PCDD/F/PCB emissions from energy generation in Central Europe: uptake mechanisms in biomass, fingerprint profiling and source modeling

National emission inventories in Central Europe attribute PCDD/F releases mainly to energy generation. The chemical industry contributes only a minor share. To test the validity of these inventories, we focus on Poland's national PCDD/F data, the second-largest emitter in Central Europe after Germany. We follow two lines of enquiry into PCDD/F/PCB emissions, i.e., from energy generation and chemical industry. We draw on environmental fingerprints of PCDD/F/PCB in tree bark, conifer needles, and soil, and include characterization of the herbicide Aminopielik. To gain insights into the uptake mechanisms of PCDD/F/PCB in the bark, we study the variation in loading and fingerprints across the bark thickness. The high limits of quantitation (LOQ) for the mono-ortho congeners of dioxin-like PCB (dl-PCB) constrained our ability to perform a comprehensive analysis comparable to that achieved for PCDD/F. Fingerprint profiling of PCDD/F provides input data for contamination source modeling, using cluster and principal component analyses, as well as positive matrix factorization (PMF), to allow matching the fingerprints against a broad range of potential emission sources in Central Europe. We find that the historical uptake of PCDD/F in the bark, with the translocation and transpiration streams within trees and their subsequent transfer to rhytidome, is practically insignificant compared to the present atmospheric absorption. We also confirm that samples of bark and conifer needles, collected in forests, probe different sources, and discover that atmospheric deposition of PCDD/F/PCB onto the lipid-rich algal/lichen layers on tree trunks amplifies bark toxicity, as high oil solubility of PCDD/F/PCB promotes their retention within these matrices. For our study site, the PMF analysis allocates 19.6 % of PCDD/F pollution in the atmosphere to coal, municipal and household waste combustion, 41.6 % to release from diesel and unleaded vehicles and 38.8 % to combustion of wood for domestic heating. While our measurements of emissions of PCDD/F provide no evidence of sources linked to chemical manufacturing, we also detect an unknown source of dl-PCB that may stem from industrial activity and identify high PCDD/F content in Aminopielik. The results of the present work stress progress in controlling the output of trace pollutants from energy generation in Central Europe, and emerging technological challenges.