杭州市区空气污染物变化特征及其与气象条件的关系

Variation of Air Pollutants and Their Relation with Meteorological Conditions in Hangzhou

利用2002—2007年杭州市区空气污染物监测资料,根据杭州周边城市的每日环境空气质量,结合不同污染类型和气象资料,分析市区空气污染物变化特征及与气象条件的关系。结果表明,市区环境空气质量中污染天数出现频率逐年减少,空气质量正在好转,主要是首要污染物PM_(10)的浓度呈现逐年降低的趋势。在三种污染类型中大范围连续污染类型中的较重污染出现天数比其他两种污染类型多一半,大范围连续污染类型时PM_(10)浓度是最高的,个别污染类型时最低,PM_(10)浓度分别为0.256 mg·m^(-3)和0.177 mg·m^(-3)。不同类型与不同天气形势的关系比较密切。杭州市区污染出现频率存在明显的季节变化,冬季最高,夏季最低,污染频率分别为25.6%和3.6%。不同污染类型中个别污染类型出现最多,局地连续污染类型出现最少,出现频率分别为40.7%和29.9%。不同季节不同污染类型的出现频率相差较大,局地连续污染冬季出现频率较高,个别污染在春季出现较多,大范围连续污染在秋季出现较多。夏季的空气质量最好,只有少数的个别污染出现。在不同级别污染中,Ⅲ1级(轻微污染)主要是个别污染类型,Ⅲ2级(轻度污染)和Ⅳ1级(中度污染)污染主要是大范围连续污染类型,而Ⅳ2级(中度重污染)和Ⅴ级(重度污染)污染出现时主要是受到沙尘暴影响或春节烟花爆竹燃放影响的个别污染类型。

Based on the monitoring data of air pollutants from 2002 to 2007 over Hangzhou,according to ambient air quality every day in surrounding cities of Hangzhou,combined with different types of pollution and meteorological data,the characteristics of air pollutants and its relationship with weather conditions are analyzed.The results show that the frequency of pollution days in air quality is decreased year by year, and the air quality has been improved step by step,because the concentrations of PM10 that is the primary pollutant are decreased by degrees.The day of heavier level pollution in large-scale continual pollution is half more than that of other two types of pollution,and the highest concentration of PM10 appears in largescale continual pollution,and lowest in the individual pollution,there are 0.253 mg·m^-3 and 0.177 mg·m^-3,respectively.The different types of pollution are affected by various weather situations,their pollution level is also changed.The rates of different pollution types have an obvious seasonal variation,which is highest in winter,lowest in summer,there are 25.6%and 3.6%,respectively.Among the different types of pollution,the rates of individual pollution and local continual pollution are 40.7%and 29.9%,respectively. The rates of different pollution types in four seasons are very obvious,showing a higher rate of local pollution type in winter,that of individual pollution in spring,and that of the large-scale continuous pollution in autumn.The air quality in summer,that appears to be few of local pollution days,is the best in four seasons.The levels of different pollution are different,presenting the grades ofⅢ1（level of slight pollution） is mainly the type of local pollution,the grades ofⅢ2（lightly pollution） andⅣ1（moderat pollution） are mainly the large-scale continual pollution type,the grades ofⅣ2（moderat heavier pollution level） andⅤ（heavy pollution level） are mostly the individual pollution type that affected by the duststorm or firework in the Spring Festival.