Using Hydrochemistry And StrontiumIsotopes To Identify The Sources Of Salt In Groundwater Waters Of The Tianjin Coastal Area

Groundwater resources is very precious for us, especially in arid and semiarid regions, groundwater is the main water source in these areas.And because of the over-exploitation the groundwater saliniation has been raised,become a global environmental problem.lt may cause many problems,such as the shortage of potable water,soil salinization,abnormal growth crops.This project investigates each level of groundwater on the coastal areas of the Tianjin with Sr isotope. The major research focuses on Sr isotope and Sr content in groundwater and the seasonal change of water chemical characteristics in three years. Combining with the spatial distribution of groundwater, it aims to disclose the migratory route of ground water, as well as the processes of interactions among sea water, surface water, salt water and deep groundwater, additionally to discover the mechanisms of salt water intrusion and groundwater salinization, and the recycling route of groundwater. The results that this project brings will provide scientific evidence to the protection and management on the groundwater of the littoral areas. The dissolved Sr ranges from0.53μuM to3.47μM with87Sr/86Sr from0.707627to0.710178.The Sr data along with the available concentrations of major ions in the samples show that the deep groundwater salinization mainly was intruded by salt water of shallow groundwater. The seawater has litter effect on the salinization.The present study concerns the different geologic setting caused by different salinization incentive.The salinization of groundwater in coastal regions,are maily controlled by seawater intrusion.In arid and semiarid areas evapotranspirarion always lead to the salinization.Water-rock interaction is the main factor of groundwater saliniation in where created evaporite.And fresh water aquifer salinization in the regions that the fresh and salt water aquifer alternated, as a result of natural and human activities.In most areas of the world,changes in salts concentration of groundwater through one or any combination of four main mechanisms:seawater intrusion,water-rock interaction,evapotranspirarion and leakage between aquifers. In this research area, the main reason of the groundwater saliniation is the shallow ground fresh water supply to the deep underground. In view of the actual situation, we put forward some solutions:development the water saving agriculture, sewage reuse, artificial recharge, etc.