广州地区灰霾与清洁过程的污染特征研究

Pollution characteristics during haze and clean processes in Guangzhou

不同的污染天气对应着不同的污染特征,本文利用广州观象台2010—2012年地面逐时能见度和相对湿度数据,广州番禺大气成分站2010—2012年逐时MARGA数据及O3、PM、SO2、NOx等污染物数据,判识得到广州地区2010—2012年3年中的灰霾过程和清洁过程,并研究了灰霾过程和清洁过程的污染特征.研究发现,广州地区灰霾过程主要集中在干季,清洁过程集中在湿季;灰霾过程中NO2>SO2>NO>O3,清洁过程中O3>NO2>SO2>NO,灰霾过程时的细粒子浓度比要高于清洁过程,且灰霾与清洁过程中二次离子(SO2-4、NO-3、NH+4)与PM2.5的比值分别为0.55、0.45.灰霾过程的氮氧化作用强于清洁过程,而硫氧化作用和氯损耗过程相对较弱;同时,灰霾过程和清洁过程中气溶胶均呈现弱酸性,其中,清洁过程中的气溶胶酸性强于灰霾过程.个例分析发现,灰霾过程和清洁过程均处于富氨环境中,其中,灰霾过程中,NH+4在低浓度时更为富氨状态,此时相对于SO2-4,更多的氨与NO-3结合生成NH4NO3;清洁过程则刚好相反.灰霾过程中Cl-浓度普遍较高,其主要来自KCl;而清洁过程中有明显的氯损耗,Cl-主要来自海盐,部分来自NH4Cl.

Different pollution weather has different pollution characteristics. Based on visibility and relative humidity data of Guangzhou meteorological observatory and the hourly data of MARGA,O3,particulate matter,SO2 and nitrogen oxides from Panyu atmospheric components observatory of China Meteorological Agency during 2010—2012,the days of haze and clean processes have been identified and the pollution characteristics of these two kinds of processes have also been studied. It was found that haze processes frequently happened in dry season,while clean processes happened more frequently in rainy season. The pollution characteristics of haze and clean processes were NO2SO2NO O3and O3NO2SO2NO,respectively. The fine particle concentrations in haze processes were much higher than those in clean processes. The ratios between sum of secondary ions（ SO2-4,NO-3and NH＋4） and PM2.5during haze and clean processes were 0. 55 and 0. 45,respectively. Compared with the clean processes,the oxidation of nitrogen during haze processes was stronger,while the oxidation of sulfur and the chlorine loss were weaker. Although the acidity of aerosols during clean processes was a bit stronger,they were generally weak during these two kinds of processes. It was also found by case studies that both processes happened in ammonia-rich environment. More NH＋4was combined with NO-3to generate NH4NO3 during haze processes while combined with SO2-4during clean processes. During haze processes,the concentrations of Cl-were much higher,most of which came from KCl,while during clean processes there was an obvious chlorine loss.Cl-was mostly from sea-salt and partially from NH4 Cl.