摘要

<正>碳是生命物质中的主要元素之一,是有机质的重要组成部分。碳元素在大气、陆地和海洋等各大碳库之间不断循环变化,达到一个相对平衡的状态。Carbon is the fourth most abundant element in the universe, and is absolutely essential to life on Earth. In fact,carbon constitutes the very definition of