Methane fluxes were calculated from measurements carried out at a temperate upland forest in Central Ontario using the eddy covariance method over five months in the summer and fall seasons of 2011. Measurements were made by an off-axis integrated cavity output spectrometer Fast Greenhouse Gas Analyzer (FGGA) which simultaneously measured methane (CH4), carbon dioxide (CO2), and water at 10 Hz sampling rates. Observed methane fluxes showed net uptake of methane over the measurement period with an average uptake flux value (±standard deviation of the mean) of -2.7±0.13 nmol m-2 s-1. Methane fluxes showed a diurnal pattern of increased uptake during the day and increasing uptake with seasonal progression. There was also a significant correlation in methane fluxes with soil water content and wind speed. Comparison of the FGGA measurements to those using a static chamber method and canister sampling showed close agreement in flux and mixing ratio values respectively.

Methane fluxes were calculated from measurements carried out at a temperate upland forest in Central Ontario using the eddy covariance method over five months in the summer and fall seasons of 2011. Measurements were made by an off-axis integrated cavity output spectrometer Fast Greenhouse Gas Analyzer (FGGA) which simultaneously measured methane (CH4), carbon dioxide (CO2), and water at 10 Hz sampling rates. Observed methane fluxes showed net uptake of methane over the measurement period with an average uptake flux value (±standard deviation of the mean) of -2.7±0.13 nmol m-2 s-1. Methane fluxes showed a diurnal pattern of increased uptake during the day and increasing uptake with seasonal progression. There was also a significant correlation in methane fluxes with soil water content and wind speed. Comparison of the FGGA measurements to those using a static chamber method and canister sampling showed close agreement in flux and mixing ratio values respectively.

No description available.

Carbon plays a major role in physical and biogeochemical processes in the atmosphere, the biosphere, and the ocean. CO2 and CH4 are two of the most common carbon-containing compounds in the atmosphere, also recognized as major greenhouse gases. The exchange of CO2 and CH4 between the ocean and the atmosphere is an essential part of the global carbon cycle. The exchange is controlled by the air–sea concentration gradient and by the efficiency of the transfer processes. The lack of knowledge about the forcing mechanisms affecting the exchange of these climate-relevant gases is a major source of uncertainty in the estimation of the global oceanic contributions. Quantifying and understanding the air–sea exchange processes is essential to constrain the estimates and to improve our knowledge about the current and future climate. In this thesis, the mechanisms controlling the air–sea gas exchange in the Baltic Sea are investigated. The viability of micrometeorological techniques for CH4 monitoring in a coastal environment is evaluated. One year of semi-continuous measurements of air–sea CH4 fluxes using eddy covariance measurements suggests that the method is useful for CH4 flux estimations in marine environments. The measurements allow long-term monitoring at high frequency rates, thus, capturing the temporal variability of the flux. The region off Gotland is a net source of CH4, with both the air–sea concentration gradient and the wind as controlling mechanisms. A sensitivity analysis of the gas transfer velocity is performed to evaluate the effect of the forcing mechanisms controlling the air–sea CO2 exchange in the Baltic Sea. This analysis shows that the spatio-temporal variability of CO2 fluxes is strongly modulated by water-side convection, precipitation, and surfactants. The effect of these factors is relevant both at regional and global scales, as they are not included in the current budget estimates.

<p>Methane is an important green house gas as it is responsible for 15-20 % of the green house effect. Marine environments in general and shallow near-coastal waters specifically may be important contributors of methane emissions but are as of today poorly studied.  In this study we measured total fluxes of methane from shallow near-coastal waters at two sites along the east coast of Sweden. The sea-to-air emissions of methane where captured using floating chambers. This gave measured fluxes as compared to earlier studies of the Baltic Sea where calculated fluxes are often used. Measured fluxes have the merit of not having to rely on several highly varying and complex variables e.g. mean wind speed and piston velocity that vary and give an uncertainty to the results.  The fluxes ranged from -2.14 to 0.37 mg CH4 m-2 d-1 with a mean of 0.05 mg CH4 m-2 d-1. The results show a correlation, however not strong, between depth and methane. No difference in flux between the study sites could be seen. We look forward to further studies using floating chambers on shallow near-coastal waters with longer sampling periods to catch seasonal variations.</p>

Methane is an important green house gas as it is responsible for 15-20 % of the green house effect. Marine environments in general and shallow near-coastal waters specifically may be important contributors of methane emissions but are as of today poorly studied.  In this study we measured total fluxes of methane from shallow near-coastal waters at two sites along the east coast of Sweden. The sea-to-air emissions of methane where captured using floating chambers. This gave measured fluxes as compared to earlier studies of the Baltic Sea where calculated fluxes are often used. Measured fluxes have the merit of not having to rely on several highly varying and complex variables e.g. mean wind speed and piston velocity that vary and give an uncertainty to the results.  The fluxes ranged from -2.14 to 0.37 mg CH4 m-2 d-1 with a mean of 0.05 mg CH4 m-2 d-1. The results show a correlation, however not strong, between depth and methane. No difference in flux between the study sites could be seen. We look forward to further studies using floating chambers on shallow near-coastal waters with longer sampling periods to catch seasonal variations.

Os aterros de disposição de resíduos sólidos urbanos são equipamentos que, necessariamente, devem ser integrados ao sistema de saneamento e proteção à saúde pública das municipalidades. Independentemente se bem planejados, construídos e operados, os mesmos oferecem impactos ambientais aos locais onde estão implantados e ao seu entorno. Os referidos aterros são fontes de emissão antropogênica de gases indutores do efeito estufa global, como o metano (\'CH IND.4\') e o dióxido de carbono (\'CO IND.2\'). O presente trabalho teve por objetivo medir, estimativamente, in situ, a contribuição destes equipamentos no fluxo destes gases na natureza. Para isso, foram desenvolvidas duas campanhas em oito aterros de municípios do estado de São Paulo (Brasil) nos anos de 2006 e 2007. Foram medidas a concentrações de \'CH IND.4\' e \'CO IND.2\' no ar ambiente dos aterros, a emissão solo-ar e o fluxo a partir dos dissipadores verticais, quando presentes. As amostras coletadas do GAS foram analisadas por cromatografia gasosa. Os resultados evidenciaram que as concentrações de \'CH IND.4\' e \'CO IND.2\' na atmosfera dos aterros foram de 18.000 ppm e 5.500 ppm, respectivamente. Estes valores corresponderam a dez mil vezes e quinze vezes maiores que aquelas medidas em locais distantes dos aterros (background). Os resultados das medidas do fluxo solo-ar apontaram para uma grande variabilidade desta emissão, entre os sítios da coleta, entre os aterros e entre as campanhas. As taxas médias de emissão solo-ar variaram de 5,66 g/\'M POT.2\'.d a 148,20 g/\'M POT.2\'.d para \'CH IND.4\' e de 17,78 g/\'M POT.2\'.d a 223,04 g/\'M POT.2\'.d para \'CO IND.2\'. A emissão estimada solo-ar para os aterros variou de 276,82 a 75.730,20 toneladas por ano de \'CH IND.4\' e de 501,02 a 76.312,74 toneladas por ano para o \'CO IND.2\'. A emissão estimada para os aterros a partir dos dissipadores verticais variou de 73,52 a 307,31 toneladas para \'CH IND.4\' e de 165,83 a 692,32 toneladas por ano para o \'CO IND.2\'. Os resultados também evidenciaram que a concentração dos gases no ar ambiente dos aterros e a emissão solo-ar, especialmente, pareceram independer da operação dispensada: caso aterros sanitários, controlados ou lixões. Todos apresentaram muitas semelhanças no processo de emissão. Mesmo a presença do sistema de sucção do GAS para alimentar a usina termoelétrica (UTEB) no aterro Bandeirantes, São Paulo, Capital, não o diferenciou dos demais. De modo geral, não foi possível correlacionar variáveis que apontassem para tendências gerais na emissão destes sistemas de disposição de RSU. Com base nos resultados supracitados, este trabalho sugere futuras perspectivas de pesquisas. / Urban solid waste disposal landfills are equipments that must be integrated with the drainage and protection of the public health of municipalities system. Regardless of whether they are well planned, built and operated, they offer environmental impacts to the areas where they are deployed and their surroundings. The present work aimed at measuring, as estimates, in situ, the contribution of the aforementioned equipments in the flux of these gases in nature. The research was developed in 2006 and 2007 in two campaigns in eight municipal solid waste landfills in the state of São Paulo, Brazil. Concentrations of \'CH IND.4\' and \'CO IND.2\' were measured in the air from landfills; the ground-air emission and the flux from vertical drains, when present. The samples collected of the GAS were analyzed utilizing gas chromatography. The results showed that the concentrations of \'CH IND.4\' and \'CO IND.2\' in the atmosphere from landfills were 18,000 ppm and 5,500 ppm, respectively. These values correspond to ten thousand and fifteen times greater than those measured on places far away from landfills (background). The results of the ground-air flux indicated a great variability of this emission, not only among the collection sites, but also among the landfills and between the campaigns. The average ground-air emission ranged from 5.66 g/\'M POT.2\'.d to 148.20 g/\'M POT.2\'.d for \'CH IND.4\' and from 17.78 g/\'M POT.2\'.d to 223,04 g/\'M POT.2\'.d for \'CO IND.2\'. The estimated ground-air emission for the landfills ranged from 276.82 to 75,730.20 tons per year of \'CH IND.4\' and from 501.02 to 76,312.74 tons per year for \'CO IND.2\'. The estimated emission for the landfills from the vertical drains ranged from 73.52 to 307.31 tons per year for \'CH IND.4\' and from 165.83 to 692.32 tons per year for \'CO IND.2\'. The results also showed that concentration of gases in the environment air of landfills and the emission, especially ground-air, seems to be independent of the operation given: whether it is sanitary landfill, controlled landfill, or dump. They all presented many similarities in the emission process, and major differences among them were not elucidated. Even the presence of the suction system of the GAS to feed the thermoelectric plant (UTEB) at the Bandeirantes landfill, located at the capital of São Paulo, did not differentiate it from the other landfills from the \'CH IND.4\' and \'CO IND.2\' emission perspective. In a nutshell, it was not possible to correlate variables that pointed to general trends in the emissions of these USW disposal equipments. Based on these results, future prospects for research are suggested.

Os aterros de disposição de resíduos sólidos urbanos são equipamentos que, necessariamente, devem ser integrados ao sistema de saneamento e proteção à saúde pública das municipalidades. Independentemente se bem planejados, construídos e operados, os mesmos oferecem impactos ambientais aos locais onde estão implantados e ao seu entorno. Os referidos aterros são fontes de emissão antropogênica de gases indutores do efeito estufa global, como o metano (\'CH IND.4\') e o dióxido de carbono (\'CO IND.2\'). O presente trabalho teve por objetivo medir, estimativamente, in situ, a contribuição destes equipamentos no fluxo destes gases na natureza. Para isso, foram desenvolvidas duas campanhas em oito aterros de municípios do estado de São Paulo (Brasil) nos anos de 2006 e 2007. Foram medidas a concentrações de \'CH IND.4\' e \'CO IND.2\' no ar ambiente dos aterros, a emissão solo-ar e o fluxo a partir dos dissipadores verticais, quando presentes. As amostras coletadas do GAS foram analisadas por cromatografia gasosa. Os resultados evidenciaram que as concentrações de \'CH IND.4\' e \'CO IND.2\' na atmosfera dos aterros foram de 18.000 ppm e 5.500 ppm, respectivamente. Estes valores corresponderam a dez mil vezes e quinze vezes maiores que aquelas medidas em locais distantes dos aterros (background). Os resultados das medidas do fluxo solo-ar apontaram para uma grande variabilidade desta emissão, entre os sítios da coleta, entre os aterros e entre as campanhas. As taxas médias de emissão solo-ar variaram de 5,66 g/\'M POT.2\'.d a 148,20 g/\'M POT.2\'.d para \'CH IND.4\' e de 17,78 g/\'M POT.2\'.d a 223,04 g/\'M POT.2\'.d para \'CO IND.2\'. A emissão estimada solo-ar para os aterros variou de 276,82 a 75.730,20 toneladas por ano de \'CH IND.4\' e de 501,02 a 76.312,74 toneladas por ano para o \'CO IND.2\'. A emissão estimada para os aterros a partir dos dissipadores verticais variou de 73,52 a 307,31 toneladas para \'CH IND.4\' e de 165,83 a 692,32 toneladas por ano para o \'CO IND.2\'. Os resultados também evidenciaram que a concentração dos gases no ar ambiente dos aterros e a emissão solo-ar, especialmente, pareceram independer da operação dispensada: caso aterros sanitários, controlados ou lixões. Todos apresentaram muitas semelhanças no processo de emissão. Mesmo a presença do sistema de sucção do GAS para alimentar a usina termoelétrica (UTEB) no aterro Bandeirantes, São Paulo, Capital, não o diferenciou dos demais. De modo geral, não foi possível correlacionar variáveis que apontassem para tendências gerais na emissão destes sistemas de disposição de RSU. Com base nos resultados supracitados, este trabalho sugere futuras perspectivas de pesquisas. / Urban solid waste disposal landfills are equipments that must be integrated with the drainage and protection of the public health of municipalities system. Regardless of whether they are well planned, built and operated, they offer environmental impacts to the areas where they are deployed and their surroundings. The present work aimed at measuring, as estimates, in situ, the contribution of the aforementioned equipments in the flux of these gases in nature. The research was developed in 2006 and 2007 in two campaigns in eight municipal solid waste landfills in the state of São Paulo, Brazil. Concentrations of \'CH IND.4\' and \'CO IND.2\' were measured in the air from landfills; the ground-air emission and the flux from vertical drains, when present. The samples collected of the GAS were analyzed utilizing gas chromatography. The results showed that the concentrations of \'CH IND.4\' and \'CO IND.2\' in the atmosphere from landfills were 18,000 ppm and 5,500 ppm, respectively. These values correspond to ten thousand and fifteen times greater than those measured on places far away from landfills (background). The results of the ground-air flux indicated a great variability of this emission, not only among the collection sites, but also among the landfills and between the campaigns. The average ground-air emission ranged from 5.66 g/\'M POT.2\'.d to 148.20 g/\'M POT.2\'.d for \'CH IND.4\' and from 17.78 g/\'M POT.2\'.d to 223,04 g/\'M POT.2\'.d for \'CO IND.2\'. The estimated ground-air emission for the landfills ranged from 276.82 to 75,730.20 tons per year of \'CH IND.4\' and from 501.02 to 76,312.74 tons per year for \'CO IND.2\'. The estimated emission for the landfills from the vertical drains ranged from 73.52 to 307.31 tons per year for \'CH IND.4\' and from 165.83 to 692.32 tons per year for \'CO IND.2\'. The results also showed that concentration of gases in the environment air of landfills and the emission, especially ground-air, seems to be independent of the operation given: whether it is sanitary landfill, controlled landfill, or dump. They all presented many similarities in the emission process, and major differences among them were not elucidated. Even the presence of the suction system of the GAS to feed the thermoelectric plant (UTEB) at the Bandeirantes landfill, located at the capital of São Paulo, did not differentiate it from the other landfills from the \'CH IND.4\' and \'CO IND.2\' emission perspective. In a nutshell, it was not possible to correlate variables that pointed to general trends in the emissions of these USW disposal equipments. Based on these results, future prospects for research are suggested.

科学研究費補助金 研究種目:基盤研究(B)(2) 課題番号:08458144 研究代表者:飯田 孝夫 研究期間:1996-1997年度