川西高原天然剖面土壤硒的含量及分布特征

摘要

There is a wide distribution of low selenium belts in China, resulting in a large area of relevant endemic disease. It is necessary to study on the regularity of selenium distribution in undisturbed soils and analyze the influence factors, so as to provide references for urban layout and agricultural production, to avoid the effect of low selenium on the population health. Barkam county, Zamtang county, Aba county, and Ruoergai county in the western Sichuan Province have been selected as the study area, which are in the famous low selenium belt in China in order to avoid the interference of human activities to selenium distribution and enrichment regularity. Six groups of natural soil profile samples have been collected in the areas with less human activities. Selenium concentrations in the samples have been analyzed and the basic statistics, correlation analysis of selenium with major elements, and principal component analysis have been made to study the influence factors. The results show that the soil selenium concentrations ranged from 0.06 to 0.16μg·g-1, obviously lower than the global and China’s average soil selenium contents, in consistence with the rock research results, which showed that the geological background and the soil parent material are the main factors affecting the soil selenium contents. Principal component analysis and correlation analysis by SPSS revealed that organic matter, the element S, P, Ca, Si, Al, Mn and their compounds in soil are the important factors for controlling the selenium contents in soil profile. The enrichment and erosion of soil selenium have close relationships with these substances.%中国低硒带分布范围广，低硒程度高，造成了广泛的相关地方病的发生。对未经人为破坏的天然土壤中硒的分布规律及其影响因素进行分析研究，可为城镇布局和农业生产提供参考，避免低硒现象对人群健康的影响。选取中国著名低硒带上的川西阿坝地区的马尔康、壤塘、阿坝和若尔盖为研究区域，在人为活动较少的区域进行布点。采集6个天然土壤剖面样品，分析其硒含量，并对土壤样品中与硒含量相关的影响因素进行统计分析，研究影响硒分布和富集的因子。结果表明：研究区天然土壤剖面样品中硒的质量分数范围为0.06~0.16μg·g-1，明显低于世界和中国土壤硒含量平均水平。此结果明显对应于该区域岩石中较低的硒含量，表明地质背景和土壤母质是影响土壤硒含量的主要因素。统计分析表明，土壤有机质质量分数以及S、P、Ca、Si、Al、Mn等元素及其化合物的质量分数都是影响和控制硒在土壤剖面中的含量和分布规律的重要因素；硒在土壤中的固定和流失均与这些物质有着密切的关系。