本研究探討南台灣石化產業所在地區附近2005 年5 月至2005 年12 月底止，包括
梅雨季節、颱風降雨與颱風外圍環流、夏季及冬季降雨之濕沉降二元有機酸特性。五種
濕沉降型態中，平均而言，二元有機酸佔物種組成成份的0.11－0.87%，二元有機酸均
以oxalic acid 為主要物種。三種二元有機酸在各降雨型態中，以冬季濕沉降所佔已分析
物種組成比例為最高，主要乃因冬季時期長期沒有降雨，而在降雨時，降雨雨量少及降
雨強度小，導致濕沉降中之三種二元有機酸當量濃度較其他降雨型態為高。比較不同季
節型態之二元有機酸之malonic acid:succinic acid (M:S)比值，在梅雨季節、颱風降雨及
夏季降雨型態的M:S 比值，分別為2.1、2.0 及1.2，其值介於低比值(0.3－0.5)與高比值
3 之間，由梅雨季節、颱風降雨及夏季降雨型態逆軌跡圖所示，顯示降雨物種經長程傳
輸，從海上吹經高雄市區，降雨之部份來源為市區交通的污染排放和在海洋上產生的光
化產物溶入降雨中，在外圍環流及冬季降雨型態則有相同的M:S 比值為3.4，其M:S 的
比值高於3，由外圍環流及冬季降雨型態逆軌跡圖顯示降雨中之物種來源主要為交通車
輛排放。 the wet precipitation of the Mei-yu rain, typhoon precipitation and typhoon peripheral
circumfluence surrounding the petrochemical industry park in southern Taiwan from May
2005 till December 2005 were investigated. In all 5 types of wet precipitations, the average
percentage of low-Mw DCAs constitutes 0.87±0.43% of all chemical species. Oxalic acid is
the major constituent among all low-Mw DCAs. These three low-Mw DCAs have the highest
percentages of all analyzed chemical species in winter wet precipitation. This is mainly
because that there is little precipitation in winter and the occasional precipitations have small
quantities and intensities thus leading to higher observed equivalent concentrations of low-Mw
DCAs than observed for other patterns of precipitation. The ratios of malonic acid to succinic
acid (M:S ratio) are 2.1 for the Mei-yu rainy season, 2.0 for typhoon precipitation and 1.2 for
summer precipitation. All these ratios are between the low ratio (0.3－0.5) and the high ratio
(3) ranges. Based on the backward trajectories for these three precipitation patterns, the
chemical species contained in the rainwater have been subject to long-range transportation to
be blown from sea to Kaohsiung downtown. Some chemical species originated from local
municipal traffic-related pollution react photo-chemically with the species from the ocean and
the products are dissolved in the rainwater. Both peripheral circumfluence and the winter
precipitation have similar M:S ratios of 3.4, which is higher than 3. The backward trajectories
for both precipitation patterns indicate that the main chemical species in the rainwater mainly
come from traffic emission.
