Sources and fate of polycyclic aromatic hydrocarbons in the Antarctic and Southern Ocean atmosphere

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are a geochemically relevant family of semivolatile compounds originating from fossil fuels, biomass burning, and their incomplete combustion, as well as biogenic sources. Even though PAHs are ubiquitous in the environment, there are no previous studies of their occurrence in the Southern Ocean and Antarctic atmosphere. Here we show the gas and aerosol phase PAHs concentrations obtained from three sampling cruises in the Southern Ocean (Weddell, Bellingshausen, and South Scotia Seas), and two sampling campaigns at Livingston Island (Southern Shetlands). This study shows an important variability of the atmospheric concentrations with higher concentrations in the South Scotia and northern Weddell Seas than in the Bellingshausen Sea. The assessment of the gas-particle partitioning of PAHs suggests that aerosol elemental carbon contribution is modest due to its low concentrations. Over the ocean, the atmospheric concentrations do not show a temperature dependence, which is consistent with an important role of long-range atmospheric transport of PAHs. Conversely, over land at Livingston Island, the PAHs gas phase concentrations increase when the temperature increases, consistently with the presence of local diffusive sources. The use of fugacity samplers allowed the determination of the air-soil and air-snow fugacity ratios of PAHs showing that there is a significant volatilization of lighter molecular weight PAHs from soil and snow during the austral summer. The higher volatilization, observed in correspondence of sites where the organic matter content in soil is higher, suggests that there may be a biogenic source of some PAHs. The volatilization of PAHs from soil and snow is sufficient to support the atmospheric occurrence of PAHs over land but may have a modest regional influence on the atmospheric occurrence of PAHs over the Southern Ocean.

Analysis of air mass back trajectories with present and historical volcanic activity and anthropogenic compounds to infer pollution sources in the South Shetland Islands (Antarctica)

“…3). If we assume, on the basis of air mass trajectories presented herein and by other authors (Lee et al , 2007Chambers et al 2014;McConnel et al 2014), that such transport is possible, and we take into account the high activity of volcanoes in the Southern Hemisphere (Table 1), it can be assumed that such events could have occurred in the past. The model of the global distribution of volcanic sulphur (Graf et al 1997) confirms the possibility of this source of compounds influencing the Antarctic environment.…”

“…Many authors have pointed out that some contaminants occurring in Antarctica could be related to LRAT (inter alia, Lee et al 2004Lee et al , 2007Klánová et al 2008;Chambers et al 2014;McConnel et al 2014), but there is still little knowledge about the frequency of air masses incoming from lower latitudes to the Antarctic Peninsula. The 10-day back trajectories for the period September 2015 to August 2017 show that long-range transport by air masses to the South Shetland Islands occurs relatively often (44% of researched days) and the most frequent source area is South America (31% of researched days).…”

“…volcanic eruptions). This is mainly due to long-range atmospheric transport (LRAT) (Corsolini 2009;Cabrerizo et al 2014). The presence of industrial, agricultural and volcanic compounds in Antarctica is explained by the phenomenon of global distillation (Corsolini 2009): contamination resulting from numerous evaporation and condensation processes may move to ever-higher latitudes (Bengtson-Nash 2011).…”

“…Although the inflow of pollutants to the Antarctic is being limited by the range of circumpolar air circulation, the possibility of long-range atmospheric pollution has been indicated in some works (e.g. Lee et al 2004;Mishra et al 2004;Kallenborn et al 2013;Cabrerizo et al 2014). Therefore, the paper analyses the possibility of atmospheric transport of pollution to the South Shetlands.…”

Introduction to the special issue on the Life in Antarctica: Boundaries and Gradients in a Changing Environment (XIth SCAR Biology Symposium)

“…The intense industrialization of the world brought new compounds and new hazards to Earth ecosystems, and Antarctica was not an exception. The global distribution of substances, exemplified by the ozone hole distribution, is bringing substances to Antarctica produced in the northern hemisphere which are accumulated at high concentrations due to the polar amplification (Cabrerizo et al 2014), with unknown ecological effects.…”