土壤硒含量影响因素及富硒土地资源区划研究——以湖北恩施沙地为例

The Influencing Factors of Selenium in Soils and Classifying the Selenium-rich Soil Resources in the Typical Area of Enshi,Hubei

硒是人体必需的微量元素之一。为了研究土壤硒含量分布特征及其主要影响因素,并对富硒土地资源进行安全利用区划,本研究在恩施市沙地乡系统地采集并分析化验了199件表层土壤样,60件农作物样。分析了玉米籽实及对应的表层土壤中硒含量等地球化学参数的相关性,建立了玉米籽实硒元素吸收模型。结果表明:研究区表层土壤硒含量变化范围为0.19~15.57 mg·kg^(-1),算术平均值为1.88 mg·kg^(-1),远超过湖北省及全国表层土壤硒含量水平,足硒、富硒土壤面积占研究区总面积的84.43%;表层土壤硒含量分布受控于地质背景,不同地质背景的表层土壤硒含量分布存在较大差异,二叠系茅口组地层表层土壤硒含量显著高于其他地层分布区域;土壤有机碳含量及海拔高度是影响研究区表层土壤硒含量的重要因素;农作物硒含量变化范围较大,其中处于富硒水平的农作物所占比例最大,为43.22%;研究区富硒土地面积和潜在富硒土地面积分别占研究区总面积的65.33%和23.12%。

Selenium is an essential element for mammals. In order to study the distribution characteristics,the important influencing factors of selenium distribution in soils and to classify selenium-rich soil resources,this study systematically collected and analyzed 199 top-soil samples and 60 crop samples in Shadi township of Enshi City. The correlation of the geochemical parameters,such as the selenium concentrations of corn seeds and top soils,was analyzed,and as a result an absorption model of selenium in corn seeds was established. Results of the analysis show that concentrations of total selenium in the top-soils ranged from 0. 19 mg·kg^(-1) to 15. 57 mg·kg^(-1),and averaged 1. 88 mg·kg^(-1),which is clearly higher than the average concentrations in Hubei Province and China as a whole. The area with selenium-sufficient soil and selenium-rich soil accounts for 84. 43%of the study area. The distribution of selenium is mainly influenced by geology. There is a significant difference in selenium content distribution in top-soils formed in proximity to different geologies. The selenium content inthe outcropping area of Permian Maokou Formation is higher than that of other stratigraphic regions. The results also indicate that soil TOC and altitude were important influencing factors on selenium content. The selenium concentrations in crops had a large range. Se-enriched crops have the largest proportions,accounting for 43. 22%. The selenium-rich land and potentially selenium-rich land accounted for 65. 33% and 23. 12% of the study area,respectively.