Correction factors for large-scale greenhouse gas assessment from pulp and paper mill sludge landfill sites.

Assessments of greenhouse gas (GHG) emissions in managed areas are facing various challenges. A non-flow-through, non-steady-state (NFT-NSS) chamber coupled to a frame permanently inserted into the landfilled substrates is a standard method for quantifying GHG emissions in managed areas, such as pulp and paper mill sludge (PPMS) landfill sites. Frequent measurements are needed to minimize uncertainties on GHG emission factors at the landfill site scale. However, maintaining a frame inserted into the substrates for a long time period is often impossible due to landfilling management operations. Therefore, GHG measurements using NFT-NSS chambers placed directly on substrates' surface could be an interesting option. Our objectives were to determine the relationships between CO2, CH4, and N2O fluxes measured with (F + ) and without (F-) a frame inserted in the substrates' surface and to develop correction factors for fluxes measured without a frame. Measurements were made at different PPMS landfill sites in the province of Québec, Canada. Stronger GHG flux relationships were observed at the provincial (across sites) than the specific site scale: the variance in GHG fluxes from F- chambers explained up to 80 % of variance in fluxes from F + chambers. The measured CO2, CH4, and N2O fluxes in F- chambers were on average 53, 78, and 63 % lower, respectively, than those estimated by the models at provincial scale. The correction factors developed with this approach could greatly extend the number of sites where in situ GHG measurements can be done and would help refining GHG inventories at the provincial and national levels.

Greenhouse Gas Emissions after Application of Landfilled Paper Mill Sludge for Land Reclamation of a Nonacidic Mine Tailings Site.

Large areas of mine tailings are reclaimed by applying organic amendments such as paper mill sludge (PMS). Although mining industries can use PMS freshly generated by paper mills, operational constraints on paper industries make temporary landfilling of this material an unavoidable alternative for the paper industries, creating the most prominent PMS source for mining industries. This study aimed to quantify soil greenhouse gas (GHG) emissions (NO, CO, and CH) after application of landfilled PMS (LPMS; i.e., excavated from a landfill site at a paper mill) and LPMS combined with a seeding treatment of white clover ( L.) on nonacidic mine tailings site prior to reforestation. Soil NO, CO, and CH fluxes were measured after applications of 50 and 100 Mg dry LPMS ha during two consecutive snow-free seasons on two adjacent sites; LPMS was applied once in the first season. The LPMS application increased NO emissions (7.6 to 34.7 kg NO-N ha, comprising 1.04 to 2.43% of applied N) compared with the unamended control during the first season; these emissions were negligible during the second season. The LPMS application increased CO emissions (∼5800 to 11,400 kg CO-C ha, comprising 7 to 27% of applied C) compared with the unamended control on both sites and in both seasons. Fluxes of CH were negligible. White clover combined with LPMS treatments did not affect soil GHG emissions. These new GHG emission factors should be integrated into life-cycle analyses to evaluate the C footprint of potential symbioses between the mining and paper industries. Future research should focus on the effect of PMS applications on soil GHG emissions from a variety of mine tailings under various management practices and climatic conditions to plan responsible and sustainable land reclamation.

Uncovering the Minor Contribution of Land-Cover Change in Upland Forests to the Net Carbon Footprint of a Boreal Hydroelectric Reservoir.

Hydropower in boreal conditions is generally considered the energy source emitting the least greenhouse gas per kilowatt-hour during its life cycle. The purpose of this study was to assess the relative contribution of the land-use change on the modification of the carbon sinks and sources following the flooding of upland forested territories to create the Eastmain-1 hydroelectric reservoir in Quebec's boreal forest using Carbon Budget Model of the Canadian Forest Sector. Results suggest a carbon sink loss after 100 yr of 300,000 ± 100,000 Mg CO equivalents (COe). A wildfire sensitivity analysis revealed that the ecosystem would have acted as a carbon sink as long as <75% of the territory had burned over the 100-yr-long period. Our long-term net carbon flux estimate resulted in emissions of 4 ± 2 g COe kWh as a contribution to the carbon footprint calculation, one-eighth what was obtained in a recent study that used less precise and less sensitive estimates. Consequently, this study significantly reduces the reported net carbon footprint of this reservoir and reveals how negligible the relative contribution of the land-use change in upland forests to the total net carbon footprint of a hydroelectric reservoir in the boreal zone can be.

eNOS gene delivery prevents hypertension and reduces renal failure and injury in rats with reduced renal mass.

BACKGROUND: Impaired nitric oxide (NO) release in chronic renal failure has been implicated in the pathogenesis of hypertension and the progression of renal insufficiency. We investigated whether gene delivery of the endothelial NO synthase (eNOS) improves NO release and reduces blood pressure and renal failure and injury in rats with reduced renal mass. METHODS: Renal failure was induced by renal artery branches ligation. Two weeks later, rats with renal failure were divided into three groups and received an intravenous injection of the vehicle or the adenovirus that expresses eNOS or ß-galactosidase (ß-gal). Systolic blood pressure, renal parameters and histopathology were assessed at Week 4 after gene delivery. RESULTS: At the end of the study, systolic blood pressures, serum creatinine, proteinuria, urinary endothelin-1 (ET-1) excretion and renal cortex ET-1 levels were increased, whereas plasma and urine NO(2)/NO(3) were reduced in renal failure rats as compared to normal controls. Renal injury comprised blood vessel media hypertrophy, focal and segmental glomerular sclerosis, tubular atrophy and interstitial fibrosis. Gene delivery of eNOS, but not ß-gal, prevented an increase in systolic blood pressure and proteinuria, and a reduction in plasma and urine NO(2)/NO(3). eNOS gene delivery also reduced a rise in serum creatinine, urinary ET-1 excretion and renal cortex ET-1 levels, and the renal vascular, glomerular and tubular injury. CONCLUSION: This study indicates that eNOS gene delivery in rats with renal failure improves NO release, which likely prevents the aggravation of hypertension and slows down the progression of renal failure and injury.