Dynamic silver speciation as studied with fluorous-phase ion-selective electrodes: Effect of natural organic matter on the toxicity and speciation of silver

Maral P S Mousavi, Ian L. Gunsolus, Carlos E. Pérez De Jesús, Mitchell Lancaster, Kadir Hussein, Christy L. Haynes, Philippe Bühlmann

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28 Scopus citations

Abstract

The widespread application of silver in consumer products and the resulting contamination of natural environments with silver raise questions about the toxicity of Ag+ in the ecosystem. Natural organic matter, NOM, which is abundant in water supplies, soil, and sediments, can form stable complexes with Ag+, altering its bioavailability and toxicity. Herein, the extent and kinetics of Ag+ binding to NOM, matrix effects on Ag+ binding to NOM, and the effect of NOM on Ag+ toxicity to Shewanella oneidensis MR-1 (assessed by the BacLight viability assay) were quantitatively studied with fluorous-phase Ag+ ion-selective electrodes (ISEs). Our findings show fast kinetics of Ag+ and NOM binding, weak Ag+ binding for Suwannee River humic acid, fulvic acid, and aquatic NOM, and stronger Ag+ binding for Pony Lake fulvic acid and Pahokee Peat humic acid. We quantified the effects of matrix components and pH on Ag+ binding to NOM, showing that the extent of binding greatly depends on the environmental conditions. The effect of NOM on the toxicity of Ag+ does not correlate with the extent of Ag+ binding to NOM, and other forms of silver, such as Ag+ reduced by NOM, are critical for understanding the effect of NOM on Ag+ toxicity. This work also shows that fluorous-phase Ag+ ISEs are effective tools for studying Ag+ binding to NOM because they can be used in a time-resolved manner to monitor the activity of Ag+ in situ with high selectivity and without the need for extensive sample preparation.

Original languageEnglish (US)
Pages (from-to)453-461
Number of pages9
JournalScience of the Total Environment
Volume537
DOIs
StatePublished - Dec 15 2015

Bibliographical note

Funding Information:
This work was supported by a Graham N. Gleysteen Excellence Fellowship and a UMN Doctoral Dissertation Fellowship for M. P. S. Mousavi, a National Science Foundation MRSEC REU award for C. E. Pérez De Jesús (Research Experiences for Undergraduates, REU, DMR-1263062 ), a National Institutes of Health Training for Future Biotechnology Development Grant ( T32 GM008347 ) and Minneapolis Torske Klubben Graduate Fellowship to I. L. Gunsolus, a University of Minnesota Heisig/Gleysteen fellowship to K. Hussein, and National Science Foundation ( CHE-1152931 ) funding to C.L. Haynes.

Publisher Copyright:
© 2015 Elsevier B.V.

Keywords

  • Fluorous
  • Fulvic acid
  • Humic acid
  • Ion-selective electrode
  • Natural organic matter
  • Silver nanoparticles
  • Toxicity

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