Long-range atmospheric transport of polycyclic aromatic hydrocarbons is worldwide problem - results from measurements at remote sites and modelling

Abstract

Despite the fact that the occurrence of polycyclic aromatic hydrocarbons (PAHs) in the atmospheric environment has been studied for decades the photochemistry, deposition and, consequently, the long-range transport potential (LRTP) are not well understood. The reason is gas-particle partitioning (GPP) in the aerosol, its sensitivity to temperature and particulate phase composition, and sampling artefacts', and reactivity's sensitivities towards particulate phase composition. Furthermore, most PAHs are subject to re-volatilisation upon deposition to surfaces (multihopping). Levels and sources of 2-6-ring unsubstituted PAHs were studied in remote environments of Europe, Africa and Antarctica. Global atmospheric transport and fate of 3-5-ring PAHs were simulated under various scenarios of photochemistry and GPP. GPP influences drastically the atmospheric lifetime, compartmental distributions and the LRTP of PAH. Mid latitude emissions seem to reach the Arctic but not the Antarctic.

Determination of polycyclic aromatic hydrocarbons (PAHs) and other organic pollutants in freshwaters on the western shore of Admiralty Bay (King George Island, Maritime Antarctica)

“…In places where it is impossible to calculate the NP/PHE ratio, the principle and only designated compound from the PAH group is NP (samples 2.1, 2.3, 3.1, 4.1, 4.3, 5.1, 5.2). Due to its high volatility, this suggests that the more likely source of origin for both PHE and NP will be long-range atmospheric transport—LRAT (a global source) (Lammel et al 2015 ).…”

Polycyclic aromatic hydrocarbons (PAHs) and oxy- and nitro-PAHs in ambient air of the Arctic town Longyearbyen, Svalbard

“…Gas-particle partitioning is an important process that controls transport, degradation, and distribution patterns of contaminants in and between environmental compartments (Finlayson-Pitts and Pitts, 1999;Lammel et al, 2009;Franklin et al, 2000). The sampling campaign in the present study was conducted from late Arctic summer until early autumn and during this period the air temperature varied from +6.8 in August to −4.4 • C in September and several precipitation events (snow and rain) occurred.…”

“…Under unique Arctic weather conditions, with extreme temperatures, wind, and light seasonality, atmospheric PAHs may behave differently compared to in temperate climatic conditions. Low temperatures favour the partitioning of semi-volatile PAHs from gas phase to particulate phase, which makes them more persistent in the Arctic environment (Lammel, 2015). Due to extended winter darkness in the Arctic, photodegradation of PAHs is limited for several months.…”

Hygroscopic Coating of Sulfuric Acid Shields Oxidant Attack on the Atmospheric Pollutant Benzo(a)pyrene Bound to Model Soot Particles

“…Ageing of soot particles can also bring changes in cloud albedo (Twomey effect) and precipitation pattern 34 . It is believed that the experimental rate coefficient values are possibly overestimations compared to the real atmospheric values 40 , because in real atmosphere, particle associated PAHs are shielded from atmospheric oxidants which have not yet been mimicked in the experiments. BaP apparently undergoes faster chemical degradation compared to that in real atmosphere.…”