From UPSC perspective, the following things are important :
Prelims level : Geothermal springs
Mains level : Not Much
The Himalayas, which hosts about 600 geothermal springs needs to be considered while estimating emissions to the carbon cycle and thereby to global warming says, Indian researchers.
Note the following hot springs in India:
1) Panamik in Nubra valley
2) Kheer Ganga in Kullu, Himachal
3) Manikaran Sahib, Himachal
4) Tattapani, Chhattisgarh
5) Gaurikund, Uttarakhand
6) Yumthang, Sikkim
7) Reshi, Sikkim
- Geothermal or Hot springs are heated by shallow intrusions of magma (molten rock) in volcanic areas. Some thermal springs, however, are not related to volcanic activity.
- The water is heated by convective circulation: groundwater percolates downward & reaches depths of a kilometre or more where the temperature of rocks is high because of the normal temperature gradient of the Earth’s crust.
Why consider the Himalayas?
- The Himalayan geothermal springs which cover about 10,000 square km in the Garhwal region of Himalaya show a significant discharge of CO2 rich water.
- The estimated carbon dioxide degassing (removal of dissolved gases from liquids, especially water or aqueous solutions) flux is nearly 7.2 ×106 mol/year to the atmosphere.
- Such CO2 degassing should be taken into account to assess global carbon outflux in the earth’s atmosphere.
Where does this CO2 come from?
- Carbon outflux from Earth’s interior to the exosphere through volcanic eruptions, fault zones, and geothermal systems contribute to the global carbon cycle that effects short and long term climate of the Earth.
- The CO2 in the thermal springs are sourced from metamorphic decarbonation of carbonate rocks present deep in the Himalayan core along with magmatism and oxidation of graphite.
- Most of the geothermal water is dominated by evaporation followed by weathering of silicate rocks.
- Isotopic analyses further point towards a meteoric source for geothermal water.