Assessment of micropollutant degradation using multi-element compound-specific isotope analysis
| Responsable du projet |
Daniel Hunkeler
Thomas Hofstetter Martin Elsner Hans Peter Kohler |
| Résumé |
The frequent detection of polar organic micropollutants such as
pesticides, consumer care products or pharmaceutical in water is an
increasing concern for human and ecosystem health. Currently, little
is known about the long-term fate of such compounds in aquatic
systems due to the difficulty in demonstrating their degradation.
Compound-specific isotope analysis (CSIA) of multiple elements is a
potentially powerful method to evaluate organic micropollutant
transformation because pathway-specific isotope fractionation is
expected to occur for many compounds as suggested by some recent
studies of the applicants. For classical priority pollutants such
as chlorinated and petroleum hydrocarbons, CSIA has become a
well-established method to identify and quantify degradation
pathways. The extension of the CSIA approach to micropollutants is
challenging for several reasons: Micropollutants are typically
present in lower concentrations thus requiring more extensive
preconcentration, they often are more polar hence requiring
derivatization before gas chromatographic analysis, they frequently
include heteroatoms complicating their conversion to measurement
gases for mass spectrometry, and they are degraded by a wide range
of mechanisms, whose isotope effects are not known yet. The main
goal of this project is to extend the CSIA approach for assessing
degradation pathways to polar organic micropollutants, thereby
demonstrating that (i) it is feasible to analyze the isotopic
composition of common organic micropollutants at field-relevant
concentration levels (analytical method development), (ii) a
multi-isotope approach can be used to gain unique insight into
pathways of micropollutant degradation (process studies), (iii)
transformation processes can be identified and quantified based on
micropollutants' isotope ratios under field conditions and/or in
experimental settings mimicking field conditions (system studies).
Given the numerous challenges that have to be overcome to establish
multi-element CSIA for micropollutant, a collaborative research
strategy will be chosen that brings together leading experts in the
field of CSIA and micropollutant studies from the University of
Neuchâtel (UNINE), the Helmholtz Zentrum München (HGMU),
the Swiss Federal Institute of Aquatic Science and Technology
(Eawag), and Agroscope Reckenholz-Tänikon Research Station
(ART). The participation of the German partner, HGMU, is essential
for the analytical part of the project and will make it possible to
transfer some of its unique expertise in micropollutant CSIA to
Swiss institutions. The project consists of three PhD theses. Each
of them focuses on a specific, highly-relevant organic
micropollutant and emphasizes one of the three conceptual
activities, that is analytical methods, transformation processes,
and system studies. Subproject 1 (led by UNINE) investigates if
multi-element CSIA can be used to identify and quantify
micropollutant transformation in complex systems where
transformation and transport processes interact. The project will
make use of lysimeter experiments, which allow control of
experimental conditions. The project will focus on substances for
which pathway-specific isotope fractionation and analytical methods
are already established. Subproject 2 (HGMU) is dedicated to the
challenge of multielement isotope analysis for micropollutants. Its
objectives are the isotope analysis of lysimeter samples, as well as
the analytical method development and degradation process studies
for chloridazon and desphenyl-chloridazon as emerging pesticides of
concern. Subproject 3 (Eawag) targets a class of consumer chemicals
(benzotriazoles), which are widely encountered in the aquatic
environment but whose fate assessment is hampered by the lack of
knowledge regarding (bio)degradation processes. The overall project
includes extensive collaboration across subprojects:
Multi-element-CSIA methods will be jointly developed bringing
together the complementary expertise of the partners, laboratory
process studies will be carried out in close collaboration sharing
experimental setups and tools, and the lysimeter experiments will
be jointly executed sharing the high load of concentration
measurements and CSIA analysis. In order to favor collaboration,
joint semi-annual meetings are planned, as well as short term
scientific visits of the PhD fellows at the partner institutions.
The project is expected to lead to a series of groundbreaking
publications on multi-element micropollutant CSIA and bring the
method a substantial step forward towards its field application as
unique method to characterize the long-term micropollutant fate in
aquatic systems, a pressing issue for society. |
| Mots-clés |
biodegradation, stable isotopes, organic micropollutants |
| Type de projet | Recherche fondamentale |
| Domaine de recherche | Autres secteurs des sciences de l`environnement |
| Source de financement | FNS (Sinergia) |
| Etat | Terminé |
| Début de projet | 1-7-2013 |
| Fin du projet | 30-6-2016 |
| Budget alloué | 736'144.00 |
| Contact | Daniel Hunkeler |