福建长乐地区海水入侵(上溯)对水化学变化的影响

海水入侵是沿海地区主要环境地质问题，分析沿海地下水和河水水化学特征，对圈定海水入侵范围及判断影响程度具有重要意义。通过在福建长乐市海水入侵含水层和闽江口海水上溯区采取23件水样进行室内常规离子测试，获得了海水入侵(上溯)区水中主要离子含量。利用海水稀释线分析主要离子与Cl离子之间的相对变化，对比离子实际浓度与理想浓度的差异，分析海水入侵对水化学变化的影响。研究结果显示，随着海水与淡水混合，水化学类型从海水到淡水依次为Na-Cl型水-Na-Cl·HCO₃型水-Na·Ca-HCO₃·Cl型水-Ca-HCO₃型水；引起水化学类型和TDS变化的主要因素为Na⁺和Cl^-的增加；Ca²⁺、Mg²⁺高于海水稀释线和理想浓度线，Na⁺、K⁺在海水稀释线和理想浓度线上下跳跃：Br^-/Cl^-与海水稀释线吻合较好，可以作为判断海水入侵范围的依据。

Water Chemical Changes with Seawater Intrusion (Upstream) in Changle City,Fujian Province

Seawater intrusion is a major environmental geological problem in coastal areas, and the analysis of chemical characteristics of coastal groundwater and river water is significant to delineate the scope of seawater intrusion and to determine the degree of influence.The purpose of the study was to analyze the changes of water chemistry in the process of seawater intrusion. To confirm the correlation, twenty three water samples were collected from aquifers of seawater intrusion of Changle and upstream movement area of Minjiang, which the conventional ion were tested at laboratory. By analyzing the relative changes between major ions and Cl ions with seawater dilution line, and comparing the ionic concentration difference between the actual and the ideal, the water chemical changes with seawater intrusion are investigated. The results were as follows: Types of water chemistry were followed by Na-Cl-Na-Cl·HCO₃-Na·Ca-HCO₃·Cl-Ca-HCO₃ as seawater mixed with freshwater; Increase of Na⁺，Cl^- was the main factor to affect the type of water chemistry and TDS; Content ofCa²⁺，Mg²⁺was higher than ideal concentration line and seawater dilution line，but Na⁺, K⁺ waved. The ratio curve ofBr^-/Cl^- was good agreement with seawater dilution line and can be used as one decisive factor to seawater intrusion.