Seasonal trends and retention of polycyclic aromatic compounds (PACs) in a remote sub-Arctic catchment

Minh A Nguyen; Lutz Ahrens; Sarah Josefsson; Jakob Gustavsson; Hjalmar Laudon; Karin Wiberg

doi:10.1016/j.envpol.2023.121992

Seasonal trends and retention of polycyclic aromatic compounds (PACs) in a remote sub-Arctic catchment

Environ Pollut. 2023 Sep 15:333:121992. doi: 10.1016/j.envpol.2023.121992. Epub 2023 Jun 20.

Authors

Minh A Nguyen¹, Lutz Ahrens¹, Sarah Josefsson², Jakob Gustavsson¹, Hjalmar Laudon³, Karin Wiberg⁴

Affiliations

¹ Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Box 7050, SE-750 07, Uppsala, Sweden.
² Geological Survey of Sweden, Box 670, SE-751 28, Uppsala, Sweden.
³ Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), SE-901 83, Umeå, Sweden.
⁴ Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Box 7050, SE-750 07, Uppsala, Sweden. Electronic address: karin.wiberg@slu.se.

PMID: 37348698
DOI: 10.1016/j.envpol.2023.121992

Abstract

Atmospheric deposition is the most dominant source of polycyclic aromatic hydrocarbons (PAHs) in remote and pristine areas. Despite low bioaccumulation potential, PAHs and their persistent transformation products (PAH-derivatives) are chemicals of concern as they can harm human and animal health through chronic low dose exposure. In this study, atmospheric deposition fluxes of polycyclic aromatic compounds (PACs) were measured on a seasonal basis (3-month periods) from 2012 to 2016 in a remote subarctic forest catchment in northern Europe. The target PACs included 19 PAHs and 15 PAH-derivatives (oxygenated, nitrogenated, and methylated PAHs). The deposition fluxes of ƩPAHs and ƩPAH-derivatives were in the same range and averaged 530 and 500 ng m² day^-1, respectively. The fluxes were found to be higher with a factor of 2.5 for ƩPAHs and a factor of 3 for ƩPAH-derivatives during cold (<0 °C) in comparison to warm (>10 °C) periods. PAHs and PAH-derivatives showed similar seasonal patterns, which suggests that these two compound classes have similar sources and deposition mechanisms, and that the source strength of the PAH-derivatives in air follows that of the PAHs. The terrestrial export of PACs via the outlet of the catchment stream was estimated to be 1.1% for ƩPAHs and 1.7% for ƩPAH-derivatives in relation to the annual amounts deposited to the catchment, which suggests that boreal forests are sinks for PACs derived from the atmosphere. Some individual PACs showed higher export than others (i.e. chrysene, cyclopenta(c,d)pyrene, carbazole, quinoline, and benzo(f)quinoline), with high export PACs mostly characterized by low molecular weight and low hydrophobicity (2-3 benzene rings; log K_ow<6.0).

Keywords: Atmospheric deposition; Boreal catchment; Cold climate; Nitrogenated, and methylated PAHs; Oxygenated; PAHs and PAH-Derivatives; Polycyclic aromatic compounds (PACs); Polycyclic aromatic hydrocarbons (PAHs); Seasonal trends; Snow; Terrestrial export; Terrestrial retention; Wet and dry deposition.

MeSH terms

Air Pollutants* / analysis
Animals
Environmental Monitoring
Europe
Humans
Polycyclic Aromatic Hydrocarbons* / analysis
Polycyclic Compounds*
Seasons

Substances

Polycyclic Compounds
Polycyclic Aromatic Hydrocarbons
Air Pollutants