960 resultados para Economics, General|Environmental Sciences


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The purpose of this study was to develop a series of workshops designed to raise the environmental literacy of a community college faculty and facilitate infusion of an environmental perspective into the courses they teach. Data was gathered on the effect of the workshops on the level of environmental literacy of the participants as well as the persistence of any observed effect. How faculty infused an environmental perspective into their courses was also explored.^ The workshop model was developed by reviewing adult learning and change theories, case studies of workshops at other colleges, environmental education research, and results of a pilot study. Content, organization, and delivery methods from these sources were selected and integrated to create the 14 components of the model employed by the workshops in this study.^ Forty-two faculty from the North Campus of Broward Community College participated in the study. The 20 workshop participants from seven academic departments attended seven two hour workshops during the fall term of 1996, and implemented projects to infuse environmental topics into their courses the following term. A quasi-experimental pretest-posttest-delayed posttest nonequivalent control group design was employed in which the 22 members of the control group who did not attend the workshops were administered the Wisconsin Environmental Survey at the same time as the workshop participants (immediately before the first workshop, immediately following the last workshop, and four months following the completion of the workshop series). This instrument, an adaption of the Wisconsin High School Student Environmental Survey, yielded three measures of environmental literacy: Affective, Behavior, and Cognitive Subscale scores.^ The repeated measures MANOVA performed using the scores of the two groups on the three administrations of WES revealed a significant interaction for group by time, so repeated measures ANOVA were performed for each of the three subscales to investigate the interaction. Tukey-HSD post hoc comparisons indicated that for all three subscale scores, the two groups were not significantly different on the pretest, but on the posttest and the delayed posttest, the workshop participants demonstrated significantly higher levels of environmental literacy. All statistical tests were performed at $\alpha$ =.05. ^

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The purpose of this study is to characterize the degradation products of Irgarol 1051(2-methylthio-4-tertbutylamino-6-cyclopropylamino- s-triazine), a compound recently developed for use as an antifouling agent on boat hulls. The photolytic fate of this compound in different natural waters will be used in the development of a monitoring program designed to survey the occurrence of this compound and its degradation products in South Florida marinas, the Miami River and surrounding coastal areas. ^ The transformation of Irgarol 1051 and degradation rate constants were characterized in a photo-reactor under simulated natural conditions. The degradation pathway in the UVB-UVA region (300nm to 350nm) closely resembled the transformations under natural conditions in the pond, showing that both direct photolysis and the presence of natural sensitizers play an important role in the abiotic transformation of this compound. Irgarol 1051 has an average environmental half-life of 10 days in surface waters. Average concentrations from samples around Biscayne Bay and the Miami River increased from 1–5 ng/L during 1999 and increased to between 28 and 38 ng/L in 2001, respectively. Irgarol concentrations showed a strong correlation with concentrations of its major transformation product, M1, from samples collected as part of the study ([M1]/[Irgarol] = 0.247, R2 = 0.9165, n = 125). ^

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The goal of this project was to explore activism, attitudes, and imagery connecting Black churchgoers in Miami, Florida and the natural environment. The research approach was qualitative, began as exploratory research, and used the techniques of snowball sampling, participant observation, and semi-structured interviews. Three case studies representing various socio-economic levels, denominations, participant education levels, and environmental facets were chosen for in-depth ethnographic research. There are three major findings in the research. First, there is a link between the preservation of Black history and the preservation of the environment among Black churchgoers, who feel strong connections to a sense of place, rural life, and the past. However their work is strongly directed to bring about benefits for people and the environment in the present and the future. Second, public access to public lands is a basic and important right espoused by these Black churchgoing activists. Third, the vocabulary used by Black churchgoing activists regarding the natural environment differs from today's “mainstream” environmentalists. The concept of “beauty” is pivotal to Black appreciation of and activism toward the environment and is reminiscent of the early environmental protection movement in the United States and conservationists such as John Muir. These findings concerning how Black spirituality relates to the environment adds to the sparse literature on the subject, and provides for potential linkages between Blacks and “mainstream” environmental groups to benefit both parties. An understanding of the connections between Black spirituality and perceptions of the environment should facilitate the development of better programs to improve and protect the environment. Environmental projects may also address the social and economic needs of Black communities, churches, and congregations, as well as the ecosystem. ^

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The Everglades are undergoing the world largest wetland restoration project with the aim of returning this system to hydrological conditions in place prior to anthropogenic modifications. Therefore, it is essential to know what these pristine conditions were. In this work, molecular marker (biomarker) distributions and carbon stable isotopic signatures in sediment samples were employed to assess historical environmental changes in Florida Bay over approximately the last 4000 years. Two biomarkers of terrestrial plants, particularly for mangroves (taraxerol and C29 n-alkane), combined with two seagrass proxies (the Paq and the C25/C 27 n-alkan-2-one ratio) revealed a sedimentary environmental shift from freshwater marshes to mangrove swamps and then to seagrass dominated marine ecosystems, likely as a result of sea-level rise in Florida Bay since the Holocene. The maximum values for the Paq and the C 25/C27 n-alkan-2-ones occurred during the 20th century, suggesting that the greatest abundance of seagrass cover is a recent rather than a historical, long-term phenomenon. The greater oscillation in frequency and amplitude for the biomarkers after 1900 potentially reflects an ecosystem under increasing anthropogenic stress. Several algal biomarkers such as C20 highly branched isoprenoids (HBIs), C 25 HBIs and dinosterol indicative of cyanobacteria, diatom and dinoflagellate organic matter inputs respectively, increased dramatically in the latter part of the 20th century and were attributed to recent anthropogenic changes in Florida Bay. ^ The highlight of this work is the development of HBIs as paleo-proxies. As biomarkers of diatoms, the C25 HBIs in the core from the central bay displayed the highest concentration at mid depth, reflecting strong historical inputs of diatom-derived sedimentary OM during that period. In fact, the depth profile of C25 HBIs coincided quite well with historical variations in diatom abundance and variations in diatom species composition in central Florida Bay based on the results of fossil diatom species analysis by microscopy. This study provides evidence that some C25 HBIs can be applied as biomarkers for certain diatom inputs in paleoenvironmental studies. The sources of C20 and C30 HBIs and their potential applicability as paleo-proxies were also investigated and their sources assessed based on their δ13C distributions. ^

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The common occurrence of human derived contaminants like pharmaceuticals, steroids and hormones in surface waters has raised the awareness of the role played by the release of treated or untreated sewage in the water quality along sensitive coastal ecosystems. South Florida is home to many important protected environments ranging from wetlands to coral reefs which are in close proximity to large metropolitan cities. Since large portions of South Florida and most of the Florida Keys population are not served by modern sewage treatment plants and rely heavily on the use of inefficient septic systems; a comprehensive survey of selected human waste contamination markers is needed in these areas to assess water quality with respect to non-traditional micro-constituents. ^ This study reports the development and application of new sensitive and selective analytical methods for the fast screening of multiple wastewater tracers, classified as Emergent Pollutants of Concern (EPOC). Novel methods for the trace analysis of non-traditional markers of human-specific contamination such as aminopropanone were developed and used to assess the potential of non-traditional markers as wastewater tracers. ^ During our investigation, surface water samples collected from near shore environments along the South Florida were analyzed for fifteen hormones and steroids, and five commonly detected pharmaceuticals. The compounds most frequently detected were: coprostanol, cholesterol, estrone, β-estradiol, caffeine, triclosan and DEET. Concentrations of caffeine, bisphenol A and DEET were usually higher and more prevalent than the hormonal steroids. In general, it was found that common pharmaceuticals and steroids are widely present in major coastal environments in South Florida. It is also evident that aquatic bodies in heavily urbanized sectors such as the Miami River and Key Largo Harbor contain higher concentrations of several compounds while relatively open bay waters and agricultural areas show reduced chemical signatures. Concentrations of hormones in the Little Venice area of Marathon Key were above the Lowest Observable Effect Levels (LOELs) for several species, indicating that biological resources in this area are at risk. Water quality issues in some of these coastal water environments go beyond eutrophication, thus EPOC should be the target goal for future mitigation projects. ^

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Exchange rate economics has achieved substantial development in the past few decades. Despite extensive research, a large number of unresolved problems remain in the exchange rate debate. This dissertation studied three puzzling issues aiming to improve our understanding of exchange rate behavior. Chapter Two used advanced econometric techniques to model and forecast exchange rate dynamics. Chapter Three and Chapter Four studied issues related to exchange rates using the theory of New Open Economy Macroeconomics. ^ Chapter Two empirically examined the short-run forecastability of nominal exchange rates. It analyzed important empirical regularities in daily exchange rates. Through a series of hypothesis tests, a best-fitting fractionally integrated GARCH model with skewed student-t error distribution was identified. The forecasting performance of the model was compared with that of a random walk model. Results supported the contention that nominal exchange rates seem to be unpredictable over the short run in the sense that the best-fitting model cannot beat the random walk model in forecasting exchange rate movements. ^ Chapter Three assessed the ability of dynamic general-equilibrium sticky-price monetary models to generate volatile foreign exchange risk premia. It developed a tractable two-country model where agents face a cash-in-advance constraint and set prices to the local market; the exogenous money supply process exhibits time-varying volatility. The model yielded approximate closed form solutions for risk premia and real exchange rates. Numerical results provided quantitative evidence that volatile risk premia can endogenously arise in a new open economy macroeconomic model. Thus, the model had potential to rationalize the Uncovered Interest Parity Puzzle. ^ Chapter Four sought to resolve the consumption-real exchange rate anomaly, which refers to the inability of most international macro models to generate negative cross-correlations between real exchange rates and relative consumption across two countries as observed in the data. While maintaining the assumption of complete asset markets, this chapter introduced endogenously segmented asset markets into a dynamic sticky-price monetary model. Simulation results showed that such a model could replicate the stylized fact that real exchange rates tend to move in an opposite direction with respect to relative consumption. ^

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Compared to phosphorus (P), nitrogen (N) has received little attention across the Everglades landscape. Despite this lack of attention, N plays important roles in many Everglades systems, including being a significant pollutant in Florida Bay and the Gulf of Mexico, the limiting nutrient in highly P-impacted areas, and an important substrate for microbial metabolism. Storage and transport of N throughout the Everglades is dominated by organic forms, including peat soils and dissolved organic N in the water column. In general, N sources are highest in the northern areas; however, atmospheric deposition and active N2 fixation by the periphyton components are a significant N source throughout most systems. Many of the processes involved in the wetland N cycle remain unmeasured for most of the Everglades systems. In particular, the lack of in situ rates for N2 fixation and denitrification prevent the construction of system-level budgets, especially for the Southern mangrove systems where N export into Florida Bay is critical. There is also the potential for several novel N processes (e.g., Anammox) with an as yet undetermined importance for nitrogen cycling and function of the Everglades ecosystem. Phosphorus loading alters the N cycle by stimulating organic N mineralization with resulting flux of ammonium and DON, and at elevated P concentrations, by increasing rates of N2 fixation and N assimilation. Restoration of hydrology has a potential for significantly impacting N cycling in the Everglades both in terms of affecting N transport, but also by altering aerobic-anaerobic transitions at the soil-water interface or in areas with seasonal drawdowns (e.g., marl prairies). Based on the authors’ understanding of N processes, much more research is necessary to adequately predict potential impacts from hydrologic restoration, as well as the function of Everglades systems as sinks, sources, and transformers of N in the South Florida landscape.

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Public opinion polls in the United States reveal that a great majority of Americans are aware and show concern about ecological issues and the need to preserve natural areas. In South Florida, natural resources have been subjected to enormous strain as the pressure to accommodate a growing population has led to rapid development. Suburbs have been built on areas that were once natural wetlands and farmlands, and the impact today shows a landscape where natural places have all but disappeared. This dissertation examines the intersection between the perceptions that individuals living in the South Florida region have with respect to the natural environment and local ecological problems with where their relationship to nature takes place. ^ The research is based upon both quantitative and qualitative data. The principal methodology used in this research is the ethnographic method, which employed the data gathering techniques of in-depth interviewing and participant observation. The objective of the qualitative portion of the study was to determine how people perceive and relate to their immediate environment. The quantitative portion of the study employed telephone survey data from the FIU/Florida Poll 2000. Data collected through this survey provided the basis to statistically test responses to the research questions. ^ The findings show that people in South Florida have a general idea of the relationship between the human population and the environment but very little knowledge of how they individually affect each other. The experience of private places and public spaces in everyday life permits people to compartmentalize cultural values and understandings of the natural world in separate cognitive schemas. The appreciation of the natural world has almost no connection to their personal sense of obligation to preserve the environment. That obligation is only felt in their home space even though the South Florida environment overall struggles desperately with water shortages, land encroachment, and a rapidly expanding human population whose activities continuously aggravate an already delicate natural balance. ^

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Vegetation patterns of mangroves in the Florida Coastal Everglades (FCE) result from the interaction of environmental gradients and natural disturbances (i.e., hurricanes), creating an array of distinct riverine and scrub mangroves across the landscape. We investigated how landscape patterns of biomass and total net primary productivity (NPPT), including allocation in above- and below-ground mangrove components, vary inter-annually (2001–2004) across gradients in soil properties and hydroperiod in two distinct FCE basins: Shark River Estuary and Taylor River Slough. We propose that the allocation of belowground biomass and productivity (NPPB) relative to aboveground allocation is greater in regions with P limitation and permanent flooding. Porewater sulfide was significantly higher in Taylor River (1.2 ± 0.3 mM) compared to Shark River (0.1 ± 0.03 mM) indicating the lack of a tidal signature and more permanent flooding in this basin. There was a decrease in soil P density and corresponding increase in soil N:P from the mouth (28) to upstream locations (46–105) in Shark River that was consistent with previous results in this region. Taylor River sites showed the highest P limitation (soil N:P > 60). Average NPPT was double in higher P environments (17.0 ± 1.1 Mg ha−1 yr−1) compared to lower P regions (8.3 ± 0.3 Mg ha−1 yr−1). Root biomass to aboveground wood biomass (BGB:AWB) ratio was 17 times higher in P-limited environments demonstrating the allocation strategies of mangroves under resource limitation. Riverine mangroves allocated most of the NPPT to aboveground (69%) while scrub mangroves showed the highest allocation to belowground (58%). The total production to biomass (P:B) ratios were lower in Shark River sites (0.11 yr−1); whereas in Taylor River sites P:B ratios were higher and more variable (0.13–0.24 yr−1). Our results suggest that the interaction of lower P availability in Taylor River relative to Shark River basin, along with higher sulfide and permanent flooding account for higher allocation of belowground biomass and production, at expenses of aboveground growth and wood biomass. These distinct patterns of carbon partitioning between riverine and scrub mangroves in response to environmental stress support our hypothesis that belowground allocation is a significant contribution to soil carbon storage in forested wetlands across FCE, particularly in P-limited scrub mangroves. Elucidating these biomass strategies will improve analysis of carbon budgets (storage and production) in neotropical mangroves and understanding what conditions lead to net carbon sinks in the tropical coastal zone.

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Wetlands are ecosystems commonly characterized by elevated levels of dissolved organic carbon (DOC), and although they cover a surface area less than 2 % worldwide, they are an important carbon source representing an estimated 15 % of global annual DOC flux to the oceans. Because of their unique hydrological characteristics, fire can be an important ecological driver in pulsed wetland systems. Consequently, wetlands may be important sources not only of DOC but also of products derived from biomass burning, such as dissolved black carbon (DBC). However, the biogeochemistry of DBC in wetlands has not been studied in detail. The objective of this study is to determine the environmental dynamics of DBC in different fire-impacted wetlands. An intensive, 2-year spatial and temporal dynamics study of DBC in a coastal wetland, the Everglades (Florida) system, as well as one-time sampling surveys for the other two inland wetlands, Okavango Delta (Botswana) and the Pantanal (Brazil), were reported. Our data reveal that DBC dynamics are strongly coupled with the DOC dynamics regardless of location, season or recent fire history. The statistically significant linear regression between DOC and DBC was applied to estimate DBC fluxes to the coastal zone through two main riverine DOC export routes in the Everglades ecosystem. The presence of significant amounts of DBC in these three fire-impacted ecosystems suggests that sub-tropical wetlands could represent an important continental-ocean carrier of combustion products from biomass burning. The discrimination of DBC molecular structure (i.e. aromaticity) between coastal and terrestrial samples, and between samples collected in wet and dry season, suggests that spatially-significant variation in DBC source strength and/or degree of degradation may also influence DBC dynamics.

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In 2005 we initiated a project designed to better understand tree island structure and function in the Everglades and the wetlands bordering it. Focus was on the raised portions at the upstream end of the islands, where tropical hardwood species adapted to well-drained conditions usually are the most prominent component of the vegetation. The study design is hierarchical, with four levels; in general, a large number of sites is to be surveyed once for a limited set of parameters, and increasingly small sets of islands are to be sampled more intensively, more frequently, and for more aspects of ecosystem function. During the first year of the 3-year study, we completed surveys of 41 Level 1 (i.e., the least intensive level) islands, and established permanent plots in two and three islands of Levels 2 and 4 intensity, respectively. Tree species richness and structural complexity was highest in Shark Slough “hammocks”, while islands in Northeast Shark Slough and Water Conservation Area 3B, which receive heavy human use, were simpler, more park-like communities. Initial monitoring of soil moisture in Level 4 hammocks indicated considerable local variation, presumably associated with antecedent rainfall and current water levels in the adjacent marsh. Tree islands throughout the study area were impacted significantly by Hurricanes Katrina and Wilma in 2005, but appear to be recovering rapidly. As the project continues to include more islands and repeated measurements, we expect to develop a better grasp of tree island dynamics across the Everglades ecosystem, especially with respect to moisture relations and water levels in the adjacent marsh. The detailed progress report which follows is also available online at http://www.fiu.edu/~serp1/projects/treeislands/tree_islands_2005_annual_report.pd

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Fire, which affects community structure and composition at all trophic levels, is an integral component of the Everglades ecosystem (Wade et al. 1980; Lockwood et al. 2003). Without fire, the Everglades as we know it today would be a much different place. This is particularly true for the short-hydroperiod marl prairies that predominate on the eastern and western flanks of Shark River Slough, Everglades National Park (Figure 1). In general, fire in a tropical or sub-tropical grassland community favors the dominance of C4 grasses over C3 species (Roscoe et al. 2000; Briggs et al. 2005). Within this pyrogenic graminoid community also, periodic natural fires, together with suitable hydrologic regime, maintain and advance the dominance of C4 vs C3 graminoids (Sah et al. 2008), and suppress the encroachment of woody stems (Hanan et al. 2009; Hanan et al. unpublished manuscript) originating from the tree islands that, in places, dominate the landscape within this community. However, fires, under drought conditions and elevated fuel loads, can spread quickly throughout the landscape, oxidizing organic soils, both in the prairie and in the tree islands, and, in the process, lead to shifts in vegetation composition. This is particularly true when a fire immediately precedes a flood event (Herndon et al. 1991; Lodge 2005; Sah et al. 2010), or if so much soil is consumed during the fire that the hydrologic regime is permanently altered as a result of a decrease in elevation (Zaffke 1983).

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This dissertation consists of three essays on different aspects of water management. The first essay focuses on the sustainability of freshwater use by introducing the notion that altruistic parents do bequeath economic assets for their offspring. Constructing a two-period, over-lapping generational model, an optimal ratio of consumption and pollution for old and young generations in each period is determined. Optimal levels of water consumption and pollution change according to different parameters, such as, altruistic degree, natural recharge rate, and population growth. The second essay concerns water sharing between countries in the case of trans-boundary river basins. The paper recognizes that side payments fail to forge water-sharing agreement among the international community and that downstream countries have weak bargaining power. An interconnected game approach is developed by linking the water allocation issue with other non-water issues such as trade or border security problems, creating symmetry between countries in bargaining power. An interconnected game forces two countries to at least partially cooperate under some circumstances. The third essay introduces the concept of virtual water (VW) into a traditional international trade model in order to estimate water savings for a water scarce country. A two country, two products and two factors trade model is developed, which includes not only consumers and producer's surplus, but also environmental externality of water use. The model shows that VW trade saves water and increases global and local welfare. This study should help policy makers to design appropriate subsidy or tax policy to promote water savings especially in water scarce countries.^

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This study attempted to determine if an excessive amount of 1,1,1 - Trichloroethane was released into the air, the acute effects of exposure and the cause(s) of excessive use. The types of degreasing equipments which were tested in this study are straight vapor and the vapor spray machines. The instruments utilized to obtain the data for this study are Gastech Haline Detector, Organic Vapor Monitor Badge and Personal Sampling Pump. Readings were taken on three different tanks. The data accumulated by this study were obtained during actual cleaning operation. During testing, increased exposure was detected due to exceeding the rate of removal, downward drafts were blowing right over the top of a degreaser and, in some cases, poor general ventilation caused solvent vapor to be blown out of the tank and into the workers' breathing zone, affecting excessive vapor drag out and solvent loss. The results show that, since the characteristics of solvent 1,1,1 - Trichloroethane are well suited to vapor degreasing requirements, by using proper procedures and maintenance, 1,1,1 - Trichloroethane emission during vapor degreasing can be controlled at levels well below the industrial hygiene standard established by OSHA for safe and healthful conditions.

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A comprehensive forensic investigation of sensitive ecosystems in the Everglades Area is presented. Assessing the background levels of contamination in these ecosystems represents a vital resource to build up forensic evidence required to enforce future environmental crimes within the studied areas. This investigation presents the development and validation of a fractionation and isolation method for two families of herbicides commonly applied in the vicinity of the study area, including phenoxy acids like 2,4-D, MCPA, and silvex; as well as the most common triazine-based herbicides like atrazine, prometyne, simazine and related metabolites like DIA and DEA. Accelerated solvent extraction (ASE) and solid phase extraction (SPE) were used to isolate the analytes from abiotic matrices containing large amounts of organic material. Atmospheric-pressure ionization (API) with electrospray ionization in negative mode (ESP-), and Chemical Ionization in the positive mode (APCI+) were used to perform the characterization of the herbicides of interest.