title: An evaluation of the toxicity and bioaccumulation of thallium in the coastal marine environment using the macroalga, Ulva lactuca.
abstract: Thallium(I) has been added to cultures of the marine macroalga, Ulva lactuca, for a period of 48 h and the accumulation of the metal and its effects on the photochemical efficiency of photosystem II (PS II) measured. Thallium elicited a measurable toxic response above concentrations of 10 μg L⁻¹ in both coastal seawater (salinity 33) and estuarine water (salinity 20). The accumulation of Tl was defined by a linear relationship with aqueous Tl and accumulation factors of about 900 mL g⁻¹ in both media. Thallium accumulated by U. lactuca that was resistant to an EDTA extraction and, by operational definition, internalised, exceeded 90% in both cases. Accumulation and toxicity of Tl in the presence of a ∼10⁵-fold excess of its biogeochemical analogue, potassium, suggests that Tl has a high intrinsic phytotoxicity and that its mode of action involves permeation of the cell membrane as Tl⁺ through NaCl-KCl co-transporter sites rather than (or in addition to) transport through K⁺ ion channels.
authors.affiliation: School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK. aturner@plymouth.ac.uk
authors.forename: Andrew
authors.initials: A
authors.lastname: Turner
authors.forename: Oliver
authors.initials: O
authors.lastname: Furniss
mesh_terms: D004784:Environmental Monitoring; D054712:Salinity; D012623:Seawater / Q000737:chemistry; D013793:Thallium / Q000378:metabolism / Q000633:toxicity*; D018675:Toxicity Tests / Q000379:methods*; D044445:Ulva / Q000187:drug effects* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D013793:Thallium