Fighting Pollution with Bacteria You may think that all bacteria are harmful. Think again! Some bacteria are working to clean up the damage humans have caused to the environment. In 1989, the oil tanker Exxon Valdez hit ground off the coast of Alaska spilling millions of gallons of crude oil on to the beaches. There seemed to be no way to clean up this major oil spill that was both damaging to the ecology and the economy of the region. Then environmental scientists decided to try a new method, using bacteria found naturally along the Alaskan coast. These bacteria break down hydrocarbons (molecules found in oil) into simpler less harmful substances such as carbon and water. The problem was that there were not enough bacteria in beach sand to handle the huge oil spill. To increase the number of bacteria scientists decided to spray the beaches with a food chemical that acted as fertilizer to increase bacterial growth. Seventy miles of oil-soaked beaches were sprayed. Within 15 days the number of bacteria in beach sand tripled. The beaches that had been treated with the chemical were much cleaner than those that had not been sprayed. Without this bacterial activity Alaska’s beaches might still be covered with oil. The process of using organisms to eliminate toxic materials is called bio-remediation. Bioremediation is being used to clean up gasoline that leaks into the soil under gas stations. Bacteria are also used in sewage treatment plants to clean water.Americans produce more than 600 million tons of toxic wastes a year. If scientists can identify the bacteria that break down all the different kinds of toxic waste, then we will have made major progress in our efforts to improve the quality of our environment.
43. A nutrient chemical was sprayed along the Alaskan coastline in order to 1) introduce new bacteria to the beaches 2) wash away oil that had been spilled 3) dissolve oil that was spilled on the beaches 4) increase the population of bacteria
44. Which statement is accurate regarding the information in the reading passage? 1) All bacteria are harmful 2) Some bacteria are beneficial 3) Scientists have identified bacterial species to fight every toxic substance 4) Oil is non-biodegradable
45. Which statement does not represent an example of bioremediation? 1) Plants remove heavy metals from ponds and lakes 2) Ragweed plants remove lead from the ground around factory sites 3) Bacteria break down hydrocarbons in oil 4) Ladybugs eliminate insect pests from plants
Answers the following questions neatly on your answer paper:
46. State the economic and ecological benefits of bioremediation.
47. How did the bacteria clean up the oil spill?
48. Describe the scientific evidence showing that bioremediation works?