Chemical characterization of the boundary layer outflow of air pollution to Hong Kong during February–April 2001

摘要: [1] As a cooperative effort with the TRACE-P and ACE-Asia intensive in spring of 2001, trace gases aerosols were measured at relatively remote coastal site (Hok Tsui) southeastern Hong Kong. The main objective measurement program was to provide continuous ground-based data subtropical region eastern Asia characterize southward outflow continental pollution that prevails lower atmosphere during early spring. In this paper, we present results for ozone, CO, NO, NOy ,S O2, 222 Radon, methane C2–C8 nonmethane hydrocarbons (NMHCs), C1–C2 halocarbons, C1–C5 alkyl nitrate measurements obtained between 19 February 30 April 2001. average mixing ratios O3, SO2, 45 ppbv, 404 1.8 10.4 respectively. two dominant NMHCs ethane (mean: 2368 pptv) ethyne 1402 pptv), followed by propane (814 toluene (540 benzene (492 ethene (498 n-butane (326 pptv). most abundant halocarbon CH3Cl 821 while 2-BuONO2 i-PrONO2 nitrates species mean ratio 20 pptv pptv, levels strongly influenced air masses initiated passage cold fronts. are segregated into four mass groups according Rn wind direction, representing fresh outflow, coastal, perturbed maritime, local urban air. Ozone CO showed moderate positive correlation (r 2 = 0.4) marine group, characterized low levels, but they poorly correlated other groups. SO2 exhibited good correlations > 0.6) each indicating differences their emission sources and/or removal processes. very 0.85) also several NMHCs. Moreover, moderately biomass burning tracer (CH3Cl) an urban/industrial (C2Cl4) impact mixed from sources. relationship indicator atmospheric processing, ethyne/ propane/ethane, examined. 2001 compared same period 1994 PEM-West B. ozone level much higher than had concentrations TRACE-P, comparable campaigns. observed difference has been discussed context changes variations meteorology. Although it is difficult draw definitive conclusions about extent influence these factors, appears clearer skies drier conditions may have responsible period. INDEX TERMS: 0345 Atmospheric Composition Structure: Pollution—urban regional (0305); 0365 Troposphere—composition chemistry; 0368 Troposphere—constituent transport