Pollution Characteristics and Potential Ecological Risk of Inorganic Elements in PM_2.5 during First Quarter of 2015 in Lanzhou

Objectives To investigate the pollution degree and potential ecological risk of inorganic elements in PM_2.5 of Lanzhou in the first quarter of 2015.

Methods PM_2.5 samples were collected at two sampling sites in Lanzhou. ICP-MS was used to determine the content of inorganic elements in PM_2.5. The pollution status was evaluated by enrichment factors and Hakanson potential ecological risk index, respectively.

Results The PM_2.5 content in Lanzhou in the first quarter was 1.6 times higher than the limit for grade two standard 75 μg/m³ of PM_2.5, ruled in GB 3095-2012 Ambient Air Quality Standards.Enrichment factor analysis of 11 inorganic elements (V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Hg and Pb) showed that Mo, Cu and Cd reached hyperaccumulation, which were caused by human factors. The potential ecological risk of Cd and Hg was extremely strong, while ecological harm degree of Cu and Pb was stronger, the other 7 elements had slight ecological hazards. The whole potential ecological risk degree was 2 116.

Conclusions The potential ecological risk of inorganic elements in PM_2.5 in Lanzhou in the first quarter of 2015 is extremely strong, and corresponding control measures should be taken.