Cross-section Study on Seasonal Variations of PM_2.5 Concentrations for Ten Metal and Melloids in Air of Lanzhou City

Objective To understand the concentrations of ten metal and metalloids in PM_2.5 of air in Lanzhou city, and to find out the main pollutants and heavy polluted seasons, thus to provide a basic data for air pollution control.

Methods Chengguan District and Xigu District of Lanzhou were selected as the surveillance sites. The concentration of PM_2.5 and ten metal and melloids in air samples were determined in 2015.

Results The concentration of Plumbum (Pb), Cadmium (Cd) and Manganese (Mn) of PM_2.5 in Chengguan district were higher than those in Xigu district, and the seasonal variation of these three metals were significant in Chengguan district(χ²=18.406, P < 0.001) and Xigu district (χ²=30.0, P < 0.001). For instance, the concentration of PM_2.5 in Chengguan district in the Spring was the highest (0.12 ng/m³), and in Xigu district in the Winter was the highest (0.11 ng/m³).

Conclusions There were obvious seasonal trend on concentration of several ten metal and melloid in PM_2.5 in 2015. Hence, the measure on prevention of air pollution should comply with the prevalence characteristics of air pollution in different seasons.