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Groups with Metalloids

Characteristics of Groups 13 - 16 of the periodic table.

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Poison Water

Poison Water


Credit: Michel Royon
Source: http://commons.wikimedia.org/wiki/File:Bhaktapur_Puits.JPG
License: CC BY-NC 3.0

These women are drawing water from a village well in the South Asian country of Nepal. Generally, well water is considered to be safer than water from a surface source such as a river. But the water in this well may be slowly poisoning the people who drink it. The reason? The water contains high levels of arsenic.

Why It Matters

  • Arsenic is a chemical element in the class known as metalloids. As a metalloid, it shares properties with both metals and nonmetals. Arsenic has been known to be poisonous for centuries.
  • Credit: NASA Earth Observatory
    Source: http://www.flickr.com/photos/gsfc/5229268334/
    License: CC BY-NC 3.0

    Some organisms actually require arsenic to survive. One such microorganism is found in Mono Lake, California [Figure2]

  • Starting in the 1980s, high levels of arsenic were found in drinking water throughout South Asia, including Bangladesh, Pakistan, and India as well as Nepal. It has been called “the largest mass poisoning in history.” How and why did it happen? Watch this video to find out: 


Explore More

At the links below, learn more about arsenic poisoning in water in South Asia and other places. Then answer the questions that follow.

  1. Why are there high levels of arsenic in the ground water in South Asia? How many people are thought to be affected by arsenic in the water?
  2. In South Asia, people were at one time encouraged to dig wells and drink well water. That’s because well water was thought to be safer than surface water, which is usually contaminated with bacteria. Ironically, bacteria play a major role in the arsenic contamination of ground water. Explain why.
  3. What are signs of arsenic poisoning? What are some long-term health problems caused by arsenic poisoning?
  4. Deep wells in South Asia generally provide water that contains little or no arsenic. Why are scientists worried that overuse of the deep wells by using the water for irrigation may lead them to be contaminated with arsenic too?
  5. Besides deep wells, what are some other possible solutions to the arsenic-poisoning problem?
  6. South Asia isn’t the only area of the world where drinking water sources are contaminated with arsenic. What are some other places where this is a problem?

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    Image Attributions

    1. [1]^ Credit: Michel Royon; Source: http://commons.wikimedia.org/wiki/File:Bhaktapur_Puits.JPG; License: CC BY-NC 3.0
    2. [2]^ Credit: NASA Earth Observatory; Source: http://www.flickr.com/photos/gsfc/5229268334/; License: CC BY-NC 3.0

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