scholarly journals Supplementary material to "Depth to water table correction for initial carbon-14 activities in groundwater mean residence time estimation"

2021 ◽  
Author(s):  
Dylan Irvine ◽  
Cameron Wood ◽  
Ian Cartwright ◽  
Tanya Oliver
Keyword(s):  
Water Table ◽  
Residence Time ◽  
Mean Residence Time ◽  
Time Estimation ◽  
Carbon 14 ◽  
Depth To Water Table ◽  
Initial Carbon ◽  
Supplementary Material

scholarly journals Depth to water table correction for initial carbon-14 activities in groundwater mean residence time estimation

2021 ◽  
Vol 25 (10) ◽  
pp. 5415-5424
Author(s):  
Dylan J. Irvine ◽  
Cameron Wood ◽  
Ian Cartwright ◽  
Tanya Oliver
Keyword(s):  
Water Table ◽  
Unsaturated Zone ◽  
Time Estimation ◽  
Carbon 14 ◽  
Depth To Water Table ◽  
Groundwater Samples ◽  
Initial Carbon ◽  
Mean Residence Times ◽  
Depth Relationship

Abstract. Carbon-14 (14C) is routinely used to determine mean residence times (MRTs) of groundwater. 14C-based MRT calculations typically assume that the unsaturated zone is in equilibrium with the atmosphere, controlling the input 14C activity. However, multiple studies have shown that unsaturated zone 14C activities are lower than atmospheric values. Despite the availability of unsaturated zone 14C data, no attempt has been made to generalise initial 14C activities with depth to the water table. We utilise measurements of unsaturated zone 14C activities from 13 studies to produce a 14C–depth relationship to estimate initial 14C activities. The technique only requires the depth to the water table at the time of sampling or an estimate of depth to water in the recharge zone to determine the input 14C activity, making it straightforward to apply. Applying this new relationship to two Australian datasets (113 14C measurements in groundwater) shows that MRT estimates were up to 9250 years younger when the 14C–depth correction was applied relative to conventional MRTs. These findings may have important implications for groundwater samples that suggest the mixing of young and old waters and the determination of the relative proportions of young and waters, whereby the estimated fraction of older water may be much younger than previously assumed. Owing to the simplicity of the application of the technique, this approach can be easily incorporated into existing correction schemes to assess the sensitivity of unsaturated zone 14C to MRTs derived from 14C data.

scholarly journals Depth to water table correction for initial carbon-14 activities in groundwater mean residence time estimation

2021 ◽  
Author(s):  
Dylan Irvine ◽  
Cameron Wood ◽  
Ian Cartwright ◽  
Tanya Oliver
Keyword(s):  
Water Table ◽  
Unsaturated Zone ◽  
Time Estimation ◽  
Carbon 14 ◽  
Depth To Water Table ◽  
Groundwater Samples ◽  
Initial Carbon ◽  
Mean Residence Times ◽  
Depth Relationship

Abstract. Carbon-14 (14C) is routinely used to determine mean residence times (MRTs) of groundwater. 14C-based MRT calculations typically assume that the unsaturated zone is in equilibrium with the atmosphere, controlling the input 14C activity. However, multiple studies have shown that unsaturated zone 14C activities are lower than atmospheric values. Despite the availability of unsaturated zone 14C data, no attempt has been made to generalise initial 14C activities with depth to the water table. We utilise measurements of unsaturated zone 14C activities from 13 studies to produce a 14C-depth relationship to estimate initial 14C activities. The technique only requires the depth to the water table at the time of sampling, or an estimate of depth to water in the recharge zone to determine the input 14C activity, making it straightforward to apply. Applying this new relationship to two Australian datasets (113 14C measurements in groundwater) shows that MRT estimates were up to 9250 years younger when the 14C-depth correction was applied relative to conventional MRTs. These findings may have important implications for groundwater samples that suggest the mixing of young and old waters and the determination of the relative proportions of young and waters, whereby the estimated fraction of older water may be much younger than previously assumed. Owing to the simplicity of the application of the technique, this approach can be easily incorporated into existing correction schemes to assess the sensitivity of 14Cuz to MRTs derived from 14C data.

The Use of Carbon-14 and Tritium For Peat and Water Dynamics Characterization: Case of Čepkeliai Peatland, Southeastern Lithuania

2009 ◽  
Vol 34 (-1) ◽  
pp. 41-48 ◽  
Author(s):  
Jonas Mažeika ◽  
Rimantė Guobytė ◽  
Gintautas Kibirkštis ◽  
Rimantas Petrošius ◽  
Žana Skuratovič ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Residence Time ◽  
Sedimentation Rate ◽  
Mean Residence Time ◽  
Natural Condition ◽  
Accumulation Rate ◽  
Water Dynamics ◽  
Peat Accumulation ◽  
Carbon 14 ◽  
Peatland Development

The Use of Carbon-14 and Tritium For Peat and Water Dynamics Characterization: Case of Čepkeliai Peatland, Southeastern LithuaniaThe present investigation conducted in Čepkeliai peatland (south-eastern Lithuania) deals with two radioisotope methods - carbon-14 (14C) and tritium (3H).14C was applied to peatland chronology and sedimentation rate estimation and3H to peat water dynamics characterization. According to14C data, peatland development began since 12650-11350 years cal BP and peat accumulation since 10550-9700 years cal BP with peat accumulation rate of 0.27-0.79 mm/year in the central part of the peatland. The peat water mean residence time and basic groundwater flow was estimated to be respectively about 27±6 years and 62±15 mm based on3H data. The obtained data showed relatively undisturbed natural condition of Čepkeliai peatland in the studied sites.

scholarly journals Integrating Stable Isotopes with Mean Residence Time Estimation to Characterize Groundwater Circulation in a Metamorphic Geothermal Field in Yilan, Taiwan

Water ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 97
Author(s):  
Ching-Huei Kuo ◽  
Pi-Yi Li ◽  
Jun-Yi Lin ◽  
Yi-Lin Chen
Keyword(s):  
Stable Isotopes ◽  
Residence Time ◽  
Mean Residence Time ◽  
Circulation Model ◽  
Time Estimation ◽  
Geothermal Field ◽  
Water Circulation ◽  
Temporal And Spatial Distribution ◽  
Rock Interaction ◽  
Δ18o And Δd

This paper presents a water circulation model by combing oxygen and hydrogen stable isotopes and mean residence time (MRT) estimation in a high-temperature metamorphic geothermal field, Tuchen, in Yilan, Taiwan. A total of 18 months of oxygen and hydrogen stable isotopes of surface water and thermal water show the same variation pattern, heavier values in summer and lighter values in the rest of the year. A shift of δ18O with a relative constant δD indicates the slow fluid–rock interaction process in the study area. Two adjacent watersheds, the Tianguer River and Duowang River, exhibit different isotopic values and imply different recharge altitudes. The seasonal variation enabled us to use stable isotope to estimate mean residence time of groundwater in the study area. Two wells, 160 m and 2200 m deep, were used to estimate mean residence time of the groundwater. Deep circulation recharges from higher elevations, with lighter isotopic values, 5.9‰ and 64‰ of δ18O and δD, and a longer mean residence time, 1148 days, while the shallow circulation comes from another source with heavier values, 5.7‰ and 54.4‰ of δ18O and δD, and a shorter mean residence time, 150 days. A two-circulation model was established based on temporal and spatial distribution characteristics of stable isotopes and the assistance of MRT. This study demonstrates the usefulness of the combined usage for further understanding water circulation of other various temperatures of metamorphic geothermalfields.

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.

Nitrogen use efficiency: does a trade-off exist between the N productivity and the mean residence time within species?

2008 ◽  
Vol 56 (3) ◽  
pp. 272 ◽  
Author(s):  
Zhi Y. Yuan ◽  
Han Y. H. Chen ◽  
Ling H. Li
Keyword(s):  
Residence Time ◽  
Nitrogen Use Efficiency ◽  
Mean Residence Time ◽  
Negative Relationship ◽  
Controlled Experiments ◽  
Nitrogen Use ◽  
Trade Off ◽  
N Supply ◽  
Use Efficiency ◽  
The Mean

Nitrogen use efficiency (NUE) can be divided into two components, i.e. N productivity (A) and the mean residence time (MRT). Controlled experiments indicate that there is not a trade-off between A and MRT within species, but this theory has not been well tested in field conditions. Here, we studied the A, MRT and NUE of Stipa krylovii Roshev. in a grassland over 4 years of N fertilisation experimentation. The three parameters (A, MRT and NUE) were significantly related to soil N supply and there was a negative relationship between A and MRT within this species (r = –0.775, P < 0.05), i.e. plants with higher A had lower MRT. Our results showed a trade-off between A and MRT within this Stipa species and this observed trade-off was attributed to different responses of A and MRT to soil fertility.

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