Which of the following is the biggest cause of underground soil pollution in cities?

Correct option is B

The correct answer is (b) Sanitation waste
Explanation:
. In urban areas, Sanitation waste (sewage and septage) is the most widespread cause of underground soil and water pollution.
. Leaking sewer lines and poorly constructed septic tanks allow untreated human waste to seep into the ground.
. This leads to high concentrations of nitrates and pathogenic bacteria (like E. coli) in the soil and shallow aquifers.
. According to environmental studies, the lack of centralized sewage treatment in many Indian cities forces waste into the ground, permanently damaging the soil profile.
. This pollution is often "invisible" compared to industrial waste but affects a much larger geographic area within a city.
Information Booster:
. Leachate from unmanaged landfills (municipal solid waste) is another major contributor to soil contamination in urban centers.
. Soil pollution directly impacts the groundwater quality, making it unfit for drinking without expensive treatment.
Additional Knowledge:
Chromium (Option a)
. A heavy metal usually associated with industrial pollution, particularly from tanneries and electroplating units, rather than general domestic urban waste.
Decomposed material (Option c)
. While decomposition is part of the cycle, natural decomposed organic matter actually enriches soil; it is the pollutants within the waste that cause the issue.
Cadmium (Option d)
. A toxic heavy metal found in electronic waste (e-waste) and batteries; while dangerous, it is less "widespread" as a primary cause compared to the sheer volume of sanitation waste.