陕西泾惠渠灌区土壤-小麦体系中硒的空间分布特征

Spatial distribution of selenium in soils and winter wheat grain of Jinghui irrigation area of Shaanxi(China)

查明一个地区土壤和主食中硒含量及其空间分布特征,是探究该地区人体硒营养状况的重要基础.基于陕西泾惠渠灌区104个表层土壤样品和对应的小麦籽粒硒含量的测定,运用地统计的方法,对该地区硒含量的空间分布特征进行了分析,评价了土壤硒的有效性及其对人体硒摄入量的影响.结果表明:泾惠渠灌区土壤总硒含量变化为0.020~0.603 mg·kg-1,平均为(0.154±0.085)mg·kg-1,76.9%的地区处于临界缺硒状态,其中以阎良区土壤硒含量显著高于高陵区、临潼区、泾阳县和三原县;小麦籽粒硒含量为0.003~0.485 mg·kg-1,平均为(0.076±0.070)mg·kg-1,各地区间无显著差异,69.2%达到适度硒水平.造成土壤硒含量处于临界缺硒水平而小麦硒含量达到适度硒水平的原因是该地区土壤有效硒占土壤总硒含量的11.6%,硒的有效性相对较高.该灌区土壤和小麦的硒含量分布存在显著空间分布不均一性,在粮食硒强化中应综合考虑土壤供硒及作物硒吸收两个方面.

It is important to clarify selenium （Se） spatial distribution in soil and corresponded staple food for exploring Se nutrient status of human in a region. Based on the determination of Se content in 104 surface soil samples and wheat grain in Jinghuiqu irrigation area, the spatial distribution characteristics of Se content in this area were analyzed by means of geostatistics. The results showed that the total Se content in soil of Jinghuiqu irrigation area ranged from 0.020 to 0.603 mg.kg^-1 with mean value of （0.154 ± 0.085） mg·kg^-1.76.9% of the area belonged to critical Se deficiency. Soil Se content was significantly higher in Yanliang district than other areas in this study. Se content in wheat grain ranged from 0.003 to 0.485 mg·kg^-1 with mean of （0.076 ± 0.070） mg.kg^-l. No significant difference was found of wheat grain Se content among different counties. 69.2% of wheat grain Se content belonged to moderate or high selenium levels mainly due to the relatively high bioavailability of selenium in the region. Available Se content in soil accounted for l 1.6% of total selenium content further verified this. There was a significant spatial heterogeneity in the content of selenium in soil and wheat grain, which must be taken into consideration in the biofortifieation practice.