Metal speciation and environmental impact on sandy beaches due to El Salvador copper mine, Chile Marco Ramirez a , Serena Massolo b, * , Roberto Frache b , Juan A. Correa a a Facultad de Ciencias Biolo ´ gicas, Departamento de Ecologı ´a y Center for Advanced Studies in Ecology and Biodiversity, P. Universidad Cato ´ lica de Chile, Casilla 144-D, Santiago, Chile b Dipartimento di Chimica e Chimica Industriale, Sezione di Chimica Analitica ed Ambientale, Universita ` di Genova, Via Dodecaneso 31, 16146-Genova, Italy Abstract Several coastal rocky shores in northern Chile have been affected by the discharges of copper mine tailings. The present study aims to analyze the chemical speciation of heavy metals in relation to the diversity of sessile species in the rocky intertidal benthic community on the northern Chilean coast, which is influenced by the presence of copper mine tailings. In particular, the chemical forms of Cd, Cu, Fe, Mn, Ni, Pb and Zn in beach sediment samples collected in the area influenced by El Salvador mine tailings were studied using a sequential chemical extraction method. In general, all the elements present a maximum concentration in the area near the actual discharge point (Caleta Palito). With regard to Cu and Mn, the concentrations range between 7.2–985 and 746–22,739 lg/g respectively, being lower than background levels only in the control site of Caleta Zenteno. Moreover, the correlation coefficients highlight that Fe, Mn and Ni correlate sig- nificantly and positively in the studied area, showing a possible common, natural origin, whilst Cu shows a negative correlation with Fe, Mn and Ni. It could be possible that Cu has an anthropogenic origin, coming from mining activity in the area. Cd, Fe, Mn, Ni, Pb and Zn are mostly associated with the residual phase, whilst Cu presents a different speciation pattern, as resulted from selective extractions. In fact, Cu is highly associated with organic and exchangeable phases in contaminated localities, whilst it is mainly bound to the residual phase in control sites. Moreover, our results, compared to local biological diversity, showed that those sites characterized by the highest metal concentrations in bioavailable phase had the lowest biodiversity. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Heavy metals; Chemical speciation; Sediments; Chile; Mine tailings; Diversity 1. Introduction 1.1. Mining history Copper mining in Chile is based in open or under- ground mines spread along the Andes Mountains. Por- phyry deposits, which are the worldÕs principal source of copper and molybdenum, characterize this area. Ore minerals (mainly Cu and Mo sulphides) are sepa- rated from gangue minerals and pyrite by flotation (Dold and Fontbote `, 2001). Generally, most mining operations, such as processing, smelting and tailing dis- posal, are carried out near the exploitation areas. How- ever, the El Salvador mine, a porphyry copper deposit located in the Atacama Desert, is an exception because the tailings were dumped without treatment directly into Chan ˜aral Bay via the river Salado (Castilla, 1983; Paskoff and Petiot, 1990). Approximately 150 million tonnes (mining between 1938 and 1975) of disposed materials accumulated in the area have caused a beach to widen (Castilla and Correa, 1997). In 1976 the 0025-326X/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.marpolbul.2004.08.010 * Corresponding author. Tel.: +39 010 3536178; fax: +39 010 3536190. E-mail address: massolo@chimica.unige.it (S. Massolo). www.elsevier.com/locate/marpolbul Marine Pollution Bulletin 50 (2005) 62–72