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Yi SC, Heijbroek A, Cutz L, Pillay S, de Jong W, Abeel T, Gebert J. Effects of fir-wood biochar on CH 4 oxidation rates and methanotrophs in landfill cover soils packed at three different proctor compaction levels. Sci Total Environ 2024; 907:167951. [PMID: 37865253 DOI: 10.1016/j.scitotenv.2023.167951] [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: 06/12/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 10/23/2023]
Abstract
Application of biochar to landfill cover soils can purportedly improve methane (CH4) oxidation rates, but understanding the combined effects of soil texture, compaction, and biochar on the activity and composition of the methanotrophs is limited. The amendment of wood biochar on two differently textured landfill cover soils at three compaction levels of the Proctor density was explored by analyzing changes in soil physical properties relevant to methane oxidation, the effects on CH4 oxidation rates, and the composition of the methanotrophic community. Loose soils with and without biochar were pre-incubated to equally elevate the CH4 oxidation rates. Hereafter, soils were compacted and re-incubated. Methane oxidation rates, gas diffusivity, water retention characteristics, and pore size distribution were analyzed on the compacted soils. The relative abundance of methanotrophic bacteria (MOB) was determined at the end of both the pre-incubation and incubation tests of the packed samples. Biochar significantly increased porosity at all compaction levels, enhancing diffusion coefficients. Also, a re-distribution in pore sizes was observed. Increased gas diffusivity from low compaction and amendment of biochar, though, did not reflect higher methane oxidation rates due to high diffusive oxygen fluxes over the limited height of the compacted soil specimens. All soils, with and without biochar, were strongly dominated by Type II methanotrophs. In the sandy soil, biochar amendment strongly increased MOB abundance, which could be attributed to a corresponding increase in the relative abundance of Methylocystis species, while no such response was observed in the clayey soil. Compaction did not change the community composition in either soil. Fir-wood biochar addition to landfill cover soils may not always enhance methanotrophic activity and hence reduce fugitive methane emissions, with the effect being soil-specific. However, especially in finer and more compacted soils, biochar amendment can maintain soil diffusivity above a critical level, preventing the collapse of methanotrophy.
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Affiliation(s)
- Susan C Yi
- Delft University of Technology, Faculty of Civil and Geosciences Engineering, Stevinweg 1, 2628 CN Delft, Netherlands.
| | - Anne Heijbroek
- Delft University of Technology, Faculty of Civil and Geosciences Engineering, Stevinweg 1, 2628 CN Delft, Netherlands
| | - Luis Cutz
- Delft University of Technology, Faculty of Mechanical, Maritime and Materials Engineering, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
| | - Stephanie Pillay
- Delft University of Technology, Faculty of Electrical Engineering, Mathematics and Computer Science, Van Mourik Broekmanweg 6, 2628 XE Delft, Netherlands
| | - Wiebren de Jong
- Delft University of Technology, Faculty of Mechanical, Maritime and Materials Engineering, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
| | - Thomas Abeel
- Delft University of Technology, Faculty of Electrical Engineering, Mathematics and Computer Science, Van Mourik Broekmanweg 6, 2628 XE Delft, Netherlands; Broad Institute of MIT and Harvard, Infectious Disease and Microbiome Program, 415 Main St., Cambridge, MA 02142, USA
| | - Julia Gebert
- Delft University of Technology, Faculty of Civil and Geosciences Engineering, Stevinweg 1, 2628 CN Delft, Netherlands
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