安康南部大巴山区硒过剩土壤分布及来源研究

Distribution and Source of Selenium Excess Soils in Daba Mountain Area of Southern Ankang

为了查明安康市南部大巴山区硒过剩土壤分布特征和来源,为安康富硒土壤安全、合理开发和规划打下基础,采集了研究区岩石、土壤样品,测定了硒含量,分析了岩石、土壤硒含量分布特征及其相互关系。结果表明:研究区土壤硒含量在0.00007~36.69 mg/kg,均值0.84 mg/kg,变幅大,呈现两条NW—SE向高硒区,高硒土壤面积占73.09%,硒过剩土壤以斑块、斑点状分布,面积占0.91%;岩石硒含量范围0.005~68.75 mg/kg,均值5.83 mg/kg,变幅大,处于深水沉积环境下的震旦系上统灯影组和两期大规模海侵阶段的寒武系下统鲁家坪组和志留系下统斑鸠关组岩石硒含量均值明显高于其他岩组,板岩、硅质岩、白云岩、正长斑岩硒含量较高,尤其黄铁矿和石煤硒含量更高;岩石、土壤硒含量表现出强烈的正相关性。硒过剩土壤以斑块、斑点状分布于紫阳县双安镇、汉王镇、焕古镇、洞河镇、蒿坪镇、瓦庙镇、麻柳镇、毛坝镇、高滩镇、界岭镇,岚皋县佐龙镇、城关镇,镇坪县城关镇。土壤硒主要来源于岩石,震旦系上统灯影组含硒量高的碳质板岩,寒武系下统鲁家坪组含硒量高的黄铁矿、含碳板岩、碳质板岩、硅质板岩、含碳硅质岩、硅质岩和志留系下统斑鸠关组硒量高的石煤、含碳板岩、含碳硅质板岩是硒过剩土壤的主要来源。

In order to disclose the distribution characteristic and sources of selenium(Se)excess soils in Daba Mountain area of southern Ankang and lay the foundation for the rational development and planning of Se-enriched soils,rock and soil samples were collected and Se contents were determined,and the distribution characteristics and correlation between Se contents in rocks and soils were analyzed.The results show that soil Se is ranged from 0.00007 to 36.69 mg/kg with an average of 0.84 mg/kg.Two NW–SE oriented high Se regions are found there.Se-enriched soil is occupied 73.09%of the total area,and Se excess soils are distributed in patches and spots with an area of 0.91%.Rock Se is ranged from 0.005 to 68.75 mg/kg with a mean of 5.83 mg/kg.Rock Se are obviously higher in the upper Sinian Dengying formation and the lower Cambrian Lujiaping formation and the lower Silurian Banjiuguan formation in the deep-water sedimentary environment than in other formations.Se is higher in slate,siliceous rock,dolomite and syenite porphyry,especially in pyrite and stone coal,and rock and soil Se contents have significant positive correlation.Se excess soils are distributed in patches and spots in Shuang’an,Hanwang,Huangu,Donghe,Haoping,Wamiao,Maliu,Maoba,Gaotan and Jieling in Ziyang County,Zuolong and Chengguan in Langao County,Chengguan in Zhenping County.Soil Se is mainly derived from rocks,and the main sources of Se excess soil are carbonaceous slate with high Se content in the upper Sinian Dengying formation,Se-rich pyrite,carbonaceous slate,carbonaceous slate,siliceous slate,carbonaceous siliceous rock and siliceous rock in the lower Cambrian Lujiaping formation,Se-rich stone coal,carbonaceous slate and carbonaceous siliceous slate in the lower Silurian Banjiuguan formation.