【作者】 王娟；

【导师】 刘贯群；

【作者基本信息】 中国海洋大学 ， 环境工程， 2011， 硕士

【摘要】 黄河三角洲位于陆海交汇的过渡带,是河流动力和海洋动力相互作用下在河口地区形成的沉积物堆积体,受陆海相互作用的影响,该区地下淡水和微咸水资源匮乏,咸水、卤水广泛分布。自晚更新世以来该区经历了三次海侵与海退,地下水赋存条件复杂,不同含水层地下水的起源及水化学特征各不相同。海侵和海退过程是一个复杂的多组分化学反应过程,主要包括咸淡水混合、蒸发浓缩、离子交换和矿物溶解沉作用,也是该区地下水化学成分形成的主要作用。研究该区地下水的化学成分特征及其形成机制,可以为确定地下水环境的承载能力和地下水的合理利用提供科学依据。本文在充分研究黄河三角洲地区地质、水文地质条件的基础上,将黄河三角洲地区地下水划分为:南部冲洪积潜水-承压水、黄河三角洲潜水和浅层承压水三个系统,分析了各系统地下水化学成分特征;通过研究各含水层地下水中δ18O-δD、δ18O与Cl-含量的关系探讨黄河水、大气降水以及海水对地下水的补给;根据14C测定结果及地下水中14C与Cl-含量的关系判断地下水的年龄和地下水的起源;通过实验分析并运用水文地球化学模拟软件PHREEQC揭示了该区地下水化学成分的主要形成作用。研究表明:南部冲洪积潜水-承压水为淡水资源,水化学类型主要为HCO₃-Ca·Mg水,HCO₃·Cl-Ca·Mg水和HCO₃-Na水。黄河三角洲潜水主要为微咸水和咸水,同时也存在少量淡水透镜体,水化学类型为HCO₃·Cl-Na·Ca水、Cl·HCO₃-Na·Mg水和HCO₃·Cl-Na·Mg水。浅层承压水为咸水和卤水,水化学类型以高矿化的Cl·SO4-Na·Mg水和Cl-Na水为主。南部小清河两侧埋深大于100m的深层地下水形成年代比浅层地下水早得多,浅层地下水来源于现代大气降水的补给,而深层地下水可能起源于古代大气降水的入渗补给;黄河三角洲潜水形成年代较晚,地下水年龄小,起源于现代大气降水和黄河水;含水层埋深20³0m的浅层承压水年龄介于4000⁷500年间,起源于古海水,并发生浓缩作用。研究区地下水化学成分形成作用主要为蒸发浓缩作用、阳离子交替吸附作用和矿物溶解沉淀作用。随着远离黄河沿水流方向由陆向海,潜水含水层中土壤颗粒表面发生的Na⁺对Ca²⁺的交替吸附作用呈减弱趋势。地下水中各种组分除Cl、K和Na仅以离子形式存在外,Ca、Mg、S、C均存在多种络合形式。石膏和岩盐的饱和指数都小于0,地下水对石膏和岩盐具有侵蚀性,且沿地下水流动方向侵蚀强度减弱。而方解石、白云石和文石的饱和指数大于0,处于过饱和状态,矿物发生沉淀。更多还原

【Abstract】 The Yellow River delta, located in the transitional zone of land and sea, is asediment deposit which forms from the interaction of river dynamics and seadynamics. Salt water and brine is widely distributed in the delta, but fresh water andbrackish water is scarce. Marine transgression and regression has happened threetimes in the area since Late Pleistocene, so the groundwater storage and distribution iscomplex, and the water origin and water quality are different. Marine transgressionand regression is a complex process with multicomponent reactions, including mixingerosion of saltwater-freshwater, evaporation-concentration process, cation exchangeand mineral dissolution/precipitation process. They are the most important processesof the groundwater chemical formation in the delta. The study on chemicalcompositions and formation of groundwater will provide scientific evidence for theidentification of environmental carrying capacity and reasonable use of groundwater.Based on the fully studying of geology condition and hydrogeology condition ofthe Yellow River delta, groundwater here is divided into three systems: the phreaticand confined groundwater in the south diluvial fan, phreatic water and shallowconfined groundwater in the Yellow River delta. The chemical characteristics ofgroundwater in each system are analysed. The relationship between groundwater andYellow River, rainwater and seawater is studied by analyzingδ¹⁸O-δD andδ¹⁸O-Cl- ofgroundwater in aquifers. The age and origin of groundwater are estimated accordingto the result of 14C and the relationship between ¹⁴C and Cl^-. And then the formationmechanism of groundwater chemical composition is revealed through experimentanalysis and PREEQC soft.The study shows that: the phreatic and confined groundwater in the southdiluvial fan is fresh water, and the hydrochemical types are mainly HCO₃-Ca·Mg, HCO₃·Cl-Ca·Mg and HCO₃-Na. Phreatic water in the Yellow River delta is brackishwater, salt water and a small amount of lenticular freshwater. Cl·HCO₃-Na·Mg waterand HCO₃·Cl-Na·Mg water are the main hydrochemical types. Shallow confinedgroundwater is salt water, even brine, and hydrochemical types are Cl·SO₄-Na·Mg andCl-Na.Formation period of deep groundwater （depth of confined aquifer is more than100m） in both sides of Xiaoqing River is much earlier than shallow groundwater. Itprobably originated from paleo-rainwater recharge. Phreatic water in the Yellow Riverdelta is relatively young and originated from modern rainwater and the Yellow River.High-salinity shallow confined groundwater, aged between 4000 and 7500, originatedfrom paleo-seawater which remained in the area and became concentrated.In the study area, evaporation-concentration process, cation exchange andmineral dissolution/precipitation are the most important effects related to theformation of groundwater chemical composition. Cation exchange occurred on thesurface of aquifer medium decreases with increasing distance to the Yellow River. Cl,K and Na of the groundwater exist in the form of ions, while Ca, Mg, S, and C haveother complex compounds except ion forms. The saturation index of gypsum andhalite is below 0, so groundwater is erosive for gypsum and halite. And the erosiveintensity becomes weak along the direction of groundwater flow. Calcite, dolomiteand aragonite are in a supersaturation state and will be precipitated.更多还原