Persistent Organic Pollutants (POPs) in the European Atmosphere: An Updated Overview

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The industrial revolution and the resultant technological society have led to a continuous production and emission of new toxic substances causing gradual and widely diffuse adverse effects to the entire planet usually known as Global Environmental Changes. Climate change, ozone depletion and global distribution of persistent organic pollutants (POPs) are, among other, important examples of detriment of global environmental quality. POPs are a group of chemicals which share some specific characteristics, such as hidrofobicity, bioaccumulation potential, toxicity and persistence that make them of high international concern. Due to their semivolatility, POPs present a widespread distribution being able to reach remote locations and areas after traveling long distances in the atmosphere where they have never been produced nor used. Different chemical families are considered as POPs, such as polychlorinated biphenyls (PCBs), a wide spectrum of organochlorine pesticides (OCPs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), and, polychlorinated naphthalenes (PCNs). In addition, some emerging contaminants are currently considered as candidate POPs, like the polybrominated diphenyl ethers (PBDEs) and the perfluorinated compounds (PFCs).

POPs exist in the atmosphere as gases and bound to particles depending on their physicochemical properties. For instance, most measurements are dominated by the gas-phase concentrations for PCBs, whereas airborne PCDD/Fs are mainly associated to particles. This affinity to gas or particulate phase is of relevant importance in the processes of POP atmospheric global transport and degradation (mode of transport and exposure to primary or secondary photooxidation may be different). POPs are delivered to aquatic and terrestrial ecosystems by atmospheric deposition, air-water interchanges and direct discharges. The general hydrophobic nature of POPs results in high affinity to organic matter and biota tissues. Consequently, organisms and sediments become final “sinks” of POPs due to the low metabolic activity for these compounds and their slow degradation processes in the environment.
A number of national and international actions have been promoted to reduce or ban their production and control their emissions to the environment. At a global scale, the UNEP Stockholm Convention adopted in May 2001 aims to reduce and eliminate emissions of selected POPs into the environment. In addition, it contemplates a Global Monitoring Programme as an instrument to assure its implementation. In the Artic region (eight circumpolar countries) the Artic Monitoring and Assessment Programme (AMAP) is measuring atmospheric concentrations of POPs since it was established in 1991 (Figure 1). At a European scale a big effort is being carried out combining the update of existing monitoring programmes with the generation of new legislations. Such is the case of the largest monitoring network across Europe gathering concentrations of POPs in air and deposition (the Cooperative Programme for Monitoring and
Evaluation of the Long-range Transmission of Air Pollutants in Europe, EMEP). This monitoring network operates under the UNECE Convection on Long-range Transboundary Air Pollution (CLRTAP) that was recently extended by a protocol on POPs. The EMEP network officially started to monitor POPs in 1999 but only a few sites are currently active within the network. On the political side, the brand new European legislation on chemicals, REACH (Registration, Evaluation and Authorization of Chemicals) will regulate the production of chemicals at a European scale. In addition, other POPs monitoring programmes exist at regional or national scales (eg. TOMPS in UK, NJADN in New Jersey-US, CBADS in Chesapeake Bay-US) and a large number of “independent” sites measuring atmospheric concentrations of POPs are spread out in the European geography. Considering such a scenario it seems obvious that a strong effort in harmonization and communication of results and monitoring and research strategies needs to be achieved.

A step to facilitate this needed interaction was the workshop on “Persistent Organic Pollutants (POPs) in the European Atmosphere – Concentration, Deposition and Sources in Europe –“ organized by the European Commission Joint Research Center held in October 17-19th, 2005 in Stresa (Italy). It was one of the objectives of the workshop to gather top experts from Europe and North America to share their expertise on POP monitoring and research in the atmospheric compartment in order to evaluate their current status in Europe. Invited experts (Annex I) develop their professional activities either in the existing POPs monitoring networks or in research institutions closely linked to POPs research. Other objectives of the workshop were to explore future research lines on the topic and to establish links with the existing science and new policies in Europe regarding chemicals. Twenty oral communications were presented covering the following key issues on POPs:

• Emission database: knowledge and reliability
• Atmospheric monitoring programmes in Europe and North America: current status
(Figure 1) and future schemes based on actual experiences
• State of the art in sampling strategies
• Atmospheric processes, global transport mechanisms and deposition behavior
• The role of the POP atmospheric inputs into terrestrial and aquatic ecosystems
• Research open questions and needs

In this report a compilation of the extended abstracts submitted by the participants is presented, whereas the working result output of the workshop will be submitted as an article to a peerreviewed scientific journal.
The Organizing Committee thanks to all participants from the workshop for their fruitful contributions. This EU report is a direct reflection of their expertise.

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