江苏盐城地区地下水水化学特征及形成机理

为了查明江苏盐城地区深层地下水咸化的主要影响因素,采集了不同类型水样(河水、浅层地下水、深层地下水和海水),通过对该地区不同水体的水化学特征、离子比值以及氘氧氚同位素组成进行分析,研究了盐城地区深层地下水水化学特征的形成机理。结果表明:浅层微咸水主要是溶解地层盐分和蒸发作用形成,而滨海港镇的部分地区受到一定程度的现代海水入侵影响。深层地下水总体为淡水,水化学演化以正常的水-岩作用为主,而深层微咸水主要分布在两个地区,一是东部滨海地区的灌河口至大丰一带,二是内陆地区的大丰市及其周边一带。滨海地区的深层微咸水主要是淋滤古海相地层盐分形成,黄沙港镇部分地区则受到轻微的现代海水入侵影响,而内陆地区的深层微咸水主要是浅层咸水下渗造成的。因此,盐城东部沿海矿化度增高的区域应大力加强对地下水的保护,特别是随着全球变暖,黄海海平面有上升的趋势,东部的滨海港镇等受海水入侵影响较大的区域更应引起高度重视。

HYDROCHEMICAL CHARACTERISTICS AND FORMATION MECHANISM OF THE GROUNDWATER IN YANCHENG,JIANGSU PROVINCE

For the purpose of investigating the main factors of deep groundwater salinization in the coastal plain of Yanchen,Jiangsu Province,various water samples (river water,shallow groundwater,deep groundwater and seawater) were collected to analyze their characteristics of hydrochemistry and isotopes.On the basis of the analysis of the environment isotopes (δ18O-δ2H),the characteristics of major hydrochemical composition and the ratios of major ions,the results suggested that dissolving the salts of strata and evaporation are the dominant processes in the evolvement of shallow brackish groundwater,and some shallow brackish samples in Binhaigang areas are possibly affected by seawater intrusion.The distribution of deep brackish groundwater is mainly in two areas;one is located along the coastal areas,while the other is in the inland areas of Dafeng and its surrounding areas.Dissolving salts of ancient marine strata is the major cause for the salinity of the deep confined groundwater in eastern coastal areas;moreover,some deep groundwater may be also influenced by seawater intrusion,such as YC2012 in Huangshagang.Among the inland areas surrounding Dafeng,the deep brackish groundwater is caused by mixing with overlying shallow saline groundwater.The water quality of the deep aquifer in central and western areas is good as a whole,and the hydrochemical evolution is the natural water-rock interaction.Hence,the deep aquifer groundwater in eastern coastal areas where TDS is high should be protected effectively,especially the salified areas such as the town of Binhaigang.