青土湖土壤剖面盐分特征及其定量表述研究

Study on salt distribution characteristics and mathematical expression of the soil profile in Qingtu Lake

选取石羊河流域下游青土湖芦苇区与荒漠植被过渡区为研究区,采集24个样点不同深度土样和地下水水样,测定土壤含盐量和质地、地下水埋深和矿化度等环境要素,分析芦苇区与荒漠植被过渡区土壤剖面含盐量分布特征及其主要影响因素和定量表述式。结果表明:(1)土壤剖面盐分聚集在芦苇区主要为平均型,荒漠过渡区主要为表聚型(0~20 cm)和中聚型(20~60 cm);(2)土壤盐分(S)随地下水矿化度(m)与埋深(h)之间的比值呈指数型关系式(S=aebm/h);(3)随着m/h值的增大,芦苇区盐分聚型从平均型到中聚型,荒漠过渡区从平均型到中聚型再到表聚型的方式过渡;(4)维持芦苇和荒漠典型植被(如白刺)生长的土壤表层含盐量分别不超过2 g·kg-1、6 g·kg-1时,地下水临界埋深为1.15 m和2.37 m,可为该地区生态地下水位调控和植被恢复提供科学依据。

In this paper,24 samples of soil and groundwater in different depths were collected from the reed area of Qingtu Lake and the transition area of desert vegetation in the lower reaches of the Shiyang River Basin.Environmental factors,such as soil salt content and texture,groundwater depth,and mineralization degree,were measured.The distribution characteristics,main influencing factors,and quantitative expression of salt content in the soil section of the transition area between the reed area and desert vegetation were analyzed.The results show that the salt concentration of soil profile in the reed area is mainly average type and is mainly surface type(0-20 cm)and middle type(20-60 cm)in the desert transition area.The relationship between soil salt"S"and the ratio of groundwater salinity"m"to burial depth"h"is an exponential type(S=aebm/h);with the increase of m/h value,the salt accumulation pattern in the reed area is from average type to middle type,and the transition pattern in the desert transition area is from average type to middle type to surface type.When the salt content of the soil surface layer maintaining the growth of reed and desert-typical vegetation(such as Nitraria tangutorum)does not exceed 2 and 6 g?kg-1,respectively,the critical burial depth of groundwater is 1.15 and 2.37 m.It can provide a scientific basis for ecological groundwater level regulation and vegetation restoration.