作　　者： (侯瑶瑶）; (周卫健）; (程鹏）; (吴书刚）; (熊晓虎）; (牛振川）; (付云翀）;

机构地区： 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安710061 西安加速器质谱中心,西安710061 中国科学院大学,北京100049

出　　处： 《地球环境学报》 2017年第4期367-378,共12页

摘　　要： 利用^(14)C进行大气化石源CO_2示踪是目前节能减排领域的热点研究,为了更加便利、环保地对大气CO_2进行长期、积时采样,在原有排磷酸溶液集气法的基础上,西安加速器质谱中心研究组设计和建立了新的分子筛采样方法和装置。进一步的实验表明,分子筛解吸附的最佳条件为550℃下热解20 min,该条件下分子筛解吸附效率达99%以上,且重复性良好。该方法所收集的碳量随采样天数呈线性增长,碳吸附速率约为1.04—1.30 mg C?d^(-1),可以满足高精度AMS-^(14)C测定及高分辨率大气^(14)C研究的要求。在相同实验条件下,利用分子筛方法和排磷酸溶液集气法同时采集大气CO_2气体,结果表明,两者存在较好的一致性,说明分子筛法可提供可靠的数据。此外,分子筛法易于操作和运输,并具有便利环保的特性,值得推广使用。目前该方法已应用于大气CO_2的收集,数据表明从冬季供暖期到夏季,西安市大气化石源CO_2浓度以0.22μL?L^(-1)?d^(-1)的速率逐渐降低。化石源CO_2来源分析结果进一步表明,西安市化石源CO_2主要源自于煤燃料的燃烧,而冬季采暖需求导致的煤燃烧量的增加可能是导致冬季化石源CO_2浓度较高的主要原因。 Background, aim, and scope Large quantities of CO2 has emitted due to anthropogenic combustion of fossil fuel since industrial revolution, and the concentration of atmospheric CO2 has increased to levels unprecedented in at least the last 800000 years which is the largest contribution to the global warming. Monitoring atmospheric CO2 sources is increasingly important in the interests of establishing controllable strategies and implementing greenhouse gas regulations. CO2 emitted from the combustion of fossil fuels contains no 14C because the half-life of 14C （5730 years） is much less than the age of fossil fuels. The difference between the 14C compositions of CO2 derived from fossil fuels （CO2ff） and from modern CO2 sources is huge and this contrast makes 14C a unique and sensitive tracer for quantifying CO2ff. The existing sampling methods all have their own shortcomings. For example, the samples collected by flasks or gas sample bags are only representative of each point in time, and the pump-based alkaline solution method and molecular sieve method require external energy supply which could not be deployed in remote sampling sites, and absorption rate of the passive sampling method using molecular sieve was too low （0.014--0.065 mg C· d -1） to make high-resolution atmospheric 14C research. So there is an interest in developing an active absorption system using a molecular sieve with the pressure gradient produced by the water flowing out of a glass bottle drop by drop. Materials and methods The active absorption system is composed of two parts： （1） a molecular sieve device and （2） pressure gradient apparatus. The molecular sieve cartridge （MSC） was made in a quartz tube, in the middle of cartridge （22 mm O.D., 60 mm length） filled with 6.5 g of 13x molecular sieve secured with quartz wool. The pressure gradient apparatus consists of a 6 L custom-made glass bottle with a 9 mm O.D., 60 mm length glass tube welded to the bottle, and a water flow regulator connected to the glass tube

关 键 词： 压力差 分子筛 主动吸附 大气