Narter, Matthew (The University of Arizona., 2012)
The objective of this study was to characterize non-wetting fluid in multi-phase systems comprising a range of fluid and porous medium properties. Synchrotron X-ray microtomography was used to obtain high-resolution, three-dimensional images of fluids in natural porous media. Images were processed to obtain quantitative measurements of fluid distribution, morphology, and interfacial area. Column-flooding experiments were conducted with four enhanced-solubilization (ES) solutions to examine their impact on entrapped organic liquid. Mobilization caused a change in organic-liquid morphology and distribution for most experiments. The effect of ES-solution flooding on fluid-fluid interfacial area was similar to that of water flooding. Organic-liquid mobilization was observed at total trapping numbers that were smaller than expected. This was attributed to pore-scale mobilization of blobs that were re-trapped prior to being eluted from the column. Pore-scale mobilization was also observed during water-flooding experiments for which trapping numbers varied over several orders of magnitude. Water-flooding and surfactant-flooding experiments were compared to investigate the impact of interfacial tension, viscosity, and fluid velocity on entrapped organic liquid. For similar total trapping numbers, flooding at larger velocities appeared to have a greater effect on the distribution of non-wetting blobs than lowering interfacial tension or increasing the viscosity of the wetting fluid. The fluid-normalized interfacial area was generally independent of the total trapping number. Finally, the impact of fluid type on the interfacial area between different pairs of non-wetting fluids was investigated during drainage and imbibition in four natural porous media. Interfacial areas were similar among all fluid pairs for a given porous medium. They were also similar for drainage and imbibition conditions. The maximum specific interfacial area (A(m)) was determined to quantify the magnitude of interfacial area associated with a given porous medium. The value of A(m) was larger for the media with smaller median grain diameters. Therefore, physical properties of the porous medium appear to have a greater influence on the magnitude of specific total interfacial area for a given saturation than fluid properties or wetting-phase history.
Rodriguez, Roberto Alejandro (The University of Arizona., 2007)
The goals of this dissertation were to determine the viral contribution of combined sewer overflows (CSO) to receiving waters during wet weather conditions, and to compare the use of the primary liver carcinoma (PLC/PRF/5) cells with the buffalo green monkey (BGM) cells for total culturable virus assay (TCV). To assess the contribution of CSO on the viral quality of the receiving water, samples of discharges and effluent receiving waters of three sewage reclamation plants located in Illinois were collected from June to October during two consecutive years. Samples were tested for TCV, adenovirus and norovirus. Viral concentration in the receiving water increases approximately ten times the concentration during CSO events in comparison with dry weather. An assessment comparing TCV by PLC/PRF/5 and BGM cells was also conducted using sewage samples collected before and after disinfection. PLC/PRF/5 cells detected between 10 to 50 times more viruses (?) than the BGM cells. Adenoviruses were detected in the PLC/PRF/5 cells, but not in the BGM cells. In conclusion, CSO events resulted in a significant increase in the concentration of viruses in the receiving waters and PLC/PRF/5 cells are more sensitive for enteric virus detection than the BGM cell line.
Holleran, Molly E. (The University of Arizona., 2013)
The quantification and prediction of soil properties is fundamental to further understanding the Critical Zone (CZ). In this study we aim to quantify and predict soil properties within a forested catchment, Marshall Gulch, AZ. Input layers of soil depth (modeled), slope, Saga wetness index, remotely sensed normalized difference vegetation index (NDVI) and national agriculture imagery program (NAIP) bands 3/2 were determined to account for 95% of landscape variance and used as model predictors. Target variables including soil depth (cm), carbon (kg/m²), clay (%), Na flux (kg/m²), pH, and strain are predicted using multivariate linear step-wise regression models. Our results show strong correlations of soil properties with the drainage systems in the MG catchment. We observe deeper soils, higher clay content, higher carbon content, and more Na loss within the drainages of the catchment in contrast to the adjacent slopes and ridgelines.
Bacteria have evolved sophisticated cellular transport mechanisms to maintain metal homeostasis to not only utilize metals as important cofactors but also to evade the toxicity of these ions. The delicate balance is maintained by several homeostatic mechanisms that range from active cytoplasmic export, modification, sequestration, and periplasmic detoxification of toxic metals to the extracellular milieu. One mechanism involves active periplasmic extrusion of toxic substrates via a transmembrane spanning tripartite protein complex. The mechanism of substrate binding and subsequent efflux has yet to be elucidated. However, genetic, comparative genomic, biochemical, and functional analyses of the components of the heavy-metal efflux family have allowed the development of proposed models for a substrate transport pathway. The goals of this research were to identify the roles these systems play and to further characterize these systems on a molecular level to ultimately understand the mechanism of substrate transport. Elucidating a transport pathway in metal transporters allows for the development of a revised working model, which ultimately can have implications for antimicrobial drug development.
Nuñez Moreno, Jesus Humberto (The University of Arizona., 2009)
Annual application of N at rates of 118 (118N), 236 (236N), and 354 (354N) kg•ha⁻¹ on 35 year old 'Western Schley' pecan trees during four years had little effect on mineral composition and foliar N. No differences in yield, nut quality, and reproductive characteristics were found. Alternate bearing intensity in four consecutive years was 37, 33 and 28% in 118N, 236N, and 354N, respectively, with a significant linear response. Rates from 118 to 236 kg N•ha⁻¹ satisfy N needs for pecan in irrigated pecan orchard of the southwest of United States. The effect of one-time banding of zinc sulfate (74 kg Zn•ha⁻¹) and zinc-EDTA (19 kg Zn•ha⁻¹) was evaluated over a period of four years on ‘Wichita’ pecans growing in alkaline soil. Significant differences in foliar Zn levels were found one month after application of Zinc-EDTA. Differences also were noted during the next three years on approximately 25% of the sampling dates. Yield, leaflet area, and trunk cross sectional area were not affected. Zinc-EDTA increased Zn uptake by 'Wichita' pecan trees in alkaline conditions during three years. A field study indicated that manure or manure plus Zn increased foliar Zn levels in pecans after two years of annual applications. Manure (24 ton ha⁻¹) plus zinc sulfate (258 kg Zn•ha⁻¹ as zinc sulfate) treatment had the highest foliar Zn levels. No differences were observed in trunk growth, leaf area, leaf weight, nut filling, and yield. Manganese toxicity symptoms are exhibited when leaf Mn levels are higher than 1700 μg•g⁻¹ during the standard date sampling of July and affected reproductive characteristics and leaf and shoot growth. More severe visible symptoms include delayed budbreak and die-back of young shoots. In potted pecan trees, zinc EDTA treated trees had a foliar Zn of 244 μg•g⁻¹, in foliar sprayed trees (eight foliar sprays of a combination of zinc sulfate and UAN32) had 140 μg•g⁻¹, and in control trees had 33 μg•g⁻¹. Soil adsorption isotherms showed that of the three fertilizers evaluated Zn sulfate was adsorbed most strongly by the soil (1.5 mg Zn•g⁻¹ of soil). Soil adsorption from Zn EDTA solutions was insignificant.
Yepiz, Maria Susana (The University of Arizona., 2009)
The first study was designed to determine the occurrence of bacteria in dishcloths used in restaurants and bars. Coliforms were isolated from 89% of dishcloths and 70% of tabletops. Escherichia coli was isolated from 54% of dishcloths and 20% of tabletops. The numbers of heterotrophic bacteria (HPC) and coliforms were higher in bars than in restaurants. The levels of HPC found in dishcloths were 25-fold and coliforms were 60-to 120-fold lower than the levels found in dishcloths in previous home studies. The most commonly isolated genera from dishcloths in restaurants and bars differed from those in homes. The numbers of HPC on restaurant tabletops were 45-fold greater after cleaning than prior to cleaning. The mandatory use of sanitizers in restaurants and bars may therefore have reduced contamination levels and caused a shift in the microbial populations present in food service establishments. The second study was designed to determine the recovery efficiency and the survival of two respiratory viruses on produce and was compared to the survival of the enteric poliovirus 1. Adenovirus was recovered with an efficiency of 56%, 32% and 35% from lettuce, strawberries and raspberries, respectively. Coronavirus was recovered from lettuce with an efficiency of 19.6%, but could not be recovered from strawberries. Poliovirus was recovered from lettuce with an efficiency of 76.6% and 0.06% from strawberries. The survival of the viruses was observed for up to eight days. Adenovirus survived the longest on raspberries, with a log₁₀ reduction of 0.61, followed by 1.68- and 1.75-log₁₀ reductions on strawberries and lettuce, respectively. Coronavirus declined by 0.41-log₁₀ after two days and >1.34 log₁₀ by day 4 on lettuce. The enteric poliovirus 1 survived longer on produce, decreasing by only 0.37-log₁₀ on lettuce and 1.30-log₁₀ on strawberries. A microbial risk assessment was performed to assess the risk of infection from ingesting 1, 10, and 100 particles of adenovirus on lettuce. The estimated risk of infection by ingesting these numbers were 1:2000, 1:200, and 1:20, respectively and increased in a proportional way as the number of servings was increased from one to ten and 365 servings of lettuce.
Navarro-Ainza, Jose A. Cristobal (The University of Arizona., 2007)
The first project involved the evaluation of different times of application on the fertilizer nitrogen recovery (FNR) in the soil-plant system in an irrigated upland cotton system, during two seasons. This was accomplished by using the isotopic dilution technique applying the 15N to microplots. No differences were observed in the total plant FNR, seed and stover, soil and the total FNR among the different 15N application times; however, despite no differences were observed in the plant the FNR value ranged from 30-38%, while the seed exhibited the highest FNR with an average over 50% of the 15N recovered in the plant. In the soil, the obtained average FNR value was over 40% while the total FNR (plant + soil) ranged from 70-80%, being reduced as the 15N application time was delayed.The second project was conducted during two seasons to examine the 15N and bromide distribution pattern in the soil profile as a function of the time of application. 15Nitrogen and bromide were applied to the soil at three different times in a cotton growth cycle; after that, soil samples were taken at the end of the cotton cycle to a depth of 1.80 m., and 15N and bromide recoveries were determined. Slightly higher FNR were obtained with the intermediate application time. The higher FNR were detected in the surface layer (0-30 cm) with an average of 40%. Below 30 cm depth, low 15N recoveries were obtained and even lower below the 60 cm soil layer. Bromide recovery behavior was related to the water movement in the soil profile: as the Br- application time was delayed more of the anionic tracer was found in the top of the soil profile, while less Br- was found in the surface soil for the early Br- application time.
Martinez Garcia, Rafael (The University of Arizona., 2010)
It has been demonstrated the technical feasibility of using seawater and other saline water for irrigation. Through the use of saline water for irrigation, highly salt-tolerant crops could greatly increase global agriculture. Brackish water and seawater from different sources are available in areas suitable for production of salt-tolerant crops. Dwarf glasswort Salicornia bigelovii Torr. (Chenopodiaceae), is a leafless, succulent, small-seeded, annual saltmarsh plant, with potential as a saline water crop. It is also a potential oilseed, forage, biomass crop, and a promising carbon sequestration plant. In the first chapter of this document we describe a study where we grew Salicornia bigelovii from seedlings, in saline, drying soils in a greenhouse experiment. The effects of drought and salinity stress were additive. Optimal growth and water use efficiency coincided at 0.35-0.53 M NaCl. The plants were tolerant of high salinity but exhibited little drought tolerance. Salicornia bigelovii plants varied little in their uptake of Na+ for osmotic adjustment, with final Na+ contents of 18% on a dry mass basis. Both growth and water use efficiency of Salicornia bigelovii were affected by salinity. Also, Na+, the primary cation involved in osmotic adjustment of this species, apparently stimulates growth by mechanisms apart from its role as an osmoticum. In the second chapter of this dissertation we developed a research study where we evaluated the production and osmotic adjustment of two S. bigelovii lines (Texas and Florida), plants were grown in pot in a green house and irrigated with water treated with three different levels of NaCl (5 ppt, 15 ppt and 30 ppt) combined with inorganic fertilizer. At the end of the experiment sixty plants from each line were measured for height, biomass, seed yield, seed size, dry matter yield, and tissue osmolarity. There was no significant difference among groups in plant height, or final biomass either in salinity irrigation treatments, or S. bigelovii lines. Tissue osmolarity differed among salinity treatments but not among S. bigelovii lines. The highest tissue osmolarity value was 1192 mM kg-1 found at the treatment 30ppt in the Florida line. Total biomass production was 12 000 kg/Ha.
Sifuentes, Laura Yvette (The University of Arizona., 2012)
The amoebae Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris are free-living amoebae found in both water and soil. They are opportunistic pathogens in humans. Acanthamoeba is the most common cause of illness, usually infecting the eyes and sometimes causing a sight-threatening keratitis. Acanthamoeba spp. and B. mandrillaris can cause granulomatous amoebic encephalitis, in addition to infections of the lungs and skin. N. fowleri causes primary amoebic meningoencephalitis . There is little known regarding the ecology and occurrence of these organisms. A total of 36 high-use recreational surface waters in Arizona were surveyed over a period of two years to assess the occurrence of N. fowleri and seasonal and environmental factors. Overall, 9.3% of the warm weather samples collected were positive for N. fowleri, whereas 16.3% of the samples were positive during cold weather. Although the presence of N. fowleri could not be significantly correlated with physical and chemical parameters such as temperature, pH, turbidity, conductivity, and the presence of heterotrophic bacteria, total coliforms, and Escherichia coli, a weak correlation (0.52) with live amoebic activity was observed. Five lakes to the north and northeast of Phoenix tested positive for the N. fowleri on more than one occasion over multiple seasons. Finished drinking water samples (n= 785) from a municipal potable distribution system were evaluated for the presence of N. fowleri, B. mandrillaris and Acanthamoeba spp. from 18 different regions during three different sampling periods. Physical and chemical parameters were also evaluated but provided no significant correlations with the occurrence of amoebae or indicator organisms. A total of 138 samples (17.9%) were positive for viable amoebae in distribution water with more than an adequate chlorine residual (average of 0.86 mg/L). Microorganisms that are typically used to monitor microbial water quality such as coliforms and E. coli would likely not be found under these circumstances. Clusters with three or more samples testing positive for viable amoebae per region were observed during all three periods. Viable amoebae may not only provide a better assessment of the microbial quality of water, but such clustering could reveal areas with potential water quality issues within the distribution system.
Mendez, Monica Orozco (The University of Arizona., 2007)
Phytostabilization is an emerging technology for the remediation of mine tailings sites. In arid and semiarid environments, mine tailings disposal sites are a major source of environmental pollution as they are subject to eolian dispersion and water erosion. Mine tailings are acidic to neutral, high in metal content, and nutrient poor. Furthermore, these sites remain unvegetated even after decades of no additional mining activity. In arid and semiarid regions, climatic variables such as high winds, salinity, and drought exacerbate the problem. The Klondyke mine tailings site is a model site for studying plant establishment in mine tailings within semiarid regions. It was a lead and zinc ore- processing operation from 1948 to 1958 and is similar in physicochemical characteristics to other acidic pyritic mine tailings.In a greenhouse study, a native drought tolerant halophyte, Atriplex lentiformis (Torr.) S. Wats., was evaluated for its potential as a phytostabilization candidate in compost-amended tailings from the Klondyke site. Germination, plant growth, and metal uptake of A. lentiformis were examined, and the microbial community was monitored by enumeration of autotrophic iron- and sulfur-oxidizing bacteria as well as heterotrophic bacteria. Results demonstrated that with 10 to 15% compost addition, growth of A. lentiformis was not affected and shoot metal concentrations were generally not a concern for foraging animals. Furthermore, the heterotrophic bacterial community is severely stressed but recovers with compost addition and successful plant growth. Therefore, A. lentiformis is a good candidate for phytostabilization of mine tailings with compost amendments.Poor revegetation of mine tailings has been attributed to the microbial community involved in acidifying tailings; however, no thorough microbial studies have been conducted. The second study characterizes the bacterial community of the Klondyke site and compares it to an offsite control sample. Results demonstrate that the heterotrophic community is indicative of soil health as it has a positive relationship with pH, phylotype richness, and diversity. Also, the mine tailings contain an unexplored diversity of acidophiles that are important in maintaining acidity and thus, metal bioavailability. Therefore, the bacterial community in mine tailings should be monitored in phytostabilization studies to evaluate restoration.
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