Volume26/Number l 1/November 1993 Marine Pollution Bulletin, Volume 26, No. 11, pp. 613-619, 1993~ Printed in Great Britain. 0025-326X/93 $6.00+0.00 © 1993 Pergamon Press Ltd Herbicide Contamination of Mediterranean Estuarine Waters: Results from a MED POL Pilot Survey J. W. READMAN*, T. A. ALBANISt, D. BARCELO:~, S. GALASSI§, J. TRONCZYNSKI¶ and G. E GABRIELIDES II *International Atomic Energy Agency--Marine Environment Laboratory, P.O. Box No. 800, MC-98012, Principality of Monaco + Department of Chemistry, University ofloannina, 45332 Ioannina, Greece "Environmental Chemistry Department, CID-CSIC, c/ Jordi Girona, 18-26, 08034 Barcelona, Spain §Istituto di Ricerca sulle Acque, Consiglio Nazionale delle Ricerche, 20047 Brugherio, Milano, Italy ¶ Institut Francais de Recherche pour l'Exploitation de la Mer, P.O. Box No. 1049, 44037 Nantes, France II FAO Project Office, Mediterranean Action Plan, Leoforos Vassileos Konstantinou 48, P.O. Box 18019, GR-11610, Athens, Greece The reported data offers the first extensive evidence that significant concentrations of some herbicides persist in marine systems. In the areas studied (the Ebro delta on the Eastern Coast of Spain, the Rhone delta in the South of France, the River Po, Italy/the Northern Adriatic Sea, the Thermaikos and Amvra- kikos Gulfs in Greece and the Nile delta in Egypt) the most commonly encountered herbicides were atrazine, simazine, alachlor, metolachlor and molinate. In general, aqueous concentrations encountered in the riverine inputs were comparable to (or below) those reported for rivers in other regions of the World. Concentrations generally declined from freshwater locations through estuaries to marine waters. The distributions of some herbicides (e.g. the triazines) in sediments endorsed the environmental persistence of these compounds. In contrast to the other areas studied, no herbicides were detected in samples from a preliminary survey of the Nile delta. Herbicide usage has increased dramatically during the last two decades coinciding with changes in farming practices and increasingly intensive agriculture. The annual application of herbicides for example in Italy, increased from 9600 t of active ingredients in 1971 to 33 000 t in 1987 (Fielding etal., 1992). The 36 000 t of herbicides used in France during 1988 represented 36% of the total pesticides used in the country (Fielding et al., 1992) endorsing the importance of this class of agrochemicals. Other Mediterranean countries use lesser amounts of herbicides, for example Spain and Greece both used 3000 t (active ingredients) during 1989 (Fielding et al., 1992). No data are currently available for countries bordering the southern coast of the Mediterranean. Herbicides have been detected in many rivers around the world including those flowing into the Mediter- ranean Sea [the River Po (Galassi & Leoni, 1987; Baraldi et al., 1991; Galassi et al., 1992), River Rhone (Tronczynski et al., 1993), River Llobregat, Spain (Rivera, 1987)]. In contrast, only very limited data are available for estuarine locations (Baldi et al., 1991) and no data are available for coastal and seawater. In 1990 the Co-ordinating Unit for the Mediter- ranean Action Plan in cooperation with FAO and IAEA organized a pilot survey in selected areas to generate data on existing levels of herbicides in Mediterranean locations. Materials and Methods Sampling Samples were collected from the areas shown in Fig. 1. The Ebro delta, Spain. The Ebro delta is an alluvial plain of about 35 km 2. Lagoons and marshes cover 20% of the area, the remainder is principally agri- cultural (mainly rice cultivation). Water samples were collected each month from April to June 1991 from the Carret6 drainage canal, the Ebro fiver and the Encanizada and Tancada lagoons. In addition, soil/ sediments were taken each month (December 1990 to June 1991) from two stations in the delta. The Rhone delta, France. The Rhone drains 15% of the cultivated surfaces in France. Within its highly populated and industrialized basin, vinyards, horti- culture and corn production dominate agriculture in the upper regions whereas the lower reaches (including its 750 km 2 delta) are devoted principally to rice. Water samples were collected each month (April to November 1991) at fresh water riverine sites and at a low salinity estuarine station. In addition, in November 1990 and 613