2012~2019年天津市公交站微环境空气质量改善

Improvement of microenvironmental air quality in Tianjin bus stations from 2012 to 2019

于2012年9月、2014年3月、2015年6月和2019年6月在天津市八里台公交站采集环境空气样品,分析该微环境中大气可吸入颗粒物(PM_(10))污染的整体改善趋势以及PM_(10)中碳组分、水溶性离子组分以及元素组分的特征和4次采样之间的差异.结果表明,4次采样的PM_(10)浓度分别为281,217,188,78μg/m^(3),呈明显下降趋势.其中水溶性离子组分和元素组分浓度逐年降低,但其占比变化不大(平均浓度占比分别为22%和39%),4次采样的二次离子SNA(即SO_(4)^(2-),NO_(3)−和NH_(4)^(+))占PM_(10)比例分别为11%,9%,9%,17%;总碳质量浓度逐年降低,碳组分在PM_(10)中所占的比例呈波动上升的趋势(从18%上升至32%,平均为25%),根据估算结果,4次采样的二次有机碳(SOC)占PM_(10)比例分别为4%,9%,9%,13%.研究显示,天津市交通微环境空气质量改善效果显著,但二次组分(SNA和SOC)在PM_(10)中占比呈上升趋势,需进一步加强二次污染的控制.

Ambient air samples were collected at Tianjin Balitai Bus Station in September 2012,February 2014,June 2015 and June 2019 to analyze the overall improvement trend of atmospheric particulate matter(PM_(10))pollution in the microenvironment as well as the characteristics of the carbonaceous components,water-soluble ionic components and elemental components in PM_(10) and the differences between the four samplings.The results showed that the PM_(10) concentrations of the four samples were respectively 281,217,188,and 78μg/m^(3),presenting a significant downward trend.The concentrations of water-soluble ionic and elemental components in PM_(10) decreased year by year,while their proportions changed a little(22%and 39%separately).The proportion of secondary ions SNA(SO_(4)^(2-),NO_(3)−,NH_(4)^(+))in PM_(10) of the 4samples was 11%,9%,9%,17%.The concentrations of total carbon decreased year by year,while the proportion of the carbonaceous components in PM_(10) showed a fluctuating upward trend(increase from 18%to 32%,with an average of 25%).According to the estimation results,the proportion of secondary organic carbon(SOC)in the 4samples in PM_(10) was 4%,9%,9%and 13%,respectively.Our study shows that the air quality of the traffic microenvironment in Tianjin has been improved significantly,but the proportion of secondary components(SNA and SOC)in PM_(10)showed an increasing trend,it is necessary to further strengthen the control of secondary pollution.