Molecular Distributions and Compound-Specific Stable Carbon Isotopic Compositions of Plant Wax n-Alkanes in Marine Aerosols along a North–South Transect in the Arctic–Northwest Pacific Region

Jung-Hyun Kim,Sol-Bin Kim,Jiyeon Park,Yeontae Gim,Sookwan Kim,Kyung-Hoon Shin

doi:10.3390/atmos11050499

Abstract

A geographical source of n-alkanes in marine aerosols was assessed along a North–South transect in the Arctic–Northwest Pacific region. Marine aerosol samples were collected during the ARA08 cruise with the R/V Araon between 28 August and 28 September 2017. We investigated molecular distributions of n-alkanes (homologous series of C16 to C34) and compound-specific stable carbon isotopes (δ13C) of n-C27, n-C29, and n-C31. Unresolved complex mixtures (UCM) showed a latitudinal trend from the Arctic Ocean to the northwest Pacific Ocean, highlighting an increasing influence of the plume of polluted air exported from East Asian countries. The anthropogenic input was further evidenced by high U/R ratios (>5) and low CPI17–23 (0.6–1.4). The occurrence of high molecular weight (HMW) n-alkanes with high CPI27–31 (>3) indicated the biogenic input of terrestrial higher plant leaf waxes in all studied samples. The δ13C of HMW n-alkanes was influenced by both the relative contributions from the C3/C4 plant sources and from fossil fuel combustions. The back-trajectory analyses provided evidence that changes in molecular distributions and δ13C of n-alkanes were due to the long-range atmospheric transport of anthropogenic and biogenic organic materials from North American and East Asian countries to the Arctic Ocean and the remote northwest Pacific Ocean, respectively.

Highlights

Our results are in good good agreement with previous studies which showed the presence of Unresolved complex mixtures (UCM) hydrocarbons in marine agreement with previous studies which showed the presence of UCM hydrocarbons in marine aerosol samples collected over the northwest Pacific Ocean, the East China Sea, and the East Sea of aerosol samples collected over the northwest Pacific Ocean, the East China Sea, and the East Sea of
We investigated molecular distributions and δ13 C of n-alkanes in marine aerosols collected along a transect from the Arctic Ocean to the northwest Pacific Ocean
The anthropogenic input was evidenced by the presence of UCM, high unresolved to resolved hydrocarbon components (U/R) ratios, and low carbon preference index (CPI) values for low molecular weight n-alkanes

Summary

Introduction

The n-alkanes originate from both anthropogenic and biogenic sources, including petroleum residue [1], biomass burning [2], and terrestrial plant wax, fungi, bacteria, algae, and plankton [3].High molecular weight (HMW) n-alkanes (>n-C25 ) are typical land-derived lipid biomarkers which can be carried from adjacent continents to remote oceanic settings by long-range atmospheric transport [4,5,6,7].Investigations of HMW n-alkanes in marine aerosols have been widely conducted in the AtlanticOcean [5,8,9], the Pacific Ocean [10,11,12], and the Southern Ocean [11]. High molecular weight (HMW) n-alkanes (>n-C25 ) are typical land-derived lipid biomarkers which can be carried from adjacent continents to remote oceanic settings by long-range atmospheric transport [4,5,6,7]. HMW n-alkanes are often found in marine surface sediments close to continental land in the Atlantic Ocean [13,14,15], the Pacific Ocean [16,17], and the Southern Ocean [18], reflecting latitudinal vegetation changes on the continent. The distributions and isotopic signatures of HMW n-alkanes extracted from marine sediment cores have successfully been used to reconstruct changes in terrestrial vegetation. Long-range atmospheric transport is an important for the land-derived

Methods

Results

Discussion

Conclusion