Search

Oil and gas exploration has resulted in over 300,000 km of linear disturbances, known as seismic lines, throughout boreal peatlands across Canada. Sites are left with altered hydrologic and topographic conditions that prevent tree re-establishment. Restoration efforts have concentrated on tree recovery through mechanical mounding to re-create microtopography and support planted tree seedlings to block sightlines and deter the use of lines by wolves, but little is known about the impact of seismic line disturbance or restoration on peatland carbon cycling. This study looked at two mounding treatments and compared summer growing season carbon dioxide and methane fluxes to untreated lines and natural reference areas of a wooded fen in the first two years post-restoration. We found no significant differences in net ecosystem CO2 exchange, but untreated seismic lines were slightly more productive than natural reference areas and mounding treatments. Both restoration treatments increased ecosystem respiration, decreased net productivity by 6–21 g CO2 m−2 d−1, and created areas of increased methane emissions, including an increase in the contribution of ebullition, of up to 2000 mg CH4 m−2 d−1 over natural and untreated lines. Further research on this site to assess the longer-term impacts of restoration, as well as application on other sites with varied conditions, will help determine if these restoration practices are effective at restoring carbon cycling. [ABSTRACT FROM AUTHOR]

In response to growing pressures to reduce the clinker content in cement and hence the CO2 emissions associated with its production, the Canadian Standards Association (CSA A3001-08) introduced a new classification of cement in 2008, this being Portland limestone cement (PLC) containing up to 15% limestone. PLC is now permitted in the production of all classes of concrete in Canada except for sulfate-exposure classes (CSA A23.1-09). Considerable laboratory testing has been conducted in Canada in recent years to demonstrate that PLC with up to 15% limestone can be manufactured to produce equivalent performance to a Portland cement in terms of concrete strength and other properties, including durability. The equivalent performance is achieved by optimizing the PLC with regards to composition and particle-size distribution, and this is achieved by intergrinding rather than blending of the Portland cement and limestone. This paper presents data from a number of recent full-scale field trials where PLC has been used in paving projects in Quebec, Alberta, and Nova Scotia. In each field trial, the performance of PLC concrete has been compared with that of equivalent concrete produced using Portland cement (PC), and concretes have been produced with varying levels (up to 50%) of supplementary cementing materials (SCM). Testing of concrete produced during the field trials has included compressive strength, freeze-thaw and deicer-salt-scaling resistance, chloride permeability, and chloride diffusion. The results indicate that concrete performance is strongly influenced by the level of SCM used, but is independent of whether PLC or PC is used. The use of such PLC has the potential to bring about a 10% reduction in the greenhouse gas emissions associated with the production of Portland cement clinker. The acceptable performance of concrete containing combinations of PLC and SCM will permit further reductions in the CO2 footprint of the concrete; in one mix, the clinker content was just 41% of the total mass of cementing material. [ABSTRACT FROM AUTHOR]

Greenhouse gases in the atmosphere, mainly carbon dioxide (CO2), can be mitigated by the planting of trees and shrubs. Appropriate agroforestry practices in Saskatchewan include field and farmyard shelterbelts, wildlife plantations, poplar plantations and managed woodlots. A study was conducted to determine the amount of carbon held in prairie shelterbelts. The effect of the soil type and tree species on biomass and carbon content was measured in shelterbelts in the brown, dark brown and black soil zones of Saskatchewan. For some of the main shelterbelt species, the mean aboveground carbon content was 79 kg/tree (32 t/km) for green ash, 263 kg/tree (105 t/km) for poplar, 144 kg/tree (41 t/km) for white spruce and 26 t/km for caragana. Inthe brown and the dark brown soils, which are more arid than the black soil zone, trees had 60.6% and 65.5%, respectively, of the biomassand carbon content of trees and shrubs in the black soil zone. Improved, fast-growing poplar clones had the greatest biomass at maturity and fixed the greatest amount of carbon. Simple equations were developed to calculate the carbon contents of prairie shelterbelts, based on easily measured tree or shrub parameters. This paper will discuss the results of this particular study and the broader implications of this work. [ABSTRACT FROM AUTHOR]

During 2 years (2009, 2010), CO fluxes were measured in an oligotrophic fen located at the ecotonal limit of forest tundra and lichen woodland, in northeastern Canada. Peatlands in this region have registered a rise in surface moisture since Little Ice Age, allowing an increase in their pool size and density. In the studied peatland, 83 % of the surface is covered either with pools (42 %), hollows (28 %) and lawns (13 %) all of which present a mean water table higher than 7 cm. We evaluated how these conditions might influence the CO balance in these poor fens located in the northeastern section of the La Grande river watershed. During the two years measurements, results indicate a net CO source with 404 (±287) and 272 (±250) g CO myear emitted to the atmosphere throughout the growing seasons and winters. Modeled wintertime net ecosystem exchange resulted in a net loss of 150 (±36) and 150 (±37) g CO m year in 2009 and 2010 respectively, while 248 (±248) and 124 (±195) g CO m was emitted during 2009 and 2010 growing seasons. This high CO source can be attributed to three factors: (1) the length of the cold season which represented 210-214 days of net CO loss (2) a high pool/vegetated surface ratio since pools are a net source of CO and presented 38-40 % of the annual spatially weighted CO budget and (3) hydroclimatic conditions during the growing season as dryer and warmer conditions in 2009 reduced photosynthesis and increased respiration rates. [ABSTRACT FROM AUTHOR]

The agricultural sector is responsible for an important part of Canadian greenhouse gas (GHG) emissions, 8 % of the 747 Mt eq. CO emitted each year. The pork industry, a key sector of the agrifood industry, has had a rapid growth in Canada since the middle 1980s. For this industry, slurry storage accounts for the major part of methane (CH) emissions, a GHG 25 times higher than carbon dioxide (CO) on a 100-year time horizon. Intending to reduce these emissions, biofiltration, a process effective to treat CH from landfills and coal mines, could be effective to treat CH from the pig industry. Biofiltration is a complex process that requires the understanding of the biological process of CH oxidation and a control of the engineering parameters (filter bed, temperature, etc.). Some biofiltration studies show that this technology could be used to treat CH at a relatively low cost and with a relatively high purification performance. [ABSTRACT FROM AUTHOR]

In 2001–03, continuous eddy covariance measurements of carbon dioxide (CO2) flux were made above mature boreal aspen, black spruce, and jack pine forests in Saskatchewan, Canada, prior to and during a 3−year drought. During the 1st drought year, ecosystem respiration ( R) was reduced at the aspen site due to the drying of surface soil layers. Gross ecosystem photosynthesis (GEP) increased as a result of a warm spring and a slow decrease of deep soil moisture. These conditions resulted in the highest annual net ecosystem productivity (NEP) in the 9 years of flux measurements at this site. During 2002 and 2003, a reduction of 6% and 34% in NEP, respectively, compared to 2000 was observed as the result of reductions in both R and GEP, indicating a conservative response to the drought. Although the drought affected most of western Canada, there was considerable spatial variability in summer rainfall over the 100−km extent of the study area; summer rainfalls in 2001 and 2002 at the two conifer sites minimized the impact of the drought. In 2003, however, precipitation was similarly low at all three sites. Due to low topographic position and consequent poor drainage at the black spruce site and the coarse soil with low water-holding capacity at the jack pine site almost no reduction in R, GEP, and NEP was observed at these two sites. This study shows that the impact of drought on carbon sequestration by boreal forest ecosystems strongly depends on rainfall distribution, soil characteristics, topography, and the presence of vegetation that is well adapted to these conditions. [ABSTRACT FROM AUTHOR]

The Denitrification-Decompostion (DNDC) model was used to estimate the impact of change in management practices on N2O emissions in seven major soil regions in Canada, for the period 1970 to 2029. Conversion of cultivated land to permanent grassland would result in the greatest reduction in N2O emissions, particularly in eastern Canada where the model estimated about 60% less N2O emissions for this conversion. About 33% less N2O emissions were predicted for a change from conventional tillage to no-tillage in western Canada, however, a slight increase in N2O emissions was predicted for eastern Canada. Greater N2O emissions in eastern Canada associated with the adoption of no-tillage were attributed to higher soil moisture causing denitrification, whereas the lower emissions in western Canada were attributed to less decomposition of soil organic matter in no-till versus conventional tilled soil. Elimination of summer fallow in a crop rotation resulted in a 9% decrease in N2O emissions, with substantial emissions occurring during the wetter fallow years when N had accumulated. Increasing N-fertilizer application rates by 50% increased average emissions by 32%, while a 50% decrease of N-fertilizer application decreased emissions by 16%. In general, a small increase in N2O emissions was predicted when N-fertilizer was applied in the fall rather than in the spring. Previous research on CO2 emissions with the CENTURY model (Smith et al., 2001) allowed the quantification of the combined change in N2O and CO2 emissions in CO2 equivalents for a wide range of management practices in the seven major soil regions in Canada. The management practices that have the greatest potential to reduce the combined N2O and CO2 emissions are conversion from conventional tillage to permanent grassland, reduced tillage, and reduction of summer fallow. The estimated net greenhouse gas (GHG) emission reduction when changing from cultivated land to permanent grassland ranged from 0.97 (Brown Chernozem) to 4.24 Mg CO2 equiv. ha−1 y−1 (Black Chernozem) for the seven soil regions examined. When changing from conventional tillage to no-tillage the net GHG emission reduction ranged from 0.33 (Brown Chernozem) to 0.80 Mg CO2 equiv. ha−1 y−1 (Dark Gray Luvisol). Elimination of fallow in the crop rotation lead to an estimated net GHG emission reduction of 0.43 (Brown Chernozem) to 0.80 Mg CO2 equiv. ha−1 y−1 (Dark Brown Chernozem). The addition of 50% more or 50% less N-fertilizer both resulted in slight increases in combined CO2 and N2O emissions. There was a tradeoff in GHG flux with greater N2O emissions and a comparable increase in carbon storage when 50% more N-fertilizer was added. The results from this work indicate that conversion of cultivated land to grassland, the conversion from conventional tillage to no-tillage, and the reduction of summerallow in crop rotations could substantially increase C sequestration and decrease net GHG emissions. Based on these results a simple scaling-up scenario to derive the possible impacts on Canada''s Kyoto commitment has been calculated. [ABSTRACT FROM AUTHOR]

Sedimentary basins are suitable to different degrees for CO2 geological sequestration as a result of various intrinsic and extrinsic characteristics, of which the geothermal regime is one of the most important. Warm basins are less favorable for CO2 sequestration than cold basins because of reduced capacity in terms of CO2 mass, and because of higher CO2 buoyancy, which drives the upward CO2 migration. A set of 15 criteria, with several classes each, has been developed for the assessment and ranking of sedimentary basins in terms of their suitability for CO2 sequestration. Using a parametric normalization procedure, a basin's individual scores are summed to a total score using weights that express the relative importance of different criteria. The total score is ranked to determine the most suitable basin or region thereof for the geological sequestration of CO2. The method is extremely flexible in that it allows changes in the functions that express the importance of various classes for any given criterion, and in the weights that express the relative importance of various criteria. Examples of application are given for Canada's case and for the Alberta basin in Canada. [ABSTRACT FROM AUTHOR]