Polycyclic aromatic hydrocarbons (PAHs) in sediment environments in Vietnam: Analytical methods and contamination status

Introduction: Polycyclic aromatic hydrocarbons (PAHs) are prevalent organic pollutants that garner attention due to their toxicity and carcinogenic properties. These hydrophobic compounds tend to accumulate in the organic components of sediments, posing significant ecological risks. Methods: This study synthesizes analytical methodologies and assesses the contamination status of PAHs in Vietnamese sediments through a review of previous studies complemented by recent findings from our research group. Various extraction techniques, including Soxhlet extraction, pressurized liquid extraction, continuous solid-liquid extraction, and ultrasonic extraction, were employed using organic solvents of low to moderate polarity (e.g., hexane, acetone, toluene, dichloromethane). Purification was achieved via column chromatography using sorbents like silica gel, alumina, and Florisil, followed by gel permeation chromatography. Separation and analysis were primarily conducted through gas chromatography/mass spectrometry (GC/MS). Results: PAHs were detected in all samples, with concentrations ranging from 33 to 6400 ng/g, indicating widespread contamination. The sources of PAHs in Vietnamese sediments appear to be predominantly urban and informal waste processing areas. The levels of sedimentary PAHs in Vietnam are on par with those reported in other Asian countries, with the majority of PAHs being traced back to pyrogenic sources, as opposed to petroleum products. Conclusions: Our findings offer a detailed understanding of the distribution, patterns, and potential sources of PAHs in Vietnamese sediments. The notably higher concentrations of PAHs in urban and waste processing sites underscore the urgency of implementing effective management and remediation strategies. The study advocates for further monitoring of PAHs and related pollutants to fully elucidate their contamination scope, origins, and ecological consequences.