Thesis (Ph.D.)--York University, 2009. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 140-154). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR51678

Thesis (Ph.D.)--Indiana University, Dept. of Geological Sciences, 2005. / Source: Dissertation Abstracts International, Volume: 66-07, Section: B, page: 3599. Chair: Lisa Pratt. Title from dissertation home page (viewed Oct. 5, 2006).

Thesis (Ph.D.)--Indiana University, School of Public Environmental Affairs, 2005. / Source: Dissertation Abstracts International, Volume: 66-02, Section: B, page: 0765. Adviser: Flynn W. Picardal. Title from dissertation home page (viewed Oct. 18, 2006).

Thesis (PH.D.) -- Syracuse University, 2006 / "Publication number AAT 3242506."

Thesis (Ph.D.)--Indiana University, Dept. of Geological Sciences, 2006. / "Title from dissertation home page (viewed July 11, 2007)." Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4307. Adviser: Lisa M. Pratt.

Thesis (Ph. D.)--Stanford University, 2002. / Includes bibliographical references (leaves 122-126).

<p> The Gulf of Alaska is a seasonally productive ecosystem surrounded by glaciated coastal mountains with high precipitation. With a combination of high biological production, inputs of suspended sediments from glacial runoff, and contrasting nutrient regimes in offshore and shelf environments, there is a great need to study particle cycling in this region. I measured the concentrations and size distributions of large marine particles (0.06-27 mm) during four cruises in 2014 and 2015 using the Underwater Vision Profiler (UVP). The UVP produces high resolution depth profiles of particle concentrations and size distributions throughout the water column, while generating individual images of objects >500 &mu;m including marine snow particles and mesozooplankton. </p><p> The objectives of this study were to 1) describe spatial variability in particle concentrations and size distributions, and 2) use that variability to identify driving processes. I hypothesized that UVP particle concentrations and size distributions would follow patterns in chlorophyll <i>a</i> concentrations. Results did not support this hypothesis. Instead, a major contrast between shelf and offshore particle concentrations and sizes was observed. Total concentrations of particles increased with proximity to glacial and fluvial inputs. Over the shelf, particle concentrations on the order of 1000-10,000/L were 1-2 orders of magnitude greater than offshore concentrations on the order of 100/L. Driving processes over the shelf included terrigenous inputs from land, resuspension of bottom sediments, and advective transport of those inputs along and across the shelf. Offshore, biological processes were drivers of spatial variability in particle concentration and size. High quantities of terrigenous sediments could have implications for enhanced particle flux due to ballasting effects and for offshore transport of particulate phase iron to the central iron-limited gyre. The dominance of resuspended material in shelf processes will inform the location of future studies of the biological pump in the coastal Gulf of Alaska. This work highlights the importance of continental margins in global biogeochemical processes.</p>

<p>Limestone dissolution in karst environments is likely due to geochemistry of the water, the actions of microbial communities, and the effect of water flow. We explored the rate of limestone dissolution and will examine here the microbial communities associated with the limestone. A conduit within the brackish cave, Double Keyhole Spring, on the coast of central west Florida was the site of the experiment. PVC pipes (5cm x 16cm) were filled with crushed limestone that was screened to a 1.9cm ? 2.54cm size range. There were three treatments (5 replicates each): Control - sealed autoclaved controls with limestone and conduit water; Low Flow ? sealed at one end, with a screen on the other so water contacts the limestone but cannot flow through; High Flow ? screen mesh at both ends to allow the flow of conduit water over the limestone in the tube. After 9 months, the samples were retrieved. The Controls showed a loss of 0.33% ? 0.10, Low Flow samples showed a loss of 1.63% ? 0.71, and High Flow samples lost 2.28% ?0.29. Other studies in freshwater conditions found an average mass loss of 2.25% over the same time period under conditions similar to the High Flow sample in this experiment. Q-PCR and LH-PCR were used to estimate microbial density and species richness. The microbial community growing on the limestone samples were found to be significantly different from sediment or water column samples in both diversity and richness. The conclusion of this study is that the archaeal community growing on the limestone is the main biological driver of limestone dissolution in Double Keyhole Spring.

abstract: Hydrology and biogeochemistry are coupled in all systems. However, human decision-making regarding hydrology and biogeochemistry are often separate, even though decisions about hydrologic systems may have substantial impacts on biogeochemical patterns and processes. The overarching question of this dissertation was: How does hydrologic engineering interact with the effects of nutrient loading and climate to drive watershed nutrient yields? I conducted research in two study systems with contrasting spatial and temporal scales. Using a combination of data-mining and modeling approaches, I reconstructed nitrogen and phosphorus budgets for the northeastern US over the 20th century, including anthropogenic nutrient inputs and riverine fluxes, for ~200 watersheds at 5 year time intervals. Infrastructure systems, such as sewers, wastewater treatment plants, and reservoirs, strongly affected the spatial and temporal patterns of nutrient fluxes from northeastern watersheds. At a smaller scale, I investigated the effects of urban stormwater drainage infrastructure on water and nutrient delivery from urban watersheds in Phoenix, AZ. Using a combination of field monitoring and statistical modeling, I tested hypotheses about the importance of hydrologic and biogeochemical control of nutrient delivery. My research suggests that hydrology is the major driver of differences in nutrient fluxes from urban watersheds at the event scale, and that consideration of altered hydrologic networks is critical for understanding anthropogenic impacts on biogeochemical cycles. Overall, I found that human activities affect nutrient transport via multiple pathways. Anthropogenic nutrient additions increase the supply of nutrients available for transport, whereas hydrologic infrastructure controls the delivery of nutrients from watersheds. Incorporating the effects of hydrologic infrastructure is critical for understanding anthropogenic effects on biogeochemical fluxes across spatial and temporal scales. / Dissertation/Thesis / Ph.D. Biology 2013

Seabird-derived nutrients enhance plant abundance in coastal ecosystems, increasing rates of primary productivity, and indirectly increasing consumer populations. However, at Cape Vera, concentrations of contaminants in the sediment of ponds below nesting colonies of northern fulmars (Fulmarus glacialis) are 10 to 60 times higher than in reference ponds (Blais et al. 2005). This pattern suggests that the colony concentrates hexachlorobenzene (HCB), total mercury (THg), and dichlorodiphenyltrichloroethane (DDT) through guano to pond sediments (Blais et al. 2005). It remains unclear whether the effects of these contaminants are localized to the ponds or whether they enter the food chain. This study was designed to determine whether organochlorines and mercury were transferred from a seabird colony to coastal food webs. Contaminant concentrations were measured in primary producers and animals. Nitrogen stable isotopes were used to detect seabird influence. Concentrations of SigmaPCB and SigmaDDT in organisms were high relative to other Arctic areas; however, THg concentrations were similar. Snow buntings (Plectrophenax nivalis ) had SigmaPCB (mean: 168 ng/g ww) and SigmaDDT (mean: 106 ng/g ww) concentrations that surpassed environmental guidelines for protecting wildlife. Biovector transport may be a source of contaminants to certain organisms at Cape Vera.