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Special Issue "Isotopes in Hydrology and Hydrogeology"

A special issue of Water (ISSN 2073-4441).

Deadline for manuscript submissions: closed (31 October 2017)

Special Issue Editor

Guest Editor
Prof. Dr. Maurizio Barbieri

Department of Earth Sciences, Sapienza University of Rome, P.le Aldo Moro, 5 - 00185 Roma, Italy
Website | E-Mail
Interests: geochemical tracers in hydrological studies; interactions between water and the geological and chemical environment; quantitative understanding of chemically based processes in hydrogeochemical environments and complementary physical and biological processes and conditions; kinetics and equilibria of geochemical reactions; the movement of isotopes and soil chemistry; freshwater-seawater interactions in coastal aquifers; basic and applied research on speciation and transformation of trace metals and metalloids during biogeochemical processes in both natural and anthropogenic environments; radiogenic and stable isotope geochemistry

Special Issue Information

Dear Colleagues,

Within the realm of the newly evolving discipline of environmental sciences, the application of isotopes methodology is being used to an ever-increasing extent.

Application include tracing the evolution of a water mass from its origin as precipitation, through its recharge processes and ending at its occurrence in an aquifer. There is a special focus on the processes at the surface–atmosphere and land–biosphere–atmosphere interfaces, since these are the sites of major changes in isotope composition.

Isotopes can also be used to determine the origin of a specific solutes in ground water. Application of this type commonly involve stable isotopes. The list of stable isotopes that has important implications for water resources management has grown in recent years. The other main class of applications of isotopes is based on the decay of radioisotopes. Unlike stable isotope applications that shed light on geochemical processes in aquifers, the radioisotopes are primarily used to determining the relative or absolute age of water in an aquifer. Actually, the date obtained give some indication of the residence time of water in an aquifer once it has passed through the vadose zone.

In some instance, ground waters can be dated by the use of radioisotopes, although the stable isotope can also be used in some dating applications.

In the last decades is increasing interest in environmentally friendly tracers, like isotopes, because of concern has emerged about the application of artificially tracers in aquatic ecosystems due to their potentially negative impact on the environment.

Prof. Dr. Maurizio Barbieri
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • aquifer,
  • hydrological cycle
  • stable isotopes
  • tracers
  • radioactive isotopes
  • groundwater recharge
  • groundwater salinization
  • groundwater pollution
  • groundwater transit time
  • groundwater dating

Published Papers (10 papers)

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Research

Open AccessArticle The Source, Flow Rates, and Hydrochemical Evolution of Groundwater in an Alluvial Fan of Qilian Mountain, Northwest China
Water 2017, 9(12), 912; doi:10.3390/w9120912
Received: 31 October 2017 / Revised: 19 November 2017 / Accepted: 21 November 2017 / Published: 23 November 2017
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Abstract
Major ions and selected environmental tracers (D, 18O, 3H and chlorofluorocarbons (CFCs)) were employed to determine the source, flow rates, and hydrochemical evolution of groundwater in an alluvial fan along the front of the Qilian Mountains, which serves as an important
[...] Read more.
Major ions and selected environmental tracers (D, 18O, 3H and chlorofluorocarbons (CFCs)) were employed to determine the source, flow rates, and hydrochemical evolution of groundwater in an alluvial fan along the front of the Qilian Mountains, which serves as an important groundwater reservoir in northwest China. Temporal and spatial variations in ion concentrations were limited near the upper portion of the alluvial fan. However, groundwater quality deteriorated along the flow path as concentrations of Mg2+, Na+, SO42−, and Cl increased toward the fan toe and into the center of the valley. The relative abundance of the major cations and anions also changed down-fan from Ca2+ to Na+ and Mg2+, and from HCO3 to SO42− and Cl, respectively. Isotopic data suggests that precipitation within the Qilian Mountains, which recharged the alluvial deposits near the mountain front, was the primary source of groundwater. Apparent groundwater ages determined by CFCs varied from 23 to 40 years, and in general, increased in age from south to north (down-fan). It is concluded that groundwater in the study area was recharged by the Qilian Mountains, flowed through the alluvial fan from south to north, and was subsequently discharged several decades later from springs located along the toe of the fan, after which it re-entered the Shule River. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessFeature PaperArticle Evolution of Uranium Isotopic Compositions of the Groundwater and Rock in a Sandy-Clayey Aquifer
Water 2017, 9(12), 910; doi:10.3390/w9120910
Received: 4 October 2017 / Revised: 3 November 2017 / Accepted: 20 November 2017 / Published: 23 November 2017
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Abstract
Uranium isotopes have been used as mechanistic or time scale tracers of natural processes. This paper describes the occurrence and redistribution of U in the Vendian aquifer of a paleo-valley in NW Russia. Forty-four rock samples were collected from nine boreholes with depths
[...] Read more.
Uranium isotopes have been used as mechanistic or time scale tracers of natural processes. This paper describes the occurrence and redistribution of U in the Vendian aquifer of a paleo-valley in NW Russia. Forty-four rock samples were collected from nine boreholes with depths up to 160 m, and 25 groundwater samples were collected from 23 boreholes with depths up to 300 m. The U, Fe concentration, and 234U/238U activity ratio were determined in the samples. Estimations were made of the 14C and 234U-238U residence time of groundwater in the aquifer. It has been established that the processes of chemical weathering of Vendian deposits led to the formation of a strong oxidation zone, developed above 250 m.b.s.l. The inverse correlation between the concentrations of uranium and iron is a result of removal of U from paleo-valley slopes in oxidizing conditions, accumulation of U at the bottom of the paleo-valley in reducing conditions, and accumulation of Fe on the slopes and removal from the bottom of the paleo-valley. Almost all U on the slopes has been replaced by a newly formed hydrogenic U with a higher 234U/238U activity ratio. After, dissolution and desorption of hydrogenic U occurred from the slopes during periods with no glaciations and marine transgressions. Elevated concentrations of U are preserved in reduced lenses at the paleo-valley bottom. In these areas, the most dangerous aspect is the flow of groundwater from the underlying horizons, since during the operation of water supply wells it can lead to the creation of local zones of oxidizing conditions in the perforated screens zone and the transition of uranium into solution. For groundwater under oxidizing conditions, an increase in the concentration of uranium is characteristic of an increase in the residence time (age) of water in the aquifer. Also, the 234U/238U activity ratio increases with increasing radioactivity of groundwater. Therefore, the most rational approach is to use groundwater for drinking water supply from the slopes of the Northern Dvina basin. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessFeature PaperArticle Compound-Specific Isotope Analysis (CSIA) Application for Source Apportionment and Natural Attenuation Assessment of Chlorinated Benzenes
Water 2017, 9(11), 872; doi:10.3390/w9110872
Received: 22 September 2017 / Revised: 25 October 2017 / Accepted: 1 November 2017 / Published: 9 November 2017
Cited by 1 | PDF Full-text (2762 KB) | HTML Full-text | XML Full-text
Abstract
In light of the complex management of chlorobenzene (CB) contaminated sites, at which a hydraulic barrier (HB) for plumes containment is emplaced, compound-specific stable isotope analysis (CSIA) has been applied for source apportionment, for investigating the relation between the upgradient and downgradient of
[...] Read more.
In light of the complex management of chlorobenzene (CB) contaminated sites, at which a hydraulic barrier (HB) for plumes containment is emplaced, compound-specific stable isotope analysis (CSIA) has been applied for source apportionment, for investigating the relation between the upgradient and downgradient of the HB, and to target potential CB biodegradation processes. The isotope signature of all the components potentially involved in the degradation processes has been expressed using the concentration-weighted average δ13C of CBs + benzene (δ13Csum). Upgradient of the HB, the average δ13Csum of −25.6‰ and −29.4‰ were measured for plumes within the eastern and western sectors, respectively. Similar values were observed for the potential sources, with δ13Csum values of −26.5‰ for contaminated soils and −29.8‰ for the processing water pipeline in the eastern and western sectors, respectively, allowing for apportioning of these potential sources to the respective contaminant plumes. For the downgradient of the HB, similar CB concentrations but enriched δ13Csum values between −24.5‰ and −25.9‰ were measured. Moreover, contaminated soils showed a similar δ13Csum signature of −24.5‰, thus suggesting that the plumes likely originate from past activities located in the downgradient of the HB. Within the industrial property, significant δ13C enrichments were measured for 1,2,4-trichlorobenzene (TCB), 1,2-dichlorobenzene (DCB), 1,3-DCB, and 1,4-DCBs, thus suggesting an important role for anaerobic biodegradation. Further degradation of monochlorobenzene (MCB) and benzene was also demonstrated. CSIA was confirmed to be an effective approach for site characterization, revealing the proper functioning of the HB and demonstrating the important role of natural attenuation processes in reducing the contamination upgradient of the HB. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle Variability of Stable Isotope in Lake Water and Its Hydrological Processes Identification in Mt. Yulong Region
Water 2017, 9(9), 711; doi:10.3390/w9090711
Received: 13 July 2017 / Revised: 11 September 2017 / Accepted: 12 September 2017 / Published: 16 September 2017
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Abstract
Lakes are regarded as important nodes in water resources, playing pivotal roles in the regional hydrological cycle. However, the systematic study on lake water balance is scarce in Mt. Yulong region. Here, we study the stable isotope compositions of precipitation, inflowing rivers and
[...] Read more.
Lakes are regarded as important nodes in water resources, playing pivotal roles in the regional hydrological cycle. However, the systematic study on lake water balance is scarce in Mt. Yulong region. Here, we study the stable isotope compositions of precipitation, inflowing rivers and lake water to exploit the characteristics of hydrological supply and lake water balance. The results showed that there was a typical spatial distribution of surface isotope in August and April. Relatively high δ18O values with low d-excess were found on the east and west shores of the lake in August and in the middle part of the lake in April. The lowest δ18O with highest d-excess were found in the north and south shores in August and April, respectively. Meanwhile, slight isotopic stratification indicated that the lake water was vertically mixed-well. Subsequently, the evaporation-to-inflow ratios (E/Is) during the two periods were further derived based on the isotope mass balance model. Approximately 51% in August and 12% in April of the water flowing into Lashi Lake underwent evaporation. This study provides a reference for the long-term monitoring and modeling the hydrology processes of the basin, and is important for the regional water resource. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle Temporal and Spatial Variations of Hydrological Processes on the Landscape Zone Scale in an Alpine Cold Region (Mafengou River Basin, China): An Update
Water 2017, 9(8), 574; doi:10.3390/w9080574
Received: 7 June 2017 / Revised: 25 July 2017 / Accepted: 26 July 2017 / Published: 12 August 2017
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Abstract
This study investigates precipitation, snow, groundwater, glaciers and frozen soil in different landscape zones using isotopic and hydrogeochemical tracers. The aim of this study is to identify temporal and spatial variations, as well as hydrological processes in the alpine cold region. The results
[...] Read more.
This study investigates precipitation, snow, groundwater, glaciers and frozen soil in different landscape zones using isotopic and hydrogeochemical tracers. The aim of this study is to identify temporal and spatial variations, as well as hydrological processes in the alpine cold region. The results show that there was no significant difference in water chemical characteristics of various waterbodies, and no obvious temporal variation, but exhibited spatial variation. In the wet season, various waterbodies are enriched in oxygen δ18O and deuterium δD due to a temperature effect. Precipitation and the temperature decrease during the dry season, which cannot easily be affected by secondary evaporation. The d-excess (deuterium excess) of various waterbodies was greater than 10‰. There are no altitude effects during wet and dry seasons because the recharged water resources are different in the wet and dry seasons. It is influenced by the freezing-thawing process of glacier snow and frozen soil. The river water is recharged by thawed frozen soil water and precipitation in the wet season, but glacier snow meltwater with negative δ18O and δD is less (14–18%). In the dry season, glacier snow meltwater and groundwater are the dominant source of the river water, and thawed frozen soil water is less (10–15%). Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle Applications of Hydro-Chemical and Isotopic Tools to Improve Definitions of Groundwater Catchment Zones in a Karstic Aquifer: A Case Study
Water 2017, 9(8), 595; doi:10.3390/w9080595
Received: 12 June 2017 / Revised: 2 August 2017 / Accepted: 7 August 2017 / Published: 10 August 2017
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Abstract
Some researchers have proposed the groundwater protection zone (GPZ) method as a methodological framework for defining safeguard zones of groundwater bodies. Its goal is to protect the quality of water intended for human consumption and to facilitate a common implementation of this method
[...] Read more.
Some researchers have proposed the groundwater protection zone (GPZ) method as a methodological framework for defining safeguard zones of groundwater bodies. Its goal is to protect the quality of water intended for human consumption and to facilitate a common implementation of this method in all European Union member states. One of the criteria used to establish GPZs is to define contributing catchment areas (CCAs). This methodology has been applied to the Sierra de Cañete, a region comprising a carbonate aquifer in the province of Malaga, Spain. The tools used to define CCAs are hydro-chemical and isotopic characterizations, namely water isotopes (i.e., 2H, 18O and tritium) and the isotopes of dissolved sulfates (i.e., 34S and 18O). Traditionally, the Sierra de Cañete aquifer has been divided into six sectors. Hydro-chemical and isotopic characterization differentiated between two large areas in the carbonate aquifer. The southern part presents younger water that is the result of faster recharge and that shows a high level of karstification, while the northern area has a slower flow, and recharge is produced over several years. In addition, the northern part is hydraulically connected to an alluvial aquifer (i.e., Llanos de Almargen) that borders the Sierra de Cañete to the north. This aquifer has high levels of pollution due to agricultural and livestock activities carried out in the Llanos de Almargen area. This pollution is transmitted to the carbonate aquifer when groundwater depletion occurs. Therefore, the Sierra de Cañete GPZ needs to be extended to include the Llanos de Almargen aquifer. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle Identifying Groundwater Recharge Sites through Environmental Stable Isotopes in an Alluvial Aquifer
Water 2017, 9(8), 569; doi:10.3390/w9080569
Received: 26 June 2017 / Revised: 26 July 2017 / Accepted: 28 July 2017 / Published: 2 August 2017
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Abstract
Environmental isotope tracers have been a useful tool in providing new insights into hydrologic processes. In Mexico, there have been several studies reporting different values for δ18O and δ2H for certain geographical areas. The objective of this study is
[...] Read more.
Environmental isotope tracers have been a useful tool in providing new insights into hydrologic processes. In Mexico, there have been several studies reporting different values for δ 18 O and δ 2 H for certain geographical areas. The objective of this study is to achieve the isotopic characterization of rainfall and groundwater and to report the comprehensive understanding of groundwater flow processes around and within the Calera aquifer and, consequently, its potential recharge sites. The samples used for the stable isotope analysis ( δ 18 O , δ 2 H ) were measured using a GV-Isoprime isotope-ratio mass spectrometer at the Isotopy Laboratory of the Water Center for Latin America and the Caribbean. The δ D of precipitation ranged between −110.20‰ and 10.11‰, with a mean of −55.67‰ ± 27.81‰. The δ 18 O ranged between −17.80‰ and 2.74‰, with a mean of −9.44‰ ± 4.74‰. The δ D of groundwater ranged between −81.92‰ and −36.45‰, with a mean of −66.05‰ ± 8.58‰. The δ 18 O ranged between −18.26‰ and −8.84‰, with a mean of −12.35‰ ± 2.12‰. The local meteoric water line of the Zacatecas state is δ D = 2.03 + 5.68 δ 18 O . The groundwater samples were clustered into four groups. The clustering of the samples led to the finding that streamflows play a significant role in the hydrological balance as a source of local recharge to the aquifer. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle Understanding the Role of Groundwater in a Remote Transboundary Lake (Hulun Lake, China)
Water 2017, 9(5), 363; doi:10.3390/w9050363
Received: 14 January 2017 / Revised: 8 April 2017 / Accepted: 4 May 2017 / Published: 22 May 2017
Cited by 2 | PDF Full-text (1293 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Hulun Lake, located in a remote, semi-arid area in the northeast part of Inner Mongolia, China, shares a transboundary basin with Mongolia and supports a unique wetland ecosystem that includes many endangered species. Decadal scale decreases in the lake stage and increased salinity
[...] Read more.
Hulun Lake, located in a remote, semi-arid area in the northeast part of Inner Mongolia, China, shares a transboundary basin with Mongolia and supports a unique wetland ecosystem that includes many endangered species. Decadal scale decreases in the lake stage and increased salinity make an understanding of the lake’s water and salt sources critical for appropriate design of strategies to protect and manage the lake. Multiple tracers (chloride, and δ18O and δ2H in water) in samples collected from lake water, rivers, and nearby water wells were used in conjunction with an annual water balance based on historic data to better understand the lake’s major water and salt sources. The average annual water balance was conducted for two time periods: 1981–2000 and 2001–2013. The contribution of river discharge to the annual lake input decreased by half (from 64% to 31%) between the two time periods, while the volumetric contribution of groundwater discharge increased four-fold (from about 11% to about 50% of the total lake input). Significant evaporation was apparent in the stable isotope composition of the present-day lake water, however, evaporation alone could not account for the high lake water chloride concentrations. Limited domestic well water sampling, a regional salinity survey, and saline soils suggest that high chloride groundwater concentrations exist in the region south of the lake. The chloride mass balance suggested that groundwater currently contributes more than 90% of the annual chloride loading to the lake, which is likely four times greater than the earlier period (1981–2000) with lower groundwater input. The use of water and chloride mass balances combined with water isotope analyses could be applied to other watersheds where hydrologic information is scarce. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle Using δ15N and δ18O Signatures to Evaluate Nitrate Sources and Transformations in Four Inflowing Rivers, North of Taihu Lake
Water 2017, 9(5), 345; doi:10.3390/w9050345
Received: 28 February 2017 / Revised: 8 May 2017 / Accepted: 8 May 2017 / Published: 17 May 2017
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Abstract
Taihu Lake is the third largest freshwater lake in China. Due to rapid economic development and excessive nutrient discharges, there is serious eutrophication in the northern part of the lake. Nitrogen (N) is one of the key factors for eutrophication in Taihu Lake,
[...] Read more.
Taihu Lake is the third largest freshwater lake in China. Due to rapid economic development and excessive nutrient discharges, there is serious eutrophication in the northern part of the lake. Nitrogen (N) is one of the key factors for eutrophication in Taihu Lake, which mainly comes from the rivers around the lake. Samples from four inflowing rivers were analysed for δ15N and δ18O isotopes in December 2013 to identify the different sources of nitrogen in the northern part of Taihu Lake. The results indicated that the water quality in Taihu Lake was clearly influenced by the water quality of the inflowing rivers and nitrate (NO3-N) was the main component of the soluble inorganic nitrogen in water. The soil organic N represented more than 70% of the total NO3-N loads in the Zhihugang. Domestic sewage was the major NO3-N source in the Liangxi river, with a contribution of greater than 50%. Soil organic N and domestic sewage, with contributions of more than 30% and 35% respectively, were the major NO3-N sources in the Lihe river and Daxigang river. Denitrification might be responsible for the shifting δ15N-NO3 and δ18O-NO3 values in the Daxigang river, and a mixing process may play a major role in N transformations in the Lihe river in winter. The results of this study will be useful as reference values for reducing NO3 pollution in the inflowing rivers in the north of Taihu Lake. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Open AccessArticle Identification of Waters Incorporated in Laguna Lake, Republic of the Philippines, Based on Oxygen and Hydrogen Isotopic Ratios
Water 2017, 9(5), 328; doi:10.3390/w9050328
Received: 21 January 2017 / Revised: 3 May 2017 / Accepted: 3 May 2017 / Published: 6 May 2017
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Abstract
We examined the oxygen and hydrogen isotopic ratios of surface waters and groundwaters in the catchment of Laguna Lake, Republic of the Philippines, to identify the types of water that combine and control these ratios in the lake water. The oxygen and hydrogen
[...] Read more.
We examined the oxygen and hydrogen isotopic ratios of surface waters and groundwaters in the catchment of Laguna Lake, Republic of the Philippines, to identify the types of water that combine and control these ratios in the lake water. The oxygen and hydrogen isotopic ratios of water samples collected from rivers, lakes, springs, and irrigation canals were determined using cavity ring-down spectroscopy. The lake water data deviated from the meteoric line of the Philippines by between −13.5‰ and −10‰, and between −11.5‰ and −1.5‰ in the dry and wet seasons, respectively. The values for the groundwaters and surface waters were mainly between −8‰ and 3‰ throughout the year. In addition to rainwater, evaporative concentration, which may have an almost constant effect throughout the year, was the main control on the oxygen and hydrogen isotopic properties of Laguna Lake. The contributions of the surface waters and groundwaters to the oxygen and hydrogen isotopic ratios of the lake were relatively constant. Based on their isotopic properties, the waters within the water catchment area of Laguna Lake can be roughly divided into lake water with heavier isotopic ratios, and groundwater and surface water with lighter isotopic ratios. Full article
(This article belongs to the Special Issue Isotopes in Hydrology and Hydrogeology)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Delineating Recharge Elevation and Residence Time of Groundwater on a Cascade Range Volcano

Authors: Jean E. Moran, Ate Visser, Elizabeth Peters, Bradley K. Esser, Michael J. Singleton

Abstract: A warming climate will bring drastic changes to hydrologic systems in the headwater basins of the major rivers in California, USA. Runoff in these rivers fills the reservoirs that sustain cities and agriculture through the dry months, while cool, late season groundwater discharge to streams is critical for sustaining subalpine ecosystems. Despite the important role they play in the larger hydrologic system, groundwater flow paths in headwater basins are typically not well characterized, with recharge and discharge locations largely unidentified, and subsurface residence times unknown.

We examined several groundwater residence time tracers, stable isotopes and noble gas recharge temperatures in samples from wells and springs on Mount Shasta at the headwaters of the Sacramento River. The topographic relief of this 4300 m volcano imparts robust signatures of recharge elevation to both stable isotopes of the water molecule (d^18 O and dD), and to dissolved noble gases, offering tools to identify recharge areas and delineate groundwater flow paths. This study was carried out during drought years, when the influence of runoff and recent recharge were minimal. Recharge elevations determined using stable isotopes and noble gas recharge temperatures are in close agreement, and indicate that most snowmelt infiltrates at elevations between 2000 and 2900 m (6600 and 9500 ft), which coincides with areas of thin soils and barren land cover. The large springs in Mt Shasta City discharge at an elevation more than 1500 m lower. High elevation springs (>2000 m) yield very young water (< 2 years) while lower elevation wells (1000-1500 m) produce water with a residence time of 6 years or more, based on tritium concentrations in sampled water. Residence time indicators with shorter half-lives (35-Sulfur and 22-Sodium) were not detected, suggesting that very recent recharge was a negligibly small component at the time of sampling. Combined with recharge elevation estimates, ages indicate horizontal flow velocities between 0.5 and 1 km per year. Differences between recharge and discharge temperatures (corrected for gravitational potential energy dissipation), allow estimation of a maximum flow path depth, which for Mt Shasta samples is about 500 m.

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