内蒙古河套灌区典型监测区不同时期地下水变化特征

Groundwater characteristics at different periods in a typical monitoring area of the Hetao irrigation district of Inner Mongolia

选择内蒙古河套灌区一典型监测区作为研究区,对区内地下水埋深、TDS、主要离子等进行了连续监测(2012年5月-2015年12月),运用统计学方法分析了试验区内地下水埋深、TDS等在全监测期、非冻融期和作物生长期的变化特征,以及各关键环境要素间的相关性。研究结果表明:(1)研究区内约82%地下水属于微咸水,TDS大多介于1～2g/L,地下水化学类型为HCO3-+Cl--Na++Mg2+型;(2)地下水埋深与TDS呈微弱正相关,而TDS与Cl-、SO42-和K++Na+在三个时期的相关系数均比较大,属于高度相关,这些离子的变化对地下水质的影响较大;(3)综合变异分析、相关分析和主成分分析,Cl-和TDS的相关性均为作物生长期>非冻融期>全监测期,说明蒸发浓缩和溶滤作用对灌区地下水水化学特征的影响占主导地位。

A typical monitoring area of the Hetao Irrigation District of Inner Mongolia was used in this study to explore the groundwater charactristics at different periods.The depth to water table,total dissolved solid(TDS)and eight major ions were continuously monitored from 05/2012 to 12/2015.The characteristics of depth to groundwater and TDSwere analyzed with statistical methods,based on the filed observation data,for the entire monitoring period,non-freezing-thawing period and crop growth period,respectively.The results showed that:(1)82% of the groundwater in the study area was brackish water.TDS was mostly between 1~2 g/L.The groundwater chemical type was HCO^-3+Cl^——Na^++Mg^2+.(2)There was a slightly positive correlation between depth to water table and TDS.However,the correlation coefficients between TDSand Cl^-,SO^2-4,K^++Na^+were relatively higher for all three periods,which implied that these ions had a great impact on TDS.(3)The correlation coefficients between Cl-and TDSat three periods were crop growth period>non-freezing-thawing period>the entire monitoring period,indicating that concentration caused by evaporation and leaching played the dominant role in the variations of the groundwater chemical characteristics.