filtered, <0.45μm filtered (dissolved) and unfiltered (total) present in solution over the 72-h bioassay. The chronic population growth rate inhibition after aluminium exposure varied between diatom species. C. closterium was the most sensitive species (10% inhibition of growth rate (72-h IC10) of 80 (55-100)μg Al/L (95% confidence limits)) while M. polymorphus (540 (460-600)μg Al/L) and P. tricornutum (2100 (2000-2200)μg Al/L) were less sensitive (based on measured total aluminium). Dissolved aluminium was the primary contributor to toxicity in C. closterium, while a combination of dissolved and precipitated aluminium forms contributed to toxicity in M. polymorphus. In contrast, aluminium toxicity to the most tolerant diatom P. tricornutum was due predominantly to precipitated aluminium. Preliminary investigations revealed the sensitivity of C. closterium and M. polymorphus to aluminium was influenced by initial cell density with aluminium toxicity significantly (p<0.05) increasing with initial cell density from 10(3) to 10(5)cells/mL. No effects on plasma membrane permeability were observed for any of the three diatoms suggesting that mechanisms of aluminium toxicity to diatoms do not involve compromising the plasma membrane. These results indicate that marine diatoms have a broad range in sensitivity to aluminium with toxic mechanisms related to both dissolved and precipitated

Bottom-trawling along submarine canyons impacts deep sedimentary regimes

PubMed Central

Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

2017-01-01

Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons’ morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20th century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities. PMID:28233856

Bottom-trawling along submarine canyons impacts deep sedimentary regimes

NASA Astrophysics Data System (ADS)

Paradis, Sarah; Puig, Pere; Masqué, Pere; Juan-Díaz, Xènia; Martín, Jacobo; Palanques, Albert

2017-02-01

Many studies highlight that fish trawling activities cause seafloor erosion, but the assessment of the remobilization of surface sediments and its relocation is still not well documented. These impacts were examined along the flanks and axes of three headless submarine canyons incised on the Barcelona continental margin, where trawling fleets have been operating for decades. Trawled grounds along canyon flanks presented eroded and highly reworked surface sediments resulting from the passage of heavy trawling gear. Sedimentation rates on the upper canyon axes tripled and quadrupled its natural (i.e. pre-industrialization) values after a substantial increase in total horsepower of the operating trawling fleets between 1960 s and 1970 s. These impacts affected the upper canyon reaches next to fishing grounds, where sediment resuspended by trawling can be transported towards the canyon axes. This study highlights that bottom trawling has the capacity to alter natural sedimentary environments by promoting sediment-starved canyon flanks, and by enhancing sedimentation rates along the contiguous axes, independently of canyons’ morphology. Considering the global mechanisation and offshore expansion of bottom trawling fisheries since the mid-20th century, these sedimentary alterations may occur in many trawled canyons worldwide, with further ecological impacts on the trophic status of these non-resilient benthic communities.

Active geologic processes in Barrow Canyon, northeast Chukchi Sea

USGS Publications Warehouse

Eittreim, S.; Grantz, A.; Greenberg, J.

1982-01-01

Circulation patterns on the shelf and at the shelf break appear to dominate the Barrow Canyon system. The canyon's shelf portion underlies and is maintained by the Alaska Coastal Current (A.C.C.), which flows northeastward along the coast toward the northeast corner of the broad Chukchi Sea. Offshelf and onshelf advective processes are indicated by oceanographic measurements of other workers. These advective processes may play an important role in the production of bedforms that are found near the canyon head as well as in processes of erosion or non-deposition in the deeper canyon itself. Coarse sediments recovered from the canyon axis at 400 to 570 m indicate that there is presently significant flow along the canyon. The canyon hooks left at a point north of Point Barrow where the A.C.C. loses its coastal constriction. The left hook, as well as preferential west-wall erosion, continues down to the abyssal plain of the Canada Basin at 3800 m. A possible explanation for the preferential west-wall erosion along the canyon, at least for the upper few hundred meters, is that the occasional upwelling events, which cause nutrient-rich water to flow along the west wall would in turn cause larger populations of burrowing organisms to live there than on the east wall, and that these organisms cause high rates of bioerosion. This hypothesis assumes that the dominant factor in the canyon's erosion is biological activity, not current velocity. Sedimentary bedforms consisting of waves and furrows are formed in soft mud in a region on the shelf west of the canyon head; their presence there perhaps reflects: (a) the supply of fine suspended sediments delivered by the A.C.C. from sources to the south, probably the Yukon and other rivers draining northwestern Alaska; and (b) the westward transport of these suspended sediments by the prevailing Beaufort Gyre which flows along the outer shelf. ?? 1982.

Benthic prokaryotic community dynamics along the Ardencaple Canyon, Western Greenland Sea

NASA Astrophysics Data System (ADS)

Quéric, Nadia-Valérie; Soltwedel, Thomas

2012-07-01

The Ardencaple Canyon, emanating from the Eastern Greenland continental rise over a distance of about 200 km towards the Greenland Basin, was investigated to determine the effect of enhanced down-slope transport mechanisms on deep-sea benthic prokaryotic communities. The concentration of viable bacterial cells (Live/Dead®BacLight) and prokaryotic incorporation rates (3H-thymidine, 14C-leucine) increased with increasing distance from the continental shelf. Multidimensional scaling (MDS) results from terminal restriction fragment length polymorphism (T-RFLP) analysis indicated a spatial coherence between the benthic bacterial community structure, prokaryotic incorporation rates, water content, protein concentration and the total organic matter in the sediments. The community complexity in sediments at 4-5 cm depth was lower in the central parts of the channel compared with the northern and the southern levees, while richness in surface sediments of all stations was similar. Lacking any clear indications for a recent mass sediment transport or funneled shelf drainage flows, high similarities between bacterial assemblages in sediments along the canyon course may thus be governed by a combination of an ice-edge induced particle flux, episodic down-slope and canyon-guided transport mechanisms.

Room-temperature NaI/H2O compression icing: solute-solute interactions.

PubMed

Zeng, Qingxin; Yao, Chuang; Wang, Kai; Sun, Chang Q; Zou, Bo

2017-10-11

In situ Raman spectroscopy revealed that transiting the concentrated NaI/H 2 O solutions to an ice VI phase and then into an ice VII phase at 298 K proceeds in a way different from that activated by the solute type. Unlike the solute type that raises both the critical pressures P C1 and P C2 , for the liquid-VI, the VI-VII transition simultaneously occurs in the Hofmeister series order: I > Br > Cl > F ∼ 0; concentration increase raises the P C1 faster than the P C2 that remains almost constant at higher NaI/H 2 O molecular number ratios. Concentration increase moves the P C1 along the liquid-VI phase boundary and it finally merges with P C2 at the triple-phase junction featured at 350 K and 3.05 GPa. The highly-deformed H-O bond is less sensitive to the concentration because of the involvement of anion-anion repulsion that weakens the electric field in the hydration shells. Observations confirm that the salt solvation lengthens the O:H nonbond and softens its phonon but relaxes the H-O bond contrastingly. Compression, however, has the opposite effect from that of salt solvation. Therefore, compression recovers the polarization-deformed O:H-O bond first and then proceeds to the phase transitions. The anion-anion interaction discriminates the effect of NaI/H 2 O concentration from that of the solute type at an identical concentration on the phase transitions.

Perspective view over the Grand Canyon, Arizona

NASA Image and Video Library

2001-10-22

This simulated true color perspective view over the Grand Canyon was created from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data acquired on May 12, 2000. The Grand Canyon Village is in the lower foreground; the Bright Angel Trail crosses the Tonto Platform, before dropping down to the Colorado Village and then to the Phantom Ranch (green area across the river). Bright Angel Canyon and the North Rim dominate the view. At the top center of the image the dark blue area with light blue haze is an active forest fire. http://photojournal.jpl.nasa.gov/catalog/PIA01908

The San Juan Canyon, southeastern Utah: A geographic and hydrographic reconnaissance

USGS Publications Warehouse

Miser, Hugh D.

1924-01-01

This report, which describes the San Juan Canyon, San Juan River and the tributary streams and the geography and to some extent the geology of the region, presents information obtained by me during the descent of the river with the Trimble party in 1921. The exploration of the canyon, which was financed jointly by the United States Geological Survey and the Southern California Edison Co., had as its primary object the mapping and study of the San Juan in connection with proposed power and storage projects along this and Colorado rivers.1 The exploration party was headed by K. W. Thimble, topographic engineer of the United States Geological Survey. Other members of the party were Robert N. Allen, Los Angeles, Calif., recorder; H. E. Blake, jr., Monticello, Utah, and Hugh Hyde, Salt Lake City, Utah, rodmen; Bert Loper, Green River, Utah, boatman; Heber Christensen, Moab, Utah, cook; and H. D. Miser, geologist. Wesley Oliver, of Mexican Hat, Utah, served as packer for the party and brought mail and provisions by pack train twice a month to specified accessible places west of Goodridge.

6. DARK CANYON SIPHON Photographic copy of historic photo, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. DARK CANYON SIPHON - Photographic copy of historic photo, January 29, 1907 (original print filed in Record Group 115, National Archives, Washington, D.C.) W.J.Lubken, photographer 'RIPRAP AT THE ENTRANCE END OF DARK CANYON PRESSURE PIPE' - Carlsbad Irrigation District, Dark Canyon Siphon, On Main Canal, 1 mile South of Carlsbad, Carlsbad, Eddy County, NM

Use of Composite Fingerprinting Technique to Determine Contribution of Paria River Sediments to Dam-Release Flood Deposits in Marble Canyon, Grand Canyon, Az

NASA Astrophysics Data System (ADS)

Chapman, K.; Parnell, R. A.; Smith, M. E.; Grams, P. E.; Mueller, E. R.

2015-12-01

The 1963 closure of Glen Canyon Dam drastically reduced the downstream sediment supply and altered daily flow regimes of the Colorado River through Grand Canyon, resulting in significant sandbar erosion downstream of the dam. Dam-release floods, known as High Flow Experiments (HFEs), have occurred six times since 1996 and are intended to rebuild Grand Canyon sandbars using tributary-supplied sediment. In Marble Canyon (first 100 km of Grand Canyon) the targeted tributary is the Paria River which supplies approximately 90% of the annual suspended sediment flux through Marble Canyon; the same input contributed less than 6% prior to the dam. Annual topographic surveys have established that HFEs are effective at rebuilding sandbars. However, the long-term viability of using HFEs for sandbar maintenance is dependent on a sustainable source of sediments comprising HFE deposits. Significant use of non-tributary, main-stem sediments (i.e. pre-dam sand stored in eddies or the channel bed) in HFE deposits would indicate reliance on a limited resource, and diminishing returns in the ability of HFEs to rebuild sandbars. In this study, we sampled vertically throughout 12 bars in Marble Canyon to document temporal and downstream changes in the proportion of sediment sourced from the Paria River during the 2013 and 2014 HFEs. Preliminary data suggest that heavy mineral compositions and concentrations of Ti, S, Cr and Rb, all of which are influenced by grainsize, could be sufficiently capable of differentiating Paria-derived and main-stem sediments when combined into a composite fingerprint (CF). A multivariate mixing model using these CFs quantitatively determines the contribution of Paria-derived sediment in each HFE deposit sample. Mixing model endmembers for non-Paria sand include pre-dam flood deposits in Glen and Marble Canyons, and Marble Canyon dredge samples. These results elucidate the role of contemporary versus legacy sediment in long-term sandbar maintenance.

Thermal comfort in an east-west oriented street canyon in Freiburg (Germany) under hot summer conditions

NASA Astrophysics Data System (ADS)

Ali-Toudert, F.; Mayer, H.

2007-01-01

Field-measurements were conducted in an urban street canyon with an east-west orientation, and a height-to-width ratio H/W = 1 during cloudless summer weather in 2003 in Freiburg, Germany. This experimental work adds to the knowledge available on the microclimate of an urban canyon and its impact on human comfort. Air temperature T a , air humidity VP, wind speed v and direction dd were measured continuously. All short-wave and long-wave radiation fluxes from the 3D surroundings were also measured. The degree of comfort was defined in terms of physiologically equivalent temperature (PET). Furthermore, the data gathered within the canyon were compared to data collected by a permanent urban climate station with the aim of furthering the understanding of microclimatic changes due to street geometry. Changes in the meteorological variables T a , v and dd in the canyon in comparison to an unobstructed roof level location were found to be in good agreement with previous studies, i.e., a small increase of T a in the canyon adjacent to irradiated surfaces, and a good correlation of v and dd between canyon and roof levels. The daily dynamics of canyon facet irradiances and their impacts on the heat gained by a pedestrian were strongly dependent on street geometry and orientation. Thermal stress was mostly attributable to solar exposure. Under cloudless summer weather, a standing body was found to absorb, on average, 74% of heat in the form of long-wave irradiance and 26% as short-wave irradiance. Shading the pedestrian as well as the surrounding surfaces is, hence, the first strategy in mitigating heat stress in summer under hot conditions.

Observations of environmental change in Grand Canyon, Arizona

USGS Publications Warehouse

Webb, Robert H.; Melis, Theodore S.; Valdez, Richard A.

2002-01-01

Few scientific data have been collected on pre-dam conditions of the Colorado River corridor through Grand Canyon National Park. Using historical diaries, interviews with pre-dam river runners (referred to as the ?Old Timers?), and historical scientific data and observations, we compiled anecdotal information on environmental change in Grand Canyon. The most significant changes are the: lowering of water temperature in the river, near-elimination of heavily sediment-laden flows, erosion of sand bars, invasion of non-native tamarisk trees, reduction in driftwood, development of marshes, increase in non-native fish at the expense of native fishes, and increase in water bird populations. In addition, few debris flows were observed before closure of Glen Canyon Dam, which might suggests that the frequency of debris flows in Grand Canyon has increased. Other possible changes include decreases in bat populations and increases in swallow and bighorn sheep populations, although the evidence is anecdotal and inconclusive. These results provide a perspective on managing the Colorado River that may allow differentiation of the effects of Glen Canyon Dam from other processes of change.

DISSOLVED ORGANIC MATTER AND METALS: EFFECTS OF PH ON PARTITIONING NATURAL ORGANIC MATTER IN SOILS AND WATER

EPA Science Inventory

Eighteen Dutch soils were extracted in aqueous solutions at varying pH. Extracts were analyzed for Cd, Cu, Ni, Pb, and Zn by ICP-AES. Extract dissolved organic carbon (DOC) was fractionated into three operationally defined fractions: hydrophilic acids (Hyd), fulvic acids (FA), an...

Grand Canyon, Lake Powell, and Lake Mead

NASA Technical Reports Server (NTRS)

2002-01-01

A snowfall in the American West provides contrast to the landscape's muted earth tones and indicates changes in topography and elevation across (clockwise from top left) Nevada, Utah, Colorado, New Mexico, Arizona, and California. In Utah, the southern ranges of the Wasatch Mountains are covered in snow, and the Colorado River etches a dark ribbon across the red rock of the Colorado Plateau. In the center of the image is the reservoir created by the Glen Canyon Dam. To the east are the gray-colored slopes of Navaho Mountain, and to the southeast, dusted with snow is the region called Black Mesa. Southwest of Glen Canyon, the Colorado enters the Grand Canyon, which cuts westward through Arizona. At a deep bend in the river, the higher elevations of the Keibab Plateau have held onto snow. At the end of the Grand Canyon lies another large reservoir, Lake Mead, which is formed by the Hoover Dam. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

Turbidity, light, temperature, and hydropeaking control primary productivity in the Colorado River, Grand Canyon

USGS Publications Warehouse

Hall, Robert O.; Yackulic, Charles B.; Kennedy, Theodore A.; Yard, Michael D.; Rosi-Marshall, Emma J.; Voichick, Nicholas; Behn, Kathrine E.

2015-01-01

Dams and river regulation greatly alter the downstream environment for gross primary production (GPP) because of changes in water clarity, flow, and temperature regimes. We estimated reach-scale GPP in five locations of the regulated Colorado River in Grand Canyon using an open channel model of dissolved oxygen. Benthic GPP dominates in Grand Canyon due to fast transport times and low pelagic algal biomass. In one location, we used a 738 days time series of GPP to identify the relative contribution of different physical controls of GPP. We developed both linear and semimechanistic time series models that account for unmeasured temporal covariance due to factors such as algal biomass dynamics. GPP varied from 0 g O2 m−2 d−1 to 3.0 g O2 m−2 d−1 with a relatively low annual average of 0.8 g O2 m−2d−1. Semimechanistic models fit the data better than linear models and demonstrated that variation in turbidity primarily controlled GPP. Lower solar insolation during winter and from cloud cover lowered GPP much further. Hydropeaking lowered GPP but only during turbid conditions. Using the best model and parameter values, the model accurately predicted seasonal estimates of GPP at 3 of 4 upriver sites and outperformed the linear model at all sites; discrepancies were likely from higher algal biomass at upstream sites. This modeling approach can predict how changes in physical controls will affect relative rates of GPP throughout the 385 km segment of the Colorado River in Grand Canyon and can be easily applied to other streams and rivers.

The dissolution of quartz in dilute aqueous solutions of organic acids at 25°C

USGS Publications Warehouse

Bennett, P.C.; Melcer, M.E.; Siegel, D.I.; Hassett, J.P.

1988-01-01

The dissolution of quartz in dilute aqueous solutions of organic acids at 25° and standard pressure was investigated by the batch dissolution method. The bulk dissolution rate of quartz in 20 mmole/Kg citrate solutions at pH 7 was 8 to 10 times faster than that in pure water. After 1750 hours the concentration of dissolved silica in the citrate solution was 167 μmole/Kg compared to 50 μmole/Kg in water and a 20 mmole/Kg solution of acetate at pH 7. Solutions of salicylic, oxalic, and humic acids also accelerated the dissolution of quartz in aqueous solution at pH 7. The rate of dissolution in organic acids decreased sharply with decreasing pH.The possibility of a silica-organic acid complex was investigated using UV-difference spectroscopy. Results suggest that dissolved silica is complexed by citrate, oxalate and pyruvate at pH 7 by an electron-donor acceptor complex, whereas no complexation occurs between silica and acetate, lactate, malonate, or succinate. Three models are proposed for the solution and surface complexation of silica by organic acid anions which result in the accelerated dissolution and increased solubility of quartz in organic rich water.

Amphitheater-headed canyons formed by megaflooding at Malad Gorge, Idaho

PubMed Central

Lamb, Michael P.; Mackey, Benjamin H.; Farley, Kenneth A.

2014-01-01

Many bedrock canyons on Earth and Mars were eroded by upstream propagating headwalls, and a prominent goal in geomorphology and planetary science is to determine formation processes from canyon morphology. A diagnostic link between process and form remains highly controversial, however, and field investigations that isolate controls on canyon morphology are needed. Here we investigate the origin of Malad Gorge, Idaho, a canyon system cut into basalt with three remarkably distinct heads: two with amphitheater headwalls and the third housing the active Wood River and ending in a 7% grade knickzone. Scoured rims of the headwalls, relict plunge pools, sediment-transport constraints, and cosmogenic (3He) exposure ages indicate formation of the amphitheater-headed canyons by large-scale flooding ∼46 ka, coeval with formation of Box Canyon 18 km to the south as well as the eruption of McKinney Butte Basalt, suggesting widespread canyon formation following lava-flow diversion of the paleo-Wood River. Exposure ages within the knickzone-headed canyon indicate progressive upstream younging of strath terraces and a knickzone propagation rate of 2.5 cm/y over at least the past 33 ka. Results point to a potential diagnostic link between vertical amphitheater headwalls in basalt and rapid erosion during megaflooding due to the onset of block toppling, rather than previous interpretations of seepage erosion, with implications for quantifying the early hydrosphere of Mars. PMID:24344293

Method for dissolving plutonium oxide with HI and separating plutonium

DOEpatents

Vondra, Benedict L.; Tallent, Othar K.; Mailen, James C.

1979-01-01

PuO.sub.2 -containing solids, particularly residues from incomplete HNO.sub.3 dissolution of irradiated nuclear fuels, are dissolved in aqueous HI. The resulting solution is evaporated to dryness and the solids are dissolved in HNO.sub.3 for further chemical reprocessing. Alternatively, the HI solution containing dissolved Pu values, can be contacted with a cation exchange resin causing the Pu values to load the resin. The Pu values are selectively eluted from the resin with more concentrated HI.

Enhanced Indirect Photochemical Transformation of Histidine and Histamine through Association with Chromophoric Dissolved Organic Matter.

PubMed

Chu, Chiheng; Lundeen, Rachel A; Remucal, Christina K; Sander, Michael; McNeill, Kristopher

2015-05-05

Photochemical transformations greatly affect the stability and fate of amino acids (AAs) in sunlit aquatic ecosystems. Whereas the direct phototransformation of dissolved AAs is well investigated, their indirect photolysis in the presence of chromophoric dissolved organic matter (CDOM) is poorly understood. In aquatic systems, CDOM may act both as sorbent for AAs and as photosensitizer, creating microenvironments with high concentrations of photochemically produced reactive intermediates, such as singlet oxygen (1O2). This study provides a systematic investigation of the indirect photochemical transformation of histidine (His) and histamine by 1O2 in solutions containing CDOM as a function of solution pH. Both His and histamine showed pH-dependent enhanced phototransformation in the CDOM systems as compared to systems in which model, low-molecular-weight 1O2 sensitizers were used. Enhanced reactivity resulted from sorption of His and histamine to CDOM and thus exposure to elevated 1O2 concentrations in the CDOM microenvironment. The extent of reactivity enhancement depended on solution pH via its effects on the protonation state of His, histamine, and CDOM. Sorption-enhanced reactivity was independently supported by depressed rate enhancements in the presence of a cosorbate that competitively displaced His and histamine from CDOM. Incorporating sorption and photochemical transformation processes into a reaction rate prediction model improved the description of the abiotic photochemical transformation rates of His in the presence of CDOM.

Crossing fitness canyons by a finite population

NASA Astrophysics Data System (ADS)

Saakian, David B.; Bratus, Alexander S.; Hu, Chin-Kun

2017-06-01

We consider the Wright-Fisher model of the finite population evolution on a fitness landscape defined in the sequence space by a path of nearly neutral mutations. We study a specific structure of the fitness landscape: One of the intermediate mutations on the mutation path results in either a large fitness value (climbing up a fitness hill) or a low fitness value (crossing a fitness canyon), the rest of the mutations besides the last one are neutral, and the last sequence has much higher fitness than any intermediate sequence. We derive analytical formulas for the first arrival time of the mutant with two point mutations. For the first arrival problem for the further mutants in the case of canyon crossing, we analytically deduce how the mean first arrival time scales with the population size and fitness difference. The location of the canyon on the path of sequences has a crucial role. If the canyon is at the beginning of the path, then it significantly prolongs the first arrival time; otherwise it just slightly changes it. Furthermore, the fitness hill at the beginning of the path strongly prolongs the arrival time period; however, the hill located near the end of the path shortens it. We optimize the first arrival time by applying a nonzero selection to the intermediate sequences. We extend our results and provide a scaling for the valley crossing time via the depth of the canyon and population size in the case of a fitness canyon at the first position. Our approach is useful for understanding some complex evolution systems, e.g., the evolution of cancer.

Photocatalytic degradation of H2S aqueous media using sulfide nanostructured solid-solution solar-energy-materials to produce hydrogen fuel.

PubMed

Lashgari, Mohsen; Ghanimati, Majid

2018-03-05

H 2 S is a corrosive, flammable and noxious gas, which can be neutralized by dissolving in alkaline media and employed as H 2 -source by utilizing inside semiconductor-assisted/photochemical reactors. Herein, through a facile hydrothermal route, a ternary nanostructured solid-solution of iron, zinc and sulfur was synthesized in the absence and presence of Ag-dopant, and applied as efficient photocatalyst of hydrogen fuel production from H 2 S media. The effect of pH on the photocatalyst performance was scrutinized and the maximum activity was attained at pH=11, where HS - concentration is high. BET, diffuse reflectance and photoluminescence studies indicated that the ternary solid-solution photocatalyst, in comparison to its solid-solvent (ZnS), has a greater surface area, stronger photon absorption and less charge recombination, which justify its superiority. Moreover, the effect of silver-dopant on the photocatalyst performance was examined. The investigations revealed that although silver could boost the absorption of photons and increase the surface area, it could not appreciably enhance the photocatalyst performance due to its weak influence on retarding the charge-recombination process. Finally, the phenomenon was discussed in detail from mechanistic viewpoint. Copyright © 2017 Elsevier B.V. All rights reserved.

Formation of Hg(II) tetrathiolate complexes with cysteine at neutral pH

DOE PAGES

Warner, Thomas; Jalilehvand, Farideh

2016-01-04

Mercury(II) ions precipitate from aqueous cysteine (H 2Cys) solutions containing H 2Cys/Hg(II) mole ratio ≥ 2.0 as Hg( S-HCys) 2. In absence of additional cysteine, the precipitate dissolves at pH ~12 with the [Hg( S, N-Cys) 2] 2- complex dominating. With excess cysteine (H 2Cys/Hg(II) mole ratio ≥ 4.0), higher complexes form and the precipitate dissolves at lower pH values. Previously, we found that tetrathiolate [Hg( S-Cys) 4] 6- complexes form at pH = 11.0; in this work we extend the investigation to pH values of physiological interest. We examined two series of Hg(II)-cysteine solutions in which C Hg(II) variedmore » between 8 – 9 mM and 80 – 100 mM, respectively, with H 2Cys/Hg(II) mole ratios from 4 to ~20. The solutions were prepared in the pH range 7.1 – 8.8, at the pH at which the initial Hg( S-HCys) 2 precipitate dissolved. The variations in the Hg(II) speciation were followed by 199Hg NMR, X-ray absorption and Raman spectroscopic techniques. Our results show that in the dilute solutions (C Hg(II) = 8 – 9 mM), mixtures of di-, tri- (major) and tetrathiolate complexes exist at moderate cysteine excess (C H2Cys ~ 0.16 M) at pH 7.1. In the more concentrated solutions (C Hg(II) = 80 – 100 mM) with high cysteine excess (C H2Cys > 0.9 M), tetrathiolate [Hg( S-cysteinate) 4] m-6 ( m = 0 – 4) complexes dominate in the pH range 7.3 – 7.8, with lower charge than for the [Hg( S-Cys) 4] 6- complex due to protonation of some ( m) of the amino groups of the coordinated cysteine ligands. In conclusion, the results of this investigation could provide a key to the mechanism of biosorption and accumulation of Hg(II) ions in biological / environmental systems.« less

[Effect of greenbelt on pollutant dispersion in street canyon].

PubMed

Xu, Wei-Jia; Xing, Hong; Yu, Zhi

2012-02-01

The effect feature of greenbelt on flow field and pollutant dispersion in urban street canyon was researched. The greenbelt was assumed as uniform porous media and its aerodynamics property defined by the pressure loss coefficient. Subsequently, the pollutant dispersion in the street canyon of which there was greenbelt in the middle was simulated with the steady-state standard kappa-epsilon turbulence model and species transport equation. The simulated results agreed well with the wind-tunnel data. Compared with the treeless case, it finds that the street canyon contain a clockwise vortex, the pollutant concentration of the leeward was several times than the windward and the growth rate of pollutant concentration was 46.0%. The further simulation for the impact of tree crown position on the airflow and pollutant dispersion finds that the height of major vortex center in the street canyon increases with the height of tree crown and gradually closes the top of windward building This causes that the average wind speed in the street canyon decreases. Especially when the top of tree crown over the roof and hinder the air flow above the street canyon, the average pollutant concentration increases with the height of tree crown rapidly.

Concentration dependences of the density, viscosity, and refraction index of Cu(NO3)2 · 3H2O solutions in DMSO at 298 K

NASA Astrophysics Data System (ADS)

Mamyrbekova, A. K.

2013-03-01

Physicochemical properties (density, dynamic viscosity, refraction index) of the DMSO-Cu(NO3)2 · 3H2O system are studied in the concentration range of 0.01-2 M at 298 K. The refraction index of a solution of copper(II) nitrate in dimethylsulfoxide (DMSO) is measured at 288-318 K. The excess and partial molar volumes of the solvent and dissolved substance are calculated analytically.

Enhanced dissolution of cinnabar (mercuric sulfide) by dissolved organic matter isolated from the Florida Everglades

USGS Publications Warehouse

Ravichandran, Mahalingam; Aiken, George R.; Reddy, Michael M.; Ryan, Joseph N.

1998-01-01

Organic matter isolated from the Florida Everglades caused a dramatic increase in mercury release (up to 35 μM total dissolved mercury) from cinnabar (HgS), a solid with limited solubility. Hydrophobic (a mixture of both humic and fulvic) acids dissolved more mercury than hydrophilic acids and other nonacid fractions of dissolved organic matter (DOM). Cinnabar dissolution by isolated organic matter and natural water samples was inhibited by cations such as Ca2+. Dissolution was independent of oxygen content in experimental solutions. Dissolution experiments conducted in DI water (pH = 6.0) had no detectable (<2.5 nM) dissolved mercury. The presence of various inorganic (chloride, sulfate, or sulfide) and organic ligands (salicylic acid, acetic acid, EDTA, or cysteine) did not enhance the dissolution of mercury from the mineral. Aromatic carbon content in the isolates (determined by 13C NMR) correlated positively with enhanced cinnabar dissolution. ζ-potential measurements indicated sorption of negatively charged organic matter to the negatively charged cinnabar (pHpzc = 4.0) at pH 6.0. Possible mechanisms of dissolution include surface complexation of mercury and oxidation of surface sulfur species by the organic matter.

Pulp tissue dissolution capacity of QMix 2in1 irrigation solution.

PubMed

Arslan, Dilara; Guneser, Mehmet Burak; Kustarci, Alper; Er, Kursat; Siso, Seyda Herguner

2015-01-01

The aim of this study was to evaluate the tissue dissolution efficacy of four root canal irrigation solutions (sodium hypochlorite [NaOCl], chlorhexidine gluconate [CHX], Octenidine [OCT], and QMix 2in1) on bovine pulp tissue. Fifty bovine pulp tissue samples, each weighing 6.55 mg, were prepared and randomly divided into four experimental groups and one control group (n = 10) according to the dissolution irrigants used: (1) 5.25% NaOCl group; (2) 2% CHX group; (3) OCT group; (4) QMix 2in1 group; and (5) control group (saline solution). These samples were then placed into special bovine dentin reservoir models and immersed for 1 h with each test solution (0.1 mL of each) at room temperature. The pulp samples were then blotted dry and weighed again. The percentage of weight loss was calculated. Statistically analyzed with one-way analysis of variance and post-hoc Tukey tests (P = 0.05). Saline solution did not dissolve the bovine pulp tissue. All groups, except OCT, dissolved pulp samples more effectively than the control group (P < 0.05). The highest tissue dissolution was observed in 5.25% NaOCl group (P < 0.05). No statistically significant difference was found between the tissue-dissolving effect between QMix 2in1 and those of 2% CHX. Within the limitations of this in vitro study, NaOCl exhibited the best tissue-dissolving effect out of all solutions tested. CHX and QMix 2in1 were able to dissolve pulp tissue but less than NaOCl. OCT and saline solutions could not exhibit significantly tissue-dissolving effectiveness. This study shown that QMix 2in1 has little capacity to dissolve pulp tissue therefore used alone is not sufficient for this purpose.

Pulp tissue dissolution capacity of QMix 2in1 irrigation solution

PubMed Central

Arslan, Dilara; Guneser, Mehmet Burak; Kustarci, Alper; Er, Kursat; Siso, Seyda Herguner

2015-01-01

Objective: The aim of this study was to evaluate the tissue dissolution efficacy of four root canal irrigation solutions (sodium hypochlorite [NaOCl], chlorhexidine gluconate [CHX], Octenidine [OCT], and QMix 2in1) on bovine pulp tissue. Materials and Methods: Fifty bovine pulp tissue samples, each weighing 6.55 mg, were prepared and randomly divided into four experimental groups and one control group (n = 10) according to the dissolution irrigants used: (1) 5.25% NaOCl group; (2) 2% CHX group; (3) OCT group; (4) QMix 2in1 group; and (5) control group (saline solution). These samples were then placed into special bovine dentin reservoir models and immersed for 1 h with each test solution (0.1 mL of each) at room temperature. The pulp samples were then blotted dry and weighed again. The percentage of weight loss was calculated. Statistically analyzed with one-way analysis of variance and post-hoc Tukey tests (P = 0.05). Results: Saline solution did not dissolve the bovine pulp tissue. All groups, except OCT, dissolved pulp samples more effectively than the control group (P < 0.05). The highest tissue dissolution was observed in 5.25% NaOCl group (P < 0.05). No statistically significant difference was found between the tissue-dissolving effect between QMix 2in1 and those of 2% CHX. Conclusions: Within the limitations of this in vitro study, NaOCl exhibited the best tissue-dissolving effect out of all solutions tested. CHX and QMix 2in1 were able to dissolve pulp tissue but less than NaOCl. OCT and saline solutions could not exhibit significantly tissue-dissolving effectiveness. This study shown that QMix 2in1 has little capacity to dissolve pulp tissue therefore used alone is not sufficient for this purpose. PMID:26430374

An analysis of the potential for Glen Canyon Dam releases to inundate archaeological sites in the Grand Canyon, Arizona

USGS Publications Warehouse

Sondossi, Hoda A.; Fairley, Helen C.

2014-01-01

The development of a one-dimensional flow-routing model for the Colorado River between Lees Ferry and Diamond Creek, Arizona in 2008 provided a potentially useful tool for assessing the degree to which varying discharges from Glen Canyon Dam may inundate terrestrial environments and potentially affect resources located within the zone of inundation. Using outputs from the model, a geographic information system analysis was completed to evaluate the degree to which flows from Glen Canyon Dam might inundate archaeological sites located along the Colorado River in the Grand Canyon. The analysis indicates that between 4 and 19 sites could be partially inundated by flows released from Glen Canyon Dam under current (2014) operating guidelines, and as many as 82 archaeological sites may have been inundated to varying degrees by uncontrolled high flows released in June 1983. Additionally, the analysis indicates that more of the sites currently (2014) proposed for active management by the National Park Service are located at low elevations and, therefore, tend to be more susceptible to potential inundation effects than sites not currently (2014) targeted for management actions, although the potential for inundation occurs in both groups of sites. Because of several potential sources of error and uncertainty associated with the model and with limitations of the archaeological data used in this analysis, the results are not unequivocal. These caveats, along with the fact that dam-related impacts can involve more than surface-inundation effects, suggest that the results of this analysis should be used with caution to infer potential effects of Glen Canyon Dam on archaeological sites in the Grand Canyon.

Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland.

PubMed

Baynes, Edwin R C; Attal, Mikaël; Niedermann, Samuel; Kirstein, Linda A; Dugmore, Andrew J; Naylor, Mark

2015-02-24

Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (10(0) to 10(3) h). However, their impacts are rarely considered in studies of long-term landscape evolution (>10(3) y), because the mechanisms of erosion during such floods are poorly constrained. Here we use topographic analysis and cosmogenic (3)He surface exposure dating of fluvially sculpted surfaces to determine the impact of extreme flood events within the Jökulsárgljúfur canyon (northeast Iceland) and to constrain the mechanisms of bedrock erosion during these events. Surface exposure ages allow identification of three periods of intense canyon cutting about 9 ka ago, 5 ka ago, and 2 ka ago during which multiple large knickpoints retreated large distances (>2 km). During these events, a threshold flow depth was exceeded, leading to the toppling and transportation of basalt lava columns. Despite continuing and comparatively large-scale (500 m(3)/s) discharge of sediment-rich glacial meltwater, there is no evidence for a transition to an abrasion-dominated erosion regime since the last erosive event because the vertical knickpoints have not diffused over time. We provide a model for the evolution of the Jökulsárgljúfur canyon through the reconstruction of the river profile and canyon morphology at different stages over the last 9 ka and highlight the dominant role played by extreme flood events in the shaping of this landscape during the Holocene.

Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland

PubMed Central

Baynes, Edwin R. C.; Attal, Mikaël; Kirstein, Linda A.; Dugmore, Andrew J.; Naylor, Mark

2015-01-01

Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (100 to 103 h). However, their impacts are rarely considered in studies of long-term landscape evolution (>103 y), because the mechanisms of erosion during such floods are poorly constrained. Here we use topographic analysis and cosmogenic 3He surface exposure dating of fluvially sculpted surfaces to determine the impact of extreme flood events within the Jökulsárgljúfur canyon (northeast Iceland) and to constrain the mechanisms of bedrock erosion during these events. Surface exposure ages allow identification of three periods of intense canyon cutting about 9 ka ago, 5 ka ago, and 2 ka ago during which multiple large knickpoints retreated large distances (>2 km). During these events, a threshold flow depth was exceeded, leading to the toppling and transportation of basalt lava columns. Despite continuing and comparatively large-scale (500 m3/s) discharge of sediment-rich glacial meltwater, there is no evidence for a transition to an abrasion-dominated erosion regime since the last erosive event because the vertical knickpoints have not diffused over time. We provide a model for the evolution of the Jökulsárgljúfur canyon through the reconstruction of the river profile and canyon morphology at different stages over the last 9 ka and highlight the dominant role played by extreme flood events in the shaping of this landscape during the Holocene. PMID:25675484

Geomorphic Thresholds of Submarine Canyons Along the U.S. Atlantic Continental Margin

NASA Astrophysics Data System (ADS)

Brothers, D. S.; ten Brink, U. S.; Andrews, B. D.; Chaytor, J. D.

2011-12-01

Vast networks of submarine canyons and associated channels are incised into the U.S. Atlantic continental slope and rise. Submarine canyons form by differential erosion and deposition, primarily from sedimentary turbidity flows. Theoretical and laboratory studies have investigated the initiation of turbidity flows and their capacity to erode and entrain sedimentary material at distances far from the shelf edge. The results have helped understand the nature of turbidite deposits on the continental slope and rise. Nevertheless, few studies have examined the linkages between down-canyon sediment transport and the morphology of canyon/channel networks using mesoscale analyses of swath bathymetry data. We present quantitative analysis of 100-m resolution multibeam bathymetry data spanning ~616,000 km2 of the slope and rise between Georges Banks and the Blake Plateau (New England to North Carolina). Canyons are categorized as shelf-indenting or slope-confined based on spatial scale, vertical relief and connection with terrestrial river systems during sea level low stands. Shelf-indenting canyons usually represent the trunk-canyon of submerged channel networks. On the rise, shelf-indenting canyons have relatively well-developed channel-levees and sharp inner-thalwag incision suggesting much higher frequency and volume of turbidity flows. Because of the similarities between submarine canyon networks and terrestrial river systems, we apply methods originally developed to study fluvial morphology. Along-canyon profiles are extracted from the bathymetry data and the power-law relationship between thalwag gradient and drainage area is examined for more than 180 canyons along an ~1200 km stretch of the US Atlantic margin. We observe distinct thresholds in the power-law relationship between drainage area and gradient. Almost all canyons with heads on the upper slope contain at least two linear segments when plotted in log-log form. The first segment along the upper slope is flat

Spatial and Temporal Variation in DeSoto Canyon Macrofaunal Community Structure

NASA Astrophysics Data System (ADS)

Baco-Taylor, A.; Shantharam, A. K.

2016-02-01

Sediment-dwelling macrofauna (polychaetes, bivalves, and assorted crustaceans ≥ 300 µm) have long served as biological indicators of ecosystem stress. As part of evaluating the 2010 impact from the Deepwater Horizon blowout, we sampled 12 sites along and transverse to the DeSoto Canyon axis, Gulf of Mexico, as well as 2 control sites outside the Canyon. Sites ranged in depth from 479-2310 m. Three of the sites (PCB06, S36, and XC4) were sampled annually from 2012-2014. We provide an overview of the macrofauna community structure of canyon and non-canyon sites, as well as trends in community structure and diversity at the time-series sites. Compositionally, polychaetes dominated the communities, followed by tanaid crustaceans and bivalves. The total number of individuals was not significantly correlated with depth while the total number of taxa and species richness were. Rarefaction shows the deepest station, XC4 (2310 m) had the lowest diversity while NT800 (a non-canyon control at 800m) had the highest. Multivariate analysis shows the canyon assemblages fall into eight clusters with the non-canyon stations forming a separate ninth cluster, indicating a detectable difference in canyon and non-canyon communities. Time series stations show an increase in diversity from 2012-2014 with a strong overlap in community structure in 2013 and 2014 samples. Environmental analysis, via BEST, using data from 10 canyon sites and the controls, indicated depth in combination with latitude explain the most variation in macrofaunal community structure.

Modern landscape processes affecting archaeological sites along the Colorado River corridor downstream of Glen Canyon Dam, Glen Canyon National Recreation Area, Arizona

USGS Publications Warehouse

East, Amy E.; Sankey, Joel B.; Fairley, Helen C.; Caster, Joshua J.; Kasprak, Alan

2017-08-29

The landscape of the Colorado River through Glen Canyon National Recreation Area formed over many thousands of years and was modified substantially after the completion of Glen Canyon Dam in 1963. Changes to river flow, sediment supply, channel base level, lateral extent of sedimentary terraces, and vegetation in the post-dam era have modified the river-corridor landscape and have altered the effects of geologic processes that continue to shape the landscape and its cultural resources. The Glen Canyon reach of the Colorado River downstream of Glen Canyon Dam hosts many archaeological sites that are prone to erosion in this changing landscape. This study uses field evaluations from 2016 and aerial photographs from 1952, 1973, 1984, and 1996 to characterize changes in potential windblown sand supply and drainage configuration that have occurred over more than six decades at 54 archaeological sites in Glen Canyon and uppermost Marble Canyon. To assess landscape change at these sites, we use two complementary geomorphic classification systems. The first evaluates the potential for aeolian (windblown) transport of river-derived sand from the active river channel to higher elevation archaeological sites. The second identifies whether rills, gullies, or arroyos (that is, overland drainages that erode the ground surface) exist at the archaeological sites as well as the geomorphic surface, and therefore the relative base level, to which those flow paths drain. Results of these assessments are intended to aid in the management of irreplaceable archaeological resources by the National Park Service and stakeholders of the Glen Canyon Dam Adaptive Management Program.

NASA Satellite Reveals Grandeur of Arizona Grand Canyon

NASA Image and Video Library

2011-10-14

Arguably one of America most magnificent national parks is the Grand Canyon in northern Arizona. NASA Terra spacecraft captured this image looking to the northeast, the buildings and roads in the center foreground are Grand Canyon Village.

Distribution and transport of suspended particulate matter in Monterey Canyon, California

USGS Publications Warehouse

Xu, J. P.; Noble, M.; Eittreim, S.L.; Rosenfeld, L.K.; Schwing, F.B.; Pilskaln, C.H.

2002-01-01

From August 1993 to August 1994, six moorings that measure current, temperature, salinity, and water clarity were deployed along the axis of Monterey Canyon to study the circulation and transport of water and suspended particulate matter through the canyon system. The moorings occupied three sites that are morphologically different: a narrow transverse section (axis width 900 m) at 1450 m water depth, a wide transverse section at 2837 m, and a third site in the fan valley axis farther offshore at 3223 m that recorded for 3 yr. In addition, CTD/transmissometer casts were conducted within and near the Monterey Canyon during four cruises. Our data show a mainly biogenic, surface turbid layer, a limited intermediate nepheloid layer, and a bottom nepheloid layer. There is a consistent presence of a turbid layer within the canyon at a water depth of about 1500 m. Tidal flow dominates at all sites, but currents above the canyon rim and within the canyon appear to belong to two distinct dynamic systems. Bottom intensification of currents plays an important role in raising the near-bottom shear stress high enough that bottom sediments are often, if not always, resuspended. Mean flow pattern suggests a convergence zone between the narrow and wide site: the near-bed (100 m above bottom where the lowest current meter was located) mean transport is down-canyon at the 1450-m site, while the near-bottom transport at the 2837-m site is up-canyon, at a smaller magnitude. Transport at the 3223-m site is dominantly NNW, cross-canyon, with periods of up-canyon flow over 3 yr. A very high-turbidity event was recorded 100 m above the canyon bottom at the narrow site. The event started very abruptly and lasted more than a week. This event was not detected at either of the deeper sites. A canyon head flushing event is likely the cause. ?? 2002 Elsevier Science B.V. All rights reserved.

Greenhouse gases dissolved in soil solution - often ignored, but important?

NASA Astrophysics Data System (ADS)

Weymann, Daniel; Brueggemann, Nicolas; Puetz, Thomas; Vereecken, Harry

2014-05-01

Flux measurements of climate-relevant trace gases from soils are frequently undertaken in contemporary ecosystem studies and substantially contribute to our understanding of greenhouse gas balances of the biosphere. While the great majority of such investigations builds on closed chamber and eddy covariance measurements, where upward gas fluxes to the atmosphere are measured, fewest concurrently consider greenhouse gas dissolution in the seepage and leaching of dissolved gases via the vadose zone to the groundwater. Here we present annual leaching losses of dissolved N2O and CO2 from arable, grassland, and forest lysimeter soils from three sites differing in altitude and climate. We aim to assess their importance in comparison to direct N2O emission, soil respiration, and further leaching parameters of the C- and N cycle. The lysimeters are part of the Germany-wide lysimeter network initiative TERENO-SoilCan, which investigates feedbacks of climate change to the pedosphere on a long-term scale. Soil water samples were collected weekly from different depths of the profiles by means of suction cups. A laboratory pre-experiment proved that no degassing occurred under those sampling conditions. We applied the headspace equilibration technique to determine dissolved gas concentrations by gas chromatography. The seepage water of all lysimeters was consistently supersaturated with N2O and CO2 compared to water equilibrated ambient air. In terms of N2O, leaching losses increased in the ascending order forest, grassland, and arable soils, respectively. In case of the latter soils, we observed a strong variability of N2O, with dissolved concentrations up to 23 μg N L-1. However, since seepage discharge of the arable lysimeters was comparatively small and mostly limited to the hydrological winter season, leached N2O appeared to be less important than direct N2O emissions. In terms of dissolved CO2,our measurements revealed considerable leaching losses from the mountainous

Dissolved Divalent Metal and pH Effects on Amino Acid Polymerization: A Thermodynamic Evaluation.

PubMed

Kitadai, Norio

2017-03-01

Polymerization of amino acids is a fundamentally important step for the chemical evolution of life. Nevertheless, its response to changing environmental conditions has not yet been well understood because of the lack of reliable quantitative information. For thermodynamics, detailed prediction over diverse combinations of temperature and pH has been made only for a few amino acid-peptide systems. This study used recently reported thermodynamic dataset for the polymerization of the simplest amino acid "glycine (Gly)" to its short peptides (di-glycine and tri-glycine) to examine chemical and structural characteristics of amino acids and peptides that control the temperature and pH dependence of polymerization. Results showed that the dependency is strongly controlled by the intramolecular distance between the amino and carboxyl groups in an amino acid structure, although the side-chain group role is minor. The polymerization behavior of Gly reported earlier in the literature is therefore expected to be a typical feature for those of α-amino acids. Equilibrium calculations were conducted to examine effects of dissolved metals as a function of pH on the monomer-polymer equilibria of Gly. Results showed that metals shift the equilibria toward the monomer side, particularly at neutral and alkaline pH. Metals that form weak interaction with Gly (e.g., Mg 2+ ) have no noticeable influence on the polymerization, although strong interaction engenders significant decrease of the equilibrium concentrations of Gly peptides. Considering chemical and structural characteristics of Gly and Gly peptides that control their interactions with metals, it can be expected that similar responses to the addition of metals are applicable in the polymerization of neutral α-amino acids. Neutral and alkaline aqueous environments with dissolved metals having high affinity with neutral α-amino acids (e.g., Cu 2+ ) are therefore not beneficial places for peptide bond formation on the primitive

Fertilization and pH effects on processes and mechanisms controlling dissolved inorganic phosphorus in soils

NASA Astrophysics Data System (ADS)

Devau, Nicolas; Hinsinger, Philippe; Le Cadre, Edith; Colomb, Bruno; Gérard, Frédéric

2011-05-01

We used of a set of mechanistic adsorption models (1-pK TPM, ion exchange and Nica-Donnan) within the framework of the component additive (CA) approach in an attempt to determine the effect of repeated massive application of inorganic P fertilizer on the processes and mechanisms controlling the concentration of dissolved inorganic phosphorus (DIP) in soils. We studied the surface layer of a Luvisol with markedly different total concentrations of inorganic P as the result of different P fertilizer history (i.e. massive or no application for 40 years). Soil pH was made to vary from acid to alkaline. Soil solutions were extracted with water and CaCl 2 (0.01 M). The occurrence of montmorillonite led us to determine the binding properties of P and Ca ions for this clay mineral. Satisfactory results were obtained using generic values for model parameters and soil-specific ones, which were either determined directly by measurements or estimated from the literature. We showed that adsorption largely controlled the variations of DIP concentration and that, because of kinetic constrains, only little Ca-phosphates may be precipitated under alkaline conditions, particularly in the P fertilized treatment. The mineral-P pool initially present in both P treatments did not dissolve significantly during the course of the experiments. The adsorption of Ca ions onto soil minerals also promoted adsorption of P ions through electrostatic interactions. The intensity of the mechanism was high under neutral to alkaline conditions. Changes in DIP concentration as a function of these environmental variables can be related to changes in the contribution of the various soil minerals to P adsorption. The extra P adsorbed in the fertilized treatment compared with the control treatment was mainly adsorbed onto illite. This clay mineral was the major P-fixing constituent from neutral to alkaline pH conditions, because the repulsion interactions between deprotonated hydroxyl surface sites and P

Geology of the head of Lydonia Canyon, U.S. Atlantic outer continental shelf

USGS Publications Warehouse

Twichell, David C.

1983-01-01

The geology of the part of Lydonia Canyon shoreward of the continental shelf edge on the southern side of Georges Bank was mapped using high-resolution seismic-reflection and side-scan sonar techniques and surface sediment grab samples. The head of the canyon incises Pleistocene deltaic deposits and Miocene shallow marine strata. Medium sand containing some coarse sand and gravel covers the shelf except for a belt of very fine sand containing no gravel on either side of the canyon in water depths of 125–140 m. Gravel and boulders, presumably ice-rafted debris, cover the rim of the canyon. The canyon floor and canyon wall gullies are covered by coarse silt of Holocene age which is as much as 25 m thick, and Miocene and Pleistocene strata are exposed on the spurs between gullies. The Holocene sediment is restricted to the canyon shoreward of the shelf edge and has been winnowed from the shelf. Furrows cut in the shelf sands and ripples on the shelf and in the canyon suggest that sediment continues to be moved in this area. Sediment distribution, however, is inconsistent with that expected from the inferred westward sediment transport on the shelf. Either the fine-grained deposits on the shelf to either side of the canyon head are relict or there is a significant component of offshore transport around the canyon head.In the head of Oceanographer Canyon, only 40 km west of Lydonia Canyon, present conditions are strikingly different. The floor of Oceanographer Canyon is covered by sand waves, and their presence indicates active reworking of the bottom sediments by strong currents. The close proximity of the two canyons suggests that the relative importance of processes acting in canyons can be variable over short distances.

Dissolution of bovine pulp tissue in solutions consisting of varying NaOCl concentrations and combined with EDTA.

PubMed

Irala, Luis Eduardo Duarte; Grazziotin-Soares, Renata; Salles, Alexandre Azevedo; Munari, Aline Zen; Pereira, Joseani Santos

2010-01-01

This in vitro study evaluated (1) the dissolution of bovine pulp tissue in solutions consisting of varying NaOCl concentrations and combined with EDTA; and (2) the pH of these solutions before and after the experiment. The independent variables were the concentration and the volume of the solution. Thirty bovine pulps were divided in equal fragments, resulting in 90 fragments of pulp tissue. Each fragment was immersed in one of the following solutions: 1% NaOCl (4 ml), 2.5% NaOCl (4 ml), 1% NaOCl + 17% EDTA (2 ml : 2 ml), 1% NaOCl + 17% EDTA (1 ml : 3 ml), 2.5% NaOCl + 17% EDTA (2 ml : 2 ml), and 2.5% NaOCl + 17% EDTA (1 ml : 3 ml). The test solutions were dichotomized as either able or not able to dissolve the tissue, the latter being attributed when the dissolution of the pulp tissue was not complete within 48 hours. When the samples were able to dissolve the tissue, the time required for complete tissue dissolution was submitted to statistical analysis. The pH of the solutions was measured before and after the experiment. The pH variable was dichotomized as either changed or unchanged. The results demonstrated that the NaOCl solutions combined with 17% EDTA were not able to dissolve the tissue. The t-test revealed that the 2.5% NaOCl solution presented a lower mean dissolution time than the 1% NaOCl solution (p < 0.001). The pH of the solutions with equal volumes of NaOCl and EDTA decreased in 48 hours.

27 CFR 9.152 - Malibu-Newton Canyon.

Code of Federal Regulations, 2010 CFR

2010-04-01

....” (2) Then south along Kanan Dume Road to the point where an unnamed, unimproved dirt road referred to... Canyon Road to an unnamed, unimproved dirt road referred to by the petitioner as Newton Mountain Way at... southeastern ridgeline of Newton Canyon, to an unnamed, unimproved dirt road referred to by the petitioner as...

Sediment Dating With 210Pb and 137Cs In Monterey Canyon, California Reveal the extent of recent sediment movement down canyon

NASA Astrophysics Data System (ADS)

Lorenson, T. D.; Maier, K. L.; Gwiazda, R.; Paull, C. K.; McGann, M.

2017-12-01

Submarine canyons are major vectors of sediment transport off the continent into the deep sea. Recent results from the Monterey Coordinated Canyon Experiment document fifteen sediment transport events occurred during an 18-month period from 2015 to 2017, and three of them reached at least to 1850m. In an attempt to constrain the timing and rate in which sediments were transported down canyons in these and earlier events we have collected sediment cores and measured the sedimentation rates using 210Pb and 137Cs dating techniques along the axis of Monterey Canyon. We employed transects of precisely located ROV collected push cores and vibracores collected at water depths ranging from 300m to 2900m perpendicular to the canyon axis using a remotely operated vehicle (ROV). Some cores were taken in 2013 and compared with those taken in 2017. We focused on cores from terraces that are between 60m and 75m above the canyon thalweg in water depths between 300 and 1500 m and in cores collected form the canyon's axial channel between 1800 and 2900 m water depths where the canyon widens considerably. Generally sedimentation rates vary with depth, with the highest sedimentation rate closest to land, but vary substantially across successive terraces. Sawtooth-shaped excess 210Pb and 137Cs profiles with depth at almost all sites at least to 1500m imply several episodes of deposition and reworking of sediment on the terraces suggesting multiple sediment transport events. The excess 210Pb in many cores reach depths of up to 1m implying sedimentation rates greater than 10mm per year. At the deepest site (2900m) about 10 cm of fine hemipelagic sediment overlies sand indicating a high-energy sediment flow event. In 2014 the measured 210Pb sedimentation rate of 0.6 to 0.8mm per year indicates that the last 10 cm of sediment have been deposited and undisturbed since about the year 1910 showing that recent events have not reached this depth. Measurements are on going to determine if the

Dispersion and photochemical evolution of reactive pollutants in street canyons

NASA Astrophysics Data System (ADS)

Kwak, Kyung-Hwan; Baik, Jong-Jin; Lee, Kwang-Yeon

2013-05-01

Dispersion and photochemical evolution of reactive pollutants in street canyons with canyon aspect ratios of 1 and 2 are investigated using a computational fluid dynamics (CFD) model coupled with the carbon bond mechanism IV (CBM-IV). Photochemical ages of NOx and VOC are expressed as a function of the NO2-to-NOx and toluene-to-xylene ratios, respectively. These are found to be useful for analyzing the O3 and OH oxidation processes in the street canyons. The OH oxidation process (O3 oxidation process) is more pronounced in the upper (lower) region of the street canyon with a canyon aspect ratio of 2, which is characterized by more (less) aged air. In the upper region of the street canyon, O3 is chemically produced as well as transported downward across the roof level, whereas O3 is chemically reduced in the lower region of the street canyon. The O3 chemical production is generally favorable when the normalized photochemical ages of NOx and VOC are larger than 0.55 and 0.28, respectively. The sensitivities of O3 chemical characteristics to NOx and VOC emission rates, photolysis rate, and ambient wind speed are examined for the lower and upper regions of the street canyon with a canyon aspect ratio of 2. The O3 concentration and the O3 chemical production rate divided by the O3 concentration increase as the NOx emission rate decreases and the VOC emission rate and photolysis rate increase. The O3 concentration is less sensitive to the ambient wind speed than to other factors considered. The relative importance of the OH oxidation process compared to the O3 oxidation process increases with increasing NOx emission rate and photolysis rate and decreasing VOC emission rate. In this study, both O3 and OH oxidation processes are found to be important in street-canyon scale chemistry. The methodology of estimating the photochemical ages can potentially be adopted to neighborhood scale chemistry.

An empirical method for estimating instream pre-mining pH and dissolved Cu concentration in catchments with acidic drainage and ferricrete

USGS Publications Warehouse

Nimick, D.A.; Gurrieri, J.T.; Furniss, G.

2009-01-01

Methods for assessing natural background water quality of streams affected by historical mining are vigorously debated. An empirical method is proposed in which stream-specific estimation equations are generated from relationships between either pH or dissolved Cu concentration in stream water and the Fe/Cu concentration ratio in Fe-precipitates presently forming in the stream. The equations and Fe/Cu ratios for pre-mining deposits of alluvial ferricrete then were used to reconstruct estimated pre-mining longitudinal profiles for pH and dissolved Cu in three acidic streams in Montana, USA. Primary assumptions underlying the proposed method are that alluvial ferricretes and modern Fe-precipitates share a common origin, that the Cu content of Fe-precipitates remains constant during and after conversion to ferricrete, and that geochemical factors other than pH and dissolved Cu concentration play a lesser role in determining Fe/Cu ratios in Fe-precipitates. The method was evaluated by applying it in a fourth, naturally acidic stream unaffected by mining, where estimated pre-mining pH and Cu concentrations were similar to present-day values, and by demonstrating that inflows, particularly from unmined areas, had consistent effects on both the pre-mining and measured profiles of pH and Cu concentration. Using this method, it was estimated that mining has affected about 480 m of Daisy Creek, 1.8 km of Fisher Creek, and at least 1 km of Swift Gulch. Mean values of pH decreased by about 0.6 pH units to about 3.2 in Daisy Creek and by 1-1.5 pH units to about 3.5 in Fisher Creek. In Swift Gulch, mining appears to have decreased pH from about 5.5 to as low as 3.6. Dissolved Cu concentrations increased due to mining almost 40% in Daisy Creek to a mean of 11.7 mg/L and as much as 230% in Fisher Creek to 0.690 mg/L. Uncertainty in the fate of Cu during the conversion of Fe-precipitates to ferricrete translates to potential errors in pre-mining estimates of as much as 0.25 units

Dissolved metals and associated constituents in abandoned coal-mine discharges, Pennsylvania, USA. Part 2: Geochemical controls on constituent concentrations

USGS Publications Warehouse

Cravotta, C.A.

2008-01-01

Water-quality data for discharges from 140 abandoned mines in the Anthracite and Bituminous Coalfields of Pennsylvania reveal complex relations among the pH and dissolved solute concentrations that can be explained with geochemical equilibrium models. Observed values of pH ranged from 2.7 to 7.3 in the coal-mine discharges (CMD). Generally, flow rates were smaller and solute concentrations were greater for low-pH CMD samples; pH typically increased with flow rate. Although the frequency distribution of pH was similar for the anthracite and bituminous discharges, the bituminous discharges had smaller median flow rates; greater concentrations of SO4, Fe, Al, As, Cd, Cu, Ni and Sr; comparable concentrations of Mn, Cd, Zn and Se; and smaller concentrations of Ba and Pb than anthracite discharges with the same pH values. The observed relations between the pH and constituent concentrations can be attributed to (1) dilution of acidic water by near-neutral or alkaline ground water; (2) solubility control of Al, Fe, Mn, Ba and Sr by hydroxide, sulfate, and/or carbonate minerals; and (3) aqueous SO4-complexation and surface-complexation (adsorption) reactions. The formation of AlSO4+ and AlHSO42 + complexes adds to the total dissolved Al concentration at equilibrium with Al(OH)3 and/or Al hydroxysulfate phases and can account for 10-20 times greater concentrations of dissolved Al in SO4-laden bituminous discharges compared to anthracite discharges at pH of 5. Sulfate complexation can also account for 10-30 times greater concentrations of dissolved FeIII concentrations at equilibrium with Fe(OH)3 and/or schwertmannite (Fe8O8(OH)4.5(SO4)1.75) at pH of 3-5. In contrast, lower Ba concentrations in bituminous discharges indicate that elevated SO4 concentrations in these CMD sources could limit Ba concentrations by the precipitation of barite (BaSO4). Coprecipitation of Sr with barite could limit concentrations of this element. However, concentrations of dissolved Pb, Cu, Cd, Zn

Populating a Control Point Database: A cooperative effort between the USGS, Grand Canyon Monitoring and Research Center and the Grand Canyon Youth Organization

NASA Astrophysics Data System (ADS)

Brown, K. M.; Fritzinger, C.; Wharton, E.

2004-12-01

The Grand Canyon Monitoring and Research Center measures the effects of Glen Canyon Dam operations on the resources along the Colorado River from Glen Canyon Dam to Lake Mead in support of the Grand Canyon Adaptive Management Program. Control points are integral for geo-referencing the myriad of data collected in the Grand Canyon including aerial photography, topographic and bathymetric data used for classification and change-detection analysis of physical, biologic and cultural resources. The survey department has compiled a list of 870 control points installed by various organizations needing to establish a consistent reference for data collected at field sites along the 240 mile stretch of Colorado River in the Grand Canyon. This list is the foundation for the Control Point Database established primarily for researchers, to locate control points and independently geo-reference collected field data. The database has the potential to be a valuable mapping tool for assisting researchers to easily locate a control point and reduce the occurrance of unknowingly installing new control points within close proximity of an existing control point. The database is missing photographs and accurate site description information. Current site descriptions do not accurately define the location of the point but refer to the project that used the point, or some other interesting fact associated with the point. The Grand Canyon Monitoring and Research Center (GCMRC) resolved this problem by turning the data collection effort into an educational exercise for the participants of the Grand Canyon Youth organization. Grand Canyon Youth is a non-profit organization providing experiential education for middle and high school aged youth. GCMRC and the Grand Canyon Youth formed a partnership where GCMRC provided the logistical support, equipment, and training to conduct the field work, and the Grand Canyon Youth provided the time and personnel to complete the field work. Two data

Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

NASA Astrophysics Data System (ADS)

van Pinxteren, Dominik; Wadinga Fomba, Khanneh; Mertes, Stephan; Müller, Konrad; Spindler, Gerald; Schneider, Johannes; Lee, Taehyoung; Collett, Jeffrey L.; Herrmann, Hartmut

2016-03-01

Cloud water samples were taken in September/October 2010 at Mt. Schmücke in a rural, forested area in Germany during the Lagrange-type Hill Cap Cloud Thuringia 2010 (HCCT-2010) cloud experiment. Besides bulk collectors, a three-stage and a five-stage collector were applied and samples were analysed for inorganic ions (SO42-,NO3-, NH4+, Cl-, Na+, Mg2+, Ca2+, K+), H2O2 (aq), S(IV), and dissolved organic carbon (DOC). Campaign volume-weighted mean concentrations were 191, 142, and 39 µmol L-1 for ammonium, nitrate, and sulfate respectively, between 4 and 27 µmol L-1 for minor ions, 5.4 µmol L-1 for H2O2 (aq), 1.9 µmol L-1 for S(IV), and 3.9 mgC L-1 for DOC. The concentrations compare well to more recent European cloud water data from similar sites. On a mass basis, organic material (as DOC × 1.8) contributed 20-40 % (event means) to total solute concentrations and was found to have non-negligible impact on cloud water acidity. Relative standard deviations of major ions were 60-66 % for solute concentrations and 52-80 % for cloud water loadings (CWLs). The similar variability of solute concentrations and CWLs together with the results of back-trajectory analysis and principal component analysis, suggests that concentrations in incoming air masses (i.e. air mass history), rather than cloud liquid water content (LWC), were the main factor controlling bulk solute concentrations for the cloud studied. Droplet effective radius was found to be a somewhat better predictor for cloud water total ionic content (TIC) than LWC, even though no single explanatory variable can fully describe TIC (or solute concentration) variations in a simple functional relation due to the complex processes involved. Bulk concentrations typically agreed within a factor of 2 with co-located measurements of residual particle concentrations sampled by a counterflow virtual impactor (CVI) and analysed by an aerosol mass spectrometer (AMS), with the deviations being mainly caused by systematic

Cloud water composition during HCCT-2010: Scavenging efficiencies, solute concentrations, and droplet size dependence of inorganic ions and dissolved organic carbon

NASA Astrophysics Data System (ADS)

van Pinxteren, D.; Fomba, K. W.; Mertes, S.; Müller, K.; Spindler, G.; Schneider, J.; Lee, T.; Collett, J.; Herrmann, H.

2015-09-01

Cloud water samples were taken in September/October 2010 at Mt. Schmücke in a rural, forested area in Germany during the Lagrange-type Hill Cap Cloud Thuringia 2010 (HCCT-2010) cloud experiment. Besides bulk collectors, a 3-stage and a 5-stage collector were applied and samples were analysed for inorganic ions (SO42-, NO3-, NH4+, Cl-, Na+, Mg2+, Ca2+, K+), H2O2 (aq), S(IV), and dissolved organic carbon (DOC). Campaign volume-weighted mean concentrations were 191, 142, and 39 μmol L-1 for ammonium, nitrate, and sulfate, respectively, between 4 and 27 μmol L-1 for minor ions, 5.4 μmol L-1 for H2O2 (aq), 1.9 μmol L-1 for S(IV), and 3.9 mgC L-1 for DOC. The concentrations compare well to more recent European cloud water data from similar sites. On a mass basis, organic material (as DOC · 1.8) contributed 20-40 % (event means) to total solute concentrations and was found to have non-negligible impact on cloud water acidity. Relative standard deviations of major ions were 60-66 % for solute concentrations and 52-80 % for cloud water loadings (CWLs). Contrary to some earlier suggestions, the similar variability of solute concentrations and CWLs together with the results of back trajectory analysis and principal component analysis, suggests that concentrations in incoming air masses (i.e. air mass history), rather than cloud liquid water content (LWC) was the main factor controlling bulk solute concentrations at Mt. Schmücke. Droplet effective radius was found to be a somewhat better predictor for cloud water total ionic content (TIC) than LWC, even though no single explanatory variable can fully describe TIC (or solute concentration) variations in a simple functional relation due to the complex processes involved. Bulk concentrations typically agreed within a factor of 2 with co-located measurements of residual particle concentrations sampled by a counterflow virtual impactor (CV) and analysed by an aerosol mass spectrometer (AMS), with the deviations being mainly

Ultrafast Scavenging of the Precursor of H(•) Atom, (e(-), H3O(+)), in Aqueous Solutions.

PubMed

Balcerzyk, Anna; Schmidhammer, Uli; Wang, Furong; de la Lande, Aurélien; Mostafavi, Mehran

2016-09-01

Picosecond pulse radiolysis measurements have been performed in several highly concentrated HClO4 and H3PO4 aqueous solutions containing silver ions at different concentrations. Silver ion reduction is used to unravel the ultrafast reduction reactions observed at the end of a 7 ps electron pulse. Solvated electrons and silver atoms are observed by the pulse (electron beam)-probe (supercontinuum light) method. In highly acidic solutions, ultrafast reduction of silver ions is observed, a finding that is not compatible with a reaction between the H(•) atom and silver ions, which is known to be thermally activated. In addition, silver ion reduction is found to be even more efficient in phosphoric acid solution than that in neutral solution. In the acidic solutions investigated here, the species responsible for the reduction of silver atoms is considered to be the precursor of the H(•) atom. This precursor, denoted (e(-), H3O(+)), is a pair constituting an electron (not fully solvated) and H3O(+). Its structure differs from that of the pair of a solvated electron and a hydronium ion (es(-), H3O(+)), which absorbs in the visible region. The (e(-), H3O(+)) pair , called the pre-H(•) atom here, undergoes ultrafast electron transfer and can, like the presolvated electron, reduce silver ions much faster than the H(•) atom. Moreover, it is found that with the same concentration of H3O(+) the reduction reaction is favored in the phosphoric acid solution compared to that in the perchloric acid solution because of the less-efficient electron solvation process. The kinetics show that among the three reducing species, (e(-), H3O(+)), (es(-), H3O(+)), and H(•) atom, the first one is the most efficient.

Physiographic rim of the Grand Canyon, Arizona: a digital database

USGS Publications Warehouse

Billingsley, George H.; Hampton, Haydee M.

1999-01-01

This Open-File report is a digital physiographic map database. This pamphlet serves to introduce and describe the digital data. There is no paper map included in the Open-File report. The report does include, however, PostScript and PDF format plot files, each containing an image of the map. For those interested in a paper plot of information contained in the database or in obtaining the PostScript plot files, please see the section entitled "For Those Who Don't Use Digital Geologic Map Databases" below. This physiographic map of the Grand Canyon is modified from previous versions by Billingsley and Hendricks (1989), and Billingsley and others (1997). The boundary is drawn approximately along the topographic rim of the Grand Canyon and its tributary canyons between Lees Ferry and Lake Mead (shown in red). Several isolated small mesas, buttes, and plateaus are within this area, which overall encompasses about 2,600 square miles. The Grand Canyon lies within the southwestern part of the Colorado Plateaus of northern Arizona between Lees Ferry, Colorado River Mile 0, and Lake Mead, Colorado River Mile 277. The Colorado River is the corridor for raft trips through the Grand Canyon. Limestone rocks of the Kaibab Formation form most of the north and south rims of the Grand Canyon, and a few volcanic rocks form the north rim of parts of the Uinkaret and Shivwits Plateaus. Limestones of the Redwall Limestone and lower Supai Group form the rim of the Hualapai Plateau area, and Limestones of Devonian and Cambrian age form the boundary rim near the mouth of Grand Canyon at the Lake Mead. The natural physiographic boundary of the Grand Canyon is roughly the area a visitor would first view any part of the Grand Canyon and its tributaries.

Shelf-Slope Exchanges near Submarine Canyons in the Southern Mid-Atlantic Bight

NASA Astrophysics Data System (ADS)

Wang, H.; Gong, D.

2016-02-01

Shelf-slope exchange processes are major physical drivers of biological productivity near the shelf-break. Observations from two Slocum ocean gliders in Fall 2013 are used to explore the driving mechanisms of cross-shelf-slope exchanges near Norfolk Canyon and Washington Canyon in the southern Mid-Atlantic Bight. Offshore excursion of bottom "cold pool" water, and shoreward intrusion of slope water at surface layer and thermocline depth occurred during northeasterly along-shelf winds. The saline intrusions of surface slope water resided between the cold pool and surface shelf water, and reached the bottom on the outer and mid-shelf, while the offshore excursion of cold pool water was found between the surface and intermediate slope-water over the canyon. Ekman transport calculation shows wind-driven cross-shelf transport can partially explain this interleaving pattern of intrusions. Scaling analysis of double diffusive processes demonstrate that they also likely played a role in the cross-shelf-slope exchange. A unique canyon upwelling event was captured in and around Washington Canyon during a period of southwesterly along-shelf wind and along-shelf flow to the northeast. The water mass distributions and isopycnal responses in both along-canyon and cross-canyon transects are consistent with scaling analysis and numerical studies of canyon upwelling. Temperature-Salinity properties of water masses in the canyon suggest active mixing between shelf and slope water masses near the canyon head. These results point to the importance of wind, double diffusion, and canyon topography on shelf-slope exchange in the MAB.

Evolution and Submarine Landslide Potential of Monterey Canyon Head, Offshore Central California

NASA Astrophysics Data System (ADS)

Maier, K. L.; Johnson, S. Y.; Hart, P. E.; Hartwell, S. R.

2016-12-01

Monterey Canyon, offshore central California, incises the shelf from near the shoreline to 30 km seaward where axial water depths approach 2,000 m. It is one of the world's most studied submarine canyons, yet debate continues concerning its age, formation, and associated geologic hazards. To address these issues, the USGS, with partial support from the California Seafloor Mapping Program, collected hundreds of kilometers of high-resolution, mini-sparker, single-channel (2009 and 2011 surveys) and multichannel (2015 survey) seismic-reflection profiles near the canyon head. The seismic data were combined with multibeam bathymetry to generate a geologic map of the proximal canyon, which delineates numerous faults and compound submarine landslide headwall scarps (covering up to 4 km2) along canyon walls. Seismic-reflection data reveal a massive ( 100 km2 lateral extent) paleochannel cut-and-fill complex underlying the proximal canyon. These subsurface cut-and-fill deposits span both sides of the relatively narrow modern canyon head, crop out in canyon walls, and incise into Purisima Formation (late Miocene and Pliocene) bedrock to depths of up to 0.3 s two-way travel time ( 240 m) below the modern shelf. We propose that the paleochannel complex represents previous locations of a migrating canyon head, and attribute its origin to multiple alternating cycles of fluvial and submarine canyon erosion and deposition linked to fluctuating sea levels. Thus, the canyon head imaged in modern bathymetry is a relatively young feature, perhaps forming in the last 20,000 years of sea-level rise. The paleocanyon deposits are significantly less consolidated than bedrock in deeper canyon walls, and therefore, are probably more prone to submarine landsliding. Nearby mapped faults occur within the active, distributed, San Andreas fault system, and earthquake-generated strong ground motions are likely triggers for past and future submarine landslides and potential associated tsunamis.

Deep-Water Coral Diversity and Habitat Associations: Differences among Northeast Atlantic Submarine Canyons

NASA Astrophysics Data System (ADS)

Shank, T. M.

2016-02-01

From 2012 to 2015, annual seafloor surveys using the towed camera TowCam were used to characterize benthic ecosystems and habitats to groundtruth recently developed habitat suitability models that predict deep-sea coral locations in northwest Atlantic canyons. Faunal distribution, abundance, and habitat data were obtained from more than 90 towed camera surveys in 21 canyons, specifically Tom's, Hendrickson, Veatch, Gilbert, Ryan, Powell, Munson, Accomac, Leonard, Washington, Wilmington, Lindenkohl, Clipper, Sharpshooter, Welker, Dogbody, Chebacco, Heel Tapper, File Bottom, Carteret, and Spencer Canyons, as well as unnamed minor canyons and inter-canyon areas. We also investigated additional canyons including Block, Alvin, Atlantis, Welker, Heezen, Phoenix, McMaster, Nantucket, and two minor canyons and two intercanyon areas through high-definition ROV image surveys from the NOAA CANEX 2013 and 2014 expeditions. Significant differences in species composition and distribution correlated with specific habitat types, depth, and individual canyons. High abundances and diversity of scleractinians, antipatharians, octocorals and sponges were highly correlated with habitat substrates, includingvertical canyon walls, margins, sediments, cobbles, boulders, and coral rubble habitat. Significant differences in species composition among canyons were observed across similar depths suggesting that many canyons may have their own biological and geological signature. Locating and defining the composition and distribution of vulnerable coral ecosystems in canyons in concert with validating predictive species distribution modeling has resulted in the regional management and conservation recommendations of these living resources and the largest proposed Marine Protected Area in North American waters.

Lung cancer risk assessment due to traffic-generated particles exposure in urban street canyons: A numerical modelling approach.

PubMed

Scungio, M; Stabile, L; Rizza, V; Pacitto, A; Russi, A; Buonanno, G

2018-08-01

Combustion-generated nanoparticles are responsible for negative health effects due to their ability to penetrate in the lungs, carrying toxic compounds with them. In urban areas, the coexistence of nanoparticle sources and particular street-building configurations can lead to very high particle exposure levels. In the present paper, an innovative approach for the evaluation of lung cancer incidence in street canyon due to exposure to traffic-generated particles was proposed. To this end, the literature-available values of particulate matter, PAHs and heavy metals emitted from different kind of vehicles were used to calculate the Excess Lifetime Cancer Risk (ELCR) at the tailpipe. The estimated ELCR was then used as input data in a numerical CFD (Computational Fluid Dynamics) model that solves the mass, momentum, turbulence and species transport equations, in order to evaluate the cancer risk in every point of interest inside the street canyon. Thus, the influence of wind speed and street canyon geometry (H/W, height of building, H and width of the street, W) on the ELCR at street level was evaluated by means of a CFD simulation. It was found that the ELCR calculated on the leeward and windward sides of the street canyon at a breathable height of 1.5 m, for people exposed 15 min per day for 20 years, is equal to 1.5 × 10 -5 and 4.8 × 10 -6 , respectively, for wind speed of 1 m/s and H/W equal to 1. The ELCR at street level results higher on the leeward side for aspect ratios equal to 1 and 3, while for aspect ratio equal to 2 it is higher on the windward side. In addition, the simulations showed that with the increasing of wind speed the ELCR becomes lower everywhere in the street canyon, due to the increased in dispersion. Copyright © 2018 Elsevier B.V. All rights reserved.

Lava Flows in the Grand Canyon

NASA Technical Reports Server (NTRS)

2003-01-01

Over vast expanses of time, natural processes like floods and volcanoes deposit layers of rock on the Earth's surface. To delve down through layers of rock is to explore our planet's history. Sometimes rock layers are exposed through human activity, such as drilling or excavation. Other times, rivers carve through the rock. One of the best, and most well-known, examples of a river exposing ancient rocks is Colorado River in Arizona's Grand Canyon. What fewer people know is that the Grand Canyon also has a history of relatively recent (on geologic time scales) volcanism. The evidence--hardened lava--spills down the canyon walls all the way to the river. On June 22, 2003, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of the Grand Canyon, near 36.2 degrees north latitude and 113.2 degrees west longitude. ASTER detects light visible to human eyes as well as 'invisible' infrared light. Because different minerals reflect different portions of the light spectrum, ASTER can see varying mineral compositions of the rocks it observes, as well as detecting vegetation. In this three-dimensional visualization, lava fields appear brownish gray, darker than the layers of limestone, sandstone and other rock in the canyon. Vegetation appears green, and sparsely vegetated areas appear mustard. Water in the Colorado River is blue-purple. Geologists estimate that between 1.8 million and 400,000 years ago, lava flows actually dammed the Colorado River more than a dozen times. Some of the lava dams were as high as 600 meters (about 1,969 feet), forming immense reservoirs. Over time, enough water and sediment built up to push the river flow over the tops of these dams and eventually erode them away. Today, remnants of these lava dams remain throughout the area, along with the much older rock layers they cover. Among the most well known examples of these 'frozen' lava cascades is Lava Falls, which spills down to the

The flow across a street canyon of variable width—Part 2:. Scalar dispersion from a street level line source

NASA Astrophysics Data System (ADS)

Simoëns, Serge; Wallace, James M.

As described in Part 1 [Simoëns et al., 2007. The flow across a street canyon of variable width—Part 1: kinematic description. Atmospheric Environment 41, 9002-9017] measurements have been made of the velocity field around and within the canyon formed by two obstacles placed on the wall of a turbulent boundary layer. Here in Part 2 measurements of the scalar dispersion of smoke released from a two-dimensional slot in the wall perpendicular to the mean flow and located parallel to and midway between these two square obstacles are presented. The Reynolds number of the boundary layer at the slot location without the obstacles in place was Rθ≈980. Statistical properties of the concentration field and the scalar fluxes in the streamwise plane are reported here for canyon openings that have been chosen based on characteristics of the kinematic description. These opening widths, expressed as multiples of the obstacle height, are 1 h, 4 h and 8 h. The mean concentration field revealed that the much of the scalar is trapped on the leeward side of the upstream obstacle before some of it escapes the canyon and is entrained on the roof of the upstream obstacle. It then is spread downstream by the turbulence in the wake of this obstacle. Surprisingly, the root mean square (rms) concentration field reveals that high concentration fluctuations exist in a zone where velocity field turbulence is very low. Measured streamwise scalar fluxes were found to be negative above the obstacles, whereas they are mainly positive between the obstacles. The measured wall normal scalar fluxes have an inverse behavior. Within the canyon, the scalar fluxes are greatest in the region between the large primary vortex, evident in the kinematic field, and the secondary vortex located in the corner of the leeward side of the upstream obstacle. In the flow above the obstacle roofs the wake of the upstream obstacle seems to dominate the scalar transport. Between the obstacles in and above the canyon

Geologic map and upper Paleozoic stratigraphy of the Marble Canyon area, Cottonwood Canyon quadrangle, Death Valley National Park, Inyo County, California

USGS Publications Warehouse

Stone, Paul; Stevens, Calvin H.; Belasky, Paul; Montañez, Isabel P.; Martin, Lauren G.; Wardlaw, Bruce R.; Sandberg, Charles A.; Wan, Elmira; Olson, Holly A.; Priest, Susan S.

2014-01-01

This geologic map and pamphlet focus on the stratigraphy, depositional history, and paleogeographic significance of upper Paleozoic rocks exposed in the Marble Canyon area in Death Valley National Park, California. Bedrock exposed in this area is composed of Mississippian to lower Permian (Cisuralian) marine sedimentary rocks and the Jurassic Hunter Mountain Quartz Monzonite. These units are overlain by Tertiary and Quaternary nonmarine sedimentary deposits that include a previously unrecognized tuff to which we tentatively assign an age of late middle Miocene (~12 Ma) based on tephrochronologic analysis, in addition to the previously recognized Pliocene tuff of Mesquite Spring. Mississippian and Pennsylvanian rocks in the Marble Canyon area represent deposition on the western continental shelf of North America. Mississippian limestone units in the area (Tin Mountain, Stone Canyon, and Santa Rosa Hills Limestones) accumulated on the outer part of a broad carbonate platform that extended southwest across Nevada into east-central California. Carbonate sedimentation was interrupted by a major eustatic sea-level fall that has been interpreted to record the onset of late Paleozoic glaciation in southern Gondwana. Following a brief period of Late Mississippian clastic sedimentation (Indian Springs Formation), a rise in eustatic sea level led to establishment of a new carbonate platform that covered most of the area previously occupied by the Mississippian platform. The Pennsylvanian Bird Spring Formation at Marble Canyon makes up the outer platform component of ten third-order (1 to 5 m.y. duration) stratigraphic sequences recently defined for the regional platform succession. The regional paleogeography was fundamentally changed by major tectonic activity along the continental margin beginning in middle early Permian time. As a result, the Pennsylvanian carbonate shelf at Marble Canyon subsided and was disconformably overlain by lower Permian units (Osborne Canyon and

Versatile common instrumentation for optical detection of pH and dissolved oxygen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sardesai, Neha; Rao, Govind; Kostov, Yordan, E-mail: kostov@umbc.edu

2015-07-15

The recent trend toward use of disposable and miniature bioreactors requires the use of appropriate sensors. pH and dissolved oxygen (DO) are often measured using optical chemical sensors due to their small form factor and convenience in use. These sensors are often interrogated using a specialized opto-electronic transducer that is designed around the optical sensor. In this contribution, we are presenting a new class of opto-electronic transducers that are usable with several different chemical sensors without the need to switch the optics or hardware when changing the type of the chemical sensor. This allows flexibility closer to the lab-grade devicesmore » while the size is closer to a dedicated sensor. This versatile instrumentation is capable of seamlessly switching between the pH and DO measurement modes and is capable of auto recognition of the sensor type. The principle of ratiometric fluorescence is used for pH measurements, and that of fluorescence lifetime for DO measurements. An approach to obtain identical calibrations between several devices is also presented. The described hardware constitutes common instrumentation for measuring either pH or DO and has been tested in actual bioprocesses. It has been found adequate for continuous bioprocess monitoring.« less

Pancreatic enzymes prepared in bicarbonate solution for administration through enteral feeding tubes.

PubMed

Boullata, Angela M; Boullata, Joseph I

2015-07-15

The dissolution and physicochemical effects of preparing delayed-release pancrelipase in a sodium bicarbonate solution before administration via an enteral feeding tube were studied. Several doses of four delayed-release pancrelipase products (Creon, Pancreaze, Ultresa, Zenpep) were studied. The intact contents of pancrelipase capsules was added to 20 mL of 8.4% sodium bicarbonate solution to dissolve the enteric coating and liberate the enzymes into solution. In addition to visual observation, the pH, relative particle count, and osmolality of each admixture were assessed immediately and 5, 10, 20, and 30 minutes after admixture preparation. The only dose of Creon that was completely dissolved at 30 minutes was the 24,000 lipase unit dose. None of the doses of Pancreaze and only the lowest dose (23,000 lipase units) of Ultresa were completely dissolved at 30 minutes. However, Zenpep doses of 20,000 and 40,000 lipase units were completely dissolved 30 minutes after preparation. Higher doses of each pancrelipase product did not completely dissolve. The baseline pH of the solvent decreased slightly at the first few time points after pancrelipase was added. The relative particle count increased over time and with increasing doses. The osmolality of the mixtures varied by pancrelipase product. The dissolution of enteric coated granules in sodium bicarbonate varied with the pancrelipase product and dose. Zenpep 40,000 lipase units was found to most efficiently dissolve in sodium bicarbonate, possibly due to the consistent size of the product's granules and visibly thinner and uniform enteric coating. Copyright © 2015 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

Method to Estimate the Dissolved Air Content in Hydraulic Fluid

NASA Technical Reports Server (NTRS)

Hauser, Daniel M.

2011-01-01

In order to verify the air content in hydraulic fluid, an instrument was needed to measure the dissolved air content before the fluid was loaded into the system. The instrument also needed to measure the dissolved air content in situ and in real time during the de-aeration process. The current methods used to measure the dissolved air content require the fluid to be drawn from the hydraulic system, and additional offline laboratory processing time is involved. During laboratory processing, there is a potential for contamination to occur, especially when subsaturated fluid is to be analyzed. A new method measures the amount of dissolved air in hydraulic fluid through the use of a dissolved oxygen meter. The device measures the dissolved air content through an in situ, real-time process that requires no additional offline laboratory processing time. The method utilizes an instrument that measures the partial pressure of oxygen in the hydraulic fluid. By using a standardized calculation procedure that relates the oxygen partial pressure to the volume of dissolved air in solution, the dissolved air content is estimated. The technique employs luminescent quenching technology to determine the partial pressure of oxygen in the hydraulic fluid. An estimated Henry s law coefficient for oxygen and nitrogen in hydraulic fluid is calculated using a standard method to estimate the solubility of gases in lubricants. The amount of dissolved oxygen in the hydraulic fluid is estimated using the Henry s solubility coefficient and the measured partial pressure of oxygen in solution. The amount of dissolved nitrogen that is in solution is estimated by assuming that the ratio of dissolved nitrogen to dissolved oxygen is equal to the ratio of the gas solubility of nitrogen to oxygen at atmospheric pressure and temperature. The technique was performed at atmospheric pressure and room temperature. The technique could be theoretically carried out at higher pressures and elevated

The influence of the San Gregorio fault on the morphology of Monterey Canyon

USGS Publications Warehouse

McHugh, C.M.G.; Ryan, William B. F.; Eittreim, S.; Donald, Reed

1998-01-01

A side-scan sonar survey was conducted of Monterey Canyon and the San Gregorio fault zone, off shore of Monterey Bay. The acoustic character and morphology of the sonar images, enhanced by SeaBeam bathymetry, show the path of the San Gregorio fault zone across the shelf, upper slope, and Monterey Canyon. High backscatter linear features a few kilometers long and 100 to 200 m wide delineate the sea-floor expression of the fault zone on the shelf. Previous studies have shown that brachiopod pavements and carbonate crusts are the source of the lineations backscatter. In Monterey Canyon, the fault zone occurs where the path of the canyon makes a sharp bend from WNW to SSW (1800 m). Here, the fault is marked by NW-SE-trending, high reflectivity lineations that cross the canyon floor between 1850 m and 1900 m. The lineations can be traced to ridges on the northwestern canyon wall where they have ~ 15 m of relief. Above the low-relief ridges, bowl-shaped features have been excavated on the canyon wall contributing to the widening of the canyon. We suggest that shear along the San Gregorio fault has led to the formation of the low-relief ridges near the canyon wall and that carbonate crusts, as along the shelf, may be the source of the high backscatter features on the canyon floor. The path of the fault zone across the upper slope is marked by elongated tributary canyons with high backscatter floors and 'U'-shaped cross-sectional profiles. Linear features and stepped scarps suggestive of recent crustal movement and mass-wasting, occur on the walls and floors of these canyons. Three magnitude-4 earthquakes have occurred within the last 30 years in the vicinity of the canyons that may have contributed to the observed features. As shown by others, motion along the fault zone has juxtaposed diverse lithologies that outcrop on the canyon walls. Gully morphology and the canyon's drainage patterns have been influenced by the substrate into which the gullies have formed.

Is Canyon Width a Diagnostic Indicator of the Discharge of Megafloods on Earth and Mars?

NASA Astrophysics Data System (ADS)

Lapotre, M. G.; Lamb, M. P.

2013-12-01

On Earth, large floods have carved steep-walled and amphitheater-headed canyons from the Pleistocene (e.g. Box Canyon, ID) through the Holocene (e.g. Asbyrgi Canyon, Iceland), to historic times (e.g. Canyon Lake Gorge, TX). The geologic record on Mars suggests that similar floods have carved canyons by waterfall retreat about 3.5 billion years ago, when the red planet was wetter and possibly warmer. We currently lack robust paleo-hydraulic tools to reconstruct the discharge of ancient floods, especially on Mars where sediment sizes are obscured from observation. To address this issue, we hypothesize that the width of canyon escarpment is controlled by the hydraulics of the canyon-carving flood due to focusing of the flood into the canyon head. We compiled field data from multiple canyons and floods on Earth and Mars and show that there is a correlation between estimated flood discharge and canyon headwall width. To explore what sets this relationship, we identified five important parameters using dimensional analysis: the Froude number, the ratio of backwater length to canyon length, the ratio of backwater length to flood width, the ratio of canyon width to flood width, and the topographic slope upstream of the canyon. We used the hydraulic numerical modeling suite ANUGA to simulate overland flow over different canyon geometries and flood parameters to systematically explore the relative bed shear stresses along the canyon rim as a metric for flow focusing. Results show that canyons that exceed a certain length, scaling with the hydraulic backwater length, have shear stresses at their heads that are significantly higher than near the canyon mouth. Shear stresses along the rim of the canyon sidewalls are limited, in comparison to stresses along the canyon head, when the flood width is of the order of the backwater length. Flow focusing only occurs for subcritical flow. Together, these results suggest that canyons may only grow from a perturbation that is large

DIissolution of low enriched uranium from the experimental breeder reactor-II fuel stored at the Idaho National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniel, G.; Rudisill, T.; Almond, P.

The Idaho National Laboratory (INL) is actively engaged in the development of electrochemical processing technology for the treatment of fast reactor fuels using irradiated fuel from the Experimental Breeder Reactor-II (EBR-II) as the primary test material. The research and development (R&D) activities generate a low enriched uranium (LEU) metal product from the electrorefining of the EBR-II fuel and the subsequent consolidation and removal of chloride salts by the cathode processor. The LEU metal ingots from past R&D activities are currently stored at INL awaiting disposition. One potential disposition pathway is the shipment of the ingots to the Savannah River Sitemore » (SRS) for dissolution in H-Canyon. Carbon steel cans containing the LEU metal would be loaded into reusable charging bundles in the H-Canyon Crane Maintenance Area and charged to the 6.4D or 6.1D dissolver. The LEU dissolution would be accomplished as the final charge in a dissolver batch (following the dissolution of multiple charges of spent nuclear fuel (SNF)). The solution would then be purified and the 235U enrichment downblended to allow use of the U in commercial reactor fuel. To support this potential disposition path, the Savannah River National Laboratory (SRNL) developed a dissolution flowsheet for the LEU using samples of the material received from INL.« less

Optimizing Street Canyon Orientation for Rajarhat Newtown, Kolkata, India

NASA Astrophysics Data System (ADS)

De, Bhaskar; Mukherjee, Mahua

2017-12-01

Air temperature in urban street canyons is increased due to the morphed urban geometry, increased surface area, decreased long wave radiation and evapo-transpiration, different thermo-physical properties of surface materials and anthropogenic heat which results in thermal discomfort. Outdoor thermal stress can be mitigated substantially by properly orienting the canyons. It is crucial for the urban planners and designers to orient street canyons optimally considering variable local climatic context. It is important especially for cities in warm humid climatic context as these cities receive higher insolation with higher relative humidity and low level macro wind flow. This paper examines influence of canyon orientation on outdoor thermal comfort and proposes the optimum canyon orientation for the Rajarhat Newtown, Kolkata - a city in warm humid climate zone. Different scenarios are generated with different orientations. Change in air temperature, wind speed, Mean Radiant Temperature (MRT) and Physiological Equivalent Temperature (PET) of different scenarios are compared to find out the optimum orientation by parametric simulation in ENVI_met. Analysing the simulation results it is observed that orientation angle between 30°-60° to north performs the best for the study area of the Rajarhat Newtown. The findings of this research will be helpful for the planners to orient the street canyons optimally for future development and extension of the Rajarhat Newtown, Kolkata.

Compositions of supersaturated solutions for enhanced growth of {alpha}-NiSO{sub 4} . 6H{sub 2}O, Me{sub 2}Ni(SO{sub 4}){sub 2} . 6H{sub 2}O, MeH{sub 2}PO{sub 4} [Me = Li, Na, K, Rb, Cs, NH{sub 4}], and K(H{sub x}D{sub 1-x}){sub 2}PO{sub 4} single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soboleva, L. V., E-mail: afkonst@ns.crys.ras.ru

2008-05-15

The possibility of determining the optimal compositions and temperatures of supersaturated solutions for enhanced growth of single crystals of congruently and incongruently dissolving solid phases from the solubility diagrams of ternary systems is shown, and this approach is justified. The NiSO{sub 4}-H{sub 2}SO{sub 4}-H{sub 2}O, Me{sub 2}SO{sub 4}-NiSO{sub 4}-H{sub 2}O, and Me{sub 2}O-P{sub 2}O{sub 5}-H{sub 2}O(D{sub 2}O) systems have been used to determine the optimal compositions and temperatures of supersaturated solutions for growth of {alpha}-NiSO{sub 4} . 6H{sub 2}O, Me{sub 2}Ni(SO{sub 4}){sub 2} . 6H{sub 2}O, MeH{sub 2}PO{sub 4} [Me = Li, Na, K, Rb, Cs, NH{sub 4}], and Kmore » (H{sub x} D{sub 1-x}){sub 2}PO{sub 4} (D is deuterium) single crystals.« less

Groundwater flow and its effect on salt dissolution in Gypsum Canyon watershed, Paradox Basin, southeast Utah, USA

NASA Astrophysics Data System (ADS)

Reitman, Nadine G.; Ge, Shemin; Mueller, Karl

2014-09-01

Groundwater flow is an important control on subsurface evaporite (salt) dissolution. Salt dissolution can drive faulting and associated subsidence on the land surface and increase salinity in groundwater. This study aims to understand the groundwater flow system of Gypsum Canyon watershed in the Paradox Basin, Utah, USA, and whether or not groundwater-driven dissolution affects surface deformation. The work characterizes the groundwater flow and solute transport systems of the watershed using a three-dimensional (3D) finite element flow and transport model, SUTRA. Spring samples were analyzed for stable isotopes of water and total dissolved solids. Spring water and hydraulic conductivity data provide constraints for model parameters. Model results indicate that regional groundwater flow is to the northwest towards the Colorado River, and shallow flow systems are influenced by topography. The low permeability obtained from laboratory tests is inconsistent with field observed discharges, supporting the notion that fracture permeability plays a significant role in controlling groundwater flow. Model output implies that groundwater-driven dissolution is small on average, and cannot account for volume changes in the evaporite deposits that could cause surface deformation, but it is speculated that dissolution may be highly localized and/or weaken evaporite deposits, and could lead to surface deformation over time.

Geologic Map of the Upper Parashant Canyon and Vicinity, Mohave County, Northwestern Arizona

USGS Publications Warehouse

Billingsley, George H.; Harr, Michelle L.; Wellmeyer, Jessica L.

2000-01-01

Introduction The geologic map of the upper Parashant Canyon area covers part of the Colorado Plateau and several large tributary canyons that make up the western part of Arizona's Grand Canyon. The map is part of a cooperative U.S. Geological Survey and National Park Service project to provide geologic information for areas within the newly established Grand Canyon/Parashant Canyon National Monument. Most of the Grand Canyon and parts of the adjacent plateaus have been geologically mapped; this map fills in one of the remaining areas where uniform quality geologic mapping was needed. The geologic information presented may be useful in future related studies as to land use management, range management, and flood control programs for federal and state agencies, and private concerns. The map area is in a remote region of the Arizona Strip, northwestern Arizona about 88 km south of the nearest settlement of St. George, Utah. Elevations range from about 1,097 m (3,600 ft) in Parashant Canyon (south edge of map area) to 2,145 m (7,037 ft) near the east-central edge of the map area. Primary vehicle access is by dirt road locally known as the Mount Trumbull road; unimproved dirt roads and jeep trails traverse various parts of the map area. Travel on the Mount Trumbull road is possible with 2-wheel-drive vehicles except during wet conditions. Extra fuel, two spare tires and extra food and water are highly recommended when traveling in this remote area. The map area includes about 26 sections of land belonging to the State of Arizona, about 40 sections of private land, and a small strip of the Lake Mead National Recreation Area (southeast edge of the map area). The private land is mainly clustered around the abandoned settlement of Mt. Trumbull, locally known as Bundyville, and a few sections are scattered in the upper Whitmore Canyon area just south of Bundyville. Lower elevations within the canyons support a sparse growth of sagebrush, cactus, grass, creosote bush, and a

Canyon transfer neutron absorber to fissile material ratio analysis. Revision 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clemmons, J.S.

1994-03-04

Waste tank fissile material and non-fissile material estimates are used to evaluate criticality safety for the existing sludge inventory and batches of sludge sent to Extended Sludge Processing (ESP). This report documents the weight ratios of several non-fissile waste constituents to fissile waste constituents from canyon reprocessing waste streams. Weight ratios of Fe, Mn, Al, Mi, and U-238 to fissile material are calculated from monthly loss estimates from the F and H Canyon Low Heat Waste (LHW) and High Heat Waste (HHW) streams. The monthly weight ratios for Fe, Mn and U-238 are then compared to calculated minimum safe weightmore » ratios. Documented minimum safe weight ratios for Al and Ni to fissile material are currently not available. Total mass data for the subject sludge constituents is provided along with scatter plots of the monthly weight ratios for each waste stream.« less

Historical and New Perspective of Moissanite in the Canyon Diablo Meteorite

NASA Astrophysics Data System (ADS)

Leung, I. S.; Winston, R.

2004-12-01

Silicon carbide (SiC) was reportedly found in the residue of a 50-kg sample of the Canyon Diablo meteorite dissolved in acid by Henri Moissan, and, in his honor, George F. Kunz coined the mineral name moissanite in 1904. Scholars of the same meteorite, unable to find SiC, believed that Moissan's sample might have been contaminated by synthetic SiC used in tools and abrasives. Thus, an intriguing mineralogical controversy ensued to this day. Recently, occurrence of SiC in carbonaceous chondrites has been confirmed. We present in this paper our finding of three varieties of SiC crystals in the Canyon Diablo meteorite. We found 5 crystals of SiC (size 70-150 microns) in a black nodule (1 cm in size), composed mostly of disordered graphite and diamond/lonsdaleite. The crystals are pale blue, but some have dark overgrowths of uneven thickness, and black spotty or feathery inclusions. Their forms are rounded and resorbed. Our second specimen is oxidized and friable, bearing a 2-cm nodule showing sandy and black magnetic layers. We found 3 apple-green crystals, up to 200 microns in size. Scattered over two of the sandy layers are many minute emerald-green SiC crystals. Carbon in these crystals might have a terrestrial origin. As Moissan's crystals are no longer available for re-examination, a study of large carbon nodules housed in museums might at least lend credence that meteoritic SiC crystals could be as large as ones reported by Moissan.

Giant submarine canyons: Is size any clue to their importance in the rock record?

USGS Publications Warehouse

Normark, William R.; Carlson, Paul R.

2003-01-01

Submarine canyons are the most important conduits for funneling sediment from continents to oceans. Submarine canyons, however, are zones of sediment bypassing, and little sediment accumulates in the canyon until it ceases to be an active conduit. To understand the potential importance in the rock record of any given submarine canyon, it is necessary to understand sediment-transport processes in, as well as knowledge of, deep-sea turbidite and related deposits that moved through the canyons. There is no straightforward correlation between the final volume of the sedimentary deposits and size of the associated submarine canyons. Comparison of selected modern submarine canyons together with their deposits emphasizes the wide range of scale differences between canyons and their impact on the rock record.Three of the largest submarine canyons in the world are incised into the Beringian (North American) margin of the Bering Sea. Zhemchug Canyon has the largest cross-section at the shelf break and greatest volume of incision of slope and shelf. The Bering Canyon, which is farther south in the Bering Sea, is first in length and total area. In contrast, the largest submarine fans-e.g., Bengal, Indus, and Amazon-have substantially smaller, delta-front submarine canyons that feed them; their submarine drainage areas are one-third to less than one-tenth the area of Bering Canyon. some very large deep-sea channels and tubidite deposits are not even associated with a significant submarine canyon; examples include Horizon Channel in the northeast Pacific and Laurentian Fan Valley in the North Atlantic. Available data suggest that the size of turbidity currents (as determined by volume of sediment transported to the basins) is also not a reliable indicator of submarine canyon size.

Large eddy simulation of fire-induced buoyancy driven plume dispersion in an urban street canyon under perpendicular wind flow.

PubMed

Hu, L H; Huo, R; Yang, D

2009-07-15

The dispersion of fire-induced buoyancy driven plume in and above an idealized street canyon of 18 m (width) x 18 m (height) x 40 m (length) with a wind flow perpendicular to its axis was investigated by Fire Dynamics Simulator (FDS), Large Eddy Simulation (LES). Former studies, such as that by Oka [T.R. Oke, Street design and urban canopy layer climate, Energy Build. 11 (1988) 103-113], Gayev and Savory [Y.A. Gayev, E. Savory, Influence of street obstructions on flow processes within street canyons. J. Wind Eng. Ind. Aerodyn. 82 (1999) 89-103], Xie et al. [S. Xie, Y. Zhang, L. Qi, X. Tang, Spatial distribution of traffic-related pollutant concentrations in street canyons. Atmos. Environ. 37 (2003) 3213-3224], Baker et al. [J. Baker, H. L. Walker, X. M. Cai, A study of the dispersion and transport of reactive pollutants in and above street canyons--a large eddy simulation, Atmos. Environ. 38 (2004) 6883-6892] and Baik et al. [J.-J. Baik, Y.-S. Kang, J.-J. Kim, Modeling reactive pollutant dispersion in an urban street canyon, Atmos. Environ. 41 (2007) 934-949], focus on the flow pattern and pollutant dispersion in the street canyon with no buoyancy effect. Results showed that with the increase of the wind flow velocity, the dispersion pattern of a buoyant plume fell into four regimes. When the wind flow velocity increased up to a certain critical level, the buoyancy driven upward rising plume was re-entrained back into the street canyon. This is a dangerous situation as the harmful fire smoke will accumulate to pollute the environment and thus threaten the safety of the people in the street canyon. This critical re-entrainment wind velocity, as an important parameter to be concerned, was further revealed to increase asymptotically with the heat/buoyancy release rate of the fire.

Currents in monterey submarine canyon

USGS Publications Warehouse

Xu, J. P.; Noble, M.A.

2009-01-01

Flow fields of mean, subtidal, and tidal frequencies between 250 and 3300 m water depths in Monterey Submarine Canyon are examined using current measurements obtained in three yearlong field experiments. Spatial variations in flow fields are mainly controlled by the topography (shape and width) of the canyon. The mean currents flow upcanyon in the offshore reaches (>1000 m) and downcanyon in the shallow reaches (100-m amplitude isotherm oscillations and associated high-speed rectilinear currents. The 15-day spring-neap cycle and a ???3-day??? band are the two prominent frequencies in subtidal flow field. Neither of them seems directly correlated with the spring-neap cycle of the sea level.

Canyon formation constraints on the discharge of catastrophic outburst floods of Earth and Mars

NASA Astrophysics Data System (ADS)

Lapotre, Mathieu G. A.; Lamb, Michael P.; Williams, Rebecca M. E.

2016-07-01

Catastrophic outburst floods carved amphitheater-headed canyons on Earth and Mars, and the steep headwalls of these canyons suggest that some formed by upstream headwall propagation through waterfall erosion processes. Because topography evolves in concert with water flow during canyon erosion, we suggest that bedrock canyon morphology preserves hydraulic information about canyon-forming floods. In particular, we propose that for a canyon to form with a roughly uniform width by upstream headwall retreat, erosion must occur around the canyon head, but not along the sidewalls, such that canyon width is related to flood discharge. We develop a new theory for bedrock canyon formation by megafloods based on flow convergence of large outburst floods toward a horseshoe-shaped waterfall. The model is developed for waterfall erosion by rock toppling, a candidate erosion mechanism in well fractured rock, like columnar basalt. We apply the model to 14 terrestrial (Channeled Scablands, Washington; Snake River Plain, Idaho; and Ásbyrgi canyon, Iceland) and nine Martian (near Ares Vallis and Echus Chasma) bedrock canyons and show that predicted flood discharges are nearly 3 orders of magnitude less than previously estimated, and predicted flood durations are longer than previously estimated, from less than a day to a few months. Results also show a positive correlation between flood discharge per unit width and canyon width, which supports our hypothesis that canyon width is set in part by flood discharge. Despite lower discharges than previously estimated, the flood volumes remain large enough for individual outburst floods to have perturbed the global hydrology of Mars.

Approximate solutions for diffusive fracture-matrix transfer: Application to storage of dissolved CO 2 in fractured rocks

DOE PAGES

Zhou, Quanlin; Oldenburg, Curtis M.; Spangler, Lee H.; ...

2017-01-05

Analytical solutions with infinite exponential series are available to calculate the rate of diffusive transfer between low-permeability blocks and high-permeability zones in the subsurface. Truncation of these series is often employed by neglecting the early-time regime. Here in this paper, we present unified-form approximate solutions in which the early-time and the late-time solutions are continuous at a switchover time. The early-time solutions are based on three-term polynomial functions in terms of square root of dimensionless time, with the first coefficient dependent only on the dimensionless area-to-volume ratio. The last two coefficients are either determined analytically for isotropic blocks (e.g., spheresmore » and slabs) or obtained by fitting the exact solutions, and they solely depend on the aspect ratios for rectangular columns and parallelepipeds. For the late-time solutions, only the leading exponential term is needed for isotropic blocks, while a few additional exponential terms are needed for highly anisotropic rectangular blocks. The optimal switchover time is between 0.157 and 0.229, with highest relative approximation error less than 0.2%. The solutions are used to demonstrate the storage of dissolved CO 2 in fractured reservoirs with low-permeability matrix blocks of single and multiple shapes and sizes. These approximate solutions are building blocks for development of analytical and numerical tools for hydraulic, solute, and thermal diffusion processes in low-permeability matrix blocks.« less

Oak Canyon Action Memo

EPA Pesticide Factsheets

This memorandum requests approval for a time-critical removal action at the 27 residential properties that compose the Oak Canyon Site located in the Village of Paguate, Pueblo of Laguna, near Cibola County, New Mexico.

California State Waters Map Series--Hueneme Canyon and vicinity, California

USGS Publications Warehouse

Johnson, Samuel Y.; Dartnell, Peter; Cochrane, Guy R.; Golden, Nadine E.; Phillips, Eleyne L.; Ritchie, Andrew C.; Kvitek, Rikk G.; Greene, H. Gary; Krigsman, Lisa M.; Endris, Charles A.; Clahan, Kevin B.; Sliter, Ray W.; Wong, Florence L.; Yoklavich, Mary M.; Normark, William R.

2012-01-01

In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California's State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonar data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow (to about 100 m) subsurface geology. The Hueneme Canyon and vicinity map area lies within the eastern Santa Barbara Channel region of the Southern California Bight. The area is part of the Western Transverse Ranges geologic province, which is north of the California Continental Borderland. Significant clockwise rotation - at least 90° - since the early Miocene has been proposed for the Western Transverse Ranges, and the region is presently undergoing north-south shortening. This geologically complex region forms a major biogeographic transition zone, separating the cold-temperate Oregonian province north of Point Conception from the warm-temperate California province to the south. The map area, which is offshore of the Oxnard plain and west of and along the trend of the south flank of the Santa Monica Mountains, lies at the east end of the Santa Barbara littoral cell, characterized by west-to-east littoral transport of sediment derived mainly from coastal watersheds. The Hueneme Canyon and vicinity map area in California's State Waters is characterized by two major physiographic features: (1) the nearshore continental shelf, and (2) the Hueneme and Mugu Submarine Canyon system, which, in the map area, includes Hueneme Canyon and parts

California State Waters Map Series—Monterey Canyon and vicinity, California

USGS Publications Warehouse

Dartnell, Peter; Maier, Katherine L.; Erdey, Mercedes D.; Dieter, Bryan E.; Golden, Nadine E.; Johnson, Samuel Y.; Hartwell, Stephen R.; Cochrane, Guy R.; Ritchie, Andrew C.; Finlayson, David P.; Kvitek, Rikk G.; Sliter, Ray W.; Greene, H. Gary; Davenport, Clifton W.; Endris, Charles A.; Krigsman, Lisa M.; Dartnell, Peter; Cochran, Susan A.

2016-06-10

IntroductionIn 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath bathymetry data, acoustic backscatter, seafloor video, seafloor photography, high-resolution seismic-reflection profiles, and bottom-sediment sampling data. The map products display seafloor morphology and character, identify potential marine benthic habitats, and illustrate both the surficial seafloor geology and shallow subsurface geology.The Monterey Canyon and Vicinity map area lies within Monterey Bay in central California. Monterey Bay is one of the largest embayments along the west coast of the United States, spanning 36 km from its northern to southern tips (in Santa Cruz and Monterey, respectively) and 20 km along its central axis. Not only does it contain one of the broadest sections of continental shelf along California’s coast, it also contains Monterey Canyon, one of the largest and deepest submarine canyons in the world. Note that the California’s State Waters limit extends farther offshore between Santa Cruz and Monterey so that it encompasses all of Monterey Bay.The coastal area within the map area is lightly populated. The community of Moss Landing (population, 204) hosts the largest commercial fishing fleet in Monterey Bay in its harbor. The map area also includes parts of the cities of Marina (population, about 20,000) and Castroville (population, about 6,500). Fertile lowlands of the Salinas River and Pajaro River valleys largely occupy the inland part of the map area, and land use is primarily agricultural.The offshore part of the map area lies completely within the Monterey Bay National Marine Sanctuary. The

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Grand Canyon National Park. 7.4 Section 7.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial...

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Grand Canyon National Park. 7.4 Section 7.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial...

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Grand Canyon National Park. 7.4 Section 7.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial...

36 CFR 7.4 - Grand Canyon National Park.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Grand Canyon National Park. 7.4 Section 7.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.4 Grand Canyon National Park. (a) Commercial...

Influence of under pressure dissolved oxygen on trichloroethylene degradation by the H2O2/TiO2 process.

PubMed

Hoseini, Mohammad; Nabizadeh, Ramin; Nazmara, Shahrokh; Safari, Gholam Hossein

2013-12-20

The widespread use of trichloroethylene (TCE) and its frequent release into the environment has caused many environmental and health problems. In this study the degradation of TCE at different micromolar concentrations was investigated in a stainless steel reactor with various concentrations of H2O2 and TiO2 at different oxygen pressures and three different pHs. To examine the synergistic effect of under pressure oxygen on TCE degradation, the concentrations of H2O2 and TiO2 as well as pH were first optimized, and then the experiments were performed under optimal conditions. Gas chromatography with a flame ionization detector (FID) was used to measure TCE concentrations. Results showed that the percentage of TCE degradation without pressurized oxygen was low and it increased with increasing pressure of oxygen at all initial concentrations of TCE. The degradation percentages without oxygen pressure were 48.27%, 51.22%, 58.13% and 64.33% for TCE concentrations of 3000, 1500, 300 and 150 μg/L respectively. At an oxygen pressure of 2.5 atmospheres (atm) the percent degradation of TCE reached 84.85%, 89.14%, 93.13% and 94.99% respectively for the aforementioned TCE concentrations. The results of this study show that the application of dissolved oxygen under pressure increases the efficiency of the H2O2/TiO2 process on the degradation of TCE and can be used along with other oxidants as an effective method for the removal of this compound from aqueous solutions.

Influence of under pressure dissolved oxygen on trichloroethylene degradation by the H2O2/TiO2 process

PubMed Central

2013-01-01

Background The widespread use of trichloroethylene (TCE) and its frequent release into the environment has caused many environmental and health problems. In this study the degradation of TCE at different micromolar concentrations was investigated in a stainless steel reactor with various concentrations of H2O2 and TiO2 at different oxygen pressures and three different pHs. Methods To examine the synergistic effect of under pressure oxygen on TCE degradation, the concentrations of H2O2 and TiO2 as well as pH were first optimized, and then the experiments were performed under optimal conditions. Gas chromatography with a flame ionization detector (FID) was used to measure TCE concentrations. Results Results showed that the percentage of TCE degradation without pressurized oxygen was low and it increased with increasing pressure of oxygen at all initial concentrations of TCE. The degradation percentages without oxygen pressure were 48.27%, 51.22%, 58.13% and 64.33% for TCE concentrations of 3000, 1500, 300 and 150 μg/L respectively. At an oxygen pressure of 2.5 atmospheres (atm) the percent degradation of TCE reached 84.85%, 89.14%, 93.13% and 94.99% respectively for the aforementioned TCE concentrations. Conclusions The results of this study show that the application of dissolved oxygen under pressure increases the efficiency of the H2O2/TiO2 process on the degradation of TCE and can be used along with other oxidants as an effective method for the removal of this compound from aqueous solutions. PMID:24359702

B-Plant Canyon Ventilation Control System Description

DOE Office of Scientific and Technical Information (OSTI.GOV)

MCDANIEL, K.S.

1999-08-31

Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This document describes the CVCS system components which include a Programmable Logic Controller (PLC) coupled with an Operator Interface Unit (OIU) and application software. This document also includes an Alarm Index specifying the setpoints and technical basis for system analog and digital alarms.

Measuring currents in submarine canyons: technological and scientific progress in the past 30 years

USGS Publications Warehouse

Xu, J. P.

2011-01-01

The development and application of acoustic and optical technologies and of accurate positioning systems in the past 30 years have opened new frontiers in the submarine canyon research communities. This paper reviews several key advancements in both technology and science in the field of currents in submarine canyons since the1979 publication of Currents in Submarine Canyons and Other Sea Valleys by Francis Shepard and colleagues. Precise placements of high-resolution, high-frequency instruments have not only allowed researchers to collect new data that are essential for advancing and generalizing theories governing the canyon currents, but have also revealed new natural phenomena that challenge the understandings of the theorists and experimenters in their predictions of submarine canyon flow fields. Baroclinic motions at tidal frequencies, found to be intensified both up canyon and toward the canyon floor, dominate the flow field and control the sediment transport processes in submarine canyons. Turbidity currents are found to frequently occur in active submarine canyons such as Monterey Canyon. These turbidity currents have maximum speeds of nearly 200 cm/s, much smaller than the speeds of turbidity currents in geological time, but still very destructive. In addition to traditional Eulerian measurements, Lagrangian flow data are essential in quantifying water and sediment transport in submarine canyons. A concerted experiment with multiple monitoring stations along the canyon axis and on nearby shelves is required to characterize the storm-trigger mechanism for turbidity currents.

Determination of filter pore size for use in HB line phase II production of plutonium oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shehee, T.; Crowder, M.; Rudisill, T.

2014-08-01

H-Canyon and HB-Line are tasked with the production of plutonium oxide (PuO 2) from a feed of plutonium (Pu) metal. The PuO 2 will provide feed material for the Mixed Oxide (MOX) Fuel Fabrication Facility. After dissolution of the Pu metal in H-Canyon, plans are to transfer the solution to HB-Line for purification by anion exchange. Anion exchange will be followed by plutonium(IV) oxalate precipitation, filtration, and calcination to form PuO 2. The filtrate solutions, remaining after precipitation, contain low levels of Pu ions, oxalate ions, and may include solids. These solutions are transferred to H-Canyon for disposition. To mitigatemore » the criticality concern of Pu solids in a Canyon tank, past processes have used oxalate destruction or have pre-filled the Canyon tank with a neutron poison. The installation of a filter on the process lines from the HB-Line filtrate tanks to H-Canyon Tank 9.6 is proposed to remove plutonium oxalate solids. This report describes SRNL’s efforts to determine the appropriate pore size for the filters needed to perform this function. Information provided in this report aids in developing the control strategies for solids in the process.« less

Red Rock Canyon National Conservation Area Transportation Feasibility Study

DOT National Transportation Integrated Search

2012-07-31

Red Rock Canyon National Conservation Area is a popular Bureau of Land Management natural area located near Las Vegas, Nevada. Red Rock Canyon experiences heavy congestion on its Scenic Drive and associated parking areas, due to high volumes of visit...

Dissolution of pulp tissue by aqueous solution of chlorhexidine digluconate and chlorhexidine digluconate gel.

PubMed

Okino, L A; Siqueira, E L; Santos, M; Bombana, A C; Figueiredo, J A P

2004-01-01

To evaluate the activity of various root canal irrigants on bovine pulp tissue. The irrigants tested were: 0.5, 1.0 and 2.5% sodium hypochlorite; 2% aqueous solution of chlorhexidine digluconate; 2% chlorhexidine digluconate gel (Natrosol); and distilled water as control. Bovine pulp fragments were weighed and placed in contact with 20 mL of each tested substance in a centrifuge at 150 r.p.m. until total dissolution. Dissolution speed was calculated by dividing pulp weight by dissolution time. Statistical analysis was performed using the Kruskal-Wallis test. Distilled water and both solutions of chlorhexidine did not dissolve the pulp tissue within 6 h. Mean dissolution speeds for 0.5, 1.0 and 2.5% sodium hypochlorite solutions were 0.31, 0.43 and 0.55 mg min(-1), respectively. The solvent ability of chlorhexidine solutions was similar to that of distilled water. The results for sodium hypochlorite solutions, chlorhexidine solutions and distilled water were statistically different (P>0.01). Both chlorhexidine preparations and distilled water were not able to dissolve pulp tissue. All sodium hypochlorite solutions were efficient in dissolving pulp tissue; the dissolution speed varied with the concentration of the solution.

A method of calculating quartz solubilities in aqueous sodium chloride solutions

USGS Publications Warehouse

Fournier, R.O.

1983-01-01

The aqueous silica species that form when quartz dissolves in water or saline solutions are hydrated. Therefore, the amount of quartz that will dissolve at a given temperature is influenced by the prevailing activity of water. Using a standard state in which there are 1,000 g of water (55.51 moles) per 1,000 cm3 of solution allows activity of water in a NaCl solution at high temperature to be closely approximated by the effective density of water, pe, in that solution, i.e. the product of the density of the NaCl solution times the weight fraction of water in the solution, corrected for the amount of water strongly bound to aqueous silica and Na+ as water of hydration. Generally, the hydration of water correction is negligible. The solubility of quartz in pure water is well known over a large temperature-pressure range. An empirical formula expresses that solubility in terms of temperature and density of water and thus takes care of activity coefficient and pressure-effect terms. Solubilities of quartz in NaCl solutions can be calculated by using that equation and substituting pe, for the density of pure water. Calculated and experimentally determined quartz solubilities in NaCl solutions show excellent agreement when the experiments were carried out in non-reactive platinum, gold, or gold plus titanium containers. Reactive metal containers generally yield dissolved silica concentrations higher than calculated, probably because of the formation of metal chlorides plus NaOH and H2. In the absence of NaOH there appears to be no detectable silica complexing in NaCl solutions, and the variation in quartz solubility with NaCl concentration at constant temperature can be accounted for entirely by variations in the activity of water. The average hydration number per molecule of dissolved SiO2 in liquid water and NaCl solutions decreases from about 2.4 at 200??C to about 2.1 at 350??C. This suggests that H4SiO4 may be the dominant aqueous silica species at 350??C, but other

Environmental analysis of Lower Pueblo/Lower Los Alamos Canyon, Los Alamos, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.

1994-12-01

The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, Pueblo Canyon, and Los Alamos Canyon found residual contamination at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons all the way to the Rio Grande. The largest reservoir of residual radioactivity is in lower Pueblo Canyon, which is on DOE property. However, residual radioactivity does not exceed proposed cleanup criteria in either lower Pueblo or lower Los Alamos Canyons. The three alternatives proposed are (1) to take no action, (2) to construct a sediment trap in lowermore » Pueblo Canyon to prevent further transport of residual radioactivity onto San Ildefonso Indian Pueblo land, and (3) to clean the residual radioactivity from the canyon system. Alternative 2, to cleanup the canyon system, is rejected as a viable alternative. Thousands of truckloads of sediment would have to be removed and disposed of, and this effort is unwarranted by the low levels of contamination present. Residual radioactivity levels, under either present conditions or projected future conditions, will not result in significant radiation doses to persons exposed. Modeling efforts show that future transport activity will not result in any residual radioactivity concentrations higher than those already existing. Thus, although construction of a sediment trap in lower Pueblo Canyon is a viable alternative, this effort also is unwarranted, and the no-action alternative is the preferred alternative.« less

Volunteer revegetation of waste rock surfaces at the Bingham Canyon Mine, Utah.

PubMed

Borden, Richard K; Black, Rick

2005-01-01

Voluntary recolonization of sulfide-bearing waste rock dumps by native vegetation is inhibited by the harsh chemical and physical conditions. The success of volunteer vegetation on the waste rock surfaces at the Bingham Canyon (Utah) porphyry copper deposit is most strongly dependent on the soil pH and salinity, and to a lesser extent on physical characteristics such as compaction and distance from seed source. Vegetation cover and richness both decline below a paste pH of about 6 and above a paste conductivity of about 0.7 dS/m (for a 1:1 soil to water mixture). No significant vegetation establishment occurs below a soil pH of about 4.5. Young sulfide-bearing waste rock surfaces at Bingham Canyon have high salinity, but as reactive pyrite is depleted and salts are flushed from the soil, the salinity eventually declines, allowing volunteer native vegetation to become established on surfaces with a circumneutral pH. Under natural conditions, the pH of older acidic weathered surfaces will recover very slowly, but it can be rapidly raised by adding relatively small amounts of limestone because there are few intact reactive sulfides. For uncompacted waste rock surfaces with favorable chemical conditions, less than 90% gravel content, and that are located near a native seed source, the arithmetic mean volunteer vegetation cover was 56 +/- 24% and the mean species richness was 17 +/- 5. These data indicate that with adequate surface preparation and limestone addition, direct planting of older, acidic, but low salinity waste rock surfaces can greatly accelerate natural revegetation.

Erosion patterns on dissolving blocks

NASA Astrophysics Data System (ADS)

Courrech du Pont, Sylvain; Cohen, Caroline; Derr, Julien; Berhanu, Michael

2016-04-01

Patterns in nature are shaped under water flows and wind action, and the understanding of their morphodynamics goes through the identification of the physical mechanisms at play. When a dissoluble body is exposed to a water flow, typical patterns with scallop-like shapes may appear [1,2]. These shapes are observed on the walls of underground rivers or icebergs. We experimentally study the erosion of dissolving bodies made of salt, caramel or ice into water solutions without external flow. The dissolving mixture, which is created at the solid/liquid interface, undergoes a buoyancy-driven instability comparable to a Rayleigh-Bénard instability so that the dissolving front destabilizes into filaments. This mechanism yields to spatial variations of solute concentration and to differential dissolution of the dissolving block. We first observe longitudinal stripes with a well defined wavelength, which evolve towards chevrons and scallops that interact and move again the dissolving current. Thanks to a careful analysis of the competing physical mechanisms, we propose scaling laws, which account for the characteristic lengths and times of the early regime in experiments. The long-term evolution of patterns is understood qualitatively. A close related mechanism has been proposed to explain structures observed on the basal boundary of ice cover on brakish lakes [3] and we suggest that our experiments are analogous and explain the scallop-like patterns on iceberg walls. [1] P. Meakin and B. Jamtveit, Geological pattern formation by growth and dissolution in aqueous systems, Proc. R. Soc. A 466, 659-694 (2010). [2] P.N. Blumberg and R.L. Curl, Experimental and theoretical studies of dissolution roughness, J. Fluid Mech. 65, 735-751 (1974). [3] L. Solari and G. Parker, Morphodynamic modelling of the basal boundary of ice cover on brakish lakes, J.G.R. 118, 1432-1442 (2013).

Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

NASA Astrophysics Data System (ADS)

Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

2015-10-01

;Clumped-isotope; thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope ;clumps;). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals. We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect. Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3- and CO32-. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many natural systems. The two

Morphology of Submarine Canyons in the Palomares Margin (East of Alboran Sea, western Mediterranean)

NASA Astrophysics Data System (ADS)

Perez-Hernandez, S.; Comas, M. C.; Escutia, C.

2009-04-01

Morphological analysis on the Palomares Margin has been done using high-resolution swath bathymetry data collected during the MARSIBAL-06 (2006) cruise on board of the R/V BIO Hespérides. Complemented with data from GEBCO 2000 and Ifremer (Medimap Group, 2007) the data-set provides the first complete bathymetric mosaic of the Palomares Margin. The bathymetric mosaic allows to study the physiographic provinces of the Palomares Margin and to conduct, for the first time, a detailed morphological analysis of the two main sediment-transfer conduits: the Gata and the Alias-Almanzora Canyons. The Gata Canyon extends for 64km from the outer shelf to the base of the slope with a general W-E direction. A tributary system of canyons originates at the shelf break and continues on the slope until they merge at 1230m water depth. The walls of the canyons are characterized by repeated slides. Perpendicular profiles to the Canyon pathway reveal gentle transversal "V" asymmetrical shapes with a marked axial incision on the canyon floor (highs between 65 to 103m in the southern flank, and between 30-90m in the northern flank ). The transition from an erosional canyon to a deposition channel is located at 2100m water depth, and is characterized by trapezoidal shapes on transversal profiles accompanied of lower relieves (40-65m). At the mouth of the canyon-channel system no sedimentary lobes are observed. The Alias-Almanzora canyon (73km long and preferential direction W-E) is located North of the Gata Canyon and extends from the continental shelf to the base of the slope. A tributary system to the Alias- Almanzora canyon-head locates less than 150m from the coast, facing a fluvial drainage system onland. Proximal tributary canyons and gullies feed the main canyon until it merges in the continental slope at 1516m water depth. The tributary system exhibits a marked "V" shape in transverse profiles and marked axial incisions. Down slope, transversal profiles have trapezoidal shapes

Surface micro-dissolve method of imparting self-cleaning property to cotton fabrics in NaOH/urea aqueous solution

NASA Astrophysics Data System (ADS)

Fan, Tao; Hu, Ruimin; Zhao, Zhenyun; Liu, Yiping; Lu, Ming

2017-04-01

A simple and economical micro-dissolved process of embedding titanium dioxide (TiO2) nanoparticles into surface zone of cotton fabrics was developed. TiO2 was coated on cotton fabrics in 7% wt NaOH/12% wt urea aqueous solution at low temperature. Photocatalytic efficiency of cotton fabrics treated with TiO2 nanoparticles was studied upon measuring the photocatalytic decoloration of Rhodamine B (RhB) under ultraviolet irradiation. Self-cleaning property of cotton fabric coated with TiO2 was evaluated with color depth of samples (K/S value). The treated fabrics were characterized using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectroscopy (FITR), tensile strength, stiffness and whiteness. The results indicated, TiO2 nanoparticles could be embedded on the surface layer of cotton fabrics throuth surface micro-dissolve method. Treated cotton fabrics possessed distinct photocatalytic efficiency and self-cleaning properties. Tensile strength and whiteness of modified cotton fabrics appeared moderately increasement.

Water-quality conditions near the confluence of the Snake and Boise Rivers, Canyon County, Idaho

USGS Publications Warehouse

Wood, Molly S.; Etheridge, Alexandra

2011-01-01

Total Maximum Daily Loads (TMDLs) have been established under authority of the Federal Clean Water Act for the Snake River-Hells Canyon reach, on the border of Idaho and Oregon, to improve water quality and preserve beneficial uses such as public consumption, recreation, and aquatic habitat. The TMDL sets targets for seasonal average and annual maximum concentrations of chlorophyll-a at 14 and 30 micrograms per liter, respectively. To attain these conditions, the maximum total phosphorus concentration at the mouth of the Boise River in Idaho, a tributary to the Snake River, has been set at 0.07 milligrams per liter. However, interactions among chlorophyll-a, nutrients, and other key water-quality parameters that may affect beneficial uses in the Snake and Boise Rivers are unknown. In addition, contributions of nutrients and chlorophyll-a loads from the Boise River to the Snake River have not been fully characterized. To evaluate seasonal trends and relations among nutrients and other water-quality parameters in the Boise and Snake Rivers, a comprehensive monitoring program was conducted near their confluence in water years (WY) 2009 and 2010. The study also provided information on the relative contribution of nutrient and sediment loads from the Boise River to the Snake River, which has an effect on water-quality conditions in downstream reservoirs. State and site-specific water-quality standards, in addition to those that relate to the Snake River-Hells Canyon TMDL, have been established to protect beneficial uses in both rivers. Measured water-quality conditions in WY2009 and WY2010 exceeded these targets at one or more sites for the following constituents: water temperature, total phosphorus concentrations, total phosphorus loads, dissolved oxygen concentration, pH, and chlorophyll-a concentrations (WY2009 only). All measured total phosphorus concentrations in the Boise River near Parma exceeded the seasonal target of 0.07 milligram per liter. Data collected

Does littoral sand bypass the head of Mugu Submarine Canyon? - a modeling study

USGS Publications Warehouse

Xu, Jingping; Elias, Edwin; Kinsman, Nicole; Wang, Ping; Rosati, Julie D.; Roberts, Tiffany M.

2011-01-01

A newly developed sand-tracer code for the process-based model Delft3D (Deltares, The Netherlands) was used to simulate the littoral transport near the head of the Mugu Submarine Canyon in California, USA. For westerly swells, which account for more than 90% of the wave conditions in the region, the sand tracers in the downcoast littoral drift were unable to bypass the canyon head. A flow convergence near the upcoast rim of the canyon intercepts the tracers and moves them either offshore onto the shelf just west of the canyon rim (low wave height conditions) or into the canyon head (storm wave conditions). This finding supports the notion that Mugu Canyon is the true terminus of the Santa Barbara Littoral Cell.

Influence of San Gabriel submarine canyon on narrow-shelf sediment dynamics, southern California

USGS Publications Warehouse

Karl, Herman A.

1980-01-01

A conceptual model attributes the PTC to modification of shelf circulation patterns by San Gabriel Canyon. Surface waves diverge over the canyon head resulting in differential wave set up at the shore face. This forces back turbid nearshore water for a distance of a few kilometers toward the canyon. At some point on the shelf, seaward nearshore flow overlaps offshore currents generated or modified by internal waves focused onto the shelf by the canyon and/or turbulent eddies produced by flow separation in currents moving across the canyon axis. At times, these subtle processes overprint tidal and wind-driven currents and thereby create the PTC. The model suggests that canyons heading several kilometers from shore can have a regulatory effect on narrow-shelf sediment dynamics.

Geomorphic characterization of four shelf-sourced submarine canyons along the U.S. Mid-Atlantic continental margin

USGS Publications Warehouse

Obelcz, Jeffrey; Brothers, Daniel S.; Chaytor, Jason D.; ten Brink, Uri S.; Ross, Steve W.; Brooke, Sandra

2013-01-01

Shelf-sourced submarine canyons are common features of continental margins and are fundamental to deep-sea sedimentary systems. Despite their geomorphic and geologic significance, relatively few passive margin shelf-breaching canyons worldwide have been mapped using modern geophysical methods. Between 2007 and 2012 a series of geophysical surveys was conducted across four major canyons of the US Mid-Atlantic margin: Wilmington, Baltimore, Washington, and Norfolk canyons. More than 5700 km2 of high-resolution multibeam bathymetry and 890 line-km of sub-bottom CHIRP profiles were collected along the outer shelf and uppermost slope (depths of 80-1200 m). The data allowed us to compare and contrast the fine-scale morphology of each canyon system. The canyons have marked differences in the morphology and orientation of canyon heads, steepness and density of sidewall gullies, and the character of the continental shelf surrounding canyon rims. Down-canyon axial profiles for Washington, Baltimore and Wilmington canyons have linear shapes, and each canyon thalweg exhibits morphological evidence for recent, relatively small-scale sediment transport. For example, Washington Canyon displays extremely steep wall gradients and contains ~100 m wide, 5–10 m deep, v-shaped incisions down the canyon axis, suggesting modern or recent sediment transport. In contrast, the convex axial thalweg profile, the absence of thalweg incision, and evidence for sediment infilling at the canyon head, suggest that depositional processes strongly influence Norfolk Canyon during the current sea-level high-stand. The north walls of Wilmington, Washington and Norfolk canyons are steeper than the south walls due to differential erosion, though the underlying cause for this asymmetry is not clear. Furthermore, we speculate that most of the geomorphic features observed within the canyons (e.g., terraces, tributary canyons, gullies, and hanging valleys) were formed during the Pleistocene, and show only

Effect of asymmetrical street canyons on pedestrian thermal comfort in warm-humid climate of Cuba

NASA Astrophysics Data System (ADS)

Rodríguez-Algeciras, José; Tablada, Abel; Matzarakis, Andreas

2017-07-01

Walkability and livability in cities can be enhanced by creating comfortable environments in the streets. The profile of an urban street canyon has a substantial impact on outdoor thermal conditions at pedestrian level. This paper deals with the effect of asymmetrical street canyon profiles, common in the historical centre of Camagüey, Cuba, on outdoor thermal comfort. Temporal-spatial analyses are conducted using the Heliodon2 and the RayMan model, which enable the generation of accurate predictions about solar radiation and thermal conditions of urban spaces, respectively. On these models, urban settings are represented by asymmetrical street canyons with five different height-to-width ratios and four street axis orientations (N-S, NE-SW, E-W, SE-NW). Results are evaluated for daytime hours across the street canyon, by means of the physiologically equivalent temperature (PET index) which allows the evaluation of the bioclimatic conditions of outdoor environments. Our findings revealed that high profiles (façades) located on the east-facing side of N-S streets, on the southeast-facing side of NE-SW streets, on the south-facing side of E-W street, and on the southwest-facing side of SE-NW streets, are recommended to reduce the total number of hours under thermal stress. E-W street canyons are the most thermally stressed ones, with extreme PET values around 36 °C. Deviating from this orientation ameliorates the heat stress with reductions of up to 4 h in summer. For all analysed E-W orientations, only about one fifth of the street can be comfortable, especially for high aspect ratios (H/W > 3). Optimal subzones in the street are next to the north side of the E-W street, northwest side of the NE-SW street, and southwest side of the SE-NW street. Besides, when the highest profile is located on the east side of N-S streets, then the subzone next to the east-facing façade is recommendable for pedestrians. The proposed urban guidelines enable urban planners to create

Influence of dissolved organic matter and manganese oxides on metal speciation in soil solution: A modelling approach.

PubMed

Schneider, Arnaud R; Ponthieu, Marie; Cancès, Benjamin; Conreux, Alexandra; Morvan, Xavier; Gommeaux, Maxime; Marin, Béatrice; Benedetti, Marc F

2016-06-01

Trace element (TE) speciation modelling in soil solution is controlled by the assumptions made about the soil solution composition. To evaluate this influence, different assumptions using Visual MINTEQ were tested and compared to measurements of free TE concentrations. The soil column Donnan membrane technique (SC-DMT) was used to estimate the free TE (Cd, Cu, Ni, Pb and Zn) concentrations in six acidic soil solutions. A batch technique using DAX-8 resin was used to fractionate the dissolved organic matter (DOM) into four fractions: humic acids (HA), fulvic acids (FA), hydrophilic acids (Hy) and hydrophobic neutral organic matter (HON). To model TE speciation, particular attention was focused on the hydrous manganese oxides (HMO) and the Hy fraction, ligands not considered in most of the TE speciation modelling studies in soil solution. In this work, the model predictions of free ion activities agree with the experimental results. The knowledge of the FA fraction seems to be very useful, especially in the case of high DOM content, for more accurately representing experimental data. Finally, the role of the manganese oxides and of the Hy fraction on TE speciation was identified and, depending on the physicochemical conditions of the soil solution, should be considered in future studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lung deposited surface area concentrations in a street canyon

NASA Astrophysics Data System (ADS)

Kuuluvainen, Heino; Hietikko, Riina; Järvinen, Anssi; Saukko, Erkka; Irjala, Matti; Niemi, Jarkko V.; Timonen, Hilkka; Keskinen, Jorma; Rönkkö, Topi

2017-04-01

Street canyons are interesting environments with respect to the dispersion of traffic emissions and human exposure. Pedestrians may be exposed to relatively high concentrations of fine particles and the vertical dispersion affects the human exposure above the ground level in buildings. Previously, particle concentrations have been measured in street canyons at a few different heights (Marini et al., 2015). The information on the lung deposited surface area (LDSA) concentration, which is a relevant metric for the negative health effects, is very limited even at the ground level of street canyons (Kuuluvainen et al., 2016). More information especially on the vertical dispersion and the ground level concentrations is needed, for instance, for the use of urban planning and the design of ventilation systems in buildings. Measurements were carried out in a busy street canyon in Helsinki, Finland, at an urban super-site measurement station (Mäkelänkatu 50). The data included vertical concentration profiles measured in an intensive measurement campaign with a Partector (Naneos GmbH) installed into a drone, long-term measurements with an AQ Urban particle sensor (Pegasor Ltd.), and an extensive comparison measurement in the field with different devices measuring the LDSA. These devices were an AQ Urban, Partector, DiSCmini (Testo AG), NSAM (TSI Inc.), and an ELPI+ (Dekati Ltd.). In addition, continuous measurements of gas phase components, particle size distributions, and meteorology were run at the supersite. The vertical profile measurements were con-ducted in November 2016 during two days. In the measurements, the drone was flown from the ground level to an altitude of 50 or 100 m, which is clearly above the roof level of the buildings. Altogether, 48 up-and-down flights were conducted during the two days. The vertical profiles were supported by continuous measurements at the ground level on both sides of the street canyon. The long-term measurements were conducted

Science Activities Associated with Proposed 2008 High-Flow Experiment at Glen Canyon Dam

USGS Publications Warehouse

Hamill, John

2008-01-01

Grand Canyon National Park lies approximately 15 miles downriver from Glen Canyon Dam, which was built on the Colorado River just south of the Arizona-Utah border. Because the dam stops most sediment moving downstream, its presence has resulted in erosion and shrinkage of river sandbars in Grand Canyon. Fewer and smaller sandbars mean smaller camping beaches for visitors to use, continued erosion of cultural sites, and possibly less habitat for native fish, including the endangered humpback chub. In an effort to restore sandbars and related habitat and to comply with its responsibilities under the Grand Canyon Protection Act, the Department of the Interior has proposed a high-flow release of water from Glen Canyon Dam in March 2008. The U.S. Geological Survey?s (USGS) Grand Canyon Monitoring and Research Center is responsible for coordinating research associated with the proposed experiment. The proposed studies are designed to evaluate the feasibility of using such high flows to improve a range of Grand Canyon resources.

The Molecular Composition of Dissolved Organic Matter in Forest Soils as a Function of pH and Temperature

PubMed Central

Roth, Vanessa-Nina; Dittmar, Thorsten; Gaupp, Reinhard; Gleixner, Gerd

2015-01-01

We examined the molecular composition of forest soil water during three different seasons at three different sites, using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). We examined oxic soils and tested the hypothesis that pH and season correlate with the molecular composition of dissolved organic matter (DOM). We used molecular formulae and their relative intensity from ESI-FT-ICR-MS for statistical analysis. Applying unconstrained and constrained ordination methods, we observed that pH, dissolved organic carbon (DOC) concentration and season were the main factors correlating with DOM molecular composition. This result is consistent with a previous study where pH was a main driver of the molecular differences between DOM from oxic rivers and anoxic bog systems in the Yenisei River catchment. At a higher pH, the molecular formulae had a lower degree of unsaturation and oxygenation, lower molecular size and a higher abundance of nitrogen-containing compounds. These characteristics suggest a higher abundance of tannin connected to lower pH that possibly inhibited biological decomposition. Higher biological activity at a higher pH might also be related to the higher abundance of nitrogen-containing compounds. Comparing the seasons, we observed a decrease in unsaturation, molecular diversity and the number of nitrogen-containing compounds in the course of the year from March to November. Temperature possibly inhibited biological degradation during winter, which could cause the accumulation of a more diverse compound spectrum until the temperature increased again. Our findings suggest that the molecular composition of DOM in soil pore waters is dynamic and a function of ecosystem activity, pH and temperature. PMID:25793306

The source of dissolved silicon in soil surface solutions of a temperate forest ecosystem: Ge/Si and Si isotope ratios as biogeochemical tracers

NASA Astrophysics Data System (ADS)

Cornelis, J.; Delvaux, B.; Cardinal, D.; André, L.; Ranger, J.; Opfergelt, S.

2010-12-01

Understand the biogeochemical cycle of silicon (Si) in the Earth’s critical zone and the dissolved Si transfer from the litho-pedosphere into the hydrosphere is of great interest for the global balance of biogeochemical processes, including the global C cycle. Indeed, the interaction between Si and C cycles regulates the atmospheric CO2 through the chemical weathering of silicate minerals, the C sequestration in stable organo-mineral compounds and the Si nutrition of phytoplankton CO2-consumers in oceans. H4SiO4 released by mineral dissolution contributes to the critical zone evolution through neoformation of secondary minerals, adsorption onto hydroxyl-bearing phases and recycling by vegetation and return of phytoliths on topsoil. The neoformation of secondary precipitates (clay minerals and phytoliths polymerized in plants) and adsorption of Si onto Fe and Al (hydr)oxides are processes favoring the light Si isotope incorporation, generating rivers enriched in heavy Si isotopes. On the other hand, clay minerals and phytoliths display contrasting Ge/Si ratios since clay-sized weathering products are enriched in Ge and phytoliths are depleted in Ge. Thus stable Si isotope and Ge/Si ratios constitute very interesting proxies to trace transfer of Si in the critical zone. Here we report Si isotopic and Ge/Si ratios of the different Si pools in a temperate soil-tree system (Breuil experimental forest, France) involving various tree species grown on Alumnic Cambisol derived from granitic bedrock. Relative to granitic bedrock (δ30Si = -0.07 ‰; Ge/Si = 2.5 µmol/mol), clay-sized minerals are enriched in 28Si (-1.07 ‰) and Ge (6.2 µmol/mol) while phytoliths are enriched in 28Si (-0.28 to -0.64 ‰) and depleted in Ge (0.1 to 0.3 µmol/mol). This contrast allows us to infer the relative contribution of litho/pedogenic and biogenic mineral dissolution on the release of H4SiO4 in soil surface solutions. The Si-isotope signatures and Ge/Si ratios of forest floor

Fast response modeling of a two building urban street canyon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pardyjak, E. R.; Brown, M. J.

2002-01-01

QWIC-URB is a fast response model designed to generate high resolution, 3-dimensional wind fields around buildings. The wind fields are produced using a mass consistent diagnostic wind model based on the work of Roeckle (1990, 1998) and Kaplan & Dinar (1996). QWIC-URB has been used for producing wind fields around single buildings with various incident wind angles (Pardyjak and Brown 2001). Recently, the model has been expanded to consider two-building, 3D canyon flow. That is, two rectangular parallelepipeds of height H, crosswind width W, and length L separated by a distance S. The purpose of this work is to continuemore » to evaluate the Roeckle (1990) model and develop improvements. In this paper, the model is compared to the twin high-rise building data set of Ohba et al. (1993, hereafter OSL93). Although the model qualitatively predicts the flow field fairly well for simple canyon flow, it over predicts the strength of vortex circulation and fails to reproduce the upstream rotor.« less

Composition, Distribution and Abundance of Anthropogenic Marine Debris in Northwest Atlantic Submarine Canyons

NASA Astrophysics Data System (ADS)

Heyl, T. P.; Nizinski, M. S.; Kinlan, B. P.; Shank, T. M.

2016-02-01

Submarine canyons are important productive habitats in the deep-sea, as well as downslope conduits for transporting sediment and organic material that enhances local and regional species diversity, including species and ecosystems vulnerable to anthropogenic activities. In 2012 and 2013, we documented and characterized deep-sea coral and sponge ecosystems in virtually unexplored northeast and mid-Atlantic canyons using WHOI's TowCam towed imaging system on the FSV Bigelow. Specifically, thirty-eight digital image TowCam surveys were completed in 10 canyons, with more than 91,000 images documenting not only deep-sea coral and sponge ecosystems and habitat features, but also anthropogenic debris. Canyons surveyed cover most of the latitudinal range of the northeast US region and include Toms Canyon complex, Ryan, Veatch, Gilbert, Powell, and Munson canyons. Each of these canyon hosted debris across depths of 550 to 2100m, consisting mostly of fisheries equipment, including fishing lines, traps, and nets. Potentially-land-based debris (e.g., plastic bags and magazines) was also present in all canyons surveyed. These substrates likely enhance colonization and often served as habitat for specific sessile and mobile species. Comparisons of debris in these canyons revealed depth-related differences, likely due to offshore extent of fishing activities, and will be compared to density and abundances of other deep-sea environments. The occurrence of anthropogenic debris on Northeast US canyon floors suggests major sources via transport ship and fishing-related activities and perhaps the rapid transport of debris through near-shore zones and entrainment in bottom currents.

pH, dissolved oxygen, and adsorption effects on metal removal in anaerobic bioreactors.

PubMed

Willow, Mark A; Cohen, Ronald R H

2003-01-01

Anaerobic bioreactors were used to test the effect of the pH of influent on the removal efficiency of heavy metals from acid-rock drainage. Two studies used a near-neutral-pH, metal-laden influent to examine the heavy metal removal efficiency and hydraulic residence time requirements of the reactors. Another study used the more typical low-pH mine drainage influent. Experiments also were done to (i) test the effects of oxygen content of feed water on metal removal and (ii) the adsorptive capacity of the reactor organic substrate. Analysis of the results indicates that bacterial sulfate reduction may be a zero-order kinetic reaction relative to sulfate concentrations used in the experiments, and may be the factor that controls the metal mass removal efficiency in the anaerobic treatment systems. The sorptive capacities of the organic substrate used in the experiments had not been exhausted during the experiments as indicated by the loading rates of removal of metals exceeding the mass production rates of sulfide. Microbial sulfate reduction was less in the reactors receiving low-pH influent during experiments with short residence times. Sulfate-reducing bacteria may have been inhibited by high flows of low-pH water. Dissolved oxygen content of the feed waters had little effect on sulfate reduction and metal removal capacity.

How Does CeIII Nitrate Dissolve in a Protic Ionic Liquid? A Combined Molecular Dynamics and EXAFS Study.

PubMed

Serva, Alessandra; Migliorati, Valentina; Spezia, Riccardo; D'Angelo, Paola

2017-06-22

A diluted solution of Ce(NO 3 ) 3 in the protic ionic liquid (IL) ethylammonium nitrate (EAN) was investigated using molecular dynamics (MD) simulations and extended X-ray absorption fine structure (EXAFS) spectroscopy. For the first time polarizable effects were included in the MD force field to describe a heavy metal ion in a protic IL, but, unlike water, they were found to be unessential. The Ce III ion first solvation shell is formed by nitrate ions arranged in an icosahedral structure, and an equilibrium between monodentate and bidentate ligands is present in the solution. By combining distance and angular distribution functions it was possible to unambiguously identify this peculiar coordination geometry around the ions dissolved in solution. The metal ions are solvated within the polar domains of the EAN nanostructure and the dissolved salt induces almost no reorganization of the pre-existing structure of EAN upon solubilization. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Creationism in the Grand Canyon, Texas Textbooks

NASA Astrophysics Data System (ADS)

Folger, Peter

2004-01-01

AGU President Bob Dickinson, together with presidents of six other scientific societies, have written to Joseph Alston, Superintendent of Grand Canyon National Park, pointing out that a creationist book, The Grand Canyon: A Different View, is being sold in bookstores within the borders of the park as a scientific explanation about Grand Canyon geologic history. President Dickinson's 16 December letter urges that Alston clearly separate The Grand Canyon: A Different View from books and materials that discuss the legitimate scientific understanding of the origin of the Grand Canyon. The letter warns the Park Service against giving the impression that it approves of the anti-science movement known as young-Earth creationism, or that it endorses the advancement of religious tenets disguised as science. The text of the letter is on AGU's Web site http://www.agu.org/sci_soc/policy/sci_pol.html. Also, this fall, AGU sent an alert to Texas members about efforts by intelligent design creationists aimed at weakening the teaching of biological evolution in textbooks used in Texas schools. The alert pointed scientists to a letter, drafted by AGU, together with the American Institute of Physics, the American Physical Society, the Optical Society of America, and the American Astronomical Society, that urged the Texas State Board of Education to adopt textbooks that presented only accepted, peer-reviewed science and pedagogical expertise. Over 550 scientists in Texas added their names to the letter (http://www.agu.org/sci_soc/policy/texas_textbooks.pdf ), sent to the Board of Education on 1 November prior to their vote to adopt a slate of new science textbooks. The Board voted 11-5 in favor of keeping the textbooks free of changes advocated by groups supporting intelligent design creationism.

Anomalous topography on the continental shelf around Hudson Canyon

USGS Publications Warehouse

Knebel, H.J.

1979-01-01

Recent seismic-reflection data show that the topography on the Continental Shelf around Hudson Canyon is composed of a series of depressions having variable spacings (< 100 m to 2 km), depths (1-10 m), outlines, and bottom configurations that give the sea floor an anomalous "jagged" appearance in profile. The acoustic and sedimentary characteristics, the proximity to relict shores, and the areal distribution indicate that this rough topography is an erosional surface formed on Upper Pleistocene silty sands about 13,000 to 15,000 years ago by processes related to Hudson Canyon. The pronounced southward extension of the surface, in particular, may reflect a former increase in the longshore-current erosion capacity caused by the loss of sediments over the canyon. Modern erosion or nondeposition of sediments has prevented the ubiquitous sand sheet on the Middle Atlantic shelf from covering the surface. The "anomalous" topography may, in fact, be characteristic of areas near other submarine canyons that interrupt or have interrupted the longshore drift of sediments. ?? 1979.

The timing of sediment transport down Monterey Submarine Canyon, offshore California

USGS Publications Warehouse

Stevens, Thomas; Paull, Charles K.; Ussler, William III; McGann, Mary; Buylaert, Jan-Pieter; Lundsten, Eve M.

2013-01-01

While submarine canyons are the major conduits through which sediments are transported from the continents out into the deep sea, the time it takes for sediment to pass down through a submarine canyon system is poorly constrained. Here we report on the first study to couple optically stimulated luminescence (OSL) ages of quartz sand deposits and accelerator mass spectrometry 14C ages measured on benthic foraminifera to examine the timing of sediment transport through the axial channel of Monterey Submarine Canyon and Fan, offshore California. The OSL ages date the timing of sediment entry into the canyon head while the 14C ages of benthic foraminifera record the deposition of hemipelagic sediments that bound the sand horizons. We use both single-grain and small (∼2 mm area) single-aliquot regeneration approaches on vibracore samples from fining-upward sequences at various water depths to demonstrate relatively rapid, decadal-scale sand transport to at least 1.1 km depth and more variable decadal- to millennial-scale transport to a least 3.5 km depth on the fan. Significant differences between the time sand was last exposed at the canyon head (OSL age) and the timing of deposition of the sand (from 14C ages of benthic foraminifera in bracketing hemipelagic sediments) are interpreted as indicating that the sand does not pass through the entire canyon instantly in large individual events, but rather moves multiple times before emerging onto the fan. The increased spread in single-grain OSL dates with water depth provides evidence of mixing and temporary storage of sediment as it moves through the canyon system. The ages also indicate that the frequency of sediment transport events decreases with distance down the canyon channel system. The amalgamated sands near the canyon head yield OSL ages that are consistent with a sub-decadal recurrence frequency while the fining-upward sand sequences on the fan indicate that the channel is still experiencing events with a 150�

5. Long view from canyon edge, west of the overlook, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. Long view from canyon edge, west of the overlook, showing relationship of Mather Point to neighboring south rim projections; view to southeast - Mather Point Overlook, South Entrance Road, Grand Canyon Village, Coconino County, AZ

Computer model of hydroponics nutrient solution pH control using ammonium.

PubMed

Pitts, M; Stutte, G

1999-01-01

A computer simulation of a hydroponics-based plant growth chamber using ammonium to control pH was constructed to determine the feasibility of such a system. In nitrate-based recirculating hydroponics systems, the pH will increase as plants release hydroxide ions into the nutrient solution to maintain plant charge balance. Ammonium is an attractive alternative to traditional pH controls in an ALSS, but requires careful monitoring and control to avoid overdosing the plants with ammonium. The primary advantage of using NH4+ for pH control is that it exploits the existing plant nutrient uptake charge balance mechanisms to maintain solution pH. The simulation models growth, nitrogen uptake, and pH of a l-m2 stand of wheat. Simulation results indicated that ammonium-based control of nutrient solution pH is feasible using a proportional integral controller. Use of a 1 mmol/L buffer (Ka = 1.6 x 10(-6)) in the nutrient solution is required.

Hydraulics of outburst floods spilling over a steep-walled canyon: Implications for paleo-discharges on Mars

NASA Astrophysics Data System (ADS)

Lapotre, Mathieu; Lamb, Michael

2013-04-01

Canyons carved by outburst floods are common landforms on Earth and Mars. These canyons are generally found in fractured basalts and jointed sedimentary rocks. Flood-carved canyons commonly have steep headwalls and a roughly constant width, and are often thought to have formed from upstream headwall propagation due to waterfall erosion. Because morphology is readily available from satellite imagery, these canyons offer a unique opportunity to quantify the discharge of rare, catastrophic paleo-floods on Earth and Mars. However, mechanistic relationships that relate canyon size to flood discharge have yet to be developed. We propose that the width of a canyon headwall in fractured rock is set by the spatial distribution of erosion around the rim of the canyon, which is controlled by the distribution of shear stresses induced by the overflowing water as it is focused into the canyon head. We test this hypothesis by performing a series of numerical simulations of flood-water focusing using ANUGA Hydro, a 2D-depth averaged, fully turbulent, hydraulic numerical modeling suite allowing for Froude-number transitions. The numerical simulations were designed to explore five dimensionless variables: the aspect ratio of the canyon (length normalized by width), the canyon width to flood-water width ratio, the canyon width to normal-flow depth ratio, the Froude number, and the topographic gradient upstream of the canyon. Preliminary results show that flow focusing leads to increased shear stresses at the canyon head compared to the sides of the canyon for subcritical floods and higher canyon aspect ratios. This suggests that proto-canyons start growing from a topographic defect in all directions until they reach a critical length for the side walls to dry. Once this critical length is attained, canyons focus most of the flood waters into their heads, and propagate upstream only, maintaining roughly constant widths. Preliminary results suggest that canyon width may be used to

Overview of the Colorado River Canyon from the helicopter pad. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Overview of the Colorado River Canyon from the helicopter pad. View of the Nevada side where new bridge will cross canyon, view northwest - Hoover Dam, Spanning Colorado River at Route 93, Boulder City, Clark County, NV

Ability of rabbit alveolar macrophages to dissolve metals.

PubMed

Lundborg, M; Lind, B; Camner, P

1984-01-01

Manganese dioxide particles, 0.1-0.5 micron, were added to samples of 2-3 X 10(6) rabbit alveolar macrophages. The amount of manganese added and dissolved from the particles, over periods of 0, 1, 3, and 5 days, was determined by flame atomic absorption spectrophotometry. Macrophages from six rabbits received about 10 micrograms of Mn, macrophages from two rabbits about 30 micrograms, and macrophages from another two rabbits about 100 micrograms. Over periods of 1, 3, and 5 days the macrophages in all three dose groups dissolved two to three times more Mn than was dissolved in control experiments. In control experiments solubility was studied in the medium without macrophages. Macrophages cultivated 3 days before the addition of MnO2 dissolved the particles within another 2 days to an extent similar to that in the control experiments. The ability of the macrophages to dissolve MnO2 particles might be related to the low pH values in the phagosomes. Studies of the ability of macrophages from various species to dissolve metal particles as well as of pH values in their phagosomes might lead to a better understanding of alveolar clearance of metal particles.

Low temperature dissolution flowsheet for Pu metal

DOE PAGES

Daniel, Jr., William E.; Almond, Philip M.; Rudisill, Tracy S.

2017-06-30

The Savannah River National Laboratory was requested to develop a Pu metal dissolution flowsheet at two reduced temperature ranges for implementation in the Savannah River Site H-Canyon facility. The dissolution and H 2 generation rates during Pu metal dissolution were investigated using a dissolving solution at ambient temperature (20–30°C) and for an intermediate temperature of 50–60°C. The Pu metal dissolution rate measured at 57°C was approximately 20 times slower than at boiling (112–116°C). As a result, the dissolution rate at ambient temperature (24°C) was approximately 80 times slower than the dissolution rate at boiling. Hydrogen concentrations were less than detectablemore » (<0.1 vol%).« less

Status and Trends of Resources Below Glen Canyon Dam Update - 2009

USGS Publications Warehouse

Hamill, John F.

2009-01-01

The protection of resources found in Glen Canyon National Recreation Area and Grand Canyon National Park, Arizona, emerged as a significant public concern in the decades following the completion of Glen Canyon Dam in 1963. The dam, which lies about 15 miles upstream from the park, altered the Colorado River's flow, temperature, and sediment-carrying capacity, resulting over time in beach erosion, expansion of nonnative species, and losses of native fish. During the 1990s, in response to public concern, Congress and the Department of the Interior embarked on an ongoing effort to reduce and address the effects of dam operations on downstream resources. In 2005, the U.S. Geological Survey produced a comprehensive report entitled 'The State of the Colorado River Ecosystem in Grand Canyon', which documented the condition and trends of resources downstream of Glen Canyon Dam from 1991 to 2004. This fact sheet updates the 2005 report to extend its findings to include data published through April 2009 for key resources.

Space-for-time substitution and the evolution of submarine canyons in a passive, progradational margin.

NASA Astrophysics Data System (ADS)

Micallef, Aaron; Ribó, Marta; Canals, Miquel; Puig, Pere; Lastras, Galderic; Tubau, Xavier

2013-04-01

40% of submarine canyons worldwide are located in passive margins, where they constitute preferential conduits of sediment and biodiversity hotspots. Recent studies have presented evidence that submarine canyons incising passive, progradational margins can co-evolve with the adjacent continental slope during long-term margin construction. The stages of submarine canyon initiation and their development into a mature canyon-channel system are still poorly constrained, however, which is problematic when attempting to reconstruct the development of passive continental margins. In this study we analyse multibeam echosounder and seismic reflection data from the southern Ebro margin (western Mediterranean Sea) to document the stages through which a first-order gully develops into a mature, shelf-breaching canyon and, finally, into a canyon-channel system. This morphological evolution allows the application of a space-for-time substitution approach. Initial gully growth on the continental slope takes place via incision and downslope elongation, with limited upslope head retreat. Gravity flows are the main driver of canyon evolution, whereas slope failures are the main agent of erosion; they control the extent of valley widening, promote tributary development, and their influence becomes more significant with time. Breaching of the continental shelf by a canyon results in higher water/sediment loads that enhance canyon development, particularly in the upper reaches. Connection of the canyon head with a paleo-river changes evolution dynamics significantly, promoting development of a channel and formation of depositional landforms. Morphometric analyses demonstrate that canyons develop into geometrically self-similar systems that approach steady-state and higher drainage efficiency. Canyon activity in the southern Ebro margin is pulsating and enhanced during sea level lowstands. Rapid sedimentation by extension of the palaeo-Millars River into the outermost shelf and upper

Composition characteristics and regularities of dissolving of hydroxyapatite materials obtained in water solutions with varied content of silicate ions

NASA Astrophysics Data System (ADS)

Solonenko, A. P.

2018-01-01

Research aimed at developing new bioactive materials for the repair of defects in bone tissues, do not lose relevance due to the strengthening of the regenerative approach in medicine. From this point of view, materials based on calcium phosphates, including silicate ions, consider as one of the most promising group of substances. Methods of synthesis and properties of hydroxyapatite doped with various amounts of SiO4 4- ions are described in literature. In the present work synthesis of a solid phase in the systems Ca(NO3)2 - (NH4)2HPO4 - Na2SiO3 - NH4OH - H2O (Cca/CP = 1.70) performed with a wide range of sodium silicate additive concentration (y = CSi/CP = 0 ÷ 5). It is established that under the studied conditions at y ≥ 0.3 highly dispersed poorly crystallized apatite containing isomorphic impurities of CO3 2- and SiO4 4- precipitates in a mixture with calcium hydrosilicate and SiO2. It is shown that the resulting composites can gradually dissolve in physiological solution and initiate passive formation of the mineral component of hard tissues.

Regional economic impacts of Grand Canyon river runners.

PubMed

Hjerpe, Evan E; Kim, Yeon-Su

2007-10-01

Economic impact analysis (EIA) of outdoor recreation can provide critical social information concerning the utilization of natural resources. Outdoor recreation and other non-consumptive uses of resources are viewed as environmentally friendly alternatives to extractive-type industries. While outdoor recreation can be an appropriate use of resources, it generates both beneficial and adverse socioeconomic impacts on rural communities. The authors used EIA to assess the regional economic impacts of rafting in Grand Canyon National Park. The Grand Canyon region of northern Arizona represents a rural US economy that is highly dependent upon tourism and recreational expenditures. The purpose of this research is twofold. The first is to ascertain the previously unknown regional economic impacts of Grand Canyon river runners. The second purpose is to examine attributes of these economic impacts in terms of regional multipliers, leakage, and types of employment created. Most of the literature on economic impacts of outdoor recreation has focused strictly on the positive economic impacts, failing to illuminate the coinciding adverse and constraining economic impacts. Examining the attributes of economic impacts can highlight deficiencies and constraints that limit the economic benefits of recreation and tourism. Regional expenditure information was obtained by surveying non-commercial boaters and commercial outfitters. The authors used IMPLAN input-output modeling to assess direct, indirect, and induced effects of Grand Canyon river runners. Multipliers were calculated for output, employment, and income. Over 22,000 people rafted on the Colorado River through Grand Canyon National Park in 2001, resulting in an estimated $21,100,000 of regional expenditures to the greater Grand Canyon economy. However, over 50% of all rafting-related expenditures were not captured by the regional economy and many of the jobs created by the rafting industry are lower-wage and seasonal. Policy

Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

USGS Publications Warehouse

Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

2015-01-01

“Clumped-isotope” thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope “clumps”). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals.We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect.Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3− and CO32−. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many

The Jurassic section along McElmo Canyon in southwestern Colorado

USGS Publications Warehouse

O'Sullivan, Robert B.

1997-01-01

In McElmo Canyon, Jurassic rocks are 1500-1600 ft thick. Lower Jurassic rocks of the Glen Canyon Group include (in ascending order) Wingate Sandstone, Kayenta Formation and Navajo Sandstone. Middle Jurassic rocks are represented by the San Rafael Group, which includes the Entrada Sandstone and overlying Wanakah Formation. Upper Jurassic rocks comprise the Junction Creek Sandstone overlain by the Morrison Formation. The Burro Canyon Formation, generally considered to be Lower Cretaceous, may be Late Jurassic in the McElmo Canyon area and is discussed with the Jurassic. The Upper Triassic Chinle Formation in the subsurface underlies, and the Upper Cretaceous Dakota Sandstone overlies, the Jurassic section. An unconformity is present at the base of the Glen Canyon Group (J-0), at the base of the San Rafael Group (J-2), and at the base of the Junction Creek Sandstone (J-5). Another unconformity of Cretaceous age is at the base of the Dakota Sandstone. Most of the Jurassic rocks consist of fluviatile, lacustrine and eolian deposits. The basal part of the Entrada Sandstone and the Wanakah Formation may be of marginal marine origin.

Event-driven sediment flux in Hueneme and Mugu submarine canyons, southern California

USGS Publications Warehouse

Xu, J. P.; Swarzenski, P.W.; Noble, M.; Li, A.-C.

2010-01-01

Vertical sediment fluxes and their dominant controlling processes in Hueneme and Mugu submarine canyons off south-central California were assessed using data from sediment traps and current meters on two moorings that were deployed for 6 months during the winter of 2007. The maxima of total particulate flux, which reached as high as 300+ g/m2/day in Hueneme Canyon, were recorded during winter storm events when high waves and river floods often coincided. During these winter storms, wave-induced resuspension of shelf sediment was a major source for the elevated sediment fluxes. Canyon rim morphology, rather than physical proximity to an adjacent river mouth, appeared to control the magnitude of sediment fluxes in these two submarine canyon systems. Episodic turbidity currents and internal bores enhanced sediment fluxes, particularly in the lower sediment traps positioned 30 m above the canyon floor. Lower excess 210Pb activities measured in the sediment samples collected during periods of peak total particulate flux further substantiate that reworked shelf-, rather than newly introduced river-borne, sediments supply most of the material entering these canyons during storms.

DISSOLUTION OF PLUTONIUM METAL IN 8-10 M NITRIC ACID

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudisill, T. S.; Pierce, R. A.

2012-07-02

The H-Canyon facility will be used to dissolve Pu metal for subsequent purification and conversion to plutonium dioxide (PuO{sub 2}) using Phase II of HB-Line. To support the new mission, the development of a Pu metal dissolution flowsheet which utilizes concentrated (8-10 M) nitric acid (HNO{sub 3}) solutions containing potassium fluoride (KF) is required. Dissolution of Pu metal in concentrated HNO{sub 3} is desired to eliminate the need to adjust the solution acidity prior to purification by anion exchange. The preferred flowsheet would use 8-10 M HNO{sub 3}, 0.015-0.07 M KF, and 0.5-1.0 g/L Gd to dissolve the Pu upmore » to 6.75 g/L. An alternate flowsheet would use 8-10 M HNO{sub 3}, 0.05-0.2 M KF, and 1-2 g/L B to dissolve the Pu. The targeted average Pu metal dissolution rate is 20 mg/min-cm{sup 2}, which is sufficient to dissolve a “standard” 2250-g Pu metal button in 24 h. Plutonium metal dissolution rate measurements showed that if Gd is used as the nuclear poison, the optimum dissolution conditions occur in 10 M HNO{sub 3}, 0.04-0.05 M KF, and 0.5-1.0 g/L Gd at 112 to 116 °C (boiling). These conditions will result in an estimated Pu metal dissolution rate of ~11-15 mg/min-cm{sup 2} and will result in dissolution times of 36-48 h for standard buttons. The recommended minimum and maximum KF concentrations are 0.03 M and 0.07 M, respectively. The data also indicate that lower KF concentrations would yield dissolution rates for B comparable to those observed with Gd at the same HNO{sub 3} concentration and dissolution temperature. To confirm that the optimal conditions identified by the dissolution rate measurements can be used to dissolve Pu metal up to 6.75 g/L in the presence of representative concentrations of Fe and Gd or B, a series of experiments was performed to demonstrate the flowsheets. In three of the five experiments, the offgas generation rate during the dissolution was measured and samples were analyzed for hydrogen gas (H{sub 2}). The

A selective and sensitive optical sensor for dissolved ammonia detection via agglomeration of fluorescent Ag nanoclusters and temperature gradient headspace single drop microextraction.

PubMed

Dong, Jiang Xue; Gao, Zhong Feng; Zhang, Ying; Li, Bang Lin; Li, Nian Bing; Luo, Hong Qun

2017-05-15

In this paper, a simple sensor platform is presented for highly selective and sensitive detection of dissolved ammonia in aqueous solutions without pretreatment based on temperature gradient headspace single drop microextraction (HS-SDME) technique, and fluorescence and UV-vis spectrophotometry are utilized with the Ag nanoclusters (Ag NCs) functioned by citrate and glutathione as the probe. The sensing mechanism is based on the volatility of ammonia gas and the active response of Ag NCs to pH change caused by the introduction of ammonia. High pH can make the Ag NCs agglomerate and lead to the obvious decrease of fluorescence intensity and absorbance of Ag NCs solution. Moreover, the presented method exhibits a remarkably high selectivity toward dissolved ammonia over most of inorganic ions and amino acid, and shows a good linear range of 10-350μM (0.14-4.9mgNL -1 ) with a low detection limit of 336nM (4.70μgNL -1 ) at a signal-to-noise ratio of 3. In addition, the practical applications of the sensor have been successfully demonstrated by detecting dissolved ammonia in real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

The Porcupine Bank Canyon coral mounds: oceanographic and topographic steering of deep-water carbonate mound development and associated phosphatic deposition

NASA Astrophysics Data System (ADS)

Mazzini, A.; Akhmetzhanov, A.; Monteys, X.; Ivanov, M.

2012-06-01

The head of a canyon system extending along the western Porcupine Bank (west of Ireland) and which accommodates a large field of giant carbonate mounds was investigated during two cruises (INSS 2000 and TTR-13). Multibeam and sidescan sonar data (600-1,150 m water depth) suggest that the pre-existing seabed topography acts as a significant factor controlling mound distribution and shape. The mounds are concentrated along the edges of the canyon or are associated with a complex fault system traced around the canyon head, comprising escarpments up to 60 m high and several km long. The sampling for geochemical and petrographic analysis of numerous types of authigenic deposits was guided by sidescan sonar and video recordings. Calcite-cemented biogenic rubble was observed at the top and on the flanks of the carbonate mounds, being associated with both living and dead corals ( Lophelia pertusa, Madrepora oculata and occasional Desmophyllum cristagalli). This can plausibly be explained by dissolution of coral debris facilitated by strong currents along the mound tops and flanks. In turn, the dissolved carbon is recycled and precipitated as interstitial micrite. Calcite, dolomite and phosphatic hardgrounds were identified in samples from the escarpment framing the eastern part of the survey area. The laterally extensive phosphatic hardgrounds represent a novel discovery in the region, supplying hard substrata for the establishment of new coral colonies. Based on existing knowledge of regional oceanographic conditions, complemented with new CTD measurements, it is suggested that water column stratification, enhanced bottom currents, and upwelling facilitate the deposition of organic matter, followed by phosphatisation leading to the formation of phosphate-glauconite deposits. The occurrence of strong bottom currents was confirmed by means of video observations combined with acoustic and sampling data, providing circumstantial evidence of fine- to medium-grained sand

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

36 CFR 7.70 - Glen Canyon National Recreation Area.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Glen Canyon National Recreation Area. 7.70 Section 7.70 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF... in excess of flat wake speed on the Escalante River from Cow Canyon to Coyote Creek. (3) After...

Stability of a novel corticosteroid nasal irrigation solution: betamethasone 17-valerate added to extemporaneously prepared nasal irrigation solutions.

PubMed

Ong, Kheng Yong; Lim, Wei Ching; Ooi, Shing Ming; Loh, Zhi Hui; Kong, Ming Chai; Chan, Lai Wah; Heng, Paul Wan Sia

2017-05-01

There are no commercially available nasal irrigation solutions containing corticosteroids. Instead, such preparations are extemporaneously prepared by adding existing corticosteroid formulations to nasal irrigation solutions. The stability of the corticosteroid betamethasone 17-valerate (B17V), in nasal irrigation solutions of different compositions and pH and stored under different temperatures, was studied to determine the optimal choice of solution and storage conditions. Triplicate extemporaneous preparations made with B17V were prepared by adding a predetermined volume of B17V lotion to each nasal irrigation solution: normal saline (NS), sodium bicarbonate (NaHCO 3 ) powder dissolved in tap water, and a commercially available powder mixture (FLO Sinus Care Powder), dissolved in tap water or pre-boiled tap water. Preparations were stored at 30°C and 4°C. Sampling was carried out at 0, 1, 2, 6, and 24 hours. The concentrations of B17V and its degradation compound, betamethasone 21-valerate (B21V), were determined by high-performance liquid chromatography. Preparations stored at 30°C contained a lower amount of B17V and higher amount of B21V than those stored at 4°C. B17V stability in nasal irrigation solutions decreased in the following order: NS, FLO in fresh tap water, FLO in pre-boiled tap water, and NaHCO 3 . The degradation rate of B17V increased with higher storage temperature and higher pH. B17V is most stable when added to NS and least stable in NaHCO 3 solution. FLO solution prepared with either cooled boiled water or tap water is an alternative if administered immediately. Storage at 4°C can better preserve stability of B17V, over a period of 24 hours. © 2017 ARS-AAOA, LLC.

Megabenthic assemblages at the Hudson Canyon head (NW Atlantic margin): Habitat-faunal relationships

NASA Astrophysics Data System (ADS)

Pierdomenico, Martina; Gori, Andrea; Guida, Vincent G.; Gili, Josep-Maria

2017-09-01

The distribution of megabenthic communities at the head of Hudson Canyon and adjacent continental shelf was studied by means of underwater video transects and still photo imagery collected using a towed camera system. The goal was to explore the relationships between faunal distribution and physical seafloor conditions and to test the hypothesis that increased seafloor heterogeneity in the Hudson Canyon supports a larger diversity of benthic communities, compared with the adjacent continental shelf. Hierarchical cluster analysis was performed to identify benthic assemblages as defined in imagery. The BIO-ENV procedure and the Canonical Correspondence Analysis were carried out to elucidate species groupings in relation to terrain variables extracted from bathymetric data. Species accumulation curves were generated to evaluate species turn over in and out of Hudson Canyon. The results indicate that seafloor morphology is the main physical factor related to benthic community composition and distribution. Assemblages dominated by sponges, zoanthids and cup corals colonized the canyon margins and flanks, and were associated with coarse-grained sediments, while sea pen assemblages were observed along muddy seafloor within the thalweg. An assemblage dominated by sea stars occurred on the shelf, associated with a sandy seafloor. Some assemblages were exclusively observed in the canyon area, suggesting that the increased variability of seafloor composition, together with the oceanographic processes specific to the canyon area, enhance beta diversity. The colonization by benthic suspension feeders within the canyon, in contrast to shelf assemblages, mainly composed of carnivores and detritus feeders could be favored the intense hydrodynamics at the canyon head that increase the availability of suspended organic matter. From the perspective of management and conservation of marine resources, the results obtained support the relevance of Hudson Canyon as a biodiversity hotspot

Identification of Mercury and Dissolved Organic Matter Complexes Using Ultrahigh Resolution Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Hongmei; Johnston, Ryne C.; Mann, Benjamin F.

The chemical speciation and bioavailability of mercury (Hg) is markedly influenced by its complexation with naturally dissolved organic matter (DOM) in aquatic environments. To date, however, analytical methodologies capable of identifying such complexes are scarce. Here, we utilize ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) coupled with electrospray ionization to identify individual Hg-DOM complexes. The measurements were performed by direct infusion of DOM in a 1:1 methanol:water solution at a Hg to dissolved organic carbon (DOC) molar ratio of 3 × 10 -4. Heteroatomic molecules, especially those containing multiple S and N atoms, were found to bemore » among the most important in forming strong complexes with Hg. Major Hg-DOM complexes of C10H21N2S4Hg+ and C8H17N2S4Hg+ were identified based on both the exact molecular mass and patterns of Hg stable isotope distributions detected by FTICR-MS. Density functional theory was used to predict the solution-phase structures of candidate molecules. These findings represent the first step to unambiguously identify specific DOM molecules in Hg binding, although future studies are warranted to further optimize and validate the methodology so as to explore detailed molecular compositions and structures of Hg-DOM complexes that affect biological uptake and transformation of Hg in the environment.« less

H2S Injection and Sequestration into Basalt - The SulFix Project

NASA Astrophysics Data System (ADS)

Gudbrandsson, S.; Moola, P.; Stefansson, A.

2014-12-01

Atmospheric H2S emissions are among major environmental concern associated with geothermal energy utilization. It is therefore of great importance for the geothermal power sector to reduce H2S emissions. Known solutions for H2S neutralization are both expensive and include production of elemental sulfur and sulfuric acid that needs to be disposed of. Icelandic energy companies that utilize geothermal power for electricity production have decided to try to find an environmentally friendly and economically feasible solution to reduce the H2S emission, in a joint venture called SulFix. The aim of SulFix project is to explore the possibilities of injecting H2S dissolved in water into basaltic formations in close proximity to the power plants for permanent fixation as sulfides. The formation of sulfides is a natural process in geothermal systems. Due to basalt being rich in iron and dissolving readily at acidic conditions, it is feasible to re-inject the H2S dissolved in water, into basaltic formations to form pyrite. To estimate the mineralization rates of H2S, in the basaltic formation, flow through experiments in columns were conducted at various H2S concentrations, temperatures (100 - 240°C) and both fresh and altered basaltic glass. The results indicate that pyrite rapidly forms during injection into fresh basalt but the precipiation in altered basalt is slower. Three different alteration stages, as a function of distance from inlet, can be observed in the column with fresh basaltic glass; (1) dissolution features along with precipitation, (2) precipitation increases, both sulfides and other secondary minerals and (3) the basalt looks to be unaltered and little if any precipitation is observed. The sulfur has precipitated in the first half of the column and thereafter the solution is possibly close to be supersaturated with respect to the rock. These results indicate that the H2S sequestration into basalt is possible under geothermal conditions. The rate limiting

Establishing a pre-mining geochemical baseline at a uranium mine near Grand Canyon National Park, USA

USGS Publications Warehouse

Naftz, David L.; Walton-Day, Katherine

2016-01-01

During 2012, approximately 404,000 ha of Federal Land in northern Arizona was withdrawn from consideration of mineral extraction for a 20-year period to protect the Grand Canyon watershed from potentially adverse effects of U mineral exploration and development. The development, operation, and reclamation of the Canyon Mine during the withdrawal period provide an excellent field site to understand and document off-site migration of radionuclides within the withdrawal area. As part of the Department of Interior's (DOI's) study plan for the exclusion area, the objective of our study is to utilize pre-defined decision units (DUs) in areas within and surrounding the Canyon Mine to demonstrate how newly established incremental sampling methodologies (ISM) combined with multivariate statistical methods can be used to document a repeatable and statistically defensible measure of pre-mining baseline conditions in surface soils and stream sediment samples prior to ore extraction. During the survey in June 2013, the highest pre-mining 95% upper confidence level (UCL) concentrations with respect to As, Mo, U, and V were found in the triplicate samples collected from surface soils in the mine site DU designated as M1. Gamma activities were slightly elevated in soils within the M1 DU (up to 28 μR/h); however, off-site gamma activities in soil and stream-sediment samples were lower (< 6 to 12 μR/h). Hierarchical cluster analysis (HCA) was applied to 33 chemical constituents contained in the multivariate data generated from the analysis of triplicate samples collected in the soil and stream sediment DUs within and surrounding Canyon Mine. Most of the triplicate samples from individual DUs were grouped in the same dendrogram cluster when using a similarity value (SV) of 0.70 (unitless). Different group membership of triplicate samples from two of the four haul road DUs was likely the result of heterogeneity induced by non-native soil material introduced from the gravel road base

Submarine canyons represent an essential habitat network for krill hotspots in a Large Marine Ecosystem.

PubMed

Santora, Jarrod A; Zeno, Ramona; Dorman, Jeffrey G; Sydeman, William J

2018-05-15

Submarine canyon systems are ubiquitous features of marine ecosystems, known to support high levels of biodiversity. Canyons may be important to benthic-pelagic ecosystem coupling, but their role in concentrating plankton and structuring pelagic communities is not well known. We hypothesize that at the scale of a large marine ecosystem, canyons provide a critical habitat network, which maintain energy flow and trophic interactions. We evaluate canyon characteristics relative to the distribution and abundance of krill, critically important prey in the California Current Ecosystem. Using a geological database, we conducted a census of canyon locations, evaluated their dimensions, and quantified functional relationships with krill hotspots (i.e., sites of persistently elevated abundance) derived from hydro-acoustic surveys. We found that 76% of krill hotspots occurred within and adjacent to canyons. Most krill hotspots were associated with large shelf-incising canyons. Krill hotspots and canyon dimensions displayed similar coherence as a function of latitude and indicate a potential regional habitat network. The latitudinal migration of many fish, seabirds and mammals may be enhanced by using this canyon-krill network to maintain foraging opportunities. Biogeographic assessments and predictions of krill and krill-predator distributions under climate change may be improved by accounting for canyons in habitat models.

The t-PA-encapsulated PLGA nanoparticles shelled with CS or CS-GRGD alter both permeation through and dissolving patterns of blood clots compared with t-PA solution: an in vitro thrombolysis study.

PubMed

Wang, Shoei-Shen; Chou, Nai-Kuan; Chung, Tze-Wen

2009-12-01

Accelerated thrombolysis by pressure-driven permeation has been demonstrated in in vitro and in vivo animal models by using plasminogen activators (PAs) encapsulated liposomes or PEG microparticles. Recent reports have also described acceleration of thrombolysis using tissue type PA (t-PA) encapsulated in PLGA nanoparticles (NPs) coated with chitosan (CS) or CS-GRGD by interactions between the NPs and blood clots. However, the permeation through and dissolving patterns in thrombolysis with the aforementioned microparticles or NPs, which may be clinically relevant to the recovery status of the posttreatments, have not been reported. Therefore, this work studied such phenomena in thrombolysis with t-PA encapsulated in NPs. The t-PA solution and the NPs exhibited distinctly different permeation patterns of dissolved clots. Plasma permeates through clots showed a stream flow or burst flow phenomena when lyzed with NPs shelled with CS or CS-GRGD, respectively, whereas a diffusion pattern was observed in those lyzed with t-PA solution. At the outlet position of clots, the clots dissolved with PLGA/CS and PLGA/CS-GRGD NPs revealed extremely rough surfaces to a depth of 100 mum, indicating that a cross-permeation direction of clot lysis occurred, while those dissolved with t-PA solution showed slightly rough surfaces to a depth of 12 mum. Permeation through and clot dissolution patterns of thrombolysis with t-PA encapsulated in NPs shelled with CS or CS-GRGD distinctly differed from those dissolved with t-PA solutions in this in vitro thrombolysis model, These findings may be relevant to posttreatment of patients with conventional PA thrombolysis. Copyright 2008 Wiley Periodicals, Inc.

Electrochemical control of pH in a hydroponic nutrient solution

NASA Technical Reports Server (NTRS)

Schwartzkopf, S. H.

1986-01-01

The electrochemical pH control system described was found to provide a feasible alternative method of controlling nutrient solution pH for CELSS applications. The plants grown in nutrient solution in which the pH was controlled electrochemically showed no adverse effects. Further research into the design of a larger capacity electrode bridge for better control is indicated by the results of this experiment, and is currently under way.

4. VISTA POINT AND INTERPRETIVE PLAQUE AT LEE VINING CANYON. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. VISTA POINT AND INTERPRETIVE PLAQUE AT LEE VINING CANYON. NOTE ROAD CUT ON CANYON WALL. LOOKING NNE. GIS: N-37 56 30.3 / 119 13 44.8 - Tioga Road, Between Crane Flat & Tioga Pass, Yosemite Village, Mariposa County, CA

ACID EVAPORATION OF ULTIMA GOLD TM AB LIQUID SCINTILLATION COCKTAIL RESIDUE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kyser, E.; Fondeur, F.; Crump, S.

2011-12-21

Prior analyses of samples from the F/H Lab solutions showed the presence of diisopropylnapthalene (DIN), a major component of Ultima Gold{trademark} AB liquid scintillation cocktail (LSC). These solutions are processed through H-Canyon Tank 10.5 and ultimately through the 17.8E evaporator. Similar solutions originated in SRNL streams sent to the same H Canyon tanks. This study examined whether the presence of these organics poses a process-significant hazard for the evaporator. Evaporation and calorimetry testing of surrogate samples containing 2000 ppm of Ultima Gold{trademark} AB LSC in 8 M nitric acid have been completed. These experiments showed that although reactions between nitricmore » acid and the organic components do occur, they do not appear to pose a significant hazard for runaway reactions or generation of energetic compounds in canyon evaporators. The amount of off-gas generated was relatively modest and appeared to be well within the venting capacity of the H-Canyon evaporators. A significant fraction of the organic components likely survives the evaporation process primarily as non-volatile components that are not expected to represent any new process concerns during downstream operations such as neutralization. Laboratory Waste solutions containing minor amounts of DIN can be safely received, stored, transferred, and processed through the canyon waste evaporator.« less

REDUCTION OF PLUTONIUM VALUES IN AN ACIDIC AQUEOUS SOLUTION WITH FORMALDEHYDE

DOEpatents

Olson, C.M.

1959-06-01

A method is given for reducing Pu to the tetravalent state and lowering the high acidity of dissolver solutions containing U and Pu. Formaldehyde is added to the HNO/sub 3/ solution of U and Pu to effect a formaldehyde to HNO/sub 3/ molar ratio of 0.375:1 to 1.5:1. The Pu can then be removed from the solution by carrier precipitation using BiPO/sub 4/ or by ion exchange. (T.R.H.)

36 CFR 7.92 - Bighorn Canyon National Recreation Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Bighorn Canyon National Recreation Area. 7.92 Section 7.92 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.92 Bighorn Canyon National Recreation Area. (a) Aircraft-designated...

Rapid formation of a modern bedrock canyon by a single flood event

NASA Astrophysics Data System (ADS)

Lamb, Michael P.; Fonstad, Mark A.

2010-07-01

Deep river canyons are thought to form slowly over geological time (see, for example, ref. 1), cut by moderate flows that reoccur every few years. In contrast, some of the most spectacular canyons on Earth and Mars were probably carved rapidly during ancient megaflood events. Quantification of the flood discharge, duration and erosion mechanics that operated during such events is hampered because we lack modern analogues. Canyon Lake Gorge, Texas, was carved in 2002 during a single catastrophic flood. The event offers a rare opportunity to analyse canyon formation and test palaeo-hydraulic-reconstruction techniques under known topographic and hydraulic conditions. Here we use digital topographic models and visible/near-infrared aerial images from before and after the flood, discharge measured during the event, field measurements and sediment-transport modelling to show that the flood moved metre-sized boulders, excavated ~7m of limestone and transformed a soil-mantled valley into a bedrock canyon in just ~3days. We find that canyon morphology is strongly dependent on rock type: plucking of limestone blocks produced waterfalls, inner channels and bedrock strath terraces, whereas abrasion of cemented alluvium sculpted walls, plunge pools and streamlined islands. Canyon formation was so rapid that erosion might have been limited by the ability of the flow to transport sediment. We suggest that our results might improve hydraulic reconstructions of similar megafloods on Earth and Mars.

Giant landslides and turbidity currents in the Agadir Canyon Region, NW-Africa

NASA Astrophysics Data System (ADS)

Krastel, Sebastian; Wynn, Russell B.; Stevenson, Christopher; Feldens, Peter; Mehringer, Lisa; Schürer, Anke

2017-04-01

Coring and drilling of the Moroccan Turbidite System off NW-Africa revealed a long sequence of turbidites, mostly sourced from the Moroccan continental margin and the volcanic Canary Islands. The largest individual flow deposits in the Moroccan Turbidite System contain sediment volumes >100 km3, although these large-scale events are relatively infrequent with a recurrence interval of 10,000 years (over the last 200,000 years). The largest siliciclastic flow in the last 200,000 years was the 'Bed 5 event', which transported 160 km3 of sediment up to 2000 km from the Agadir Canyon region to the southwest Madeira Abyssal Plain. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during RV Maria S. Merian Cruise MSM32 in late 2013. A major landslide area was identified 200 km south of the Agadir Canyon. A landslide was traced from this failure area to the Agadir Canyon. This landslide entered the canyon in about 2500 m water depth. Despite a significant increase in slope angle, the landslide did not disintegrate into a turbidity current when entering the canyon but moved on as landslide for at least another 200 km down the canyon. The age of the landslide ( 145 ka) does not correspond to any major turbidte deposit in the Moroccan Turbidite System, further supporting the fact that the landslide did not disintegrate into a major turbidity current. A core taken about 350 m above the thalweg in the head region of Agadir Canyon shows a single coarse-grained turbidite, which resembles the composition of the Bed 5 event in the Madeira Abyssal Plain. Hence, the Bed 5 turbidite originated as a failure in the

Biodiversity of macrofaunal assemblages from three Portuguese submarine canyons (NE Atlantic)

NASA Astrophysics Data System (ADS)

Cunha, Marina R.; Paterson, Gordon L. J.; Amaro, Teresa; Blackbird, Sabena; de Stigter, Henko C.; Ferreira, Clarisse; Glover, Adrian; Hilário, Ana; Kiriakoulakis, Konstadinos; Neal, Lenka; Ravara, Ascensão; Rodrigues, Clara F.; Tiago, Áurea; Billett, David S. M.

2011-12-01

The macrofaunal assemblages from three Portuguese submarine canyons, Nazaré, Cascais and Setúbal were studied from samples collected at their upper (900-1000 m), middle (3200-3500 m) and lower sections (4200-4500 m) and at the adjacent open slopes (˜1000 m), during the HERMES cruises D297 (R.R.S. Discovery, 2005) CD179 (R.R.S. Charles Darwin, 2006) and 64PE252 (R.V. Pelagia, 2006). The taxonomic composition and patterns in biodiversity, abundance and community structure of the benthic macrofauna were described. Annelida (42.1% of total abundance; 137 species) and Arthropoda (20.6%; 162 species) were, respectively, the most abundant and the most species-rich Phyla among the 342 taxa identified during this study. Multivariate analyses showed significant differences between and within canyons and between canyons and open slope assemblages. At their upper section, canyons supported higher macrofauna abundance but slightly lower biodiversity than the adjacent slopes at similar depth. In all canyons abundance reached the highest value in the middle section and the lowest in the upper section, with marked fluctuations in Nazaré (474-4599 ind. m -2) and lower variability in Cascais (583-1125 ind. m -2). The high abundance and dominance of the assemblages in the middle section of Nazaré and Setúbal was accompanied by depressed biodiversity, while in Cascais, Hurlbert's expected species richness showed increasing values from the upper to the middle canyon, and maintained the high values at the lower section. Overall, the Nazaré Canyon showed the lowest expected species richness (ES (100): 16-39) and the Cascais Canyon the highest (39-54). There was a significant negative Kendall's correlation between total organic carbon concentrations in the superficial sediments and ES (100) and a significant positive correlation between total nitrogen and macrofauna density. The influences of organic enrichment, sediment heterogeneity and hydrodynamic regime on the abundance

Supersaturation of Dissolved Hydrogen and Methane in Rumen of Tibetan Sheep

PubMed Central

Wang, Min; Ungerfeld, Emilio M.; Wang, Rong; Zhou, Chuan She; Basang, Zhu Zha; Ao, Si Man; Tan, Zhi Liang

2016-01-01

Hydrogen (H2) is an essential substrate for methanogens to produce methane (CH4), and also influences pathways of volatile fatty acids (VFA) production in the rumen. Dissolved H2 (H2 (aq)) is the form of H2 available to microbes, and dissolved CH4 (CH4 (aq)) is important for indicating methanogens activity. Rumen H2 (aq) concentration has been estimated by assuming equilibrium with headspace gaseous H2 (H2 (g)) concentration using Henry's law, and has also been directly measured in the liquid phase in some in vitro and in vivo experiments. In this in vivo study, H2 (aq) and CH4 (aq) concentration measured directly in rumen fluid and their corresponding concentrations estimated from their gaseous phase concentrations, were compared to investigate the existence of equilibrium between the gas and liquid phases. Twenty-four Tibetan sheep were randomly assigned to two mixed diets containing the same concentrate mixed with oat grass (OG diet) or barley straw (BS diet). Rumen gaseous phase and contents were sampled using rumenocentesis and oral stomach tubing, respectively. Rumen H2 (aq) and CH4 (aq) concentration and VFA profile differed between sheep fed OG and BS diets. Measured H2 (aq) and CH4 (aq) concentration were greater than H2 (aq) and CH4 (aq) concentrations estimated using gas concentrations, indicating lack of equilibrium between gas and liquid phase and supersaturation of H2 and CH4 in rumen fluid. As a consequence, Gibbs energy changes (ΔG) estimated for various metabolic pathways were different when calculated using dissolved gases concentrations directly measured and when using dissolved gases concentrations assuming equilibrium with the gaseous phase. Dissolved CH4, but not CH4 (g), was positively correlated with H2 (aq). Both H2 (aq) and H2 (g) concentrations were positively correlated with the molar percentage of butyrate and negatively correlated with the molar percentage of acetate. In summary, rumen fluid was supersaturated with both H2 and CH4

CORRELATION OF THE PARTITIONING OF DISSOLVED ORGANIC MATTER FRACTIONS WITH THE DESORPTION OF CD, CU, NI, PB AND ZN FROM 18 DUTCH SOILS

EPA Science Inventory

Eighteen Dutch soils were extracted in aqueous solutions at varying pH. Extracts were analyzed for Cd, Cu, Ni, Pb and Zn by ICP-AES. Extract dissolved organic carbon (DOC) was also concentrated onto a macroreticular resin and fractionation into three operationally defined fract...

Re-collection of Fish Canyon Tuff for fission-track standardization

USGS Publications Warehouse

Naeser, C.W.; Cebula, G.T.

1984-01-01

The PURPOSE of this note is to announce the availability of apatite and zircon from a third collection of the Oligocene Fish Canyon Tuff (FC-3). Apatite and zircon separated from the Fish Canyon Tuff have prove to be a useful standard for fission-track dating, both for interlaboratory comparisons and for checking procedures within a laboratory. In May 1981, about 540 kg of Fish Canyon Tuff were collected for mineral separation. Approximately 7. 5 g of apatite, 6. 5 g of zircon, and 89 g of sphene were recovered from this collection. This new material is now ready for distribution.

33 CFR 165.1171 - Copper Canyon, Lake Havasu, Colorado River-Regulated Navigation Area.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Copper Canyon, Lake Havasu... Guard District § 165.1171 Copper Canyon, Lake Havasu, Colorado River—Regulated Navigation Area. (a) Location. The following is a regulated navigation area: (1) In the water area of Copper Canyon, Lake Havasu...

33 CFR 165.1171 - Copper Canyon, Lake Havasu, Colorado River-Regulated Navigation Area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Copper Canyon, Lake Havasu... Guard District § 165.1171 Copper Canyon, Lake Havasu, Colorado River—Regulated Navigation Area. (a) Location. The following is a regulated navigation area: (1) In the water area of Copper Canyon, Lake Havasu...

A Numerical Simulation of Traffic-Related Air Pollution Exposures in Urban Street Canyons

NASA Astrophysics Data System (ADS)

Liu, J.; Fu, X.; Tao, S.

2016-12-01

Urban street canyons are usually associated with intensive vehicle emissions. However, the high buildings successively along both sides of a street block the dispersion of traffic-generated air pollutants, which enhances human exposure and adversely affects human health. In this study, an urban scale traffic pollution dispersion model is developed with the consideration of street distribution, canyon geometry, background meteorology, traffic assignment, traffic emissions and air pollutant dispersion. Vehicle exhausts generated from traffic flows will first disperse inside a street canyon along the micro-scale wind field (generated by computational fluid dynamics (CFD) model) and then leave the street canyon and further disperse over the urban area. On the basis of this model, the effects of canyon geometry on the distribution of NOx and CO from traffic emissions were studied over the center of Beijing, China. We found that an increase of building height along the streets leads to higher pollution levels inside streets and lower pollution levels outside, resulting in higher domain-averaged concentrations over the area. In addition, street canyons with equal (or highly uneven) building heights on two sides of a street tend to lower the urban-scale air pollution concentrations at pedestrian level. Our results indicate that canyon geometry strongly influences human exposure to traffic pollutants in the populated urban area. Carefully planning street layout and canyon geometry in consideration of traffic demand as well as local weather pattern may significantly reduce the chances of unhealthy air being inhaled by urban residents.

Analysis of local scale tree-atmosphere interaction on pollutant concentration in idealized street canyons and application to a real urban junction

NASA Astrophysics Data System (ADS)

Buccolieri, Riccardo; Salim, Salim Mohamed; Leo, Laura Sandra; Di Sabatino, Silvana; Chan, Andrew; Ielpo, Pierina; de Gennaro, Gianluigi; Gromke, Christof

2011-03-01

This paper first discusses the aerodynamic effects of trees on local scale flow and pollutant concentration in idealized street canyon configurations by means of laboratory experiments and Computational Fluid Dynamics (CFD). These analyses are then used as a reference modelling study for the extension a the neighbourhood scale by investigating a real urban junction of a medium size city in southern Italy. A comparison with previous investigations shows that street-level concentrations crucially depend on the wind direction and street canyon aspect ratio W/H (with W and H the width and the height of buildings, respectively) rather than on tree crown porosity and stand density. It is usually assumed in the literature that larger concentrations are associated with perpendicular approaching wind. In this study, we demonstrate that while for tree-free street canyons under inclined wind directions the larger the aspect ratio the lower the street-level concentration, in presence of trees the expected reduction of street-level concentration with aspect ratio is less pronounced. Observations made for the idealized street canyons are re-interpreted in real case scenario focusing on the neighbourhood scale in proximity of a complex urban junction formed by street canyons of similar aspect ratios as those investigated in the laboratory. The aim is to show the combined influence of building morphology and vegetation on flow and dispersion and to assess the effect of vegetation on local concentration levels. To this aim, CFD simulations for two typical winter/spring days show that trees contribute to alter the local flow and act to trap pollutants. This preliminary study indicates that failing to account for the presence of vegetation, as typically practiced in most operational dispersion models, would result in non-negligible errors in the predictions.

Variability of CO2 concentrations and fluxes in and above an urban street canyon

NASA Astrophysics Data System (ADS)

Lietzke, Björn; Vogt, Roland

2013-08-01

The variability of CO2 concentrations and fluxes in dense urban environments is high due to the inherent heterogeneity of these complex areas and their spatio-temporally variable anthropogenic sources. With a focus on micro- to local-scale CO2-exchange processes, measurements were conducted in a street canyon in the city of Basel, Switzerland in 2010. CO2 fluxes were sampled at the top of the canyon (19 m) and at 39 m while vertical CO2 concentration profiles were measured in the center and at a wall of the canyon. CO2 concentration distributions in the street canyon and exchange processes with the layers above show, apart from expected general diurnal patterns due mixing layer heights, a strong dependence on wind direction relative to the canyon. As a consequence of the resulting corkscrew-like canyon vortex, accumulation of CO2 inside the canyon is modulated with distinct distribution patterns. The evaluation of diurnal traffic data provides good explanations for the vertical and horizontal differences in CO2-distribution inside the canyon. Diurnal flux characteristics at the top of the canyon can almost solely be explained with traffic density expressed by the strong linear dependence. Even the diurnal course of the flux at 39 m shows a remarkable relationship to traffic density for east wind conditions while, for west wind situations, a change toward source areas with lower emissions leads to a reduced flux.

Photochemical Oxidation of Dissolved Elemental Mercury by Carbonate Radicals in Water

DOE PAGES

He, Feng; Zhao, Weirong; Liang, Liyuan; ...

2014-11-11

Photochemical oxidation of dissolved elemental mercury [Hg(0)] affects mercury chemical speciation and its transfer at the water-air interface in the aquatic environment. The mechanisms and factors that control Hg(0) photooxidation, however, are not completely understood, especially in natural freshwaters containing dissolved organic matter (DOM) and carbonate. Here, we evaluate Hg(0) photooxidation rates affected by various reactive ionic species [e.g., DOM, CO 3 2-, NO 3 -] and free radicals in a creek water and a phosphate buffer solution (pH=8) under simulated solar irradiation. We report a high Hg(0) photooxidation rate (k = 1.44 h -1) in the presence of bothmore » HCO 3 2- and NO 3 -, whereas HCO 3 2-, NO 3 -, or DOM alone increased the oxidation rate slightly (k = 0.1 0.17 h -1). Using scavengers and enhancers for singlet oxygen ( 1O 2) and hydroxyl (HO ∙ ) radicals, as well as electron paramagnetic resonance spectroscopy, we identify that carbonate radicals (CO 3 ∙-) primarily drive the Hg(0) photooxidation, whereas addition of DOM resulted in a 2-fold decrease in Hg(0) oxidation. This study identifies an unrecognized pathway of Hg(0) photooxidation by CO 3 ∙- radicals and the inhibitory effect of DOM, which could be important in assessing Hg transformation and fate in water containing carbonate such as hard water and seawater.« less

Application and evaluation of scale dissolver treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fielder, G.D.

1994-12-31

In order to provide an improved basis for the design of barium sulfate scale dissolver treatments both laboratory testing and monitoring of field applications were carried out. The deleterious effects of mixing produced water with dissolver prior to contacting scale are shown. Increasing total dissolved solids (TDS) levels can reduce dissolution depending upon temperature. Precomplexation with divalent cations reduces the capacity of the dissolver to solubilize solid scales. Magnesium may adversely affect dissolver performance at elevated temperatures. Several oil and gas wells were closely monitored during initial flowback after treatment. Samples were collected on a frequent basis and analyzed formore » pH, dissolver content, chlorides and various cations. The resulting data were used to construct flowback profiles for evaluation of the treatments. Evidence of scale dissolution is presented. The presence of an incompatible flush brine was discovered in one case and possible reverse order of addition of preflush and dissolver in another. The importance of establishing and following treatment procedures is briefly discussed.« less

Geologic framework of thermal springs, Black Canyon, Nevada and Arizona

USGS Publications Warehouse

Beard, L. Sue; Anderson, Zachary W.; Felger, Tracey J.; Seixas, Gustav B.

2014-01-01

Thermal springs in Black Canyon of the Colorado River, downstream of Hoover Dam, are important recreational, ecological, and scenic features of the Lake Mead National Recreation Area. This report presents the results from a U.S. Geological Survey study of the geologic framework of the springs. The study was conducted in cooperation with the National Park Service and funded by both the National Park Service and National Cooperative Geologic Mapping Program of the U.S. Geological Survey. The report has two parts: A, a 1:48,000-scale geologic map created from existing geologic maps and augmented by new geologic mapping and geochronology; and B, an interpretive report that presents results based on a collection of fault kinematic data near springs within Black Canyon and construction of 1:100,000-scale geologic cross sections that extend across the western Lake Mead region. Exposures in Black Canyon are mostly of Miocene volcanic rocks, underlain by crystalline basement composed of Miocene plutonic rocks or Proterozoic metamorphic rocks. The rocks are variably tilted and highly faulted. Faults strike northwest to northeast and include normal and strike-slip faults. Spring discharge occurs along faults intruded by dacite dikes and plugs; weeping walls and seeps extend away from the faults in highly fractured rock or relatively porous volcanic breccias, or both. Results of kinematic analysis of fault data collected along tributaries to the Colorado River indicate two episodes of deformation, consistent with earlier studies. The earlier episode formed during east-northeast-directed extension, and the later during east-southeast-directed extension. At the northern end of the study area, pre-existing fault blocks that formed during the first episode were rotated counterclockwise along the left-lateral Lake Mead Fault System. The resulting fault pattern forms a complex arrangement that provides both barriers and pathways for groundwater movement within and around Black

Investigation of phase stability of poly(1-oxotrimethylene)-dissolved aqueous solutions containing ZnCl2/CaCl2/LiCl: Influence of boric acid introduction and aging time

NASA Astrophysics Data System (ADS)

Chae, Dong Wook; Jang, Han Beol; Kim, Byoung Chul

2018-02-01

Poly(1-oxotrimethylene) (POTM) was dissolved in aqueous solutions containing ZnCl2, CaCl2, and LiCl, and the effects of boric acid introduction on the phase stability of the POTM solutions over various aging times were investigated. In the absence of boric acid, aging at 70°C for 8 h notably reduced the loss tangent (tanδ) for the 7.0 wt.% POTM solutions. Addition of boric acid into unaged solutions had little effect on tanδ over the frequency range measured, regardless of its content, whereas addition of 0.3-1.0 wt.% of boric acid into aged solutions increased tanδ. The dynamic viscosity of the POTM solutions with 1.0 wt.% boric acid was affected little by aging time. Conversely, the POTM solutions without boric acid exhibited increased dynamic viscosity in the low-frequency range with aging time. In addition, the slope of the solutions in the Cole-Cole plot decreased with increasing aging time in the absence of boric acid, whereas aging time had little effect in the presence of 1.0 wt.% boric acid. For dilute POTM solutions ( i.e., 0.5 g/dL), the reduced viscosity decreased with increasing aging time in the absence of boric acid, while it was affected little in solutions with the addition of 1.0 wt.% boric acid. In the UV-Vis spectra, the aging-time-dependent increase of the absorbance peak at 390 nm was associated with the generation of a chromophoric complex in the POTM solutions. Conversely, the disappearance of the peak due to the addition of boric acid indicated suppression of complex formation.

Structures of Cu surfaces developing in benzotriazole solutions: Effect of pH

NASA Astrophysics Data System (ADS)

Kondoh, Eiichi; Kawakami, Tatsuya; Watanabe, Mitsuhiro; Jin, Linhua; Hamada, Satomi; Shima, Shohei; Hiyama, Hirokuni

2017-07-01

The effect of pH on layer formation onto clean Cu surfaces in benzotriazole (BTA) aqueous solutions was studied by in situ spectroscopic ellipsometry. The effect of H2O2 addition was also investigated. Time changes in the ellipsometric parameters Ψ and Δ, which correspond to the structural changes of the layers on Cu, were discussed. In acidic solutions, a BTA or a Cu-BTA complex layer grows directly on Cu. The out-diffusion of Cu is suppressed at the Cu layer interface. When H2O2 was mixed, the Cu surface is eroded in acidic solutions. In alkaline solutions, the BTA layer grows on the oxidized Cu layer, or no growth occurs, depending on the composition of the solutions. In neutral solutions, the Cu-BTA complex layer forms on Cu, and the uncovered part is oxidized in the presence of H2O2.

Standardized methods for Grand Canyon fisheries research 2015

USGS Publications Warehouse

Persons, William R.; Ward, David L.; Avery, Luke A.

2013-01-01

This document presents protocols and guidelines to persons sampling fishes in the Grand Canyon, to help ensure consistency in fish handling, fish tagging, and data collection among different projects and organizations. Most such research and monitoring projects are conducted under the general umbrella of the Glen Canyon Dam Adaptive Management Program and include studies by the U.S. Geological Survey (USGS), U.S. Fish and Wildlife Service (FWS), National Park Service (NPS), the Arizona Game and Fish Department (AGFD), various universities, and private contractors. This document is intended to provide guidance to fieldworkers regarding protocols that may vary from year to year depending on specific projects and objectives. We also provide herein documentation of standard methods used in the Grand Canyon that can be cited in scientific publications, as well as a summary of changes in protocols since the document was first created in 2002.

75 FR 34476 - Glen Canyon Dam Adaptive Management Work Group

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-17

... DEPARTMENT OF THE INTERIOR Bureau of Reclamation Glen Canyon Dam Adaptive Management Work Group... Management Work Group. The purpose of the Adaptive Management Work Group is to advise and to provide... of the Glen Canyon Dam Adaptive Management Work Group is in the public interest in connection with...

Refraction tomography mapping of near-surface dipping layers using landstreamer data at East Canyon Dam, Utah

USGS Publications Warehouse

Ivanov, J.; Miller, R.D.; Markiewicz, R.D.; Xia, J.

2008-01-01

We apply the P-wave refraction-tomography method to seismic data collected with a landstreamer. Refraction-tomography inversion solutions were determined using regularization parameters that provided the most realistic near-surface solutions that best matched the dipping layer structure of nearby outcrops. A reasonably well matched solution was obtained using an unusual set of optimal regularization parameters. In comparison, the use of conventional regularization parameters did not provide as realistic results. Thus, we consider that even if there is only qualitative a-priori information about a site (i.e., visual) - in the case of the East Canyon Dam, Utah - it might be possible to minimize the refraction nonuniqueness by estimating the most appropriate regularization parameters.

Influence of a dam on fine-sediment storage in a canyon river

USGS Publications Warehouse

Hazel, J.E.; Topping, D.J.; Schmidt, J.C.; Kaplinski, M.

2006-01-01

Glen Canyon Dam has caused a fundamental change in the distribution of fine sediment storage in the 99-km reach of the Colorado River in Marble Canyon, Grand Canyon National Park, Arizona. The two major storage sites for fine sediment (i.e., sand and finer material) in this canyon river are lateral recirculation eddies and the main-channel bed. We use a combination of methods, including direct measurement of sediment storage change, measurements of sediment flux, and comparison of the grain size of sediment found in different storage sites relative to the supply and that in transport, in order to evaluate the change in both the volume and location of sediment storage. The analysis shows that the bed of the main channel was an important storage environment for fine sediment in the predam era. In years of large seasonal accumulation, approximately 50% of the fine sediment supplied to the reach from upstream sources was stored on the main-channel bed. In contrast, sediment budgets constructed for two short-duration, high experimental releases from Glen Canyon Dam indicate that approximately 90% of the sediment discharge from the reach during each release was derived from eddy storage, rather than from sandy deposits on the main-channel bed. These results indicate that the majority of the fine sediment in Marble Canyon is now stored in eddies, even though they occupy a small percentage (???17%) of the total river area. Because of a 95% reduction in the supply of fine sediment to Marble Canyon, future high releases without significant input of tributary sediment will potentially erode sediment from long-term eddy storage, resulting in continued degradation in Marble Canyon. Copyright 2006 by the American Geophysical Union.

Normal and anomalous nuclear spin-lattice relaxation at high temperatures in Sc-H(D), Y-H, and Lu-H solid solutions

NASA Astrophysics Data System (ADS)

Barnes, R. G.; Han, J.-W.; Torgeson, D. R.; Baker, D. B.; Conradi, M. S.; Norberg, R. E.

1995-02-01

We report the results of measurements of the proton (1H) spin-lattice relaxation rate R1 at high temperatures (to ~1400 K) in the hcp (α) solid-solution phases of the Sc-H, Y-H, and Lu-H systems, and of R1(45Sc) in Sc-H and Sc-D solid solutions. The latter measurements show unambiguous evidence of an anomalous increase at ~1000 K, whereas R1(1H) shows no such increase at any temperature. This behavior of R1(1H) contrasts with that in the bcc V-H, etc., solid solutions where anomalous relaxation occurs below ~1000 K, and in all investigated metal dihydride phases, MH2-x. The anomalous R1(1H) behavior in α-VHx, α-NbHx, etc., may be understood in terms of fast spin relaxation in the H2 gas in equilibrium with the solid, mediated by fast gas-solid exchange of hydrogen. However, in the present systems, α-ScHx, α-YHx, etc., the H2 gas pressure in equilibrium with the hcp systems is extremely low, resulting in negligible H2 concentration in the gas phase, and consequently a negligible contribution to R1(1H). In contrast, some of the present measurements indicate that the R1(45Sc) anomaly does result from the hydrogen content of the metal, but the mechanism remains unexplained.

Martian canyons and African rifts: Structural comparisons and implications

NASA Technical Reports Server (NTRS)

Frey, H. V.

1978-01-01

The resistant parts of the canyon walls of the Martian rift complex Valled Marineris were used to infer an earlier, less eroded reconstruction of the major roughs. The individual canyons were then compared with individual rifts of East Africa. When measured in units of planetary radius, Martian canyons show a distribution of lengths nearly identical to those in Africa, both for individual rifts and for compound rift systems. A common mechanism which scales with planetary radius is suggested. Martian canyons are significantly wider than African rifts. The overall pattern of the rift systems of Africa and Mars are quite different in that the African systems are composed of numerous small faults with highly variable trend. On Mars the trends are less variable; individual scarps are straighter for longer than on earth. This is probably due to the difference in tectonic histories of the two planets: the complex history of the earth and the resulting complicated basement structures influence the development of new rifts. The basement and lithosphere of Mars are inferred to be simple, reflecting a relatively inactive tectonic history prior to the formation of the canyonlands.

Searching for Clues to the Processes and Conditions of Past Martian Environments: The Roles of Episodic Solutions, Analog Sites and Fe-O(-H) Phases

NASA Astrophysics Data System (ADS)

King, P. L.; De Deckker, P.

2012-12-01

On Mars, limited solutions (water/brine) were likely present episodically. Gradients in solution abundance may have caused salt precipitation and re-solution, brine reflux, pH gradients, and cycling of anions and cations; we provide an example of such processes in a playa lake. We propose that on Mars, the limited, episodic solutions, pH and abundant Fe-O(-H) phases are significant factors in salt precipitation and in promoting adsorption/desorption of anions and cations. FACTORS LEADING TO EPISODIC SOLUTIONS: Episodic movement of solutions may be driven by punctuated processes that 1) remove surface materials (e.g., impact and sedimentary mass wasting and deflation); 2) add surface materials (e.g., impact, volcanic and sedimentary processes); and 3) increase temperature and/or decrease atmospheric pressure (e.g., seasons, diurnal cycles, variation in obliquity). Removal and addition of surface materials results in topographic gradients that change pressure gradients of any potential groundwater, films, or buried ground ice. For example, episodic fluid flow and salt precipitation/re-solution may occur at topographic discontinuities like craters/basins, channel walls, mounds and dunes. Such areas provide the opportunity to sample multiple fluid sources (with different pH, Eh and total dissolved solids, TDS) and they may be the foci of subsurface solution flow and surface transport. EARTH ANALOG: Interplay of the three processes above is seen in Lake Tyrrell (playa), western Victoria, Australia (McCumber, P, 1991 http://vro.dpi.vic.gov.au). During wetter periods, springs from the regional groundwater (low pH, oxidized, mod-high TDS) mix with lake waters and saline 'reflux' brines (mod. pH, reduced, high TDS) at the lake edge at the base of higher ground. The Br/Cl of the reflux brines indicates mineral re-solution. Gypsum and Fe-O(-H) phases precipitate near the lake edge. During hot, dry climate episodes the lake precipitates gypsum and carbonate, efflorescent salts

Evolution of Spatial pH Distribution in Aqueous Solution induced by Atmospheric Pressure Plasma

NASA Astrophysics Data System (ADS)

Takahashi, Shigenori; Mano, Kakeru; Hayashi, Yui; Takada, Noriharu; Kanda, Hideki; Goto, Motonobu

2016-09-01

Discharge plasma at gas-liquid interface produces some active species, and then they affect chemical reactions in aqueous solution, where pH of aqueous solution is changed due to redox species. The pH change of aqueous solution is an important factor for chemical reactions. However, spatial pH distribution in a reactor during the discharge has not been clarified yet. Thus, this work focused on spatial pH distribution of aqueous solution when pulsed discharge plasma was generated from a copper electrode in gas phase to aqueous solution in a reactor. Experiments were conducted using positive unipolar pulsed power. The unipolar pulsed voltage at +8.0 kV was applied to the copper electrode and the bottom of the reactor was grounded. The size of the reactor was 80 mm wide, 10 mm deep, and 40 mm high. The electrode was set at distance of 2 mm from the solution surface. Anthocyanins were contained in the aqueous solution as a pH indicator. The change pH solution spread horizontally, and low pH region of 10 mm in depth was formed. After discharge for 10 minutes, the low pH region was diffused toward the bottom of the reactor. After discharge for 60 minutes, the pH of the whole solution decreased.

Are amphitheater headed canyons indicative of a particular formative process?

NASA Astrophysics Data System (ADS)

Ryan, A. J.; Whipple, K. X.; Johnson, J. P.

2012-12-01

Tributary canyons with amphitheater-shaped heads have previously been interpreted as evidence for groundwater seepage erosion, particularly in environments where fluvial processes are assumed to be negligible. However, some have questioned whether this canyon morphology is truly diagnostic of a particular formative process. We seek to determine the relative roles of fluvial and groundwater-related processes and the strength of stratigraphic control on the Colorado Plateau through a combination of fieldwork and GIS analysis. Amphitheater valleys may have overhanging or steep-sided headwalls with a semicircular plan-view pattern. It is reasonable to assume that this form is a result of focused erosion at the base of the headwall (i.e. sapping). Two frequently cited agents may lead to undermining: plunge-pool scour at the base of waterfalls and seepage induced weathering and erosion where the groundwater table intersects the land surface. Both processes are enhanced where weaker, less permeable layers underlie stronger cap rock. We conducted preliminary fieldwork in two locations on the Colorado Plateau, where there are many classic examples of amphitheater headed canyons. The Escalante River landscape is highly variable with a range of canyon and valley-head forms, many of which cut through the thick Navajo Sandstone into the underlying shale and sand of the Kayenta Formation. Northeast of Escalante National Monument, at the base of the Henry Mountains, is Tarantula Mesa. The canyons there are also considerably variable, with nearly all containing at least one abrupt amphitheater knickpoint at the valley head or farther downstream. Our observations are presented here with an analysis of the canyon profiles, surrounding topography, and potential structural controls. We have found that nearly all amphitheaters in both locales show signs of groundwater seepage weathering and plausibly seepage erosion. However, many also contain plunge pools and evidence of substantial

Effects of building roof greening on air quality in street canyons

NASA Astrophysics Data System (ADS)

Baik, Jong-Jin; Kwak, Kyung-Hwan; Park, Seung-Bu; Ryu, Young-Hee

2012-12-01

Building roof greening is a successful strategy for improving urban thermal environment. It is of theoretical interest and practical importance to study the effects of building roof greening on urban air quality in a systematic and quantitative way. In this study, we examine the effects of building roof greening on air quality in street canyons using a computational fluid dynamics (CFD) model that includes the thermodynamic energy equation and the transport equation of passive, non-reactive pollutants. For simplicity, building roof greening is represented by specified cooling. Results for a simple building configuration with a street canyon aspect ratio of one show that the cool air produced due to building roof greening flows into the street canyon, giving rise to strengthened street canyon flow. The strengthened street canyon flow enhances pollutant dispersion near the road, which decreases pollutant concentration there. Thus, building roof greening improves air quality near the road. The degree of air quality improvement near the road increases as the cooling intensity increases. In the middle region of the street canyon, the air quality can worsen when the cooling intensity is not too strong. Results for a real urban morphology also show that building roof greening improves air quality near roads. The degree of air quality improvement near roads due to building roof greening depends on the ambient wind direction. These findings provide a theoretical foundation for constructing green roofs for the purpose of improving air quality near roads or at a pedestrian level as well as urban thermal environment. Further studies using a CFD model coupled with a photochemistry model and a surface energy balance model are required to evaluate the effects of building roof greening on air quality in street canyons in a more realistic framework.

Bedrock Canyons Carved by the Largest Known Floods on Earth and Mars

NASA Astrophysics Data System (ADS)

Lamb, M. P.; Lapôtre, M. G. A.; Larsen, I. J.; Williams, R. M. E.

2017-12-01

The surface of Earth is a dynamic and permeable interface where the rocky crust is sculpted by ice, wind and water resulting in spectacular mountain ranges, vast depositional basins and environments that support life. These landforms and deposits contain a rich, yet incomplete, record of Earth history that we are just beginning to understand. Some of the most dramatic landforms are the huge bedrock canyons carved by catastrophic floods. On Mars, similar bedrock canyons, known as Outflow Channels, are the most important indicators of large volumes of surface water in the past. Despite their importance and now decades of observations of canyon morphology, we lack a basic understanding of how the canyons formed, which limits our ability to reconstruct flood discharge, duration and water volume. In this presentation I will summarize recent work - using mechanistic numerical models and field observations - that suggests that bedrock canyons carved by megafloods rapidly evolve to a size and shape such that boundary shear stresses just exceed that required to entrain fractured blocks of rock. The threshold shear stress constraint allows for quantitative reconstruction of the largest known floods on Earth and Mars, and implies far smaller discharges than previous methods that assume flood waters fully filled the canyons to high water marks.

The influence of dissolved H2O content in supercritical carbon dioxide to the inclusion complexes formation of ketoprofen/β-cyclodextrin

NASA Astrophysics Data System (ADS)

Goenawan, Joshua; Trisanti, P. N.; Sumarno

2015-12-01

This work studies the relation between dissolved H2O content in supercritical carbon dioxide (SC-CO2) with the formation of ketoprofen (KP)/β-cyclodextrin(CD) inclusion complexes. The process involves a physical mixture of these two compounds into contact with the supercritical carbon dioxide which had been previously saturated with H2O over a certain duration. The pressure used for saturation process is 130 bar and saturation temperature was ranged between 30 °C to 50 °C. The inclusion process was achieved by keeping it for 2 hours at 160 bar and 200 bar with inclusion temperature of 50 °C. The results enable us to suggest explanations for the inclusion formation. The inclusion complexes can be formed by contacting the dissolved H2O in SC-CO2 to the physical mixture of KP and CD. An increase in the temperature of saturation process resulted in an increase of dissolved H2O content in the supercritical carbon dioxide. The increasing levels of this water soluble resulted an increase in the inclusion complexes that has been formed. The formation of inclusion complexes includes the water molecules enhancing the emptying of the CD cavities and being replaced by KP, towards a more stable energy state. The drug release used for analyzing the dissolution rate of the KP/CD complexes. The results vary from 79,85% to 99,98% after 45 minutes which is above the rate that has been assigned by Farmakope Indonesia at 70% dissolution rate for KP. The use of SC-CO2 offers a new methods for increasing the rate of dissolution of drugs that are hydrophobic such as KP. CO2 used as a supercritical fluid because of its relatively low cost, easily obtainable supercritical conditions, and lack of toxicity. The material samples were characterized by DSC and Spectrophotometer UV-vis technique.

3D View of Grand Canyon, Arizona

NASA Technical Reports Server (NTRS)

2000-01-01

The Grand Canyon is one of North America's most spectacular geologic features. Carved primarily by the Colorado River over the past six million years, the canyon sports vertical drops of 5,000 feet and spans a 445-kilometer-long stretch of Arizona desert. The strata along the steep walls of the canyon form a record of geologic time from the Paleozoic Era (250 million years ago) to the Precambrian (1.7 billion years ago).

The above view was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument aboard the Terra spacecraft. Visible and near infrared data were combined to form an image that simulates the natural colors of water and vegetation. Rock colors, however, are not accurate. The image data were combined with elevation data to produce this perspective view, with no vertical exaggeration, looking from above the South Rim up Bright Angel Canyon towards the North Rim. The light lines on the plateau at lower right are the roads around the Canyon View Information Plaza. The Bright Angel Trail, which reaches the Colorado in 11.3 kilometers, can be seen dropping into the canyon over Plateau Point at bottom center. The blue and black areas on the North Rim indicate a forest fire that was smoldering as the data were acquired on May 12, 2000.

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land

Solvent wash solution

DOEpatents

Neace, J.C.

1984-03-13

A process is claimed for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 vol % of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.

Solvent wash solution

DOEpatents

Neace, James C.

1986-01-01

Process for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 volume percent of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.

Effect of stable stratification on dispersion within urban street canyons: A large-eddy simulation

NASA Astrophysics Data System (ADS)

Li, Xian-Xiang; Britter, Rex; Norford, Leslie K.

2016-11-01

This study employs a validated large-eddy simulation (LES) code with high tempo-spatial resolution to investigate the effect of a stably stratified roughness sublayer (RSL) on scalar transport within an urban street canyon. The major effect of stable stratification on the flow and turbulence inside the street canyon is that the flow slows down in both streamwise and vertical directions, a stagnant area near the street level emerges, and the vertical transport of momentum is weakened. Consequently, the transfer of heat between the street canyon and overlying atmosphere also gets weaker. The pollutant emitted from the street level 'pools' within the lower street canyon, and more pollutant accumulates within the street canyon with increasing stability. Under stable stratification, the dominant mechanism for pollutant transport within the street canyon has changed from ejections (flow carries high-concentration pollutant upward) to unorganized motions (flow carries high-concentration pollutant downward), which is responsible for the much lower dispersion efficiency under stable stratifications.

When Organic-Rich Turbidites Reach 5000 m: "Cold-Seep Like" Life in the Congo Deep-Sea Fan

NASA Astrophysics Data System (ADS)

Pastor, L.; Toffin, L.; Cathalot, C.; Olu, K.; Brandily, C.; Bessette, S.; Lesongeur, F.; Godfroy, A.; Khripounoff, A.; Decker, C.; Taillefert, M.; Rabouille, C.

2016-12-01

The Congo canyon, located on the west coast of Africa, is a unique example of a canyon directly connected to a major river (The Congo River). Turbidites are responsible for a large input of terrestrial organic matter at depths up to 5000 m. These high inputs led to global high organic matter mineralization rates, with very localized hot spots that were visually observed and specifically sampled with a ROV. These hot spots, featuring substantial concentration of reduced compounds, mainly methane and sulfides, were recognizable in surface by the presence of reduced sediment patches, bacterial mats, and/or vesicomyid bivalves that host bacterial endosymbionts able to process H2S. In this paper we present geochemical sediment profiles of sulfate, methane, sulfide and dissolved iron together with phylogenetic diversity of 16S rRNA communities. This will give a first understanding of biogeochemical processes occurring in this peculiar ecosystem, mainly sulfate reduction, methanogenesis and subsequent anaerobic oxidation of methane with bacterial and archaeal assemblages similar to cold seeps environments. Iron also seems to play a major role in this system and iron/sulfur interactions as a sink for H2S can probably compete with H2S consumption by chemosynthetic bivalves, estimated at one site by vesicomyds gills incubations in a sulfide-rich solution.

Photochemical Reactivity of Dissolved Organic Matter in Boreal Lakes

NASA Astrophysics Data System (ADS)

Gu, Y.; Vuorio, K.; Tiirola, M.; Perämäki, S.; Vahatalo, A.

2016-12-01

Boreal lakes are rich in dissolved organic matter (DOM) that terrestrially derived from forest soil and wetland, yet little is known about potential for photochemical transformation of aquatic DOM in boreal lakes. Transformation of chromophoric dissolved organic matter (CDOM) can decrease water color and enhance microbial mineralization, affecting primary production and respiration, which both affect the CO2 balance of the lakes. We used laboratory solar radiation exposure experiments with lake water samples collected from 54 lakes located in Finland and Sweden, representing different catchment composition and watershed location to assess photochemical reactivity of DOM. The pH of water samples ranged from 5.4 to 8.3, and the concentrations of dissolved iron (Fe) were between < 0.06 and 22 μmol L-1. The filtered water samples received simulated solar radiation corresponding to a daily dose of sunlight, and photomineralization of dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) was measured for determination of spectral apparent quantum yields (AQY). During irradiation, photobleaching decreased the absorption coefficients of CDOM at 330 nm between 4.9 and 79 m-1 by 0.5 to 11 m-1. Irradiation generated DIC from 2.8 to 79 μmol C L-1. The AQY at 330 nm ranged between 31 and 273 ×10-6 mol C mol photons-1 h-1, which was correlated positively with concentration of dissolved Fe, and negatively with pH. Further statistical analyze indicated that the interaction between pH and Fe may explain much of the photochemical reactivity of DOM in the examined lakes, and land cover concerns main catchment areas also can have impact on the photoreaction process. This study may suggest how environmental conditions regulate DOM photomineralization in boreal lakes.

Identification of Mercury and Dissolved Organic Matter Complexes Using Ultrahigh Resolution Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Hongmei; Johnston, Ryne C.; Mann, Benjamin F.

The chemical speciation and bioavailability of mercury (Hg) is markedly influenced by its complexation with naturally dissolved organic matter (DOM) in aquatic environments. To date, however, analytical methodologies capable of identifying such complexes are scarce. Here in this paper, we utilize ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) coupled with electrospray ionization to identify individual Hg–DOM complexes. The measurements were performed by direct infusion of DOM in a 1:1 methanol:water solution at a Hg to dissolved organic carbon (DOC) molar ratio of 3 × 10 –4. Heteroatomic molecules, especially those containing multiple S and N atoms, weremore » found to be among the most important in forming strong complexes with Hg. Major Hg–DOM complexes of C 10H 21N 2S 4Hg + and C 8H 17N 2S 4Hg + were identified based on both the exact molecular mass and patterns of Hg stable isotope distributions detected by FTICR-MS. Density functional theory was used to predict the solution-phase structures of candidate molecules. Finally, these findings represent the first step to unambiguously identify specific DOM molecules in Hg binding, although future studies are warranted to further optimize and validate the methodology so as to explore detailed molecular compositions and structures of Hg–DOM complexes that affect biological uptake and transformation of Hg in the environment.« less

Identification of Mercury and Dissolved Organic Matter Complexes Using Ultrahigh Resolution Mass Spectrometry

DOE PAGES

Chen, Hongmei; Johnston, Ryne C.; Mann, Benjamin F.; ...

2016-12-22

The chemical speciation and bioavailability of mercury (Hg) is markedly influenced by its complexation with naturally dissolved organic matter (DOM) in aquatic environments. To date, however, analytical methodologies capable of identifying such complexes are scarce. Here in this paper, we utilize ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) coupled with electrospray ionization to identify individual Hg–DOM complexes. The measurements were performed by direct infusion of DOM in a 1:1 methanol:water solution at a Hg to dissolved organic carbon (DOC) molar ratio of 3 × 10 –4. Heteroatomic molecules, especially those containing multiple S and N atoms, weremore » found to be among the most important in forming strong complexes with Hg. Major Hg–DOM complexes of C 10H 21N 2S 4Hg + and C 8H 17N 2S 4Hg + were identified based on both the exact molecular mass and patterns of Hg stable isotope distributions detected by FTICR-MS. Density functional theory was used to predict the solution-phase structures of candidate molecules. Finally, these findings represent the first step to unambiguously identify specific DOM molecules in Hg binding, although future studies are warranted to further optimize and validate the methodology so as to explore detailed molecular compositions and structures of Hg–DOM complexes that affect biological uptake and transformation of Hg in the environment.« less

Assessment of dissolved-solids loading to the Colorado River in the Paradox Basin between the Dolores River and Gypsum Canyon, Utah

USGS Publications Warehouse

Shope, Christopher L.; Gerner, Steven J.

2014-01-01

Salinity loads throughout the Colorado River Basin have been a concern over recent decades due to adverse impacts on population, natural resources, and regional economics. With substantial financial resources and various reclamation projects, the salt loading to Lake Powell and associated total dissolved-solids concentrations in the Lower Colorado River Basin have been substantially reduced. The Colorado River between its confluence with the Dolores River and Lake Powell traverses a physiographic area where saline sedimentary formations and evaporite deposits are prevalent. However, the dissolved-solids loading in this area is poorly understood due to the paucity of water-quality data. From 2003 to 2011, the U.S. Geological Survey in cooperation with the U.S. Bureau of Reclamation conducted four synoptic sampling events to quantify the salinity loading throughout the study reach and evaluate the occurrence and impacts of both natural and anthropogenic sources. The results from this study indicate that under late-summer base-flow conditions, dissolved-solids loading in the reach is negligible with the exception of the Green River, and that variations in calculated loads between synoptic sampling events are within measurement and analytical uncertainties. The Green River contributed approximately 22 percent of the Colorado River dissolved-solids load, based on samples collected at the lower end of the study reach. These conclusions are supported by water-quality analyses for chloride and bromide, and the results of analyses for the stable isotopes of oxygen and deuterium. Overall, no significant sources of dissolved-solids loading from tributaries or directly by groundwater discharge, with the exception of the Green River, were identified in the study area.

Turbid releases from Glen Canyon Dam, Arizona, following rainfall-runoff events of September 2013

USGS Publications Warehouse

Wildman, Richard A.; Vernieu, William

2017-01-01

Glen Canyon Dam is a large dam on the Colorado River in Arizona. In September 2013, it released turbid water following intense thunderstorms in the surrounding area. Turbidity was >15 nephelometric turbidity units (NTU) for multiple days and >30 NTU at its peak. These unprecedented turbid releases impaired downstream fishing activity and motivated a rapid-response field excursion. At 5 locations upstream from the dam, temperature, specific conductance, dissolved oxygen, chlorophyll a, and turbidity were measured in vertical profiles. Local streamflow and rainfall records were retrieved, and turbidity and specific conductance data in dam releases were evaluated. Profiling was conducted to determine possible sources of turbidity from 3 tributaries nearest the dam, Navajo, Antelope, and Wahweap creeks, which entered Lake Powell as interflows during this study. We discuss 4 key conditions that must have been met for tributaries to influence turbidity of dam releases: tributary flows must have reached the dam, tributary flows must have been laden with sediment, inflow currents must have been near the depth of dam withdrawals, and the settling velocity of particles must have been slow. We isolate 2 key uncertainties that reservoir managers should resolve in future similar studies: the reach of tributary water into the reservoir thalweg and the distribution of particle size of suspended sediment. These uncertainties leave the source of the turbidity ambiguous, although an important role for Wahweap Creek is possible. The unique combination of limnological factors we describe implies that turbid releases at Glen Canyon Dam will continue to be rare.

Fourmile Canyon Fire Findings

Treesearch

Russell Graham; Mark Finney; Chuck McHugh; Jack Cohen; Dave Calkin; Rick Stratton; Larry Bradshaw; Ned Nikolov

2012-01-01

The Fourmile Canyon Fire burned in the fall of 2010 in the Rocky Mountain Front Range adjacent to Boulder, Colorado. The fire occurred in steep, rugged terrain, primarily on privately owned mixed ponderosa pine and Douglas-fir forests. The fire started on September 6 when the humidity of the air was very dry (¡Ö

Method for separating contaminants from solution employing an organic-stabilized metal-hydroxy gel

DOEpatents

Alexander, Donald H.

1996-01-01

Metals and organics are extracted from solution by co-precipitating them with a gel comprising aluminum hydroxide and a complexing agent such as EDTA. After the gel is processed to remove the metals and organics, it can be recycled for further use by dissolving it in a high-pH solution, leaving no secondary waste stream. A number of alternative complexing agents perform better than EDTA.

78 FR 21415 - Glen Canyon Dam Adaptive Management Work Group

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-10

...: The Glen Canyon Dam Adaptive Management Program (AMP) was implemented as a result of the Record of... consultation requirements of the Grand Canyon Protection Act (Pub. L. 102-575) of 1992. The AMP includes a.../amp/amwg/mtgs/13may08/index.html . Time will be allowed for any individual or organization wishing to...

Comprehensive Evaluation of Fast-Response, Reynolds-Averaged Navier-Stokes, and Large-Eddy Simulation Methods Against High-Spatial-Resolution Wind-Tunnel Data in Step-Down Street Canyons

NASA Astrophysics Data System (ADS)

Hayati, Arash Nemati; Stoll, Rob; Kim, J. J.; Harman, Todd; Nelson, Matthew A.; Brown, Michael J.; Pardyjak, Eric R.

2017-08-01

Three computational fluid dynamics (CFD) methods with different levels of flow-physics modelling are comprehensively evaluated against high-spatial-resolution wind-tunnel velocity data from step-down street canyons (i.e., a short building downwind of a tall building). The first method is a semi-empirical fast-response approach using the Quick Urban Industrial Complex (QUIC-URB) model. The second method solves the Reynolds-averaged Navier-Stokes (RANS) equations, and the third one utilizes a fully-coupled fluid-structure interaction large-eddy simulation (LES) model with a grid-turbulence inflow generator. Unlike typical point-by-point evaluation comparisons, here the entire two-dimensional wind-tunnel dataset is used to evaluate the dynamics of dominant flow topological features in the street canyon. Each CFD method is scrutinized for several geometric configurations by varying the downwind-to-upwind building-height ratio (H_d/H_u) and street canyon-width to building-width aspect ratio ( S / W) for inflow winds perpendicular to the upwind building front face. Disparities between the numerical results and experimental data are quantified in terms of their ability to capture flow topological features for different geometric configurations. Overall, all three methods qualitatively predict the primary flow topological features, including a saddle point and a primary vortex. However, the secondary flow topological features, namely an in-canyon separation point and secondary vortices, are only well represented by the LES method despite its failure for taller downwind building cases. Misrepresentation of flow-regime transitions, exaggeration of the coherence of recirculation zones and wake fields, and overestimation of downwards vertical velocity into the canyon are the main defects in QUIC-URB, RANS and LES results, respectively. All three methods underestimate the updrafts and, surprisingly, QUIC-URB outperforms RANS for the streamwise velocity component, while RANS is

Photogeneration of H2O2 in SPEEK/PVA aqueous polymer solutions.

PubMed

Little, Brian K; Lockhart, PaviElle; Slaten, B L; Mills, G

2013-05-23

Photolysis of air-saturated aqueous solutions containing sulphonated poly(ether etherketone) and poly(vinyl alcohol) results in the generation of hydrogen peroxide. Consumption of oxygen and H2O2 formation are initially concurrent processes with a quantum yield of peroxide generation of 0.02 in stirred or unstirred solutions within the range of 7 ≤ pH ≤ 9. The results are rationalized in terms of O2 reduction by photogenerated α-hydroxy radicals of the polymeric ketone in competition with radical-radical processes that consume the macromolecular reducing agents. Generation of H2O2 is controlled by the photochemical transformation that produces the polymer radicals, which is most efficient in neutral and slightly alkaline solutions. Quenching of the excited state of the polyketone by both H3O(+) and OH(-) affect the yields of the reducing macromolecular radicals and of H2O2. Deprotonation of the α-hydroxy polymeric radicals at pH > 9 accelerate their decay and contribute to suppressing the peroxide yields in basic solutions. Maxima in [H2O2] are observed when illuminations are performed with static systems, where O2 reduction is faster than diffusion of oxygen into the solutions. Under such conditions H2O2 can compete with O2 for the reducing radicals resulting in a consumption of the peroxide.

Geologic setting and genesis of the Mule Canyon low-sulfidation epithermal gold-silver deposit, north-central Nevada

USGS Publications Warehouse

John, D.A.; Hofstra, A.H.; Fleck, R.J.; Brummer, J.E.; Saderholm, E.C.

2003-01-01

/or marcasite veins. Ore minerals consist mostly of electrum and Ag sulfide and selenide minerals, with minor to major amounts of pyrite, marcasite, and arsenopyrite, and local stibnite. Both types of ores have similar geochemical signatures, characterized by high Au, Ag, As, Sb, and Se contents, locally high Hg, Mo, Tl, and W contents, and low Cu, Pb, and Zn contents. Stable isotope data indicate that ore fluids consisted dominantly of meteoric water that evolved by deep circulation through Paleozoic sedimentary rocks at low water/rock ratios (about 1) and high temperatures (>200??C). Calculated isotopic compositions of ore fluids are ??18OH2O = -3 to -7 per mil, ??DH2O = -107 to -124 per mil, ??13CCO2 = 0 to -6 per mil, and ??34SH2S = -3 to +8 per mil. The ore fluids obtained much of their H2S and CO2 and probably scavenged ore metals and trace elements from the Paleozoic sedimentary rocks. Some H2S and CO2 may have been derived from degassing Miocene magmas. Mule Canyon formed at shallow depths, probably about 100 m below the paleosurface. Ore fluids were dilute, nearly neutral in pH, reduced, H2S-rich, and CO2-bearing. Peak temperatures in ore zones reached 230?? to 265??C at nearly lithostatic pressures when some crystalline quartz ?? adularia precipitated, but most ore formed at temperatures <200??C at near hydrostatic pressures and was accompanied by precipitation of opaline and chalcedonic silica ?? adularia ?? calcite and dolomite. Deposition of gold in As-rich overgrowths on pyrite and/or marcasite in disseminated ores occurred owing to decreasing H2S in the ore fluids resulting from sulfidation reactions. Later electrum and Ag selenide precipitation in open spaces occurred owing to boiling, loss of H2S to the vapor phase, and cooling. Mule Canyon is similar to most other low-sulfidation Au-Ag deposits associated with Miocene tholeiitic bimodal basalt-rhyolite magmatism in the Great Basin, such as Sleeper, Midas, and Buckhorn. Major differences at Mule Canyon are

Evidence of Trawl-Induced Resuspension at the Whittard Canyon, NE Atlantic?

NASA Astrophysics Data System (ADS)

Wilson, A. M.; Kiriakoulakis, K.; Raine, R.; Gerritsen, H. D.; Blackbird, S.; Allcock, A. L.; White, M. G.

2016-02-01

Four research surveys (2011-2014) to the Whittard Canyon have taken place as part of an Irish Bio-discovery and Ecosystem functioning project. Hydrographic observations including turbidity measurements and samples for biogeochemical analysis were collected in order to improve our understanding of sediment transport, biogeochemical cycling and trophic food webs within canyons. Benthic and intermediate nepheloid layers were detected during all four surveys, in eastern and western branches of the canyon. These layers act as a pathway from productive shelf environments to the deep abyss. Unusual peaks in turbidity were detected in two branches of the canyon in June 2013. These turbidity peaks, termed Enhanced Nepheloid Layers (ENLs), had elevated suspended particulate matter concentrations exceeding 1 mg L-1. Typically, concentrations of material in nepheloid layers range between 0.28-0.6 mg L-1, while the largest ENLs measured between 2-8 mg L-1. The ENLs measured 100-260 m in vertical height and were detected in water depths of between 640-2880 m. Vessel Monitoring System data showed that high spatial and temporal activity of potential bottom trawling vessels coincided with the occurrence of the ENLs. Molar C/N ratios of the suspended organic material from the ENLs showed a high degree of degradation. While trawling has previously been suspected to affect the Whittard Canyon, this is the first study to provide evidence of such activity. Regular occurrences of these events are likely to have implications for increased sediment fluxes, burial of organic carbon and alteration of benthic and canyon ecosystems.

Impact of roof height non-uniformity on pollutant transport between a street canyon and intersections.

PubMed

Nosek, Štěpán; Kukačka, Libor; Jurčáková, Klára; Kellnerová, Radka; Jaňour, Zbyněk

2017-08-01

This paper presents an extension of our previous wind-tunnel study (Nosek et al., 2016) in which we highlighted the need for investigation of the removal mechanisms of traffic pollution from all openings of a 3D street canyon. The extension represents the pollution flux (turbulent and advective) measurements at the lateral openings of three different 3D street canyons for the winds perpendicular and oblique to the along-canyon axis. The pollution was simulated by emitting a passive gas (ethane) from a homogeneous ground-level line source positioned along the centreline of the investigated street canyons. The street canyons were formed by courtyard-type buildings of two different regular urban-array models. The first model has a uniform building roof height, while the second model has a non-uniform roof height along each building's wall. The mean flow and concentration fields at the canyons' lateral openings confirm the findings of other studies that the buildings' roof-height variability at the intersections plays an important role in the dispersion of the traffic pollutants within the canyons. For the perpendicular wind, the non-uniform roof-height canyon appreciably removes or entrains the pollutant through its lateral openings, contrary to the uniform canyon, where the pollutant was removed primarily through the top. The analysis of the turbulent mass transport revealed that the coherent flow structures of the lateral momentum transport correlate with the ventilation processes at the lateral openings of all studied canyons. These flow structures coincide at the same areas and hence simultaneously transport the pollutant in opposite directions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Erosional threshold for the formation of bedrock canyons carved by megafloods on Earth and Mars

NASA Astrophysics Data System (ADS)

Lamb, Michael P.; Lapotre, Mathieu G. A.; Larsen, Isaac J.; Williams, Rebecca M. E.

2017-04-01

Enormous canyons have been carved into the surfaces of Earth and Mars by catastrophic outbursts of water. On Mars, these bedrock canyons, known as the planetary-scale outflow channels, are the most important indicator of large volumes of flowing water in the planet's history. Despite their importance and now decades of observations of canyon morphology, we lack a basic understanding of how the canyons formed, which limits our ability to reconstruct flood discharge, duration, and water volume. In this presentation I will summarize recent work - using mechanistic numerical models and field observations of similar landforms on Earth - that suggests that bedrock canyons carved by megafloods may rapidly evolve to a size and shape in which boundary shear stress just exceeds that required to entrain fractured blocks of rock. Recent advances in theory for plucking, sliding and toppling of fractured rock allow for quantitative constraints on erosion thresholds. Coupling these erosional constraints with 2-D hydrodynamic models at waterfalls shows that cataracts in basalt, which are common in megaflood terrain, evolve to a threshold state such that canyon width accurately reflects flood discharge. The erosional threshold hypothesis also is consistent with the formation of gravel bars in the Channeled Scablands of the Missoula Floods, USA, and with observations of a small flood-carved canyon from a dam overflow event in 2002 in Texas. Together, these studies suggest that canyons progressively erode in concert with megaflooding, such that flood waters never fully filled the final canyon relief, implying smaller flood discharges and longer durations than models that assume near canyon-filling floods routed over modern topography.

Interaction of Corundum, Wollastonite and Quartz With H2O-NaCl Solutions at 800 C and 10 Kbar

NASA Astrophysics Data System (ADS)

Newton, R. C.; Manning, C. E.

2005-12-01

Aqueous fluids are potentially important transport agents in subduction zones and other high-P metamorphic environments. Recent studies indicate that at high P and T, the solubilities of major rock-forming elements are strongly enhanced by the formation of metal-chloride complexes, metal-hydroxide complexes and polynuclear metal-hydroxide clusters. However, the relative abundances of these species and the energetics of their interactions in high-pressure environments remains largely unknown. We measured the solubilities of corundum (Al2O3) and wollastonite (CaSiO3) at 800 °C and 10 kbar in H2O-NaCl solutions to halite saturation (XNaCl = 0.6) . Both minerals show marked enhancement of solubility with increasing salinity. Al2O3 mol fraction rises rapidly to XNaCl = 0.1, and then declines slowly towards halite saturation. Quenched experimental fluids have neutral pH. Modeling based on ideal solution of ions and molecules leads to a simple dissolution reaction and corresponding molality (m=mol/kg H2O) expression: Al2O3(cor) + Na+ + 3H2O = NaAl(OH)4 + Al(OH)2+ and mAl2O3 = [0.0232(aNaCl)1/4(aH2O)3/2+0.00123][1+2XNaCl/(1-XNaCl)] where H2O and NaCl activities are given by aH2O = (2-XNaCl)/(2+XNaCl) and aNaCl = 4(XNaCl)2/(1 + XNaCl)2. Wollastonite solubility in NaCl solutions is accurately described by: mCaSiO3 = 0.6734XNaCl + 0.1183(XNaCl)1/2 + 0.0204. There is a roughly 50-fold enhancement of dissolved wollastonite at halite saturation. Quenched experimental fluids are strongly basic (pH=11). A consistent dissolution reaction must therefore be similar to: CaSiO3(wo) + Na+ + Cl- = CaCl+ + OH- + HNaSiO3 Quartz solubility declines monotonically from mSiO2 = 1.248 in pure H2O to 0.20 at halite saturation. Quenched fluids are neutral, indicating that quartz does not react with solvent NaCl. The only salinity control on solubility is decrease of H2O activity. The simple dissolution behaviors to be deduced from measurements on these minerals suggest that fluid

Influence of calcite and dissolved calcium on uranium(VI) sorption to a hanford subsurface sediment.

PubMed

Dong, Wenming; Ball, William P; Liu, Chongxuan; Wang, Zheming; Stone, Alan T; Bai, Jing; Zachara, John M

2005-10-15

The influence of calcite and dissolved calcium on U(VI) adsorption was investigated using a calcite-containing sandy silt/clay sediment from the U. S. Department of Energy Hanford site. U(VI) adsorption to sediment, treated sediment, and sediment size fractions was studied in solutions that both had and had not been preequilibrated with calcite, at initial [U(VI)] = 10(-7)-10(-5) mol/L and final pH = 6.0-10.0. Kinetic and reversibility studies (pH 8.4) showed rapid sorption (30 min), with reasonable reversibility in the 3-day reaction time. Sorption from solutions equilibrated with calcite showed maximum U(VI) adsorption at pH 8.4 +/- 0.1. In contrast, calcium-free systems showed the greatest adsorption at pH 6.0-7.2. At pH > 8.4, U(VI) adsorption was identical from calcium-free and calcium-containing solutions. For calcite-presaturated systems, both speciation calculations and laser-induced fluorescence spectroscopic analyses indicated that aqueous U(VI) was increasingly dominated by Ca2UO2(CO3)3(0)(aq) at pH < 8.4 and thatformation of Ca2UO2(CO3)3(0)(aq) is what suppresses U(VI) adsorption. Above pH 8.4, aqueous U(VI) speciation was dominated by UO2(CO3)3(4-) in all solutions. Finally, results also showed that U(VI) adsorption was additive in regard to size fraction but not in regard to mineral mass: Carbonate minerals may have blocked U(VI) access to surfaces of higher sorption affinity.

Mapping wilderness character in Sequoia and Kings Canyon National Parks

Treesearch

James Tricker; Peter Landres; Gregg Fauth; Paul Hardwick; Alex Eddy

2014-01-01

The Sequoia-Kings Canyon Wilderness was established in September of 1984 when President Ronald Reagan signed the California Wilderness Act (PL 98-425). In March 2009, President Barack Obama signed the Omnibus Public Land Management Act (PL 111-11) designating the John Krebs Wilderness and the Sequoia-Kings Canyon Wilderness Addition (all wholly contained within SEKI)....

Internal tides affect benthic community structure in an energetic submarine canyon off SW Taiwan

NASA Astrophysics Data System (ADS)

Liao, Jian-Xiang; Chen, Guan-Ming; Chiou, Ming-Da; Jan, Sen; Wei, Chih-Lin

2017-07-01

Submarine canyons are major conduits of terrestrial and shelf organic matter, potentially benefiting the seafloor communities in the food-deprived deep sea; however, strong bottom currents driven by internal tides and the potentially frequent turbidity currents triggered by storm surges, river flooding, and earthquakes may negatively impact the benthos. In this study, we investigated the upper Gaoping Submarine Canyon (GPSC), a high-sediment-yield canyon connected to a small mountain river (SMR) off southwest (SW) Taiwan. By contrasting the benthic meiofaunal and macrofaunal communities within and outside the GPSC, we examined how food supplies and disturbance influenced the benthic community assemblages. The benthic communities in the upper GPSC were mainly a nested subset of the adjacent slope assemblages. Several meiofaunal (e.g. ostracods) and macrofaunal taxa (e.g. peracarid crustaceans and mollusks) that typically occurred on the slope were lost from the canyon. The polychaete families switched from diverse feeding guilds on the slope to motile subsurface deposit feeders dominant in the canyon. The diminishing of epibenthic peracarids and proliferation of deep burrowing polychaetes in the GPSC resulted in macrofauna occurring largely within deeper sediment horizons in the canyon than on the slope. The densities and numbers of taxa were depressed with distinct and more variable composition in the canyon than on the adjacent slope. Both the densities and numbers of taxa were negatively influenced by internal tide flushing and positively influenced by food availability; however, the internal tides also negatively influenced the food supplies. While the meiofauna and macrofauna densities were both depressed by the extreme physical conditions in the GPSC, only the macrofaunal densities increased with depth in the canyon, presumably related to increased frequency and intensity of disturbance toward the canyon head. The population densities of meiofauna, on the

75 FR 39147 - Establishment of Class E Airspace; Bryce Canyon, UT

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-08

... E airspace at Bryce Canyon, UT, to accommodate aircraft using a new Area Navigation (RNAV) Global Positioning System (GPS) Standard Instrument Approach Procedures (SIAPs) at Bryce Canyon Airport. This will improve the safety and management of Instrument Flight Rules (IFR) operations at the airport. DATES...

Turbulent Transfer Between Street Canyons and the Overlying Atmospheric Boundary Layer

NASA Astrophysics Data System (ADS)

Salizzoni, Pietro; Marro, Massimo; Soulhac, Lionel; Grosjean, Nathalie; Perkins, Richard J.

2011-12-01

The turbulent exchange of momentum between a two-dimensional cavity and the overlying boundary layer has been studied experimentally, using hot-wire anemometry and particle image velocimetry (PIV). Conditions within the boundary layer were varied by changing the width of the canyons upstream of the test canyon, whilst maintaining the square geometry of the test canyon. The results show that turbulent transfer is due to the coupling between the instabilities generated in the shear layer above the canyons and the turbulent structures in the oncoming boundary layer. As a result, there is no single, unique velocity scale that correctly characterizes all the processes involved in the turbulent exchange of momentum across the boundary layer. Similarly, there is no single velocity scale that can characterize the different properties of the turbulent flow within the canyon, which depends strongly on the way in which turbulence from the outer flow is entrained into the cavity and carried round by the mean flow. The results from this study will be useful in developing simple parametrizations for momentum exchange in the urban canopy, in situations where the street geometry consists principally of relatively long, uniform streets arranged in grid-like patterns; they are unlikely to be applicable to sparse geometries composed of isolated three-dimensional obstacles.

Environmental and human impact on the sedimentary dynamic in the Rhone Delta subaquatic canyons (France-Switzerland)

NASA Astrophysics Data System (ADS)

Arantegui, A.; Corella, J. P.; Loizeau, J. L.; Anselmetti, F. S.; Girardclos, S.

2012-04-01

Deltas are very sensitive environments and highly vulnerable to variations in water discharge and the amount of suspended sediment load provided by the delta-forming currents. Human activities in the watershed, such as building of dams and irrigation ditches, or river bed deviations, may affect the discharge regime and sediment input, thus affecting delta growth. Underwater currents create deeply incised canyons cutting into the delta lobes. Understanding the sedimentary processes in these subaquatic canyons is crucial to reconstruct the fluvial evolution and human impact on deltaic environments and to carry out a geological risk assessment related to mass movements, which may affect underwater structures and civil infractructure. Recently acquired high-resolution multibeam bathymetry on the Rhone Delta in Lake Geneva (Sastre et al. 2010) revealed the complexity of the underwater morphology formed by active and inactive canyons first described by Forel (1892). In order to unravel the sedimentary processes and sedimentary evolution in these canyons, 27 sediment cores were retrieved in the distal part of each canyon and in the canyon floor/levee complex of the active canyon. Geophysical, sedimentological, geochemical and radiometric dating techniques were applied to analyse these cores. Preliminary data show that only the canyon originating at the current river mouth is active nowadays, while the others remain inactive since engineering works in the watershed occurred, confirming Sastre et al. (2010). However, alternating hemipelagic and turbiditic deposits on the easternmost canyons, evidence underflow processes during the last decades as well. Two canyons, which are located close to the Rhone river mouth, correspond to particularly interesting deeply incised crevasse channels formed when the underwater current broke through the outer bend of a meander in the proximal northern levee. In these canyons, turbidites occur in the sediment record indicating ongoing