scholarly journals Estimating mixing processes of sources contributing to baseflow in Alpine headwater catchments

2020 ◽  
Author(s):  
Marius G. Floriancic ◽  
Clément Roques ◽  
Joaquin Jimenez-Martinez
Keyword(s):  
Water Chemistry ◽  
Major Ions ◽  
Large Fraction ◽  
Isotopic Signature ◽  
Catchment Scale ◽  
Mixing Processes ◽  
Headwater Catchments ◽  
Chemical Screening ◽  
Relative Contribution ◽  
Geomorphological Features

<p>Baseflow is fed by groundwater to a large fraction. Estimating water quantity and quality from groundwater stores is essential for water management. However, there are few datasets available that contain detailed water chemistry analysis on high spatial resolution across multiple headwater catchments in (high) Alpine environments. This information is essential to analyze mixing processes on catchment scale from distinct landscape features.</p><p>We use two data sets: i) water chemistry analysis snapshot sampling campaigns in 7 headwater streams during low‑flow periods across Switzerland, and ii) a detailed chemical screening (every 25 m) in one selected catchment during baseflow, including electric conductivity and temperature. Major ions, stable isotopes, TOC, DOC, trace elements were analyzed for some of the samples (> 80). These data reveal the chemical fingerprint of the contributing groundwater sources. The chemical composition of these contributing sources to baseflow is largely influenced by weathering products depended on lithology and geomorphology. Using maximum likelihood calculations, we define the ion composition and the isotopic signature of the potential major endmembers (up to three), based on the mixed samples along the main stem.</p><p>The proposed methodology allows to i) reduce uncertainty of the endmembers, and ii) quantify the relative contribution of different lithology and geomorphological features to streamflow and shows iii) which spatial scale of input information is needed to analyze mixing processes from various groundwater sources. Our results show how the contribution of different lithologies, along with topography and geomorphological features, varies spatially throughout Alpine headwater catchments.</p>

scholarly journals Using stable isotope tracers to identify hydrological flow paths, residence times and landscape controls in a mesoscale catchment

2005 ◽  
Vol 2 (1) ◽  
pp. 1-35 ◽  
Author(s):  
P. Rodgers ◽  
C. Soulsby ◽  
S. Waldron ◽  
D. Tetzlaff
Keyword(s):  
Stream Water ◽  
Spatial Scales ◽  
Isotopic Signature ◽  
Residence Times ◽  
Catchment Scale ◽  
Mixing Processes ◽  
Flow Paths ◽  
Isotope Tracers ◽  
Periodic Regression ◽  
Stream Waters

Abstract. δ18O tracer measurements of precipitation and stream waters were used to investigate hydrological flow paths and residence times at nested spatial scales in the mesoscale (233 km2 River Feugh catchment in the northeast of Scotland over the 2001-2002 hydrological year. Precipitation δ18O exhibited strong seasonal variation, which although significantly damped by catchment mixing processes, was reflected in stream water outputs at six sampling sites. This allowed δ18O variations to be used to infer the relative influence of soil-derived storm flows with a seasonally variable isotopic signature, and groundwater of more constant isotopic composition. Periodic regression analysis was then used to examine the sub-catchment differences in the mixing of these two main hydrological sources processes more quantitatively, using an exponential flow model to provide preliminary estimates of mean stream water residence times, which varied between 0.4-2.9 years. This showed that the effects of increasing scale on estimated mean stream water residence time was minimal beyond the smallest (ca. 1 km2 headwater catchment scale. Instead, the interaction of catchment soil cover and topography acted as the dominant influence. Responsive hydrological pathways, associated with peat soils in the headwater sub-catchments, produced seasonally variable δ18O signatures in runoff with short mean residence times (0.4-0.8 years). In contrast, areas dominated by more freely draining soils and larger groundwater storage in shallow aquifers appear to provide effective mixing and damping of variable precipitation inputs implying longer residence times (1.4-2.9 years). These insights from δ18O measurements extend the hydrological understanding of the Feugh catchment gained from previous geochemical tracer studies, and demonstrate the utility of isotope tracers in investigating the interaction of hydrological processes and catchment characteristics at the mesoscale.

scholarly journals Water Quality and Hydrogeochemical Characteristics of Some Karst Water Sources in Apuseni Mountains, Romania

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 857
Author(s):  
Maria-Alexandra Hoaghia ◽  
Ana Moldovan ◽  
Eniko Kovacs ◽  
Ionut Cornel Mirea ◽  
Marius Kenesz ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Chemistry ◽  
Major Ions ◽  
Anthropogenic Activities ◽  
Water Sources ◽  
Main Process ◽  
Karst Water ◽  
Rock Interaction ◽  
Apuseni Mountains ◽  
Karst Waters

Human activities and natural factors determine the hydrogeochemical characteristics of karst groundwaters and their use as drinking water. This study assesses the hydrogeochemical characteristics of 14 karst water sources in the Apuseni Mountains (NW Romania) and their potential use as drinking water sources. As shown by the Durov and by the Piper diagrams, the chemical composition of the waters is typical of karst waters as it is dominated by HCO3− and Ca2+, having a circumneutral to alkaline pH and total dissolved solids ranging between 131 and 1092 mg L−1. The relation between the major ions revealed that dissolution is the main process contributing to the water chemistry. Limestone and dolostone are the main Ca and Mg sources, while halite is the main Na and Cl source. The Gibbs diagram confirmed the rock dominance of the water chemistry. The groundwater quality index (GWQI) showed that the waters are of excellent quality, except for two waters that displayed medium and good quality status. The quality of the studied karst waters is influenced by the geological characteristics, mainly by the water–rock interaction and, to a more limited extent, by anthropogenic activities. The investigated karst waters could be exploited as drinking water resources in the study area. The results of the present study highlight the importance of karst waters in the context of good-quality water shortage but also the vulnerability of this resource to anthropogenic influences.

Mismatch between lipid mobilization and oxidation: glycerol kinetics in running African goats

1993 ◽  
Vol 264 (4) ◽  
pp. R797-R803 ◽  
Author(s):  
J. M. Weber ◽  
T. J. Roberts ◽  
C. R. Taylor
Keyword(s):  
Fatty Acid ◽  
Aerobic Capacity ◽  
Indirect Calorimetry ◽  
Treadmill Exercise ◽  
Large Fraction ◽  
O2 Consumption ◽  
Glycerol Release ◽  
Intense Exercise ◽  
Lipid Mobilization ◽  
Relative Contribution

Glycerol kinetics and total fatty acid (FA) oxidation of trained African pygmy goats were measured by continuous infusion of [2-3H]glycerol and indirect calorimetry during treadmill exercise at 40, 60, and 85% maximal O2 consumption (VO2max). Our main goals were 1) to determine whether rates of FA mobilization and utilization are eventually matched as exercise intensity increases, thereby minimizing reesterification to supply more FA to working muscles, and 2) to test the hypothesis that lipolytic rate is proportional to aerobic capacity by comparing low-aerobic goats with published values from highly aerobic dogs and humans. Mean rate of glycerol release in the circulation (Ra glycerol) was 3.83 +/- 0.11 at rest, 7.69 +/- 0.88 at 40% VO2max, reached a maximum of 15.32 +/- 0.95 at 60% VO2max, and returned to 10.53 +/- 0.76 mumol.kg-1 x min-1 at 85% VO2max. Lipolytic rate did not match total FA oxidation, implying that Ra glycerol cannot be used as an index of FA utilization, even during intense exercise. A large fraction of total FA released by lipolysis was reesterified at 60 and 85% VO2max, showing that FA mobilization does not limit whole animal FA oxidation at these intensities. Comparing goat, dog, and human responses reveals that mammalian lipolytic rate is scaled with aerobic capacity. High- and low-aerobic species exercising at the same %VO2max mobilize FA in exact proportion with their metabolic rate, suggesting that the relative contribution of FA to total energy provision is independent of VO2max.

scholarly journals Verifying Operational Forecasts of Land–Sea-Breeze and Boundary Layer Mixing Processes

2020 ◽  
Vol 35 (4) ◽  
pp. 1427-1445
Author(s):  
Ewan Short
Keyword(s):  
Boundary Layer ◽  
Diurnal Cycle ◽  
Spatial Scales ◽  
Sea Breeze ◽  
Absolute Error ◽  
Wind Fields ◽  
Mixing Processes ◽  
Relative Contribution ◽  
The Mean ◽  
Diurnal Wind

AbstractForecasters working for Australia’s Bureau of Meteorology (BoM) produce a 7-day forecast in two key steps: first they choose a model guidance dataset to base the forecast on, and then they use graphical software to manually edit these data. Two types of edits are commonly made to the wind fields that aim to improve how the influences of boundary layer mixing and land–sea-breeze processes are represented in the forecast. In this study the diurnally varying component of the BoM’s official wind forecast is compared with that of station observations and unedited model guidance datasets. Coastal locations across Australia over June, July, and August 2018 are considered, with data aggregated over three spatial scales. The edited forecast produces a lower mean absolute error than model guidance at the coarsest spatial scale (over 50 000 km2), and achieves lower seasonal biases over all spatial scales. However, the edited forecast only reduces errors or biases at particular times and locations, and rarely produces lower errors or biases than all model guidance products simultaneously. To better understand physical reasons for biases in the mean diurnal wind cycles, modified ellipses are fitted to the seasonally averaged diurnal wind temporal hodographs. Biases in the official forecast diurnal cycle vary with location for multiple reasons, including biases in the directions that sea breezes approach coastlines, amplitude biases, and disagreement in the relative contribution of sea-breeze and boundary layer mixing processes to the mean diurnal cycle.

Estimation of groundwater CO2 concentrations on a catchment scale using Random Forest

2021 ◽  
Author(s):  
Stefan Baltruschat ◽  
Steffen Bender ◽  
Jens Hartmann ◽  
Annika Nolte
Keyword(s):  
Random Forest ◽  
Major Ions ◽  
Land Use Land Cover ◽  
Catchment Scale ◽  
Chemistry Data ◽  
Management Processes ◽  
Bulk Parameter ◽  
Anthropogenic Pollutions ◽  
Organic And Inorganic Fertilizers

<p>Water-rock-interactions in the saturated and unsaturated zone govern the natural variability of CO<sub>2</sub> in groundwater. However, anthropogenic pollutions such as excessive input of organic and inorganic fertilizers or sewage leakage can cause shifts in the carbonate-pH system in an aquifer. Additional dissolution of minerals and associated mobilization of harmful heavy metals are possible consequences. Anthropogenic groundwater pollution is especially an issue where a protective confining layer is absent. On the other hand, addressing an environmental hazard such as fertilizer input to a single parameter remain intricate due to the high number of possible competing reactions such as microbial-controlled redox reactions. To overcome these obstacles, machine learning based statistical methods become increasingly important.</p><p>This study attempt to predict the CO<sub>2 </sub>concentration in groundwater from a multi-feature selection by using Random Forest. For this purpose, groundwater chemistry data (in situ measured bulk parameter, major ions, nutrients, trace elements and more) from more than 23000 wells and springs in Germany were collected and homogenized in a single database. Measured or calculated CO<sub>2 </sub>concentrations<sub></sub>are used to train the Random Forest algorithm and later to validate model results. Beside chemistry data, features about hydrogeology, soil characteristics, land use land cover and climate factors serve as predictors to build the “forest”. The intention of this study is to establish comprehensive CO<sub>2 </sub>predictions based on surface and climate features and to identify trends in local CO<sub>2 </sub>production. Gained knowledge can be used as input for groundwater quality management processes and adaptation policies.</p>

Stoichiometric distance and total concentration: a binary numerical description of inland water chemistry

1976 ◽  
Vol 27 (1) ◽  
pp. 73
Author(s):  
RT Buckney
Keyword(s):  
Water Chemistry ◽  
Major Ions ◽  
Total Concentration ◽  
Inland Waters ◽  
Ion Chemistry ◽  
Major Ion Chemistry ◽  
Inland Water ◽  
Major Ion ◽  
Silica Concentration

A two-number description of the major ion chemistry of inland waters is derived from data on total concentration and the relative proportions of major ions (stoichiometry), and used to describe some broad features of Tasmanian inland waters. Equilibrium and other controls on pH and silica concentration are identified. Other possible uses of the binary numerical description are discussed.

scholarly journals Identification of multiple natural and anthropogenic sources of dust in snow from Zhongshan Station to Dome A, East Antarctica

2018 ◽  
Vol 64 (248) ◽  
pp. 855-865 ◽  
Author(s):  
ZHIHENG DU ◽  
CUNDE XIAO ◽  
MINGHU DING ◽  
CHUANJIN LI
Keyword(s):  
Major Ions ◽  
Isotope Composition ◽  
Isotopic Signature ◽  
East Antarctica ◽  
Anthropogenic Sources ◽  
Dome A ◽  
Long Distance ◽  
Anthropogenic Pollutants ◽  
Zhongshan Station ◽  
Snow Samples

ABSTRACTThe stable oxygen isotope composition, major ions and isotopic compositions of strontium (Sr), neodymium (Nd) and lead (Pb) in insoluble dust from recent surface snow samples along the transect from the Zhongshan and Progress stations (located on the Amery Ice Shelf, East Antarctica) to Dome A (Summit, Antarctica) were analysed. No previous isotopic fingerprinting studies have been conducted for this transect. These data were used to document the dust provenances in Antarctica along the transect up to the highest site, Dome A, for the first time. The insoluble dust in snow samples along the coast displays an overall crust-line isotopic signature that is characterised by highly radiogenic 87Sr/86Sr values and less radiogenic 143Nd/144Nd values. These signatures are comparable with those of samples collected near the ice-free areas of the Zhongshan and Progress stations. Spatial differences are statistically significant along the transect, and the Sr, Nd and Pb isotope components in insoluble dust from two continuous snow samples at Dome A exhibit marked differences, indicating that additional dust reaches the East Antarctic Plateau. The isotopic characteristics of insoluble dust from this transect indicate that the long-distance natural dust and anthropogenic pollutants in these samples primarily originate from Australia.

Sign in / Sign up

Export Citation Format

Share Document