黄土高原干旱半干旱区生物结皮覆盖土壤水汽吸附与凝结特征  

Characteristics of water vapor sorption and condensation in biocrusts covered surface soil in arid and semiarid areas of the Loess Plateau,China

作　　者：李胜龙 肖波 孙福海[1,2] Li Shenglong;Xiao Bo;Sun Fuhai(College of Land Science and Technology,China Agricultural University,Beijing 100193,China;Key Laboratory of Arable Land Conservation(North China),Ministry of Agriculture and Rural Affairs,Beijing 100193,China;State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,Institute of Soil and Water Conservation,Chinese Academy of Sciences,Yangling 712100,China)

机构地区：[1]中国农业大学土地科学与技术学院,北京100193 [2]农业农村部华北耕地保育重点实验室,北京100193 [3]中国科学院水土保持研究所黄土高原土壤侵蚀与旱地农业国家重点实验室,杨凌712100

出　　处：《农业工程学报》2020年第15期111-119,共9页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金(41671221);中国科学院“西部引进人才”项目(2019)。

摘　　要：生物结皮是一种广泛分布于干旱半干旱地区土壤表层的特殊复合体,为揭示其对土壤水汽吸附与凝结过程的影响,该研究通过室内定量水汽吸附试验和野外对水汽凝结的连续观测,对黄土高原典型生物结皮(藻结皮、藻藓混生结皮、藓结皮)与裸沙的水汽吸附和凝结特征进行对比研究。结果表明:生物结皮的覆盖显著提升了表层土壤的水汽吸附能力,其平均水汽吸附量比裸沙高66.7%。不同类型生物结皮水汽吸附能力差异显著,表现为藓结皮最高,混生结皮次之,而藻结皮最低。GAB(Guggenheim-Anderson-de Boer)吸附模型能较好的描述生物结皮土壤水汽吸附与解吸附过程,模拟结果决定系数R2>0.99、均方根误差RMSE<0.001 2 g/g及平均相对偏差百分比E<16.0%;此外,生物结皮加剧了土壤水汽吸附与解吸附曲线之间的滞后效应,其滞后指数平均是裸沙的2.0~2.9倍。水汽凝结结果显示,水汽凝结过程均受气温与相对湿度等气象因子制约,且生物结皮覆盖下表层土壤的水汽凝结和蒸发过程相较于裸沙更为迅速。同时,生物结皮的日均水汽凝结量是裸沙的1.6~1.8倍。综上,干旱和半干旱地区生物结皮覆盖显著提高了表层土壤的水汽吸附能力、并增加了水汽凝结量,对区域表层土壤的水分运动过程产生了重要影响。Water vapor movement is one of the several important components of total(hydrological)water flux in the vadosezone of drylands.When the soil water content is relatively low,the vapor sorption and condensation naturally become vitalwater sources for plants,insects,and small animals,particularly in arid andsemiarid drylandswith quite small rainfall.Biocrusts(biological soil crusts)covera large portion of the terrestrial soil surface of drylands,and they greatly changesurface soil water and heat movement through regulating the energy balance of surface soil.However,the influences of the critical upper layerof soil,biocrusts,on water vapor sorption and condensation have not yet been fully understood.Therefore,it is necessary toinvestigate the characteristics of water vapor sorption and condensation in biocrustsand their influential factors to quantifyvapor water supplement from biocrusts,for a better understanding of biocrust effects on vapor movement in drylands.This studywas conducted to explore the essential features of vapor sorption andcondensation in cyanobacteria crusts(cyano-crusts),cyanobacteria and moss mixed crusts(mixed crusts),moss crusts(more than 30 yrs),and bare sand(aeolian sand).Anautomatic measurement was performed to analyze the vapor sorption(adsorption and desorption directions)of biocrusts and bare sand in laboratory,and a field measurement was implementedtomeasure the vapor condensationof the different treatment,including the condensation process and daily amount of vaporcondensation.The results showedthat the vapor sorption amount increased with the water activity(aw),and the biocrusts significantly increased vapor sorptionamount as compared withthe bare sand.The vapor sorption amount of the biocrusts was averagely 66.7%higher than thatof the bare sand;and as an example,that of the moss crusts was 1.0-2.2 times higher than that of bare sand.The simulation results implied that the GAB(Guggenheim-Anderson-de Boer)model was capable ofdescripting vapor sorption isotherms of the biocrusts,with R2>

关 键 词：土壤 水分 水汽吸附量 GAB模型 凝结水 微型蒸渗仪 黄土高原 

分 类 号：S152.7[农业科学—土壤学] S157.1[农业科学—农业基础科学]