【作者】 裴建国；

【导师】 沈照理；

【作者基本信息】 中国地质大学(北京) ， 地下水科学与工程， 2012， 博士

【摘要】 本文在寨底地下河系统水文地质调查以及流量和水化学动态监测的基础上，分析了寨底地下河系统的特征，特别是通过水质评价和水质变化趋势的分析，总结了1983年¹984年和2008年²010年两个时段的水质演化趋势，探讨了地下河硝酸盐氮的来源，并计算了两个时段的岩溶碳汇量和碳汇通量。寨底地下河系统具有多块多层结构的特点，含水介质高度不均匀，以注入、渗漏和入渗的方式补给，仍具天然流场状态，但不具有统一的地下水动力场，而具有高度非连续水流的特点，“三水”转化频繁，动态变化大，富Ca（Mg）偏碱性环境。地下水化学类型为HCO₃—Ca型，pH值范围为7.05⁷.86。阳离子及HCO₃-总体表现为稀释效应，低值现雨季，峰值在旱季，年际变化不具有重现性。SO42与Cl-变化与人类活动关系较为密切，其含量较低，变化不大。水质评价综合分析结果显示，影响寨底地下河水质的指标主要有Pb、NO2-和Ni，集中出现在1984年和2008年，2009年²010年水质几乎全部是Ⅰ类水。从多年变化趋势分析，寨底地下河水质呈现出逐渐变好的趋势，从Ⅱ、Ⅲ类水逐渐变为Ⅰ类水。采用差值法和比值法对比分析，直观地反映了水质变化趋势，K⁺、Na⁺、Ca²⁺、Mg²⁺、Cl^-、SO₄^2-、HCO₃^-等7项常规指标中，只有Mg²⁺含量减少，其余都增加但幅度不大；微量元素中Cu、Zn、Ni、Mn的检出率较高，其余偶尔被检出，两个时段的差值＜0，比值＜1；Cu、Cd、As差值≥0，比值≥1。NO₃-、NO2-、NH₄⁺都呈增加的趋势，尤其是NO₃-普遍出现。NO₃-平均值的差值为2.28 mg/l，两个时段相差2.6倍；NO₂^-平均值的差值为0.0645mg/l，两个时段相差22.5倍，最大可达105倍。通过地下水硝酸盐氮氧同位素分析和结合土地利用方式判定寨底地下河硝酸盐来源于以动物粪便为主的厩肥的污染。δ15N值的变化范围是10.44‰～18.52‰。2008年²010年寨底地下河系统年碳汇通量为68.82 t（/km2 a）（平水年），1984年为51.56 t/（km2 a）（偏枯年）。地下河流量和HCO₃-浓度共同影响岩溶碳汇强度的大小，HCO₃-浓度与碳汇强度呈现出负相关的趋势，但不具线性关系，流量与岩溶碳汇强度具有很好的线性正相关关系。更多还原

【Abstract】 On the basis of the hydrogeological survey, flow rate and water chemistrydynamic monitoring of Zhaidi underground river system, the characteristics of Zhaidiunderground river system was analyzed in this paper, furthermore, water qualityevolution trends of two periods （1983 to 1984 and 2008 to 2011）was summarizedusing water quality evaluation method and analytical approach of water qualityvariation. The source of nitrate-N of underground river was discussed and karstcarbon sink amount and flux of the two periods also were estimated respectively.Zhaidi underground river system is characterized by multi-block and multi-layerstructure, aquifer media is highly heterogeneous, recharging by inpouring, percolatingand infiltration. It is still in the state of natural flow field without uniformhydrodynamic field. However, it is featured as a highly non-continuous flow systemwith high-frequency transferring rate of“three water”, large variation range of waterflow, Ca （Mg）-rich alkaline environment.The groundwater chemical type is HCO₃-Catype with pH ranging from 7.05 to 7.86. Cations and HCO₃-mainly were controlled bydilution effect and present low values in rainy season, high values in dry season, andirreproducible interannual variation. The contents of SO42-and Cl-are low with littlechange and has close relationship with human activities.Comprehensive analysis results of water quality evaluation show that theindicators of affecting the underground river water quality mainly include Pb, NO2-,and Ni, mostly occurredin 1984 and 2008, the water quality in 2009 to 2010 is almostall in class-I water. Years of trend analysis indicated that the water quality of Zhaidiunderground river system shows improvement gradually from class II or III to class I.Difference method and ratio method was employed to analyse the water quality trendsand good results was obtained, in which only Mg²⁺content decreases while six ofother general indicators increase at small range, including K+, Na+, Ca²⁺, Cl-, SO42-,HCO₃-; detection rates for Cu, Zn, Ni, Mn is high, the rest of trace elements are occasionally been detected, the difference value between the two periods is less thanzero, the ratio is smaller than one; and the difference value for Cu, Cd, As is largerthan or equal to zaro, and the ratio is greater than or equal to one.NO₃^-, NO₂^-and NH4+present an increasing trend. The mean value difference ofNO₃-is 2.28mg/l with 2.6 timesdifference between two periods is; the mean valuedifference of NO2-is 0.0645mg/l with 22.5 times difference between two periods,maxima up to 105 times. Nitrate source of Zhaidi underground river wass determinedbased on the analysis of groundwater nitrate nitrogen and oxygen isotope and land usepatterns, it mainly comes from manure pollution（animal waste）.δ15N values rangefrom 10.44‰to 18.52‰.The carbon sink fluxes of the Zhaidi underground river system in years of2008-2010 and 1984 were estimated to be 68.82 t/km2·a （normal year） and51.56t/km2·a （dry year） respectively. The size of karst carbon sink intensity isinfluenced by bothunderground river flow and [HCO₃-]concentration.The [HCO₃-]concentration and the carbon sink intensity showed a negative correlation trend（non-linear relationship）. Karst carbon sink intensity has a good linear correlationrelationship with water flow.更多还原