Kinetics of Mercury Accumulation and Its Effects on Ulva lactuca Growth Rate at Two Salinities and Exposure Conditions Sónia Costa & Daniel Crespo & Bruno M. G. Henriques & Eduarda Pereira & Armando C. Duarte & Miguel A. Pardal Received: 1 June 2010 / Accepted: 18 August 2010 / Published online: 4 September 2010 # Springer Science+Business Media B.V. 2010 Abstract The research on metals effect on macro- algae has been focused on Cd, Cu, Zn and Pb, and no study dealt with the effects of mercury on macroalgae growth rate. Also, the kinetic of accumulation is not well known. The main aim of this work was to assess the mercury accumulation kinetics of Ulva lactuca and its effects on growth rate. Three concentrations were tested: 5, 50 and 500 μgL -1 , under static and renewal conditions and at two salinities (15 and 35), during 72 h. The mercury accumulation kinetic patterns were different according to the exposure conditions and metal concentration, but were always a very fast process (hours). Three patterns were established based on the models substrate inhibition, linear regression and Michaelis–Menten equation. Statistical differences in the mercury accumulated were recorded depending on the salinity values and exposure conditions, being higher at salinity 15 and at renewal tests, corresponding to the lower relative growth rates. The lowest mercury concentration did not have an effect on relative growth rate, while the others caused an accentuated inhibition at 24 h. The highest concentration was toxic to algae causing its death before 48 h. Under controlled conditions, the U. lactuca’ s high and fast ability for mercury accumula- tion could be useful for phytoremediation and for industrial wastewaters treatment. Keywords Mercury . Kinetic of accumulation . Relative growth rate . Ulva lactuca 1 Introduction At the moment, several areas of knowledge have been observing the increasing number of pollutants in the world with great interest. Discharge of industrial wastewaters and untreated sewage causes a serious risk to the coastal and estuarine areas and conse- quently to human populations. Among the contami- nants, metals are of utmost concern due to the potential impact of contaminated foodstuffs consump- tion on humans (Commission Regulation EC 466/ 2001) and consequent health hazard. Despite their natural sources, human activity is largely responsible for their abnormal release and accumulation in the environment. Several industries use metals due to their technological importance and applications. In order to control metal levels in the environment, the treatment of the contaminated effluents is highly important since they can accumulate on organisms Water Air Soil Pollut (2011) 217:689–699 DOI 10.1007/s11270-010-0620-9 S. Costa (*) : D. Crespo : M. A. Pardal CEF–Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Apartado 3046, 3001-401 Coimbra, Portugal e-mail: soniacosta@ci.uc.pt B. M. G. Henriques : E. Pereira : A. C. Duarte CESAM–Centre for Environmental and Marine Studies, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal