黄河三角洲土壤盐渍化与地下水特征关系研究

为研究黄河三角洲表层土壤盐分含量与地下水特征的关系,对研究区内土壤盐分含量及地下水进行原位监测,分析土壤盐渍化和地下水特征,并运用灰色关联分析法对地下水埋深、电导率、p H和主要离子含量的关系进行定量分析。结果表明:土壤表层盐分含量均值为3.90~6.31 g kg-1,表层以下土壤盐分含量均值为2.54~3.44 g kg-1,属于中度及以上盐渍化程度;地下水埋深平均值为1.16~1.71 m,普遍较浅;地下水阴离子以Cl-为主,阳离子以Na+为主,两者分别占阴、阳离子总量的比例约为65%。关联分析表明,不同地下水特征指标与土壤表层盐分含量的密切程度不同,同一特征指标与土壤表层盐分含量的密切程度在不同时期间差异显著,总体而言,土壤表层积盐与地下水电导率、Na+、Cl-的关系较为密切,与p H、CO32-和HCO3-之间的关系较弱。在防治土壤盐渍化中,应当加强对地下水电导率、Na+、Cl-的控制与管理。

Relationship between Soil Salinization and Groundwater Characteristics in the Yellow River Delta

Objective]Soil salinization is one of the most important environmental problems that restrict the ecological system and the sustainable development of agriculture in the Yellow River delta. Composed mainly of silt and fine sand the soil is stronger in capillary water action,turning groundwater into the main factor affecting migration,accumulation and release of salt in soil body. To study relationships between soil salinity and groundwater will sure be of important theoretical value and practical significance to amelioration of the saline alkali soil and control of secondary salinization of the soil in the Yellow River Delta.Method]In order to study the relationship between salt accumulation in topsoil and groundwater characteristics and to monitor in-situ variation of soil salt content and groundwater table in the Yellow River Delta,four sections were laid out and a total of 20 wells set up by taking into full consideration factors like hydrogeological features,soil salinization status,topography,land use and human activities. Groundwater tables in the wells were measured,and water samples from the wells and topsoil(0~15 cm)samples in the locations of the wells were collected in February,May,August and November,2013 for analysis of salt content and characteristics of the groundwater. Groundwater tables were measured,and samples of the groundwater and topsoil(0~15 cm)were collected from the wells and the fields near the wells,separately, in February,May,August,and November 2013,for analysis of soil salt content and characteristics of the groundwater. Grey correlation analysis of the obtained data was performed to quantitatively analyze relationships of groundwater table with EC,pH,and ion content(Ca2+,Mg2+,K+,Na+,CO32-,HCO3-, Cl- and SO24-)of the water relative to season.Result]Results show that soil salt varied in the range of 3.90~6.31 g kg-1 in content,in the topsoils and of 2.54~3.44 g kg-1 in the subsoil both belonging to the category of medium or higher in salinization degree;Groundwater tables were all rather high,fluctuating in the range of 1.16~1.71 m;and the anion in the groundwater was dominated with Cl-,while the cation with Na+,accounting in total for 65% of the total of ions. Correlation analysis shows that the relationships of the groundwater characteristics with salt content in the topsoil varied from index characteristics and with time as well. On the whole,salt accumulation in the surface soil was closely related to EC,Na+ and Cl- in the groundwater,but not so to pH,CO32- and HCO3-.Conclusion]To control and manage soil salinization in the Yellow River Delta,it is essential to intensify control of EC,Na+ and Cl- in the groundwater of the region.