Digital Commons Network^™

Phylogenetic Diversity And Community Structure Of Sulfate-Reducing Bacteria In A Salt Marsh Sediment, Juliette Nicole Rooney Varga

Doctoral Dissertations

Phylogenetic diversity and community structure of sulfate-reducing bacteria (SRB) in a salt marsh sediment and rhizosphere of Spartina alterniflora were investigated. Uncultivated phylotypes were studied by selectively amplifying Desulfobacteriaceae 16S rRNA gene fragments from DNA extracted from salt marsh rhizosphere samples. An in vitro transcription technique was developed to synthesize reference RNAs containing sequences presumably identical to corresponding regions of the uncultivated organisms' 16S rRNAs. These reference RNAs were used in subsequent quantitative probing experiments. Oligonucleotide probes were designed to specifically target novel phylotypes and were tested for optimal hybridization wash conditions and target specificity. The newly designed probes were …

Development And Application Of Molecular Techniques For The Detection Of Human Enteric Viruses In Environmental Samples, Patrick Michael Regan

Doctoral Dissertations

Shellfish and water have been implicated in the transmission of viral diseases. National surveillance data on waterborne and foodborne illnesses underestimate the public health significance of these viruses. The focus of this research was to evaluate, develop, and apply molecular techniques to detect human enteric viruses in environmental samples.

The initial study evaluated a nucleic acid hybridization assay using a $\sp{32}$P labeled cDNA probe to detect poliovirus in clams. Clams (Mercenaria mercenaria) were harvested from Narragansett Bay, Rhode Island. Poliovirus was detected in clams from the conditionally approved area in 3 of 9 collections and in the prohibited area in …

Impact Of Land-Use And Climatic Changes On Hydrology Of The Himalayan Basin: A Case Study Of The Kosi Basin, Keshav Prasad Sharma

Doctoral Dissertations

Land-use and climatic changes are of major concern in the Himalayan region because of their potential impacts on a predominantly agriculture-based economy and a regional hydrology dominated by strong seasonality. Such concerns are not limited to any particular basin but exist throughout the region including the downstream plain areas. As a representative basin of the Himalayas, we studied the Kosi basin (54,000 km$\sp2)$ located in the mountainous area of the central Himalayan region. We analyzed climatic and hydrologic information to assess the impacts of existing and potential future land-use and climatic changes over the basin.

The assessment of anthropogenic inputs …

The Mechanism And Kinetics Of Conway Granite Weathering In Aqueous Solutions At Low Temperature And Pressure, Zhaosong Lu

Doctoral Dissertations

Radon, a carcinogenic radioactive gas and a contamination in household air and drinking water, has been an environmental issue of great concern in New England, particularly in the Concord and Conway granite areas of New Hampshire. One of the major factors controlling the releases of radionuclide is the weathering rate. In this project, two Conway granite samples collected from the Redstone Quarry, Conway, NH, were weathered in laboratory by several solutions (HNO$\sb3$, H$\sb2$SO$\sb4$, H$\sb2$C$\sb2$O$\sb4$, KHP, catechol, EDTA, and humic acid) using several methods (batch, FBR, and surface titration).

The release of all cations except K follows a typical parabolic pattern. …

An Analysis Of High Frequency Methane Measurements In Central New England, Mark Charles Shipham

Doctoral Dissertations

A unique high resolution ambient air methane data set consisting of approximately 125,000 independently measured data points for the years 1991-1995 has been collected at a site in the northeastern United States. This data base is used to examine the long term trend, seasonal and diurnal cycles, and the frequent pollution events that affect the site on a year round basis.

The annual median mixing ratio of methane for all measurements was 1808 ppbv in 1992, increasing at a variable rate to 1837 ppbv in 1995. The lower 10-30% of the data from each month was defined as representative of …

The Chemistry And Dry Deposition Of Atmospheric Nitrogen At A Rural Site In The Northeastern United States, Barry Lee Lefer

Doctoral Dissertations

Measurements of N gas (HNO$\sb3$, NH$\sb3$) and aerosol (NO$\sb3\sp-,$ NH$\sb4\sp+$) species were made between 1991-1995 to examine the nature of atmospheric N chemistry and to estimate the importance of N dry deposition to the Harvard Forest (Petersham, MA). This U.S. site was influenced by aged rural air masses advected from the northwest (NW) and fresh industrial emissions from the southwest (SW). Mean midday HNO$\sb3$ and aerosol N mixing ratios were four times higher in SW surface winds.

Diel cycles provided evidence of the entrainment of HNO$\sb3$ and aerosol NO$\sb3\sp-$ from aloft as the nocturnal inversion broke down. HNO$\sb3$ made up …

Ecological Database Development And Analyses Of Soil Variability In Northern New England, Michael Anayo Okoye

Doctoral Dissertations

The 1983 Forest Inventory and Analysis (FIA) data of the states of Maine, New Hampshire and Vermont (the study area) contain large amounts of field-measurements of many ecologically important variables. Despite the vast potential usefulness of the FIA data for scientific research, the data were until now, literally unused except for a few administrative purposes, because of problems in the way the data were organized, summarized, and coded for storage. The primary objective of this research was to solve the problems that had thus precluded these FIA data from use in scientific applications, and present the data in a form …