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  • 1
    Language: English
    In: Journal of Contaminant Hydrology, 2015, Vol.177-178, p.30(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jconhyd.2015.02.006 Byline: Irina Engelhardt, Stephan Sittig, Jirka A imA[macron]nek, Joost Groeneweg, Thomas Putz, Harry Vereecken Abstract: Based on small-scale laboratory and field-scale lysimeter experiments, the sorption and biodegradation of sulfonamide sulfadiazine (SDZ) were investigated in unsaturated sandy and silty-clay soils. Sorption and biodegradation were low in the laboratory, while the highest leaching rates were observed when SDZ was mixed with manure. The leaching rate decreased when SDZ was mixed with pure water, and was smallest with the highest SDZ concentrations. In the laboratory, three transformation products (TPs) developed after an initial lag phase. However, the amount of TPs was different for different mixing-scenarios. The TP 2-aminopyrimidine was not observed in the laboratory, but was the most prevalent TP at the field scale. Sorption was within the same range at the laboratory and field scales. However, distinctive differences occurred with respect to biodegradation, which was higher in the field lysimeters than at the laboratory scale. While the silty-clay soil favored sorption of SDZ, the sandy, and thus highly permeable, soil was characterized by short half-lives and thus a quick biodegradation of SDZ. For 2-aminopyrimidine, half-lives of only a few days were observed. Increased field-scale biodegradation in the sandy soil resulted from a higher water and air permeability that enhanced oxygen transport and limited oxygen depletion. Furthermore, low pH was more important than the organic matter and clay content for increasing the biodegradation of SDZ. A numerical analysis of breakthrough curves of bromide, SDZ, and its TPs showed that preferential flow pathways strongly affected the solute transport within shallow parts of the soil profile at the field scale. However, this effect was reduced in deeper parts of the soil profile. Due to high field-scale biodegradation in several layers of both soils, neither SDZ nor 2-aminopyrimidine was detected in the discharge of the lysimeter at a depth of 1m. Synthetic 50year long simulations, which considered the application of manure with SDZ for general agricultural practices in Germany and humid climate conditions, showed that the concentration of SDZ decreased below 0.1[mu]g/L in both soils below the depth of 50cm. Article History: Received 1 October 2014; Revised 12 February 2015; Accepted 25 February 2015
    Keywords: Clay Soils – Analysis ; Biodegradation – Analysis ; Permeability – Analysis ; Sulfadiazine – Analysis
    ISSN: 0169-7722
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Journal of Contaminant Hydrology, June 2015, Vol.177-178, pp.30-42
    Description: Based on small-scale laboratory and field-scale lysimeter experiments, the sorption and biodegradation of sulfonamide sulfadiazine (SDZ) were investigated in unsaturated sandy and silty-clay soils. Sorption and biodegradation were low in the laboratory, while the highest leaching rates were observed when SDZ was mixed with manure. The leaching rate decreased when SDZ was mixed with pure water, and was smallest with the highest SDZ concentrations. In the laboratory, three transformation products (TPs) developed after an initial lag phase. However, the amount of TPs was different for different mixing-scenarios. The TP 2-aminopyrimidine was not observed in the laboratory, but was the most prevalent TP at the field scale. Sorption was within the same range at the laboratory and field scales. However, distinctive differences occurred with respect to biodegradation, which was higher in the field lysimeters than at the laboratory scale. While the silty-clay soil favored sorption of SDZ, the sandy, and thus highly permeable, soil was characterized by short half-lives and thus a quick biodegradation of SDZ. For 2-aminopyrimidine, half-lives of only a few days were observed. Increased field-scale biodegradation in the sandy soil resulted from a higher water and air permeability that enhanced oxygen transport and limited oxygen depletion. Furthermore, low pH was more important than the organic matter and clay content for increasing the biodegradation of SDZ. A numerical analysis of breakthrough curves of bromide, SDZ, and its TPs showed that preferential flow pathways strongly affected the solute transport within shallow parts of the soil profile at the field scale. However, this effect was reduced in deeper parts of the soil profile. Due to high field-scale biodegradation in several layers of both soils, neither SDZ nor 2-aminopyrimidine was detected in the discharge of the lysimeter at a depth of 1 m. Synthetic 50 year long simulations, which considered the application of manure with SDZ for general agricultural practices in Germany and humid climate conditions, showed that the concentration of SDZ decreased below 0.1 μg/L in both soils below the depth of 50 cm.
    Keywords: Sulfonamides ; Sulfadiazine ; Manure ; Hydrus ; Lysimeter ; Dual-Permeability Model ; Engineering ; Environmental Sciences ; Geography
    ISSN: 0169-7722
    E-ISSN: 1873-6009
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  • 3
    Language: English
    In: Journal of Contaminant Hydrology, 2002, Vol.54(1), pp.141-171
    Description: The local scale dispersion tensor, D (sub d) , is a controlling parameter for the dilution of concentrations in a solute plume that is displaced by groundwater flow in a heterogeneous aquifer. In this paper, we estimate the local scale dispersion from time series or breakthrough curves, BTCs, of Br (super -) concentrations that were measured at several points in a fluvial aquifer during a natural gradient tracer test at Krauthausen. Locally measured BTCs were characterized by equivalent convection dispersion parameters: equivalent velocity, v (sub eq) (x) and expected equivalent dispersivity, {lambda (sub eq) (xchi )}. A Lagrangian framework was used to approximately predict these equivalent parameters in terms of the spatial covariance of log (sub e) transformed conductivity and the local scale dispersion coefficient. The approximate Lagrangian theory illustrates that {lambda (sub eq) (chi )} increases with increasing travel distance and is much larger than the local scale dispersivity, lambda (sub d) . A sensitivity analysis indicates that {lambda (sub eq) (chi )} is predominantly determined by the transverse component of the local scale dispersion and by the correlation scale of the hydraulic conductivity in the transverse to flow direction whereas it is relatively insensitive to the longitudinal component of the local scale dispersion. By comparing predicted {lambda (sub eq) (chi )} for a range of D (sub d) values with {lambda (sub eq) (chi )} obtained from locally measured BTCs, the transverse component of D (sub d) , D (sub dT) , was estimated. The estimated transverse local scale dispersivity, lambda (sub dT) = D (sub dT) /U (sub 1) (U (sub 1) = mean advection velocity) is in the order of 10 (super 1) -10 (super 2) mm, which is relatively large but realistic for the fluvial gravel sediments at Krauthausen.
    Keywords: Heterogeneous Aquifers ; Dilution ; Breakthrough Curves ; Dispersion ; Engineering ; Environmental Sciences ; Geography
    ISSN: 0169-7722
    E-ISSN: 1873-6009
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  • 4
    Language: English
    In: Journal of Contaminant Hydrology, 2007, Vol.89(1), pp.107-135
    Description: Antibiotics, such as sulfadiazine, reach agricultural soils directly through manure of grazing livestock or indirectly through the spreading of manure or sewage sludge on the field. Knowledge about the fate of antibiotics in soils is crucial for assessing the environmental risk of these compounds, including possible transport to the groundwater. Transport of C-labelled sulfadiazine was investigated in disturbed soil columns at a constant flow rate of 0.26 cm h near saturation. Sulfadiazine was applied in different concentrations for either a short or a long pulse duration. Breakthrough curves of sulfadiazine and the non-reactive tracer chloride were measured. At the end of the leaching period the soil concentration profiles were determined. The peak maxima of the breakthrough curves were delayed by a factor of 2 to 5 compared to chloride and the decreasing limbs are characterized by an extended tailing. However, the maximum relative concentrations differed as well as the eluted mass fractions, ranging from 18 to 83% after 500 h of leaching. To identify relevant sorption processes, breakthrough curves of sulfadiazine were fitted with a convective–dispersive transport model, considering different sorption concepts with one, two and three sorption sites. Breakthrough curves can be fitted best with a three-site sorption model, which includes two reversible kinetic and one irreversible sorption site. However, the simulated soil concentration profiles did not match the observations for all of the used models. Despite this incomplete process description, the obtained results have implications for the transport behavior of sulfadiazine in the field. Its leaching may be enhanced if it is frequently applied at higher concentrations.
    Keywords: Sulfadiazine Transport ; Antibiotics ; Soil Column ; Breakthrough Curve ; Transport Models ; Sorption Models ; Engineering ; Environmental Sciences ; Geography
    ISSN: 0169-7722
    E-ISSN: 1873-6009
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  • 5
    Language: English
    In: Journal of Contaminant Hydrology, 1999, Vol.36(1), pp.31-52
    Description: The spatial variability of the Kf and n parameters of the Freundlich sorption isotherm for atrazine and their correlation with soil textural variables, cation exchange capacity and organic carbon content were studied in a stagnic podzoluvisol. Ninety-three sample points were organized on an irregular three-dimensional grid to a depth of 3.2 m. A trend in the vertical direction explains, for most variables, about 85% of the observed variance. This trend also significantly influences the observed correlation structure between the variables. The horizontal and vertical trends were removed from the data set with the median polish algorithm. The residuals resulting from this technique obey the intrinsic hypothesis. Organic carbon content, cation exchange capacity and n revealed spatial structure. The estimated correlation length scales in the vertical direction were between 0.63-0.81 m for n and the organic carbon content, and between 0.25-0.40 m for the cation exchange capacity. The variograms of sand, loam, clay and Kf exhibited pure nugget. The correlation structures between the variables differ for different spatial increments. Variables appeared correlated at small spatial increments whereas they are not correlated if the spatial location of the sample points is neglected. ; Includes references ; p. 31-52.
    Keywords: Multivariate Geostatistics ; Hydrology ; Stochastic Processes ; Transport ; Sorption ; Median Polish ; Engineering ; Environmental Sciences ; Geography
    ISSN: 0169-7722
    E-ISSN: 1873-6009
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