Carbon, nitrogen and phosphorus release from peat and forest floor-based cover soils used during oil sands reclamation

Reclamation practices in the oil sands region of Alberta involve the reconstruction of soil profiles using a combination of salvaged mineral substrates and organic matter-rich surface materials, including peat-mineral mix (PM) and forest floor-mineral mix (FFM). The successful re-establishment of vegetation on reclaimed sites is for a large part dependent on the nutrients these materials can provide. Hence, the overall objective of this study was to compare carbon (C), nitrogen (N) and phosphorus (P) release rates from PM and FFM materials used to cap reconstructed sandy soils. A 325-day laboratory incubation was conducted to measure these rates. The two materials released comparable amounts of N on a per kilogram of soil basis (111 to 118 mgN kg-1). However, when results were normalized based on each materialâ s organic C content, N release was six times greater for FFM than for PM, in accordance with results of previous studies. In addition, overall C mineralization and P release rates were over one order of magnitude higher with FFM than with PM. As opposed to N, however, P release seemed to be controlled more by abiotic processes than by organic matter mineralization. While the FFM material overall released more N and P, it also degraded faster; in comparison, PM may provide a smaller but more stable release of N.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Assessing Structural and Functional Indicators of Soil Nitrogen Availability in Reclaimed Forest Ecosystems Using 15N-labelled Aspen Litter

Landscape-level disturbance is a reality in many parts of the world including the Athabasca oil sands region, Canada, and soils play an essential part in the overall reclamation process. Soils are reconstructed during reclamation to provide a foundation and a nutrient source for the novel ecosystems. However, reclamation is often monitored through structural indicators of soil quality, which may not reflect dynamic ecosystem functions such as nutrient cycling. Our objective was to determine if nutrient cycling was occurring on novel ecosystems and if standard structural measures of soil quality were appropriate indicators. We assessed soil quality and nitrogen cycling in reclaimed, harvested and undisturbed aspen forest sites following the addition of 15N-labelled aspen (Populus tremuloides Michx.) leaf litter to the soil surface. Structural soil quality indicators, including soil moisture and microbial carbon and nitrogen biomass, were higher on the undisturbed site, whereas soil microbial composition differed among sites. Yet, uptake of 15N by microbes and plants, which continued throughout the 52 mo field incubation, was comparable across all sites. These results indicate that differences in structural attributes between disturbed and undisturbed soils do not necessarily translate into differences in soil functioning related to nitrogen cycling. Instead, this case study supports exploring the use of stable isotope tracers to assess dynamic soil function indicators in reclaimed ecosystems. Being able to follow biogeochemical cycling as vegetation becomes established and new forests start to develop following reclamation is key to assessing the long-term sustainability of these novel ecosystems

Comparative analysis of cellulose preparation techniques for use with 13C, 14C, AND 18O isotopic measurements.

A number of operationally defined methods exist for pretreating plant tissues in order to measure C, N, and O isotopes. Because these isotope measurements are used to infer information about environmental conditions that existed at the time of tissue growth, it is important that these pretreatments remove compounds that may have exchanged isotopes or have been synthesized after the original formation of these tissues. In stable isotope studies, many pretreatment methods focus on isolating "cellulose" from the bulk tissue sample because cellulose does not exchange C and O isotopes after original synthesis. We investigated the efficacy of three commonly applied pretreatment methods, the Brendel method and two variants of the Brendel method, the Jayme-Wise method and successive acid/base/acid washes, for use on three tissue types (wood, leaves, roots). We then compared the effect of each method on C and O isotope composition (13C, 14C, 18O), C and N content, and chemical composition of the residue produced (using 13C nuclear magnetic resonance (NMR)). Our results raised concerns over use of the Brendel method as published, as it both added C and N to the sample and left a residue that contains remnant lipids and waxes. Furthermore, this method resulted in 18O values that are enriched relative to the other methods. Modifying the Brendel method by adding a NaOH step (wash) solved many of these problems. We also found that processed residues vary by tissue type. For wood and root tissues, the 13C NMR spectra and the 18O and 13C data showed only small differences between residues for the Jayme-Wise and modified Brendel methods. However, for leaf tissue, 13C NMR data showed that Jayme-Wise pretreatments produced residues that are more chemically similar to cellulose than the other methods. The acid/base/acid washing method generated 13C NMR spectra with incomplete removal of lignin for all tissues tested and both isotopic, and 13C NMR results confirmed that this method should not be used if purified cellulose is desired

Comparative analysis of cellulose preparation techniques for use with 13C, 14C, AND 18O isotopic measurements.

A number of operationally defined methods exist for pretreating plant tissues in order to measure C, N, and O isotopes. Because these isotope measurements are used to infer information about environmental conditions that existed at the time of tissue growth, it is important that these pretreatments remove compounds that may have exchanged isotopes or have been synthesized after the original formation of these tissues. In stable isotope studies, many pretreatment methods focus on isolating "cellulose" from the bulk tissue sample because cellulose does not exchange C and O isotopes after original synthesis. We investigated the efficacy of three commonly applied pretreatment methods, the Brendel method and two variants of the Brendel method, the Jayme-Wise method and successive acid/base/acid washes, for use on three tissue types (wood, leaves, roots). We then compared the effect of each method on C and O isotope composition (13C, 14C, 18O), C and N content, and chemical composition of the residue produced (using 13C nuclear magnetic resonance (NMR)). Our results raised concerns over use of the Brendel method as published, as it both added C and N to the sample and left a residue that contains remnant lipids and waxes. Furthermore, this method resulted in 18O values that are enriched relative to the other methods. Modifying the Brendel method by adding a NaOH step (wash) solved many of these problems. We also found that processed residues vary by tissue type. For wood and root tissues, the 13C NMR spectra and the 18O and 13C data showed only small differences between residues for the Jayme-Wise and modified Brendel methods. However, for leaf tissue, 13C NMR data showed that Jayme-Wise pretreatments produced residues that are more chemically similar to cellulose than the other methods. The acid/base/acid washing method generated 13C NMR spectra with incomplete removal of lignin for all tissues tested and both isotopic, and 13C NMR results confirmed that this method should not be used if purified cellulose is desired