Pergamon PII: S0025-326X(97)00063-5 Marine Pollution Bulletin, Vol. 34, No. 11, pp. 857-867, 1997 © 1997 Elsevier Science Ltd All rights reserved. Printed in Great Britain 0025-326X/97 $17.00+0.00 Polyaromatic Hydrocarbon (PAH) Distributions in the Seine River and its Estuary M. B. FERNANDES*, M.-A. SICRE*:~, A. BOIREAU* and J. TRONCZYNSKI'f *Laboratoire de Physique et Chimie Marines, Universit~ Pierre et Marie Curie, INSU/CNRS URA 353, 4 Place Jussieu, 75252 Paris Cedex 05, France tLaboratoire de Chimie des Contaminants et Mod~lisation, IFREMER, Centre de Nantes, BP 1049, 44037 Nantes Cedex, France Dissolved and particulate PAHs were quantified through- out the Seine River and its estuary. Samples were collected in October 1993, covering a salinity gradient of 0.2%0 to 34.8%0. Two mooring stations were occupied at the river mouth to ascertain the influence of tidal cycles on the dispersal of riverborne PAils. Total particulate PAH concentrations ranged from 2 to 687 ng 1-1 (or I to 14pgg-1). Concentrations were correlated to the suspended matter load and distributions could be explained by estuarine mixing. PAII levels decreased from ebb to flood tides. PAH concentrations in the dissolved phase (4 to 36 ng 1-1) were, in general, an order of magnitude lower than in the particulate phase. The partition coefficient of individual PAHs (Koc) were comparable to those previously reported for the RhSne River suspensions. © 1997 Elsevier Science Ltd A large variety of organic substances, including anthropogenic contaminants, are transported into coastal marine environments via riverine discharge. To evaluate pollutant impact it is important to estimate and understand river transport/dispersal of anthropogenic compounds and their effects on water quality and biota. The distribution and fate of contaminants in water, sediment and biota in estuaries are influenced by numerous factors such as salinity, pH, suspended particulate matter (SM), tidal currents and seasonal/ meteorological variability (Olsen et al., 1982; Jaffa, 1991). Polycyclic aromatic hydrocarbons (PAHs) are wide- spread pollutants in aquatic systems and occur primarily as a result of anthropogenic inputs. Their ~/Corresponding author. Present address: Centre des Faibles Radioactivitb, s, Laboratoire Mixte CNRS-CEA, Domaine du CNRS, Ave. de la Terrasse, 91191 Gif-sur-Yvette Cedex, France. main sources include both high and low temperature combustion (e.g. industrial pyrolysis, ship and auto- mobile exhausts, forest fires, urban coal and oil heating) (Grimmer et al., 1983a) and the direct release of oil and its products (Neff, 1979; Grimmer et al., 1981a,b, 1983b). High molecular weight PAHs are generated mainly by high temperature combustion whereas lower molecular weight PAHs, e.g. phenanthrene and its alkylated homologues, may derive from fossil fuel combustion, but are also major constituents of petroleum. PAHs are present as mixtures of alkylated and parent species. The ratio of methyl-phenanthrenes/ phenanthrene (MP/P) is commonly used to ascertain emission sources. Combustion-generated PAHs are known to be deficient in substituted homologues (MP/ P< 1), even though combustion temperature affects their relative abundance (Youngblood and Blumer, 1975). In contrast, alkylated PAHs dominate the assemblage of unburned fossil organic material (MP/ P > 1) (Youngblood and Blumer, 1975). PAHs are considered to be hazardous to the environment. They include highly mutagenic (Guerin et al., 1978) and carcinogenic four- to seven-ring compounds (Medical Research Council, 1968). Two- or three-ring PAHs are less mutagenic (Berichte 1/79 des Umweltbundesamtes, 1979) but can be highly toxic, e.g. three-ring phenanthrene and its methyl-substituted homologues are toxic to algal growth (Pulich et al., 1974). Chronic introduction of PAHs in estuaries can affect freshwater quality and induce accumulation in the pelagic and benthic food chains at various trophic levels leading to long term changes in the biota. Some PAHs are readily degradable. Their occurrence on airborne particles, riverine suspensions or sediments suggests that part of them survive degradation processes. It has been hypothesized that PAHs adsorbed onto particles are more readily accessible to degradation whereas those tightly bound or occluded into particles 857