Excavation and trace element analysis indicates: Jehol biota experienced mass mortality and rapid burial; toxic gases of the volcanic activities are the main factors of biological catastrophic event.

化石发掘和微量元素分析表明，热河生物群经历了集群死亡和快速掩埋，火山活动的有毒气体是生物灾难事件的主要因素。

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In the nature, arsenic is one of the wide distribution toxic trace element and carcinogen.

砷是一种具有毒性且分布相当广泛的微量元素之一，并且已被认定为是致癌物质之一。

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