A stable carbon isotopic approach for understanding the CO2 flux at the Haibei Alpine Meadow Ecosystem—A simple model

Although respiration of organisms and biomass as well as fossil fuel burning industrial production are identified as the major sources, the CO2 flux is still unclear due to the lack of proper measurements. A mass-balance approach that exploits differences in the carbon isotopic signature (δ13C) of CO2 sources and sinks was introduced and may provide a means of reducing uncertainties in the atmospheric budget. δ13C measurements of atmospheric CO2 yielded an average of −10.3‰ relative to the Peedee Belemnite standard; soil and plants had a narrow range from −25.09‰ to −26.51‰ and averaged at −25.80‰. Based on the fact of steady fractionation and enrichment during respiration of mitochondria, we obtained the emission of CO2 of 35.451 mol m−2 a−1 and CO2 flux of 0.2149 μmol m−2 s−1. The positive CO2 flux indicated the Haibei Alpine Meadow Ecosystem a source rather than a sink. The mass-balance model can be applied for other ecosystem even global carbon cycles because it neglects the complicated process of carbon metabolism, however just focuses on stable carbon isotopic compositions in any of compartments of carbon sources and sinks.