As of 2010, there are approximately twenty one surface water locations classified as impaired for Escherichia coli (E. coli) contamination in the State of Arizona. Of note is the San Francisco River (SFR) which is currently listed on the US EPA 303d list of impaired waters due to E. coli bacteria present at higher concentrations than the US EPA standards for partial- and full-body contact. In 2010-2011 surface water samples were collected at sites within the impaired region to monitor E. coli and areas known for heavy recreational uses. Of 70 samples collected over 1 year, 81% were positive for universal Bacteroides marker (Allbac). Of the 57 Allbac-positive samples, 68% show contributions of the human-specific marker and 60% were positive for bovine-specific marker. While 28% of the total samples assayed showed elevated levels of E. coli (>235 MPN/100mL), there were minimal significant correlations between Bacteroides and generic E. coli across all samples. While this information is significant, past research has suggested that successfully distinguishing the sources of fecal contamination will not alone reduce or eliminate disease associated with contaminated water unless these investigations are coupled with public outreach and education. With this in mind a survey was developed to gather information about water quality perceptions, water use, peoples' attitudes, knowledge, and behaviors related to the water resources in Clifton, AZ. Survey questions consisted of multiple choice and Likert scales questions and were provided in both English and Spanish and were conducted during the summer of 2012 and winter of 2013. A total of 150 surveys were deployed with 38 surveys completed for a response rate of 25%. Our study findings indicate mixed attitudes on water quality with 80% reporting the SFR has poor water quality for drinking and 39% agree the SFR has poor water quality for swimming. Yet, 84% consider the river safe enough for picnics and activities near the water. Also, it was interesting to note participants' opinions regarding consequences of poor water quality with 66% of respondents indicating that they are concerned with poor water quality and their health. Clifton is a very tight knit community so it was not unexpected that the majority of the respondents (61%) get water quality information by having conversations with other people and 68% from newspapers, factsheets and brochures. Based on the survey responses, our team worked to develop two peer reviewed Extension publications entitled; Microbial Source Tracking: Watershed Characterization and Source Identification (Arizona Cooperative Extension, #AZ1547) and Water Quality, E. coli, and Your Health (#AZ1624). Publications have been developed in both English and Spanish and will be part of future outreach to this and other Arizona communities. It is our goal that these survey findings can be used to better tailor outputs appropriate for the targeted audience, namely the local Hispanic population. These results are important because they add to understanding perceptions of water quality and health risks in this rural community; and can lend towards enhanced outreach practices in other similar communities.

Utilization of areas adjacent to rivers for agricultural and industrial purposes can have detrimental effects on water quality and can potentially impact human and ecosystem health downstream. In this study we tested water quality along a stretch of the effluent-dependent Santa Cruz River near Nogales, AZ. This stretch of river has historically been impaired, but prior to upgrades to the Nogales International Wastewater Treatment Plant (NIWTP) in 2009. Our work endeavored to assess water quality according to the Arizona Department of Environmental Quality (ADEQ) standards, and identify sources of pollution entering the river system. Heavy metals were analyzed via ICP. Three IDEXX quantification systems were used to detect E. coli, Enterococcus, and P. aeruginosa as fecal indicators or potential threats to public health. Potential fecal sources were analyzed using quantitative PCR targeting Bacteroides DNA markers for total, human, and bovine feces (Allbac, HF183, and CowM2, respectively). The NIWTP effectively removed chemical and biological contaminants. The lowest E. coli counts occurred at the site located at the NIWTP outfall (mean = 5 MPN/100ml) while the highest counts (mean = 348 MPN/100 ml) came from Nogales Wash, a tributary receiving untreated flow from Nogales, Mexico. The Allbac marker was detected in all samples, while approximately 97% of samples tested positive for HF183 and 33% tested positive for the CowM2 marker. Continued monitoring of effluent effects on river quality and evaluation of water quality degradation will lead to improvements in the management of Arizona's riparian areas and will ultimately contribute to healthy water bodies.

The dryland ecosystems of the US Desert Southwest (SW) are dependent on soil moisture for aboveground productivity; the generation of soil moisture in the SW is dependent on both soil physical properties and climate forcing. This study is one of the first regional point-scale analyses that explores the role of soil physical properties in modulating aboveground vegetation dynamics in response to climate forcing in the SW. Soil texture accounted for significant differences in average aboveground primary productivity across the SW. However, soil texture could not account for differences in inter-annual aboveground productivity variation across the SW. Subsurface soil texture was tightly coupled with precipitation seasonality in accounting for differences in long-term average seasonal aboveground productivity in the Mojave and Sonoran Deserts. The results of this study indicate that the subsurface is a significant factor in modulating aboveground primary productivity, and needs to be included in future modeling exercises of dryland ecosystem response to climate forcing and change.

I estimated patterns of shorebird abundance and species diversity in the Colorado River Delta and Upper Gulf of California wetlands in order to determine the relative contribution of intertidal wetlands and non-tidal anthropogenic wetlands to support shorebird habitat use. Species richness varied from 15 to 26 species among sites and 29 species were detected across sites. Density during the peak migration month was higher at the anthropogenic wetland Cienega de Santa Clara (mean = 168 ind/ha, 95% C.I. 29-367), and the intertidal Golfo de Santa Clara (mean = 153 ind/ha, 95% C.I. 17-323). Anthropogenic wetlands (playa and lagoons) supported high abundance of shorebirds along with intertidal wetlands in the Colorado River Delta (mudflats). In contrast, intertidal wetlands farther south on the Sonoran Coast presented lower abundance but higher diversity of shorebird, likely as a result of the higher diversity of habitats (rocky shore, sandy beach, estuary). I modeled water management scenarios for the Cienega in order to determine the response of the dominant vegetation (southern cattail, Typha domingensis Pers.) and the area of the outflow pool below the marsh to different scenarios of water management. The model indicates that if the inflow rate is reduced below the current 4-5 m³s⁻¹ the vegetated area of the Cienega that supports habitat for marsh birds would decrease in proportion, as would the area of the outflow pool in the Santa Clara Slough identified previously as shorebird habitat. Increases in salinity will also reduce the vegetated area due to the low salt tolerance of T. domingensis. In winter about 90% of inflow water exits the Cienega into the Santa Clara Slough due to low evapotranspiration contributing to inundate areas that are used by wintering and migrating shorebirds. Lastly, I explored the feasibility of using Vegetation Indices (NDVI and EVI) to model Yuma Clapper Rail detections in the Cienega de Santa Clara as well as the effects of adding other habitat variables and the presence of fire events in the performance of linear models based on NDVI. Both NDVI and EVI were positively related to the Yuma Clapper Rail detections. The relationship was weak to moderate, but significant (P<0.001), which suggests other factors besides the vegetation condition play an important role in the bird distribution pattern. A model including all the variability among years was a better predictor of the rails detected per transect, than models for fire and non-fire years. We did not find a significant effect from adding habitat features (water % or vegetation %), and we recommend to include variables at both microhabitat level and landscape level, relevant before and during the breeding season in order to increase the explanatory power of models.

The air-water interface in variably saturated porous media is recognized to influence interfacial retention of organic and inorganic contaminants, and mediate various mass-transfer processes. The formation and presence of water films commonly solvating the surfaces of soil/sediment grains in unsaturated systems, as well as their impact on flow and retention processes have been of sustained interest. X-ray microtomography was used to measure air-water interfacial area at multiple wetting-phase saturations for natural porous media. First, a study was conducted to evaluate image-processing procedures suitable for characterizing fluids and associated interfaces in natural porous media. A simple method was developed for the analysis of all phases in the system, using global threshold for phase identification and combination of binary files (M1). This method was then compared to a simultaneous multiphase segmentation approach using locally adaptive threshold selection (M2). Both methods were used to process data sets comprised of multiple drainage steps for water-saturated packed columns imaged via synchrotron x-ray microtomography. The results of both methods were evaluated based on comparison of values determined for porosity and specific solid surface area to independently measured porosity and specific solid surface areas. The results show both methods are suitable for determination of total air-water interfacial area, which requires characterization of only the non-wetting phase. Conversely, determination of capillary interfacial area requires characterization of all phases present and thus, is more sensitive to the challenges associated with image processing. The simultaneous multiple-phase segmentation (M2) method provides an integrated and consistent analysis of the phases, and anticipated to improve water-phase detection. Using the advanced segmentation approach, the air-water interfacial area is presented as a result of direct measurement of contact areas between the two fluids. This is in contrast to previously reported data, which were derived indirectly from calculations based on individually measured phase surface areas and conceptualizations of fluid distributions. The effects of these assumptions on the capillary interfacial behavior are evaluated. Results from this study confirmed the initial hypothesis that the behavior of fluid surface areas will affect the theoretical shape of the capillary curve. The results support the understanding of the capillary interfacial area behavior in response to changes in the configuration of fluid surface areas during a drainage cycle. Furthermore, results for the measured air-water interface allows for further identification of fluid domains, such as the relationship between film interfacial area, capillary domains (menisci), and the total-measurable interfacial area. Experiments were also conducted using aqueous-phase interfacial partitioning tracer tests for comparison. Results support the hypothesis that different methods provide characterization of different interfacial domains. Overall, this study provides an imaging-based approach for evaluation of water configuration, and presents a measurement-based framework for further understanding of the role of fluid-fluid interfaces in natural porous media.

The critical zone is the interface between abiotic and biotic constituents that spans from the vegetation canopy through the groundwater and represents an open system shaped by the climate, topography, and vegetation communities of a given environment. Four studies were completed to examine soil development, specifically mineral weathering and soil carbon storage, across semiarid sites spanning the Santa Catalina Mountain Critical Zone Observatory (SCM-CZO). The Santa Catalina Mountain Critical Zone Observatory is located along an environmental gradient in southern Arizona where co-varying climate and vegetation community properties have generated distinct changes in soil development across a relatively short distance (<20 miles). Soil, saprock, and parent rock were sampled on north-facing slopes from five climate-vegetation zones spanning desert scrub to mixed conifer forest. Within each climate-vegetation zone, samples were collected from two divergent summit and two convergent footslope landscape positions to account for topographic controls on mineral transformation. In the first study, the soil morphologic, physical, and chemical properties collected for all samples were combined with profile development indices to quantify soil variation with landscape position across the SCM-CZO. The results of this research demonstrated that climate and landscape position exert significant control on soil development in semiarid ecosystems, and that the profile development index is an effective tool for detecting these regional to hillslope scale variations in soil properties. The second study consisted of a cross-scale analysis of feldspar mineral transformation across the selected research sites to connect measures of pedon-scale soil development, depletions of feldspar and sodium in bulk soil, and elemental losses across feldspar grains at the microscale. Results indicated that greater soil development in the mixed conifer pedons corresponded to increased total feldspar and sodium losses. Desert scrub soils presented less evidence for feldspar transformation including lower profile development indices, gains in total feldspar percentages attributed to dust deposition, and less Na chemical depletion at the microscale. Greater soil development in convergent positions relative to adjacent divergent sites was consistent across all sites, with the highest degree of total feldspar depletion occurring in the conifer convergent locations. The third study focused on the physical distribution and mean residence time of soil organic carbon (SOC) in the SCM-CZO soils described for the first two studies. Surface (0-10 cm) and subsurface (30-40 cm) samples were collected from the aforementioned granitic regolith profiles. The soils were characterized using total C and N, δ¹³C, Δ¹⁴C, and radiocarbon derived mean residence time (MRT) estimates of bulk soil and physically separated C fractions to quantify SOC change with climate, vegetation, and landscape position. The results document a shift in SOC stabilization mechanisms across bioclimatically distinct ecosystems from mineral-associated SOC in the desert scrub soils to a mixture of mineral and occluded SOC in the conifer soils. Soils in the convergent landscapes concentrated the most SOC and typically exhibited the longest residence times across all locations. The fourth study examined the geochemical and mineralogical properties of the SCM-CZO soils across regional and hillslope scales of study to quantify soil development in semiarid environments. X-ray fluorescence and x-ray diffraction were used to characterize the elemental and mineralogical properties of the soils and parent material. Desert scrub dust samples were analyzed using x-ray fluorescence. The results indicate that mineral and base cation depletion were greatest in the convergent landscape positions at both sites and increased from the hot, moisture-limited desert scrub sites to the wetter, more productive conifer ecosystems. Enrichments in mica and select elements (i.e., Fe, Mg) suggested that dust deposition was a significant contributor to soil development across all sites. Geochemical estimates of dust fraction inputs confirmed this finding with dust composing up to 35% of the regolith material in the mixed conifer convergent soils. Clay mineral assemblage was dominated by halloysite and smectite minerals in the desert scrub site, reflecting complex climatic and mineral microtextural interactions in the dry, silica-rich desert environment. Clay minerals at the mixed conifer site exhibited the greatest degree of mineral transformation in the SCM, consisting of vermiculite, illite, kaolinite, and minor amounts of smectite and gibbsite. These findings confirm the interactive role of climate, vegetation, and landscape position in shaping the critical zone, where greater moisture availability and biological production are likely driving increased soil organic carbon storage and mineral weathering across various scales of study.

Heavy metals have been known to possess antimicrobial properties against bacterial, fungal, and viral pathogens. Silver and copper in particular have been used for millennia to control bacterial and fungal contamination. Metal nanoparticles (aggregations of metal atoms 1-200 nm in size) have recently become the subject of intensive study for their increased antimicrobial properties due to their increased surface area and localized release of metal ions when attached to pathogens. In the current studies, metal and metalhalide nanoparticles including silver (Ag), silver bromide (AgBr), silver iodide (AgI), and copper iodide (CuI) nanoparticles were evaluated for their antibacterial efficacy against two common bacterial pathogens. All of the nanoparticles significantly reduced bacterial numbers within 24 hours of exposure and were more effective against the Gram-negative Pseudomonas aeruginosa than the Gram-positive Staphylococcus aureus. CuI nanoparticles were found to be highly effective, reducing both organisms by >4.43 log₁₀ within 15 minutes at 60 ppm Cu. CuI nanoparticles were selected for further evaluation against a range of microorganisms to determine their broad spectrum efficacy. CuI nanoparticles formulated with different stabilizers (sodium dodecyl sulfate, SDS; PVP) were tested against representative Gram-positive and Gram-negative bacteria, Mycobacteria, a fungus (Candida albicans), and a non-enveloped virus (poliovirus). Both nanoparticles caused significant reductions in most of the Gram-negative bacteria within five minutes of exposure (>5.09-log₁₀). The Gram-positive bacterial species were more sensitive to the CuI-SDS than the CuI-PVP nanoparticles. Likewise, C. albicans was also more sensitive to the CuI-SDS than the CuI-PVP nanoparticles. In contrast, the acid-fast Mycobacterium smegmatis was more resistant to the CuI-SDS than the CuI-PVP nanoparticle solutions (2.54-log₁₀ vs. 3.80-log₁₀ after 30 minutes). Poliovirus was more resistant than the other organisms tested except for Mycobacterium fortuitum. M. fortuitum was more resistant to both CuI nanoparticle solutions than any of the other organisms tested, requiring longer exposure times to achieve comparable reductions (~4.15 log₁₀ after 24 hours). As an example of a real world antimicrobial application, polymer surface coatings with embedded CuI nanoparticles were investigated to determine their potential use as self-disinfecting surfaces. Brushed polyurethane, spincoated acrylic, and powder coated polyester-epoxy coatings containing various concentrations of CuI nanoparticles were tested for antibacterial efficacy against P. aeruginosa and S. aureus. Polyester-epoxy powder coatings were superior to the other coatings in terms of uniformity and stability under moist conditions and displayed antimicrobial properties against both organisms (>4.92 log₁₀) after six hours at 0.25% Cu. Polyester-epoxy coatings were selected for more rigorous testing under adverse conditions. These surfaces were negatively impacted when tested under dry conditions with high organic content, with organic content appearing to have a greater impact on antimicrobial efficacy. At 0.25% Cu, the antibacterial activity of the powder coatings was not impacted by washing with several commercial cleaners; however, at concentrations of 0.05% Cu, antibacterial activity was reduced by multiple washings with water, Windex®, and Pine Sol®. Additionally, ultrasonic cleaning of the coatings appeared to decrease their antimicrobial efficacy. Despite this, CuI nanoparticles were found in all studies to have great potential as a new class of fast-acting, broad-spectrum antimicrobial.

Ecosystem changes from grassland to shrubland in the Rio Grande Plains are thought to have negative effects on the hydrology of the region. The increase in woody plants, known as woody encroachment, may alter the amount of water moving beyond the root zone of plants. Water moving beyond the root zone is referred to as deep drainage, and has potential to become aquifer recharge. A vegetation manipulation project was designed to understand the effects of woody vegetation removal on soil water dynamics in the recharge zone of the Carrizo-Wilcox aquifer of south Texas. The primary objective of the project was to determine the potential to increase groundwater recharge through woody vegetation removal. To understand the effects of vegetation removal on various soil textures we studied changes in soil water, rooting depth, and the role of water redistribution by woody vegetation. Woody vegetation was removed using common methods of cut-stump and roller chop across three soil types. Soil water contents and changes were measured using neutron moisture meter to a depth of 180 cm. Average rooting depth was determined across three soil types. Soil and stem water stable isotopes were used to understand soil water movement. Rooting depth was determined to between 140 and 160 cm for all soil textures. Soil water content and changes were analyzed at three depth increments: 0-60, 60-120 and 120-180 cm. ANOVA analysis showed that there was no treatment response in average soil profile water in the sandy or sandy loam soils. There was a significant decrease in soil profile water for clay loam soil in response to roller chopping. Changes in soil profile water were the greatest in the sandy roller chopped soils. Below 120 cm, three months had significant differences in change in soil water in the sandy roller chop plot. During dry conditions, Honey mesquite shifts water use to deeper in the soil profile. In clay loam soils under dry conditions there is evidence of water being moved up from below 2 m soil depth to drier shallow soils. Roller chopping in sandy soils is the vegetation removal treatment and soil type most likely to result in water moving beyond the root zone. Although treatments had significant effects on soil moisture dynamics that interacted with soil type, we did not find support for deep drainage effects over the Carrizo-Wilcox aquifer from woody vegetation removal.

No description available.

Agricultural scientists are faced with the challenge of producing enough food for the increasing world population. Hence the need to develop tools for managing soil and plant systems to increase food production in order to meet the world food demand in the future. Crop simulation models have become promising tools in predicting yield and related components fi'om a set of weather, soil, plant and management data inputs. This study describes the estimation of solar radiant density, a crucial input in crop simulation models; calibration and validation of a soil-plant growth simulator, CropSyst, for management purposes; and generation of weather data for assessment of crop production under possible climate changes in the future. Daily solar radiant density, an input required by most crop simulation models, is infiequently observed in many stations. This may prevent application of crop simulation models for specific locations. Long-term data records of daily minimum and maximum air temperatures, precipitation, sunshine hours and/or solar radiant density were obtained for Cedara, Durban, Seven Oaks and Ukulinga in KwaZulu-Natal, South Africa. Solar radiant density was estimated fi'om sunshine hours using the Angstrom equation and ten other models that involved daily minimum and maximum air temperatures and/or precipitation along with extratelTestrial radiant density. Coefficients for the Angstrom equation and one of the other ten models were specifically developed for South African conditions; the remaining models required fitting coefficients using the available data for all locations. The models were evaluated using (i) conventional statistics that involved, root mean square elTor (RMSE) along with its systematic and unsystematic components, slope, intercept, index of agreement (d), and coefficient of determination (R\ and (ii) a fuzzy expert system that involved a single modular indicator (Ira d) aggregated from the modules of accuracy (aggregation of the indices relative RMSE, model efficiency and I-student probability), con'elation (Pearson's correlation coefficient) and pattem (aggregation of pattem index vs day of year and pattem index vs minimum air temperature). For each index, two functions describing membership to the fuzzy subsets Favourable (F) and Unfavourable (V) were defined. The expelt system calculates the modules according to both the degree of membership and a set of decision rules. Solar radiant density estimated from sunshine hours for the Durban station resulted in R2 , RMSE (MJ m,2) and d index of 0.90, 2.32 and 0.97 respectively. In the absence of observed solar radiant density data, estimations from sunshine hours were used for derivation of coefficients as well as evaluation of the models. For Durban, the performance of the models was generally poor. For Cedara, Seven Oakes and Ukulinga two of the models resulted in a high d index and smallest systematic RMSE. The solar radiant density estimated from each model was also used as an input to simulate maize grain yields using the soil-plant growth simulator, CropSyst. The models were ranked according to their ability to simulate grain yields that match those obtained from using the observed solar radiant density. The rankings according to crop simulation, conventional statistics and expert system were compared. The CropSyst model was also evaluated for its ability to simulate crop water-use of fallow and cropped (oats, Italian ryegrass, rye and maize) plots at Cedara, KwaZulu-Natal, South Africa. Soil characteristics, initial soil water conditions, irrigation and weather data were inputted to CropSyst. Crop input parameters for oats, Italian ryegrass and rye were used, with little modifications, as determined from field experiments conducted at Kromdraai open cast mine, Mpumalanga province, South Africa. Crop input parameters for maIze were either determined fi'om field experiments or taken from CropSyst crop input parameters documentation and adjusted within a narrow specification range of values as dictated by CropSyst. The findings indicated that CropSyst was generally able to simulate reasonably well the water-use of fallow and cropped (oats, Italian ryegI°ass, rye and maize) plots; leaf area index and crop evapotranspiration of rye; and grain yield and developmental stages of maize. The validated CropSyst model was also used to simulate timing and amount of irrigation water, and investigate incipient water stress in oats, Italian ryegrass and rye. The CropSyst model was used to investigate potential effects of future climate changes on the productivity of maize grain yields at Cedara, KwaZulu-Natal, South Africa. The effect of planting date (local planting date, a fortnight earlier and a fortnight later) was also included in the study. A 30-year baseline weather data input series were generated by a stochastic weather generator, ClimGen, using 30 years of observed weather data (l971 to 2000). The generated weather data series was compared with the observed for its distributions of daily rainfall and wet and dry series, monthly total rainfall and its variances, daily and monthly mean and variance of precipitation, minimum and maximum air temperature, and solar radiant density. Four months of the year failed to reproduce distributions of wet and dry series, daily precipitation, and monthly variances of precipitation of the observed weather data series. In addition, Penman-Monteith reference evaporation (ETa) was calculated using the observed and generated data series. Cumulative probability function of ETa calculated using the generated weather data series followed the observed distribution well. Moreover, maize grain yields were simulated using the generated and observed weather data series with local, a fortnight earlier and a fortnight later planting dates. The mean simulated grain yields for the respective planting dates were not statistically different from each other; the grain yields simulated using the generated weather data had significantly smaller variance than the grain yields simulated using the observed weather data series. When the generated weather data series was used an input, the early planting date as compared to the locally practiced and late planting dates resulted in significantly greater simulated grain yields. The grain yields simulated using the observed weather data for the early and local planting dates were not statistically different from each other. The baseline period was modified by synthesized climate projections to create future climatic scenarios. The climate changes considered corresponded to doubling of [C02] from 350 to 700 ~t1 ,-I without air temperature and water regime changes, and doubling of [C02] accompanied by increases in mean air temperature and precipitation changes of 2 (lC and 10%, 2 (le and 20%>, 4 °c and 10%, and 4 (lC and 20% respectively. Solar radiant density was also estimated from daily air temperature range for all scenarios that involved change in mean air temperature. In addition, input crop parameters of radiation-use and biomass transpiration efficiencies were modified for maize, in CropSyst, to accommodate changes in elevated levels of [C02]. Equivalent doubling of [C02], without air temperature or water regime changes, resulted in increased simulated grain yields as compared to the baseline period. Adding 2 QC to the mean daily temperature and 10% to the daily precipitation of a [C02] elevated atmosphere reduced the grain yield but still kept it above the level of the baseline period grain yield. Adding 4 QC to the mean daily temperature and 10% to the daily precipitation fLllther decreased the yield. Increasing the daily precipitation by 20% instead of 10% did not change the simulated grain yield as compared to the 10% increments. Early planting date, for all scenarios, also resulted in higher yields, but the relative increment in grain yield was higher for the late planting dates with scenarios that involved increment in mean air temperature. In general, this study confi1l11ed that doubling of [C02] increases yield but the accompanied increase in mean air temperature reduces yield. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.