## 3 Results and Discussion
### Source Profile of Biomass Burning
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Type of Biomass** & **Measurement Approach** & **PM Size** & **K\({}^{+}\)/EC** & **References** \\ \hline Wood (pine needles) & chamber & PM\({}_{2.5}\) & 0.10 & this study \\ Wood (pine stem) & chamber & PM\({}_{2.5}\) & 0.15 & this study \\ Wood (ginkgo leaves) & chamber & PM\({}_{2.5}\) & 0.75 & this study \\ Wood (maple leaves) & chamber & PM\({}_{2.5}\) & 0.18 & this study \\ Wood (cherry leaves) & chamber & PM\({}_{2.5}\) & 0.44 & this study \\ Wood (cherry stem) & chamber & PM\({}_{2.5}\) & 0.69 & this study \\ Rice straw & chamber & PM\({}_{2.5}\) & 0.45 & this study \\ Soybean stem & chamber & PM\({}_{2.5}\) & 0.25 & this study \\ Green perilla stem & chamber & PM\({}_{2.5}\) & 0.42 & this study \\ Red pepper stem & chamber & PM\({}_{2.5}\) & 0.73 & this study \\ Wheat straw & chamber & PM\({}_{2.5}\) & 2.26 & Ni et al. 2017 \\ Rice straw & chamber & PM\({}_{2.5}\) & 3.45 & Ni et al. 2017 \\ Corn stalk & chamber & PM\({}_{2.5}\) & 1.12 & Ni et al. 2017 \\ Wheat straw & chamber & PM\({}_{2.5}\) & 2.2 & Hays et al. 2005 \\ Wood (Pine) & wind tunnel & PM\({}_{10}\) & 0.19 & Turn et al. 1997 \\ Wood (Pine) & field measurement & PM\({}_{2.5}\) & 0.76 & Zhang et al. 2012 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Ratios of K\({}^{+}\)/elemental carbon (EC) for crop residue emissions from this study compared to similar measurements reported elsewhere. Figure 3: Composition ratio of PM\({}_{2.5}\) mass by biomass burning of woods and agricultural byproducts. Levoglucasn is created solely by the decomposition of cellulose and hemicellulose to be burnt at temperature over 300 \({}^{\circ}\)C [44; 45]. Therefore, the levoglucasn is employed as one of organic molecular markers of PM\({}_{2.5}\) created from the biomass burning. To trace the biomass materials of burning by using the acceptance model, the ratio of levoglucasn to OC (levoglucasn/OC, mg/g-OC) is generally used [46; 47; 48] In the present study, the content of levoglucasn in WSOC appeared as the second largest one, which was corresponded to 2.11% of the weight of PM\({}_{2.5}\); the levoglucasn/OC appeared distributing in the range 26.99-157.29 mg/g-OC. With regard to the classification according to characteristics of compounds employed for the analysis, the average levoglucasn/OC of hard specimen appeared as approximately 100.24 mg/g, while it was in the range 32.67 mg/g-OC for the soft specimen. This agrees with the results of previous studies reported the yield of levoglucasn/OC of hard specimen (109-168 mg/g-OC) appeared higher than that of soft specimen (52-95 mg/g-OC) [49]. Di-carboxylic acid occupied approximately 0.16% of the weight of PM\({}_{2.5}\) for both specimens of woods and herbaceous plants. The percentage of contents of analyzed di-carboxylic acid appeared in the following order of succinic acid > glutaratic acid > azelaic acid, wherein the suberic acid was detected only from specimens of woods while the adipic acid was detected only from the stalk of woods. pimelic acid was not detected from all specimens. Benzene carboxylic acid and amino acids appeared as occupying 0.02% and 0.04% of the weight of PM\({}_{2.5}\), respectively. From the analyzed 8 compounds of benzene carboxylic acid, both the phthalate acid and methylphthalic acid were commonly detected however, the rest of 6 compounds were not detected. The analyzed amino acid was detected with the average 0.48 mg/g-OC emitted from specimens of woods and 1.25 mg/g-OC from specimens of herbaceous plant. In regard to the classification of specimens into the hard- and soft ones, it appeared as 0.52 mg/g-OC from the hard specimens, while it was 0.81 mg/g-OC from the soft specimens, suggesting lower emission from hard specimens than soft specimens. In particular, the emission of amino acid  
Figure 4: Comparison of concentrations of the main components of PM\({}_{2.5}\) from forest burning and agriculture burning.