Effect of pH on cadmium toxicity, speciation, and accumulation during naphthalene biodegradation

Todd R. Sandrin, Raina Margaret Maier

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Lowering pH of a microbiological medium from 7 to 4 decreased cadmium toxicity during naphthalene biodegradation by a Burkholderia sp. Cadmium speciation and cadmium accumulation in the system were studied to explain this effect. Cadmium speciation was determined by direct measurement and by geochemical modeling. Previous studies have implicated the monovalent hydroxylated cadmium (CdOH+) species in the effect of pH on cadmium toxicity. Modeling analysis predicted CdOH+ formation only at very low concentrations (≤0.0128 μM), while the measured concentration of divalent ionic cadmium (Cd2+) was at least three orders of magnitude greater, suggesting that Cd2+ is the more significant metal form. With respect to cadmium accumulation, cells contained in media adjusted to pH 4 accumulated only 2.76 ± 0.76 mg Cd/g cells, whereas cells in media adjusted to pH 7 accumulated 8.52 ± 0.71 mg Cd/g cells. These data suggest that cadmium toxicity is correlated with increased cadmium accumulation rather than the formation of CdOH+ as pH is increased. At low pH, the decrease in cadmium accumulation may be caused by increased competition between hydrogen and cadmium ions for binding sites on the cell surface or by an increase in metal efflux pump activity due to an increase in the proton gradient that drives the efflux pump.

Original languageEnglish (US)
Pages (from-to)2075-2079
Number of pages5
JournalEnvironmental Toxicology and Chemistry
Volume21
Issue number10
StatePublished - Oct 2002

Fingerprint

Biodegradation
naphthalene
Cadmium
Toxicity
biodegradation
cadmium
toxicity
effect
Protons
pump
Metals
Pumps
Burkholderia
metal
modeling
Hydrogen
Binding Sites
hydrogen
Ions

Keywords

  • Biodegradation
  • Cadmium toxicity
  • pH
  • Speciation

ASJC Scopus subject areas

  • Environmental Science(all)
  • Environmental Chemistry
  • Toxicology
  • Health, Toxicology and Mutagenesis

Cite this

Effect of pH on cadmium toxicity, speciation, and accumulation during naphthalene biodegradation. / Sandrin, Todd R.; Maier, Raina Margaret.

In: Environmental Toxicology and Chemistry, Vol. 21, No. 10, 10.2002, p. 2075-2079.

Research output: Contribution to journalArticle

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