摘要:
提要: 文章通过80组不同地热田的样品, 分析总结了北京地区地热水资源氘过量参数的特征: (1)地热水的平均δ值为5.4, 常温地下水的平均d值为6.04, 热水的d值与氚值都较低, 水岩作用所导致的氧同位素交换比冷水更容易进行; (2)地下热水的氢和氧同位素组成具有明显的热交换趋势, d值随地下水年龄增大而递增, 当地热水年龄为(12.76±0.13) ka时, d值为11.2, 而当地热水年龄为(38.96±0.63) ka, d值为14.6; (3)在同一地区, d值随着地下水埋深加大而减小, 埋深为125.13 m时d值为5.72, 埋深为3221 m时, d值为3.03; (4)从补给源到排泄区, 地下水的d值应逐渐降低, 其中北部补给区平均d值为7.31, 北京断陷盆地平均d值为5.68, 南部凤河营地区仅为-9.20; 补给源区与排泄区水的d的差值越大, 地下水的运动速度越慢; (5)当Eh小于200 mV时, 北京地区地下热水的d值随着Eh值的降低而减少, 如在桐热-7中, 氧化还原电位为-326 mV, d值为-9.20, 而在TR-43中氧化还原电位为158 mV, d值为7.48; 当Eh大于200 mV时, 地下热水的d值随着Eh值的降低而增加, 但增幅较小。
Abstract:
Abstract: Eighty water samples were collected from different geothermal fields in Beijing and the following five kinds of characteristics of deuterium excess parameters were analyzed: (1) The average d value of geothermal water is 5.40, the average d value of cold groundwater is 6.04, which is bigger than that of the geothermal water, so the oxygen isotope exchange caused by water?rock interaction is easier in geothermal water than in cold groundwater. (2) The oxygen isotope has remarkable isotope exchange process, and the d value increases with the age of the geothermal groundwater. When the age of the water is (12.76±0.13) ka, the d value is 11.2; when the age of the water is (38.96±0.63) ka, the d value is 14.6. (3) The d value decreases with the depth of the geothermal groundwater in the same area; when the depth is 3221 m, the d value is 3.03; when the depth is 125.13 m, the d value is 5.72. (4) The d value decreases from the recharge area to the discharge area. The average d value is 7.31 in northern recharge area, 5.68 in Beijing depression, and ?9.20 at the southern edge of Beijing plain. The velocity of flow decreases with the difference d values. (5) The d value increases with the redox potential when it is smaller than 200 mV. When the redox potential is ?326 mV, the d value is ?9.20; when the redox potential is 158 mV, the d value is 7.48. The d value decreases with the redox potential when it is bigger than 200 mV.
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