Polycyclic aromatic hydrocarbons in natural waters: sources, occurrence and analysis E. Manoli*, C. Samara Aristotle University of Thessaloniki, Chemistry Department, Environmental Pollution Control Lab., GR-54006 Thessaloniki, Greece The introduction of polycyclic aromatic hydrocarbons (PAHs) into natural waters is considered in terms of both point and non- point source discharges to surface, ground and drinking water. The occurrence of PAHs has been evaluated with regard to their con- centrations in some aqueous samples and fre- quency of occurrence. In addition, an over- view of the capabilities of the currently available analytical techniques is given along with requirements for achieving reliable analysis of PAHs in various environmental water samples. z1999 Elsevier Science B.V. All rights reserved. Keywords: Polycyclic aromatic hydrocarbon; Water analysis 1. Introduction Water pollution by organic compounds, many of which are known to be toxic or carcinogenic, has caused considerable and worldwide concern. Coastal and inland waters usually act as receptors for sewage ef£uents, industrial ef£uents and urban and rural run- off. As streams and rivers, lakes and ponds are fre- quently used for potable water supply, contamination of watercourses, where water re-use is practised, is particularly undesirable. Polycyclic aromatic hydrocarbons (PAHs ) are a group of organic compounds which have received considerable attention because of the documented car- cinogenicity in experimental animals of several of its members. PAHs are fused compounds built on benzene rings. When a pair of carbon atoms is shared, then the two sharing aromatic rings are considered fused. The resulting structure is a molecule where all carbon and hydrogen atoms lie in one plane [ 1 ]. The environ- mentally signi¢cant PAHs range between naphthalene (C 10 H 8 ) and coronene (C 24 H 12 ). In this range, there are a large number of PAHs differing in the number and position of aromatic rings, with varying number, position and eventual chemistry of substituents on the basic ring system. Physical and chemical properties of PAHs vary with molecular weight [ 1]. Due to their environmental concern, PAHs are included in the US EPA and in the European Union priority lists of pol- lutants. US EPA has identi¢ed 16 unsubstituted PAHs as priority pollutants, some of which are considered to be possible or probable human carcinogens, and hence their distribution in the environment and potential risks to human health have been the focus of much attention. The 16 US EPA PAHs along with their structures, physicochemical constants and estimated carcinogenic potency are given in Table 1. The Euro- pean list contains six target PAHs ( Fl, B[ b ]Fl, B[ k ]Fl, B[ K ]Py, B[ ghi ]Pe and I[ 1,2,3-cd ]Py ). PAHs are introduced into the environment mainly via natural and anthropogenic combustion processes. As a consequence, their loadings to aquatic and terres- trial systems all have a component which is atmo- spheric in origin. Volcanic eruptions and forest and prairie ¢res are among the major natural sources of PAHs in the atmosphere. Important anthropogenic sources include combustion of fossil fuels, waste incineration, coke and asphalt production, oil re¢ning, aluminum production and many other industrial activ- ities [ 2 ]. Despite their large source strength in urban / industrial sites, PAHs occur at relatively high concen- trations in rural and remote areas due to their ability to be transported over long distances as gases or aerosols, and their apparent resistance to degradation on atmo- spheric particulates. Thus, PAH emissions into urban / industrial atmospheres may signi¢cantly affect coastal and inland surface waters. After entering the aquatic environment, the behav- ior and fate of PAHs depend on their physicochemical 0165-9936/99/$ ^ see front matter ß 1999 Elsevier Science B.V. All rights reserved. PII:S0165-9936(99)00111-9 *Corresponding author. trends in analytical chemistry, vol. 18, no. 6, 1999 417