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  • 1
    Call number: AWI G4-95-0109
    Type of Medium: Monograph available for loan
    Pages: xxvi, 293 S. , graph. Darst.
    Note: Contents: Extended Summary. - 1 Introduction. - 2 Susceptibility of Soils to Preferential Flow of Water: A Field Study. - 2.1 Introduction. - 2.2 Materials and Methods. - 2.2.1 Soils. - 2.2.2 Dye Tracer. - 2.2.3 Experimental Design. - 2.2.4 Sprinkling Apparatus. - 2.2.5 Flood Irrigation. - 2.2.6 Analysis of Data. - 2.3 Results and Discussion. - 2.3.1 Infiltration Patterns. - 2.3.2 Maximum Depth of Dye Penetration. - 2.3.3 Effect of Initial Water Content. - 2.3.4 Sprinkling versus Flood Irrigation. - 2.4 Conclusion. - 3 Transport of Herbicides: Experimental Results. - 3.1 Introduction. - 3.2 Materials and Methods. - 3.2.1 Experimental Site. - 3.2.2 Experimental Setup. - 3.2.3 Tracer Experiment. - 3.2.4 Chemical Analysis. - 3.3 Results. - 3.3.1 Water Content and Water Potential. - 3.3.2 Anions and Herbicides. - 3.4 Discussion. - 3.5 Conclusions. - 4 Transport of Herbicides: Modeling of Flow in Sandy Soil. - 4.1 Introduction. - 4.2 Theory. - 4.2.1 Assumptions. - 4.2.2 Model. - 4.2.3 Application. - 4.3 Estimation of Parameters. - 4.4 Results and Discussion. - 4.5 Conclusions. - 5 Transport of Herbicides: Modeling of Flow in Loamy Soil. - 5.1 Introduction. - 5.2 Theory. - 5.2.1 Local Interaction Models. - 5.2.2 Linking Local Interaction Models to DLA. - 5.3 Illustrations. - 5.4 Application to the Tracer Field Experiment. - 5.5 Discussion and Conclusions. - 6 Cooperative Research at University of California, Riverside. - 6.1 Introduction. - 6.2 Linear Transport Models for Adsorbing Solutes. - 6.3 Transport of Bromide, Simazine, and MS-2 Coliphage in a Lysimeter containing undisturbed, unsaturated Soil. - 6.4 Description of Simazine Transport with rate-limited, two-step linear and nonlinear Adsorption. - 6.5 Conclusions. - 7 Conclusions and Recommendations. - 7.1 Conclusions. - 7.2 Recommendations. - APPENDICES. - A Extraction and Analysis of Anions (Chloride and Bromide) from Soil Samples. - A.1 Preface. - A.1.1 General Information. - A.1.2 Guidelines. - A.1.3 Purpose. - A.2 Materials and Methods. - A.2.1 Chemicals. - A.2.2 Extraction of Soil Samples. - A.2.3 Analysis of Anions by HPLC. - B Extraction and Analysis of Triazines (Atrazine and Terbuthylazine) from Soil Samples. - B .1 Preface. - B.1.1 General Information. - B.1.2 Guidelines. - B.1.3 Purpose. - B.2 Materials and Methods. - B.2.1 Chemicals. - B.2.2 Materials. - B.2.3 Extraction of Soil Samples. - B.2.4 Analysis of Pesticides by GC. - B.3 Results. - C Extraction of Triasulfuron from Soil Samples. - C.1 Preface. - C.1.1 General Information. - C.1.2 Guidelines. - C.1.3 Purpose. - C.2 Materials and Methods. - C.2.1 Chemicals. - C.2.2 Materials. - C.2.3 Extraction of Soil Samples. - C.2.4 Analysis of Triasulfuron by Chemoluminescence-immunoassay. - C.2.5 Calculation of concentrations. - C.3 Results. - D Influence of Brilliant Blue FCF on the Adsorption Behavior of Atrazine and Triasulfuron. - D.1 Preface. - D.1.1 General Information. - D.1.2 Guidelines. - D.1.3 Purpose. - D.2 Materials and Methods. - D.2.1 Chemicals. - D.2.2 Apparatus. - D.2.3 Adsorption Experiments. - D.3 Results and Discussion. - E Sprinklingapparatur zur Simulation ungesättigten Stofftransportes in Feldböden. - F Begriffliche Ver(w)irrung: Pflanzenschutzmittel oder Pestizide ; Eine semantische Betrachtung. - G Bromide in the Natural Environment: Occurrence and Toxicity. - H Brilliant Blue FCF as a Dye Tracer for Solute Transport Studies - a Toxicological Overview. - I Tracer Characteristics of Brilliant Blue FCF. - J Glossary of Symbols. - Bibliography.
    Location: AWI Reading room
    Branch Library: AWI Library
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  • 2
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Transport of volatile hydrocarbons in soils is largely controlled by interactions of vapours with the liquid and solid phase. Sorption on solids of gaseous or dissolved compounds may be important. Since the contact time between a chemical and a specific sorption site can be rather short, kinetic or mass-transfer resistance effects may be relevant. An existing mathematical model describing advection and diffusion in the gas phase and diffusional transport from the gaseous phase into an intra-aggregate water phase is modified to include linear kinetic sorption on gas-solid and water-solid interfaces. The model accounts for kinetic mass transfer between all three phases in a soil. The solution of the Laplace-transformed equations is inverted numerically. We performed transient column experiments with 1,1,2-Trichloroethane, Trichloroethylene, and Tetrachloroethylene using air-dry solid and water-saturated porous glass beads. The breakthrough curves were calculated based on independently estimated parameters. The model calculations agree well with experimental data. The different transport behaviour of the three compounds in our system primarily depends on Henry's constants.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2018-07-27
    Description: Streamflow response to precipitation is often investigated using isotope-based hydrograph separation, which quantifies the contribution of precipitation (i.e., event water Qe) or water from storage (i.e., pre-event water Qpe) to total discharge (Q) during storm events. In order to better understand streamflow generating mechanisms, hydrograph separation studies often seek to relate the event water fraction Qe/Q to storm characteristics or antecedent wetness conditions. However, these relationships may be obscured because the same factors that influence Qe also necessarily influence total discharge Q as well. Here we propose that the fractions of event water and pre-event water relative to precipitation instead of discharge (Qe/P and Qpe/P) provide useful alternative tool for studying catchment storm responses. These two quantities separate the well-known runoff coefficient (Q/P, i.e. the ratio between discharge and precipitation over the event time scale) into its contributions from event water and pre-event water. Whereas the runoff coefficient Q/P quantifies how strongly precipitation inputs affect streamflow, the fractions Qe/P and Qpe/P track the sources of this streamflow response. We use high-frequency measurements of stable water isotopes for 24 storm events at a steep headwater catchment (Erlenbach, central Switzerland) to compare the storm-to-storm variations in Qe/Q, Qe/P and Qpe/P. Our analysis explores how storm characteristics and antecedent wetness conditions affect the mobilization of event water and pre-event water at the catchment scale. Isotopic hydrograph separation shows that streamflow was typically dominated by pre-event water, although event water exceeded 50% of discharge for several storms. No clear relationships were found linking either storm characteristics or antecedent wetness conditions with the volumes of event water or pre-event water (Qe, Qpe), or with event water as a fraction of discharge (Qe/Q), beyond the unsurprising correlation of larger storms with greater Qe and greater total Q. By contrast, event water as a fraction of precipitation (Qe/P) was strongly correlated with storm volume and intensity but not with antecedent wetness, implying that the volume of event water that is transmitted to streamflow increases more-than-proportionally with storm size under both wet and dry conditions. Conversely, pre-event water as a fraction of precipitation (Qpe/P) was strongly correlated with all measures of antecedent wetness but not with storm characteristics, implying that wet conditions primarily facilitate the mobilization of old (pre-event) water, rather than the fast transmission of new (event) water to streamflow, even at a catchment where runoff coefficients can be large. Thus, expressing event and pre-event water volumes as fractions of precipitation rather than discharge was more insightful for investigating the Erlenbach catchment's hydrological behaviour. If Qe/P and Qpe/P exhibit similar relationships with storm characteristics and antecedent wetness conditions in other catchments, we suggest that these patterns may potentially be useful as diagnostic fingerprints of catchment storm response.
    Print ISSN: 1812-2108
    Electronic ISSN: 1812-2116
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
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  • 4
    Publication Date: 2018-11-13
    Description: Catchment response to precipitation is often investigated using two-component isotope-based hydrograph separation, which quantifies the contribution of precipitation (i.e., event water Qe) or water from storage (i.e., pre-event water Qpe) to total discharge (Q) during storm events. In order to better understand streamflow-generating mechanisms, two-component hydrograph separation studies often seek to relate the event-water fraction Qe∕Q to storm characteristics or antecedent wetness conditions. However, these relationships may be obscured because the same factors that influence Qe also necessarily influence total discharge Q as well. Here we propose that the fractions of event water and pre-event water relative to total precipitation (Qe∕P and Qpe∕P), instead of total discharge, provide useful alternative tools for studying catchment storm responses. These two quantities separate the well-known runoff coefficient (Q∕P, i.e., the ratio between total discharge and precipitation volumes over the event timescale) into its contributions from event water and pre-event water. Whereas the runoff coefficient Q∕P quantifies how strongly precipitation inputs affect streamflow, the fractions Qe∕P and Qpe∕P track the sources of this streamflow response. We use high-frequency measurements of stable water isotopes for 24 storm events at a steep headwater catchment (Erlenbach, central Switzerland) to compare the storm-to-storm variations in Qe/Q,Qe/P and Qpe∕P. Our analysis explores how storm characteristics and antecedent wetness conditions affect the mobilization of event water and pre-event water at the catchment scale. Isotopic hydrograph separation shows that catchment outflow was typically dominated by pre-event water, although event water exceeded 50% of discharge for several storms. No clear relationships were found linking either storm characteristics or antecedent wetness conditions with the volumes of event water or pre-event water (Qe, Qpe), or with event water as a fraction of discharge (Qe∕Q), beyond the unsurprising correlation of larger storms with greater Qe and greater total Q. By contrast, event water as a fraction of precipitation (Qe∕P) was strongly correlated with storm volume and intensity but not with antecedent wetness, implying that the volume of event water that is transmitted to streamflow increases more than proportionally with storm size under both wet and dry conditions. Conversely, pre-event water as a fraction of precipitation (Qpe∕P) was strongly correlated with all measures of antecedent wetness but not with storm characteristics, implying that wet conditions primarily facilitate the mobilization of old (pre-event) water, rather than the fast transmission of new (event) water to streamflow, even at a catchment where runoff coefficients can be large. Thus, expressing event- and pre-event-water volumes as fractions of precipitation rather than discharge was more insightful for investigating the Erlenbach catchment's hydrological behaviour. If Qe∕P and Qpe∕P exhibit similar relationships with storm characteristics and antecedent wetness conditions in other catchments, we suggest that these patterns may potentially be useful as diagnostic “fingerprints” of catchment storm response.
    Print ISSN: 1027-5606
    Electronic ISSN: 1607-7938
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
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  • 5
    Publication Date: 2017-03-23
    Description: High-frequency measurements of solutes and isotopes (18O and 2H) in rainfall and streamflow can shed important light on catchment flow pathways and travel times, but the workload and sample storage artifacts involved in collecting, transporting, and analyzing thousands of bottled samples severely constrain catchment studies in which conventional sampling methods are employed. However, recent developments towards more compact and robust analyzers have now made it possible to measure chemistry and water isotopes in the field at sub-hourly frequencies over extended periods. Here, we present laboratory and field tests of a membrane-vaporization continuous water sampler coupled to a cavity ring-down spectrometer for real-time measurements of δ18O and δ2H combined with a dual-channel ion chromatograph (IC) for the synchronous analysis of major cations and anions. The precision of the isotope analyzer was typically better than 0.03‰ for δ18O and 0.17‰ for δ2H in 10min average readings taken at intervals of 30min. Carryover effects were less than 1.2% between isotopically contrasting water samples for 30min sampling intervals, and instrument drift could be corrected through periodic analysis of secondary reference standards. The precision of the ion chromatograph was typically  ∼ 0.1–1ppm or better, with relative standard deviations of  ∼ 1% or better for most major ions in stream water, which is sufficient to detect subtle biogeochemical signals in catchment runoff. We installed the coupled isotope analyzer/IC system in an uninsulated hut next to a stream of a small catchment and analyzed stream water and precipitation samples every 30min over 28 days. These high-frequency measurements facilitated a detailed comparison of event-water fractions via endmember mixing analysis with both chemical and isotope tracers. For two events with relatively dry antecedent moisture conditions, the event-water fractions were 〈21% based on isotope tracers but were significantly overestimated (40 to 82%) by the chemical tracers. These observations, coupled with the storm-to-storm patterns in precipitation isotope inputs and the associated stream water isotope response, led to a conceptual hypothesis for runoff generation in the catchment. Under this hypothesis, the pre-event water that is mobilized by precipitation events may, depending on antecedent moisture conditions, be significantly shallower, younger, and less mineralized than the deeper, older water that feeds baseflow and thus defines the pre-event endmember used in hydrograph separation. This proof-of-concept study illustrates the potential advantages of capturing isotopic and hydrochemical behavior at a high frequency over extended periods that span multiple hydrologic events.
    Print ISSN: 1027-5606
    Electronic ISSN: 1607-7938
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
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  • 6
    Publication Date: 2020-05-15
    Description: Studying the response of streamwater chemistry to changes in discharge can provide valuable insights into how catchments store and release water and solutes. Previous studies have determined concentration–discharge (cQ) relationships from long-term, low-frequency data of a wide range of solutes. These analyses, however, provide little insight into the coupling of solute concentrations and flow during individual hydrologic events. Event-scale cQ relationships have rarely been investigated across a wide range of solutes and over extended periods of time, and thus little is known about differences and similarities between event-scale and long-term cQ relationships. Differences between event-scale and long-term cQ behavior may provide useful information about the processes regulating their transport through the landscape. Here we analyze cQ relationships of 14 different solutes, ranging from major ions to trace metals, as well as electrical conductivity, in the Swiss Erlenbach catchment. From a 2-year time series of sub-hourly solute concentration data, we determined 2-year cQ relationships for each solute and compared them to cQ relationships of 30 individual events. The 2-year cQ behavior of groundwater-sourced solutes was representative of their cQ behavior during hydrologic events. Other solutes, however, exhibited very different cQ patterns at the event scale and across 2 consecutive years. This was particularly true for trace metals and atmospheric and/or biologically active solutes, many of which exhibited highly variable cQ behavior from one event to the next. Most of this inter-event variability in cQ behavior could be explained by factors such as catchment wetness, season, event size, input concentrations, and event-water contributions. We present an overview of the processes regulating different groups of solutes, depending on their origin in and pathways through the catchment. Our analysis thus provides insight into controls on solute variations at the hydrologic event scale.
    Print ISSN: 1027-5606
    Electronic ISSN: 1607-7938
    Topics: Geography , Geosciences
    Published by Copernicus on behalf of European Geosciences Union (EGU).
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