Physical Sciences and Mathematics Commons^™

A Comparison Of No And N20 Production By The Autophic Nitrifier Nitrosomonas Europaea And The Heterotrophic Nitrifier Alcaligenes Faecalis, Iris C. Anderson, Mark Poth, Julie Homstead, David J. Burdige

OES Faculty Publications

Soil microorganisms are important sources of the nitrogen trace gases NO and N₂O for the atmosphere. Present evidence suggests that autotrophic nitrifiers such as Nitrosomonas europaea are the primary producers of NO and N₂O in aerobic soils, whereas denitrifiers such as Pseudomonas spp. or Alcaligenes spp. are responsible for most of the NO and N₂O emissions from anaerobic soils. It has been shown that Alcaligenes faecalis, a bacterium common in both soil and water, is capable of concomitant heterotrophic nitrification and denitrification. This study was undertaken to determine whether heterotrophic nitrification might be …

Identification And Quantitation Of Volatile Amines In Chesapeake Bay Sediments, Neeraja Y. Krishna

Chemistry & Biochemistry Theses & Dissertations

Sediments from different parts of the Chesapeake Bay were analyzed to determine the presence of volatile amines. A HF-HCl extraction method was used to extract both exchangeable and fixed amines from the sediments and a purge-and-trap technique was used to concentrate the amines. Following derivatization with heptafluorobutyric anhydride (HFBA), the HFBA-amines were analyzed by gas chromatography with electron capture detection and with mass spectrometric detection. One primary amine, i-amylamine with a concentration ranging from 0. 78 nmoles/g dry weight to < 0.05 nmoles/g dry weight was found in a total of twenty seven samples collected on three different dates in 1993. Another primary amine, 2-methylbutylamine with a concentration ranging from 0.18 nmoles/g dry weight to < 0.05 nmoles/g dry weight was found in a total of twenty three samples collected on three different dates in 1993. A secondary amine, diethylamine was detected but could not be quantified in a total of seven samples collected in September 1993. The concentrations of these amines varied with location in the Bay, depth in the sediment, and time of year the sediments were collected. The origin of i-amylamine and 2-methylbutylamine might be from the biological decarboxylation of amino acids leucine and isoleucine, respectively. The origin of diethylamine is unknown.

The Biogeochemistry Of Iodine In Seawater, Lingsu Zhang

OES Theses and Dissertations

Iodate and iodide are the two major species of iodine in seawater. In comparison to iodate, iodide is thermodynamically unstable in oxic seawater. The conversion (or reduction) of iodate to iodide may be mediated via biological activities. Since biological activities vary with the season, the conversion of iodate to iodide may also vary seasonally. The conversion (or oxidation) of iodide to iodate is thermodynamically feasible, but the mechanism is poorly known. Hydrogen peroxide, which is ubiquitous in surface seawater, may oxidize iodide to iodate.

Water samples were collected in the middle and lower Chesapeake Bay in different seasons between 1990 …

Paleobathymetric Interpretation Of Pleistocene Sediments In The South Padre Island Area, Northwestern Gulf Of Mexico, Using Benthic Foraminiferal Morphology, Karen Ianthe Kruebbe-Belwood

OES Theses and Dissertations

This study tested the validity of using intraspecific variation in benthic foraminifera as a means for determining Pleistocene paleobathymetry. Canonical variate analysis was used as a means for determining visually undetectable but statistically significant differences in the morphology of selected species. Two species, Cassidulina subglobosa and Uvigerina peregrina, were collected from Pleistocene well cuttings from the northwest Gulf of Mexico. The canonical analysis involved comparing the intraspecific variation of these Pleistocene species to their counterparts occurring in the modern Gulf of Mexico, where intraspecific variation was previously analyzed and found to be sufficient to allow detection of bathymetric differences …

Lithofacies Of The Pliocene-Pleistocene Lucayan Limestone, Great Abaco Island, Little Bahama Bank, Mary K. Mullen

OES Theses and Dissertations

Petrographic and sedimentologic analyses of eleven shallow subsurface cores (3 to 19 meters in length) from the Lucayan Limestone where it occurs along northeastern Great Abaco Island (little Bahama Bank) are used to delineate five carbonate lithofacies. The most prevalent lithofacies is a mottled, nonskeletal, peloidal packstone to grainstone. Other lithofacies include a rudstone, a laminated nonskeletal grainstone, a crossbedded grainstone and a mudstone-wackestone.

Cementation varies from poor to very well cemented core intervals. Cements observed included equant granular, equant blocky, drusy, meniscus, and needle fiber "whisker" cements. These cements reflect a variety of diagenetic environments such as the vadose, …

The Biogeochemistry Of Hydrogen Sulfide In The Open Ocean, Joël Radford-Knoery

OES Theses and Dissertations

Hydrogen sulfide is a poorly quantified component of the global sulfur cycle. In seawater, its dissolved species (dissolved sulfide) can react with trace metals to form dissolved complexes and insoluble compounds. Therefore, the study of dissolved° sulfide in the open ocean can yield a better understanding of the biogeochemical cycles of sulfur and trace metals.

The biogeochemical cycling of dissolved sulfide was examined using specially developed sampling and analytical methods. In the western North Atlantic and central Equatorial Pacific Oceans, total dissolved sulfide concentrations ranged from /L; they were highest, in the mixed layer and decreased with depth. The depth …

Petrology Of A Large Granophyre-Rich Mesozoic Diabase Dike Near Farmville, Virginia, Philip Thomas Rogan

OES Theses and Dissertations

Up to 37% granophyre occurs in the center of a 150m-wide Mesozoic diabase dike near Farmville, Virginia. The exceptional abundance of granophyre compared with other Mesozoic diabase dikes suggests unusual petrogenetic processes are involved in formation of the dike. Petrographic analyses show that granophyre increases from 5-10% near the flanks of the dike to a maximum of 37% in the core of the dike, and that granophyre distribution is approximately symmetrical about the center of the dike. Major and trace element concentrations parallel variations in the modal abundance of granophyre, with SiO₂ , Na₂O and K_{2 …}

Recent Benthic Foraminifera, Petrology, And Implications For Recent Transport In Wilmington And South Heyes Submarine Canyons, U.S. Atlantic Continental Margin, Jason James Lundquist

OES Theses and Dissertations

Two hundred and forty-six species of benthic foraminifera have been recognized in fourteen short cores (≤ 24cm) taken from within the Wilmington and South Heyes submarine canyons along the slope and rise of the United States Atlantic Continental Margin. Of these one hundred and forty-five species were identified to the species level, thirty were closely related to known species, sixty-six could not be assigned specific names, and five species were of uncertain generic placement. The petrologic character of the sediments was determined for each of the seventy-eight micropaleontogical samples.

Cluster analysis of benthic foraminiferal data identified twelve groups which, together …

Paleocene To Miocene Foraminifera From A Well Near Gloucester, Virginia, Nelson Stanley Ford

OES Theses and Dissertations

Lithologic analysis of twenty-one core samples from a well near Gloucester, Virginia, when compared to published descriptions of formations occurring in the study area, indicates the presence of five formations. From oldest to youngest these units are the Aquia (late Paleocene), Nanjemoy (early Eocene), Chickahominy (late Eocene), Old Church (late Oligocene and early Miocene), and Eastover (late Miocene) formations. Comparison of the stratigraphic ranges of key planktic and benthic foraminifera from each of the core samples shows chronological agreement with previously published ages for each of these formations.

Paleoenvironmental analysis of each of the formations in the well is based …