石家庄市区土壤水分运移的稳定同位素特征分析

Stable Isotopes Characters of Soil Water Movement in Shijiazhuang City

根据2013年4月到2014年5月测得的石家庄市区降水和2013年石家庄市雨季土壤水、灌溉水的稳定氢氧同位素,通过稳定同位素示踪的方法从时间和空间的角度分析了不同土壤层位中的稳定同位素的变化规律,进而得出土壤的水分迁移过程.结果表明,过量氘均值为-6.188 5‰,反映了石家庄2013~2014年的年降水主要来自季风带来的海洋水汽,同时有一定的局地蒸发.石家庄土壤水的来源主要是降水,灌溉水在雨季前期有辅助作用,且雨季的降水量足以对土壤进行适当补给.10~100 cm土壤水的δ18O值随深度增大而减小,雨季最大蒸发深度在40 cm左右,取样期间基本上形成了一个土壤水δ18O峰值沿剖面徘徊中不断向下推进的情况,反映了降水的入渗、蒸发和新旧水的混合的相互作用.

In this study,we analyzed the stable hydrogen and oxygen isotope values of precipitation,soil water,irrigation water that collected in Shijiazhuang City from April 2013 to May 2014 to investigate the changing rule of the stable isotopes in different soil profiles and the process of soil water movement according to using the isotope tracer technique. The results showed that the mean excess deuterium of the local precipitation was- 6. 188 5‰. Those reflected that the precipitation in Shijiazhuang City mainly brought by the monsoon from the ocean surface moisture,and also to some extent by the local evaporation. Precipitation was the main source of the soil water and the irrigation water played the supplementary role. In the rainy season,precipitation was enough to supply the soil water. The stable oxygen isotopes at 10-100 cm depth decreased with the increase of depth,the maximum depth of evaporation in the rainy season reached 40 cm. The peak of stable oxygen isotopes of soil water pushed down along the profile,which was infected by the interaction of the precipitation infiltration,evaporation and the mixing water.