西北地区黑河中游盐渍化地区土壤盐分特征

土壤盐渍化是黑河中游可持续发展面临的主要问题之一,有必要深入分析该区盐渍化土壤的盐分含量以及各可溶性离子的相关性。通过野外考察和GPS定点等手段,在甘肃张掖市高台县境内黑河两侧盐渍化土壤进行了采样。采样方式为人工坑探分层取样法,地表5 cm内取样,如土壤剖面层位变化时取样,层位不变或者层位厚度超过50 cm时,平均30 cm取一次样;待水位静止后,采取地下水样品。一共坑探15个剖面,共采取90个土壤样品和15个地下水样品。样品的盐分以及各可溶性离子含量的测试结果表明:区内表层土壤属于重度盐渍土,土壤中盐类主要为硫酸盐,其次为氯化物,盐分聚集层的厚度在20~30 cm之间;在各层中,含盐量与SO24-、K++Na+、Cl-、Mg2+相关性较强,SO42-、Cl-与K++Na+的相关性较强,但在深度为90~100 cm的土层中各种相关性都减弱;土壤垂直剖面上,颗粒越细的层位其盐分含量越大,颗粒越粗的层位其盐分含量越小,而且颗粒粗大的层位越厚其表层盐渍化程度越低,颗粒细小的层位越厚则表层盐渍化程度增高。

Salt Characteristics of Salt-affected Soil in the Middle Reach of Heihe River in Gansu Province

The middle reach of Heihe River in Gansu Province is faced with serious problem of soil salinization.It is necessary to study the content of salt and the correlation among the soluble ions in salted soils further.Based on the field observation and the GPS technology,the salted soil and the groundwater samples were taken along the Heihe River in Gaotai County,Zhangye District.This study adopted the pit prospecting method.In each pit,the groundwater level was disclosed.Within 5 cm from the surface and when soil particle changed at the vertical profile,the samples were taken.If one single soil layer was more than 50 cm,the samples were taken at 30 cm intervals.After the groundwater reached to the static level,the groundwater samples were taken.The total pits,groundwater samples and the soil samples are 15,15 and 90,respectively.The analysis results of the contents of salt and ions show that the surface soils are intensely salinized,and the primary compound is sulphate,the secondary is chloride.The depth of salt accumulation layer is about 20-30 cm from the surface.In most of layers,the total salt content has strong correlation with sulfate ion,summation of potassium ion and sodium ion,chloride ion and magnesium ion,as well sulfate ion and chloride ion has strong correlation with summation of potassium and sodium ions,whereas on layer of 90-100 cm,each type of correlation attenuated.On the vertical soil profile,the layer with fine particles has higher salt content and the layer with coarse particles has lower salt content.Furthermore,the layers with coarse particles are thicker,the surface salinization is less intense,and the layers with fine particles are thicker,the surface salinization is more intense.