台灣西部地區露天農廢燃燒 污染物之傳輸效應

Abstract

摘要 本研究利用環保署監測空氣品質監測資料，研究近三年來之二期稻作露天農廢燃燒的事件，建立污染物排放的源區，分析源區因露天農燃事件一次污染物的增量；再利用光化學軌跡模式（Trajectory Photochemical Air Quality Model, TPAQM）中之氣象前處理模組以及軌跡模組進行流場分析，再計算從「源區」出來的氣團軌跡流過的時間與地點，建立排放的受體區，再分析受體區中，一次污染物與二次污染物的增量情形。 統計三年內露天農廢燃燒事件案例，分類為一般事件例與大規模事件案例。其中一般事件案例27筆，大規模事件案例7筆。大規模事件案例之發生，雖有較充足之光化學反應前驅物質，但在二次污染物之增量上確不及一般事件案例，推論的原因可能為：一、大規模事件案例中，PM10之小時濃度值約在200∼300 ，影響陽光之照射，不利光化學反應之進行；二、受氣象因素雲量之影響。大規模事件常在總雲量>0.5的情況下發生，其原因可能為台灣地區農民露天燃燒農廢之行為時間，多半集中趕在降雨來臨之前夕。 最後統計源區與受體區各污染物種濃度之小時平均增量（與逐時月小時平均比較），源區部分增量為：O3 3.76 ppb 、CO 0.489 ppm、PM10 73.14 、NOx 26.44 ppb、THC 0.88 ppmc、NMHC 0.49 ppmc；受體區之增量部分為：O3 13.47 ppb 、CO 0.098 ppm、PM10 34.68 、NOx 3.93 ppb、THC 0.218 ppmc、NMHC 0.148 ppmc。

Abstract The study aimed on the effect of pollutants from open burning of agriculture waste of aftergrowth rice by analyzing the ambient air monitor data of the last three years from Taiwan EPA. Source district was defined when there has significant statistical increment of primary pollutants happened in upwind area. Utilizing the forward trajectory calculate by meteorological preprocess module and trajectory module of Trajectory Photochemical Air Quality Model (TPAQM) to find the corresponded receptor district, the increment concentration of primary and secondary pollutants of receptor district can be obtained as the difference of observed and hourly ensemble mean of the month. To gather statistics of the case for agriculture waste open burning in the past three years, I classify it for the 27 local incident case and 7 extensive incident case. Although there are more sufficient precursors for photochemical reaction in the extensive incident cases, but the increment of secondary pollutants is less than the local incident case, one reason of the inference is that concentration of extensive incident among the case usually is more than 200∼300 ,and it will influence the shining of sunshine going on of unfavorable photochemical reaction. Another is that it receives the influence of the meteorological cloudiness of factor. The extensive incidents often take place in the total cloudiness under 0.5, its reason may be the behavior concentrating shortly on open burning agriculturally waste before the rainfall will come mostly for Taiwan peasants. To count the hour-average increment comparing with the moon while chasing equally hour of primary and secondary pollutants of source and acceptor district, increment part in the source district is O3 3.76 ppb, CO 0.489 ppm, PM10 73.14 , NOX 26.44 ppb, THC 0.88 ppmc, NMHC 0.49 ppmc; the increment part of the receptor district is O3 13.47 ppb, CO 0.098 ppm,PM10 34.68 ,NOX 3.93 ppb, THC 0.218 ppmc, NMHC 0.148 ppmc.