气候变化领域集成服务门户(CCPortal): The effect of water repellency on the short-term release of CO2 upon soil wetting

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DOI	10.1016/j.geoderma.2020.114481
	The effect of water repellency on the short-term release of CO2 upon soil wetting
	Sánchez-García C.; Doerr S.H.; Urbanek E.
发表日期	2020
ISSN	167061
卷号	375
英文摘要	The spike in carbon dioxide (CO2) observed after rewetting of dry soils, known as the ‘Birch effect’, can contribute substantially to total soil carbon (C) emissions, however, the exact mechanisms and timings underlying this sudden CO2 release remain unclear. The amount of applied water and duration of the previous dry period are considered the main factors affecting the magnitude of the CO2 peak, but the preceding change in soil wettability, triggered by low soil water content, could also be an important contributor. We investigated the effect of soil water repellency (SWR, assessed by water drop penetration time test) on the short-term release of CO2 upon wetting of dry soils with different water quantities. The experiments were conducted under laboratory conditions using homogeneous and autoclaved soil from two locations in South Wales (UK) in both wettable and extremely water-repellent states. The CO2 efflux was measured using chambers above and below the samples. Upon wetting, CO2 efflux was up to 10 times lower in water-repellent soils as a result of rapid percolation through preferential pathways, with only a small amount of water (up to 10%) retained in the soil. Total CO2 efflux was proportional to the water retained in the soil after infiltration, suggesting that the release of CO2 occurred only from limited pore-spaces of the soil. The quick CO2 release suggests that chemical or biochemical processes, rather than microbial respiration, is the main source of CO2 efflux in this study. Part of the CO2 released was transported to the bottom chamber, which under natural conditions could enhance the entrapment of gas in the subsoil. This study shows that alterations in the water-filled pore-space as a result of SWR significantly reduced the CO2 efflux upon wetting and suggests that SWR could be a key factor when investigating and predicting C fluxes. © 2020 Elsevier B.V.
英文关键词	Birch effect; C emissions; CO2 pulse; Hydrophobicity; Rain pulses; Soil degassing
scopus关键词	Soil moisture; Solvents; Waterproofing; Wetting; Biochemical process; Laboratory conditions; Microbial respiration; Preferential pathways; Soil water repellency; Water drop penetration time; Water repellent soils; Water-filled pore space; Carbon dioxide; carbon dioxide; carbon flux; soil carbon; soil water; subsoil; wetting; South Wales; United Kingdom; Wales
来源期刊	Geoderma
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/176794
作者单位	Department of Geography, Swansea University, Swansea, United Kingdom
推荐引用方式 GB/T 7714	Sánchez-García C.,Doerr S.H.,Urbanek E.. The effect of water repellency on the short-term release of CO2 upon soil wetting[J],2020,375.
APA	Sánchez-García C.,Doerr S.H.,&Urbanek E..(2020).The effect of water repellency on the short-term release of CO2 upon soil wetting.Geoderma,375.
MLA	Sánchez-García C.,et al."The effect of water repellency on the short-term release of CO2 upon soil wetting".Geoderma 375(2020).