台灣北部三個空氣品質測站之大氣微粒來源研究

Abstract

本研究利用正矩陣因子法(Positive Matrix Factorization, PMF)以及其他輔助來源分析之相關理論分析台灣北部都會地區三空氣品質測站: 中山、新莊及竹東測站，三種微粒(PM10、PM2.5及PM0.1)之汙染來源。本研究使用的數據為交大環工所蔡春進教授研究團隊的成果，其微粒的採樣係利用雙道採樣器(Dichotomous PM10 samplers)、微孔均勻沉降微粒採樣器（Micro-Orifice Uniform Deposit Impactor, MOUDI）及半自動氣膠碳成份分析儀(Sunset Laboratory Model 4 Semi‐Continuous OC/EC Field Analyzer)完成，並分析微粒中的元素(Al、Fe、Na、Mg、K、Ca、Ba、Ti、Mn、Cu、Zn、Pb、V及Cr共17種)、離子(F-、Cl-、NO3-、SO42-、NH4+、Na+、K+、Mg2+、Ca2+共九種)、元素碳和有機碳濃度。2011年5月至2013年6月，期間分別在中山、新莊及竹東測站進行49次、47次及50次24 小時的採樣。 在元素、離子及有機碳和元素碳之來源特性研究中，利用微粒的物化特性對於四周汙染源特性進行分析，並判別各物種與污染來源之間的關係，再利用PMF及條件機率函數(Conditional probability function, CPF)分析量化各來源貢獻和可能的來源方向，以詳細了解造成測站附近空氣品質下降的主因。結果顯示三個測站的PM10及PM2.5中皆分別以地殼元素及汽機車排放為最大宗汙染源，而PM0.1中的主要汙染源有二次氣膠或汽機車排放，中山測站位於都市繁忙之市中心，以汽機車排放為主，竹東測站則在較小型的都市，汙染物容易受到光化學反應作用而以二次氣膠為主要來源，新莊測站位於大都市邊陲地區，二次氣膠及汽機車排放兩汙染源貢獻比例相當。此初步結果顯示，粗微粒的部分仍以自然界的來源貢獻為主，但在交通繁忙的都會區，細微粒及奈米微粒將受到人類活動極大的影響，而以汽機車排放或二次氣膠為主。

To characterize the sources around three urban stations, characteristics of PM10, PM2.5 and PM0.1 were evaluated in three ambient monitoring stations (i.e., Zhongshan, Sinjhuang, and Jhudong) in Taiwan. The samples were collected by using MOUDI (Micro-Orifice Uniform Deposit Impactor, MSP Model 110) and a Dichotomous sampler (Andersen Model SA-241) during May 2011 to June 2013 in the stations. In Zhongshan the average concentrations of PM10, PM2.5 and PM0.1 were 31.1 ± 12.6, 19.7 ± 9.3 and 1.5 ± 0.6 µg m-3, respectively. In Sinjhuang the average concentrations were 32.2 ± 16.1, 17.9 ± 8.8 and 1.2 ± 0.5 µg m-3, respectively. In Jhudong the average concentrations were 29.7 ± 10.3, 14.5 ± 6.6 and 0.9 ± 0.5 µg m-3, respectively. The aim of our research was to characterize the sources around three urban stations. The chemical speciation including crustal matter, trace elements and ions were analyzed. We judge the characteristics of pollution sources by analyzing the percentage of crustal matter and trace elements in total mass. In terms of water soluble ions, the result of component analysis indicates that the secondary pollutant plays an important role in air quality. Based on the chemical information, positive matrix factorization (PMF) was used to identify PM sources. Five sources which are soil dust, vehicle emissions, sea salt, industrial emissions and secondary aerosols were identified to be important. Furthermore, their contributions were intensively estimated. Further conditional probability function (CPF) was used to examine the potential location of identified sources after applying the PMF modeling. Crustal enrichment factors (cEF) were calculated for trace elements to identify the nature of sources. The result indicates that fine particles relating to anthropogenic sources play an important role in the urban atmosphere.