Hands-On Science

The City from the Ooze

lake view What do you think of when you think of a lake in the country? Maybe you think of things that live in it and around it: fish, ducks, trees, and the mosquitoes that are buzzing around the shore.

What about the residents of the lake environment that are too small to see? A drop of lake water is filled with all sorts of microscopic life. But what about the muddy shores of the lake? Could there be more to them than some plants and wet dirt? lake shore

Let's look at how some lakeshore mud can be turned into The City from the Ooze...

What You’ll Need

materials The main thing that you’ll need is a nice country lake that you can collect some mud from. You’ll also need:
  • A small bucket to collect mud in
  • A shovel or spade to pick up the mud with
  • A 1- or 2-liter clear plastic soft drink bottle
  • A raw egg
  • A little shredded newspaper
  • Some chalk stubs
  • A bowl or pan to mix muck in
  • Plastic wrap
  • A rubber band to go around the soft drink bottle
  • An adhesive label or masking tape

Cut off the top of the soft drink bottle, and save the top to use as a funnel. Also, if the bottle has a label on it, remove the label (soaking it in warm, soapy water will help).

This project is a bit messy, so you may want to do most of the work outside. If you have to work indoors, spread some newspapers around to protect the floor and table, and keep a window open, because it will get smelly!


Field Trip!

Gather up your bucket and shovel, and head for the beach! On the way, be sure to pay attention to your environment.
bee Can you identify the plants and trees that you see? If you are out in the country away from people, and you walk along quietly, you will see birds and maybe some animals, too. Taking a camera along is always a good idea.

When you get to the lake shore, look around for the best mud you can find. What mud is good mud? Well, pond scum in the vicinity is a good sign that things are living there. When you dig in with the shovel, take a sniff for that nice rotten egg smell that means sulfur is present. Smelly, slimy mud is what we’re after....

ooze gathering Now, fill your bucket with mud (be sure to get some water, too). Try to avoid getting plants, roots, or other large stuff in the bucket, because it will just be in the way. Make sure that you have more mud and water in your bucket than you will need to fill your soda bottle, then you can pack up and head home with your bucket of muck.

Who’s in the Neighborhood?

drawing 2

If all goes well, your Ooze City will develop several layers with different colors. The colors identify the type of microbe that is living in that neighborhood of the city:

The way that your city turns out will depend on what sorts of microbes you picked up in your mud collection, and how well they liked the environment that you created for them.

What’s Going On?

What are the differences in the microbes that makes them happy at different levels of Ooze City? Finding the answer to that question isn’t easy, but fortunately some scientists have studied the matter and have figured out what’s going on. Scientists actually call Ooze City a “Winogradsky column” because a microbiologist in the 19th century, Sergei Winogradsky, built these cities and studied them to learn how microbes live and work together. Here’s a little bit of what he found.

Imagine that you are microbe-size, and you have an elevator that runs from the air above Ooze City all the way to the lowest level. What is it like at the top floor, just above the water?


You may have noticed that some of the steps in creating Ooze City were a little vague. How much newspaper and chalk should be added? How close to the light should the bottle be? Why not use fluorescent lights? What temperature is best?

If you are building several Ooze Cities with classmates or for a science project, try experimenting with the conditions to see what works and what doesn’t. You may find that some of your Ooze City residents like one set of conditions, while other Ooze City microbes prefer another set.

Other things you can try:

Effects on Earth’s Environment

Maybe you’ve wondered how Ooze City ties into physics, since all of the other projects have something to do with atmospheric or space science. The fact is that microbes, like the residents of Ooze City, have an enormous effect on Earth’s atmosphere and environment, but nobody fully understands exactly what the effect is!

Scientists are concerned about the ways that human pollution may affect our environment, since we dump so many chemicals into the air and water. Atmospheric scientists are especially concerned about carbon dioxide, methane, and other gasses that could change how much heat the atmosphere absorbs from the sun. If the temperature of the atmosphere changes by even a few degrees, it could have a big effect on how crops grow, how often we have hurricanes and typhoons, and many other things.

Microbes are an important part of the picture, and one that we don’t understand very well. As we've seen in Ooze City, some of the microbes take in oxygen from the air, and others generate hydrogen sulfide which escapes into the air. Microbes also take in carbon dioxide, and give off methane. These microbes are everywhere ... in the oceans (plankton), lakes, marshes, wetlands, forests, and just about anywhere that you find moist soil, so the amount of gasses that they use or produce could be the key to understanding how human pollution will affect the Earth.

Some of the questions that scientists want to understand about the way natural Ooze Cities affect the environment include:

This activity came from Alaska’s Poker Flat Research Range rocket-launching facility.

Regrettably, we can no longer find the original. Apparently, you are to mix the egg, newspaper, and chalk bits into the muck in your bottle before capping it with plastic wrap and rubber band, and placing it in sunlight. We’d love to hear from anyone who can find the original or give us more details of how this experiment worked for them!

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