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High atmosphere–ocean exchange of semivolatile aromatic hydrocarbons


Polycyclic aromatic hydrocarbons, and other semivolatile aromatic-like compounds, are an important and ubiquitous fraction of organic matter in the environment. The occurrence of semivolatile aromatic hydrocarbons is due to anthropogenic sources such as incomplete combustion of fossil fuels or oil spills, and other biogenic sources1,2,3,4,5,6,7. However, their global transport, fate and relevance for the carbon cycle have been poorly assessed, especially in terms of fluxes3,5,8,9,10,11. Here we report a global assessment of the occurrence and atmosphere–ocean fluxes of 64 polycyclic aromatic hydrocarbons analysed in paired atmospheric and seawater samples from the tropical and subtropical Atlantic, Pacific and Indian oceans. The global atmospheric input of polycyclic aromatic hydrocarbons to the global ocean is estimated at 0.09 Tg per month, four times greater than the input from the Deepwater Horizon spill6. Moreover, the environmental concentrations of total semivolatile aromatic-like compounds were 102–103 times higher than those of the targeted polycyclic aromatic hydrocarbons, with a relevant contribution of an aromatic unresolved complex mixture. These concentrations drive a large global deposition of carbon, estimated at 400 Tg C yr−1, around 15% of the oceanic CO2 uptake12.

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Figure 1: Occurrence of PAHs in the global oceans.
Figure 2: Measured atmosphere–ocean exchange of PAHs.
Figure 3: Estimates of oceanic atmosphere–ocean exchanges of PAHs.
Figure 4: Comparison of the semivolatile aromatic-like compounds (SALCs) with the 64 targeted PAHs.


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This work was funded by the Spanish Ministry of Economy and Competitiveness (Circumnavigation Expedition Malaspina 2010: Global Change and Biodiversity Exploration of the Global Ocean. CSD2008-00077). B.G.-G. and M.-C.F.-P. acknowledge a predoctoral fellowship from BBVA Foundation and the Spanish National Research Council (CSIC), respectively. CSIC and the Spanish Government are also acknowledged for additional financial support. Thanks to RV Hespérides staff and UTM technicians during the cruise. D. García, G. Caballero and M. J. Ojeda are acknowledged for collaborating in the laboratory work.

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B.G.-G. participated in the sampling campaign, analysed the samples, estimated the fluxes and wrote the paper. J.D. participated in the sampling campaign and designed the sampling strategy and work, estimated the fluxes, and wrote the paper. C.M.D. led the Malaspina 2010 project and coordinated the overall sampling strategy for the project. L.Mé contributed in the chemical identification. M.-C.F.-P., L.Mo and B.J. participated in the sampling campaign. All authors have contributed to the discussion of the results and commented on the final version of the manuscript.

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Correspondence to Jordi Dachs.

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The authors declare no competing financial interests.

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González-Gaya, B., Fernández-Pinos, MC., Morales, L. et al. High atmosphere–ocean exchange of semivolatile aromatic hydrocarbons. Nature Geosci 9, 438–442 (2016).

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