Journal of Photochemistry and Photobiology A: Chemistry 168 (2004) 109–115 Photodegradation and biodegradation study of benzo(a)pyrene in different liquid media Agata Kot-Wasik, Dagmara D˛ abrowska, Jacek Namie´ snik ∗ Department of Analytical Chemistry, Gdañsk University of Technology, 11/12 Narutowicz Str., 80-952 Gdañsk, Poland Received 29 April 2004; accepted 25 May 2004 Available online 3 July 2004 Abstract The rate of degradation of benzo(a)pyrene in different media has been investigated. Different parameters such as light intensity respon- sible for photodegradation, temperature, exposure time and the presence of naturally occurring bacterial flora blamed for biodegradation processes, influencing stability of benzo(a)pyrene in various solvents and water have been monitored. Degradation in organic solvents decreased in the following order: dichloromethane > acetonitrile > hexane ≥ cyclohexane > methanol. In the case of natural waters, the degradation rate course in the following order: pond water > river water > seawater. Benzo(a)pyrene-4,5-dihydrodiol and one of isomers of hydroxy-BaP-dione as products of photodegradation have been detected. BaP-dione-like compound formed during biodegradation was identified. © 2004 Elsevier B.V. All rights reserved. Keywords: Benzo(a)pyrene; Photodegradation; Biodegradation; Degradation products; LC-DAD-MS analysis 1. Introduction The term polycyclic aromatic hydrocarbons (PAH) gen- erally refers to hydrocarbons containing two or more fused benzene rings in linear, angular or clustered arrangements [1]. Generally, PAH solubility and volatility decrease and hy- drophobicity increases with an increase in number of fused benzene rings [2]. Most polycyclic aromatic hydrocarbons, especially those with four or more rings and their metabolites, have a variety of mutagenic and carcinogenic effects on microorganisms, plants and animals, and are classified as compounds with significant human health risk [3]. One such high molecular weight PAH is benzo[a]pyrene (BaP), a five-ring com- pound, which has been classified by the US Environmental Protection Agency (USEPA) as a priority pollutant: due to its known or suspected carcinogenicity, teratogenicity or acute toxicity. BaP has a very low water solubility (3.8 gl -1 ) and vapour pressure (5.0 × 10 -7 mm Hg at 20 ◦ C), and a high octanol/water partitioning coefficient (6.04), which suggests its preference to non-aqueous phases [4]. BaP is one of the most potent carcinogenic PAHs, and as such, is the most ∗ Corresponding author. Tel.: +48-58-347-2310; fax: +48-58-347-2694. E-mail address: chemanal@pg.gda.pl (J. Namie´ snik). studied compound of the PAH class. Several reviews have been written on the risk assessment of BaP [5], as well as the metabolism and activation of BaP in mammalian systems [6]. Numerous studies have indicated that one, two, and three-ring compounds are acutely toxic [1], while higher molecular weight PAHs, including BaP are considered to be genotoxic [7–11]. The dominant processes for the successful removal and elimination of PAHs from the environment, except volatilisation, photo-oxidation, chemical oxidation, bio- accumulation and adsorption on sediment particles, are mi- crobiological transformation and degradation [2]. Although microbial degradation is considered the main elimination process in the environment [12], photochemical reactions are also responsible for removing PAHs from water and air [13,14]. Photolysis is an important transformation path- way for most PAHs in the environment. The photolysis rate of selected PAHs in natural water body is relatively fast [15–18]. In organic solvents, the photolysis rates of PAHs are also found to be rapid [19]. Oxidation prod- ucts of PAHs, produced by photo-oxidation and microbial degradation, are more water soluble than parent PAHs [14]. PAHs and its metabolites in remote continental environ- ments have essentially been studied in sediments [20–24]; 1010-6030/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jphotochem.2004.05.023