Radiocarbon based study of fossil fuel CO2 variations across India
Mr Rajveer Sharma1,2, Dr. Ravi Kumar Kunchala1, Mr. Sunil Ojha2, Dr. Pankaj Kumar2, Mr. Satinath Gargari2, Dr. Sundeep Chopra2
1Centre for Atmospheric Science, Indian Institute Of Technology Delhi, New Delhi, India, 2Inter University Accelerator Centre, New Delhi, India
Radiocarbon is a unique tracer for identifying the fossil fuel CO2 (CO2ff) content in the atmosphere since fossil fuels are depleted in the radiocarbon. The measurement of radiocarbon content in air can easily identify CO2 produced by combustion of fossil fuels. The radiocarbon content of crop plants can also provide the signature of CO2ff of their growing period because plants assimilate atmospheric CO2 for photosynthesis process. The literature indicates that India is the one of the largest CO2 emitter in the world. However, as per literature survey, no radiocarbon-based study of fossil fuel CO2 has been reported about emissions from India. A study has been initiated through present measurements to determine the fossil fuel CO2 variations across major parts of India using radiocarbon measurements in the crop plants.
A variety of samples in the form of leaves and grains of crop plants (wheat, mustard, rice etc.) from various locations in India has been collected for the present study. Radiocarbon measurements were performed using a 500kV Ion accelerator (XCAMS: the compact 14C Accelerator Mass Spectrometer eXtended for 10Be and 26Al) at Inter University Accelerator Centre (IUAC) – Accelerator Mass Spectrometry (AMS) facility with the precision between 2 to 3 per mill and measured 14C/12C ratios were converted into Δ14C values and CO2ff values were calculated using Δ14C values.
The results focus towards the high CO2ff values from the areas having largest coal reserves in India and from the samples collected in the vicinity of highways. The studies were further extended to look into the effect of sampling different plant organs on the CO2ff values which indicate that sampling of wheat grain in place of wheat leave can introduce an error which is slightly higher than the error introduced due to uncertainty in the radiocarbon measurements. The present study emphasizes that radiocarbon measurements can also be used effectively to monitor fossil fuel CO2 concentrations across India in the absence of continuous measurements of CO2.
Rajveer Sharma is pursuing his PhD at Centre for Atmospheric Sciences (CAS), IIT Delhi, India. He is working on the fossil fuel CO2 estimations in India using radiocarbon measurements. He is utilizing AMS facility of IUAC, New Delhi for radiocarbon measurements.