Preliminary investigation on the occurrence of PCNS in ambient air of Ho Chi Minh City, Vietnam

Abstract

Polychlorinated Naphthalenes (PCNs) were included as the new Persistent Organic Pollutants (POPs) under the Stockholm Convention and forced to terminate the production and use in any application due to their toxicity, bioaccumulation, persistence and adverse effects to the environment and humans. However, no study on the occurrence of PCNs in the environment in Vietnam has been conducted so far. Therefore, it is necessary to carry out an investigation on the presence of these pollutants in Vietnam. In this study, ambient air samples were collected at 5 different sites in the urban area of Ho Chi Minh City to investigate the occurrence of PCNs. Fourteen air samples (both gas and particulate phases) were collected using large volume samplers. Totally, 75 PCNs in gas and particulate phases were analyzed using HRGC/HRMS following isotope dilution method. Total concentrations of PCNs measured at five sites ranged from 60.4 pg/m³ to 264 pg/m³ (mean 134 pg/m³), which was significantly higher than those reported by similar studies around the world. The result also indicated that gaseous PCNs predominated in total atmospheric concentration (99.7 – 100%); while particulate PCNs only contributed minor faction. Based on the characteristics of the analyzed PCNs, the samples were divided into 2 groups, group 1 is characterized by TetraCN as the main contributor, while group 2 is dominated by low-chlorine homologues (1 to 3 chlorines). The results also revealed that the PCNs in the air samples in HCMC were mainly derived from evaporation of PCNs from products containing PCNs and combustion-related sources. However, evaporation of PCNs from products containing PCNs seemed to be the dominant source.