Abstract: A total of 367 twentyfour hour composited particulate matter (PM_2.5) samples were continuously collected in Guiyang City from June 2013 to May 2014. Meteorological data were simultaneously recorded by HOBO U30. Mercury (Hg) concentrations in PM_2.5 samples were measured by using Lumex with a Zeeman atomic absorption spectrometer (ZAAS). Results showed that the daily concentrations of Hg in PM_2.5 ranged from 11 to 2560 pg·m^-3 with an average of 104±85 pg·m^-3. The highest concentrations of Hg in PM_2.5 were found in December and January and the lowest in July. An obvious seasonal variation was observed as: summer < autumn < spring < winter. The anthropogenic sources from northeastern wind as well as the scarcity of precipitations resulted in high levels of Hg in PM_2.5 in winter. Compared with the investigated results in China’s other cities, the present study shows a lower level of particulate Hg pollution in Guiyang.

Key words: similarity coefficient, isolation frequency, diversity index, Pteroceltis tatarinowii