科研之友
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摘要
To investigate the ambient mass concentration, size-distribution and temporal variability of atmospheric particulate matter (PM), a long-term monitoring campaign was undertaken at an urban background site in Como, Northern Italy, from May 2015 to March 2016. A 13-stage Low Pressure Impactor (DLPI) was used for the collection of size-segregated particulates in the 0.028-10 mu m size range. The results revealed a good level of agreement between DLPI and a co-located Harvard-type PM2.5 Impactor, allowing them to be classified as comparable and characterized by a reciprocal predictability. The PM concentration levels varied greatly between the different 5-days monitoring sessions, with higher mean mass concentrations during the heating season. Appreciable seasonal differences were found for particles between 0.15 and 1.60 mu m that, on average, registered concentration levels 3.5 times higher during the heating season (mean: 28.2 mu g m(-3); median: 24.4 mu g m(-3)) compared to the non-heating season (mean: 8.3 mu g m(-3); median: 7.6 mu g m(-3)). No relevant and significant differences were detected for the coarser ranges (> 1.60 mu m). Temporal variabilities were influenced by typical PM urban sources (e.g., household heating, traffic), that significantly affected fine and submicrometer particles, and were related to meteorological factors. Ambient air particles exhibited a trimodal distribution: a first and sharp peak more pronounced during the heating season was identified between 0.3 and 0.5 mu m and two other slight peaks in the coarse mode were centered on approximately 3 and 8 mu m. No relevant differences were found in the shape of the size-distribution between the two investigated seasons. The mean PM2.5 (22.4 mu g m(-3)) and PM10 (27.7 mu g m(-3)) concentrations monitored in the study area exceeded the annual Air Quality Guideline Values (respectively equal to 10 mu g m(-3) and 20 mu g m(-3)) established by the World Health Organization.
- 出版日期2017-5
