江苏盐城滨海地区浅层地下咸水的水盐来源及咸化成因

Water and salt sources and salinization of shallow saline groundwater in the coastal area of Yancheng, Jiangsu

江苏盐城滨海地区浅层地下咸水对区域水资源利用和生态环境保护具有重要影响,为了查明浅层地下咸水的水盐来源及咸化成因,于2018—2019年采集了研究区河水、雨水、海水、地下淡水、微咸水及咸水等不同类型水样,对水样的水化学组成、离子比、Piper三线图、氢氧同位素组成及^(14)C测年结果进行了分析,结果表明:①潜水与第Ⅰ承压含水层地下水均以咸水为主,潜水含水层上部存在埋深小于10 m的淡化层,向海方向分布有淡水、微咸水、咸水水质类型。②潜水与第Ⅰ承压含水层地下水主要来源于全新世暖期降水补给,盐分来源于强烈蒸发浓缩后的古残留海水。③潜水淡化层地下水主要来源于现代时期降水补给,盐分来源于岩盐和铝硅酸盐矿物的溶解,废黄河口部分地区地下水咸化主要受海水入侵影响。

For the purpose to identify the sources of groundwater and salt and the salinization of shallow groundwater in the coastal area of Yancheng,Jiangsu province,different types of water samples are collected,such as the river water,rainwater,seawater,underground fresh water,brackish water,salt water in the study area during the period from 2018 to 2019.The chemical composition and ions ratio,Piper diagram,hydrogen and oxygen isotopic composition and ^(14)C dating results are analyzed.The results suggest that:(1)The phreatic water and the first confined water are dominated by saline water.The upper layer of the phreatic aquifer is less than 10 m in thickness and widely desalinated,which changes seawards from fresh water,brackish water to salty water.(2)The water in the phreatic aquifer and the first confined aquifer mainly come from precipitation replenishment in the Holocene warm period,and salinity mainly come from the ancient residual seawater that has suffered strong evaporation and concentration.(3)Groundwater in the phreatic desalination layer mainly comes from modern precipitation replenishment,and salinity mainly comes from the dissolution of rock salt and aluminosilicate minerals,the salinization of groundwater in some areas of the abandoned Yellow River estuary is mainly affected by seawater intrusion.