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Experiments and numerical

studies on transport of

sulfadiazine in soil columns

Inaugural-Dissertation

zur Erlangung des Grades Doktor der Agrarwissenschaft

(Dr. agr.)

der Hohen Landwirtschaftlichen Fakultt

der Rheinischen Friedrich-Wilhelms-Universitt

zu Bonn

vorgelegt am 18. Dezember 2009

von Myriam Unold

aus Landstuhl, Deutschland

Referent: Prof. Dr. Harry Vereecken

Ko-Referent: Prof. Dr. Wulf Amelung

Tag der mndlichen Prfung: 07. Juli 2010

Erscheinungsjahr: 2010

i

Acknowledgements First of all I want to thank my promotor Prof. Harry Vereecken, head of the ICG-4,

Agrosphere, Forschungszentrum Jlich GmbH, Dr. Thomas Ptz and Dr. Joost Groeneweg,

head of the project Veterinary pharmaceuticals in soils, for the chance to conduct this

thesis at the Agrosphere Institute which included amongst others the possibility to stay in

the USA for three month. Furthermore I thank Prof. Wulf Amelung (University of Bonn)

for being my co-promotor. I express my gratitude to the German Research Foundation for

funding this thesis in the frame of the research group Veterinary medicines in soils Basic

Research for Risk analysis and I thank the members of the research group for many

inspiring discussions and information. I am especially grateful to Dr. Marc Lamshft

(University of Dortmund) for his support in the analysis of metabolites. I also thank Bayer

HealthCare for providing the 14C-labeled sulfadiazine and BayerCropScience AG for the

performance of the feeding experiment.

I appreciate the staff of the ICG-4 for the pleasant working atmosphere, especially

numerous people who greatly contributed to the performance of the experiments and the

evaluation of data. A special thank goes to my direct mentor Dr. Roy Kasteel for his

excellent advice and support during the last years. For adapting the Hydrus-1D code to my

experiments, the corrections of the second manuscript and the kind hospitality I thank Prof.

Jirka imnek and also his working group at the University of California, Riverside. For

building the experimental setup for the soil column experiments and their quick help in all

kind of technical questions I express my gratitude to Ansgar Weuthen and Jrgen

Hltkemeier. I am also very grateful to Thorsten Bttner and Rainer Harms for their efforts

during sampling in the field. The performance of the transport experiments in the laboratory

would have been impossible without the splendid help of Thorsten Bttner, Kavita

Mayekar, Stefan Masjosthuisman and Maja Stiefelhagen. For conducting the HPLC-

measurements and his patience in detecting and quantifying metabolites I am very grateful

to Stephan Kppchen. For advice in questions regarding laboratory issues I thank also

Odilia Esser, Werner Mittelstdt, Anke Langen, Herbert Philipp, Anne Berns, Ulrike

Langen and Martina Krause. For answering all questions regarding programming and the

Hydrus1D-code I am much obliged to Horst Hardelauf. I thank Roy Kasteel, Joost

Groeneweg and Harry Vereecken for reading drafts of the manuscript. For their company

and friendship during my stay in Jlich I thank my fellow PhD-students, especially my

roommates Jana and Katrin as well as our neighbours Christoph and John. Finally, special

thanks to my family, friends and Ansgar for their love, support and understanding.

ii

iii

Summary Veterinary antibiotics like sulfadiazine (SDZ) are used in large amounts worldwide.

Excreted as parent compounds or in the form of metabolites they reach agricultural soils

mainly via spreading of manure or sewage sludge and may be transported to the

groundwater. Recently, antibiotics have been detected in several environmental

compartments leading to an increasing concern about their hazardous effects. To asses the

leaching potential of SDZ from soils into groundwater, knowledge on its transport

processes in soils is necessary. Also the transport of its metabolites as well as possible

transformation processes have to be considered.

In this work transport experiments at the column scale were performed. Therefore,

SDZ and pig manure were used to analyze the governing processes that affect the transport

of SDZ in disturbed and undisturbed soil columns of a loamy sand and a silty loam. For this

purpose the Hydrus model (imnek et al., 2008) has been adapted and applied to the

observed BTCs and resident concentrations.

The occurrence of transformation products in the outflow of repacked soil columns of

both soils was investigated in experiments with a SDZ-solution. For the prediction of the 14C-distribution in the repacked soil columns, empirical approaches to describe irreversible

sorption were tested. Furthermore the influence of flow rate and concentration/applied mass

on SDZ transport was investigated and the respective experiments were simultaneously

described with a common set of parameters. In transport experiments with pig manure, the

effect of pig manure on the transport of SDZ as well as the transport behavior of the main

metabolites of SDZ present in pig manure, N-Ac-SDZ and 4-OH-SDZ, were investigated.

Without considering a known photo-degradation product transformation was very low

in both investigated soils. In soil columns where most of the 14C was found near the soil

surface, the prediction of the 14C-concentration profiles was improved by applying two

empirical models other than first-order to predict irreversible sorption. The application of

SDZ at a higher flow rate led to higher eluted masses and concentrations compared to

experiments conducted at a lower flow rate. The simultaneous fitting process with a three

site attachment/detachment model revealed that although the same sorption mechanisms

seem to occur in all experiments, their characteristic time scales were different, especially

under transient flow conditions. As the main difference between experiments with manure

and SDZ-solution an accumulation of 14C in the upper soil layer was found in the

experiments with manure. The modeling process revealed a high mobility of both SDZ and

its transformation products. While the transformation of N-Ac-SDZ into SDZ was fast and

no extended tailing of N-Ac-SDZ was observed, the transport behavior of 4-OH-SDZ was

similar to SDZ.

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v

Kurzfassung In der Tiermedizin angewandte Antibiotika wie Sulfadiazin (SDZ) werden weltweit

in groen Mengen eingesetzt. Nachdem sie als Ausgangssubstanz oder in der Form von

Metaboliten ausgeschieden werden, gelangen sie hauptschlich durch das Ausbringen von

Glle oder Klrschlamm in landwirtschaftliche Bden von wo aus sie ins Grundwasser

transportiert werden knnen. In den letzten Jahren wurden Antibiotika in verschiedenen

Umweltmedien nachgewiesen was aufgrund ihrer schdlichen Auswirkungen zu einer

steigenden Besorgnis gefhrt hat. Um das Potential einer mglichen Auswaschung von

SDZ ins Grundwasser einschtzen zu knnen, sind Kenntnisse ber die Transportprozesse

in Bden entscheidend. Auch der Transport der Metabolite sowie mgliche

Transformationsprozesse mssen bercksichtigt werden.

In dieser Dissertation wurden Transportexperimente auf der Skala von Bodensulen

durchgefhrt. Anhand von SDZ-Lsungen und SDZ-haltiger Schweineglle wurden

Prozesse untersucht, die den Transport von SDZ in gestrten und ungestrten Bodensulen

eines lehmigen Sandes und eines schluffigen Lehms beeinflussen. Dazu wurde das Model

Hydrus (imnek et al., 2008) verndert und zur Modellierung der gemessenen

Durchbruchskurven und Profilkonzentrationen genutzt.

Das Auftreten von Transformationsprodukten im Ausfluss von gepackten

Bodensulen beider Bden wurde in Experimenten mit einer SDZ-Lsung untersucht. Zur

Vorhersage der 14C-Konzentrationen in den Bodenprofilen wurden empirische Anstze zur

Beschreibung der irreversiblen Sorption getestet. Zustzlich wurde der Einfluss von

Flierate und Konzentration/applizierter Masse auf den Transport von SDZ untersucht.

Whrend des Modellierungsprozesses wurden die entsprechenden Experimente mit einem

gemeinsamen Parametersatz beschrieben. In Transportexperimenten mit Schweineglle

wurden der Einfluss von Schweineglle auf den Transport von SDZ sowie das Verhalten

der in der Schweinglle vorhandenen Hauptmetabolite, N-Ac-SDZ und 4-OH-SDZ,

untersucht.

Ohne Bercksichtung eines bekannten Phototransformationsproduktes war die

Transformation von SDZ in beiden Bden sehr gering. In den Bodensulen wurde die

grte Menge an 14C nahe der Oberflche gefunden. Die Beschreibung dieses Musters

konnte durch die Anwendung zweier empirischer Modelle zur Beschreibung der

irreversiblen Sorption verbessert werden. Die Applikation von SDZ bei einer hheren

Flierate fhrte, im Vergleich zu Experimenten, die bei einer geringen Flierate

durchgefhrt wurden, zu hheren eluierten Mengen. Die simultane Modellierung mit einem

dreiseitigen attachment/detachment Model zeigte, dass die charakteristischen Zeitskalen in

den Experimenten verschieden sind, obwohl in al