28. This is caused by oxygen reacting with iron sulfide in the soil and it produces iron oxide, or rust.

这些土壤的颜色是由氧气和土壤中的硫化铁发生反应形成的，这个反应生成氧化铁，俗名铁锈。

If you pull up a Spartina, you might even notice some reddish mud on some of the roots, this is caused by oxygen reacting with iron sulfide in the soil, and it produces iron oxide or rust.

如果你拔起一棵米草，你甚至可能会注意到一些根部有一些微红的泥土， 这是由于氧气与土壤中的硫化铁反应， 产生氧化铁或铁锈。