Tracing The Variational Characteristics Of Atmospheric Fossil Fuel CO₂ Using AMS-¹⁴C At Typical Chinese Regional Sites

Climate warming will cause inestimable loss to the global environment.As the main cause of global warming,excessive emission of CO₂ has become a common concern of the international community.If we want to slow down the atmospheric temperature,we need to control the emissions and emission intensity of CO₂.Up to now,the data used by the international community for evaluating the growth of the global atmospheric CO₂concentration are mainly from the base sites set up by the World Meteorological Organization（WMO）.Because of uniform distribution of CO₂ and vast territory of China,the measured results from based on above data set can not represent the level of the regional CO₂ emissions in China.As the main source of new CO₂,CO_2ff is the key to control the emission of CO₂ in the atmosphere.Therefore,it is necessary to observe the atmospheric CO₂ concentration in the regional base area of China and to quantitatively distinguish the contribution of CO₂ from the fossil emission source.In this study,we choose two typical regional sites LH（Coastal sites）and CB（Inland sites）to observe the change of ¹⁴CO₂ for one years.The purpose of the study is to determine the level of the ¹⁴CO₂ in the two typical regions in 2016 and to further track the regional transmission of the fossil fuel CO₂ in those region.Studing the typical coastal and inland background region CO_2ff levels,change rule and spatial distribution and influencing factors by radioactive carbon isotope(¹⁴C)technology and combined with stable carbon isotope tracer(¹³C)To provide scientific basis for formulating relevant carbon emission reduction policies and evaluating carbon emission reduction achievements.Sampling time of atmospheric samples from January to December,2016.Collect an air sample each month,which as a seasonal variation sample.In the summer of 2016（August）and winter（December）,atmospheric daily variation samples were collected in two research areas.In order to analyze the seasonal and diurnal variation characteristics and trends of atmospheric CO_2,δ¹³C and CO_2ff in the northern and southern regions of China,the source of CO_2ff was further analyzed.Results show that CO₂ concentration of CB and LH regional sites is higher than that of the global atmospheric background station of WLG,and similar to the concentration level of the regional background sites in the areas such as the Shangdian,Linan and Longfengshan station.The concentration of CO₂ in the regional site is mainly affected by the atmospheric emission from the surrounding area.The mean values of ¹⁴CO₂ in LH and CB were-5.2±16.2‰and-1.6±9.0.‰,respectively.Both are low in autumn/winter,and high in spring/summer.It is more obvious that the LH to CB.The course of a year,The maxmum value of CO_2ff ff about LH was 20.6 ppm,the minimum value was-5.2ppm,and the average value was5.1±6.8ppm.The mean value of the CO_2ff in CB is 3.6ppm,the highest is 12.9 ppm,and the lowest is-4.7 ppm.The CO_2ff in both places shows high autumn/winter,with low spring/summer variation patterns,and the seasonal fluctuation of LH is bigger than CB.The results showed that the CO_2ff concentration of LH and CB was higher in night time than that in the daytime.It is mainly affected by the height change of atmospheric boundary layer and wind direction,diffusion conditions and regional transmission.So the CO_2ff ff concentration in winter was significantly higher than that of summer in the same period.The atmospheric CO_2ff concentration at the bottom of the two background sites is affected by the surrounding economic circle.CB is affected by the Beijing-Tianjin-Hebei economic circle and the northeast industrial base,and the LH is affected by the pearl river delta economic circle and the northern city of Hainan province.The observation of background sites ¹⁴CO₂ to the typical coastal and inland regions,it is of great significance to understand the current situation and source of CO_2ff concentration in the typical regions of China by understanding the concentration of ¹⁴CO₂ and CO_2ff in the background atmosphere under different climate types in China.