摘要
湿筛法是测定土壤团聚体粒径分布和稳定性的经典方法。土样在湿润过程中,同时发生了崩解、差异膨胀和物理-化学分散作用。已有的湿润方法按湿润速度可分为快速湿润和慢速湿润,按土样所处的气压条件可分为常压湿润和高真空湿润。常压快速湿润过程中,水分沿毛管快速渗入土体,土壤内部封闭的空气被压缩,产生微型爆炸,对团聚体破坏较大;慢速湿润和真空湿润能使团聚体稳定性显著增大。如果是为全面了解土壤团聚体稳定性及粒径分布的信息,可对土样采用常压快速湿润和常压慢速湿润(或真空湿润)2种预湿润。湿筛的作用在于区分不同粒级的土壤颗粒,应尽量减小对团聚体颗粒进一步的磨蚀作用,因此湿筛过程中振动速度不能太快。筛目可以根据实验目的选择。
Wet-sieving method is a classical and still the most prevalent procedure for testing the water stability of soil aggregates.Three main mechanisms are attributed to the breakdown of soil aggregates during wetting including slaking（breakdown caused by the compression of entrapped air in the soil pores）,differential swelling and physic-chemical dispersion.The existing wetting methods can be divided into fast wetting and slow wetting according to the velocity of wetting,and atmospheric pressure wetting and high-vacuum wetting according to the barometric condition of soil sample when wetting.When soil samples are fast wetted under atmospheric pressure,water penetrates the soil mass at a high rate along capillaries,and compressing entrapped air causes a series of miniature explosions and breaks down soil aggregates,while wetting soil samples slowly or in vacuum gives high aggregation.In order to investigate the soil aggregate size distribution and water-stability comprehensively,it is recommended that fast wetting under atmospheric pressure and slow wetting（or wetting in vacuum） should be taken respectively with equivalent soil samples.During wet-sieving,the sieves should not shake too rapidly,and the number and aperture of sieves can be selected according to analytical purpose.
出处
《中国水土保持科学》
CSCD
2011年第3期106-113,共8页
Science of Soil and Water Conservation
基金
国家重点基础研究发展计划课题(2007CB407204)
北京师范大学优秀博士学位论文培育基金项目(08022)
关键词
土壤团聚体
水稳性
粒径分布
湿筛法
soil aggregates
water-stability
aggregate size distribution
wet-sieving
