深埋地热水中三氮分布特征及其影响因素研究

Distribution and analysis of factors influencing three nitrogen compounds of the ultra-deep geothermal water

为有效控制深埋地热水中三氮污染,并为合理开发地热水资源提供理论依据,基于开封市城区44眼地热井(埋深为600~1 800m)的理化指标,绘制了三氮在各含水层中的浓度等值线图,研究了开封市地热水中三氮空间分布规律及其影响因素。研究结果表明:以《地下水质量标准》(GB/T 14848—93)的Ⅲ类水质要求为评价标准,开封市埋深为600~1 800m的地热水中,三氮污染以亚硝酸盐氮为主,硝酸盐氮与氨氮污染较轻;亚硝酸盐氮超标区主要分布在开封市火车站附近,其分布规律是发生不同程度硝化/反硝化作用的结果;除个别取样点外,各含水层中硝酸盐氮和氨氮的浓度均较低。相关分析结果表明,亚硝酸盐氮与硝酸盐氮显著相关,氨氮与pH显著相关,进一步证实了三氮浓度分布与硝化/反硝化作用有关。

To control the three nitrogen compounds pollution of ultra-deep geothermal water effectively and provide theoretical basis for rational development of geothermal water resources, physical and chemical indicators of 44 geothermal wells with depth of 600-1 800 m in the area of Kaifeng City were analyzed, and the spatial distribution characteristics and influencing faetors of three nitrogen compounds in the geothermal water were studied based on contour map of three nitrogen eompounds eoncentration in eaeh aquifer. The results showed that the geothermal wells with depths of 600-1 800 m were mainly polluted by nitrite. The pollution of ammonia nitrogen and nitrate was light. Based on Grade Ⅲ of ＂Quality standard for ground water＂ （GB/T 14848-93） ,the nitrite concentration in each aquifer exceeded standard, mainly distributed in the region near the railway station, which was contributed by nitrification/ denitrification process. However,ammonia nitrogen and nitrate concentration of each aquifer in the whole research area showed low values except individual sample points. According to correlation analysis, nitrite and nitrate concentration were significantly related,and ammonia nitrogen concentration and pH were also in significant correlation. The relationship between the distribution of the three nitrogen compounds and nitrification,as well as denitrification,were confirmed further.