Establecer una cota global a las emisiones de gases de efecto invernadero ha sido imposibilitado por la complejidad que conlleva demostrar los efectos de la contribución humana al efecto invernadero. Para alcanzar un desarrollo sostenible es necesario, primero limitar y en lo posible eliminar las emisiones de dichos gases a la atmosfera. En este contexto, la adsorción de gases se ha establecido como una de las alternativas más efectivas a mediano plazo para la reducción de emisiones de gases de efecto invernadero. Por lo tanto, en esta tesis, el objetivo principal es estudiar a nivel molecular la adsorción de gases de efecto invernadero y comprender mejor la interacción entre las distintas variables que afectan el proceso de captura. En la primera parte de esta tesis se estudió, la separación de una mezcla de hexafluoruro de azufre (SF6) y nitrógeno (N2). El SF6 se emite en pequeñas cantidades, sin embargo por ser un potente gas de efecto invernadero con un tiempo de vida extremadamente alto se requiere un control estricto de sus emisiones. En este trabajo se estudió, empleando modelos simples, el efecto del tamaño de poro, la presión y la composición de la mezcla en la separación selectiva del SF6. Posteriormente, se realizaron simulaciones con modelos realistas de dos carbonos réplicas de zeolitas y se encontró que la selectividad predicha para el SF6 en dichos materiales es superior a la de los materiales previamente reportados en la literatura. En la segunda parte del trabajo se estudió el uso de estos materiales de carbono para la captura de dióxido de carbono (CO2) a temperatura ambiente, y se encontró que su capacidad de captura de CO2 a altas presiones es comparable a la de los mejores adsorbentes de CO2 reportados. Para comprender mejor la captura en los carbonos réplicas de zeolitas, se emplearon simulaciones moleculares para obtener información acerca de su compleja estructura interna y predecir las interacciones del CO2 con el interior de estos materiales. En la parte final de esta tesis se estudiaron materiales híbridos organo-inorgánicos, en particular, adsorbentes de sílica funcionalizados con grupos amino. Se desarrolló una nueva metodología de simulación para la generación de materiales de sílica funcionalizados con cadenas orgánicas y el cálculo de sus propiedades de adsorción. La metodología se evaluó empleando modelos de sílica gel y MCM-41 funcionalizados con diferentes cadenas orgánicas, comparando los resultados de las simulaciones de las isotermas de adsorción y la densidad de funcionalización con datos experimentales. Simultáneamente, se desarrolló un nuevo método que permite calcular adicionalmente a la fisisorción la quimisorción del CO2 en las aminas empleando simulaciones moleculares. En resumen, esta tesis de doctorado resalta diferentes posibilidades para la captura y separación de gases de efecto invernadero y proporciona nuevas herramientas de simulación para evaluar y optimizar sistemas de captura de gases. Esta tesis se enmarca dentro de la ciencia de materiales y muestra como la investigación básica en este campo puede ser usada como una herramienta para evaluar y optimizar procesos industriales. / The establishment of a global limit on the emissions of greenhouse gases has been hindered by the complexity to prove the effects of manmade greenhouse gases on a global scale. In order to achieve a sustainable development it is important to limit, and when possible eliminate, emissions of industrial greenhouse gases to the atmosphere. In this context, adsorption has been established as one of the best cost-effective means of reducing emissions of greenhouse gases in the short-term. Thus, in this thesis, the main objective is to study at a molecular level the adsorption of greenhouse gases and to obtain a better insight into the capture processes for their future optimization. Molecular simulations are used in order to find the optimal diameter for the separation of sulfur hexafluoride (SF6) from nitrogen (N2); this mixture is commonly used in electrical applications. SF6 is typically emitted in small quantities, but because it is a potent greenhouse gas and possesses extremely long lifetimes, there is a pressing need for a strict control of its emissions. The effect of pore size, pressure, and mixture compositions on the selective adsorption of SF6 was investigated using simple models. Subsequently, simulations using two atomistic models of zeolite templated carbons were performed. The separation selectivities compared favorably to the materials previously reported for the separation of this mixture. Moreover, the potential use of these two templated carbon materials to capture carbon dioxide (CO2) at room temperature is reported. Their high-pressure CO2 adsorption isotherms are among the highest carbon capture capacity for carbonaceous materials and are comparable to the best CO2 adsorbing materials. In addition, the simulated adsorption isotherms were used to obtain new insights into the adsorption process of the templated carbons. In the final part of the thesis hybrid organic-inorganic adsorbents were studied. For CO2 capture, solid adsorbents are functionalized with amino groups that largely increase their adsorption capabilities. However, the underlying mechanism of the adsorption process in the functionalized materials is not fully understood, limiting the possibility of designing optimal adsorbent materials for different applications. The adsorption of CO2 in aminefunctionalized silica materials was studied using Monte Carlo molecular simulations. A simulation methodology for the design of functionalized silica materials was proposed. The methodology was evaluated using models of silica gel and MCM-41 functionalized with different organic groups, comparing the resulting adsorption isotherms and grafting density to available experimental data. Furthermore, a new scheme that allows accounting for the chemisorbed CO2 on the adsorption isotherms is presented In summary, this PhD thesis highlights different possibilities for the capture and separation of greenhouse gases and provides new tools for evaluating and optimizing capture systems. Finally, this dissertation shows the use of basic research in Materials Science as an established tool for evaluating and optimizing thermodynamics of engineering processes.

Reservoirs impound and store large volumes of water and flood land. The water is used for electricity generation, irrigation, industrial and municipal consumption, flood control and to improve navigation. The decomposition of flooded soil and vegetation creates greenhouse gases and thus reservoirs are a source of greenhouse gases. Reservoirs are not well studied for greenhouse gas flux from the water to the atmosphere. The FLooded Upland Dynamics EXperiment (FLUDEX) involves the creation of three experimental reservoirs in the upland boreal forest to study greenhouse gas and mercury dynamics. The balance of biological processes, decomposition, primary production, CH₄ oxidation and the nitrogen cycle in the reservoirs controls the greenhouse gas flux from the reservoir to the atmosphere. Understanding the importance and controlling factors of these processes is vital to understanding the sources and sinks of greenhouse gases within reservoirs. The carbon and oxygen dynamics near the sediment-water interface are very important to the entire reservoir because many processes occur in this area. Light and dark benthic chambers were deployed, side-by-side, to determine the benthic flux of DIC and CH₄ across the sediment-water interface and to determine the role of benthic photoautotrophs in benthic DIC, CH₄ and O₂ cycling. Benthic chambers have shown photoautotrophs use the decomposing soil, rocks and exposed bedrock as a physical substrate to colonize and the CO₂ produced by the decomposing soil as a carbon source since the delta¹³C-DIC value of the DIC added to light chambers is enriched relative to dark chambers and net photosynthesis rates are linked to community respiration. Benthic photoautotrophs consume 15-33% of the potential DIC flux into the water column. CH₄ produced by the decomposition of soils is partially oxidized by methanotrophs that use the photosynthetically produced oxygen. The delta¹³C-CH₄ values of the CH₄ added to light chambers is enriched relative to dark chambers and 15-88% of the potential CH₄ flux into the water column is oxidized. An isotope-mass budget for DIC and CH₄ is presented for each reservoir to identify the importance of processes on areservoir scale. Input of DIC to the reservoirs from overland flow can be important because concentration is greater and delta¹³C-DIC values are depleted relative to inflow from Roddy Lake. Estimates of total reservoir primary production indicate that 3-19% of the total DIC production from decomposition is removed by photoautotrophs. The carbon cycling in biofilm and the importance of periphytic primary production needs to be better understood. Dissolved delta¹³C-CH₄ values of CH₄ in reservoir outflow enriched 45-60permil, indicating that CH₄ oxidation was an important CH₄ sink within the reservoirs. Stable carbon isotope data indicates that the CH₄ in the bubbles is partially oxidized so the site of bubble formation is the upper portion of the flooded soil. The fraction of CH₄ converted to CO₂ in the FLUDEX reservoirs is similar to that of the wetland flooded for the Experimental Lakes Area Reservoir Project (ELARP). Approximately half of the dissolved CH₄ in the FLUDEX reservoirs was removedby CH₄ oxidation. The ebullitive flux of CH₄ from FLUDEX reservoirs is reduced 25-75% by CH₄ oxidation. The CH₄ flux to the atmosphere from peat surface of the ELARP reservoir became less oxidized after flooding: 91% to 85% oxidized. The floating peat islands of the ELARP reservoir were less oxidized than the peat surface. Similar to the CH₄ in the FLUDEX reservoirs, CH₄ in the ELARP peat islands was oxidized 56%. CH₄ oxidation is an important process because it reduces the global warming potential of the greenhouse gas flux since CO₂ is less radiatively active than CH₄.

Through appropriate soil and crop residue management, soil can function as a sink for carbon (C) and nitrogen (N) for the mitigation of greenhouse gases (GHG). No research has yet investigated the potential of intercrop agroecosystems to reduce emissions of GHG to the atmosphere. This research evaluates whether maize-soybean intercrop agroecosystems sequester more C and N and emit fewer GHG than maize and soybean sole crop agroecosystems. An experiment was conducted at Balcarce, Argentina using four treatments: a maize sole crop, a soybean sole crop, and two intercrops with either 1:2 or 2:3 rows of maize to soybean. The objectives were to quantify soil organic carbon (SOC) and soil total nitrogen (TN) at 0-10, 10-20, 20-40, 40-80 and 80-120 cm depths, rates of decomposition of maize and soybean crop residue after 312 days, crop residue C- and N-input at harvest, and emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Significant decreases in SOC were observed with depth in all treatments after 40 cm, and significant decreases in TN were observed with depth in all treatments after 20 cm. Crop residue from maize had the greatest input of C and N to the soil, but the slowest rate of decomposition. Soybean biomass had the least input of C and N to the soil and the fastest rate of decomposition. The 1:2 and 2:3 intercrop agroecosystems had moderate crop residue inputs of C and N and intermediate rates of decomposition. No significant differences in GHG emissions were detected between treatments throughout the growing season. The major influences on GHG emissions were weather events, soil temperature and moisture, and crop residue input. Annual GHG emissions were determined; the CH4 sink in the 1:2 intercrop and the soybean sole crop was significantly greater (P < 0.05) than the 2:3 intercrop and the maize sole crop. Emissions of CO2 were inversely proportionate to N2O, with the greatest C sink in the 1:2 intercrop.

Riparian zones (RZ) are known to act as buffers, reducing the transfer of potentially harmful nutrients from agricultural fields to surface water bodies. However, many of the same processes in the subsurface that help to reduce this nutrient loading, may also be leading to greenhouse gas (GHG) production and emissions from these areas. Agricultural riparian zones in Southern Ontario are often characterized by a sloped topography, with the highest topographic position being closest to the field edge, decreasing towards an adjacent stream or other surface water body. This topographic variability, combined with lateral chemical inputs from both upland areas and the stream, is expected to cause variable hydrochemical environments throughout the RZ, which may therefore lead to variable N2O dynamics between upland, mid-riparian and lowland areas. The objectives of this study were to examine these spatial trends in N2O production and resulting emissions, as related to the hydrochemical environment in these three distinct zones. Objectives were achieved by instrumenting 6 sites across two transects running perpendicular from the agricultural field edge, towards the stream edge, analyzing for subsurface N2O, moisture and temperature, groundwater NO3, NH4, dissolved organic carbon (DOC), dissolved oxygen, and surface fluxes of N2O. Subsurface N2O concentrations and ground water nutrient concentrations displayed distinct spatial and temporal/seasonal trends in the three positions across the RZ, however N2O fluxes across the soil-atmosphere interface did not display strong or consistent spatial trends. There was a disconnect between the subsurface variables and the fluxes at the surface, in that N2O emissions did not reflect the N2O concentrations produced in the shallow soil profile (150 cm deep), nor were they significantly related to the geochemical environment at each position. The lack of visible spatial trends in N2O fluxes may have been due to an “oxic blanket” effect which may divide the surface from the subsurface soil profile. As N2O fluxes in this study (-0.28 to 1.3 nmol m-2 s-1) were within the range observed at other, similar study sites, the oxic blanket doesn’t appear to impede concentrations of N2O reaching the soil-atmosphere interface. This may suggest that the N2O released as a flux was being produced in the very shallow soil profile (0 – 5 cm), above the soil gas profile arrays installed at this site. Subsurface concentrations of N2O were fairly high at certain depths and times, which was not reflected in the fluxes. This may have resulted from nitrifier denitrification reducing N2O to N2 before it reached the surface, in aerobic zones above the water table. Another potential reason for the lack of connection between subsurface processes and surface emissions was the high heterogeneity observed across the RZ, which may have overshadowed potential differences between positions. Physical soil properties like porosity and bulk density across the RZ also potentially impacted the N2O movement through the soil profile, resulting in similar fluxes among positions, and over time. The missing connection between subsurface N2O concentrations, ground water nutrients, and the surface fluxes was not a hypothesized result, and requires further research and analysis for a better understanding of the production and consequent movement of N2O.

Reservoirs impound and store large volumes of water and flood land. The water is used for electricity generation, irrigation, industrial and municipal consumption, flood control and to improve navigation. The decomposition of flooded soil and vegetation creates greenhouse gases and thus reservoirs are a source of greenhouse gases. Reservoirs are not well studied for greenhouse gas flux from the water to the atmosphere. The FLooded Upland Dynamics EXperiment (FLUDEX) involves the creation of three experimental reservoirs in the upland boreal forest to study greenhouse gas and mercury dynamics. The balance of biological processes, decomposition, primary production, CH₄ oxidation and the nitrogen cycle in the reservoirs controls the greenhouse gas flux from the reservoir to the atmosphere. Understanding the importance and controlling factors of these processes is vital to understanding the sources and sinks of greenhouse gases within reservoirs. The carbon and oxygen dynamics near the sediment-water interface are very important to the entire reservoir because many processes occur in this area. Light and dark benthic chambers were deployed, side-by-side, to determine the benthic flux of DIC and CH₄ across the sediment-water interface and to determine the role of benthic photoautotrophs in benthic DIC, CH₄ and O₂ cycling. Benthic chambers have shown photoautotrophs use the decomposing soil, rocks and exposed bedrock as a physical substrate to colonize and the CO₂ produced by the decomposing soil as a carbon source since the delta¹³C-DIC value of the DIC added to light chambers is enriched relative to dark chambers and net photosynthesis rates are linked to community respiration. Benthic photoautotrophs consume 15-33% of the potential DIC flux into the water column. CH₄ produced by the decomposition of soils is partially oxidized by methanotrophs that use the photosynthetically produced oxygen. The delta¹³C-CH₄ values of the CH₄ added to light chambers is enriched relative to dark chambers and 15-88% of the potential CH₄ flux into the water column is oxidized. An isotope-mass budget for DIC and CH₄ is presented for each reservoir to identify the importance of processes on areservoir scale. Input of DIC to the reservoirs from overland flow can be important because concentration is greater and delta¹³C-DIC values are depleted relative to inflow from Roddy Lake. Estimates of total reservoir primary production indicate that 3-19% of the total DIC production from decomposition is removed by photoautotrophs. The carbon cycling in biofilm and the importance of periphytic primary production needs to be better understood. Dissolved delta¹³C-CH₄ values of CH₄ in reservoir outflow enriched 45-60permil, indicating that CH₄ oxidation was an important CH₄ sink within the reservoirs. Stable carbon isotope data indicates that the CH₄ in the bubbles is partially oxidized so the site of bubble formation is the upper portion of the flooded soil. The fraction of CH₄ converted to CO₂ in the FLUDEX reservoirs is similar to that of the wetland flooded for the Experimental Lakes Area Reservoir Project (ELARP). Approximately half of the dissolved CH₄ in the FLUDEX reservoirs was removedby CH₄ oxidation. The ebullitive flux of CH₄ from FLUDEX reservoirs is reduced 25-75% by CH₄ oxidation. The CH₄ flux to the atmosphere from peat surface of the ELARP reservoir became less oxidized after flooding: 91% to 85% oxidized. The floating peat islands of the ELARP reservoir were less oxidized than the peat surface. Similar to the CH₄ in the FLUDEX reservoirs, CH₄ in the ELARP peat islands was oxidized 56%. CH₄ oxidation is an important process because it reduces the global warming potential of the greenhouse gas flux since CO₂ is less radiatively active than CH₄.

Through appropriate soil and crop residue management, soil can function as a sink for carbon (C) and nitrogen (N) for the mitigation of greenhouse gases (GHG). No research has yet investigated the potential of intercrop agroecosystems to reduce emissions of GHG to the atmosphere. This research evaluates whether maize-soybean intercrop agroecosystems sequester more C and N and emit fewer GHG than maize and soybean sole crop agroecosystems. An experiment was conducted at Balcarce, Argentina using four treatments: a maize sole crop, a soybean sole crop, and two intercrops with either 1:2 or 2:3 rows of maize to soybean. The objectives were to quantify soil organic carbon (SOC) and soil total nitrogen (TN) at 0-10, 10-20, 20-40, 40-80 and 80-120 cm depths, rates of decomposition of maize and soybean crop residue after 312 days, crop residue C- and N-input at harvest, and emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Significant decreases in SOC were observed with depth in all treatments after 40 cm, and significant decreases in TN were observed with depth in all treatments after 20 cm. Crop residue from maize had the greatest input of C and N to the soil, but the slowest rate of decomposition. Soybean biomass had the least input of C and N to the soil and the fastest rate of decomposition. The 1:2 and 2:3 intercrop agroecosystems had moderate crop residue inputs of C and N and intermediate rates of decomposition. No significant differences in GHG emissions were detected between treatments throughout the growing season. The major influences on GHG emissions were weather events, soil temperature and moisture, and crop residue input. Annual GHG emissions were determined; the CH4 sink in the 1:2 intercrop and the soybean sole crop was significantly greater (P < 0.05) than the 2:3 intercrop and the maize sole crop. Emissions of CO2 were inversely proportionate to N2O, with the greatest C sink in the 1:2 intercrop.

Riparian zones (RZ) are known to act as buffers, reducing the transfer of potentially harmful nutrients from agricultural fields to surface water bodies. However, many of the same processes in the subsurface that help to reduce this nutrient loading, may also be leading to greenhouse gas (GHG) production and emissions from these areas. Agricultural riparian zones in Southern Ontario are often characterized by a sloped topography, with the highest topographic position being closest to the field edge, decreasing towards an adjacent stream or other surface water body. This topographic variability, combined with lateral chemical inputs from both upland areas and the stream, is expected to cause variable hydrochemical environments throughout the RZ, which may therefore lead to variable N2O dynamics between upland, mid-riparian and lowland areas. The objectives of this study were to examine these spatial trends in N2O production and resulting emissions, as related to the hydrochemical environment in these three distinct zones. Objectives were achieved by instrumenting 6 sites across two transects running perpendicular from the agricultural field edge, towards the stream edge, analyzing for subsurface N2O, moisture and temperature, groundwater NO3, NH4, dissolved organic carbon (DOC), dissolved oxygen, and surface fluxes of N2O. Subsurface N2O concentrations and ground water nutrient concentrations displayed distinct spatial and temporal/seasonal trends in the three positions across the RZ, however N2O fluxes across the soil-atmosphere interface did not display strong or consistent spatial trends. There was a disconnect between the subsurface variables and the fluxes at the surface, in that N2O emissions did not reflect the N2O concentrations produced in the shallow soil profile (150 cm deep), nor were they significantly related to the geochemical environment at each position. The lack of visible spatial trends in N2O fluxes may have been due to an “oxic blanket” effect which may divide the surface from the subsurface soil profile. As N2O fluxes in this study (-0.28 to 1.3 nmol m-2 s-1) were within the range observed at other, similar study sites, the oxic blanket doesn’t appear to impede concentrations of N2O reaching the soil-atmosphere interface. This may suggest that the N2O released as a flux was being produced in the very shallow soil profile (0 – 5 cm), above the soil gas profile arrays installed at this site. Subsurface concentrations of N2O were fairly high at certain depths and times, which was not reflected in the fluxes. This may have resulted from nitrifier denitrification reducing N2O to N2 before it reached the surface, in aerobic zones above the water table. Another potential reason for the lack of connection between subsurface processes and surface emissions was the high heterogeneity observed across the RZ, which may have overshadowed potential differences between positions. Physical soil properties like porosity and bulk density across the RZ also potentially impacted the N2O movement through the soil profile, resulting in similar fluxes among positions, and over time. The missing connection between subsurface N2O concentrations, ground water nutrients, and the surface fluxes was not a hypothesized result, and requires further research and analysis for a better understanding of the production and consequent movement of N2O.

The issue of odour, greenhouse gas emissions and indoor air quality in swine buildings have become a great concern for the neighbouring communities as well as governments. Air dispersion models have been adopted widely as an approach to address these problems which determine science-based distance between livestock production site and neighbours. However, no existing model considers the diurnal and seasonal variations of odour, gas (ammonia, hydrogen sulphide, greenhouse gas), and dust concentrations and emissions, which may cause great uncertainty. The primary objective of this project is to monitor and model the diurnal and seasonal variations of odour, gases, and dust concentrations and emissions from nursery, farrowing, and gestation rooms. Additionally, this study tried to quantify the greenhouse gas contribution from swine buildings and evaluate the indoor air quality of swine barns. <p>Strip-block experimental design was used to measure the diurnal variation of odour and gas concentrations and emissions in PSC Elstow Research Farm. It was found that: 1) odour and gas concentrations in winter were significantly higher than those in mild and warm weather conditions for all three rooms (P<0.05); 2) the nursery room had higher level of odour and gas concentration and emission than the other two types of rooms, no significant difference existed between the farrowing and gestation rooms (P>0.05); 3) significant diurnal variations occurred in August and April (P<0.05) for odour and some gas concentrations and emissions, while no significant diurnally variations were found in February (P>0.05); 4) apparent diurnal variation patterns were observed in August and April for NH3, H2S and CO2 concentrations, being high in the early morning and low in the late afternoon; 5) positive correlation was found between odour concentrations and NH3, H2S, and CO2 concentrations, respectively. <p>A whole year ( August 2006 to July 2007) monitoring of odour, gas and dust concentrations and emissions revealed that: 1) significant seasonal effect on odour and gas concentrations and emissions, total dust concentrations and dust depositions were observed (P<0.05), but no specific variation pattern was discovered for odour and gas emissions; 2) the total greenhouse gas emission from all the rooms in the gestation, nursery and farrowing area was 2956 CO2 equivalent tons per year, where gestation area, nursery area, and farrowing area accounted for 39.3 %, 37.2% and 23.5%, respectively; the CO2 emission contributed 53.4% to the total greenhouse emission, and CH4 contributed to 43.9%, 2.7% for N2O; N2O could be considered negligible; 3) indoor air quality of the swine barn met the requirements set by the Occupational Health and Safety Regulations (1996) of Saskatchewan for NH3, H2S, and CO2. <p>Statistical models were developed for each type of room to predict the odour and gas concentrations and emissions based on four variables: ventilation rate, room temperature, ambient temperature, and animal unit. The predicted results showed agreeable with measured values for most models (R2 = 0.56-0.96). Generally, gas prediction models performed better (R2=0.61-0.96) than odour prediction models (R2=0.56-0.85).<p>This study was conducted in the province of Saskatchewan throughout one year and the results could be used as representative data for Canada Prairies. Due to the large diurnal and seasonal variabilities of odour emissions, it was recommended to take multiple measurements of odour emission rate under different weather conditions in order to improve the accuracy of air dispersion modeling.

The Gulf of Mexico hypoxic zone is created by strong persistent water stratification and nutrient loading from the Mississippi River which fuels primary production and bacterial decomposition. The Texas-Louisiana shelf becomes seasonally oxygen depleted and hypoxia (O2 less than or equal to 1.4 ml l-1) occurs. Low oxygen environments are conducive for the microbial production of nitrous oxide (N2O), a powerful greenhouse gas found in the atmosphere in trace amounts (319 ppbv). Highly productive coastal areas contribute 61% of the total oceanic N2O production and currently global sources exceed sinks. This study is the first characterization of N2O produced in the Gulf of Mexico hypoxic zone. Because of enhanced microbial activity and oxygen deficiency, it is hypothesized that the Gulf of Mexico hypoxic zone is a source of N2O to the atmosphere. Seasonal measurements of N2O were made during three research cruises in the Northern Gulf of Mexico (Sept. 2007, April 2008, and July 2008). Water column N2O profiles were constructed from stations sampled over time, and bottom and surface samples were collected from several sites in the hypoxic zone. These measurements were used to calculate atmospheric flux of N2O. The Gulf of Mexico hypoxic zone was a source of N2O to the atmosphere, and N2O production was highest during times of seasonal hypoxia. N2O was positively correlated with temperature and salinity, and negatively correlated with oxygen concentration. Atmospheric fluxes ranged from -11.27 to 153.22 umol m-2 d-1. High accumulations of N2O in the water column (up to 2878 % saturated) were associated with remineralization of organic matter at the base of the pycnocline and oxycline. Seasonal hypoxia created a source of N2O to the atmosphere (up to 2.66 x 10-3 Tg N2O for the month of September 2007), but there was a slight sink during April 2008 when hypoxia did not occur. Large fluxes of N2O during the 3 to 5 month hypoxic period may not be counterbalanced by a 7 to 9 month sink period indicating the Gulf of Mexico hypoxic zone may be a net source of N2O to the atmosphere.

With climate change arising as an important issue in the 21th century, many states have been working diligently to develop climate action plans with the hopes of reducing greenhouse gas emissions and stop climate change from occurring. According to scientists' theories, however, many places across the globe are already feeling the effects of a changing climate and must therefore switch their focus from mitigation to adaptation. In the United States, there has been a focus on how climate change will impact one of the most vulnerable parts of the country, the transportation infrastructure. Many countries have already begun adapting their transportation infrastructure to climate change including the United States. This thesis focuses on how states are adapting to climate change by analyzing strategies, frameworks, and reports released by these states in order to document where they stand in regards to adaptation of the transportation network. The states that are adapting their transportation infrastructure are Washington, Oregon, California, Hawaii, Alaska, Florida, North Carolina, Maryland, Delaware, Pennsylvania, Michigan, Connecticut, Massachusetts, Vermont, and Maine. There is also a brief summary of how Canada and the United Kingdom are preparing for climate change with an analysis of frameworks and strategies used to adapt their transportation infrastructure. The ultimate goal of this thesis is to provide engineers and policymakers with evidence that several states are implementing adaptation into transportation projects and provide a variety of strategies for them to use in their own state. Specifically, this report provides applications of adaptation for Georgia to use, so that they can begin the lengthy process of adapting their transportation infrastructure to climate change.