青岛海滨大气PM_(2.5)与PM_(10)观测

2007年5～10月在黄海海滨青岛的观测表明大气PM_(2.5)和PM_(10)质量浓度呈同步变化,且变化范围较大.海陆风转换对海滨空气质量有重要影响:海风输送时空气较洁净,而陆风输送通常导致空气质量变差.PM_(2.5)、PM_(10)质量浓度与相对湿度(RH%)呈显著反相关,可能与RH%较高时多为海风输送有关.海风输送条件下较高的RH%和细粒子吸湿增长可能导致了此时PM_(2.5)对PM_(10)质量载荷的贡献率(64.7%)小于在海风/陆风混合输送和陆风输送条件下的贡献率(70.9%和77.5%).PM_(2.5)占PM_(10)质量载荷的72.3%,表明细粒子贡献显著.整个观测期PM_(10)未"达标"(PM_(10) 24 h均值 < 150 μg m~(-3),空气质量"良")的观测日仅占14 7%;但PM_(2.5)未达到美国EPA标准(PM_(2.5) 24 h均值 < 35 μg m~(-3)的观测日约为68.6%,表明大气细颗粒物PM_(2.5)的达标任务尚很艰巨.

Observation of atmospheric PM_(2.5) and PM_(10) at a coastal site,Qingdao,China

An averaged PM_(2.5) (particles ≤ 2.5 μm) and PM_(10) (particles ≤ 10 μm) mass concentrations within 24 hours were measured from bulk aerosol samples at a coastal site of Baguanshan (BGS) in Qingdao, China from May to October 2007, which showed the synchronous variations for PM_(2.5) and PM_(10) with large ranges. Transition of marine wind and continental wind is found to have influence on coastal air quality: Marine wind is always associates with clean air, while the air quality usually deteriorates with continental wind. Significant negative correlations were found between PM_(2.5) and PM_(10) mass concentrations with the ambient relative humidity (RH%), probably due to marine wind associated with high RH% and clean air. Higher RH% associated with efficient hygroscopic growth of the fine particles (≤ 2.5 μm) under marine wind might result in lower contribution of PM_(2.5) to PM_(10) mass loading (64.7%) then than those under maine/continental wind and under continental wind (70.9% and 77.5%). PM_(2.5) accounted for 72.3% of PM_(10) mass loading, indicating significant contribution of fine particles to the aerosol. The observation days with PM_(10) didn′t meet the air quality standard set by the Chinese Ministry of Environment Protection (PM_(10) 24 h mean < 150 μg·m~(-3), air quality "fine") accounting for 14.7%; however, the days didn′t meet the PM_(2.5) standard of the US EPA (Environment Protection Administration) (PM_(2.5) 24 h mean < 35 μg·m~(-3)) accounting for 68.6%, indicating implement of the controlling target of atmospheric fine particles (PM_(2.5)) in Qingdao was still tough.