宣恩县西北部土壤硒锌含量特征及其生物有效性研究

测定宣恩县西北部表层土壤及茶叶、水稻、玉米、土豆中硒和锌的含量,研究其分布特征及土壤中硒、锌的生物有效性。结果表明,宣恩县西北部表层土壤中硒含量处于高硒水平,锌含量也处于丰富水平,且土壤硒、锌含量空间分布不均匀,这主要与其区域地质背景有关。土壤中硒、锌元素形态主要为强有机结合态与残渣态,很难以离子形态释放出来,不同形态硒变异系数随着硒惰性增强而增大,不同形态锌变异系数随着锌惰性增强而减小,硒在全区的生物易利用性较锌稳定。土壤中各形态硒、锌含量与其全量、pH值、有机质等存在不同程度的相关性。农作物可食部分对土壤硒、锌元素富集能力强弱分别为玉米>茶叶>水稻>土豆、茶叶>玉米>水稻>土豆。硒在不同农作物中自根茎至叶片或籽实富集系数依次降低,锌在茶叶叶片及玉米籽粒中富集系数高于其根部或者茎部。

Characteristics of Soil Selenium and Zinc Content and Its Bioavailability in Northwestern Xuan'en County

In this study,the contents of selenium and zinc in surface soil,tea,rice,maize and potato in the northwest of Xuan'en County are determined,and their distribution characteristics and bioavailability are studied.In general,the selenium content in the surface soil of northwest Xuan'en County is at a high level of selenium,and the spatial distribution of Se and Zn in the soil is not uniform,which is mainly related to the regional geological background.The forms of selenium and zinc in the soil are mainly in strong organic binding state and residue state,and it is difficult for ions to be released.The variation coefficients of different forms of selenium increase with the increase of selenium inert state,while the variation coefficients of different forms of zinc decrease with the increase of zinc inert state.The bioavailability of selenium in the whole region is more stable than that of zinc.The contents of Se and Zn in soil are correlated with the total amount of Se and Zn in soil,pH value and organic matter in different degrees.The absorption capacity of selenium and zinc in edible parts of crops is as follows:corn>tea>rice>potato,tea>corn>rice>potato.The enrichment coefficient of selenium in different crops decrease from the bottom to the top,while the enrichment coefficient of zinc in tea leaves and corn grains is higher than that in roots or stems.