title: Bioconcentration of inorganic and organic thallium by freshwater phytoplankton.
abstract: Uptake of inorganic Tl(I) and dimethylthallium, (CH3)2Tl+, by Chlorella spp. (Chlorophyta) and the diatom Stephanodiscus hantzschii (Heterokontophyta) were measured using radio-tracer techniques in water from Lakes Erie and Superior (North America). Uptake of both Tl(I) and dimethylthallium was bioactive. Uptake of [204Tl]-Tl(I) was greater in Lake Superior water than in Lake Erie water due to the greater K content in Lake Erie that inhibits Tl(I) uptake by phytoplankton but not that of [204Tl]-dimethylthallium. Volume-based bioconcentration factors for Tl(I) after 72 h of exposure were 5 x 10(4) and 1.1 x 10(4) for Chlorella sp. and S. hantzschii; for dimethylthallium they were 7.8 x 10(2) and 8.3 x 10(3). Both Tl(I) and Tl(III) were concentrated similarly by Chlorella spp. These results suggest that chlorophytes, but not diatoms, accumulate Tl(I) to a greater extent than dimethylthallium. Greater bioaccumulation factors of inorganic Tl are possible in waters containing low amounts of K+; water quality guidelines seeking to protect biota from deleterious effects of Tl should consider the role of K.
authors.affiliation: Department of Chemistry, Biology and Chemical Engineering, Ryerson Polytechnic University, 350 Victoria Street, Toronto, Ontario, Canada, M5B 2K3. mtwiss@clarkson.edu
authors.forename: Michael R
authors.initials: MR
authors.lastname: Twiss
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Twining
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Fisher
mesh_terms: D002708:Chlorella / Q000737:chemistry*; D017377:Diatoms / Q000737:chemistry*; D004784:Environmental Monitoring; D006114:Great Lakes Region; D010839:Phytoplankton; D013793:Thallium / Q000493:pharmacokinetics*; D014873:Water Pollutants / Q000493:pharmacokinetics*
chemical_list: D014873:Water Pollutants; D013793:Thallium