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Nutrient cycles connect past, present, and future forms of life. Some of the carbon atoms in your skin may once have been part of a leaf, a dinosaur’s skin, or a layer of limestone rock. Your grandmother, Attila the Hun, or a hunter-gatherer who lived 25,000 years ago may have inhaled some of the oxygen molecules you just inhaled.

翻譯：營養素循環在我們生活中連接了過去，現在，和未來。例如：或許在我們皮膚上的碳原子有可能曾經是葉子的某一部分，或是恐龍的皮膚，更或者是石灰岩的表層。而或許我們現在所吸的氧氣，也有可能是祖先或住在25,000年前受獵者們所吸的氧氣。