PM_(2.5)水溶性重金属元素在线监测技术的研究和初步应用

Development and preliminary application of online monitoring technology for PM_(2.5) water soluble heavy metal

利用气体和气溶胶捕集系统(GAC),与伏安极谱分析仪(VA)的联用,自行研制了一套大气PM_(2.5)水溶性重金属元素在线监测系统(GAC—DPASV),实现了水溶性元素Zn、Cd、Pb、Cu的富集与检测,并对系统各部分的原理和结构进行了描述.该系统时间分辨率为0.5 h,采样时间为15 min,GAC捕集液进样量为5 m L,样品计量进样装置和DPASV检测装置分析时间为30 min.通过一系列参数优化,确定了系统最佳运行条件;混合标液的标定结果显示,Zn、Cd、Pb、Cu的线性相关系数(R2)均在0.987—0.999之间,大气质量浓度最低检出限分别为7.17、0.92、4.25、2.13 ng·m-3;Zn、Cd、Pb、Cu加标回收率分别为114%、103%、111%、96%,Cd测量准确度最高,测量精密度均小于8%,表明整个系统的重现性及准确度良好.在线应用结果表明联用系统能够连续在线自动监测,且Zn、Cd、Pb、Cu水溶性含量受到降雨冲刷影响较大.

An on-line monitoring system for PM_（2.5）water soluble heavy metals elements（ GAC—DPASV） was developed by using gas and aerosol collector system（ GAC）,together with the polarographic heavy metal element analyzer,realizing enrichment and detection of the water soluble heavy metals（ Zn,Cd,Pb,Cu）. The principle and structure of the system were described with a time resolution of 0. 5 h and 5 m L sampling volume. The sampling time was 15 min,and DPASV detection device needed 30 min. The optimal operation conditions of the system were determined through a series of parameters optimization. The calibration curve indicated good regression results with the linear correlation coefficient（ R2） of 0.987— 0.999,and the lowest detection limit of Zn,Cd,Pb,Cu were 7.17、0.92、4.25、2.13 ng·m-3respectively. For the 5 μg·L-1standard solution,the average recovery of Zn,Cd,Pb,Cu were 114%,103%,111%,96% respectively,and the reproducibility and stability of the whole system showed good performance with the precision less than8%. The result of online application indicated that the combination system could monitor online continuously,and the water soluble contents of Zn,Cd,Pb,Cu were affected heavily by rain.