南京北郊一次重污染事件期间PM_(2.5)理化特性及其对大气消光的影响  

Physicochemical characteristics of PM_(2.5) and impacts on light extinction during the heavy pollution period at North Suburban Nanjing

作　　者：刘兴瑞[1] 马嫣[1] 崔芬萍[1] 王振[1] 王利朋[1] 

机构地区：[1]南京信息工程大学环境科学与工程学院,江苏省大气环境监测与污染控制高技术研究重点实验室,南京210044

出　　处：《环境化学》2016年第6期1164-1171,共8页Environmental Chemistry

基　　金：国家自然科学基金(21377059,41275142,41030962);江苏省自然科学基金(BK2012861)资助~~

摘　　要：为了解南京地区重度污染下PM_(2.5)污染特征及其对消光的影响,于2013年12月5日至12月15日在南京北郊进行了PM_(2.5)采样分析,利用离子色谱分析了其中SO_4^(2-)、NO_3^-、NH_4^+、Cl^-、Na^+、K^+、Mg^(2+)和Ca^(2+)的含量,采用扫描电迁移率粒径谱仪(SMPS)测量细粒子的粒径谱分布,运用Model 2001A热/光碳分析仪对PM_(2.5)中OC、EC进行了分析,同时采用三波长光声黑碳光度计(PASS-3)实时在线测量细粒子的吸收和散射系数,并同步获得了痕量气体SO_2、NO_x浓度.结果表明,观测期间PM_(2.5)平均浓度为161.8±51.2μg·m^(-3),主要的水溶性无机离子为SO_4^(2-)、NO_3^-和NH_4^+;气溶胶在532 nm处平均吸收、散射系数分别为98.00±42.91 MmPM_(2.5)、630.00±308.52 MmPM_(2.5).(NH_4)_2SO_4和OM是南京北郊冬季大气气溶胶中的主要消光物质,积聚模态颗粒物体积浓度和表面积浓度与总消光系数呈较好的正相关,与能见度则呈明显的负相关.重度污染期间SOR、NOR平均值分别是轻度污染期间的1.26倍和1.81倍.除较低风速条件下污染物的物理积聚,较高的相对湿度条件下污染物的二次转化是造成此次重度污染的主要原因.To understand the characteristics of PM_（2.5）and their contribution to light extinction under heavy pollution in Nanjing,sampling of PM_（2.5）was conducted at North Suburban Nanjing from 5September to 15 September,2013. Samples were analyzed by ion charomatetography（ IC） for the contents of SO_4^（2-）,NO_3^-,NH_4~＋,Cl^-,Na~＋,K~＋,Mg^（2＋） and Ca^（2＋）.Particle size distribution was measured using scanning mobility particle sizer（ SMPS）. OC and EC in PM_（2.5）were analyzed using thermal /optical carbon analyzer. The absorption and scattering coefficients were measured by threewavelength Photoacoustic Soot Spectrometer（ PASS-3） simultaneously. Trace gases SO_2 and NOx were also monitored. The results showed that the average concentration of PM_（2.5）during the observation was 161.8 ± 51. 2 μg·m^（-3）. Secondary hygroscopic components including SO_4^（2-）,NO_3^-and NH_4~＋ are major water-soluble ions. The average aerosol absorption and scattering coefficients were98.00±42.91 MmPM_（2.5）and 630. 00 ± 308. 52 MmPM_（2.5）.（ NH_4）_2SO_4 and OM were found to be the majorcontributor to aerosol extinction in winter in Nanjing. Accumulation mode particle volume concentration and surface area concentration showed positive correlations with aerosol extinction coefficient,and negative correlations with visibility. The average NOR and SOR in heavy pollution were 1.26 and 1.81 times of those during light pollution,respectively. Physical accumulation under relatively low wind speed, and the secondary transformation of pollutants under high relative humidity were the main reasons for the heavy pollution.

关 键 词：PM2.5 理化特性 消光系数 积聚模态 重度污染 南京. 

分 类 号：X513[环境科学与工程—环境工程]