Preliminary carbon isotope measurements of fossil fuel and biogenic emissions from the Brazilian Southeastern region

Abstract:

Researchers have confirmed that the continuing global rising of atmospheric CO₂ content is caused by anthropogenic CO₂ contributions. Most of those contributions are essentially associated with burning of fossil fuels (coal, petroleum and natural gas). However, deforestation, biomass burning, and land use changes, can also play important roles. Researchers have showed that ¹⁴C measurements of annual plants, such as corn leaf (Hsueh et al. 2007), annual grasses (Wang and Pataki 2012), and leaves of deciduous trees (Park et al. 2013) can be used to obtain time-integrated information of the fossil fuel ration in the atmosphere. Those regional-scale fossil fuel maps are essential for monitoring CO₂ emissions mitigation efforts and/or growth spikes around the globe. However, no current data from anthropogenic contributions from both biogenic and fossil carbon has been reported from the major urban areas of Brazil. Here we make use of carbon isotopes (¹³C and ¹⁴C) to infer sources of CO₂ in the highly populated Brazilian Southeastern region (over 80 million in 2010). This region leads the country in population, urban population, population density, vehicles, industries, and many other utilities and major infrastructures. For a starting point, we focus on collecting Ipê leaves (Tabebuia, a popular deciduous tree) from across Rio de Janeiro city and state as well as Sao Paulo city during May/June of 2014 to obtain the regional distribution of ¹³C and ¹⁴C of those urban domes. So far, Δ¹⁴C range from -10 to 32‰, when δ¹³C values are running from -26 to -35‰. The result of these preliminary investigations will be presented and discussed.

Hsueh et al. 2007 Regional patterns of radiocarbon and fossil fuel-derived CO2 in surface air across North America. Geophysical Research Letters. 34: L02816. doi:10.1029/2006GL027032

Wang and Pataki 2012 Drivers of spatial variability in urban plant and soil isotopic composition in the Los Angeles Basin. Plant and Soil 350: 323–338.

Park et al. 2013 A Comparison of Distribution Maps of Δ14C of 2010 and 2011 in Korea. Radiocarbon, 55(2–3), 841-847.