黑龙江海伦农业区冬春PM2.5和气态污染物污染特征

2011~2012年冬春期间(11月到翌年4月),通过设置在海伦农田生态系统国家野外科学观测研究站内的在线监测仪器获取了PM2.5和气态污染物(NOx、O3和SO2)质量浓度的时间变化,同时结合地面气象资料和HYSPLIT后向气团轨迹模型分析了该地大气污染物的污染水平、可能来源及传输过程.结果表明:观测期间PM2.5、NOx和SO2的24h均值(范围)分别为(54.7±45.7)(8.0~217.8),(23.0±11.5)(4.5~59.6), (10.0±10.3)(0.3~56.0)μg/m3, O3的日最大8h平均值(范围)为(62.4±18.7)(24.1~173.5)μg/m3,其中除O3在4月份超过国家一级标准8d外,其它气态污染物均未超过国家一级标准;PM2.5超过国家二级标准的天数为40d,占整个观测期间的22.5%.PM2.5和SO2各月质量浓度变化较大,最高值出现在12月份,是冬季采暖的高峰期.NOx、PM2.5和SO2日变化呈双峰型,峰值出现在07:00和17:00左右;O3为单峰型,峰值出现13:00~15:00.通过对海伦地区72h内HYSPLIT后向气团轨迹模拟结果和该站点的气象数据进行分析,表明该农业区大气污染受本地源和区域输送共同影响,偏南气流易造成污染物积累,而偏北气流有利于污染物扩散.

Pollution characteristics of PM2.5 and gaseous pollutants in winter and spring at agricultural region of Hailun city,Heilongjiang Province

To know the pollution levels, possible emission sources and transport process in agricultural region, on-line measurements of main air pollutants (i.e., PM2.5, NOx, O3 and SO2) were conducted from November 1 2011 to April 30 2012 at National Observation Station of Hailun Agro-ecology System, Heilongjiang Province and further analysis were taken with surface meteorology data and backward trajectories model (i.e., HYSPLIT). The average of daily concentrations of PM2.5, NOx, and SO2 during the measurement period were (54.7±45.7) (8.0~217.8)、(23.0±11.5) (4.5~59.6) and (10.0±10.3) (0.3~56.0) μg/m3, respectively. The maximum average 8hours of O3 concentration was (62.4±18.7) (24.1~173.5) μg/m3. The gaseous pollutant levels were all below the National Ambient Air Quality Standard (NAAQS) except O3. Daily average of PM2.5 concentrations exceeded more than 40days as compared to NAAQS, which accounted for approximately one-fourth of measurement days. The concentrations of PM2.5 and SO2 were significantly higher in December than other months due to the greatest needs of winter heating. The diurnal variations of NOx, PM2.5 and SO2 were similar with two peaks occurring at 07:00and 17:00, while O3has one peak between 13:00to 15:00local time. The analysis of meteorology data and HYSPLIT suggested that the atmospheric pollution in winter is closely linked to local source emission, regional transport as well as the local meteorological conditions in Hailun city. South flows easily formed air pollution, while north wind favored the removal of pollutants by diffusion.