Estimation of regional background concentration of CO₂ at Lin'an Station in Yangtze River Delta, China

A new method of extracting regional background concentration of CO₂ in Yangtze River Delta was established based on the observations of both black carbon concentration and meteorological parameters. The concentrations of CO₂ and black carbon were observed at Lin'an regional background station from 2009 to 2011. The regional background concentration of CO₂ in Yangtze River Delta was obtained by means of this new method, and the impact of human activities on CO₂ concentration in this area was also assessed. The results showed that the regional background concentration of CO₂ extracted by this approach was comparable to the values obtained by R statistical filter method, and moreover this new method was better at picking up episodes heavily polluted by anthropogenic emissions. The annual regional average background concentration of CO₂ in Yangtze River Delta from 2009 to 2011 was approximately 404.7±8.2ppm, 405.6±5.3ppm and 407.0±5.3ppm, respectively, much higher than global average value, indicating the distinct characteristic of this region. The anthropogenic emissions from Yangtze River Delta had significant influence on the concentration of CO₂, increasing the value roughly 9.1ppm higher than the regional background concentration of this area.