Polycyclic aromatic hydrocarbons (PAHs) levels in PM and bulk deposition using Mosspheres: A pilot study in an urban environment.

Study air polycyclic aromatic hydrocarbons (PAHs) capturing the spatial variability of their concentrations is not economically feasible with conventional methods. In the present work we tested, for the first time and under real conditions, the suitability for intensive monitoring and mapping these contaminants of innovative, cost-effective passive air samplers known as "Mosspheres". The Mosspheres, filled with a devitalised Sphagnum palustre L. moss clone, were placed in a 575 m. grid in a medium-sized European city for three months. Concentrations in the moss tissues of 15 priority PAHs, including benzo(a)pyrene, were determined and converted into PM and bulk deposition with the equations proposed in a recent study. Low concentrations of PAHs were detected, with only a few enriched points never exceeding the legal thresholds, near industrial areas and busy roads. Despite these low PAH concentrations, Mosspheres were able to detect spatial structure for several PAHs and high-resolution pollution maps were constructed for these compounds. The results prove the high sensitivity and suitability of Mosspheres for mapping PAH levels and for quantitative (i.e. PAHs with 4 or more rings) and qualitative (3-ring PAHs) monitoring. Thus, this study supports their widespread application and its potential inclusion in European Directives on air quality control.