scholarly journals Interception effects on stable isotope driven streamwater transit time estimates

2015 ◽  
Vol 42 (13) ◽  
pp. 5299-5308 ◽  
Author(s):  
Michael P. Stockinger ◽  
Andreas Lücke ◽  
Jeffrey J. McDonnell ◽  
Bernd Diekkrüger ◽  
Harry Vereecken ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Transit Time ◽  
Time Estimates

scholarly journals New water fractions and transit time distributions at Plynlimon, Wales, estimated from stable water isotopes in precipitation and streamflow

2019 ◽  
Author(s):  
Julia L. A. Knapp ◽  
Colin Neal ◽  
Alessandro Schlumpf ◽  
Margaret Neal ◽  
James W. Kirchner
Keyword(s):  
Time Series ◽  
Stable Isotope ◽  
Transit Time ◽  
Transport Processes ◽  
Water Isotopes ◽  
Data Sets ◽  
Hydrograph Separation ◽  
Stable Water Isotopes ◽  
Isotope Data ◽  
Water Fractions

Abstract. Long-term, high-frequency time series of passive tracers in precipitation and streamflow are essential for quantifying catchment transport and storage processes, but few such data sets are publicly available. Here we describe, present, and make available to the public two extensive data sets of stable water isotopes in streamflow and precipitation at the Plynlimon experimental catchments in mid-Wales. Stable isotope data are available at 7-hourly intervals for 17 months, and at weekly intervals for 4.25 years. Precipitation isotope values were highly variable in both data sets, and the high temporal resolution of the 7-hourly streamwater samples revealed rich isotopic dynamics that were not captured by the weekly sampling. We used ensemble hydrograph separation to calculate new water fractions and transit time distributions from both data sets. Transit time distributions estimated by ensemble hydrograph separation were broadly consistent with those estimated by spectral fitting methods, suggesting that they can reliably quantify the contributions of recent precipitation to streamflow. We found that on average, roughly 3 % of streamwater was made up of precipitation that fell within the previous 7 hours, and 13–15 % of streamwater was made up of precipitation that fell within the previous week. The contributions of recent precipitation to streamflow were highest during large events, as illustrated by comparing new water fractions for different discharges and precipitation rates. This dependence of new water fractions on water fluxes was also reflected in their seasonal variations, with lower new water fractions and more damped catchment transit time distributions in spring and summer compared to fall and winter. We also compared new water fractions obtained from stable water isotopes against those obtained from concentrations of chloride, a solute frequently used as a passive tracer of catchment transport processes. After filtering the chloride data for dry deposition effects, we found broadly similar new water fractions using chloride and stable water isotopes, indicating that these different tracers may yield similar inferences about catchment storage and transport, if potentially confounding factors are eliminated. These stable isotope time series comprise some of the longest and most detailed publicly available catchment isotope data sets. They complement extensive solute data sets that are already publicly available for Plynlimon, enabling a wide range of future analyses of catchment behavior.

scholarly journals New water fractions and transit time distributions at Plynlimon, Wales, estimated from stable water isotopes in precipitation and streamflow

2019 ◽  
Vol 23 (10) ◽  
pp. 4367-4388 ◽  
Author(s):  
Julia L. A. Knapp ◽  
Colin Neal ◽  
Alessandro Schlumpf ◽  
Margaret Neal ◽  
James W. Kirchner
Keyword(s):  
Time Series ◽  
Stable Isotope ◽  
Transit Time ◽  
Transport Processes ◽  
Water Isotopes ◽  
Data Sets ◽  
Hydrograph Separation ◽  
Stable Water Isotopes ◽  
Isotope Data ◽  
Water Fractions

Abstract. Long-term, high-frequency time series of passive tracers in precipitation and streamflow are essential for quantifying catchment transport and storage processes, but few such data sets are publicly available. Here we describe, present, and make available to the public two extensive data sets of stable water isotopes in streamflow and precipitation at the Plynlimon experimental catchments in central Wales. Stable isotope data are available at 7-hourly intervals for 17 months, and at weekly intervals for 4.25 years. Precipitation isotope values were highly variable in both data sets, and the high temporal resolution of the 7-hourly streamwater samples revealed rich isotopic dynamics that were not captured by the weekly sampling. We used ensemble hydrograph separation to calculate new water fractions and transit time distributions from both data sets. Transit time distributions estimated by ensemble hydrograph separation were broadly consistent with those estimated by spectral fitting methods, suggesting that they can reliably quantify the contributions of recent precipitation to streamflow. We found that on average, roughly 3 % of streamwater was made up of precipitation that fell within the previous 7 h, and 13 %–15 % of streamwater was made up of precipitation that fell within the previous week. The contributions of recent precipitation to streamflow were highest during large events, as illustrated by comparing new water fractions for different discharges and precipitation rates. This dependence of new water fractions on water fluxes was also reflected in their seasonal variations, with lower new water fractions and more damped catchment transit time distributions in spring and summer compared to fall and winter. We also compared new water fractions obtained from stable water isotopes against those obtained from concentrations of chloride, a solute frequently used as a passive tracer of catchment transport processes. After filtering the chloride data for dry deposition effects, we found broadly similar new water fractions using chloride and stable water isotopes, indicating that these different tracers may yield similar inferences about catchment storage and transport, if potentially confounding factors are eliminated. These stable isotope time series comprise some of the longest and most detailed publicly available catchment isotope data sets. They complement extensive solute data sets that are already publicly available for Plynlimon, enabling a wide range of future analyses of catchment behavior.

Sensitivity of mean transit time estimates to model conditioning and data availability

2011 ◽  
Vol 25 (6) ◽  
pp. 980-990 ◽  
Author(s):  
M. Hrachowitz ◽  
C. Soulsby ◽  
D. Tetzlaff ◽  
I. A. Malcolm
Keyword(s):  
Transit Time ◽  
Mean Transit Time ◽  
Data Availability ◽  
Time Estimates

scholarly journals Regionalization of transit time estimates in montane catchments by integrating landscape controls

2009 ◽  
Vol 45 (5) ◽  
Author(s):  
M. Hrachowitz ◽  
C. Soulsby ◽  
D. Tetzlaff ◽  
J. J. C. Dawson ◽  
I. A. Malcolm
Keyword(s):  
Transit Time ◽  
Time Estimates

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.

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