Water Research 39 (2005) 3945–3953 Assessment of heavy metal levels in Almendares River sediments—Havana City, Cuba Susana Olivares-Rieumont a , Daniel de la Rosa a , Lazaro Lima a , David W. Graham b,Ã , Katia D 0 Alessandro a , Jorge Borroto a , Francisco Martı´nez a , J. Sa´nchez c a Laboratorio de Ana´lisis Ambiental. Instituto Superior de Tecnologı´as y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Plaza, Ciudad Habana, Cuba b Department of Civil, Environmental, and Architectural Engineering, University of Kansas, Lawrence, KS 66045, USA c Instituto Cibernetica Matema´tica y Fı´sica, Calle 15, No 551 entre C y D, Plaza, Ciudad Habana, Cuba Received 8 December 2004; received in revised form 10 June 2005; accepted 7 July 2005 Available online 19 August 2005 Abstract The Almendares River watershed covers a large portion of Havana, Cuba and is centrally important to both recreational and other activities in the region. In order to assess current water quality conditions prior to planned remediation efforts, the spatial distribution of six heavy metals and other compounds were determined in river sediments at fifteen sampling stations in the watershed. Metal concentrations in sediments ranged from 86.1 to 708.8 for Zn, 39.3 to 189.0 for Pb, 71.6 to 420.8 for Cu, 84.4 to 209.7 Cr, 1.5 to 23.4 for Co, and 1.0 to 4.3 for Cd mg/g dry weight sediment. Calculated enrichment factors (EF; measured metal versus background mineral conditions) were almost always greater than 1.0, suggesting significant anthropogenic impact on metal levels in the river. The highest EF values were seen immediately below Cotorro (EF410 for Pb, Cu, and Cd), a suburban town that has an active secondary smelter, and below the largest municipal landfill in Havana (EF410 for Pb, Cu, Cd, and Zn). Further, three sampling stations had multiple metals at concentrations higher than probable effects concentrations (PEC), implying possible local ecotoxicological impacts. Finally, sequential extractions of the sediments indicated that heavy metals were largely associated with the organic fraction, and it was estimated that up to 62% of metals in the sediments would be susceptible to release back into the water column if hydraulic or other changes occurred in the river. These data are being used to prioritize decisions related to the remediation of the river system. r 2005 Elsevier Ltd. All rights reserved. Keywords: Cuba; Heavy metals; Sediments; Almendares River; Enrichment factors; Metal fractionation 1. Introduction The Almendares River is one of the most important watersheds in Cuba. Over 52.8% of the watershed (40,202 km 2 ) is within the City of Havana and 47% of the city’s drinking water comes from groundwater below the basin. Further, the Ejercito Rebelde reservoir, ARTICLE IN PRESS www.elsevier.com/locate/watres 0043-1354/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.watres.2005.07.011 Ã Corresponding author. Tel.: +1 785 864 2945; fax: +1 785 864 5379. E-mail address: dwgraham@ku.edu (D.W. Graham).