Speciation-dependent toxicity of Neptunium(V) toward Chelatobacter heintzii

James E. Banaszak; Donald T. Reed; Bruce E. Rittmann

doi:10.1021/es970664h

Speciation-dependent toxicity of Neptunium(V) toward Chelatobacter heintzii

James E. Banaszak, Donald T. Reed, Bruce E. Rittmann

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

This work investigates how chemical speciation controls the toxicity of neptunium and the neptunium - NTA complex toward Chelatobacter heintzii. We studied the effect of aquo and complexed/precipitated neptunium on the growth of C. heintzii in noncomplexing, glucose and phosphate-buffered nitrilotriacetic acid (NTA) growth media. Equilibrium chemical speciation modeling and absorption spectroscopy were used to link neptunium speciation to biological growth inhibition. Our results show that metal toxicity of aquo NpO₂⁺ significantly limits the growth of C. heintzii at free metal ion concentrations greater than ≃10^-5 M. However, neptunium concentrations ≤10^-4 M do not cause measurable radiotoxicity effects in C. heintzii when present in the, form of a neptunium - NTA complex or colloidal/precipitated neptunium phosphate. The neptunium - NTA complex, which is stable under aerobic conditions, is destabilized by microbial degradation of NTA. When phosphate was present, degradation of NTA led to the precipitation of a neptunium-phosphate phase.

Original language	English (US)
Pages (from-to)	1085-1091
Number of pages	7
Journal	Environmental Science and Technology
Volume	32
Issue number	8
DOIs	https://doi.org/10.1021/es970664h
State	Published - Apr 15 1998
Externally published	Yes

ASJC Scopus subject areas

Chemistry(all)
Environmental Chemistry

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title = "Speciation-dependent toxicity of Neptunium(V) toward Chelatobacter heintzii",

abstract = "This work investigates how chemical speciation controls the toxicity of neptunium and the neptunium - NTA complex toward Chelatobacter heintzii. We studied the effect of aquo and complexed/precipitated neptunium on the growth of C. heintzii in noncomplexing, glucose and phosphate-buffered nitrilotriacetic acid (NTA) growth media. Equilibrium chemical speciation modeling and absorption spectroscopy were used to link neptunium speciation to biological growth inhibition. Our results show that metal toxicity of aquo NpO2+ significantly limits the growth of C. heintzii at free metal ion concentrations greater than ≃10-5 M. However, neptunium concentrations ≤10-4 M do not cause measurable radiotoxicity effects in C. heintzii when present in the, form of a neptunium - NTA complex or colloidal/precipitated neptunium phosphate. The neptunium - NTA complex, which is stable under aerobic conditions, is destabilized by microbial degradation of NTA. When phosphate was present, degradation of NTA led to the precipitation of a neptunium-phosphate phase.",

author = "Banaszak, {James E.} and Reed, {Donald T.} and Rittmann, {Bruce E.}",

year = "1998",

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journal = "Environmental Science & Technology",

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AU - Banaszak, James E.

AU - Reed, Donald T.

AU - Rittmann, Bruce E.

PY - 1998/4/15

Y1 - 1998/4/15

N2 - This work investigates how chemical speciation controls the toxicity of neptunium and the neptunium - NTA complex toward Chelatobacter heintzii. We studied the effect of aquo and complexed/precipitated neptunium on the growth of C. heintzii in noncomplexing, glucose and phosphate-buffered nitrilotriacetic acid (NTA) growth media. Equilibrium chemical speciation modeling and absorption spectroscopy were used to link neptunium speciation to biological growth inhibition. Our results show that metal toxicity of aquo NpO2+ significantly limits the growth of C. heintzii at free metal ion concentrations greater than ≃10-5 M. However, neptunium concentrations ≤10-4 M do not cause measurable radiotoxicity effects in C. heintzii when present in the, form of a neptunium - NTA complex or colloidal/precipitated neptunium phosphate. The neptunium - NTA complex, which is stable under aerobic conditions, is destabilized by microbial degradation of NTA. When phosphate was present, degradation of NTA led to the precipitation of a neptunium-phosphate phase.

AB - This work investigates how chemical speciation controls the toxicity of neptunium and the neptunium - NTA complex toward Chelatobacter heintzii. We studied the effect of aquo and complexed/precipitated neptunium on the growth of C. heintzii in noncomplexing, glucose and phosphate-buffered nitrilotriacetic acid (NTA) growth media. Equilibrium chemical speciation modeling and absorption spectroscopy were used to link neptunium speciation to biological growth inhibition. Our results show that metal toxicity of aquo NpO2+ significantly limits the growth of C. heintzii at free metal ion concentrations greater than ≃10-5 M. However, neptunium concentrations ≤10-4 M do not cause measurable radiotoxicity effects in C. heintzii when present in the, form of a neptunium - NTA complex or colloidal/precipitated neptunium phosphate. The neptunium - NTA complex, which is stable under aerobic conditions, is destabilized by microbial degradation of NTA. When phosphate was present, degradation of NTA led to the precipitation of a neptunium-phosphate phase.

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Speciation-dependent toxicity of Neptunium(V) toward Chelatobacter heintzii

Abstract

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