Uptake of Neutral Metal Complexes by a Green Alga: Influence of pH and Humic Substances

Amiel Boullemant; Bernard Vigneault; Claude Fortin; Peter G. C. Campbell

doi:10.1071/CH04093

RESEARCH ARTICLE

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Uptake of Neutral Metal Complexes by a Green Alga: Influence of pH and Humic Substances

Amiel Boullemant ^A , Bernard Vigneault ^B , Claude Fortin ^A and Peter G. C. Campbell ^A ^C

+ Author Affiliations

- Author Affiliations

^A Université du Québec, Quebec City, Québec G1K 9A9, Canada.

^B CANMET Mining and Mineral Sciences Laboratory, Natural Resources Canada, Ottawa, Ontario K1A 0G1, Canada.

^C Author to whom correspondence should be addressed (e-mail: peter_campbell@inrs-ete.uquebec.ca).

Australian Journal of Chemistry 57(10) 931-936 https://doi.org/10.1071/CH04093
Submitted: 23 April 2004 Accepted: 26 July 2004 Published: 1 October 2004

Abstract

We have examined the influence of pH and a natural humic acid on the short-term uptake (<40 min) of a neutral, lipophilic metal complex by a unicellular freshwater alga, Pseudokirchneriella subcapitata. Cadmium diethyldithiocarbamate ([Cd(DDC)₂]⁰) was used as a model lipophilic metal complex and Suwannee River Humic Acid (SRHA) was chosen as a representative aquatic humic acid (6.5 mg C L⁻¹). Under the experimental conditions virtually all the Cd was expected to be present as the lipophilic complex ([Cd]_T = 0.38 nM; [DDC] 1 μM; [Cd²⁺] <10⁻¹⁵ M; pH 7.0, 6.0, or 5.5). Uptake of [Cd(DDC)₂]⁰ proved to be sensitive to pH changes. It was lower at pH 6.0 and 5.5 than at pH 7.0. To our knowledge, this is the first demonstration of reduced uptake of a lipophilic metal complex at low pH. The presence of SRHA also affected uptake, either by binding the lipophilic complex in solution and reducing its bioavailability (pH 7.0) or by increasing the permeability of the algal membrane (pH 5.5).

Acknowledgments

This work was supported by grants from the Canadian Network of Toxicology Centres (Environment Canada) and from the Natural Sciences and Engineering Research Council of Canada (NSERC). This paper is dedicated to the memory of Dr Mark Florence, whose ideas and research on metal–algae interactions were an important stimulus for this work. P.G.C.C. is supported by the Canada Research Chair Program.

References

Uptake of Neutral Metal Complexes by a Green Alga: Influence of pH and Humic Substances

Abstract

Acknowledgments

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