可可西里土壤凝结水形成特征及其影响因素研究

青藏高原受气候变化影响，干湿过渡状况不断扩大，凝结水是旱区重要的水分补给来源，研究凝结水对青藏高原生态具有重要意义。为探究凝结水在青藏高原的形成特征以及影响凝结水形成因素，选取近年来受气候影响较大的可可西里盐湖地区作为研究区，使用微型蒸渗仪探究其0~10 cm土壤水分蒸发凝结特征，并利用相关回归分析、主成分分析探究影响凝结水形成因素。结果表明：（1） 在14:00—次日14:00期间，气温和土层温度均呈现出先减小后增大的变化趋势，0~10 cm土壤在00:00—10:00内有明显土壤凝结水形成，而在其余时间水量蒸发明显。大气水汽和土壤深层水汽组成土壤凝结水的比例约为1:3。当夜间近地空气相对湿度大于64%，近地气温小于3.8 ℃，5 cm土层温度低于4.1 ℃，有利于土壤凝结水的形成，平均水量可达0.2 mm·d^-1。（2） 相关分析表明土壤总凝结水量与5 cm土层温度和5~30 cm土层温度差呈显著负相关，而且凝结水量与相关因子的线性拟合效果较好；大气水汽凝结水量与气温呈现显著负相关，与相对湿度呈现显著正相关。主成分分析结果显示0~10 cm以上土层微气象因子对凝结水形成因素较大。

Formation characteristics and factors effecting of condensation waterin surface soil in Hoh Xil area

Caused by climate change, the Qinghai-Tibet Plateau has continuously expanded the transition between dry and wet conditions, and the phenomenon of ecological degradation has increased. Condensation water is an important water resource in arid regions. In order to explore the formation characteristics and influencing factors of condensation water on the Qinghai-Tibet Plateau, this study selected Yanhu (Salt lake) district at the Hoh Xil area that has been greatly affected by climate in recent years, micro lysimeters were used to weigh the 0-10 cm soil to explore the evaporation and condensation characteristics of surface soil moisture. Besides, used multivariate statistical methods to analyze the relationship between condensation water and micro-meteorological factors, such as one-way analysis of variance, correlation analysis and principal component analysis. The results showed that: (1) During the period from 14:00 to 14:00 the next day, both the air temperature and the soil layer temperature showed a trend of first decreasing and then increasing. The 0-10 cm soil had obvious soil condensate formation from 00:00 to 10:00, but the soil water evaporated significantly in the other period. The soil condensation water was mainly composed of atmospheric water vapor and deep soil water vapor, with a ratio of about 1:3. We found that the conditions for the occurrence of soil condensation water were as follows: the relative humidity of the air at night was greater than 64%, the air temperature was less than 3.8 ℃, and the temperature of the 5 cm soil layer was less than 4.1 ℃, it was conducive to the formation of condensation water, and the average water volume could reach 0.2 mm·d^-1. (2) Correlation analysis showed that the total amount of soil condensed water was significantly negatively correlated with the temperature of the 5 cm soil layer and the soil temperature difference between 5 cm and 30 cm, and the linear regression effect between the amount of condensation water and related factors was good; There was a significant negative correlation between the amount and air temperature, and a significant positive correlation with relative humidity. The results of principal component analysis showed that the amount of condensation water was closely related to micro-meteorological factors, especially the micro-meteorological factors above 10 cm soil layer. This research could provide a certain scientific basis for the reasonable estimation of ecological water volume and vegetation restoration in the Yanhu district.