Air–sea exchange and gas–particle partitioning of polycyclic aromatic hydrocarbons in the Mediterranean

Abstract

Polycyclic aromatic hydrocarbon (PAH) concentration in air of the central and eastern Mediterranean in summer 2010 was 1.45 (0.30-3.25) ng m −3 (sum of 25 PAHs), with 8 (1-17) % in the particulate phase, almost exclusively associated with particles < 0.25 µm. The total deposition flux of particulate PAHs was 0.3-0.5 µ g m −2 yr −1 . The diffusive air-sea exchange fluxes of fluoranthene and pyrene were mostly found net-depositional or close to phase equilibrium, while retene was net-volatilisational in a large sea region. Regional fire activity records in combination with box model simulations suggest that seasonal depositional input of retene from biomass burning into the surface waters during summer is followed by an annual reversal of air-sea exchange, while interannual variability is dominated by the variability of the fire season. One-third of primary retene sources to the sea region in the period 2005-2010 returned to the atmosphere as secondary emissions from surface seawaters. It is concluded that future negative emission trends or interannual variability of regional sources may trigger the sea to become a secondary PAH source through reversal of diffusive air-sea exchange.Capsule: In late summer the seawater surface in the Mediterranean has turned into a temporary secondary source of PAH, obviously related to biomass burning in the region.Published by Copernicus Publications on behalf of the European Geosciences Union.

Particulate PAHs and n-alkanes in the air over Southern and Eastern Mediterranean Sea

“…The minimum concentrations were measured offshore in T 3-3(1) , T 6-8 and T 8-9 . Concentrations presented in this work were for most PAHs lower than those found previously in the Black and Eastern Mediterranean Sea (CastroJimenez et al, 2012;Tsapakis and Stephanou, 2005), Pacific and Atlantic Oceans (Xu et al, 2012;Nizzetto et al, 2008;Del Vento and Dachs, 2007); on the other hand, our values were in agreement with data reported for Indian Ocean air (Liu et al, 2014) and Mediterranean sub-basins (Castro-Jim enez et al, 2012), as well as with cruise measurements performed in the south-eastern Mediterranean in summer 2010 (Mulder et al, 2014). The seasonality of emissions, the different maritime traffic in these regions or its combination with various cruise routes distinctly influenced by in land combustion sources on land (biomass burning, power plants etc.…”

“…These investigations were focused on both macro and micro-components, inorganic and organic substances, gaseous compounds, semi-volatile and particulate species. Nevertheless, rather than to marine air attention was overall paid to sea water (dissolved and suspended materials: Maldonado et al, 1999;Campanelli et al, 2004;Nizzetto et al, 2008;Berrojalbiz et al, 2011;Castro-Jim enez et al, 2012;Marrucci et al, 2013;Siemers et al, 2015), sediments (Gogou et al, 2000;Tsapakis et al, 2006;Cardellicchio et al, 2007;Perra et al, 2011;Acquavita et al, 2012Acquavita et al, , 2014Marini and Frapiccini, 2013;Net et al, 2015) and sea/air interface (Marty et al, 1988;Manodori et al, 2006;Lohmann et al, 2009;Guitart et al, 2010;Mulder et al, 2014).…”

Persistent organochlorine pesticides and polychlorinated biphenyls in air of the North Sea region and air-sea exchange

“…However, air-sea exchange of POPs is controlled by the combination of the parameters temperature, wind speed and concentration in surface water (Stemmler and Lammel 2011). Moreover, it has been observed that the direction of air-sea exchange may fluctuate once the substance concentration has approached (or is close to) phase equilibrium on a range of time scales (Jantunen and Bidleman 1995; Stemmler and Lammel 2009; Berrojalbiz et al 2014; Mulder et al 2014; Lammel et al 2016). This could explain these observations.…”

Distribution pattern and mass budget of sedimentary polycyclic aromatic hydrocarbons in shelf areas of the Eastern China Marginal Seas

“…Anthropogenic PAHs are omnipresent in environmental matrices and are found in the atmosphere, soil, water, ice, sediment, and food web [ Chen et al ., ; C. Wang et al ., ; Lohmann et al ., ; Yuan et al ., ; Stout and Graan , ; Huang and Batterman , ], due to the global distribution of sources and the resistance of PAHs to degradation. Marine sediments usually act as important sinks for anthropogenic PAHs through two major pathways, riverine discharge and atmospheric deposition [ Wang et al ., ; Mulder et al ., ; González‐Gaya et al ., ]. Following release into the marine environment, most PAHs bind to fine particles, due to their high hydrophobicity and lipid solubility, and are deposited in the bottom sediments.…”