Application of Positive Matrix Factorization for Source Apportionment of Polycyclic Aromatic Hydrocarbons (PAH) in the Adriatic Sea, and the Evaluation of PAH-Related Carcinogenic Risks  
[PERSON]  
1 Daboratory of Chemical Oceanography and Sea Sedimentology, Institute of Oceanography and Fisheries,  
Setaliste [PERSON] 63,usually contain a greater amount of low molecular weight PAH and alkyl-substituted PAH, while PAH mixtures from pyrogenic sources are enriched in unsubstituted PAH compounds with higher molecular weight. PAH are introduced into the marine environment mainly through rivers, atmospheric deposition, municipal and industrial runoff, and accidental spills of fresh petroleum derivatives. Due to their high hydrophobicity, PAHs adsorb to particles in the water column and sink through the water column. Sediments can accumulate large amounts of PAH, which degrade over long periods of time and pose a threat to ecosystem health [2; 3]. PAHs have been shown to have disruptive effects on the lymphatic system and hematopoiesis [11; 12], while chronic exposure to PAH causes mutagenicity due to their tendency to interact with DNA [13]. While pyrogenic PAHs are associated with greater environmental and health risks, they are primarily associated with chronic toxicity [11; 13]. In contrast, petrogenic PAH are more soluble and bioavailable to marine organisms, and as such considered to cause acute toxicity. Due to their adverse effects on human health and the health of marine organisms, the U.S. Environmental Protection Agency (USEPA) has included 16 PAHs in a list of priority pollutants to be monitored in the environment [14]. Various approaches have been developed to assess the environmental risk associated with PAH, of which the use of Sediment Quality Guidelines (SQGs) and bioassays have been the most widely used [15; 16]. Laboratory experiments have been conducted on a variety of marine animals, including microorganisms, algae, invertebrates, fish and marine mammals [11; 13; 17], and the results served as the basis for the carcinogen classification system for PAH and mixtures of PAH, and for the development of the Toxic Equivalent (TEQ) method for PAH-related environmental risk assessment [13; 17; 18; 19; 20]. This method assumes that all carcinogenic PAH are equivtoxic to benzo[_a_]pyrene and that the carcinogenic effect of a complex PAH mixture can be calculated as the sum of the effects of the individual PAH compounds [17; 20]. Although this approach may lead to overestimation or underestimation of the effects of PAH due to the inhibitory/synergetic properties of PAH compounds when present as a complex mixture, the TEQ method has been used in many studies to assess the PAH-related environmental risk [18; 19; 20]. Since the toxicity of a PAH mixture is determined by its composition and, consequently, by the nature of the source from which the PAH mixture originated, knowledge of the PAH sources at a particular site is important for the assessment of PAH-related environmental risk. Many approaches have been applied to constrain PAH sources, of which diagnostic ratios, statistical tools and modelling have been most commonly used. The use of statistical multivariate analyses, such as principal component analyses (PCA), cluster analyses and alternating least squares (ALS) are a cost-effective method for attributing PAH sources, although these methods require the identification of a larger number of PAH compounds at a larger number of locations [19; 21; 22]. To provide a reliable tool for addressing PAH pollution, the USEPA has developed a specific model based on the factor analysis method: the Positive Matrix Factorizations (PMF) [23]. The PMF results provide the number of factors (sources), the contributions of the factors to the concentration of each PAH compound, and a contribution of the factors to the total pollution PAH for each case [4; 19; 21; 24]. This study aims to obtain detailed information on the most important PAH sources and their contributions in the overall PAH pollution by application of PMF software.