本篇論文研究台灣副熱帶溪頭森林雲霧溶液及氣膠顆粒之化學組成，根據分子追蹤方法，特定碳水化合物如arabitol、mannitol及methyl-tetrol可作為真菌孢子及二次有機氣膠的追蹤物。
副熱帶森林中富含真菌及二次有機氣膠追蹤物，說明真菌生長及二次有機氣膠生成為溪頭主要的活動。離子層析法的結果顯示，在所有樣品中銨鹽、硝酸鹽及硫酸鹽為最主要的物種，高含量的硝酸鹽與硫酸鹽使雲霧溶液呈高度酸性。除此之外，低分子量有機酸(甲酸、乙酸及草酸)在雲霧溶液有機物組成中佔高度比例，由甲酸和乙酸的比值可得知顆粒物的排放來源種類。另外總有機碳及含碳物分析(有機碳、無機碳)結果顯示在雲霧溶液中有高於75%之總有機碳為水溶性，氣膠顆粒中也含相當高的有機碳。雲霧溶液中亦含高濃度的硫、矽、鋁、鐵及重金屬等微量元素。此外，本研究也分析雲霧溶液及氣膠顆粒之物理性質，如掃描式電子顯微鏡影像及顆粒物質重量測定，得知白天顆粒物質重量高於夜晚。
由於鮮少文獻研究雲霧溶液及氣膠顆粒的化學組成，特別是在副熱帶森林，本研究著重分析雲霧及氣膠之物化性質。再者，本研究使用多種分析儀器，其結果皆有相似的趨勢，可提升出儀器與數據的可信度。

A study was conducted in a subtropical forest, Xitou, in central Taiwan to investigate chemical characteristics in fog/cloud water and aerosol particles. Specifically, selected carbohydrate species, including arabitol, mannitol and methyl-tetrols (methyl-threitol and methyl-erythritol), were quantified and used as molecular source tracers for bioaerosol (fungal spores) and secondary organic aerosols (SOA).
The ambient concentrations of the fungi and SOA tracers in the subtropical forest were high, indicating that microbial activities and secondary aerosol formation were important processes in Xitou. In addition, inorganic ions were measured in order to determine the influence from other sources, such as agricultural and industrial activities, as well as the leaching from canopy. The large amounts of ammonium, nitrate and sulfate found in both fog water and aerosol, apparently caused the high measured acidity in the atmosphere. In addition, low-molecular weight organic acids, including acetic, formic and oxalic acid, gave information about the emission type, and accounted for a relatively large proportion of known organic species. Moreover, total organic carbon (TOC) and carbonaceous species (organic and elemental carbon) were measured, showing that on average more than 75% of organic carbon in fog water was water-soluble and the concentration of organic carbon in aerosol particles was rather high. Trace elements were detected in fog water as well, displaying high concentrations of S, Si, Al, Fe and some heavy metals. Besides the chemical analyses, physical measurements, e.g., SEM-EDX analysis and determination of total particulate matter (PM) mass were performed as well. SEM images and EDX spectra (scanning electron microscopy with energy dispersive X-ray) revealed aluminosilicate inorganic particles or mineral dust with K, Fe, Ca, Mn, Fe, Cl inclusions. Concentrations of PM mass in daytime were higher than in nighttime, implying the chemical aerosol components in Xitou were mainly of biogenic origin.
As few studies have investigated the role which organic compounds play in cloud-aerosol interactions, especially in form of ambient measurements, and specifically in subtropical forests, the results from this study reveal new insights into the composition and sources of aerosol particles and fog/cloud water in such environments. Furthermore, different analytic methods were compared, providing more reliable results for this study, especially for bioaerosol characterization.

1. Engling, G., et al., Aerosol characteristics in rural and remote areas of south China. Geochimica Et Cosmochimica Acta, 2009. 73(13): p. A332-A332.
2. Bauer, H., et al., Arabitol and mannitol as tracers for the quantification of airborne fungal spores. Atmospheric Environment, 2008. 42(3): p. 588-593.
3. Iinuma, Y., et al., A highly resolved anion-exchange chromatographic method for determination of saccharidic tracers for biomass combustion and primary bio-particles in atmospheric aerosol. Atmospheric Environment, 2009. 43(6): p. 1367-1371.
4. Claeys, M., et al., Hydroxydicarboxylic acids: Markers for secondary organic aerosol from the photooxidation of alpha-pinene. Environmental Science & Technology, 2007. 41(5): p. 1628-1634.
5. Claeys, M., et al., Formation of secondary organic aerosols from isoprene and its gas-phase oxidation products through reaction with hydrogen peroxide. Atmospheric Environment, 2004. 38(25): p. 4093-4098.
6. Schnell, R.C. and G. Vali, Atmospheric ice nuclei from decomposing vegetation. Nature, 1972. 236(5343): p. 163-&.
7. Taylor, T.N., et al., Perithecial ascomycetes from the 400 million year old Rhynie chert: an example of ancestral polymorphism. Mycologia, 2004. 96(6): p. 1403-1419.
8. Pringle, A., et al., The captured launch of a ballistospore. Mycologia, 2005. 97(4): p. 866-871.
9. Elbert, W., et al., Contribution of fungi to primary biogenic aerosols in the atmosphere: wet and dry discharged spores, carbohydrates, and inorganic ions. Atmospheric Chemistry and Physics, 2007. 7(17): p. 4569-4588.
10. Frohlich-Nowoisky, J., et al., Biogeography in the air: fungal diversity over land and oceans. Biogeosciences, 2012. 9(3): p. 1125-1136.
11. Andreae, M.O. and D. Rosenfeld, Aerosol-cloud-precipitation interactions. Part 1. The nature and sources of cloud-active aerosols. Earth-Science Reviews, 2008. 89(1-2): p. 13-41.
12. Petters, M.D., et al., On measuring the critical diameter of cloud condensation nuclei using mobility selected aerosol. Aerosol Science and Technology, 2007. 41(10): p. 907-913.
13. Petters, M.D. and S.M. Kreidenweis, A single parameter representation of hygroscopic growth and cloud condensation nucleus activity. Atmospheric Chemistry and Physics, 2007. 7(8): p. 1961-1971.
14. Kanakidou, M., et al., Organic aerosol and global climate modelling: a review. Atmospheric Chemistry and Physics, 2005. 5: p. 1053-1123.
15. Guenther, A., et al., A global-model of natural volatile organic-compound emissions. Journal of Geophysical Research-Atmospheres, 1995. 100(D5): p. 8873-8892.
16. Zhang, Z.S., et al., Determination of isoprene-derived secondary organic aerosol tracers (2-methyltetrols) by HPAEC-PAD: Results from size-resolved aerosols in a tropical rainforest. Atmospheric Environment, 2013. 70: p. 468-476.
17. Liang, L.L., et al., Characteristics of 2-methyltetrols in ambient aerosol in Beijing, China. Atmospheric Environment, 2012. 59: p. 376-381.
18. Surratt, J.D., et al., Chemical composition of secondary organic aerosol formed from the photooxidation of isoprene. Journal of Physical Chemistry A, 2006. 110(31): p. 9665-9690.
19. Noziere, B., et al., Atmospheric chemistry in stereo: A new look at secondary organic aerosols from isoprene. Geophysical Research Letters, 2011. 38.
20. Hallquist, M., et al., The formation, properties and impact of secondary organic aerosol: current and emerging issues. Atmospheric Chemistry and Physics, 2009. 9(14): p. 5155-5236.
21. Herckes, P., et al., Organic matter in Central California radiation fogs. Environmental Science & Technology, 2002. 36(22): p. 4777-4782.
22. Herckes, P., K.T. Valsaraj, and J.L. Collett, A review of observations of organic matter in fogs and clouds: Origin, processing and fate. Atmospheric Research, 2013. 132: p. 434-449.
23. Fuzzi, S., et al., Soluble organic compounds in fog and cloud droplets: what have we learned over the past few years? Atmospheric Research, 2002. 64(1-4): p. 89-98.
24. Herckes, P., et al., Evolution of the fogwater composition in Strasbourg (France) from 1990 to 1999. Atmospheric Research, 2002. 64(1-4): p. 53-62.
25. Fine, P.M., et al., Diurnal variations of individual organic compound constituents of ultrafine and accumulation mode particulate matter in the Los Angeles basin. Environmental Science & Technology, 2004. 38(5): p. 1296-1304.
26. Ieda, T., et al., Diurnal variations and vertical gradients of biogenic volatile and semi-volatile organic compounds at the Tomakomai larch forest station in Japan. Tellus Series B-Chemical and Physical Meteorology, 2006. 58(3): p. 177-186.
27. Fu, P.Q. and K. Kawamura, Diurnal variations of polar organic tracers in summer forest aerosols: A case study of a Quercus and Picea mixed forest in Hokkaido, Japan. Geochemical Journal, 2011. 45(4): p. 297-308.
28. Guenther, D.B., M.H. Pinsonneault, and J.N. Bahcall, The effects of helium diffusion on solar p-mode frequencies. Astrophysical Journal, 1993. 418(1): p. 469-475.
29. Liang, Y.L., et al., Fog and precipitation chemistry at a mid-land forest in central taiwan. Journal of Environmental Quality, 2009. 38(2): p. 627-636.
30. Arndt, R.L. and G.R. Carmichael, long-range transport and deposition of sulfur in Asia. Water Air and Soil Pollution, 1995. 85(4): p. 2283-2288.
31. Chang, K.H., et al., Modeling of long-range transport on Taiwan's acid deposition under different weather conditions. Atmospheric Environment, 2000. 34(20): p. 3281-3295.
32. Lin, T.C., et al., Base cation leaching from the canopy of a subtropical rainforest in northeastern Taiwan. Canadian Journal of Forest Research-Revue Canadienne De Recherche Forestiere, 2001. 31(7): p. 1156-1163.
33. Potter, C.S. and H.L. Ragsdale, Dry deposition washoff from forest tree leaves by experimental acid rainfall. Atmospheric Environment Part a-General Topics, 1991. 25(2): p. 341-349.
34. Schuurkes, J., Atmospheric ammonium-sulfate deposition and its role in the acidification and nitrogen enrichment of poorly buffered aquatic systems. Experientia, 1986. 42(4): p. 351-357.
35. Vanbreemen, N., et al., Soil acidification from atmospheric ammonium-sulfate in forest canopy throughfall. Nature, 1982. 299(5883): p. 548-550.
36. Talbot, R.W., et al., Atmospheric geochemistry of formic and acetic-acids at a mid-latitude temperate site. Journal of Geophysical Research-Atmospheres, 1988. 93(D2): p. 1638-1652.
37. Wang, Y., et al., Characteristics and sources of formic, acetic and oxalic acids in PM2.5 and PM10 aerosols in Beijing, China. Atmospheric Research, 2007. 84(2): p. 169-181.
38. Zhang, T., et al., Contribution of fungal spores to particulate matter in a tropical rainforest. Environmental Research Letters, 2010. 5(2).
39. Jacob, D.J., Chemistry of oh in remote clouds and its role in the production of formic-acid and peroxymonosulfate. Journal of Geophysical Research-Atmospheres, 1986. 91(D9): p. 9807-9826.
40. Yu, S.C., Role of organic acids (formic, acetic, pyruvic and oxalic) in the formation of cloud condensation nuclei (CCN): a review. Atmospheric Research, 2000. 53(4): p. 185-217.
41. Sanhueza, E., L. Figueroa, and M. Santana, Atmospheric formic and acetic acids in Venezuela. Atmospheric Environment, 1996. 30(10-11): p. 1861-1873.
42. Bauer, H., et al., The contribution of bacteria and fungal spores to the organic carbon content of cloud water, precipitation and aerosols. Atmospheric Research, 2002. 64(1-4): p. 109-119.
43. Kleindienst, T.E., et al., The formation of secondary organic aerosol from the isoprene plus OH reaction in the absence of NOx. Atmospheric Chemistry and Physics, 2009. 9(17): p. 6541-6558.
44. Surratt, J.D., et al., Evidence for organosulfates in secondary organic aerosol. Environmental Science & Technology, 2007. 41(2): p. 517-527.
45. Lu, Z.F., et al., Effect of calcium sulfate and ammonium sulfate aerosol on secondary organic aerosol formation. Acta Chimica Sinica, 2008. 66(4): p. 419-423.
46. Blake, N.J., et al., Biomass burning emissions and vertical distribution of atmospheric methyl halides and other reduced carbon gases in the South Atlantic region. Journal of Geophysical Research-Atmospheres, 1996. 101(D19): p. 24151-24164.
47. Lee, M., et al., Hydrogen peroxide, organic hydroperoxide, and formaldehyde as primary pollutants from biomass burning. Journal of Geophysical Research-Atmospheres, 1997. 102(D1): p. 1301-1309.
48. Tsai, Y.I., et al., Source indicators of biomass burning associated with inorganic salts and carboxylates in dry season ambient aerosol in Chiang Mai Basin, Thailand. Atmospheric Environment, 2013. 78: p. 93-104.
49. Sang, X.F., et al., Source categories and contribution of biomass smoke to organic aerosol over the southeastern Tibetan Plateau. Atmospheric Environment, 2013. 78: p. 113-123.
50. Facchini, M.C., et al., Partitioning of the organic aerosol component between fog droplets and interstitial air. Journal of Geophysical Research-Atmospheres, 1999. 104(D21): p. 26821-26832.
51. Raja, S., et al., Fog chemistry in the Texas-Louisiana Gulf Coast corridor. Atmospheric Environment, 2008. 42(9): p. 2048-2061.
52. Liu, X.H., et al., Evaluation of trace elements contamination in cloud/fog water at an elevated mountain site in Northern China. Chemosphere, 2012. 88(5): p. 531-541.
53. Li, W.J., et al., Microscopic evaluation of trace metals in cloud droplets in an acid precipitation region. Environmental Science & Technology, 2013. 47(9): p. 4172-4180.
54. Birch, M.E. and R.A. Cary, Elemental carbon-based method for monitoring occupational exposures to particulate diesel exhaust. Aerosol Science and Technology, 1996. 25(3): p. 221-241.
55. Bond, T.C., et al., Bounding the role of black carbon in the climate system: A scientific assessment. Journal of Geophysical Research-Atmospheres, 2013. 118(11): p. 5380-5552.
56. Bauer, H., et al., Significant contributions of fungal spores to the organic carbon and to the aerosol mass balance of the urban atmospheric aerosol. Atmospheric Environment, 2008. 42(22): p. 5542-5549.