Adsorción de boro del agua

En el siguiente trabajo se propone la técnica de la adsorción mediante la utilización de polímeros naturales para eliminar el boro de residuos industriales, puesto que estos residuos presentan una gran problemática medioambiental. El biopolímero con el que se trabajó fue el quitosano, modificado químicamente, éste se usó para pruebas de adsorción de boro en soluciones acuosas de concentraciones de 5 y 50 ppm de boro. Dichas pruebas se basaron en dos fases de experimentación. La primera fase consistió en poner en contacto las soluciones con perlas de quitosano-níquel de fabricación propia siguiendo un determinado protocolo, dicha fase constó de dos etapas, es decir que se realizaron las mismas pruebas dos veces para tener un mayor número de resultados y para corregir posibles errores de análisis. La segunda fase consistió en poner en contacto las soluciones con perlas de alginato ya fabricadas, disponibles en el laboratorio. Culminadas ambas fases de experimentación se midió la concentración de boro por espectrofotometría de absorción molecular y la concentración de níquel por espectroscopia de absorción atómica. En ambos casos se obtuvieron resultados satisfactorios, en cuanto al boro se logró remover hasta valores por debajo del límite permisible para consumo humano que establece la normativa europea (1 ppm) y lo que recomienda la Organización Mundial de la Salud (0.5 ppm), y en algunos casos se logró remover totalmente dicho metaloide. En cuanto al níquel se logró remover hasta valores por encima del límite permisible para consumo humano, pero por debajo del límite permisible para los vertidos provenientes de la industria. Finalmente, se le dio una posible utilidad o aplicación a este proyecto, relacionándolo con la reducción de boro del agua de mar, teniendo en cuenta la problemática que presenta el agua desalinizada respecto a su alta concentración de boro y su aplicación como agua de riego. También, en esta ocasión se obtuvieron resultados satisfactorios, logrando remover el boro a valores por debajo de 0.3 ppm, esta cifra se refiere a las cosechas más sensibles al boro (árboles frutales de cítricos), las cuales presentan daño foliar a concentraciones de boro en el agua de riego mayores a 3 ppm

Alaskan Arctic epibenthic communities: distribution patterns, links to the environment, and brittle star population dynamics

Thesis (Ph.D.) University of Alaska Fairbanks, 2016The Arctic marine shelves are characterized by areas of high and low invertebrate standing stock and communities that vary spatially in patches. Large-scale environmental characteristics, such as the distribution of water masses, the fenology of sea ice cover, and variability of water depth define changes in epibenthic community structure throughout the Arctic shelves. The longevity and relatively low mobility of epibenthic invertebrates make them especially relevant as indicators of long-term environmental patterns. In terms of standing stock and biomass, the most representative group among Arctic epibenthic taxa are brittle stars. Large areas of the Arctic shelves have dense assemblages of brittle stars; however, despite their ecological importance for Arctic shelf systems, little is known of their age, growth and turnover rates. The research developed through this dissertation examined how environmental drivers influence epibenthic invertebrate communities of the Alaska Arctic shelves and the population parameters of the dominant brittle star species. The first chapter of my dissertation focused on the northeastern Chukchi Sea and the second one focused on the Alaskan Beaufort Sea. The overarching questions addressed in chapters 1 and 2 focused on characterizing the epibenthic communities of the Alaskan Chukchi and Beaufort seas and defining environmental characteristics that influence the community structure. To answer this question, biological and environmental data were collected and analyzed in 2009 and 2010 in the Chukchi Sea, and in 2011 in the Beaufort Sea. For my third chapter, the overarching question was: what is the predictive power of the seasonality of sea ice for epibenthic community structure in the Alaskan Arctic, and how does it compare to more commonly used environmental descriptors. To test this relationship, six variables depicting the patterns of the seasonality of sea ice were computed from passive microwave sea ice concentration data. For the fourth chapter, the overarching question was, what are the population parameters of the two dominant brittle star species of the Alaskan Arctic. For this analysis, individuals of Ophiura sarsii and Ophiocten sericeum were collected in 2013 for age and organic mass determination. Findings of this research indicate that epibenthic communities have a patchy distribution with one or a few taxa dominating the community over large spatial extents. In both the Chukchi and Beaufort seas, communities were dominated by either crustaceans or echinoderms. Only in the mid-depth stations of the Beaufort Sea were both groups equally abundant. The environmental measure that best correlated to epibenthic commuity structure in both regions was longitude. Biologically relevant variables, such as sediment grain size, sediment phaeopigments, bottom water temperature and salinity, though region specific, were also important drivers of commuity structure. As predictors of epibenthic community structure, sea ice variables resulted in moderate to high correlation values. In the Beaufort Sea, sea ice variables performed better than traditionally used environmental descriptors; however, this was not the case for the Chukchi Sea. This study is the first to report on the age, growth and turnover of Arctic brittle stars. The asymptotic age was higher for O. sarsii than for O. sericeum; however, both species had significantly higher maximum ages than temperate region congeners. The individual production of O. sarsii surpassed that of O. sericeum by an order of magnitude throughout the size spectra. As a whole, this research highlights the complexity of the biological-environmental interactions that create the large spatial variability in community structure, benthic biomass and diversity throughout the Alaska Arctic. The variability in community structure throughout the Chukchi and Beaufort seas was linked qualitatively to large-scale environmental patterns. Quantitatively, these environmental forces were represented by the date of sea ice return and date of sea ice retreat in the Beaufort Sea. The predictive power of sea ice variables was reduced in the Chukchi Sea by the large inter-annual variability in wind direction and intensity that in turn affect the pattern of seasonality of sea ice. As integrators of large-scale environmental patterns, sea ice variables proved useful as additional predictors of epibenthic community structure. The dominant shelf brittle star species do not experience short-term fluctuations in population size. Top-down and bottom-up controls on these populations, such as predation and food supply, may be governing their growth strategy and total annual growth. Considering the longevity and slow growth of many Arctic epibenthic species such as brittle stars, the recovery after disturbance could require decades to restore high biomass in some areas. Environmental changes associated with climate change and resource development in the Arctic shelves have the potential to create large changes in the benthic system, such as local changes epibenthic community composition, dominant taxa, community diversity and benthic biomass hotspots. Future research focusing on the biological interactions that influence epibenthic communities, the supply and success of new recruits to the benthos and the temporal stability of epibenthic communities would help complete our understanding of the spatial and temporal variability of Arctic epibenthic communities and make solid predictions of future scenarios.General introduction -- CHAPTER 1: Epibenthic community variability in the northeastern Chukchi Sea -- CHAPTER 2: Spatial variability of epibenthic communities on the Alaska Beaufort Shelf -- CHAPTER 3: What lies beneath the ice: relating seasonal sea ice patterns with benthic shelf fauna in the Alaska Arctic -- CHAPTER 4: Growth and production of the brittle stars Ophiura sarsii and Ophiocten sericeum (Echinodermata: Ophiuroidea) in the Alaskan Arctic -- Summary and conclusion

Associations of HIV Risk Behaviors among Older Latinas and their Adult Daughters

This dissertation examines the associations between adult Latina daughters’ HIV risk behaviors and that of their older Latina mothers’ HIV risk behaviors. The central hypothesis of the study is that adult Latina daughters’ influence their older mothers’ behaviors and that such behaviors interact with the level of their attachment. Older Latinas are a vulnerable population that face cultural risk factors, health care provider bias, and engage in low rates of HIV testing. The primary mode of HIV infection for Latinas is through heterosexual contact. Yet, traditional gender norms such as marianismo belief place pressure on Latina women to be submissive to their partners, disregard their infidelities, and not attempt to negotiate condom use, increasing the risk of HIV infection among Latinas via heterosexual sex with their primary partners. Efforts by the CDC to increase HIV testing have emerged as a critical part of HIV prevention. However, research has indicated that older Latinas are less likely to speak to a health care provider about safe sex practices or HIV testing than their younger counterparts. Despite health care providers having strong influences over Latinas’ decisions to perform health related tests, physicians are not endorsing HIV testing for their older patients. This in part, leads to a disproportionate number of late stage diagnoses among older adults. Evidence suggest that adult daughters are a source of support and assistance in health-related issues for their aging mothers and are uniquely positioned to influence their mothers’ health-related behaviors and decisions. Additionally, mother-daughter attachment has been found to be a protective factor to other risky health behaviors. The present study (1) Examined the association between recurrent HIV risk behaviors of adult Latina daughters and those of their older Latina mothers and (2) examined the moderating effect mother-daughter attachment have on those associations. No statistical significance was found in examining the association between adult Latina daughters and their older mothers, nor was attachment found to be a moderator on those associations. Findings show culture may be the significant factor influencing the lack of association between adult Latina daughters and their older mothers. Results add to the literature and scientific field of social work and public health. Additionally promoting studies on cultural barriers that may exist in adult Latina daughter and older mother upward communication as techniques to promote healthy behaviors among older Latinas

Free energy and vibrational entropy difference between ordered and disordered Ni3Al

We have calculated free energy and vibrational entropy differences in Ni3Al between its equilibrium ordered structure and a disordered fcc solid solution. The free energy and entropy differences were calculated using the method of adiabatic switching in a molecular-dynamics formalism. The path chosen for the free-energy calculations directly connects the disordered with the ordered state. The atomic interactions are described by embedded-atom-method potentials. We find that the vibrational entropy difference increases with temperature from 0.14kB/atom at 300 K to 0.22kB/atom at 1200 K. We have calculated the density of states (DOS) of the disordered phase from the Fourier transform of the velocity-velocity autocorrelation function. The disordered DOS looks more like a broadened version of the ordered DOS. Analysis of the partial density of states shows that the Al atoms vibrations are most affected by the compositional disorder. The phonon partial spectral intensities along the 〈100〉 direction show that the vibrational spectrum of the disordered phase contains intensities at optical mode frequencies of the ordered alloy. We find that the volume difference between the ordered and disordered phases plays the most crucial role in the magnitude of the vibrational entropy difference. If the lattice constant of the two phases is set to the same value, the vibrational entropy difference decreases to zero

Assessment of the microbiome associated with endangered orchids

The Orchidaceae (orchid family) is perhaps the most speciose group of flowering plants with approximately 25,000 described species and many thousands of hybrids. While certain mycorrhizal fungi are required for orchids to germinate, these mycorrhizae form just part of a microbial community that interacts with the plant. In this study, we sought a broader picture of the microbiome associated with these plants. A major motivation for our work is the concern that the gaps in our understanding of orchid microbiomes might have important consequences when decisions are made in the management of species of conservation concern. Because of the complexity of their symbiotic interactions, orchids are particularly at risk when faced with habitat loss or the potential effects of climate change. We studied two species of endangered terrestrial orchids in Missouri and, using DNA collected from soil and high throughput sequencing, evaluated the bacterial microbiome associated with these two orchid species.Includes bibliographical reference

Estratificación de la información ambiental y construcción de bioindicadores: identificación de áreas prioritarias para la conservación de la biodiversidad.

Las regiones naturales de la provincia de Córdoba presentan diversos ecosistemas que están afectados por un constante deterioro ambiental siendo degradadas por la deforestación, el avance de la frontera agropecuaria, los incendios rurales, la introducción de plantas exóticas, el sobre-pastoreo, las sequías prolongadas, y el crecimiento urbano de las villas turísticas. La biodiversidad permite que los ecosistemas tengan mayor resiliencia ante cambios climáticos o antrópicos, siendo de suma importancia para mantener los servicios ecosistémicos. La experiencia adquirida por el equipo de trabajo del CREAN en el monitoreo de sitios pilotos a través del proyecto LADA/FAO mediante la metodología WOCAT, para la evaluación de la degradación de la tierra y los usos de la tierra sirve de antecedente tecnológico para encarar este proyecto multidisciplinario en red. El producto a obtener es una cartografía multicapa sobre los usos de la tierra (LUS), en la región de las Sierras Chicas de Córdoba en donde queden delimitadas las áreas naturales conservadas, las zonas explotadas con un uso sustentable, las áreas degradadas con procesos de desertificación, el estado de las cuencas proveedoras de agua a ríos y embalses, como así también las zonas urbanas y de explotaciones agropecuarias o mineras. Sobre la base de esta evaluación de bioindicadores y estratificación de la información ambiental se puede proveer de información a decisores sociales y políticos para que establezcan medidas que contribuyan a realizar acciones que protejan el ambiente, promuevan el manejo sustentable de las tierras y establezcan normativas para la conservación del suelo, el agua y la biodiversidad