The Science of the Total Enuironment, 72 (1988) 123130 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands 123 zyxwvutsr ASSESSMENT OF MERCURY DISTRIB’UTION AND PARTITIONING IN RECENT SEDIMENTS OF THE WESTERN MEDITERRANEAN BASIN R. BARGAGLI zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Department of Environmental Biology, University of Siena, Via delle Cerchia 3, 53100 Siena (It a ly) R. FERRARA and B.E. MASERTI Institute of Biophysics, National Research Council, Via San Lorenzo 26, 56100 Pisa (Italy) (Received November 5th, 1987; accepted December 14th, 1987) ABSTRACT Surface sediments collected throughout the Tyrrhenian Sea and the Western Mediterranean basin were analyzed for granulometric and geochemical characteristics and for total mercury content. Sediments of the Southern Tyrrhenian continental shelf and those collected from the Tyrrhenian slope and the Western Mediterranean basin have a total mercury content which is in the same range as that for other marine areas assumed to be background. Based on chemical leaching studies, most of the mercury appears to be fixed in a refractory phase and -20% is associated with organic materials. Biogenic carbonates, a large constituent of Mediterranean sediments, contain a very low percentage of the total mercury. On the basis of its content and its geochemistry, mercury in Mediterranean sediments, outside the continental shelf, seems to have little relevance to the high concentrations of the metal in tuna and other pelagic fish. INTRODUCTION The Mediterranean is a semi-enclosed sea with topographic and oceano- graphic characteristics which may give rise to magnification of the effects of contamination. Research carried out since the 1970s has shown that, of the heavy metals, mercury is of the greatest regional concern (UNEP, 1983). Samples of water, sediments and marine organisms collected in several coastal areas, especially those affected by widespread cinnabar deposits and by the outflows of chlor-alkali plants, exhibit high levels of the metal. Moreover, several species of open-sea pelagic fish show mercury concentrations about twice that usually found in specimens of the same species and size collected in the Atlantic Ocean (Cumont et al., 1972; Bernhard and Renzoni, 1977). It has been suggested that the higher level of mercury is due to its natural anomalous occurrence in the Mediterranean basin. This hypothesis needs to be more comprehensively assessed before it can be zyxwvutsrqpo 0048s9697/88/$03.50 0 1988 Elsevier Science Publishers B.V.