Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland.
Sci Total Environ. 2010 May 15;408(12):2527-42. doi: 10.1016/j.scitotenv.2010.03.010. Epub 2010 Apr 1.
A series of smoke plumes was detected in Helsinki, Finland, during a one-month-lasting period in August 2006. The smoke plumes originated from wildfires close to Finland, and they were short-term and had a high particulate matter (PM) concentration. Physical and chemical properties of fine particles in those smokes were characterised by a wide range of real-time measurements that enabled the examination of individual plume events. Concurrently PM(1) filter samples were collected and analysed off-line. Satellite observations employing MODIS sensor on board of NASA EOS Terra satellite with the dispersion model SILAM and the Fire Assimilation System were used for evaluation of the emission fluxes from wildfires. The model predicted well the timing of the plumes but the predicted PM concentrations differed from the observed. The measurements showed that the major growth in PM concentration was caused by submicrometer particles consisting mainly of particulate organic matter (POM). POM had not totally oxidised during the transport based on the low WSOC-to-OC ratio. The fresh plumes were compared to another major smoke episode that was observed in Helsinki during April-May 2006. The duration and the source areas of the two episode periods differed. The episode in April-May was a period of nearly constantly upraised level of long-range transported PM and it was composed of aged particles when arriving in Helsinki. The two episodes had differences also in the chemical composition of PM. The mass concentrations of biomass burning tracers (levoglucosan, potassium, and oxalate) increased during both the episodes but different concentration levels of elemental carbon and potassium indicated that the episodes differed in the form of burning as well as in the burning material. In spring dry crop residue and hay from the previous season were burnt whereas in August smokes from smouldering and incomplete burning of fresh vegetation were detected.
2006 年 8 月，在芬兰赫尔辛基持续一个月的时间里，检测到一系列烟雾羽流。烟雾羽流源自芬兰附近的野火，它们是短期的，具有高颗粒物（PM）浓度。通过广泛的实时测量，对这些烟雾中的细颗粒物的物理和化学性质进行了表征，这使我们能够检查单个羽流事件。同时，离线收集和分析了 PM(1)滤膜样品。利用 NASA EOS Terra 卫星上搭载的 MODIS 传感器，结合 SILAM 分散模型和火灾同化系统，对野火排放通量进行了卫星观测。模型很好地预测了羽流的时间，但预测的 PM 浓度与观测值不同。测量结果表明，PM 浓度的主要增长是由主要由颗粒有机物（POM）组成的亚微米颗粒引起的。基于低 WSOC-OC 比，POM 在运输过程中没有完全氧化。将新生成的羽流与 2006 年 4 月至 5 月在赫尔辛基观测到的另一次主要烟雾事件进行了比较。两次事件的持续时间和源区不同。4 月至 5 月的事件是一个长距离输送 PM 水平持续升高的时期，当到达赫尔辛基时，它由老化颗粒组成。两次事件的 PM 化学成分也存在差异。生物质燃烧示踪剂（左旋葡聚糖、钾和草酸盐）的质量浓度在两次事件中均增加，但元素碳和钾的浓度水平不同，表明两次事件在燃烧形式和燃烧材料方面存在差异。在春季，干燥的作物残留物和上一季的干草被燃烧，而在 8 月，检测到由新鲜植被闷烧和不完全燃烧产生的烟雾。
