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Influence of complexation with chloride on the responses of a lux‐marked bacteria bioassay to cadmium, copper, lead, and mercury
Author(s) -
Sarin Charoon,
Hall Jennifer M.,
CotterHowells Janet,
Killham Ken,
Cresser Malcolm S.
Publication year - 2000
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620190202
Subject(s) - chemistry , cadmium , mercury (programming language) , toxicity , chloride , bioassay , metal toxicity , environmental chemistry , chelation , metal , metal ions in aqueous solution , copper , nuclear chemistry , cadmium chloride , inorganic chemistry , aqueous solution , organic chemistry , ecology , biology , computer science , programming language
Abstract The toxicity of a heavy metal in solution to a microorganism depends not only on its concentration but also on pH and the concentrations of any aqueous complexing ligands in the microorganism's environment. This paper reports on the use of different inorganic resuscitation media and effect of the chloride ion, Cl − , on the bioluminescence response of a bacterial biosensor, Escherichia coli HB101 (pUCD607), to four metals: Cd, Cu, Hg, and Pb. The toxicity tests were conducted at pH 4, using 0.1 M KNO 3 as resuscitation medium and adding KCl to investigate effect of Cl − concentration. The species distributions of metals as a function of Cl − concentration were calculated using GeoChem‐PC. Resuscitation in 0.1 M KC1 gave significantly higher light output than that in 0.1 M KNO 3 , demonstrating that Cl − in the resuscitation medium has a direct effect on the bioluminescence response of the E. coli biosensor. Increasing concentrations of Cl − ions increased the toxicity of Hg, apparently because of the formation of HgCl − 3 , and increased the toxicity of Pb because of PbCl + formation. The toxicity of Cu decreased at high Cl − concentrations as free Cu 2+ decreased, in accordance with the free ion model. Concentrations of Cl − had no significant effect on the toxicity of Cd. This study clearly demonstrates that the chloro‐complexes of some heavy metals can be toxic and, for Pb and Hg, more toxic than the free ion.