Bananas, Can be Used to Clean River Waters

March 18, 2011

Unlocking Word Meanings
Read the following words/expressions found in today’s article.

1. extract (v.) [ik-strakt] – to remove or separate something
Example:  Oil is extracted from roses and lavender to be used in making scented candles.

2. runoff (n.) [ruhn-awf, -of] -  water that comes from land which overflows into bodies of water such as streams, rivers and lakes.
Example: Runoffs from chemical plants are dangerous.
3. toxic (adj.) [tok-sik] – something poisonous and deadly
Example: Improper disposal of toxic wastes cause harm to humans, animals, and the environment.

4. filter (n.)  [fil-ter]  – a material used to remove solid substances in water or gas
Example: The filter in the coffee maker needs to be replaced.

Read the text below.

Recent studies show that banana skin can be used to clean river waters. Researchers from Brazil discovered that banana skin can extract poisonous metals like copper and lead [led] from river water.

These metals get into river waters through runoffs from farms and factories. They are absorbed by the soil and threaten the health of humans and animals.

Toxic metals in river waters are normally extracted using substances like silica, cellulose and aluminum oxide. However, these substances have dangerous side effects.

Gustavo Castro from Biosciences Institute in Brazil discovered that banana skins extract more metal and are much safer to use than the usual substances used.

Castro conducted two experiments. In the first one, he placed dried and powdered banana skin into a container of water with toxic metal. In the second experiment, he used a filter made out of banana skin. Both experiments showed that bigger amounts of metals get stuck to the banana skin compared to the usual extracting substances.

Other plants like apple, sugar cane, coconut and peanut have also been proven to extract metals from water.

Castro warned people not to use banana skin to filter water in their homes. The metal content in tap water is very small that the average person may not know if the banana actually extracted the metal.

Banana skins are better used in cleaning wastes from factories.

Viewpoint Discussion
Enjoy a discussion with your tutor. 

Discussion A

·         What kinds of factory are common in Japan?
·         What do you think should the government do to prevent these factories from emitting harmful wastes to our rivers or lands?

Discussion B

·         What science inventions do you think are harmful to the environment?
·         As an ordinary person, what can you do to protect our environment?

March 18, 2011