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Using nitrogen isotope fractionation to assess redox reactions of organic contaminants

English title Using nitrogen isotope fractionation to assess redox reactions of organic contaminants
Applicant Hofstetter Thomas
Number 116447
Funding scheme Project funding
Research institution Umweltchemie Eawag
Institution of higher education ETH Zurich - ETHZ
Main discipline Other disciplines of Environmental Sciences
Start/End 01.03.2008 - 28.02.2011
Approved amount 169'956.00
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Keywords (9)

compound-specific isotope analysis; CSIA; kinetic isotope effect; isotopic enrichment factor; groundwater pollution; redox reactions; organic groundwater contaminants; isotope fractionation; kinetic isotope effects

Lay Summary (English)

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Lay summary
Compound-specific isotope analysis (CSIA) is a very promising tool for the qualitative and quantitative assessment of organic contaminant transformation in the environment. For a specific element (e.g., H, C, N, O) present in an organic compound of interest, CSIA can be used to detect changes in its bulk isotopic composition occurring during a particular transformation reaction. In many cases, these changes can be expressed quantitatively by an isotopic enrichment factor, ?, which may then be very useful to assess the extent of contaminant degradation in more complex environments.

While CSIA of the elements C and H has been applied successfully to assess the transformation of a variety of groundwater contaminants including chlorinated solvents, fuel components and fuel additives, its potential for assessing priority contaminants such as pesticides, dyes, and explosives, exhibiting nitrogen-containing functional groups is largely unexplored. On the basis of our newly developed analytical methods for studying 15N fractionation in organic contaminants, we will investigate redox reactions of organic contaminants under environmental conditions typical for soils and aquifers. The type of reactions to be investigated include the reduction of aromatic nitro and azo groups by reduced iron species, the surface catalyzed oxidation of aromatic amines by manganese oxide, and the enzymatic, oxidative dealkylation of tertiary amines. By using series of structurally related model compounds, we will study the effect of compound properties (effect of different substituents) and of system properties (type of reductant/oxidant, pH) on isotope fractionation. The interpretation of measured isotope effects will be supported by theoretical work including density functional calculations carried out in collaboration with research groups at the University of Minnesota.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
134720 Using nitrogen isotope fractionation to assess redox reactions of organic contaminants 01.04.2011 Project funding
140545 Tracking Water Disinfection By-Product Formation by Multi-Element Isotope Fractionation Analysis 01.08.2012 Project funding
113871 Coupling of biogeochemical Fe(III) mineral reduction and pollutant transformation in anoxic environments 01.10.2006 Project funding

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