西藏自治区隆子县土壤硒地球化学特征及影响因素

硒是人体必需的微量元素之一，土壤中的硒含量与人体健康关系密切。调查土壤硒含量分布特征、圈定富硒土壤资源分布区、查明土壤硒含量影响因素，对于推动富硒土地资源开发利用、发展富硒农牧产业、预防地方疾病等均具有重要意义，也可为土壤硒背景值研究提供参比资料。土壤硒是当前热点研究领域，国内外对土壤硒研究已有很多，然而西藏地区有关土壤硒方面研究资料非常有限。本文选择西藏自治区隆子县重点耕地区为研究对象，系统采集表层土壤、垂向剖面、岩石样等样品，采用原子荧光光谱法(AFS)、容量法(VOC)、电感耦合等离子体发射光谱法(ICP-OES)等方法测定土壤中的硒、有效硒、有机质、全磷等含量指标，利用统计方法对研究区土壤硒、有效硒等地球化学含量特征及影响因素进行初步探讨。结果表明：①研究区表层土壤硒含量范围为0.14~1.51mg/kg，中位数为0.44mg/kg，是西藏土壤硒平均值(0.15mg/kg)的2.9倍和中国表层土壤Se平均值(0.26mg/kg)的1.5倍，表明研究区表层土壤中全硒含量较高；研究区表层土壤中有效硒含量范围为0.8~26.8μg/kg，中位数为9.2μg/kg，土壤有效硒占全硒含量的0.21%~5.79%；土壤硒含量高于0.4mg/kg为界限值，研究区总面积的77.25%符合富硒土壤划定标准，表明富硒土壤资源丰富；②研究区广泛分布的涅如组(T3n)和日当组(J1r)地层发育土壤中硒含量较高，中位数分别为0.44mg/kg和0.41mg/kg，土壤硒含量与地质背景密切相关；土壤理化性质包括有机质、pH、TFe2O3等对土壤全硒含量影响不显著，但土壤有效硒与有机质、pH、N、P、碱解氮、有效磷、速效钾、阳离子交换量(CEC)呈显著正相关；此外，铁氧化物(TFe2O3)对有效硒含量也有一定控制作用；③土壤垂向剖面研究发现，土壤硒含量还与表生富集作用有关。综合认为，研究区土壤Se含量较高，富硒土壤资源丰富，可以通过土壤养分管理，进一步提高土壤硒生物有效性。

Geochemical Characteristics and Influencing Factors of Soil Selenium in Longzi County,Tibet Autonomous Region

BACKGROUNDSelenium (Se) is one of the essential trace elements in the human body, which has many biological functions. Insufficient or excessive intake of Se will cause a series of diseases. The trace element Se in the human or animal body cannot be synthesized by itself, but can only be supplemented from external food. Se in food, especially in plant food, mainly comes from soil. Therefore, Se in soil is closely related to human health and animal growth. China is a country lacking in soil Se content, especially in Tibet. The background value of soil Se in Tibet is significantly lower than that of surface soil in China. Therefore, local diseases such as Kashin-Beck disease are common in some areas of Tibet due to long-term insufficient intake of selenium. It is of great significance to investigate the distribution characteristic of soil Se content, delineate the distribution area of selenium-enriched soil resources and determine the influencing factors of soil Se content for promoting the development and utilization of selenium-enriched land resources, develop Se-enriched industries and prevent local diseases. This will also provide reference data for the research of soil Se background value.