北京市房山区富硒土壤调查与评价

采用全国A层土壤背景值累频分级法来划定土壤硒的丰缺分级值，确认房山区存在富硒土壤。对于不同地貌类型土壤调查结果发现：硒含量平均值按照剥蚀堆积台地、洪积平原、冲积洪积平原、冲击平原依次递减，并且土壤硒主要富集于表层土壤，向地下深部硒的含量快速降低。土壤硒的含量受山区成土母质的影响较大，且偏碱性、富含有机质的表生环境有利于土壤硒富集。富硒区小麦和蔬菜水果中硒的分布与土壤硒含量具有良好的空间对应关系，其元素含量属于安全食品标准。

THE INVESTIGATION AND EVALUATION OF SELENIUM-RICH SOIL IN FANGSHAN DISTRICT OF BEIJING CITY

Based on soil pool-rich standard classification for selenium from ＂National A Layer Soil Background Cumulative Frequency Classification Method＂, the authors hold that selenium-rich soil exists in Fangshan District. Se content of soil from different physiogno- mies shows that the mean value of Se decreases in order of erosion accumulation platform, pluvial plain, alluvial-pluvial plain and allu- vial plain, and the Se element is mostly concentrated in the top soil, and decreases rapidly toward the depth. The Se content of soil is considerably influenced by soil organic matter of mountain areas, whereas the meta-alkaline and organic matter-rich supergene environ- ment helps to the enrichment of Se in soil. The selenium content of winter wheat and vegetations has good relationship with the soil se- lenium content, and is lower than the standard content stipulated in the National Specification of Food and Vegetation.