INFLUENCE OF NATURAL ORGANIC MATTER ON THE MOBILITY OF ARSENIC IN AQUATIC ...

215 Pages·2008·4.57 MB·English

INFLUENCE OF NATURAL ORGANIC MATTER ON THE MOBILITY
OF ARSENIC IN AQUATIC SYSTEMS, SOILS AND SEDIMENTS

Dissertation zur Erlangung des Grades
Doktor der Naturwissenschaften
(Dr. rer. nat.)
an der Fakultät Biologie/Chemie/Geowissenschaften
der Universität Bayreuth

vorgelegt von

Markus Bauer
Geb. am 01.05.1977 in Ingolstadt

Bayreuth, 23. April 2008

Vollständiger Abdruck der von der Fakultät für Chemie/Biologie/Geowissenschaften
der Universität Bayreuth genehmigten Dissertation zur Erlangung des Grades eines
Doktors der Naturwissenschaften (Dr. rer. nat.).

Prüfungsausschuss:
Prof. Dr. Stefan Peiffer (Vorsitzender)
PD Dr. Christian Blodau (1. Gutachter)
Prof. Dr. Egbert Matzner (2. Gutachter)
Prof. Dr. Hartmut Frank
PD Dr. Bruno Glaser

Tag der Einreichung: 20.04.08
Tag des wissenschaftlichen Kolloquiums: 29.10.08

TABLE OF CONTENTS

TABLE OF CONTENTS
INFLUENCE OF NATURAL ORGANIC MATTER ON THE MOBILITY OF ARSENIC IN
AQUATIC SYSTEMS, SOILS AND SEDIMENTS ............................................................................... I
TABLE OF CONTENTS ..................................................................................................................... I
LIST OF FIGURE ............................................................................................................................. III
LIST OF TABLES ............................................................................................................................. V
SUMMARY ..................................................................................................................................... VII
ZUSAMMENFASSUNG .................................................................................................................. IX
EXTENDED SUMMARY .................................................................................................................. 1
Introduction ......................................................................................................................................... 1
1. Arsenic health concerns ............................................................................................................... 1
2. Arsenic geochemistry and mobility ............................................................................................. 1
3. Natural organic matter ................................................................................................................. 4
4. As mobility in environments rich in organic matter .................................................................... 7
5. Objectives of the dissertation ...................................................................................................... 8
I. Redox Chemistry of DOM and Electron Transfer Reactions with As ........................................... 11
1. DOM oxidation and reduction by inorganic compounds (study 1 and 2) ................................. 12
2. DOM redox reactivity with As (study 3) ................................................................................... 14
Conclusions ................................................................................................................................... 14
II. Aqueous and Surface Complexation Reactions of As and DOM ................................................. 15
1. Complex and colloid formation in solutions with Fe, DOM and As (study 4 and 5) ................ 16
2. Influence of DOM on As binding to mineral surfaces (study 6) ............................................... 18
3. Aqueous and surface complexation reactions and the redox speciation of As .......................... 18
Conclusions ................................................................................................................................... 19
III. Effect of DOM Load on the As Mobilization (study 7) .............................................................. 19
IV. Arsenic Mobility and Retention in Organic Matter Rich Peat Soils ........................................... 21
1. Arsenic in peat mesocosms subject to drying and rewetting (Study 8) ..................................... 22
2. Arsenic in degraded peatland soil (Study 9) .............................................................................. 23
Conclusions ................................................................................................................................... 24
Conclusions and Outlook .................................................................................................................. 26
References ......................................................................................................................................... 29
Contributions to the Different Studies ............................................................................................... 37
APPENDIX ....................................................................................................................................... 41

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TABLE OF CONTENTS

Study 1, APPENDIX 45
Electron Transfer Capacities and Reaction Kinetics of Peat Dissolved Organic Matter

Study 2, APPENDIX 63
Electron Accepting Capacitiy od Dissolved Organic Matter as determined by Reaction with
Metallic Zinc

Study 3, APPENDIX 85
Oxidation of As(III) and Reduction of As(V) in Dissolved Organic Matter Solutions

Study 4, APPENDIX 97
Experimental colloid formation in aqueous solutions rich in dissolved organic matter, ferric
iron, and As

Study 5, APPENDIX 119
Evidence for Aquatic Binding of Arsenate by Natural Organic Matter-Suspended Fe(III)

Study 6, APPENDIX 129
Mobilization of Arsenic by Dissolved Organic Matter from Iron Oxides,Soils and Sediments

Study 7, APPENDIX 143
Mobilization of Iron and Arsenic from Iron Oxide Coated Sand Columns by Percolation with
Dissolved Organic Matter

Study 8, APPENDIX 159
Arsenic Speciation and Turnover in intact Organic Soil Mesocosms during Experimental
Drought and Rewetting

Study 9, APPENDIX 179
Groundwater Derived Arsenic in High Carbonate Wetland Soils: Sources, Sinks, and Mobility

Redox reactions and Redox potentials, APPENDIX 193

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LIST OF FIGURES

LIST OF FIGURE
Page
Figure 1 Extended Summary E -pH diagrams for As 3
h
Figure 2 Extended Summary Schematic structure of a DOM molecule 5
Figure 3 Extended Summary Electron transfer reactions of quinones and DOM 5
Figure 4 Extended Summary Aqueous and surface complexes of As and DOM 7
Figure 5 Extended Summary Interactions of As with DOM and Fe 9
Figure 6 Study 1, Fig. 1 Reduction of Fe(III) complexes by DOM 47
Figure 7 Study 1, Fig. 2 Reduction of Fe(III) vs. DOM concentration 48
Figure 8 Study 1, Fig. 3 Reduction of Fe(III) vs. pH 48
Figure 9 Study 1, Fig. 4 Oxidation of H S and Zn0 by DOM 49
2
Figure 10 Study 1, Fig. 5 Oxidation of H S and Zn0 vs. DOM concentration 49
2
Figure 11 Study 1, Fig. 6 Dependency of ETC and reaction rate constant on E 0 50
h
Figure 12 Support, Study 1 Aqueous Fe speciation as modelled by Phreeqc 55
Figure 13 Support, Study 1 Aqueous Fe speciation as modelled by Phreeqc 56
Figure 14 Support, Study 1 Variability during modelling 58
Figure 15 Support, Study 1 Formation of Fe(II) in DOM solution 59
Figure 16 Study 2 Zn2+, H and H+ turnover in DOM solution 71
2
Figure 17 Study 2 Dependency of Zn release on pH 72
Figure 18 Study 2 Time series of Zn release with different DOM samples 73
Figure 19 Study 2 Zn0 oxidation vs. DOM concentration 73
Figure 20 Study 2 Electron accepting capacity vs. DOM concentration 75
Figure 21 Study 2 Reversibility of DOM electron uptake 75
Figure 22 Study 2 Relation of DOM SUVA and FTIR properties to EAC 76
Figure 23 Study 2 Relation of DOM fluorescence properties to EAC 77
Figure 24 Study 3 Time series of As(III) oxidation by DOM 90
Figure 25 Study 3 As(III) oxidation capacity 91
Figure 26 Study 3 Time series of As(V) reduction by DOM 93
Figure 27 Study 3 As(V) reduction capacity 94
Figure 28 Study 4 Colloid formation assays: Standard procedure and variations 101
Figure 29 Study 4 Results of standard colloid filtration experiments 103
Figure 30 Study 4 Time series of formation of Fe-As-DOM aggregates 104
Figure 31 Study 4 Correlation of As, Fe and DOC in aggregates with PPHA 105
Figure 32 Study 4 Dependency of aggregate formation on pH 106
Figure 33 Study 4 Dependency of aggregate formation on DOC concentration 107
Figure 34 Study 4 Dependency of aggregate formation on Fe/C ratio 111
Figure 35 Study 4 Filtration results vs. WINHUMIC model calculations 110

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LIST OF FIGURES

Page
Figure 36 Support, Study 4 Formation of Fe-As-DOM aggregates with SRDOM 118
Figure 37 Study 5, Fig. 1 Arsenic dialysis experiments without DOM and with SRHPOA 123
Figure 38 Study 5, Fig. 2 Arsenic dialysis experiments with EGFA and SRWW 124
Figure 39 Study 5, Fig. 3 Arsenic mass balance during dialysis experiments 124
Figure 40 Study 5, Fig. 4 DOC and Fe mass balance in dialysis experiments 125
Figure 41 Study 5, Fig. 5 Arsenic complexation dependency on Fe concentration 126
Figure 42 Study 6, Fig. 1 Aqueous As speciation in DOM solution 134
Figure 43 Study 6, Fig. 2 Arsenic sorption on goethite 134
Figure 44 Study 6, Fig. 3 Arsenic desorption from goethite 135
Figure 45 Study 6, Fig. 4 Arsenic desorption by DOM from soil and sediment 137
Figure 46 Study 6, Fig. 5 Time series of As mobilization and speciation 137
Figure 47 Study 7 Breakthrough of chloride and pH in column experiments 148
Figure 48 Study 7 Column effluent concentrations of Fe, As and S 150
Figure 49 Study 7 Dynamics of Fe, S and As within the column 151
Figure 50 Study 7 Column solid phase Fe, S and As content 152
Figure 51 Study 8 Solid phase As and Fe distribution in peat material 164
Figure 52 Study 8 Gas content in the peat cores during drying and rewetting 166
Figure 53 Study 8 Root activity in the peat cores as determined by d13C of CO 166
2
Figure 54 Study 8 Aqueous depth profiles of Fe, S, DOC, and pH 167
Figure 55 Study 8 Temporal dynamics of dissolved As in the peat cores 168
Figure 56 Study 8 Arsenic speciation at the beginning of the drying period 169
Figure 57 Study 8 Temporal dynamics of the As(III) to As(V) ratio 169
Figure 58 Study 8 Temporal dynamics of DMA concentration 170
Figure 59 Study 8 Redox potential values calculated from As, Fe and S couples 170
Figure 60 Study 8 Turnover rates calculated for As and Fe 171
Figure 61 Support, Study 8 Time series of water levels during drying and rewetting 177
Figure 62 Study 9 Aqueous concentration profiles of As, Fe and DOC 183
Figure 63 Study 9 Soil horizon XRD spectra 184
Figure 64 Study 9 Soil content of As, Fe and C in different pools 186
Figure 65 Study 9 Arsenic mobilization by soil organic carbon dispersion 187
Figure 66 Support, Study 9 Setup of the Stella transport model 192
Figure 67 Support, Study 9 Measured and modelled depth profile of As and Cl- 192

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LIST OF TABLES

LIST OF TABLES
Page
Table 1 Study 1, Tab. 1 DOM oxidation and reduction experiments 46
Table 2 Support, Study 1 Properties of DOM samples 52
Table 3 Support, Study 1 List of critical stability constants 54
Table 4 Support, Study 1 Thermodynamic calculations 57
Table 5 Support, Study 1 Literature review of EAC and EDC values 60
Table 6 Study 2 Properties of DOM samples 66
Table 7 Study 3 Experiments of As oxidation and reduction by DOM 88
Table 8 Study 3 Thermodynamic calculations 89
Table 9 Study 4 Complexation and colloid formation experiments 101
Table 10 Study 4 Properties of DOM samples 103
Table 11 Study 4 Fe, DOC and As concentrations in different size fractions 108
Table 12 Study 5, Tab. 1 Properties of DOM samples 121
Table 13 Study 5, Tab. 2 Inorganic constituents of DOM solution 121
Table 14 Study 5, Tab. 3 Results of sequential filtration experiments 126
Table 15 Study 6, Tab. 1 Arsenic sorption and desorption experiments from iron oxide 136
Table 16 Study 6, Tab. 2 Characteristics of soil and sediment samples 138
Table 17 Study 6, Tab. 3 Arsenic content in soil and sediment pools 138
Table 18 Study 7 Column hydraulic characteristics 149
Table 19 Study 7 Mass balances for Fe, S, As and C in column experiments 152
Table 20 Study 8 Solid phase Fe, Al and TRIS content 165
Table 21 Study 8 Correlation of As content with major soil constituents 165
Table 22 Support, Study 8 Solid phase elemental content 178
Table 23 Study 9 Applied extraction procedures 182
Table 24 Study 9 Physical and chemical properties of soil horizons 185
Table 25 Study 9 Solid phase Ca, Fe and As content in soil mineral pools 185
Table 26 Appendix 10 Summary of thermodynamic calculations 194/195

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LIST OF TABLES

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