Polycyclic Aromatic hydrocarbon (PAH) accumulation in different common sole tissues by Quechers method.

The evaluation of polycyclic aromatic hydrocarbon (PAH) level in environmental matrices and the edible part of aquatic organisms is an important issue (1). PAH bioaccumulation is a complex phenomenon governed by many factors including their physicochemical characteristics, environmental conditions and the characteristics of the species itself (2; 3). This study extends our knowledge of the bioaccumulation of PAHs in marine organisms and investigates its possible determinants. The aims were to analyze and evaluate the residue levels and distribution of PAH in the tissue of common sole individuals (S. solea) collected from three areas of the northern Adriatic Sea and to examine the main factors involved in PAH bioaccumulation, namely the lipid content of tissue, biometric characteristics of fish, environmental features and physicochemical properties (e.g. Kow) of PAHs to establish which factors exert a major influence on PAH bioaccumulation in fish tissue. The Quechers (QUick Easy CHeap Effective Rugged and Safe) method was applied and developed for the extraction and purification steps of PAHs from fish tissue(4). At the same time, the ultrasonic bath and liquid-liquid separation were performed for the PAH extraction from marine sediments (5). PAH identification and quantification in fish tissue and surface sediment samples were performed by the same methods using an HPLC system (Ultimate 3000, Thermo Scientific) equipped with a fluorescence detector (RF-2000, Thermo Scientific). The whole analytical procedure was validated by analyzing the reference materials (IAEA code 106, code 408 and code 383) and the recovery fell with the confidence interval of 95%. Statistical analysis of method performance data, in particularly the evaluation of the linearity range and LOD, LOQ quantification, was performed using Statgraphics Plus software, version 5.1 (6). A p value lower than 0.05 was considered to indicate significance, while a p value higher than 0.05 was considered to indicate not significance (n.s.). The content of the total PAHs was measured in muscle, liver and gill tissue of S. solea individuals caught in the Venice Lagoon, off Chioggia and the Po Delta (Table 1). The average total PAH concentration was 6.7 ng g-1 d.w. (range: 1.3-16.3 ng g-1 d.w.), 13.1 ng g-1 d.w. (range: 2.1-31.8 ng g-1 d.w.) and 32.0 ng g-1 d.w. (range: 2.0-112.6 ng g-1 d.w.), in muscle, liver and gill tissue, respectively. Therefore, a significantly higher PAH accumulation in gills, followed by liver and muscle was found (p < 0.05). The sediment concentrations of total PAHs were also measured to understand how the sampling areas affected their bioaccumulation in fish tissues. PAH concentrations were highest in the Venice Lagoon and the Po Delta (980±2 ng g-1 d.w and 625±62 ng g-1 d.w, respectively) and lowest in the off Chioggia (58±2 ng g-1 d.w). The impact of PAHs was higher on biota and sediment form the coastal areas (the Venice Lagoon and the Po Delta), which are characterized by dense human settlements and activities as well as direct and indirect discharges. Correlations were observed between several factors, especially the lipid content of tissue, the octanol-water partition coefficient (Kow) of PAHs and the body size of fish, in relation to PAH bioaccumulation in fish tissue (Table 2). Our finding suggests that a quota of PAHs accumulation in gill and liver tissues depend on PAH physico chemical features, such as Kow. Although, a positive relationship between lipid content and total PAH levels was found in the three tissues, the degree of significance was not significant. Moreover, PAH tissue concentrations decreases with the increase in body size, in line with the data reported by other authors (7; 8) may be due to a relatively low resistance of PAHs to biotransformation and a high depuration rates by adult organisms. The main factors determining PAH bioaccumulation in S. solea tissue in the Adriatic Sea were closely related to their environment.