Zhou Zhang

Abstract Aromatic hydrocarbons are important anthropogenic precursors of tropospheric ozone and secondary organic aerosols. Here we measured ambient aromatic hydrocarbons from March 2012 to February 2014 at six rural sites in China's developed coastal regions. On average, benzene (B) comprised > 50% of total benzene (B), toluene (T), ethylbenzene (E), and xylenes (X) (BTEX) at sites in the Northeast China Plain (NECP) or in the North China Plain (NCP), whereas T, E, and X accounted for > 77% of total BTEX at sites in the Yangtze River Delta (YRD) and the Pearl River Delta in the south. BTEX at the northern sites was significantly correlated ( p < 0.01) with combustion tracer‐carbon monoxide (CO) but weakly correlated with traffic marker‐methyl tert‐butyl ether (MTBE), suggesting that their main sources were coal and biofuel/biomass burning with substantially elevated B levels during the winter heating period. In contrast, BTEX at the southern sites originated mainly from traffic‐related and/or industrial emission sources, as indicated by the poor correlations with CO but highly significant ( p < 0.01) correlations with MTBE and tetrachloroethylene, an industrial emission tracer. The B/CO emission ratios from measurement agreed within a factor of 2 with that of a previous widely used emission inventory of China, but the T/CO ratio at the NECP site and the o‐X/CO ratio at the NCP site were 29% and 38% of that in the inventory, respectively; the E/CO and X/CO ratios at the YRD site were 3.2–3.5 fold that in the emission inventory.

Abstract. We describe here characterization of a new state-of-the-art smog chamber facility for studying atmospheric gas-phase and aerosol chemistry. The chamber consists of a 30 m3 fluorinated ethylene propylene (FEP) Teflon film reactor housed in a temperature-controlled enclosure equipped with black lamps as the light source. Temperature can be set in the range from −10 to 40 °C at accuracy of ±1 °C as measured by eight temperature sensors inside the enclosure and one just inside the reactor. Matrix air can be purified with non-methane hydrocarbons (NMHCs) < 0.5 ppb, NOx/O3/carbonyls < 1 ppb and particles < 1 cm−3. The photolysis rate of NO2 is adjustable between 0 and 0.49 min−1. At 298 K under dry conditions, the average wall loss rates of NO, NO2 and O3 were measured to be 1.41 × 10−4 min−1, 1.39 × 10−4 min−1 and 1.31 × 10−4 min−1, respectively, and the particle number wall loss rate was measured to be 0.17 h−1. Auxiliary mechanisms of this chamber are determined and included in the Master Chemical Mechanism to evaluate and model propene–NOx–air irradiation experiments. The results indicate that this new smog chamber can provide high-quality data for mechanism evaluation. Results of α-pinene dark ozonolysis experiments revealed secondary organic aerosol (SOA) yields comparable to those from other chamber studies, and the two-product model gives a good fit for the yield data obtained in this work. Characterization experiments demonstrate that our Guangzhou Institute of Geochemistry, Chinese Academy Sciences (GIG-CAS), smog chamber facility can be used to provide valuable data for gas-phase chemistry and secondary aerosol formation.