While researching biosheens for the last post, I came across iron bacteria as a possible organism that creates them. When I looked them up, I saw that they produce a brilliant orange cloud in the water which I didn’t see around the bridge where I witnessed the biosheen. So I went back out to the arboretum to see if I could find this nebulous, tangerine dream.
Iron is the fourth most common element in the earth’s crust and vital to life. The biogeochemical cycle of iron through the biosphere, atmosphere, lithosphere, and hydrosphere is often cleverly referred to as the Ferrous Wheel. Iron is constantly cycling through the environment in two states, ferrous iron (Fe2+) and ferric iron (Fe3+). Ferrous iron has a positive charge of plus two because it has lost two electrons and ferric iron has a positive charge of three.
This orange cloud is a result of oxidation (losing electrons) by iron bacteria converting ferrous iron (Fe2+) into ferric iron (Fe3+). The most common acceptor of this electron is oxygen. Ferrous iron is highly dissolvable in water in anerobic (oxygen-free) environments. Where this water leaches out into aerobic (oxygen-rich) environments, iron bacteria thrives. Iron bacteria obtains energy when it transfers an electron from ferrous iron to oxygen creating ferric iron which is insoluble in water. This insolubility creates a beautiful orange soup of ferric iron and iron bacteria swirling around in the water.
For me, the ferrous wheel was a fascinating and dizzying ride full of science that I spent lots of time reading about. The importance of iron will surely find its way into more posts in the future. For example, iron is vital for the production of chlorophyll which is a key component for photosynthesis. For now, I feel this amount of information is enough to get you started doing some research of your own, good luck.
Also part of this story, I put my hand down in the water to see how it felt. It looked slimy, but I was unable to feel it. I expected it to cling to my hand when I pulled it out, but it didn’t stick to my hand at all. I scooped up some in a container to have a look. I immediately noticed that I had caught a small organism and it was excitedly darting around. That creature was me swimming around in this nebulous, tangerine dream—it was a metaphor, a reminder of a world so unbelievable in its infinite complexity and bewilderment.
Nature is an inexhaustible source of wonder. I hope to see you out there!
