Study Of Spatial Distribution Feature Of Soil Salinity In The Glauber’s Salt Mining Area Of Danling County

By the influence of waste water and mineral waste residue which contains Glauber’s salt, the soil of Glauber’s salt mining area may be salinized. This thesis takes the small watershed soil of Danning County Glauber’s salt mining area as the object of study, and collects soil sample according to different scales, among them, there are totally52sampling points of large scale (the distance between two points is100m), and30sampling points of small scale (the distance between two points is5m). By measuring the following ten indexes, pH、EC、HCO3-、SO42-、NO3-、Cl-、Ca2+、Mg2+、K+、Na+, of the soil, then conducting semivariance analysis by geostatistics approach, and finally using common Kriging approach on ArcGIS platform to conduct spatial interpolation, this thesis studies the spatial distribution feature of soil salinity in the Glauber’s salt mining area by different scales systematically. As a result, this thesis provides a scientific basis for the grain yield increase and environmental improvement of the mining area, main research results are as follows:(1) The average EC value of the soil of research area is0.430dS/m, it indicates the soil is mild salinized; the EC value of the soil of the area close to mineral waste residue field reach up to2.380dS/m, it shows that it is severe salinized; under the condition of large scale, the average contents of HCO3-、SO42-、NO3-、Cl-、Ca2+、Mg2+、K+and Na+of the soil are348.25、1062.78、32.28、14.81、409.93、68.14.11.40and85.62mg/kg; under the condition of small scale, the average contents of HCO3-、SO42-、NO3-、Cl-、 Ca2+、Mg2+、K+and Na+of the soil are152.64,622.73,58.93,17.35,70.53,23.62,17.13and53.22mg/kg. To sort the contents of each soluble salt ions of the soil, of large scale, it is shown as:SO42->Ca2+>HCO3->Na+>Mg2+>NO3->Cl->K+, and of small scale, it is shown as SO42->HCO3->Ca2+>NO3->Na+>Mg2+>Cl->K+, that is to say, the negative ion of small scale mainly is SO42-and positive ions mainly are Ca2+and Na. This result indicates that the soluble salt of the soil mainly are gypsum and Glauber’s salt. Related research shows that, under the condition of large scale, the relationship between soil EC and SO42-、Ca2+、Mg2+、Na+presents as significant positive correlation, it means that SO42-、Ca2+、Na+in the mineral waste residue in the Glauber’s salt are main elements which influence the salt salinity content of the soil. And under the condition of small scale, the relation between soil EC and NO3-presents as negative correlation.(2) The spatial structure features of the soil salinity differ from each other by different scales. Among them, the nugget effects of Ca2+、K+、Na+under large scale and Na+by small scale are all less than0.25, a high spatial autocorrelation indicates that its spatial variation is determined by structural factors like geology and hydrology; the nugget effects of pH、EC、Cl-、Mg2+、K+under small scale are all1, it is pure nugget effect, that is to say, artificial random factors influence its spatial variation the most and the structural factors can be ignored. However, the nugget effects of the rest indexes are between0.25and0.75, they are influenced by structural factors and artificial random factors.(3) The soil salinity content of the research area has a high spatial variability. The distribution of SO42-、Ca2+、HCO3-、Mg2+、Cl-、Na+are the same with pH and EC under large scale, they are all decreasing progressively from the southwest to the east, that is to say, it decreases with the increase of the distance from the mining area. The result indicates that the distribution of these salinity ions is mainly influenced by structural factors like geology and hydrology; while, due to the contents of NO3-、K+are influenced by fertilizing, they mainly distribute in the northeast and southeast farming area of the research area; in the small sampling scale, soil salinity is mostly influenced by random factors (artificial activities), it leads to the weak continuity of spatial distribution of each index, most indexes have relative high contents around the paddy field and have relative low contents in the middle of the paddy field.