都市部と郊外の大気中の炭素質エアロゾル成分の汚染特性の比較分析

[Comparative Analysis of Pollution Characteristics of Carbonaceous Aerosol Components in the Atmosphere Between Urban and Suburban Areas].

• Xin-Yue Li
• Kai-Shan Zhang
• Lin-Li Deng
• Xin-Peng Xiang
• Wen-Qi Wu
• Zi-Yuan Yin

抄録

都市部と郊外の大気中の炭素質エアロゾル成分の汚染特性を比較するために、成都市と任寿県を調査地域として選定し、ヘイズ時と非ヘイズ時のPMを88サンプル収集して分析した。PMの質量濃度、炭素質エアロゾル成分[有機炭素(OC),元素炭素(EC),二次有機炭素(SOC)]の定量化、OCとECの相関分析、炭素成分の主成分分析(PCA)を行った。その結果、ヘイズ時の汚染物質濃度は非ヘイズ時に比べて高いことがわかった。成都市と任寿県のOCとECは正の相関があり、非ヘイズ時の相関係数はヘイズ時よりも高かった。また、ヘイズ時のSOC/PM比は、成都市よりも蓮寿県の方が高かった。このことは、二次エアロゾルがヘイズ形成において成都市よりも蓮寿県の方が重要な役割を果たしていることを示している。一方、成都市では、ヘイズが発生していない期間の二次エアロゾルの割合が有意に高く、成都市では依然として直接排出が大気汚染の主な原因であることが示唆された。PCAの結果、成都市と任寿県の両方でPMが形成されているのは、主に石炭燃焼、自動車運転、バイオマス燃焼によるものであることが示された。

To compare the pollution characteristics of carbonaceous aerosol components in the atmosphere between urban and suburban areas, Chengdu City and Renshou County were selected as study areas from which 88 samples of PM during haze and non-haze periods were collected and analyzed. Quantification of mass concentrations of PM, carbonaceous aerosol components[organic carbon (OC), elemental carbon (EC), and secondary organic carbon (SOC)], along with correlation analysis of OC and EC, and principal component analysis (PCA) of carbon components were carried out. The results show that pollutant concentrations during the haze period were higher than those during the non-haze period. The OC and EC for Chengdu City and Renshou County were positively correlated, with their correlation coefficients during the non-haze period higher than those during the haze period. The ratios of SOC/PM in Renshou County were higher than those in Chengdu City during the haze period. This indicates that secondary aerosols play a more important role in haze formation in Renshou than in Chengdu City. In contrast, the proportion of secondary aerosols during the non-haze period in Chengdu City was significantly higher, indicating that direct emissions are still the main cause of air pollution in Chengdu City. PCA results showed that PM formation in both Chengdu City and Renshou County was mainly due to coal burning, vehicle operation, and biomass burning.