| 摘要: | 本研究分析環保署嘉義酸雨站2004-2020年長期降雨化學監測資料，結果顯示其長期降水權重平均pH為5.20，pH與pAi(- log ( [nss-SO42-] + [NO3-] ))相關性分析結果並不顯著，表示降水化學中和效應顯著，而主要中和因子為NH4+，應與嘉義地區農業活動頻繁有關。主要致酸因子SO42-逐年權重平均有顯著降低趨勢，而NO3-長期逐年濃度趨勢有明顯震盪， 但濃度值並未明顯減低，長期趨勢並不顯著。嘉義地區長期S沉降量呈現減少趨勢，具有顯著性；N沉降量主來自於NH4+貢獻，N與N-NH4+以及N-NO3-沉降量長期趨勢雖為減量，但並不顯著。
應用因子分析共分類出3個因子，Factor1 為農業活動與工業、交通污染以及塵土等因子混合影響，Factor 2 為Cl-、Na+及Mg2+為高度相關，三者屬海洋因子，Factor 3 為K+高度相關，Cl-為中度相關，為塵土與農業混合因子影響。污染來源推估結果可將氣流分為三個主要來源，Cluster 2可能會帶來較多之境外污染物傳輸貢獻，佔總樣本數之28 %，Cluster 1與Cluster 3 佔總樣本數72 %，可能以台灣區域性污染物為主。分析高濃度降水個案顯示，在嘉義地區除受到境外污染物傳送貢獻外，也可能受到台中地區較高污染排放傳送至嘉義地區影響當地降水。
;In this study, long-term precipitation chemistry monitoring data from the Chiayi Acid Rain Station from 2004 to 2020 were analysed. The results of the analysis showed that the long-term rainfall-weighted average pH of precipitation in the Chiayi region was 5.20. The correlation analysis between pH and pAi showed no significant relationship. This indicates a significant neutralization effect in precipitation chemistry. The primary neutralizing factor was found to be NH4+, which is likely associated with frequent agricultural activities in the Chiayi region. The main acidifying factor, SO42-, showed a significant decreasing trend in the rainfall-weighted average concentration over the years. On the other hand, the long-term yearly concentration trend of NO3- exhibited noticeable variability, but the concentration values did not show a significant decrease, and the long-term trend was not significant. The long-term S deposition in the Chiayi region showed a decreasing trend with a slope of -0.374(P = 0.0013<0.05), indicating statistical significance. The deposition of N was mainly contributed by NH4+, and although the long-term trends of N, N-NH4+, and N-NO3- deposition showed a decrease, they were not statistically significant.
The factor analysis classified three factors. Factor 1 represents a combination of agricultural activities, traffic pollution, and dust, among other factors. Factor 2 shows a high correlation between Cl-, Na+, and Mg2+, related a marine source. Factor 3 shows a high correlation with K+ and moderately correlated with Cl-, associated with agriculture, and dust-related influences. The estimated pollution sources suggest three main airflow source regions. Cluster 2 may be attributed more to the long-range transport pollutants, accounting for 28 % of the total samples. Cluster 1 and Cluster 3, comprising 72 % of the total samples, are likely to be associated with local/regional pollutants surrounding Taiwan. The analysis of high concentration precipitation events indicates that, in addition to the long-range transport pollutants, the Chiayi region may also be influenced by higher pollutant emissions from the Taichung area, which affect local precipitation. |
