Dissertations / Theses on the topic 'Greenhouse gas measurement'

Doctor of Philosophy
Department of Biological and Agricultural Engineering
Ronaldo Maghirang
Emission of greenhouse gases (GHGs), including nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2), from open beef cattle feedlots is becoming an environmental concern; however, scientific information on emissions and abatement measures for feedlots is limited. This research was conducted to quantify GHG emissions from feedlots and evaluate abatement measures for mitigating emissions. Specific objectives were to: (1) measure N2O emissions from the pens in a commercial cattle feedlot; (2) evaluate the effectiveness of surface amendments in mitigating GHG emissions from feedlot manure; (3) evaluate the effects of water application on GHG emissions from feedlot manure; and (4) compare the photo-acoustic infrared multi-gas analyzer (PIMA) and gas chromatograph (GC) in measuring concentrations of N2O and CO2 emitted from feedlot manure. Field measurements on a commercial beef cattle feedlot using static flux chambers combined with GC indicated that N2O emission fluxes varied significantly with pen surface condition. The moist/muddy surface had the largest median emission flux; the dry and compacted, dry and loose, and flooded surfaces had significantly lower median emission fluxes. Pen surface amendments (i.e., organic residues, biochar, and activated carbon) were applied on feedlot manure samples in glass containers and evaluated for their effectiveness in mitigating GHG emissions. Emission fluxes were measured with the PIMA. For dry manure, all amendments showed significant reduction in N2O and CO2 emission fluxes compared with the control (i.e., no amendment). For moist manure, biochar significantly reduced GHG emissions at days 10 and 15 after application; the other amendments had limited effects on GHG emissions. The effect of water application on GHG emissions from feedlot manure was evaluated. Manure samples (with and without water application) were placed in glass containers and analyzed for GHG emission using a PIMA. For the dry manure, GHG emissions were negligible. Application of water on the manure samples resulted in short-term peaks of GHG emissions a few minutes after water application. Comparison of the GC and PIMA showed that they were significantly correlated but differed in measured concentrations of N2O and CO2. The PIMA showed generally lower N2O concentrations and higher CO2 concentrations than the GC.

Tableau d'honneur de la Faculté des études supérieures et postdorales, 2015-2016
Le réchauffement de l’Arctique a le potentiel d’affecter le climat global par le dégel du pergélisol engendrant des émissions accrues de gaz à effet de serre (GES). Ces émissions sont cependant difficiles à quantifier puisque les méthodes conventionnellement utilisées sont généralement onéreuses et souvent très laborieuses. À l’aide d’un nouveau système automatisé de chambres fermées développé pour cette étude, ce projet visait à mesurer les émissions de GES provenant du pergélisol dans une tourbière située à Salluit, au Nunavik. Les émissions ont été quantifiées sous différentes conditions environnementales afin de simuler le réchauffement climatique et déterminer les effets des variations spatiales sur les émissions de GES. Les résultats démontrent que le nouveau système produit des résultats comparables à ceux obtenus avec un système commercial existant. La température était le principal facteur affectant la variabilité de la ER et les plus grandes émissions de GES provenaient du site saturé en eau. Mots-clés: Pergélisol, Arctique, Changements climatiques, Toundra, Tourbière polygonale, Respiration de l’écosystème, Chambre fermée, Gaz à effet de serre, Décomposition, Réchauffement expérimental.
Warming in the Arctic has the potential to affect the global climate through permafrost thaw leading to increased greenhouse gas (GHG) emissions. However, these emissions are difficult to quantify because the methods conventionally used are often prohibitively expensive and time-consuming. With a new automated system of closed chambers developed for this study, this project aimed to measure permafrost GHG emissions in a polygonal peatland located near Salluit, Nunavik. The emissions were quantified under different environmental conditions in order to simulate climate warming and to determine the effect of spatial variability on GHG emissions. Results show that the new system yields results comparable to those obtained with an existing commercial system. Temperature was the principal factor influencing ecosystem respiration variability and the largest GHG emissions were measured on the water-saturated plot. Keywords: Permafrost, Arctic, Climate change, Tundra, Polygonal peatland, Ecosystem respiration, Closed chamber, Greenhouse gas, Decomposition, Experimental warming.

While most micrometeorological measurement techniques are only suitable for windy conditions, the Nocturnal Boundary Layer Technique can be used to measure trace gas flux during calm, clear nights as the nighttime stability enables gas emitted at the ground to accumulate. The difference between two measurements over the whole depth of this layer is believed to integrate emissions from a large area representative of, in this study, an agricultural farm. A tethersonde and infrared gas analyzer attached to a blimp carrying a bag sampling system monitored atmospheric variables for each ascent during two summer field campaigns. A mini-SODAR was installed in the field to obtain the wind flowfield. Strong accumulation was observed under low level jets suggesting that this feature acts as a good lid for trace gases. An average background vertical motion different from zero seemed to have more influence on gas propagation than did intermittent turbulence. On at least one night, a density current created by the nearby St-Lawrence River was observed to influence measurements.

The objective of this study was to develop a gas measurement chamber for the comparison of emissions from different dairy manure storage facilities. Compost bedded pack (CBP) barns are a loose housing system in which cows rest on an intensely managed compost pack. Sawdust is the primary material added to the system, along with manure and urine inputs from the cows, and the pack is stirred one to two times daily. Maintaining a high level of aerobic microbial activity in the pack is critical for cow health. Previous dairy emissions work has not included compost bedded pack barns; it was expected that the largely aerobic system would have a different emissions profile than other manure storage systems. A measurement chamber was developed to determine emission fluxes from the compost bedded pack barn surface. Infrared and electrochemical sensors measuring ammonia, methane, and carbon dioxide obtain headspace gas concentrations, temperature, and humidity each second. The relatively lower cost of each chamber, as compared to photoacoustic and gas chromatography systems, will allow a greater number to be deployed to more accurately represent the spatial variation within the system.

Albany thicket is prevalent in the Eastern Cape Province of South Africa. Its spread has diminished through overgrazing and heavy browsing by animals, land clearance and urban expansion. The result is highly degraded land characterized by invasion of alien species. There is a wealth of documented evidence on the high carbon sequestration ability of thicket biome, but not much has been done to assess its effect on carbon dioxide emissions from the soil. Given that the concentration of atmospheric greenhouse gases has been constantly rising since the industrial era, it is imperative to assess the influence of thicket biome as a source or sink of these gases. There is evidence of shifts in the climate in southern Africa as reflected by changes in rainfall patterns, increased temperatures, recurrent droughts and fires. As such, the historical rainfall variability in an Albany thicket region and its interaction with the temporal land use / cover changes was studied. This served to give some background information about the study area for more detailed study on C and carbon dioxide effluxes in thicket vegetation under different levels of degradation. This study thus aimed to determine the influence of thicket vegetation at various levels of degradation on soil carbon and carbon dioxide fluxes. The impact of plant photosynthetic pathway on soil C residence time and gas effluxes were analysed to elucidate on the land-use and cover patterns occurring in the area. All this was done to shed some light on the role of soil and thicket vegetation on carbon dioxide emissions and C storage in the spectrum of a shifting climate. The main area of research was Amakhala reserve in an Albany thicket in Eastern Cape Province; and it concentrated on three land cover types namely intact thicket, degraded thicket and grassland. The objectives mentioned above were achieved by assessing historical rainfall variability from 1970 to 2010 through trend and time series analysis at nine rainfall stations located at Amakhala reserve, Grahamstown, Bathurst, Port Alfred, Uitenhage and Port Elizabeth. The land use changes that have occurred in the Albany thicket region covering Amakhala reserve, Grahamstown, Bathurst and Port Alfred were also assessed for 1989, 1999 and 2009 through satellite image analysis with Idrisi Andes GIS software; then their interaction with rainfall variability were determined. To elucidate on the vegetation species composition and land use / cover changes that have occurred in the study area, plant biomass as well carbon (C) and nitrogen (N) isotope measurements were done. Plant biomass was assessed for the dominant species through use of pre-existing allometric equations that required data on plant basal diameter, canopy area, stem numbers and height. The plant carbon was then estimated through use of a conversion factor of 0.48 on above-ground biomass, while soil organic C was determined through the modified Walkely - Black method. Carbon and N isotope ratios were determined from the foliar material of three replicate samples of dominant plant species then analyzed through mass spectrometry. Soil carbon dioxide effluxes were then monitored in each of the intact thicket (IT), degraded thicket (DT) and grassland (G) over a 10 month period; by measuring the net carbon dioxide exchange rate (NCER) through the dynamic chamber method. An automated carbon dioxide exchange analyzer, coupled to a soil temperature probe and photosynthetic active radiation (PAR) sensor was used; with NCER measurements taken every 20-30 days. Soil temperature, moisture, penetration resistance and PAR readings were taken during each assay and later used to interpret the NCER. Results showed that long term variability in annual rainfall had a declining trend at Grahamstown (r = -0.59), Uitenhage and Bathurst stations (r = -0.32 at both stations), but was not significant at Amakhala, Port Alfred and Port Elizabeth stations. Most reductions in rainfall occurred in the 1980s and 1990s with the autumn, winter and summer rainfalls, the daily rainfall index and the daily rainfall subclasses of 10 mm and above showing a similar trend. The land use change detection gave a significant increase in proportion of degraded and transformed (moderately degraded) land between 1989 and 2009 with most of the increases occurring from 1989 to 1999, while farmland area decreased by 1.8 percent over the years. Thus the Albany region had over 30 percent of its land occupied by transformed vegetation, with heavy browsing and uncontrolled grazing being attributed to the destruction of pristine vegetation. Land-use change to game ranching and goat pastoralism was attributed to the reduction in farmland. Rainfall variability – land use change linkages were most significant in 1999 that recorded the least rainfall and had the lowest mean, maximum and sum of the NDVI. Grahamstown had the most significant rainfall-NDVI trends as it had the lowest NDVIs in 1999 when rainfall was lowest, the highest NDVI in 1989 when rainfall was highest and moderate NDVIs in 2009 when rainfall was moderate. Vegetation at the IT was characterized by a dense thicket with diverse growth forms of canopy trees, woody shrubs, succulent shrubs and ephemerals which mostly had the C3 type of pathway. This was in contrast with the IT soil isotopy that showed more positive C isotope ratios, indicating a switch between C3 and CAM photosynthesis in original vegetation. Most of the canopy trees had disappeared in the DT to be replaced by herbs, shrubs and grasses. As such, there was a huge difference in isotope ratios between DT plants and soils with the plants having mostly C3 metabolism while the soil showed a predominance of CAM plants in previous vegetation, indicating significant changes in land cover. The G site mostly comprised the grasses Themeda triandra and Panicum maximum and a few herbs. It maintained a dominance of C4 metabolism in both plants and soils showing very little change in species composition over the years. Because of the higher species diversity at IT, its soil organic C was quite high reaching levels of 3.4 percent (i.e. 3.4 t C / ha) in the top 10 cm then decreasing with depth (p < 0.001); but was moderate at DT (1.1-1.3 percent) and very low at G ( 0.5 percent C) (p < 0.001). In the same manner above-ground biomass was highest at IT i.e. 330 000 kg/ha; but was only 22 000 kg/ha in DT and as low as 6 700 kg/ha in G vegetation. High biomass at IT was mostly attributed to the succulent shrub Portulacaria afra and the canopy trees Euclea undulate, Rhus longispina and Schotia afra. This above-ground biomass translated to biomass C amounts of 158 000 kg/ha at IT, 10 600 kg/ha at DT and 3 200 kg/ha at G. Thus the IT had the highest while G the least and DT moderate plant and soil C sequestration ability. In all, the conversion of IT to DT led to a net loss of 147 000 Kg of biomass C / ha and 12 000kg less organic C / ha of land. Soil carbon dioxide effluxes were however variable between seasons as they were affected by differences in soil properties and seasonal weather patterns. High soil moisture levels (up to 16 percent gravimetric moisture) resulted in reduced soil penetration resistance (1 to 4 Kg/cm2) which raised effluxes at G and DT sites (up to 1.2 μmols m-2 sec-1) in winter, while low moisture (2 percent) resulted in hard dry soil (14 Kgm-2 penetration resistance) with suppressed CO2 effluxes in spring (0.2 μmols m-2 sec-1) especially in DT and G soils. Rising temperature generally caused accelerated gas emissions but only when moisture was not limiting (as was the case in IT). Thus the high summer temperatures (up to 40oC) gave lower effluxes especially in DT and G (< 1 μm-2sec-1) due to limited moisture supply (< 10 percent); while the Autumn period that had very high temperature (up to 48 oC) and good moisture (up to 16 percent) saw accelerated soil CO2 emissions (averaging 2 μmols m-2 sec-1) from all cover types. The high biomass and litter fall at IT served as ready substrate for soil respiration as long as moisture was not limiting and temperatures were favourable, while reduced cover at DT resulted in poor moisture conservation and creation of hard dry soils in spring and summer with reduced respiration. It was concluded that the DT had high CO2 effluxes in winter and reduced emissions in summer; while the opposite was true for the IT. All the cover types had minimal CO2 effluxes in spring and accelerated emissions in autumn. The grassland on the other hand was a fairly moderate source or sink of CO2 in most seasons compared with the other two covers. It was observed that an environment of good moisture and low-moderate temperatures (such as that in the winter) minimises effluxes while maintaining good plant productivity. It was concluded that thicket vegetation is a good sink of carbon that should be preserved in its natural condition to optimize its carbon sequestration potential. All three land covers served as sources or sinks of CO2 depending on soil and seasonal conditions. Thus high moisture and low penetration resistance generally increased effluxes of thicket ecosystems. The effect of increasing temperature on effluxes was only significant when moisture was not limiting. Conditions of good moisture and low-moderate temperatures gave reasonable amounts of effluxes while maintaining good plant productivity. Though the dry soil conditions significantly reduced effluxes in all land covers; they were not desirable since they decreased plant productivity and ultimately its C sequestration potential. Moreover, prolonged dry conditions only serve to exacerbate recovery of thicket plants as they increase mortality of canopy species in degraded and transformed areas in comparison with intact thicket.

Nitrous oxide (N2O) is a potent greenhouse gas (GHG) which is released naturally into the atmosphere as a by-product of the microbial processes of nitrification and denitrification. Agricultural activities are believed to account for up to 80% of anthropogenic N2O emissions at a global scale; however, these estimates are prone to large uncertainties due to the large temporal and spatial variability associated with flux measurements. This thesis contains five studies which aimed to improve the ability to measure and predict N2O emissions from agricultural activities. A closed loop dynamic chamber was developed using a quantum cascade laser (QCL). This method provided high precision chamber measurements of N2O flux from soils with a detection limit below 4 μg N2O-N m-2 h-1. Using the dynamic chamber method allowed for a detailed investigation of uncertainties in individual measurements including contributions from regression fitting, temperature and pressure. The lack of negative fluxes measured that were outwith the detection limits of the methodology (0.3% of all measurements) highlighted that the uptake of N2O reported in some previous literature is likely to have been the result of detection limits of measurement methods applied. Spatial variability of N2O flux was investigated at the plot, field and farm scale. Fluxes were measured from a grassland field plot before and after a tillage event. These measurements highlighted the large spatially variability present in N2O fluxes from agricultural soils. Fluxes varied by up to three orders of magnitude over distances less than 5 metres after the tillage event. A field scale experiment carried out on grazed grassland investigated relationships between soil properties and N2O flux. This study found that N2O emissions correlated strongly with available nitrogen content in the soil and that animal waste was likely responsible for the spatial variability of N2O flux observed at the field scale. A farm scale inventory of N2O emissions was carried out investigating several large point sources of N2O and emissions from the wider field coverage. The inventory estimates that nitrogen fertiliser application is the single largest N2O source from the livestock farm accounting for 49% of annual emissions.

The underlying objective of this thesis was to perform GHG simulation studies to predict the dispersion and transport of greenhouse gases emitted from a thermal power plant in order to assess the extent of dangerous living environment for those surrounding it in case of an unforeseen calamity. The research carried out during this thesis was to investigate the method of wind averaging techniques to analyse column measurements (XCO2). The reason for adopting this method of analysis was to correlate the physical aspect of wind data to average over a certain period of time wherein the amount of XCO2 (in ppm) observed displays values greater than the background concentration. CFD simulations were performed using the open source code, OpenFOAM, and steady RANS models modified with turbulence boundary conditions for the urban environment case with previously validated simulation studies carried out for the same region in Munich, Germany. Initial results performed during the testing stage indicated that maximum average XCO2 value (in ppm) was recorded at the lowest value of mean wind speed and at a more downwind location of the measurement site. The results obtained from simulation studies on comparison with experimental values (arithmetic average) also suggest that for the same time interval, the difference in values for similar wind conditions as mentioned before makes this technique a more favourable choice for comparison and verification at another time instant.  There have been recent developments in GHG simulation based studies and however the current method does represent certain drawbacks, an insight into performing averaging analysis at time intervals representing peak XCO2 moments could be demonstrated which can also help in reducing the overall number of simulations as well as provide information with respect to mitigation measures based on transport and diffusion behavior.

碩士
國立清華大學
經濟學系
93
For the purpose that energy use makes lots of pollution and does change the climate, promoting energy efficiency becomes a very important strategy to reduce the greenhouse gas. Energy productivity, the most often method we use to measure energy efficiency, will change depend on real GDP could not be an appropriate measurement. Otherwise, like stochastic frontier and DEA method, energy productivity could only measure the overall efficiency but could not measure the efficiency of individual energy use. In the thesis, we set up the energy efficiency indicator both on production and cost side, and called “loss of energy use by unit.” This indicator not only could measure the efficiency of individual energy use but also could apply in firm’s comparison. In addition, loss of energy use by unit could measure all kinds of study level no matter micro or macro level. Besides, we take emission standard and carbon tax into account and discussed how these policy effect energy efficiency. Furthermore, this thesis uses OLS, 2SLS, and stochastic production frontier function (STF) to do the empirical study. We found that energy productivity estimated by STF method was closer to actual situation of energy use. Keywords: energy efficiency, emission standard, carbon tax, stochastic production frontier function

碩士
國立臺北科技大學
能源與冷凍空調工程系
106
The assessment of a companys business performance is often the most important factor in business operations. It is hoped that the largest output will be achieved with minimal input, and the direction in which efforts to improve corporate performance should be understood.The units participating in the performance appraisal can make adjustments to the redistribution of resources to achieve the purpose of improving the competitiveness of enterprises. As global climate changes and energy supply and demand tighten, energy conservation and green energy are almost an important issue. If you consider greenhouse gas emissions when assessing performance, achieve an increase in the efficiency of business operations, and save energy and reduce carbon, and fulfill corporate social responsibility. In recent years, statistical software R has been the hot spot for reanalysing the application of various statistical problems. In this study, DEA (Data Envelopment Analysis) data envelopment analysis method was used as the method of efficiency evaluation. The greenhouse gas emissions were used as inputs, and the total working iv hours, area and average outside air temperature of the business units were output. Analyze the scale efficiency of a decision-making unit with pure technical efficiency, and find out the direction in which each unit needs improvement. This study found that in the analysis of the relative efficiency of 30 business units, 3 are relatively efficient, and 27 are relatively inefficient. In the inefficient business unit, the pure technology of 6 business units is measured by the BBC model. Efficiency = 1, two of the 27 business units that indicated overall inefficiency were caused by economies of scale.

The pressing global demand to transform to a low-carbon business community, which is required by the urgency of mitigating climate change, significantly alters the operating procedures for carbon emitters and carbon revenue generators alike. Although agricultural activities are not considered as heavy carbon emission source, the increased public focus on climate change has catapulted the exploitation of sustainable agricultural land management mitigating strategies as intervention by the sector. Additionally, the focus on market-based mechanism to address climate change, which has led to the evolution of cap-and-trade schemes, makes the agricultural sector become a source of low-cost carbon offsets. However, the fact that cap-and-trade schemes in the agricultural sector are voluntary has resulted into not only very diverse farming practices but also diverse accounting practices. The consequences of the diversity practices are that, the impacts on financial performance and position are not comparable. Therefore, the overall objective of this study was to investigate the recognition, measurement and disclosure for cap-and-trade schemes in the agricultural sectors This study was conducted through literature reviews and empirical test. A qualitative research approach utilising constructivist methodology was employed. Primary data was collected in Kenya by administering three sets of semi-structured questionnaires to drafters of financial statements, loan officers and financial consultants. Secondary data involved content analysis of financial statements and reports of listed entities across the globe. It was established that proper accounting for cap-and-trade schemes adaptation activities is critical to the success of an entity’s environmental portfolio. Additionally, a model for valuing an organisation's carbon capture potential as suggested by this study enables entities to better report the impact of the adaptation activities on the financial performance and financial position. The outcome of this study enables entities to integrate the carbon capture potential on an entity sustainability reporting framework.
Colleges of Economic and Management Sciences
D. Phil. (Accounting Science)

Livestock agriculture is a source of methane (CH4), nitrous oxide (N2O) and ammonia (NH3) emissions. A comprehensive approach aimed at mitigating these emissions is needed to reduce the environmental footprint of agriculture. This thesis examined three aspects of a comprehensive mitigation strategy which included: evaluating a management consideration, improving flux measurement techniques, and modeling emissions. The relationships between total solids (TS), gas emissions and surface crust dynamics were assessed. Diurnal and long–term CH4 and N2O flux variations were examined in the context of improving discrete sampling protocols. Finally, a mechanistic model that predicts CH4 emissions from manure slurries was evaluated. Over long–term storage, the crusts were not effective in mitigating total gas emissions because the slurries remained open to the atmosphere for a significant portion of the time. Total CH4 and NH3 emissions were related linearly to TS, while N2O exhibited a sigmoid response. The linear response to TS observed for CH4 and NH3 occurred despite varying crust conditions suggesting that the availability of substrates in slurries is the more important regulator of emissions over long–term storage. Diurnal CH4 and N2O flux variations were linked with the diurnal surface temperature (T0) cycle, with the strength of the relationship depending on surface crust conditions. An assessment of discrete sampling protocols revealed that sampling intervals should be ≤7 d. In terms of the timing, it is best to sample these gases when the T0 is closest to the daily mean, which would typically be before 0900 h or after 1700 h. A mechanistic model of CH4 emissions from slurries was evaluated. The model was most accurate during the first 47 d of storage, after which the accuracy decreased. However, total emissions estimated over 145 d were within –21.1 to 6.0% of measured emissions for slurries with TS 3.2%, 5.8% and 8.2%. Emissions were also modeled using the USEPA inventory method. There was relatively good agreement between the USEPA and mechanistic models, with relative percent differences ranging from 19.9 to 37.3%, which is encouraging from the standpoint of advancing greenhouse gas inventory methods.
Ontario Graduate Scholarship

Reliable determinations of ecosystem scale fluxes of net carbon (C) and greenhouse gases for northern peatland ecosystems are of great value to determine the impact of soil warming and altered precipitation on emissions. Additionally, few studies have been performed which measure the C fluxes, particularly methane flux (FCH4), during the spring melt and fall freeze up periods, therefore making it difficult to provide adequate annual C estimates from northern peatland ecosystems. This study aimed to determine ecosystem scale FCH4 from a eutrophic Subarctic fen at Churchill, Manitoba (58°45'N 94°4'W), to understand (a) seasonal trends over two consecutive growing seasons,(b) if over-winter stored CH4 was released as a pulse during the spring-melt period, and (c) soil temperature - FCH4 relations for modelling FCH4 over the spring-melt period. An ecosystem scale methane (CH4) and carbon dioxide (CO2) flux measurement system using the eddy covariance (EC) technique was used from late-June to mid-October of 2008 and early-June to late-September of 2009, with focus on the spring-melt period of late-May to mid-July of 2009. The EC flux measurement system consisted of a closed-path RMT-200 Fast Methane Analyzer (Los Gatos Research Inc.) along with a LI-7500 open-path CO2/H2O gas analyzer (LI-COR Biosci.) and a CSAT3 3-dimensional sonic anemometer (Campbell Sci.). The system was powered by a combination of wind, solar, and gas electric generation. The EC flux measurement system provided seasonal FCH4 values of 0 – 90 nmol CH4 m-2 s-1, similar to previous studies in Subarctic and Arctic peatlands which incorporated the EC technique. A melt period CH4 emission burst was not observed, rather a gradual increase in emission over the spring period. Modelled FCH4 using a temperature-response curve relationship with soil temperature at 5 cm depth over the spring-melt period (May 30 – July 19, 2009) showed the fen to be a net source of CH4, of 1.4 mmol m-2 CO2 equivalent.

A field experiment was carried out in Ontario, Canada to compare independently measured soil N2O profile concentration and surface N2O flux measurements overwinter and at spring thaw, to estimate the soil N2O content accumulation overwinter, and to estimate the magnitude of the contribution of the physical release of trapped N2O to surface fluxes at spring thaw. Gas samples at various depths were taken and N2O concentrations determined, soil profile gaseous N2O content was calculated by estimating the air-filled pore-space from soil condition measurements, and soil aqueous N2O content was calculated using liquid water content measurements and applying Henry’s Law. Soil N2O content was found to reach a maximum of ~25 mg N2O m-2, and by comparing changes in soil N2O content to surface fluxes measured using the micrometeorological flux-gradient technique, the physical release of previously produced N2O was estimated to contribute up to 47% of spring thaw N2O surface fluxes.