Caractéristiques isotopiques (18O, 13CO2, 3H) des écoulements dans une tourbière sur pergélisol au Nouveau-Québec

1982 ◽  
Vol 19 (6) ◽  
pp. 1255-1263 ◽  
Author(s):  
Laurent Dever ◽  
Michelle Laithier ◽  
Claude Hillaire-Marcel
Keyword(s):  
Organic Matter ◽  
Water Flow ◽  
Residence Time ◽  
Lag Time ◽  
Temperature Relationship ◽  
Mean Annual Temperature ◽  
Hydraulic Characteristics ◽  
A Value ◽  
Winter Snow

The 18O – mean annual temperature relationship, which is known in organic matter, presents some anomalies in Sphagnum. A study of water flow and isotopic characteristics of an arctic mire (Leaf River, Ungava Peninsula) has been undertaken to explain these anomalies. The isotopic compositions of the water (18O, 13CO2, 3H) permit the determination of some hydraulic characteristics of a peat on permafrost: (1) evaluation of the lag time between a rainfall and the discharge; (2) evaluation of the residence time of the water; and (3) subsequent mixing parts. A relationship between the isotopic characteristics and the ombrotrophic or minerotrophic nature of the mire is observed. A δ18O value of −11‰ appears in the ombrotrophic zone and a value of −17‰ in the minerotrophic zone. The relative enrichment in 18O of the first one indicates a shorter residence time. The isotopic changes subsequent to rainfalls (with δ18O = −12.2, −14.5, and −19.1‰ differ in time and space: (1) a 2‰ change is observed within 24 h in the minerotrophic zone; (2) a 6‰ change appears almost instantaneously in the ombrotrophic zone. 3H values indicate that neither the meltwater from winter snow (with low 3H content), nor the meltwater from permafrost participates in the subsurface flow.

scholarly journals A colony count model for the control of drinking water distribution systems

2005 ◽  
Vol 9 (2) ◽  
pp. 189-205
Author(s):  
A. Kerneis ◽  
A. Déguin ◽  
M. Feinberg
Keyword(s):  
Organic Matter ◽  
Process Control ◽  
Residence Time ◽  
Distribution Systems ◽  
Control Parameter ◽  
Control Parameters ◽  
Supply Water ◽  
Biodegradable Organic Matter

The purpose of this study is to select a process control parameter for monitoring microbial regrowth in a network and to develop a more accurate and relevant quality control of supply water. Two parameters were examined as potential process control parameters: the water residence time in the network and the concentration of biodegradable organic matter. Residence time calculations were carried out and validated by tracer studies in a branched network and then in a simply looped network. The measurement of the natural dissolved organic carbon (DOC) consumption in the network was preferred to the determination of any in vitro biodegradation. The measurement of consumption requires the determination of DOC in treated water and in supply water. It is simpler and less expensive than other biodegradable organic matter determinations. A model for colony counts as a function of the residence time was developed in order to demonstrate that this parameter can be used for process controlling. This model was very well adjusted to data collected in a network in winter, spring and summer. This process control parameter was then used in order to locate and estimate the quantity of water whose colony counts exceed the European directive guide level. Accurate correlation measurements between colony counts and DOC consumed in the network were carried out in three distinct systems. No significant correlations were measured. For these three networks, biodegradable organic matter measurements based on DOC determinations were demonstrated to be unreliable process control parameters for monitoring bacterial regrowth.

Determination of the water regulation capacity of a typic hapludands by means of humidity retention curves and the modeling of its hydrophysical properties

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
Cindy L. Argote-Sanchez ◽  
Juliana M. Lozano-Santa ◽  
Aldemar Reyes-Trujillo
Keyword(s):  
Organic Matter ◽  
Laboratory Finding ◽  
High Capacity ◽  
Water Regulation ◽  
A Value ◽  
Best Fitting ◽  
The Mean ◽  
Valle Del Cauca ◽  
Fitting Model

In the watershed Centella , located in the upper river basin of the Dagua - Valle del Cauca, in nine farms with association coffee - banana, coffee - guamo, cane panelera and pastures, the water regulation capacity of the soil was studied by means of humidity retention curves obtained in the laboratory and by modeling its hydrophysical properties in Hydrus 2D. Properties such as texture, bulk density, porosity, organic matter, hydraulic conductivity, infiltration and humidity were determined. Subsequently, moistureretention curves were simulated using the hydraulic models of Van Genuchten, Brooks and Corey, Van Genuchten modified and Kosugi, evaluating the average errors and the dispersion of the data. Agreed to the results it is possible to point out that the soil under study has a high capacity for moisture retention ( > 18%), consequence of the high content of clays ( > 41%) and organic matter ( > 5%), characteristics of the Andisols of the Valle del Cauca. Finally, the best fitting model was compared statistically with the data of the curves obtained in the laboratory, finding that Van Genuchten and Van Genuchten models modified, are the most appropriate for obtaining the retention curves from the hydrophysical properties since they presented a lower mean error (ME) with a value not higher than -0.11 cm3 / cm3 and a value of the square root of the mean square error (RMSE) less than 0.11 cm3 / cm3.

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

TURNOVER OF FLUVIAL PARTICULATE ORGANIC MATTER: THE ROLES OF SEDIMENT RESIDENCE TIME AND MICROBIOTA

2019 ◽  
Author(s):  
Marisa Repasch ◽  
◽  
Joel Scheingross ◽  
Joel Scheingross ◽  
Carolin Zakrzewski ◽  
...  
Keyword(s):  
Organic Matter ◽  
Residence Time ◽  
Particulate Organic Matter

Precipitation and filtration of zinc, magnesium, copper and aluminium hydroxides

1982 ◽  
Vol 47 (12) ◽  
pp. 3362-3370
Author(s):  
Otakar Söhnel ◽  
Eva Matějčková
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Filtration Resistance ◽  
Filtration Pressure ◽  
Bed Porosity ◽  
The Mean ◽  
Filtration Properties

Filtration properties of batchwise precipitated suspensions of Zn(OH)2, Mg(OH)2 and Cu(OH)2 and continuously precipitated Al(OH)3 were studied. For batchwise precipitated suspensions was verified the theoretically predicted dependence of specific filtration resistance on initial supersaturation and for the continuously precipitated Al(OH)3 the relation between the specific filtration resistance and the mean residence time of suspension in the reactor. Dependences were also recorded between the bed porosity and concentration of precipitated solutions, specific filtration resistance and used filtration pressure and the effect of aging of the batchwise precipitated suspension of Mg(OH)2on its filtration properties. The used CST method for determination of filtration characteristics of Zn(OH)2 suspension was also studied.

Sign in / Sign up

Export Citation Format

Share Document