Content and absorption features of polycyclic aromatic hydrocarbons in the leaves of frequently-used evergreen trees in Beijing

To understand the absorption capacity of polycyclic aromatic hydrocarbons (PAHs, a kind of air pollutant) from evergreen trees in Beijing, the contents of PAHs in the leaves from 9 kinds of evergreen trees in normal growth at Taoranting Park and Madian Park of Beijing in winter were measured by liquid chromatography, and a comparative analysis of 4 kinds of plants' absorption capacity in different sampling area was made. The results showed that: the absorption characteristics for PAHs from tested trees in the same sampling area was species dependent. The highest total content of PAHs was Pinus bungeana. The order of total PAHs content in different leaves at Taoranting Park from high to low was: Pinus bungeana > Cedrus deodara > Pinus armandii > Platycladus orientalis > Pinus tabuliformis > Cephalotaxus sinensis > Sabina vulgaris > Sabina chinensis > Picea meyeri, among which, the highest content of light PAHs was Pinus bungeana, while the minimum was Picea meyeri; Cephalotaxus sinensis had the most intermediate PAHs, while Sabina vulgaris had the least; the content of heavy PAHs in Pinus tabuliformis was the maximum, and Sabina chinensis had the minimum content of heavy PAHs in leaves; The order of total PAHs content from four plants at Madian Park was the same as the content in leaves at Taoranting Park, which was Pinus bungeana > Platycladus orientalis > Pinus tabuliformis > Sabina chinensis; However, the four trees had different absorption features. The results indicate that evergreen trees can absorb PAHs from air, different trees have significantly different absorption content of PAHs and characteristics. In terms of absorption of harmful pollutants, the relevant tree species selection is necessary.