Theoretical principles and application to measure the flux of carbon dioxide in the air of urban zones

Atmospheric carbon dioxide (CO2) concentrations increase due to volcanic emissions, diffuse degassing from fault zones, and various human-caused gas emissions, especially in densely populated urban zones, which play a pivotal role in the ongoing climate change. This study aims to examine changes in the concentration and stable isotopic composition of atmospheric CO2. A laser-based analyzer provided the delta C-13 and delta O-18 values based on concentration measurements for various CO2 isotopologues. Multiple linear regression (MLR) showed that almost 30% of the atmospheric CO2 changes are caused by weather variations, while similar to 70% of the changes involve CO2 from various gas sources related to human activities. The Keeling plot approach was used to identify the isotopic signature of the extra CO2, which points to the gas produced by hydrocarbon combustion. An isotopic mass balance model was designed to show the relation between excess atmospheric CO2 and the flux of human-related gas emissions. Calculating the CO2 flux in the atmosphere based on this isotopic mass balance model showed that several tons of CO2 move daily between geospheres. This study shows that surveying atmospheric CO2 in urban zones allows quantifying the CO2 emissions from various sources.

Automated summary

This study examines changes in atmospheric CO2 concentration and stable isotopic composition, revealing that approximately 70% of the changes are attributed to human activities, while 30% are influenced by weather variations. Additionally, the isotopic mass balance model allows for the calculation of CO2 flux, demonstrating significant daily movement of CO2 between geospheres.