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Cold regions are warming much faster than the global average, resulting in more frequent and intense freeze-thaw cycles (FTCs) in soils. In hydrocarbon-contaminated soils, FTCs modify the biogeochemical and physical processes controlling petroleum hydrocarbon (PHC) biodegradation and the associated generation of methane (CH 4 ) and carbon dioxide (CO 2 ). Thus, understanding the effects of FTCs on the biodegradation of PHCs is critical for environmental risk assessment and the design of remediation strategies for contaminated soils in cold regions. In this study, we developed a diffusion-reaction model that accounts for the effects of FTCs on toluene biodegradation, including methanogenic biodegradation. The model is verified against data generated in a 215 day-long batch experiment with soil collected from a PHC contaminated site in Ontario, Canada. The fully saturated soil incubations with six different treatments were exposed to successive 4-week FTCs, with temperatures oscillating between -10 °C and +15 °C, under anoxic conditions to stimulate methanogenic biodegradation. We measured the headspace concentrations and 13 C isotope compositions of CH 4 and CO 2 and analyzed the porewater for pH, acetate, dissolved organic and inorganic carbon, and toluene. The numerical model represents solute diffusion, volatilization, sorption, as well as a reaction network of 13 biogeochemical processes. The model successfully simulates the soil porewater and headspace concentration time series data by representing the temperature dependencies of microbial reaction and gas diffusion rates during FTCs. According to the model results, the observed increases in the headspace concentrations of CH 4 and CO 2 by 87% and 136%, respectively, following toluene addition are explained by toluene fermentation and subsequent methanogenesis reactions. The experiment and the numerical simulation show that methanogenic degradation is the primary toluene attenuation mechanism under the electron acceptor-limited conditions experienced by the soil samples, representing 74% of the attenuation, with sorption contributing to 11%, and evaporation contributing to 15%. Also, the model-predicted contribution of acetate-based methanogenesis to total produced CH 4 agrees with that derived from the 13 C isotope data. The freezing-induced soil matrix organic carbon release is considered as an important process causing DOC increase following each freezing period according to the calculations of carbon balance and SUVA index. The simulation results of a no FTC scenario indicate that, in the absence of FTCs, CO 2 and CH 4 generation would decrease by 29% and 26%, respectively, and that toluene would be biodegraded 23% faster than in the FTC scenario. Because our modeling approach represents the dominant processes controlling PHC biodegradation and the associated CH 4 and CO 2 fluxes, it can be used to analyze the sensitivity of these processes to FTC frequency and duration driven by temperature fluctuations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In this paper, we propose an optimization model that considers two pathways for injecting renewable content into natural gas pipeline networks. The pathways include (1) power-to-hydrogen or PtH, where off-peak electricity is converted to hydrogen via electrolysis, and (2) power-to-methane, or PtM, where carbon dioxide from different source locations is converted into renewable methane (also known as synthetic natural gas, SNG). The above pathways result in green hydrogen and methane, which can be injected into an existing natural gas pipeline network. Based on these pathways, a multi-period network optimization model that integrates the design and operation of hydrogen from PtH and renewable methane is proposed. The multi-period model is a mixed-integer non-linear programming (MINLP) model that determines (1) the optimal concentration of hydrogen and carbon dioxide in the natural gas pipelines, (2) the optimal location of PtH and carbon dioxide units, while minimizing the overall system cost. We show, using a case study in Ontario, the optimal network structure for injecting renewable hydrogen and methane within an integrated natural gas network system provides a $12M cost reduction. The optimal concentration of hydrogen ranges from 0.2 vol % to a maximum limit of 15.1 vol % across the network, while reaching a 2.5 vol % at the distribution point. This is well below the maximum limit of 5 vol % specification. Furthermore, the optimizer realized a CO2 concentration ranging from 0.2 vol % to 0.7 vol %. This is well below the target of 1% specified in the model. The study is essential to understanding the practical implication of hydrogen penetration in natural gas systems in terms of constraints on hydrogen concentration and network system costs. [ABSTRACT FROM AUTHOR]

In this paper, new polygeneration processes co‐producing electricity, methanol, dimethyl ether (DME), and Fischer–Tropsch (FT) fuels from different feedstock ratios of biomass, natural gas, and nuclear hydrogen generated through a copper‐chlorine (CuCl) cycle are analyzed for operation in Canada to produce transportation fuels. This combination of carbonless heat and a 'carbon neutral' biomass feedstock would contribute to the net reduction in greenhouse gas (GHG) emissions. In Part I of this work, the model for this biomass‐gas‐and‐nuclear‐to‐liquids (BGNTL) process was developed. This work expands on it and evaluates the economic and environmental impacts this plant would have in both Ontario and Alberta based on their local costs and resource availability. The analysis demonstrates that an increase in the ratio of biomass to natural gas in feedstock reduces the emissions of the process but increases the cost of carbon dioxide equivalents (CO2e) avoided. The results show that the BGNTL concept can be an economically attractive way of reducing net transportation sector GHG emissions in both Ontario and Alberta in meaningful quantities. [ABSTRACT FROM AUTHOR]

In deregulated electricity sector climates, such as in Ontario, the production of clean or renewable energy by small power producers through distributed generation (DG) is encouraged. This paper examines the policies that can be used to encourage DG investment and incorporates them into a mathematical model. This model is then used to create scenarios for examining the economic and environmental supply-side effects of policies to a distribution system over a ten-year period. The policies analyzed include a combination of feed-in-tariffs, CO2 tax, and cap-and-trade schemes. The results are discussed in the context of the Ontario market and its Standard Offer Program, implemented on a 32-bus radial distribution system. [ABSTRACT FROM AUTHOR]

• New carbon-sequestration geosystem paradigm proposed for screening CO 2 repositories. • Deposition, burial history 1st-order controls on repository attributes, traps, etc. • Genetic understanding of geology enables property prediction away from data control. • Case-study application to heavily industrialized region of onshore Canada. In this paper, I propose a new geoscience paradigm for evaluating potential carbon-sequestration targets. I introduce the term carbon-sequestration geosystem to study and describe portions of sedimentary basins where all the geologic components necessary for the safe and long-term storage of CO 2 are present. The purpose of this type of analysis, most appropriately applied at a basin-screening stage, is to derive a holistic, genetic, and predictive understanding of the geology – the depositional systems, structural setting and other factors that are direct controls on storage, injectivity, potential for induced seismicity, and other critical factors. To illustrate the concepts, I present a re-evaluation of the geologic carbon-sequestration options in Southern Ontario (Canada) where business and environmental needs, mostly associated with hard-to-abate industries, require urgent action. Legacy wireline-logs, core, and outcrop data are the main data sources available in this onshore setting. The results of this new, independent study are broadly similar to those of previous studies: the Cambrian section, a saline aquifer, is the most likely candidate to be a CO 2 repository. However, the methodology used identified several issues (e.g., stratigraphic heterogeneity, proximity to basement) that will need addressing by targeted data collection and/or analysis before site-selection for a test should be undertaken. [ABSTRACT FROM AUTHOR]

Nature-based solutions such as green infrastructure present an opportunity to reduce air pollutant concentrations and greenhouse gas emissions. This paper presents new findings from a controlled field study in Ontario, Canada, evaluating the impact of productive applications of green infrastructure on air pollution and carbon dioxide concentrations across different agricultural morphologies compared to other non-productive applications. This study demonstrates that productive green infrastructure applications are as beneficial as non-productive applications in reducing ozone, nitrogen dioxide, and carbon dioxide concentrations. Nature-based solutions present an opportunity to build climate resilience into agricultural systems through supply-side mitigation and adaptation. The implementation of productive green infrastructure could be a viable agricultural practice to address multiple climate change impacts. [ABSTRACT FROM AUTHOR]

In this paper, we model the greenhouse gas (GHG) intensity of the electric grid in Ontario, Canada, at different temporal resolutions from 2010 through 2018. We developed a stochastic approach to estimate the lifecycle GHG emissions from each type of source of electricity, by assigning uncertainties to critical parameters (carbon dioxide (CO 2), methane and nitrous oxide emissions, and global warming potentials (GWP)), based on variations reported in the literature. The annual mean lifecycle GHG emissions from electricity generated in the province has declined from 175 to 58 g CO 2 e/kWh from 2010 to 2018, considering the GWP time horizon of 100 years. The downward trend is largely associated with the phasing out of coal plants, coupled with the gradually reduced use of natural gas plants, and the increased participation of nuclear and renewables in the mix over the years. We were also able to identify large variations in the lifecycle GHG emissions across months and hours: higher values are generally associated with demand peaks registered in the months of summer and winter, and daily from 5 to 8 p.m. The method employed for the analysis in this paper can serve as a benchmark for other studies on the lifecycle GHG emissions from electricity at various levels (national, provincial, regional, etc.). The Ontario-specific data obtained can serve as a basis for the evaluation of the lifecycle of various activities and sectors within the province. At the corporate level, companies reporting the GHG emissions of their projects and products can improve their estimates by capturing the variations of emissions from electricity generation at the various temporal resolutions. Image 1 • We used hourly generation data to model GHG intensity of electricity in Ontario. • Emissions from electricity declined from 175 to 58 g CO 2 e/kWh from 2010 to 2018. • Higher emissions are due to demand peaks: summer and winter, daily from 5 to 8 p.m. • Hourly GHG intensity varies by a factor of 4–5 within a single year. • Data obtained are useful for LCA practitioners, policy makers and companies. [ABSTRACT FROM AUTHOR]

The objective of this research was to map out the greenhouse gas (GHG) footprint of Ontario transit agencies. A system-by-system GHG emissions model was developed to determine which transit agencies are low, medium, or high emitters based on the metric tonnes of carbon dioxide equivalent (CO2e) emitted from mobile sources. A score card was created based on four preliminary indicators: (1) CO2e per passenger, per revenue vehicle kilometer; (2) CO2e per passenger, per service area density; (3) CO2e per vehicle, per revenue vehicle kilometer; and (4) CO2e per vehicle, per service area density. This score card provides a relative metric to compare the GHG emissions of different transit agencies which can be used as an audit standard for quantifying comparative CO2e reductions. The results indicated that one-third of transit agencies operate in the "A" grade range, while the remaining agencies received grades of "B" to "E"; thus, demonstrating the potential for utilizing Green Funds in different jurisdictions to advance technology and ridership solutions aimed at GHG emissions reduction to achieve climate change objectives. [ABSTRACT FROM AUTHOR]

Abstract: This paper summarizes results from 8 years (1996–2003) of eddy covariance-based ecosystem CO2 exchange measurements at the Borden Forest Research Station (44°19′N, 79°56′W). The site represents a mid-latitude, 100-year-old, mixed deciduous and coniferous forest dominated by red maple, aspen and white pine. The years 1996 and 1997 were relatively cold, had a late spring and received below average photosynthetic photon flux density (PPFD). This contrasts with an early spring, warmer soil and air temperatures during 1998–1999, and with distinctly wet year of 2000 and dry years of 2001–2003. The combination of early spring, warmer air and soil temperature and relatively high level of PPFD was associated with higher net ecosystem productivity (NEP) that peaked during 1999. Photosynthetic capacity was reduced and NEP showed a mid-growing season depression during the dry years of 2001–2003. Annual average ecosystem respiration (R) determined from a light response model was ∼30% less than R derived from a logistic respiration equation, relating night time CO2 flux and soil temperature. However these independently determined R values were well correlated indicating that the site is unaffected by fetch and spatial heterogeneity problems. Based on the combined 8 years of growing season daytime data, an air temperature of 20–25°C and a vapor pressure deficit (VPD) of 1.3kPa were found to be the optimal conditions for CO2 uptake by the canopy. Over the 1996–2003 period, the forest sequestered carbon at an average rate of 140±111gCm−2 y−1. The corresponding gross ecosystem photosynthesis (GEP) and R over this period were 1116±93gCm−2 y−1 and 976±68gCm−2 y−1, respectively. The annual carbon sequestration ranged from 19gCm−2 in 1996 to 281gCm−2 in 1999. However, these estimates were sensitive to frictional velocity threshold () used for screening data associated with poor turbulent mixing at night. Increasing from 0.2ms−1 (based on the inflection point in the nighttime CO2 flux vs. u * relationship) to 0.35ms−1 (determined using a selection algorithm based on change-point detection) modified the 8-year mean NEP estimate from 140±111gCm−2 y−1 to 65±120gCm−2 y−1. Both approaches show that the Borden forest was a low to moderate sink of carbon over the 8-year period. [Copyright &y& Elsevier]

Abstract: Soils and vegetation are the second largest global carbon reservoir. Carbon storage in soil can be increased by increasing carbon inputs and/or reducing decomposition rates. Reduced tillage practices have the potential to increase soil carbon storage by reducing decomposition of soil organic matter and/or crop residue. Isotope values (C) of soil respiration can help infer the contribution of soil carbon pools to the soil CO2flux, providing insight into the effects of tillage on residue decomposition. The objectives of this paper were to: (1) measure the isotope signatures of respired CO2 from conventional tillage and no-till plots; (2) compare and contrast the two treatments in the fall and in the following spring before planting; and (3) compare the C of soil respiration of the experimental plots with the surrounding region. Isotope soil CO2 fluxes were measured using tunable diode laser spectroscopy and micrometeorological methods in a field experiment in Ontario, Canada. Measurements were made in fall following corn (a C4 plant) harvest and again in spring prior to soybean emergence. Data were used to compute the C value of respired CO2 using both the flux ratio and Keeling plot methods. The large concentration footprint prevented the Keeling plots from discerning the treatment effect. In the conventional till plots, the respired C value showed a stronger C4 signature () compared to the no-till field () which had no soil incorporation of above-ground crop residue. This indicates more rapid decomposition of the ‘new’ residue in the conventional tillage treatment. Both treatments showed a decrease in the isotope ratio during the spring measurements ( and for the conventional and no-till plots, respectively) which shows a depletion of the labile C4 substrate and a shift in respired substrate towards the soil C3 organic matter over the fall to spring period. For the fall, we estimate that 57 and 25% of the CO2 flux originated from crop residue for the conventional and no-till systems, while in the spring the proportions had decreased to 22 and 0%, respectively. [Copyright &y& Elsevier]

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• A novel COG desulphurization and COG + BFG to methanol process has been proposed. • A net cradle-to-product reduction of about 272 ktonne CO 2 /yr is possible. • The decision to use the proposed process depends highly on geopolitical circumstance. • Building the proposed methanol plant is a more profitable choice for some of the studied locations. This paper documents a process for converting coke oven gas (COG) and blast furnace gas (BFG) from steel refineries into methanol. Specifically, we propose the use of blast furnace gas (BFG) as an additional carbon source. The high CO 2 and CO content of BFG make it a good carbon resource. In the proposed process, CO 2 is recovered from the BFG and blended with H 2 O, H 2 , and CH 4 -rich COG to reform methane. Optimized amounts of H 2 O and CO 2 are used to adjust the (H 2 – CO 2)/(CO + CO 2) molar ratio in order to maximize the amount of methanol that is produced. In addition, the desulphurization process was modified to enable the removal of sulfur compounds, especially thiophene, from the COG. The process design and simulation results reported herein were then used to determine any potential environmental and economic benefits. This research is based on off-gas conditions provided by ArcelorMittal Dofasco (AMD), Hamilton, Ontario. In order to determine which conditions are most desirable for this retrofit strategy, potential greenhouse gas reduction and economic benefits were analyzed. In particular, this analysis focused on the heating utility chosen for methane reformation prior to methanol synthesis. To this end, COG, BFG, and natural gas (NG) were compared. The results showed that using BFG/NG as a heating utility can produce greater economic gains, and that synthesizing COG + BFG to methanol results in greater economic and environmental gains than solely producing electricity (the status quo). Compared to current operating procedures, the proposed process could potentially increase net present values by up to $54 million. The carbon efficiency achieved was up to 72%. An additional 0.73 kg of CO 2 from BFG is needed for every 1 kg of MeOH produced. About 52% of feedstock energy is converted to MeOH, with another 33% recovered in the form of utilities. The exergy efficiency of the recommended version of the system is about 61%. The business case for converting CO 2 into methanol highly depends on the local electricity grid carbon intensity. For Ontario, it can reduce direct CO 2 emissions by 228 ktonne per year, and fix up to 246 ktonne CO 2 into methanol per year. In addition, analyses of location effects, CO 2 taxes, electricity prices, electricity carbon intensity, methanol prices, and income taxes indicated that MeOH production is highly recommended for Ontario, Mexico, the USA, and China applications. For USA, build MeOH plant is recommended for Finland, whether to do this retrofit or not is inconclusive. For Finland, the results are inconclusive, other strategies may be equally suitable. Aspen Plus Simulation files and other source code have been open-sourced and are available to the reader. [ABSTRACT FROM AUTHOR]

Canada's mineral reserves can play a very important role in curbing climate change if natural alkaline minerals are used for the process of mineral carbonation. In this work, the potential of using two Canadian natural silicates for accelerated carbonation is experimentally assessed: kimberlite mine tailing (Mg0.846Al0.165Fe0.147Ca0.067SiO3.381) from the Northwest Territories, and mined wollastonite ore (Ca0.609Mg0.132Al0.091Fe0.024SiO2.914) from Ontario. The aim of this work was to evaluate the weathering reactivity and CO2 uptake capacity via carbonation of these two comminuted rocks, both of which are made up of a mixture of alkaline minerals, under process conditions that spanned from milder to intensified. Research questions addressed include: does kimberlite contain a sufficient amount of reactive minerals to act as an effective carbon sink; is dehydroxylation necessary to activate kimberlite, and to what extent does it do this; do secondary phases of wollastonite hinder its reactivity; and can either of these minerals be carbonated without pH buffering, or only weathered? Incubator, slurry, and pressurized slurry methods of accelerated weathering and carbonation were used, and the effect of the process parameters (temperature, solid-to-liquid ration, reaction time, CO2 level, pH buffer) on the CO2 uptake and crystalline carbonates formation is tested. The reacted samples were analyzed by pH test, loss-on-ignition test, calcimeter test, and X-ray diffraction analysis. Results showed that wollastonite ore (rich in fast-weathering CaSiO3) is more suitable for accelerated carbonation than kimberlite tailing (containing slow-weathering hydrated magnesium silicates and aluminosilicates) when only its capability to rapidly form solid carbonates is considered. Incubator and pressurized buffered slurry methods proved to be most effective as under these conditions the precipitation of carbonates was more favorable, while the unbuffered slurry reaction conditions were more akin to accelerated weathering rather than accelerated carbonation. [ABSTRACT FROM AUTHOR]

The article focuses on the supersaturation of carbon dioxide (CO2) and methane (CH4) in the surface waters at the Mer Bleue peatlands in Ottawa, Ontario. Information on the mean annual temperature and precipitation is presented. Surface waters were tested from 11 different points of the Mer Bleue drainage system for over 2 weeks during spring snowmelt in April 2005. The temperature and potential Hydrogen (pH) conductivity are also determined. Other methodology and results of the study are discussed.

Measurements of energy, carbon dioxide and water vapour fluxes and supporting meteorological variables were made from 1 September 2003 to 31 August 2004 in a 74-year-old mixedwood forest in northern Ontario, Canada, using the eddy covariance technique. Land surface cover data analysis showed that although this forest is comprised of deciduous and coniferous species, their proportion throughout the forest was almost equal, resulting in a homogeneously mixedwood stand. The seasonal pattern of albedo showed a distinct pattern as a result of mixed deciduous and coniferous species with the first low radiation reflection period in early spring (between snowmelt and deciduous leaf-out), and the second low reflection period in late autumn (between senescence and snowfall). Root zone soil water content remained above 0.32 throughout the growing season, which is characteristic of wet soil conditions. The evaporative flux exceeded the sensible heat flux during most of the growing season. Daily mean evapotranspiration values during the peak growing season were about 2–2.5 mm day-1 with maximum values reaching up to 4–5 mm day-1 on sunny days. The total water loss over the 12-month measurement period was 480 ± 30 mm, while the total precipitation was 835 mm. Despite high soil water content, bulk surface conductance calculated using the inverted Penman-Monteith formulation, showed a strong correlation with vapour pressure deficit (VPD), indicating stomatal control on water loss during the afternoons with high atmospheric demand and during occasional dry periods. Bulk surface conductance values in this mixedwood forest were relatively higher than those in other boreal coniferous forests and were more similar to values observed in the southern boreal deciduous forests. The Priestley-Taylor α values showed a wide range but during most of the growing season its values were close to unity, indicating that water stress does not play a major role in the overall water loss from this boreal forest ecosystem, while energy supply has a strong control on evapotranspiration. These results will help parameterize accurately energy and water exchanges for the moist mixedwood forests in land surface-atmosphere interaction and hydrologic models. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Botany is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: The effect of rainfall patterns on soil surface CO2 efflux, soil moisture, soil temperature and plant growth was investigated in a grassland ecosystem of northern Ontario, Canada, where climatic change is predicted to introduce new precipitation regimes. Rain shelters were established in a fallow field consisting mainly of Trifolium hybridum L., Trifolium pratense L., and Phleum pratense L. Daytime ambient air temperatures within the shelters increased by an average of 1.9°C similar to predicted future increases in air temperatures for this region. To simulate six precipitation regimes which cover the maximum range to be expected under climate change, a portable irrigation system was designed to modify the frequency of monthly rainfall events with a constant delivery rate of water, while maintaining contemporary average precipitation volumes. Controls consisted of blocks irrigated with frequencies and total monthly precipitation consistent with the 25 year average rainfall for this location. Results: Seasonal soil moisture correlated with soil surface CO2 efflux (R = 0.756, P < 0.001) and above ground plant biomass (R = 0.447, P = 0.029). By reducing irrigation frequency, soil surface CO2 efflux decreased by 80%, P < 0.001, while soil moisture content decreased by 42%, P < 0.001. Conclusions: Manipulating the number of precipitation events and inter-rainfall intervals, while maintaining monthly rainfall averages impacted CO2 efflux and plant growth. Even with monthly rainfall averages that are similar to contemporary monthly precipitation averages, decreasing the number of monthly rainfall events reduced soil surface CO2 efflux and plant growth through soil moisture deficits. Although many have speculated that climate change will increase ecosystem productivity, our results show that a reduction in the number of monthly rainfall events while maintaining monthly averages will limit carbon dynamics. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)