【摘要】 渔塘坝北部山区地势较高的富硒碳质岩层,相对封闭地势较低的山间盆地,以及二者之间的两条山沟共同构成了一个相对比较封闭的高硒微域地球化学景观。其北部茅口组富硒碳质岩石的平均硒含量为1251.1±1218.8μg.g-1,是渔塘坝出露地层中最为富硒的。这些富硒岩石为渔塘坝中的土壤和植物提供了硒的间接来源,而导致渔塘坝高硒景观的形成,除了地形、气候因素之外,主要是当地居民活动直接干预的结果,特别是田地以火土(石煤熏土)施肥改良土壤。因此,如果说渔塘坝北部富硒碳质岩层的存在是高硒区形成的必然条件,那么人为的开挖"石煤"和不当的耕种方式则为硒的迁移和转化提供了充分条件。无论是自然或后生形成的高硒区,当硒的累积达到一定程度并突然释放时,硒中毒仍然可以发生。所以,恩施的高硒地区依然是硒中毒可能发生的高风险区。更多还原

【Abstract】 Yutangba,one of the most typical high-Se areas in Enshi Prefecture,is located in the northern part of Shuanghe Community about 81 km SE of Enshi City,Hubei Province,China.In order to better understand the origin of high-Se areas and the source of selenium,a comprehensive study in combination with geologic,topographic,climatic and anthropic factors was conducted.The results showed that Yutangba is essentially an almost closed valley-basin and has unique topographic features that have given Yutangba an integral geochemical landscape characterized as being high in Se.Selenium concentrations in Permian Se-rich carbonaceous rocks exposed in the northern part of Yutangba are highest in all Se-rich rocks,even up to 2669.9±809.6 μg·g-1.Se-rich rocks of the Permian Maokou and Wujiaping formations are the source of Se for soils and plants,but the high-Se development of Yutangba landscape,apart from topographic and climatic factors,mainly resulted from human activities such as cultivation manner and mining Se-rich rocks as a fuel or fertilizer,and this impacts on local environment on a long-term scale.So,if Se-rich carbonaceous strata can be a necessary condition for incidence of Se poisoning,human cultivating manner and activities such as mining Se-rich rocks as a fuel or fertilizer will provide a sufficient condition for transportation,bioavailability of Se and its accumulation.Whether primary high-Se areas such as Xintang and Shadi or those developed later,such as Yutangba,once soluble Se is accumulated to a certain extent and suitable environmental conditions exist,Se poisoning would occur again in some places of Enshi Prefecture.更多还原