基于氚和CFCs的三江平原浅层地下水更新能力估算

论文通过对三江平原浅层地下水年龄的测定,研究了地下水的来源与更新能力。在井深小于60 m的钻孔中,采集了11 组浅层地下水样,分别测定水中放射性同位素氚(T)和氟利昂(CFCs),根据活塞模型,分别计算出浅层地下水的年龄。分析结果表明,三江平原浅层地下水中氚同位素含量为1.7~61.2 TU;CFC-12 和CFC-113 浓度分别是0.04~1.25 pmol·kg^-1 和0.1~0.71 pmol·kg^-1。根据氚同位素含量估算的浅层地下水年龄范围是39~51 a;CFC-12 浓度估算的浅层地下水年龄范围为38.2~61.7 a。两种测年数据都表明,浅层地下水缺失了0~39 a 的年轻水,这暗示三江平原的地下水主要接受外源水的补给,深循环地下水越流补给地表水并形成湿地,最终补给到河流之中,地下水有稳定的补给源,可以适当地进行开发和利用。

Estimation of Groundwater Renewal Rate by Tritium and Chlorofluorocarbons in Sanjiang Plain

The groundwater renewal ability is the basis for the rational development and utilization of groundwater resources, as well as the important factor to the grain production in Sanjiang Plain. The analyses of the shallow groundwater ages were conducted to study the recharge source of the groundwater and the renewable ability during 10th-17th, September 2009. There are 11 shallow groundwater samples were collected from the less than 60 m deep wells along Heilongjiang River, Songhua River and Wusuli River. The shallow groundwater samples were analyzed for concentrations of tritium (T) and chlorofluorocarbons (CFCs) by Quantulus 1220 and GC-ECD, respectively. The groundwater ages were calculated by the tritium and CFCs contents with piston flow model, respectively. The results show that the tritium content in shallow groundwater ranged from 1.7-61.2 TU. While, the CFC-12 and CFC-113 concentrations ranged from 0.04-1.25 pmol·kg^-1 and 0.1-0.71 pmol·kg^-1, respectively. The shallow groundwater age ranged from 39-51 years according to the contents of tritium. Meanwhile, the CFC-12 apparent groundwater age ranged from 38.2-61.7 years. The shallow groundwater with age less than 39 years was missing according to the tritium and CFCs data, indicating that the groundwater mainly recharged from the allogenic water in Sanjiang Plain. The percolating water from the water deep circulation recharges the surface water, forms to the wetland, and discharges to river finally. The groundwater table monitoring data shows that the groundwater table was the least in June since the agricultural irrigation. However, the groundwater table increased to the elevation before irrigation in September. The groundwater renewable ability also shows that there is stable recharge source in Sanjiang Plain. Consequently, the groundwater could be explored and utilized appropriately to increase the farmland, and to enhance the sustainable agricultural development in Sanjiang Plain.