## 3 Results and Discussion
### Source Profile of Biomass Burning
The similarity (of woods) and difference (of herbaceous plant) in the ratio of K\({}^{+}\)/EC of the present study from those of previously conducted studies were attributed to the differences in components of specimens, species and corresponding cultivation environment. In the present study, the leaves and branches of the part of specimens of woods were distinguished wherein the ratio of K\({}^{+}\)/EC in branches of pine tree and cherry tree appeared approximately 50% higher than those in the leaves thereof. This suggests the ratio of K\({}^{+}\)/EC can be varied according to the ratio of composition of leaves and branches to be burnt, though they belong to the same kind of biomass of identical species. In addition, the content of K\({}^{+}\) in leaves and branches of cherry tree appeared higher than other woods with respective values of 3.80% and 4.18%, while the content of K\({}^{+}\) in stems of green perilla and red-pepper appeared 6.34% and 8.39%, respectively, suggesting the contents of K\({}^{+}\) appeared distributing in the variable range of 0.43%-8.39% according to species of crops. Additionally, the K\({}^{+}\), contained in plants, is affected by microorganisms and amount of potassium in soil. Potassium is the one of major nutrients for the growth of plants, the representative element of fertilizer. Water soluble potassium among fertilizer elements spread over soils are absorbed by crops, whereas the solidified potassium are absorbed by crops via microorganisms enabling the solubilization of potassium [42]. Therefore, the amount of potassium, contained in plants, is significantly dependent on the cultivation environment of plants. In the meantime, the red-pepper in Korea is regarded as one of the crops creating the highest value added as well as essential seasoning agent for which the area of cultivation of 32,865 ha in 2018 for red-pepper appeared higher than that of other flavor vegetables [43]. In addition, since the red-peppers are cultivated in an open field, it is included as the representative one of burning of agricultural byproducts in the registry of national atmospheric pollutants in Korea. Based on these facts, the kinds of species and cultivation environment of crops in each country, and the emission of K\({}^{+}\) from respective crops need to be identified preemptively for the employment of K\({}^{+}\) as an indicator material of the biomass burning. This is because the crops to be cultivated in countries are different according to respective dietary habits and the emission of K\({}^{+}\) varies significantly according to types of species of crops cultivated. The OC, occupying the highest portion among the components of PM\({}_{2.5}\), was classified into WIOC and WSOC, wherein the ratio of WIOC to WSOC appeared as approximately 1.2; the occupancies of WIOC and WSOC in PM\({}_{2.5}\) were approximately 16% and 32%, respectively. Further, for the specimens of woods, the weight percentage of WIOC and WSOC to total weight of PM\({}_{2.5}\) appeared approximately 20.0% and 29.2%, respectively, whereas the weight percentage of WIOC and WSOC to total weight of PM\({}_{2.5}\) in herbaceous plant appeared approximately 8.5% and 37.6%, respectively. That is, the WIOC appeared higher in woods than in herbaceous plant, whereas the WSOC appeared higher in herbaceous plant than in woods. To determine the concentration of components in WIOC and WSOC, the 114 organic compounds, comprising the 23 compounds of PAHs and 33 compounds of alkanes were analyzed for the analysis of WIOC, as well as the 27 compounds of alkanoic acids, 8 compounds of benzene carboxylic acid, 7 compounds of di-carboxylic acid, 15 compounds of amino acids and levoglucosan, were analyzed for the analysis of WSOC. The results of the analysis are presented in Figures 3 and 4. A total of 56 compounds of analysis of the PAHs and alkanes occupied approximately 7% of entire WIOC, wherein the weight percentage of PAHs and alkanes were 0.47% and 0.64%, respectively, to the weight of PM\({}_{2.5}\).