Geothermal springs in Himalayas release large amount of carbon dioxide

The Himalayas host hundreds of geothermal springs and they release a huge amount of carbon dioxide in the atmosphere, according to a study by the scientists of the Wadia Institute of Himalayan Geology (WIHG).

The scientists at the WIGH, a Dehradun-based institute under the Department of Science and Technology, studied geothermal springs which cover about 10,000 square kms in the Garhwal region of the Himalayas in Uttarakhand.

The study, published in the scientific journal Environmental Science and Pollution Research, suggested that the CO2 in these 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.

The team of scientists carried out detailed chemical and stable isotope analysis of water samples collected from 20 geothermal springs from major fault zones of Garhwal Himalaya.

"It shows a significant discharge of Carbon dioxide (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, the study said.

Kalachand Sain, the director of the WIGH, said this translates into 7,20,000 carbon dioxide molecules.

"Carbon outflux from Earth's interior to the exosphere through volcanic eruptions, fault zones, and geothermal systems contribute to the global carbon cycle that affects short and long term climate of the Earth. Himalaya hosts about 600 geothermal springs having varied temperature and chemical conditions.

Their role in regional and global climate, as well as the process of tectonic driven gas emission, needs to be considered while estimating emissions to the carbon cycle and thereby to global warming, the study said.

When asked what could be the impact of the release of carbon molecules in such a huge quantity and its impact on global warming, Sain said this aspect needs to be studied as other gases too contribute to rising temperatures.

He added that the scientists have only studied the Garhwal region of Himalayas and other areas also need to be looked into.