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With the ongoing need for water conservation, the American Southwest has worked to increase harvested rainwater efforts to meet municipal needs. Concomitantly, environmental pollution is prevalent, leading to concerns regarding the quality of harvested rainwater. Project Harvest, a co-created community science project, was initiated with communities that neighbor sources of pollution. To better understand how a participant's socio-demographic factors affect home characteristics and rainwater harvesting infrastructure, pinpoint gardening practices, and determine participant perception of environmental pollution, a 145-question "Home Description Survey" was administered to Project Harvest participants (n = 167) by project promotoras (community health workers). Race/ethnicity and community were significantly associated (p < 0.05) with participant responses regarding proximity to potential sources of pollution, roof material, water harvesting device material, harvesting device capacity, harvesting device age, garden amendments, supplemental irrigation, and previous contaminant testing. Further, the study has illuminated the idiosyncratic differences in how underserved communities perceive environmental pollution and historical past land uses in their community. We propose that the collection of such data will inform the field on how to tailor environmental monitoring efforts and results for constituent use, how community members may alter activities to reduce environmental hazard exposure, and how future studies can be designed to meet the needs of environmentally disadvantaged communities. [ABSTRACT FROM AUTHOR]

The saguaro cactus (Carnegiea gigantea [Engelm.] Britton & Rose) is a keystone species endemic to the Sonoran Desert of northern Mexico and the southwestern United States. The saguaro produces large white flowers near its stem apex (crown) during April–June, which bloom at night and close the following day. In 1924, Duncan Johnson reported that saguaro floral buds are likely to have an asymmetrical distribution in which buds occur in higher densities on the eastern half of a plant's crown. Using technology not available to Johnson, we tested his observations to determine whether flowers are asymmetrically distributed using repeat photography. We also tested whether there is a seasonal pattern of flowering that may explain Johnson's observations. We tracked intra‐individual flowering phenology of 20 saguaros and measured 2372 flowers across two reproductive seasons in Saguaro National Park, Tucson, Arizona. Flowers first appeared on the east side of all saguaro crowns at the start of the reproductive season, and then spread radially in a counterclockwise direction as the season progressed. In contrast to previous reports, saguaro flowers were consistently more abundant on the northern part of the crown than in the eastern part. To our knowledge, this study is the first to document a seasonal, counterclockwise pattern of asynchronous flowering in saguaro or any angiosperm. We discuss potential drivers of this phenomenon as well as implications for saguaros responding to climate change. [ABSTRACT FROM AUTHOR]

Fear of liability from the 1980 Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund) has prompted developers to build preferentially upon undeveloped green space rather than potentially contaminated former industrial sites, leading to urban sprawl in the suburban areas while blighted properties in the urban core remain vacant. A brownfield is defined as a property in which the presence or potential presence of a hazardous substance or contaminant poses a barrier to development. Agencies often create brownfield inventories by performing a site suitability analysis, using distinguishing features such as ecologically and culturally significant areas or neighborhoods that need revitalizing. Pima County, Arizona and the Sonora Environmental Research Institute, Inc. (SERI) developed a brownfield inventory of the large, industrial area directly to the west of Davis-Monthan Air Force Base. Because the brownfield target area has few residential neighborhoods and lacks the distinguishing features usually used in a brownfield site suitability analysis, the county and SERI used the official tax assessor database and 11 federal, state and county environmental databases to develop a brownfield inventory. The goal of the project was to prioritize properties that stood to benefit from the grant funding. The final brownfield inventory contained 531 parcels. [ABSTRACT FROM AUTHOR]

A new thermocatalytic method to destroy chlorinated solvents has been developed in the laboratory and tested in a pilot field study. The method employs a conventional Pt/Rh catalyst on a ceramic honeycomb. Reactions proceed at moderate temperatures in the simultaneous presence of oxygen and a reductant (mixed redox conditions) to minimize catalyst deactivation. In the laboratory, stable operation with high conversions (above 90% at residence times shorter than 1 s) for perchloroethylene (PCE) is achieved using hydrogen as the reductant. A molar ratio of H2/O2= 2 yields maximum conversions; the temperature required to produce maximum conversions is sensitive to influent PCE concentration. When a homologous series of aliphatic alkanes is used to replace hydrogen as the reductant, the resultant mixed redox conditions also produce high PCE conversions. It appears that the dissociation energy of the C–H bond in the respective alkane molecule is a strong determinant of the activation energy, and therefore the reaction rate, for PCE conversion. This new method was employed in a pilot field study in Tucson, Arizona. The mixed redox system was operated semicontinuously for 240 days with no degradation of catalyst performance and complete destruction of PCE and trichloroethylene in a soil vapor extraction gas stream. Use of propane as the reductant significantly reduced operating costs. Mixed redox destruction of chlorinated solvents provides a potentially viable alternative to current soil and groundwater remediation technologies. [ABSTRACT FROM AUTHOR]

A strategy for accelerating the rate of transport of surfactant within a system by delivering the surfactant as a precursor to the surface-active state ("prosurfactant") and subsequently transforming it to a functional form (surfactant) is reported. An increase in the overall rate of transport of a redox-active surfactant across a polycarbonate membrane containing pores with a diameter of 10 nm is demonstrated. This redox-active molecule, which is molecularly dispersed in aqueous solutions in its oxidized state (prosurfactant), but assembles into globular micellar aggregates (Rh = 5 nm) in its reduced state (surfactant), was rapidly transported across the membrane in its oxidized state to a concentration of 0.2 mM. Subsequent delivery of ascorbic acid (a reducing agent) by diffusion through the same membrane led to reduction of the oxidized precursor and formation of surfactant and micelles. The sequential delivery of the prosurfactant and then transforming agent resulted in a greater than sixfold increase in the overall rate of delivery of surfactant as compared to a procedure in which the surfactant was diffused across the membrane. These observations are compared to calculations based on hindered diffusion through cylindrical pores. [ABSTRACT FROM AUTHOR]