SELECT * FROM question_mgmt as q WHERE id=3060 AND status=1 SELECT id,question_no,question,chapter FROM question_mgmt as q WHERE courseId=2 AND subId=9 AND chapterId=55 and ex_no='1' AND status=1 ORDER BY CAST(question_no AS UNSIGNED) CBSE Free NCERT Solution of 11th chemistry Environmental Chemistry what are the major causes of water pollution expl

Question:

What are the major causes of water pollution? Explain.

Answer:

Water pollution arises as a result of several human activities, which leads to the presence of several undesirable substances in water. Major water pollutants with their sources have been tabulated as follows:

Pollutant Source
Radioactive substances Mining of uranium-containing minerals
Heat Water used for cooling in industries

Plant nutrients

 

Chemical fertilizers
Toxic heavy metals Chemical factories and industries
Sediments Strip mining and soil erosion
Pesticides Chemicals used for killing fungi, weed, insects

Micro-organisms

Domestic sewage
Organic wastes Domestic sewage, decaying animals and plants, animal excreta and waste, discharge from food processing industries

Roles played by major pollutants are:

1. Pathogens: These water pollutants include bacteria and other organisms. They enter water from animal excreta and domestic sewage. Bacteria present in human excreta (for example, Escherichia coli and Streptococcus faecalis) cause gastrointestinal diseases.

2. Organic wastes: These are biodegradable wastes that pollute water as a result of run off. The presence of excess organic wastes in water decreases the amount of oxygen held by water. This decrease in the amount of dissolved oxygen inhibits aquatic life.

3. Chemical pollutants: These are water soluble chemicals like heavy metals such as cadmium, mercury, nickel, etc. The presence of these chemicals (above the tolerance limit) can damage the kidneys, central nervous system, and liver.


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SELECT ex_no,question,question_no,id,chapter FROM question_mgmt as q WHERE courseId='2' AND subId='9' AND ex_no!=0 AND status=1 and id!=3060 ORDER BY last_viewed_on desc limit 0,10

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