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abstract: This work focuses on a generalized assessment of source zone natural attenuation (SZNA) at chlorinated aliphatic hydrocarbon (CAH) impacted sites. Given the numbers of sites and technical challenges for cleanup there is a need for a SZNA method at CAH impacted sites. The method anticipates that decision makers will be interested in the following questions: 1-Is SZNA occurring and what processes contribute? 2-What are the current SZNA rates? 3-What are the longer-term implications? The approach is macroscopic and uses multiple lines-of-evidence. An in-depth application of the generalized non-site specific method over multiple site events, with sampling refinement approaches applied for improving SZNA estimates, at three CAH impacted sites is presented with a focus on discharge rates for four events over approximately three years (Site 1:2.9, 8.4, 4.9, 2.8kg/yr as PCE, Site 2:1.6, 2.2, 1.7, 1.1kg/y as PCE, Site 3:570, 590, 250, 240kg/y as TCE). When applying the generalized CAH-SZNA method, it is likely that different practitioners will not sample a site similarly, especially regarding sampling density on a groundwater transect. Calculation of SZNA rates is affected by contaminant spatial variability with reference to transect sampling intervals and density with variations in either resulting in different mass discharge estimates. The effects on discharge estimates from varied sampling densities and spacings were examined to develop heuristic sampling guidelines with practical site sampling densities; the guidelines aim to reduce the variability in discharge estimates due to different sampling approaches and to improve confidence in SZNA rates allowing decision-makers to place the rates in perspective and determine a course of action based on remedial goals. Finally bench scale testing was used to address longer term questions; specifically the nature and extent of source architecture. A rapid in-situ disturbance method was developed using a bench-scale apparatus. The approach allows for rapid identification of the presence of DNAPL using several common pilot scale technologies (ISCO, air-sparging, water-injection) and can identify relevant source architectural features (ganglia, pools, dissolved source). Understanding of source architecture and identification of DNAPL containing regions greatly enhances site conceptualization models, improving estimated time frames for SZNA, and possibly improving design of remedial systems. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2013

The growing environmental awareness regarding production and use of renewable fuels has led many of countries to create policies to benefit producers of renewable fuels. Thus, the search for raw materials for production of biofuels, which do not conflict with the global food production and exhibit similar performance to fossil fuels, has generated interest towards crambe, a crop of high oil content, inappropriate for animal consumption and which can be applied in crop rotation without the need for exchange farm machinery. However, studies evaluating the influence of spatial variability of soil chemical and physical properties on grain yield and oil content of crambe are scarce. Thus, this study aimed to evaluate the spatial correlation between physical and chemical properties of an Oxisol under compaction states with grain yield and oil content of crambe, through a cross-correlation estimator based on moving windows and assess adequate sampling density for application of geostatistics. For this, we used geostatistical techniques such as kriging and simulation data and using software R. We concluded that increased bulk density and soil resistance to penetration change the source:sinc relationship of crambe, reflecting in lower yield but with grain production of higher quality; chemical attributes that have higher direct spatial relationship to grain yield of crambe are phosphorus, calcium, magnesium and organic matter; sampling grids constructed with points spaced at large distances are not effective in detecting the spatial variability of chemical attributes and grain yield and oil content of crambe; and that the cross semivariogram based on moving windows detects the structure of spatial correlation between the physical and chemical soil properties, independent of its variability or dispersion, showing superior performance when the data have outliers and do not have normal distribution. / A crescente conscientização ambiental a respeito da produção e uso de combustíveis renováveis tem levado muitos países a criar políticas que beneficiam os produtores destes combustíveis. Assim, a busca por matéria-prima para produção dos biocombustíveis não conflitantes com a produção mundial de alimentos e que apresentem desempenho semelhante aos combustíveis fósseis despertou interesse pelo crambe, uma cultura de grande teor energético, imprópria para o consumo animal e que pode ser aplicada em rotação de culturas sem a necessidade de troca de maquinário agrícola. No entanto, estudos avaliando a influência da variabilidade espacial de atributos químicos e físicos no rendimento de grãos e no teor de óleo do crambe ainda são escassos. Neste sentido, este trabalho objetivou principalmente avaliar a correlação espacial entre atributos físicos e químicos de um Latossolo sob estados de compactação, com o rendimento de grãos e de óleo do crambe, através de um estimador de correlação cruzada baseado em janelas móveis e avaliar a densidade amostral adequada para aplicação da geoestatística. Para isto, utilizaram-se técnicas de geoestatística como a simulação de dados e krigagem com auxílio do software R. Concluiu-se que o aumento da densidade e da resistência do solo altera a relação fonte:dreno do crambe, repercutindo em menor rendimento de grãos, porém com produção de grãos de maior qualidade; os atributos químicos que apresentam maior relação espacial direta com o rendimento de grãos do crambe são o fósforo, cálcio, magnésio e matéria orgânica; malhas amostrais construídas com pontos espaçados a grandes distâncias não são eficazes na detecção da variabilidade espacial de atributos químicos e do rendimento de grãos e teor de óleo do crambe; e que o semivariograma cruzado baseado em janelas móveis detecta a estrutura de correlação espacial entre os atributos físicos e químicos do solo, independente de sua variabilidade ou dispersão, apresentando desempenho superior quando os dados apresentam outliers e não possuem distribuição normal.

Yes / Purpose.: To establish whether a clinically exploitable relationship exists between surrogate measures of retinal ganglion cell number and functional sampling density and visual contrast sensitivity in healthy young eyes. Methods.: Psychometric functions for contrast detection were measured at 9° eccentricity in superior and inferior visual field from 20 healthy adults (age 23–43, median 26 years). Functions were compared with corresponding localized regions of retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography, a surrogate of retinal ganglion cell number, and to grating resolution acuity, a psychophysical surrogate of retinal ganglion cell sampling density. Correlations between psychometric function parameters and retinal ganglion cell surrogates were measured by Spearman's rank correlation. Results.: All measures exhibited a 2- to 4-fold variation in our sample. Despite this, correlations between measures were weak. Correlations between psychometric function parameters (threshold, spread) and RNFL thickness ranged in magnitude from 0.05 to 0.19 (P = 0.43–0.85). Grating resolution was sampling limited for 16 of 20 participants in superior visual field, and for 12 of 20 participants in inferior visual field. Correlations between psychometric function parameters and grating resolution acuities ranged in magnitude from 0.05 to 0.36 (P = 0.12–0.85) when all data were considered, and from 0.06 to 0.36 (P = 0.26–0.87) when only sampling-limited data were considered. Conclusions.: Despite considerable variation in both psychometric functions for contrast detection and surrogate measures of retinal ganglion cell number and sampling density among healthy eyes, relationships between these measures are weak. These relationships are unlikely to be exploitable for improving clinical tests in healthy populations.