Activity: Blue Ice
Materials:
Ice cubes made with LOTS of dark food dye (blue, purple, green, etc.)
Clear demo tank (something thin and see through that can hold water)
Procedure:
- Make the ice cubes ahead of time and have them ready for the demo.
- Fill the demo tank with luke warm tap water.
- Put a piece of white colored paper behind the tank for better visibility.
- Put an ice cube in the tank.
- If done correctly, the ice cube will melt and the color from the cube will drop to the bottom of the tank. Water, just before it freezes or just after it melts, is at its heaviest. The water from the cube will drop, due to its heavier nature, and will then fan out to the edges of the tank, where it will mix with the other water and the temperatures will then even out. The water will then rise up the sides of the tank.
Background:
The higher density of melting water has a tendency to pull surface pollutants down to the depths of the ocean, where they will mix with whatever else is in the ocean. This is a particular problem when you consider the melting polar ice caps and the increased dumping of pollutants into the ocean.
Ocean pollution can come in many forms. It can result from oil tankers spilling oil, boats sinking, or even ocean litter. Large or small, ocean debris can cause problems for both sea life and humans. Garbage gets into the ocean when people dump it off boats and litter beaches, but it also can reach the ocean from rivers, storm drains, or ocean dumping of industrial waste. Eventually all water on land flows toward the sea.
Besides being ugly to look at, a lot of ocean debris, like plastic bottles, bags, Styrofoam peanuts, old fishing wire, and nets are quite dangerous to wildlife. Whales and dolphins eat plastic bags thinking they are squid. Sea turtles and ocean birds eat Styrofoam peanuts that block their digestive tracts. Abandoned fishing nets tangle and drown thousands of seals every year. Even human swimmers and divers can get tangled in dumped nets and drown.
Other dangerous ocean pollutants include human sewage, oil spilled at sea and medical waste dumped in the ocean. These hazards endanger both ocean beaches. Fish and shellfish become so toxic from eating pollutants that they are not safe for people to catch and eat either.