【作者】 徐彦泽；

【导师】 陈鸿汉；

【作者基本信息】 中国地质大学（北京） ， 环境工程， 2009， 博士

【摘要】 沧州市是河北平原淡水资源最为紧缺的城市之一,人均水资源占有量约192m3,仅占全国人均占有量的8%。如何合理开发利用地下淡水资源和改造地下咸水资源,成为满足当地供水和水资源管理需求的重点关注问题。本文在历史地理、古气候变化和环境影响分析的基础上,结合水文地球化学和稳定同位素方法,从多学科角度综合研究了沧州市浅层地下水盐分溶质演化过程以及地下水补给来源和分层关系。沧州市浅层地下水水位动态分析、主要离子对比、可溶盐化学平衡以及饱和指数计算等研究表明,在干季和湿季交替作用下,地面和饱气带中易溶盐处于不断的沉淀—溶解循环过程中。旱季,水分完全蒸发,矿物全部沉淀;雨季和灌溉季节,有选择性地把溶解能力强的可溶盐优先溶解到水中,排除了海水组分来源,而难溶的碳酸盐类矿物易于形成胶结物,保留在土壤层和包气带中。将沧州市当地浅层地下水(井深5~15m)的氢氧稳定同位素值与石家庄降水的氢氧稳定同位素加权平均值(IAEA)和格陵兰冰芯相对比,认为这些浅层地下水的δ2H值(-60~-55‰)和δ18O值(-8.4~-7.9‰)可代表当地全新世降水补给的氢氧同位素特征值。同时,当地水样14C数据估算和格陵兰冰芯对比结果判定,深层地下水(井深300~450m)的δ2H值(-76~-72‰)和δ18O值(-10.7~-10.1‰)可看作是晚更新世冰期古水补给,地下水滞留时间距今2.56~6万年。其他浅层地下水(井深10~50m)样点的δ2H值(-69~-59‰)和δ18O值(-9.6~-8.2‰)明显低于全新世降水补给的氢氧稳定同位素值,结合当地水文地质条件和历史地理状况,认为该层地下水主要为全新世黄河河水补给。因此,本次研究所取得的氢氧稳定同位素数据可将沧州市采样点的地下水划分为三组:(1)埋深5~15m的7件样品为当地全新世降水补给,(2)埋深10~50m的9件样品以全新世黄河河水补给为主,和(3)埋深300~450m的5件样品为晚更新世冰期古水。主要离子关系和卤族元素分析进一步从溶质角度论证了上述三组地下水入渗环境的异同,有效地避免了单一应用稳定同位素方法的多解性。本文综合应用了地下水动力学以及水文地球化学和氢氧稳定同位素等多种示踪方法,并充分考虑了古气候变化、当地历史地理条件和环境影响状况对沧州市地下水环境的影响。研究结论相辅相成,互相佐证,弥补了单一研究方法可能存在不足,对于认识当地地下水补给来源和地下水咸化过程具有理论指导意义,同时也为地下水资源的开发利用和咸水改造提供了充分的科学依据。更多还原

【Abstract】 Cangzhou is one of the most water-scarce cities in Hebei Plain,where amount per capita of water resources is 192m3, only 8% of the national average level. Therefore, it is of great importance to consider how to reasonably exploit the fresh groundwater and to desalinate the saline groundwater to satisfy water resources management.The dissertation presents a comprehensive study on the evolution of salt solute in shallow groundwater as well as the recharge source of the aquifer system and its stratification in Cangzhou, by employing multidisciplinary methods integrated with historical geography, paleoclimate change and environmental impact analysis based on geochemistry and stable isotope technology.Dynamic water-level, main ions relation, soluble salt chemical equilibrium and saturated indexes of shallow groundwater are analyzed, proving soluble salts experiencing precipitation-dissolution cycles in dry and wet seasonal variation. In dry seasons, water is completely evaporated and all minerals are precipitated. In rainy and irrigation seasons, highly soluble salts have the dissolving priority, excluding those salts having marine origins, and insoluble carbonate minerals tend to become cements, remaining in soil and vadose zones.δ2H (-60~-55‰) andδ18O (-8.4~-7.9‰) values of the shallow groundwater (5~15m of well depth) in Cangzhou are regarded as stable isotope values (δ2H,δ18O) of local modern precipitation by analyzing the distribution ofδ2H andδ18O values and comparing with the weighted average values of precipitation in Shijiangzhuang (IAEA) and records of ice core from Greenland.δ2H (-76~-72‰) andδ18O (-10.7~-10.1‰) values of the deep groundwater (300~450m of well depth) are defined as paleowater in glacial period of Late Pleistocene about 2.5 to 6 million years ago, based on the calculation of 14C data and the comparison of the Camp Century ice core.δ2H (-69~-59‰) andδ18O (-9.6~-8.2‰) values of the other shallow groundwater, sampled at 10~50m of well depth, are below the values of Holocene precipitation recharge, which indicates it is mainly recharged by paleo-Yellow River of Holocene by analyzing local hydrology and historical geography.Therefore, groundwater samples can be divided into 3 groups byδ2H andδ18O values: (1) samples of 5~10m depth recharged by modern precipitation, (2) samples of 10~50m depth mainly recharged by ancient Yellow River, and (3) samples of 300~450m depth considered as paleowater of Late Pleistocene ice age. Main ions and halogen elements are used to show environment of groundwater infiltration to avoid multiple explanations of such isotope method.The integrated application of groundwater dynamics, multi-tracers such as geochemistry and stable isotopes with paleoclimate, historical geography and environmental impact makes up the weak points of an individual method. The results have a theoretical significance of understanding recharge source and salinazation of groundwater, and provide adequate scientific basis for groundwater resources exploitation and saline water desalination.更多还原