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- Title
Influence of zwitterionic pH buffers on the bioavailability and toxicity of copper to the alga Amphidinium carterae
- Authors
Sansonetty, Filipe; Lage, Olga M.; Vasconcelos, M. Teresa S. D.; Almeida, Cristina M. R.
- Abstract
The culture and testing of algae frequently requires stabilization of pH levels to maintain the availability of trace metals. In this work we evaluated the influence of 25 x 10-3 M N-[2-hydroxyethyl]piperazine-N'-[2-hydroxypropanes ulfonic acid] (HEPPSO and piperazine-NN'-bis[2-hydroxypropanesulfonic acid] (POPSO) pH buffers, at pH8.0, on the biological response of Amphidinium carterae Hulburt. Growth rate, copper uptake, mean cell size, mean cell complexity, and fluorescein labeling of algae cultures were studied in enriched solutions of artificial seawater (ESAWs) containing a range of total copper(II) concentrations between 23 X 10-9 M (level before copper addition) and 15 x 10-6 M. The ESAW (without a pH buffer, initial pH = 8.0) was used as the control medium. Initial free copper (Cufree) was between 53 X 10-15 and 72 X 10-10 M, which represents ranges of concentrations typical of unimpacted and polluted surface seawater. These ranges were achieved using ehtylenediaminetetraacetic acid (EDTA) alone and in combination with the two buffers. Biological data endpoints were interpreted based on the cellular copper (Cu cellular' in fmol/cell) and on the estimated initial inorganic copper (Cuinorg = Cufree plus that bound with inorganic ligands) in the medium. At innocuous Cu inorg' up to 10 X 10-9 M (Cufree =/<4 X 10-11 M), the Cucellular was independent of the presence of the buffer and very little dependent of Cu inorg. For Cuinorg up to 0.40 x 10-9 M, the Cucellular was approximately constant (0.1-0.2 fmol/ cell) and when Cuinorg ranged between 1.1 X 10-9 M and 10 X 10-9 M the Cucellular was three times higher but also constant. The POPSO enhanced copper uptake and toxicity. The HEPPSO reduced uptake and toxicity of copper b
- Subjects
METABOLISM; ALGAE; TOXICITY testing; BIOAVAILABILITY; COPPER
- Publication
Environmental Toxicology & Chemistry, 2000, Vol 19, Issue 10, p2542
- ISSN
0730-7268
- Publication type
Article