Size distributions of total airborne particles and bioaerosols in a municipal composting facility

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• 作者：Jeong Hoon Byeon ; Chul Woo Park ; Ki Young Yoon ; Jae Hong Park ; Jungho Hwang
• 关键词：Size distribution ; Total airborne particles ; Bioaerosols ; Composting facility
• 刊名：Bioresource Technology
• 出版年：2008
• 出版时间：July 2008
• 年：2008
• 卷：99
• 期：11
• 页码：5150-5154
• 全文大小：328 K

文摘

The size distribution of airborne particles in the atmosphere is extremely wide, however from biological point of view most important is the region between 0.2-0.3 and 10 microns, which contains the respirable domain. Investigation of altitude dependence of the size distribution and concentration of dust particles in this region in ambient air of large cities, which have an influence on indoor air quality in high buildings, is a difficult task, because the results of such measurements are influenced by many known (and some unknown) factors, such as meteorological conditions, including wind velocity and direction, up or down air currents, precipitation, changes of temperature, etc., features of topography, vehicle traffic, the density of building structures, vegetation and many others. Therefore, a large number of data points are required for the development of a realistic picture. At the same time, the need of such investigations is coused by the fact, that there are some discrepancies between experimental results and theoretical estimations especially for altitude dependence of the concentration of dust particles.

RESULTS AND DISCUSSION

The measurements were performed by an APC-03-2A type airborne particle counter (Technoorg-Linda, Hungary), having a size range of 0.3 - 10 μm and upper concentration limit 5×10⁶ particles/litre. About 600 measurements were performed during a year between 1994.06.01 and 1995.09.01 in several 3 - 5-day series at different locations under various meteorological conditions up to 100 - 150 meters in altitude. Duration of one measuring cycle was usually 5 - 10 minute. Several collection cycles were performed at all locations, all cycles contained five measurements each. Tests were carried out between certain measurement series, using a 3 μm air filter manufactured by Gelman Sciences Inc., whose transmissivity curves and efficiency were known.

Figures 1 and 2 show typical results of measurements. These measurements were taken on various floors of a 24 story building (OTE-building, Nagyvárad square), from windows facing either north or south. There were no significant differences between the data taken on the north and south side, therefore for each floor, only the average of all data taken on that particular floor is shown. The wind velocity during the measurement was less than 2m/s. The particle counts in different size ranges as a function of altitude does not significantly change up to the roof level (corresponding to about 100 meters in altitude). For the comparison Figures 3 and 4 shows the changing of size distribution of dust concentration performed at different more and less polluted locations at different points in the city. It can be seen that for the larger particles the concentration changes more dramatically between the cleaner and the more polluted locations, and it is, of course, precisely the larger particles which give the dominant contribution to the total mass concentration. At the cleaner locations the concentration of larger dust particles, namely those with diameter d > 2 or 3 μm, is roughly 4 to 5 times lower than at the more polluted locations. For the smaller particles this difference is less pronounced, and since there are significantly more of these, than larger ones, the total particle count changes relatively much less between the cleaner and the more polluted locations.Figure omitted

CONCLUSIONS

The size distribution of dust particles for different altitudes does not significantly change up to 100 - 150 m. At the cleaner and more polluted locations the concentration of larger particles (higher 2-3 μm) change 4-5 times, for the smaller particles this difference is less pronounced.