Bull. Environ. Contam. Toxicol. (1987) 39:1076-1083 9 1987 Springer-Verlag New York Inc. ~= Environmental Contamination ~and Toxicology Organochlorine and Metal Pollution in Aquatic Organisms Sampled in the Dofiana National Park During the Period 1983-1986 M- ~. C. Rico, L. M. Hernandez, M~-. J. Gonzalez, M. A. FernAndez, and M. C. Montero Institute of Organic Chemistry (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain The study area, Do~ana National Park, is located in the South South-West of Spain, and this is one of most important reservation of Europe. Samples of aquatic organism were obtained from the principal waterway of Do5ana National Park to determine the degree of organochlorine and metal contamination of this environment. The sampling was carried out during the period 1983-1986 in order to collect six aquatic species in four sites along the "Brazo de la Torre" (Figure i). An agricultural area in the North-West side of the Park and a working mine at about 40 km from its northern boundary were considered as the likely main polluting souirces of organochlorine pesticides, PCBs, and heavy metals respectively. MATERIALS AND METHODS The aquatic organism species chosen for analysis were: American crayfish (Procambarus clarckii), carp (Cyprinus carpio), barbel (Barbus barbus), grey mullet (Mugil capito), eel (Anguilla anguilla), and frog (Rana perezi). Specimens were immediately weighed, wrapped in aluminium foil and frozen at -18~ The composite aquatic organism samples, each of different species consisted of 1-21 adults. Extraction, purification and analysis of organochlorine compounds presents in the muscle tissue samples were carried out according to a method previously described (Cromartie et al. 1975; Kaiser et al. 1980). The organochlorine contaminant analysis consisted of hexane extraction of a homogenized fish-sodium sulfate mixture on a Soxhlet extractor, clean-up of the extracts on a partially deactivated Florisil column; the pesticides and PCBs were separated into four fractions. Determination was made by gas chromatography using an electron affinity detector. Send reprint requests to M a. C. Rico at the above address. 1076