LIST OF CONTENTS .............................................. VII
LIST OF CONTENTS .............................................. VII
LIST OF ABBREVIATIONS ........................................... X
SUMMARY ...................................................... XIII
ZUSAMMENFASSUNG ................................................ XV
1 INTRODUCTION ................................................. 1
2 STATE OF THE ART ............................................. 3
2.1 Complexity of the soil system ........................... 3
2.2 Microbial activity in the soil .......................... 6
2.2.1 Natural organic compounds biodegradation in
soil ............................................. 9
2.2.2 Anthropogenic organic compounds biodegradation
in soil ......................................... 10
2.3 Bioavailability of organic contaminants in soil ........ 11
2.4 Definition of the non-extractable residues (NER) ....... 14
2.5 Determination of NER in soil ........................... 15
2.6 Formation of NER in soil ............................... 16
2.6.1 Parent compounds and metabolites ................ 17
2.6.2 Components of microbial biomass (Fatty acids
and amino acids) ................................ 19
2.7 Stability of NER in soil ............................... 23
2.8 Risk assessment of NER ................................. 25
3 AIMS OF THE STUDY ........................................... 29
4 MODEL COMPOUNDS ............................................. 31
4.1 2,4-Dichlorophenoxyacetic acid (2,4-D) ................. 31
4.2 Ibuprofen (Ibu) ........................................ 34
5 MATERIAL AND METHODS ........................................ 37
5.1 Chemicals and materials ................................ 37
5.2 Liquid culture experiments ............................. 38
5.2.1 Strain .......................................... 38
5.2.2 Medium .......................................... 39
5.2.3 Preculture incubation ........................... 39
5.2.4 Incubation experiment with 13C6-2,4-D ............ 40
5.2.5 Incubation experiment under 13CO2 atmosphere ..... 41
5.3 Soil experiments ....................................... 42
5.3.1 Soil ............................................ 43
5.3.2 Incubation experiment ........................... 43
5.3.3 Soil incubation experiment with 13C6-2,4-D ....... 44
5.3.4 Soil incubation experiment under 13СО2
atmosphere ...................................... 44
5.3.5 Soil incubation experiment with 13С6-ibu ......... 45
5.4 Chemical analyses ...................................... 45
5.4.1 CO2 measurement ................................. 46
5.4.2 Parent compound and metabolites measurement ..... 46
5.4.3 Total biomass and NER measurement ............... 47
5.4.4 Fatty acids (FA) analyses ....................... 48
5.4.5 Amino acids (AA) analyses ....................... 50
5.5 Data analyses .......................................... 52
6 RESULTS ..................................................... 53
6.1 Liquid culture experiments ............................. 53
6.1.1 Incubation experiment with 13С6-2,4-D ............ 53
6.1.1.1 Mass balance of 13C6-2,4-D in the
system ................................. 54
6.1.1.2 Incorporation of 13C into PLFA of С
necator JMP 134 grown on 13С6-2,4-D ..... 56
6.1.1.3 Incorporation of 13С into AA of C.
necator JMP 134 grown on 13С6-2,4-D ..... 56
6.1.2 Incubation experiment under 13СO2 atmosphere ..... 57
6.1.2.1 Incorporation of 13С into biomass of
C. necator JMP 134 grown under 13СO2 .... 58
6.1.2.2 Incorporation of 13С into PLFA of C.
necator JMP 134 grown under 13СO2 ....... 59
6.1.2.3 Incorporation of 13С into AA of C.
necator JMP 134 grown under 13СO2 ....... 60
6.2 Soil experiments ....................................... 60
6.2.1 Soil incubation experiment with 13С6-2,4-D ....... 61
6.2.1.1 Mass balance of 13С6-2,4-D in the
soil ................................... 61
6.2.1.2 Formation of FA and their fate in
soil incubated with 13С6-2,4-D .......... 62
6.2.1.3 Formation of AA and their fate in
soil incubated with 13С6-2,4-D .......... 66
6.2.1.4 Biogenic residues in soil incubated
with 13С6-2,4-D ......................... 68
6.2.2 Soil incubation experiment under 13СO2
atmosphere ...................................... 68
6.2.2.1 Formation of FA and their fate in soil
incubated under 13СO2 .atmosphere ........ 68
6.2.3 Soil incubation experiment 13С6-ibu .............. 71
6.2.3.1 Mass balance of 13С6-ibu in the
soil ................................... 71
6.2.3.2 Formation of FA and their fate in
soil incubated with 13С6-ibu ............ 72
6.2.3.3 Formation of AA and their fate in
soil incubated with 13С6-ibu ............ 76
6.2.3.4 Biogenic residues in soil incubated
with 13С6-ibu ........................... 78
7 DISCUSSION .................................................. 79
7.1 Liquid culture experiments ............................. 79
Incorporation of 13С into biomass of C. necator
JMP 134 grown on 2,4-D medium
7.2 Soil experiments ....................................... 83
7.2.1 Soil incubation experiment with 13С6-2,4-D ....... 83
7.2.1.1 Biogenic residues as NER in soil
incubated with 13С6-2,4-D ............... 83
7.2.1.2 Fate and stability of FA in soil
incubated with 13С6-2,4-D ............... 86
7.2.1.3 Fate and stability of AA in soil
incubated with 13С6-2,4-D ............... 87
7.2.2 Soil incubation experiment with 13С6-ibu ......... 89
7.2.2.1 Biogenic residues as NER in soil
incubated with 13С6-ibu ................. 89
7.2.2.2 Fate and stability of FA in soil
incubated with 13С6-ibu ................. 91
7.2.2.3 Fate and stability of AA in soil
incubated with 13С6-ibu ................. 92
8 CONCLUSIONS ................................................. 95
LITERATURE ..................................................... 99
ACKNOWLEDGEMENTS .............................................. 115
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