基于电磁感应仪的黄河三角洲地区土壤盐分时空变异特征

Spatio-temporal variability of soil salinity in the Yellow River Delta using electromagnetic induction

针对黄河下游三角洲土壤盐渍化的空间复杂性与发生反复性,运用磁感式大地电导率仪EM38及其移动测定系统,结合GIS与地统计学方法,对该地区典型地块两个关键季节土壤盐分的时空变异特征进行了分析。结果表明,土壤表观电导率与盐分呈极显著相关性;各时段土壤盐分都表现出多层次空间结构的复合尺度效应,且短程变异构成了土壤盐分空间异质性的最主要部分;土地利用方式差异使得秋季时段土壤盐分呈弱各向异性,地形因素导致春季时段土壤盐分各向异性比在全步长域波动,但在整个研究尺度上仍为各向同性。空间分析表明,结构性因素主导了土壤盐分空间分布格局,随机性因素是加快该分布格局形成的重要因素;春季时段研究区总体表现出积盐趋势,且盐分变动幅度主要集中在10.0 g/kg范围内。电磁感应仪与GIS的结合运用为不同尺度土壤调查与质量评价提供了新的途径,并为农业水土资源的决策管理提供指导。

Aiming at the spatial complexity and genesic repeatability of soil salinization in Lower Yellow River Delta, with the application of electromagnetic induction EM38 and its mobile sensing system, spatio-temporal variation of soil salinity in typical field of this region during two critical seasons was analyzed by using GIS and geostatistics method. Results indicate that apparent soil electrical conductivity is significantly correlated with salinity. Soil salinity at two periods both exhibits compound scale effect of multilayer spatial structures, and short-range variation is the chief constitute of spatial heterogeneity. Difference of land use patterns results in weak anisotropy of soil salinity at autumn period, and topography leads to fluctuation of anisotropic ratio in the whole lag size at spring period, while it remains isotropic at the study scale. Spatial analysis shows that the spatial distribution of soil salinity is mainly controlled by structural factors, while stochastic factors accelerate its formation. Soil salinity generally exhibits the trend of increment at spring period across the study areas, and the variation amplitude of soil salinity is mostly less than 10.0 g.kg^-1. The joint application of electromagnetic induction and GIS provides a reference for the survey and quality evaluation of soil resources at different scales, and it can be used as a guide for the decision-making and management of agricultural water-soil resources.