<p> The coastal zone of Louisiana is changing due to multiple pressures associated with sea-level rise, subsidence, and the inability of sediment or organic accretion to keep pace. The expected increases in sea level and salinity may affect the distribution of the existing plant communities. In addition, these changes in the environment could lead to shifts in plant community composition. During the summer of 2014, I researched how changes in salinity and water levels may change the establishment of vegetation in Louisiana marshes. Randomly selected Coastwide Reference Monitoring System (CRMS) sites were used to collect vegetation data and soil samples. The collected soil samples from fresh, intermediate, brackish, and saline marsh sites were used in a seed bank study. The seed bank study evaluated the effects of different levels of salinity and flooding on seed germination and species richness. Seed germination was highest in soil samples collected from fresh and intermediate sites when these samples were exposed to low salinity (0.0 ppt) and non-flooded conditions. My study only found 43 seedlings in the 10 ppt treatment of 336 total seed germinations, and only 2 seedlings were found in the 20 ppt salinity treatment. Salinity was the dominant factor governing seed germinations and species richness. I also determined that the parent plants for the species found in my seed bank study were more likely to be found within the study site. However, the species data showed at least one species or genus was not present in either the historical or the field collected data. Therefore, the dispersal distance of some seeds from their parental seed provider could have been several hundred meters.</p>

<p>Ecological risk assessment (ERA) is a framework for monitoring risks of exposure and adverse effects of environmental stressors to populations or communities of interest. One tool of ERA is the biomarker, which is a characteristic of an organism that reliably indicates exposure to or effects of a stressor like chemical pollution. Traditional biomarkers which rely on characteristics at the tissue level and higher often detect only acute exposures to stressors. Sensitive molecular biomarkers may detect lower stressor levels than traditional biomarkers, which helps inform risk mitigation and restoration efforts before populations and communities are irreversibly affected. In this study I developed gene expression-based molecular biomarkers of exposure to metals and insecticides in the model toxicological freshwater amphipod Hyalella azteca. My goals were to not only create sensitive molecular biomarkers for these chemicals, but also to show the utility and versatility of H. azteca in molecular studies for toxicology and risk assessment. I sequenced and assembled the H. azteca transcriptome to identify reference and stress-response gene transcripts suitable for expression monitoring. I exposed H. azteca to sub-lethal concentrations of metals (cadmium and copper) and insecticides (DDT, permethrin, and imidacloprid). Reference genes used to create normalization factors were determined for each exposure using the programs BestKeeper, GeNorm, and NormFinder. Both metals increased expression of a nuclear transcription factor (Cnc), an ABC transporter (Mrp4), and a heat shock protein (Hsp90), giving evidence of general metal exposure signature. Cadmium uniquely increased expression of a DNA repair protein (Rad51) and increased Mrp4 expression more than copper (7-fold increase compared to 2-fold increase). Together these may be unique biomarkers distinguishing cadmium and copper exposures. DDT increased expression of Hsp90, Mrp4, and the immune response gene Lgbp. Permethrin increased expression of a cytochrome P450 (Cyp2j2) and decreased expression of the immune response gene Lectin-1. Imidacloprid did not affect gene expression. Unique biomarkers were seen for DDT and permethrin, but the genes studied were not sensitive enough to detect imidacloprid at the levels used here. I demonstrated that gene expression in H. azteca detects specific chemical exposures at sub-lethal concentrations, making expression monitoring using this amphipod a useful and sensitive biomarker for risk assessment of chemical exposure.

<p>The health impacts of urban air pollution are a growing concern in our rapidly urbanizing world. Urban air pollutants show high intra-urban spatial variability linked to urban land use and land cover (LULC). This correlation of air pollutants with LULC is widely recognized; LULC data is an integral input into a wide range of models, especially land use regression models developed by epidemiologists to study the impact of air pollution on human health. Given the demonstrated links between LULC and urban air pollution, and between urban air pollution and health, an interesting question arises: what is the potential of LULC modifications to mitigate the health impacts of urban air pollution? </p><p> In this dissertation we assess the potential of LULC modifications to mitigate the health impacts of NO₂, a respiratory irritant and strong marker for combustion-related air pollution, in the Portland-Vancouver metropolitan area in northwestern USA. We begin by measuring summer and winter NO₂ in the area using a spatially dense network of passive NO₂ samplers. We next develop an annual average model for NO₂ based on the observational data, using random forest&mdash;for the first time in the realm of urban air pollution&mdash;to disentangle the effects of highly correlated LULC variables on ambient NO₂ concentrations. We apply this random forest (LURF) model to a 200m spatial grid covering the study area, and use this 200m LURF model to quantify the effect of different urban land use categories on ambient concentrations of NO₂. Using the changes in ambient NO₂ concentrations resulting from land use modifications as input to BenMAP (a health benefits assessment tool form the US EPA), we assess the NO₂-related health impact associated with each land use category and its modifications. We demonstrate how the LURF model can be used to assess the respiratory health benefits of competing land use modifications, including city-wide and local-scale mitigation strategies based on modifying tree canopy and vehicle miles traveled (VMT). </p><p> Planting trees is a common land cover modification strategy undertaken by cities to reduce air pollution. Statistical models such as LUR and LURF demonstrate a correlation between tree cover and reduced air pollution, but they cannot demonstrate causation. Hence, we run the atmospheric chemistry and transport model CMAQ to examine to what extent the dry deposition mechanism can explain the reduction of NO₂ which statistical models associate with tree canopy. </p><p> Results from our research indicate that even though the Portland-Vancouver area is in compliance with the US EPA NO₂ standards, ambient concentrations of NO₂ still create an annual health burden of at least $40 million USD. Our model suggests that NO₂ associated with high intensity development and VMT may be creating an annual health burden of $7 million and $3.3 million USD respectively. Existing tree canopy, on the other hand, is associated with an annual health benefit of $1.4 million USD. LULC modifications can mitigate some fraction of this health burden. A 2% increase in tree canopy across the study area may reduce incidence rates of asthma exacerbation by as much as 7%. We also find that increasing tree canopy is a more effective strategy than reducing VMT in terms of mitigating the health burden of NO₂. </p><p> CMAQ indicates that the amount of NO₂ removed by dry deposition is an order of magnitude smaller than that predicted by our statistical model. About one-third of the difference can be explained by the lower NO₂ values predicted by CMAQ, and one-third may be attributable to parameterization of stomatal uptake. </p>

Invertebrates are suffering the greatest species loss in the current biodiversity crisis. These animals perform essential ecosystem functions upon which humanity depends yet they are largely ignored m conservation efforts. The main challenges facing invertebrate conservationists, in terms of raising public awareness, are to change common negative perceptions regarding invertebrates and to apply some form of value to them. Conservation efforts can be improved by raising public awareness of, and appreciation for, invertebrates in the context of ecotourism. Current levels of inclusion of invertebrates in ecotourism activities were gauged, using qualitative research methods of participant observation and semi-structured interviews. The response of tourists to the concept of the inclusion of both western/scientific and indigenous knowledge regarding invertebrates into current and planned ecotourism activities was determined using the quantitative research method of a structured questionnaire. Canvassing of tourists was done at a popular ecotourism destination (Hluhluwe-Umfolozi Nature Reserve) and 121 questionnaires were completed. In addition to tourists the opinions and attitudes of a range of people working in ecotourism and conservation were examined via semi-structured interviews. The respondents were specifically selected according to the positions they held in the ecotourism and conservation field and a total of eight people in management, ten ecotourism guides and seven ecotourism trainers were interviewed. The findings revealed that there is currently negligible information regarding invertebrates in ecotourism activities. There was an overwhelmingly positive response from tourists, with 95% indicating that they would like to see information regarding invertebrates included in ecotourism activities. Ecotourism service providers, such as tour guides and those in conservation management also indicated a positive attitude toward the concept. There is thus potential to increase levels of information regarding invertebrates in ecotourism and it is recommended that ecotourism include a focus on invertebrates. Recommendations on how to address the lack of invertebrate information in ecotourism are provided and examples of the types of invertebrates to include in specific ecotourism activities are given. Including a focus on invertebrates in ecotourism will serve the multiple purposes of placing value on invertebrates; raising public awareness and hence the conservation status of invertebrates, and finally will increase the scope of ecotourism. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

<p> The purpose of this research was to explore the state of sustainability in U.S. Parks and Protected Areas (PPAs) as well as to create a tool to help measure and maintain sustainability in PPAs. The primary research question driving this research was &ldquo;What is the current state of sustainability in U.S. PPAs?&rdquo; This guiding question also addressed a sub-question, which asked, &ldquo;Can a tool be developed and validated to measure the state of sustainability in parks?&rdquo; The second research question in this project was &ldquo;Do current park managers believe the use of a sustainable parks certificate would aid ongoing efforts to uphold and maintain sustainability in their parks?&rdquo; Each research question was addressed through the creation of a survey to measure the state of sustainability through five hypothesized domains, with 55 Likert-scale-style questions and six open-ended questions addressing the certificate program. The survey opened in May 2017 and ended in October 2017. It was sent to approximately 2,645 managers across the country and included national parks and state parks in U.S. states and territories. The data showed that participants were in favor of creating a sustainable parks certificate to help them become more sustainable. A chief recommendation was to start an initiative aimed at providing an online platform for sustainability training geared specifically toward PPAs. This research project has begun the steps necessary to advance the state of sustainability in U.S. PPAs.</p>

<p> Since the inception of the U.S. Environmental Protection Agency (EPA), considerable emphasis has been placed on the use of prospective policy analysis tools that aim to inform environmental decisions, including cost-benefit analysis and risk assessment. However, compared to the prevalence of <i> ex ante</i> analysis at the EPA to inform decisions, relatively little evaluation of these same environmental policies is conducted after implementation, to inform future policy development or to modify existing policies. </p><p> This dissertation applied accountability, organizational learning, evaluation capacity, and institutionalism literature in consideration of processes and determinants that affect evaluation supply at the EPA. The dissertation relied on archival documents, semi-structured interviews, and three embedded case studies of EPA&rsquo;s ambient air, hazardous waste, and performance partnership programs. Ten key factors were identified across the three case studies in this research that affect EPA's production of program evaluation to inform decision-making, and a new emergent model of evaluation capacity was proposed for EPA given the agency's regulatory structure. This research concludes that evaluation has much to offer EPA decision-makers, and efforts to improve evaluation capacity will present organizational learning opportunities that can further support the agency's evidence-building practices, specifically improving the application and use of program evaluation at EPA.</p>

<p> The deep sea is the Earth&rsquo;s largest ecosystem and harbors a unique and largely endemic fauna. Although most research has focused on the ecological mechanisms that allow coexistence, recent studies have begun to investigate how this remarkable fauna evolved.. My work quantifies geographic patterns of genetic variation and investigates potential mechanisms that shape evolution in the deep ocean. </p><p> Bathymetric genetic divergence is common in the deep sea with population structure typically decreasing with depth. The evolutionary mechanisms that underlie these patterns are poorly understood. Geographic patterns of genetic variation indicated that the protobranch bivalve <i>Neilonella salicensis </i> was composed of two distinct lineages separated bathymetrically. Genetic diversity was greater in the lower-bathyal clade of <i>N. salicensis </i> than the upper to mid-bathyal clade. In a co-occurring mid-bathyal protobranch <i>Malletia johnsoni,</i> population differentiation was greater among samples than the confamilial lower-bathyal <i>Clencharia abyssorum,</i> though, genetic diversity was similar. These patterns suggest general trends do not always hold and fine scale patterns of gene flow need to be thoroughly investigated. </p><p> Little is known about the ecological or evolutionary mechanisms that might promote divergence or maintain population structure. Oxygen minimum zones (OMZs), which cover enormous regions of the deep ocean, might hamper gene flow by precluding larval dispersal. To test this, genetic patterns of the wood-boring bivalve <i>Xylophaga washington</i> were quantified across the northeastern Pacific OMZ. Results indicate two clades were apparent, one throughout the OMZ and one within and below it, possibly segregated by a historically stronger OMZ or other environmental factors that vary with depth. A similarly uninvestigated evolutionary factor with potentially large impacts is selection on mitochondrial DNA. Positive selection is apparent in the mitochondrial DNA of shallow water and deep-sea crabs, shrimp, and fishes, possibly related to any of the myriad factors that differ between the two habitats. </p><p> The deep sea is biogeochemically important and is highly impacted by climate change and anthropogenic factors. Genetic patterns in this habitat are very complex. This work suggests gene flow is inhibited at many scales, both across bathymetric gradients and within small bathymetric ranges.</p><p>

<p> Adoption of nitrogen (N) management strategies to minimize gaseous N loss from agriculture while maintaining high yield production is increasingly important for an exponentially growing population. Agricultural management on poorly-drained claypan soils in the Midwestern U.S. make corn (<i> Zea mays</i> L.) production even more challenging due to the subsoil&rsquo;s low permeability, which may result in wetter soil conditions and relatively larger amounts of soil N₂O emissions during the growing season. The objective of this study was to determine the effects of urea fertilizer placement with and without the addition of a nitrification inhibitor (NI) on corn yield, N use efficiency (NUE), and cumulative soil N2O emissions on a Northeastern Missouri claypan soil. The fertilizer strategies utilized in this study consisted of deep-banded urea (DB) or urea plus nitrapyrin [2-chloro-6-(trichloromethyl) pyridine] (DB+NI) at a depth of 20 cm compared to urea broadcast surface applied (SA) or incorporated to a depth of 8 cm (IA). The addition of a NI with deep-banded urea resulted in 27% greater apparent N recovery efficiency than all other N treatments. Additionally, DB+NI had 54 and 55% lower cumulative soil N₂O emissions than IA and SA treatments in the two combined growing seasons. These results suggest that deep placement of urea with or without nitrapyrin is an effective management strategy for increasing corn yield and reducing N loss on a claypan soil.</p><p>

<p> Precipitation and land cover in the West African Sahel have changed dramatically over the past 50 years. Region-wide data on land cover change in the Sahel, however, have been sparse or unreliable. I present a new 30 meter 2000&ndash;2016 annual resolution land cover dataset for the West African Sahel. The product is built from hand-classified land cover maps using random forest machine learning methods with Landsat, precipitation, and topography features. The resulting maps confirm the widespread extensification of agriculture in the region over this time period. Contrary to the common narrative of desertification, this increase in agriculture has not been accompanied by an increase in bare soil or sandy area. Land cover change volatility is shown to be spatially heterogeneous, both at local and regional scales. In addition to the new land cover dataset, I present spatial and temporal analyses of precipitation during the recent years of increased variability in the West African Sahel. I examine seasonal trends, interannual variability, and differences among datasets representing precipitation in the Sahel. Region-wide spatial organization of precipitation is identified using the self-organizing mapping pattern recognition technique. The number of days spent in the monsoon transition period is strongly negatively correlated with annual precipitation anomaly` indicating a tradeoff with the peak monsoon period, a result that supports the upped-ante hypothesis of precipitation in the Sahel.</p><p>

<p>Adsorption of Pb2+ onto ordered mesoporous Carbon (OMC) modified by nitric and phosphoric acid was investigated with variations of the parameters, such as pH, contact time, temperature, and initial concentration. Optimum Pb2+ adsorption was observed at a pH value of 5. Modified OMC was characterized by Nitrogen Adsorption-Desorption Isotherm, FT-IR, SEM, EDS, and TEM. The time required to reach equilibrium was between 20 mins and 30 mins. The equilibrium adsorption capacity of modified OMC (MOMC-NP) increased with the increase of temperature indicating that the process of Pb2+ adsorption is an endothermic process. The equilibrium adsorption capacity of MOMC-NP was found to be 56.06, 68.82, and 77.8 mg g-1 at an initial concentration of 60, 80, and 100 mg L-1 of Pb2+, respectively. Kinetics studies suggested a better applicability of Pseudo-Second-Order kinetics model. Linear and non-linear isotherm studies suggested that the experimental data was better fitted to the Langmuir isotherm model. Additionally, the results also indicated that the modified finite-bath diffusion model fitted the experiments very well, with a diffusion coefficient of 1.63 ? ?10?</p><p>(-2) cm2 s-1. On the basis of above information, the ordered mesoporous carbon (OMC) modified by nitric acid and phosphoric acid can be employed as an potentially effective adsorbent for Pb2+ removal.