Delft University of Technology, Faculty of Civil and Geosciences Engineering, Stevinweg 1, 2628 CN Delft, Netherlands.
Delft University of Technology, Faculty of Civil and Geosciences Engineering, Stevinweg 1, 2628 CN Delft, Netherlands.
Sci Total Environ. 2024 Jan 10;907:167951. doi: 10.1016/j.scitotenv.2023.167951. Epub 2023 Oct 19.
Application of biochar to landfill cover soils can purportedly improve methane (CH) 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 CH oxidation rates, and the composition of the methanotrophic community. Loose soils with and without biochar were pre-incubated to equally elevate the CH 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.
生物炭在垃圾填埋场覆盖土壤中的应用据称可以提高甲烷（CH）氧化速率，但对于土壤质地、压实度和生物炭对甲烷氧化菌活性和组成的综合影响的理解有限。本研究通过分析与甲烷氧化相关的土壤物理性质的变化、对 CH 氧化速率的影响以及甲烷氧化菌群落的组成，探讨了在三种普罗克特密度压实水平下，两种不同质地的填埋场覆盖土壤中添加木质生物炭的情况。在添加生物炭和不添加生物炭的疏松土壤中进行预培养，以同等程度提高 CH 氧化速率。此后，对土壤进行压实并重新培养。对压实土壤进行甲烷氧化速率、气体扩散率、水分保持特性和孔径分布分析。在预培养和填充样品的培养试验结束时，确定甲烷氧化菌（MOB）的相对丰度。生物炭在所有压实水平下均显著增加了孔隙度，提高了扩散系数。此外，还观察到孔径的重新分布。由于压实土壤标本的有限高度上扩散氧通量较高，低压实度和生物炭添加引起的气体扩散性增加并未反映出更高的甲烷氧化速率。所有土壤，无论是否添加生物炭，均主要由 II 型甲烷氧化菌主导。在砂质土壤中，生物炭添加强烈增加了 MOB 的丰度，这可能归因于 Methylocystis 种的相对丰度相应增加，而在粘性土壤中则没有观察到这种反应。压实度在两种土壤中均未改变群落组成。在垃圾填埋场覆盖土壤中添加木质生物炭不一定总是能增强甲烷氧化活性，从而减少逸散性甲烷排放，其效果具有土壤特异性。然而，特别是在较细和更压实的土壤中，生物炭添加可以将土壤扩散率维持在临界水平以上，防止甲烷氧化作用的崩溃。
