Abstract
We present measurements of trace gases and fine aerosols obtained from a rural site in eastern China during 18 February to 30 April 2001. The field program aimed to characterize the variations in aerosol and gaseous pollutant concentrations and the emission signatures from the inland region of eastern China in the spring season. The data included O3, CO, NO, NOy*, SO2, methane, C2‐C8 nonmethane hydrocarbons (NMHCs), C1‐C2 halocarbons, and the chemical composition of PM2.5. The average hourly mixing ratios (±standard deviation) of CO, SO2, and NOy* were 677 (±315) ppbv, 15.9 (±14.6) ppbv, and 13.8 (±7.2) ppbv, respectively. The mean daytime ozone mixing ratio was 41 (±19) ppbv. The most abundant NMHC was ethane (3189 ± 717 pptv), followed by ethyne (2475 ± 1395 pptv), ethene (1679 ± 1455 pptv), and toluene (1529 ± 1608 pptv). Methyl chloride was the most abundant halocarbon (1108 ± 653 pptv). The average concentrations of particulate organic matter (POM, as organic carbon, OC, times 1.4) and elemental carbon (EC) in PM2.5 were 21.5 (±7) μg/m3 and 2.5 (±0.7) μg/m3, respectively, and sulfate and nitrate levels were 17.3 (±6.6) and 6.5 (±4) μg/m3, respectively. CO showed moderate to good correlation with NOy* (r2 = 0.59), OC (r2 = 0.65), CH3Cl (r2 = 0.59), soluble potassium (r2 = 0.53), and many NMHCs, indicating contributions from the burning of biofuel/biomass. CO also correlated with an industrial tracer, C2Cl4, indicative of some influence from industrial sources. SO2, on the other hand, correlated well with EC (r2 = 0.56), reflecting the contribution from the burning of coal. Ammonium was sufficiently abundant to fully neutralize sulfate and nitrate, indicating that there were strong emissions of ammonia from agricultural activities. Silicon and calcium had poor correlations with iron and aluminum, revealing the presence of source(s) for Si and Ca other than from soil. Examination of C2H2/CO, C3H8/C2H6, nitrate/(nitrate + NOy*), and sulfate/(SO2 + sulfate) suggested that relatively fresh air masses had been sampled at the study site in the spring season. Comparison of the observed ratios/slopes with those derived from emission inventories showed that while the observed SO2/NOy* ratio (1.29 ppbv/ppbv) in March was comparable (within 20%) to the inventory‐derived ratio for the study region, the measured CO/NOy* slope (37 ppbv/ppbv) was about 200% larger. The observed slope of CO relative to NMHC (including ethane, propane, butanes, ethene, and ethyne) also indicated the presence of excess CO, compared to the ratios from the inventories. These results strongly suggest that emissions of CO in eastern China have been underrepresented. The findings of this study highlight the importance of characterizing trace gases and aerosols within source regions of the Asian continent. The springtime results were also compared with data previously collected at the site in 1999–2000 and with those obtained on the Transport and Chemical Evolution over the Pacific (TRACE‐P) aircraft and from a coastal site in South China for the same study period.
Highlights
[8] In the present study, we present measurements of trace gases and aerosols obtained at Lin’an in spring 2001
We compare our ground-based results with those obtained on the TRACE-P DC-8 and P-3B aircraft
A sample collected in Lin’an township showed a CH3Cl mixing ratio of 1234 pptv (CO = 731 pptv), as compared to 1539 pptv (CO = 767 ppbv) obtained at the rural site at about same time. These results suggest that rural areas are important source regions for CH3Cl, reconfirming the hypothesis that CH3Cl is emitted in significant quantities from the burning of biomass/biofuel in rural locations
Summary
[2] Rapid industrialization in China has stimulated scientific research on possible impacts of the increasing emissions of gases and aerosols on the atmospheric environment and various ecosystems. The aim is to better characterize emissions and ambient concentrations in the spring season and to assess the relationship between gases and aerosol pollutants This field program was conducted during the same period as the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) and Transport and Chemical Evolution over the Pacific (TRACE-P) intensive campaigns over the western Pacific region [Huebert et al, 2003; Jacob et al, 2003]. NO2 and other reactive nitrogen species were converted to NO on hot molybdenum oxide maintained at 325°C, followed by the quantification of NO using the same chemiluminescence detector We refer to this measurement as NO*y because it does not include aerosol nitrate, which was collected on an inline filter placed upstream from the converter. Those regression results with significance levels greater than 95% (i.e., p < 0.05) are shown in the plots and used in the discussion
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