Browsing by Subject "Sedimentation analysis"
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Item Biosolids application on southwest Texas rangelands: its influence on the soil and sediment properties and on runoff water quality(Texas Tech University, 1998-12) Rostagno, Cesar MarioWe assessed the effects of surface biosolids application date (Jan and Jul 95 and 1996) and rate (0, 7, 18, 34, and 90 Mg ha^-1) on soil physical and chemical properties, infiltration rate (IR), sediment production (SP) and quality, and runoff water quality from shrubland (Ustic Calciargid) and grassland (Vertic Paleargid) soils. Between July and October of 1996 we applied simulated rainfall to 0.50 m^2 plots with a single-nozzle rainfall simulator for 30-min at a rate of 160 mm hr^-1. All of the runoff and sediments were collected at 5-min increments. In the two soils, organic matter and IR increased; bulk density and SP decreased as rate of biosolids application increased. In the shrubland soil and for the plots treated in Jan 95 with 90 Mg ha^-1 IR increased 4.5 times with respect to the control plots. For the same soil and treatment, SP decreased 22-fold. The eroded sediments of the shrubland soil for the 18 Mg ha^-1 biosolids applied in Jan 95 had the highest amount of organic matter For this soil, the enrichment of total N in the eroded sediments of the control plots was 40%, and increased to 1600% in the 18 Mg ha^-1 plots treated in January, 1995. Also, Cu and Zn in the eroded sediments increased from 96% and 160% in the control plots, to 1660% and 1460% in the treated plots, respectively. The concentration of NH4, NO?, PO4, Cu, and Mn in the runoff water were similarly affected by biosolids application, increasing with rate and decreasing with time of biosolids postapplication in the two soils. PO4 and NH4 should be the main compounds considered when surface-applying biosolids since their concentrations are well above the threshold for eutrophication and the recommendations for effluent discharge levels into surface waters Except for Mn that was above the US-EPA established secondary maximum contaminant level for drinking water in the plots treated with the higher rates of biosolids, the rest of the analyzed elements and compounds were either below the detection limits or within the US-EPA established .standards.Item Petrologic study of sediments from selected central Texas caves(1965-08) Frank, Ruben Milton; Folk, Robert L.The petrologic study of cave sediments is a new field whose history dates back only about 30 years. Most previous work has been done in Europe, with very little in North America. This is the first petrologic study of sediments of Texas caves. Sediments from the 11 Central Texas caves investigated provide information on the diagenetic sequence of authigenic calcite and collophane, and add to the knowledge of the occurrence and distribution of red clays and dolomite silts. The sediments from Fyllan Cave in Travis County place a maximum date of mid-Pleistocene on the existing Colorado River terraces. X-ray analysis of clays in sediments from three caves indicates a decline in kaolinite content, confirming a drying tendency for the last 8000 years.Item Sedimentation of multisized particles(Texas Tech University, 1981-08) Kothari, Akalankkumar C.A new model is developed for the sedimentation of multisized particles. Unlike previously published models, the present model takes into account interparticle interactions by taking into consideration the buoyancy effect induced by the smaller size particles on the terminal falling velocities of large size particles. The new and previously published models are tested against published and newly collected data on suspensions with discrete size distribution. It is shown that the present model is the most accurate and represents the experimental data satisfactorily. Moreover, the model satisfactorily represents the experimental data on binary countercurrent operations where the Reynolds number is as high as 546. It is also shown that the proposed model can be used to predict the sedimentation velocities of suspensions with continuous size distribution.Item Soil-geomorphic relationships in the ancient Lake Lomax Basin, Southern High Plains(Texas Tech University, 1999-08) Cano-Garcia, Miguel A.The Lake Lomax Basin is on the southern margin of the High Plains in West Texas. Evidence suggests that it has been formed by subsidence/erosion processes in very eariy Pleistocene time and subsequent wind deflation. This study was conducted to determine the relationships between geomorphic surfaces and soil parent materials inside and outside of the basin and to generate information useful for a planned soil survey update. A preliminary study was conducted inside, as well as outside, of the basin. Clay mineralogy and particle-size distribution (PSD) analyses were used to differentiate between Blackwater Draw Formation and Ogallala Formation sediments. In the basin area, soil profile morphology was described along a 25-km east-west transect across the basin and along a 23-km north-south transect in the basin. Clay mineralogy, particle-size distribution, and selected chemical analyses were carried out. Particle-size distribution statistical parameters such as mean grain size, standard deviation, and skewness were used as criteria to discriminate among the different parent materials in transect samples.