深圳市大气细粒子(PM2.5)中汞的污染特征

Pollution Characteristics of Mercury in Fine Particles (PM_(2.5)) in Shenzhen City

于2008年8月─2009年1月系统地采集了深圳市学院区和工业区的大气PM2.5样品,应用冷原子荧光法分析颗粒态总汞的含量〔以(ρ(汞)计〕.结果表明:深圳市大气PM2.5中ρ(汞)为1.93~249.27 pg/m3,平均值为72.11 pg/m3,与国内外同类研究的结果相比,其处于中等污染水平.PM2.5中ρ(汞)存在较大的季节和功能区差异,且季节差异更为显著,冬季污染最重,夏季次之,秋季最轻.夏季PM2.5中汞污染水平较高的原因:①受局地燃煤电厂排放量增加的影响;②由于台风外围下沉气流导致污染物在局地累积.从功能区差异来看,受局地燃煤电厂排放的影响,工业区PM2.5中汞的污染水平显著高于学院区.但在秋季,由于受集中的生物质燃烧排放的影响,学院区PM2.5中ρ(汞)约为工业区的1.51倍.此外,利用TEOM同步测定了学院区PM2.5中的w(汞),范围为0.19~3.43μg/g,平均值为1.11μg/g,冬季明显高于夏、秋季.PM2.5中w(汞)和温度呈显著负相关,说明温度是影响颗粒态汞的重要因素.

PM_（2.5） samples were systematically collected in a university area and an industrial area in Shenzhen from August 2008 to January 2009.Particulate mercury（pHg） was measured using a cold atomic fluorescent mercury analyzer.The results show that the pHg concentrations varied between 1.93 and 249.27（pgm^3）,with an average of 72.11（pgm^3）.Compared to other cities in China and around the world,the pHg concentrations in Shenzhen were at a middle level.Both seasonal and spatial variations of the pHg concentrations were significant, though the seasonal variations were much bigger,being highest in winter,middle in summer and lowest in fall.The relatively higher pHg concentrations in summer than in fall were attributed to both high coal burning emissions from local power plants and local contamination accumulation influenced by subsiding airflow from typhoons＇ peripheries in summer.With respect to spatial variation,the pHg concentrations were significantly higher in the industrial area than in the university area,resulting from the impact of local power plant emissions in the industrial area.In fall,however,the pHg concentrations in the university area were 1.51 times higher than in the industrial area,possibly because of intensive biomass burning events occurring in the vicinity of the university area.Simultaneously,the PM_（2.5） mass concentrations were also monitored in the university area using the TEOM instrument.The results indicated that the relative pHg concentrations,expressed as pHg mass per unit PM_（2.5） mass,ranged from 0.19 to 3.43（μgg）,with a mean value of 1.11（μgg）.The relative pHg concentrations in winter were significantly higher than in summer and autumn.Generally,the pHg relative concentrations and ambient temperature were negatively correlated,indicating that ambient temperature was an important factor influencing the pHg concentrations.