How do oil spills affect aquatic plants?

Topic Information :  Effects of oil spills 

This science fair project was performed to find out how oil spills will affect aquatic plants. Testing was done using hydrilla plants in water with and without a layer of oil covering the surface.

Oil is an organic fluid that has a lower density than water. When oil is spilled on water, it will float on the water surface and form a thin layer. Oil is not soluble in water. This thin layer of oil on the water surface is called sheen and it can kill the aquatic animals and plants that live beneath the water if it is not removed quickly.

The presence of oil on the water surface will blocks sunlight and prevents air from reaching the plants that live in the water. This will prevent the plants from producing food through photosynthesis. Without photosynthesis, the plants will not be able to grow, germinate and produce oxygen. If this condition persists, the plants will eventually die.

Aquatic animals are also not spared by oil spills. They are affected through physical contact, inhalation, ingestion and absorption of oil. The oil also contaminates the algae, plankton, fish eggs and larvae that are food for the smaller fishes. These smaller fishes are eventually eaten by the bigger fishes, birds, other animals and humans. The food chain becomes contaminated and everyone becomes affected.

Organic fluid: made up of two or more parts or ingredients

Density: A measure of the amount of matter contained by a given volume. 

Soluble: Able to be dissolved

Sheen: Brightness; splendor; glitter. 

Photosynthesis: is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight.

Hypothesis

The plant living in the beaker with a layer of oil on the surface will not be able to perform photosynthesis, and will hence stop producing oxygen.

Materials

The materials required for this science fair project: 

-    2 hydrilla plants (of approximately equal size) 

-    2 beakers

-    2 test tubes

-    2 funnels

-    1 liter of water

-    1 ruler (measuring 150mm long) 

-    10ml of engine oil

Variables

For this science fair project, the independent variable is whether or not there is a layer of oil on the surface of the water. The dependent variable is the amount of oxygen collected in the test tube.

Controls

The amount of water that the two plants have.

The amount of oil---------------

Procedure

1.  This is determined by measuring the length of the air trapped in the test tube with the ruler. The constants (control variables) are the size of the hydrilla plant, the size of the beaker, the amount of water and the size of the test tube used for air collection.

2.  Fill each of the 2 beakers with 300ml of water and place one hydrilla plant inside each beaker. Next, invert the funnels and place them over the hydrilla plants in the beakers. The plant should be positioned inside the inverted funnel as shown in Figure 1 below. 

3.  Fill 2 test tubes with water and place them over the outlet of the funnels, as shown in Figure 1. There should not be any air inside the inverted test tubes before the start of the experiment. 

4.  Pour 10ml of engine oil into one of the beakers. The oil will spread evenly to form a thin layer. 

5.  Observe the amount of air collected in the test tubes to determine the level of  oxygen produced by the hydrilla plants. Using a ruler, measure the height of the oxygen in the test tubes. Record your observations every hour for the next 5 hour.

Result

The hydrilla plant in the beaker with a layer of oil stopped producing oxygen after 3 hours, while the plant in the beaker without the oil continued to produce oxygen even after 5 hours.


References

How does oil affect the growth of an aquatic plant? http://www.ehow.com/about_6127348_oil-affect-growth-aquatic-plant_.html

The detrimental effects of oil spills on our environment - http://www.articlesbase.com/environment-articles/the-detrimental-effects-of-oil-spills-on-our-environment-1043176.html

The effects of oil spills on aquatic life and the environment - http://pollution-control.suite101.com/article.cfm/the-effects-of-oil-spills-on-aquatic-life-and-environments.