Question 32 from UPSC CSE 2021 - Environment

Question

Why is there a concern about copper smelting plants?
1. They may release lethal quantities of carbon monoxide into the environment.
2. The copper slag can cause the leaching of some heavy metals into the environment.
3. They may release sulphur dioxide as a pollutant.
Select the correct answer using the code given below.

Accepted Answer

Correct Option: B. 2 and 3 only

Strategy: Critically evaluate plausible emissions from copper smelting. Focus on sulphur dioxide from sulphide ores and toxic heavy metals in copper slag. Disregard carbon monoxide as it is not a primary emission at lethal scales.

Key Info: Copper smelting involves heating copper ores, often sulphide ores like chalcopyrite, to high temperatures to separate copper from impurities.

**Sulphur Dioxide (SO2)**
The process releases a significant quantity of sulphur dioxide (SO2) due to the oxidation of sulphur in the ores. SO2 is a major air pollutant with environmental and health consequences, including acid rain and respiratory problems.

**Copper Slag and Heavy Metals**
Copper slag is a by-product mainly composed of iron oxides and silica, containing residual heavy metals such as:
- Arsenic
- Lead
- Cadmium
- Zinc

When exposed to weathering, these heavy metals can leach into soil and water, causing contamination and posing ecological and health risks. Studies have documented their migration into groundwater and surface water near smelting sites.

**Carbon Monoxide (CO)**
While smelting may produce small amounts of carbon monoxide (CO), it is not typically a concern at lethal quantities. The primary air pollution issues are SO2 and particulate matter containing toxic metals.

**Example**
The closure of the Sterlite copper smelter in Tamil Nadu was linked to public concern over SO2 emissions and groundwater contamination from heavy metals in slag.

**Regulation**
In India, copper smelting is regulated under environmental norms enforced by pollution control boards, including:
- The Air (Prevention and Control of Pollution) Act, 1981
- The Water (Prevention and Control of Pollution) Act, 1974

Answer

Option A: 1 and 2 only

Answer

Option C: 1 and 3 only

Answer

Option D: 1, 2, and 3