文献类型：期刊文献

英文题名：A method to estimate the water vapour enhancement factor in soil

作者：Lu, S.[2] Ren, T.[1] Yu, Z.[3] Horton, R.[4]

第一作者：陆森

通信作者：Ren, T[1]

机构：[1]China Agr Univ, Dept Soil & Water Sci, Beijing 100193, Peoples R China;[2]Chinese Acad Forestry, Key Lab Tree Breeding & Cultivat, State Forestry Adm, Res Inst Forestry, Beijing 100091, Peoples R China;[3]China Agr Univ, Dept Ecol Sci & Engn, Beijing 100193, Peoples R China;[4]Iowa State Univ, Dept Agron, Ames, IA 50011 USA

年份：2011

卷号：62

期号：4

起止页码：498-504

外文期刊名：EUROPEAN JOURNAL OF SOIL SCIENCE

收录：;Scopus(收录号：2-s2.0-79960465708);WOS:【SCI-EXPANDED(收录号:WOS:000292862000002)】；

基金：This research was supported by the Natural Science Foundation of China (No. 40901108), the National Key Technology R&D Program of China (No. 2011BAD38B06), and the China Postdoctoral Science Foundation (No. 201003187).

语种：英文

摘要：Enhanced water vapour diffusion under temperature gradients has been proposed as a mechanism to explain the discrepancies between measured and predicted water fluxes in soils. Because of the difficulties in measuring soil vapour diffusion directly, modelling approaches have been used to estimate the vapour enhancement factor (eta) by matching theory to measurements. In the method proposed by Hiraiwa & Kasubuchi (2000), soil thermal conductivity associated with conduction heat transfer (lambda(c)) is assumed to be equal to the apparent soil thermal conductivity (lambda) measured at a low temperature, and eta is significantly under-estimated. In the present study, an improved approach for estimating eta is used, in which lambda(c) is taken as the apparent soil thermal conductivity associated with infinite atmospheric pressure. The lambda at infinite atmospheric pressure is estimated by extrapolating lambda measurements made at finite air pressures. By subtracting lambda(c) from measured lambda values at a given atmospheric pressure, the contribution of thermal vapour diffusion to heat transfer (lambda(v)) is obtained and then used to estimate eta. In the case of a lysimeter sand, lambda(v) accounts for 4-25, 8-29 and 13-35% of lambda at 3.5, 22.5 and 32.5 degrees C, respectively, at soil water contents greater than 0.02 m(3) m(-3). Thus, the latent heat transfer through vapour diffusion is important even at temperatures as low as 3.5 degrees C. The agreement between predictions from the new method and selected literature values suggests that the improved approach is able to provide accurate estimate of eta. The results from this study show that the magnitude of latent heat transfer resulting from thermal vapour diffusion is strongly soil texture-dependent. Thus, it is important to estimate eta on specific soils rather than assuming eta from literature values.