An evaluation of the toxicity and bioaccumulation of thallium in the coastal marine environment using the macroalga, Ulva lactuca

► Thallium concentrations of 10 μg L−1 are toxic to Ulva lactuca. ► Accumulation factors are about 900 mL g−1 in both sea water and estuarine water. ► The majority of Tl accumulated is internalised by the macroalga. ► It is suggested that cell permeation of Tl+ proceeds through Na+, K+ and Cl− co-transporter sites.