Friday, January 28, 2022

Swarnajayanti fellow exploring ways to combat climate change by enhancing ocean alkalinity

Since the 1800s, human activities for development and growth have been a major driver in increasing the global temperature of the planet, thus causing global warming which resulted in unnatural changes in the environment. Scientists are trying to tackle various approaches to solve the problem of increasing due to anthropogenic (Anthropogenic effects, processes, objects, or materials are those that are derived from human activities) and other processes.

Among those scientists, one is Arvind Singh, a physicist by training and a biogeochemist by profession. He won the Swarnajayanti fellowship instituted by the Department of Science and Technology. Arvind is currently working on will identifying minerals that can be used to enhance ocean alkalinity in a sustained way, examining the impact of increased ocean alkalinity on carbon, nitrogen, and phosphorus cycles, and understanding the effect of increased alkalinity on phytoplankton – microscopic marine algae and bacterial community structure.

Understanding what is ocean alkalinity and how it will help in combating climate change

In fighting climate change, Ocean alkalinity is one area that can help immensely to trap atmospheric CO2. On the same, several scientists suggest that over the coming decades, planet earth might need reservoirs that can store up to trillions of tons of CO2 emitted from industrial and other man-made emissions.

Arvind elaborated on the same, “Based on our understanding of the intense chemical weathering resulting in global cooling in the Cenozoic era (66 million years), it has been proposed that the enhanced ocean alkalinity through large scale mineral dissolution has the potential to provide a solution to store large amount of CO2 in the ocean.”

Arvind explained that mineral dissolution will lead to a change in the ocean carbonate chemistry equilibrium towards HCO3 (In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid) and CO32 (Carbonate ion is a polyatomic ion) − (i.e., increase in alkalinity) so that additional CO2 from the atmosphere could be dissolved and stored for a long time (more than 1000 years) in the ocean. It may be possible to sequester up to trillion tons of carbon without surpassing present-day carbonate saturation states in the ocean. In turn, the impacts of elevated alkalinity will be potentially small and may even help to reduce the effects of ocean acidification on the microbial ecosystem, but these aspects have not been tested experimentally.

Arvind Experiment

To understand the elemental cycling of the ocean, Arvind is working with stable isotopes of C (13C) and N (15N). His work blends stable isotopes, in-situ and satellite observations, microbiology, and statistical modeling to make quantitative estimates of carbon and nitrogen fluxes in the ocean. The first direct estimate of N2 fixation rates in the Arabian Sea was the work of Arvind’s Ph.D.

He also worked on elemental stoichiometry in the North Atlantic and the effect of ocean acidification on N2 fixation rates. He studied niche construction theory, the role of eddies on ocean biological pumps, and the contribution of atmospheric deposition to new nitrogen. His seminal work emphasized that C: N:P is not fixed in oceanic plankton and nutrients.

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