Polycyclic aromatic hydrocarbons (PAHs) pollution recorded in annual rings of gingko (Gingko biloba L.): Regression analysis and comparison to other pollutants

Further interesting information about contamination recorded in gingko annual rings is revealed in this paper. The degradation degrees of varied PAHs in gingko trunk, range 2.4 to 3.4%, are evaluated by using regression analysis and confirmed to depend upon their molecular sizes and chemical properties. For other lipophilic compounds, the translocation and diffusion behaviors conform to our donut model of PAHs in previous work, while for hydrophilic contaminants, the translocation and diffusion are more complicated owing to the second uptake pathways by roots. Further, the gingko tree exhibits selective absorption to heavy metals, such as Cu, Cd, Zn, Cr, Pb, Ni, Fe, and Mn. The relative accumulation degrees of these heavy metals are estimated by comparing to Fe in the soil and the gingko tree, and the result suggests that the gingko accumulates Cr, Cd and Pb from the soil. However, the metals in annual rings might not reflect historical environment changes for their diffusive nature in water-sapwood.