Losses of Nitrogen from Some Flooded Soils in Tracer Experiments

A numerical analysis of solute transport in two spatially heterogeneous fields is carried out assuming that the fields are composed of ensembles of one-dimensional non-interacting soil columns, each column representing a possible soil profile in statistical terms. The basis for the analysis is the flow simulation described in Part II (Jensen and Refsgaard, this issue), which serves as input to a transport model based on the convection-dispersion equation. The simulations of the average and variation in solute concentration in planes perpendicular to the flow direction are compared to measurements obtained from tracer experiments carried out at the two fields. Due to the limited amount of measurement data, it is difficult to draw conclusive evidence of the simulations, but reliable simulations are obtained of the mean behaviour within the two fields. The concept of equivalent soil properties is also tested for the transport problem in heterogeneous soils. Based on effective parameters for the retention and hydraulic conductivity functions it is possible to predict the mean transport in the two experimental fields.

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New Method for Estimation of Contaminant Travel Rate in Unsaturated Zone under Irrigated Soils

Water Science & Technology ◽

10.2166/wst.1993.0549 ◽

1993 ◽

Vol 27 (7-8) ◽

pp. 173-178 ◽

Cited By ~ 4

Author(s):

M. Zilberbrand

Keyword(s):

Water Content ◽

Unsaturated Zone ◽

Sandy Loam ◽

Chestnut Soil ◽

Deep Penetration ◽

Groundwater Recharge Rate ◽

Capillary Tension ◽

Travel Rate ◽

Tracer Experiments ◽

Irrigated Soils

In a thick unsaturated zone, when quick deep penetration of rain and irrigation water is absent, at the depths below 3-5 m there exists a zone of downwards quasi-steady water flow. Darcy's water velocity in this zone remains constant with depth and equal to the groundwater recharge rate; unit hydraulic head gradient occurs above the capillary fringe. Therefore, contaminant travel rate is equal to the ratio of hydraulic conductivity (K) and effective volumetric water content (θef). Field tracer experiments and laboratory K and θef determinations were carried out for several representative irrigated lots in the South Ukraine. The dependence of θef on capillary tension was studied for the first time. For loess loam with a capillary tension decreasing from 46 kPa to 0, θef nonlinearly increases from 12% to 27-28%. The effective water content portion (β1) of the total water content increases nonlinearly from 0.38 to 0.65-0.7. The β1 values were estimated for different unsaturated sedimentary rocks. For a capillary tension of about 5 kPa β1 values were: 0.88-0.99 for sands, about 0.65 for loess loam and chestnut soil, about 0.6 for sandy loam, about 0.32 for limestone and about 0.07 for clay. Calculated chloride travel rates in loess loams under irrigated soils fit the values of 0.001-0.003 m/day, determined by the results of field tracer experiments.

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Studies on Sporopollenin Biosynthesis in Cucurbita maxima I: The Substantial Labeling of Sporopollenin from Cucurbita maxima after Application of [14C]Phenylalanine

Zeitschrift für Naturforschung C ◽

10.1515/znc-1993-1-203 ◽

1993 ◽

Vol 48 (1-2) ◽

pp. 10-15 ◽

Cited By ~ 7

Author(s):

Sabine Gubatz ◽

Rolf Wiermann

Keyword(s):

Terephthalic Acid ◽

Phthalic Acid ◽

Degradation Products ◽

Hydroxybenzoic Acid ◽

Cucurbita Maxima ◽

Purification Step ◽

Decanedioic Acid ◽

Octanedioic Acid ◽

High Level ◽

Tracer Experiments

The results of tracer experiments performed with anthers of Tulipa cv. Apeldoorn have already shown that a high level of incorporation into the sporopollenin fraction was achieved, when [14C]phenylalanine was applicated as a precursor. In order to investigate whether the substantial incorporation of [14C]phenylalanine is a unique phenomenon restricted to Tulipa, tracer experiments were carried out on anthers of Cucurbita maxima. The sporopollenin fraction was isolated and purified by a gentle method including extractions with various solvents, incubations with hydrolysing enzymes and fractionated saponifications. The remaining, as well as the released radioactivity, was determined after each purification step. After the application of [U-14C]phenylalanine, a substantial incorporation into the sporopollenin fraction was determined. The values were clearly higher than those obtained with [1-14C]glucose or those from corresponding experiments on Tulipa anthers. After potash fusion of sporopollenin fractions labeled via [U-14C]phenylalanine, p-hydroxybenzoic acid was shown to be the main com ponent among the ether soluble acids; moreover it showed the highest level of radioactivity. No radioactivity was detected in the degradation products oxalic acid, benzoic acid, phthalic acid and terephthalic acid or octanedioic acid- and decanedioic acid-dimethylester.

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TRACER EXPERIMENTS ON THE MECHANISM OF URIC ACID DECOMPOSITION AND ACETIC ACID SYNTHESIS BY CLOSTRIDIUM ACIDI-URICI

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)56908-8 ◽

1949 ◽

Vol 178 (2) ◽

pp. 891-902

Author(s):

J.L. Karlsson ◽

H.A. Barker

Keyword(s):

Acetic Acid ◽

Uric Acid ◽

Acid Synthesis ◽

Acid Decomposition ◽

Tracer Experiments

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Tracer experiments in saturated sand by computed tomography and inductively coupled plasma

International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts ◽

10.1016/0148-9062(93)90342-b ◽

1993 ◽

Vol 30 (1) ◽

pp. A22

Keyword(s):

Computed Tomography ◽

Inductively Coupled Plasma ◽

Saturated Sand ◽

Inductively Coupled ◽

Tracer Experiments

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Short term variations of tracer transit speed on alpine glaciers

The Cryosphere ◽

10.5194/tc-4-381-2010 ◽

2010 ◽

Vol 4 (3) ◽

pp. 381-396 ◽

Cited By ~ 16

Author(s):

M. A. Werder ◽

T. V. Schuler ◽

M. Funk

Keyword(s):

Drainage System ◽

Relative Importance ◽

Short Term ◽

Diurnal Variability ◽

Alpine Glacier ◽

Two Component ◽

Transit Speed ◽

Underlying Processes ◽

Diurnal Maximum ◽

Tracer Experiments

Abstract. We first present the results of a series of tracer experiments conducted on an alpine glacier (Gornergletscher, Switzerland) over a diurnal discharge cycle. For these injections, a moulin was used into which an ice marginal lake was draining, providing a relatively constant discharge. The measured tracer transit speeds show two diurnal maxima and minima. These findings are qualitatively different to existing observations from two series of injections conducted at Unteraargletscher (Switzerland) using a moulin fed by supraglacial meltwater having a high diurnal variability, which displayed one diurnal maximum and minimum. We then develop and use a simple two-component model of the glacier drainage system, comprising a moulin and a channel element, to simulate the measured transit speeds for all three injection series. The model successfully reproduces all the observations and shows that the same underlying processes can produce the qualitatively different behaviour depending on the different moulin input discharge regimes. Using the model, we assess the relative importance of the different measurement quantities, show that frequent measurements of moulin input discharge are indispensable and propose an experiment design to monitor the development of the drainage system over several weeks.

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