No description available.

No description available.

No description available.

No description available.

<p> Estimating the water budget of three mid-latitude extratropical cyclones is attempted from the perspective of the precipitation efficiency (PE), using a method proposed for the study of convective columns. Using a lagrangian, system-relative volume centered on the surface low pressure, each cyclone was followed for most of its lifetime within a pre-defined volume (7 degrees latitude x 9 degrees longitude, or approximately 700 x 700 km). A comparison is then made of total atmospheric water vapor ingested to total moisture eliminated (as precipitation). We hypothesize that the PE increases with the intensity of the cyclone. This small sample confirms that idea, and thus encourages further study with this approach.</p><p>

<p> MONITOR is an active, automatic extraction sampler that collects daily, integrated extracts of hydrophobic compounds in water. Compounds partition from water, through a polydimethylsiloxane membrane and into hexane. The sampling rate, membrane-water partition coefficients (K_MW) and hexane-water partition coefficients (K_HW) were determined for atrazine and four nonpolar reference compounds. The reference compounds had high effective sampling rates (>10 L/day) while atrazine had a low effective sampling rate (&lt;1 L/day). Atrazine had intermediate hydrophobicity as determined by K_MW and octanol-water partition coefficient (KOW). However, atrazine had a low K_HW, which caused its low sampling rate. In spite of MONITOR's low sampling rate for atrazine, the concentration of atrazine in the drinking water of Syracuse, New York was observed from March - November 2012 using MONITOR. The average concentration was 0.016 &mu;g/L. MONITOR was able to capture fluctuations in the concentration of atrazine at very low levels over several months.</p>

<p> Selenium (Se) is a trace element of great ecological importance whose environmental distribution is highly impacted by anthropogenic activity. In the 1980s, selenium was recognized as a major aquatic contaminant following widespread deformities and mortality among waterfowl hatchlings near the agricultural drainage evaporation ponds of the Kesterson Reservoir (CA, USA). Today, 400,000 km² in the Western United States are threatened by agricultural selenium contamination, as are parts of Canada, Egypt, Israel, and Mexico. From the soil aggregate to the watershed, from the soils of the Central Valley to the sediments of the Salton Sea, and from Environmental Science to Policy and Management, in this dissertation I explore agricultural selenium contamination across scales, ecosystems, and disciplines. I begin with a review of the science, policy, and management of irrigation-induced selenium contamination in California, the heart of worldwide research on the issue. I then delve into the physical and biogeochemical mechanisms that control selenium reduction and mobility within the structured surface soils that are the source of contamination, using an aggregate-scale combined experimental and reactive transport modeling approach. Finally, I present a diagenetic model for selenium incorporation into the sediment of the Salton Sea, which has been receiving seleniferous agricultural drainage over the last 100 years. </p><p> To extract lessons from the last 30 years of seleniferous drainage management and water quality regulation in California, I reviewed the history and current developments in science, policy, and management of irrigation-induced selenium contamination in California. Specifically, I evaluated improvements in the design of local attenuation methods and the development of programs for selenium load reductions at the regional scale. On the policy side, I assessed the site-specific water quality criteria under development for the San Francisco Bay-Delta in the context of previous regulation. This approach may be a landmark for future legislation on selenium in natural water bodies and I discussed challenges and opportunities in expanding it to other locations such as the Salton Sea. By combining proven management tools with the novel, site-specific policy approach, it may be possible to avoid future events of irrigation-induced selenium contamination. However, the majority of regional selenium load reductions in California were achieved by decreasing drainage volume rather than selenium concentrations. Thus, there appear to be opportunities for additional improvements through management practices that enhance selenium retention in source soils. </p><p> To quantify the likely implications of these experimental results for soils with different degrees of aggregation, I formulated a general mechanistic framework for aggregate scale heterogeneity in selenium reduction. Specifically, I constructed a dynamic 2D model of selenium fate in single idealized aggregates, in which reactions were implemented with double-Monod rate equations coupled to the transport of pyruvate, O₂, and Se-species (selenate, selenite, and elemental selenium). The spatial and temporal dynamics of the model were validated with the experimental data and predictive simulations were performed covering aggregate sizes between 1 and 2.5 cm diameters. Simulations predict that selenium retention scales with aggregate size. Depending on aeration conditions and the input concentrations of selenate and pyruvate, selenium retention was predicted to be 4-23 times higher in 2.5-cm-aggregates compared to 1-cm-aggregates. Under oxic conditions, aggregate size and pyruvate-concentrations were found to have a positive synergistic effect on selenium retention. Promoting soil aggregation on seleniferous agricultural soils may thus help decrease the impacts of selenium contaminated drainage on downstream aquatic ecosystems receiving it. </p><p> This work presents agricultural selenium contamination as a complex problem that crosses ecosystems, scales, and disciplines. From a management perspective, the tension between dispersed non-point sources and hotspots where elevated selenium concentrations and sensitive aquatic ecosystems converge is difficult to address. Differences in biogeochemical conditions and trophic transfer within food webs render traditional regulatory approaches ineffective and force regulators to engage with the science of site-specific selenium transfer between ecological compartments. At the same time, gaps still exist in our mechanistic understanding of selenium's environmental cycling and in our integration of scientific knowledge across different ecosystems and scales. Centimeter scale heterogeneity in the biogeochemical conditions within source soils may fundamentally control selenium emissions across large agricultural areas and thus determine the selenium loading of rivers, lakes, and estuaries. Within aquatic environments receiving seleniferous drainage, the first few centimeters of surface sediment may control selenium exposure for entire food webs. Improved understanding at this level holds the potential to simultaneously reduce selenium emissions and respond more effectively to pollution where it occurs. In order to preserve sensitive habitat while also meeting agricultural drainage needs in seleniferous regions we must bridge the gaps between ecosystems, scales, and disciplines.</p><p> (Abstract shortened by UMI.)</p>

A wide variety of assessment techniques are presently available to quantify the environmental performance of an organisation. They are predominantly site- or area-specific, making them sensitive to differences in the environmental capacity of an area, and they exclude a number of global impacts. A more generic level-plane assessment tool, which quantifies the environmental burden, may therefore be needed to make a valid comparison between organisations. Furthermore, the generic process data used in these assessment tools, to inform policy decisions on a material or product, does not recognise the potential variation in burden of a sector. This thesis develops a corporate level-plane assessment tool using the techniques available from Life Cycle Assessment. This generic tool, the Total Environmental Potency Index (TEPI), is then compared with the Environment Agency's Integrated Environmental Index (IEI), to assess the significance of site location on compliance based site-specific indices like the IEI. The two indices are compared using realworld emission data from seven industrial collaborators in five sectors. Two of these, paper manufacture and power generation, are used to assess the potential variability among processes within the same sector. The potential use of the indices is also determined by examining the accessibility to the required data at each of the participating companies. The results show that site location significantly affects the IEI and that the TEPI can provide a useful generic impact assessment tool to compare sites from different locations or sectors. The burdens from processes within the same sector were highly variable, suggesting that process-specific data will be important if valid policy decisions are to be made in the future. The TEPI and its categories can provide a standard format for aggregating and presenting the required emission data in a way that protects its commercial sensitivity. Although the accessibility to this data was low to moderate, the potential for deriving emission data using mass balance studies was high, with a large amount of accessible input data available. The implications of these results for the use of internal and external impact assessment techniques within an organisation are discussed. A framework is provided to guide the use of process data and impact assessment techniques in the wide range of assessments made by organisations to manage and report on their environmental performance. Finally, the experiences gained from using the IEI and TEPI are used to make recommendations for their improvement, and further development by research.

Thesis (M.S.C.E.)--University of Toledo, 2006. / Typescript. "Submitted as partial fulfillment of the requirements for Masters of Science degree in Civil Engineering." Bibliography: leaves 53-55.

Thesis (M.S.V.)--University of Toledo, 2004. / Typescript. "A thesis [submitted] as partial fulfillment of the requirements of the Master of Science degree in Civil Engineering." Includes bibliographical references (leaves 87-91).