陕西咸阳地区潜水水化学特征及成因分析

Hydro-chemical characteristics and cause analysis of phreatic water in Xianyang Region

基于咸阳地区103个水样的主要离子及其他相关指标,通过数理统计方法、Piper三线图、相关性分析、因子分析法及Gibbs图等多种方法,分析研究了区域内潜水水化学场的空间分布特征及演化成因。研究结果表明,潜水阴离子主要为HCO_3^-,阳离子为Na^+、Mg^(2+),空间差异小,F-富集,SO_4^(2-)和Cl^-受地质因素和人为因素控制空间分异显著,区域性污染导致NO_3^-含量高。沿补排路径及渭河流向,水化学类型呈条带状变化。区内水化学场形成的主要控制因素是地质地貌及水文气候条件,在黄土台塬和冲积平原上,以溶滤作用为主,蒸发浓缩作用为辅,冲洪积平原反之,全区同时存在阳离子交替吸附作用和混合作用;次要控制因素是人类活动,并且作用日益增强。

Based on main ions and other relevant indicators of 103 water samples in Xianyang area,the spatial distribution characteristics and evolution causes of the phreatic water hydrochemical field have been studied by means of mathematical statistics,Piper’s three-line map,correlation analysis,factor analysis,and Gibbs map. The results show that the main anion of phreatic water is HCO3^-and the cations are Na^+and Mg^2+. Their spatial difference is small when SO42^-and Cl^-have a significant spatial differentiation controlled by geological and human factors. Meanwhile the enrichment of F-is notable and a regional pollution leads to high content of NO3^-. Along the recharge and discharge route and the direction of the Weihe River,the type of water chemistry changes in a strip. The main controlling factors for the formation of hydro-chemical fields in the region are geological geomorphology and hydroclimate conditions. In the loess plateau and alluvial plain,leaching is the main function while evaporation concentration acts as auxiliary,but alluvial-proluvial plain is the opposite. Cation alternating adsorption function and mixing function exist in the whole area. The secondary controlling factor is human activity,and its role is increasing day by day.