Speaker 1: Welcome to brain Stuff, a production of I Heart Radio. Hey,
Speaker 1: brain Stuff, Lauren Vogel bomb here. Everybody needs nitrogen, but
Speaker 1: as far as non negotiable life sustaining elements go, it's tricky.
Speaker 1: Living things require nitrogen for their cells to function. And furthermore,
Speaker 1: we're virtually steeping in the stuff since our atmosphere is
Speaker 1: made up of seventy percent nitrogen gas. However, there's a catch.
Speaker 1: It's a water water everywhere, but not a drop to
Speaker 1: drink kind of situation. Although nitrogen is floating basically everywhere,
Speaker 1: it's not terribly abundant in the Earth's crust, and it's
Speaker 1: incredibly difficult for living things to capture atmospheric nitrogen and
Speaker 1: use it for their purposes. It's like having a bucket
Speaker 1: full of Icelandic money and say Minneapolis, where you can't
Speaker 1: spend it. And we spoke by email with Jesse Moates,
Speaker 1: a PhD candidate at the Odum School of Ecology at
Speaker 1: the University of Georgia. She said nitrogen is a major
Speaker 1: part of amino acids, which are the building blocks of
Speaker 1: proteins and nucleic acids such as DNA. In addition to
Speaker 1: needing nitrogen for proteins and plants. It's a main component
Speaker 1: of chlorophyll, which makes it crucial for photosynthesis. Since nitrogen
Speaker 1: is a limited resource on this planet, a nitrogen atom
Speaker 1: doesn't spend much time doing nothing when it's in a
Speaker 1: form that living things can use. Scientists called nitrogen in
Speaker 1: this form fixed. A fixed nitrogen is taken up by plants,
Speaker 1: which are eaten by animals, which eat other animals, which
Speaker 1: die and decompose and release nitrogen back into the ecosystem
Speaker 1: to be worked on by bacteria or plants. And this
Speaker 1: is the cycle of a nitrogen atom on Earth, and
Speaker 1: its journey starts either very quietly or with a humongous bang.
Speaker 1: The step one in the cycle is nitrogen fixation. Believe
Speaker 1: it or not, Lightning and bacteria are the two things
Speaker 1: primarily responsible for turning atmospheric nitrogen into nitrogen that living
Speaker 1: things can use. Atmosphere nitrogen is very stable, so it
Speaker 1: takes an incredible amount of energy to convert it to
Speaker 1: a different form. If you've ever wondered why your outdoor
Speaker 1: plants seem happier after a thunderstorm than they do when
Speaker 1: you turn a sprinkler on them, there's a reason for that.
Speaker 1: Lightning electrifies atmospheric nitrogen and water to reconfigure them into
Speaker 1: ammonia and nitrates. This falls to the ground is rain,
Speaker 1: where plants slurp it up and use it for their
Speaker 1: biological processes. On the other end of the spectrum, the
Speaker 1: most common way nitrogen is made available to organisms is
Speaker 1: when atmospheric nitrogen is fixed by bacteria, and some of
Speaker 1: which live free in the soil, and others of which
Speaker 1: enjoy a symbiotic relationship with certain plant species. Lagoons like peas, clover,
Speaker 1: and peanuts have little nodules on their roots that attract
Speaker 1: bacteria that convert stubborn atmospheric nitrogen into ammonia or ammonium,
Speaker 1: which can then be used to power the plant. Step too,
Speaker 1: is nitrification. Ammonia in the soil can be used directly
Speaker 1: by plants, but it's all so a step in the
Speaker 1: process of nitrification, through which specialized bacteria and other microorganisms
Speaker 1: convert ammonia into nitrite and then pass it off to
Speaker 1: an entirely different set of micro organisms that further oxidize
Speaker 1: the nitrate into nitrate. This process is slow, but it's
Speaker 1: the way that nitrogen is built as a nutrient. In
Speaker 1: soil and aquatic and marine environments. Terrestrial plants, for instance,
Speaker 1: can absorb ammonium and nitrate through their root hairs. The
Speaker 1: organisms that specialize in nitrification are also important in treating
Speaker 1: municipal wastewater, and anyone who's kept an aquarium knows how
Speaker 1: important those organisms are to keeping your water, fish and
Speaker 1: plant friendly. Step three is a monification. Everything living eventually
Speaker 1: dies and the nitrogen a particular organism was using when
Speaker 1: it shuffled off. This mortal coil is taken to hand
Speaker 1: by bacteria that turned the nitrogen rich corpse into ammonium,
Speaker 1: which can be picked back up by plants and used again.
Speaker 1: The step four is D nitrification. It's possible to convert
Speaker 1: bioavailable nitrogen into atmospheric nitrogen again, and that process is
Speaker 1: called unitrification. Nitrification is performed by bacteria and other microorganisms
Speaker 1: that can tolerate oxygen. Not all microorganisms can. In the
Speaker 1: case of D nitrification, certain anaerobic bacteria that don't need
Speaker 1: oxygen convert nitrate to nitrogen gas, which floats up into
Speaker 1: the atmosphere and plays hard to get again until some
Speaker 1: lightning or crafty bacterium comes along and ropes it. Back
Speaker 1: into the first step of the nitrogen cycle yet again.
Speaker 1: Today's episode was written by Justesceline Shields and produced by
Speaker 1: Tyler Klang. For more on this and lots of other
Speaker 1: cyclical topics, visit how stuff works dot com. Brain Stuff
Speaker 1: is production of by Heart Radio. Or more podcasts to
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Speaker 1: or wherever you listen to your favorite shows.