Evaluation of the Semi-Continuous OCEC analyzer performance with the EUSAAR2 protocol
Evaluation of the Semi-Continuous OCEC analyzer performance with the EUSAAR2 protocol
复制标题
DOI：
10.1016/j.scitotenv.2020.141266
复制
发表时间：
2020-12-10
影响因子：
9.8
通讯作者：
Alastuey, A.
中科院分区：
文献类型：
--
作者：
Karanasiou, A.;Panteliadis, P.;Alastuey, A.
这项工作评估的适用性的参考协议EUSAAR 2在半连续OCEC分析仪在两种环境下，城市背景站点的交通排放和区域背景站点的影响。半连续分析仪的24小时平均OC和EC测量值与PM2.5 24小时过滤器中离线测定的OC和EC浓度的比较对于裸露和未裸露样品都产生了非常好的一致性。在城市背景区，裸露和未裸露样品的EC回归斜率分别为0.93和1.04（B = 0.07和0.05，R-2 = 0.83和0.84）。低容量样本的OC回归斜率为0.99（B =-0.18，R-2 = 0.81），高容量样本的OC回归斜率为0.93（B = 0.12，R-2 = 0.84）。在区域背景点，裸露样和未裸露样的EC回归斜率分别为0.91和1.02（B = 0和-0.03，R-2 = 0.77和0.89）。OC的回归斜率接近1;高容量采样器为1.03，低容量采样器为0.95（B = 0.08和0.26，R-2 = 0.78和0.78）。在这两个采样点，通过aethalometer和MAAP获得的BC测量值与EC非常一致。BC水平始终高于EC（对于城市背景地点，回归aethalometer BC与EC的斜率a = 1.2，截距B = 0.19，R-2 = 0.79，对于区域地点，斜率a = 1.9，B =-0.04，R-2 = 0.94，MAAP BC与EC的斜率a = 1.2，B = 0.06，R-2 = 0.94，对于城市背景站点，1.7，B =-0.03，R-2 = 0.96，对于区域站点）。这证实了需要使用特定场地的质量吸收截面（MAC），而不是制造商提供的吸收单位转换为BC质量浓度。BC数据与从半连续OCEC分析仪获得的光学EC非常好地相关（对于城市背景站点，a = 1.3，B = 0.16，R-2 = 0.80;对于区域站点，a = 1.7，B = 0.009，R-2 = 0.94）。通过半连续日落分析仪与ACSM在线测量的有机气溶胶浓度的比较显示出很强的相关性。城市背景和区域站点的OA/OC比值分别为1.9和2.3。由于取样时间延长，过滤器上耐火材料的积累导致分裂点向惰性模式转变，并改变了PC的形成和演变。极端的沙尘暴导致OC的高估，由于碳酸盐的演变中的He模式。一般来说，带有EUSAAR 2的Sunset半连续OCEC分析仪通过离线热光学分析提供了稳健和一致的测量。(C)2020年，任作家。由爱思唯尔公司出版
This work evaluates the applicability of the reference protocol EUSAAR2 in the Semi-Continuous OCEC analyzer under two environments, an urban background site influenced by traffic emissions and a regional background site. The comparison of the 24-h averaged OC and EC measurements of the Semi-Continuous analyzer with the OC and EC concentrations determined offline in PM2.5 24 h filters yielded very good agreement for both denuded and undenuded samples. In the urban background site, the regression for EC yielded a slope of 0.93 and 1.04 (b = 0.07 and 0.05, R-2 = 0.83 and 0.84), for denuded and undenuded samples respectively. The slopes of OC regressions were 0.99 (b = -0.18, R-2 = 0.81) for the low volume and 0.93 (b = 0.12, R-2 = 0.84) for the high volume samples. In the regional background site, the slopes of the EC regression with the denuded and undenuded samples was 0.91 and 1.02 correspondingly (b = 0 and - 0.03, R-2 = 0.77 and 0.89). The regression of OC had slopes close to 1; 1.03 for the high volume and 0.95 for the low volume sampler (b = 0.08 and 0.26, R-2 = 0.78 and 0.78). BC measurements obtained by an aethalometer and MAAP were in very good agreement with EC at both sampling sites. BC levels were consistently higher than EC (slope of the regression aethalometer BC vs EC slope a = 1.2, intercept b = 0.19, R-2 = 0.79, for the urban background site and a = 1.9, b = -0.04, R-2 = 0.94, for the regional site, slope MAAP BC vs EC a = 1.2, b = 0.06, R-2 = 0.94, for the urban background site and 1.7, b = -0.03, R-2 = 0.96, for the regional site). This confirms the need of using the site-specific mass absorption cross section (MAC) instead of the ones provided by manufacturers for the conversion of absorption units into BC mass concentration. BC data correlated very well with the optical EC obtained from the semi-continuous OCEC analyzer (a = 1.3, b = 0.16, R-2 = 0.80 for the urban background site and a = 1.7, b = 0.009, R-2 = 0.94 for the regional site, respectively). The comparison of OC concentrations by the Semi-Continuous Sunset analyzer with organic aerosol online measurements by ACSM showed strong correlations. The ratio OA/OC was 1.9 and 2.3 for the urban background and regional sites. The accumulation of refractory material on the filter, because of prolonged periods of sampling, caused a shift of the split point to the inert mode and changes on PC formation and evolution. Extreme dust outbreaks lead to the overestimation of OC due to the evolution of carbonate in the He mode. Generally, the Sunset Semi-Continuous OCEC analyzer with EUSAAR2 provided robust and consistent measurements with offline thermal-optical analysis. (C) 2020 The Authors. Published by Elsevier B.V.