Consider the following statements regarding mercury pollution: 1) Gold mining activity is a source of mercury pollution in the world. 2) Coal-based thermal power plants cause mercury pollution. [2023]

Consider the following statements regarding mercury pollution:

Gold mining activity is a source of mercury pollution in the world.
Coal-based thermal power plants cause mercury pollution.
There is no known safe level of exposure to mercury.

How many of the above statements are correct?

Only one
Only two
All three
None

Explanation

Statement 1 is correct

Mercury-dependent artisanal and small-scale gold mining (ASGM) is one of the largest source of mercury pollution on Earth. In this practice, elemental mercury is used to extract gold from ore as an amalgam.
The amalgam is typically isolated by hand and then heated—often with a torch or over a stove—to distil the mercury and isolate the gold. Mercury released from tailings and vaporised mercury exceed 1000 tonnes each year from ASGM.

Bar chart showing mercury emissions by sector in 2018, totaling 2,223,594 kg globally. Artisanal and small-scale mining leads with nearly 900,000 kg, followed by stationary coal combustion and nonferrous metals production, with emissions decreasing across other sectors

Statement 2 is correct

Fly ash generated by thermal power plants is one of the ways mercury is released into the environment.
Coal-based Thermal Power Plants (TPPs) are responsible for a disproportionately large share of emissions compared with the industrial sector (60 per cent of PM, 45 per cent of SO2, 30 per cent of NO2, and 80 per cent of mercury (Hg)).

Statement 3 is incorrect

Mercury is the only liquid state metal, which finds very wide commercial application in industries, electrical appliances, mercurial catalysts, healthcare sector for extensive use in thermometers, sphygmomanometer, dental amalgams, agriculture for seed treatment, as laboratory reagents etc. The mercury is highly toxic in both forms (a) elemental; (b) compounds, irrespective of whether inhaled, ingested or absorbed through the skin. While mercury is highly toxic, the statement that there is “no known safe level of exposure” is not entirely accurate under some regulatory standards, which establish permissible exposure limits. You can refer to the link for more info about regulatory standards: https://cpcb.nic.in/uploads/News_Letter_Mercury_2017.pdf (Pg-49-54).

PMF Concept Hack

Statement 3 can be eliminated easily because it makes an extreme claim — “no known safe level of exposure.” Such absolute statements are usually avoided in science questions, as safe exposure limits are generally defined. Statements 1 and 2 are well-known sources of mercury pollution (gold mining and coal power plants).

Additional Information

Mercury is a naturally occurring element that is found in air, water and soil.
Exposure to mercury – even small amounts – may cause serious health problems, and is a threat to the development of the child in utero and early in life.
Mercury may have toxic effects on the nervous, digestive and immune systems, and on lungs, kidneys, skin and eyes.
Mercury is considered by WHO as one of the top ten chemicals or groups of chemicals of major public health concern.
Mercury emitted into the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish.
Most human exposure to mercury is from eating fish and shellfish contaminated with methylmercury.
In Japan, mass mercury poisoning (Minamata disease) was observed in the 1960s, caused by eating fish from Minamata Bay contaminated with methylmercury.
Natural sources of mercury include volcanic eruptions and emissions from the ocean.
Anthropogenic (human-caused) emissions include mercury that is released from fuels or raw materials, or from uses in products or industrial processes.

Answer: (b) Only two; Difficulty Level: Medium

2023, PYQs