摘要
采用高分辨质子转移反应飞行时间质谱仪(PTR-ToF-MS)对环境空气中还原性含硫化合物(RSCs)进行高时间分辨率在线测量.时间分辨率为2 s时,硫化氢(H_2S)、甲硫醇(MeSH)、二甲硫(DMS)和二甲二硫(DMDS)的检测限分别为25、26、22、80 ng·m^(-3);时间分辨率为10 min时,4种RSCs的检测限全面优于离线测量方法.标准样品10次重复测量表明,RSCs相对标准偏差<3%,与真实浓度相对偏差在±5%以内.通过理论计算得到的绝对定量结果与外标法测得结果的比较,对绝对定量时理论计算的RSCs与H_3O^+反应常数k值进行了校正.利用校正后k值对广州环境空气RSCs进行绝对定量,结果与外标法测量结果相对偏差<4%; 2017年2月对广州环境空气RSCs进行了为期一周的初步在线观测,测得H2S、DMDS、DMS和MeSH的浓度水平分别为501±155、1026±388、215±35、120±25 ng·m^(-3).RSCs日变化呈现差异,H2S、MeSH和DMS浓度日变化规律不明显,而其DMDS则呈现出较为明显的日变化特征.
High time resolution ambient levels of reduced sulfur compounds( RSCs) were measured online with a proton transfer reaction time-of-flight mass spectrometer( PTR-ToF-MS). With a time resolution of 2 s, detection limits of H2S, MeSH, DMS,and DMDS were 25,26,22 and 80 ng·m(-3),respectively. And with a time resolution of 10 min,the detection limits were lower than those of other offline measurement methods. Ten repetitive trials of standard RSCs mixtures showed that the relative standard deviations were less than 3% while the relative deviations from the authentic concentrations were within 5%. The theoretical rate constants k for the reactions between RSCs and H3O+,were corrected by comparing the theoretically calculated results with those determined by the external standard method. The relative deviations between ambient levels of RSCs theoretically calculated with the corrected rate constants k and those determined by the external standard method were less than 4%. Preliminary one-week online measurements of the RSCs in ambient air in Guangzhou in February 2017 revealed that the average concentrations of H2S,DMDS,DMS and MeSH were 501±155,1026±388,215±35 and 120±25 ng·m(-3),respectively. The diurnal variations of RSCs showed different patterns: the diurnal variations of H2S,MeSH and DMS were insignificant while DMDS showed distinctive diurnal changes.
作者
王钊逸
黄忠辉
张慧娜
张艳利
王新明
WANG Zhaoyi;HUANG Zhonghui;ZHANG Huina;ZHANG Yanli;WANG Xinming(Cuangdong Key Laboratory of Environmental Protection and Resources Utilization,State Key Laboratory of Organic Geochemistry,Guangzbou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou,510640,China;University of Chinese Academy of Sciences,Beijing,100049,China;Center for Excellence in Urban Atmospheric Environment,Institute of Urban Environment,Chinese Academy of Sciences,Xiamen,361021,China)
出处
《环境化学》
CAS
CSCD
北大核心
2018年第11期2425-2432,共8页
Environmental Chemistry
基金
国家自然科学基金(41571130031)
广东省科技计划(2016B050502005)
广州市科技和信息化局(201607020002
201704020135)资助~~