The carbon isotopic compositions of Non-methane Hydrocarbons in atmosphere

Carbon isotopic compositions of atmospheric Non-methane Hydrocarbons (NMHCs) in the urban areas of Taiyuan and Lanzhou in summer were reported and the sources of NMHCs are discussed. Carbon isotopic ratios (δ13C) of vehicle exhaust, coal-combustion exhaust, fuel volatiles and cooking exhaust were also measured with thermal desorption-gas chromatography-isotope ratio-mass spectrometry (TD-GC-IR-MS). δ13C values of NMHCs in the urban areas of Lanzhou and Taiyuan range from 32.3% to 22.3% and from 32.8% to 18.1‰ δ13C values of vehicle exhaust, coal-combustion exhaust, fuel volatiles and cooking exhaust are 32.6- 21.7%, 24.5%- 22.3%, 32.5%- 27.4% and 31.6%- 24.5%, respectively. The data indicate that vehicle exhaust and cooking exhaust make a significant contribution to the atmospheric NMHCs. Therefore, to reduce emissions of vehicle exhaust and cooking exhaust is critical for controlling atmospheric NMHCs pollution in summer.