Heavy metals

WHY IN NEWS?

IIT Bombay efficiently removes heavy metals from water.

ABOUT HEAVY METALS

• The term heavy metal refers to any metallic chemical element that has a relatively high density, atomic weights, or atomic numbers. Heavy metals are toxic or poisonous even at low concentrations. Examples of heavy metals include mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), thallium (Tl), and lead (Pb).
• Heavy metals are natural components of the Earth's crust. They cannot be degraded or destroyed. To a small extent they enter our bodies via food, drinking water and air. As trace elements, some heavy metals (e.g. copper, selenium, zinc) are essential to maintain the metabolism of the human body.
• However, at higher concentrations they can lead to poisoning. Heavy metal poisoning could result, for instance, from drinking-water contamination (e.g. lead pipes), high ambient air concentrations near emission sources, or intake via the food chain.
• Heavy metals are dangerous because they tend to bio accumulate. Bioaccumulation means an increase in the concentration of a chemical in a biological organism over time, compared to the chemical's concentration in the environment.
• Compounds accumulate in living things any time they are taken up and stored faster than they are broken down (metabolized) or excreted.
• Researchers at the Indian Institute of Technology (IIT) Bombay have developed a carbon-based nanostructure that can simultaneously remove heavy metals such as arsenic, chromium, cadmium and mercury from wastewater with very high efficiency.
• No electricity is required for the nanostructure to remove heavy metals from water as it allows for gravity-driven purification of the water. The nanostructures can be recycled and reused multiple times.

Prelims Question

Q. Consider the following statements regarding heavy metals:
1.Examples of heavy metals include mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), thallium (Tl), and lead (Pb).
2.Some heavy metals are essential to maintain the metabolism of the human body.
Which of the statements given above is/are correct?
a)1 only
b)2 only
c)Both 1 and 2
d)Neither 1 nor 2

Answer to the Prelims Question