北京房山南部地区富硒土壤生物有效性特征及来源

Bioavailability and source analyses of Se-enriched soil in the south of Fangshan district,Beijing

依据北京房山南部地区详细的土壤地质调查数据,通过土壤有效Se的累频分级,发现土壤Se全量与有效Se在空间分布上呈现很好的一致性。进一步的相关分析表明,表层土壤中元素C、N、S、有机质及重金属元素Cd、Pb、Cu、Zn的含量与土壤Se含量相关性较高,与元素P含量及pH值的相关性较低。通过对研究区普遍种植的6种农作物、经济作物和蔬菜中Se与对应根系土中Se含量的相关性研究,发现小麦和玉米的富Se能力最强,是提升农产品附加值的备选品种。土壤剖面Se全量的垂向分布特征表明,Se属于表聚型,且随着远离山前,Se有效态所占比例越来越高,难迁移态中的比例越来越低;最后结合地质学、大地构造学、岩石地球化学等方面综合论证,得出研究区富Se土壤中的Se主要来自杨家屯煤系地层,途径以周口店河和马刨泉河为主,大石河为辅。

According to the detailed soil geological survey data in the south of Fangshan,Beijing,it is found that the total amount of soil selenium is consistent with the available Selenium in spatial distribution through the cumulative frequency classification of soil available Selenium.Further correlation analysis showed that the content of elements C,N,S,organic matter and heavy metal elements Cd,Pb,Cu,Zn in surface soil had a high correlation with the content of selenium in soil,and a low correlation with the content of element P and pH value.Through the relevant study on selenium in six crops,cash crops and vegetables planted in the study area and selenium content in corresponding root soil,it is found that wheat and maize had the strongest Selenium enrichment ability and were the alternative varieties to enhance the added value of agricultural products.The vertical distribution characteristics of total selenium in soil profile show that selenium belongs to surface accumulate type,and with the distance from the mountain front,the proportion of effective selenium is higher and the proportion of difficult to migrate is lower;Finally,combined with the comprehensive demonstration of geology,geotectonics and petrochemistry,it is concluded that the selenium elements in the selenium rich soil in the study area are mainly from the coal measures strata of Yangjiatun,and the main ways are Zhoukoudian River and Mapuiquan River,supplemented by Dashihe River.