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Obi-Njoku O, Boh MY, Smith W, Grant B, Flemming C, Price GW, Hernandez-Ramirez G, Burton D, Whalen JK, Clark OG. A comparison of Tier 1, 2, and 3 methods for quantifying nitrous oxide emissions from soils amended with biosolids. Sci Total Environ 2024; 915:169639. [PMID: 38181952 DOI: 10.1016/j.scitotenv.2023.169639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 12/08/2023] [Accepted: 12/21/2023] [Indexed: 01/07/2024]
Abstract
Municipal biosolids are a nitrogen (N)-rich agricultural fertilizer which may emit nitrous oxide (N2O) after rainfall events. Due to sparse empirical data, there is a lack of biosolids-specific N2O emission factors to determine how land-applied biosolids contribute to the national greenhouse gas inventory. This study estimated N2O emissions from biosolids-amended land in Canada using Tier 1, Tier 2 (Canadian), and Tier 3 (Denitrification and Decomposition model [DNDC]) methodologies recommended by the Intergovernmental Panel on Climate Change (IPCC). Field data was from replicated plots at 8 site-years between 2017 and 2019 in the provinces of Quebec, Nova Scotia and Alberta, Canada, representing three distinct ecozones. Municipal biosolids were the major N source for the crop, applied as mesophilic anaerobically digested biosolids, composted biosolids, or alkaline-stabilized biosolids alone or combined with an equal amount of urea-N fertilizer to meet the crop N requirements. Fluxes of N2O were measured during the growing season with manual chambers and compared to N2O emissions estimated using the IPCC methods. In all site-years, the mean emission of N2O in the growing season was greater with digested biosolids than other biosolids sources or urea fertilizer alone. The emissions of N2O in the growing season were similar with composted or alkaline-stabilized biosolids, and no greater than the unfertilized control. The best estimates of N2O emissions, relative to measured values, were with the Tier 3 > adapted Tier 2 with biosolids-specific correction factors > standard Tier 2 = Tier 1 methods of the IPCC, according to the root mean square error statistic. The Tier 3 IPCC method was the best estimator of N2O emissions in the Canadian ecozones evaluated in this study. These results will be used to improve methods for estimating N2O emissions from agricultural soils amended with biosolids and to generate more accurate GHG inventories.
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Affiliation(s)
- Okenna Obi-Njoku
- Department of Bioresource Engineering, McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Michael Yongha Boh
- Department of Bioresource Engineering, McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Ward Smith
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Ave, Ottawa, ON, K1A 0C6, Canada
| | - Brian Grant
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, 960 Carling Ave, Ottawa, ON, K1A 0C6, Canada
| | - Corey Flemming
- Pollutant Inventories and Reporting Division, Environment and Climate Change Canada, 351 St-Joseph Blvd, Gatineau, QC, K1A 0H3, Canada
| | - G W Price
- Department of Engineering, Faculty of Agriculture, Dalhousie University, PO Box 550, Truro, NS, B2N 5E3, Canada
| | - Guillermo Hernandez-Ramirez
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB, T6G 2E3, Canada
| | - David Burton
- Department of Engineering, Faculty of Agriculture, Dalhousie University, PO Box 550, Truro, NS, B2N 5E3, Canada
| | - Joann K Whalen
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - O Grant Clark
- Department of Bioresource Engineering, McGill University, 21111 Lakeshore Road, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada.
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Willcock S, Phillips OL, Platts PJ, Balmford A, Burgess ND, Lovett JC, Ahrends A, Bayliss J, Doggart N, Doody K, Fanning E, Green JMH, Hall J, Howell KL, Marchant R, Marshall AR, Mbilinyi B, Munishi PKT, Owen N, Swetnam RD, Topp-Jorgensen EJ, Lewis SL. Quantifying and understanding carbon storage and sequestration within the Eastern Arc Mountains of Tanzania, a tropical biodiversity hotspot. Carbon Balance Manag 2014; 9:2. [PMID: 24891875 PMCID: PMC4041645 DOI: 10.1186/1750-0680-9-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 03/31/2014] [Indexed: 05/27/2023]
Abstract
BACKGROUND The carbon stored in vegetation varies across tropical landscapes due to a complex mix of climatic and edaphic variables, as well as direct human interventions such as deforestation and forest degradation. Mapping and monitoring this variation is essential if policy developments such as REDD+ (Reducing Emissions from Deforestation and Forest Degradation) are to be known to have succeeded or failed. RESULTS We produce a map of carbon storage across the watershed of the Tanzanian Eastern Arc Mountains (33.9 million ha) using 1,611 forest inventory plots, and correlations with associated climate, soil and disturbance data. As expected, tropical forest stores more carbon per hectare (182 Mg C ha(-1)) than woody savanna (51 Mg C ha(-1)). However, woody savanna is the largest aggregate carbon store, with 0.49 Pg C over 9.6 million ha. We estimate the whole landscape stores 1.3 Pg C, significantly higher than most previous estimates for the region. The 95% Confidence Interval for this method (0.9 to 3.2 Pg C) is larger than simpler look-up table methods (1.5 to 1.6 Pg C), suggesting simpler methods may underestimate uncertainty. Using a small number of inventory plots with two censuses (n = 43) to assess changes in carbon storage, and applying the same mapping procedures, we found that carbon storage in the tree-dominated ecosystems has decreased, though not significantly, at a mean rate of 1.47 Mg C ha(-1) yr(-1) (c. 2% of the stocks of carbon per year). CONCLUSIONS The most influential variables on carbon storage in the region are anthropogenic, particularly historical logging, as noted by the largest coefficient of explanatory variable on the response variable. Of the non-anthropogenic factors, a negative correlation with air temperature and a positive correlation with water availability dominate, having smaller p-values than historical logging but also smaller influence. High carbon storage is typically found far from the commercial capital, in locations with a low monthly temperature range, without a strong dry season, and in areas that have not suffered from historical logging. The results imply that policy interventions could retain carbon stored in vegetation and likely successfully slow or reverse carbon emissions.
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Affiliation(s)
- Simon Willcock
- School of Geography, University of Leeds, Leeds, LS2 9JT UK
- School of Biological Sciences, University of Southampton, Southampton, SO17 1BJ UK
| | | | - Philip J Platts
- Environment Department, University of York, York, YO10 5DD UK
| | - Andrew Balmford
- Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ UK
| | - Neil D Burgess
- WWF US, Washington, USA
- UNEP World Conservation Monitoring Centre, Cambridge, CB3 0DL UK
| | - Jon C Lovett
- School of Geography, University of Leeds, Leeds, LS2 9JT UK
| | - Antje Ahrends
- Genetics and Conservation, Royal Botantic Garden Edinburgh, Edinburgh, UK
| | - Julian Bayliss
- Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ UK
| | - Nike Doggart
- Tanzanian Forest Conservation Group, Dar es Salaam, Tanzania
| | - Kathryn Doody
- Frankfurt Zoological Society, Frankfurt, D-60316 Germany
| | - Eibleis Fanning
- The Society for Environmental Exploration, London, EC2A 3QP UK
| | | | - Jaclyn Hall
- Department of Geography, University of Florida, PO Box 117315, Gainesville, Florida FL 32611 USA
| | - Kim L Howell
- The University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Rob Marchant
- Environment Department, University of York, York, YO10 5DD UK
| | - Andrew R Marshall
- Environment Department, University of York, York, YO10 5DD UK
- Centre for the Integration of Research, Conservation and Learning, Flamingo Land Ltd, Malton, YO 17 6UX UK
| | | | | | - Nisha Owen
- The Society for Environmental Exploration, London, EC2A 3QP UK
- EDGE of Existence, Conservation Programmes, Zoological Society of London, London, UK
| | - Ruth D Swetnam
- Department of Geography, Staffordshire University, Stoke-on-Trent, ST4 2DF UK
| | | | - Simon L Lewis
- School of Geography, University of Leeds, Leeds, LS2 9JT UK
- Department of Geography, University College London, London, WC1E 6BT UK
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