Investigating the surface of the sea
- Float a needle on the surface of a glass of water. Add a drop
of detergent to the water and observe what happens. How could
detergents harm the delicate skin of the sea?
- Observe calm water from an overlook or a boat to see windrows
on the surface of the sea or a lake. In a protected area, like
a marina, look to see what pollutants you might find on the surface
of the water. Are there oil slicks? Floating trash? Discuss how
these might harm the skin of the sea.
- Get some wide clear sticky tape (the kind used in packing).
Find smooth surfaces (glass, metal, automobiles, tiles) in different
indoor and outdoor environments. The surfaces should not have
been cleaned or washed recently. If you can, find out how long
it has been since the surface was washed or wiped. Cut a strip
of sticky tape about 70-mm long and fold over one end about 5-mm
to form a tab. Place the tape over the surface and smooth it down,
then lift it off again along with the dust, dirt and "fallout"
from the surface. Write down the time and exact location of the
sample on a piece of paper and stick the tape onto the paper.
Collect samples from vertical and horizontal surfaces, upwind
and downwind of urban areas (perhaps students living in different
parts of the community can sample near their homes to get a wider
- In the classroom, begin a "fallout" loose-leaf notebook
of the samples. Compare samples. Where does the heaviest fallout
come from? What colour is it? Can you guess where the material
came from (a farm, a fire, an industrial activity, heavy motor
vehicle traffic, construction).
- Discuss how chemicals put onto farms and gardens to kill unwanted
plants or insects could become bound up in dust particles during
dry periods. How would these effect the plants and animals that
live at the sea's surface when the dust blows out onto the ocean?
- Collect some fall-out with a rubber or plastic blade. Place
some in a glass of water and observe what happens to it. Does
it float? Does it form an oil slick? Is it easily soluble in water?
If not, will it dissolve easily when detergent is added to the
water? (Form 6 and 7 students might investigate other physical
parameters such as pH, toxicity to micro-organisms, or even heavy
- Place a clean white, uncovered plastic container (an ice-cream
container works fine) in an out of the way place in the classroom,
and in an open, but covered, shed where air, but not rain, and
pass the container. Write "Science Experiment do not clean
or move" on the outside with a felt-tip pen. After four weeks,
examine the inside of the container. Using a plastic or rubber
blade, scrape any dust or fall out into a single pile (be careful
not to blow on it). Place the sample on a piece of paper and seal
it in place with clear sticky tape. Record the time and place
the container was set out and collected. Note if the weather was
dry or wet during the experiment. Repeat the experiment at a later
time, perhaps when the weather has been different.
- Design a rotating drum to sample the surface film from a boat.
Dr. Hardy's surface film collector has a Teflon-coated drum towed
alongside the research vessel. Organic film adheres to the drum
and is continuously scraped by a squeegee into a large glass jar.
- Design a special plankton net with pontoons that can skim
just the top few centimetres of the skin of the ocean to collect
surface-dwelling crustaceans, fish eggs and larvae.
- Make (or buy) a plankton net and collect some plankton from
the surface of the water in a protected embayment (or from a boat).
During algal blooms, the phytoplankton
is so thick one can simply collect some by scooping them up in
a jar. Use a microscope to examine the plankton and record what
you find. Look for larvae and fish eggs. Discuss the specialisation's
of these organisms that enable them to survive in the upper zone
of the sea. Consider the impact of various environmental pollutants
on these creatures and what this might do to the ability of the
creatures to maintain their populations.