1,720,997 research outputs found
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A Comprehensive Approach in Identifying Sources of Contamination, Understanding Water Quality Perception, and Translating Information through Community Outreach in the Upper Gila Watershed in Clifton, Arizona
No full textAs 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.Release 16-Apr-201
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Self-Sterilizing Harvesting Materials and Irrigation Pipelines
No full textFood production is a growing industry in Arizona making safe and sustainable practices for irrigating crops of the utmost importance. Harvesting materials such as knives, packing crates, plastic pallets and processing tables are constantly exposed to soil and other bacteria- laden environments presenting the risk for contamination. Irrigation pipelines are assembled using rubber gaskets to make a watertight seal. The gasket pipeline interface is a warm, moist environment that is subject to biofilm accumulation. Therefore, a long-term sanitization treatment of these materials would be greatly beneficial to the farms of Yuma, Arizona. Quaternary ammonium compounds and chlorine dioxide have proven to be sufficient household cleaning products. Our work examined the efficiency of these products as well as others in long- term sanitization of harvesting materials and irrigation systems. Treating materials with these compounds did not inhibit microbial growth or prevent biofilm accumulation in irrigation systems. The first study treated of harvesting materials (knives) with sanitization treatments. Samples were qualitatively analyzing the presence of Escherichia coli (E. coli) as an indicator bacteria and its ability to survive on the equipment after the equipment goes through three different treatments; water (as a control), QACs and bleach. The second study determined the efficacy of these treatments on packing materials such as wood, plastic and metal. Both studies found the treatment, given the contamination levels present in the study, was not an effective microbial control. The third study will quantified the presence of heterotrophic bacteria, E. coli and Salmonella as indicators of biofilm accumulation on irrigation pipeline gaskets. The same treatment methods were used for the gaskets that hold the irrigation pipelines together. The study determined that treating the gaskets did not inhibit the growth of biofilms and that pretreatment was not an effective microbial control. A field study determined that treatment residues did not affect the growth of spinach. The present research provides preliminary data to assist in the development of future studies
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Water Usage for Power Generation & Opportunities for Water Reuse Expansion a Study of Salt River Projects Water Usage
No full textIncreasing demands on limited water resources have made the use of recycled water an attractive option for extending potable water supplies. Recent actions towards the development of the Drought Contingency Plan require Southwestern states, and water users within the States, to develop a plan for more sustainable water usage from the Colorado River. Tasked with protecting the State’s valuable resources now and in the future, the Arizona Department of Water Resources (ADWR) regulates water users, including large-scale power generators, one of the largest waters, within the Active Management Areas (AMAs) through a set of Management Plans. Thermoelectric power generation, accounts for around 40 percent of total water withdrawals in the US; the largest volume of which is used for cooling (Dieter et al., 2018). While less than one percent of power plants in the US use recycled water, over 50 percent are located with ten miles of suitable reclaimed water supplies. By 2025, ADWR will require power plants that produce greater than 25 megawatts of electricity to meet a set of conservation requirements, including using zero liquid discharge systems and increasing cycles of concentration to reduce the volume of cooling tower makeup water. To incentivize the use of recycled water in power generation, the ADWR will provide exemptions for plants that beneficially reuse 100 percent of blowdown water from cooling towers or use reclaimed water for at least 50 percent of water used in cooling towers.
The purpose of this study was to identify opportunities for enhanced use of recycled water in power generation, specifically for a fleet of generating stations owned and operated by the Salt River Project (SRP). To help protect the State’s fresh water supplies, the Salt River Project (SRP) developed a set of Sustainability Goals, highlighting the need to increase the use of recycled water to become more water resilient. Action plans include, but are not limited to, reducing total groundwater mining in the State’s AMAs. Within the State’s five AMAs, reclaimed water production is estimated at 140,000 million gallons per year (MGY) of which only 25,000 MGY is used in power generation, the majority going to the Palo Verde Nuclear Generating Station. Because water and energy are inextricably linked, each relying on the other for production through to distribution, the adoption of this untapped potential can facilitate a more water resilient future for SRP.
Each SRP station was paired with one to three WRFs within a 25-mile radius. To evaluate potential partnerships, water usage and water quality needs of each station were assessed and compared to discharges from paired WRFs. Water usage data for cooling towers, spanning three years (2017-2019) for each station, was collated from the Energy Information Administration (EIA). Additional water usage and water quality data was obtained directly from each of the stations. Using a variety of sources, data from twelve WRFs were used to estimate potentially available reclaimed water based on volumes of produced treated effluent not already allocated for reuse and were used as the basis to identify and prioritize potential partnerships.
Total facility-wide water withdrawals, including groundwater, surface water, and recycled water, for all seven stations averaged 10,000 MGY. Average annual total groundwater withdrawals are approximately 7,600 MG (76%), surface waters 2,100 MG (21%), and recycled water 280 MG (3%). Groundwater withdrawals within the AMAs, used specifically for cooling towers, reaches nearly 3,000 MGY. While the goal of SRP is to reduce groundwater withdrawals within the AMAs by 8 percent (a reduction of 240 MGY), the potential for much greater reductions is possible.
Of the seven SRP stations assessed, five were identified as having the potential for reuse opportunities with at least one of the paired WRFs within a 25-mile radius having a supply of reclaimed water that met or exceeded the demand. The analysis indicates, based on distance and volume of supply, that recycled water could augment at least 35 percent of groundwater withdrawals (a reduction of nearly 1,050 MGY) within the AMAs alone. The potential for expanding reuse to augment all freshwater supplies, within and outside of the AMAs, is also possible and should be further investigated.
This study was a first step in identifying potential reuse partnerships between SRP and WRFs in Arizona. From this work, a report was provided to SRP and includes the full water usage and water quality assessment of the fleet of generating stations and WRFs, identified gaps in SRP data management and communications and recommendations for improvement, limitations to the study, challenges to reuse in power generation and recommendations to overcome them, and key next steps. In addition, all raw data was transferred to SRP. While there are many considerations for using recycled water in power generation, including water availability and quality; distance and geography between supply and demand; system requirements; and cost and regulatory requirements, the main objective was to provide SRP an overview of the fleet’s total water demands and water footprint to use as a framework to identify priority areas and viable opportunities for potential reuse partnerships with WRFs
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Efficacy of Chlorine and Peracetic Acid to Reduce Shiga Toxin-Producing Escherichia Coli and Impact of Simultaneous Nitrogen-Based Fertilizer Use on Microbial Die-Off in Preharvest Agricultural Water
No full textSeveral foodborne disease outbreaks in the United States have been linked to the consumption of various types of leafy greens in which irrigation water was suspected as the potential source of contamination. To reduce potential produce contamination from agricultural water, the U.S. Food and Drug Administration (FDA) has proposed regulations/metrics which would require growers to assess their agricultural water systems. In some cases, this would mean monitoring their water quality and taking corrective action, by way of antimicrobial treatments, when agricultural waters are deemed as a “reasonably likely foreseeable hazard”. Additionally, the Arizona and California Leafy Greens Marketing Agreements (AZ/CA LGMA) require growers utilizing surface water for overhead irrigation to treat their water within 21 days of harvest to meet acceptable risk indicators; generic Escherichia coli (E. coli) (non-detect per 100mL) and Total Coliform bacteria (<99 MPN/100mL). For many growers, this will be the first time that water quality data may necessitate them to use an antimicrobial treatment before irrigation can be applied safely. Additionally, growers are faced with a myriad of options related to antimicrobial water treatment with very little guidance on the most appropriate treatment option for their ranch, or the requirements needed for successful implementation. With limited guidance, water treatment decisions are likely to be unsuccessful and expend both excess time and money while seeing little to no reduction in potential pathogen loading in an agricultural water source and thus little to no reduction in microbiological risk. To provide guidance on antimicrobial agricultural water treatment options available to industry, the efficacy of two antimicrobial treatments Peroxyacetic Acid (PAA) and Calcium Hypochlorite (Cl) were tested, in triplicate. Tests were executed for various rates of each antimicrobial product (sanitizer), 6 & 8 PPM for PAA and 2 & 4 PPM for Cl. For each sanitizer at each PPM, tests were conducted at temperatures 12°C and 32°C. To evaluate sanitization efficacy, the team measured the reduction of a 109 CFU/mL cocktail of Shiga toxin-producing E. coli (STEC) strains (ATCC MP-9 and 43895) in four water sources from across the southwestern United States (Yuma and Maricopa, AZ, Uvalde and Edinburgh, TX). Four different water sources were used to gauge if water quality impacted sanitization efficacy. The experimental design was based on an EPA/FDA protocol to assess the efficacy of an antimicrobial product to reduce foodborne bacteria in pre-harvest agricultural water (https://www.fda.gov/media/140640/download) . This protocol dictates that STEC cocktail be added to agricultural water then equilibrated at either temperature (12°C or 32°C); post equilibration, each sanitizer, for each concentration, is injected into the mixed solution. The appointed contact time (1 or 5 minutes) is given and then the solution is neutralized and evaluated. To further growers’ comprehension of best management practices for successful antimicrobial treatment application, the impact of two nitrogen-based fertilizers (UAN32 and CAN17) on the efficacy of Sodium Hypochlorite 6% (chlorine) and PAA against naturally occurring coliforms was also evaluated. The first study provides evidence that chlorine meets EPA’s required 3-log reduction of pathogens in order to receive label approval. At a one-minute contact time, the chlorine treatment resulted in log reduction values (LRVs) ranging from 3.24 to 6.15 regardless of temperature, dose/PPM, or water source. PAA however did not perform as well with LRVs ranged from 0.0 to 1.10 with higher reduction occurring at the higher temperature and dose of PAA. When the contact time of PAA treatment was increased to five minutes, LRVs increased and ranges from 1.5 to 5.4 were observed; the efficacy of the sanitizer increased with increased solution temperature. Furthermore, the addition of nitrogen-based fertilizer to the water source in tandem with treatment application significantly affected the antimicrobial capabilities of chlorine. For chlorine, when applied unaccompanied an average log reduction of 3 logs was seen. However, LRVs decreased on average by 1.34 logs when fertilizer was introduced: with the greatest reduction in efficacy resulting in a nearly 2-log decrease. Contrarily, combined application of PAA and either fertilizer showed little to no interaction with a 0.4 log increase in disinfection efficacy when UAN32 was used. Results indicate that a prolonged contact time may be needed to meet regulations when PAA is used as an antimicrobial treatment. As well, growers must be cautious when applying fertilizer conjointly with antimicrobial treatment to their agricultural waters to ensure compliance with new proposed food safety metrics
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Microbial Source Tracking: Watershed Characterization and Source Identification
No full text8 pp
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La Calidad del Agua, E. coli y su Salud
No full textPublicación de Extensión de la calidad del agua y la protección de la salud humana
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Water Quality Assessment of the Santa Cruz River in Southern Arizona
No full textUtilization 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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