Characterizing ozone pollution in a petrochemical industrial area in Beijing, China: a case study using a chemical reaction model

This study selected a petrochemical industrial complex in Beijing, China, to understand the characteristics of surface ozone (O-3) in this industrial area through the on-site measurement campaign during the July-August of 2010 and 2011, and to reveal the response of local O-3 to its precursors' emissions through the NCARMaster Mechanism model (NCAR-MM) simulation. Measurement results showed that the O-3 concentration in this industrial area was significantly higher, with the mean daily average of 124.6 mu g/m(3) and mean daily maximum of 236.8 mu g/m(3), which are, respectively, 90.9 and 50.6 % higher than those in Beijing urban area. Moreover, the diurnal O-3 peak generally started up early in 11: 00-12: 00 and usually remained for 5-6 h, greatly different with the normal diurnal pattern of urban O-3. Then, we used NCAR-MM to simulate the average diurnal variation of photochemical O-3 in sunny days of August 2010 in both industrial and urban areas. A good agreement in O-3 diurnal variation pattern and in O-3 relative level was obtained for both areas. For example of O-3 daily maximum, the calculated value in the industrial area was about 51 % higher than in the urban area, while measured value in the industrial area was approximately 60 % higher than in the urban area. Finally, the sensitivity analysis of photochemical O-3 to its precursors was conducted based on a set of VOCs/NOx emissions cases. Simulation results implied that in the industrial area, the response of O-3 to VOCs was negative and to NOx was positive under the current conditions, with the sensitivity coefficients of -0.16 similar to-0.43 and + 0.04 similar to+ 0.06, respectively. By contrast, the urban area was within the VOCs-limitation regime, where ozone enhancement in response to increasing VOCs emissions and to decreasing NOx emission. So, we think that the VOCs emissions control for this petrochemical industrial complex will increase the potential risk of local ozone pollution aggravation, but will be helpful to inhibit the ozone formation in Beijing urban area through reducing the VOCs transport from the industrial area to the urban area.