Linking the contents of hydrophobic PAHs with the canopy water storage capacity of coniferous trees

Highlights: • In conifer species, the SUM. PAH is related to the canopy storage capacity (S). • PAHs contamination and S are strongly related to the species and location. • An increase in SUM.PAH causes an increase of canopy storage capacity. • Canopy storage capacity is highest at all locations for the Picea, and lowest for the Abies. • The highest SUM.PAH was found for Picea and lower for Abies and Pinus at all locations. The canopy water storage capacity (S) is an important parameter for the hydrological cycle in forests. One factor which influences the S is leaf texture, which in turn is thought to be affected by the contents of polycyclic aromatic hydrocarbons (PAHs). In order to improve our understanding of S we simulated rainfall and measured the S of coniferous species growing under various conditions. The contents of 18 PAHs were measured in the needles. The species chosen were: Scots pine (Pinus sylvestris L), Norway spruce (Picea abies (L.) H. Karst) and silver fir (Abies Alba Mill.). Sample branches were collected in 3 locations: A - forest; B - housing estate; C - city center. We found that PAHs have a significant impact on the S of tree crowns. The increase in the total content of all of polycyclic aromatic hydrocarbons (SUM.PAH) translates into an increase of S for all species. The S is the highest for the P. abies species, followed by P. sylvestris and A. alba at all locations. Within the same species, an increase in the value of S is associated with an increase in the PAH content in needles measured by gas chromatography. For A.alba, the average S increased from 11.54% of the total amount of simulated rain (ml g⁻¹) at location A, to 17.10% at location B, and 21.02% at location C. Similarly for P. abies the S was 21.78%, 29.06% and 34.36% at locations A, B and C respectively. The study extends the knowledge of the mechanisms of plant surface adhesion and the anthropogenic factors that may modify this process as well as foliage properties.