Analysis and Assessment of Contamination Degree and Emission Sources of Polycyclic Aromatic Hydrocarbons (PAHs and Me-PAHs) in Surface Sediments from Central Coast of Vietnam

Abstract

Polycyclic aromatic hydrocarbons (PAHs)  and their derivatives are a diverse group of organic pollutants, which are relatively persistent and toxic. Simultaneous determination of unsubstituted PAHs and methylated PAHs (Me-PAHs) is necessary to provide comprehensive insights into contamination levels and sources of these pollutants. In this study, we collected surface sediment samples in Vietnamese central coast to analyze 7 PAHs and 12 Me-PAHs. The sediment samples were extracted by using a focused ultrasonic processor with acetone/hexane (1:1) mixture and toluene. The extract was purified by column chromatography technique with activated silica gel and dichloromethane/hexane (1:3) as elution solvent. PAHs and Me-PAHs were determined by a gas chromatography/mass spectrometry (GC/MS) system operated in electron impact ionization (EI) and selected ion monitoring mode (SIM). Concentrations of total 7 PAHs and 12 Me-PAHs ranged from 30 to 246 (average 92) nanograms per gram sediment (ng/g). These levels were comparable to or lower than those measured in Vietnamese river sediments and marine sediments from some other countries in the world. The accumulation profiles of PAHs and Me-PAHs indicated that their emissions are likely associated with mixed pyrogenic and petrogenic sources. Our results have provided preliminary information about the pollution degree and accumulation characteristics of these substances in Vietnamese marine environments. Additional comprehensive studies should be performed to characterize contamination characterisrics, emission sources, and ecological risks of PAHs and their derivatives in this country.