城市大气Δ^(14)CO_(2)监测中背景站和背景值的选取——以深圳市为例

Selection of background stations and background values for urban atmosphericΔ^(14)CO_(2) monitoring:A case study of Shenzhen

城市化石源CO_(2)(CO_(2)ff)排放的可靠量化对准确理解全球和区域碳核算至关重要。虽然CO_(2)放射性C同位素(Δ^(14)CO_(2))可作为独立示踪剂对CO_(2)ff排放进行量化,但其准确性仍然受制于背景站和背景值的选取。鉴于此,本研究以深圳市为例,对比评估了距离观测站点由远及近的全球/大陆背景站、区域背景站、城市背景站和城市背景值共8个背景选项,提出了一种基于Keeling Plot(KP)右上角区域样点对背景站和背景值进行筛选和评定的新方法。结果表明,深圳市背景首选区域背景站南岭,其次为KP右上角均值。针对不同城市,可依据边界条件的复杂性、有无背景观测等情况使用不同的背景选取方法。本研究为基于Δ^(14)CO_(2)估算重点城市和区域的CO_(2)ff排放量提供了背景站和背景值选取的基本原理和实践经验。

Reliable quantification of urban fossil fuel CO_(2)(CO_(2)ff)emissions is crucial for an accurate understanding of global and regional carbon accounting.Although atmosphericΔ^(14)CO_(2) can be used as an independent tracer to quantify CO_(2)ff emissions,its accuracy is still limited by selection of background stations and background values.This study evaluated eight background options,including continental/regional/urban background stations/values,to screen the best one for Shenzhen.Among these selections,a new background value called“KP-URCM”,i.e.,the mean of the observed values in the upper right corner of the Keeling Plot,was proposed.Through assessment,the Nanling regional background station is the first choice for Shenzhen,followed by the KP-URCM.For different cities,different methods of background station/value selection can be used based on the complexity of boundary conditions and the presence or absence of background observations.This study provides basic principles and practical experience for selecting background stations/values to estimate CO_(2)ff emissions in key cities and regions based on atmosphericΔ^(14)CO_(2).