应用~2H、^(18)O同位素示踪华北平原石家庄包气带土壤水入渗补给及年补给量确定

Tracing Infiltration and Recharge of the Unsaturated Zone Using ~2H,^(18)O Isotopes in Shijiazhuang,North China Plain

采集2个不同深度包气带土壤水2 H、18 O同位素剖面ZK1,ZK2,应用天然稳定同位素2 H、18 O示踪的方法,研究了华北山前冲积平原石家庄地区包气带土壤水入渗补给的历史演化特征。结果显示,研究区内,以0.05m为取样间隔,δ2 H、δ18 O值可以明显指示出大气降水及灌溉水入渗补给时间—剖面深度位置的年际对应关系。ZK2的δ2 H、δ18 O值随着埋深的增大出现周期性的波动,具有分层现象的岩性差异并不明显,说明ZK2剖面以活塞流的入渗方式补给地下水。在0~3.90m深度,δ2 H、δ18 O值显示降水和灌溉水的入渗补给时间为2011年10月至2001年11月。18 O峰值位移法计算补给量的结果显示,降水、灌溉水通过包气带补给地下水的垂向运移速度为38.5~65.0cm/a,年均入渗补给量为131.3~185.3mm。同时,对比2003年及2005-2007年降水量数据,说明少雨年份农业灌溉用水量的大小对当地地下水的入渗补给量起着关键性作用。

The natural stable isotopes are used to trace the characteristics of historical infiltration and recharge evolution, and two unsaturated profiles of δ^2H, δ^18O soil water were employed in Shijiazhuang, North China Alluvial Plain. The results show that the time scale of the profile records of the precipitation and irrigation percolating water are remarkable by the δ^62H, δ^18O of the unsaturated zone water at an interval of 0.05 m. The δ^2H,δ^18O cyclical fluctuation of the ZK2 profile and the diversity of layering soil texture both indicate the piston flow. The percolating time of the precipitation and irrigation covers the duration from October, 2011 to November, 2001 （corresponding to depths from 0 to 3.90m） by the δ^2H, δ^18O profile. The annual mean migration velocity, recharge and recharge rate are 38.5-65.0 cm/a, 131.3- 185.3 mm respectively calculated by the 180 isotopes displacement method. Moreover, comparison of the precipitation of 2003 and 2005-2007 indicates that the amount of irrigation plays a key role in the local infiltration recharge.