Spatial distribution of fossil fuel derived CO over India using radiocarbon measurements in crop plants.

Examining the contribution of fossil fuel CO to the total CO changes in the atmosphere is of primary concern due to its alarming levels of fossil fuel emissions over the globe, specifically developing countries. Atmospheric radiocarbon represents an important observational constraint and utilized to trace fossil fuel derived CO (CO) in the atmosphere. For the first time, we have presented a detailed analysis on the spatial distribution of fossil fuel derived CO (CO) over India using radiocarbon (ΔC) measurements during three-year period. Analysis shows that the ΔC values are varying between 29.33‰ to -34.06‰ across India in the year 2017, where highest value belongs to a location from Gujarat while lowest value belongs to a location from Chhattisgarh. Based on the ΔC patterns, spatial distributions of CO mole fractions have been determined over India and the calculated values of CO mole fractions are varying between 4.85 ppm to 26.59 ppm across India. It is also noticed that the highest CO mole fraction is observed as 26.59 ppm from a site in Chhattisgarh. CO mole fraction values from four high altitude sites are found to be varied between 4.85 ppm to 14.87 ppm. Effect of sampling different crop plants from the same growing season and different crop plant organs (grains, leaves, stems) on the ΔC and CO have been studied. Annual and intra seasonal variations in the ΔC and CO mole fractions have also been analyzed from a rural location (Dholpur, Rajasthan).