Constraining anthropogenic CH emissions in Nanjing and the Yangtze River Delta, China, using atmospheric CO and CH mixing ratios.

Methane (CH) emissions estimated with the Intergovernmental Panel on Climate Change (IPCC) inventory method at the city and regional scale are subject to large uncertainties. In this study, we determined the CH:CO emissions ratio for both Nanjing and the Yangtze River Delta (YRD), using the atmospheric CH and CO concentrations measured at a suburban site in Nanjing in the winter. The atmospheric estimate of the CH:CO emissions ratio was in reasonable agreement with that calculated using the IPCC method for the YRD (within 20%), but was 200% greater for the municipality of Nanjing. The most likely reason for the discrepancy is that emissions from unmanaged landfills are omitted from the official statistics on garbage production. [ABSTRACT FROM AUTHOR]