Temporal change of the accumulation of persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in lichens in Switzerland between 1995 and 2014

The aim of this study was to assess the temporal change of atmospheric deposition patterns of persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) in Switzerland between 1995 and 2014 by a passive biomonitoring with lichens. Lichen tissues sampled at 16 representative sites in the same season of 1995 and 2014 were analyzed for a total of 94 individual and 27 sum parameters of POPs and PAHs by means of gas chromatography-mass spectrometry (GC/MS). The comparative analyses showed a decrease of 40 to 80% (medians) for most of the POPs and PAHs concentration in lichens at all site categories. Reduction in tissue concentration of the polychlorinated dibenzo-p-dioxins/furans (PCDD/PCDFs), such as the highly toxic 2,3,7,8-TetraCDD and the TEQ according to WHO (2005) were 66% and 73%, respectively. For the dioxin- and non-dioxin-like PCBs, a decrease of 67% and 58% was found. The average decrease of 30 organochlorine pesticides and insecticides (OCPs) was 65%, with a 94% decrease for lindane. For the 27 PAHs and for benzo(a)pyrene, an average decrease of 58% and 59% was found. Polybrominated diphenyl ethers (PBDE) showed reduced concentrations in lichens at rural and agglomeration sites, but an increase of contamination was observed at industrial and road traffic sites. The direct comparison of changes of POPs and PAHs concentrations in lichens and of emissions between 1995 and 2014 revealed consistent results. The results of this study highlight for the first time in biota the positive effect of emission regulation of POPs in Switzerland.