2013年成都财富论坛期间空气质量状况分析研究

利用2013年5月20日-6月20日成都市区7个环境质量监测站点可吸入颗粒物(PM₁₀)、细颗粒物(PM_2.5)、SO₂、NO₂、CO和臭氧的实测资料及地面气象观测资料,对成都举办财富全球论坛期间及前后的空气质量变化特征和成因进行分析.结果表明,由于市政府采取交通管制措施,使机动车尾气排放的NO₂浓度与财富论坛前后相比降幅达27.2%;财富论坛期间臭氧前体物质浓度的降低,使地面臭氧日均浓度在相同太阳日辐射值下与财富论坛前后相比较低;对城区扬尘控制和周边重污染企业限产停产,分别对PM₁₀和SO₂的排放起到了明显的削减作用;后向轨迹分析表明市区SO₂浓度累积与来自东南部低空的气团有关.当相对湿度小于60%时颗粒物容易吸湿增长,而当相对湿度大于60%时降雨概率增大,颗粒物容易被清除.综合分析,成都市区财富论坛期间空气质量改善是政府减排举措的有效实施和较好的气象条件共同作用的结果.

Analysis of air quality in urban Chengdu during Fortune Global Forum in 2013

Respirable suspended particles (PM₁₀), fine particles (PM_2.5), SO₂, NO₂, CO and O₃ concentrations and meteorological conditions were measured at 7 monitoring sites in Chengdu City from 20 May to 20 June 2013, and the variation characteristics and impact factor of air quality before, during and after the Fortune Global Forum (FGF) were analyzed. As a result of the traffic restriction in urban area, the concentration of NO₂ during the FGF period decreased by 27.2% compared to the concentration before and after the FGF. O₃ concentration also declined with the same solar radiation due to the reduced concentrations of precursors. The dust control in urban area and the restriction on the pollution factories around Chengdu City were helpful to control the emissions of PM₁₀ and SO₂. The backward trajectory analysis revealed that the accumulation of SO₂ in urban area was related to the air mass of low altitude from southeast. Particulate matters were hygroscopic while the relative humidity was below 60%, while the precipitation probability increased when relative humidity was above 60%, thus particulate matters tended to be eliminated. In summary, the improvement of the air quality during the FGF in Chengdu City was due to both the emission-reduction measures implemented by government and favorable meteorological condition.