Veterinary Medicines

Environmental Toxicology and Chemistry, Vol. 24, No. 4, pp. 777–781, 2005 q 2005 SETAC Printed in the USA 0730-7268/05 $12.00 1 .00

Veterinary Medicines TEST-PLOT STUDIES ON RUNOFF OF SULFONAMIDES FROM MANURED SOILS AFTER SPRINKLER IRRIGATION ROBERT KREUZIG,*† SIBYLLA HO¨LTGE,† JOACHIM BRUNOTTE,‡ NORBERT BERENZEN,§ JO¨RN WOGRAM,§ and RALF SCHULZ§ †Institute of Ecological Chemistry and Waste Analysis, Technical University of Braunschweig, D-38106 Braunschweig, Germany ‡Institute for Production Engineering and Building Research, Federal Agricultural Research Center, D-38112 Braunschweig, Germany §Zoological Institute, Technical University of Braunschweig, D-38106 Braunschweig, Germany ( Received 23 October 2003; Accepted 19 April 2004) Abstract—Three test-plot series have been performed to gather information on runoff of sulfonamides from manured arable and grassland after sprinkler irrigation. To prepare test slurries with defined aged residues, liquid bovine manure was fortified with sulfadiazine, sulfadimidine, and sulfamethoxazole and stored short-term. After test-slurry application, the arable land was treated by soil cultivation before irrigation, and the manured grassland was irrigated directly with 50 mm h21 for 2 h. The runoff suspensions were sampled at 5- to 10-min intervals, separated into aqueous phase and suspended matter and residue analyzed. Higher runoff emissions were found from manured grassland plots. The discharge volumes ranged from 106 to 252 L and the total runoff emissions ranged from 13 to 28% of sulfonamides applied initially. Within the first 20 min of the irrigation period that represented a rainfall of 17 mm, emissions, on average, were 4%. The loads of sulfonamides predominantly occurred in the runoff water. The only emissions via suspended matter, on average, were 0.02%. On arable land, however, the runoff was reduced by soil cultivation. Discharge volumes and sulfonamide emissions were 36 to 128 L and 0.1 to 2.5%, respectively. Despite the high-intensity sprinkler irrigation, major emissions did not occur until a 60-min delay. Keywords—Sulfonamides

Test-plot studies

Test-slurry application

Runoff

Sprinkler irrigation

the Evaluation of Medicinal Products [7] and in the exposure assessment of the German Federal Environmental Agency’s registration procedure [8]. Due to the limitations of available results from field studies, this research project has been conducted to provide initial data on runoff of veterinary pharmaceutical products after high-intensity sprinkler irrigation. In order to assess the potential risk for surface-water contamination by runoff, variable site-specific and seasonal parameters have been investigated. In order to mimic the real entry route as closely as possible, liquid bovine manure was fortified with the sulfonamides sulfadiazine, sulfadimidine, and sulfamethoxazole, which have been identified as pollutants in liquid manures [9–15], and stored to prepare test slurries with defined aged residues. Then, test slurries were applied onto test plots on arable and grassland that subsequently were sprinkler irrigated to simulate heavy precipitation events.

INTRODUCTION

Veterinary pharmaceutical products applied in livestock husbandry may be excreted as parent compounds and metabolites by production animals via urine and feces. Hence, residues are released into soil environments by polluted dung pats on pasture or by applications of contaminated manures onto arable and grassland. Thus, it may be valuable to investigate the stability of veterinary pharmaceutical residues in manures during the storage period and the degradability in soils applying laboratory test systems [1]. Furthermore, mobility of the residues via leaching and surface runoff as possible routes of groundwater and surface water contamination, respectively, needs to be assessed by conducting field trials. Besides interflow, surface runoff has been identified as an environmentally relevant nonpoint source for pesticides affecting aquatic organisms in headwater streams of agricultural areas [2–4]. Runoff risk usually is given by slopes of $2% and by precipitation events of $10 mm d21 particularly enhanced by the physico-chemical properties of loamy soils. Emission factors considered for runoff and erosion were calculated by Pussemier and Beernaerts [5]. According to their results, 0.4 to 2% of more polar pesticides (e.g., herbicides) applied by spray application were considered to leave the treated fields. Liess et al. [6] found that 0.01 and 0.07% of the less polar, strongly soil-adsorbed insecticides fenvalerate and parathion, respectively, were released into a headwater stream by runoff from arable land. Runoff of veterinary pharmaceutical residues also is considered relevant in the guidance of the European Agency for

MATERIALS AND METHODS

Investigation site and test-plot setup At Adenstedt, the investigation site located in the Luvisol catchment area in the south of Hildesheim in a distance of 70 km to Braunschweig in Lower Saxony, Germany, three testplot series were conducted in October 2002 (series 1), April 2003 (series 2), and September 2003 (series 3). Thus, they cover different weather conditions and soil-water balances in autumn and spring. A potential runoff risk after heavy precipitation events was given by slopes of 2 to 10% and enhanced by silty-clay soils. The soil properties, which widely matched those of the European reference soil EUROSOIL 4 [16], were characterized for arable land by 5% sand, 56% silt, 39% clay, 1.6% organic carbon, and pH (CaCl2) 6.9 and for grassland by 2% sand, 59% silt, 39% clay, 3.0% organic carbon, and

* To whom correspondence may be addressed ([email protected]). 777

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Table 1. Runoff emissions in the test-plot series of October 2002 (series 1), April 2003 (series 2), and September 2003 (series 3) after highintensity sprinkler irrigation (50 mm h21, 2 h) given as percentages of actual sulfonamide amounts in test slurries applied onto soil Series 2

Series 3

Arable landb Arable landb plot 1 plot 2 Grassland

Arable landb Arable landb plot 1 plot 2 Grassland

Series 1 Plot Slope (%)

Arable landa 7.7

Grassland 9.0

8.2

8.2

9.0

7.7

7.7

9.0

Residue levels in slurries applied onto soil (g 20 kg21) Sulfadiazine 4.3 4.2 Sulfadimidine 6.5 4.1 Sulfamethoxazole 5.1 5.3 Discharge (L) 36 181

0.5 0.7 0.6 73

0.4 0.4 0.3 66

0.2 0.4 0.3 252

0.9 1.0 1.0 99

0.8 NAc NA 128

0.4 NA NA 106

2.5 1.2 1.6

0.1 0.2 0.2

27.6 15.8 13.3

0.1 0.1 0.1

0.2 NA NA

14.4 NA NA

Runoff emissions via aqueous phase (%) Sulfadiazine 1.2 Sulfadimidine 0.8 Sulfamethoxazole 0.9

17.9 27.4 15.5

a

Test-slurry application onto arable soil in winter wheat postharvest stage. Test-slurry application onto arable soil in cultivator drill stage. c NA 5 not applied. b

pH (CaCl2) 4.5. The test plots of approximately 4 3 2 m2 were installed on arable and grassland. Discrete slopes were 7.7 and 8.2% on arable land as well as 9.0% on grassland.

Test-slurry preparation and application In series 1, 10 g of each technical-grade sulfadiazine (N1[2-pyrimidinyl]-sulfanilamide; Caesar and Lorentz, Hilden, Germany), sulfadimidine (N 1-[4,6-dimethyl-2-pyrimidinyl]sulfanilamide) and sulfamethoxazole (N1-[5-methyl-3isoazolyl]-sulfanilamide; both Synopharm, Barsbu¨ttel, Germany) suspended in 100 ml methanol (Merck, Darmstadt, Germany) were distributed homogeneously in 20 kg of liquid bovine manure. The manure amount for each test plot represented 50% of the maximum nitrogen content of 170 kg N ha21 a21 that is accepted by the German Ordinance Concerning Fertilizers [17]. According to sulfonamides that have been found in contaminated manures, application amounts were elevated in series 1 to ensure a first characterization of runoff tendencies. For test-slurry preparation with defined aged residues of sulfonamides, fortified manures were stored for 7 and 9 d, respectively. These different storage intervals corresponded to different start times of the discrete plot experiments caused by the technical reinstallation of the sprinkler apparatus from plot to plot, the weather conditions and the requirements of soil cultivation. During the storage of the manure, sulfonamides are subjected to degradation processes. Therefore, residue levels determined in slurries actually applied onto soils are listed in Table 1. On arable land at a slope of 7.7%, the test slurry was applied onto soil in winter wheat postharvest stage and incorporated into the Ap horizon by soil cultivation to 15-cm depth before sprinkler irrigation. In contrast, the grassland plot sloped at 9.0% was manured and subsequently irrigated. In series 2, the initial concentration of each sulfonamide was reduced to 1 g 20 kg21 manure largely to approach the real contamination levels of liquid manures that can exceed 10 mg kg21 as it was found for sulfadiazine [10,12]. The storage was 7 and 9 d that depended on the start of the discrete runoff experiment. On the basis of the initial concentration of sulfonamides in the liquid manure, a soil surface contamination for each sulfonamide was calculated to be 125 mg m22, matching the initial sulfonamide levels of 150 and 120 mg m22 realized in field studies of Burkhardt et al. [13] and Boxall et al. [14]. Test slurry was applied onto arable soil sloped at 8.2%

and remained in cultivator drill since October 2002, while it had been applied onto the wheat stubble in series 1. Then, cultivation was performed again before sprinkler irrigation. The grassland plot sloped at 9.0% and was irrigated directly after test-slurry application. In series 3, two parallel test plots were installed on arable land at a slope of 7.7%. Onto one test plot, test slurry containing 1 g of each sulfonamide in 20 kg was applied. In order to control effects caused by the application of sulfonamides in a mixture, the second one was manured with 1 g sulfadiazine 20 kg21 test slurry. Both experiments were conducted without any storage of the test slurry, thus no degradation has to be considered. Cultivator drill application was conducted again and test slurry applied was incorporated into the 0- to 15-cm soil layer by further cultivation before sprinkler irrigation. The single component design for sulfadiazine was realized additionally on the grassland plot sloped at 9.0%. Here, the test slurry contaminated at 1 g 20 kg21 was stored for 9 d. Directly after the application, the test plot was sprinkler irrigated.

Sprinkler irrigation and runoff sampling For the simulation of heavy precipitation events, a swing nozzle sprinkler was used. The swing nozzle was a Veejet 80/ 100 (Spraying System Company, Wheaton, IL, USA), generating a kinetic energy of 1.2 kJ m22 for 60-mm precipitation [18]. Each test plot was delimited by folding plates to transfer quantitatively the surface runoff suspension via a discharge channel into the runoff sampler at the plot exit. After the calibration procedure of the sprinkler apparatus to account for the differences in slopes of arable and grassland, the irrigation intensity was adjusted to 50 mm h21 for 2 h, simulating a worst-case scenario typical for test-plot experiments assuming no afflux from the surrounding agricultural area. Following the same principle, Ko¨rdel and Klo¨ppel [19] adjusted the experimental parameters of their test-plot studies for pesticide runoff as follows: The irrigation intensity was 65 to 75 mm h21 for 1 h with a 0.5-h postrun period and the test-plot areas were 4.6 3 1.5 m2 sloped at 10 to 16%. After the prerun period, when the discharge changed from drop-to-drop to continuous flow, the runoff samples were taken at 5 to 10 min intervals. The runoff suspensions were sampled quantitatively and the volumes of all samples were determined. After taking 250- to 1,000-ml aliquots for water analysis, the


Test-plot studies on runoff of sulfonamides

residual volumes were pooled in a tank to determine the suspended matter content after 48-h sedimentation. After decanting the supernatants, aliquots were taken for residue analytical purposes and stored at 2208C until analysis.

Residue analytical methods Test-slurry analysis. Prior to each test-slurry application, aliquots were sampled to determine the actual concentrations of sulfonamides. The slurry samples (50 g) were adjusted to pH 7.3 by adding sodium hydroxide solution (0.5%) [20]. Then, 50 ml 0.1 M acetate buffer, 10 g sodium chloride, and 100 ml ethyl acetate were added and the samples were shaken on a horizontal shaker (220 rpm; type 3020, Gesellschaft fu¨r Labortechnik, Burgwedel, Germany) overnight [1]. After decanting of the solvent, the samples were extracted again with ethyl acetate. Subsequently, the extracts were pooled and rotary evaporated. For the clean up via solid-phase extraction, the extracts were transferred to amino propyl cartridges (500 mg, 3 ml; Mallinckrodt-Baker, Griesheim, Germany) that were eluted using 15 ml demineralized water. Eluates were adjusted to pH 5.2 by adding acetic acid and additionally cleaned up using polystyrene/divinyl benzene cartridges (200 mg, 6 ml; Mallinckrodt-Baker) that were eluted using a 5-ml acetonitrile/ methanol mixture (1:1). These eluates were evaporated in a gentle nitrogen stream nearly to dryness. Then, chloridazone (5-amino-4-chloro-2-phenyl-pyridazine-3-one; 10 ng m l 21; Riedel-de Hae¨n, Seelze, Germany) was added as the internal standard. The sample solutions were filled up to 1 ml with acetonitrile:water mixture (1:9) and analyzed by reversedphase high-performance liquid chromatography with a variable wavelength detector and liquid chromatography coupled to electrospray ionization mass spectrometry [1]. The quality assurance was performed by fortification experiments. On the basis of average recoveries ranging from 67 to 97% with a relative standard deviation of #17%, the limits of determination were 100 mg kg21 slurry matching the European Agency for the Evaluation of Medicinal Products trigger [7]. Water analysis. The runoff suspensions were centrifuged at 4,000 rpm for 10 min (Megafuge 1.0; Hereaus, Osterode, Germany). Due to the amphoteric character of the sulfonamides, the supernatants decanted were adjusted to pH 5.2 by adding diluted sulfuric acid. Then, the target compounds were enriched by solid-phase extraction using polystyrene/divinyl benzene cartridges and subsequently eluted using a 5-ml acetonitrile:methanol mixture (1:1; all solvents used: HPLC or residue analytical grade, Merck) [21]. The eluates were evaporated in a gentle nitrogen stream. Chloridazone (10 ng ml21) was added again as the internal standard. The sample solutions were filled up to 1 ml with acetonitrile:water (1:9) and reversed-phase high-performance liquid chromatography with a variable wavelength detector and exemplarily analyzed by liquid chromatography coupled to electrospray ionization mass spectrometry. The quality assurance was performed by fortification experiments. On the basis of recoveries ranging from 80 to 111% with a relative standard deviation of #15%, limits of determination were 0.2 mg L21 surface water. Suspended-matter analysis. Suspended-matter analysis was conducted according to the principles of the soil analysis [1]. After defrosting, the aliquots of 50-g dry weight equivalents were weighed out and extracted with 50 ml 0.1 M acetate buffer (pH 5.2) and ethyl acetate (100 ml) on a horizontal shaker overnight. After decanting the solvent, the samples were rinsed twice with 50 ml ethyl acetate by shaking again for 30

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min each. The aliquots of 150 ml were rotary evaporated and redissolved into 5 ml methanol. For the clean-up step, gel permeation chromatography with Sephadex LH-20 (Gilson, Du¨sseldorf, Germany) was applied. The eluent was methanol containing acetic acid (0.01 M). Flow rate was 5 ml min21. The analyte fraction was sampled at 145 to 390 ml, rotary evaporated nearly to dryness, and redissolved in an acetonitrile:water mixture (1:9). Prior to filling the sample to its final volume of 1 ml, chloridazone was added as the internal standard at 10 ng ml21. The sample solutions were analyzed with reversed-phase high-performance liquid chromatography with a variable wavelength detector and the results exemplarily confirmed by liquid chromatography coupled to electrospray ionization mass spectrometry. Corresponding to soil analysis, fortification experiments continuously performed revealed limits of determination of 20 mg kg21 dry matter at recoveries of 65 to 90% with relative standard deviations of #13%. RESULTS AND DISCUSSION

The test-plot series were conducted to study runoff of sulfonamides after heavy precipitation events taking varying sitespecific and seasonal parameters into special account. Differences of runoff tendencies from arable and grassland were compared qualitatively. For arable land, the impact of different soil surface structures caused by postharvest stage and cultivator drill remaining throughout the winter period was investigated, too.

Total discharge Heavy precipitation events at test-plot scale were simulated by sprinkler irrigation intensity of 50 mm h21 for 2 h. The comparison of the discharge volumes listed in Table 1 already indicated higher runoff tendencies from the grassland plots. Because the slope was remained at 9.0% in these test-plot series and no soil-tillage measures were carried out on grassland, discharge volumes ranging from 106 to 252 L reflected the impact of seasonally varying soil-water balances affecting infiltration and surface runoff. Thus, the initial soil-moisture contents of topsoil layers in series 1 and 2 were 14.5 and 13.8%, respectively, and the soil moisture was only 6.4% after the dry summer in 2003. After sprinkler irrigation in series 1, 2, and 3, the soil-moisture contents were 22.5, 22.8, and 23.3%, respectively. From arable land, the discharge ranged from 36 to 128 L, revealing the impact of different soil structures caused by soil cultivation varying from series to series as is typical for agricultural farming practice. Comparing the parallel test-plot experiments in series 3, the different discharge volumes could be interpreted only by small-scale variabilities of structure and texture often found in soils. Differences in slopes from 7.7 to 9.0%, however, seemed to be of low relevance.

Runoff of sulfonamides Due to the water solubility of sulfonamides of 8 to 1,500 mg L21 [11], the target compounds predominantly occurred in the aqueous phase. Corresponding to highest discharge volumes, highest amounts of sulfonamides also were released from grassland by surface runoff. In the aqueous phase, the overall emission range was 13.3 to 27.6% given as percentages of sulfonamide residues actually applied with the test slurries onto soil (Table 1). In contrast to the grassland experiments, the release from arable land only was 0.1 to 2.5%. According

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Fig. 1. Discharge and runoff of sulfadiazine (SDZ), sulfadimidine (SDM), and sulfamethoxazole (SMZ) from arable land (plot 1) after test-slurry application on cultivator drill followed by further cultivation and sprinkler irrigation in April 2003 (series 2).

to the variabilities of runoff emissions, no tendencies depending on different slopes or impacts of soil cultivation have been identified. This has been the same for the three sulfonamide analogues applied in different amounts and as mixture or as single component. Despite similar discharge volumes, different runoff emissions occurred in the parallel test-plot experiments of series 2 conducted at same slope and topsoil conditions. They pointed out again that small-scale variabilities of soil structure and texture of the arable land may affect infiltration and runoff. Contrary to this, runoff emissions via suspended-matter phase were of low relevance. Average amounts of only 0.004 and 0.02% of the sulfonamides initially applied were released from arable and grassland, respectively. Higher amounts from grassland plots apparently were caused by the surface runoff of slurry itself indicated by slurry inherent odor of the first runoff samples. The results from these test-plot series were compared to those of Burkhardt et al. [13] (http://www.envirpharma.org), which revealed lower runoff emissions from grassland plots. Loads of sulfadiazine, sulfathiazole, and sulfadimidine applied there only ranged from 0.07 to 0.12%. This possibly could be attributed to a shorter irrigation period (1.5 h) and a lower sprinkler irrigation intensity (30 mm h21). Additionally, application of contaminated pig manure and sprinkler irrigation were interrupted by contact times of 1 to 3 d. During this period, the availability of sulfonamides might be reduced due to the formation of nonextractable residues, as has been shown in laboratory test systems [1]. Particularly, this concentrationdetermining process has been identified as immediately occurring when 14C-labeled sulfadiazine-containing test slurry was applied onto soil [22]. The runoff of sulfonamides was recorded time resolved at 5-to 10-min intervals. Thus, further differences between arable and grassland plots were found. The characteristic discharge and runoff curves from arable land were exemplified for the test plot 1 of series 2 (Fig. 1). The discharge did not change from drop-to-drop to continuous flow until a 60- to 70-min period. Then, discharge volumes and runoff emissions continuously increased, reflecting the potential runoff emissions after high-intensity irrigation. At the end of the sprinkler irrigation, discharges and emissions of sulfonamides rapidly dropped down. A completely different situation was found on the grassland plots. In contrast to the permeable soil surface after cultivation

R. Kreuzig et al.

Fig. 2. Discharge and runoff of sulfadiazine (SDZ), sulfadimidine (SDM), and sulfamethoxazole (SMZ) from grassland after test-slurry application and sprinkler irrigation in April 2003 (series 2).

of the arable land, where irrigation water was infiltrated down to 10- to 15-cm soil depth, the grassland constituted a compacted surface that suppressed the infiltration and promoted the surface runoff. In series 2, the discharge rose steeply within the first 35 min of the irrigation period and remained nearly constant until the end (Fig. 2). Major emissions of sulfonamides appeared in this period, too. Then, they dropped continuously to lowest levels in the postrun period. On average, 4% of the sulfonamides were released during the first 20 min of the sprinkler irrigation. This period represented a 17-mm rainfall, which is revealed as the 10-year mean for Essen, Germany, by the model EXPOSIT (http://www.bba.de/ap/ apppsm/exposit/exposit.htm). Therefore, this realistic worstcase scenario may be considered relevant for a risk assessment for surface water contamination. In series 3, discharge and runoff of sulfadiazine from the grassland plot were found to be different after the dry summer in 2003 (Fig. 3). Both parameters increased directly after the start of sprinkler irrigation and, after 15 and 35 min, respectively, they decreased until the end of the irrigation period. CONCLUSION

Runoff of pesticides from agricultural fields has been identified as an environmentally relevant entry route into headwater streams. However, these experiences cannot be transferred directly to the runoff behavior of veterinary medicines without special consideration of their entry route into soil via contaminated manure. Thus, differences are given for manured arable

Fig. 3. Discharge and runoff of sulfadiazine (SDZ) from grassland after test-slurry application and sprinkler irrigation in September 2003 (series 3).

Test-plot studies on runoff of sulfonamides

and grassland. On arable land, soil cultivation should follow short-dated to the manure application. As shown in the three test-plot studies presented here, runoff emissions of sulfonamides were reduced by this measure. Despite the high-intensity sprinkler irrigation, they did not occur until a 60-min delay. A runoff risk may appear from grassland when the manure application is followed directly by heavy rainfall. Then, the contaminated manure may be washed off superficially and sulfonamides may be released into headwater streams. These test-plot studies further showed that the comparison of results from the experiments conducted in parallel and from series to series revealed wide variabilities caused by variable field conditions. Therefore, further test-plot experiments, including further veterinary medicines, are necessary to identify interfering parameters and to establish runoff emission factors for veterinary pharmaceutical residues from manured soils. Acknowledgement—The authors gratefully acknowledge the Federal Environmental Agency (Berlin, Germany) for the financial support to the research project investigations on runoff of veterinary pharmaceuticals after the application of liquid manures to farmland and grassland (FKZ 202 67 435). Many thanks also go to the Federal Agricultural Research Center ([FAL], Braunschweig, Germany) for the supply of the sprinkler apparatus and the liquid manure, and to M. Aures for language revision. REFERENCES 1. Kreuzig R, Ho¨ltge S. 2004. Investigations on the fate of sulfadiazine in manured soil: Laboratory experiments and test-plot studies. Environ Toxicol Chem 24:771–776. 2. Flury M. 1996. Experimental evidence of transport of pesticides through field soils—a review. J Environ Qual 25:25–45. 3. Blanchard PE, Lerch RN. 2000. Watershed vulnerability to losses of agricultural chemicals: Interactions of chemistry, hydrology, and land use. Environ Sci Technol 34:3315–3322. 4. Schulz R, Liess M. 1999. A field study of the effects of agriculturally derived insecticide input on stream macroinvertebrates dynamics. Aquat Toxicol 46:155–176. 5. Pussemier L, Beernaerts S. 1999. SEPTWA95: A system for the estimation of pesticide emissions to surface and groundwater. In Mohaupt V, Bach M, Kerzmar, S, eds, Pesticide Emissions into Water Bodies—Modeling and Measure. Umweltbundesamt, Berlin, Germany, pp 30–38. 6. Liess M, Schulz R, Liess MH-D, Rother B, Kreuzig R. 1999. Determination of insecticide contamination in agricultural headwater streams. Water Res 33:239–247. 7. European Agency for the Evaluation of Medicinal Products. 1997. Environmental risk assessment for veterinary medicinal products other than GMO-containing and immunological products. EMEA/ CVMP/055/96-FINAL. London, UK.


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8. Kosschorreck J, Koch C, Ro¨nnefahrt I. 2002. Environmental risk assessment of veterinary medicinal products in the EU—a regulatory perspective. Toxicol Lett 131:117–224. 9. Langhammer JP. 1989. Untersuchungen zum Verbleib antimikrobiell wirksamer Arzneistoffe als Ru¨cksta¨nde in Gu¨lle und im landwirtschaftlichen Umfeld. PhD thesis. University of Bonn, Bonn, Germany. 10. Grote M, Schwarze D, Freitag M, Vockel A, Mehlich A. 2002. Antiinfektivaeintra¨ge aus der Tierproduktion in Umweltkompartimente und Nahrungskette. Proceedings, Jahrestagung Um¨ kotoxikologie, Forschung und Entwicklung im weltchemie und O Dienste des Umwelt- und Verbraucherschutzes, Braunschweig, Germany, October 6–8, p 110. 11. Thiele-Bruhn S. 2003. Pharmaceutical antibiotic compounds in soils—a review. J Plant Nutr Soil Sci 166:145–167. 12. Mu¨ller SR, Singer H, Stoob K, Burckhardt M, Hartmann N, Go¨tz Ch, Stamm Ch, Waul Ch. 2003. Occurrence and fate of antibiotics in manure, soil, and water. Mitt Lebensmittelunters Hyg 94:574– 578. 13. Burkhardt M, Stamm C, Waul C, Singer H, Mu¨ller S. 2003. Transport behavior of sulfonamides and tracers after manure application on sloped grassland. Proceedings, Envirpharma Conference, April 14–16, Lyon, France, p 26. 14. Boxall ABA, Blackwall P, Cavallo R, Kay P, Tolls J. 2002. The sorption and transport of a sulphonamide antibiotic in soil systems. Toxicol Lett 131:19–28. 15. Boxall ABA, Fogg LA, Blackwell PA, Kay P, Pemberton E, Croxford A. 2004. Veterinary medicines in the environment. Rev Environ Contam Toxicol 180:1–91. 16. Gawlik BM, Bo F, Kettrup A, Muntau H. 1999. Characterization of the second generation of European reference soils for sorption studies in the framework of chemical testing—part I: Chemical composition and pedological properties. Sci Total Environ 229: 99–107. 17. Kluge G, Embert G. 1996. Das Du¨ngemittelrecht. Landwirtschaftsverlag, Mu¨nster-Hiltrup, Germany. 18. Hassel JM, Richter G. 1992. Ein Vergleich deutscher und schweizerischer Regensimulatoren nach Regenstruktur und kinetischer Energie. Z Pflanzenernaehr Bodenkd 155:185–190. 19. Ko¨rdel W, Klo¨ppel H. 1994. Erfassung des Runoff bei der Anwendung von Pflanzenschutzmitteln. Abschlußbericht zum Forschungsvorhaben FKZ 12605087. Umweltbundesamt, Berlin, Deutschland. 20. Pfeifer T, Tuerk J, Bester K, Spiteller M. 2002. Determination of selected sulfonamide antibiotics and trimethoprim in manure by electrospray and atmospheric pressure chemical ionization tandem mass spectrometry. Rapid Commun Mass Spectrom 16:663– 669. 21. Pietsch J, Ricordel D, Imhof L, Schmidt W, Werner P, Croue JP, Brauch H-J. 1999. Trace analysis of veterinary chemotherapeutic residues in water by high-performance liquid chromatography. Vom Wasser 92:51–59. 22. Kreuzig R, Kullmer C, Matthies B, Ho¨ltge S, Dieckmann H. 2003. Fate and behavior of pharmaceutical residues in soils. Fresenius Environmental Bulletin 12:550–558.