No description available.

<p>Arsenic (As) exposure via groundwater consumption is a global health problem affecting millions. Monitoring exposure is a key step in understanding and predicating future health outcomes. This thesis explores the relationships between arsenic concentrations in toenails and arsenic in water. Three case studies were investigated, with residents from: North Carolina, USA (n=103); the Rift Valley, Ethiopia (n=60); and the Mekong Delta, Vietnam (n=65). Arsenic concentrations above the WHO's recommended 10ppb limit were found in groundwater from the three research sites. </p><p>Arsenic in toenails was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). </p><p>In the Rift Valley of Ethiopia, 53% of the tested drinking wells (n=34) had As above the WHO's limit. Arsenic concentrations in toenails (n=60) were significantly correlated to As concentrations in groundwater (r=0.72; p<0.001), reflecting the direct exposure of rural communities to As in well water, which is their principle water source. Male minors (<18 years old) were found to have greater nail-As concentrations compared with adults consuming equal amounts of As (p<0.05). Estimated As dose specifically from drinking water sources was also associated with nail concentrations (p<0.01). </p><p>In the Mekong Delta of Vietnam (Dong Thap Province), 36 out of the 68 tested wells had As content above the WHO's recommended limit of 10ppb, with levels as high as 981 ppb. Arsenic contents in nails collected from local residents (n=62) were significantly correlated to As in drinking water (r=0.49, p<0.001). Demographic and survey data show that the ratio of As in nail to As in water varies among residents that reflects differential As accumulation in the exposed population. The data show that water filtration and diet, particularly increased consumption of animal protein and dairy and reduced consumption of seafood, were associated with lower ratios of As in nail to As in water and thus could play important roles in mitigating As exposure.</p><p>Sixty-one wells were tested from Union County, North Carolina, with 15 out of 61 wells exceeded the WHO's 10 ppb limit. Arsenic values ranged from below the limit of detection (0.07) to 130ppb, with a mean of 11ppb (median=1.5ppb). Nails were collected from county residents (n=103) and were statistically correlated with As-water concentrations (r=0.48, p<0.001). </p><p>Integration of the data from the three cases studies across different populations and ethnicities show high correlation between As concentrations in groundwater and As in nails in all the three locations (r(Union County)= 0.48, p<0.001; r(Ethiopia)=0.72 p<0.001; r(Vietnam)=0.49, p<0.001). For As-nail to As-water pairs in which As in water was above 1ppb, these three locations are statistically indistinguishable from one another (r=0.62, p<0.001, n=176). These results support the hypothesis that nails can be used as a biomarker of exposure regardless of geographic or ethnic differences in populations considered. Nutrition (meat, seafood, and milk consumption) rather than gender, ethnicity, or dose is suggested to be the major confounding issue affecting the magnitude of As exposure in the human body.</p> / Dissertation

Includes bibliographical references. / Cover title. "February 2003." 4/8/03: Also available via Internet.

<p> Many methods have been employed to study coastline change. These methods range from historical map analysis to GPS surveys to modern airborne LiDAR and satellite imagery. These previously used methods can be time consuming, labor intensive, and expensive and have varying degrees of accuracy and temporal coverage. Additionally, it is often difficult to apply such techniques in direct response to an isolated event within an appropriate temporal framework. Here we utilize a new ground based Canopy Biomass LiDAR (CBL) system built at The University of Massachusetts Boston (in collaboration with the Rochester Institute of Technology) in order to identify and analyze coastal change on Lovells Island, Boston Harbor. Surveys of a bluff developing in an eroding drumlin and beach cusps on a high-energy cobble beach on Lovells Island were conducted in June, September and December of 2013. At each site for each survey, the CBL was set up and multiple scans of each feature were taken on a predetermined transect that was established parallel to the high-water mark at distances relative to the scale of the bluff and cusps. The scans from each feature were compiled, integrated and visualized using Meshlab. Results from our surveys indicate that the highly portable and easy to deploy CBL system produces images of exceptional clarity, with the capacity to resolve small-scale changes to coastal features and systems. The CBL, while still under development (and coastal surveying protocols with it are just being established), appears to be an ideal tool for analyzing coastal geological features and is anticipated to prove to be a useful tool for the observation and analysis of coastal change. Furthermore, there is significant potential for utilizing the low cost ultra-portable CBL in frequent deployments to develop small-scale erosion rate and sediment budget analyses.</p>

<p> Mountain Lake is one of only two natural lakes in the state of Virginia. The lake's origin has been attributed to either a natural solution-collapse basin, or to a landslide damming the valley of northwesterly flowing Pond Drain, or to a NW-SE trending fracture lineation. The lake is located within the breached northwest limb of a gently plunging anticline, a part of the larger Valley and Ridge physiographic province. In recent years, the lake drained almost completely, exposing the lake bottom and revealing the presence of four sinkhole-like depressions, containing piping holes at their sides and bottoms, at the northeastern and northwestern margins of the lake. This study focuses on the most likely origin of large sandstone blocks present at the northern end of the lake in an area locally referred to as "Rock City", including mapping of the block locations and analyzing the mode and extent of displacement that they have undergone. An additional objective is to investigate the piping potential of the lake-bottom sediment and its role in seepage out of the lake basin causing lake-level fluctuations. </p><p> Mapping of Rock City was conducted by taking GPS readings at the corners of the rock blocks and using ArcMap Software. Investigations of the displacement mode of the rock blocks was done by comparing the measured orientations of principal discontinuity sets, forming the rock-block boundaries, with discontinuity orientations of undisturbed outcrops within the headscarp, using stereonet analysis. Grain size analysis, Atterberg limits, and a compaction-mold permeameter test were used to evaluate lake sediment's susceptibility to piping. </p><p> Field observations and discontinuity data analysis indicate that Rock City is a landslide that dammed the valley of Pond Drain, consequently forming the lake. The primary mode of slope movement involves lateral spreading that is associated with extension occurring along discontinuities. The Tuscarora Sandstone rock blocks comprising Rock City were detached from the scarp face along a northwest-southeast trending joint set and were displaced laterally towards the west. A seismic event appears to be the most likely triggering mechanism for slope movement. </p><p> Laboratory testing reveals that lake-bottom sediment is susceptible to piping, which is the primary mechanism responsible for the formation of the lake-bed depressions and lake-levels fluctuations. Grain size analysis reveals that lake-bottom sediment consists predominantly of fine sand and silt, both of which are highly susceptible to piping. Results of the compaction-mold permeameter test show that the hydraulic gradient at which lake-bottom sediment starts to pipe, the critical hydraulic gradient, ranges between 1 and 10, depending on the density, grain size distribution and cohesive properties of the sediment.</p>

<p> The basin-fill aquifers of the American Southwest host elevated concentrations of arsenic in groundwater due to the local geology. Limited information is available on arsenic dynamics in semi-arid and arid regions of the world. This study describes arsenic biogeochemistry and mechanisms of arsenic solubilization for a soil profile collected from the surface to the depth of groundwater in the Cache Valley Basin, Northern Utah. </p><p> The first objective was to delineate mechanisms of arsenic solubilization from sediments collected at the study site. Microcosms containing site groundwater and site-oxidized and site-reduced sediments, were monitored over time to observe changes in the solubilization and oxidation state of arsenic and changes in mineral phases of arsenic and iron. The observed solubilization of arsenic was decoupled from iron reduction in the site-oxidized sediments in the presence of native organic carbon, which disagreed with the widely accepted hypothesis that arsenic solubilization is derived from microbial driven reductive dissolution of iron oxides. Carbonate minerals were defined as the mineral phase associated with arsenic that contributed to the arsenic measured in solution. </p><p> The second objective was to determine how altering redox and water conditions down a profile affects arsenic geochemistry and hence solubility. Redox stratification was delineated in two sediment cores based on chemical analyses and visual observation of redox-sensitive parameters. The vadose zone released a considerable amount of arsenic, while the next zone, the carbonate enrichment zone, released the highest concentration of arsenic. Soluble arsenic was exclusively As(V) in the redox transition zone, where As was primarily associated with iron oxides. Solubilization of arsenic was limited in the deeply reduced depletion zone due to the formation of sulfide minerals. </p><p> Lateral resolution of oxidation state and elemental association of arsenic at the micron scale were delineated using synchrotron-based X-ray absorption spectroscopy under Objective 3. The presence of unaltered arsenic sulfides was revealed in the vadose zone, suggesting that arsenic was inputted continuously to the ground surface. From the water table to the deeply reduced depletion zone sediments, arsenic mineral association was dominated by manganese-bearing carbonate minerals and amorphous iron oxides, which are vulnerable to groundwater fluctuation and redox-cycling.</p>

No description available.

Thesis (M.S.)--University of North Dakota, 1999. / Title from title screen. Includes bibliographical references.

Orientador: Regina Célia de Oliveira / Acompanhado de mapa (folha solta), acondicionado em envelope / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-21T11:58:32Z (GMT). No. of bitstreams: 1 Santos_MariaCrizaldaFerreira_D.pdf: 182886813 bytes, checksum: 16262f18234bd7c07fb15140bc5bcb7e (MD5) Previous issue date: 2012 / Resumo: Este trabalho propõe um Zoneamento Ambiental da Região Costa do Cacau, Bahia e busca aplicar e desenvolver uma pratica dos elementos conceituais, teóricos e metodológicos da Teoria Geossistêmica, que enfatiza a integração dos componentes do meio natural, sua integração com seus elementos, conexões e processos. O potencial dos recursos naturais utilizados pelo homem é caracterizado como um sistema de recursos naturais aos quais se integram sociedades e num binômio inseparável Sociedade-Natureza. Buscamos através da analise geoambiental articular a relação entre os geossistemas, sua transformação, as dimensões e os processos de alteração da paisagem para diagnosticar o estado de degradação e os estados ambientais que se encontram os geossistemas. Partindo do principio de que os geossistemas, no seu processo de ocupação, visam à formação de unidades socioambientais, esta tese visa analisar as transformações ambientais e estabelecer comparações do Estado ambiental e grau de degradação, além de delimitar e analisar os geossistemas e os sistemas antrópicos da Região Costa do Cacau, Bahia. Para controle ou mitigação dos prejuízos ambientais identificados nos geossistemas naturais e o Estado Ambiental em que se encontram cada unidade geoecológica, além do uso e ocupação, incluindo a interpretação dos impactos sobre o processo de ocupação e seus agentes de alteração e redução da biodiversidade. A partir dos geossistemas como unidades naturais integrais, foi possível distinguir suas modificações e transformações da natureza feitas pela sociedade, à diversidade de tipos de ocupação que determinaram as suas condições naturais e a produção social / Abstract: This paper proposes an environmental zoning of the Costa do Cacau Bahia region and aims to apply and develop a practice of conceptual, theoretical and methodological elements of the Geosistemica Theory that emphasizes the natural environment components integration, its integration with its elements, connections and processes. The potential of natural resources used by man is characterized as a natural resources system to which societies integrate and in an inseparable binomial society-nature. We aim, through geoenvironmental analysis articulate the relationship among geosystems, their transformation, the dimensions and processes altering the landscape, to diagnose the degradation status and the geosystems environmental status. Considering the premisses that the geosystems, in their occupation process, aim the formation of socioenvironmental units, this thesis analyses the environmental transformations and compares the environmental state and amount of degradation, and limits and analyzes the geosystems and anthropic systems of the Costa do Cacau, Bahia region. For control or mitigation of the environmental prejudices identified in the natural geosystems and the environmental state of each geoechological unit, and the use and occupation, including the interpretation of the impacts on the occupation process and biodiversity reduction and alteration agents. From geosystems as integral natural units, it was possible to distinguish its modifications and nature transformations done by society, the diversity of occupation types that determined the natural conditions and social production / Doutorado / Análise Ambiental e Dinâmica Territorial / Doutora em Geografia

No description available.