Question

List any four factors which determine the amount of dissolved oxygen in water. Explain in brief the harmful effects of nitrate, fluoride and arsenic salts in ground water on humans.

Answer 1

Factors determining amount of Dissolved Oxygen in water include

• water temperature
• pressure
• salinity and
• amount of organic matter present in water.

Presence of nitrates, arsenic salts and fluoride in ground water has various harmful health effects on humans enlisted as:-

1. Nitrates cause blue baby syndrome in which normal haemoglobin(Hb) is converted into met-haemoglobin.
2. Arsenic binds to globin part of Hb, causing black foot disease diarrhoea, Indian Child Hood Cirrhosis, hyper keratosis etc.
3. Fluoride causes fluorosis, mottling of teeth knocking of knee, weakening of bones etc.