Dual-Element Isotope Analysis of Desphenylchloridazon to Investigate Its Environmental Fate in a Systematic Field Study:A Long-Term Lysimeter Experiment
Author(s)
Melsbach, Aileen
Ponsin, Violaine
Bolotin, Jakov
Lachat, Laurence
Prasuhn, Volker
Hofstetter, Thomas B.
Date issued
March 2020
In
Environmental Sceince and Technology
Vol
7
No
54
From page
3929
To page
3939
Reviewed by peer
1
Abstract
Desphenylchloridazon (DPC), the main metabolite
of the herbicide chloridazon (CLZ), is more water soluble and
persistent than CLZ and frequently detected in water bodies. When
assessing DPC transformation in the environment, results can be
nonconclusive if based on concentration analysis alone because
estimates may be confounded by simultaneous DPC formation from
CLZ. This study investigated the fate of DPC by combining
concentration-based methods with compound-specific C and N
stable isotope analysis (CSIA). Additionally, DPC formation and
transformation processes were experimentally deconvolved in a
dedicated lysimeter study considering three scenarios. First, surface
application of DPC enabled studying its degradation in the absence
of CLZ. Here, CSIA provided evidence of two distinct DPC
transformation processes: one shows significant changes only in 13C/12C, whereas the other involves changes in both 13C/12C and 15N/14N isotope ratios. Second, surface application of CLZ mimicked a realistic field scenario, showing that during DPC formation, 13C/12C ratios of DPC were depleted in 13C relative to CLZ, while 15N/14N ratios remained constant. Finally, CLZ depth injection
simulated preferential flow and demonstrated the importance of the topsoil for retaining DPC. The combination of the lysimeter
study with CSIA enabled insights into DPC transformation in the field that are superior to those of studies of concentration trends.
of the herbicide chloridazon (CLZ), is more water soluble and
persistent than CLZ and frequently detected in water bodies. When
assessing DPC transformation in the environment, results can be
nonconclusive if based on concentration analysis alone because
estimates may be confounded by simultaneous DPC formation from
CLZ. This study investigated the fate of DPC by combining
concentration-based methods with compound-specific C and N
stable isotope analysis (CSIA). Additionally, DPC formation and
transformation processes were experimentally deconvolved in a
dedicated lysimeter study considering three scenarios. First, surface
application of DPC enabled studying its degradation in the absence
of CLZ. Here, CSIA provided evidence of two distinct DPC
transformation processes: one shows significant changes only in 13C/12C, whereas the other involves changes in both 13C/12C and 15N/14N isotope ratios. Second, surface application of CLZ mimicked a realistic field scenario, showing that during DPC formation, 13C/12C ratios of DPC were depleted in 13C relative to CLZ, while 15N/14N ratios remained constant. Finally, CLZ depth injection
simulated preferential flow and demonstrated the importance of the topsoil for retaining DPC. The combination of the lysimeter
study with CSIA enabled insights into DPC transformation in the field that are superior to those of studies of concentration trends.
Publication type
journal article
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