Environ Monit Assess (2011) 182:317–324 DOI 10.1007/s10661-011-1878-0 Trace metals and radionuclides in macroalgae from Moroccan coastal waters Azzouz Benkdad · Abdelmourhit Laissaoui · Maria Victoria Tornero · Moncef Benmansour · ElMahjoub Chakir · Ignacio Moreno Garrido · Julian Blasco Moreno Received: 24 September 2010 / Accepted: 18 January 2011 / Published online: 5 February 2011 © Springer Science+Business Media B.V. 2011 Abstract Macroalgae species Codium sp, Bangia atropurpurea, Membranoptera alata, Plocamium cartilagineum, Dictyota dichotoma, Fucus spiralis and Stypocaulon scoparia were collected from seven stations along the north coast of Morocco. Samples were analysed to determine activities of naturally occurring radionuclides ( 210 Pb, U iso- topes and 40 K) and concentrations of metals (Zn, Fe, Co, Cu, Ni, Mn, Pb, Cd, As and Cr) using ra- diometric and ICP-OES techniques, respectively. Metal concentrations were within ranges reported in the scientific literature, and concentrations of bio-essential elements were in the order Mn>Fe> Zn>Cu in all samples. Brown algae had the highest concentrations of almost all metals, and concen- trations decreased in the order brown>red>green algae. With respect to radionuclides, the red alga A. Benkdad · A. Laissaoui (B ) · M. Benmansour Centre National de l’Energie, des Sciences et des Techniques Nucléaires, B.P. 1382 10001 Rabat, Morocco e-mail: laissaoui@cnesten.org.ma M. V. Tornero · I. M. Garrido · J. B. Moreno Instituto de Ciencias Marinas de Andalucía (CSIC), Campus Universitario Rio San Pedro, s/n. Puerto Real, Cadiz, 11510 Spain E. Chakir LHESIR, Départment de Physique, Faculté des Sciences, University Ibn Tofail, Kenitra, Morocco P. cartilagineum had the highest activities of 210 Pb, in most cases an order of magnitude higher than for the green alga Codium sp. 234 U and 238 U acti- vities in all algae samples were in the range 0.96– 7.61 and 1.16–6.14 Bq/kg dry weight, respectively. Our analyses of radionuclide activities and metal concentrations in marine macroalgae showed large differences among taxa. These results provide in- sights into which algal species should be used for biomonitoring programmes. Keywords Moroccan coast · Algae · Radionuclides · Metals · Biomonitoring Introduction Coastal zones are sinks for urban and industrial discharges, which introduce large amounts of pol- lutants into the marine environment, causing sig- nificant ecological degradation. During the last few decades, many studies have established the association of these pollutants with marine algae, with the objective of understanding how these or- ganisms reflect water quality (Bryan and Langston 1992; Storelli et al. 2001; Al-Masri et al. 2003; Connan et al. 2007). Macroalgae are used world- wide as quantitative bioindicators for dissolved metal and radionuclide contamination in marine systems because they are capable of accumulating these substances to concentrations thousands of