## 3 Results and Discussion
### Source Profile of Biomass Burning
The ratio of OC/EC of PM\({}_{2.5}\) resulted from the burning of coal has been known to be distributing in the range 1.6-3 [35; 36] while the ratio of OC/EC of PM\({}_{2.5}\) resulted from combustion of engine has been known to be distributing in the range 0.5-1.3 [16; 37]. The ratio of OC/EC of PM\({}_{2.5}\) emitted from the biomass burning has been known over 3 which is higher than those of other sources; according to part of previously conducted studies, the ratio of OC/EC appeared higher than 12 of rice straw and 24 of wheat straw [37; 38]. The ratio of OC/EC resulted from the biomass burning appeared distributing in the range 2.46-29.85 wherein the mean ratio thereof was 10.98. The ratio of OC/EC of 8 specimens among 10 specimens of analysis appeared over 3.0 and corresponded to results of previous studies however the ratios of OC/EC of stems of red-pepper and green perilla appeared below 3.0 suggesting different consequences from results of previous studies. To identify the causes behind the consequences, the specimens were distinguished into the hard ones of higher density (pine trees, cherry tree, red-pepper stems and stems of green perilla) and soft ones of lower density (pine needles, gingko leaves, maple leaves, cherry leaves, rice straws and stems of beans). The resulting ratio of 15.99 of OC/EC of soft specimens appeared relatively high while the ratio of 3.47 of OC/EC of hard specimens appeared lower than that of soft specimens. The four chemical components of K\({}^{+}\), SO\({}_{4}\)\({}^{2-}\), NO\({}_{3}\)\({}^{-}\) and NH\({}_{4}\)\({}^{+}\), constituting PM\({}_{2.5}\), were analyzed as ionic components. Contents of respective components of PM\({}_{2.5}\) appeared as approximately 2.36% of K\({}^{+}\), 1.99% of SO\({}_{4}\)\({}^{2-}\), 1.43% of NO\({}_{3}\)\({}^{-}\) and 0.8% of NH\({}_{4}\)\({}^{+}\). Among them, K\({}^{+}\) has been known as a major indicator ingredient of biomass burning; the level of content of K\({}^{+}\) contained in dried woods has been known approximately over 0.1%, over 0.2% for dried herbaceous plant and over 3% for crops such as olive, etc. [39]. The K\({}^{+}\), contained in crops, is emitted as KCl, KOH or K\({}^{+}\) at temperature over 1000 K [40] and according to previously conducted studies, the K\({}^{+}\) in PM\({}_{2.5}\), discharged from biomass burning, has been known to be contained 1%-10% in wheat straw and stems of maize and over 10% in rice straws [41]. The content of K\({}^{+}\) analyzed in the present study appeared with lower levels of average 1.82% in the six woods and average 3.33% in herbaceous plants comparing to results reported from previous studies. In particular, the specimens of rice straw, analyzed in the present study, contained approximately 0.81% of K\({}^{+}\) showing significant difference from results of previous studies. Figure 2: Relative chemical abundances in PM\({}_{2.5}\) and scatterplots between measured and reconstructed PM\({}_{2.5}\) mass from burning of forest tree types and agricultural crop residues byproducts. Generally, in the case of using K\({}^{+}\) as an indicator material of the biomass burning, the ratio of K\({}^{+}\)/EC is used [41]. Table 3 shows the ratio of K\({}^{+}\)/EC derived from the previously conducted studies and from the present study. As presented in the table, the ratio of K\({}^{+}\)/EC of herbaceous plant, employed for the present study, appeared distributing in the lower range 0.25-0.73 comparing to the ratio of K\({}^{+}\)/EC of 1.12-3.45 of herbaceous plant employed for the previous studies. In particular, the ratio of K\({}^{+}\)/EC of rice straw, which was predicted as pseudo-crop, was 3.45 in the previous studies exhibiting significant difference from 0.45 of the present study. On the contrary, the ratio of K\({}^{+}\)/EC of woods of the present study appeared distributing in the range 0.1-0.75 which were similar to those of 0.19 and 0.76 of previously conducted studies.