山东莱州湾南岸典型剖面海（咸）水入侵过程的水文地球化学识别

摘要

Laizhou Bay area, Shandong Province, is a typical area for seawater intrusion studies. In order to fur-ther research of the seawater intrusion in this area, the typical profile of Changyi-Liutuanin the south coast of Lai-zhou Bay is chosen to be studied. Various water samples (i.e. river water, fresh water,brackish water, salt water, brine water and seawater) were collected to analyze the characteristics of major hydrochemical compositions, combining environment isotopes (d18O-d2H), and the ratios of major ions and saturation index of the main miner-als. According to the hydrochemical characteristics of different waters, the mixing effect occurres firstly during the seawater (salt water) intrusion in the studying area. And then, the cation exchange and adsorption effect, the dissolution and precipitation effect take places in varying degrees. And the saltwater, brackish water formed through fresh groundwater mixing with brine water according to the special ion ratios. Some deep fresh water has also been affected by the brine water intrusion, based on the distribution characters of the saltwater and Cl--δ18O relationship. Through testing and comprehensive analysis of hydrogen and oxygen isotopes,we propose that fresh groundwater in the studying area originate from atmospheric precipitation obviously, and the brine water of Quaternary sea water origin is effected by the evaporation effect,"Oxygen elegant"is quite serious. The saturabil-ities of the main minerals show that rock salt are in the unsaturated condition, and gypsum and dolomite in the underground fresh water and brackish water are unsaturated, but they are saturated in salt water and brine water;calcite in all waters are substantially saturated.%山东莱州湾地区是我国海水入侵研究的典型地区之一，为了进一步促进对莱州湾海水入侵的认识，本次研究选择莱州湾南岸的典型剖面（昌邑-柳疃）为研究对象，系统采集了不同类型水样（河水、淡水、微咸水、咸水、卤水和海水），分析了不同水体的水化学、δ18O、δ2H、离子比及饱和度等特征。根据不同水体的水化学特征分析，判断出研究区在海（咸）水入侵过程中首先发生了混合作用，在此基础上，发生了阳离子交替吸附作用和不同程度的溶解沉淀作用。特征离子比值分析表明，咸水、微咸水是由地下淡水与卤水混合形成；剖面上咸水体的分布特征、δ18O－Cl-关系显示部分深层地下淡水也受到了卤水下移侵入影响。氢氧同位素的分布特征表明，研究区地下淡水明显来源于大气降水，第四纪古海水成因的卤水受到了蒸发及浓缩作用，“氧漂移”现象比较严重；矿物饱和度显示，研究区所有水体中盐岩均处于未饱和状态，石膏与白云石在部分地下淡水和微咸水中未达到饱和，在卤水与咸水体中处于饱和状态，方解石则在所有水体中都基本呈饱和状态。