Pond Life

Black line represents original
air bubble. Photosynthesis
in the right tube has created an
oxygen bubble.

Test tubes containing pond
water. Tube on the right
received some fertilizer.
 

To study eutrophication I set up a small scale experiment using pond water from the wetlands on the school property. This area is surrounded by athletic fields which are treated with fertilizers. In the spring and summer there is quite the alga bloom and the nasty smell of decaying matter.

One of my colleagues set up a large scale experiment in two little fish bowls, adding fertilizer to one of the bowls. After a week or so there was clearly a difference between the two bowls. The one with the fertilizer was green and becoming greener with each passing day. I did the same except in the test tubes adding a little bit of baking soda to ensure a carbon dioxide source for the growing algae. This piggy backs on my previous post about the Nitrogen cycle. The excess use of fertilizer results in the disruption of the nitrogen cycle and the introduction of excess nitrogen into bodies of water resulting in the overgrowth of algae and the depletion of oxygen in the water causing death among other species in the water. We need to rethink our obsession with thick green lawns and how to obtain them.