Department of Physical Sciences, Faculty of Science, Sokoine University of Agriculture (SUA), Morogoro, Tanzania.
Sci Total Environ. 2010 Feb 15;408(6):1308-14. doi: 10.1016/j.scitotenv.2009.10.054. Epub 2009 Nov 10.
Ambient daytime and nighttime PM(10) and PM(2.5) samples were collected in parallel at a kerbside in Dar es Salaam in August and September 2005 (dry season) and in April and May 2006 (wet season). All samples were analyzed for the particulate matter mass, for organic, elemental, and total carbon (OC, EC, and TC), and for water-soluble OC (WSOC). The average PM(10) and PM(2.5) mass concentrations and associated standard deviations were 76+/-32microg/m(3) and 26+/-7microg/m(3) for the 2005 dry season and 52+/-27microg/m(3) and 19+/-10microg/m(3) for the 2006 wet season campaign. On average, TC accounted for 29% of the PM(10) mass and 49% of the PM(2.5) mass for the 2005 dry season campaign and the corresponding values for the 2006 wet season campaign were 35% and 59%. There was little difference between the two campaigns for the WSOC/OC ratios with the PM(2.5) fraction having higher ratios than the PM(10) fraction during each campaign. Also for EC/TC higher ratios were noted in PM(2.5) than in PM(10), but the ratios were substantially larger in the 2006 wet season than in the 2005 dry season. The large EC/TC ratios (means 0.22-0.38) reflect the substantial impact from traffic at Dar es Salaam, as was also apparent from the clear diurnal variation in OC levels, with higher values during the day. A simple source apportionment approach was used to apportion the OC to traffic and charcoal burning. On average, 70% of the PM(10) OC was attributed to traffic and 30% to charcoal burning in both campaigns. A definite explanation for the substantially larger EC/TC ratios in the 2006 campaign as compared to the 2005 campaign is not available.
2005 年 8 月至 9 月（旱季）和 2006 年 4 月至 5 月（雨季），在达累斯萨拉姆的路边并行采集了日间和夜间的环境 PM（10）和 PM（2.5）样本。所有样本均进行了颗粒物质量、有机碳（OC）、元素碳（EC）和总碳（TC）以及水溶性有机碳（WSOC）分析。2005 年旱季 PM（10）和 PM（2.5）的平均质量浓度及其标准偏差分别为 76+/-32microg/m（3）和 26+/-7microg/m（3），2006 年雨季则分别为 52+/-27microg/m（3）和 19+/-10microg/m（3）。平均而言，TC 占 PM（10）质量的 29%和 PM（2.5）质量的 49%，而 2006 年雨季对应的数值分别为 35%和 59%。对于 WSOC/OC 比值，两个季节之间几乎没有差异，每个季节 PM（2.5）的比值均高于 PM（10）的比值。对于 EC/TC 比值，也发现 PM（2.5）的比值高于 PM（10），但 2006 年雨季的比值明显高于 2005 年旱季。较大的 EC/TC 比值（平均值为 0.22-0.38）反映了达累斯萨拉姆交通的巨大影响，OC 水平的明显日变化也表明了这一点，白天的数值更高。采用一种简单的源分配方法将 OC 分配给交通和木炭燃烧。在两个季节中，PM（10）OC 的平均值有 70%归因于交通，30%归因于木炭燃烧。2006 年雨季 EC/TC 比值明显高于 2005 年雨季的原因目前还无法明确解释。
