Intra-community spatial variability of particulate matter size distributions in Southern California/Los Angeles
Intra-community spatial variability of particulate matter size distributions in Southern California/Los Angeles
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DOI：
10.5194/acp-9-1061-2009
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发表时间：
2009-01-01
影响因子：
6.3
通讯作者：
Froines, J.
中科院分区：
文献类型：
--
作者：
Krudysz, M.;Moore, K.;Froines, J.
由于超细颗粒物在大气中的寿命短，来源多样，其数量浓度在小的空间和时间尺度上变化很大。为了确定一个社区内的UFP暴露梯度，同时在一个网络的网站粒子数浓度测量是必要的。同时进行的颗粒数尺寸分布测量有助于确定UFP来源，同时提供数据以调查光化学和物理过程对UFP的局部尺度效应。从2007年4月至12月，我们监测粒子数尺寸分布在350米-11公里内的13个站点在附近的洛杉矶和长滩港口使用扫描迁移率粒度仪（SMPS）。通常情况下，三个SMPS单位同时部署，并在1-2周的时间间隔在站点之间轮换。在所有地点连续进行总颗粒数浓度测量。季节性和昼夜数量大小分布模式是复杂的，高度依赖于当地的气象，附近的PM源，和一天中的时间，不能概括在研究区域，也不能推断出从一个或两个采样位置。通过计算站点对之间的发散系数（COD）和相关系数（r）来评估颗粒数尺寸分布的空间变化。结果表明，颗粒大小和COD之间的总体反比关系，这意味着较小颗粒的数量浓度（
Ultrafine particle (UFP) number concentrations vary significantly on small spatial and temporal scales due to their short atmospheric lifetimes and multiplicity of sources. To determine UFP exposure gradients within a community, simultaneous particle number concentration measurements at a network of sites are necessary. Concurrent particle number size distribution measurements aid in identifying UFP sources, while providing data to investigate local scale effects of both photochemical and physical processes on UFP. From April to December 2007, we monitored particle number size distributions at 13 sites within 350 m-11 km of each other in the vicinity of the Ports of Los Angeles and Long Beach using Scanning Mobility Particle Sizers (SMPS). Typically, three SMPS units were simultaneously deployed and rotated among sites at 1-2 week intervals. Total particle number concentration measurements were conducted continuously at all sites. Seasonal and diurnal number size distribution patterns are complex, highly dependent on local meteorology, nearby PM sources, and times of day, and cannot be generalized over the study area nor inferred from one or two sampling locations. Spatial variation in particle number size distributions was assessed by calculating the coefficient of divergence (COD) and correlation coefficients (r) between site pairs. Results show an overall inverse relationship between particle size and CODs, implying that number concentrations of smaller particles (