The distribution and origin of PAHs over the Asian marginal seas, the Indian, and the Pacific Oceans: Implications for outflows from Asia and Africa

Abstract

Aerosol samples were collected aboard the R/V Dayang Yihao from 8 January to 7 August 2007 to investigate the geographical distribution of polycyclic aromatic hydrocarbons (PAHs) over oceans and to assess their continental origins. The highest concentrations were found over the marginal seas in Asia, especially the East and South China Seas, indicating that China is a top source of emissions into the marine atmosphere in the areas monitored on this cruise. PAH concentrations over the west oceanic region in the South Indian Ocean were noticeably higher than in other areas of the Indian Ocean, most likely because air masses from Africa, the Arabian Sea, and the Bay of Bengal exert a negative impact on those regions through long-range atmospheric transport. The PAH isomer ratio values varied over the oceans that were impacted by continental sources but remained relatively uniform over most of the remote oceans. Using diagnostic ratio analysis, we found PAHs emitted from China were mainly associated with biomass/coal burning. The measurements of levoglucosan were consistent with the results mentioned above. The western part of the South Indian Ocean atmosphere was likely affected by wildfire emissions from Africa, while the northern part was by petroleum combustion, biofuel, and wildfire burning, because the winter monsoon most likely carries aerosol from the Arabian Peninsula and India across the equator. Using the monthly images of fire activity and aerosol optical depth, it can be confirmed biomass burning from Africa can significantly influence the aerosol over the Indian Ocean.

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.…”

“…Studies dealing with composition of marine aerosols started at rural locations over the coasts more than 30 years ago, (Sicre et al, 1987;Gogou et al, 1998;Gigliotti et al, 2000;Kavouras and Stephanou, 2002;Almeida et al, 2005;Tsapakis and Stephanou, 2007;Wang et al, 2013), and continued by means of ship cruises across seas (Tsapakis and Stephanou, 2005;Moreno et al, 2010;Velchev et al, 2011) and oceans (Jaward et al, 2004;Ding et al, 2007;Xu et al, 2012;Lohmann et al, 2013;Liu et al, 2014). These investigations were focused on both macro and micro-components, inorganic and organic substances, gaseous compounds, semi-volatile and particulate species.…”

Sources of non-fossil-fuel emissions in carbonaceous aerosols during early winter in Chinese cities

“…OC and EC were obtained with an offline carbon analyzer (Sunset Laboratory, Inc., USA) using the thermo-optical transmittance method (NIOSH 870 (Wang et al, 2012) and anhydrosugars (Liu et al, 2014a;2014b) are presented elsewhere and a detailed analytical procedure and method are available in the Supplement.…”

Global simulation of semivolatile organic compounds – development and evaluation of the MESSy submodel SVOC (v1.0)

“…For K p calculation four options of gas-particle partitioning schemes are available in SVOC: (1) a parameterization that is based on adsorption onto aerosol surface (Junge, 1977;Pankow, 1987), (2) absorption into organic matter (Finizio et al, 1997), (3) a combination of the two ways of organic matter absorption and black carbon adsorption (Lohmann and Lammel, 2004), and (4) multiple phases of the two-way sorption system (Goss and Schwarzenbach, 2001;Endo and Goss, 2014;Shahpoury et al, 2016). Two schemes used in this study are described below.…”