Summary ...................................................... viii
Zusammenfassung ................................................. x
1 Introduction ................................................. 1
1.1 Registration and environmental risk assessment of
chemicals ............................................... 1
1.2 Degradation of chemicals in the environment ............. 2
1.2.1 Abiotic degradation .............................. 3
1.2.2 Biodegradation ................................... 4
1.2.2.1 Biodegradation in aqueous systems ....... 6
1.2.2.2 The soil environment .................... 6
1.2.2.3 Bioavailability, biodegradation and
toxicity ............................... 10
1.2.2.4 Microbial degradation in soil .......... 14
1.2.2.5 Non-extractable residues ............... 16
1.3 Comparison of biodegradation in water and soil ......... 18
1.4 Aims of the study ...................................... 22
1.5 Model compounds ........................................ 23
1.5.1 2,4-dichlorphenoxyacetic acid (2,4-D) ........... 24
1.5.2 Pharmaceuticals ................................. 25
1.5.2.1 Ibuprofen .............................. 26
1.5.2.2 Ciprofloxacin .......................... 28
2 Materials and methods ....................................... 32
2.1 Chemicals and materials ................................ 32
2.2 Incubations in aqueous media ........................... 33
2.2.1 Mineral medium .................................. 33
2.2.2 Experimental setup .............................. 33
2.3 Soil incubation experiments ............................ 35
2.3.1 Soil ............................................ 35
2.3.2 Experimental setup .............................. 36
2.4 Mass balance and analytical procedures ................. 37
2.4.1 Mineralisation .................................. 38
2.4.2 Label in MM and in suspended solids (SS) ........ 39
2.4.3 Extractable residues in soil .................... 39
2.4.4 Non-extractable residues in soil ................ 41
2.4.5 Chemical analyses ............................... 41
2.4.5.1 2,4-D and ibuprofen determination and
their metabolites ...................... 41
2.4.5.2 Ciprofloxacin determination and its
metabolites ............................ 42
2.5 Inhibition of microorganisms by ciprofloxacin .......... 44
2.5.1 Inhibition study in pure culture ................ 45
2.5.2 Inhibition studies in soil ...................... 46
2.6 Data analyses and statistics ........................... 47
3 Results ..................................................... 49
3.1 Biodegradation of 2,4-D ................................ 49
3.1.1 Aqueous media (OECD 30IB test) .................. 49
3.1.2 Soil (OECD 307 test) ............................ 51
3.2 Biodegradation of ibuprofen ............................ 55
3.2.1 Aqueous media (OECD 30IB test) .................. 55
3.2.2 Soil (OECD 307 test) ............................ 58
3.3 Biodegradation of ciprofloxacin ........................ 62
3.3.1 Aqueous media (OECD 301B test) .................. 62
3.3.2 Soil (OECD 307 test) ............................ 64
3.3.2.1 Mass balance and metabolite
identification ......................... 64
3.3.2.2 Sorption of ciprofloxacin .............. 68
3.3.3 Toxicity studies of ciprofloxacin ............... 69
3.3.3.1 Effects on activated sludge and soil
microbiota ............................. 69
3.3.3.2 EC50 for bacteria (Pseudomonas
putida) ................................ 74
3.3.3.3 Induction of antibiotic resistance in
soil ................................... 75
4 Discussion .................................................. 77
4.1 Biodegradation of 2,4-D in aqueous medium and soil ..... 77
4.2 Biodegradation of ibuprofen in aqueous medium and
soil ................................................... 79
4.3 Biodegradation of ciprofloxacin in aqueous medium and
soil ................................................... 81
4.4 Toxicity of ciprofloxacin and bioavailability .......... 84
4.5 Implications of fluorquinolone contamination for
human health and human related activities .............. 87
4.6 General rules for prediction of biodegradation in
soil ................................................... 88
4.7 New concept for assessment of non-extractable
residues ............................................... 91
Conclusions .................................................... 94
Abbreviations .................................................. 98
Figures ....................................................... 101
Tables ........................................................ 104
Bibliography .................................................. 105
Acknowledgements .............................................. 126
Declaration of Authorship (in German) ......................... 127
Curriculum Vitae .............................................. 128
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