高寒沙区吸湿凝结水凝结过程与温湿度的关系

Relationship between the Condensation Process of Hygroscopic and Condensate Water and the Air & Soil Humiture in Alpine Sandy Lands

吸湿凝结水作为干旱半干旱地区除降雨外主要的水分来源,具有十分重要的生态水文学意义。以青海共和盆地高寒沙区1997年植被恢复区生物土壤结皮吸湿凝结水为研究对象,2018年5-9月采用自制微渗仪观测吸湿凝结水量,同时观测近地层空气温湿度和土壤温湿度。结果表明:观测期间,不同类型结皮吸湿凝结水量存在差异,表现为苔藓结皮>藻类结皮>物理结皮>流沙,且差异性与观测时间无关;吸湿凝结水量与近地层空气湿度正相关,与近地层空气温度、土壤温度湿度负相关,且相关性与地表类型无关;吸湿水凝结过程主要受近地层空气温湿度的影响,累积贡献率85.294%;生长季吸湿凝结水主要产生时间为19:00至次日07:00,期间凝结速率呈波动性变化;19:00-23:00吸湿凝结水凝结速率不断上升,且上升趋势与近地层空气温湿度无关;00:00-03:00吸湿凝结水凝结速率出现滞后效应,滞后于近地层空气温湿度变化1 h;04:00-07:00呈先升高后降低趋势,04:00出现该时间段凝结速率最低值,05:00出现该时间段凝结速率的最高值。

Expect for the rainfall, hygroscopic and condensate water as the main source of moisture in arid and semi-arid regions, has great significance for eco-hydrology. In this experiment, the contents of hygroscopic and condensate water in biological soil crusts in alpine sandy artificial vegetation restoration area of Gonghe basin were set as the research object. We used micro-lysimeters to observe hygroscopic and condensate water in alpine sandy lands from May to September in 2018, recorded the change rule of air humiture and soil humiture in the meantime. The results showed that hygroscopic and condensate water in different types of biological soil crust were different: moss crusts>algae crusts>physical crusts>sand, and the difference was not related to the date. The relationship between near-surface air humidity and the contents of hygroscopic and condensate water was positively correlated. And the relationship between near-surface air temperature, soil temperature, soil humidity and the contents of hygroscopic and condensate water was negative, and the correlation was not related to surface types. The main component analysis showed that the condensation process of hygroscopic and condensate water was mainly affected by near-surface air temperature and humidity, and the cumulative contribution rate was 85.294%. The main generation time of hygroscopic and condensate water in growing season was 19 o’clock to 7 o’clock the next day, during this period, the changes of condensation speed was volatile. The speed of hygroscopic and condensate water rose constantly at 19 o’clock to 23 o’clock, and the rising trend was unconnected with near-surface air temperature and humidity. At 0 o’clock to 3 o’clock, the speed of hygroscopic and condensate water appeared hysteretic effect, and it lagged one hour behind the change in atmospheric humiture. The tendency to go up and down at 4 o’clock to 7 o’clock, and the peak speed of hygroscopic and condensate water appeared at 5 o’clock, the lowest speed of hygroscopic and condensate water appeared at 4 o’clock.