Details zur Publikation

Kategorie Textpublikation
Referenztyp Zeitschriften
DOI 10.5194/hess-21-5243-2017
Titel (primär) Pesticide fate on catchment scale: conceptual modelling of stream CSIA data
Autor Lutz, S.R.; van der Velde, Y.; Elsayed, O.F.; Imfeld, G.; Lefrancq, M.; Payraudeau, S.; van Breukelen, B.M.
Quelle Hydrology and Earth System Sciences
Erscheinungsjahr 2017
Department CATHYD
Band/Volume 21
Heft 10
Seite von 5243
Seite bis 5261
Sprache englisch
UFZ Querschnittsthemen RU2;
Abstract Compound-specific stable isotope analysis (CSIA) has proven beneficial in the characterization of contaminant degradation in groundwater, but it has never been used to assess pesticide transformation on catchment scale. This study presents concentration and carbon CSIA data of the herbicides S-metolachlor and acetochlor from three locations (plot, drain, and catchment outlets) in a 47 ha agricultural catchment (Bas-Rhin, France). Herbicide concentrations at the catchment outlet were highest (62 µg L−1) in response to an intense rainfall event following herbicide application. Increasing δ13C values of S-metolachlor and acetochlor by more than 2 ‰ during the study period indicated herbicide degradation. To assist the interpretation of these data, discharge, concentrations, and δ13C values of S-metolachlor were modelled with a conceptual mathematical model using the transport formulation by travel-time distributions. Testing of different model setups supported the assumption that degradation half-lives (DT50) increase with increasing soil depth, which can be straightforwardly implemented in conceptual models using travel-time distributions. Moreover, model calibration yielded an estimate of a field-integrated isotopic enrichment factor as opposed to laboratory-based assessments of enrichment factors in closed systems. Thirdly, the Rayleigh equation commonly applied in groundwater studies was tested by our model for its potential to quantify degradation on catchment scale. It provided conservative estimates on the extent of degradation as occurred in stream samples. However, largely exceeding the simulated degradation within the entire catchment, these estimates were not representative of overall degradation on catchment scale. The conceptual modelling approach thus enabled us to upscale sample-based CSIA information on degradation to the catchment scale. Overall, this study demonstrates the benefit of combining monitoring and conceptual modelling of concentration and CSIA data and advocates the use of travel-time distributions for assessing pesticide fate and transport on catchment scale.
dauerhafte UFZ-Verlinkung
Lutz, S.R., van der Velde, Y., Elsayed, O.F., Imfeld, G., Lefrancq, M., Payraudeau, S., van Breukelen, B.M. (2017):
Pesticide fate on catchment scale: conceptual modelling of stream CSIA data
Hydrol. Earth Syst. Sci. 21 (10), 5243 - 5261 10.5194/hess-21-5243-2017