恩施土壤全硒含量分布的研究

A STUDY OF THE DISTRIBUTION OF SOIL TOTAL SELENIUM CONTENT IN Enshi Prefecture

在恩施州境内采集442个土壤样品,对其进行全硒含量的测定,研究其空间异质性和分布格局。为了绘制土壤全硒含量分布图并进行验证,将442个样品,分为两部分,一部分为建模样品点,样品数为424个,占总样品的96%;另一部分为检查点,样品数为18个,占总样品的4%。经分析,建模样品的全硒含量不服从正态分布,但服从对数正态分布;经数据变换后在GS+软件中构造出了变异函数,变程R=38100m,块金值为0.268,空间异质性指数Q=0.28,说明全硒含量的变异主要是由结构性因素引起的,空间自相关性较强,用普通克立格法(OK法)绘制全州的土壤全硒分布图,发现利川市齐岳山以西土壤全硒含量相对偏低,小于1.28μg·g-1。用交叉验证法和F检验法对土壤全硒含量分布图验证认为,所构建恩施州土壤全硒含量分布图是可用的。

In this study,442 samples were collected in Enshi Prefecture and measured their soil total selenium content. In order to explore the distribution the soil total selenium content,the samples were divided into two groups：samples for modeling and samples of validation,the former taking up 96% with 424 samples and the latter accounting for 4% ,with 18 samples. The analyses show that the total selenium content in samples for modelling did not conform to the normal distribution but conform to logormal distribution. After the data conversion,the variation function was constructed in the GS ＋ software,where the range （ R） was 38100m,the nugget was 0. 268 and the spatial heterogeneity index （ Q） is 0. 28. This indicates that the variation in total selenium content mainly contributed to the structure factor,and there was a strong spatial autocorrelation,so the Ordinary Kriging （OK） can be used to map the soil total selenium distribution of the whole Prefecture. From the map,it can be seen that the soil total selenium content was relatively low in the west to Qiyue Mountain in Lichuan City,less than 1. 28μg /g. Cross-validation and variance homogeneity were then adopted to validate the distribution map. The identical conclusion is reached that the distribution map of soil total selenium content constructed is applicable.