PAH generation behaviors in carbonization were compared, using cypress, chestnut, and bamboo as samples. Generation of tarry matter was almost completed by the time the temperature reached 400 degrees C, while generation of PAHs continued until the temperature reached 1,000 degrees C. The weight of tarry matter per unit sample weight was large with bamboo, while the amount of PAHs was large with cypress. Of the 15 types of PAHs measured this time, the largest amount collected was fluorene, followed by phenanthrene and anthracene. The amount of PAHs generated accounted for 6 x 10(-6) to 16 x 10(-6) of the weight of the wood samples.
Background
The harmful effects of fine particles with an aerodynamic diameter less than 2.5 μm (PM2.5) on respiratory organs are emphasized in pollution studies because PM2.5 have high deposition rates in the respiratory organs and contain various hazardous compounds. In this study, a sampling method combining a high-volume air sampler (HV) with a PM2.5 impactor was developed for collecting large quantities of PM2.5. The concentrations of elemental carbon (EC), organic carbon (OC), inorganic ions, and polycyclic aromatic hydrocarbons (PAHs) were measured in PM2.5 collected by the high-and low-volume air samplers (LV).
Results
Similar results were obtained from the HV and LV methods, with respect to inorganic carbon, organic carbon, sodium ions, ammonium ions, and PAHs with more than four rings. Because of the much larger amount of PM2.5 could be collected by the HV method, the trace constituents, that were difficult to detect by the conventional LV method, were readily detected by the HV method. Furthermore, when the microsuspension method that was modified more sensitive Ames mutagenicity test, was used to test the PM2.5 samples at four sites, mutagenic activities were detected by strains TA100 and TA98. Most of the mutagenic activity was associated with the PM2.5 fraction and mutagenic activity in winter was greater than that in summer.
Conclusions
The HV method produced results similar to those from the conventional LV method with respect to the PM2.5 components present in the atmosphere in relatively high concentrations, but its 40-fold greater flow rate enabled the detection of mutagenic compounds present in only trace concentrations.
Mutagenicity of size-fractioned airborne particles collected with a multi-stage fractioned sampler, an Andersen low pressure impactor, was measured by microsuspension assay using Salmonella typhimurium YG1024 strain (× 20 conc. bacterial solution). Fine particle samples showed mutagenicity with a good dose-response relationship under the conditions of both with and without a metabolic activation system (S9 mix). In generally, the activities without S9 mix were higher than those with S9 mix, and the highest activity per unit air volume was observed in the sample of 0.52 µm in diameter. Most of the negatives were observed in coarse particle samples. The size distribution of mutagenic activity per unit air volume was skewed to the smaller size range and had one peak at 0.52 µm, although that of mass concentration was bimodal, having two peaks bounded around 1-2 µm in diameter. The highest mutagenic activity per unit mass of particles in a series of fractioned samples was observed in the sample of less than 0.22 µm in diameter. It was suggested that ultrafine particles were more mutagenic than fine particles (PM 2.5-0.1), as if the mass concentrations of ultrafine particles were 10% or less than those of fine particles. It was also shown the Andersen low pressure impactor is very useful for studies of carcinogens and mutagens in suspended particles in ambient air.
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