紫阳富硒区土壤中的硒

SELENIUM IN SOILS OF SELENIUM-RICH AREAS IN ZIYANG COUNTY

为探讨地方病与环境硒的关系,本文研究了陕西紫阳富硒区土壤硒的含量,分布规律以及土壤有效硒与土壤理化性质的关系。结果表明,因母质和成土条件不同,土壤含硒量变化各异,平均值为0.323mg/kg土。水溶态硒占全硒的0.1—0.9%,KH_2PO_4浸提态硒占全硒的1.1—3.8%。按照土壤硒的地理分布,可分为四个区:中毒区、高硒区、中等含量区、低硒区。硒在土壤剖面中的分布,都是表土层含量最高,然后随深度加大而逐渐减少。7种土壤因子对KH_2PO_4浸提态硒影响的程度依次为:CaCO_3>粉粒>有机质>粘粒>pH>有效性铁>代换量。土壤和植物样品的分析结果表明,KH_2PO_4浸提态硒能反映土壤对植物的供硒状况。

In order to find out some endemic desease in relation to environmental selenium, the content and the regular distribution of Se in soils of selenium-rich area in Ziyang county have been studied, and the relationship between the soil available Se and soil properties has been discussed. The total Se contents of soils varied with the parent material and soil-forming condition, and the average content of total Se was 0.323 mg/kg, ,the water-soluble Se content ranged from 0.1% to 0.9%, and the KH_2PO_4-extracted Se from 1.1% to 3.8%. Selenium-rich rocks and soils were found to be only distributed in the limited areas. According to the geographical distribution of Se in soils of Ziyang county, Four areas could be distinguished follows: 1. selenium-toxi.c area, 2. high-selenium area, 3. medium-stlenium area, and 4. low-selenium area.The Se content of topsoil was the highest, and it decreased with the depth progressively in the soil profile. The degrees of seven soil factors affecting the KH_2PO_4-extracted Se: CaCO_3>silt > organic matter > clay > pH > free iron > CEC. The analytical results of the soils and plants have proved that the KH_2PO_4-extracted Se could reflect the situatious of Se supplied by the soil.