Vertical and temporal variation of PM10 in Yanta District, Xi''an during winter
西安市雁塔区冬季可吸入颗粒物时空变化研究

In order to ascertain vertical and temporal variation characteristics of the thoracic fraction of particulate matter (PM10) in a cultural and educational area of Yanta District, Xi'an during winter,we observed the PM10 mass concentration for six days from different heights on four buildings in Shaanxi Normal University from January 22 to January 29, 2010. The results showed that PM10 concentrations were lowest at ground level (1 m) and 45~54 m. Concentrations at ground level ranged from 0.005 mg · m-3 to 0.080 mg · m-3 with an average of 0.037 mg · m-3;and concentrations at 45~54 meters ranged from undetectable to 0.005 mg · m-3 with an average of 0.038 mg · m-3. The concentrations of PM10 were highest at 3~27 m, where they ranged from 0.030 mg · m-3 to 0.180 mg · m-3 and had an average of 0.076 mg · m-3. Concentrations varied temporally and peaked in the morning and at night throughout a 24h cycle. Concentrations were lowest in the afternoon. Variations were affected by atmospheric stability, pollution sources, etc. Temperature and PM10 was negatively correlated at 6~27 m. With increasing height up to 81 m, the concentration of PM10 increased, then decreased, and finally increased. Temporal and vertical variations at dusk were complex and need further study. Concentrations at 1~81 meters were low during the study period, therefore, pollution was moderate. Environmental quality can be well and truly evaluated by monitoring PM10 and SO2 and NOx every day.