Yutangba village, located in the northern part of Shuanghe Town of Enshi City in the SWof Hubei Province, China, is the unique location in the world where a sudden incidence of Se poison-ing took place in 1963. It is one of the most typical high-Se areas in Enshi Prefecture, and thus it isselected as our study area. The results from studies show that native Se, which varies morphologicallydue to different mechanisms, has been discovered within the abandoned stone coal spoils and Se-richcarbonaceous siliceous rock. Krutaite( CuSe2), mandarinoite( Fe2(SeO3) 3) and other Se minerals arealso found. In the black Se-rich rocks of Yutangba, Refractory-Se and Organic-Se are predominant,the others are sulfide or selenide-Se, elemental Se and available Se, respectively. The processes offorming elemental Se is not only the key phase for Se transforming among the different Se fractions inSe-rich rocks, and also for Se releasing, mobilizing and transporting during Se-rich rocks weathering.The Se-rich carbonaceous siliceous rock and carbonaceous shale of the Permian Maokou and Wujiap-ing are the predominant factors for Yutangba to develop into a high-Se area. The manners of cultiva-ting activities and life of local inhabitants are the main factors that cause Se to accumulate in foodchain, and high risk of Se poisoning occurrence is mainly controlled by Se content in corn (mainfood). Se, Yutangba is still a high risk area to villagers, where Se poisoning is possible to take place.%选取迄今世界上唯一发生过人群硒中毒爆发性流行的地区--湖北恩施渔塘坝为研究区.研究结果表明,在渔塘坝废弃的"石煤堆"和富硒岩段,首次发现了多形态、多成因的自然硒和硒铜蓝、水硒铁石等硒的独立矿物,证实了富硒岩石中自然硒的存在.富硒岩石中硒主要以有机结合态和残渣态硒为主.元素硒的形成过程是影响风化岩石硒释放、转化和迁移的重要因素.富硒岩石是渔塘坝高硒区形成的直接因素.硒中毒的高风险主要受玉米硒(主食)的控制,渔塘坝目前依然是硒中毒可能发生的高风险区.
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