佛山市冬季PM2.5中重金属元素的污染特征

为了解珠江三角洲典型工业城市佛山冬季大气细颗粒物中重金属元素的污染特征,在佛山的城区(禅城)和城市清洁点(三水)同步采集24h PM2.5样品,分析了16种元素Fe、Ti、Zn、V、Mn、Cu、As、Rb、Sr、Cd、Cs、Ba、Hg、Tl、Pb和Bi的浓度.禅城的重金属处于较高的污染水平,三水重金属元素浓度普遍低于禅城,但Fe、Ti、Sr、Cd的浓度高于禅城.与国家大气颗粒物中重金属浓度标准相比,禅城的As、Cd超标严重,Pb略超标,三水的As、Cd超标严重.Zn、Cu、As、Pb的富集因子均高于10,表明其主要与人类活动导致的污染有关.重金属元素的浓度在灰霾期都有增高的趋势,但各重金属浓度日变化趋势和幅度在禅城较为一致,在三水则不太一致.气团后向轨迹分析表明,研究期间重金属元素的浓度分布受靠近或者始于福建的广东东北方向气团、广福沿岸气团、海洋方向气团和来自江西的气团影响,其中第1类气团主要使得重金属元素浓度提高,后面3类气团均使得重金属浓度下降.

Characteristics of heavy metals in PM2.5 during winter in Foshan City

To investigate the characteristics of heavy metals in fine particles(PM2.5) during winter in Foshan,a typical industrial city in Pearl River Delta,24h integrated PM2.5 samples were simultaneously collected at a pair of sites,one urban site and one background site,and 16 elements(Fe,Ti,Zn,V,Mn,Cu,As,Rb,Sr,Cd,Cs,Ba,Hg,Tl,Pb and Bi) of the samples were analyzed.Heavy metals at the urban site were at a high level of pollution,and generally higher than those at the background site,except Fe,Ti,Sr,and Cd.Compared with the national standard of heavy metals,the concentrations of As,and Cd were much higher and Pb exceeded slightly at the urban site,while those of As and Cd at the background site were much higher.The enrichment factors of Zn,Cu,As,and Pb were greater than 10,indicating that they were mainly from anthropogenic activities.There were clear increases in the concentrations of heavy metals during the haze period,while their daily variations at the urban site were more consistent than those in the background site.Air mass back trajectory analysis showed that the concentration distribution of heavy metals was affected by four kinds of air masses: the ones close to or starting from the northeast of Guangdong or Fujian,the ones along the coast of Guangdong and Fujian,the ones from marine and the ones from Jiangxi.The first kind of air masses increased the heavy metals concentrations,while the others decreased the levels.