Gas-particle distributions, sources and health effects of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in Venice aerosols

Highlights

• Gas-particle distribution of POPs in Venice is discussed.

• PCB-11 was found for the first time in aerosols in Venice and Europe.

• A high concentration of PCN-42 in 2009 samples was measured.

• Traffic was the major source of PAHs.

• A toxicological evaluation by TCA and TEQ methods was conducted.

Abstract

Air samples were collected in Venice during summer 2009 and 2012 to measure gas and particulate concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs). PCB-11, considered a marker for non-Aroclor contamination of the environment, was found for the first time in the Venetian lagoon and in Europe. An investigation on sources has been conducted, evidencing traffic as the major source of PAHs, whereas PCBs have a similar composition to Aroclor 1248 and 1254; in 2009 a release of PCN-42 has been hypothesized. Toxicological evaluation by TCA and TEQ methods, conducted for the first time in Venice air samples, identified BaP, PCB-126 and PCB-169 as the most important contributors to the total carcinogenic activity of PAHs and the total dioxin-like activity of PCBs and PCNs.

Introduction

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) are semi-volatile organic compounds that are persistent and ubiquitous in the environment. PAHs can be produced by incomplete combustion from natural origins (e. g. volcanism, natural fires) or from anthropogenic origins (e. g. combustion of timber, waste, and fossil fuels). PCBs were first synthesized in 1929 and were widely used as dielectric fluids, hydraulic fluids and in many other applications until they were banned in the late 1970s (Desaules et al., 2008). PCNs were used in the electrical industry owing to their water-repellent, flame-retardant, dielectric and fungus-resistant properties. In addition, PCNs can be unintentionally generated by several industrial processes and by incomplete combustion from waste incinerators (Manodori et al., 2006a). Because of their toxicity and low reactivity PAHs, PCBs and PCNs are classified as POPs (Persistent Organic Pollutants) (Helm and Bidleman, 2003, UNECE (United Nations Economic Commision for Europe), 1998).

POPs are affected by long-range atmospheric transport (LRAT) and their presence has been discovered in remote environments such as the Arctic (Hung et al., 2005, Polkowska et al., 2011) and Antarctica (Dickhut et al., 2012, Klanova et al., 2008, Negri et al., 2006). Bioaccumulation of these substances can cause adverse effects on human health including reproductive and immune effects, developmental anomalies and cancer (Desaules et al., 2008, Gambaro et al., 2004). Generally the atmospheric burden of POPs is relatively small compared to other environmental constituents but air is considered the most important pathway for their global redistribution (Piazza et al., 2013).

PAHs, PCBs and PCNs exist in the atmosphere as vapor phase chemicals and in a condensed form where they are adsorbed on atmospheric particles. Gas to particle partition of pollutants depends on molecular weight, atmospheric conditions (temperature, humidity and precipitation), the nature (origin and properties) of the aerosol, interactions between the compounds and the aerosol and the overall behavior of compounds in the atmosphere (Hassan and Khoder, 2012). The distribution between the gaseous and particle-bound phases is the most important factor determining removal mechanisms and residence time in the atmosphere (Gambaro et al., 2004). This distribution strongly influences POP transport and how pollutants enter the human body. Therefore, the evaluation of gas-particle distribution of pollutants in the atmosphere has received worldwide attention. Studies of POPs in the Venice lagoon have principally focused on sediments (Frignani et al., 2001, Frignani et al., 2004, Moret et al., 2001) and surface waters (Manodori et al., 2006b, Moret et al., 2005) but very little is known about the role of aerosols in the transport of pollutants into the lagoon system and the gas-particle partition of POPs in this area.

The first objective of this work is to characterize the gas-particle distribution profile of atmospheric PAHs, PCBs and PCNs. Due to the importance of estimating the possible origin of pollutants in this area, we examined the sources of PAHs, using the diagnostic ratio method. This study presents the first Venetian lagoon samples that evaluate the toxicological activities of PAHs and the dioxin-like activity of PCBs while focusing on the differences between gas and particulate toxicological characteristics.