Stormwater runoff is one of the leading causes of water quality impairment in the U.S. Bioretention systems are ecologically engineered to treat stormwater pollution and offer exciting opportunities to provide local climate change resiliency by reducing peak runoff rates, and retaining/detaining storm volumes, yet implementation is outpacing our understanding of the underlying physical, biological, and chemical mechanisms involved in pollutant removal. Further, we do not know how performance will be affected by increases in precipitation, which are projected to occur in the northeastern U.S. as a result of climate change, or if these systems could act as a source or sink for greenhouse gas emissions. This research examines the design, construction, and development of monitoring methods for bioretention research, using the University of Vermont (UVM) Bioretention Laboratory as a case study. In addition, this research evaluates mobilization patterns and pollutant loads from road surfaces during the "first flush" of runoff, or the earlier part of a storm event. Finally, this research analyzes the comparative pollutant removal performance of bioretention systems on a treatment by treatment basis. At the UVM Bioretention Laboratory, eight lined bioretention cells were constructed with monitoring infrastructure installed at the entrance and at the subterranean effluent. A conventional, sand and compost based, bioretention soil media was compared to a proprietary media engineered to remove phosphorus, called Sorbtive Media™, under simulated increases in precipitation. Two drought tolerant vegetation mixes, native to the northeast, were compared for sediment and nutrient retention. Each treatment was sampled for soil gas emissions to determine if it was a source or a sink. The monitoring infrastructure designs used in this research allowed for the effective characterization of pollutant mass loads entering and exiting bioretention. Cumulative mass loads from stormwater were found to be highest for total suspended solids, followed by total Kjeldahl nitrogen, nitrate, non-labile phosphorus and soluble reactive phosphorus, in descending order by mass. Total suspended solids, total Kjeldahl nitrogen, and non-labile phosphorus mass were well retained by all bioretention treatments. However, the compost amendment in the conventional soil media was found to release labile nitrogen and phosphorus, far surpassing the mass loads in stormwater. When compared with conventional media, Sorbtive Media™ was highly effective at removing labile phosphorus and was also found to enhance nitrate removal. Systems containing deep-rooted vegetation (Panicum virgatum) were found to be particularly effective at retaining both labile and non-labile constituents. Overall, none of the bioretention treatments were found to be a significant source of N2O and were small sinks for CH4 in most treatments.

Research report, presented to the SBL Unisa, Midrand. / The current and future anticipated changes in the earth’s climate are a concern that has captured business’s and governments’ global attention. Climate change and its potential impacts cannot be ignored as there is ample evidence that global warming is indeed the result of anthropogenic greenhouse gas emissions. The mobile operator in Africa and the Middle East (ME) operates on continents and in parts of the world, predicted by scientists as the most vulnerable to the effects of climate change. The mobile operator in Africa and the Middle East is moreover an emitter of significant amounts of CO2 and this exacerbates the serious environmental climate change problem that humankind faces. This research paper addresses the Corporate Social Responsibility of African and Middle East (ME) mobile operators, and its Carbon Footprint. The main objectives of the research are to identify strategic risks and opportunities and the implications for the mobile operator and to determine its Greenhouse Gas emissions. The performance against targets and plans to reduce GHG emissions are also reviewed. The research is based on the questionnaire of the Carbon Disclosure Project (CDP) initiative. A shortened and modified version of the CDP was designed and emailed to two major mobile telecom operators both operating in Africa and the Middle East. It is postulated that the telecommunications industry is at an inflection point where significant changes must take place in the way energy requirements are managed. This in turn could have a positive effect on reducing its carbon footprint, benefit corporate reputation and at the same time earn “green miles” in the subscriber’s minds. The research reached the main conclusion that the mobile operators’ investigated do not yet have strategies, systems and reporting in place to be counted as “good corporate citizens” concerning their environmental responsibility. The research further concluded that a proactive strategic intent is a necessity to achieve this goal. In short: The Corporate Social Responsibility of African and Middle East mobile operators indeed has a positive effect on its Carbon Footprint.

Biomass is the world’s largest renewable energy source, accounting for approximately 10% of global primary energy supply, and 5% of energy consumed in the United States. Prominent national programs like the U.S. Renewable Fuel Standard incentivize increased use of biomass, primarily as a transportation fuel. There has been comparatively little government support for using biomass as a renewable feedstock for the chemical sector. Such asymmetry in incentives can lead to sub-optimal outcomes in the allocation of biomass toward different uses. Greenhouse gas reduction is among the most cited benefits of bioenergy and bio-based products, however, there is increasing controversy about whether increased use of biomass can actually contribute to greenhouse gas emission targets. If biomass is to play a role in current and future greenhouse gas mitigation efforts its use should be guided by efficient use of natural and economic resources. This thesis addresses these questions through a series of case studies, designed to highlight important tradeoffs in the use of biomass for greenhouse gas mitigation. Should biomass be used as a fuel, a chemical feedstock, or neither? The first case study in this thesis focuses on the ‘fuel vs feedstock’ question, examining the greenhouse gas implications of expanding the scope of the U.S. Renewable Fuel Standard to include credits for bioethylene, an important organic chemical readily produced from bioethanol. Results suggest that an expanded policy that includes bioethylene as an approved use for ethanol would provide added flexibility without compromising greenhouse gas targets – a clear win scenario. Having established that bioethylene based plastics can achieve similar greenhouse gas reductions to bioethanol used as fuel, this thesis expands the analysis by considering how the greenhouse gas emissions from a wider range of bio-based plastics compare to each of the main commodity thermoplastics produced in the U.S. The analysis demonstrates that there are large uncertainties involved in the life cycle greenhouse gas emissions from bio-based plastics, and that only a subset of pathways are likely to be preferable to conventional plastics. The following chapter then builds on the existing model to compare the greenhouse gas mitigation potential of bio-based plastics to the potential for reducing emissions by adopting low carbon energy for plastics production. That chapter concludes that switching to renewable energy across the supply chain for conventional plastics energy cuts greenhouse gas emissions by 50-75%, achieving a greater reduction, with less uncertainty and lower cost, than switching to corn-based biopolymers – the most likely near-term biopolymer option. In the long run, producing bio-based plastics from advanced feedstocks (e.g. switchgrass) and/or with renewable energy likely offers greater emission reductions. Finally, this thesis returns to the dominant form of policy surrounding biomass use: biofuel mandates. That study takes a consequential approach to the ‘fuel or neither’ question. Specifically, this work examines how petroleum refineries are likely to adjust their production in response to biofuel policies, and what this implies for the success of these policies. The research demonstrates that biofuel policies induce a shift toward greater diesel production at the expense of both gasoline and non-combustion petroleum products. This has the potential to result in an increase in greenhouse gas emissions, even before accounting for the emissions from producing the biofuels themselves.

Problemática mundial levantada nas últimas duas décadas, a geração de gases de efeito estufa (GEE) tem como parcela contribuidora a emissão de metano por ruminantes. O metano, um potente GEE, é produto final do processo fermentativo de bovinos e, por constituir perda no potencial produtivo destes, tem sido objeto de estudo por nutricionistas do mundo todo. Na busca por estratégias para diminuírem as perdas por metano, diferentes dietas, aditivos e manejos nutricionais têm sido empregados. Fontes lipídicas vegetais, como os grãos de soja, contêm alta porcentagem de ácidos graxos insaturados e este tipo lipídio pode colaborar para a diminuição da metanogênese. Em contrapartida, a inclusão de uma fonte rica em pectina (polpa cítrica) pode contribuir para aumento da produção de metano. Assim, objetivou-se com o presente experimento avaliar o efeito de diferentes fontes energéticas da dieta sobre a produção de metano e parâmetros fermentativos em bovinos. O delineamento adotado foi o quadrado latino 3x3 replicado, com período de 16 dias e 3 tratamentos: Controle: Dieta de baixo extrato etéreo (3,50% de EE); Soja: Dieta de alto extrato etéreo (inclusão de 15% de soja grão, com 5,30% de EE); Polpa: Dieta de baixo extrato etéreo e alta participação de pectina (inclusão de 15% de polpa cítrica, com 3,0% de EE). O consumo de matéria seca (CMS) foi obtido pela diferença do ofertado e a sobra da dieta nos últimos seis dias experimentais. O volume de líquido total, o volume de sólido total, o turnover de sólidos e a taxa de passagem ruminal foram obtidos pelo esvaziamento deste orgão, realizado no 11º e 12º dias experimentais, sendo realizado antes e 3 horas após a alimentação matutina. O conteúdo sólido foi retirado manualmente e o líquido com ajuda de bomba a vácuo, sendo estes pesados separadamente. Uma alíquota de 10% foi utilizada para determinar a matéria seca do conteúdo ruminal e corrigir o volume de sólido total. No 16° dia experimental, foi analisado o pH, com auxílio de uma probe de mensuração contínua. Neste mesmo dia foram realizadas coletas do conteúdo ruminal antes, 3, 6, 9 e 12 horas após a alimentação matinal, para a quantificação da produção de ácidos graxos de cadeia curta (AGCC). Também coletou líquido ruminal, com auxilio de bomba a vácuo, para análise de N-NH3. A técnica empregada para mensurar a produção de AGCC e metano foi de fermentação ruminal ex situ, que consiste em incubar frascos tipo penicilina com conteúdo ruminal sólido e líquido, em banho termostático por 30 minutos. Em seguida, a mensuração de metano e AGCC foi realizada por cromatografia gasosa e estimada a perda de energia realtiva (PER). A PER avalia a eficiência da fermentação dos alimentos, ou seja, verifica a perda de metano quando comparada aos outros produtos da fermentação. Os tratamentos apresentaram efeito (P<0,05) para CMS, Turnover de sólido e Taxa de Passagem. A dieta contendo Soja apresentou menores valores para estes parâmetros que as dietas Controle e Polpa. Os tratamentos não diferiram significativamente (P>0,05) para o Volume Sólido Total. As variáveis pH médio e máximo, tempo de pH abaixo de 5,8; 6,0 e 6,2, assim como, área de pH abaixo de 5,8 e 6,2, não diferiram (P>0,05) entre os tratamentos. Entretanto, o pH mínimo foi maior (P<0,05) para dieta contendo Soja em relação à dieta Controle, sem diferença dos dois grupos para polpa cítrica. A área de pH abaixo de 6,0 foi menos elevada (P<0,05) para o grupo soja quando comparado ao grupo controle, sem diferença dos dois grupos para polpa cítrica. Quanto ao nitrogênio amoniacal, não houve diferença (P>0,05) entre os tratamentos. As produções de AGCC totais, acetato e butirato (mMol/Kg/dia) foram mais elevadas na dieta à base de polpa cítrica e diminuída na dieta à base de grão de soja. Nenhuma dos tratamentos alterou a produção de metano ou a PER. A partir disto, essas fontes são indicadas para a utilização em dietas de bovinos, porém, a inclusão dos grãos de soja, alterou o CMS e sua inclusão resultou em mudanças no ambiente ruminal, alterando do perfil fermentativo, não demonstrando alterações na produção de metano e a PER. A inclusão de lipídios na dieta de bovinos pode diminuir a produção de metano, mas esse efeito não é específicos sobre as arqueas metanogênicas e, portanto, não altera a eficiência de fermentação ruminal. Já a pectina pode aumentar a produção de metano, por ter alta fermentabilidade ruminal, sem, contudo alterar a ineficiência deste processo. / Worldwide issue raised in the last two decades, the generation of greenhouse gases (GGE) has, a contributor parcel in the methane emission by ruminants. Methane, a powerful GGE, is the final product of cattle fermentative process and, for representing productive potential loss, has been studied by nutritionist all over the world. In the search for strategies to reduce losses by methane, different diets, additives and nutritional management have been used. Vegetable lipid sources, such as soybean grain contain high content of unsaturated fatty acids and this type of lipid can contribute to methanogenesis reduction. On the other hand, the inclusion of a high pectin (citrus pulp) source in diets can contribute for methane production increase. In this sense, the objective of the present experiment was to evaluate different energy sources in diet on methane production and fermentation parameters in cattle. The design adopted was a replicated 3x3 Latin square with 16 day period and 3 treatments: Control: Low ether extract diet (3.50% of EE); Soybean: High ether extract diet (inclusion of 15% of soybean grain with 5.30% of EE); Citrus pulp: Low ether extract and high inclusion of pectin diet (inclusion of 15% of citrus pulp with 3.0% of EE). Dry matter intake (DMI) was obtained by the difference between the offered and the surplus of the diet at the last six experimental days. Rumen total liquid volume, total solid volume, solid turnover and ruminal passage rate were obtained by the emptying of this organ performed at days 11 and 12 of each experimental period, before and 3 hours after morning feeding. The solid content was manually removed and the liquid by vacuum pulp and both samples weighed separately. A sample of 10% was used to determine dry matter of rumen content and correct total solid volume. At day 16 of experimental period, ruminal pH was determined by a data logger of continuous measurement. At this day, ruminal content sampling was carried out before, 3, 6, 9 and 12 hours after morning feeding for short chain fatty acids (SCFA) production. Rumen fluid was also collected, through vacuum pulp, for ammonia nitrogen determination. The technique applied to measure methane and SCFA production was the ex situ rumen fermentation that consists on the incubation of penicillin flasks with solid and liquid rumen content in a thermostatic bath for 30 min. After, methane and SCFA determinations were carried out by gas chromatography and the relative energy loss (REL) was estimated. The REL evaluates the efficiency of feed fermentation. In other words, verifies methane loss when compared to other fermentation products. It was observed effect of treatment (P<0.05) for DMI, rumen solid turnover and passage rate. Soybean diet had lower values than control and citrus pulp diet in all these parameters. Treatments did not significantly differ (P>0.05) for total solid volume. The variables mean and maximum ruminal pH, time wich pH was under 5.8; 6.0 and 6.2, as well as, pH area under 5.8 and 6.2 did not differ (P>0.05) between treatments. However, minimum pH was higher (P<0.05) in soybean group when compared to control, without difference of two groups to citrus pulp. pH area under 6.0 was lesser (P<0.05) in soybean group compared with control group, without difference of two groups to citrus pulp. For ammonia nitrogen determination, it was not observed difference (P>0.05) between treatments. Total SCFA, acetate and butirate production (mMol/kg/day) were increased in citrus pulp diet and were decreased in soybean diet. No diet altered (P>0.05) methane production or REL. The inclusion of lipids in the diet of cattle can reduce methane production, but this effect is not specific methanogenic archaea on and therefore does not alter the efficiency of rumen fermentation. Already pectin can increase the production of methane, having high fermentability rumen, without however changing the inefficiency of this process.

O aumento contínuo das emissões de gases causadores do efeito estufa resulta em níveis elevados de aquecimento do planeta. Estes efeitos, relacionados à mudança do clima, representam impactos na saúde humana, na produção de alimentos, nos ecossistemas e no abastecimento hídrico. Com o abastecimento hídrico afetado, as águas de menor qualidade para fins de irrigação, tornam-se importantes fontes hídricas para produção de alimentos. Dessa forma, objetivou-se estudar a tolerância da mini melancia à salinidade, bem como a resposta da cultura ao incremento de CO2 atmosférico, sob irrigação salina e não salina. O primeiro experimento foi realizado na Escola Superior de Agricultura Luiz de Queiroz (ESALQ-Piracicaba), em casa de vegetação. Cultivaram-se plantas de mini melancia, cv. Smile, irrigadas com água de diferentes condutividades elétricas- CEa (1, 2, 3, 4 e 5 dSm-1) com o objetivo de estudar a tolerância das plantas, em função do estresse salino. O segundo experimento foi realizado no Centro Nacional de Pesquisa de Informática Agropecuária (CNPTIA-Campinas) em duas câmaras de crescimento. Com objetivo de estudar como o incremento do CO2 atmosférico afeta a tolerância à salinidade da mini melancia cv. Smile. Na primeira câmara de crescimento (C1), cultivaram-se as plantas irrigadas com águas de diferentes condutividades elétricas- CEa (1 e 5 dSm-1), com aumento da concentração atmosférica de CO2 para 800 ppm. Na segunda câmara de crescimento (C2), cultivaram-se as plantas irrigadas com as mesmas condutividades elétricas da C1, entretanto com a concentração de CO2 atmosférico de 400 ppm. A salinidade afetou negativamente e o aumento da concentração de CO2 afetou positivamente a massa e o tamanho dos frutos da mini melancia. Assim, conclui-se que a mini melancia cv. Smile é moderadamente sensível à salinidade e que o aumento da concentração de CO2 atmosférico favorece o desenvolvimento dos frutos irrigados com água salina e não salina. / The continued increase in emissions of greenhouse gas effect inducing gases results in the warming of the planet. These climate change-related effects impact human health, food production, ecosystems and water supply. With the water supply affected, lower quality water becomes a possible water source for food production. Thus, the purpose of this analysis was to study the tolerance of mini watermelon to salinity and the crop response to increasing atmospheric CO2 in saline and non-saline irrigation. The first experiment was conducted at the School of Agriculture \"Luiz de Queiroz\" (ESALQ-Piracicaba), under greenhouse conditions. Mini watermelon plants were cultivated and irrigated with water of different electrical conductivities-ECw (1, 2, 3, 4 and 5 dSm-1) with the purpose of observing the behavior of plants affected by salt stress. The second experiment was carred out at the National Center of Agricultural Informatics Research (CNPTIA-Campinas) in two different growth chambers. In the first growth chamber (C1), the plants were cultivated and irrigated with different electrical conductivities-ECw (1 and 5 dSm-1), with an increase of atmospheric CO2 concentration to 800 ppm. In the second growth chamber (C2), plants were grown and irrigated with the same electrical conductivities as in C1, though the atmospheric concentration was kept at CO2 400 ppm. The salinity negatively affected the mass and the size of the fruits of mini watermelon while the increased CO2 concentration had a positive effect. Thus, it is possible to conclude that the cv. Smile mini watermelon is moderately sensitive to salinity whereas the increasing atmospheric CO2 concentration favors the development of irrigated fruit with both saline and non-saline water.

Esta pesquisa teve como objetivo quantificar a emissão de metano (CH4) proveniente da vinhaça presente em diferentes sistemas de armazenamento e transporte e, adicionalmente, avaliar, por técnicas independentes de cultivo, a microbiota funcional relacionada à produção deste gás. Para atingir esta meta foram realizados três estudos complementares. O primeiro abordou a caracterização dos sistemas de armazenamento e transporte de vinhaça encontrados no Brasil baseado em um questionário aplicado às usinas produtoras de etanol. O segundo visou quantificar as emissões de CH4 em condições de campo provenientes da vinhaça nos canais e tanques e também em laboratório em um estudo de incubação. O terceiro estudo avaliou a microbiota funcional associada à emissão de CH4 através de técnicas independentes de cultivo, como PCR em tempo real (qPCR) e pirosequenciamento. As análises microbiológicas indicaram que as emissões de CH4 são produzidas, preferencialmente, através da decomposição anaeróbia do material orgânico dissolvido da vinhaça depositados no fundo dos sistemas. Estas emissões não são desprezíveis e devem ser consideradas nos cálculos de pegada de carbono do etanol. Nos canais sem revestimento a emissão média em dois anos safras consecutivos apresentou valor de 0,75 kg CO2 eq m-3 de vinhaça, aproximadamente 5 vezes superior às emissões na parte revestida. Nos tanques a emissão foi aproximadamente setenta vezes inferior quando comparada ao canal revestido. O experimento de incubação auxiliou no entendimento de que a vinhaça sozinha não produz quantidades significativas de CH4. Entende-se que os nichos microbianos metanogênicos provavelmente são formados no sedimento, enquanto que a vinhaça mantém as condições de anaerobiose do sedimento necessárias à metanogênese e fornece nutrientes para acelerar a reação. O gênero Methanobrevibacter se mostrou dominante na comunidade microbiana metanogênica, conforme demonstrado pelo pirosequenciamento do gene 16S rRNA. Houve correlação positiva entre a abundância do gene 16S rRNA de Arquéia e dos genes funcionais mcrA e mba com a emissão de CH4. As informações sobre produção e emissão de CH4 e das características da vinhaça constituem informações importantes para tomada de decisão sobre a mitigação e/ou aproveitamento do CH4 gerado para fins econômicos e ambientais. / This research aimed to quantify methane (CH4) emissions from the vinasse in different storage and transportation systems and, additionally, to evaluate the functional microbiota associated with the production of this gas by molecular biology approaches. Three complimentary studies were performed to reach this goal. The first one was related to the characterization of main vinasse storage and transportation systems adopted in Brazil based on a survey administered to the mills, in south-central region of Brazil, producing sugarcane etanol. The second aimed to quantify the CH4 emissions from vinasse in both, field - channels and thanks - and laboratory conditions. The third study evaluated the functional microbiota associated with the CH4 emission by molecular biology approaches like real time PCR ans pyrosequencing. Microbial analysis indicated that CH4 emissions are produced preferably by anaerobic decomposition of the organic material dissolved in the vinasse and deposited on the bottom of the systems. These emissions are not negligible and should be considered in ethanol\'s carbon footprint calculations. At the uncoated part of the channel, the average emission from two crop years was 0.75 kg CO2 eq m-3 of vinasse, about 5 times greater than the emissions at the coated part. Methane emissions from the tank were about seventy times lower than from the uncoated channel. The laboratory experiment supported the understanding that the vinasse alone produces no significant emission of CH4. The microbial methanogenic niches were probably formed in the sediment, while the vinasse keeps sediment anaerobic conditions necessary for methanogenesis and provides nutrients to speed up the reaction. The Methanobrevibacter genus showed dominant in methanogenic microbial community, as demonstrated by pyrosequencing of the 16S rRNA gene. There was a positive correlation between the abundance of 16S rRNA gene Archaea and the functional mcrA and mba genes with the emission of CH4. Information on production and emission of CH4 and vinasse characteristics are important for decision making on mitigation and/or use of gas generated for economic and environmental purposes.

Increasing levels of CO2 in the atmosphere is a contributing cause to climate change. To give a better understanding, natural sources of CO2 is as important as anthropogenic sources, such as burning fossil fuels. The current role of large boreal lakes as emitters of CO2 are poorly understood and there is a clear lack of data from different types of systems. The aim of this thesis was to examine CO2 fluxes from Roxen, Glan and Vättern, three large lakes in Sweden. The purpose of the study was also to compare different approaches to get empirical CO2 flux data, and to investigate if there was difference between the lakes and study periods. Floating chambers were used as method with both direct measured fluxes and calculated fluxes. The direct fluxes were measured with sensors equipped inside the chambers. The calculated fluxes were obtained with gas samples from the chambers, water samples and wind speed in k-wind models. The results showed both temporal and spatial variability between the periods and the lakes. The results also showed a difference between the methods, where CO2 fluxes from sensors (direct measurements) ranged from -36 to 152 mmol m-2 d-1 and the calculated fluxes from the CC-model (Cole &amp; Caraco 1998) ranged from –29 to 58 mmol m-2 d-1. / Ökande halter av CO2 i atmosfären är en bidragande faktor till klimatförändringar. För att få en bättre förståelse för de så behövs kunskap om naturliga flöden, inte enbart antropogena källor, som t.ex. förbränning av fossila bränslen som störst fokus kretsar kring. Den nuvarande kunskapsnivån om större nordiska sjöars CO2 utsläpp är begränsad, och det finns en tydlig brist i data från dessa typer av system. Målet med denna uppsats var att utforska CO2 flöden från Roxen, Glan och Vättern, tre stora sjöar i Sverige. Syftet med studien var också att jämföra olika sätt att samla in empiriskt material samt undersöka om det fanns skillnader mellan sjöarna samt de olika studerade perioderna. Flytande kammare användes för att samla in prover som mättes direkt genom en sensor, men de användes också för att ta manuella gasprover som sedan beräknade flödet av CO2 med hjälp av modeller i efterhand. Resultatet visade både på skillnader i tid och rum mellan perioderna och sjöarna. Resultatet visade även att det fanns en skillnad mellan de olika metoderna vi använde oss av, där sensor (direkta mätningar) var mellan -36 to 152 mmol m-2 d-1 och flödesberäkningarna från CC-modellen (Cole &amp; Caraco 1998) var –29 to 58 mmol m-2 d-1.

The objective of the research is to develop various green-house gas (GHG) mitigations scenarios in the energy demand and supply sectors for state of Florida through energy and environment modeling tool called LEAP (Long Range Energy Alternative Planning System Model) for 2010-2050. The GHG mitigation scenarios consist of various demand and supply side scenarios. One of the GHG mitigation scenarios is crafted by taking into account the available renewable resources potential for power generation in the state of Florida and then the comparison has been made for transformation sector and corresponding GHG emissions through this newly developed mitigation scenario versus Business As Usual and Florida State Policy scenario. Moreover two master mitigation scenarios (Electrification and Efficiency and Lifestyle) were crafted through combination of certain GHG mitigation scenarios. The energy demand and GHG emissions assessment is performed for both master mitigation scenarios versus business As Usual scenario for 2010 – 2050. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Salt marshes provide a range of ecosystem services and yet are subjected to anthropogenic impacts that alter the biogeochemical processes underlying these services. In particular, human activities may modify salt marsh greenhouse gas (carbon dioxide, methane, nitrous oxide) emissions by changing plant and microbial communities, hydrological regime, and sediment chemistry. Quantifying the effects of human impacts on greenhouse gas emissions is important for complete carbon budgets, and for effective management of salt marshes and the ecosystem services they provide. In Chapters 1 and 2, I investigate the effects of hydrology and plant invasion on greenhouse gas emissions. First, I show how the restriction and restoration history of four salt marshes influence methane flux in unpredictable ways. Despite comparable salinity, methane emissions from one partially restored marsh were 25 times higher than unimpacted reference sites 13+ years after restoration, but emissions from other restored sites were equal or lower. Next, I show that greenhouse gas emissions associated with invasive Phragmites australis are not different from those associated with native Spartina alterniflora. These Chapters demonstrate the de-coupling of greenhouse gas emissions, and carbon sequestration more generally, from ecosystem degradation and restoration. In Chapters 3 and 4, I quantify greenhouse gas fluxes and microbial community structure under precipitation changes that may occur with global climate change. In a field experiment, doubled rainfall and drought had significant transient impacts on porewater salinity following storms, and on the community structure of plants (doubled rainfall) or microbes (drought), yet greenhouse gas fluxes and other biogeochemical processes were not affected. The absence of biogeochemical change indicates functional redundancy and resistance or resilience exist in the microbial community, suggesting marshes may continue providing services as precipitation changes. In a lab experiment, rewetting intact cores to simulate tidal inundation or rainstorms produced a nitrous oxide pulse 10-20x the baseline flux rates, without changing the microbial community. A model of rewetting event frequency suggests that pulsed emissions may be responsible for the majority of marsh nitrous oxide emission. Precipitation change may increase coastal nitrous oxide emission if it causes more or stronger storms, and thus more rewetting events.

This dissertation describes methodologies for evaluating a set of anticipated and recommended energy infrastructure changes essential to achieving deep greenhouse gas emissions reductions in a dense urban area: Deep penetration of grid-connected wind power, widespread adoption of electric heat pumps, multiple potential services from extensive deployment of distributed generation, and increasing focus on auxiliary energy in heating and cooling systems as cities continue to grow in population and height. The focus of the research presented here was New York City and the surrounding New York State electricity supply infrastructure. After developing a wind power model based on an NREL model wind data set, a linear program model showed that after passing a low-curtailment threshold of 10 GW, energy-related wind power curtailment is driven largely by continuous operation of baseload generation and misalignment of winter wind power peaks and existing summer electricity demand peaks. Separate analyses showed the potential for increase wind-generated electricity utilization through increased use of heat pumps in New York City. A suite of models was developed to assess the zonal effects in New York City of deep statewide penetration of wind power and widespread adoption of electric heat pumps in New York City. New York City was found to have highly fluctuating net loads in deep wind penetration scenarios. Further, with large amounts of existing space heating demand replaced by heat pumps, the increased winter electricity demand peaks occurred infrequently enough that the additional generation capacity required to meet those loads would have a capacity factor well less than 1%. Small-scale, natural gas-fueled internal combustion engines deployed as distributed generation were shown to improve the ability of the system to respond to load fluctuations, to be a more economical option than new large centralized generators at the low capacity factor, and to reduce overall system gas usage due to mitigating part-load effects and startup fuel requirements. This distributed generation, which could in reality also include combined heat and power systems as well as battery storage standing alone, connected to rooftop solar or in electric vehicles, also has potential system resilience benefits. The last research effort described here included long-term monitoring of a high-rise mixed use building’s hydronic system before and after a retrofit of hydraulic equipment. Significant annual reductions of 40% energy usage for pumping were computed, primarily due to part-load flow control effects. Analysis of the monitoring data, as well as computations related to theoretical performance of hydraulic networks, showed that this approach also has potential to reduce peak loads, particularly in high-rise buildings.