Methods for using argon-39 to age-date groundwater using ultra-low-background proportional counting

Energy Technology Data Exchange (ETDEWEB)

Mace, Emily; Aalseth, Craig; Brandenberger, Jill; Day, Anthony; Hoppe, Eric; Humble, Paul; Keillor, Martin; Kulongoski, Justin; Overman, Cory; Panisko, Mark; Seifert, Allen; White, Signe; Wilcox Freeburg, Eric; Williams, Richard

2017-08-01

Argon-39 can be used as a tracer for age-dating glaciers, oceans, and more recently, groundwater. With a half-life of 269 years, 39Ar fills an intermediate age range gap (50-1,000 years) not currently covered by other common groundwater tracers. Therefore, adding this tracer to the data suite for groundwater studies provides an important tool for improving our understanding of groundwater systems. We present the methods employed for arriving at an age-date for a given sample of argon degassed from groundwater.

Inferring Groundwater Age in an Alluvial Aquifer from Tracer Concentrations in the Stream - Little Wind River, Wyoming

Science.gov (United States)

Goble, D.; Gardner, W. P.; Naftz, D. L.; Solder, J. E.

2017-12-01

We use environmental tracers: CFC's, SF6, and 222Rn measured in stream water to determine volume and mean age of groundwater discharging to the Little Wind River, near Riverton, Wyoming. Samples of 222Rn were collected every 200 m along a 2 km reach, surrounding a known groundwater discharge zone. Nearby groundwater wells, in-stream piezometers and seepage meters were sampled for 222Rn, CFC's and SF6. Tracer concentrations measured in groundwater and in-stream piezometers were used to estimate the mean age of the subsurface system. High resolution 222Rn samples were used to determine the location and volume of groundwater inflow using a model of instream transport that includes radioactive decay and gas exchange with the atmosphere. The age of groundwater entering the stream was then estimated from in-stream measured CFC and SF6 concentrations using a new coupled stream transport and lumped-parameter groundwater age model. Ages derived from in-stream measurements were then compared to the age of subsurface water measured in piezometers, seepage meters, and groundwater wells. We then asses the ability of groundwater age inferred from in-stream samples to provide constraint on the age of the subsurface discharge to the stream. The ability to asses groundwater age from in-stream samples can provide a convenient method to constrain the regional distribution of groundwater circulation rates when groundwater sampling is challenging or wells are not in place.

Application of groundwater sustainability indicators to the Upper Pliocene aquifer in Ho Chi Minh city, Viet Nam

Science.gov (United States)

Ngo, T. M.; Lee, J.; Lee, H.; Woo, N. C.

2013-12-01

Groundwater plays an importance role for domestic, industrial, and agricultural uses in Ho Chi Minh city, Viet Nam. This study is objected to evaluate the sustainability of groundwater by using groundwater sustainability indicators (GWSIs) defined by UNESCO/IAEA/IAH Working Group on Groundwater Indicators at aquifer scale (the Upper Pliocene aquifer). There are four main indicators selected and one new indicator designed for the particular characteristic of Ho Chi Minh city which is under influence of by saline-water intrusion. The results indicated groundwater of the Upper Pliocene aquifer, the main groundwater supply source, is generally in the unsustainable state. The abstraction of groundwater, which was much greater than its capability, is probably causing the serious state of annual groundwater depletion and saline-water intrusion. The GWSIs, which expressed in such a simple way but scientifically-based and policy-relevant, proved its usefulness in evaluating the sustainability of groundwater at the aquifer scale in Ho Chi Minh city, and subsequently should be incorporated in water resource management practices.

Modeling groundwater age using tritium and groundwater mineralization processes - Morondava sedimentary basin, Southwestern Madagascar

International Nuclear Information System (INIS)

RAMAROSON, V.

2007-01-01

The tritium method in the lumped parameter approach was used for groundwater dating in the Morondava sedimentary basin, Southwestern Madagascar. Tritium data were interpreted by the dispersion model. The modeling results, with P D values between 0.05 and 0.7, show that shallow groundwater age is ranging from 17 to 56 years. Different types of chemical composition were determined for these shallow ground waters, among others, Ca-HCO 3 , Ca-Na-HCO 3 , Ca-Na-Mg-HCO 3 , Ca-K-HCO 3 -NO 3 -SO 4 , Na-Cl, or Ca-Na-Mg-Cl. Likewise, deeper ground waters show various chemical type such as Ca-Na-HCO 3 , Ca-Mg-Na H CO 3 , Ca-Na-Mg-HCO 3 , Ca-Na-Mg-HCO 3 -Cl-SO 4 , Ca-Mg-HCO 3 , Na-Ca-Mg-HCO 3 -SO 4 -Cl, Na-Cl-HCO 3 or Na-HCO 3 -Cl. To evaluate the geochemical processes, the NETPATH inverse geochemical modeling type was implemented. The modeling results show that silicate minerals dissolution , including olivine, plagioclase, and pyroxene is more important than calcite or dolomite dissolution, for both shallow and deeper groundwater . In the Southern part of the study area, while halite dissolution is likely to be the source of shallow groundwater chloride concentration rise, the mineral precipitation seems to be responsible for less chloride content in deeper groundwater. Besides, ion exchange contributes to the variations of major cations concentrations in groundwater. The major difference between shallow and deep groundwater mineralization process lies in the leaching of marine aerosols deposits by local precipitation, rapidly infiltrated through the sandy formation and giving marine chemical signature to shallow groundwater [fr

A Bayesian modeling approach for estimation of a shape-free groundwater age distribution using multiple tracers

NARCIS (Netherlands)

Massoudieh, A.; Visser, A.; Sharifi, S.; Broers, H.P.

2014-01-01

Due to the mixing of groundwaters with different ages in aquifers, groundwater age is more appropriately represented by a distribution rather than a scalar number. To infer a groundwater age distribution from environmental tracers, a mathematical form is often assumed for the shape of the

A new approach to constrain basal helium flux into aquifers for better estimation of groundwater ages by Helium 4

Science.gov (United States)

Matsumoto, Takuya; Sturchio, Neil C.; Chang, Hung K.; Gastmans, Didier; Araguas-Araguas, Luis J.; Jiang, Wei; Lu, Zheng-Tian; Mueller, Peter; Yokochi, Reika; Purtschert, Roland; Zongyu, Chen; Shuiming, Hu; Aggarwal, Pradeep K.

2016-04-01

Estimation of groundwater age through the combined use of isotope methods and groundwater flow modelling is the common approach used for developing the required level of knowledge in the case of groundwater pumped from deep aquifers. For more than 50 years radiocarbon and tritium have been the common tools used in isotope hydrology studies to provide first estimates of groundwater age and dynamics. The half-life of carbon-14 (5730 years) and the complex geochemistry of carbon species in most environments have limited the proper characterization of groundwater flow patterns in large sedimentary basins and deep aquifers to ages more recent than about 40 000 years. Over the last years, a number of long-live radionuclides and other isotopes have been tested as more reliable age indicators by specialised laboratories. Among these methods, chlorine-36 (half-life of 300 000 yr) has been used with mixed results, mainly due to problems derived from in-situ production of this radionuclide. Uranium isotopes have also been used in a few instances, but never became a routine tool. Accumulation of helium-4 in deep groundwaters has also been proposed and used in a few instance, but one major obstacle in the 4He dating method is a difficulty in assessing a rate constant of 4He input into aquifers (namely, the entering basal 4He flux). In this context, recent breakthrough developments in analytical methods allow the precise determination of dissolved noble gases in groundwater as well as trace-level noble gas radionuclides present in very old groundwaters. Atom trap trace analysis, or ATTA, has dramatically improved over the last years the processing of very small amount of noble gases, providing now real possibilities for routine measurements of extremely low concentration of exotic radionuclides dissolved in groundwater, such as krypton-81 (half-life 229 000 years). Atom trap trace analysis involves the selective capture of individual atoms of a given isotope using six laser

Determination of timescales of nitrate contamination by groundwater age models in a complex aquifer system

Science.gov (United States)

Koh, E. H.; Lee, E.; Kaown, D.; Lee, K. K.; Green, C. T.

2017-12-01

Timing and magnitudes of nitrate contamination are determined by various factors like contaminant loading, recharge characteristics and geologic system. Information of an elapsed time since recharged water traveling to a certain outlet location, which is defined as groundwater age, can provide indirect interpretation related to the hydrologic characteristics of the aquifer system. There are three major methods (apparent ages, lumped parameter model, and numerical model) to date groundwater ages, which differently characterize groundwater mixing resulted by various groundwater flow pathways in a heterogeneous aquifer system. Therefore, in this study, we compared the three age models in a complex aquifer system by using observed age tracer data and reconstructed history of nitrate contamination by long-term source loading. The 3H-3He and CFC-12 apparent ages, which did not consider the groundwater mixing, estimated the most delayed response time and a highest period of the nitrate loading had not reached yet. However, the lumped parameter model could generate more recent loading response than the apparent ages and the peak loading period influenced the water quality. The numerical model could delineate various groundwater mixing components and its different impacts on nitrate dynamics in the complex aquifer system. The different age estimation methods lead to variations in the estimated contaminant loading history, in which the discrepancy in the age estimation was dominantly observed in the complex aquifer system.

Krypton-81, Helium-4 and Carbon-14 based estimation of groundwater ages in the Guarani Aquifer System: implications for the He-4 geochronometer

Science.gov (United States)

Aggarwal, P. K.; Chang, H. K.; Gastmans, D.; Sturchio, N. C.; Araguas, L.; Matsumoto, T.; Lu, Z.; Jiang, W.; Yokochi, R.; Mueller, P.

2012-12-01

Characterization of aquifer systems remains a challenge, particularly for large aquifers with limited hydrogeological information. Groundwater age is an important parameter that integrates aquifer recharge and flow dynamics and provides the ability to reliably constrain groundwater models. We have used multiple isotope tracers (C-14, He-4, and Kr-81) to estimate the age of groundwater along a 400-km transect in the north-eastern part of the Guarani Aquifer System (GAS) in Brazil. Carbon-14 measurements were made with an AMS, He-4 by mass-spectrometry, and Kr-81 by atom trap trace analysis (ATTA). Groundwater samples were collected along a groundwater flow path that runs from the outcrop area in the east to the deep confined section in the west, where the aquifer is up to about 1000 m deep. Present groundwater recharge occurs in the outcrop areas, as indicated by the presence of tritium and modern 14C. Carbon-14 activities reach values below detection limit at relatively short distances (a few km) from the outcrop. Abundance of 81Kr (half-life 229 Ka), in samples free of C-14, decreases from 0.81±0.11 (expressed as (81Kr/Kr)sample/(81Kr/Kr)air) in the east to 0.18±0.03 in the western-most sample (estimated age = 566±60 ka). Measured 4He-excess is far above that expected from in-situ production rates in sandstone aquifers and overestimates the age by several orders of magnitude. We used 81Kr ages to calibrate the 4He geochronometer which indicates a basal flux of about 2.8 x10-11 cm3STP He/cm2/a. This flux is lower than most estimates of basal flux in previous studies and will allow a wider use of 4He for groundwater dating and aquifer characterization.

TracerLPM (Version 1): An Excel® workbook for interpreting groundwater age distributions from environmental tracer data

Science.gov (United States)

Jurgens, Bryant C.; Böhlke, J.K.; Eberts, Sandra M.

2012-01-01

TracerLPM is an interactive Excel® (2007 or later) workbook program for evaluating groundwater age distributions from environmental tracer data by using lumped parameter models (LPMs). Lumped parameter models are mathematical models of transport based on simplified aquifer geometry and flow configurations that account for effects of hydrodynamic dispersion or mixing within the aquifer, well bore, or discharge area. Five primary LPMs are included in the workbook: piston-flow model (PFM), exponential mixing model (EMM), exponential piston-flow model (EPM), partial exponential model (PEM), and dispersion model (DM). Binary mixing models (BMM) can be created by combining primary LPMs in various combinations. Travel time through the unsaturated zone can be included as an additional parameter. TracerLPM also allows users to enter age distributions determined from other methods, such as particle tracking results from numerical groundwater-flow models or from other LPMs not included in this program. Tracers of both young groundwater (anthropogenic atmospheric gases and isotopic substances indicating post-1940s recharge) and much older groundwater (carbon-14 and helium-4) can be interpreted simultaneously so that estimates of the groundwater age distribution for samples with a wide range of ages can be constrained. TracerLPM is organized to permit a comprehensive interpretive approach consisting of hydrogeologic conceptualization, visual examination of data and models, and best-fit parameter estimation. Groundwater age distributions can be evaluated by comparing measured and modeled tracer concentrations in two ways: (1) multiple tracers analyzed simultaneously can be evaluated against each other for concordance with modeled concentrations (tracer-tracer application) or (2) tracer time-series data can be evaluated for concordance with modeled trends (tracer-time application). Groundwater-age estimates can also be obtained for samples with a single tracer measurement at one

Groundwater recharge and flow on Montserrat, West Indies: Insights from groundwater dating

OpenAIRE

Hemmings, Brioch; Gooddy, Daren; Whitaker, Fiona; George Darling, W.; Jasim, Alia; Gottsmann, Joachim

2015-01-01

Study region Montserrat, Lesser Antilles, Caribbean. Study focus Analysis of δ2H and δ18O isotopes, and chlorofluorocarbon (CFC) anthropogenic tracers in Montserrat groundwater provides insights into the age and provenance of the spring waters. New hydrological insights δ2H and δ18O analysis indicates uniform recharge elevations for groundwaters on Montserrat. CFC-11 and CFC-12 analysis reveals age differences between isotopically similar, high elevation springs and low eleva...

Degradation of sucralose in groundwater and implications for age dating contaminated groundwater.

Science.gov (United States)

Robertson, W D; Van Stempvoort, D R; Spoelstra, J; Brown, S J; Schiff, S L

2016-01-01

The artificial sweetener sucralose has been in use in Canada and the US since about 2000 and in the EU since 2003, and is now ubiquitous in sanitary wastewater in many parts of the world. It persists during sewage treatment and in surface water environments and as such, has been suggested as a powerful tracer of wastewater. In this study, longer-term persistence of sucralose was examined in groundwater by undertaking a series of three sampling snapshots of a well constrained wastewater plume in Canada (Long Point septic system) over a 6-year period from 2008 to 2014. A shrinking sucralose plume in 2014, compared to earlier sampling, during this period when sucralose use was likely increasing, provides clear evidence of degradation. However, depletion of sucralose from a mean of 40 μg/L in the proximal plume zone, occurred at a relatively slow rate over a period of several months to several years. Furthermore, examination of septic tank effluent and impacted groundwater at six other sites in Canada, revealed that sucralose was present in all samples of septic tank effluent (6-98 μg/L, n = 32) and in all groundwater samples (0.7-77 μg/L, n = 64). Even though sucralose degradation is noted in the Long Point plume, its ubiquitous presence in the groundwater plumes at all seven sites implies a relatively slow rate of decay in many groundwater septic plume environments. Thus, sucralose has the potential to be used as an indicator of 'recent' wastewater contamination. The presence of sucralose identifies groundwater that was recharged after 2000 in Canada and the US and after 2003 in the EU and many Asian countries. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of Chemical Indicators of Groundwater Contamination Near the Carcass Burial Site

Science.gov (United States)

Kim, H.; Choi, J.; Kim, M.; Choi, J.; Lee, M.; Lee, H.; Jeon, S.; Bang, S.; Noh, H.; Yoo, J.; Park, S.; Kim, H.; Kim, D.; Lee, Y.; Han, J.

2011-12-01

A serious outbreak of foot and mouth disease (FMD) and avian influenza (AI) led to the culling of millions of livestock in South Korea from late 2010 to earlier 2011. Because of the scale of FMD and AI epidemic in Korea and rapid spread of the diseases, mass burial for the disposal of carcass was conducted to halt the outbreak. The improper construction of the burial site or inappropriate management of the carcass burial facility can cause the contamination of groundwater mainly due to the discharges of leachate through the base of disposal pit. The leachate from carcass burial contains by products of carcass decay such as amino acids, nitrate, ammonia and chloride. The presence of these chemical components in groundwater can be used as indicators demonstrating contamination of groundwater with leachate from carcass. The major concern about using these chemical indicators is that other sources including manures, fertilizers and waste waters from human or animal activities already exist in farming area. However, we lack the understanding of how groundwater contamination due to mass burial of carcass can be differentiated from the contamination due to livestock manures which shows similar chemical characteristics. The chemical compositions of the leachate from carcass burial site and the wastewater from livestock manure treatment facilities were compared. The chemical compositions considered include total organic carbon (TOC), total nitrogen (TN), nitrate, organic nitrogen (Organic nitrogen =TN-Ammonium Nitrogen- Nitrate nitrogen), ammonia, chloride, sodium, potassium and amino acids (20 analytes). The ratios of concentrations of the chemical compositions as indicators of contamination were determined to distinguish the sources of contamination in groundwater. Indicators which showed a linear relationship between two factors and revealed a distinct difference between the carcass leachate and livestock manure were chosen. In addition, the background level of the

Radon as an indicator of submarine groundwater discharge in coastal regions

International Nuclear Information System (INIS)

Jacob, Noble; Shivanna, K.; Suresh Babu, D.S.

2009-01-01

This article reviews the various available methodologies to estimate submarine groundwater discharge (SGD) and demonstrates the utility of radon with a case study. An attempt has been made to identify the existence of submarine groundwater discharge (SGD) and semi-quantitatively estimate its rate in the coastal area of Vizhinjam, Thiruvananthapuram, Kerala. Natural 222 Rn (half-life = 3.8 days) was used as a tracer of SGD because of its conservative nature, short half-life, easiness in measurement and high abundance in groundwater. As in situ radon ( 222 Rn) monitoring study conducted in this region indicated comparatively higher 222 Rn activities (average 14.1±1.7 Bq/m 3 ) in the coastal waters revealing significant submarine groundwater discharge. The SGD may be a combination of fresh groundwater and recirculated seawater that is controlled by the hydraulic gradient in the adjacent aquifer and varying tidal conditions in the coastal waters. Using a transient 222 Rn mass balance model for the coastal waters, SGD rates were computed and the average value was found to be 10.9±6.1 cm/day. These estimates are comparable with those reported in the literature. In general, identification and estimation of submarine groundwater discharge is important in the Indian context because of the possibility of large amounts of groundwater loss through its long coastline, that can be judiciously exploited to cater to the present water requirements for drinking and irrigation purposes. (author)

Dissolved Organic Carbon 14C in Southern Nevada Groundwater and Implications for Groundwater Travel Times

Energy Technology Data Exchange (ETDEWEB)

Hershey, Ronald L. [Nevada University, Reno, NV (United States). Desert Research Institute; Fereday, Wyall [Nevada University, Reno, NV (United States). Desert Research Institute; Thomas, James M [Nevada University, Reno, NV (United States). Desert Research Institute

2016-08-01

Dissolved inorganic carbon (DIC) carbon-14 (¹⁴C) ages must be corrected for complex chemical and physical reactions and processes that change the amount of ¹⁴C in groundwater as it flows from recharge to downgradient areas. Because of these reactions, DIC ¹⁴C can produce unrealistically old ages and long groundwater travel times that may, or may not, agree with travel times estimated by other methods. Dissolved organic carbon (DOC) ¹⁴C ages are often younger than DIC ¹⁴C ages because there are few chemical reactions or physical processes that change the amount of DOC ¹⁴C in groundwater. However, there are several issues that create uncertainty in DOC ¹⁴C groundwater ages including limited knowledge of the initial (A₀) DOC ¹⁴C in groundwater recharge and potential changes in DOC composition as water moves through an aquifer. This study examines these issues by quantifying A₀ DOC ¹⁴C in recharge areas of southern Nevada groundwater flow systems and by evaluating changes in DOC composition as water flows from recharge areas to downgradient areas. The effect of these processes on DOC ¹⁴C groundwater ages is evaluated and DOC and DIC ¹⁴C ages are then compared along several southern Nevada groundwater flow paths. Twenty-seven groundwater samples were collected from springs and wells in southern Nevada in upgradient, midgradient, and downgradient locations. DOC ¹⁴C for upgradient samples ranged from 96 to 120 percent modern carbon (pmc) with an average of 106 pmc, verifying modern DOC ¹⁴C ages in recharge areas, which decreases uncertainty in DOC ¹⁴C A₀ values, groundwater ages, and travel times. The HPLC spectra of groundwater along a flow path in the Spring Mountains show the same general pattern indicating that the DOC compound composition does not change along this flow path

Groundwater flow analysis using radon-222 existing in environment as an indicator

International Nuclear Information System (INIS)

Komae, Takami

1996-01-01

Several kinds of isotopes have been used to trace water movement in the hydrology including surface and ground water as indicators. But those are not effective to analyze the contaminant movement with groundwater though short distance in short time owing to long life. Radon ( 222 Rn) existing in environment was chosen for this purpose as an short-lived indicator. Radon is a radioactive gas, with a half life of 3.8 days, generated from radium ( 226 Ra) in strata. Radon concentration in groundwater increases to reach an equilibrated value within about three weeks after infiltrating underground. The equilibrated concentration becomes an own value of the aquifer depending on the radium content, the grain size and porosity of aquifer. The characteristic makes it able to identify aquifers and sub basins. Since radon concentration in groundwater is 100 to 1000 times as high as that in surface water, groundwater and surface water interaction is quantitatively analyzed. A liquid scintillation counter was employed to measure radon concentration after extracting radon in water to toluene. We applied those advantage of radon-222 to various field investigations and discussed the applicability. It was really possible to analyze the groundwater flow. Monitoring radon concentration in pumped water, occurrences of squeeze and leakage from the different aquifer were detected. Main aquifer was easily determined from the vertical distribution of radon concentration in bore hole. In the injection test using surface water, the spread of injected water was confirmed by the decrease of radon concentration in bore hole water. The radon method was useful to analyze the dam leakage, effluent seepage of groundwater in river, influent seepage of river water underground, and groundwater recharge with irrigation water through unsaturated zone. (author)

Metadata from 12 international groundwater studies: virus and microbial indicator occurrence

Data.gov (United States)

U.S. Environmental Protection Agency — This data set contains raw data from 12 international groundwater studies that monitored for human viruses and microbial indicators. Please see the first worksheet...

Application of multiple-isotope and groundwater-age data to identify factors affecting the extent of denitrification in a shallow aquifer near a river in South Korea

Science.gov (United States)

Kaown, Dugin; Koh, Eun-Hee; Mayer, Bernhard; Kim, Heejung; Park, Dong Kyu; Park, Byeong-Hak; Lee, Kang-Kun

2018-01-01

The extent of denitrification in a small agricultural area near a river in Yangpyeong, South Korea, was determined using multiple isotopes, groundwater age, and physicochemical data for groundwater. The shallow groundwater at one monitoring site had high concentrations of NO3-N (74-83 mg L-1). The δ15N-NO3 values for groundwater in the study area ranged between +9.1 and +24.6‰ in June 2014 and +12.2 to +21.6‰ in October 2014. High δ15N-NO3 values (+10.7 to +12.5‰) in both sampling periods indicated that the high concentrations of nitrate in the groundwater originated from application of organic fertilizers and manure. In the northern part of the study area, some groundwater samples showed elevated δ15N-NO3 and δ18O-NO3 values, which suggest that nitrate was removed from the groundwater via denitrification, with N isotope enrichment factors ranging between -4.8 and -7.9‰ and O isotope enrichment factors varying between -3.8 and -4.9‰. Similar δD and δ18O values of the surface water and groundwater in the south appear to indicate that groundwater in that area was affected by surface-water infiltration. The mean residence times (MRTs) of groundwater showed younger ages in the south (10-20 years) than in the north (20-30 years). Hence, it was concluded that denitrification processes under anaerobic conditions with longer groundwater MRT in the northern part of the study area removed considerable amounts of nitrate. This study demonstrates that multi-isotope data combined with physicochemical data and age-dating information can be effectively applied to characterize nitrate contaminant sources and attenuation processes.

U-ages in soils and groundwater evidencing wet periods 400-600 kyr ago in southeast Brazil

International Nuclear Information System (INIS)

Bonotto, D.M.; Jimenez-Rueda, J.R.

2007-01-01

238 U and its radiogenic daughter 234 U have been utilized for dating soil formation and groundwater residence time during the last 1.5 million years, in this case based on the U-dissolution/precipitation occurring during modifications of the oxidation-reduction conditions. In this paper, we report a 400-600 kyr proxy of wet periods from sediments occurring in a soil profile developed over rocks outcropping at the Parana sedimentary basin in Brazil, and from groundwater exploited of Guarani aquifer at the same basin. The approaches indicated successful use of the U-modeled ages for suggesting wet periods exceeding the past 116-210 kyr from previous studies

Carbon isotope systematics of the Cambrian–Vendian aquifer system in the northern Baltic Basin: Implications to the age and evolution of groundwater

International Nuclear Information System (INIS)

Raidla, Valle; Kirsimäe, Kalle; Vaikmäe, Rein; Kaup, Enn; Martma, Tõnu

2012-01-01

Groundwater in the Cambrian–Vendian aquifer system has a strongly depleted stable isotope composition (δ 18 O values of about −22‰) and a low radiocarbon concentration, which suggests that the water is of glacial origin from the last Ice Age. The aim of this paper was to elucidate the timing of infiltration of glacial waters and to understand the geochemical evolution of this groundwater. The composition of the dissolved inorganic C (DIC) in Cambrian–Vendian groundwater is influenced by complex reactions and isotope exchange processes between water, organic materials and rock matrix. The δ 13 C composition of dissolved inorganic C in Cambrian–Vendian water also indicates a bacterial modification of the isotope system. The corrected radiocarbon ages of groundwater are between 14,000 and 27,000 radiocarbon years, which is coeval with the advance of the Weichselian Glacier in the area.

Characterization of groundwater quality using water evaluation indices, multivariate statistics and geostatistics in central Bangladesh

Directory of Open Access Journals (Sweden)

Md. Bodrud-Doza

2016-04-01

Full Text Available This study investigates the groundwater quality in the Faridpur district of central Bangladesh based on preselected 60 sample points. Water evaluation indices and a number of statistical approaches such as multivariate statistics and geostatistics are applied to characterize water quality, which is a major factor for controlling the groundwater quality in term of drinking purposes. The study reveal that EC, TDS, Ca2+, total As and Fe values of groundwater samples exceeded Bangladesh and international standards. Ground water quality index (GWQI exhibited that about 47% of the samples were belonging to good quality water for drinking purposes. The heavy metal pollution index (HPI, degree of contamination (Cd, heavy metal evaluation index (HEI reveal that most of the samples belong to low level of pollution. However, Cd provide better alternative than other indices. Principle component analysis (PCA suggests that groundwater quality is mainly related to geogenic (rock–water interaction and anthropogenic source (agrogenic and domestic sewage in the study area. Subsequently, the findings of cluster analysis (CA and correlation matrix (CM are also consistent with the PCA results. The spatial distributions of groundwater quality parameters are determined by geostatistical modeling. The exponential semivariagram model is validated as the best fitted models for most of the indices values. It is expected that outcomes of the study will provide insights for decision makers taking proper measures for groundwater quality management in central Bangladesh.

Apparent 85Kr ages of groundwater within the Royal watershed, Maine, USA.

Science.gov (United States)

Sidle, W C

2006-01-01

Specific 85Kr activity is mapped from 264 domestic and municipal wells sampled during 2002-2004 in the Royal watershed (361 km2), Maine. Gas samples are collected at 20 m, 40 m, and > 50 m interval depths within the unconfined aquifers. Gas extraction for 85Kr from wells is obtained directly via a wellhead methodology avoiding conventional collection of large sample volumes. Atmospheric 85Kr input to the recharge environment is estimated at 1.27 Bq m(-3) by time-series analyses of weighted monthly precipitation (2001-2004). Numerical simulation of Kr gas transport through the variable unsaturated zones to the water table suggests up to 12-year time lags locally, thus biasing the 85Kr groundwater ages. Apparent 85Kr ages suggest that approximately 70% of groundwater near 20 m depth was recharged less than 30 years BP (2004). Mass-age transport modeling suggests that post mid-1950s recharge penetrates to part of the basin's floor and that older groundwater seeps from the underlying fractured bedrock may occur.

Establishing indices for groundwater contamination risk assessment in the vicinity of hazardous waste landfills in China

International Nuclear Information System (INIS)

Li Ying; Li Jinhui; Chen Shusheng; Diao Weihua

2012-01-01

Groundwater contamination by leachate is the most damaging environmental impact over the entire life of a hazardous waste landfill (HWL). With the number of HWL facilities in China rapidly increasing, and considering the poor status of environmental risk management, it is imperative that effective environmental risk management methods be implemented. A risk assessment indices system for HWL groundwater contamination is here proposed, which can simplify the risk assessment procedure and make it more user-friendly. The assessment framework and indices were drawn from five aspects: source term, underground media, leachate properties, risk receptors and landfill management quality, and a risk assessment indices system consisting of 38 cardinal indicators was established. Comparison with multimedia models revealed that the proposed indices system was integrated and quantitative, that input data for it could be easily collected, and that it could be widely used for environmental risk assessment (ERA) in China. - Highlights: ► No comprehensive environmental risk assessment method for hazardous waste management is proposed in China. ► An assessment indices system is established for groundwater contamination in the vicinity of hazardous waste landfill. ► All indicators are quantitative and applicable in China. - Capsule: This research identified critical indices and established a system for environmental risk assessment for groundwater contamination in the vicinity of HWLs in China.

Groundwater evolution in the Continental Intercalaire aquifer of southern Algeria and Tunisia: trace element and isotopic indicators

International Nuclear Information System (INIS)

Edmunds, W.M.; Guendouz, A.H.; Mamou, A.; Moulla, A.; Shand, P.; Zouari, K.

2003-01-01

The geochemical processes taking place along an 800 km flow line in the non-carbonate Continental Intercalaire aquifer (CI) aquifer in North Africa are described using chemical (major and trace element) and isotopic indicators. The aquifer is hydraulically continuous from the Atlas Mountains in Algeria to the Chotts of Tunisia and the geochemical evidence corroborates this. The highest discharge temperature is 73 deg. C but silica geothermometry indicates a maximum temperature of 94 deg. C at depth. Chloride concentrations increase from 200 to 800 mg l -1 and the Br/Cl ratios confirm the dissolution of non-marine evaporites or interstitial waters as the main source of salinity. Fluoride concentrations are low and are likely to be derived from rainfall, recording oscillations in source. Radiocarbon ages, except near outcrop, are at or near detection limits and the δ 18 O and δ 2 H values indicate a cooler recharge regime with rainfall having lower primary evaporation than today. This is shown by the fact that mean isotope ratios of CI waters are around 3 per mille lighter than the present-day weighted mean value for rain. Major ion ratios and most trace elements indicate that despite the complex structure and stratigraphy, uniform evolution with continuous water-rock interaction takes place along the flow lines, which are only disturbed near the Tunisian Chotts by groundwater converging from additional flow lines. The ageing of the water can also be followed by the smooth increase in several indicator elements such as Li, K and Mn which are least affected by solubility controls. Similarly the influence of marine facies in the Tunisian sector may be recognised by the changing Mg/Ca and higher Br/Cl as well as trace element indicators. The groundwaters are oxidising up to 300 km from outcrop (dissolved O 2 has persisted for at least 20 ka) and within this zone the concentrations of several elements forming oxy-anions, such as U and Cr, increase and NO 3 remains

Quantifying shallow and deep groundwater inputs to rivers with groundwater dating in hydrological observatories.

Science.gov (United States)

Aquilina, Luc; Marçais, Jean; Gauvain, Alexandre; Kolbe, Tamara; de Dreuzy, Jean-Raynald; Labasque, Thierry; Abbott, Benjamin W.; Vergnaud, Virginie; Chatton, Eliot; Thomas, Zahra; Ruiz, Laurent; Bour, Olivier; Pinay, Gilles

2017-04-01

river from the groundwater age deduced from a deterministic model of the aquifer (Kolbe et al., 2016). The relationship between silica concentration determined with anthropogenic gases and observed silica concentration was strong (R2= 0.54-0.92), indicating that silica was a reliable geochemical chronometer, though it systematically underestimated anthropogenic gas age estimates. The difference could be accounted for by the very young water contribution : approximately 20 - 40% of overall discharge. Both approaches indicated that very young water is particularly important during winter and that deep groundwater contributes at least a third of the river discharge throughout the year. This last result has implications for river nitrate dynamics and understanding the potential limits of catchment management interventions which only reduce nitrate dynamics in shallow groundwater on decadal timescales. Aquilina L. et al., 2012 - Nitrate dynamics in agricultural catchments deduced from groundwater dating and long-term nitrate monitoring in surface- and groundwaters. Sci of the total Environment 435, 167-178. Kolbe et al., 2016 - Coupling 3D groundwater modeling with CFC-based age dating to classify local groundwater circulation in an unconfined crystalline aquifer. J. of Hydrology DOI: 10.1016/j.jhydrol.2016.05.020

Exploring Hydrofluorocarbons as Groundwater Age Tracers (Invited)

Science.gov (United States)

Haase, K. B.; Busenberg, E.; Plummer, L. N.; Casile, G.; Sanford, W. E.

2013-12-01

Groundwater dating tracers are an essential tool for analyzing hydrologic conditions in groundwater systems. Commonly used tracers for dating post-1940's groundwater include sulfur hexafluoride (SF6), chlorofluorocarbons (CFCs), 3H-3He, and other isotopic tracers (85Kr, δ2H and δ18O isotopes, etc.). Each tracer carries a corresponding set of advantages and limitations imposed by field, analytical, and interpretive methods. Increasing the number available tracers is appealing, particularly if they possess inert chemical properties and unique temporal emission histories from other tracers. Atmospherically derived halogenated trace gases continue to hold untapped potential for new tracers, as they are generally inert and their emission histories are well documented. SF5CF3, and CFC-13 were previously shown to have application as dating tracers, though their low mixing ratios and low solubility require large amounts of water to be degassed for their quantification. Two related groups of compounds, hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are hypothesized to be potential age tracers, having similar mixing ratios to the CFCs and relatively high solubility. However, these compounds yield gas chromatography electron capture detector (GC-ECD) responses that are 10-2 -10-5 less than CFC-12, making purge and trap or field stripping GC-ECD approaches impractical. Therefore, in order to use dissolved HCFCs and HFCs as age tracers, different approaches are needed. To solve this problem, we developed an analytical method that uses an atomic emission detector (GC-AED) in place of an ECD to detect fluorinated compounds. In contrast to the ECD, the AED is a universally sensitive, highly linear, elementally specific detector. The new GC-AED system is being used to measure chlorodifluoromethane (HCFC-22), 1,1,1,2-tetrafluoroethane (HFC-134a), and other fluorinated compounds in one liter water samples to study their potential as age dating tracers. HCFC-22 is a

Age determination of ground-waters by means of carbon 14

International Nuclear Information System (INIS)

Eichinger, L.

1982-02-01

At present the age determination of ground-waters aged between 1,500 and approximately 40,000 years is only possible by measuring their 14 C content. A precise age assignment can be established in slightly mineralised waters, whereas it becomes vague in mineralised waters, particularly in acidulous springs. In general, additional information and data are required about the 13 C, D, 18 O, 3 H, 85 Kr and the 39 Ar contents, about the ph value, temperature and the principal ions. (DG) [de

Simulations of Ground-Water Flow, Transport, Age, and Particle Tracking near York, Nebraska, for a Study of Transport of Anthropogenic and Natural Contaminants (TANC) to Public-Supply Wells

Science.gov (United States)

Clark, Brian R.; Landon, Matthew K.; Kauffman, Leon J.; Hornberger, George Z.

2008-01-01

Contamination of public-supply wells has resulted in public-health threats and negative economic effects for communities that must treat contaminated water or find alternative water supplies. To investigate factors controlling vulnerability of public-supply wells to anthropogenic and natural contaminants using consistent and systematic data collected in a variety of principal aquifer settings in the United States, a study of Transport of Anthropogenic and Natural Contaminants to public-supply wells was begun in 2001 as part of the U.S. Geological Survey National Water-Quality Assessment Program. The area simulated by the ground-water flow model described in this report was selected for a study of processes influencing contaminant distribution and transport along the direction of ground-water flow towards a public-supply well in southeastern York, Nebraska. Ground-water flow is simulated for a 60-year period from September 1, 1944, to August 31, 2004. Steady-state conditions are simulated prior to September 1, 1944, and represent conditions prior to use of ground water for irrigation. Irrigation, municipal, and industrial wells were simulated using the Multi-Node Well package of the modular three-dimensional ground-water flow model code, MODFLOW-2000, which allows simulation of flow and solutes through wells that are simulated in multiple nodes or layers. Ground-water flow, age, and transport of selected tracers were simulated using the Ground-Water Transport process of MODFLOW-2000. Simulated ground-water age was compared to interpreted ground-water age in six monitoring wells in the unconfined aquifer. The tracer chlorofluorocarbon-11 was simulated directly using Ground-Water Transport for comparison with concentrations measured in six monitoring wells and one public supply well screened in the upper confined aquifer. Three alternative model simulations indicate that simulation results are highly sensitive to the distribution of multilayer well bores where leakage

Use of multiple age tracers to estimate groundwater residence times and long-term recharge rates in arid southern Oman

International Nuclear Information System (INIS)

Müller, Th.; Osenbrück, K.; Strauch, G.; Pavetich, S.; Al-Mashaikhi, K.-S.; Herb, C.; Merchel, S.; Rugel, G.; Aeschbach, W.; Sanford, W.

2016-01-01

Multiple age tracers were measured to estimate groundwater residence times in the regional aquifer system underlying southwestern Oman. This area, known as the Najd, is one of the most arid areas in the world and is planned to be the main agricultural center of the Sultanate of Oman in the near future. The three isotopic age tracers "4He, "1"4C and "3"6Cl were measured in waters collected from wells along a line that extended roughly from the Dhofar Mountains near the Arabian Sea northward 400 km into the Empty Quarter of the Arabian Peninsula. The wells sampled were mostly open to the Umm Er Radhuma confined aquifer, although, some were completed in the mostly unconfined Rus aquifer. The combined results from the three tracers indicate the age of the confined groundwater is  100 ka in the central section north of the mountains, and up to and > one Ma in the Empty Quarter. The "1"4C data were used to help calibrate the "4He and "3"6Cl data. Mixing models suggest that long open boreholes north of the mountains compromise "1"4C-only interpretations there, in contrast to "4He and "3"6Cl calculations that are less sensitive to borehole mixing. Thus, only the latter two tracers from these more distant wells were considered reliable. In addition to the age tracers, δ"2H and δ"1"8O data suggest that seasonal monsoon and infrequent tropical cyclones are both substantial contributors to the recharge. The study highlights the advantages of using multiple chemical and isotopic data when estimating groundwater travel times and recharge rates, and differentiating recharge mechanisms. - Highlights: • Multiple age tracers are required for the interpretation of the groundwater system. • Different tracers are applicable along different sections of the flowpath. • Groundwater residence times >1 Ma have been determined for the northern Najd area.

Extraction and development of inset models in support of groundwater age calculations for glacial aquifers

Science.gov (United States)

Feinstein, Daniel T.; Kauffman, Leon J.; Haserodt, Megan J.; Clark, Brian R.; Juckem, Paul F.

2018-06-22

treated statistically, may be capable of explaining much of the variance in the simulated age metrics. One example of a predictor that model results indicate strongly affects simulated age is the depth of the well open interval below the simulated water table. The strength of this example variable as an overall predictor of groundwater age and its relation to other predictors can be statistically tested through the metamodeling process. In this way the inset models are designed to serve as a training area for metamodels that estimate groundwater age in glacial wells, which in turn will contribute to ongoing studies, under the direction of the U.S. Geological Survey National Water Quality Assessment, of contaminant susceptibility of shallow groundwater across the glacial aquifer system.

Indicative effects of climate change on groundwater levels in Estonian raised bogs over 50 years

Directory of Open Access Journals (Sweden)

E. Lode

2017-08-01

Full Text Available Analyses of 50-year (1962–2011 monthly air temperature and precipitation data indicated substantial climate change in the locations of two raised bogs (Linnusaare and Männikjärve in central-east Estonia. During recent years the cross-year winter air temperature increased by 1.7 ºC, while the cold-season precipitation increased by 4 mm. The fluctuation amplitude of temperature and precipitation values decreased. Snow depth proved to be the most sensitive variable to winter warming, followed by groundwater levels together with mean and maximum soil frosts. Long-term groundwater levels on the domes of the bogs and in the forested/treed lagg areas were 0.3−0.4 m and 0.4−0.8 m below the soil surface, respectively. Warming caused changes in groundwater level amplitude of 3−22 cm in the bog domes and 3−14 cm in the forested lagg zones. The lowest groundwater levels in ridge-pool ecotopes at Männikjärve rose by 6−10 cm (i.e. these ecotopes became wetter; but the incidence of low groundwater levels increased in most ecotopes, indicating a more general trend towards drier conditions in the bog.

Geohydrology of Big Bear Valley, California: phase 1--geologic framework, recharge, and preliminary assessment of the source and age of groundwater

Science.gov (United States)

Flint, Lorraine E.; Brandt, Justin; Christensen, Allen H.; Flint, Alan L.; Hevesi, Joseph A.; Jachens, Robert; Kulongoski, Justin T.; Martin, Peter; Sneed, Michelle

2012-01-01

Big Bear Valley. The INFILv3 model was modified for this study to include a perched zone beneath the root zone to better simulate lateral seepage and recharge in the shallow subsurface in mountainous terrain. The climate input used in the INFILv3 model was developed by using daily climate data from 84 National Climatic Data Center stations and published Parameter Regression on Independent Slopes Model (PRISM) average monthly precipitation maps to match the drier average monthly precipitation measured in the Baldwin Lake drainage basin. This model resulted in a good representation of localized rain-shadow effects and calibrated well to measured lake volumes at Big Bear and Baldwin Lakes. The simulated average annual recharge was about 5,480 acre-ft/yr in the Big Bear study area, with about 2,800 acre-ft/yr in the Big Bear Lake surface-water drainage basin and about 2,680 acre-ft/yr in the Baldwin Lake surface-water drainage basin. One spring and eight wells were sampled and analyzed for chemical and isotopic data in 2005 and 2006 to determine if isotopic techniques could be used to assess the sources and ages of groundwater in the Big Bear Valley. This approach showed that the predominant source of recharge to the Big Bear Valley is winter precipitation falling on the surrounding mountains. The tritium and uncorrected carbon-14 ages of samples collected from wells for this study indicated that the groundwater basin contains water of different ages, ranging from modern to about 17,200-years old.The results of these investigations provide an understanding of the lateral and vertical extent of the groundwater basin, the spatial distribution of groundwater recharge, the processes responsible for the recharge, and the source and age of groundwater in the groundwater basin. Although the studies do not provide an understanding of the detailed water-bearing properties necessary to determine the groundwater availability of the basin, they do provide a framework for the future

234U/238U activity ratio in groundwater - an indicator of past hydrogeological processes

International Nuclear Information System (INIS)

Rasilainen, K.; Suksi, J.; Marcos, N.; Nordman, H.

2005-01-01

In this report we describe the long-term behaviour of the uranium isotopes, U-234 and U-238 in groundwater systems. U is a redox sensitive element what for its behaviour is largely controlled by changes in the environmental conditions. A striking feature in U isotope geochemistry is seemingly different behaviour of U-238 and U-234. U isotopes fractionate at the rock-groundwater interface depending on chemical and radiological factors. Changes of the redox conditions in groundwater may thus affect the behaviour of U and its isotopes resulting in variable U concentration and U-234/U-238 activity ratios (AR). We examined the formation of ARs in different groundwater types from a geochemical and a physical/radiological point of view. It was envisaged that AR in groundwater is the consequence of radiological, chemical and hydrological processes. Groundwater condition (redox, flow, etc.) play a very important role in controlling the mass flow of U isotopes. Quantitative α-recoil modelling showed that α-recoil induced flux can be considered insignificant in cases of high-flow. This was an important finding because the exclusion of direct a-recoil means that it is groundwater chemistry and its variations which controls the U-234 mass flow and the formation of AR. Therefore, AR values could be used more confidently to indicate past redox changes and possibly flow paths. (orig.)

Distinct kinetics and mechanisms of mZVI particles aging in saline and fresh groundwater: H2 evolution and surface passivation.

Science.gov (United States)

Xin, Jia; Tang, Fenglin; Zheng, Xilai; Shao, Haibing; Kolditz, Olaf; Lu, Xin

2016-09-01

Application of microscale zero-valent iron (mZVI) is a promising technology for in-situ contaminated groundwater remediation; however, its longevity is negatively impacted by surface passivation, especially in saline groundwater. In this study, the aging behavior of mZVI particles was investigated in three media (milli-Q water, fresh groundwater and saline groundwater) using batch experiments to evaluate their potential corrosion and passivation performance under different field conditions. The results indicated that mZVI was reactive for 0-7 days of exposure to water and then gradually lost H2-generating capacity over the next hundred days in all of the tested media. In comparison, mZVI in saline groundwater exhibited the fastest corrosion rate during the early phase (0-7 d), followed by the sharpest kinetic constant decline in the latter phases. The SEM-EDS and XPS analyses demonstrated that in the saline groundwater, a thin and compact oxide film was immediately formed on the surface and significantly shielded the iron reactive site. Nevertheless, in fresh groundwater and milli-Q water, a passive layer composed of loosely and unevenly distributed precipitates slowly formed, with abundant reactive sites available to support continuous iron corrosion. These findings provide insight into the molecular-scale mechanism that governs mZVI passivation and provide implications for long-term mZVI application in saline contaminated groundwater. Copyright © 2016 Elsevier Ltd. All rights reserved.

14C age reassessment of groundwater from the discharge zone due to cross-flow mixing in the deep confined aquifer

Science.gov (United States)

Mao, Xumei; Wang, Hua; Feng, Liang

2018-05-01

In a groundwater flow system, the age of groundwater should gradually increase from the recharge zone to the discharge zone within the same streamline. However, it is occasionally observed that the groundwater age becomes younger in the discharge zone in the piedmont alluvial plain, and the oldest age often appears in the middle of the plain. A new set of groundwater chemistry and isotopes was employed to reassess the groundwater 14C ages from the discharge zone in the North China Plain (NCP). Carbonate precipitation, organic matter oxidation and cross-flow mixing in the groundwater from the recharge zone to the discharge zone are recognized according to the corresponding changes of HCO3- (or DIC) and δ13C in the same streamline of the third aquifer of the NCP. The effects of carbonate precipitation and organic matter oxidation are calibrated with a 13C mixing model and DIC correction, but these corrected 14C ages seem unreasonable because they grow younger from the middle plain to the discharge zone in the NCP. The relationship of Cl- content and the recharge distance is used to estimate the expected Cl- content in the discharge zone, and ln(a14C)/Cl is proposed to correct the a14C in groundwater for the effect of cross-flow mixing. The 14C ages were reassessed with the corrected a14C due to the cross-flow mixing varying from 1.25 to 30.58 ka, and the groundwater becomes older gradually from the recharge zone to the discharge zone. The results suggest that the reassessed 14C ages are more reasonable for the groundwater from the discharge zone due to cross-flow mixing.

Ground-Water Age and Quality in the High Plains Aquifer near Seward, Nebraska, 2003-04

Science.gov (United States)

Stanton, Jennifer S.; Landon, Matthew K.; Turco, Michael J.

2007-01-01

The U.S. Geological Survey, in cooperation with the City of Seward, Nebraska, conducted a study of ground-water age and quality to improve understanding of: (1) traveltimes from recharge areas to public-supply wells, (2) the effects of geochemical reactions in the aquifer on water quality, and (3) how water quality has changed historically in response to land-use practices. Samples were collected from four supply wells in the Seward west well field and from nine monitoring wells along two approximate ground-water flow paths leading to the well field. Concentrations of three different chlorofluorocarbons (CFC-12, CFC-11, and CFC-113), sulfur hexafluoride (SF6), and ratios of tritium (3H) to helium-3 (3He) isotope derived from radioactive decay of 3H were used to determine the apparent recharge age of ground-water samples. Age interpretations were based primarily on 3H/3He and CFC-12 data. Estimates of apparent ground-water age from tracer data were complicated by mixing of water of different ages in 10 of the 13 ground-water samples collected. Apparent recharge dates of unmixed ground-water samples or mean recharge dates of young fractions of mixed water in samples collected from monitoring wells ranged from 1985 to 2002. For monitoring-well samples containing mixed water, the fraction of the sample composed of young water ranged from 26 to 77 percent of the sample. Apparent mean recharge dates of young fractions in samples collected from four supply wells in the Seward west well field ranged from about 1980 to 1990. Estimated fractions of the samples composed of young water ranged from 39 to 54 percent. It is implicit in the mixing calculations that the remainder of the sample that is not young water is composed of water that is more than 60 years old and contains no detectable quantities of modern atmospheric tracers. Estimated fractions of the mixed samples composed of 'old' water ranged from 23 to 74 percent. Although alternative mixing models can be used to

Interpretation of stable isotope, denitrification, and groundwater age data for samples collected from Sandia National Laboratories /New Mexico (SNL/NM) Burn Site Groundwater Area of Concern

Energy Technology Data Exchange (ETDEWEB)

Madrid, V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Singleton, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Visser, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Esser, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-06-02

This report combines and summarizes results for two groundwater-sampling events (October 2012 and October/November 2015) from the Sandia National Laboratories/New Mexico (SNL/NM) Burn Site Groundwater (BSG) Area of Concern (AOC) located in the Lurance Canyon Arroyo southeast of Albuquerque, NM in the Manzanita Mountains. The first phase of groundwater sampling occurred in October 2012 including samples from 19 wells at three separate sites that were analyzed by the Environmental Radiochemistry Laboratory at Lawrence Livermore National Laboratory as part of a nitrate Monitored Natural Attenuation (MNA) evaluation. The three sites (BSG, Technical Area-V, and Tijeras Arroyo) are shown on the regional hydrogeologic map and described in the Sandia Annual Groundwater Monitoring Report. The first phase of groundwater sampling included six monitoring wells at the Burn Site, eight monitoring wells at Technical Area-V, and five monitoring wells at Tijeras Arroyo. Each groundwater sample was analyzed using the two specialized analytical methods, age-dating and denitrification suites. In September 2015, a second phase of groundwater sampling took place at the Burn Site including 10 wells sampled and analyzed by the same two analytical suites. Five of the six wells sampled in 2012 were resampled in 2015. This report summarizes results from two sampling events in order to evaluate evidence for in situ denitrification, the average age of the groundwater, and the extent of recent recharge of the bedrock fracture system beneath the BSG AOC.

Interpretation of stable isotope, denitrification, and groundwater age data for samples collected from Sandia National Laboratories /New Mexico (SNL/NM) Burn Site Groundwater Area of Concern

International Nuclear Information System (INIS)

Madrid, V.; Singleton, M. J.; Visser, A.; Esser, B.

2016-01-01

This report combines and summarizes results for two groundwater-sampling events (October 2012 and October/November 2015) from the Sandia National Laboratories/New Mexico (SNL/NM) Burn Site Groundwater (BSG) Area of Concern (AOC) located in the Lurance Canyon Arroyo southeast of Albuquerque, NM in the Manzanita Mountains. The first phase of groundwater sampling occurred in October 2012 including samples from 19 wells at three separate sites that were analyzed by the Environmental Radiochemistry Laboratory at Lawrence Livermore National Laboratory as part of a nitrate Monitored Natural Attenuation (MNA) evaluation. The three sites (BSG, Technical Area-V, and Tijeras Arroyo) are shown on the regional hydrogeologic map and described in the Sandia Annual Groundwater Monitoring Report. The first phase of groundwater sampling included six monitoring wells at the Burn Site, eight monitoring wells at Technical Area-V, and five monitoring wells at Tijeras Arroyo. Each groundwater sample was analyzed using the two specialized analytical methods, age-dating and denitrification suites. In September 2015, a second phase of groundwater sampling took place at the Burn Site including 10 wells sampled and analyzed by the same two analytical suites. Five of the six wells sampled in 2012 were resampled in 2015. This report summarizes results from two sampling events in order to evaluate evidence for in situ denitrification, the average age of the groundwater, and the extent of recent recharge of the bedrock fracture system beneath the BSG AOC.

Groundwater Flow Computed with Modflow and Isotopic Age Tracer Data in the Continental Intercalaire (Sahara)

Energy Technology Data Exchange (ETDEWEB)

Petersen, J. O.; Goncalves, J.; Deschamps, P.; Hamelin, B. [Centre Europeen de Recherche et d' Enseignement de Geosciences de l' Environnement, Aix-en-Provence (France); Zouari, K. [Laboratoire de Radio-Analyses et Environnement, Sfax (Tunisia); Guendouz, A. [University of Blida, Science Engineering Faculty, Soummaa Blida (Algeria); Michelot, J. -L. [Interactions et Dynamique des Environnements de Surface, Universite Paris-Sud, Orsay (France)

2013-07-15

In one of the largest confined aquifers of the world, the Continental Intercalaire (Sahara), which is located in an arid region (57 mm/y of mean of precipitation), groundwater flow patterns are rather complex. Coupling measurements of isotopic composition of water and age mass calculations obtained by numerical simulations can allow, to a greater extent than a simple comparison, to constrain and validate the recharge scenario, transport and age of groundwater. First, the multiple tracers {sup 14}C, {sup 36}Cl, or {sup 234}U/{sup 238}U used in this study including noble gases such as {sup 4}He, allow investigation of a large range of groundwater ages. Then a MODFLOW simulation is built using (i) the distribution of hydrological parameters, (ii) geometrical limits and iii) the concept of age mass of water, accounting for the tracers data. This approach improves the understanding of the hydrodynamics of this system. In particular, the mixing of old and young waters should be better constrained and the interpretation of paleohydrological conditions is permitted. (author)

Indicators to identify the source of pesticide contamination to groundwater

DEFF Research Database (Denmark)

Thorling, Lærke; Brüsch, Walter; Tuxen, Nina

In Denmark groundwater is synonym with drinking water. The mainstream Danish political approach favors prevention and action at source over advanced treatments of polluted groundwater. The main pollutants are nitrate and pesticides. Pesticides in groundwater can originate from either diffuse or p...

Human virus and microbial indicator occurrence in public-supply groundwater systems: meta-analysis of 12 international studies

Science.gov (United States)

Groundwater quality is often evaluated using microbial indicators. This study examines data from 12 international groundwater studies (conducted 1992–2013). Sites were chosen from 718 public drinking-water systems with a range of hydrogeological conditions. Focus was on testing the value of indicato...

Water ages of 20 groundwater bodies and its relevance for the implementation of the European Water Framework Directive

Science.gov (United States)

Kralik, Martin; Brielmann, Heike; Humer, Franko; Grath, Johannes; Sültenfuß, Jürgen; Philippitsch, Rudolf

2015-04-01

The 'Mean Residence Time' (MRT) of groundwater is required to develop reliable hydrogeological concepts of groundwater bodies as a prerequisite for a qualified monitoring and risk assessment. MRTs from monitoring wells help to assess if groundwater bodies are 'at risk' or 'not at risk' failing to meet good groundwater quantitative and chemical status according to the Water Framework Directive and therefore not being able to use the groundwater as drinking water or industrial water resource. A combination of 18O/2H, 3H, 3H/3He and in some cases additional CFC, SF6, 85Kr and 35S measurements allow to calculate reliable MRTs in 20 groundwater bodies covering 13% (approx.10719 km2) of the Austrian territory. Altogether 401 groundwater wells and springs from the existing groundwater monitoring network were analysed for δ18O (n=1500), 3H (n=800) and 3He (n=327) since 2006. Considering both the fact that monitoring wells may have multiple or long well screens and the inherent uncertainties of groundwater age dating techniques, age estimations were classified into 5 categories of short ( 50years) mean residence times for each monitoring site. Subsequently, median values of the MRT categories were assigned to each investigated groundwater body. These are valuable information to fix extraction rates, to set measures to improve the land use and groundwater protection and to validate hydrogeological concepts. Generally, MRTs of groundwater bodies increase from shallow Alpine groundwater bodies over deeper Alpine valley-aquifers to longer MRTs in the Pannonian climate range in the east of Austria.

Chemical Evolution of Groundwater Near a Sinkhole Lake, Northern Florida: 1. Flow Patterns, Age of Groundwater, and Influence of Lake Water Leakage

Science.gov (United States)

Katz, Brian G.; Lee, Terrie M.; Plummer, L. Niel; Busenberg, Eurybiades

1995-06-01

Leakage from sinkhole lakes significantly influences recharge to the Upper Floridan aquifer in poorly confined sediments in northern Florida. Environmental isotopes (oxygen 18, deuterium, and tritium), chlorofluorocarbons (CFCs: CFC-11, CCl3F; CFC-12, CCl2F2; and CFC-113, C2Cl3F3), and solute tracers were used to investigate groundwater flow patterns near Lake Barco, a seepage lake in a mantled karst setting in northern Florida. Stable isotope data indicated that the groundwater downgradient from the lake contained 11-67% lake water leakage, with a limit of detection of lake water in groundwater of 4.3%. The mixing fractions of lake water leakage, which passed through organic-rich sediments in the lake bottom, were directly proportional to the observed methane concentrations and increased with depth in the groundwater flow system. In aerobic groundwater upgradient from Lake Barco, CFC-modeled recharge dates ranged from 1987 near the water table to the mid 1970s for water collected at a depth of 30 m below the water table. CFC-modeled recharge dates (based on CFC-12) for anaerobic groundwater downgradient from the lake ranged from the late 1950s to the mid 1970s and were consistent with tritium data. CFC-modeled recharge dates based on CFC-11 indicated preferential microbial degradation in anoxic waters. Vertical hydraulic conductivities, calculated using CFC-12 modeled recharge dates and Darcy's law, were 0.17, 0.033, and 0.019 m/d for the surficial aquifer, intermediate confining unit, and lake sediments, respectively. These conductivities agreed closely with those used in the calibration of a three-dimensional groundwater flow model for transient and steady state flow conditions.

Geostatistical analysis of tritium, groundwater age and other noble gas derived parameters in California.

Science.gov (United States)

Visser, A; Moran, J E; Hillegonds, Darren; Singleton, M J; Kulongoski, Justin T; Belitz, Kenneth; Esser, B K

2016-03-15

Key characteristics of California groundwater systems related to aquifer vulnerability, sustainability, recharge locations and mechanisms, and anthropogenic impact on recharge are revealed in a spatial geostatistical analysis of a unique data set of tritium, noble gases and other isotopic analyses unprecedented in size at nearly 4000 samples. The correlation length of key groundwater residence time parameters varies between tens of kilometers ((3)H; age) to the order of a hundred kilometers ((4)Heter; (14)C; (3)Hetrit). The correlation length of parameters related to climate, topography and atmospheric processes is on the order of several hundred kilometers (recharge temperature; δ(18)O). Young groundwater ages that highlight regional recharge areas are located in the eastern San Joaquin Valley, in the southern Santa Clara Valley Basin, in the upper LA basin and along unlined canals carrying Colorado River water, showing that much of the recent recharge in central and southern California is dominated by river recharge and managed aquifer recharge. Modern groundwater is found in wells with the top open intervals below 60 m depth in the southeastern San Joaquin Valley, Santa Clara Valley and Los Angeles basin, as the result of intensive pumping and/or managed aquifer recharge operations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Groundwater flow pattern in the Ruataniwha Plains as derived from the isotope and chemistry signature of the water

International Nuclear Information System (INIS)

Morgenstern, U.; van der Raaij, R.; Baalousha, H.

2012-01-01

The Ruataniwha Basin is situated in the upper Tukituki catchment, approximately 70 km south west of Napier City. The boundaries of the Ruataniwha Basin are the foothills of the Ruahine Range in the west, Turiri Range and Raukawa Range in the east and rolling hills in the north. The Ruataniwha Plains groundwater system is a multi-layered aquifer system that has a complex hydrogeological setting, as the plains evolved in response to sea-level changes, tectonic activity, and geomorphic processes. Aquifers in the basin occur in gravel, sandstone, pumice and limestone strata within a basin structure. In this study, groundwater samples have been collected for hydrochemistry, dissolved gases, and age tracer analysis. Tracer results were interpreted in terms of groundwater recharge source and rate, groundwater age, changes in groundwater source, and the homogeneity of the aquifers. This helps with conceptual understanding of Ruataniwha Basin groundwater flow patterns, and provides data for calibration of a numerical surface-groundwater flow model. Most water samples across the Ruataniwha Basin contain old water, with a mean residence time (MRT) > 25 years. The old age of most of the waters indicates that these groundwaters are not directly linked to surface water. In the south eastern part of the basin, all groundwater samples are old (>100 years), indicating slow movement of groundwater and slow recharge, consistent with the geology of the area. In the south eastern part of the basin the geologic units have low permeability. The age depth relationship is biased by upwelling groundwater and reflects the closed nature of the basin. The average vertical flow velocity indicates a recharge rate of 0.19 m/y. Four wells in the vicinity of the lower Waipawa River show excellent age-depth relationships, indicating absence of disturbance by groundwater upwelling. The recharge rate there of 0.42 m/y is substantially higher than in the other parts of the basin, indicating river

Radiocarbon dating of groundwater in tertiary sediments of the eastern Murray Basin

International Nuclear Information System (INIS)

Drury, L.W.; Calf, G.E.

1984-01-01

The Tertiary sediments located in the eastern part of the Murray Basin contain one of the most important low salinity groundwater resources in New South Wales. It is imperative that the hydrogeological environment in which the groundwater occurs be thoroughly understood to allow adequate management of the resource. A radiocarbon dating project was carried out on 37 groundwater samples from bores screened in these unconsolidated sediments. The results indicate water ages in the range 'modern' to 15 800 years. Groundwater recharge areas are indicated and rates of groundwater recharge and movement determined. The latter shows close correlation with velocity values quantitatively determined by Darcy's law

Radiocarbon dating of groundwater in Tertiary sediments of the eastern Murray Basin

Energy Technology Data Exchange (ETDEWEB)

Drury, L.W. (Water Resources Commission of New South Wales, Sydney (Australia)); Calf, G.E. (Australian Atomic Energy Commission Research Establishment, Lucas Heights. Isotope Div.); Dharmasiri, J.K. (Colombo Univ. (Sri Lanka))

1984-01-01

The Tertiary sediments located in the eastern part of the Murray Basin contain one of the most important low salinity groundwater resources in New South Wales. It is imperative that the hydrogeological environment in which the groundwater occurs be thoroughly understood to allow adequate management of the resource. A radiocarbon dating project was carried out on 37 groundwater samples from bores screened in these unconsolidated sediments. The results indicate water ages in the range 'modern' to 15 800 years. Groundwater recharge areas are indicated and rates of groundwater recharge and movement determined. The latter shows close correlation with velocity values quantitatively determined by Darcy's law.

Analysis and determination of age of oil spills in soil and groundwater

International Nuclear Information System (INIS)

Hoedl, P.; Schindlbauer, H.

1995-01-01

The extensive searching for hydrocarbon-based spills in soil and groundwater during the last few years rises the question of whom caused these contaminations. The answer to this very specific question is not easy and often requires the exact determination of age of the contamination. Therefore, the sampling of all imaginable data around the spilled material is necessary. Beginning at the precise check-up of the geological surrounding, including the definition of the condition and construction of the soil as well as the determination of the flow-direction of the groundwater, the chemical analysis should describe the containing substances and/or the products in the best possible way. Summing all these data and taking into consideration of the well-known microbiological pathways of decomposition for one- and/or a group of substances, it should be possible to determine the age of a contamination. (orig.) [de

The Study of Groundwater Age in Semarang Area Considering Beta Activityof Tritium

International Nuclear Information System (INIS)

F, Wisjachudin; Agus-Sulistiyono; Fajar-Budi Haendrapratikto

2000-01-01

The groundwater age in Semarang regency, they are Genuk, Pedurungan,North Semarang, Urban Semarang, Mijen, Mangkang, Manyaran, Tembalang, Sekaranconsidering tritium content inside has been done. Tritium content ingroundwater given pretreatment that is enriching tritium content usingsynthesize technique by benzene synthesizer (H 2 O converted into C 6 H 6 ).Tritium activity in C 6 H 6 was analyzed using liquid scintillation counterPackard 2000 CA/LL. Optimum condition of volume ratio between cocktail(picofluor) and sample solution is reached ratio of 10 : 10. Efficiencydetection (ε) = 42.16 %, while merit factor = 1.981.10 5 . From twolocations that can be detected show that analysis on groundwater age onManyaran location (damar formation) is younger than Urban Semarang (alluviumsediment), which is match to geological analysis considering geological layershows that on geology layer of volcanic breksi layer is younger than damarformation area and the oldest is the alluvium sediment area. (author)

Using StorAge Selection Functions to Improve Simulation of Groundwater Nitrate Lag Times in the SWAT Modeling Framework.

Science.gov (United States)

Wilusz, D. C.; Fuka, D.; Cho, C.; Ball, W. P.; Easton, Z. M.; Harman, C. J.

2017-12-01

Intensive agriculture and atmospheric deposition have dramatically increased the input of reactive nitrogen into many watersheds worldwide. Reactive nitrogen can leach as nitrate into groundwater, which is stored and eventually released over years to decades into surface waters, potentially degrading water quality. To simulate the fate and transport of groundwater nitrate, many researchers and practitioners use the Soil and Water Assessment Tool (SWAT) or an enhanced version of SWAT that accounts for topographically-driven variable source areas (TopoSWAT). Both SWAT and TopoSWAT effectively assume that nitrate in the groundwater reservoir is well-mixed, which is known to be a poor assumption at many sites. In this study, we describe modifications to TopoSWAT that (1) relax the assumption of groundwater well-mixedness, (2) more flexibly parameterize groundwater transport as a time-varying distribution of travel times using the recently developed theory of rank StorAge Selection (rSAS) functions, and (3) allow for groundwater age to be represented by position on the hillslope or hydrological distance from the stream. The approach conceptualizes the groundwater aquifer as a population of water parcels entering as recharge with a particular nitrate concentration, aging as they move through storage, and eventually exiting as baseflow. The rSAS function selects the distribution of parcel ages that exit as baseflow based on a parameterized probability distribution; this distribution can be adjusted to preferentially select different distributions of young and old parcels in storage so as to reproduce (in principle) any form of transport. The modified TopoSWAT model (TopoSWAT+rSAS) is tested at a small agricultural catchment in the Eastern Shore, MD with an extensive hydrologic and hydrochemical data record for calibration and evaluation. The results examine (1) the sensitivity of TopoSWAT+rSAS modeling of nitrate transport to assumptions about the distribution of travel

Constructing Regional Groundwater Models from Geophysical Data of Varying Type, Age, and Quality

DEFF Research Database (Denmark)

Vest Christiansen, Anders; Auken, Esben; Marker, Pernille Aabye

for parameterization of a 3D model of the subsurface, integrating lithological information from boreholes with resistivity models. The objective is to create a direct input to regional groundwater models for sedimentary areas, where the sand/clay distribution governs the groundwater flow. The resistivity input is all......-inclusive in the sense that we include data from a variety of instruments (DC and EM, ground-based and airborne), with a varying spatial density and varying ages and quality. The coupling between hydrological and geophysical parameters is managed using a translator function with spatially variable parameters, which...

Use of multiple age tracers to estimate groundwater residence times and long-term recharge rates in arid southern Oman

Science.gov (United States)

Müller, Th.; Osenbrück, K.; Strauch, G.; Pavetich, S.; Al-Mashaikhi, K.-S.; Herb, C.; Merchel, S.; Rugel, G.; Aeschbach, W.; Sanford, Ward E.

2016-01-01

Multiple age tracers were measured to estimate groundwater residence times in the regional aquifer system underlying southwestern Oman. This area, known as the Najd, is one of the most arid areas in the world and is planned to be the main agricultural center of the Sultanate of Oman in the near future. The three isotopic age tracers 4He, 14C and 36Cl were measured in waters collected from wells along a line that extended roughly from the Dhofar Mountains near the Arabian Sea northward 400 km into the Empty Quarter of the Arabian Peninsula. The wells sampled were mostly open to the Umm Er Radhuma confined aquifer, although, some were completed in the mostly unconfined Rus aquifer. The combined results from the three tracers indicate the age of the confined groundwater is  100 ka in the central section north of the mountains, and up to and > one Ma in the Empty Quarter. The 14C data were used to help calibrate the 4He and 36Cl data. Mixing models suggest that long open boreholes north of the mountains compromise 14C-only interpretations there, in contrast to 4He and 36Cl calculations that are less sensitive to borehole mixing. Thus, only the latter two tracers from these more distant wells were considered reliable. In addition to the age tracers, δ2H and δ18O data suggest that seasonal monsoon and infrequent tropical cyclones are both substantial contributors to the recharge. The study highlights the advantages of using multiple chemical and isotopic data when estimating groundwater travel times and recharge rates, and differentiating recharge mechanisms.

Calibration of a transient transport model to tritium data in streams and simulation of groundwater ages in the western Lake Taupo catchment, New Zealand

Directory of Open Access Journals (Sweden)

M. A. Gusyev

2013-03-01

Full Text Available Here we present a general approach of calibrating transient transport models to tritium concentrations in river waters developed for the MT3DMS/MODFLOW model of the western Lake Taupo catchment, New Zealand. Tritium has a known pulse-shaped input to groundwater systems due to the bomb tritium in the early 1960s and, with its radioactive half-life of 12.32 yr, allows for the determination of the groundwater age. In the transport model, the tritium input (measured in rainfall passes through the groundwater system, and the simulated tritium concentrations are matched to the measured tritium concentrations in the river and stream outlets for the Waihaha, Whanganui, Whareroa, Kuratau and Omori catchments from 2000–2007. For the Kuratau River, tritium was also measured between 1960 and 1970, which allowed us to fine-tune the transport model for the simulated bomb-peak tritium concentrations. In order to incorporate small surface water features in detail, an 80 m uniform grid cell size was selected in the steady-state MODFLOW model for the model area of 1072 km2. The groundwater flow model was first calibrated to groundwater levels and stream baseflow observations. Then, the transient tritium transport MT3DMS model was matched to the measured tritium concentrations in streams and rivers, which are the natural discharge of the groundwater system. The tritium concentrations in the rivers and streams correspond to the residence time of the water in the groundwater system (groundwater age and mixing of water with different age. The transport model output showed a good agreement with the measured tritium values. Finally, the tritium-calibrated MT3DMS model is applied to simulate groundwater ages, which are used to obtain groundwater age distributions with mean residence times (MRTs in streams and rivers for the five catchments. The effect of regional and local hydrogeology on the simulated groundwater ages is investigated by demonstrating groundwater ages

Effects of aged sorption on pesticide leaching to groundwater simulated with PEARL

NARCIS (Netherlands)

Boesten, Jos J.T.I.

2017-01-01

Leaching to groundwater is an important element of the regulatory risk assessment of pesticides in western countries. Including aged sorption in this assessment is relevant because there is ample evidence of this process and because it leads to a decrease in simulated leaching. This work assesses

Age dating and flow path evaluation of groundwater by SF6 and microbe in the foot of Mt. Fuji, central Japan

Science.gov (United States)

Yamamoto, Chisato; Tsujimura, Maki; Kato, Kenji; Nagaosa, Kazuyo; Sakakibara, Koichi; Umei, Yohei; Ohara, Kazuma

2016-04-01

A variety of industries are developed at the foot of volcanic mountains in Japan and the groundwater is major source for industrial activity in those regions. The age of groundwater has been estimated to be from 10 to 30 years in Mt. Fuji regions by using 36Cl and 3H. However, the age has not been evaluated using SF6 with higher time resolution in these regions. Also, the total number of prokaryotes shows a specific value in each spring water, suggesting different path and age of the groundwater. Therefore, we aim to estimate residence time and the groundwater flow in three dimensions using the multi-tracers approach; CFCs, SF6, the total number of prokaryotes, the stable isotopes of oxygen-18, deuterium. We collected totally 25 spring water samples in Mt. Fuji and analyzed concentration of inorganic ions, the stable isotopes of oxygen-18, deuterium, CFCs, SF6. The apparent age of the spring water was estimated to be ranging from 4 to 19 years at the foot of Mt. Fuji. These results are reasonable as considering the existed age data by36Cl (Tosaki, 2008) in this region. The spring water with younger age tends to show higher total number of prokaryotes, suggesting that the groundwater flows dominantly through the shallow and young lava with the higher total number of prokaryotes, leads to younger age. Focusing on a specific spring water, the seasonal change of SF6 and total number of prokaryotes were monitored. The spring water showed a younger age and higher total number of prokaryotes during the high water flow season, whereas it showed an older age and lower total number of prokaryotes. Therefore, the total number of prokaryotes shows a good negative correlation with the residence time of the spring/ groundwater in space and time. This shows a possibility that the total number of prokaryotes could be a useful tracer of groundwater for time and space in the three dimensions information.

Establishing indices for groundwater contamination risk assessment in the vicinity of hazardous waste landfills in China.

Science.gov (United States)

Li, Ying; Li, Jinhui; Chen, Shusheng; Diao, Weihua

2012-06-01

Groundwater contamination by leachate is the most damaging environmental impact over the entire life of a hazardous waste landfill (HWL). With the number of HWL facilities in China rapidly increasing, and considering the poor status of environmental risk management, it is imperative that effective environmental risk management methods be implemented. A risk assessment indices system for HWL groundwater contamination is here proposed, which can simplify the risk assessment procedure and make it more user-friendly. The assessment framework and indices were drawn from five aspects: source term, underground media, leachate properties, risk receptors and landfill management quality, and a risk assessment indices system consisting of 38 cardinal indicators was established. Comparison with multimedia models revealed that the proposed indices system was integrated and quantitative, that input data for it could be easily collected, and that it could be widely used for environmental risk assessment (ERA) in China. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Suitability of artificial sweeteners as indicators of raw wastewater contamination in surface water and groundwater.

Science.gov (United States)

Tran, Ngoc Han; Hu, Jiangyong; Li, Jinhua; Ong, Say Leong

2014-01-01

There is no quantitative data on the occurrence of artificial sweeteners in the aquatic environment in Southeast Asian countries, particularly no information on their suitability as indicators of raw wastewater contamination on surface water and groundwater. This study provided the first quantitative information on the occurrence of artificial sweeteners in raw wastewater, surface water and groundwater in the urban catchment area in Singapore. Acesulfame, cyclamate, saccharin, and sucralose were ubiquitous in raw wastewater samples at concentrations in the range of ng/L-μg/L, while other sweeteners were not found or found only in a few of the raw wastewater samples. Residential and commercial effluents were demonstrated to be the two main sources of artificial sweeteners entering the municipal sewer systems. Relatively higher concentrations of the detected sweeteners were frequently found in surface waters at the sampling sites located in the residential/commercial areas. No significant difference in the concentrations of the detected sweeteners in surface water or groundwater was noted between wet and dry weather conditions (unpaired T-test, p> 0.05). Relatively higher concentrations and detection frequencies of acesulfame, cyclamate and saccharin in surface water samples were observed at the potentially impacted sampling sites, while these sweeteners were absent in most of the background surface water samples. Similarly, acesulfame, cyclamate, and saccharin were found in most groundwater samples at the monitoring well (GW6), which is located close to known leaking sewer segment; whereas these were absent in the background monitoring well, which is located in the catchment with no known wastewater sources. Taken together, the results suggest that acesulfame, cyclamate, and saccharin can be used as potential indicators of raw wastewater contamination in surface water and groundwater. Copyright © 2013 Elsevier Ltd. All rights reserved.

Trend Analyses of Nitrate in Danish Groundwater

DEFF Research Database (Denmark)

Hansen, B.; Thorling, L.; Dalgaard, Tommy

2012-01-01

This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribut......This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis...... of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first...... two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded...

Methods of investigation and analysis on groundwater using radon as an indicator

International Nuclear Information System (INIS)

Hamada, Hiromasa; Imaizumi, Masayuki; Komae, Takami

1997-01-01

As for groundwater, the quality is good, and the temperature is constant throughout year, further, it can be easily utilized only by digging wells. The quantity of its utilization in one year is about 20% of total water utilization, and about 17 billion m 3 . Recently in Japan, the frequency of occurrence of water shortage is high, and the supply of river water is unstable, therefore, the importance of groundwater increased. It is indispensable to grasp in detail the state of groundwater flow as groundwater pollution is actualized, and the water quality has become problem. As the principle that radon becomes the index for groundwater analysis, the physical characteristic of radon and the features of the radon in groundwater are explained. The method of measuring radon concentration in groundwater and surface water is described. The investigation and analysis methods, to which the processes of radon formation and radon decay are applied, in which the equilibrium radon concentration in groundwater is used as the index, to which the relation of the degree of saturation in aquifer to the radon concentration in liquid phase is applied, and to which the difference of the concentrations in surface water and groundwater is applied, are reported. (K.I.)

Uncertainty in 14C model ages of groundwater: The influence of soil gas in terranes dominated by C3 plants

Science.gov (United States)

Nelson, S.; Hart, R.; Eggett, D.

2009-12-01

groundwater age models due to the choice of soil gas δ13C inputs. However, differences in the mean values changes calculated groundwater ages by about 800 years. Due to diffusive exchange, δ13C values of carbon dioxide in the soil zone vary between -8‰ at the soil/atmosphere interface and a steady state value of ˜ -23‰ at depth, thus greatly increasing the uncertainty in the choice of model input values depending on where in the soil column recharge water acquires its dissolved gas. Direct measurement, inverse models, and forward models of δ13C gradients indicate that during recharge events, the occupation of >50% of dry pore space by water decreases the effective gas porosity and increases the tortuosity to such a degree that large isotopic gradients between soil and atmospheric carbon dioxide are effectively erased at depths below 10 to 20 cm. As a result, although assumptions must be clearly stated and resulting groundwater ages are model dependent, increased precision in 14C ages of groundwater can be obtained, especially for temperate climates dominated by C3 flora.

Geochemistry and environmental isotope of groundwater from the upper Cretaceous aquifer of Orontes basin (Syria)

International Nuclear Information System (INIS)

Al-Charideh, A.

2010-03-01

Chemical and environmental isotopes have been used for studying the Upper Cretaceous aquifer systems in the Middle Orontes basin. The results indicate that the salinity of groundwater (0.2 to 2 g/l) reveals the dissolution of evaporate rocks is the main factor of high salinity especially in the Homes depression. The degree of salinity and its spaces distribution are basically related to the pattern of groundwater movement in the Upper cretaceous aquifer. The stable isotopes composition of groundwater in the Homes depression are more depleted by -2.5% and -17.0% for δ 18 O and δ 2 H respectively, than the groundwater from Hama elevation, suggested different origin and recharge time between this two groundwater groups. Estimates of their mean subsurface residence times have been constrained on the basis of 14 C D IC. The corrected ages of groundwater are recent and less to 10 thousand years in Hama uplift. However, the corrected age of groundwater in the Homs depression range between 10 to 25 thousand years indicate late Pleistocene recharge period. (author)

Pharmaceuticals as indicators of anthropogenic influence on the groundwater of Ljubljansko polje and Ljubljansko barje aquifers

Directory of Open Access Journals (Sweden)

Karin Lah

2009-12-01

Full Text Available The attention of numerous researches has been recently focused on the determination of pharmaceuticals and other persistent chemicals in the environment. The substances enter groundwater either thorough direct discharge or indirectly (through surface or waste water. Pharmaceuticals in groundwater can be regarded as artificial tracers that enable the evaluation of general anthropogenic influence on the environment and identification of the most vulnerable areas of aquifers.The article presents the properties of distribution of caffeine, carbamazepine and propyphenazone in the area of Ljubljansko polje and Ljubljansko barje. Ljubljansko polje and Barje are important drinking water resources. These pollutants are indicators of sewage system efficiency,however,in urban areas without sewage they indicate the aquifer’s ability of natural attenuation.

Ensemble models on palaeoclimate to predict India's groundwater challenge

Directory of Open Access Journals (Sweden)

Partha Sarathi Datta

2013-09-01

Full Text Available In many parts of the world, freshwater crisis is largely due to increasing water consumption and pollution by rapidly growing population and aspirations for economic development, but, ascribed usually to the climate. However, limited understanding and knowledge gaps in the factors controlling climate and uncertainties in the climate models are unable to assess the probable impacts on water availability in tropical regions. In this context, review of ensemble models on δ18O and δD in rainfall and groundwater, 3H- and 14C- ages of groundwater and 14C- age of lakes sediments helped to reconstruct palaeoclimate and long-term recharge in the North-west India; and predict future groundwater challenge. The annual mean temperature trend indicates both warming/cooling in different parts of India in the past and during 1901–2010. Neither the GCMs (Global Climate Models nor the observational record indicates any significant change/increase in temperature and rainfall over the last century, and climate change during the last 1200 yrs BP. In much of the North-West region, deep groundwater renewal occurred from past humid climate, and shallow groundwater renewal from limited modern recharge over the past decades. To make water management to be more responsive to climate change, the gaps in the science of climate change need to be bridged.

Plants as bio-indicators of subsurface conditions: impact of groundwater level on BTEX concentrations in trees.

Science.gov (United States)

Wilson, Jordan; Bartz, Rachel; Limmer, Matt; Burken, Joel

2013-01-01

Numerous studies have demonstrated trees' ability to extract and translocate moderately hydrophobic contaminants, and sampling trees for compounds such as BTEX can help delineate plumes in the field. However, when BTEX is detected in the groundwater, detection in nearby trees is not as reliable an indicator of subsurface contamination as other compounds such as chlorinated solvents. Aerobic rhizospheric and bulk soil degradation is a potential explanation for the observed variability of BTEX in trees as compared to groundwater concentrations. The goal of this study was to determine the effect of groundwater level on BTEX concentrations in tree tissue. The central hypothesis was increased vadose zone thickness promotes biodegradation of BTEX leading to lower BTEX concentrations in overlying trees. Storage methods for tree core samples were also investigated as a possible reason for tree cores revealing lower than expected BTEX levels in some sampling efforts. The water level hypothesis was supported in a greenhouse study, where water table level was found to significantly affect tree BTEX concentrations, indicating that the influx of oxygen coupled with the presence of the tree facilitates aerobic biodegradation of BTEX in the vadose zone.

Human enteric viruses in groundwater indicate offshore transport of human sewage to coral reefs of the Upper Florida Keys

Science.gov (United States)

Futch, J. Carrie; Griffin, Dale W.; Lipp, Erin K.

2010-01-01

To address the issue of human sewage reaching corals along the main reef of the Florida Keys, samples were collected from surface water, groundwater and coral [surface mucopolysaccharide layers (SML)] along a 10 km transect near Key Largo, FL. Samples were collected semi-annually between July 2003 and September 2005 and processed for faecal indicator bacteria (faecal coliform bacteria, enterococci and Clostridium perfringens) and human-specific enteric viruses (enterovirus RNA and adenovirus DNA) by (RT)-nested polymerase chain reaction. Faecal indicator bacteria concentrations were generally higher nearshore and in the coral SML. Enteric viruses were evenly distributed across the transect stations. Adenoviruses were detected in 37 of 75 samples collected (49.3%) whereas enteroviruses were only found in 8 of 75 samples (10.7%). Both viruses were detected twice as frequently in coral compared with surface water or groundwater. Offshore, viruses were most likely to be found in groundwater, especially during the wet summer season. These data suggest that polluted groundwater may be moving to the outer reef environment in the Florida Keys.

Using dissolved gases to observe the evolution of groundwater age in a mountain watershed over a period of thirteen years

Science.gov (United States)

Manning, Andrew H.

2011-01-01

Baseflows in snowmelt-dominated mountain streams are critical for sustaining ecosystems and water resources during periods of greatest demand. Future climate predictions for mountainous areas throughout much of the western U.S. include increasing temperatures, declining snowpacks, and earlier snowmelt periods. The degree to and rate at which these changes will affect baseflows in mountain streams remains unknown, largely because baseflows are groundwater-fed and the relationship between climate and groundwater recharge/discharge rates in mountain watersheds is uncertain. We use groundwater age determinations from multiple dissolved gas tracers (CFCs, SF6, and 3H/3He) to track changes in groundwater age over a period of thirteen years in the Sagehen Creek watershed, Sierra Nevada Mountains, CA. Data were collected from springs and wells in 2009 and 2010 and combined with those obtained in prior studies from 1997 to 2003. Apparent ages range from 0 to >60 years. Comparison between variations in age and variations in snow water equivalent (SWE) and mean annual air temperature reveals the degree of correlation between these climate variables and recharge rate. Further, comparison of apparent ages from individual springs obtained at different times and using different tracers helps constrain the age distribution in the sampled waters. The age data are generally more consistent with an exponential age distribution than with piston-flow. However, many samples, even those with relatively old mean ages, must have a disproportionately large very young fraction that responds directly to annual SWE variations. These findings have important implications for how future baseflows may respond to decreasing SWE.

Groundwater mixing and mineralization processes in a mountain-oasis-desert basin, northwest China: hydrogeochemistry and environmental tracer indicators

Science.gov (United States)

Ma, Bin; Jin, Menggui; Liang, Xing; Li, Jing

2018-02-01

Hydrogeochemistry and environmental tracers (2H, 18O, 87Sr/86Sr) in precipitation, river and reservoir water, and groundwater have been used to determine groundwater recharge sources, and to identify mixing characteristics and mineralization processes in the Manas River Basin (MRB), which is a typical mountain-oasis-desert ecosystem in arid northwest China. The oasis component is artificial (irrigation). Groundwater with enriched stable isotope content originates from local precipitation and surface-water leakage in the piedmont alluvial-oasis plain. Groundwater with more depleted isotopes in the north oasis plain and desert is recharged by lateral flow from the adjacent mountains, for which recharge is associated with high altitude and/or paleo-water infiltrating during a period of much colder climate. Little evaporation and isotope exchange between groundwater and rock and soil minerals occurred in the mountain, piedmont and oasis plain. Groundwater δ2H and δ18O values show more homogeneous values along the groundwater flow direction and with well depths, indicating inter-aquifer mixing processes. A regional contrast of groundwater allows the 87Sr/86Sr ratios and δ18O values to be useful in a combination with Cl, Na, Mg, Ca and Sr concentrations to distinguish the groundwater mixing characteristics. Two main processes are identified: groundwater lateral-flow mixing and river leakage in the piedmont alluvial-oasis plain, and vertical mixing in the north oasis plain and the desert. The 87Sr/86Sr ratios and selected ion ratios reveal that carbonate dissolution and mixing with silicate from the southern mountain area are primarily controlling the strontium isotope hydrogeochemistry.

Using geochemistry to identify the source of groundwater to Montezuma Well, a natural spring in Central Arizona, USA: Part 2

Science.gov (United States)

Johnson, Raymond H.; DeWitt, Ed; Wirt, Laurie; Manning, Andrew H.; Hunt, Andrew G.

2012-01-01

Montezuma Well is a unique natural spring located in a sinkhole surrounded by travertine. Montezuma Well is managed by the National Park Service, and groundwater development in the area is a potential threat to the water source for Montezuma Well. This research was undertaken to better understand the sources of groundwater to Montezuma Well. Strontium isotopes (87Sr/86Sr) indicate that groundwater in the recharge area has flowed through surficial basalts with subsequent contact with the underlying Permian aged sandstones and the deeper, karstic, Mississippian Redwall Limestone. The distinctive geochemistry in Montezuma Well and nearby Soda Springs (higher concentrations of alkalinity, As, B, Cl, and Li) is coincident with added carbon dioxide and mantle-sourced He. The geochemistry and isotopic data from Montezuma Well and Soda Springs allow for the separation of groundwater samples into four categories: (1) upgradient, (2) deep groundwater with carbon dioxide, (3) shallow Verde Formation, and (4) mixing zone. δ18O and δD values, along with noble gas recharge elevation data, indicate that the higher elevation areas to the north and east of Montezuma Well are the groundwater recharge zones for Montezuma Well and most of the groundwater in this portion of the Verde Valley. Adjusted groundwater age dating using likely 14C and δ13C sources indicate an age for Montezuma Well and Soda Springs groundwaters at 5,400–13,300 years, while shallow groundwater in the Verde Formation appears to be older (18,900). Based on water chemistry and isotopic evidence, groundwater flow to Montezuma Well is consistent with a hydrogeologic framework that indicates groundwater flow by (1) recharge in higher elevation basalts to the north and east of Montezuma Well, (2) movement through the upgradient Permian and Mississippian units, especially the Redwall Limestone, and (3) contact with a basalt dike/fracture system that provides a mechanism for groundwater to flow to the surface

Groundwater quality, age, and susceptibility and vulnerability to nitrate contamination with linkages to land use and groundwater flow, Upper Black Squirrel Creek Basin, Colorado, 2013

Science.gov (United States)

Wellman, Tristan P.; Rupert, Michael G.

2016-03-03

The Upper Black Squirrel Creek Basin is located about 25 kilometers east of Colorado Springs, Colorado. The primary aquifer is a productive section of unconsolidated deposits that overlies bedrock units of the Denver Basin and is a critical resource for local water needs, including irrigation, domestic, and commercial use. The primary aquifer also serves an important regional role by the export of water to nearby communities in the Colorado Springs area. Changes in land use and development over the last decade, which includes substantial growth of subdivisions in the Upper Black Squirrel Creek Basin, have led to uncertainty regarding the potential effects to water quality throughout the basin. In response, the U.S. Geological Survey, in cooperation with Cherokee Metropolitan District, El Paso County, Meridian Service Metropolitan District, Mountain View Electric Association, Upper Black Squirrel Creek Groundwater Management District, Woodmen Hills Metropolitan District, Colorado State Land Board, and Colorado Water Conservation Board, and the stakeholders represented in the Groundwater Quality Study Committee of El Paso County conducted an assessment of groundwater quality and groundwater age with an emphasis on characterizing nitrate in the groundwater.

Geochemical Investigations of Groundwater Stability

International Nuclear Information System (INIS)

Bath, Adrian

2006-05-01

The report describes geochemical parameters and methods that provide information about the hydrodynamic stability of groundwaters in low permeability fractured rocks that are potential hosts for radioactive waste repositories. Hydrodynamic stability describes the propensity for changes in groundwater flows over long timescales, in terms of flow rates and flow directions. Hydrodynamic changes may also cause changes in water compositions, but the related issue of geochemical stability of a potential repository host rock system is outside the scope of this report. The main approaches to assessing groundwater stability are numerical modelling, measurement and interpretation of geochemical indicators in groundwater compositions, and analyses and interpretations of secondary minerals and fluid inclusions in these minerals. This report covers the latter two topics, with emphasis on geochemical indicators. The extent to which palaeohydrogeology and geochemical stability indicators have been used in past safety cases is reviewed. It has been very variable, both in terms of the scenarios considered, the stability indicators considered and the extent to which the information was explicitly or implicitly used in assessing FEPs and scenarios in the safety cases. Geochemical indicators of hydrodynamic stability provide various categories of information that are of hydrogeological relevance. Information about groundwater mixing, flows and water sources is potentially provided by the total salinity of groundwaters, their contents of specific non-reactive solutes (principally chloride) and possibly of other solutes, the stable isotopic ratio of water, and certain characteristics of secondary minerals and fluid inclusions. Information pertaining directly to groundwater ages and the timing of water and solute movements is provided by isotopic systems including tritium, carbon-14, chlorine-36, stable oxygen and hydrogen isotopes, uranium isotopes and dissolved mobile gases in

Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination

Science.gov (United States)

Jasechko, Scott; Perrone, Debra; Befus, Kevin M.; Bayani Cardenas, M.; Ferguson, Grant; Gleeson, Tom; Luijendijk, Elco; McDonnell, Jeffrey J.; Taylor, Richard G.; Wada, Yoshihide; Kirchner, James W.

2017-06-01

The vulnerability of groundwater to contamination is closely related to its age. Groundwaters that infiltrated prior to the Holocene have been documented in many aquifers and are widely assumed to be unaffected by modern contamination. However, the global prevalence of these `fossil' groundwaters and their vulnerability to modern-era pollutants remain unclear. Here we analyse groundwater carbon isotope data (12C, 13C, 14C) from 6,455 wells around the globe. We show that fossil groundwaters comprise a large share (42-85%) of total aquifer storage in the upper 1 km of the crust, and the majority of waters pumped from wells deeper than 250 m. However, half of the wells in our study that are dominated by fossil groundwater also contain detectable levels of tritium, indicating the presence of much younger, decadal-age waters and suggesting that contemporary contaminants may be able to reach deep wells that tap fossil aquifers. We conclude that water quality risk should be considered along with sustainable use when managing fossil groundwater resources.

Groundwater sustainability in Central Australia studied using chlorine-36

International Nuclear Information System (INIS)

Cresswell, R.G.; Fifield, L.K.; Jacobson, G.

1998-01-01

The sustainability of Aboriginal community water supplies in arid Central Australia has been evaluated using the radioisotope chlorine-36 as a tracer within groundwaters to indicate the age of waters being tapped by local bores. Shallow regional groundwaters from fractured sandstones of the Ngalia Basin, fractured metamorphic rocks and Cainozoic sands and gravels show a bimodal distribution of 36 Cl ratios. The higher ratio probably represents modern (Holocene) recharge diluted with windblown salts from local playa lakes and is seen in bores around the margin. The lower ratio corresponds to a 36 Cl age of 80-100ka, implying that the last major recharge occurred during the last interglacial. These values are mainly observed in the interior of the basin, and are believed to be minimum ages for most of the shallow groundwaters in this region. Substantial recharge only appears to occur during favourable interglacial climatic regimes. Most community water supplies depend on these waters. (authors)

Preliminary simulation model to determine ground-water flow and ages within the Palo Duro Basin hydrogeologic province

International Nuclear Information System (INIS)

Atwood, H.; Picking, L.

1986-01-01

Ground-water flow through the Palo Duro and Tucumcari Basins is simulated by developing a hydrogeolgic profile and applying a cross-sectional, finite-element, numerical model to the profile. The profile is 350 miles long and 2 miles deep and extends from east-central New Mexico to the Texas-Oklahoma border. It is comprised of hydrogeologic units that are identified from geophysical well logs, sample logs, and core descriptions. A hydrogeologic unit as used in this profile is a physically continuous rock sequence with hydrologic properties that are relatively consistent throughout and distinct from surrounding units. The resulting hydrogeologic profile, with the exception of the Ogallala Formation and the Dockum Group, is discretized into a 6000-element mesh and a 22,000-element mesh. Permeability values assigned to hydrogeologic units were, in part, calculated from drill stem tests conducted throughout the Palo Duro Basin. Ground-water age and travel paths are determined by applying Darcy's equation to selected flow lines. The 170 million-year age determined from ground-water at points within the Wolfcamp Series compares favorably with the geochemical data for this region. An age of 188 million years is determined for the Pennsylvanian granite wash

Strontium isotopes as an indicator for groundwater salinity sources in the Kirkuk region, Iraq

Energy Technology Data Exchange (ETDEWEB)

Sahib, Layth Y. [Institute for Applied Geosciences, Technische Universität Darmstadt, Schnittspahnstraße 9, 64287 Darmstadt (Germany); Geology Department, College of Science, University of Baghdad, Jadreya, Baghdad (Iraq); Marandi, Andres; Schüth, Christoph [Institute for Applied Geosciences, Technische Universität Darmstadt, Schnittspahnstraße 9, 64287 Darmstadt (Germany)

2016-08-15

The Kirkuk region in northern Iraq hosts some of the largest oil fields in the Middle East. Several anticline structures enabled vertical migration and entrapment of the oil. Frequently, complex fracture systems and faults cut across the Eocene and middle Oligocene reservoirs and the cap rock, the Fatha Formation of Miocene age. Seepage of crude oil and oil field brines are therefore a common observation in the anticline axes and contamination of shallow groundwater resources is a major concern. In this study, 65 water samples were collected in the Kirkuk region to analyze and distinguish mixing processes between shallow groundwater resources, uprising oil field brines, and dissolution of gypsum and halite from the Fatha Formation. Hydrochemical analyses of the water samples included general hydrochemistry, stable water isotopes, as well as strontium concentrations and for 22 of the samples strontium isotopes ({sup 87}Sr/{sup 86}Sr). Strontium concentrations increased close to the anticline axes with highest concentrations in the oil field brines (300 mg/l). Strontium isotopes proved to be a valuable tool to distinguish mixing processes as isotope signatures of the oil field brines and of waters from the Fatha Formation are significantly different. It could be shown, that mixing of shallow groundwater with oil field brines is occurring close to the major fault zones in the anticlines but high concentrations of strontium in the water samples are mainly due to dissolution from the Fatha Formation. - Highlights: • This field study evaluates the salinity sources in the groundwater in Kirkuk region. • Salinity is related to evaporates dissolving and/or mixing with oil field brine. • Strontium isotopes proved to be a valuable tool to distinguish mixing processes.

Groundwater flow system under a rapidly urbanizing coastal city as determined by hydrogeochemistry

Science.gov (United States)

Kagabu, Makoto; Shimada, Jun; Delinom, Robert; Tsujimura, Maki; Taniguchi, Makoto

2011-01-01

In the Jakarta area (Indonesia), excessive groundwater pumping due to the rapidly increasing population has caused groundwater-related problems such as brackish water contamination in coastal areas and land subsidence. In this study, we adopted multiple hydrogeochemical techniques to demonstrate the groundwater flow system in the Jakarta area. Although almost all groundwater existing in the Jakarta basin is recharged at similar elevations, the water quality and residence time demonstrates a clear difference between the shallow and deep aquifers. Due to the rapid decrease in the groundwater potential in urban areas, we found that the seawater intrusion and the shallow and deep groundwaters are mixing, a conclusion confirmed by major ions, Br -:Cl - ratios, and chlorofluorocarbon (CFC)-12 analysis. Spring water and groundwater samples collected from the southern mountainside area show younger age characteristics with high concentrations of 14C and Ca-HCO 3 type water chemistry. We estimated the residence times of these groundwaters within 45 years under piston flow conditions by tritium analysis. Also, these groundwater ages can be limited to 20-30 years with piston flow evaluated by CFCs. Moreover, due to the magnitude of the CFC-12 concentration, we can use a pseudo age indicator in this field study, because we found a positive correlation between the major type of water chemistry and the CFC-12 concentration.

Effects of Sea Level Rise on Groundwater Flow Paths in a Coastal Aquifer System

Science.gov (United States)

Morrissey, S. K.; Clark, J. F.; Bennett, M. W.; Richardson, E.; Stute, M.

2008-05-01

Changes in groundwater flow in the Floridan aquifer system, South Florida, from the rise in sea level at the end of the last glacial period may be indicative of changes coastal aquifers will experience with continued sea level rise. As sea level rises, the hydraulic head near the coast increases. Coastal aquifers can therefore experience decreased groundwater gradients (increased residence times) and seawater intrusion. Stable isotopes of water, dissolved noble gas temperatures, radiocarbon and He concentrations were analyzed in water collected from 68 wells in the Floridan aquifer system throughout South Florida. Near the recharge area, geochemical data along groundwater flow paths in the Upper Floridan aquifer show a transition from recently recharged groundwater to glacial-aged water. Down gradient from this transition, little variation is apparent in the stable isotopes and noble gas recharge temperatures, indicating that most of the Upper Floridan aquifer contains groundwater recharged during the last glacial period. The rapid 120-meter rise in sea level marking the end of the last glacial period increased the hydraulic head in the Floridan aquifer system near the coast, slowing the flow of groundwater from the recharge area to the ocean and trapping glacial-aged groundwater. The raised sea level also flooded half of the Florida platform and caused seawater to intrude into the Lower Floridan. This circulation of seawater in the Lower Floridan continues today as our data indicate that the groundwater is similar to modern seawater with a freshwater component entering vertically from the recharge area to the Upper Floridan.

Nitrate in Danish groundwater during the last 60 years

DEFF Research Database (Denmark)

Hansen, B; Thorling, L; Dalgaard, Tommy

2011-01-01

This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribut......This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis...... of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first...... two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater (see Figure 1). Regulation and technical improvements in the intensive farming in Denmark...

A review of groundwater contamination near municipal solid waste landfill sites in China.

Science.gov (United States)

Han, Zhiyong; Ma, Haining; Shi, Guozhong; He, Li; Wei, Luoyu; Shi, Qingqing

2016-11-01

Landfills are the most widely used method for municipal solid waste (MSW) disposal method in China. However, these facilities have caused serious groundwater contamination due to the leakage of leachate. This study, analyzed 32 scientific papers, a field survey and an environmental assessment report related to groundwater contamination caused by landfills in China. The groundwater quality in the vicinity of landfills was assessed as "very bad" by a comprehensive score (FI) of 7.85 by the Grading Method in China. Variety of pollutants consisting of 96 groundwater pollutants, 3 organic matter indicators, 2 visual pollutants and 6 aggregative pollutants had been detected in the various studies. Twenty-two kinds of pollutants were considered to be dominant. According to the Kruskal-Wallis test and the median test, groundwater contamination differed significantly between regions in China, but there were no significant differences between dry season and wet season measurements, except for some pollutants in a few landfill sites. Generally, the groundwater contamination appeared in the initial landfill stage after five years and peaked some years afterward. In this stage, the Nemerow Index (PI) of groundwater increased exponentially as landfill age increased at some sites, but afterwards decreased exponentially with increasing age at others. After 25years, the groundwater contamination was very low at selected landfills. The PI values of landfills decreased exponentially as the pollutant migration distance increased. Therefore, the groundwater contamination mainly appeared within 1000m of a landfill and most of serious groundwater contamination occurred within 200m. The results not only indicate that the groundwater contamination near MSW landfills should be a concern, but also are valuable to remediate the groundwater contamination near MSW landfills and to prevent the MSW landfill from secondary pollutions, especially for developing countries considering the similar

Geochemical Investigations of Groundwater Stability

Energy Technology Data Exchange (ETDEWEB)

Bath, Adrian [Intellisci Ltd., Loughborough (United Kingdom)

2006-05-15

The report describes geochemical parameters and methods that provide information about the hydrodynamic stability of groundwaters in low permeability fractured rocks that are potential hosts for radioactive waste repositories. Hydrodynamic stability describes the propensity for changes in groundwater flows over long timescales, in terms of flow rates and flow directions. Hydrodynamic changes may also cause changes in water compositions, but the related issue of geochemical stability of a potential repository host rock system is outside the scope of this report. The main approaches to assessing groundwater stability are numerical modelling, measurement and interpretation of geochemical indicators in groundwater compositions, and analyses and interpretations of secondary minerals and fluid inclusions in these minerals. This report covers the latter two topics, with emphasis on geochemical indicators. The extent to which palaeohydrogeology and geochemical stability indicators have been used in past safety cases is reviewed. It has been very variable, both in terms of the scenarios considered, the stability indicators considered and the extent to which the information was explicitly or implicitly used in assessing FEPs and scenarios in the safety cases. Geochemical indicators of hydrodynamic stability provide various categories of information that are of hydrogeological relevance. Information about groundwater mixing, flows and water sources is potentially provided by the total salinity of groundwaters, their contents of specific non-reactive solutes (principally chloride) and possibly of other solutes, the stable isotopic ratio of water, and certain characteristics of secondary minerals and fluid inclusions. Information pertaining directly to groundwater ages and the timing of water and solute movements is provided by isotopic systems including tritium, carbon-14, chlorine-36, stable oxygen and hydrogen isotopes, uranium isotopes and dissolved mobile gases in

A multiple-tracer approach to understanding regional groundwater flow in the Snake Valley area of the eastern Great Basin, USA

International Nuclear Information System (INIS)

Gardner, Philip M.; Heilweil, Victor M.

2014-01-01

Highlights: • Age tracers and noble gases constrain intra- and inter-basin groundwater flow. • Tritium indicates modern (<60 yr) recharge occurring in all mountain areas. • Noble-gas data identify an important interbasin hydraulic discontinuity. • Further groundwater development may significantly impact Snake Valley springs. - Abstract: Groundwater in Snake Valley and surrounding basins in the eastern Great Basin province of the western United States is being targeted for large-scale groundwater extraction and export. Concern about declining groundwater levels and spring flows in western Utah as a result of the proposed groundwater withdrawals has led to efforts that have improved the understanding of this regional groundwater flow system. In this study, environmental tracers (δ 2 H, δ 18 O, 3 H, 14 C, 3 He, 4 He, 20 Ne, 40 Ar, 84 Kr, and 129 Xe) and major ions from 142 sites were evaluated to investigate groundwater recharge and flow-path characteristics. With few exceptions, δ 2 H and δ 18 O show that most valley groundwater has similar ratios to mountain springs, indicating recharge is dominated by relatively high-altitude precipitation. The spatial distribution of 3 H, terrigenic helium ( 4 He terr ), and 3 H/ 3 He ages shows that modern groundwater (<60 yr) in valley aquifers is found only in the western third of the study area. Pleistocene and late-Holocene groundwater is found in the eastern parts of the study area. The age of Pleistocene groundwater is supported by minimum adjusted radiocarbon ages of up to 32 ka. Noble gas recharge temperatures (NGTs) are generally 1–11 °C in Snake and southern Spring Valleys and >11 °C to the east of Snake Valley and indicate a hydraulic discontinuity between Snake and Tule Valleys across the northern Confusion Range. The combination of NGTs and 4 He terr shows that the majority of Snake Valley groundwater discharges as springs, evapotranspiration, and well withdrawals within Snake Valley rather than

Groundwater age, mixing and flow rates in the vicinity of large open pit mines, Pilbara region, northwestern Australia

Science.gov (United States)

Cook, Peter; Dogramaci, Shawan; McCallum, James; Hedley, Joanne

2017-01-01

Determining groundwater ages from environmental tracer concentrations measured on samples obtained from open bores or long-screened intervals is fraught with difficulty because the sampled water represents a variety of ages. A multi-tracer technique (Cl, 14C, 3H, CFC-11, CFC-12, CFC-113 and SF6) was used to decipher the groundwater ages sampled from long-screened production bores in a regional aquifer around an open pit mine in the Pilbara region of northwest Australia. The changes in tracer concentrations due to continuous dewatering over 7 years (2008-2014) were examined, and the tracer methods were compared. Tracer concentrations suggest that groundwater samples are a mixture of young and old water; the former is inferred to represent localised recharge from an adjacent creek, and the latter to be diffuse recharge. An increase in 14C activity with time in wells closest to the creek suggests that dewatering of the open pit to achieve dry mining conditions has resulted in change in flow direction, so that localised recharge from the creek now forms a larger proportion of the pumped groundwater. The recharge rate prior to development, calculated from a steady-state Cl mass balance, is 6 mm/y, and is consistent with calculations based on the 14C activity. Changes in CFC-12 concentrations with time may be related to the change in water-table position relative to the depth of the well screen.

A Multi-Methodology for improving Adelaide's Groundwater Management

Science.gov (United States)

Batelaan, Okke; Banks, Eddie; Batlle-Aguilar, Jordi; Breciani, Etienne; Cook, Peter; Cranswick, Roger; Smith, Stan; Turnadge, Chris; Partington, Daniel; Post, Vincent; Pool Ramirez, Maria; Werner, Adrian; Xie, Yueqing; Yang, Yuting

2015-04-01

through aquitard. Risk assessment of water resources status by 2050 is achieved via uncertainty quantification of potential future scenarios. This includes several development scenarios (current or increased extraction rate) as well as different outputs from climate change predictions. It is shown that groundwater in the fractured aquifer bedrock in the hills is significantly younger than groundwater in the Adelaide plains area, indicating that the Adelaide groundwater system is, at least, partially recharged by lateral flow from water infiltrated in the hills. However, increasing ages with depth, are indicative of vertical infiltration from rainfall and possible inter-aquifer leakage. A better understanding of processes controlling these two sources of fresh groundwater, as well as evaluating their relative importance to Adelaide's groundwater budget is being thoroughly investigated using the regional numerical groundwater model. The salinity distribution along the coastline is shown not to be simply an equilibrium situation with an intruded seawater wedge extending inland. Tertiary aquifers can still contain old freshwater near the coast, and in deeper layers a hypersaline brine has been identified, which could constitute a previously-overlooked source of salinity. This study is the first comprehensive investigation of the groundwater resources within the Adelaide environment and supports strongly integrated water management of the resource.

Groundwater Resources Isotope Study of Eastern and Southeastern Areas of Jordan

International Nuclear Information System (INIS)

Al-Momani, M. R.

2004-01-01

Since Jordan depends on the groundwater resources especially for municipal use so, water resources studies and development takes priority on the national level. For this reason the environmental isotope technique and application contributed and supported the hydrological studies as a research tool confirmed some scientific facts including natural and environmental changes of water resources. The isotope analyses has been implemented for upper and deep aquifer systems in the eastern and southeastern areas of Jordan for Hamad, Sirhan, Azraq and Jafr basins. The analyses included the stable isotopes for 18 O, Deuterium ( 2 H) and 13 C also the radioactive isotopes for Tritium ( 3 H ) and 14 C in nineties of the last century until 2002 and this indicates the following: * The origin and mechanism of the nonrenewable groundwater recharge in the deep aquifer systems of (B2/A7) Campanian and Turonian age for Hamad and Azraq basins has been defined. This refers that the groundwater recharge existed within humid, cold and wet climatologic conditions which is completely different from the present climate where the groundwater age exceeds thirty thousand years. * Also this indicates that the stable isotopic composition of the upper aquifers in Hamad and Sirhan basins in Shallala and Rijam aquifers (B5/B4) of Eocene and Paleocene age lie on the Global Meteoric Water Line (GMWL) where the deuterium excess (d) is 10 %. Actually this water is not tritiated and the 14 C content in the groundwater is close to zero which is a strong indication of humid and wet climate where the age of the groundwater range between 20000 and exceeds 300000 years. In comparison this situation with the same aquifer in Jafr basin located in the southeastern part of Jordan, there are differences in the deuterium excess (d), Tritium and 14 C content which depends on the climatologic conditions existed during the recharge period. Also the isotopic signaure for the middle groundwater system (B2/A7) and the

Monitoring and Assessing Groundwater Impacts on Vegetation Health in Groundwater Dependent Ecosystems

Science.gov (United States)

Rohde, M. M.; Ulrich, C.; Howard, J.; Sweet, S.

2017-12-01

Sustainable groundwater management is important for preserving our economy, society, and environment. Groundwater supports important habitat throughout California, by providing a reliable source of water for these Groundwater Dependent Ecosystems (GDEs). Groundwater is particularly important in California since it supplies an additional source of water during the dry summer months and periods of drought. The drought and unsustainable pumping practices have, in some areas, lowered groundwater levels causing undesirable results to ecosystems. The Sustainable Groundwater Management Act requires local agencies to avoid undesirable results in the future, but the location and vulnerabilities of the ecosystems that depend on groundwater and interconnected surface water is often poorly understood. This presentation will feature results from a research study conducted by The Nature Conservancy and Lawrence Berkeley National Laboratory that investigated how changes in groundwater availability along an interconnected surface water body can impact the overall health of GDEs. This study was conducted in California's Central Valley along the Cosumnes River, and situated at the boundary of a high and a medium groundwater basin: South American Basin (Sacramento Hydrologic Region) and Cosumnes Basin (San Joaquin Hydrologic Region). By employing geophysical methodology (electrical resistivity tomography) in this study, spatial changes in groundwater availability were determined under groundwater-dependent vegetation. Vegetation survey data were also applied to this study to develop ecosystem health indicators for groundwater-dependent vegetation. Health indicators for groundwater-dependent vegetation were found to directly correlate with groundwater availability, such that greater availability to groundwater resulted in healthier vegetation. This study provides a case study example on how to use hydrological and biological data for setting appropriate minimum thresholds and

Natural radioactivity in groundwater--a review.

Science.gov (United States)

Dinh Chau, Nguyen; Dulinski, Marek; Jodlowski, Pawel; Nowak, Jakub; Rozanski, Kazimierz; Sleziak, Monika; Wachniew, Przemyslaw

2011-12-01

The issue of natural radioactivity in groundwater is reviewed, with emphasis on those radioisotopes which contribute in a significant way to the overall effective dose received by members of the public due to the intake of drinking water originating from groundwater systems. The term 'natural radioactivity' is used in this context to cover all radioactivity present in the environment, including man-made (anthropogenic) radioactivity. Comprehensive discussion of radiological aspects of the presence of natural radionuclides in groundwater, including an overview of current regulations dealing with radioactivity in drinking water, is provided. The presented data indicate that thorough assessments of the committed doses resulting from the presence of natural radioactivity in groundwater are needed, particularly when such water is envisaged for regular intake by infants. They should be based on a precise determination of radioactivity concentration levels of the whole suite of radionuclides, including characterisation of their temporal variability. Equally important is a realistic assessment of water intake values for specific age groups. Only such an evaluation may provide the basis for possible remedial actions.

Isotopic and geochemical tracers in the evaluation of groundwater residence time and salinization problems at Santiago Island, Cape Verde

International Nuclear Information System (INIS)

Carreira, Paula M.; Nunes, Dina; Marques, Jose M.; Monteiro Santos, Fernando A.; Goncalves, Rui; Pina, Antonio; Mota Gomes, Antonio

2013-01-01

Stable isotopes (δ 18 O, δ 2 H) and tritium ( 3 H), together with geochemistry and geophysical data, were used for evaluating groundwater recharge sources, flow paths, and residence times in a watershed on Santiago Island, Cape Verde, West Africa. Stable isotopes indicate the predominance of high-elevation precipitation that undergoes little evaporation prior to groundwater recharge. Low tritium concentrations at seven sampling sites indicate groundwater residence times greater than 50 years. Higher tritium values at other locations suggest more recent recharge. Young ages indicate local recharge and potential groundwater vulnerability to surface contamination and/or salt-water intrusion. Geochemical results indicate that water-rock interaction mechanisms are the major processes responsible for the groundwater quality (mainly calcium-bicarbonate type), reflecting the lithological composition of subsurface soil. (authors)

Isotopic and geochemical tracers in the evaluation of groundwater residence time and salinization problems at Santiago Island, Cape Verde

Energy Technology Data Exchange (ETDEWEB)

Carreira, Paula M.; Nunes, Dina [Quimica Analitica e Ambiental, IST/ITN, Universidade Tecnica de Lisboa, Estrada Nacional no. 10, 2686-953 Sacavem (Portugal); Marques, Jose M. [Centro de Petrologia e Geoquimica. Instituto Superior Tecnico, UTL, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Monteiro Santos, Fernando A. [Universidade de Lisboa-IDL, 1749-016 Lisboa (Portugal); Goncalves, Rui [Inst. Politecnico de Tomar, Quinta do Contador, Estrada da Serra, 2300 Tomar (Portugal); Pina, Antonio; Mota Gomes, Antonio [Instituto Superior de Educacao, Praia, Santiago (Cape Verde)

2013-07-01

Stable isotopes (δ{sup 18}O, δ{sup 2}H) and tritium ({sup 3}H), together with geochemistry and geophysical data, were used for evaluating groundwater recharge sources, flow paths, and residence times in a watershed on Santiago Island, Cape Verde, West Africa. Stable isotopes indicate the predominance of high-elevation precipitation that undergoes little evaporation prior to groundwater recharge. Low tritium concentrations at seven sampling sites indicate groundwater residence times greater than 50 years. Higher tritium values at other locations suggest more recent recharge. Young ages indicate local recharge and potential groundwater vulnerability to surface contamination and/or salt-water intrusion. Geochemical results indicate that water-rock interaction mechanisms are the major processes responsible for the groundwater quality (mainly calcium-bicarbonate type), reflecting the lithological composition of subsurface soil. (authors)

Effects of aged sorption on pesticide leaching to groundwater simulated with PEARL.

Science.gov (United States)

Boesten, Jos J T I

2017-01-15

Leaching to groundwater is an important element of the regulatory risk assessment of pesticides in western countries. Including aged sorption in this assessment is relevant because there is ample evidence of this process and because it leads to a decrease in simulated leaching. This work assesses the likely magnitude of this decrease for four groundwater scenarios used for regulatory purpose in the EU (from the UK, Portugal, Austria and Greece) and for ranges of aged-sorption parameters and substance properties using the PEARL model. Three aged-sorption parameters sets were derived from literature, representing approximately 5th, 50th and 95th percentile cases for the magnitude of the effect of aged sorption on leaching concentrations (called S, M and L, respectively). The selection of these percentile cases was based only on the f NE parameter (i.e. the ratio of the aged sorption and the equilibrium sorption coefficients) because leaching was much more affected by the uncertainty in this parameter than by the uncertainty in the desorption rate coefficient of these sites (k d ). For the UK scenario, the annual flux concentration of pesticide leaching at 1m depth decreased by typically a factor of 5, 30 and >1000 for the S, M and L parameter sets, respectively. This decrease by a factor of 30 for the M parameter set appeared to be approximately valid also for the other three scenarios. Decreasing the Freundlich exponent N from 0.9 into 0.7 for the M parameter set, increased this factor of 30 into a factor of typically 1000, considering all four scenarios. The aged-sorption sites were close to their equilibrium conditions during the leaching simulations for two of the four scenarios (for all substances considered and the M parameter set), but this was not the case for the other two scenarios. Copyright © 2016 Elsevier B.V. All rights reserved.

What Can Catchment Transit Time Distributions Tell Us About Runoff Mechanisms? Exploring "Age Equifinality" with an Integrated Surface-Groundwater Model.

Science.gov (United States)

Wilusz, D. C.; Harman, C. J.; Ball, W. P.; Maxwell, R. M.; Buda, A. R.

2017-12-01

The backward transit-time distribution (bTTD) is the time-varying, probabilistic distribution of water travel times or, equivalently, water ages in catchment outflow. The bTTD is increasingly seen as a master variable of catchment hydrology that links flow and transport processes, in part because it is believed to embed information about runoff generation mechanisms (RGMs) that are difficult to directly observe. The ability to use water age to make inferences about RGMs depends on the degree of "age equifinality" in a watershed, defined here as the phenomenon where significant volumes of similarly-aged water are delivered to the outlet by different RGMs at the same time. When age equifinality is low (e.g., all discharge is old groundwater), the mapping of water age to the RGM may be simple; when age equifinality is high (e.g., discharge is a mix of old groundwater and old interflow), this mapping may be impossible. In this study we conduct experiments in a virtual watershed to (1) understand the hydrologic conditions that lead to age equifinality, (2) identify relationships between water age and RGMs that are particularly obscured/unobscured by age equifinality, and (3) test the generalizability of these relationships in other watersheds. Our experiments used the fully-distributed surface-groundwater model ParFlow, which simulates a suite of RGMs, plus SLIM-FAST particle tracking. To improve realism, the watershed model was parameterized and forced using extensive field data from the USDA's Mahantango Creek experimental catchment in PA, USA. The model output is being interrogated to understand the time-varying relationships between the composition of RGMs and the bTTD at the outlet. We are also testing the robustness of these relationships by re-running our model with controlled differences in climate, topography, and scale. Initial results suggest high age equifinality at peak flows due to overlapping young water contributions from infiltration- and saturation

Human virus and microbial indicator occurrence in public-supply groundwater systems: meta-analysis of 12 international studies

Science.gov (United States)

Fout, G. Shay; Borchardt, Mark A.; Kieke, Burney A.; Karim, Mohammad R.

2017-06-01

Groundwater quality is often evaluated using microbial indicators. This study examines data from 12 international groundwater studies (conducted 1992-2013) of 718 public drinking-water systems located in a range of hydrogeological settings. Focus was on testing the value of indicator organisms for identifying virus-contaminated wells. One or more indicators and viruses were present in 37 and 15% of 2,273 samples and 44 and 27% of 746 wells, respectively. Escherichia coli ( E. coli) and somatic coliphage are 7-9 times more likely to be associated with culturable virus-positive samples when the indicator is present versus when it is absent, while F-specific and somatic coliphages are 8-9 times more likely to be associated with culturable virus-positive wells. However, single indicators are only marginally associated with viruses detected by molecular methods, and all microbial indicators have low sensitivity and positive predictive values for virus occurrence, whether by culturable or molecular assays, i.e., indicators are often absent when viruses are present and the indicators have a high false-positive rate. Wells were divided into three susceptibility subsets based on presence of (1) total coliform bacteria or (2) multiple indicators, or (3) location of wells in karst, fractured bedrock, or gravel/cobble settings. Better associations of some indicators with viruses were observed for (1) and (3). Findings indicate the best indicators are E. coli or somatic coliphage, although both indicators may underestimate virus occurrence. Repeat sampling for indicators improves evaluation of the potential for viral contamination in a well.

Research on the neutron flux, secular equilibrium of chlorine-36 and groundwater age of the deep quaternary sediments, Hebei plain

International Nuclear Information System (INIS)

Dong Yuean; He Ming; Jiang Songsheng; Wu Shaoyong; Jiang Shan

2001-01-01

For the study of the neutron flux, secular equilibrium of chlorine-36 in the deep quaternary sediments of Hebei plain, the main chemical composition of water sand and confining bed was determined by neutron activation analysis. The mean neutron flux is 2.79 x 10 -5 cm -2 s -1 which was calculated by the chemical composition of the strata. The mean 36 Cl/Cl ratio in secular equilibrium is 1.27 x 10 -14 in the deep quaternary sediments, Hebei Plain. For the study of the groundwater age of the deep Quaternary sediments of Hebei Plain, the 36 Cl/Cl ratio of groundwater samples were determined by tandem accelerator mass spectrometry. The mixed groundwater 36 Cl/Cl ratio of the second and the third aquifer of Quaternary sediments in Baoding district is 247 x 10 -15 , that of the fourth aquifer in Baoding city is 224 x 10 -15 and the third aquifer in Cangzhou district is 40.5 x 10 -15 . The groundwater age of Baoding district was young and that of the third aquifer in Cangzhou was 229.2 ka

Microbial Indicators, Pathogens, and Antibiotic Resistance in Groundwater Impacted by Animal Farming: Field Scale to Basin Scale

Science.gov (United States)

Harter, T.; Li, X.; Atwill, E. R.; Packman, A. I.

2015-12-01

Several surveys of microbial indicators and pathogens were conducted to determine the impact of confined animal farming operations (CAFOs) on shallow, local, and regional groundwater quality in the Central Valley aquifer system, California. The aquifer system consists of highly heterogeneous, alluvial, unconsolidated coarse- to fine-grained sediments and is among the largest aquifers in the U.S.. Overlying landuse includes 3 million ha of irrigated agriculture and 1.7 million mature dairy cows in nearly 1,500 CAFOs. A multi-scale survey of water-borne indicator pathogens (Enterococcus spp. and generic E. coli) and of three water-borne pathogens (Campylobacter, Salmonella, and E. coli O157:H7) was conducted at five different spatial scales, increasing with distance from animal sources of these enteric microbial organisms: moist surfaces within individual CAFO sub-systems (calf-hutches, heifer corrals, mature cow stalls, hospital barn etc.), first encountered (shallow) groundwater immediately below these sub-systems, production aquifer below CAFOs, production aquifer near CAFOs, and production aquifer away from CAFOs. Where found, indicator pathogens were tested for antibiotic resistance. Hundreds of samples were collected at each scale: continuously during irrigation events and seasonally over a multi-year period at the three smaller site-scales; and in a one-time survey at the two larger, regional scales. All three pathogens were frequently detected in moist surface samples across CAFO sub-systems, albeit at concentrations several orders of magnitude lower than enteric indicators. Two of the three pathogens (but not Campylobacter) were also detected in first encountered groundwater, at 3-9 m below ground surface, in 1% of samples. No pathogens were found at the production aquifer scales. Generic E. coli was detected in ¼ of first encountered groundwater samples, and in 4% of production aquifer samples, while Enterococcus spp. was ubiquitously present across the

Occurrence and distribution of organophosphorus flame retardants and plasticizers in anthropogenically affected groundwater.

Science.gov (United States)

Regnery, J; Püttmann, W; Merz, C; Berthold, G

2011-02-01

Occurrence and distribution of chlorinated and non-chlorinated organophosphates in 72 groundwater samples from Germany under different recharge/infiltration conditions were investigated. Tris(2-chloro-1-methylethyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP) were the most frequently detected organophosphates in groundwater samples. Highest individual organophosphate concentrations (>0.1 µg L(-1)) were determined in groundwater polluted by infiltrating leachate and groundwater recharged via riverbank filtration of organophosphate-loaded recipients. In samples from springs and deep groundwater monitoring wells that are not affected by surface waters, organophosphate concentrations were mostly below the limit of detection. The occurrence (3-9 ng L(-1)) of TCPP and TCEP in samples from aquifers with groundwater ages between 20 and 45 years indicates the persistence of both compounds within the aquifer. At urban sites organophosphate-loaded precipitation, surface runoff, and leakage of wastewater influenced groundwater quality. For rural sites, where groundwater recharge is only influenced by precipitation, organophosphates were very rarely detectable in groundwater.

Groundwater vulnerability indices conditioned by Supervised Intelligence Committee Machine (SICM).

Science.gov (United States)

Nadiri, Ata Allah; Gharekhani, Maryam; Khatibi, Rahman; Sadeghfam, Sina; Moghaddam, Asghar Asghari

2017-01-01

This research presents a Supervised Intelligent Committee Machine (SICM) model to assess groundwater vulnerability indices of an aquifer. SICM uses Artificial Neural Networks (ANN) to overarch three Artificial Intelligence (AI) models: Support Vector Machine (SVM), Neuro-Fuzzy (NF) and Gene Expression Programming (GEP). Each model uses the DRASTIC index, the acronym of 7 geological, hydrological and hydrogeological parameters, which collectively represents intrinsic (or natural) vulnerability and gives a sense of contaminants, such as nitrate-N, penetrating aquifers from the surface. These models are trained to modify or condition their DRASTIC index values by measured nitrate-N concentration. The three AI-techniques often perform similarly but have differences as well and therefore SICM exploits the situation to improve the modeled values by producing a hybrid modeling results through selecting better performing SVM, NF and GEP components. The models of the study area at Ardabil aquifer show that the vulnerability indices by the DRASTIC framework produces sharp fronts but AI models smoothen the fronts and reflect a better correlation with observed nitrate values; SICM improves on the performances of three AI models and cope well with heterogeneity and uncertain parameters. Copyright © 2016 Elsevier B.V. All rights reserved.

Partitioning sources of recharge in environments with groundwater recirculation using carbon-14 and CFC-12

Science.gov (United States)

Bourke, Sarah A.; Cook, Peter G.; Dogramaci, Shawan; Kipfer, Rolf

2015-06-01

Groundwater recirculation occurs when groundwater is pumped from an aquifer onto the land surface, and a portion of that water subsequently infiltrates back to the aquifer. In environments where groundwater is recirculated, differentiation between various sources of recharge (e.g. natural rainfall recharge vs. recirculated water) can be difficult. Groundwater age indicators, in particular transient trace gases, are likely to be more sensitive tracers of recharge than stable isotopes or chloride in this setting. This is because, unlike stable isotopes or chloride, they undergo a process of equilibration with the atmosphere, and historical atmospheric concentrations are known. In this paper, groundwater age indicators (14C and CFC-12) were used as tracers of recharge by surplus mine water that is discharged to streams. Ternary mixing ratios were calculated based on 14C and CFC-12 concentrations measured along three transects of piezometers and monitoring wells perpendicular to the creeks, and from dewatering wells. Uncertainty in calculated mixing ratios was estimated using a Monte Carlo approach. Ternary mixing ratios in dewatering wells suggest that recharge by mine water accounted for between 10% and 87% of water currently abstracted by dewatering wells. The calculated mixing ratios suggest that recharge by mine water extends to a distance of more than 550 m from the creeks. These results are supported by seepage flux estimates based on the water and chloride balance along the creeks, which suggest that 85-90% of mine water discharged to the creeks recharges the aquifer and recharge by mine water extends between 110 and 730 m from the creeks. Mixing calculations based on gaseous groundwater age indicators could also be used to partition recharge associated with agricultural irrigation or artificial wetland supplementation.

Assessing intrinsic and specific vulnerability models ability to indicate groundwater vulnerability to groups of similar pesticides: A comparative study

Science.gov (United States)

Douglas, Steven; Dixon, Barnali; Griffin, Dale W.

2018-01-01

With continued population growth and increasing use of fresh groundwater resources, protection of this valuable resource is critical. A cost effective means to assess risk of groundwater contamination potential will provide a useful tool to protect these resources. Integrating geospatial methods offers a means to quantify the risk of contaminant potential in cost effective and spatially explicit ways. This research was designed to compare the ability of intrinsic (DRASTIC) and specific (Attenuation Factor; AF) vulnerability models to indicate groundwater vulnerability areas by comparing model results to the presence of pesticides from groundwater sample datasets. A logistic regression was used to assess the relationship between the environmental variables and the presence or absence of pesticides within regions of varying vulnerability. According to the DRASTIC model, more than 20% of the study area is very highly vulnerable. Approximately 30% is very highly vulnerable according to the AF model. When groundwater concentrations of individual pesticides were compared to model predictions, the results were mixed. Model predictability improved when concentrations of the group of similar pesticides were compared to model results. Compared to the DRASTIC model, the AF model more accurately predicts the distribution of the number of contaminated wells within each vulnerability class.

A Black Hills-Madison Aquifer origin for Dakota Aquifer groundwater in northeastern Nebraska.

Science.gov (United States)

Stotler, Randy; Harvey, F Edwin; Gosselin, David C

2010-01-01

Previous studies of the Dakota Aquifer in South Dakota attributed elevated groundwater sulfate concentrations to Madison Aquifer recharge in the Black Hills with subsequent chemical evolution prior to upward migration into the Dakota Aquifer. This study examines the plausibility of a Madison Aquifer origin for groundwater in northeastern Nebraska. Dakota Aquifer water samples were collected for major ion chemistry and isotopic analysis ((18)O, (2)H, (3)H, (14)C, (13)C, (34)S, (18)O-SO(4), (87)Sr, (37)Cl). Results show that groundwater beneath the eastern, unconfined portion of the study area is distinctly different from groundwater sampled beneath the western, confined portion. In the east, groundwater is calcium-bicarbonate type, with delta(18)O values (-9.6 per thousand to -12.4 per thousand) similar to local, modern precipitation (-7.4 per thousand to -10 per thousand), and tritium values reflecting modern recharge. In the west, groundwater is calcium-sulfate type, having depleted delta(18)O values (-16 per thousand to -18 per thousand) relative to local, modern precipitation, and (14)C ages 32,000 to more than 47,000 years before present. Sulfate, delta(18)O, delta(2)H, delta(34)S, and delta(18)O-SO(4) concentrations are similar to those found in Madison Aquifer groundwater in South Dakota. Thus, it is proposed that Madison Aquifer source water is also present within the Dakota Aquifer beneath northeastern Nebraska. A simple Darcy equation estimate of groundwater velocities and travel times using reported physical parameters from the Madison and Dakota Aquifers suggests such a migration is plausible. However, discrepancies between (14)C and Darcy age estimates indicate that (14)C ages may not accurately reflect aquifer residence time, due to mixtures of varying aged water.

Assessing groundwater availability and the response of the groundwater system to intensive exploitation in the North China Plain by analysis of long-term isotopic tracer data

Science.gov (United States)

Su, Chen; Cheng, Zhongshuang; Wei, Wen; Chen, Zongyu

2018-03-01

The use of isotope tracers as a tool for assessing aquifer responses to intensive exploitation is demonstrated and used to attain a better understanding of the sustainability of intensively exploited aquifers in the North China Plain. Eleven well sites were selected that have long-term (years 1985-2014) analysis data of isotopic tracers. The stable isotopes δ18O and δ2H and hydrochemistry were used to understand the hydrodynamic responses of the aquifer system, including unconfined and confined aquifers, to groundwater abstraction. The time series data of 14C activity were also used to assess groundwater age, thereby contributing to an understanding of groundwater sustainability and aquifer depletion. Enrichment of the heavy oxygen isotope (18O) and elevated concentrations of chloride, sulfate, and nitrate were found in groundwater abstracted from the unconfined aquifer, which suggests that intensive exploitation might induce the potential for aquifer contamination. The time series data of 14C activity showed an increase of groundwater age with exploitation of the confined parts of the aquifer system, which indicates that a larger fraction of old water has been exploited over time, and that the groundwater from the deep aquifer has been mined. The current water demand exceeds the sustainable production capabilities of the aquifer system in the North China Plain. Some measures must be taken to ensure major cuts in groundwater withdrawals from the aquifers after a long period of depletion.

Validation on groundwater flow model including sea level change. Modeling on groundwater flow in coastal granite area

International Nuclear Information System (INIS)

Hasegawa, Takuma; Miyakawa, Kimio

2009-01-01

It is important to verify the groundwater flow model that reproduces pressure head, water chemistry, and groundwater age. However, water chemistry and groundwater age are considered to be influenced by historical events. In this study, sea level change during glacial-interglacial cycle was taken into account for simulating salinity and groundwater age at coastal granite area. As a result of simulation, salinity movement could not catch up with sea level changes, and mixing zone was formed below the fresh-water zone. This mixing zone was observed in the field measurement, and the observed salinities were agreed with simulated results including sea level change. The simulated residence time including sea level change is one-tenth of steady state. The reason is that the saline water was washed out during regression and modern sea-water was infiltrated during transgression. As mentioned before, considering sea level change are important to reproduce salinity and helium age at coastal area. (author)

Groundwater recharge and flow on Montserrat, West Indies: Insights from groundwater dating

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Brioch Hemmings

2015-09-01

New hydrological insights: δ2H and δ18O analysis indicates uniform recharge elevations for groundwaters on Montserrat. CFC-11 and CFC-12 analysis reveals age differences between isotopically similar, high elevation springs and low elevation aquifer waters. Low CFC concentrations within a confined low elevation aquifer suggest water ages of ∼45 years. High CFC concentrations in the northern and western springs are explained by rapid infiltration of cool (high CFC concentration rainfall into saturated compartments, with flow through the vadose zone to the phreatic zone dominated by compartment flow. Lower CFC concentrations in a number of aligned warmer springs suggest a contribution from older, warmer waters from depth. Temperatures and CFC concentrations indicate older component supply rates of up to 8 L/s to the highest yielding spring on Centre Hills, with contributions of up to 75% in the warmest spring waters.

Using 14C and 3H to understand groundwater flow and recharge in an aquifer window

Science.gov (United States)

Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.

2014-12-01

Knowledge of groundwater residence times and recharge locations is vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge from rainfall and recharge from the Gellibrand River. To determine recharge patterns and groundwater flow paths, environmental isotopes (3H, 14C, δ13C, δ18O, δ2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. The water table fluctuates by 0.9 to 3.7 m annually, implying recharge rates of 90 and 372 mm yr-1. However, residence times of shallow (11 to 29 m) groundwater determined by 14C are between 100 and 10 000 years, 3H activities are negligible in most of the groundwater, and groundwater electrical conductivity remains constant over the period of study. Deeper groundwater with older 14C ages has lower δ18O values than younger, shallower groundwater, which is consistent with it being derived from greater altitudes. The combined geochemistry data indicate that local recharge from precipitation within the valley occurs through the aquifer window, however much of the groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High. The Gellibrand Valley is a regional discharge zone with upward head gradients that limits local recharge to the upper 10 m of the aquifer. Additionally, the groundwater head gradients adjacent to the Gellibrand River are generally upwards, implying that it does not recharge the surrounding groundwater and has limited bank storage. 14C ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10

Investigation of geochemical indicators to evaluate the connection between inland and coastal groundwater systems near Kaloko-Honokōhau National Historical Park, Hawai‘i

International Nuclear Information System (INIS)

Tillman, Fred D; Oki, Delwyn S.; Johnson, Adam G.; Barber, Larry B.; Beisner, Kimberly R.

2014-01-01

mixing process between the inland impounded and coastal unconfined-groundwater systems. Stable isotopes of water in many samples from the coastal unconfined-groundwater system require an aggregate recharge altitude that is substantially higher than the boundary between the coastal unconfined and inland impounded systems, a further indication of a hydrologic connection between the two systems. The stable isotope composition of the freshwater component of water samples from KAHO indicates that about 25–70% of the freshwater is derived from the inland impounded system

Geochemistry and isotope hydrology of groundwaters in the Stripa Granite: results and preliminary interpretation

International Nuclear Information System (INIS)

Fritz, P.; Barker, J.F.; Gale, J.E.

1979-04-01

The results of geochemical and isotopic analyses on water samples from the granite at Stripa, Sweden, are presented. Groundwater samples collected from shallow, private wells; surface boreholes; and boreholes drilled from the 330 m and 410 m mine levels were analyzed for their major ion chemistry, dissolved gases, and environmental isotope contents. The principal change in the chemical load with depth is typified by chloride concentration, which increases from less than 5 mg/liter to about 300 mg/liter. There is a parallel increase in pH, which changes from about 6.5 to over 9.75. It is important to notice that calcite saturation is maintained and that, because of rising pH, dissolved inorganic carbon is lost. The total carbonate content thus decreases from about 70 mg/liter to less than 7 mg/liter. The 18 O and deuterium analyses demonstrate that different fracture systems contain different water masses, whose age increases with depth. Groundwater age determinations with 14 C and isotopes of the uranium decay series strongly indicate that water ages exceed 25,000 years. The 13 C contents of the aqueous carbonate in these groundwaters indicate groundwater recharge through vegetated soil, presumably during an interglacial period. The 13 C and 18 O determinations show that most fracture calcites have formed in a wide variety of depositional environments, and not in the waters circulating today

Groundwater chemical changes at SFR in Forsmark

Energy Technology Data Exchange (ETDEWEB)

Laaksoharju, Marcus [GeoPoint AB, Sollentuna (Sweden); Gurban, Ioana [3DTerra (Sweden)

2003-01-01

The examination of the groundwater sampled at the SFR tunnel system indicated that the groundwater consist mainly of a Na-Cl to Na-Ca-Cl type of water. Most of the samples fall within the Cl range of 2500-5500 mg/l having a neutral pH (6.6-7.7 units). The water is reducing and despite the fact that the tunnel acts like a hydraulic sink constantly withdrawing water out from the rock into the tunnel the groundwater changes are moderate with time. Most of the sampling points in the SFR tunnel system are located under the Sea and M3 calculations indicated that most of the sampling points have a change of water types from an older marine water type affected by glacial melt water to an more modern marine water type such as Baltic Sea water which has been modified by possibly microbial sulphate reduction and ion exchange. Mass balance calculations indicated that the waters seem to be in equilibrium with the fracture filling mineral such as calcite. The quality of the aluminium data made the modelling with the major rock forming aluminium silicates such as feldspars and clay minerals uncertain and was therefore not reported. The conclusion is that the groundwater evolution and patterns at SFR are a result of many factors such as: 1. the changes in hydrogeology related to glaciation/deglaciation and land uplift, 2. repeated Sea/lake water regressions/transgressions 3. the closeness to Baltic Sea resulting in relative small hydrogeological driving forces which could preserve old water types from being flushed out, 4. organic or inorganic alteration of the groundwater caused by microbial processes or in situ water/rock interactions 5. tunnel construction which changed the flow system The modelled present-day groundwater conditions of the SFR site consist of a mixture in varying degrees of different water types. The data indicate that all the groundwater at SFR is strongly affected by Sea water of different origin and ages. The meteoric (0- 1000 B.P) portion is located close

Distribution of Isotopic and Environmental Tracers in Groundwater, Northern Ada County, Southwestern Idaho

Science.gov (United States)

Adkins, Candice B.; Bartolino, James R.

2010-01-01

Residents of northern Ada County, Idaho, depend on groundwater for domestic and agricultural uses. The population of this area is growing rapidly and groundwater resources must be understood for future water-resource management. The U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources, used a suite of isotopic and environmental tracers to gain a better understanding of groundwater ages, recharge sources, and flowpaths in northern Ada County. Thirteen wells were sampled between September and October 2009 for field parameters, major anions and cations, nutrients, oxygen and hydrogen isotopes, tritium, radiocarbon, chlorofluorocarbons, and dissolved gasses. Well depths ranged from 30 to 580 feet below land surface. Wells were grouped together based on their depth and geographic location into the following four categories: shallow aquifer, intermediate/deep aquifer, Willow Creek aquifer, and Dry Creek aquifer. Major cations and anions indicated calcium-bicarbonate and sodium-bicarbonate water types in the study area. Oxygen and hydrogen isotopes carried an oxygen-18 excess signature, possibly indicating recharge from evaporated sources or water-rock interactions in the subsurface. Chlorofluorocarbons detected modern (post-1940s) recharge in every well sampled; tritium data indicated modern water (post-1951) in seven, predominantly shallow wells. Nutrient concentrations tended to be greater in wells signaling recent recharge based on groundwater age dating, thus confirming the presence of recent recharge in these wells. Corrected radiocarbon results generated estimated residence times from modern to 5,100 years before present. Residence time tended to increase with depth, as confirmed by all three age-tracers. The disagreement among residence times indicates that samples were well-mixed and that the sampled aquifers contain a mixture of young and old recharge. Due to a lack of data, no conclusions about sources of recharge could be drawn

Assessing groundwater policy with coupled economic-groundwater hydrologic modeling

Science.gov (United States)

Mulligan, Kevin B.; Brown, Casey; Yang, Yi-Chen E.; Ahlfeld, David P.

2014-03-01

This study explores groundwater management policies and the effect of modeling assumptions on the projected performance of those policies. The study compares an optimal economic allocation for groundwater use subject to streamflow constraints, achieved by a central planner with perfect foresight, with a uniform tax on groundwater use and a uniform quota on groundwater use. The policies are compared with two modeling approaches, the Optimal Control Model (OCM) and the Multi-Agent System Simulation (MASS). The economic decision models are coupled with a physically based representation of the aquifer using a calibrated MODFLOW groundwater model. The results indicate that uniformly applied policies perform poorly when simulated with more realistic, heterogeneous, myopic, and self-interested agents. In particular, the effects of the physical heterogeneity of the basin and the agents undercut the perceived benefits of policy instruments assessed with simple, single-cell groundwater modeling. This study demonstrates the results of coupling realistic hydrogeology and human behavior models to assess groundwater management policies. The Republican River Basin, which overlies a portion of the Ogallala aquifer in the High Plains of the United States, is used as a case study for this analysis.

Measuring and understanding total dissolved gas pressure in groundwater

Science.gov (United States)

Ryan, C.; Roy, J. W.; Randell, J.; Castellon, L.

2009-05-01

Since dissolved gases are important to a number of aspects of groundwater (e.g. age dating, active or passive bioremediation, greenhouse gas fluxes, understanding biogeochemical processes involving gases, assessing potential impacts of coal bed methane activities), accurate concentration measurements, and understanding of their subsurface behaviour are important. Researchers have recently begun using total dissolved gas pressure (TGP) sensor measurements, more commonly applied for surface water monitoring, in concert with gas composition analyses to estimate more accurate groundwater gas concentrations in wells. We have used hydraulic packers to isolate the well screens where TDP is being measured, and pump tests to indicate that in-well degassing may reduce TDG below background groundwater levels. Thus, in gas-charged groundwater zones, TGPs can be considerably underestimated in the absence of pumping or screen isolation. We have also observed transient decreased TGPs during pumping that are thought to result from ebullition induced when the water table or water level in the well is lowered below a critical hydrostatic pressure.

Estimating Groundwater Development area in Jianan Plain using Standardized Groundwater Index

Science.gov (United States)

Yu, Chang Hsiang; Haw, Lee Cheng

2017-04-01

Taiwan has been facing severe water crises in recent years owing to the effects of extreme weather conditions. Changes in precipitation patterns have also made the drought phenomenon increasingly prominent, which has indirectly affected groundwater recharge. Hence, in the present study, long-term monitoring data were collected from the study area of the Jianan plain. The standardized groundwater index (SGI) and was then used to analyse the region's drought characteristics. To analyse the groundwater level by using SGI, making SGI180 groundwater level be the medium water crises, and SGI360 groundwater level be the extreme water crises. Through the different water crises signal in SGI180 and SGI360, we divide groundwater in Jianan plain into two sections. Thereby the water crises indicators establishing groundwater level standard line in Jianan Plain, then using the groundwater level standard line to find the study area where could be groundwater development area in Jianan plain. Taking into account relatively more water scarcity in dry season, so the study screen out another emergency backup groundwater development area, but the long-term groundwater development area is still as a priority development area. After finding suitable locations, groundwater modeling systems(GMS) software is used to simulate our sites to evaluate development volume. Finally, the result of study will help the government to grasp the water shortage situation immediately and solve the problem of water resources deployment.

Effect of Age on Pentacam Keratoconus Indices

Directory of Open Access Journals (Sweden)

Maged Maher Salib Roshdy

2018-01-01

Full Text Available Purpose. To assess the effect of age on elevation and pachymetric Pentacam keratoconus (KC detection indices, and the need to adjust normative values accordingly. Methods. In a retrospective study, 95 eyes of myopic normal subjects without KC were evaluated using the OCULUS Pentacam, with an age range of 17.4 to 46.8 years. Subjects were categorised into three groups according to their age: the first included those younger than 21 years (19 eyes, the second was for the age range of 21–40 years (65 eyes, and the third comprised subjects older than 40 years (11 eyes. Results. There were statistically significant differences among the three groups regarding many elevation indices: AE from BFS, PE from BFS, and PE minus AE from BFS (P=0.003, 0.010, and <0.001, resp., and pachymetric indices: PPI avg, PPI max, ART avg, ART max, and diagonal decentration of the thinnest point (P=<0.001, 0.024, 0.003, 0.026, and 0.026, resp.. On comparing subjects below 21 years to those above 40 years, there was a statistically significant decrease of both PE from BFS and PE minus AE (P=0.005 and <0.001, resp. and statistically significant increase in AE from BFS (P=0.001. Conclusions. Age is an important determinant of elevation indices, significantly altering their normative values. The use of the more robust pachymetry, rather than elevation, indices is recommended in subjects below 21 or above 40 years of age.

Groundwater sustainability and groundwater/surface-water interaction in arid Dunhuang Basin, northwest China

Science.gov (United States)

Lin, Jingjing; Ma, Rui; Hu, Yalu; Sun, Ziyong; Wang, Yanxin; McCarter, Colin P. R.

2018-03-01

The Dunhuang Basin, a typical inland basin in northwestern China, suffers a net loss of groundwater and the occasional disappearance of the Crescent Lake. Within this region, the groundwater/surface-water interactions are important for the sustainability of the groundwater resources. A three-dimensional transient groundwater flow model was established and calibrated using MODFLOW 2000, which was used to predict changes to these interactions once a water diversion project is completed. The simulated results indicate that introducing water from outside of the basin into the Shule and Danghe rivers could reverse the negative groundwater balance in the Basin. River-water/groundwater interactions control the groundwater hydrology, where river leakage to the groundwater in the Basin will increase from 3,114 × 104 m3/year in 2017 to 11,875 × 104 m3/year in 2021, and to 17,039 × 104 m3/year in 2036. In comparison, groundwater discharge to the rivers will decrease from 3277 × 104 m3/year in 2017 to 1857 × 104 m3/year in 2021, and to 510 × 104 m3/year by 2036; thus, the hydrology will switch from groundwater discharge to groundwater recharge after implementing the water diversion project. The simulation indicates that the increased net river infiltration due to the water diversion project will raise the water table and then effectively increasing the water level of the Crescent Lake, as the lake level is contiguous with the water table. However, the regional phreatic evaporation will be enhanced, which may intensify soil salinization in the Dunhuang Basin. These results can guide the water allocation scheme for the water diversion project to alleviate groundwater depletion and mitigate geo-environmental problem.

Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China

International Nuclear Information System (INIS)

Han, Dongmei; Cao, Guoliang; McCallum, James; Song, Xianfang

2015-01-01

Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33–521 mg/L) in NO_3"− concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ"1"8O, δ"2H) analysis, "3H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from − 8.5 to − 7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92–467 years) and the NO_3"− concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8–411 years) and the NO_3"− concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be transported for tens of years, through the

Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China

Energy Technology Data Exchange (ETDEWEB)

Han, Dongmei [Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China); National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Cao, Guoliang [National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Center for Water Research, College of Engineering, Peking University, Beijing 100871 (China); McCallum, James [National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Song, Xianfang [Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China)

2015-12-15

Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33–521 mg/L) in NO{sub 3}{sup −} concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ{sup 18}O, δ{sup 2}H) analysis, {sup 3}H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from − 8.5 to − 7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92–467 years) and the NO{sub 3}{sup −} concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8–411 years) and the NO{sub 3}{sup −} concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be

Slow arsenic poisoning of the contaminated groundwater users

International Nuclear Information System (INIS)

Uddin, M. M.; Harun-Ar-Rashid, A. K. M.; Hossain, S. M.; Hafiz, M. A.; Nahar, K.; Mubin, S. H.

2006-01-01

This paper gives impact of Arsenic contaminated water on human health as well as overview of the extent and severity of groundwater arsenic contamination in Bangladesh. Scalp hair is the most important part of the human body to monitor the accumulation of this type of poison. Therefore, an experiment has been carried out by Neutron Activation Analysis at Atomic Energy Research Establishment , Savar, Dhaka, Bangladesh on human hair of corresponding tube well water users of these areas to determine the total accumulation of arsenic to their body. Hair samples collected from the region where the groundwater was found highly contaminated with arsenic. The obtained results of arsenic concentration in the lower age (Hb) categories of users (below 12 years of age users) is in the range of 0.33 to 3.29 μg/g (ppm) and that in the Hu categories (upper 12 years of age users) is 0.47 to 6.64 μg/g (ppm). Where as maximum permissible range is 1 ppm certified from WHO. Results show that the peoples are highly affected where the groundwater is highly contaminated with arsenic and acts as the primary source of arsenic poisoning among the peoples of those areas. The results indicate that human population is affected with arsenic locally using the contaminated water for a long time

Use of Tritium and Helium to Define Groundwater Flow Conditions in a Coastal Aquifer Influenced by Seawater Intrusion: Everglades National Park

Science.gov (United States)

Price, R. M.; Top, Z.; Happell, J. D.; Swart, P. K.

2002-05-01

The concentrations of tritium (3H) and helium isotopes (3He, 4He) were used as tracers of groundwater flow in Everglades National Park, South Florida (USA). Both fresh and brackish groundwaters were collected from 47 wells completed at depths ranging from 2 m to 73 m within the Surficial Aquifer System (SAS). Ages as determined by 3H/3He techniques indicate that groundwater within the upper 28 m originated after the nuclear era (within the last 42 yr) and below 28 m before then with evidence of some mixing at the interface. Inter-annual variation of the 3H/3He ages within the upper 28 m was significant throughout the three year investigation, suggesting varying hydrologic conditions. The age of the shallow groundwater in the southern regions of ENP (Rocky Glades and Taylor Slough) tended to be younger following times of high water level when the dominant direction of groundwater flow water was to the southeast. In the same region, significantly older groundwater was observed following times of low water levels and a shift in the groundwater flow direction toward the southwest. Near the canals, the reverse occurred with the ages of shallow groundwater tending to be younger following times of low water levels, suggesting a greater influence of recharge water from the canals to the surrounding aquifer. Although water levels and the direction of hydrologic gradients vary greatly within a 3-month time period, the average age of the shallow (Aquifer suggesting a preferential flow path to the deeper formation. An increase in 4He with depth suggests that radiogenic 4He produced in the underlying Hawthorn Group is dispersed into the SAS. Higher Δ 4He values in brackish groundwaters compared to fresh waters from similar depths indicate an enhanced vertical transport of 4He in the seawater mixing zone. Seawater intrudes at distances of 6 to 28 km at shallow depths (Florida Bay and the Gulf of Mexico over an approximately 6 to 28 km wide strip that parallels the coastline.

Bacterial sulphate reduction and mixing processes at the Aespoe Hard Rock Laboratory indicated by groundwater δ34S isotope signatures

International Nuclear Information System (INIS)

Wallin, Bill

2011-04-01

This report includes data mostly obtained from δ 34 S isotope measurements of groundwater at the Aespoe Island and one sampling from the Laxemar site, southeastern Sweden, during tunnel construction. Early sampling at Aespoe (up to 1992), before tunnel excavation, indicates a groundwater system with multiple sulphur sources. The isotope changes over time in the dissolved sulphate were studied during a sampling campaign in the monitoring phase from 1993 to 1995. A total of 88 samples were collected by SKB between 1992 and 1995 from core-drilled surface boreholes and from boreholes drilled in the tunnel (34 of these samples were collected from the tunnel boreholes). The results of the analyses have been the focus of discussion of the isotope changes with time in the dissolved sulphate (SO 4 2- ). The results indicate that the sulphur isotope signatures in the dissolved sulphate of the groundwater and those from fracture-filling sulphides at Aespoe originate from multiple sulphur sources in the groundwater at Aespoe and Laxemar. The data may be grouped as follows: a) typically homogeneous marine signatures of dissolved SO 4 2- are observed, with δ 34 S values of approximately +21 per mille CDT at intermediate depths of approximately 100-250 m; b) dissolved sulphate in the groundwater at greater depths (below 600 m) with average values of approximately +10 per mille CDT; and c) a dissolved SO 4 2- originating from a mixture of these sulphur sources (100-600m), although there is a difference between a mixture and modification by reduction. Reduced sulphur with low δ 34 S values is also recorded in fracture-filling sulphides, with δ 34 S values of approximately 0 to -10 per mille CDT. This may contribute to small changes in the isotope signature of the dissolved SO 4 2- , probably by sulphide oxidation in the past. The changes in the δ 34 S isotope data for dissolved SO 4 2- over the 1992-1996 period suggest a complex situation, indicating both sulphate reduction by

Age and speciation of iodine in groundwater and mudstones of the Horonobe area, Hokkaido, Japan: Implications for the origin and migration of iodine during basin evolution

Science.gov (United States)

Togo, Yoko S.; Takahashi, Yoshio; Amano, Yuki; Matsuzaki, Hiroyuki; Suzuki, Yohey; Terada, Yasuko; Muramatsu, Yasuyuki; Ito, Kazumasa; Iwatsuki, Teruki

2016-10-01

This paper reports the concentration, speciation and isotope ratio (129I/127I) of iodine from both groundwater and host rocks in the Horonobe area, northern Hokkaido, Japan, to clarify the origin and migration of iodine in sedimentary rocks. Cretaceous to Quaternary sedimentary rocks deposited nearly horizontally in Tenpoku Basin and in the Horonobe area were uplifted above sea level during active tectonics to form folds and faults in the Quaternary. Samples were collected from the Pliocene Koetoi and late Miocene Wakkanai formations (Fms), which include diatomaceous and siliceous mudstones. The iodine concentration in groundwater, up to 270 μmol/L, is significantly higher than that of seawater, with the iodine enrichment factor relative to seawater reaching 800-1500. The iodine concentration in the rocks decreases from the Koetoi to Wakkanai Fms, suggesting that iodine was released into the water from the rocks of deeper formations. The iodine concentration in the rocks is sufficiently high for forming iodine-rich groundwater as found in this area. X-ray absorption near edge structure (XANES) analysis shows that iodine exists as organic iodine and iodide (I-) in host rocks, whereas it exists mainly as I- in groundwater. The isotope ratio is nearly constant for iodine in the groundwater, at [0.11-0.23] × 10-12, and it is higher for iodine in rocks, at [0.29-1.1] × 10-12, giving iodine ages of 42-60 Ma and 7-38 Ma, respectively. Some iodine in groundwater must have originated from Paleogene and even late Cretaceous Fms, which are also considered as possible sources of oil and gas, in view of the old iodine ages of the groundwater. The iodine ages of the rocks are older than the depositional ages, implying that the rocks adsorbed some iodine from groundwater, which was sourced from greater depths. The iodine concentration in groundwater decreases with decreasing chlorine concentration due to mixing of iodine-rich connate water and meteoric water. A likely scenario

Paleoclimatic information from deuterium and oxygen-18 in C-14 dated North Saharian groundwaters; groundwater formation in the past

International Nuclear Information System (INIS)

Sonntag, C.; Muennich, K.O.; Junghans, C.

1978-01-01

A statistical presentation of C-14 groundwater ages for various regions of the Northern Sahara reflects the alternating sequence of humid and arid periods in the late Pleistocene and Holocene. Groundwaters older than 20000 y B.P. are found all over the Sahara. Isoline-presentation of the Continental Effect in deuterium and oxygen-18 of Saharian groundwater is similar to the one in modern European groundwater. This similarity proves the Western Drift influence when in the past winter rains were sufficient for groundwater formation in the Sahara (great pluvial). The postpluvial humid phases of the Sahara during the Holocene were probably of decreasing importance from west to east. The lower deuterium excess d = delta D - 8 x delta 18 O observed in old Saharian groundwaters is interpreted to be due to a lower moisture deficit of the air over the ocean during the last ice-age. Extremely high D- and O-18 contents of modern groundwater in the Sahel zone south of the Sahara are probably due to summer rain originating from tropical rain forest evapotranspiration. (orig.) [de

Isotope analyses for classification of the age and origin of bodies of groundwater in the area of the Asse salt mine

International Nuclear Information System (INIS)

Wolf, M.; Batsche, H.; Graf, W.; Rauert, W.; Trimborn, P.; Klarr, K.; Stempel, C. v.

1994-01-01

Within the framework of a hydrogeological research project which contributes to the evaluation of the long- time safety of the Asse salt mine large-scale hydrological isotope analyses were made to classify bodies of groundwater by their age and origin. The radioactive isotopes carbon-14 and tritium, and the stable isotopes deuterium, oxygen-18 and carbon- 13 from boring, well and spring groundwater in the area of the Asse salt mine were analyzed. The environmental isotope data obtained were interpreted considering the chemical composition of the groundwater through hydrogeochemical model calculations by use of the PHREEQE program. The results of the study are summarized. (HP) [de

A multi-tracer approach to delineate groundwater dynamics in the Rio Actopan Basin, Veracruz State, Mexico

Science.gov (United States)

Pérez Quezadas, Juan; Heilweil, Victor M.; Cortés Silva, Alejandra; Araguas, Luis; Salas Ortega, María del Rocío

2016-12-01

Geochemistry and environmental tracers were used to understand groundwater resources, recharge processes, and potential sources of contamination in the Rio Actopan Basin, Veracruz State, Mexico. Total dissolved solids are lower in wells and springs located in the basin uplands compared with those closer to the coast, likely associated with rock/water interaction. Geochemical results also indicate some saltwater intrusion near the coast and increased nitrate near urban centers. Stable isotopes show that precipitation is the source of recharge to the groundwater system. Interestingly, some high-elevation springs are more isotopically enriched than average annual precipitation at higher elevations, indicating preferential recharge during the drier but cooler winter months when evapotranspiration is reduced. In contrast, groundwater below 1,200 m elevation is more isotopically depleted than average precipitation, indicating recharge occurring at much higher elevation than the sampling site. Relatively cool recharge temperatures, derived from noble gas measurements at four sites (11-20 °C), also suggest higher elevation recharge. Environmental tracers indicate that groundwater residence time in the basin ranges from 12,000 years to modern. While this large range shows varying groundwater flowpaths and travel times, ages using different tracer methods (14C, 3H/3He, CFCs) were generally consistent. Comparing multiple tracers such as CFC-12 with CFC-113 indicates piston-flow to some discharge points, yet binary mixing of young and older groundwater at other points. In summary, groundwater within the Rio Actopan Basin watershed is relatively young (Holocene) and the majority of recharge occurs in the basin uplands and moves towards the coast.

Wairarapa Valley groundwater : residence time, flow pattern, and hydrochemistry trends

International Nuclear Information System (INIS)

Morgenstern, U.

2005-01-01

The Wairarapa groundwater system has a complicated hydrogeological setting as it evolved from sea level changes, tectonic activity, and geomorphic process. Due to increasing groundwater demand a better understanding of the groundwater resources is required to help achieve effective management and sustainable use. In addition to previous 'classical' hydrogeology studies, this report represents the first stage of a comprehensive approach using age dating and chemistry time trends for understanding the Wairarapa groundwater system. The methodology of groundwater age dating and mixing models is described in Appendix 1. Historic tritium data were evaluated, and combined with new tritium and CFC/SF 6 data to allow for robust age dating. (author). 14 refs., 30 figs

Environmental isotope studies on groundwater problems in the Thar Desert, India

International Nuclear Information System (INIS)

Nair, A.R.; Navada, S.V.; Rao, S.M.

1997-01-01

One of the groundwater problems encountered in arid areas like the Thar Desert in Rajasthan is to know whether the shallow groundwater is being actively recharged. Environmental isotopes particularly tritium are very useful in providing evidence of recent recharge. In the Barmer area, the shallow groundwaters have tritium levels generally in the range 3-6 TU showing modern recharge. Most of the recharge possibly occurs by direct infiltration of precipitation. Indirect recharge through wadis (river channels) could sometimes be an important mechanism of groundwater recharge. Environmental isotope study in Jalore area showed that the shallow groundwaters near the Sukri river course had δ 2 H and δ 18 O are depleted compared to present day precipitation but not as depleted as the present day Himalayan rivers. Carbon-24 values of some of these groundwaters are in the range of 54-58 pMC showing that they possibly represent old river with headwater connection outside the desert. In the Thar, the deep groundwaters which sometimes form the bulk of water supply are generally paleowaters as sown by environmental δ 2 H, δ 18 O, 3 H and 14 C. For example in the Barmer area, deep groundwaters (depth > 150m) have depleted δ 2 H and δ 18 O compared to the shallow groundwaters and present day precipitation. They have negligible 3 H and 14 C model ages ranging from 4000 to 9500 BP. Hence the isotope data of the deep groundwaters indicate they are paleowaters recharged during humid periods in the Holocene. Over-exploitation of deep groundwaters could lead to mixing of shallow and deep groundwaters or influx of waters from adjoining aquifers. In the Bikaner area similar δ 2 H and δ 18 O of the shallow and deep wells and young waters encountered in some of the deep wells indicated mixing between the two aquifers due to heavy exploitation of groundwaters in the area. In a limestone belt of Jodhpur-Nagaur district heavy exploitation of groundwaters is taking place in the southern

Groundwater recharge mechanism in an integrated tableland of the Loess Plateau, northern China: insights from environmental tracers

Science.gov (United States)

Huang, Tianming; Pang, Zhonghe; Liu, Jilai; Ma, Jinzhu; Gates, John

2017-11-01

Assessing groundwater recharge characteristics (recharge rate, history, mechanisms (piston and preferential flow)) and groundwater age in arid and semi-arid environments remains a difficult but important research frontier. Such assessments are particularly important when the unsaturated zone (UZ) is thick and the recharge rate is limited. This study combined evaluations of the thick UZ with those of the saturated zone and used multiple tracers, such as Cl, NO3, Br, 2H, 18O, 13C, 3H and 14C, to study groundwater recharge characteristics in an integrated loess tableland in the Loess Plateau, China, where precipitation infiltration is the only recharge source for shallow groundwater. The results indicate that diffuse recharge beneath crops, as the main land use of the study area, is 55-71 mm yr-1 based on the chloride mass balance of soil profiles. The length of time required for annual precipitation to reach the water table is 160-400 yrs. The groundwater is all pre-modern water and paleowater, with corrected 14C age ranging from 136 to 23,412 yrs. Most of the water that eventually becomes recharge originally infiltrated in July-September. The Cl and NO3 contents in the upper UZ are considerably higher than those in the deep UZ and shallow groundwater because of recent human activities. The shallow groundwater has not been in hydraulic equilibrium with present near-surface boundary conditions. The homogeneous material of the UZ and relatively old groundwater age imply that piston flow is the dominant recharge mechanism for the shallow groundwater in the tableland.

Oxygen, hydrogen, and helium isotopes for investigating groundwater systems of the Cape Verde Islands, West Africa

Science.gov (United States)

Heilweil, V.M.; Solomon, K.D.; Gingerich, S.B.; Verstraeten, Ingrid M.

2009-01-01

Stable isotopes (??18O, ??2H), tritium (3H), and helium isotopes (3He, 4He) were used for evaluating groundwater recharge sources, flow paths, and residence times of three watersheds in the Cape Verde Islands (West Africa). Stable isotopes indicate the predominance of high-elevation precipitation that undergoes little evaporation prior to groundwater recharge. In contrast to other active oceanic hotspots, environmental tracers show that deep geothermal circulation does not strongly affect groundwater. Low tritium concentrations at seven groundwater sites indicate groundwater residence times of more than 50 years. Higher tritium values at other sites suggest some recent recharge. High 4He and 3He/4He ratios precluded 3H/3He dating at six sites. These high 3He/4He ratios (R/Ra values of up to 8.3) are consistent with reported mantle derived helium of oceanic island basalts in Cape Verde and provided end-member constraints for improved dating at seven other locations. Tritium and 3H/3He dating shows that S??o Nicolau Island's Ribeira Faj?? Basin has groundwater residence times of more than 50 years, whereas Fogo Island's Mosteiros Basin and Santo Ant??o Island's Ribeira Paul Basin contain a mixture of young and old groundwater. Young ages at selected sites within these two basins indicate local recharge and potential groundwater susceptibility to surface contamination and/or salt-water intrusion. ?? Springer-Verlag 2009.

Functional age as an indicator of reservoir senescence

Science.gov (United States)

Miranda, Leandro E.; Krogman, R. M.

2015-01-01

It has been conjectured that reservoirs differ in the rate at which they manifest senescence, but no attempt has been made to find an indicator of senescence that performs better than chronological age. We assembled an indicator of functional age by creating a multimetric scale consisting of 10 metrics descriptive of reservoir environments that were expected to change directionally with reservoir senescence. In a sample of 1,022 U.S. reservoirs, chronological age was not correlated with functional age. Functional age was directly related to percentage of cultivated land in the catchment and inversely related to reservoir depth. Moreover, aspects of reservoir fishing quality and fish population characteristics were related to functional age. A multimetric scale to indicate reservoir functional age presents the possibility for management intervention from multiple angles. If a reservoir is functionally aging at an accelerated rate, action may be taken to remedy the conditions contributing most to functional age. Intervention to reduce scores of selected metrics in the scale can potentially reduce the rate of senescence and increase the life expectancy of the reservoir. This leads to the intriguing implication that steps can be taken to reduce functional age and actually make the reservoir grow younger.

Potassium adsorption ratios as an indicator for the fate of agricultural potassium in groundwater

NARCIS (Netherlands)

Griffioen, J.

2001-01-01

Fertilization of agricultural land in groundwater infiltration areas often causes deterioration of groundwater quality. In addition to nitrogen and phosphorous, potassium deserves attention. The fate of potassium in the subsurface is controlled mainly by cation-exchange. Use of the Potassium

Using 81Kr-age of groundwater in the Guarani Aquifer, Brazil, to constrain estimates of continental degassing flux of 4He

Science.gov (United States)

Aggarwal, P. K.; Matsumoto, T.; Sturchio, N. C.; Chang, H. K.; Gastmans, D.; Lu, Z.; Jiang, W.; Müller, P.; Yokochi, R.; Han, L.; Klaus, P.; Torgersen, T.

2013-12-01

Continental degassing flux of helium is the dominant component of dissolved helium in deep groundwater together with that produced in-situ in the aquifer. A reliable estimate of the degassing flux is critical to the use of 4He as a dating tool in groundwater studies. The degassing flux is also important for understanding fluid and heat transport in the mantle and the rust. An independent tracer of groundwater age is required in order to deconvolute the two signals of the external, degassing flux and in situ production. Estimates of degassing flux mostly have relied upon shorter-lived radionuclides such as 14C and tritium and the resulting flux estimates have a significant variability (Torgersen, 2010). In the Guarani Aquifer in Brazil, an effective crustal 4He degassing flux into the aquifer was estimated from 81Kr ages ranging from about 70 Ka to 570 Ka. We then used the model framework of Toregesen and Ivey (1985), modified to include a diffusive reduction of originally uniform crustal helium flux from basement rocks through a thick sedimentary layer beneath the aquifer, to calculate a distribution of radiogenic 4He within the aquifer. With this framework, we obtain 4He ages that are consistent with ages based on 81Kr and 14C, and with a crustal degassing flux equivalent to that estimated from U and Th contents in the crust. The model framework for the Guarani Aquifer is also applied to data from other deep aquifers in Africa and Australia and our results suggest that the continental flux of 4He may be uniform, at least in stable continental areas. Additionally, a reliable estimate of the 4He degassing flux also helps to constrain the surficial discharge of deep groundwater.

Groundwater Discharges to Rivers in the Western Canadian Oil Sands Region

Science.gov (United States)

Ellis, J.; Jasechko, S.

2016-12-01

Groundwater discharges into rivers impacts the movement and fate of nutrients and contaminants in the environment. Understanding groundwater-surface water interactions is especially important in the western Canadian oil sands, where groundwater contamination risks are elevated and baseline water chemistry data is lacking, leading to substantial uncertainties about anthropogenic influences on local river quality. High salinity groundwater springs sourced from deep aquifers, comprised of Pleistocene-aged glacial meltwater, are known to discharge into many rivers in the oil sands. Understanding connections between deep aquifers and surficial waterways is important in order to determine natural inputs into these rivers and to assess the potential for injected wastewater or oil extraction fluids to enter surface waters. While these springs have been identified, their spatial distribution along rivers has not been fully characterized. Here we present river chemistry data collected along a number of major river corridors in the Canadian oil sands region. We show that saline groundwater springs vary spatially along the course of these rivers and tend to be concentrated where the rivers incise Devonian- or Cretaceous-aged aquifers along an evaporite dissolution front. Our results suggest that water sourced from Devonian aquifers may travel through bitumen-bearing Cretaceous units and discharge into local rivers, implying a strong groundwater-surface water connection in specialized locations. These findings indicate that oil sands process-affected waters that are injected at depth have the potential to move through these aquifers and reach the rivers at the surface at some time in the future. Groundwater-surface water interactions remain key to understanding the risks oil sands activities pose to aquatic ecosystems and downstream communities.

Excess air in groundwater as a potential indicator of past environmental changes

International Nuclear Information System (INIS)

Aeschenbach-Hertig, W.; Beyerle, U.; Holocher, J.; Peeters, F.; Kipfer, R.

2002-01-01

Dissolved noble gases in groundwater are used to reconstruct paleotemperature, but also yield information about 'excess air', a component of dissolved gases in excess of solubility equilibrium, derived from dissolution of trapped air in the ground. A good characterization of the excess air component is necessary not only to obtain reliable noble gas temperatures, but also to investigate the potential of excess air as a proxy for past environmental conditions. Two excess air related quantities can be derived from groundwater noble gas data sets: The initial air/water ratio and the pressure exerted on the entrapped air. Under recharge conditions typical for many aquifers, the excess of dissolved gases, expressed by the relative Ne excess ΔNe, is mainly determined by the hydrostatic pressure on the entrapped air. Thus, we suggest that ΔNe is essentially a measure of the amplitude of water table fluctuations in the recharge area. Comparing data sets from three aquifers in temperate, humid latitudes and three aquifers in tropical, semi-arid regions, we find that ΔNe is generally higher in the tropical aquifers, possibly related to larger water table fluctuations in these aquifers characterized by deep unsaturated zones. Whereas ΔNe shows little temporal variation in the mid-latitude aquifers, there is a strong signal of higher ΔNe in the paleowaters of the tropical aquifers as compared to water recharged under modern climate conditions. This finding may indicate a higher variability of recharge in the past at the studied tropical sites. (author)

Kalahari groundwaters: Their hydrogen, carbon and oxygen isotopes

International Nuclear Information System (INIS)

Mazor, E.; Verhagen, B.T.; Sellschop, J.P.F.; Robins, N.S.; Hutton, L.G.

1974-01-01

Tritium and 14 C measurements have revealed several cases of post-nuclear bomb-test rain recharge of local groundwaters, along with values indicating recharge over larger, yet hydrologically active, time scales. In general, recharge seems to follow rain distribution in being more intense in the northern rather than in the southern Kalahari. Initial δ 13 C values vary over a wide range and reveal some correlation to pH and chemical composition of the water. They cannot be used to correct for fossil carbon dilution in 14 C-age calculations. Radiocarbon-deduced ages range from recent to 30,000 years. Stable hydrogen and oxygen isotopes indicate recharge from direct rain infiltration. (author)

Marine water from mid-Holocene sea level highstand trapped in a coastal aquifer: Evidence from groundwater isotopes, and environmental significance

Energy Technology Data Exchange (ETDEWEB)

Lee, Stephen [School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne (Australia); Currell, Matthew, E-mail: Matthew.currell@rmit.edu.au [School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne (Australia); Cendón, Dioni I. [Australian Nuclear Science and Technology Organisation, Kirrawee (Australia); Connected Water Initiative, School of Biological, Earth and Environmental Sciences, University of New South Wales (UNSW), Sydney (Australia)

2016-02-15

A multi-layered coastal aquifer in southeast Australia was assessed using environmental isotopes, to identify the origins of salinity and its links to palaeo-environmental setting. Spatial distribution of groundwater salinity (electrical conductivity values ranging from 0.395 to 56.1 mS/cm) was examined along the coastline along with geological, isotopic and chemical data. This allowed assessment of different salinity sources and emplacement mechanisms. Molar chloride/bromide ratios range from 619 to 1070 (621 to 705 in samples with EC > 15 mS/cm), indicating salts are predominantly marine. Two distinct vertical salinity profiles were observed, one with increasing salinity with depth and another with saline shallow water overlying fresh groundwater. The saline shallow groundwater (EC = 45.4 to 55.7 mS/cm) has somewhat marine-like stable isotope ratios (δ{sup 18}O = − 2.4 to − 1.9 ‰) and radiocarbon activities indicative of middle Holocene emplacement (47.4 to 60.4 pMC). This overlies fresher groundwater with late Pleistocene radiocarbon ages and meteoric stable isotopes (δ{sup 18}O = − 5.5 to − 4.6‰). The configuration suggests surface inundation of the upper sediments by marine water during the mid-Holocene (c. 2–8 kyr BP), when sea level was 1–2 m above today's level. Profiles of chloride, stable isotopes, and radiocarbon indicate mixing between this pre-modern marine water and fresh meteoric groundwater to varying degrees around the coastline. Mixing calculations using chloride and stable isotopes show that in addition to fresh-marine water mixing, some salinity is derived from transpiration by halophytic vegetation (e.g. mangroves). The δ{sup 13}C ratios in saline water (− 17.6 to − 18.4‰) also have vegetation/organic matter signatures, consistent with emplacement by surface inundation and extensive interaction between vegetation and recharging groundwater. Saline shallow groundwater is preserved only in areas where low

Statin prescribing according to gender, age and indication

DEFF Research Database (Denmark)

Wallach-Kildemoes, Helle; Støvring, Henrik; Holme Hansen, Ebba

2016-01-01

RATIONALES, AIMS AND OBJECTIVES: The increasing dispensing of statins has raised concern about the appropriateness of prescribing to various population groups. We aimed to (1) investigate incident and prevalent statin prescribing according to indication, gender and age and (2) relate prescribing...... patterns to evidence on beneficial and adverse effects. METHODS: A cohort of Danish inhabitants (n = 4 424 818) was followed in nationwide registries for dispensed statin prescriptions and hospital discharge information. We calculated incidence rates (2005-2009), prevalence trends (2000-2010) and absolute...... numbers of statin users according to register proxies for indication, gender and age. RESULTS: In 2010, the prevalence became highest for ages 75-84 and was higher in men than women (37% and 33%, respectively). Indication-specific incidences and prevalences peaked at ages around 65-70, but in myocardial...

Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China.

Science.gov (United States)

Han, Dongmei; Cao, Guoliang; McCallum, James; Song, Xianfang

2015-12-15

Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33-521mg/L) in NO3(-) concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ(18)O, δ(2)H) analysis, (3)H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from -8.5 to -7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92-467years) and the NO3(-) concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8-411years) and the NO3(-) concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be transported for tens of years, through the complex carbonate

Effects of groundwater-flow paths on nitrate concentrations across two riparian forest corridors

Science.gov (United States)

Speiran, Gary K.

2010-01-01

Groundwater levels, apparent age, and chemistry from field sites and groundwater-flow modeling of hypothetical aquifers collectively indicate that groundwater-flow paths contribute to differences in nitrate concentrations across riparian corridors. At sites in Virginia (one coastal and one Piedmont), lowland forested wetlands separate upland fields from nearby surface waters (an estuary and a stream). At the coastal site, nitrate concentrations near the water table decreased from more than 10 mg/L beneath fields to 2 mg/L beneath a riparian forest buffer because recharge through the buffer forced water with concentrations greater than 5 mg/L to flow deeper beneath the buffer. Diurnal changes in groundwater levels up to 0.25 meters at the coastal site reflect flow from the water table into unsaturated soil where roots remove water and nitrate dissolved in it. Decreases in aquifer thickness caused by declines in the water table and decreases in horizontal hydraulic gradients from the uplands to the wetlands indicate that more than 95% of the groundwater discharged to the wetlands. Such discharge through organic soil can reduce nitrate concentrations by denitrification. Model simulations are consistent with field results, showing downward flow approaching toe slopes and surface waters to which groundwater discharges. These effects show the importance of buffer placement over use of fixed-width, streamside buffers to control nitrate concentrations.

Isotopes reveal dynamics of groundwater system in Region 2, Philippines

International Nuclear Information System (INIS)

Mendoza, N.D.S.; Racadio, C.D.T.; Sucgang, R.J.; Castañeda, S.S.

2015-01-01

Steady economic and population growth in Region 2 could lead to an exponential increase freshwater demand. However, region 2’s main source of freshwater is groundwater and, if not checked and managed carefully, it could eventually affect the availability and sustainability of groundwater resources in Water Resource Region 2 (WRR2). Stable isotopes along with Tritium analysis in different water bodies such as rain, shallow and deep groundwater, springs and rivers were used to gain insight about the hydrological process in WRR2. Local meteoric water line for WRR2 was found to be δ2H = 8.6 δ 18O + 13.3 (r = 0.98). The estimated annual mean, which was used as a local index was to be -7.1 ‰ δ “1”8O_v_s_m_o_w_-_s_l_a_p. Shallow wells (20 – 30 m) and production wells (multi-screened wells, max depth of about 100 – 120m) were found to exhibit relatively more enrich than the index (i.e. -7.1‰) with means of -6.2 ‰ (s.d. 1.1‰, n=19) and -6.6 ‰ (s.d. 0.9; n= 151), respectively, which was an indication of infiltration of evaporated waters possibly from river and irrigation waters. Tritium analysis were done on selected sites to identify groundwater age (GWA) and possibly track the flow of groundwater from recharge areas (such as in Nueva Vizcaya, GWA = 3 years) down to the plains (Tuguegarao, GWA range from 9 to 30 years). Groundwaters drawn from production wells in Tuguegarao with ages of more than 30 years suggest that more fraction of water were being drawn from deeper aquifers. Such scenario could mean that were less water in shallow aquifers (e.g. 30 m deep) which are typically younger in age than waters found at deeper aquifers (e.g. 100 m deep). (author)

Oxygen isotope composition as late glacial palaeoclimate indicators of groundwater recharge in the Baltic Basin

International Nuclear Information System (INIS)

Mokrik, R.; Mazeika, J.

2002-01-01

Several hypotheses were established to explain low δ 18 O values of groundwater which have been found in the Estonian Homocline. Traces of depleted groundwater were found also in other parts of the Baltic Basin near the shoreline. From data collected in this and previous studies, the δ 18 O values of groundwater in most aquifers are known to range from -7.7 to -13.9 per mille. However, the groundwater in Estonia in the Cambrian-Vendian aquifer system has significantly lower δ 18 O values, which vary mainly from -18 to -22.5 per mille. The overlying Ordovician-Cambrian aquifer is also depleted in 18 O, but, as a rule, the degree of depletion is several per mille less than in case of the Cambrian- Vendian aquifer. The thickness of the depleted water in Estonia reaches 450 m. At similar depths beneath Gotland Island (Sweden Homocline), groundwater has significantly higher δ 18 O values (from -5.7 to -6.1 per mille). A hydrogeologic model, depicting conditions during the pre Late Glacial, and accounting for hydraulic connections between the lake and river systems through taliks in permafrost, was developed to explain the observed groundwater isotope data. According to the adopted model, penetration of isotopically depleted surface waters could have reached depths of up to 500 m, with subsequent mixing between subglacial meltwater and old groundwater of Huneborg-Denekamp time. Traces of this penetration were discovered only near the shoreline, where δ 18 O values vary from -12 to -13.9 per mille and 14 C is below 4%. In the territory of the Estonian Homocline, the hydraulically close connection via the Cambrian-Vendian aquifer between talik systems of the Gulf of Riga and the Gulf of Finland existed through permafrost before the Late Glacial. This was due to subglacial recharge during the recessional Pandivere (12 ka BP) and Palivere (11.2 ka BP) phases, which is also associated with recharge of isotopically depleted groundwater. (author)

Influence of basalt/groundwater interactions on radionuclide migration

International Nuclear Information System (INIS)

Vandegrift, G.F.

1984-01-01

The work presented here is a partial summary of the experimental results obtained in the Laboratory Analog Program. Two aspects of this effort are (1) the interaction between simulated basaltic groundwater and basalt fissures that were either freshly cleaved or laboratory altered by hydrothermal treatment with the simulated groundwater and (2) the effect of this interaction on radionuclide migration through these basalt fissures. The following conclusions of this study bear heavily on the predicted safety of a basalt repository: Sorption properties of freshly fissured basalt and naturally aged basalt are quite different for different chemical species. Analog experiments predict that aged basalt would be an effective retarder of cesium, but would be much less so for actinide elements. Distribution ratios measured from batch experiments with finely ground rock samples (presenting unaltered rock surfaces) are not a reliable means of predicting radionuclide migration in geological repositories. As the near-repository area is resaturated by groundwater, its ability to retard actinide migration will be degraded with time. Disturbing the natural flow of groundwater through the repository area by constructing and backfilling the repository will modify the composition of groundwater. This modified groundwater is likely to interact with and to modify naturally aged basalt surfaces downstream from the repository

Evaluation of baseline ground-water conditions in the Mosteiros, Ribeira Paul, and Ribeira Fajã Basins, Republic of Cape Verde, West Africa, 2005-06

Science.gov (United States)

Heilweil, Victor M.; Earle, John D.; Cederberg, Jay R.; Messer, Mickey M.; Jorgensen, Brent E.; Verstraeten, Ingrid M.; Moura, Miguel A.; Querido, Arrigo; Spencer,; Osorio, Tatiana

2006-01-01

This report documents current (2005-06) baseline ground-water conditions in three basins within the West African Republic of Cape Verde (Mosteiros on Fogo, Ribeira Paul on Santo Antão, and Ribeira Fajã on São Nicolau) based on existing data and additional data collected during this study. Ground-water conditions (indicators) include ground-water levels, ground-water recharge altitude, ground-water discharge amounts, ground-water age (residence time), and ground-water quality. These indicators are needed to evaluate (1) long-term changes in ground-water resources or water quality caused by planned ground-water development associated with agricultural projects in these basins, and (2) the feasibility of artificial recharge as a mitigation strategy to offset the potentially declining water levels associated with increased ground-water development.Ground-water levels in all three basins vary from less than a few meters to more than 170 meters below land surface. Continuous recorder and electric tape measurements at three monitoring wells (one per basin) showed variations between August 2005 and June 2006 of as much as 1.8 meters. Few historical water-level data were available for the Mosteiros or Ribeira Paul Basins. Historical records from Ribeira Fajã indicate very large ground-water declines during the 1980s and early 1990s, associated with dewatering of the Galleria Fajã tunnel. More-recent data indicate that ground-water levels in Ribeira Fajã have reached a new equilibrium, remaining fairly constant since the late 1990s.Because of the scarcity of observation wells within each basin, water-level data were combined with other techniques to evaluate ground-water conditions. These techniques include the quantification of ground-water discharge (well withdrawals, spring discharge, seepage to springs, and gallery drainage), field water-quality measurements, and the use of environmental tracers to evaluate sources of aquifer recharge, flow paths, and ground-water

Modelling the distribution of tritium in groundwater across South Africa to assess the vulnerability and sustainability of groundwater resources in response to climate change

Science.gov (United States)

van Rooyen, Jared; Miller, Jodie; Watson, Andrew; Butler, Mike

2017-04-01

Groundwater is critical for sustaining human populations, especially in semi-arid to arid areas, where surface water availability is low. Shallow groundwater is usually abstracted for this purpose because it is the easiest to access and assumed to be renewable and regularly recharged by precipitation. Renewable, regularly recharged groundwater is also called modern groundwater, ie groundwater that has recently been in contact with the atmosphere. Tritium can be used to determine whether or not a groundwater resource is modern because the half-life of tritium is only 12.36 years and tritium is dominantly produced in the upper atmosphere and not in the rock mass. For this reason, groundwater with detectable tritium activities likely has a residence age of less than 50 years. In this study, tritium activities in 277 boreholes distributed across South Africa were used to develop a national model for tritium activity in groundwater in order to establish the extent of modern groundwater across South Africa. The tritium model was combined with modelled depth to water using 3079 measured static water levels obtained from the National Groundwater Archive and validated against a separate set of 40 tritium activities along the west coast of South Africa. The model showed good agreement with the distribution of rainfall which has been previously documented across the globe (Gleeson et al., 2015), although the arid Karoo basin in south west South Africa shows higher than expected tritium levels given the very low regional precipitation levels. To assess the vulnerability of groundwater to degradation in quality and quantity, the tritium model was incorporated into a multi-criteria evaluation (MCE) model which incorporated other indicators of groundwater stress including mean annual precipitation, mean annual surface temperature, electrical conductivity (as a proxy for groundwater salinization), potential evaporation, population density and cultivated land usage. The MCE model

Sources of groundwater and characteristics of surface-water recharge at Bell, White, and Suwannee Springs, Florida, 2012–13

Science.gov (United States)

Stamm, John F.; McBride, W. Scott

2016-12-21

considered together, evidence from water-level, specific conductance, major-ion concentration, and isotope data indicated that groundwater at Bell Springs and the UFA well was a mixture of surface water and groundwater from the upper confining unit, and that groundwater at White and Suwannee Springs was a mixture of surface water, groundwater from the upper confining unit, and groundwater from the Upper Floridan aquifer. Higher concentrations of magnesium in groundwater samples at the UFA well than in samples at Bell Springs might indicate less mixing with surface water at the UFA well than at Bell Springs. Characteristics of surface-water recharge, such as residence time at the surface, apparent age, and recharge water temperature, were estimated on the basis of isotopic ratios, and dissolved concentrations of gases such as argon, tritium, and sulfur hexafluoride. Oxygen and deuterium isotopic ratios were consistent with rapid recharge by rainwater for samples collected in 2012, and longer residence time at the surface (ponding) for samples collected in 2013. Apparent ages of groundwater samples, computed on the basis of tritium activity and sulfur hexafluoride concentration, indicated groundwater recharge occurred after the late 1980s; however, the estimated apparent ages likely represent the average of ages of multiple sources. Recharge since the 1980s is consistent with groundwater from shallow sources, such as the upper confining unit and Upper Floridan aquifer. Recharge water temperature computed for the three springs and UFA well averaged 20.1 degrees Celsius, which is similar to the mean annual air temperature of 20.6 degrees Celsius at a nearby weather station for 1960–2014.

Pollution indicators in groundwater of two agricultural catchments in Lower Silesia (Poland)

Science.gov (United States)

Kasperczyk, Lidia; Modelska, Magdalena; Staśko, Stanisław

2016-12-01

The article discusses the content and source of mineral nitrogen compounds in groundwater, based on the data collected in two river catchments in two series (spring and autumn 2014). The study area comprises two catchments located in Lower Silesia, Poland - Cicha Woda and Sąsiecznica. Both catchments are characterised agricultural character of development. In the both researched areas, the points of State Environmental Monitoring (SEM) are located but only the Cicha Woda area is classified as nitrate vulnerable zone (NVZ). To analyse and compare the contamination of Quaternary and Neogene aquifers, the concentration of nitrates, nitrites, ammonium and potassium ions was measured primarily. Results showed the exceedance of nitrogen mineral forms of shallow groundwater Quaternary aquifer in both basins. The concentration of nitrates range from 0.08 to 142.12 mgNO3 -/dm3 (Cicha Woda) and from 2.6 to 137.65 mg NO3 -/dm3 (Sąsiecznica). The major source of pollution is probably the intensive agriculture activity. It causes a degradation of the shallow groundwater because of nitrate, nitrite, potassium, phosphates and ammonium contents. There was no observed contamination of anthropogenic origin in the deeper Neogene aquifer of Cicha Woda catchment.

Dry Stream Reaches in Carbonate Terranes: Surface Indicators of Ground-Water Reservoirs

Science.gov (United States)

Brahana, J.V.; Hollyday, E.F.

1988-01-01

In areas where dry stream reaches occur, subsurface drainage successfully competes with surface drainage, and sheet-like dissolution openings have developed parallel to bedding creating the ground-water reservoir. Union Hollow in south-central Tennessee is the setting for a case study that illustrates the application of the dry stream reach technique. In this technique, dry stream reach identification is based on two types of readily acquired information: remotely sensed black and white infrared aerial photography; and surface reconnaissance of stream channel characteristics. Test drilling in Union Hollow subsequent to identification of the dry reach proved that a localized ground-water reservoir was present.

Geochemical and isotopic determination of deep groundwater contributions and salinity to the shallow groundwater and surface water systems, Mesilla Basin, New Mexico, Texas, and Mexico

Science.gov (United States)

Robertson, A.; Carroll, K. C.; Kubicki, C.; Purtshert, R.

2017-12-01

The Mesilla Basin/Conejos-Médanos aquifer system, extending from southern New Mexico to Chihuahua, Mexico, is a priority transboundary aquifer under the 2006 United States­-Mexico Transboundary Aquifer Assessment Act. Declining water levels, deteriorating water quality, and increasing groundwater use by municipal, industrial, and agricultural users on both sides of the international border raise concerns about long-term aquifer sustainability. Relative contributions of present-day and "paleo" recharge to sustainable fresh groundwater yields has not been determined and evidence suggests that a large source of salinity at the distal end of the Mesilla Basin is saline discharge from deep groundwater flow. The magnitude and distribution of those deep saline flow paths are not determined. The contribution of deep groundwater to discharge and salinity in the shallow groundwater and surface water of the Mesilla Basin will be determined by collecting discrete groundwater samples and analyzing for aqueous geochemical and isotopic tracers, as well as the radioisotopes of argon and krypton. Analytes include major ions, trace elements, the stable isotopes of water, strontium and boron isotopes, uranium isotopes, the carbon isotopes of dissolved inorganic carbon, noble gas concentrations and helium isotope ratios. Dissolved gases are extracted and captured from groundwater wells using membrane contactors in a process known as ultra-trace sampling. Gas samples are analyzed for radioisotope ratios of krypton by the ATTA method and argon by low-level counting. Effectiveness of the ultra-trace sampling device and method was evaluated by comparing results of tritium concentrations to the krypton-85 content. Good agreement between the analyses, especially in samples with undetectable tritium, indicates that the ultra-trace procedure is effective and confirms that introduction of atmospheric air has not occurred. The geochemistry data indicate a complex system of geochemical

Origins and bioavailability of dissolved organic matter in groundwater

Science.gov (United States)

Shen, Yuan; Chapelle, Francis H.; Strom, Eric W.; Benner, Ronald

2015-01-01

Dissolved organic matter (DOM) in groundwater influences water quality and fuels microbial metabolism, but its origins, bioavailability and chemical composition are poorly understood. The origins and concentrations of dissolved organic carbon (DOC) and bioavailable DOM were monitored during a long-term (2-year) study of groundwater in a fractured-rock aquifer in the Carolina slate belt. Surface precipitation was significantly correlated with groundwater concentrations of DOC, bioavailable DOM and chromophoric DOM, indicating strong hydrological connections between surface and ground waters. The physicochemical and biological processes shaping the concentrations and compositions of DOM during its passage through the soil column to the saturated zone are conceptualized in the regional chromatography model. The model provides a framework for linking hydrology with the processes affecting the transformation, remineralization and microbial production of DOM during passage through the soil column. Lignin-derived phenols were relatively depleted in groundwater DOM indicating substantial removal in the unsaturated zone, and optical properties of chromophoric DOM indicated lower molecular weight DOM in groundwater relative to surface water. The prevalence of glycine, γ-aminobutyric acid, and d-enantiomers of amino acids indicated the DOM was highly diagenetically altered. Bioassay experiments were used to establish DOC-normalized yields of amino acids as molecular indicators of DOM bioavailability in groundwater. A relatively small fraction (8 ± 4 %) of DOC in groundwater was bioavailable. The relatively high yields of specific d-enantiomers of amino acids indicated a substantial fraction (15–34 %) of groundwater DOC was of bacterial origin.

Hydrogeology, simulated ground-water flow, and ground-water quality, Wright-Patterson Air Force Base, Ohio

Science.gov (United States)

Dumouchelle, D.H.; Schalk, C.W.; Rowe, G.L.; De Roche, J.T.

1993-01-01

Ground water is the primary source of water in the Wright-Patterson Air Force Base area. The aquifer consists of glacial sands and gravels that fill a buried bedrock-valley system. Consolidated rocks in the area consist of poorly permeable Ordovician shale of the Richmondian stage, in the upland areas, the Brassfield Limestone of Silurian age. The valleys are filled with glacial sediments of Wisconsinan age consisting of clay-rich tills and coarse-grained outwash deposits. Estimates of hydraulic conductivity of the shales based on results of displacement/recovery tests range from 0.0016 to 12 feet per day; estimates for the glacial sediments range from less than 1 foot per day to more than 1,000 feet per day. Ground water flow from the uplands towards the valleys and the major rivers in the region, the Great Miami and the Mad Rivers. Hydraulic-head data indicate that ground water flows between the bedrock and unconsolidated deposits. Data from a gain/loss study of the Mad River System and hydrographs from nearby wells reveal that the reach of the river next to Wright-Patterson Air Force Base is a ground-water discharge area. A steady-state, three-dimensional ground-water-flow model was developed to simulate ground-water flow in the region. The model contains three layers and encompasses about 100 square miles centered on Wright-Patterson Air Force Base. Ground water enters the modeled area primarily by river leakage and underflow at the model boundary. Ground water exits the modeled area primarily by flow through the valleys at the model boundaries and through production wells. A model sensitivity analysis involving systematic changes in values of hydrologic parameters in the model indicates that the model is most sensitive to decreases in riverbed conductance and vertical conductance between the upper two layers. The analysis also indicates that the contribution of water to the buried-valley aquifer from the bedrock that forms the valley walls is about 2 to 4

Hydrochemistry of the Mahomet Bedrock Valley Aquifer, East-Central Illinois: indicators of recharge and ground-water flow

Science.gov (United States)

Panno, S.V.; Hackley, Keith C.; Cartwright, K.; Liu, Chao-Li

1994-01-01

A conceptual model of the ground-water flow and recharge to the Mahomet Bedrock Valley Aquifer (MVA), east-central Illinois, was developed using major ion chemistry and isotope geochemistry. The MVA is a 'basal' fill in the east-west trending buried bedrock valley composed of clean, permeable sand and gravel to thicknesses of up to 61 m. It is covered by a thick sequence of glacial till containing thinner bodies of interbedded sand and gravel. Ground water from the MVA was found to be characterized by clearly defined geochemical regions with three distinct ground-water types. A fourth ground-water type was found at the confluence of the MVA and the Mackinaw Bedrock Valley Aquifer (MAK) to the west. Ground water in the Onarga Valley, a northeastern tributary of the MVA, is of two types, a mixed cation-SO42- type and a mixed cation-HCO3- type. The ground water is enriched in Na+, Ca2+, Mg2+, and SO42- which appears to be the result of an upward hydraulic gradient and interaction of deeper ground water with oxidized pyritic coals and shale. We suggest that recharge to the Onarga Valley and overlying aquifers is 100% from bedrock (leakage) and lateral flow from the MVA to the south. The central MVA (south of the Onarga Valley) is composed of relatively dilute ground water of a mixed cation-HCO3- type, with low total dissolved solids, and very low concentrations of Cl- and SO42-. Stratigraphic relationships of overlying aquifers and ground-water chemistry of these and the MVA suggest recharge to this region of the MVA (predominantly in Champaign County) is relatively rapid and primarily from the surface. Midway along the westerly flow path of the MVA (western MVA), ground water is a mixed cation-HCO3- type with relatively high Cl-, where Cl- increases abruptly by one to ??? two orders of magnitude. Data suggest that the increase in Cl- is the result of leakage of saline ground water from bedrock into the MVA. Mass-balance calculations indicate that approximately 9.5% of

Assessment of groundwater salinization mechanisms in Santiago Island - Cabo Verde: An environmental isotopic approach

International Nuclear Information System (INIS)

Carreira, P.M.; Nunes, D.; Marques, J.M.; Pina, A.; Mota Gomes, A.; Almeida, E.; Goncalves, R.; Monteiro Santos, F.

2007-01-01

Two sampling campaigns were carried out at Santiago Island - Cabo Verde under the scope of an isotopic and geochemical research study. An evaluation of the groundwater systems was carried out through the application of environmental isotopes and geochemical data in order to answer questions such as: origin and mechanisms of groundwater recharge; relation between the hydrochemical evolution of the groundwater systems with the geological matrix (minerals dissolution) or mixture with seawater and aerosol marine influence; identification of seawater intrusion mechanisms and, determination of the apparent groundwater 'age'. The results obtained so far are not conclusive on the identification of the process responsible for the increase of salinity. In general, all the data obtained seems to indicate that the waters have the same isotopic history but different geochemical evolution, which depends on the weathering and permeability of the rocks. (author)

Simulation of Ground-Water Flow and Effects of Ground-Water Irrigation on Base Flow in the Elkhorn and Loup River Basins, Nebraska

Science.gov (United States)

Peterson, Steven M.; Stanton, Jennifer S.; Saunders, Amanda T.; Bradley, Jesse R.

2008-01-01

Irrigated agriculture is vital to the livelihood of communities in the Elkhorn and Loup River Basins in Nebraska, and ground water is used to irrigate most of the cropland. Concerns about the sustainability of ground-water and surface-water resources have prompted State and regional agencies to evaluate the cumulative effects of ground-water irrigation in this area. To facilitate understanding of the effects of ground-water irrigation, a numerical computer model was developed to simulate ground-water flow and assess the effects of ground-water irrigation (including ground-water withdrawals, hereinafter referred to as pumpage, and enhanced recharge) on stream base flow. The study area covers approximately 30,800 square miles, and includes the Elkhorn River Basin upstream from Norfolk, Nebraska, and the Loup River Basin upstream from Columbus, Nebraska. The water-table aquifer consists of Quaternary-age sands and gravels and Tertiary-age silts, sands, and gravels. The simulation was constructed using one layer with 2-mile by 2-mile cell size. Simulations were constructed to represent the ground-water system before 1940 and from 1940 through 2005, and to simulate hypothetical conditions from 2006 through 2045 or 2055. The first simulation represents steady-state conditions of the system before anthropogenic effects, and then simulates the effects of early surface-water development activities and recharge of water leaking from canals during 1895 to 1940. The first simulation ends at 1940 because before that time, very little pumpage for irrigation occurred, but after that time it became increasingly commonplace. The pre-1940 simulation was calibrated against measured water levels and estimated long-term base flow, and the 1940 through 2005 simulation was calibrated against measured water-level changes and estimated long-term base flow. The calibrated 1940 through 2005 simulation was used as the basis for analyzing hypothetical scenarios to evaluate the effects of

Natural radionuclides in groundwaters

International Nuclear Information System (INIS)

Laul, J.C.

1990-01-01

The U-234 and Th-230 radionuclides are highly retarded by factors of 10 4 to 10 5 in basalt groundwater (Hanford) and briny groundwaters from Texas and geothermal brine from the Salton Sea Geothermal Field (SSGF). In basalt groundwaters (low ionic strength), Ra is highly sorbed, while in brines (high ionic strength), Ra is soluble. This is probably because the sorption sites are saturated with Na + and Cl - ions and RaCl 2 is soluble in brines. Pb-210 is soluble in SSGF brine, probably as a chloride complex. The U-234/Th-230 ratios in basalt groundwaters and brines from Texas and SSGF are nearly unity, indicating that U is in the +4 state, suggesting a reducing environment for these aquifers. 19 refs., 3 figs

Nitrate in groundwater of the United States, 1991-2003

Science.gov (United States)

Burow, Karen R.; Nolan, Bernard T.; Rupert, Michael G.; Dubrovsky, Neil M.

2010-01-01

An assessment of nitrate concentrations in groundwater in the United States indicates that concentrations are highest in shallow, oxic groundwater beneath areas with high N inputs. During 1991-2003, 5101 wells were sampled in 51 study areas throughout the U.S. as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) program. The well networks reflect the existing used resource represented by domestic wells in major aquifers (major aquifer studies), and recently recharged groundwater beneath dominant land-surface activities (land-use studies). Nitrate concentrations were highest in shallow groundwater beneath agricultural land use in areas with well-drained soils and oxic geochemical conditions. Nitrate concentrations were lowest in deep groundwater where groundwater is reduced, or where groundwater is older and hence concentrations reflect historically low N application rates. Classification and regression tree analysis was used to identify the relative importance of N inputs, biogeochemical processes, and physical aquifer properties in explaining nitrate concentrations in groundwater. Factors ranked by reduction in sum of squares indicate that dissolved iron concentrations explained most of the variation in groundwater nitrate concentration, followed by manganese, calcium, farm N fertilizer inputs, percent well-drained soils, and dissolved oxygen. Overall, nitrate concentrations in groundwater are most significantly affected by redox conditions, followed by nonpoint-source N inputs. Other water-quality indicators and physical variables had a secondary influence on nitrate concentrations.

Uranium in groundwater from Western Haryana, India

International Nuclear Information System (INIS)

Balvinder Singh; Nawal Kishore; Vandana Pulhani

2014-01-01

This study was undertaken to assess uranium in groundwater and radiological and chemical risks associated with its ingestion in rural habitats in the vicinity of proposed nuclear power project in Western Haryana, India. Uranium concentration in the groundwater of the study area varied from 0.3 to 256.4 μg L -1 . Radiological risk calculated in the form of average life time dose was found 5.1 × 10 -2 mSv to the residents of the area from the ingestion of groundwater. The average cancer mortality and average cancer morbidity risk were calculated to be 4.9 × 10 -6 and 7.7 × 10 -6 respectively indicating the absence of carcinogenic risks. Chemical risk was in the range of 0.02-18.8 μg kg -1 day -1 . Hazard quotient for 72 % samples was greater than unity which indicates health risk due to chemical toxicity of uranium in groundwater. The results indicate that uranium concentrations in the groundwater of the study area are important due to chemical risk than radiological risk. (author)

Isotope characteristics of groundwater in Beishan area

International Nuclear Information System (INIS)

Guo Yonghai; Liu Shufen; Lu Chuanhe

2004-01-01

Using the isotope techniques, the authors studied the origin, evolution and circulation of the groundwater in the potential site of China's high-level waste repository. The results indicate that both deep groundwater and shallow groundwater are mainly recharged by modern and local precipitation, and the deep groundwater in the site area is of meteoric origin. The shallow groundwater is mainly recharged by modern and local precipitation, and the deep groundwater originates from regional precipitation at higher elevation, or might be derived from the precipitation during the geological period of lower temperature. It is also known from the study that the deep underground is a system of very low-permeability where the groundwater flow rates are very low. (author)

Radium mobility and the age of groundwater in public-drinking-water supplies from the Cambrian-Ordovician aquifer system, north-central USA

Science.gov (United States)

Stackelberg, Paul E.; Szabo, Zoltan; Jurgens, Bryant C.

2018-01-01

High radium (Ra) concentrations in potable portions of the Cambrian-Ordovician (C-O) aquifer system were investigated using water-quality data and environmental tracers (3H, 3Hetrit, SF6, 14C and 4Herad) of groundwater age from 80 public-supply wells (PSWs). Groundwater ages were estimated by calibration of tracers to lumped parameter models and ranged from modern (1 Myr) in the most downgradient, confined portions of the potable system. More than 80 and 40 percent of mean groundwater ages were older than 1000 and 50,000 yr, respectively. Anoxic, Fe-reducing conditions and increased mineralization develop with time in the aquifer system and mobilize Ra into solution resulting in the frequent occurrence of combined Ra (Rac = 226Ra + 228Ra) at concentrations exceeding the USEPA MCL of 185 mBq/L (5 pCi/L). The distribution of the three Ra isotopes comprising total Ra (Rat = 224Ra + 226Ra + 228Ra) differed across the aquifer system. The concentrations of 224Ra and 228Ra were strongly correlated and comprised a larger proportion of the Rat concentration in samples from the regionally unconfined area, where arkosic sandstones provide an enhanced source for progeny from the 232Th decay series. 226Ra comprised a larger proportion of the Ratconcentration in samples from downgradient confined regions. Concentrations of Rat were significantly greater in samples from the regionally confined area of the aquifer system because of the increase in 226Ra concentrations there as compared to the regionally unconfined area. 226Ra distribution coefficients decreased substantially with anoxic conditions and increasing ionic strength of groundwater (mineralization), indicating that Ra is mobilized to solution from solid phases of the aquifer as adsorption capacity is diminished. The amount of 226Ra released from solid phases by alpha-recoil mechanisms and retained in solution increases relative to the amount of Ra sequestered by adsorption processes or co

Arsenic speciation and uranium concentrations in drinking water supply wells in Northern Greece: Correlations with redox indicative parameters and implications for groundwater treatment

International Nuclear Information System (INIS)

Katsoyiannis, Ioannis A.; Hug, Stephan J.; Ammann, Adrian; Zikoudi, Antonia; Hatziliontos, Christodoulos

2007-01-01

The cities in the Aksios and Kalikratia areas in Northern Greece rely on arsenic contaminated groundwater for their municipal water supply. As remedial action strongly depends on arsenic speciation, the presence of other possible contaminants, and on the general water composition, a detailed study with samples from 21 representative locations was undertaken. Arsenic concentrations were typically 10-70 μg/L. In the groundwaters of the Aksios area with lower Eh values (87-172 mV), pH 7.5-8.2 and 4-6 mM HCO 3 alkalinity, As(III) predominated. Manganese concentrations were mostly above the EC standard of 0.05 mg/L (0.1-0.7 mg/L). In groundwaters of the Kalikratia area with higher Eh values (272-352 mV), pH 6.7-7.5 and 6-12 mM HCO 3 alkalinity, As(V) was the main species. Uranium in the groundwaters was also investigated and correlations with total arsenic concentrations and speciation were examined to understand more of the redox chemistry of the examined groundwaters. Uranium concentrations were in the range 0.01-10 μg/L, with the higher concentrations to occur in the oxidizing groundwaters of the Kalikratia area. Uranium and total arsenic concentrations showed no correlation, whereas uranium concentrations correlated strongly with As(III)/As(tot) ratios, depicting their use as a possible indicator of groundwater redox conditions. Finally, boron was found to exceed the EC drinking water standard of 1 mg/L in some wells in the Kalikratia area and its removal should also be considered in the design of a remedial action

Evaluation of high-frequency mean streamwater transit-time estimates using groundwater age and dissolved silica concentrations in a small forested watershed

Science.gov (United States)

Peters, Norman E.; Burns, Douglas A.; Aulenbach, Brent T.

2014-01-01

Many previous investigations of mean streamwater transit times (MTT) have been limited by an inability to quantify the MTT dynamics. Here, we draw on (1) a linear relation (r 2 = 0.97) between groundwater 3H/3He ages and dissolved silica (Si) concentrations, combined with (2) predicted streamwater Si concentrations from a multiple-regression relation (R 2 = 0.87) to estimate MTT at 5-min intervals for a 23-year time series of streamflow [water year (WY) 1986 through 2008] at the Panola Mountain Research Watershed, Georgia. The time-based average MTT derived from the 5-min data was ~8.4 ± 2.9 years and the volume-weighted (VW) MTT was ~4.7 years for the study period, reflecting the importance of younger runoff water during high flow. The 5-min MTTs are normally distributed and ranged from 0 to 15 years. Monthly VW MTTs averaged 7.0 ± 3.3 years and ranged from 4 to 6 years during winter and 8–10 years during summer. The annual VW MTTs averaged 5.6 ± 2.0 years and ranged from ~5 years during wet years (2003 and 2005) to >10 years during dry years (2002 and 2008). Stormflows are composed of much younger water than baseflows, and although stormflow only occurs ~17 % of the time, this runoff fraction contributed 39 % of the runoff during the 23-year study period. Combining the 23-year VW MTT (including stormflow) with the annual average baseflow for the period (~212 mm) indicates that active groundwater storage is ~1,000 mm. However, the groundwater storage ranged from 1,040 to 1,950 mm using WY baseflow and WY VW MTT. The approach described herein may be applicable to other watersheds underlain by granitoid bedrock, where weathering is the dominant control on Si concentrations in soils, groundwater, and streamwater.

Assessing regional groundwater stress for nations using multiple data sources with the groundwater footprint

International Nuclear Information System (INIS)

Gleeson, Tom; Wada, Yoshihide

2013-01-01

Groundwater is a critical resource for agricultural production, ecosystems, drinking water and industry, yet groundwater depletion is accelerating, especially in a number of agriculturally important regions. Assessing the stress of groundwater resources is crucial for science-based policy and management, yet water stress assessments have often neglected groundwater and used single data sources, which may underestimate the uncertainty of the assessment. We consistently analyze and interpret groundwater stress across whole nations using multiple data sources for the first time. We focus on two nations with the highest national groundwater abstraction rates in the world, the United States and India, and use the recently developed groundwater footprint and multiple datasets of groundwater recharge and withdrawal derived from hydrologic models and data synthesis. A minority of aquifers, mostly with known groundwater depletion, show groundwater stress regardless of the input dataset. The majority of aquifers are not stressed with any input data while less than a third are stressed for some input data. In both countries groundwater stress affects agriculturally important regions. In the United States, groundwater stress impacts a lower proportion of the national area and population, and is focused in regions with lower population and water well density compared to India. Importantly, the results indicate that the uncertainty is generally greater between datasets than within datasets and that much of the uncertainty is due to recharge estimates. Assessment of groundwater stress consistently across a nation and assessment of uncertainty using multiple datasets are critical for the development of a science-based rationale for policy and management, especially with regard to where and to what extent to focus limited research and management resources. (letter)

Hanford groundwater scenario studies

International Nuclear Information System (INIS)

Arnett, R.C.; Gephart, R.E.; Deju, R.A.; Cole, C.R.; Ahlstrom, S.W.

1977-05-01

This report documents the results of two Hanford groundwater scenario studies. The first study examines the hydrologic impact of increased groundwater recharge resulting from agricultural development in the Cold Creek Valley located west of the Hanford Reservation. The second study involves recovering liquid radioactive waste which has leaked into the groundwater flow system from a hypothetical buried tank containing high-level radioactive waste. The predictive and control capacity of the onsite Hanford modeling technology is used to evaluate both scenarios. The results of the first study indicate that Cold Creek Valley irrigationis unlikely to cause significant changes in the water table underlying the high-level waste areas or in the movement of radionuclides already in the groundwater. The hypothetical tank leak study showed that an active response (in this case waste recovery) can be modeled and is a possible alternative to passive monitoring of radionuclide movement in the unlikely event that high-level waste is introduced into the groundwater

Groundwater age and lifetime expectancy modelling approach for site characterization and performance assessment of radwaste repository in clay formation

International Nuclear Information System (INIS)

Cornaton, F.; Perrochet, P.; Benabderrahmane, H.

2010-01-01

Document available in extended abstract form only. A deep geological repository of high level and long lived radwaste requires an understanding of the far field and near field groundwater flow and of the transport properties, at actual and future climatic conditions. Andra, French National radioactive waste management Agency, is developing since last 15 years an integrated multi-scale hydrogeological model of whole Paris basin of 200000 km 2 of area (regional scale) to produce a regional flow field associated to groundwater behavior. It includes locally the Meuse/Haute Marne clay site of about 250 km 2 of area in the eastern part of the Paris basin that was chosen for the emplacement of a repository. The Callovo-Oxfordian host formation is a clay layer characterized by a very low permeability of the order 10 -14 m/s, a mean thickness of 130 m at about 500 m depth, and is embedded by calcareous aquifer formations (Dogger and Oxfordian). The hydrogeological conceptual model is based on stratigraphic and petro-physic modeling of the Paris basin and is accounting for the structural, geological, hydrogeological and geochemical data in an integrated way. This model represents 27 hydrogeological units at the scale of the Paris Basin, and it is refined at the scale of the sector to represent 27 different layers that range in age from the Trias to the Portlandian. The finite element flow and transport simulator Ground Water (GW) is used to solve for groundwater flow at steady-state in a 3 Million elements model, considering current climatic conditions. The model is calibrated against about 1250 hydraulic head measurements, and results in maximum absolute hydraulic head differences of 20 meters at the regional scale and 3 meters at the local scale. The calibrated reference model includes transmissive major faults as well as structures acting as barrier to flow. Groundwater age (the time elapsed since recharge) and lifetime expectancy (the time remaining prior to exit) are

Natural radionuclides in groundwaters

International Nuclear Information System (INIS)

Laul, J.C.

1992-01-01

The 234 U and 230 Th radionuclides are highly retarded by factors of 10 4 to 10 5 in basalt groundwater (Hanford) and briny groundwaters from Texas, and geothermal brine form the Salton Sea Geothermal Field (SSGF). In basalt groundwaters (low ionic strength), Ra is highly sorbed, while in brines (high ionic strength), Ra is soluble. This is probably because the sorption sites are saturated with Na + and Cl - ions, and RaCl 2 is soluble in brines. 210 Pb is soluble in SSGF brine, probably as a chloride complex. The 234 U/ 230 Th ratios in basalt groundwaters and brines from Texas and SSGF are nearly unity, indicating that U is in the +4 state, suggesting a reducing environment for these aquifers. (author) 19 refs.; 3 figs

Groundwater residence time and movement in the Maltese islands - A geochemical approach

Energy Technology Data Exchange (ETDEWEB)

Stuart, M.E., E-mail: mest@bgs.ac.uk [British Geological Survey, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Maurice, L. [British Geological Survey, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Heaton, T.H.E. [British Geological Survey, NERC Isotope Geoscience Laboratory, Keyworth, Nottinghamshire NG12 5GG (United Kingdom); Sapiano, M.; Micallef Sultana, M. [Malta Resources Authority, Marsa MRS 9065 (Malta); Gooddy, D.C.; Chilton, P.J. [British Geological Survey, Wallingford, Oxfordshire OX10 8BB (United Kingdom)

2010-05-15

The Maltese islands are composed of two limestone aquifers, the Upper and Lower Coralline Limestone separated by an aquitard, the 'Blue Clay'. The Lower Coralline Limestone is overlain in part by the poorly permeable Globigerina Limestone. The upper perched aquifers are discontinuous and have very limited saturated thickness and a short water level response time to rainfall. Frequent detections of coliforms suggest a rapid route to groundwater. However, the unsaturated zone has a considerable thickness in places and the primary porosity of the Upper Coralline Limestone is high, so there is likely to be older recharge by slow matrix flow as well as rapid recharge from fractures. Measurement of SF{sub 6} from a pumping station in a deep part of one of the perched aquifers indicated a mean saturated zone age of about 15 a. The Main Sea Level aquifers (MSL) on both Malta and Gozo have a large unsaturated thickness as water levels are close to sea level. On Malta, parts of the aquifer are capped by the perched aquifers and more extensively by the Globigerina Limestone. The limited detection of coliform bacteria suggests only some rapid recharge from the surface via fractures or karst features. Transmissivity is low and {sup 3}H and CFC/SF{sub 6} data indicate that saturated zone travel times are in the range 15-40 a. On Gozo the aquifer is similar but is more-extensively capped by impermeable Blue Clay. CFC data show the saturated zone travel time is from 25 a to possibly more than 60 a. Groundwater age is clearly related to the extent of low-permeability cover. The {delta}{sup 13}C signature of groundwater is related to the geochemical processes which occur along the flowpath and is consistent with residence time ages in the sequence; perched aquifers < Malta MSL < Gozo MSL. The {sup 18}O and {sup 2}H enriched isotopic signature of post 1983 desalinated water can be seen in more-modern groundwater, particularly the urbanized areas of the perched and Malta MSL

Pleistocene paleo-groundwater as a pristine fresh water resource in southern Germany – evidence from stable and radiogenic isotopes

International Nuclear Information System (INIS)

Geldern, Robert van; Baier, Alfons; Subert, Hannah L.; Kowol, Sigrid; Balk, Laura; Barth, Johannes A.C.

2014-01-01

Shallow groundwater aquifers are often influenced by anthropogenic contaminants or increased nutrient levels. In contrast, deeper aquifers hold potentially pristine paleo-waters that are not influenced by modern recharge. They thus represent important water resources, but their recharge history is often unknown. In this study groundwater from two aquifers in southern Germany were analyzed for their hydrogen and oxygen stable isotope compositions. One sampling campaign targeted the upper aquifer that is actively recharged by modern precipitation, whereas the second campaign sampled the confined, deep Benkersandstein aquifer. The groundwater samples from both aquifers were compared to the local meteoric water line to investigate sources and conditions of groundwater recharge. In addition, the deep groundwater was dated by tritium and radiocarbon analyses. Stable and radiogenic isotope data indicate that the deep-aquifer groundwater was not part of the hydrological water cycle in the recent human history. The results show that the groundwater is older than ∼20,000 years and most likely originates from isotopically depleted melt waters of the Pleistocene ice age. Today, the use of this aquifer is strictly regulated to preserve the pristine water. Clear identification of such non-renewable paleo-waters by means of isotope geochemistry will help local water authorities to enact and justify measures for conservation of these valuable resources for future generations in the context of a sustainable water management. - Highlights: • Groundwater from deep aquifer identified as paleo-water with age over 20,000 years. • Low stable isotope values indicate recharge during Pleistocene. • Shallow aquifer mirrors stable isotope signature of average modern precipitation. • Identification of non-renewable paleo-waters enhance sustainable water management. • Strict protection measures of authorities justified by isotope geochemistry

Pleistocene paleo-groundwater as a pristine fresh water resource in southern Germany – evidence from stable and radiogenic isotopes

Energy Technology Data Exchange (ETDEWEB)

Geldern, Robert van, E-mail: robert.van.geldern@fau.de [Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Department of Geography and Geosciences, GeoZentrum Nordbayern, Schlossgarten 5, 91054 Erlangen (Germany); Baier, Alfons; Subert, Hannah L. [Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Department of Geography and Geosciences, GeoZentrum Nordbayern, Schlossgarten 5, 91054 Erlangen (Germany); Kowol, Sigrid [Erlanger Stadtwerke AG, Äußere Brucker Str. 33, 91052 Erlangen (Germany); Balk, Laura; Barth, Johannes A.C. [Friedrich-Alexander-University Erlangen-Nuremberg (FAU), Department of Geography and Geosciences, GeoZentrum Nordbayern, Schlossgarten 5, 91054 Erlangen (Germany)

2014-10-15

Shallow groundwater aquifers are often influenced by anthropogenic contaminants or increased nutrient levels. In contrast, deeper aquifers hold potentially pristine paleo-waters that are not influenced by modern recharge. They thus represent important water resources, but their recharge history is often unknown. In this study groundwater from two aquifers in southern Germany were analyzed for their hydrogen and oxygen stable isotope compositions. One sampling campaign targeted the upper aquifer that is actively recharged by modern precipitation, whereas the second campaign sampled the confined, deep Benkersandstein aquifer. The groundwater samples from both aquifers were compared to the local meteoric water line to investigate sources and conditions of groundwater recharge. In addition, the deep groundwater was dated by tritium and radiocarbon analyses. Stable and radiogenic isotope data indicate that the deep-aquifer groundwater was not part of the hydrological water cycle in the recent human history. The results show that the groundwater is older than ∼20,000 years and most likely originates from isotopically depleted melt waters of the Pleistocene ice age. Today, the use of this aquifer is strictly regulated to preserve the pristine water. Clear identification of such non-renewable paleo-waters by means of isotope geochemistry will help local water authorities to enact and justify measures for conservation of these valuable resources for future generations in the context of a sustainable water management. - Highlights: • Groundwater from deep aquifer identified as paleo-water with age over 20,000 years. • Low stable isotope values indicate recharge during Pleistocene. • Shallow aquifer mirrors stable isotope signature of average modern precipitation. • Identification of non-renewable paleo-waters enhance sustainable water management. • Strict protection measures of authorities justified by isotope geochemistry.

A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells

Science.gov (United States)

Jurgens, Bryant; Böhlke, John Karl; Kauffman, Leon J.; Belitz, Kenneth; Esser, Bradley K.

2016-01-01

A partial exponential lumped parameter model (PEM) was derived to determine age distributions and nitrate trends in long-screened production wells. The PEM can simulate age distributions for wells screened over any finite interval of an aquifer that has an exponential distribution of age with depth. The PEM has 3 parameters – the ratio of saturated thickness to the top and bottom of the screen and mean age, but these can be reduced to 1 parameter (mean age) by using well construction information and estimates of the saturated thickness. The PEM was tested with data from 30 production wells in a heterogeneous alluvial fan aquifer in California, USA. Well construction data were used to guide parameterization of a PEM for each well and mean age was calibrated to measured environmental tracer data (3H, 3He, CFC-113, and 14C). Results were compared to age distributions generated for individual wells using advective particle tracking models (PTMs). Age distributions from PTMs were more complex than PEM distributions, but PEMs provided better fits to tracer data, partly because the PTMs did not simulate 14C accurately in wells that captured varying amounts of old groundwater recharged at lower rates prior to groundwater development and irrigation. Nitrate trends were simulated independently of the calibration process and the PEM provided good fits for at least 11 of 24 wells. This work shows that the PEM, and lumped parameter models (LPMs) in general, can often identify critical features of the age distributions in wells that are needed to explain observed tracer data and nonpoint source contaminant trends, even in systems where aquifer heterogeneity and water-use complicate distributions of age. While accurate PTMs are preferable for understanding and predicting aquifer-scale responses to water use and contaminant transport, LPMs can be sensitive to local conditions near individual wells that may be inaccurately represented or missing in an aquifer-scale flow model.

Dating of groundwater with tritium and 14C

International Nuclear Information System (INIS)

Muennich, K.O.; Roether, W.; Thilo, L.

1967-01-01

Shallow groundwater can be dated with some accuracy on the basis of its bomb tritium content if the unsaturated soil cover and the aquifer itself is sufficiently homogeneous. A few examples from the Rhine valley are presented. The decrease in tritium level from the water table to a few metres below is nearly two orders of magnitude. Agreement between the measured or estimated variation of bomb tritium in rain during the past decade and the tritium found in shallow groundwater can be obtained if one takes into account that (a) practically no summer rain reaches the water table, and (b) water is mixed by diffusion. Both effects can also be observed in the soil moisture of the unsaturated soil above the water table. Carbon-14 increase in groundwater due to bombs is delayed compared to tritium, the reasons being delay in the biological system and exchange with the carbonate in the soil. Nevertheless lysimeters show a marked increase of 14 C, which depends on the plant cover, being high in a plant-covered lysimeter and low in a bare one. A simple model is presented, which allows the evaluation of the influence of exchange on the 14 C age obtained. It turns out that the deviation from the true age depends on the ratio of the carbonate content in the aquifer material to the carbonate content of the water, on the specific contact surface or the grain size but not on the groundwater velocity. On the basis of this model the experimental finding that 14 C ages are usually in agreement with other age estimates despite the loss by exchange is plausible owing to the fact that only material of sufficiently coarse grain size can make up a reasonable aquifer. Assuming only exchange with a monomolecular surface layer of the carbonate grains one finds that the 14 C age is likely to differ by not more than a factor of two in the most unfavourable case. Under natural conditions (steady state of cosmic-ray-produced 14 C) the 14 C content of shallow groundwater is hardly influenced at

Flourescence Humic Substances in Arsenic Contaminated Groundwater of Bangladesh

Directory of Open Access Journals (Sweden)

SHAFI M. TAREQ

2012-06-01

Full Text Available In the past, only arsenic (As concentrations in groundwater of Bangladesh were considered as having direct effects on the epidemical degrees of different types of diseases including arsenicosis, but the results of the present investigation indicated that fluorescence humic substance (HS is also an important component of dissolved organic matter in groundwater of Bangladesh. Therefore, it is suspected that both fluorescent HS and As in groundwater may have effects on the biological toxicity. The evidence of presence of high fluorescent HS and As in groundwater of Faridpur supports the above synergistic effect. The spatial distribution of fluorescence HS and As in groundwater of Faridpur indicated that the variations may be related to local hydrogeological conditions.

Paleotemperatures derived from noble gases dissolved in groundwater and in relation to soil temperature

International Nuclear Information System (INIS)

Stute, M.; Sonntag, C.

1992-01-01

Measurements of He, Ne, Ar, Kr and Xe dissolved in groundwater at two sites (Bocholt, Germany, and the Great Hungarian Plain) were taken to prove the reliability of noble gas temperatures as indicators of paleotemperatures. Noble gas temperatures of groundwater of Holocene age were found to reflect the annual mean soil temperature in the recharge are with an accuracy close to the precision of measurement (1σ approx. ±0.5 deg. C). Noble gas temperature data demonstrate the influence of vegetation cover on the soil temperature in the infiltration area. Groundwater formed in forests at the Bocholt site shows noble gas temperatures that are 2.2 deg. C lower than the groundwater formed in fields or meadows. The temperature data obtained from groundwater of the Great Hungarian Plain for the last glaciation are ≥ 8.6 deg. C lower than data from recent groundwater for maximum glaciation (approx. 18,000 years ago) and 4.7 ± 1 deg. C lower for the preceding interstadial (approx. 28,000-35,000 years ago). These data permit independent reconstruction of paleoclimatic conditions. (author). 19 refs, 3 figs, 1 tab

A validation of the 3H/3He method for determining groundwater recharge

Science.gov (United States)

Solomon, D. K.; Schiff, S. L.; Poreda, R. J.; Clarke, W. B.

1993-09-01

Tritium and He isotopes have been measured at a site where groundwater flow is nearly vertical for a travel time of 100 years and where recharge rates are spatially variable. Because the mid-1960s 3H peak (arising from aboveground testing of thermonuclear devices) is well-defined, the vertical groundwater velocity is known with unusual accuracy at this site. Utilizing 3H and its stable daughter 3He to determine groundwater ages, we compute a recharge rate of 0.16 m/yr, which agrees to within about 5% of the value based on the depth of the 3H peak (measured both in 1986 and 1991) and two-dimensional modeling in an area of high recharge. Zero 3H/3He age occurs at a depth that is approximately equal to the average depth of the annual low water table, even though the capillary fringe extends to land surface during most of the year at the study site. In an area of low recharge (0.05 m/yr) where the 3H peak (and hence the vertical velocity) is also well-defined, the 3H/3He results could not be used to compute recharge because samples were not collected sufficiently far above the 3H peak; however, modeling indicates that the 3H/3He age gradient near the water table is an accurate measure of vertical velocities in the low-recharge area. Because 3H and 3He have different diffusion coefficients, and because the amount of mechanical mixing is different in the area of high recharge than in the low-recharge area, we have separated the dispersive effects of mechanical mixing from molecular diffusion. We estimate a longitudinal dispersivity of 0.07 m and effective diffusion coefficients for 3H (3HHO) and 3He of 2.4×10-5 and 1.3×10-4 m2/day, respectively. Although the 3H/3He age gradient is an excellent indicator of vertical groundwater velocities above the mid-1960s 3H peak, dispersive mixing and diffusive loss of 3He perturb the age gradient near and below the 3H peak.

Combining groundwater quality analysis and a numerical flow simulation for spatially establishing utilization strategies for groundwater and surface water in the Pingtung Plain

Science.gov (United States)

Jang, Cheng-Shin; Chen, Ching-Fang; Liang, Ching-Ping; Chen, Jui-Sheng

2016-02-01

Overexploitation of groundwater is a common problem in the Pingtung Plain area of Taiwan, resulting in substantial drawdown of groundwater levels as well as the occurrence of severe seawater intrusion and land subsidence. Measures need to be taken to preserve these valuable groundwater resources. This study seeks to spatially determine the most suitable locations for the use of surface water on this plain instead of extracting groundwater for drinking, irrigation, and aquaculture purposes based on information obtained by combining groundwater quality analysis and a numerical flow simulation assuming the planning of manmade lakes and reservoirs to the increase of water supply. The multivariate indicator kriging method is first used to estimate occurrence probabilities, and to rank townships as suitable or unsuitable for groundwater utilization according to water quality standards for drinking, irrigation, and aquaculture. A numerical model of groundwater flow (MODFLOW) is adopted to quantify the recovery of groundwater levels in townships after model calibration when groundwater for drinking and agricultural demands has been replaced by surface water. Finally, townships with poor groundwater quality and significant increases in groundwater levels in the Pingtung Plain are prioritized for the groundwater conservation planning based on the combined assessment of groundwater quality and quantity. The results of this study indicate that the integration of groundwater quality analysis and the numerical flow simulation is capable of establishing sound strategies for joint groundwater and surface water use. Six southeastern townships are found to be suitable locations for replacing groundwater with surface water from manmade lakes or reservoirs to meet drinking, irrigation, and aquaculture demands.

Fluoride contamination in groundwater resources of Alleppey, southern India

Directory of Open Access Journals (Sweden)

Dhanya Raj

2017-01-01

Full Text Available Alleppey is one of the thickly populated coastal towns of the Kerala state in southern India. Groundwater is the main source of drinking water for the 240,991 people living in this region. The groundwater is being extracted from a multi-layer aquifer system of unconsolidated to semi-consolidated sedimentary formations, which range in age from Recent to Tertiary. The public water distribution system uses dug and tube wells. Though there were reports on fluoride contamination, this study reports for the first time excess fluoride and excess salinity in the drinking water of the region. The quality parameters, like Electrical Conductivity (EC ranges from 266 to 3900 μs/cm, the fluoride content ranges from 0.68 to 2.88 mg/L, and the chloride ranges between the 5.7 to 1253 mg/L. The main water types are Na-HCO3, Na-CO3 and Na-Cl. The aqueous concentrations of F− and CO32− show positive correlation whereas F− and Ca2+ show negative correlation. The source of fluoride in the groundwater could be from dissolution of fluorapatite, which is a common mineral in the Tertiary sediments of the area. Long residence time, sediment–groundwater interaction and facies changes (Ca-HCO3 to Na-HCO3 during groundwater flow regime are the major factors responsible for the high fluoride content in the groundwater of the area. High strontium content and high EC in some of the wells indicate saline water intrusion that could be due to the excess pumping from the deeper aquifers of the area. The water quality index computation has revealed that 62% of groundwater belongs to poor quality and is not suitable for domestic purposes as per BIS and WHO standards. Since the groundwater is the only source of drinking water in the area, proper treatment strategies and regulating the groundwater extraction are required as the quality deterioration poses serious threat to human health.

Groundwater environmental capacity and its evaluation index.

Science.gov (United States)

Xing, Li Ting; Wu, Qiang; Ye, Chun He; Ye, Nan

2010-10-01

To date, no unified and acknowledged definition or well-developed evaluation index system of groundwater environment capacity can be found in the academia at home or abroad. The article explores the meaning of water environment capacity, and analyzes the environmental effects caused by the exploitation of groundwater resources. This research defines groundwater environmental capacity as a critical value in terms of time and space, according to which the groundwater system responds to the external influences within certain goal constraint. On the basis of observing the principles of being scientific, dominant, measurable, and applicable, six level 1 evaluation indexes and 11 constraint factors are established. Taking Jinan spring region for a case study, this research will adopt groundwater level and spring flow as constraint factors, and the allowable groundwater yield as the critical value of groundwater environmental capacity, prove the dynamic changeability and its indicating function of groundwater environmental capacity through calculation, and finally point out the development trends of researches on groundwater environmental capacity.

Arsenic in Holocene aquifers of the Red River floodplain, Vietnam: Effects of sediment-water interactions, sediment burial age and groundwater residence time

Science.gov (United States)

Sø, Helle Ugilt; Postma, Dieke; , Mai Lan, Vi; Pham, Thi Kim Trang; Kazmierczak, Jolanta; Dao, Viet Nga; Pi, Kunfu; Koch, Christian Bender; Pham, Hung Viet; Jakobsen, Rasmus

2018-03-01

Water-sediment interactions were investigated in arsenic contaminated Holocene aquifers of the Red River floodplain, Vietnam, in order to elucidate the origin of the spatial variability in the groundwater arsenic concentration. The investigated aquifers are spread over an 8 × 13 km field area with sediments that varied in burial age from V) redox couple was found in disequilibrium with the other redox couples. Using the pe calculated from the CH4/CO2 redox couple we show that the groundwater has a reducing potential towards Fe-oxides ranging from ferrihydrite to poorly crystalline goethite, but not for well crystalline goethite or hematite. Hematite and poorly crystalline goethite were identified as the Fe-oxides present in the sediments. Reductive dissolution experiments identify two phases releasing Fe(II); one rapidly dissolving that also contains As and a second releasing Fe(II) more slowly but without As. The initial release of Fe and As occurs at a near constant As/Fe ratio that varied from site to site between 1.2 and 0.1 mmol As/mol Fe. Siderite (FeCO3) is the main sink for Fe(II), based on saturation calculations as well as the identification of siderite in the sediment. Most of the carbonate incorporated in siderite originates from the dissolution of sedimentary CaCO3. Over time the CaCO3 content of the sediments diminishes and FeCO3 appears instead. No specific secondary phases that incorporate arsenite could be identified. Alternatively, the amount of arsenic mobilized during the dissolution of reactive phases can be contained in the pool of adsorbed arsenite. Combining groundwater age with aquifer sediment age allows the calculation of the total number of pore volumes flushed through the aquifer. Comparison with groundwater chemistry shows the highest arsenic concentration to be present within the first 200 pore volumes flushed through the aquifer. These results agree with reactive transport modeling combining a kinetic description of reductive

Evaluation of groundwater droughts in Austria

Science.gov (United States)

Haas, Johannes Christoph; Birk, Steffen

2015-04-01

Droughts are abnormally dry periods that affect various aspects of human life on earth, ranging from negative impacts on agriculture or industry, to being the cause for conflict and loss of human life. The changing climate reinforces the importance of investigations into this phenomenon. Various methods to analyze and classify droughts have been developed. These include drought indices such as the Standard Precipitation Index SPI, the Palmer Drought Severity Index PDSI or the Crop Moisture Index CMI. These and other indices consider meteorological parameters and/or their effects on soil moisture. A depletion of soil moisture triggered by low precipitation and high evapotranspiration may also cause reduced groundwater recharge and thus decreasing groundwater levels and reduced groundwater flow to springs, streams, and wetlands. However, the existing indices were generally not designed to address such drought effects on groundwater. Thus, a Standardized Groundwater level Index has recently been proposed by Bloomfied and Marchant (2013). Yet, to our knowledge, this approach has only been applied to consolidated aquifers in the UK. This work analyzes time series of groundwater levels from various, mostly unconsolidated aquifers in Austria in order to characterize the effects of droughts on aquifers in different hydrogeologic and climatic settings as well as under different usage scenarios. In particular, comparisons are made between the water rich Alpine parts of Austria, and the dryer parts situated in the East. The time series of groundwater levels are compared to other data, such as meteorological time series and written weather records about generally accepted phenomena, such as the 2003 European drought and heat wave. Thus, valuable insight is gained into the propagation of meteorological droughts through the soil and the aquifer in different types of hydrogeologic and climatic settings, which provides a prerequisite for the assessment of the aquifers' drought

Comprehensive Analysis of Large Sets of Age-Related Physiological Indicators Reveals Rapid Aging around the Age of 55 Years.

Science.gov (United States)

Lixie, Erin; Edgeworth, Jameson; Shamir, Lior

2015-01-01

While many studies show a correlation between chronological age and physiological indicators, the nature of this correlation is not fully understood. To perform a comprehensive analysis of the correlation between chronological age and age-related physiological indicators. Physiological aging scores were deduced using principal component analysis from a large dataset of 1,227 variables measured in a cohort of 4,796 human subjects, and the correlation between the physiological aging scores and chronological age was assessed. Physiological age does not progress linearly or exponentially with chronological age: a more rapid physiological change is observed around the age of 55 years, followed by a mild decline until around the age of 70 years. These findings provide evidence that the progression of physiological age is not linear with that of chronological age, and that periods of mild change in physiological age are separated by periods of more rapid aging. © 2015 S. Karger AG, Basel.

Groundwater protection plan for the Environmental Restoration Disposal Facility

International Nuclear Information System (INIS)

Weekes, D.C.; Jaeger, G.K.; McMahon, W.J.; Ford, B.H.

1996-01-01

This document is the groundwater protection plan for the Environmental Restoration Disposal Facility (ERDF) Project. This plan is prepared based on the assumption that the ERDF will receive waste containing hazardous/dangerous constituents, radioactive constituents, and combinations of both. The purpose of this plan is to establish a groundwater monitoring program that (1) meets the intent of the applicable or relevant and appropriate requirements, (2) documents baseline groundwater conditions, (3) monitors those conditions for change, and (4) allows for modifications to groundwater sampling if required by the leachate management program. Groundwater samples indicate the occurrence of preexisting groundwater contamination in the uppermost unconfined aquifer below the ERDF Project site, as a result of past waste-water discharges in the 200 West Area. Therefore, it is necessary for the ERDF to establish baseline groundwater quality conditions and to monitor changes in the baseline over time. The groundwater monitoring program presented in this plan will provide the means to assess onsite and offsite impacts to the groundwater. In addition, a separate leachate management program will provide an indication of whether the liners are performing within design standards

Calculation of groundwater travel time

International Nuclear Information System (INIS)

Arnett, R.C.; Sagar, B.; Baca, R.G.

1984-12-01

Pre-waste-emplacement groundwater travel time is one indicator of the isolation capability of the geologic system surrounding a repository. Two distinct modeling approaches exist for prediction of groundwater flow paths and travel times from the repository location to the designated accessible environment boundary. These two approaches are: (1) the deterministic approach which calculates a single value prediction of groundwater travel time based on average values for input parameters and (2) the stochastic approach which yields a distribution of possible groundwater travel times as a function of the nature and magnitude of uncertainties in the model inputs. The purposes of this report are to (1) document the theoretical (i.e., mathematical) basis used to calculate groundwater pathlines and travel times in a basalt system, (2) outline limitations and ranges of applicability of the deterministic modeling approach, and (3) explain the motivation for the use of the stochastic modeling approach currently being used to predict groundwater pathlines and travel times for the Hanford Site. Example calculations of groundwater travel times are presented to highlight and compare the differences between the deterministic and stochastic modeling approaches. 28 refs

Hydrochemistry, origin and residence time of deep groundwater in the Yuseong area

International Nuclear Information System (INIS)

Koh, Yong Kwon; Kim, Geon Young; Bae, Dae Seok; Park, Kyung Woo

2005-01-01

As a part of the radioactive waste disposal research program in Korea, the geological, hydrogeological and hydrogeochemical investigations have been carried out in the Yuseong area (KAERI). The temperature or groundwater is measured up to 24 .deg. C and thermal gradient is obtained, to 0.26 .deg. C/100m. pH of groundwater at upper section shows about 7 and the pH of groundwater of 200m below surface reaches almost constant value as 9.9∼10.3. The redox potential of groundwater varied with depth and more negative values were recognized in deep groundwater. The redox potential of deep groundwater, main factor of U solubility, was measured up to -150 mV. These high pH and reduced conditions indicates that the maximum U concentration in groundwater would be limited by the equilibrium solubility of U minerals. The chemistry of shallow groundwater shows Ca-HCO 3 or Ca-Na-HCO 3 type, whereas the deep groundwater belongs to typical Na-HCO 3 type. The chemistry of groundwater below 250m from the surface is constant with depth, indicating that the extent of water-rock reaction is almost unique, which is controlled by the residence time of groundwater. The carbon isotope data (δ 13 C) of groundwater show the contribution of carbon from either that microbial oxidation of organic matter or carbon dioxide from plant respiration. The measurement and interpretation of C-14 indicate that the residence time of borehole deep groundwater ranges from about 2,000 to 6,000 yr BP. The high δ 34 S so4 value of groundwater indicate that the sulfate reduction might be occurred in the deep environment

Interpretation of environmental isotopic groundwater data. Arid and semi-arid zones

International Nuclear Information System (INIS)

Geyh, M.A.

1980-01-01

Various hydrodynamic aspects are discussed in order to show their implication for the hydrogeological interpretation of environmental isotope and hydrochemical groundwater data. Special attention is drawn to radiocarbon and tritium studies carried out in arid and semi-arid zones. An exponential model has been utilized to determine the mean residence time of the long-term water from springs in karst and crystalline regions. Hydrogeological parameters such as the porosity can be checked by this result. In addition, the exponential model offers the possibility of determining the initial 14 C content of spring water, which is sensitively dependent on the soil of the recharge area. A base-flow model has been introduced to interpret the 14 C and 3 H data of groundwater samples from older karst regions. Differences between pumped and drawn samples exist with respect to the groundwater budget. Owing to pumping, the old base flow is accelerated and becomes enriched in pumped groundwater in comparison to the short-term water. Radiocarbon ages of groundwater in alluvium may be dubious because of isotope exchange with the CO 2 in the root zone along the river bank. Under confined conditions 14 C groundwater ages are diminished if the hydraulic head of the confined aquifer is lower than that of the shallow one. This is due to the radiocarbon downwards transport by convection of shallow groundwater. The same effect occurs, though much faster, if the groundwater table is depleted by groundwater withdrawal. The decrease of the radiocarbon groundwater ages in time can be used to determine the hydraulic transmissibility coefficient of the aquitarde. According to the practical and theoretic results obtained the hydrodynamic aspects require at least the same attention for the interpretation of environmental isotope and hydrochemical data of groundwater as do hydrochemical and isotope fractionation processes. (author)

Groundwater quality impacts from the land application of treated municipal wastewater in a large karstic spring basin: Chemical and microbiological indicators

International Nuclear Information System (INIS)

Katz, Brian G.; Griffin, Dale W.; Davis, J. Hal

2009-01-01

Geochemical and microbiological techniques were used to assess water-quality impacts from the land application of treated municipal wastewater in the karstic Wakulla Springs basin in northern Florida. Nitrate-N concentrations have increased from about 0.2 to as high as 1.1 mg/L (milligrams per liter) during the past 30 years in Wakulla Springs, a regional discharge point for groundwater (mean flow about 11.3 m 3 /s) from the Upper Floridan aquifer (UFA). A major source of nitrate to the UFA is the approximately 64 million L/d (liters per day) of treated municipal wastewater applied at a 774 ha (hectare) sprayfield farming operation. About 260 chemical and microbiological indicators were analyzed in water samples from the sprayfield effluent reservoir, wells upgradient from the sprayfield, and from 21 downgradient wells and springs to assess the movement of contaminants into the UFA. Concentrations of nitrate-N, boron, chloride, were elevated in water samples from the sprayfield effluent reservoir and in monitoring wells at the sprayfield boundary. Mixing of sprayfield effluent water was indicated by a systematic decrease in concentrations of these constituents with distance downgradient from the sprayfield, with about a 10-fold dilution at Wakulla Springs, about 15 km (kilometers) downgradient from the sprayfield. Groundwater with elevated chloride and boron concentrations in wells downgradient from the sprayfield and in Wakulla Springs had similar nitrate isotopic signatures, whereas the nitrate isotopic composition of water from other sites was consistent with inorganic fertilizers or denitrification. The sprayfield operation was highly effective in removing most studied organic wastewater and pharmaceutical compounds and microbial indicators. Carbamazepine (an anti-convulsant drug) was the only pharmaceutical compound detected in groundwater from two sprayfield monitoring wells (1-2 ppt). One other detection of carbamazepine was found in a distant well water

Groundwater quality impacts from the land application of treated municipal wastewater in a large karstic spring basin: Chemical and microbiological indicators

Energy Technology Data Exchange (ETDEWEB)

Katz, Brian G. [U.S. Geological Survey, 2010 Levy Avenue, Tallahassee, Florida 32310 (United States)], E-mail: bkatz@usgs.gov; Griffin, Dale W.; Davis, J. Hal [U.S. Geological Survey, 2010 Levy Avenue, Tallahassee, Florida 32310 (United States)

2009-04-01

Geochemical and microbiological techniques were used to assess water-quality impacts from the land application of treated municipal wastewater in the karstic Wakulla Springs basin in northern Florida. Nitrate-N concentrations have increased from about 0.2 to as high as 1.1 mg/L (milligrams per liter) during the past 30 years in Wakulla Springs, a regional discharge point for groundwater (mean flow about 11.3 m{sup 3}/s) from the Upper Floridan aquifer (UFA). A major source of nitrate to the UFA is the approximately 64 million L/d (liters per day) of treated municipal wastewater applied at a 774 ha (hectare) sprayfield farming operation. About 260 chemical and microbiological indicators were analyzed in water samples from the sprayfield effluent reservoir, wells upgradient from the sprayfield, and from 21 downgradient wells and springs to assess the movement of contaminants into the UFA. Concentrations of nitrate-N, boron, chloride, were elevated in water samples from the sprayfield effluent reservoir and in monitoring wells at the sprayfield boundary. Mixing of sprayfield effluent water was indicated by a systematic decrease in concentrations of these constituents with distance downgradient from the sprayfield, with about a 10-fold dilution at Wakulla Springs, about 15 km (kilometers) downgradient from the sprayfield. Groundwater with elevated chloride and boron concentrations in wells downgradient from the sprayfield and in Wakulla Springs had similar nitrate isotopic signatures, whereas the nitrate isotopic composition of water from other sites was consistent with inorganic fertilizers or denitrification. The sprayfield operation was highly effective in removing most studied organic wastewater and pharmaceutical compounds and microbial indicators. Carbamazepine (an anti-convulsant drug) was the only pharmaceutical compound detected in groundwater from two sprayfield monitoring wells (1-2 ppt). One other detection of carbamazepine was found in a distant well water

Geochemical studies of groundwater systems of semiarid Yola area ...

African Journals Online (AJOL)

This was to determine the process controlling the water chemistry and to assess the ... for the deep groundwater and Na+-Cl- for the surface water bodies. ... Groundwater samples from the shallow groundwater indicate pH values (6.10 to 7.08) ...

Fluorine geochemistry in bedrock groundwater of South Korea

International Nuclear Information System (INIS)

Chae, Gi-Tak; Yun, Seong-Taek; Mayer, Bernhard; Kim, Kyoung-Ho; Kim, Seong-Yong; Kwon, Jang-Soon; Kim, Kangjoo; Koh, Yong-Kwon

2007-01-01

High fluoride concentrations (median = 4.4 mg/L) in deep bedrock groundwater of South Korea prevent the usage of it as a drinking water source. The hydrogeochemistry of deep thermal groundwaters (N = 377) in diverse bedrocks has been studied in order to evaluate the geologic and geochemical controls on fluoride concentrations in groundwater. The groundwater samples were clustered geologically, and the average and median concentrations of fluoride were compared by the Mann-Whitney U test. The order of median fluoride concentration with respect to geology is as follows: metamorphic rocks ≥ granitoids ≥ complex rock >> volcanic rocks ≥ sedimentary rocks. This result indicates that the geological source of fluoride in groundwater is related to the mineral composition of metamorphic rocks and granitoids. With respect to groundwater chemistry, the fluoride concentration was highest in Na-HCO 3 type groundwater and lowest in Ca-HCO 3 type groundwater. Ionic relationships also imply that the geochemical behavior of fluoride in groundwater is related to the geochemical process releasing Na and removing Ca ions. The thermodynamic relationship between the activities of Ca and F indicates that fluoride concentration is controlled by the equilibrium of fluorite (CaF 2 ). In other words, the upper limits of fluoride concentration are determined by the Ca ion; i.e., Ca concentrations play a crucial role in fluoride behavior in deep thermal groundwater. The result of this study suggests that the high fluoride in groundwater originates from geological sources and fluoride can be removed by fluorite precipitation when high Ca concentration is maintained. This provides a basis for a proper management plan to develop the deep thermal groundwater and for treatment of high fluoride groundwater frequently found in South Korea

Pathogens in Dairy Farming: Source Characterization and Groundwater Impacts

Science.gov (United States)

Atwill, E. R.; Watanabe, N.; Li, X.; Hou, L.; Harter, T.; Bergamaschi, B.

2007-12-01

Intense animal husbandry is of growing concern as a potential contamination source of enteric pathogens as well as antibiotics. To assess the public health risk from pathogens and their hydrologic pathways, we hypothesize that the animal farm is not a homogeneous diffuse source, but that pathogen loading to the soil and, therefore, to groundwater varies significantly between the various management units of a farm. A dairy farm, for example, may include an area with calf hutches, corrals for heifers of various ages, freestalls and exercise yards for milking cows, separate freestalls for dry cows, a hospital barn, a yard for collection of solid manure, a liquid manure storage lagoon, and fields receiving various amounts of liquid and solid manure. Pathogen shedding and, hence, therapeutic and preventive pharmaceutical treatments vary between these management units. We are implementing a field reconnaissance program to determine the occurrence of three different pathogens ( E. coli, Salmonella, Campylobacter) and one indicator organism ( Enterococcus) at the ground-surface and in shallow groundwater of seven different management units on each of two farms, and in each of four seasons (spring/dry season, summer/irrigation season, fall/dry season, winter/rainy season). Initial results indicate that significant differences exist in the occurrence of these pathogens between management units and between organisms. These differences are weakly reflected in their occurrence in groundwater, despite the similarity of the shallow geologic environment across these sites. Our results indicate the importance of differentiating sources within a dairy farm and the importance of understanding subsurface transport processes for these pathogens.

Isotope study of groundwater in Beishan area, Gansu province

International Nuclear Information System (INIS)

Guo Yonghai; Liu Shufen; Yang Tianxiao

2004-01-01

Using the isotope techniques, the groundwater origin, evolution and circulation in the potential site of China's high-level waste repository are studied. The results indicate that both shallow groundwaters are and deep groundwaters in the site area are of meteoric origin. The shallow groundwaters are mainly recharged by modern and local precipitation, and the deep groundwaters are originated from regional history period with lower temperature. Through the study we can also understand that the deep underground is a very low-permeability system where the groundwater flow-rates are very low. (author)

Obtaining appropriate interval estimates for age when multiple indicators are used

DEFF Research Database (Denmark)

Fieuws, Steffen; Willems, Guy; Larsen, Sara Tangmose

2016-01-01

When an estimate of age is needed, typically multiple indicators are present as found in skeletal or dental information. There exists a vast literature on approaches to estimate age from such multivariate data. Application of Bayes' rule has been proposed to overcome drawbacks of classical regres...... the need for interval estimation. To illustrate and evaluate the method, Köhler et al. (1995) third molar scores are used to estimate the age in a dataset of 3200 male subjects in the juvenile age range.......When an estimate of age is needed, typically multiple indicators are present as found in skeletal or dental information. There exists a vast literature on approaches to estimate age from such multivariate data. Application of Bayes' rule has been proposed to overcome drawbacks of classical...... regression models but becomes less trivial as soon as the number of indicators increases. Each of the age indicators can lead to a different point estimate ("the most plausible value for age") and a prediction interval ("the range of possible values"). The major challenge in the combination of multiple...

Use of radiogenic noble gases for dating groundwater

International Nuclear Information System (INIS)

Marine, I.W.

1981-01-01

The accumulation in groundwater of products from the radioactive decay of elements naturally found in rocks offers a potential for measuring the time that the groundwater has been in contact with the rock. This method of dating groundwater has an advantage over using decay products from atmospheric radionuclides in that the amount of decay product becomes greater with increasing age rather than less. Different decay products accumulate at different rates, however, and, thus, have a different potential usefulness in age determinations. The most useful decay product is helium, which is produced from uranium and thorium. The use of argon-40 produced from potassium is limited because it is abundant in meteoric water. Neon, xenon, and krypton can be used, but only with great difficulty because they are produced in extremely small quantities. In general, the potential for error increases when a long time is required to produce a small quantity of the dating nuclide. An example is given of the use of helium dissolved in groundwater to obtain an age of 840,000 y for water in crystalline metamorphic rock beneath the Savannah River Plant near Aiken, SC. Combined with other information, this water age can be used to measure the hydraulic conductivity of a large mass of rock (tens of kilometers in length). The hydraulic conductivity so calculated compares favorably with that obtained from hydraulic tests

Microbes Characteristics in Groundwater Flow System in Mountainous Area

Science.gov (United States)

Yamamoto, Chisato; Tsujimura, Maki; Kato, Kenji; Sakakibara, Koichi; Ogawa, Mahiro; Sugiyama, Ayumi; Nagaosa, Kazuyo

2017-04-01

We focus on a possibility of microbes as a tracer for groundwater flow investigation. Some previous papers showed that the total number of prokaryotes in groundwater has correlation with depth and geology (Parkes et al., 1994; Griebler et al., 2009; Kato et al., 2012). However, there are few studies investigating both microbe characteristics and groundwater flow system. Therefore, we investigated a relationship between the total number of prokaryotes and age of spring water and groundwater. Intensive field survey was conducted at four mountainous areas, namely Mt. Fuji (volcano), a headwater at Mt. Setohachi, a headwater at River Oi and a headwater at River Nagano underlain by volcanic lava at Mt. Fuji, granite at Mt. Setohachi and sedimentary rock at River Oi and River Nagano. We collected totally 40 spring water/ groundwater samples in these mountainous areas in October 2015, August, October and November 2016 and analyzed concentration of inorganic ions, the stable isotopes of oxygen - 18, deuterium, CFCs and SF6. Also, we counted prokaryotic cells under the epifluorescence microscopy after fixation and filteration. The total number of prokaryotes in the spring water/ groundwater ranged from 1.0×102 to 7.0×103cells mL-1 at the Mt. Fuji, 1.3×104 to 2.7×105cells mL-1 at Mt. Setohachi, 3.1×104cells mL-1 at River Oi and 1.8×105 to 3.2×106cells mL-1 at River Nagano. The SF6 age of the spring water/ groundwater ranged from 8 to 64 years at Mt. Fuji, 2 to 32.5 years at Mt. Setohachi, 2.5 years at River Oi and 15 to 16 years at River Nagano. The total number of prokaryotes showed a clear negative correlation with residence time of spring water/ groundwater in all regions. Especially the prokaryotes number increased in the order of 102 cells mL-1 with decreasing of residence time in approximately 10 years in the groundwater and spring water with the age less than 15 years.

Feasibility Study: Applicability of geochronologic methods involving radiocarbon and other nuclides to the groundwater hydrology of the Rustler Formation, southeastern New Mexico

International Nuclear Information System (INIS)

Lambert, S.J.

1987-12-01

Radiocarbon, tritium, and 36 Cl were measured in groundwaters from the dolomite aquifers of the Rustler Formation in the northern Delaware Basin of southeastern New Mexico to determine the feasibility of using these nuclides in dating the groundwater at and near the Waste Isolation Pilot Plant, a facility for geological disposal of Radioactive waste. No measurable 36 Cl was found in any of these groundwaters, which derive their dissolved chloride from Permian evaporites. Demonstrably uncontaminated groundwaters contained no significant amounts of tritium ( 13 C does not linearly correlate with bicarbonate, indicating no single source of contaminant radiocarbon. Values of PMC and δ 13 C for groundwaters were used to calculate apparent radiocarbon ages according to an interpretive model that accounts for water/rock interactions in carbonate aquifers. All but six pairs of values give significant negative ages (-1,000 to -7,000 years). This suggests that in contaminated samples the model over-adjusts (based on δ 13 C) for radiocarbon loss due to dilution and isotopic exchange with the rock. 52 refs., 10 figs., 6 tabs

Modeling the effects of atmospheric emissions on groundwater composition

International Nuclear Information System (INIS)

Brown, T.J.

1994-01-01

A composite model of atmospheric, unsaturated and groundwater transport is developed to evaluate the processes determining the distribution of atmospherically derived contaminants in groundwater systems and to test the sensitivity of simulated contaminant concentrations to input parameters and model linkages. One application is to screen specific atmospheric emissions for their potential in determining groundwater age. Temporal changes in atmospheric emissions could provide a recognizable pattern in the groundwater system. The model also provides a way for quantifying the significance of uncertainties in the tracer source term and transport parameters on the contaminant distribution in the groundwater system, an essential step in using the distribution of contaminants from local, point source atmospheric emissions to examine conceptual models of groundwater flow and transport

Major ion chemistry and quality assessment of groundwater in Haripur area

International Nuclear Information System (INIS)

Akram, W.; Tariq, J.A.; Ahmad, M.

2011-07-01

Study was conducted for investigating chemical composition of groundwater, identifying the compositional types of groundwater, delineating the processes controlling the groundwater chemistry and assessing the groundwater quality for drinking / irrigation uses. Groundwater samples collected from shallow (hand pumps, open well, motor pumps) and deep (tube wells) aquifers were analyzed for major cations (Na/sup +/,K/sup +, Ca/sup 2+/, Mg/sup 2+/) and anions (HCO/sub 3/, Cl/sup '/, SO/sub 4/). The data indicated that Ca/sub 2/ is the dominant cation in most of the samples followed by Mg/sup 2+/ whereas HCO/sub 3/ is the most abundant anion in all samples. Hydrochemistry provides a clear indication of active recharge of shallow and deep aquifers by modern meteoric water. Carbonate dissolution was found to be the prevailing process controlling the groundwater chemistry. Chemical quality was assessed for drinking purpose by comparing with WHO, Indian and national standards, and for irrigation purpose using empirical indices such as SAR and RSC. The results show that groundwater meets the norms of good quality drinking water and can be safely used for irrigation. (author)

Why is the Groundwater Level Rising? A Case Study Using HARTT to Simulate Groundwater Level Dynamic.

Science.gov (United States)

Yihdego, Yohannes; Danis, Cara; Paffard, Andrew

2017-12-01

  Groundwater from a shallow unconfined aquifer at a site in coastal New South Wales has been causing recent water logging issues. A trend of rising groundwater level has been anecdotally observed over the last 10 years. It was not clear whether the changes in groundwater levels were solely natural variations within the groundwater system or whether human interference was driving the level up. Time series topographic images revealed significant surrounding land use changes and human modification to the environment of the groundwater catchment. A statistical model utilising HARTT (multiple linear regression hydrograph analysis method) simulated the groundwater level dynamics at five key monitoring locations and successfully showed a trend of rising groundwater level. Utilising hydrogeological input from field investigations, the model successfully simulated the rise in the water table over time to the present day levels, whilst taking into consideration rainfall and land changes. The underlying geological/land conditions were found to be just as significant as the impact of climate variation. The correlation coefficient for the monitoring bores (MB), excluding MB4, show that the groundwater level fluctuation can be explained by the climate variable (rainfall) with the lag time between the atypical rainfall and groundwater level ranging from 4 to 7 months. The low R2 value for MB4 indicates that there are factors missing in the model which are primarily related to human interference. The elevated groundwater levels in the affected area are the result of long term cumulative land use changes, instigated by humans, which have directly resulted in detrimental changes to the groundwater aquifer properties.

Monitoring effects of river restoration on groundwater with radon

International Nuclear Information System (INIS)

Hoehn, Eduard

2007-01-01

The restoration of the perialpine river Toess in a floodplain of northern Switzerland (Linsental) included the removal of bank reinforcements and tracer studies in the river and in oberservation wells of the adjacent alluvial groundwater. The river water is continuously recharging the aquifer system and the groundwater is used extensively as drinking water. Radon activity concentrations of freshly infiltrated groundwater are interpreted as radon groundwater age between the river and a well. A first flood after the restoration operations resulted in a widening of the river bed and in a reduction of the flow distance to the wells. Sixteen days after a second flood, the results of radon measurements were compared with those from before the restoration. The radon age of the groundwater between the river and the wells decreased, probably as a result of the reduction of the flow distances. Concentrations of autochthonous and coliform bacteria increased after the restoration operation and even more one day after the first flood. Thus the findings on the bacteria corroborate the interpretation of the radon concentrations. The restoration has not yet reduced the quality of the groundwater, which is pumped for drinking water. The study is contributing to the solution of land-use conflicts between river restoration and the supply of drinking water from the alluvial groundwater. (orig.) [de

Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China.

Science.gov (United States)

Li, Junxia; Wang, Yanxin; Xie, Xianjun

2016-02-15

In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000-10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ(37)Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility. Copyright © 2015. Published by Elsevier B.V.

Control of groundwater in surface mining

Science.gov (United States)

Brawner, C. O.

1982-03-01

The presence of groundwater in surface mining operations often creates serious problems. The most important is generally a reduction in stability of the pit slopes. This is caused by pore water pressures and hydrodynamic shock due to blasting which reduce the shear strength and seepage pressures, water in tension cracks and increased unit weight which increase the shear stress. Groundwater and seepage also increase the cost of pit drainage, shipping, drilling and blasting, tyre wear and equipment maintenance. Surface erosion may also be increased and, in northern climates, ice flows on the slopes may occur. Procedures have been developed in the field of soil mechanics and engineering of dams to obtain quantitative data on pore water pressures and rock permeability, to evaluate the influence of pore water and seepage pressures on stability and to estimate the magnitude of ground-water flow. Based on field investigations, a design can be prepared for the control of groundwater in the slope and in the pit. Methods of control include the use of horizontal drains, blasted toe drains, construction of adits or drainage tunnels and pumping from wells in or outside of the pit. Recent research indicates that subsurface drainage can be augmented by applying a vacuum or by selective blasting. Instrumentation should be installed to monitor the groundwater changes created by drainage. Typical case histories are described that indicate the approach used to evaluate groundwater conditions.

Indications for breast imaging in women under age 35

International Nuclear Information System (INIS)

Harris, V.J.; Jackson, V.P.

1988-01-01

Many women under age 35 years undergo breast imaging, and the vast majority of studies are normal or compatible with benign disease. In our series of 649 patients aged 13 - 34, the only significant indicators were a palpable mass or infection. In the 383 patients with either of these indications, mammographic and/or US findings were normal in 53%, compatible with benign disease in 14%, and suggestive of malignancy in 33%. Biopsy performed in 80 of these women revealed breast cancer in five (6%). None of the 266 women with low-yield indications (pain, modularity, galactorrhea, fibrocystic disease, screening) had significant imaging findings or clinical or surgical evidence of breast cancer

Assessment and uncertainty analysis of groundwater risk.

Science.gov (United States)

Li, Fawen; Zhu, Jingzhao; Deng, Xiyuan; Zhao, Yong; Li, Shaofei

2018-01-01

Groundwater with relatively stable quantity and quality is commonly used by human being. However, as the over-mining of groundwater, problems such as groundwater funnel, land subsidence and salt water intrusion have emerged. In order to avoid further deterioration of hydrogeological problems in over-mining regions, it is necessary to conduct the assessment of groundwater risk. In this paper, risks of shallow and deep groundwater in the water intake area of the South-to-North Water Transfer Project in Tianjin, China, were evaluated. Firstly, two sets of four-level evaluation index system were constructed based on the different characteristics of shallow and deep groundwater. Secondly, based on the normalized factor values and the synthetic weights, the risk values of shallow and deep groundwater were calculated. Lastly, the uncertainty of groundwater risk assessment was analyzed by indicator kriging method. The results meet the decision maker's demand for risk information, and overcome previous risk assessment results expressed in the form of deterministic point estimations, which ignore the uncertainty of risk assessment. Copyright © 2017 Elsevier Inc. All rights reserved.

Addressing the Sustainability of Groundwater Extraction in California Using Hydrochronology

Science.gov (United States)

Moran, J. E.; Visser, A.; Singleton, M. J.; Esser, B. K.

2017-12-01

In urban and agricultural settings in California, intense pressure on water supplies has led to extensive managed aquifer recharge and extensive overdraft in these areas, respectively. The California Sustainable Groundwater Management Act (SGMA) includes criteria for pumping that maintains groundwater levels and basin storage, and avoids stream depletion and degradation of water quality. Most sustainability plans will likely use water level monitoring and water budget balancing based on integrated flow models as evidence of compliance. However, hydrochronology data are applicable to several of the criteria, and provide an independent method of addressing questions related to basin turnover time, recharge rate, surface water-groundwater interaction, and the age distribution at pumping wells. We have applied hydrochronology (mainly tritium-helium groundwater age dating and extrinsic tracers) in urban areas to delineate flowpaths of artificially recharged water, to identify stagnant zones bypassed by the engineered flow system, and to predict vulnerability of drinking water sources to contamination. In agricultural areas, we have applied multi-tracer hydrochronology to delineate groundwater stratigraphy, to identify paleowater, and to project future nitrate concentrations in long-screened wells. This presentation will describe examples in which groundwater dating and other tracer methods can be applied to directly address the SGMA criteria for sustainable groundwater pumping.

Groundwater Molybdenum from Emerging Industries in Taiwan.

Science.gov (United States)

Tsai, Kuo-Sheng; Chang, Yu-Min; Kao, Jimmy C M; Lin, Kae-Long

2016-01-01

This study determined the influence of emerging industries development on molybdenum (Mo) groundwater contamination. A total of 537 groundwater samples were collected for Mo determination, including 295 samples from potentially contaminated areas of 3 industrial parks in Taiwan and 242 samples from non-potentially contaminated areas during 2008-2014. Most of the high Mo samples are located downstream from a thin film transistor-liquid crystal display (TFT-LCD) panel factory. Mean groundwater Mo concentrations from potentially contaminated areas (0.0058 mg/L) were significantly higher (p industry and following wastewater batch treatment were 0.788 and 0.0326 mg/L, respectively. This indicates that wastewater containing Mo is a possible source of both groundwater and surface water contamination. Nine samples of groundwater exceed the World Health Organization's suggested drinking water guideline of 0.07 mg/L. A non-carcinogenic risk assessment for Mo in adults and children using the Mo concentration of 0.07 mg/L yielded risks of 0.546 and 0.215, respectively. These results indicate the importance of the development of a national drinking water quality standard for Mo in Taiwan to ensure safe groundwater for use. According to the human health risk calculation, the groundwater Mo standard is suggested as 0.07 mg/L. Reduction the discharge of Mo-contaminated wastewater from factories in the industrial parks is also the important task in the future.

Groundwater evolution of the granite area, Korea

International Nuclear Information System (INIS)

Kim, C.S.; Bae, D.S.; Koh, Y.K.; Kim, K.S.; Kim, G.Y.

2001-01-01

The geochemistry and environmental isotopes of groundwater in the Cretaceous granite of the Yeongcheon area has been investigated. The hydrochemistry of groundwater belongs to the Ca-HCO 3 type. The oxygen-18 and deuterium data are clustered along the meteoric water line, indicating that the groundwater is of meteoric water origin. Tritium data show that the groundwaters were mostly recharged before pre-thermonuclear period and have been mixed with younger surface water flowing rapidly along fractured zones. Based on the mass balance and reaction simulation approaches using both the hydrochemistry of groundwater and the secondary mineralogy of fracture-filling materials, the low-temperature hydrogeochemical evolution of groundwater in the area has been modeled. The results of geochemical simulation show that the concentrations of Ca, Na and HCO 3 and pH of waters increase progressively owing to the dissolution of reactive minerals in flow paths. The concentrations of Mg and K first increase with the dissolution of reactant minerals, but later decrease when montmorillonite and illitic material are precipitated respectively. The continuous adding of reactive minerals, i. e. the progressively larger degrees of water/rock interaction, causes the formation of secondary minerals with the following sequence: hematite > gibbsite > kaolinite > montmorillonite > illitic material > microcline. The results of reaction simulation agree well with the observed water chemistry and secondary mineralogy, indicating the successful applicability of this simulation technique to delineate the complex hydrogeochemistry of bedrock groundwaters. (author)

Isotope and chemical tracers in groundwater hydrology

International Nuclear Information System (INIS)

Kendall, C.; Stewart, M.K.; Morgenstern, U.; Trompetter, V.

1999-01-01

The course sessions cover: session 1, Fundamentals of stable and radioactive isotopes; session 2, Stable oxygen and hydrogen isotopes in hydrology: background, examples, sampling strategy; session 3, Catchment studies using oxygen and hydrogen isotopes: background - the hydrologic water balance, evapotranspiration - the lion's share, runoff generation - new water/old water fractions, groundwater recharge - the crumbs; session 4, Isotopes in catchment hydrology: survey of applications, future developments; session 5, Applications of tritium in hydrology: background and measurement, interpretation, examples; session 6, Case studies using mixing models: Hutt Valley groundwater system, an extended mixing model for simulating tracer transport in the unsaturated zone; session 7, Groundwater dating using CFC concentrations: background, sampling and measurement, use and applications; session 8, Groundwater dating with carbon-14: background, sampling and measurement, use and applications; session 9, NZ case studies: Tauranga warm springs, North Canterbury Plains groundwater; session 10, Stable carbon and nitrogen isotopes: background and examples, biological applications of C-N-S isotopes; session 11, New developments in isotope hydrology: gas isotopes, compound specific applications, age dating of sediments etc; session 12, NZ case studies: North Canterbury Plains groundwater (continued), Waimea Plains groundwater. (author). refs., figs

Isolation and identification of Trichoderma harzianum from groundwater: An effective biosorbent for defluoridation of groundwater.

Science.gov (United States)

Koshle, Shalini; Mahesh, S; Swamy, S Nanjunda

2016-01-01

The ability of non-viable form of Trichoderma harzianum, isolated from fluoride rich groundwater, was investigated as biosorbent for defluoridation of groundwater. Biosorption experiments were carried out at laboratory scale for removal of fluoride from groundwater. Significant effect of operational parameters on fluoride biosorption using Trichoderma harzianum as biosorbent was evaluated by varying operational parameters such as: initial fluoride concentration (2-8 mgl(-1)), biosorbent dose (0.4-1.6g/100ml), groundwater pH (6-10), temperature (30-50 degrees C) and biosorption time (30-120 min). The fluoride adsorption isotherms were modeled by Langmuir and Freundlich isotherms. Our result showed that fluoride biosorption, significantly increased with increase in groundwater pH, biosorbent dose, temperature and biosorption time, whereas increase in initial fluoride concentration reduced fluoride removal. The fluoride biosorption was rapid and maximum fluoride uptake was attained with 1.6g 100ml(-1) biosorbent within 60 min. Optimal pH 10 and temperature 50 degrees C gave maximum defluoridation efficiency. Freundlich isotherm fits well for defluoridation of groundwater using Trichoderma harzianum as biosorbent which indicated that biosorbent surface sites were heterogeneous in nature and fitted into heterogeneous site binding model.

Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China

Energy Technology Data Exchange (ETDEWEB)

Li, Junxia; Wang, Yanxin, E-mail: yx.wang@cug.edu.cn; Xie, Xianjun

2016-02-15

In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000–10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ{sup 37}Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility. - Highlights: • Natural high arsenic, fluoride and iodine groundwater co-occur with saline water. �

Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China

International Nuclear Information System (INIS)

Li, Junxia; Wang, Yanxin; Xie, Xianjun

2016-01-01

In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000–10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ"3"7Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility. - Highlights: • Natural high arsenic, fluoride and iodine groundwater co-occur with saline water. • Groundwater

Hydrogeochemical investigations of groundwater in Ziarat valley, Baluchistan

International Nuclear Information System (INIS)

Akram, W.; Ahmad, M.; Rafiq, M.

2010-03-01

Present study was undertaken in Ziarat Valley, Baluchistan to investigate recent trends of groundwater chemistry (geochemical facies, geochemical evolution) and assess the groundwater quality for drinking and irrigation purposes. For this purpose samples of groundwater (open wells, tube wells, karezes, springs) were periodically collected from different locations and analyzed for dissolved chemical constituents such as sodium, potassium, magnesium, calcium, carbonate, bicarbonate, chloride and sulphate. The data indicated that concentrations of sodium, potassium, calcium and magnesium vary from 5 to 113,0.3 to 3,18 to 62 and 27 to 85 mg/l respectively. Values of anions i. e. bicarbonate, chloride and sulphate lie in the range of 184 to 418, 14 to 77 and 8 to 318 mg/l respectively. Hydrogeochemical facies revealed that groundwater in the study area belongs to Mg-HCO/sub 3/ type at 72% surveyed locations. Dissolution and calcite precipitation were found to be the main processes controlling the groundwater chemistry. Chemical quality was assessed for drinking use by comparing with WHO, Indian and proposed national standards, and for irrigation use using empirical indices such as SAR and RSC. The results show that groundwater is quite suitable for irrigation and drinking purposes. (author)

BrainAGE score indicates accelerated brain aging in schizophrenia, but not bipolar disorder.

Science.gov (United States)

Nenadić, Igor; Dietzek, Maren; Langbein, Kerstin; Sauer, Heinrich; Gaser, Christian

2017-08-30

BrainAGE (brain age gap estimation) is a novel morphometric parameter providing a univariate score derived from multivariate voxel-wise analyses. It uses a machine learning approach and can be used to analyse deviation from physiological developmental or aging-related trajectories. Using structural MRI data and BrainAGE quantification of acceleration or deceleration of in individual aging, we analysed data from 45 schizophrenia patients, 22 bipolar I disorder patients (mostly with previous psychotic symptoms / episodes), and 70 healthy controls. We found significantly higher BrainAGE scores in schizophrenia, but not bipolar disorder patients. Our findings indicate significantly accelerated brain structural aging in schizophrenia. This suggests, that despite the conceptualisation of schizophrenia as a neurodevelopmental disorder, there might be an additional progressive pathogenic component. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Sorbitol-fermenting Bifidobacteria are indicators of very recent human faecal pollution in streams and groundwater habitats in urban tropical lowlands

Science.gov (United States)

2010-01-01

Sorbitol-fermenting Bifidobacteria (SFB) proved to be an excellent indicator of very recent human faecal pollution (hours to days) in the investigated tropical stream and groundwater habitats. SFB were recovered from human faeces and sources potentially contaminated with human excreta. SFB were undetectable in animal faeces and environmental samples not contaminated with human faeces. Microcosm studies demonstrated a rapid die-off rate in groundwater (T90 value 0.6 days) and stream water (T90 value 0.9–1.7 days). Discrimination sensitivity analysis, including E. coli, faecal coliforms, total coliforms and Clostridium perfringens spores, revealed high ability of SFB to distinguish differing levels of faecal pollution especially for streams although high background levels of interfering bacteria can complicate its recovery on the used medium. Due to its faster die-off, as compared to many waterborne pathogens, SFB cannot replace microbiological standard parameters for routine water quality monitoring but it is highly recommendable as a specific and complementary tool when human faecal pollution has to be localized or verified. Because of its exclusive faecal origin and human specificity it seems also worthwhile to include SFB in future risk evaluation studies at tropical water resources in order to evaluate under which situations risks of infection may be indicated. PMID:20375476

Electrical conductivity and pH of groundwater: important exploratory ...

African Journals Online (AJOL)

Electrical conductivity and pH of groundwater: important exploratory tools in groundwater surveys. ... Journal of Technology and Education in Nigeria ... An analysis of the spatial variation of these parameters indicates that the EC and pH values of groundwater allow us to make deductions not only on the changes in the ...

Predicting redox conditions in groundwater at a regional scale

Science.gov (United States)

Tesoriero, Anthony J.; Terziotti, Silvia; Abrams, Daniel B.

2015-01-01

Defining the oxic-suboxic interface is often critical for determining pathways for nitrate transport in groundwater and to streams at the local scale. Defining this interface on a regional scale is complicated by the spatial variability of reaction rates. The probability of oxic groundwater in the Chesapeake Bay watershed was predicted by relating dissolved O2 concentrations in groundwater samples to indicators of residence time and/or electron donor availability using logistic regression. Variables that describe surficial geology, position in the flow system, and soil drainage were important predictors of oxic water. The probability of encountering oxic groundwater at a 30 m depth and the depth to the bottom of the oxic layer were predicted for the Chesapeake Bay watershed. The influence of depth to the bottom of the oxic layer on stream nitrate concentrations and time lags (i.e., time period between land application of nitrogen and its effect on streams) are illustrated using model simulations for hypothetical basins. Regional maps of the probability of oxic groundwater should prove useful as indicators of groundwater susceptibility and stream susceptibility to contaminant sources derived from groundwater.

Geostatistical analysis of groundwater chemistry in Japan. Evaluation of the base case groundwater data set

Energy Technology Data Exchange (ETDEWEB)

Salter, P.F.; Apted, M.J. [Monitor Scientific LLC, Denver, CO (United States); Sasamoto, Hiroshi; Yui, Mikazu

1999-05-01

The groundwater chemistry is one of important geological environment for performance assessment of high level radioactive disposal system. This report describes the results of geostatistical analysis of groundwater chemistry in Japan. Over 15,000 separate groundwater analyses have been collected of deep Japanese groundwaters for the purpose of evaluating the range of geochemical conditions for geological radioactive waste repositories in Japan. The significance to issues such as radioelement solubility limits, sorption, corrosion of overpack, behavior of compacted clay buffers, and many other factors involved in safety assessment. It is important therefore, that a small, but representative set of groundwater types be identified so that defensible models and data for generic repository performance assessment can be established. Principal component analysis (PCA) is used to categorize representative deep groundwater types from this extensive data set. PCA is a multi-variate statistical analysis technique, similar to factor analysis or eigenvector analysis, designed to provide the best possible resolution of the variability within multi-variate data sets. PCA allows the graphical inspection of the most important similarities (clustering) and differences among samples, based on simultaneous consideration of all variables in the dataset, in a low dimensionality plot. It also allows the analyst to determine the reasons behind any pattern that is observed. In this study, PCA has been aided by hierarchical cluster analysis (HCA), in which statistical indices of similarity among multiple samples are used to distinguish distinct clusters of samples. HCA allows the natural, a priori, grouping of data into clusters showing similar attributes and is graphically represented in a dendrogram Pirouette is the multivariate statistical software package used to conduct the PCA and HCA for the Japanese groundwater dataset. An audit of the initial 15,000 sample dataset on the basis of

Isotope Hydrology Investigation of Zonguldak And Province Groundwater

International Nuclear Information System (INIS)

Erduran, B.; Toerk, K.; Oektue, G.

2002-01-01

The most important coal area of Turkey is situated in Zonguldak and province. The coal series occurred during Westfalien (Carboniferous) are lower-bounded by Visean aged karstic limestones and upper-bounded by Aptian-Barremian aged karstic limestones. The isotope hydrology, which consists one of the studies dealed with karst hydrogeology, was held to determine the groundwater relations between the karstic limestones adjacent to the coal layers located in the Zonguldak coal mine areas. Environmental isotope samples were collected in the basin during 1994 - 1995 period, from the surface and groundwater. Deuterium ( 2 H), Oxygen 18 ( 18 O) and Tritium ( 3 H) analysis were carried out on the samples. Recharge elevation, water origin and transit time of the groundwater system were determined with the evaluation of the analysis results. Waters encountered in the area are of marine origined rainfall, recharging at an elevation of 400-500 meters and consisting of shallow and deep circulation systems. Groundwater that intruding the coal mine galleries, have a short flow period and are recharged from recent precipitations

Assessment of groundwater management at Hanford

International Nuclear Information System (INIS)

Deju, R.A.

1975-01-01

A comprehensive review of the groundwater management and environmental monitoring programs at the Hanford reservation was initiated in 1973. A large number of recommendations made as a result of this review are summarized. The purpose of the Hanford Hydrology Program is to maintain a groundwater surveillance network to assess contamination of the natural water system. Potential groundwater contamination is primarily a function of waste management decisions. The review revealed that although the hydrology program would greatly benefit from additional improvements, it is adequate to predict levels of contaminants present in the groundwater system. Studies are presently underway to refine advanced mathematical models to use results of the hydrologic investigation in forecasting the response of the system to different long-term management decisions. No information was found which indicates that a hazard through the groundwater pathway presently exists as a result of waste operations at Hanford. (CH)

Groundwater residence times in Shenandoah National Park, Blue Ridge Mountains, Virginia, USA: A multi-tracer approach

Science.gov (United States)

Plummer, Niel; Busenberg, E.; Böhlke, J.K.; Nelms, D.L.; Michel, R.L.; Schlosser, P.

2001-01-01

Chemical and isotopic properties of water discharging from springs and wells in Shenandoah National Park (SNP), near the crest of the Blue Ridge Mountains, VA, USA were monitored to obtain information on groundwater residence times. Investigated time scales included seasonal (wet season, April, 1996; dry season, August–September, 1997), monthly (March through September, 1999) and hourly (30-min interval recording of specific conductance and temperature, March, 1999 through February, 2000). Multiple environmental tracers, including tritium/helium-3 (3H/3He), chlorofluorocarbons (CFCs), sulfur hexafluoride (SF6), sulfur-35 (35S), and stable isotopes (δ18O and δ2H) of water, were used to estimate the residence times of shallow groundwater discharging from 34 springs and 15 wells. The most reliable ages of water from springs appear to be based on SF6 and 3H/3He, with most ages in the range of 0–3 years. This range is consistent with apparent ages estimated from concentrations of CFCs; however, CFC-based ages have large uncertainties owing to the post-1995 leveling-off of the CFC atmospheric growth curves. Somewhat higher apparent ages are indicated by 35S (>1.5 years) and seasonal variation of δ18O (mean residence time of 5 years) for spring discharge. The higher ages indicated by the 35S and δ18O data reflect travel times through the unsaturated zone and, in the case of 35S, possible sorption and exchange of S with soils or biomass. In springs sampled in April, 1996, apparent ages derived from the 3H/3He data (median age of 0.2 years) are lower than those obtained from SF6 (median age of 4.3 years), and in contrast to median ages from 3H/3He (0.3 years) and SF6 (0.7 years) obtained during the late summer dry season of 1997. Monthly samples from 1999 at four springs in SNP had SF6apparent ages of only 1.2 to 2.5±0.8 years, and were consistent with the 1997 SF6 data. Water from springs has low excess air (0–1 cm3 kg−1) and N2–Ar temperatures that vary

Predicting geogenic arsenic contamination in shallow groundwater of south Louisiana, United States.

Science.gov (United States)

Yang, Ningfang; Winkel, Lenny H E; Johannesson, Karen H

2014-05-20

Groundwater contaminated with arsenic (As) threatens the health of more than 140 million people worldwide. Previous studies indicate that geology and sedimentary depositional environments are important factors controlling groundwater As contamination. The Mississippi River delta has broadly similar geology and sedimentary depositional environments to the large deltas in South and Southeast Asia, which are severely affected by geogenic As contamination and therefore may also be vulnerable to groundwater As contamination. In this study, logistic regression is used to develop a probability model based on surface hydrology, soil properties, geology, and sedimentary depositional environments. The model is calibrated using 3286 aggregated and binary-coded groundwater As concentration measurements from Bangladesh and verified using 78 As measurements from south Louisiana. The model's predictions are in good agreement with the known spatial distribution of groundwater As contamination of Bangladesh, and the predictions also indicate high risk of As contamination in shallow groundwater from Holocene sediments of south Louisiana. Furthermore, the model correctly predicted 79% of the existing shallow groundwater As measurements in the study region, indicating good performance of the model in predicting groundwater As contamination in shallow aquifers of south Louisiana.

Field demonstration of rapid turnaround, multilevel groundwater screening

International Nuclear Information System (INIS)

Tingle, A.R.; Baker, L.; Long, D.D.

1994-01-01

A combined technology approach to rapidly characterizing source area and downgradient groundwater associated with a past fuel spill has been field tested. The purpose of this investigation was to determine the presence and extent of fuel-related compounds or indications of their biodegradation in groundwater. The distance from the source area to be investigated was established by calculating the potential extent of a plume based only on groundwater flow velocities. To accomplish this objective, commercially available technologies were combined and used to rapidly assess the source area and downgradient groundwater associated with the fuel discharge. The source of contamination that was investigated overlies glacial sand and gravel outwash deposits. Historical data suggest that from 1955 to 1970 as many as 1 to 6 million pi of aviation gasoline (AVGAS) were god at the study area. Although the remedial investigation (RI) for this study area indicated fuel-related groundwater contamination at the source area, fuel-related contamination was not detected in downgradient monitoring wells. Rapid horizontal groundwater velocities and the 24-year time span from the last reported spill farther suggest that a plume of contaminated groundwater could extend several thousand feet downgradient. The lack of contamination downgradient from the source suggests two possibilities: (1) monitoring wells installed during the RI did not intersect the plume or (2) fuel-related compounds had naturally degraded

Groundwater vulnerability to pollution mapping of Ranchi district using GIS

Science.gov (United States)

Krishna, R.; Iqbal, J.; Gorai, A. K.; Pathak, G.; Tuluri, F.; Tchounwou, P. B.

2015-12-01

Groundwater pollution due to anthropogenic activities is one of the major environmental problems in urban and industrial areas. The present study demonstrates the integrated approach with GIS and DRASTIC model to derive a groundwater vulnerability to pollution map. The model considers the seven hydrogeological factors [Depth to water table ( D), net recharge ( R), aquifer media ( A), soil media ( S), topography or slope ( T), impact of vadose zone ( I) and hydraulic Conductivity( C)] for generating the groundwater vulnerability to pollution map. The model was applied for assessing the groundwater vulnerability to pollution in Ranchi district, Jharkhand, India. The model was validated by comparing the model output (vulnerability indices) with the observed nitrate concentrations in groundwater in the study area. The reason behind the selection of nitrate is that the major sources of nitrate in groundwater are anthropogenic in nature. Groundwater samples were collected from 30 wells/tube wells distributed in the study area. The samples were analyzed in the laboratory for measuring the nitrate concentrations in groundwater. A sensitivity analysis of the integrated model was performed to evaluate the influence of single parameters on groundwater vulnerability index. New weights were computed for each input parameters to understand the influence of individual hydrogeological factors in vulnerability indices in the study area. Aquifer vulnerability maps generated in this study can be used for environmental planning and groundwater management.

Groundwater vulnerability to pollution mapping of Ranchi district using GIS.

Science.gov (United States)

Krishna, R; Iqbal, J; Gorai, A K; Pathak, G; Tuluri, F; Tchounwou, P B

2015-12-01

Groundwater pollution due to anthropogenic activities is one of the major environmental problems in urban and industrial areas. The present study demonstrates the integrated approach with GIS and DRASTIC model to derive a groundwater vulnerability to pollution map. The model considers the seven hydrogeological factors [Depth to water table ( D ), net recharge ( R ), aquifer media ( A ), soil media ( S ), topography or slope ( T ), impact of vadose zone ( I ) and hydraulic Conductivity( C )] for generating the groundwater vulnerability to pollution map. The model was applied for assessing the groundwater vulnerability to pollution in Ranchi district, Jharkhand, India. The model was validated by comparing the model output (vulnerability indices) with the observed nitrate concentrations in groundwater in the study area. The reason behind the selection of nitrate is that the major sources of nitrate in groundwater are anthropogenic in nature. Groundwater samples were collected from 30 wells/tube wells distributed in the study area. The samples were analyzed in the laboratory for measuring the nitrate concentrations in groundwater. A sensitivity analysis of the integrated model was performed to evaluate the influence of single parameters on groundwater vulnerability index. New weights were computed for each input parameters to understand the influence of individual hydrogeological factors in vulnerability indices in the study area. Aquifer vulnerability maps generated in this study can be used for environmental planning and groundwater management.

Groundwater sampling with well-points

International Nuclear Information System (INIS)

Laubacher, R.C.; Bailey, W.M.

1992-01-01

This paper reports that BP Oil Company and Engineering-Science (ES) conducted a groundwater investigation at a BP Oil Distribution facility in the coastal plain of south central Alabama. The predominant lithologies include unconsolidated Quaternary-aged gravels, sands, silts and clay. Wellpoints were used to determine the vertical and horizontal extent of volatile hydrocarbons in the water table aquifer. To determine the vertical extent of contaminant migration, the hollow-stem augers were advanced approximately 10 feet into the aquifer near a suspected source. The drill stem and bit were removed very slowly to prevent sand heaving. The well-point was again driven ahead of the augers and four volumes (18 liters) of groundwater were purged. A sample was collected and the headspace vapor was analyzed as before. Groundwater from a total of seven borings was analyzed using these techniques. Permanent monitoring wells were installed at four boring locations which had volatile concentrations less than 1 part per million. Later groundwater sampling and laboratory analysis confirmed the wells had been installed near or beyond both the horizontal and vertical plume boundaries

Hydrogeologic framework and groundwater/surface-water interactions of the upper Yakima River Basin, Kittitas County, central Washington

Science.gov (United States)

Gendaszek, Andrew S.; Ely, D. Matthew; Hinkle, Stephen R.; Kahle, Sue C.; Welch, Wendy B.

2014-01-01

unconfined part of the aquifers in unconsolidated sediments indicate generalized groundwater movement toward the Yakima River and its tributaries and the outlet of the study area. Groundwater movement through fractures within the bedrock aquifers is complex and varies over spatial scales depending on the architecture of the fracture-flow system and its hydraulic properties. The complexity of the fracturedbedrock groundwater-flow system is supported by a wide range of groundwater ages determined from geochemical analyses of carbon-14, sulfur hexafluoride, and tritium in groundwater. These geochemical data also indicate that the shallow groundwater system is actively flushing with young, isotopically heavy groundwater, but isotopicallylight, Pleistocene-age groundwater with a geochemicallyevolved composition occurs at depth within the fracturedbedrock aquifers of upper Kittitas County. An eastward depletion of stable isotopes in groundwater is consistent with hydrologically separate subbasins. This suggests that groundwater that recharges in one subbasin is not generally available for withdrawal or discharge into surface-water features within other subbasins. Water budget components were calculated for 11 subbasins using a watershed model and varied based on the climate, land uses, and geology of the subbasin. Synoptic streamflow measurements made in August 2011 indicate that groundwater discharges into several tributaries of the Yakima River with several losses of streamflow measured where the streams exit bedrock uplands and flow over unconsolidated sediments. Profiles of stream temperature during late summer suggest cool groundwater inflow over discrete sections of streams. This groundwater/surfacewater connection is further supported by the stable-isotope composition of stream water, which reflects the local stableisotope composition of groundwater measured at some wells and springs. Collectively, these hydrogeologic, hydrologic, and geochemical data support a framework

Simulations of groundwater flow, transport, and age in Albuquerque, New Mexico, for a study of transport of anthropogenic and natural contaminants (TANC) to public-supply wells

Science.gov (United States)

Heywood, Charles E.

2013-01-01

Vulnerability to contamination from manmade and natural sources can be characterized by the groundwater-age distribution measured in a supply well and the associated implications for the source depths of the withdrawn water. Coupled groundwater flow and transport models were developed to simulate the transport of the geochemical age-tracers carbon-14, tritium, and three chlorofluorocarbon species to public-supply wells in Albuquerque, New Mexico. A separate, regional-scale simulation of transport of carbon-14 that used the flow-field computed by a previously documented regional groundwater flow model was calibrated and used to specify the initial concentrations of carbon-14 in the local-scale transport model. Observations of the concentrations of each of the five chemical species, in addition to water-level observations and measurements of intra-borehole flow within a public-supply well, were used to calibrate parameters of the local-scale groundwater flow and transport models. The calibrated groundwater flow model simulates the mixing of “young” groundwater, which entered the groundwater flow system after 1950 as recharge at the water table, with older resident groundwater that is more likely associated with natural contaminants. Complexity of the aquifer system in the zone of transport between the water table and public-supply well screens was simulated with a geostatistically generated stratigraphic realization based upon observed lithologic transitions at borehole control locations. Because effective porosity was simulated as spatially uniform, the simulated age tracers are more efficiently transported through the portions of the simulated aquifer with relatively higher simulated hydraulic conductivity. Non-pumping groundwater wells with long screens that connect aquifer intervals having different hydraulic heads can provide alternate pathways for contaminant transport that are faster than the advective transport through the aquifer material. Simulation of

Estimating Natural Recharge in a Desert Environment Facing Increasing Ground-Water Demands

Science.gov (United States)

Nishikawa, T.; Izbicki, J. A.; Hevesi, J. A.; Martin, P.

2004-12-01

Ground water historically has been the sole source of water supply for the community of Joshua Tree in the Joshua Tree ground-water subbasin of the Morongo ground-water basin in the southern Mojave Desert. Joshua Basin Water District (JBWD) supplies water to the community from the underlying Joshua Tree ground-water subbasin, and ground-water withdrawals averaging about 960 acre-ft/yr have resulted in as much as 35 ft of drawdown. As growth continues in the desert, ground-water resources may need to be supplemented using imported water. To help meet future demands, JBWD plans to construct production wells in the adjacent Copper Mountain ground-water subbasin. To manage the ground-water resources and to identify future mitigating measures, a thorough understanding of the ground-water system is needed. To this end, field and numerical techniques were applied to determine the distribution and quantity of natural recharge. Field techniques included the installation of instrumented boreholes in selected washes and at a nearby control site. Numerical techniques included the use of a distributed-parameter watershed model and a ground-water flow model. The results from the field techniques indicated that as much as 70 acre-ft/yr of water infiltrated downward through the two principal washes during the study period (2001-3). The results from the watershed model indicated that the average annual recharge in the ground-water subbasins is about 160 acre-ft/yr. The results from the calibrated ground-water flow model indicated that the average annual recharge for the same area is about 125 acre-ft/yr. Although the field and numerical techniques were applied to different scales (local vs. large), all indicate that natural recharge in the Joshua Tree area is very limited; therefore, careful management of the limited ground-water resources is needed. Moreover, the calibrated model can now be used to estimate the effects of different water-management strategies on the ground-water

Integration of ground-water and vadose-zone geochemistry to investigate hydrochemical evolution

International Nuclear Information System (INIS)

Fisher, R.S.; Mullican, W.F.

1990-01-01

This paper summarizes the results of an extensive groundwater-sampling program conducted in the Hueco Bolson and Diablo Plateau area of West Texas. The origin, hydrochemical evolution, and age of groundwater in arid lands of Trans-Pecos Texas were investigated by combining mineralogic analyses of soils and aquifer matrix, chemical analyses of readily soluble materials in soils and water extracted from the thick, unsaturated zone, and chemical and isotopic analyses of groundwater from three principal aquifers, the Diablo Plateau, Hueco Bolson, and Rio Grande alluvial aquifers. Repeated groundwater sampling over a 3-year period and quarterly sampling of selected wells revealed no significant short-term chemical or isotopic variability. Groundwater ages range from recent to nearly 28,000 years; the distribution of ages reflects relative permeability (transmissivity) of the aquifers. Most groundwaters evolve from calcium-bicarbonate to sodium-sulfate types because of carbonate and sulfate mineral dissolution coupled with exchange of aqueous calcium and magnesium for sodium on clay minerals. Water in the Rio Grande alluvial aquifer evolved to a sodium-chloride type as a result of extensive evapotranspiration on irrigated fields. The appendices list detailed results of field measurements of temperature, pH, Eh, dissolved oxygen, and major ion concentrations

Impact of excessive groundwater pumping on rejuvenation processes in the Bandung basin (Indonesia) as determined by hydrogeochemistry and modeling

Science.gov (United States)

Taufiq, Ahmad; Hosono, Takahiro; Ide, Kiyoshi; Kagabu, Makoto; Iskandar, Irwan; Effendi, Agus J.; Hutasoit, Lambok M.; Shimada, Jun

2017-12-01

In the Bandung basin, Indonesia, excessive groundwater pumping caused by rapid increases in industrialization and population growth has caused subsurface environmental problems, such as excessive groundwater drawdown and land subsidence. In this study, multiple hydrogeochemical techniques and numerical modeling have been applied to evaluate the recharge processes and groundwater age (rejuvenation). Although all the groundwater in the Bandung basin is recharged at the same elevation at the periphery of the basin, the water type and residence time of the shallow and deep groundwater could be clearly differentiated. However, there was significant groundwater drawdown in all the depression areas and there is evidence of groundwater mixing between the shallow and deep groundwater. The groundwater mixing was traced from the high dichlorodifluoromethane (CFC-12) concentrations in some deep groundwater samples and by estimating the rejuvenation ratio (R) in some representative observation wells. The magnitude of CFC-12 concentration, as an indicator of young groundwater, showed a good correlation with R, determined using 14C activity in samples taken between 2008 and 2012. These correlations were confirmed with the estimation of vertical downward flux from shallower to deeper aquifers using numerical modeling. Furthermore, the change in vertical flux is affected by the change in groundwater pumping. Since the 1970s, the vertical flux increased significantly and reached approximately 15% of the total pumping amount during the 2000s, as it compensated the groundwater pumping. This study clearly revealed the processes of groundwater impact caused by excessive groundwater pumping using a combination of hydrogeochemical methods and modeling.

An isotope-aided study on the interaction of surface water and groundwater

International Nuclear Information System (INIS)

Ahn, Jong Sung; Kim, Jong Hoon; Yun, Si Tae; Jeong, Chan Ho; Kim, Kae Nam

1987-12-01

The interaction between surface water and groundwater was studied by isotope-aided techniques in the vicinity of the KAERI area. The understanding of surface water and groundwater flow systems and the analysis of geomaterials which provide the pathway of groundwater is important for the hydrogeological safety assessment of the radioactive waste disposal. The results of the analyses of environmental isotopes have shown that the shallow groundwater in this area was originated from the meteoric water which is infiltrated rapidly into the subsurface materials. The higher content of the environmental isotopes in some groundwater samples indicate that this anomalous values is attributed to impermeable, fine-grained materials. Also, the results of hydrochemical analyses of water samples indicate that shallow groundwater and precipitation are well mixed. (Author)

The Analysis of Sulfur-35 as a Young Groundwater Tracer at E-Tunnel, Rainier Mesa, Nevada National Security Site

Energy Technology Data Exchange (ETDEWEB)

Deinhart, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bibby, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Roberts, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tompson, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Esser, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-08-09

Analysis of the relatively short-lived radionuclide sulfur-35 (t_1/2 = 87 days) provides useful insight into groundwater discharge from E-Tunnel at the Nevada National Security Site (NNSS). Discharge rates at E-Tunnel vary with precipitation, potentially as the result of short or fast flowpaths between recharge and discharge. The presence of sulfur-35 in groundwater would indicate a significant component of young (< 2-year-old) groundwater. We collected two large volume (20 L) samples of discharge water in November 2016. The samples were sent to Lawrence Livermore National Laboratory (LLNL), where they were processed and analyzed by Liquid Scintillation Counting (LSC). Sulfur-35 was not detected in either the sample or field duplicate, a finding consistent with E-Tunnel discharge containing no significant component of groundwater with age less than six months.

Study on risk indicator for appropriate plant maintenance considering aging effect

International Nuclear Information System (INIS)

Mano, Akihiro; Yamaguchi, Akira; Takata, Takashi

2014-01-01

Since, nuclear power plants run for a long term and plant component may deteriorate due to aging, plant safety must be maintained through maintenance activities of components. The maintenance will become more important as the number of aged plant increases. In the planning of maintenance, one must select appropriate components and interval. In general, Fussell-Vesely importance (FV) and Risk Achievement Worth (RAW) are used as a risk indicator for the maintenance. A priority order of each component can be evaluated using those risk indicators at a certain condition. However, the influence of aging (time history) on the order cannot be estimated directly. In the paper, a change of conditional core damage probability (ΔCCDP) and a change of conditional containment failure probability (ΔCCFP) are proposed as additional indicators in which the aging effect is evaluated directly so as to determine the priority order. A simplified level one probabilistic risk assessment (PRA) has been carried out in order to investigate the change of the risk indicators by considering the change of a component failure probability due to aging. In the analyses, three conditions are assumed; base (original) state, aging state and further aging state without maintenance activities. It is demonstrated that the proposed indicator (ΔCCDP and ΔCCFP) reveals the aging effect of each component, while the change of the FV and RAW represent unrealistic behavior through the states. As a result, it is found that the ΔCCDP and ΔCCFP are superior to the others in terms of the ability to evaluate components appropriately in deteriorated (aging) states and take account of differences of deterioration behavior. It is also found that the priority order of the multiple-components maintenance at the same time can also be evaluated using the ΔCCDP and ΔCCFP. Additionally, a risk informed decision making based on the risk acceptance criteria can be discussed for the maintenance procedure using the

One-year measurements of chloroethenes in tree cores and groundwater at the SAP Mimoň Site, Northern Bohemia.

Science.gov (United States)

Wittlingerova, Z; Machackova, J; Petruzelkova, A; Trapp, S; Vlk, K; Zima, J

2013-02-01

Chlorinated ethenes (CE) are among the most frequent contaminants of soil and groundwater in the Czech Republic. Because conventional methods of subsurface contamination investigation are costly and technically complicated, attention is directed on alternative and innovative field sampling methods. One promising method is sampling of tree cores (plugs of woody tissue extracted from a host tree). Volatile organic compounds can enter into the trunks and other tissues of trees through their root systems. An analysis of the tree core can thus serve as an indicator of the subsurface contamination. Four areas of interest were chosen at the experimental site with CE groundwater contamination and observed fluctuations in groundwater concentrations. CE concentrations in groundwater and tree cores were observed for a 1-year period. The aim was to determine how the CE concentrations in obtained tree core samples correlate with the level of contamination of groundwater. Other factors which can affect the transfer of contaminants from groundwater to wood were also monitored and evaluated (e.g., tree species and age, level of groundwater table, river flow in the nearby Ploučnice River, seasonal effects, and the effect of the remediation technology operation). Factors that may affect the concentration of CE in wood were identified. The groundwater table level, tree species, and the intensity of transpiration appeared to be the main factors within the framework of the experiment. Obtained values documented that the results of tree core analyses can be used to indicate the presence of CE in the subsurface. The results may also be helpful to identify the best sampling period for tree coring and to learn about the time it takes until tree core concentrations react to changes in groundwater conditions. Interval sampling of tree cores revealed possible preservation of the contaminant in the wood of trees.

40 CFR 265 interim status indicator-evaluation ground-water monitoring plan for the 216-B-63 trench

International Nuclear Information System (INIS)

Bjornstad, B.N.; Dudziak, S.

1989-03-01

This document outlines a ground-water monitoring plan for the 216-B-63 trench located in the northeast corner of the 200-East Area on the Hanford Site in southeastern Washington State. It has been determined that hazardous materials (corrosives) were disposed of to the trench during past operations. Installation of an interim-status ground-water monitoring system is required to determine whether hazardous chemicals are leaching to the ground water from beneath the trench. This document summarizes the existing data that are available from near the 216-B-63 trench and presents a plan to determine the extent of ground-water contamination, if any, derived from the trench. The plan calls for the installation of four new monitoring wells located near the west end of the trench. These wells will be used to monitor ground-water levels and water quality immediately adjacent to the trench. Two existing RCRA monitoring wells, which are located near the trench and hydraulically upgradient of it, will be used as background wells. 46 refs., 15 figs., 12 tabs

Preliminary assessment of water chemistry related to groundwater flooding in Wawarsing, New York, 2009-11

Science.gov (United States)

Brown, Craig J.; Eckhardt, David A.; Stumm, Frederick; Chu, Anthony

2012-01-01

Water-quality samples collected in an area prone to groundwater flooding in Wawarsing, New York, were analyzed and assessed to better understand the hydrologic system and to aid in the assessment of contributing water sources. Above average rainfall over the past decade, and the presence of a pressurized water tunnel that passes about 700 feet beneath Wawarsing, could both contribute to groundwater flooding. Water samples were collected from surface-water bodies, springs, and wells and analyzed for major and trace inorganic constituents, dissolved gases, age tracers, and stable isotopes. Distinct differences in chemistry exist between tunnel water and groundwater in unconsolidated deposits and in bedrock, and among groundwater samples collected from some bedrock wells during high head pressure and low head pressure of the Rondout-West Branch Tunnel. Samples from bedrock wells generally had relatively higher concentrations of sulfate (SO42-), strontium (Sr), barium (Ba), and lower concentrations of calcium (Ca) and bicarbonate (HCO3-), as compared to unconsolidated wells. Differences in stable-isotope ratios among oxygen-18 to oxygen-16 (δ18O), hydrogen-2 to hydrogen-1 (δ2H), sulfur-34 to sulfur-32(δ34S) of SO42-, Sr-87 to Sr-86 (87Sr/86Sr), and C-13 to C-12 (δ13C) of dissolved inorganic carbon (DIC) indicate a potential for distinguishing water in the Delaware-West Branch Tunnel from native groundwater. For example, 87Sr/86Sr ratios were more depleted in groundwater samples from most bedrock wells, as compared to samples from surface-water sources, springs, and wells screened in unconsolidated deposits in the study area. Age-tracer data provided useful information on pathways of the groundwater-flow system, but were limited by inherent problems with dissolved gases in bedrock wells. The sulfur hexafluoride (SF6) and (or) chlorofluorocarbons (CFCs) apparent recharge years of most water samples from wells screened in unconsolidated deposits and springs ranged

Modeling Effects of Groundwater Basin Closure, and Reversal of Closure, on Groundwater Quality

Science.gov (United States)

Pauloo, R.; Guo, Z.; Fogg, G. E.

2017-12-01

Population growth, the expansion of agriculture, and climate uncertainties have accelerated groundwater pumping and overdraft in aquifers worldwide. In many agricultural basins, a water budget may be stable or not in overdraft, yet disconnected ground and surface water bodies can contribute to the formation of a "closed" basin, where water principally exits the basin as evapotranspiration. Although decreasing water quality associated with increases in Total Dissolved Solids (TDS) have been documented in aquifers across the United States in the past half century, connections between water quality declines and significant changes in hydrologic budgets leading to closed basin formation remain poorly understood. Preliminary results from an analysis with a regional-scale mixing model of the Tulare Lake Basin in California indicate that groundwater salinization resulting from open to closed basin conversion can operate on a decades-to-century long time scale. The only way to reverse groundwater salinization caused by basin closure is to refill the basin and change the hydrologic budget sufficiently for natural groundwater discharge to resume. 3D flow and transport modeling, including the effects of heterogeneity based on a hydrostratigraphic facies model, is used to explore rates and time scales of groundwater salinization and its reversal under different water and land management scenarios. The modeling is also used to ascertain the extent to which local and regional heterogeneity need to be included in order to appropriately upscale the advection-dispersion equation in a basin scale groundwater quality management model. Results imply that persistent managed aquifer recharge may slow groundwater salinization, and complete reversal may be possible at sufficiently high water tables.

Inverse modeling and uncertainty analysis of potential groundwater recharge to the confined semi-fossil Ohangwena II Aquifer, Namibia

Science.gov (United States)

Wallner, Markus; Houben, Georg; Lohe, Christoph; Quinger, Martin; Himmelsbach, Thomas

2017-12-01

The identification of potential recharge areas and estimation of recharge rates to the confined semi-fossil Ohangwena II Aquifer (KOH-2) is crucial for its future sustainable use. The KOH-2 is located within the endorheic transboundary Cuvelai-Etosha-Basin (CEB), shared by Angola and Namibia. The main objective was the development of a strategy to tackle the problem of data scarcity, which is a well-known problem in semi-arid regions. In a first step, conceptual geological cross sections were created to illustrate the possible geological setting of the system. Furthermore, groundwater travel times were estimated by simple hydraulic calculations. A two-dimensional numerical groundwater model was set up to analyze flow patterns and potential recharge zones. The model was optimized against local observations of hydraulic heads and groundwater age. The sensitivity of the model against different boundary conditions and internal structures was tested. Parameter uncertainty and recharge rates were estimated. Results indicate that groundwater recharge to the KOH-2 mainly occurs from the Angolan Highlands in the northeastern part of the CEB. The sensitivity of the groundwater model to different internal structures is relatively small in comparison to changing boundary conditions in the form of influent or effluent streams. Uncertainty analysis underlined previous results, indicating groundwater recharge originating from the Angolan Highlands. The estimated recharge rates are less than 1% of mean yearly precipitation, which are reasonable for semi-arid regions.

CT MEASUREMENTS OF TWO CEREBROVENTRICULAR INDICES AND THEIR RELATION WITH AGE

Directory of Open Access Journals (Sweden)

Ambili Puthanveettil

2017-01-01

Full Text Available BACKGROUND Cerebroventricular Indices are the relative measurements of the size of lateral ventricle to that of brain. A normal study of these indices are necessary in order to understand any changes in size of the ventricles or other associated abnormalities of the brain. The study uses measurements from Computerised Tomography (CT which is uniformly calibrated, has reproducible data and is less expensive than MRI. MATERIALS AND METHODS CT scans of 186 apparently healthy normal individuals of age group 1 to 85 years were taken and the subjects were categorized into age intervals of 10 years; males and females taken separately. The linear measurements of lateral ventricle and brain were taken directly from the screen. The cerebrovascular indices were calculated. The mean values in each group were compared with age and sex, using appropriate statistical tests. RESULTS Mean value for Bifrontal index was 0.31±0.03 and that of Bicaudate index was 0.12±0.02. Both indices showed a positive correlation with age. The relative size of the lateral ventricle with the brain did not show any gender difference. CONCLUSION The study results coincide with previous similar studies. Both the indices showed positive correlation with age, of which the Bicaudate index was more sensitive.

Veterinary Antibiotics in Young Dutch Groundwater under Intensive Livestock Farming

Science.gov (United States)

Vliet, M. V.; Kivits, T.; Broers, H. P.; Beeltje, H.; Griffioen, J.

2016-12-01

Dutch groundwater is heavily affected by nutrient loads from agricultural origin. The use of antibiotics is also widespread in Dutch farming practice, 200.000 kg active substance over 1.839.000 ha of agricultural land. National measures were established to reduce the applications. Spreading of manure over farmlands is assumed to be the main pathway for the leaching of antibiotics to groundwater, but actual numbers are lacking. We studied the occurrence of veterinary antibiotics in groundwater in two areas with intensive livestock farming, sampling existing multi-level wells that were previously age dated using tritium-helium. Wells were selected based on the following criteria: the uppermost screen is situated just below the average groundwater level, which is not deeper than 3 meters, the well is in an agricultural field where rainwater infiltrates avoiding areas adjacent to ditches or streams, the groundwater quality is known for several years and the age of the extracted water is known to be young (antibiotics used in in intensive livestock farming were analyzed belonging to the following groups: tetracyclines, sulfonamides, diaminopyrimidines, β-lactams, macrolides, lincosamides, quinolones and in addition nitrofurans and chloramphenicol. The samples were analyzed for antibiotics by liquid chromatography/mass spectrometry preceded by solid phase extraction (Oasis HLB cartridge). Five out of 22 antibiotics were detected: sulfamethazine, sulfadiazine, sulfamethoxazole, lincomycin, chloramphenicol in concentration ranges of 0.2 to 18 ng/l. Sulfamethazine was most frequently found, and shows a continuous concentration-depth profile in 3 out of 4 multi-level wells. Sulfonamides were found in groundwater up to 20 m. depth and in water aged between 1 and 25 years old. The study shows that sulfonamides are omnipresent in groundwater up to 25 years old, which corresponds with the known history of the use of antibiotics in veterinary practice.

Environmental isotope and hydrochemical investigation of Bauru and Botucatu groundwaters, Parana basin, Brazil

International Nuclear Information System (INIS)

Kimmelmann, A.

1991-06-01

A combined hydrogeochemical and environmental isotope investigation is being carried out in the Bauru- and Botucatu groundwaters. Based on former isotope data, the 2 H/ 18 O-, 3 H-, 13 C-, 14 C- and 3 He/ 4 He-contents of representative groundwaters out from the Bauru- and Botucatu-aquifer are now investigated to reveal a possible interaction of the groundwater systems and to correlate 14 C-groundwater residence times with groundwater ages derived from other isotope methods. (author)

Atacama perchlorate as an agricultural contaminant in groundwater: Isotopic and chronologic evidence from Long Island, New York

Science.gov (United States)

Böhlke, J.K.; Hatzinger, P.B.; Sturchio, N.C.; Gu, B.; Abbene, I.; Mroczkowski, S.J.

2009-01-01

Perchlorate (ClO4-) is a common groundwater constituent with both synthetic and natural sources. A potentially important source of ClO4- is past agricultural application of ClO4--bearing natural NO3- fertilizer imported from the Atacama Desert, Chile, but evidence for this hasbeenlargely circumstantial. Here we report ClO4- stable isotope data (??37Cl, ??18O, and ??17O), along with other supporting chemical and isotopic environmental tracer data, to document groundwater ClO4- contamination sources and history in parts of Long Island, New York. Sampled groundwaters were oxic and ClO4- apparently was not affected by biodegradation within the aquifers. Synthetic ClO4- was indicated by the isotopic method in groundwater near a fireworks disposal site at a former missile base. Atacama ClO4- was indicated in agricultural and urbanizing areas in groundwaters with apparent ages >20 years. In an agricultural area, ClO4- concentrations and ClO4-/NO3- ratios increased withgroundwaterage, possiblybecauseof decreasing application rates of Atacama NO3- fertilizers and/or decreasing ClO4- concentrations in Atacama NO 3- fertilizers in recent years. Because ClO 4-/NO3- ratios of Atacama NO 3- fertilizers imported in the past (???2 ?? 10-3 mol mol-1) were much higher than the ClO 4-/NO3- ratio of recommended drinking-water limits (7 ?? 10-5 mol mol-1 in New York), ClO4- could exceed drinkingwater limits even where NO3- does not, and where Atacama NO3- was only a minor source of N. Groundwater ClO4- with distinctive isotopic composition was a sensitive indicator of past Atacama NO3- fertilizer use on Long Island and may be common in other areas that received NO3- fertilizers from the late 19th century through the 20th century. ?? 2009 American Chemical Society.

Groundwater Quality Assessment for Waste Management Area U: First Determination

Energy Technology Data Exchange (ETDEWEB)

Hodges, Floyd N.; Chou, Charissa J.

2000-08-04

As a result of the most recent recalculation one of the indicator parameters, specific conductance, exceeded its background value in downgradient well 299-W19-41, triggering a change from detection monitoring to groundwater quality assessment program. The major contributors to the higher specific conductance are nonhazardous constituents (i.e., sodium, calcium, magnesium, chloride, sulfate, and bicarbonate). Nitrate, chromium, and technetium-99 are present and are increasing; however, they are significantly below their drinking waster standards. Interpretation of groundwater monitoring data indicates that both the nonhazardous constituents causing elevated specific conductance in groundwater and the tank waste constituents present in groundwater at the waste management area are a result of surface water infiltration in the southern portion of the facility. There is evidence for both upgradient and waste management area sources for observed nitrate concentrations. There is no indication of an upgradient source for the observed chromium and technetium-99.

Ecology and living conditions of groundwater fauna

Energy Technology Data Exchange (ETDEWEB)

Thulin, Barbara [Geo Innova AB (Sweden); Hahn, Hans Juergen [Arbeitsgruppe Grundwasseroekologie, Univ. of Koblenz-Landau (Germany)

2008-09-15

This report presents the current state of ecological knowledge and applied research relating to groundwater. A conceptual picture is given of groundwater fauna occurrence in regard to Swedish environmental conditions. Interpretation features for groundwater fauna and applications are outlined. Groundwater is one of the largest and oldest limnic habitats populated by a rich and diverse fauna. Both very old species and species occurring naturally in brackish or salt water can be found in groundwater. Groundwater ecosystems are heterotrophic; the fauna depends on imports from the surface. Most species are meiofauna, 0.3-1 mm. The food chain of groundwater fauna is the same as for relatives in surface water and salt water. Smaller animals graze biofilms and detritus, larger animals act facutatively as predators. A difference is that stygobiotic fauna has become highly adapted to its living space and tolerates very long periods without food. Oxygen is a limiting factor, but groundwater fauna tolerates periods with low oxygen concentrations, even anoxic conditions. For longer periods of time a minimum oxygen requirement of 1 mg/l should be fulfilled. Geographic features such as Quaternary glaciation and very old Pliocene river systems are important for distribution patterns on a large spatial scale, but aquifer characteristics are important on a landscape scale. Area diversity is often comparable to surface water diversity. However, site diversity is low in groundwater. Site specific hydrological exchange on a geological facies level inside the aquifer, e.g. porous, fractured and karstic aquifers as well as the hyporheic zone, controls distribution patterns of groundwater fauna. For a better understanding of controlling factors indicator values are suggested. Different adequate sampling methods are available. They are representative for the aquifer, but a suitable number of monitoring wells is required. The existence of groundwater fauna in Sweden is considered as very

Ecology and living conditions of groundwater fauna

International Nuclear Information System (INIS)

Thulin, Barbara; Hahn, Hans Juergen

2008-09-01

This report presents the current state of ecological knowledge and applied research relating to groundwater. A conceptual picture is given of groundwater fauna occurrence in regard to Swedish environmental conditions. Interpretation features for groundwater fauna and applications are outlined. Groundwater is one of the largest and oldest limnic habitats populated by a rich and diverse fauna. Both very old species and species occurring naturally in brackish or salt water can be found in groundwater. Groundwater ecosystems are heterotrophic; the fauna depends on imports from the surface. Most species are meiofauna, 0.3-1 mm. The food chain of groundwater fauna is the same as for relatives in surface water and salt water. Smaller animals graze biofilms and detritus, larger animals act facutatively as predators. A difference is that stygobiotic fauna has become highly adapted to its living space and tolerates very long periods without food. Oxygen is a limiting factor, but groundwater fauna tolerates periods with low oxygen concentrations, even anoxic conditions. For longer periods of time a minimum oxygen requirement of 1 mg/l should be fulfilled. Geographic features such as Quaternary glaciation and very old Pliocene river systems are important for distribution patterns on a large spatial scale, but aquifer characteristics are important on a landscape scale. Area diversity is often comparable to surface water diversity. However, site diversity is low in groundwater. Site specific hydrological exchange on a geological facies level inside the aquifer, e.g. porous, fractured and karstic aquifers as well as the hyporheic zone, controls distribution patterns of groundwater fauna. For a better understanding of controlling factors indicator values are suggested. Different adequate sampling methods are available. They are representative for the aquifer, but a suitable number of monitoring wells is required. The existence of groundwater fauna in Sweden is considered as very

Tritium/Helium-3 dating of groundwaters around Chernobyl site

Energy Technology Data Exchange (ETDEWEB)

Fourre, E.; Jean-Baptiste, P.; Dapoigny, A.; Baumier, D. [CEA, CNRS, LSCE, UVSQ, IPSL, F-91191 Gif Sur Yvette (France); Aquilina, L.; Labasque, T. [Geosciences Rennes - GR, CNRS UMR 6118, F-35000 Rennes (France); La Salle, C. Le Gal; Lancelot, J. [Nimes Univ, GIS/CEREGE, Nimes (France)

2010-07-01

Complete text of publication follows: Estimates of groundwater age allow geo-hydrologists to calculate recharge rates, assess aquifers contamination risks, and calibrate complex flow models. The {sup 3}H/{sup 3}He dating method offers a direct measure for the time since groundwater had its last gas exchange with the atmosphere. The aim of this study is to bring temporal constraints to the radionuclide transport model in the Chernobyl test site. Samples have been collected in the exclusion zone, close to a trench filled with low-level wastes, both in the upper eolian sand layer and deeper in the alluvial deposit. CFCs and SF6 have been measured as well in order to compare dating methods. The {sup 3}H/{sup 3}He results presented in Figure 1 clearly show increasing ages with depth (below groundwater table). This fully supports the groundwater stratification developed in the hydrogeological model of the area. The infiltration recharge rate is a sensitive key parameter of the model, and our data are consistent with a rate about 200 mm/yr (maximum estimate)

Hanford Site ground-water monitoring for 1995

International Nuclear Information System (INIS)

Dresel, P.E.; Rieger, J.T.; Webber, W.D.; Thorne, P.D.; Gillespie, B.M.; Luttrell, S.P.; Wurstner, S.K.; Liikala, T.L.

1996-08-01

This report presents the results of the Groundwater Surveillance Project monitoring for calendar year 1995 on the Hanford Site, Washington. Hanford Site operations from 1943 onward produced large quantities of radiological and chemical waste that impacted groundwater quality on the site. Monitoring of water levels and groundwater chemistry is performed to track the extent of contamination, to note trends in contaminant concentrations,a nd to identify emerging groundwater quality problems. Data from other monitoring and characterization programs were incorporated to provide an integrated assessment of onsite groundwater quality. A three- dimensional, numerical, groundwater model is being developed to improve predictions of contaminant transport. The existing two- dimensional model was applied to predict contaminant flow paths and the impact of changes on site conditions. These activities were supported by limited hydrogeologic characterization. Water level monitoring was performed to evaluate groundwater flow directions, to track changes in water levels, and to relate such changes to evolving disposal practices. Radiological monitoring results indicated that many radioactive contaminants were above US Environmental Protection Agency or State of Washington drinking water standards at the Hanford Site. Nitrate, fluoride, chromium, cyanide, carbon tetrachloride, chloroform, trichloroethylene, and cis-1,2-dichloroethylene were present in groundwater samples at levels above their US EPA or State of Washington maximum contaminant levels

Numerical groundwater-flow modeling to evaluate potential effects of pumping and recharge: implications for sustainable groundwater management in the Mahanadi delta region, India

Science.gov (United States)

Sahoo, Sasmita; Jha, Madan K.

2017-12-01

Process-based groundwater models are useful to understand complex aquifer systems and make predictions about their response to hydrological changes. A conceptual model for evaluating responses to environmental changes is presented, considering the hydrogeologic framework, flow processes, aquifer hydraulic properties, boundary conditions, and sources and sinks of the groundwater system. Based on this conceptual model, a quasi-three-dimensional transient groundwater flow model was designed using MODFLOW to simulate the groundwater system of Mahanadi River delta, eastern India. The model was constructed in the context of an upper unconfined aquifer and lower confined aquifer, separated by an aquitard. Hydraulic heads of 13 shallow wells and 11 deep wells were used to calibrate transient groundwater conditions during 1997-2006, followed by validation (2007-2011). The aquifer and aquitard hydraulic properties were obtained by pumping tests and were calibrated along with the rainfall recharge. The statistical and graphical performance indicators suggested a reasonably good simulation of groundwater flow over the study area. Sensitivity analysis revealed that groundwater level is most sensitive to the hydraulic conductivities of both the aquifers, followed by vertical hydraulic conductivity of the confining layer. The calibrated model was then employed to explore groundwater-flow dynamics in response to changes in pumping and recharge conditions. The simulation results indicate that pumping has a substantial effect on the confined aquifer flow regime as compared to the unconfined aquifer. The results and insights from this study have important implications for other regional groundwater modeling studies, especially in multi-layered aquifer systems.

Occurrence of pharmaceuticals, hormones, and perfluorinated compounds in groundwater in Taiwan.

Science.gov (United States)

Lin, Yen-Ching; Lai, Webber Wei-Po; Tung, Hsin-hsin; Lin, Angela Yu-Chen

2015-05-01

In this work, we investigated the emerging pollutants in Taiwanese groundwater for the first time and correlated their presence with possible contamination sources. Fifty target pharmaceuticals and perfluorinated chemicals in groundwater were mostly present at ng L(-1) concentrations, except for 17α-ethynylestradiol, sulfamethoxazole, and acetaminophen (maximums of 1822, 1820, and 1036 ng L(-1), respectively). Perfluorinated compounds were detected with the highest frequencies in groundwater at almost all of the sample sites, especially short-chained perfluorinated carboxylates, which were easily transferred to the groundwater. The results indicate that the compounds found to have high detection frequencies and concentrations in groundwater are similar to those found in other countries around the world. Most common pharmaceuticals that contain hydrophilic groups, such as sulfonamide antibiotics and caffeine, are easily transported through surface waters to groundwater. The results also indicated that the persistent natures of emerging contaminants with high detection frequencies in surface water and groundwater, such as perfluorooctanesulfonate (risk quotient >1), caffeine, and carbamazepine, should be further studied and evaluated.

Gravity survey of groundwater characterization at Labuan Basin

Science.gov (United States)

Handayani, L.; Wardhana, D. D.; Hartanto, P.; Delinom, R.; Sudaryanto; Bakti, H.; Lubis, RF

2018-02-01

Labuan groundwater basin currently has an abundance of water. As a deltaic area of Lada Bay, groundwater supply comes from local precipitation and also from recharge region in mountain ranges surrounding. However, Labuan has been experiencing a fast economic development with high population and tourism industry growth. Such progress would lead to the increase of water consumption. A comprehensive groundwater management should be prepared for possible future problems. Therefore, a groundwater investigation is a necessary step towards that purpose. Gravity method was applied to identify the regional condition of the basement. The assessment of deep buried basin and basement relationship using gravity data is a challenge in groundwater investigation, but previous studies had indicated the efficiency of the method to obtain basic information and can be used as a foundation for more advanced studies.

Arsenic mobilization in a freshening groundwater system formed within glaciomarine deposits

International Nuclear Information System (INIS)

Cavalcanti de Albuquerque, R.; Kirste, D.

2012-01-01

Arsenic release to groundwater and conditions favoring As mobility are investigated in a system of aquifers formed within unconsolidated Quaternary sediments. The studied groundwater system is comprised of unconfined aquifers formed in glaciofluvial sediments with Ca–Mg–HCO 3 groundwater, and confined aquifers formed within glaciomarine sediments with high As (above 10 μg/L) Na–HCO 3 or Na–Cl groundwater. A positive relationship of As concentrations with the Na/(Ca + Mg) ratio of groundwater indicates that As release occurs in glaciomarine sediments concurrent to cation exchange reactions related to groundwater freshening. Arsenic is mobile in confined aquifers as a result of groundwater basic pH which prevents arsenate from adsorbing to mineral surfaces, and reducing conditions that favor speciation to arsenite. Selected extractions applied to sediment core samples indicate that As occurs in sediments predominantly in sulfide minerals and in Mn oxides and/or Fe oxyhydroxides. General positive relationships between As and the reduced species Fe 2+ , NH 3 and dissolved S 2− suggest that As release occurs at increasingly reducing conditions. Despite likely As release via Fe oxyhydroxide reductive dissolution, Fe remains at relatively low concentrations in groundwater (up to 0.37 mg/L) as a result of possible Fe adsorption and Fe reprecipitation as carbonate minerals favored by basic pH and high alkalinity. The presence of S 2− in some samples, a negative relationship between δ 34 S of SO 4 and SO 4 2- concentrations, and a positive relationship between δ 34 S and δ 18 O of SO 4 indicate that groundwater in confined aquifers is undergoing bacterial SO 4 reduction.

Groundwater Quality Assessment for Waste Management Area U: First Determination

Energy Technology Data Exchange (ETDEWEB)

FN Hodges; CJ Chou

2000-08-04

Waste Management Area U (TWA U) is located in the 200 West Area of the Hanford Site. The area includes the U Tank Farm, which contains 16 single-shell tanks and their ancillary equipment and waste systems. WMA U is regulated under the Resource Conservation and Recovery Act of 1976 (RCRA) as stipulated in 40 CFR Part 265, Subpart F, which is incorporated into the Washington State dangerous waste regulations (WAC 173-303400) by reference. Groundwater monitoring at WMA U has been guided by an interim status indicator evaluation program. As a result of changes in the direction of groundwater flow, background values for the WMA have been recalculated several times during its monitoring history. The most recent recalculation revealed that one of the indicator parameters, specific conductance, exceeded its background value in downgradient well 299-W19-41. This triggered a change from detection monitoring to a groundwater quality assessment program. The major contributors to the higher specific conductance are nonhazardous constituents, such as bicarbonate, calcium, chloride, magnesium, sodium and sulfate. Chromium, nitrate, and technetium-99 are present and are increasing; however, they are significantly below their drinking water standards. The objective of this study is to determine whether the increased concentrations of chromium, nitrate, and technetium-99 in groundwater are from WMA U or from an upgradient source. Interpretation of groundwater monitoring data indicates that both the nonhazardous constituents causing elevated specific conductance in groundwater and the tank waste constituents present in groundwater at the WMA are a result of surface water infiltration in the southern portion of the WMA. There is evidence that both upgradient and WMA sources contribute to the nitrate concentrations that were detected. There is no indication of an upgradient source for the chromium and technetium-99 that was detected. Therefore, a source of contamination appears to

Groundwater Quality Assessment for Waste Management Area U: First Determination

International Nuclear Information System (INIS)

FN Hodges; CJ Chou

2000-01-01

Waste Management Area U (TWA U) is located in the 200 West Area of the Hanford Site. The area includes the U Tank Farm, which contains 16 single-shell tanks and their ancillary equipment and waste systems. WMA U is regulated under the Resource Conservation and Recovery Act of 1976 (RCRA) as stipulated in 40 CFR Part 265, Subpart F, which is incorporated into the Washington State dangerous waste regulations (WAC 173-303400) by reference. Groundwater monitoring at WMA U has been guided by an interim status indicator evaluation program. As a result of changes in the direction of groundwater flow, background values for the WMA have been recalculated several times during its monitoring history. The most recent recalculation revealed that one of the indicator parameters, specific conductance, exceeded its background value in downgradient well 299-W19-41. This triggered a change from detection monitoring to a groundwater quality assessment program. The major contributors to the higher specific conductance are nonhazardous constituents, such as bicarbonate, calcium, chloride, magnesium, sodium and sulfate. Chromium, nitrate, and technetium-99 are present and are increasing; however, they are significantly below their drinking water standards. The objective of this study is to determine whether the increased concentrations of chromium, nitrate, and technetium-99 in groundwater are from WMA U or from an upgradient source. Interpretation of groundwater monitoring data indicates that both the nonhazardous constituents causing elevated specific conductance in groundwater and the tank waste constituents present in groundwater at the WMA are a result of surface water infiltration in the southern portion of the WMA. There is evidence that both upgradient and WMA sources contribute to the nitrate concentrations that were detected. There is no indication of an upgradient source for the chromium and technetium-99 that was detected. Therefore, a source of contamination appears to

Krypton-81 in groundwater of the Culebra Dolomite near the Waste Isolation Pilot Plant, New Mexico.

Science.gov (United States)

Sturchio, Neil C; Kuhlman, Kristopher L; Yokochi, Reika; Probst, Peter C; Jiang, Wei; Lu, Zheng-Tian; Mueller, Peter; Yang, Guo-Min

2014-05-01

The Waste Isolation Pilot Plant (WIPP) in New Mexico is the first geologic repository for disposal of transuranic nuclear waste from defense-related programs of the US Department of Energy. It is constructed within halite beds of the Permian-age Salado Formation. The Culebra Dolomite, confined within Rustler Formation evaporites overlying the Salado Formation, is a potential pathway for radionuclide transport from the repository to the accessible environment in the human-disturbed repository scenario. Although extensive subsurface characterization and numerical flow modeling of groundwater has been done in the vicinity of the WIPP, few studies have used natural isotopic tracers to validate the flow models and to better understand solute transport at this site. The advent of Atom-Trap Trace Analysis (ATTA) has enabled routine measurement of cosmogenic (81)Kr (half-life 229,000 yr), a near-ideal tracer for long-term groundwater transport. We measured (81)Kr in saline groundwater sampled from two Culebra Dolomite monitoring wells near the WIPP site, and compared (81)Kr model ages with reverse particle-tracking results of well-calibrated flow models. The (81)Kr model ages are ~130,000 and ~330,000 yr for high-transmissivity and low-transmissivity portions of the formation, respectively. Compared with flow model results which indicate a relatively young mean hydraulic age (~32,000 yr), the (81)Kr model ages imply substantial physical attenuation of conservative solutes in the Culebra Dolomite and provide limits on the effective diffusivity of contaminants into the confining aquitards. Copyright © 2014 Elsevier B.V. All rights reserved.

Nitrogen speciation and trends, and prediction of denitrification extent, in shallow US groundwater

Science.gov (United States)

Hinkle, Stephen R.; Tesoriero, Anthony J.

2014-01-01

Uncertainties surrounding nitrogen cycling complicate assessments of the environmental effects of nitrogen use and our understanding of the global carbon–nitrogen cycle. In this paper, we synthesize data from 877 ambient-monitoring wells across the US to frame broad patterns of nitrogen speciation and trends. At these sites, groundwater frequently contains substantial co-occurring NO3− and XSN2 (N2 from denitrification), reflecting active/ongoing denitrification and/or a mixture of undenitrified and denitrified groundwater. NO3− and NH4+ essentially do not co-occur, indicating that the dominant source of NH4+ at these sites likely is not dissimilatory reduction of NO3− to NH4+. Positive correlations of NH4+ with apparent age, CH4, dissolved organic carbon, and indicators of reduced conditions are consistent with NH4+ mobilization from degradation of aquifer organic matter and contraindicate an anthropogenic source of NH4+ for most sites. Glacial aquifers and eastern sand and gravel aquifers generally have lower proportions of NO3− and greater proportions of XSN2 than do fractured rock and karst aquifers and western sand and gravel aquifers. NO3− dominates in the youngest groundwater, but XSN2 increases as residence time increases. Temporal patterns of nitrogen speciation and concentration reflect (1) changing NO3− loads over time, (2) groundwater residence-time controls on NH4+ mobilization from solid phases, and (3) groundwater residence-time controls on denitrification. A simple classification tree using readily available variables (a national coverage of soil water depth, generalized geology) or variables reasonably estimated in many aquifers (residence time) identifies categorical denitrification extent (50%) with 79% accuracy in an independent testing set, demonstrating a predictive application based on the interconnected effects of redox, geology, and residence time.

Groundwater availability of the Mississippi embayment

Science.gov (United States)

Clark, Brian R.; Hart, Rheannon M.; Gurdak, Jason J.

2011-01-01

River Valley alluvial aquifer in Arkansas, Louisiana, Mississippi, and Missouri, and to a lesser extent in Illinois, Kentucky, and Tennessee. Predevelopment groundwater flow is represented in the MERAS model as a steady-state stress period, assumed to be prior to 1870. The simulated groundwater-flow budget indicates the largest predevelopment inflow to the system is net recharge to the alluvial aquifer. This inflow is balanced by outflow to gaining streams. Overall, water enters as net recharge to the alluvial aquifer or through outcrop areas of the various hydrogeologic units. Away from the outcrop areas, groundwater flow in the deeper formations is primarily upward into overlying units, ultimately discharging to streams through the alluvial aquifer. Total net recharge and discharge (sum of inflows or outflows) for the model ranged from about 0.66 million acre-feet per year during predevelopment to 20.16 million acre-feet per year by the end of the simulation (final simulated irrigation period in summer of 2006). This change in the model budget reflects increases in withdrawals compared to predevelopment conditions. Cumulative storage within aquifers simulated in the MERAS model indicates overall depletion of 140 million acre-feet (equivalent to 2.8 feet of water covering the entire study area). Postdevelopment inflow to the system is still through net recharge to the alluvial aquifer and the outcrop areas of the several hydrogeologic units, however, the flow between each unit is no longer upward to the alluvial aquifer. Groundwater flow during the summer of 2006 was primarily downward to offset demand from pumping. Early in the model simulation (1870-1920s), the primary components of the water budget were simulated as outflow from stream leakage and inflow from net recharge. As pumpage increased through time, water that would otherwise flow to streams reversed, and net stream leakage became an inflow to the system. The largest reversals began in the mid-1980s, but

Mapping and quantifying groundwater inflows to Deep Creek (Maribyrnong catchment, SE Australia) using 222Rn, implications for protecting groundwater-dependant ecosystems

International Nuclear Information System (INIS)

Cartwright, Ian; Gilfedder, Benjamin

2015-01-01

Highlights: • Groundwater inflows in a chain-of-ponds river quantified. • Groundwater inflow vs. discharge relationship determined using Rn. • First long-term continuous Rn monitoring in a river indicates temporal changes to groundwater inflows. • Application to protection of groundwater-dependant ecosystems. - Abstract: Understanding groundwater inflows to rivers is important in managing connected groundwater and surface water systems and for protecting groundwater-dependant ecosystems. This study defines the distribution of gaining reaches and estimates groundwater inflows to a 62 km long section of Deep Creek (Maribyrnong catchment, Australia) using 222 Rn. During summer months, Deep Creek ceases to flow and comprises a chain of ponds that δ 18 O and δ 2 H values, major ion concentrations, and 222 Rn activities imply are groundwater fed. During the period where the river flows, the relative contribution of groundwater inflows to total river discharge ranges from ∼14% at high flow conditions to ∼100% at low flows. That the predicted groundwater inflows account for all of the increase in discharge at low flow conditions lends confidence to the mass balance calculations. Near-continuous 27 week 222 Rn monitoring at one location in the middle of the catchment confirms the inverse correlation between river discharge and relative groundwater inflows, and also implies that there are limited bank return flows. Variations in groundwater inflows are related to geology and topography. High groundwater inflows occur where the river is at the edge of its floodplain, adjacent to hills composed of basement rocks, or flowing through steep incised valleys. Understanding the distribution of groundwater inflows and quantifying the contribution of groundwater to Deep Creek is important for managing and protecting the surface water resources, which support the endangered Yarra pygmy perch

Geochemistry and hydrology of perched groundwater springs: assessing elevated uranium concentrations at Pigeon Spring relative to nearby Pigeon Mine, Arizona (USA)

Science.gov (United States)

Beisner, Kimberly R.; Paretti, Nicholas; Tillman, Fred; Naftz, David L.; Bills, Donald; Walton-Day, Katie; Gallegos, Tanya J.

2017-01-01

The processes that affect water chemistry as the water flows from recharge areas through breccia-pipe uranium deposits in the Grand Canyon region of the southwestern United States are not well understood. Pigeon Spring had elevated uranium in 1982 (44 μg/L), compared to other perched springs (2.7–18 μg/L), prior to mining operations at the nearby Pigeon Mine. Perched groundwater springs in an area around the Pigeon Mine were sampled between 2009 and 2015 and compared with material from the Pigeon Mine to better understand the geochemistry and hydrology of the area. Two general groups of perched groundwater springs were identified from this study; one group is characterized by calcium sulfate type water, low uranium activity ratio 234U/238U (UAR) values, and a mixture of water with some component of modern water, and the other group by calcium-magnesium sulfate type water, higher UAR values, and radiocarbon ages indicating recharge on the order of several thousand years ago. Multivariate statistical principal components analysis of Pigeon Mine and spring samples indicate Cu, Pb, As, Mn, and Cd concentrations distinguished mining-related leachates from perched groundwater springs. The groundwater potentiometric surface indicates that perched groundwater at Pigeon Mine would likely flow toward the northwest away from Pigeon Spring. The geochemical analysis of the water, sediment and rock samples collected from the Snake Gulch area indicate that the elevated uranium at Pigeon Spring is likely related to a natural source of uranium upgradient from the spring and not likely related to the Pigeon Mine.

Temporal changes in groundwater quality of the Saloum coastal aquifer

Directory of Open Access Journals (Sweden)

Ndeye Maguette Dieng

2017-02-01

High variation in rainfall between the 2 reference years (2003 and 2012 also changes chemical patterns in the groundwater. Chemical evolution of the groundwater is geographically observed and is due to a combination of dilution by recharge, anthropic contamination and seawater intrusion. The results of environmental isotopes (δ18O, δ2H compared with the local meteoric line indicate that the groundwater has been affected by evaporation processes before and during infiltration. The results also clearly indicate mixing with saltwater and an evolution towards relative freshening between 2003 and 2012 in some wells near the Saloum River.

Characterizing the interaction of groundwater and surface water in the karst aquifer of Fangshan, Beijing (China)

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Chu, Haibo; Wei, Jiahua; Wang, Rong; Xin, Baodong

2017-03-01

Correct understanding of groundwater/surface-water (GW-SW) interaction in karst systems is of greatest importance for managing the water resources. A typical karst region, Fangshan in northern China, was selected as a case study. Groundwater levels and hydrochemistry analyses, together with isotope data based on hydrogeological field investigations, were used to assess the GW-SW interaction. Chemistry data reveal that water type and the concentration of cations in the groundwater are consistent with those of the surface water. Stable isotope ratios of all samples are close to the local meteoric water line, and the 3H concentrations of surface water and groundwater samples are close to that of rainfall, so isotopes also confirm that karst groundwater is recharged by rainfall. Cross-correlation analysis reveals that rainfall leads to a rise in groundwater level with a lag time of 2 months and groundwater exploitation leads to a fall within 1 month. Spectral analysis also reveals that groundwater level, groundwater exploitation and rainfall have significantly similar response periods, indicating their possible inter-relationship. Furthermore, a multiple nonlinear regression model indicates that groundwater level can be negatively correlated with groundwater exploitation, and positively correlated with rainfall. The overall results revealed that groundwater level has a close correlation with groundwater exploitation and rainfall, and they are indicative of a close hydraulic connection and interaction between surface water and groundwater in this karst system.

Climate variability, rice production and groundwater depletion in India

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Bhargava, Alok

2018-03-01

This paper modeled the proximate determinants of rice outputs and groundwater depths in 27 Indian states during 1980-2010. Dynamic random effects models were estimated by maximum likelihood at state and well levels. The main findings from models for rice outputs were that temperatures and rainfall levels were significant predictors, and the relationships were quadratic with respect to rainfall. Moreover, nonlinearities with respect to population changes indicated greater rice production with population increases. Second, groundwater depths were positively associated with temperatures and negatively with rainfall levels and there were nonlinear effects of population changes. Third, dynamic models for in situ groundwater depths in 11 795 wells in mainly unconfined aquifers, accounting for latitudes, longitudes and altitudes, showed steady depletion. Overall, the results indicated that population pressures on food production and environment need to be tackled via long-term healthcare, agricultural, and groundwater recharge policies in India.

Assessment of groundwater contamination risk using hazard quantification, a modified DRASTIC model and groundwater value, Beijing Plain, China.

Science.gov (United States)

Wang, Junjie; He, Jiangtao; Chen, Honghan

2012-08-15

Groundwater contamination risk assessment is an effective tool for groundwater management. Most existing risk assessment methods only consider the basic contamination process based upon evaluations of hazards and aquifer vulnerability. In view of groundwater exploitation potentiality, including the value of contamination-threatened groundwater could provide relatively objective and targeted results to aid in decision making. This study describes a groundwater contamination risk assessment method that integrates hazards, intrinsic vulnerability and groundwater value. The hazard harmfulness was evaluated by quantifying contaminant properties and infiltrating contaminant load, the intrinsic aquifer vulnerability was evaluated using a modified DRASTIC model and the groundwater value was evaluated based on groundwater quality and aquifer storage. Two groundwater contamination risk maps were produced by combining the above factors: a basic risk map and a value-weighted risk map. The basic risk map was produced by overlaying the hazard map and the intrinsic vulnerability map. The value-weighted risk map was produced by overlaying the basic risk map and the groundwater value map. Relevant validation was completed by contaminant distributions and site investigation. Using Beijing Plain, China, as an example, thematic maps of the three factors and the two risks were generated. The thematic maps suggested that landfills, gas stations and oil depots, and industrial areas were the most harmful potential contamination sources. The western and northern parts of the plain were the most vulnerable areas and had the highest groundwater value. Additionally, both the basic and value-weighted risk classes in the western and northern parts of the plain were the highest, indicating that these regions should deserve the priority of concern. Thematic maps should be updated regularly because of the dynamic characteristics of hazards. Subjectivity and validation means in assessing the

Groundwater dating by means of isotopes

International Nuclear Information System (INIS)

Johansson, Barbro

1980-08-01

A short review is given of method for dating old groundwater by isotopetechniques. The carbon-14 method is then treated in detail; Carbon dioxide, released by root respiration of plants, and by decomposition of organic matter in the soil, is dissolved in soil water. The production of carbon dioxide in the root zone is high and the 14 C/ 12 C ratio is therefore assumed to be the same as in the plants. The residence time of water in the groundwater zone may then be computed, according to the laws of radioactive decay. No attempts have been made to compute the changes in the carbon-14 content of the soil air due to weathering. To do this, one would need to consider diffusion of gaseous carbon dioxide into and out of the soil. The amount of carbon entering the water through weathering in the groundwater zone may be compute if certain assumptions are made. To know if these assumptions are valid for the water of a special area, detailed knowledge about the area is required. In this report, an attempt is made to follow the changes in the composition of the water as the water moves through the ground. The differentiated equilibrium equations of the carbon dioxide system and the ionic balance are used for the calculations. It is assumed that when calcite is present in the ground, weathering of other minerals may be neglected. In order to test its usefulness, the method has been tried on groundwater from a borehole in Kraakemaala, Sweden. The results are very much dependent on the values of some of the parameters used in the calculations. The σ 13 C values especially have a great influence on the calculated age. As long as additional information on conditions at different depth remains unavailable, it seems impossible to determine the age of water with any accuracy. Only a range, which sometimes embraces several thousand years, can be given. A good aid to a better estimate of the age would be obtained if samples of water along a flow path were available. One way to get such

Distribution and Sources of Nitrate-Nitrogen in Kansas Groundwater

Directory of Open Access Journals (Sweden)

Margaret A. Townsend

2001-01-01

Full Text Available Kansas is primarily an agricultural state. Irrigation water and fertilizer use data show long- term increasing trends. Similarly, nitrate-N concentrations in groundwater show long-term increases and exceed the drinking-water standard of 10 mg/l in many areas. A statistical analysis of nitrate-N data collected for local and regional studies in Kansas from 1990 to 1998 (747 samples found significant relationships between nitrate-N concentration with depth, age, and geographic location of wells. Sources of nitrate-N have been identified for 297 water samples by using nitrogen stable isotopes. Of these samples, 48% showed fertilizer sources (+2 to +8 and 34% showed either animal waste sources (+10 to +15 with nitrate-N greater than 10 mg/l or indication that enrichment processes had occurred (+10 or above with variable nitrate-N or both. Ultimate sources for nitrate include nonpoint sources associated with past farming and fertilization practices, and point sources such as animal feed lots, septic systems, and commercial fertilizer storage units. Detection of nitrate from various sources in aquifers of different depths in geographically varied areas of the state indicates that nonpoint and point sources currently impact and will continue to impact groundwater under current land uses.

Spatial variability analysis of combining the water quality and groundwater flow model to plan groundwater and surface water management in the Pingtung plain

Science.gov (United States)

Chen, Ching-Fang; Chen, Jui-Sheng; Jang, Cheng-Shin

2014-05-01

As a result of rapid economic growth in the Pingtung Plain, the use of groundwater resources has changed dramatically. The groundwater is quite rich in the Pingtung plain and the most important water sources. During the several decades, a substantial amount of groundwater has been pumped for the drinking, irrigation and aquaculture water supplies. However, because the sustainable use concept of groundwater resources is lack, excessive pumping of groundwater causes the occurrence of serious land subsidence and sea water intrusion. Thus, the management and conservation of groundwater resources in the Pingtung plain are considerably critical. This study aims to assess the conjunct use effect of groundwater and surface water in the Pingtung plain on recharge by reducing the amount of groundwater extraction. The groundwater quality variability and groundwater flow models are combined to spatially analyze potential zones of groundwater used for multi-purpose in the Pingtung Plain. First, multivariate indicator kriging (MVIK) is used to analyze spatial variability of groundwater quality based on drinking, aquaculture and irrigation water quality standards, and probabilistically delineate suitable zones in the study area. Then, the groundwater flow model, Processing MODFLOW (PMWIN), is adopted to simulate groundwater flow. The groundwater flow model must be conducted by the calibration and verification processes, and the regional groundwater recovery is discussed when specified water rights are replaced by surface water in the Pingtung plain. Finally, the most suitable zones of reducing groundwater use are determined for multi-purpose according to combining groundwater quality and quantity. The study results can establish a sound and low-impact management plan of groundwater resources utilization for the multi-purpose groundwater use, and prevent decreasing ground water tables, and the occurrence of land subsidence and sea water intrusion in the Pingtung plain.

Building groundwater modeling capacity in Mongolia

Science.gov (United States)

Valder, Joshua F.; Carter, Janet M.; Anderson, Mark T.; Davis, Kyle W.; Haynes, Michelle A.; Dorjsuren Dechinlhundev,

2016-06-16

Ulaanbaatar, the capital city of Mongolia (fig. 1), is dependent on groundwater for its municipal and industrial water supply. The population of Mongolia is about 3 million people, with about one-half the population residing in or near Ulaanbaatar (World Population Review, 2016). Groundwater is drawn from a network of shallow wells in an alluvial aquifer along the Tuul River. Evidence indicates that current water use may not be sustainable from existing water sources, especially when factoring the projected water demand from a rapidly growing urban population (Ministry of Environment and Green Development, 2013). In response, the Government of Mongolia Ministry of Environment, Green Development, and Tourism (MEGDT) and the Freshwater Institute, Mongolia, requested technical assistance on groundwater modeling through the U.S. Army Corps of Engineers (USACE) to the U.S. Geological Survey (USGS). Scientists from the USGS and USACE provided two workshops in 2015 to Mongolian hydrology experts on basic principles of groundwater modeling using the USGS groundwater modeling program MODFLOW-2005 (Harbaugh, 2005). The purpose of the workshops was to bring together representatives from the Government of Mongolia, local universities, technical experts, and other key stakeholders to build in-country capacity in hydrogeology and groundwater modeling.A preliminary steady-state groundwater-flow model was developed as part of the workshops to demonstrate groundwater modeling techniques to simulate groundwater conditions in alluvial deposits along the Tuul River in the vicinity of Ulaanbaatar. ModelMuse (Winston, 2009) was used as the graphical user interface for MODFLOW for training purposes during the workshops. Basic and advanced groundwater modeling concepts included in the workshops were groundwater principles; estimating hydraulic properties; developing model grids, data sets, and MODFLOW input files; and viewing and evaluating MODFLOW output files. A key to success was

Hydrogeochemistry and Stable Isotope Studies of Groundwater in the Ga West Municipal Area, Ghana

International Nuclear Information System (INIS)

Saka, David

2011-07-01

This study assesses groundwater in the Ga West Municipal Area of Ghana using hydrogeochemistry and stable isotope approaches. High salinity groundwaters are obtained in the municipality which poses problems for current and future domestic water supply exploitation. The increase in salinity is related to the dissolution of minerals in the host rocks and the evaporative concentration of solutes. The dominant groundwater composition in both shallow and deep wells sampled is Na-Cl, with concentration increasing substantially with well depths. The mixing process between freshwater and saline water was observed in the shift from CaHCO3 facies to Ca-Cl facies. Schoeller diagrams showed that groundwater movement in the study area is mostly vertical, moving from the shallow groundwaters towards the deep groundwaters. There were however few exceptions where no relationship was established between the shallow and the deep groundwaters. The oxygen and hydrogen isotope compositions in the groundwater samples suggest that groundwater recharge is of meteoric origin, with few samples showing evidence of evaporation. An average deuterium excess of rainfall of 14.2‰ was observed, which indicates the significance of kinetic evaporation due to low humidity conditions prevalent in the study area. The d-excess also indicates modern recharge along the Akwapim-Togo Ranges. Groundwater analysis for trace metals indicates that 93% of the groundwaters have Iron concentration above recommended limits. However, Cu, Zn, Pb, Cd and Cr have values within the acceptable limits. Generally, about 40% of the groundwaters sampled are not suitable for drinking and domestic purposes based on comparison with international standards for drinking water. (au)

Radioactivity in groundwater along the borders of Oman and UAE

International Nuclear Information System (INIS)

Murad, A.; Alshamsi, D.; Al Shidi, F.; Al Kendi, R.; Aldahan, A.; Uppsala University, Uppsala

2014-01-01

Characterizing the quality and radioactivity of groundwater is vital as it represents valuable resource in arid regions. Here we present radioactivity level in groundwater collected from wells in a region along the border between Sultanate of Oman and United Arab Emirates (UAE). The aquifers are alluvium deposits (silt, sand and gravel) and the measured groundwater radioactivity (including 232 Th, 238 U, 235 U, 226 Ra, 222 Rn, gross-α and gross-β) indicates values below the WHO permissible limits for drinking water. The results also show large difference in radioactivity fingerprints, in particular for 226 Ra and 222 Rn within the investigated aquifers. The data further indicate lower radioactivity in groundwater of the alluviums compared to the carbonate aquifers in the region. This feature makes the alluvium aquifers valuable reservoirs that should be carefully exploited as a source of groundwater. As this is the first investigation on the radioactivity of groundwater in alluvial aquifers in the region, it suggests that other alluvial deposits, particularly those inland and far from the marine water intrusion or seepage from carbonate rocks would have low radioactivity fingerprints. (author)

Distribution and sources of 226Rain groundwater of arid region

DEFF Research Database (Denmark)

Zheng, M. J.; Murad, A.; Zhou, X. D.

2016-01-01

As a part of characterizing radioactivity in groundwater of the eastern Arabian Peninsula, a first systematic evaluation of 226Ra activity in groundwater indicates a wide range (0.65-203.66 mBq L-1) with average of 17.56 mBq L-1. Adsorption/desorption process, groundwater residence time and urani...... concentration are the main controlling factors of 226Ra distribution in groundwater of the different aquifers. Estimation of 226Ra effective dose from water ingestion suggests potential risk of drinking water from the carbonate aquifer....

Evaluating Chemical Tracers in Suburban Groundwater as Indicators of Nitrate-Nitrogen Sources

Science.gov (United States)

Nitka, A.; DeVita, W. M.; McGinley, P.

2015-12-01

The CDC reports that over 15 million US households use private wells. These wells are vulnerable to contamination. One of the most common contaminants in private wells is nitrate. Nitrate has a health standard of 10 mg/L. This standard is set to prevent methemaglobinemia, or "blue baby" syndrome, in infants. In extreme cases it can affect breathing and heart function, and even lead to death. Elevated nitrate concentrations have also been associated with increased risk of thyroid disease, diabetes, and certain types of cancer. Unlike municipal wells, there is no mandatory testing of private wells. It is the responsibility of users to have their well water tested. The objective of this research was to identify the most useful chemical tracers for determining sources of nitrate in private water supplies. Chemical characteristics, such as mobility in groundwater and water solubility, as well as frequency of use, were considered when choosing source indicators. Fourteen pharmaceuticals and personal care products unique to human use were chosen to identify wells impacted by septic waste. A bovine antibiotic and five pesticide metabolites were used to identify contamination from agricultural sources. Eighteen private wells were selected in a suburban area with septic systems and adjacent agricultural land. The wells were sampled five times and analyzed to provide a temporal profile of nitrate and the tracers. The artificial sweetener sucralose was found in >70% of private wells. Wells with sucralose detected had nitrate concentrations between 5-15 mg/L. The herbicide metabolite metolachlor ESA was detected in 50% of the wells. These wells typically had the highest nitrate concentrations, often >10 mg/L. The common use and frequent detection of these two compounds made them the most reliable indicators of nitrate sources evaluated in this study. This information will help well owners determine appropriate treatment and remediation options and could direct future

Groundwater Pollution Source Characterization of an Old Landfill

DEFF Research Database (Denmark)

Kjeldsen, Peter

1993-01-01

Only a few landfill investigations have focused on both the quantity and the quality of leachate as a source of groundwater pollution. The investigation of Vejen Landfill in Denmark included an introductionary historical survey (old maps, aerial photographs, interviews, etc.), leachate quality...... analysis, potential mapping of the groundwater surface below the landfill and leachate flow to surface waters and groundwater. The historical investigation showed that the original soil surface beneath the waste was a relatively heterogeneous mixture of boggy ground and sand soil areas. This indicated...... that the leaching from the landfill could be unevenly distributed. The main specific organic compounds observed in the leachate were aromatic hydrocarbons (mainly xylenes), phenols and the pesticide MCPP. Preliminary investigations of the leach from the landfill indicated, that both a northerly leach to a drainage...

Groundwater flow in a coastal peatland and its influence on submarine groundwater discharge

Science.gov (United States)

Ptak, T.; Ibenthal, M.; Janssen, M.; Massmann, G.; Lenartz, B.

2017-12-01

Coastal peatlands are characterized by intense interactions between land and sea, comprising both a submarine discharge of fresh groundwater and inundations of the peatland with seawater. Nutrients and salts can influence the biogeochemical processes both in the shallow marine sediments and in the peatland. The determination of flow direction and quantity of groundwater flow are therefore elementary. Submarine groundwater discharge (SGD) has been reported from several locations in the Baltic. The objective of this study is to quantify the exchange of fresh and brackish water across the shoreline in a coastal peatland in Northeastern Germany, and to assess the influence of a peat layer extending into the Baltic Sea. Below the peatland, a shallow fine sand aquifer differs in depth and is limited downwards by glacial till. Water level and electrical conductivity (EC) are permanently measured in different depths at eight locations in the peatland. First results indicate a general groundwater flow direction towards the sea. Electrical conductivity measurements suggest different permeabilities within the peat layer, depending on its thickness and degradation. Near the beach, EC fluctuates partially during storm events due to seawater intrusion and reverse discharge afterwards. The groundwater flow will be verified with a 3D model considering varying thicknesses of the aquifer. Permanent water level and electrical conductivity readings, meteorological data and hydraulic conductivity from slug tests and grain size analysis are the base for the calibration of the numerical model.

Groundwater Pumping and Streamflow in the Yuba Basin, Sacramento Valley, California

Science.gov (United States)

Moss, D. R.; Fogg, G. E.; Wallender, W. W.

2011-12-01

Water transfers during drought in California's Sacramento Valley can lead to increased groundwater pumping, and as yet unknown effects on stream baseflow. Two existing groundwater models of the greater Sacramento Valley together with localized, monitoring of groundwater level fluctuations adjacent to the Bear, Feather, and Yuba Rivers, indicate cause and effect relations between the pumping and streamflow. The models are the Central Valley Hydrologic Model (CVHM) developed by the U.S. Geological Survey and C2VSIM developed by Department of Water Resources. Using two models which have similar complexity and data but differing approaches to the agricultural water boundary condition illuminates both the water budget and its uncertainty. Water budget and flux data for localized areas can be obtained from the models allowing for parameters such as precipitation, irrigation recharge, and streamflow to be compared to pumping on different temporal scales. Continuous groundwater level measurements at nested, near-stream piezometers show seasonal variations in streamflow and groundwater levels as well as the timing and magnitude of recharge and pumping. Preliminary results indicate that during years with relatively wet conditions 65 - 70% of the surface recharge for the groundwater system comes from irrigation and precipitation and 30 - 35% comes from streamflow losses. The models further indicate that during years with relatively dry conditions, 55 - 60% of the surface recharge for the groundwater system comes from irrigation and precipitation while 40 - 45% comes from streamflow losses. The models irrigation water demand, surface-water and groundwater supply, and deep percolation are integrated producing values for irrigation pumping. Groundwater extractions during the growing season, approximately between April and October, increase by almost 200%. The effects of increased pumping seasonally are not readily evident in stream stage measurements. However, during dry time

Groundwater-quality data in the Klamath Mountains study unit, 2010: results from the California GAMA Program

Science.gov (United States)

Mathany, Timothy M.; Belitz, Kenneth

2014-01-01

radioactivity, and microbial indicators (total coliform and Escherichia coli [E. coli]). Isotopic tracers (stable isotopes of hydrogen and oxygen in water, isotopic ratios of dissolved strontium in water, and stable isotopes of carbon in dissolved inorganic carbon), dissolved noble gases, and age-dating tracers (tritium and carbon-14) were measured to help identify sources and ages of sampled groundwater. Quality-control samples (field blanks, replicate sample pairs, and matrix spikes) were collected at 13 percent of the sites in the KLAM study unit, and the results were used to evaluate the quality of the data from the groundwater samples. Field blank samples rarely contained detectable concentrations of any constituent, indicating that contamination from sample collection or analysis was not a significant source of bias in the data for the groundwater samples. More than 99 percent of the replicate pair samples were within acceptable limits of variability. Matrix-spike sample recoveries were within the acceptable range (70 to 130 percent) for approximately 91 percent of the compounds. This study did not evaluate the quality of water delivered to consumers. After withdrawal, groundwater typically is treated, disinfected, and (or) blended with other waters to maintain water quality. Regulatory benchmarks apply to water that is delivered to the consumer, not to untreated groundwater. However, to provide some context for the results, concentrations of constituents measured in the untreated groundwater were compared with regulatory and non-regulatory health-based benchmarks established by the U.S. Environmental Protection Agency (USEPA) and CDPH, and to non-health-based benchmarks established for aesthetic concerns by the CDPH. Comparisons between data collected for this study and benchmarks for drinking water are for illustrative purposes only and are not indicative of compliance or non-compliance with those benchmarks. All concentrations of organic constituents from grid sites

Statistical analysis of lake levels and field study of groundwater and surface-water exchanges in the northeast Twin Cities Metropolitan Area, Minnesota, 2002 through 2015: Chapter A of Water levels and groundwater and surface-water exchanges in lakes of the northeast Twin Cities Metropolitan Area, Minnesota, 2002 through 2015

Science.gov (United States)

Jones, Perry M.; Trost, Jared J.; Diekoff, Aliesha L.; Rosenberry, Donald O.; White, Eric A.; Erickson, Melinda L.; Morel, Daniel L.; Heck, Jessica M.

2016-10-19

) closed-basin lake-level changes reflected groundwater-level changes in the Quaternary, Prairie du Chien, and Jordan aquifers; (3) the installation of outlet-control structures, such as culverts and weirs, resulted in smaller multiyear lake-level changes than lakes without outlet-control structures; (4) water levels in lakes primarily overlying Superior Lobe deposits were significantly more variable than lakes primarily overlying Des Moines Lobe deposits; (5) lake-level declines were larger with increasing mean lake-level elevation; and (6) the frequency of some of these characteristics varies by landscape position. Flow-through lakes and lakes with outlet-control structures were more common in watersheds with more than 50 percent urban development compared to watersheds with less than 50 percent urban development. A comparison of two 35-year periods during 1925–2014 revealed that variability of annual mean lake levels in flow-through lakes increased when annual precipitation totals were more variable, whereas variability of annual mean lake levels in closed-basin lakes had the opposite pattern, being more variable when annual precipitation totals were less variable. Oxygen-18/oxygen-16 and hydrogen-2/hydrogen-1 ratios for water samples from 40 wells indicated the well water was a mixture of surface water and groundwater in 31 wells, whereas ratios from water sampled from 9 other wells indicated that water from these wells receive no surface-water contribution. Of the 31 wells with a mixture of surface water and groundwater, 11 were downgradient from White Bear Lake, likely receiving water from deeper parts of the lake. Age dating of water samples from wells indicated that the age of water in the Prairie du Chien and Jordan aquifers can vary widely across the northeast Twin Cities Metropolitan Area. Estimated ages of recharge for 9 of the 40 wells sampled for chlorofluorocarbon concentrations ranged widely from the early 1940s to mid-1970s. The wide range in estimated

Evaluating Renewable Groundwater Stress with GRACE data in Greece

Science.gov (United States)

Lakshmi, V.; Gemitzi, A.

2016-12-01

Groundwater is a resilient water source and its importance as a fundamental resource is even greater in times of drought where groundwater stress conditions are greatest for areas like Mediterranean and adverse climate change effects are expected. The present study evaluates Renewable Groundwater Stress (RGS) as the ratio of groundwater use to groundwater availability, quantifying use as the trend in GRACE-derived subsurface anomalies (ΔGWtrend) and renewable groundwater availability as mean annual recharge. Estimates for mean annual recharge were used from groundwater studies conducted for the various regions in Greece, mainly in the form of numerical models. Our results highlighted two RGS regimes in Greece out of the four characteristic stress regimes, i.e. Overstressed, Variable Stress, Human-Dominated Stress and Unstressed, defined as a function of the sign of use and the sign of groundwater availability (positive or negative). Variable Stress areas are found in central Greece (Thessaly region), where intense agricultural activities take place, with negative ΔGWtrend values combined with positive mean annual recharge rates. RGS values range from -0.05 - 0, indicating however a low impact area. Within this region, adverse effects of groundwater overexploitation are already evident, based on the negative GRACE anomalies, recharge however still remains positive, amending the adverse over pumping impacts. The rest of Greek aquifers fall within the unstressed category, with RGS values from 0.02 - 0.05, indicating that the rate of use is less than the natural recharge rate. The highest Unstressed RGS values are observed in Crete Island and in Northeastern Greece. However, the case of Crete is highly uncertain, as precipitation and recharge in this area demonstrate exceptionally high variability and the coarse resolution of GRACE results does not allow for reliable estimates.

Dissolved helium, inert gases, radium and radon in groundwaters from the Altnabreac research site

International Nuclear Information System (INIS)

Andrews, J.N.; Kay, R.L.F.

1985-01-01

A groundwater geochemical study has been carried out at Altnabreac, Cenithness, Scotland, to investigate the feasibility of disposal of high-level radioactive wastes in crystalline rock. A groundwater flow model was constructed for sampling a section at depths up to 300 m. Measurements of inert gases dissolved in groundwaters are used, with parallel measurements of 14 C, tritium, oxygen and hydrogen isotopes to infer groundwater ages and residence times. (UK)

Environmental tracers as indicators of groundwater flow and evolution in a fractured rock aquifer, Clare Valley, South Australia

International Nuclear Information System (INIS)

Love, A.J.; Cook, P.G.; Herczeg, A.L.; Simmons, C.T.

1999-01-01

Environmental tracers, chemistry and hydraulic data have been used to develop a conceptual model for groundwater flow in a fractured rock aquifer, at Clare, South Australia. In the upper 36 m there is relatively high horizontal flow, closely spaced fractures and large apertures. Below 36 m, horizontal flow rates are less and apertures become smaller. A sub horizontal fracture at 36 m separates the upper system from flow systems below. There is minimum vertical connection of groundwater above and below 36 m as indicated by low hydraulic conductivity and a steep 14 C concentration gradient. The observed linear trends in chemistry and isotope data are a result of mixing between old saline water and relatively younger fresh water. Greater mixing has occurred in the upper 36 m, with the amount of mixing diminishing with depth. We propose that this mixing is a recent process that has been triggered as a result of increased recharge to the system since the clearing of native vegetation approximately 100 years ago. Increased recharge of lower salinity water has resulted in the establishment of concentration gradients between the matrix and the fractures. This has resulted in diffusion of relatively immobile water in the matrix into relatively fast moving water in the fractures. Greater flushing has occurred in the upper 36 m due greater fracture density and larger apertures and higher horizontal flow rates. (author)

PROSPECTIVE 180S04 INDICATOR FOR IDENTIFYING ELEVATED ARSENIC RELEASE AREAS IN GROUNDWATER: GOOSE RIVER AND NORTHPORT WATERSHEDS, MAINE

Science.gov (United States)

Naturally-occurring arsenic is the most abundant source of As to groundwater in this nation. In Maine the perfect arsenic storm exists for drinking water supplies since over 70% of homeowners depend on groundwater wells. Most of these wells are developed in granites with ubiquito...

The behavior of U- and Th-series nuclides in groundwater

Science.gov (United States)

Porcelli, D.; Swarzenski, P.W.

2003-01-01

Groundwater has long been an active area of research driven by its importance both as a societal resource and as a component in the global hydrological cycle. Key issues in groundwater research include inferring rates of transport of chemical constituents, determining the ages of groundwater, and tracing water masses using chemical fingerprints. While information on the trace elements pertinent to these topics can be obtained from aquifer tests using experimentally introduced tracers, and from laboratory experiments on aquifer materials, these studies are necessarily limited in time and space. Regional studies of aquifers can focus on greater scales and time periods, but must contend with greater complexities and variations. In this regard, the isotopic systematics of the naturally occurring radionuclides in the U- and Th- decay series have been invaluable in investigating aquifer behavior of U, Th, and Ra. These nuclides are present in all groundwaters and are each represented by several isotopes with very different half-lives, so that processes occurring over a range of time-scales can be studied (Table 1⇓). Within the host aquifer minerals, the radionuclides in each decay series are generally expected to be in secular equilibrium and so have equal activities (see Bourdon et al. 2003). In contrast, these nuclides exhibit strong relative fractionations within the surrounding groundwaters that reflect contrasting behavior during release into the water and during interaction with the surrounding host aquifer rocks. Radionuclide data can be used, within the framework of models of the processes involved, to obtain quantitative assessments of radionuclide release from aquifer rocks and groundwater migration rates. The isotopic variations that are generated also have the potential for providing fingerprints for groundwaters from specific aquifer environments, and have even been explored as a means for calculating groundwater ages.

Future research needs involving pathogens in groundwater

Science.gov (United States)

Bradford, Scott A.; Harvey, Ronald W.

2017-01-01

Contamination of groundwater by enteric pathogens has commonly been associated with disease outbreaks. Proper management and treatment of pathogen sources are important prerequisites for preventing groundwater contamination. However, non-point sources of pathogen contamination are frequently difficult to identify, and existing approaches for pathogen detection are costly and only provide semi-quantitative information. Microbial indicators that are readily quantified often do not correlate with the presence of pathogens. Pathogens of emerging concern and increasing detections of antibiotic resistance among bacterial pathogens in groundwater are topics of growing concern. Adequate removal of pathogens during soil passage is therefore critical for safe groundwater extraction. Processes that enhance pathogen transport (e.g., high velocity zones and preferential flow) and diminish pathogen removal (e.g., reversible retention and enhanced survival) are of special concern because they increase the risk of groundwater contamination, but are still incompletely understood. Improved theory and modeling tools are needed to analyze experimental data, test hypotheses, understand coupled processes and controlling mechanisms, predict spatial and/or temporal variability in model parameters and uncertainty in pathogen concentrations, assess risk, and develop mitigation and best management approaches to protect groundwater.

Future research needs involving pathogens in groundwater

Science.gov (United States)

Bradford, Scott A.; Harvey, Ronald W.

2017-06-01

Contamination of groundwater by enteric pathogens has commonly been associated with disease outbreaks. Proper management and treatment of pathogen sources are important prerequisites for preventing groundwater contamination. However, non-point sources of pathogen contamination are frequently difficult to identify, and existing approaches for pathogen detection are costly and only provide semi-quantitative information. Microbial indicators that are readily quantified often do not correlate with the presence of pathogens. Pathogens of emerging concern and increasing detections of antibiotic resistance among bacterial pathogens in groundwater are topics of growing concern. Adequate removal of pathogens during soil passage is therefore critical for safe groundwater extraction. Processes that enhance pathogen transport (e.g., high velocity zones and preferential flow) and diminish pathogen removal (e.g., reversible retention and enhanced survival) are of special concern because they increase the risk of groundwater contamination, but are still incompletely understood. Improved theory and modeling tools are needed to analyze experimental data, test hypotheses, understand coupled processes and controlling mechanisms, predict spatial and/or temporal variability in model parameters and uncertainty in pathogen concentrations, assess risk, and develop mitigation and best management approaches to protect groundwater.

Influence of seawater intrusion on microbial communities in groundwater.

Science.gov (United States)

Unno, Tatsuya; Kim, Jungman; Kim, Yumi; Nguyen, Son G; Guevarra, Robin B; Kim, Gee Pyo; Lee, Ji-Hoon; Sadowsky, Michael J

2015-11-01

Groundwater is the sole source of potable water on Jeju Island in the Republic of (South) Korea. Groundwater is also used for irrigation and industrial purposes, and it is severely impacted by seawater intrusion in coastal areas. Consequently, monitoring the intrusion of seawater into groundwater on Jeju is very important for health and environmental reasons. A number of studies have used hydrological models to predict the deterioration of groundwater quality caused by seawater intrusion. However, there is conflicting evidence of intrusion due to complicated environmental influences on groundwater quality. Here we investigated the use of next generation sequencing (NGS)-based microbial community analysis as a way to monitor groundwater quality and detect seawater intrusion. Pristine groundwater, groundwater from three coastal areas, and seawater were compared. Analysis of the distribution of bacterial species clearly indicated that the high and low salinity groundwater differed significantly with respect to microbial composition. While members of the family Parvularculaceae were only identified in high salinity water samples, a greater percentage of the phylum Actinobacteria was predominantly observed in pristine groundwater. In addition, we identified 48 shared operational taxonomic units (OTUs) with seawater, among which the high salinity groundwater sample shared a greater number of bacterial species with seawater (6.7%). In contrast, other groundwater samples shared less than 0.5%. Our results suggest that NGS-based microbial community analysis of groundwater may be a useful tool for monitoring groundwater quality and detect seawater intrusion. This technology may also provide additional insights in understanding hydrological dynamics. Copyright © 2015 Elsevier B.V. All rights reserved.

Groundwater vulnerability mapping in Guadalajara aquifers system (Western Mexico)

Science.gov (United States)

Rizo-Decelis, L. David; Marín, Ana I.; Andreo, Bartolomé

2016-04-01

Groundwater vulnerability mapping is a practical tool to implement strategies for land-use planning and sustainable socioeconomic development coherent with groundwater protection. The objective of vulnerability mapping is to identify the most vulnerable zones of catchment areas and to provide criteria for protecting the groundwater used for drinking water supply. The delineation of protection zones in fractured aquifers is a challenging task due to the heterogeneity and anisotropy of hydraulic conductivities, which makes difficult prediction of groundwater flow organization and flow velocities. Different methods of intrinsic groundwater vulnerability mapping were applied in the Atemajac-Toluquilla groundwater body, an aquifers system that covers around 1300 km2. The aquifer supplies the 30% of urban water resources of the metropolitan area of Guadalajara (Mexico), where over 4.6 million people reside. Study area is located in a complex neotectonic active volcanic region in the Santiago River Basin (Western Mexico), which influences the aquifer system underneath the city. Previous works have defined the flow dynamics and identified the origin of recharge. In addition, the mixture of fresh groundwater with hydrothermal and polluted waters have been estimated. Two main aquifers compose the multilayer system. The upper aquifer is unconfined and consists of sediments and pyroclastic materials. Recharge of this aquifer comes from rainwater and ascending vertical fluids from the lower aquifer. The lower aquifer consists of fractured basalts of Pliocene age. Formerly, the main water source has been the upper unit, which is a porous and unconsolidated unit, which acts as a semi-isotropic aquifer. Intense groundwater usage has resulted in lowering the water table in the upper aquifer. Therefore, the current groundwater extraction is carried out from the deeper aquifer and underlying bedrock units, where fracture flow predominates. Pollution indicators have been reported in

Integrating a Linear Signal Model with Groundwater and Rainfall time-series on the Characteristic Identification of Groundwater Systems

Science.gov (United States)

Chen, Yu-Wen; Wang, Yetmen; Chang, Liang-Cheng

2017-04-01

Groundwater resources play a vital role on regional supply. To avoid irreversible environmental impact such as land subsidence, the characteristic identification of groundwater system is crucial before sustainable management of groundwater resource. This study proposes a signal process approach to identify the character of groundwater systems based on long-time hydrologic observations include groundwater level and rainfall. The study process contains two steps. First, a linear signal model (LSM) is constructed and calibrated to simulate the variation of underground hydrology based on the time series of groundwater levels and rainfall. The mass balance equation of the proposed LSM contains three major terms contain net rate of horizontal exchange, rate of rainfall recharge and rate of pumpage and four parameters are required to calibrate. Because reliable records of pumpage is rare, the time-variant groundwater amplitudes of daily frequency (P ) calculated by STFT are assumed as linear indicators of puamage instead of pumpage records. Time series obtained from 39 observation wells and 50 rainfall stations in and around the study area, Pintung Plain, are paired for model construction. Second, the well-calibrated parameters of the linear signal model can be used to interpret the characteristic of groundwater system. For example, the rainfall recharge coefficient (γ) means the transform ratio between rainfall intention and groundwater level raise. The area around the observation well with higher γ means that the saturated zone here is easily affected by rainfall events and the material of unsaturated zone might be gravel or coarse sand with high infiltration ratio. Considering the spatial distribution of γ, the values of γ decrease from the upstream to the downstream of major rivers and also are correlated to the spatial distribution of grain size of surface soil. Via the time-series of groundwater levels and rainfall, the well-calibrated parameters of LSM have

Opportunity for peri-urban Perth groundwater trade

Science.gov (United States)

Gao, Lei; Connor, Jeff; Doble, Rebecca; Ali, Riasat; McFarlane, Don

2013-07-01

Groundwater trade is widely advocated for reallocating scarce groundwater resources between competing users, and managing over-allocated and declining aquifers. However, groundwater markets are still in their infancy, and the potential benefits and opportunities need investigation, particularly where there is a need to reduce the extraction from declining aquifers. This article evaluates economic impacts of reducing groundwater extraction for irrigation use in peri-urban Perth, Australia, where irrigation, a lake-based ecosystem, and public water supply are highly dependent on a declining groundwater resource. We present an assessment of market-based water trading approaches to reduce groundwater extraction with an economic model representing diversity in returns to groundwater use across a population of irrigators. The results indicate that potential economic costs of a proportional reduction in available groundwater for irrigation are 18-21% less if groundwater trade is possible. We also evaluate a water buyback from irrigation to provide public water supply as an alternative to new infrastructure. We find that buying back up to around 50% of current irrigation allocations could create new public water supply only at the cost of 0.32-0.39 million per GL, which is less than one fifth of the costs of new desalinisation or recycled water supply options (2-3 million per GL). We conclude that, with rapid development of computer and internet based trading platforms that allows fast, efficient and low cost multiple party trading, it is increasingly feasible to realise the economic potentials of market-based trade approaches for managing overexploited aquifers.

Radon as a hydrological indicator

Energy Technology Data Exchange (ETDEWEB)

Komae, Takami [National Research Inst. of Agricultural Engineering, Tsukuba, Ibaraki (Japan)

1997-02-01

The radon concentration in water is measured by a liquid scintillation method. After the radioactive equilibrium between radon and the daughter nuclides was attained, the radon concentration was determined by the liquid scintillation analyzer. {alpha}-ray from radon, then two {beta}- and two {alpha}-ray from the daughter nuclei group were released, so that 500% of the apparent counting efficiency was obtained. The detector limit is about 0.03 Bq/l, the low value, which corresponds to about 5.4x10{sup -15} ppm. By determining the radon concentration in groundwater, behavior of radon in hydrological process, the groundwater exchange caused by pumping and exchange between river water and groundwater were investigated. The water circulation analysis by means of radon indicator in the environment was shown. By using the large difference of radon concentration between in river water and in groundwater, arrival of injected water to the sampling point of groundwater was detected. (S.Y.)

Hydrogeochemistry of the groundwater in the Tarkwa area, Wasa west District of Ghana

International Nuclear Information System (INIS)

Yankey, R. K.

2008-06-01

The pH of the groundwater is acidic (4.3-6.7) and acidification of the groundwater is principally due to natural biogeochemical processes. Three main water types were delineated: Na-Cl (31.3%), Ca-Mg-HCO 3 (62.5%) and mixed type (6.3%) Major cation and anion concentrations dominance pattern observed in this study were generally in the order of Na > Ca > Mg > K and HCO 3 > CI > SO 4 and indicated partial cationic and anionic characteristics of fresh water. The chemistry of groundwater is controlled by mineral weathering, ion exchange and to some extent precipitation. Iron and manganese were the predominant trace elements in the groundwater and contributed substantially (93.1 %) to the metal load of the groundwater. The pollution index (HPI) for the groundwater came out to be 9.82; which is far below the critical value of 100 indicating that the groundwater is not critically contaminated. The anthropogenic influence on the groundwater is at present minimal. Water quality is good for the majority of the groundwater samples as the majority of samples were within the permissible drinking limits of World Health Organization (WHO, 1998). However the pH of the groundwater was disturbingly low. (au)

Geochemical modelling of groundwater evolution and residence time at the Kivetty site

Energy Technology Data Exchange (ETDEWEB)

Pitkaenen, P.; Luukkonen, A. [VTT Communities and Infrastructure, Espoo (Finland); Ruotsalainen, P. [Fintact Oy, Helsinki (Finland); Leino-Forsman, H.; Vuorinen, U. [VTT Chemical Technology, Espoo (Finland)

1998-12-01

groundwater are due to carbonate reactions: oxidising of organic carbon, and dissolution and precipitation of calcite. The carbonate reactions and slight hydrolysis of silicates stabilise the pH value at 8-9. In addition to aerobic oxidation of organic matter, oxidative dissolution of biotite seems to be an important oxygen consumer at shallow depth during recharge. The most important process controlling the redox state deeper in the bedrock was interpreted to be the microbially mediated sulphate reduction with simultaneous anaerobic respiration of organic carbon. This process buffers the redox level of about -200 - -300 mV depending on the pH. Even though the salinities of the groundwater samples and mass-transfer along flow paths remain low, the geochemical evolution was fully developed and has reached quite a stable thermodynamic state. The residence times of the groundwater samples cover the time span back to glaciation. Young ages seem to be limited to the upper part of bedrock, and any really dynamic natural flowpath with deep observed recently recharged water cannot be demonstrated. Deglacial or subglacial ages (over 9,700 years old at Kivetty) are typical below the 150-300m level in the bedrock. Subglacial waters are interpreted to derive from mixing of preglacial water and meltwater, the input of which is estimated to be about 20% at the most. Indications of elevated oxygen intrusion cannot be observed in groundwater having glacial signals. (orig.) 122 refs.

Geochemical modelling of groundwater evolution and residence time at the Kivetty site

International Nuclear Information System (INIS)

Pitkaenen, P.; Luukkonen, A.; Ruotsalainen, P.; Leino-Forsman, H.; Vuorinen, U.

1998-12-01

groundwater are due to carbonate reactions: oxidising of organic carbon, and dissolution and precipitation of calcite. The carbonate reactions and slight hydrolysis of silicates stabilise the pH value at 8-9. In addition to aerobic oxidation of organic matter, oxidative dissolution of biotite seems to be an important oxygen consumer at shallow depth during recharge. The most important process controlling the redox state deeper in the bedrock was interpreted to be the microbially mediated sulphate reduction with simultaneous anaerobic respiration of organic carbon. This process buffers the redox level of about -200 - -300 mV depending on the pH. Even though the salinities of the groundwater samples and mass-transfer along flow paths remain low, the geochemical evolution was fully developed and has reached quite a stable thermodynamic state. The residence times of the groundwater samples cover the time span back to glaciation. Young ages seem to be limited to the upper part of bedrock, and any really dynamic natural flowpath with deep observed recently recharged water cannot be demonstrated. Deglacial or subglacial ages (over 9,700 years old at Kivetty) are typical below the 150-300m level in the bedrock. Subglacial waters are interpreted to derive from mixing of preglacial water and meltwater, the input of which is estimated to be about 20% at the most. Indications of elevated oxygen intrusion cannot be observed in groundwater having glacial signals. (orig.)

Determinants of Shallow Groundwater As Variability in Bangladesh

Science.gov (United States)

Radloff, K. A.; Zheng, Y.; Stute, M.; Rahman, M.; Mihajlov, I.; Siu, H.; Huq, M.; Choudhury, I.; Ahmed, K.; van Geen, A.

2010-12-01

where the As content of groundwater is variable is particularly important. The size of the pool of As adsorbed on the sediment also indicates that current attempts to flush Bangladeshi aquifers “clean” through increased pumping will likely be ineffective. 1. BBS/UNICEF. Bangladesh: Multiple Indicator Cluster Survey, 2009. (Dhaka, Bangladesh, 2009).

Impacts of swine manure pits on groundwater quality

International Nuclear Information System (INIS)

Krapac, I.G.; Dey, W.S.; Roy, W.R.; Smyth, C.A.; Storment, E.; Sargent, S.L.; Steele, J.D.

2002-01-01

New information is presented on impacts on groundwater by manure storage in deep ground pits. - Manure deep-pits are commonly used to store manure at confined animal feeding operations. However, previous to this study little information had been collected on the impacts of deep-pits on groundwater quality to provide science-based guidance in formulating regulations and waste management strategies that address risks to human health and the environment. Groundwater quality has been monitored since January 1999 at two hog finishing facilities in Illinois that use deep-pit systems for manure storage. Groundwater samples were collected on a monthly basis and analyzed for inorganic and bacteriological constituent concentrations. The two sites are located in areas with geologic environments representing different vulnerabilities for local groundwater contamination. One site is underlain by more than 6 m of clayey silt, and 7-36 m of shale. Concentrations of chloride, ammonium, phosphate, and potassium indicated that local groundwater quality had not been significantly impacted by pit leakage from this facility. Nitrate concentrations were elevated near the pit, often exceeding the 10 mg N/l drinking water standard. Isotopic nitrate signatures suggested that the nitrate was likely derived from soil organic matter and fertilizer applied to adjacent crop fields. At the other site, sandstone is located 4.6-6.1 m below land surface. Chloride concentrations and δ 15 N and δ 18 O values of dissolved nitrate indicated that this facility may have limited and localized impacts on groundwater. Other constituents, including ammonia, potassium, phosphate, and sodium were generally at or less than background concentrations. Trace- and heavy-metal concentrations in groundwater samples collected from both facilities were at concentrations less than drinking water standards. The concentration of inorganic constituents in the groundwater would not likely impact human health. Fecal

Impacts of swine manure pits on groundwater quality

Energy Technology Data Exchange (ETDEWEB)

Krapac, I.G.; Dey, W.S.; Roy, W.R.; Smyth, C.A.; Storment, E.; Sargent, S.L.; Steele, J.D

2002-12-01

New information is presented on impacts on groundwater by manure storage in deep ground pits. - Manure deep-pits are commonly used to store manure at confined animal feeding operations. However, previous to this study little information had been collected on the impacts of deep-pits on groundwater quality to provide science-based guidance in formulating regulations and waste management strategies that address risks to human health and the environment. Groundwater quality has been monitored since January 1999 at two hog finishing facilities in Illinois that use deep-pit systems for manure storage. Groundwater samples were collected on a monthly basis and analyzed for inorganic and bacteriological constituent concentrations. The two sites are located in areas with geologic environments representing different vulnerabilities for local groundwater contamination. One site is underlain by more than 6 m of clayey silt, and 7-36 m of shale. Concentrations of chloride, ammonium, phosphate, and potassium indicated that local groundwater quality had not been significantly impacted by pit leakage from this facility. Nitrate concentrations were elevated near the pit, often exceeding the 10 mg N/l drinking water standard. Isotopic nitrate signatures suggested that the nitrate was likely derived from soil organic matter and fertilizer applied to adjacent crop fields. At the other site, sandstone is located 4.6-6.1 m below land surface. Chloride concentrations and {delta}{sup 15}N and {delta}{sup 18}O values of dissolved nitrate indicated that this facility may have limited and localized impacts on groundwater. Other constituents, including ammonia, potassium, phosphate, and sodium were generally at or less than background concentrations. Trace- and heavy-metal concentrations in groundwater samples collected from both facilities were at concentrations less than drinking water standards. The concentration of inorganic constituents in the groundwater would not likely impact human

RCRA groundwater data analysis protocol for the Hanford Site, Washington

International Nuclear Information System (INIS)

Chou, C.J.; Jackson, R.L.

1992-04-01

The Resource Conservation and Recovery Act of 1976 (RCRA) groundwater monitoring program currently involves site-specific monitoring of 20 facilities on the Hanford Site in southeastern Washington. The RCRA groundwater monitoring program has collected abundant data on groundwater quality. These data are used to assess the impact of a facility on groundwater quality or whether remediation efforts under RCRA corrective action programs are effective. Both evaluations rely on statistical analysis of groundwater monitoring data. The need for information on groundwater quality by regulators and environmental managers makes statistical analysis of monitoring data an important part of RCRA groundwater monitoring programs. The complexity of groundwater monitoring programs and variabilities (spatial, temporal, and analytical) exhibited in groundwater quality variables indicate the need for a data analysis protocol to guide statistical analysis. A data analysis protocol was developed from the perspective of addressing regulatory requirements, data quality, and management information needs. This data analysis protocol contains four elements: data handling methods; graphical evaluation techniques; statistical tests for trend, central tendency, and excursion analysis; and reporting procedures for presenting results to users

Groundwater Pollution Sources Apportionment in the Ghaen Plain, Iran

Directory of Open Access Journals (Sweden)

Mohammad Reza Vesali Naseh

2018-01-01

Full Text Available Although Iran’s Ghaen Plain provides saffron to much of the world, no regional groundwater quality (GQ assessment has yet been undertaken. Given the region’s potential for saltwater intrusion and heavy metal contamination, it is important to assess the GQ and determine its main probable source of pollution (MPSP. Such knowledge would allow for informed mitigation or elimination of the potential adverse health effects of this groundwater through its use as drinking water, or indirectly as a result of the consumption of groundwater-irrigated crops. Total dissolved solids, sodium, and chloride in the water of the majority of 16 wells sampled within the region exceeded World Health Organization and Iranian permissible standards for drinking water. The groundwater proved to only be suitable for irrigating salt tolerant crops under good drainage conditions. Due to the precipitation of calcium carbonate in the water supply facilities, the water from all wells was deemed unsuitable for industrial purposes. Heavy metal pollution and contamination indices showed no groundwater contamination. Analysis of ionic ratios and the application of principal components analysis indicated the MPSP to be saltwater intrusion, with the geology subtending the plain, and to a lesser extent, anthropogenic activities. Reducing groundwater withdrawals, particularly those for agricultural production by using high performance irrigation methods could reduce saltwater intrusion and improve GQ in the Ghaen Plain.

Groundwater Pollution Sources Apportionment in the Ghaen Plain, Iran.

Science.gov (United States)

Vesali Naseh, Mohammad Reza; Noori, Roohollah; Berndtsson, Ronny; Adamowski, Jan; Sadatipour, Elaheh

2018-01-22

Although Iran's Ghaen Plain provides saffron to much of the world, no regional groundwater quality (GQ) assessment has yet been undertaken. Given the region's potential for saltwater intrusion and heavy metal contamination, it is important to assess the GQ and determine its main probable source of pollution (MPSP). Such knowledge would allow for informed mitigation or elimination of the potential adverse health effects of this groundwater through its use as drinking water, or indirectly as a result of the consumption of groundwater-irrigated crops. Total dissolved solids, sodium, and chloride in the water of the majority of 16 wells sampled within the region exceeded World Health Organization and Iranian permissible standards for drinking water. The groundwater proved to only be suitable for irrigating salt tolerant crops under good drainage conditions. Due to the precipitation of calcium carbonate in the water supply facilities, the water from all wells was deemed unsuitable for industrial purposes. Heavy metal pollution and contamination indices showed no groundwater contamination. Analysis of ionic ratios and the application of principal components analysis indicated the MPSP to be saltwater intrusion, with the geology subtending the plain, and to a lesser extent, anthropogenic activities. Reducing groundwater withdrawals, particularly those for agricultural production by using high performance irrigation methods could reduce saltwater intrusion and improve GQ in the Ghaen Plain.

Influence of geochemical processes on hydrochemistry and irrigation suitability of groundwater in part of semi-arid Deccan Plateau, India

Science.gov (United States)

Vasu, Duraisamy; Singh, Surendra Kumar; Tiwary, Pramod; Sahu, Nisha; Ray, Sanjay Kumar; Butte, Pravin; Duraisami, Veppangadu Perumal

2017-11-01

Major ion geochemistry was used to characterise the chemical composition of groundwater in part of semi-arid Deccan plateau region to understand the geochemical evolution and to evaluate the groundwater quality for irrigation. The study area comprises peninsular gneissic complex of Archean age, younger granites and basaltic alluvium. Forty-nine georeferenced groundwater samples were collected and analysed for major ions. The ionic sequence based on relative proportions was Na+ > Mg2+ > Ca2+ > SO4 2- > HCO3 - > Cl- > CO3 2- > BO3 3- > K+. High Na+, Mg2+ and Ca2+ were generally associated with basaltic alluvial formation, whereas pH, electrical conductivity (EC) and total dissolved salts (TDS) were found to be higher in granitic formations. High standard deviation for EC, TDS, Na+, Ca2+ and Mg2+ indicated the dispersion of ionic concentration throughout the study area. Four major hydrochemical facies identified were Na-Mg-HCO3 type; Mg-Na-HCO3 type; Na-Mg-Ca-SO4 and Mg-Na-Ca-SO4 type. The graphical plots indicated that the groundwater chemistry was influenced by rock-water interaction, silicate weathering and reverse ion exchange. Sodium-dominated waters might have impeded the hydraulic properties of soils as a result of long-term irrigation.

Groundwater recharge and agricultural contamination

Science.gov (United States)

Böhlke, J.K.

2002-01-01

Agriculture has had direct and indirect effects on the rates and compositions of groundwater recharge and aquifer biogeochemistry. Direct effects include dissolution and transport of excess quantities of fertilizers and associated materials and hydrologic alterations related to irrigation and drainage. Some indirect effects include changes in water–rock reactions in soils and aquifers caused by increased concentrations of dissolved oxidants, protons, and major ions. Agricultural activities have directly or indirectly affected the concentrations of a large number of inorganic chemicals in groundwater, for example NO3–, N2, Cl, SO42–, H+, P, C, K, Mg, Ca, Sr, Ba, Ra, and As, as well as a wide variety of pesticides and other organic compounds. For reactive contaminants like NO3–, a combination of chemical, isotopic, and environmental-tracer analytical approaches might be required to resolve changing inputs from subsequent alterations as causes of concentration gradients in groundwater. Groundwater records derived from multi-component hydrostratigraphic data can be used to quantify recharge rates and residence times of water and dissolved contaminants, document past variations in recharging contaminant loads, and identify natural contaminant-remediation processes. These data indicate that many of the world's surficial aquifers contain transient records of changing agricultural contamination from the last half of the 20th century. The transient agricultural groundwater signal has important implications for long-term trends and spatial heterogeneity in discharge.

Hydrogeologic framework and occurrence, movement, and chemical characterization of groundwater in Dixie Valley, west-central Nevada

Science.gov (United States)

Huntington, Jena M.; Garcia, C. Amanda; Rosen, Michael R.

2014-01-01

Dixie Valley, a primarily undeveloped basin in west-central Nevada, is being considered for groundwater exportation. Proposed pumping would occur from the basin-fill aquifer. In response to proposed exportation, the U.S. Geological Survey, in cooperation with the Bureau of Reclamation and Churchill County, conducted a study to improve the understanding of groundwater resources in Dixie Valley. The objective of this report is to characterize the hydrogeologic framework, the occurrence and movement of groundwater, the general water quality of the basin-fill aquifer, and the potential mixing between basin-fill and geothermal aquifers in Dixie Valley. Various types of geologic, hydrologic, and geochemical data were compiled from previous studies and collected in support of this study. Hydrogeologic units in Dixie Valley were defined to characterize rocks and sediments with similar lithologies and hydraulic properties influencing groundwater flow. Hydraulic properties of the basin-fill deposits were characterized by transmissivity estimated from aquifer tests and specific-capacity tests. Groundwater-level measurements and hydrogeologic-unit data were combined to create a potentiometric surface map and to characterize groundwater occurrence and movement. Subsurface inflow from adjacent valleys into Dixie Valley through the basin-fill aquifer was evaluated using hydraulic gradients and Darcy flux computations. The chemical signature and groundwater quality of the Dixie Valley basin-fill aquifer, and potential mixing between basin-fill and geothermal aquifers, were evaluated using chemical data collected from wells and springs during the current study and from previous investigations. Dixie Valley is the terminus of the Dixie Valley flow system, which includes Pleasant, Jersey, Fairview, Stingaree, Cowkick, and Eastgate Valleys. The freshwater aquifer in the study area is composed of unconsolidated basin-fill deposits of Quaternary age. The basin-fill hydrogeologic unit

Environmental Tritium (3H) and hydrochemical investigations to evaluate groundwater in Varahi and Markandeya river basins, Karnataka, India

International Nuclear Information System (INIS)

Ravikumar, P.; Somashekar, R.K.

2011-01-01

The present study aimed at assessing the activity of natural radionuclides ( 3 H) and hydrochemical parameters (viz., pH, EC, F - , NO 3 - , Cl - , Ca 2+ , Mg 2+ ) in the groundwater used for domestic and irrigation purposes in the Varahi and Markandeya river basins to understand the levels of hydrochemical parameters in terms of the relative age(s) of the groundwater contained within the study area. The recorded environmental 3 H content in Varahi and Markandeya river basins varied from 1.95 ± 0.25 T.U. to 11.35 ± 0.44 T.U. and 1.49 ± 0.75 T.U. to 9.17 ± 1.13 T.U. respectively. Majority of the samples in Varahi (93.34%) and Markandeya (93.75%) river basins being pre-modern water with modern recharge, significantly influenced by precipitation and river inflowing/sea water intrusion. The EC-Tritium and Tritium-Fluoride plots confirmed the existence of higher total dissolved solids (SEC > 500 μS/cm) and high fluoride (MAC > 1.5 mg/L) in groundwater of Markandeya river basin, attributed to relatively longer residence time of groundwater interacting with rock formations and vice versa in case of Varahi river basin. The tritium-EC and tritium-chloride plots indicated shallow and deep circulating groundwater types in Markandeya river basin and only shallow circulating groundwater type in Varahi river basin. Increasing Mg relative to Ca with decreasing tritium indicated the influence of incongruent dissolution of a dolomite phase. The samples with high nitrate (MAC > 45 mg/L) are waters that are actually mixtures of fresh water (containing very high nitrate, possibly from agricultural fertilizers) and older 'unpolluted' waters (containing low nitrate levels), strongly influenced by surface source. - Research highlights: → It is evident that majority of the samples in Varahi (93.34%) and Markandeya (93.75%) river basins exhibited radioactive decay (1-8 T.U.) having a mixture of pre-modern (viz., old water) water with modern (viz., new water) recharge, significantly

Risk-based prioritization method for the classification of groundwater pesticide pollution from agricultural regions.

Science.gov (United States)

Yang, Yu; Lian, Xin-Ying; Jiang, Yong-Hai; Xi, Bei-Dou; He, Xiao-Song

2017-11-01

Agricultural regions are a significant source of groundwater pesticide pollution. To ensure that agricultural regions with a significantly high risk of groundwater pesticide contamination are properly managed, a risk-based ranking method related to groundwater pesticide contamination is needed. In the present paper, a risk-based prioritization method for the classification of groundwater pesticide pollution from agricultural regions was established. The method encompasses 3 phases, including indicator selection, characterization, and classification. In the risk ranking index system employed here, 17 indicators involving the physicochemical properties, environmental behavior characteristics, pesticide application methods, and inherent vulnerability of groundwater in the agricultural region were selected. The boundary of each indicator was determined using K-means cluster analysis based on a survey of a typical agricultural region and the physical and chemical properties of 300 typical pesticides. The total risk characterization was calculated by multiplying the risk value of each indicator, which could effectively avoid the subjectivity of index weight calculation and identify the main factors associated with the risk. The results indicated that the risk for groundwater pesticide contamination from agriculture in a region could be ranked into 4 classes from low to high risk. This method was applied to an agricultural region in Jiangsu Province, China, and it showed that this region had a relatively high risk for groundwater contamination from pesticides, and that the pesticide application method was the primary factor contributing to the relatively high risk. The risk ranking method was determined to be feasible, valid, and able to provide reference data related to the risk management of groundwater pesticide pollution from agricultural regions. Integr Environ Assess Manag 2017;13:1052-1059. © 2017 SETAC. © 2017 SETAC.

Regional analysis of groundwater phosphate concentrations under acidic sandy soils: Edaphic factors and water table strongly mediate the soil P-groundwater P relation.

Science.gov (United States)

Mabilde, Lisa; De Neve, Stefaan; Sleutel, Steven

2017-12-01

Historic long-term P application to sandy soils in NW-Europe has resulted in abundant sorption, saturation and eventually leaching of P from soil to the groundwater. Although many studies recognize the control of site-specific factors like soil texture and phosphate saturation degree (PSD), the regional-scaled relevance of effects exerted by single factors controlling P leaching is unclear. Very large observational datasets of soil and groundwater P content are furthermore required to reveal indirect controls of soil traits through mediating soil variables. We explored co-variation of phreatic groundwater orthophosphate (o-P) concentration and soil factors in sandy soils in Flanders, Belgium. Correlation analyses were complemented with an exploratory model derived using 'path analysis'. Data of oxalate-extractable Al, Fe, P and pH KCl , phosphate sorption capacity (PSC) and PSD in three depth layers (0-30, 30-60, 60-90 cm), topsoil SOC, % clay and groundwater depth (fluctuation) were interpolated to predict soil properties on exact locations of a very extensive net of groundwater monitoring wells. The mean PSD was only poorly correlated to groundwater o-P concentration, indicating the overriding control of other factors in the transport of P to the groundwater. A significant (P soil pH and groundwater table depth than by PSD indicates the likely oversimplification of the latter index to measure the long-term potential risk of P leaching. Accounting for controls on leaching not included in PSD via an alternative index, however, seems problematic as in Flanders for example groundwater o-P turned out to be higher in finer textured soils or soils with higher pedogenic Fe content, probably because of their lower pedogenic Al content and higher soil pH. Path analysis of extensive soil and groundwater datasets seems a viable way to identify prime local determinants of soil P leaching and could be further on used for 'ground-truthing' more complex P-migration simulation

Groundwater quota versus tiered groundwater pricing : two cases of groundwater management in north-west China

NARCIS (Netherlands)

Aarnoudse, Eefje; Qu, Wei; Bluemling, B.; Herzfeld, Thomas

2017-01-01

Difficulties in monitoring groundwater extraction cause groundwater regulations to fail worldwide. In two counties in north-west China local water authorities have installed smart card machines to monitor and regulate farmers’ groundwater use. Data from a household survey and in-depth interviews are

Hydrogeologic setting and simulation of groundwater flow near the Canterbury and Leadville Mine Drainage Tunnels, Leadville, Colorado

Science.gov (United States)

Wellman, Tristan P.; Paschke, Suzanne S.; Minsley, Burke; Dupree, Jean A.

2011-01-01

63 percent of the total water budget, respectively). The largest contributions to the water budget were groundwater entering from the upper reaches of the watershed and the hydrologic interaction of the groundwater with the East Fork Arkansas River. Potentiometric surface maps of the simulated model results were generated for depths of 50, 100, and 250 m. The surfaces revealed a positive trend in hydraulic head with land-surface altitude and evidence of increased control on fluid movement by the fault network structure at progressively greater depths in the aquifer. Results of advective particle-tracking simulations indicate that the sets of simulated flow paths for the Canterbury Tunnel and the Leadville Mine Drainage Tunnel were mutually exclusive of one another, which also suggested that no major hydraulic connection was present between the tunnels. Particle-tracking simulations also revealed that although the fault network generally restricted groundwater movement locally, hydrologic conditions were such that groundwater did cross the fault network at many locations. This cross-fault movement indicates that the fault network controls regional groundwater flow to some degree but is not a complete barrier to flow. The cumulative distributions of adjusted age results for the watershed indicate that approximately 30 percent of the flow pathways transmit groundwater that was younger than 68 years old (post-1941) and that about 70 percent of the flow pathways transmit old groundwater. The particle-tracking results are consistent with the apparent ages and mixing ratios developed from the chlorofluorocarbon and tritium results. The model simulations also indicate that approximately 50 percent of the groundwater flowing through the study area was less than 200 years old and about 50 percent of the groundwater flowing through the study area is old water stored in low-permeability geologic units and fault blocks. As a final examination of model response, the conductance

Comparison of a Conceptual Groundwater Model and Physically Based Groundwater Mode

Science.gov (United States)

Yang, J.; Zammit, C.; Griffiths, J.; Moore, C.; Woods, R. A.

2017-12-01

Groundwater is a vital resource for human activities including agricultural practice and urban water demand. Hydrologic modelling is an important way to study groundwater recharge, movement and discharge, and its response to both human activity and climate change. To understand the groundwater hydrologic processes nationally in New Zealand, we have developed a conceptually based groundwater flow model, which is fully integrated into a national surface-water model (TopNet), and able to simulate groundwater recharge, movement, and interaction with surface water. To demonstrate the capability of this groundwater model (TopNet-GW), we applied the model to an irrigated area with water shortage and pollution problems in the upper Ruamahanga catchment in Great Wellington Region, New Zealand, and compared its performance with a physically-based groundwater model (MODFLOW). The comparison includes river flow at flow gauging sites, and interaction between groundwater and river. Results showed that the TopNet-GW produced similar flow and groundwater interaction patterns as the MODFLOW model, but took less computation time. This shows the conceptually-based groundwater model has the potential to simulate national groundwater process, and could be used as a surrogate for the more physically based model.

Spatial variation in background groundwater geochemistry of the Gurinai Wetland, Gobi Desert, Inner Mongolia

Science.gov (United States)

Gu, Weizu; Peters, N.E.

1995-01-01

Age dating of groundwater from several hand-dug wells in the Gurinai Wetland of the Badajilin-Gobi Desert, north-central China, indicated a continuum from present to 7625??155 years B.P. Water age correlates with concentration for some constituents. In general, concentrations of Fe, Cr, Se and Sr increase with increasing age, whereas Ca, Br, Zn and Rb decrease. Compared to concentration ranges reported for freshwaters, several constituents were much more concentrated including Na, Cl, Mg, Br and Th, and many others extended the upper concentration limit including Sr, Mo, Rb, Cr, U, Se, Nb and Ce. For Th, the maximum observed concentration extends the previously summarized maximum by more than an order of magnitude.

Quarterly RCRA Groundwater Monitoring Data for the Period April Through June 2006

Energy Technology Data Exchange (ETDEWEB)

Hartman, Mary J.

2006-11-01

This report provides information about RCRA groundwater monitoring for the period April through June 2006. Seventeen RCRA sites were sampled during the reporting quarter. Sampled sites include seven monitored under groundwater indicator evaluation (''detection'') programs, eight monitored under groundwater quality assessment programs, and two monitored under final-status programs.

85Kr dating of groundwater

International Nuclear Information System (INIS)

Rozanski, K.; Florkowski, T.

1978-01-01

The possibility of 85 Kr dating of groundwater is being investigated. The method of gas extraction from 200 to 300 litres of water sample has been developed. The Argon and Krypton mixture, separated from the gas extracted from water, was counted in a 1.5 ml volume proportional counter. The amount of krypton gas in the counter was determined by mass spectrometry. A number of surface and groundwater samples were analyzed indicating an 85 Kr concentration ranging from present atmospheric content (river water) to zero values. 85 Kr 'blank value' was determined to be about 5 per cent of present 85 Kr atmospheric content. For groundwater samples, the mean residence time in the system was calculated assuming the exponential model and known 85 Kr input function. Further improvement of the method should bring higher yield of krypton separation and lower volume of water necessary for analysis. (orig.) [de

Groundwater and Terrestrial Water Storage

Science.gov (United States)

Rodell, Matthew; Chambers, Don P.; Famiglietti, James S.

2011-01-01

Most people think of groundwater as a resource, but it is also a useful indicator of climate variability and human impacts on the environment. Groundwater storage varies slowly relative to other non-frozen components of the water cycle, encapsulating long period variations and trends in surface meteorology. On seasonal to interannual timescales, groundwater is as dynamic as soil moisture, and it has been shown that groundwater storage changes have contributed to sea level variations. Groundwater monitoring well measurements are too sporadic and poorly assembled outside of the United States and a few other nations to permit direct global assessment of groundwater variability. However, observational estimates of terrestrial water storage (TWS) variations from the GRACE satellites largely represent groundwater storage variations on an interannual basis, save for high latitude/altitude (dominated by snow and ice) and wet tropical (surface water) regions. A figure maps changes in mean annual TWS from 2009 to 2010, based on GRACE, reflecting hydroclimatic conditions in 2010. Severe droughts impacted Russia and the Amazon, and drier than normal weather also affected the Indochinese peninsula, parts of central and southern Africa, and western Australia. Groundwater depletion continued in northern India, while heavy rains in California helped to replenish aquifers that have been depleted by drought and withdrawals for irrigation, though they are still below normal levels. Droughts in northern Argentina and western China similarly abated. Wet weather raised aquifer levels broadly across western Europe. Rains in eastern Australia caused flooding to the north and helped to mitigate a decade long drought in the south. Significant reductions in TWS seen in the coast of Alaska and the Patagonian Andes represent ongoing glacier melt, not groundwater depletion. Figures plot time series of zonal mean and global GRACE derived non-seasonal TWS anomalies (deviation from the mean of

The combined use of chemical and isotopic information to model the effects of stormwater infiltration on groundwater quality in an urban fractured rock aquifer, Auckland, New Zealand

International Nuclear Information System (INIS)

Rosen, M.R.; Hong, Y.S.; Reeves, R.; Sheppard, D.; Roberts, K.; Viljevac, Z.; Smaill, A.

2002-01-01

Disposal of storm water in the Mt Eden area of Auckland, New Zealand, is via 'soak holes' drilled directly into the top of fractured basalt. Although this method of disposal has been used for at least 60 years, its sustainability with respect to groundwater quality has not been addressed. The groundwater has relatively low concentrations of dissolved heavy metals, although total metals are higher suggesting that the metals are bound to mobile particulates within the aquifer. PAH concentrations are also low in the aquifer, although sampling after rainfall events show small increases in PAH. Tritium measurements of the groundwater showed that all of the groundwater south of Chamberlin Park is less than 2 years old. This area has many soak holes. The data suggest that infiltration is very rapid and occurs throughout the area almost simultaneously after rainfall events. One well north of Chamberlin Park, where soak holes are absent has an age of 47 years ± 2 years. The groundwater here is low in dissolved oxygen and appears to be slow moving. CFC measurements indicate that all wells sampled south of Chamberlin Park are contaminated by excess CFCs. However, this result indicates rapid recharge from the surface via storm water. The same well north of Chamberlin Park that was dated using tritium, also has a CFC age of approximately 30 years. Thus, CFC dating may be useful in urban areas that are separated from atmospheric contamination by confining beds or slow circulation. A Kohonen self-organising feature maps (KSOFM) neural network was used to analyse the effect on storm water infiltration on groundwater quality, and determine the inter-relationship of the groundwater quality variables. The model shows that where the land use type is industrial or residential with many soak holes, there is a strong correlation of increased concentrations of heavy metals and storm water infiltration. (author)

Evaluation of Groundwater Quality Indices of Mashhad Plain using Geostatistics and GIS Techniques

Directory of Open Access Journals (Sweden)

Mohammadreza Yazdani

2017-11-01

The outcomes illustrate that the qualitative conditions of underground water resources, particularly in TDS and TH are in the inappropriate condition in the southern parts of Mashhad. It is related to the high population density and the lack of proper drainage. It is needed to restrict over exploitation of groundwater resources in critical hot spots, along with defining alternative safe water sources for urban consumption.

Simulation of Groundwater Flow, Denpasar-Tabanan Groundwater Basin, Bali Province

Directory of Open Access Journals (Sweden)

Heryadi Tirtomihardjo

2014-06-01

Full Text Available DOI: 10.17014/ijog.v6i3.123Due to the complex structure of the aquifer systems and its hydrogeological units related with the space in which groundwater occurs, groundwater flows were calculated in three-dimensional method (3D Calculation. The geometrical descritization and iteration procedures were based on an integrated finite difference method. In this paper, all figures and graphs represent the results of the calibrated model. Hence, the model results were simulated by using the actual input data which were calibrated during the simulation runs. Groundwater flow simulation of the model area of the Denpasar-Tabanan Groundwater Basin (Denpasar-Tabanan GB comprises steady state run, transient runs using groundwater abstraction in the period of 1989 (Qabs-1989 and period of 2009 (Qabs-2009, and prognosis run as well. Simulation results show, in general, the differences of calculated groundwater heads and observed groundwater heads at steady and transient states (Qabs-1989 and Qabs-2009 are relatively small. So, the groundwater heads situation simulated by the prognosis run (scenario Qabs-2012 are considerably valid and can properly be used for controlling the plan of groundwater utilization in Denpasar-Tabanan GB.

Tracing groundwater with low-level detections of halogenated VOCs in a fractured carbonate-rock aquifer, Leetown Science Center, West Virginia, USA

Science.gov (United States)

Plummer, Niel; Sibrell, Philip L.; Casile, Gerolamo C.; Busenberg, Eurybiades; Hunt, Andrew G.; Schlosser, Peter

2013-01-01

Measurements of low-level concentrations of halogenated volatile organic compounds (VOCs) and estimates of groundwater age interpreted from 3H/3He and SF6 data have led to an improved understanding of groundwater flow, water sources, and transit times in a karstic, fractured, carbonate-rock aquifer at the Leetown Science Center (LSC), West Virginia. The sum of the concentrations of a set of 16 predominant halogenated VOCs (TDVOC) determined by gas chromatography with electron-capture detector (GC–ECD) exceeded that possible for air–water equilibrium in 34 of the 47 samples (median TDVOC of 24,800 pg kg−1), indicating that nearly all the water sampled in the vicinity of the LSC has been affected by addition of halogenated VOCs from non-atmospheric source(s). Leakage from a landfill that was closed and sealed nearly 20 a prior to sampling was recognized and traced to areas east of the LSC using low-level detection of tetrachloroethene (PCE), methyl chloride (MeCl), methyl chloroform (MC), dichlorodifluoromethane (CFC-12), and cis-1,2-dichloroethene (cis-1,2-DCE). Chloroform (CHLF) was the predominant VOC in water from domestic wells surrounding the LSC, and was elevated in groundwater in and near the Fish Health Laboratory at the LSC, where a leak of chlorinated water occurred prior to 2006. The low-level concentrations of halogenated VOCs did not exceed human or aquatic-life health criteria, and were useful in providing an awareness of the intrinsic susceptibility of the fractured karstic groundwater system at the LSC to non-atmospheric anthropogenic inputs. The 3H/3He groundwater ages of spring discharge from the carbonate rocks showed transient behavior, with ages averaging about 2 a in 2004 following a wet climatic period (2003–2004), and ages in the range of 4–7 a in periods of more average precipitation (2008–2009). The SF6 and CFC-12 data indicate older water (model ages of 10s of years or more) in the low-permeability shale of the Martinsburg

Anisotropic analysis for seismic sensitivity of groundwater monitoring wells

Science.gov (United States)

Pan, Y.; Hsu, K.

2011-12-01

Taiwan is located at the boundaries of Eurasian Plate and the Philippine Sea Plate. The movement of plate causes crustal uplift and lateral deformation to lead frequent earthquakes in the vicinity of Taiwan. The change of groundwater level trigged by earthquake has been observed and studied in Taiwan for many years. The change of groundwater may appear in oscillation and step changes. The former is caused by seismic waves. The latter is caused by the volumetric strain and reflects the strain status. Since the setting of groundwater monitoring well is easier and cheaper than the setting of strain gauge, the groundwater measurement may be used as a indication of stress. This research proposes the concept of seismic sensitivity of groundwater monitoring well and apply to DonHer station in Taiwan. Geostatistical method is used to analysis the anisotropy of seismic sensitivity. GIS is used to map the sensitive area of the existing groundwater monitoring well.

100-D Ponds groundwater quality assessment

International Nuclear Information System (INIS)

Hartman, M.J.

1996-01-01

The 100-D Ponds facility is regulated under the Resource Conservation and Recovery Act of 1976. The pH of groundwater in a downgradient well is statistically different than local background, triggering an assessment of groundwater contamination under 40 CFR 265.93. Results of a similar assessment, conducted in 1993, show that the elevated pH is caused by the presence of alkaline ash sediments beneath the ponds, which are not part of the RCRA unit. The 100-D Ponds should remain in indicator evaluation monitoring

Natural 222Rn and 220Rn indicate the impact of the Water–Sediment Regulation Scheme (WSRS) on submarine groundwater discharge in the Yellow River estuary, China

International Nuclear Information System (INIS)

Xu, Bochao; Xia, Dong; Burnett, William C.; Dimova, Natasha T.; Wang, Houjie; Zhang, Longjun; Gao, Maosheng; Jiang, Xueyan; Yu, Zhigang

2014-01-01

Highlights: • 220 Rn and 222 Rn were combined to locate intensive SGD sites. • Influence of WSRS to SGD was found for the first time. • SGD was a dominant nutrient pathway in the Yellow River estuary. - Abstract: Submarine groundwater discharge (SGD) in estuaries brings important influences to coastal ecosystems. In this study, we observed significant SGD in the Yellow River estuary, including a fresh component, during the Water–Sediment Regulation Scheme (WSRS) period. We used the 222 Rn and 220 Rn isotope pair to locate sites of significant SGD within the study area. Three apparent SGD locations were found during a non-WSRS period, one of which became much more pronounced, according to the remarkably elevated radon levels, during the WSRS. Increased river discharge (from 245 m 3 s −1 to 3560 m 3 s −1 ) and the elevated river water level (from 11 m to 13 m) during the WSRS led to a higher hydraulic head, enhancing groundwater discharge in the estuary. Our results suggest that high river discharge (>3000 m 3 s −1 ) might be necessary for elevated fresh submarine groundwater discharging (FSGD). Vertical profiles of salinity, DO and turbidity anomalies along the benthic boundary layer also indicated significant FSGD in the estuary during the WSRS. Nutrient concentrations had positive correlations with 222 Rn during a 24-h observation, which indicates that SGD is a dominant nutrient pathway in this area

Natural organics in groundwaters and their potential effect on contaminant transport in granitic rock

International Nuclear Information System (INIS)

Vilks, P.; Bachinski, D.B.; Richer, D.

1996-07-01

Naturally occurring organics in groundwaters of the Whiteshell Research Area (WRA) of southern Manitoba and of the Atikokan Research Area of northwestern Ontario were investigated to assess their potential role in radionuclide transport within granite fractures of the Canadian Shield. A survey of dissolved organic carbon (DOC) concentrations, carried out to determine the variability in the organic content of these groundwaters, showed average concentrations in WRA deep groundwaters of 0.8 ± 0.1 mg/L for Fracture Zone 2, 0.8 ± 0.4 mg/L for near-vertical fractures, and 2.3 ± 0.8 mg/L for deeper saline groundwater. Surface waters and near-surface groundwaters had significantly higher DOC with 29.2 ± 0.6 mg/L in streams from the East Swamp. The DOC consisted mainly of hydrophilic neutral compounds 60 to 75%, and hydrophobic and hydrophilic acids 23 to 39%, along with very small amounts of hydrophobic bases and neutrals, and hydrophilic bases. The average complexing capacity of natural organics in WRA deep groundwaters was calculated to be 6.7 x 10 -6 eq/L. The ability of these organics to complex radionuclides was tested using conditional stability constants from the literature for humic complex formation with trivalent, tetravalent, pentavalent and hexavalent actinides. The chemistries of Np(V) and U(VI) were predicted to be dominated by inorganic complexes and not significantly affected by organics. Accurate predictions for AM(III) and Th(IV) could not be made since the literature contains a wide range in values of stability constants for humic complexes with these elements. Surface waters and near-surface groundwaters in many areas of the Canadian Shield contain enough humics to complex a significant fraction of dissolved actinides. Radiocarbon ages of humics from WRA groundwater varied between 3600 and 6200 years before present, indicating that a component of humic substances in deep groundwaters must originate from near-surface waters. 54 refs., 15 tabs., 5

Elucidating hydraulic fracturing impacts on groundwater quality using a regional geospatial statistical modeling approach

Energy Technology Data Exchange (ETDEWEB)

Burton, Taylour G., E-mail: tgburton@uh.edu [Civil and Environmental Engineering, University of Houston, W455 Engineering Bldg. 2, Houston, TX 77204-4003 (United States); Rifai, Hanadi S., E-mail: rifai@uh.edu [Civil and Environmental Engineering, University of Houston, N138 Engineering Bldg. 1, Houston, TX 77204-4003 (United States); Hildenbrand, Zacariah L., E-mail: zac@informenv.com [Inform Environmental, LLC, Dallas, TX 75206 (United States); Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019 (United States); Carlton, Doug D., E-mail: doug.carlton@mavs.uta.edu [Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019 (United States); Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX (United States); Fontenot, Brian E., E-mail: brian.fonteno@mavs.uta.edu [Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019 (United States); Schug, Kevin A., E-mail: kschug@uta.edu [Collaborative Laboratories for Environmental Analysis and Remediation, University of Texas at Arlington, Arlington, TX 76019 (United States); Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX (United States)

2016-03-01

Hydraulic fracturing operations have been viewed as the cause of certain environmental issues including groundwater contamination. The potential for hydraulic fracturing to induce contaminant pathways in groundwater is not well understood since gas wells are completed while isolating the water table and the gas-bearing reservoirs lay thousands of feet below the water table. Recent studies have attributed ground water contamination to poor well construction and leaks in the wellbore annulus due to ruptured wellbore casings. In this paper, a geospatial model of the Barnett Shale region was created using ArcGIS. The model was used for spatial analysis of groundwater quality data in order to determine if regional variations in groundwater quality, as indicated by various groundwater constituent concentrations, may be associated with the presence of hydraulically fractured gas wells in the region. The Barnett Shale reservoir pressure, completions data, and fracture treatment data were evaluated as predictors of groundwater quality change. Results indicated that elevated concentrations of certain groundwater constituents are likely related to natural gas production in the study area and that beryllium, in this formation, could be used as an indicator variable for evaluating fracturing impacts on regional groundwater quality. Results also indicated that gas well density and formation pressures correlate to change in regional water quality whereas proximity to gas wells, by itself, does not. The results also provided indirect evidence supporting the possibility that micro annular fissures serve as a pathway transporting fluids and chemicals from the fractured wellbore to the overlying groundwater aquifers. - Graphical abstract: A relative increase in beryllium concentrations in groundwater for the Barnett Shale region from 2001 to 2011 was visually correlated with the locations of gas wells in the region that have been hydraulically fractured over the same time period

Elucidating hydraulic fracturing impacts on groundwater quality using a regional geospatial statistical modeling approach

International Nuclear Information System (INIS)

Burton, Taylour G.; Rifai, Hanadi S.; Hildenbrand, Zacariah L.; Carlton, Doug D.; Fontenot, Brian E.; Schug, Kevin A.

2016-01-01

Hydraulic fracturing operations have been viewed as the cause of certain environmental issues including groundwater contamination. The potential for hydraulic fracturing to induce contaminant pathways in groundwater is not well understood since gas wells are completed while isolating the water table and the gas-bearing reservoirs lay thousands of feet below the water table. Recent studies have attributed ground water contamination to poor well construction and leaks in the wellbore annulus due to ruptured wellbore casings. In this paper, a geospatial model of the Barnett Shale region was created using ArcGIS. The model was used for spatial analysis of groundwater quality data in order to determine if regional variations in groundwater quality, as indicated by various groundwater constituent concentrations, may be associated with the presence of hydraulically fractured gas wells in the region. The Barnett Shale reservoir pressure, completions data, and fracture treatment data were evaluated as predictors of groundwater quality change. Results indicated that elevated concentrations of certain groundwater constituents are likely related to natural gas production in the study area and that beryllium, in this formation, could be used as an indicator variable for evaluating fracturing impacts on regional groundwater quality. Results also indicated that gas well density and formation pressures correlate to change in regional water quality whereas proximity to gas wells, by itself, does not. The results also provided indirect evidence supporting the possibility that micro annular fissures serve as a pathway transporting fluids and chemicals from the fractured wellbore to the overlying groundwater aquifers. - Graphical abstract: A relative increase in beryllium concentrations in groundwater for the Barnett Shale region from 2001 to 2011 was visually correlated with the locations of gas wells in the region that have been hydraulically fractured over the same time period

Shallow bedrock limits groundwater seepage-based headwater climate refugia

Science.gov (United States)

Briggs, Martin A.; Lane, John W.; Snyder, Craig D.; White, Eric A.; Johnson, Zachary; Nelms, David L.; Hitt, Nathaniel P.

2018-01-01

Groundwater/surface-water exchanges in streams are inexorably linked to adjacent aquifer dynamics. As surface-water temperatures continue to increase with climate warming, refugia created by groundwater connectivity is expected to enable cold water fish species to survive. The shallow alluvial aquifers that source groundwater seepage to headwater streams, however, may also be sensitive to seasonal and long-term air temperature dynamics. Depth to bedrock can directly influence shallow aquifer flow and thermal sensitivity, but is typically ill-defined along the stream corridor in steep mountain catchments. We employ rapid, cost-effective passive seismic measurements to evaluate the variable thickness of the shallow colluvial and alluvial aquifer sediments along a headwater stream supporting cold water-dependent brook trout (Salvelinus fontinalis) in Shenandoah National Park, VA, USA. Using a mean depth to bedrock of 2.6 m, numerical models predicted strong sensitivity of shallow aquifer temperature to the downward propagation of surface heat. The annual temperature dynamics (annual signal amplitude attenuation and phase shift) of potential seepage sourced from the shallow modeled aquifer were compared to several years of paired observed stream and air temperature records. Annual stream water temperature patterns were found to lag local air temperature by ∼8–19 d along the stream corridor, indicating that thermal exchange between the stream and shallow groundwater is spatially variable. Locations with greater annual signal phase lag were also associated with locally increased amplitude attenuation, further suggestion of year-round buffering of channel water temperature by groundwater seepage. Numerical models of shallow groundwater temperature that incorporate regional expected climate warming trends indicate that the summer cooling capacity of this groundwater seepage will be reduced over time, and lower-elevation stream sections may no longer serve as larger

Nitrate pollution of groundwater; all right…, but nothing else?

International Nuclear Information System (INIS)

Menció, Anna; Mas-Pla, Josep; Otero, Neus; Regàs, Oriol; Boy-Roura, Mercè

2016-01-01

Contamination from agricultural sources and, in particular, nitrate pollution, is one of the main concerns in groundwater management. However, this type of pollution entails the entrance of other substances into the aquifer, as well as it may promote other processes. In this study, we deal with hydrochemical and isotopic analysis of groundwater samples from four distinct zones in Catalonia (NE Spain), which include 5 different aquifer types, to investigate the influence of fertilization on the overall hydrochemical composition of groundwater. Results indicate that intense fertilizer application, causing high nitrate pollution in aquifers, also homogenize the contents of the major dissolved ions (i.e.; Cl - , SO 4 2- , Ca 2+ , Na + , K + , and Mg 2+ ). Thus, when groundwater in igneous and sedimentary aquifers is compared, significant differences are observed under natural conditions for Cl - , Na + and Ca 2+ (with p-values ranging from < 0.001 to 0.038), and when high nitrate concentrations occur, these differences are reduced (most p-values ranged between 0.054 and 0.978). Moreover, positive linear relationships between nitrate and some ions are found indicating the magnitude of the fertilization impact on groundwater hydrochemistry (with R 2 values of 0.490, 0.609 and 0.470, for SO 4 2- , Ca 2+ and Cl - , respectively). Nevertheless, the increasing concentration of specific ions is not only attributed to agricultural pollution, but to their enhancing effect upon the biogeochemical processes that control water-rock interactions. Such results raise awareness that these processes should be evaluated in advance in order to assess an adequate groundwater resources management. - Highlights: • The effects of nitrate pollution have been evaluated in five different aquifer types • Statistical and multivariate analyses are used to identify groundwater changes • Agricultural pollution modifies groundwater conditions and geochemical processes • Manure application

Hydrogeochemistry and isotope geochemistry of Velenje Basin groundwater

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Tjaša Kanduč

2016-08-01

Full Text Available The geochemical and isotopic composition of groundwater in the Velenje Basin, Slovenia, was investigated between the years 2014 to 2015 to identify the geochemical processes in the major aquifers (Pliocene and Triassic and the water–rock interactions. Thirty-eight samples of groundwater were taken from the aquifers, 19 in the mine and 19 from the surface. Groundwater in the Triassic aquifer is dominated by HCO3–, Ca2+ and Mg2+ with δ13C DIC values in the range from -19.3 to -2.8 ‰, indicating degradation of soil organic matter and dissolution of carbonate minerals. In contrast, groundwater in the Pliocene aquifers is enriched in Mg2+, Na+, Ca2+, K+, and Si, and has high alkalinity, with δ13CDIC values in the range of -14.4 to +4.6 ‰. Based on the δ13CDIC values in all the aquifers (Pliocene and Triassic, both processes inflence the dissolution of carbonate minerals and dissolution of organic matter and in the Pliocene aquifers, methanogenesis as well. Based on Principal Component Analysis (PCA, and on geochemical and isotopic data we conclude that the following types of groundwater in Velenje Basin are present: Triassic aquifers with higher pH and lower conductivity and chloride, Pliocene, Pliocene 1 and Pliocene 2 aquifers with lower pH and higher conductivity and chloride contents, and Pliocene 3 and Pliocene 2, 3 aquifers with the highest pH values and lowest conductivities and chloride contents. 87Sr/86Sr tracer was used for the fist time in Slovenia to determine geochemical processes (dissolution of silicate versus carbonate fraction in Velenje Basin groundwater of different aquifers dewatering Pliocene and Triassic strata. 87Sr/86Sr values range from 0.70820 to 0.71056 in groundwater of Pliocene aquifers and from 0.70808 to 0.70910 in groundwater of the Triassic aquifer. This indicates that dissolution of the carbonate fraction prevails in both aquifers, while in Pliocene aquifers, an additional silicate weathering prevails with

A new four-step hierarchy method for combined assessment of groundwater quality and pollution.

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Zhu, Henghua; Ren, Xiaohua; Liu, Zhizheng

2017-12-28

A new four-step hierarchy method was constructed and applied to evaluate the groundwater quality and pollution of the Dagujia River Basin. The assessment index system is divided into four types: field test indices, common inorganic chemical indices, inorganic toxicology indices, and trace organic indices. Background values of common inorganic chemical indices and inorganic toxicology indices were estimated with the cumulative-probability curve method, and the results showed that the background values of Mg 2+ (51.1 mg L -1 ), total hardness (TH) (509.4 mg L -1 ), and NO 3 - (182.4 mg L -1 ) are all higher than the corresponding grade III values of Quality Standard for Groundwater, indicating that they were poor indicators and therefore were not included in the groundwater quality assessment. The quality assessment results displayed that the field test indices were mainly classified as grade II, accounting for 60.87% of wells sampled. The indices of common inorganic chemical and inorganic toxicology were both mostly in the range of grade III, whereas the trace organic indices were predominantly classified as grade I. The variabilities and excess ratios of the indices were also calculated and evaluated. Spatial distributions showed that the groundwater with poor quality indices was mainly located in the northeast of the basin, which was well-connected with seawater intrusion. Additionally, the pollution assessment revealed that groundwater in well 44 was classified as "moderately polluted," wells 5 and 8 were "lightly polluted," and other wells were classified as "unpolluted."

Appraisal of groundwater resources of Ziarat valley using isotopic techniques

International Nuclear Information System (INIS)

Ahmad, M.; Akram, W.; Tasneem, M.A.; Rafique, M.

2009-07-01

Study of water resources of Ziarat Valley was carried out to investigate groundwater recharge mechanism and effectiveness of delay action dams. Samples of precipitation (rain, snow), dam reservoirs and groundwater (dug wells, tube wells, karezes, springs) were periodically collected from different locations and analyzed for environmental isotopes (/sup 2/H, /sup 3/H, /sup 18/O, /sup 34/S). The data indicate that rainfall and snow samples show wide ranges of delta /sup 2/H and delta /sup 18/O. However, the mean values for these isotopes are -6.4% and -37% respectively. Mean tritium value of rain is 9TU. Delta /sup 2/H and delta /sup 18/O values of dam reservoirs range from -6.7 to +4.9% and -42 to +30% respectively. Average isotopic indices of all the karezes are close to each other. Mean delta /sup 18/O and delta /sup 2/H values of Sandaman Tangi, Faran Tangi and Quaid springs vary from -6.3 to -6% and -40 to -31%. Tritium concentration of Sandaman Tangi and Faran Tangi springs (7 TU) is less than Quaid spring (11TU). Ranges of mean delta /sup 18/O and delta /sup 2/H values of all the groundwater samples (wells, karezes, springs) are -6.6 to -2.2% and -40 to -16% respectively. Delta /sup 34/S values of dissolved sulphates in groundwater vary from -8.5 to -0.8%. In /sup 18/O vs. /sup 2/H plot, most of the groundwater samples lie close to LMWL indicating the meteoric origin. Reservoir water in Pechi Dam shows highly enriched isotopic values in summer due to evaporation. Such enriched values are not depicted by the groundwater in the wells and karezes downstream of the dam. This implies that there is no significant recharge from this dam. Similar is the case of Mana Dam. Vouch Ghouski Dam has some contribution towards groundwater recharge while Warchoom Dam is much effective and makes significant contribution. Results of tritium dating suggest that residence time of groundwater is quite short (only few years). (author)

Environmental isotope study related to groundwater age, flow system and saline water origin in Quaternary aquifers of North China Plain

International Nuclear Information System (INIS)

Zhang Zhigan; Payne, B.R.

1988-01-01

An isotopic hydrology section across the North China Plain has been studied to investigate problems of groundwater age, flow system and saline water origin in a semi-arid pre-mountain artesian basin. Two local and one regional flow system along the section have been recognized. Turnover time of water for alluvial fan, shallow and regional systems are estimated to be the order of 10 2 , 10 3 , and 10 4 years respectively. Specific flow rates for the three systems have been calculated. Only less than 5 percent of flow from alluvial fan is drained by the regional flow system and the rest, in natural conditions, discharges at surface in the front edge of an alluvial fan and forms a groundwater discharge belt at a good distance away from the mountain foot. Developed in the alluvial plain and coastal plain areas the shallow flow system embraces a series of small local systems. Groundwater in these systems appears to be the salt carrier during continental salinization. It washes salt out of the recharge area and deep-occurred strata by circulating and carries it up to the surface in lowland areas. Consequently, in parallel with salinization at surface a desalinization process occurs at depth, which provides an additional explanation for the existing thick deep fresh water zone in most arid and semi-arid regions, where continental salting process is in progress. (author). 6 refs, 8 figs, 4 tabs

Groundwater monitoring plan for the Hanford Site 200 Area Treated Effluent Disposal Facility

International Nuclear Information System (INIS)

DB Barnett

2000-01-01

Seven years of groundwater monitoring at the 200 Area Treated Effluent Disposal Facility (TEDF) have shown that the uppermost aquifer beneath the facility is unaffected by TEDF effluent. Effluent discharges have been well below permitted and expected volumes. Groundwater mounding from TEDF operations predicted by various models has not been observed, and waterlevels in TEDF wells have continued declining with the dissipation of the nearby B Pond System groundwater mound. Analytical results for constituents with enforcement limits indicate that concentrations of all these are below Practical Quantitation Limits, and some have produced no detections. Likewise, other constituents on the permit-required list have produced results that are mostly below sitewide background. Comprehensive geochemical analyses of groundwater from TEDF wells has shown that most constituents are below background levels as calculated by two Hanford Site-wide studies. Additionally, major ion proportions and anomalously low tritium activities suggest that groundwater in the aquifer beneath the TEDF has been sequestered from influences of adjoining portions of the aquifer and any discharge activities. This inference is supported by recent hydrogeologic investigations which indicate an extremely slow rate of groundwater movement beneath the TEDF. Detailed evaluation of TEDF-area hydrogeology and groundwater geochemistry indicate that additional points of compliance for groundwater monitoring would be ineffective for this facility, and would produce ambiguous results. Therefore, the current groundwater monitoring well network is retained for continued monitoring. A quarterly frequency of sampling and analysis is continued for all three TEDF wells. The constituents list is refined to include only those parameters key to discerning subtle changes in groundwater chemistry, those useful in detecting general groundwater quality changes from upgradient sources, or those retained for comparison with end

Soil and groundwater remediation using dual-phase extraction technology

International Nuclear Information System (INIS)

Miller, A.W.; Gan, D.R.

1995-01-01

A gasoline underground storage tank (UST) was formerly used to fuel vehicles for a hospital in Madison, Wisconsin. Elevated concentrations of gasoline range organics (GRO) were observed in soils and groundwater at the site during the tank removal and a subsequent site investigation. Based on the extent of soil and groundwater contamination, a dual-phase extraction technology was selected as the most cost effective alternative to remediate the site. The dual-phase extraction system includes one extraction well functioning both as a soil vapor extraction (SVE) and groundwater recovery well. After six months of operation, samples collected from the groundwater monitoring wells indicated that the groundwater has been cleaned up to levels below the Wisconsin preventative action limits. The dual-phase extraction system effectively remediated the site in a short period of time, saving both operation and maintenance costs and overall project cost

Simulation of groundwater flow and interaction of groundwater and surface water on the Lac du Flambeau Reservation, Wisconsin

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Juckem, Paul F.; Fienen, Michael N.; Hunt, Randall J.

2014-01-01

The Lac du Flambeau Band of Lake Superior Chippewa and Indian Health Service are interested in improving the understanding of groundwater flow and groundwater/surface-water interaction on the Lac du Flambeau Reservation (Reservation) in southwest Vilas County and southeast Iron County, Wisconsin, with particular interest in an understanding of the potential for contamination of groundwater supply wells and the fate of wastewater that is infiltrated from treatment lagoons on the Reservation. This report describes the construction, calibration, and application of a regional groundwater flow model used to simulate the shallow groundwater flow system of the Reservation and water-quality results for groundwater and surface-water samples collected near a system of waste-water-treatment lagoons. Groundwater flows through a permeable glacial aquifer that ranges in thickness from 60 to more than 200 feet (ft). Seepage and drainage lakes are common in the area and influence groundwater flow patterns on the Reservation. A two-dimensional, steady-state analytic element groundwater flow model was constructed using the program GFLOW. The model was calibrated by matching target water levels and stream base flows through the use of the parameter-estimation program, PEST. Simulated results illustrate that groundwater flow within most of the Reservation is toward the Bear River and the chain of lakes that feed the Bear River. Results of analyses of groundwater and surface-water samples collected downgradient from the wastewater infiltration lagoons show elevated levels of ammonia and dissolved phosphorus. In addition, wastewater indicator chemicals detected in three downgradient wells and a small downgradient stream indicate that infiltrated wastewater is moving southwest of the lagoons toward Moss Lake. Potential effects of extended wet and dry periods (within historical ranges) were evaluated by adjusting precipitation and groundwater recharge in the model and comparing the

Pleistocene paleo-groundwater as a pristine fresh water resource in southern Germany--evidence from stable and radiogenic isotopes.

Science.gov (United States)

van Geldern, Robert; Baier, Alfons; Subert, Hannah L; Kowol, Sigrid; Balk, Laura; Barth, Johannes A C

2014-10-15

Shallow groundwater aquifers are often influenced by anthropogenic contaminants or increased nutrient levels. In contrast, deeper aquifers hold potentially pristine paleo-waters that are not influenced by modern recharge. They thus represent important water resources, but their recharge history is often unknown. In this study groundwater from two aquifers in southern Germany were analyzed for their hydrogen and oxygen stable isotope compositions. One sampling campaign targeted the upper aquifer that is actively recharged by modern precipitation, whereas the second campaign sampled the confined, deep Benkersandstein aquifer. The groundwater samples from both aquifers were compared to the local meteoric water line to investigate sources and conditions of groundwater recharge. In addition, the deep groundwater was dated by tritium and radiocarbon analyses. Stable and radiogenic isotope data indicate that the deep-aquifer groundwater was not part of the hydrological water cycle in the recent human history. The results show that the groundwater is older than ~20,000 years and most likely originates from isotopically depleted melt waters of the Pleistocene ice age. Today, the use of this aquifer is strictly regulated to preserve the pristine water. Clear identification of such non-renewable paleo-waters by means of isotope geochemistry will help local water authorities to enact and justify measures for conservation of these valuable resources for future generations in the context of a sustainable water management. Copyright © 2014 Elsevier B.V. All rights reserved.

Understanding groundwater dynamics on barrier islands using geochronological data: An example from North Stradbroke Island, South-east Queensland

Science.gov (United States)

Hofmann, Harald; Newborn, Dean; Cartwright, Ian

2017-04-01

Freshwater lenses underneath barrier islands are dynamic systems affected by changing sea levels and groundwater use. They are vulnerable to contamination and over-abstraction. Residence times of fresh groundwater in barrier islands are poorly understood and have mostly been assessed by modelling approaches and estimates without fundamental validation with geochronological data. Assessing residence time and recharge rates will improve significantly our understanding of hydrological processes of coastal environments that will in turn allow us to make informed decisions on groundwater use and environmental protection. This project focused on groundwater recharge rates and residence times of the fresh water aquifer system of North Stradbroke Island, south-east Queensland, Australia. Groundwater bores, wetlands and submarine groundwater discharge points in the tidal areas (wonky holes) were sampled along a transect across the island and were analysed for major ion chemistry and stable isotopes (δ2H, δ18O, δ13C) in combination with 3H and 14C analysis. Calculated 3H using a 95% exponential-piston flow model and 14C ages range from 12 to >100 years and modern to 3770 years, respectively, indicating a highly heterogeneous aquifer system with mixing from low and high conductive areas. The major ion chemistry in combination with stable and radiogenic isotopes suggests that a significant groundwater component derives from the fractured rock basement and older sedimentary formations underlying the sand dunes of the island. The results help refining the conceptual and numerical groundwater flow model for North Stradbroke island in this particular case but also demonstrate the possible complexity of barrier island hydrogeology.

Residence time, chemical and isotopic analysis of nitrate in the groundwater and surface water of a small agricultural watershed in the Coastal Plain, Bucks Branch, Sussex County, Delaware

Science.gov (United States)

Clune, John W.; Denver, Judith M.

2012-01-01

Nitrate is a common contaminant in groundwater and surface water throughout the Nation, and water-resource managers need more detailed small-scale watershed research to guide conservation efforts aimed at improving water quality. Concentrations of nitrate in Bucks Branch are among the highest in the state of Delaware and a scientific investigation was performed to provide water-quality information to assist with the management of agriculture and water resources. A combination of major-ion chemistry, nitrogen isotopic composition and age-dating techniques was used to estimate the residence time and provide a chemical and isotopic analysis of nitrate in the groundwater in the surficial aquifer of the Bucks Branch watershed in Sussex County, Delaware. The land use was more than 90 percent agricultural and most nitrogen inputs were from manure and fertilizer. The apparent median age of sampled groundwater is 18 years and the estimated residence time of groundwater contributing to the streamflow for the entire Bucks Branch watershed at the outlet is approximately 19 years. Concentrations of nitrate exceeded the U.S. Environmental Protection Agency drinking-water standard of 10 milligrams per liter (as nitrogen) in 60 percent of groundwater samples and 42 percent of surface-water samples. The overall geochemistry in the Bucks Branch watershed indicates that agriculture is the predominant source of nitrate contamination and the observed patterns in major-ion chemistry are similar to those observed in other studies on the Mid-Atlantic Coastal Plain. The pattern of enrichment in nitrogen and oxygen isotopes (δ15N and δ18O) of nitrate in groundwater and surface water indicates there is some loss of nitrate through denitrification, but this process is not sufficient to remove all of the nitrate from groundwater discharging to streams, and concentrations of nitrate in streams remain elevated.

Incorporating Social Determinants into a Groundwater Risk Framework

Science.gov (United States)

Simpson, M.; Allen, D. M.; Journeay, M.; Korteling, B.

2009-12-01

The remediation of polluted groundwater is often very costly, therefore water managers utilize various proactive measures, such as wellhead protection planning, to prevent contamination events. With limited available resources, it is essential to prioritize where these measures are introduced; systematic and integrated methodologies of assessing risk to groundwater can be utilized for this prioritization. To quantify the resistance of the physical system to pollution, Aquifer Vulnerability is commonly mapped for the area of interest. This information is useful for focusing monitoring efforts and identifying data gaps, but is a relative measure of contaminant risk. To more accurately assess the probability of contamination, an inventory of hazards can be integrated with intrinsic vulnerability of the physical system. This Threat indicator links land-use with chemicals and quantifies the risk based on the toxicity and environmental fate of these substances. Local knowledge of the quantity stored and likelihood of release can be utilized to further assess these threats. Both of these steps form part of an existing frameworks for assessing risk to groundwater. In this study, a groundwater risk framework is developed and tested in two study areas; Pender Island and the Lower Fraser Valley in British Columbia, Canada. Enhancements of a basic groundwater risk framework include not only incorporating points sources such as septic systems, landfills and fuel storage, but also various social determinants of risk. These social determinants include the Resistance of a community, which represents the planning and protection initiatives designed to safeguard the resource. These include items such as land-use planning that consider groundwater vulnerability and best management practices enforced by local governments. The ability to recover following an event is the Capacity of a community; indicators include the presence or absence of spill response plans, treatment systems or an

Regional variability of nitrate fluxes in the unsaturated zone and groundwater, Wisconsin, USA

Science.gov (United States)

Green, Christopher T.; Liao, Lixia; Nolan, Bernard T.; Juckem, Paul F.; Shope, Christopher L.; Tesoriero, Anthony J.; Jurgens, Bryant

2018-01-01

Process-based modeling of regional NO3− fluxes to groundwater is critical for understanding and managing water quality, but the complexity of NO3− reactive transport processes make implementation a challenge. This study introduces a regional vertical flux method (VFM) for efficient estimation of reactive transport of NO3− in the vadose zone and groundwater. The regional VFM was applied to 443 well samples in central-eastern Wisconsin. Chemical measurements included O2, NO3−, N2 from denitrification, and atmospheric tracers of groundwater age including carbon-14, chlorofluorocarbons, tritium, and tritiogenic helium. VFM results were consistent with observed chemistry, and calibrated parameters were in-line with estimates from previous studies. Results indicated that (1) unsaturated zone travel times were a substantial portion of the transit time to wells and streams (2) since 1945 fractions of applied N leached to groundwater have increased for manure-N, possibly due to increased injection of liquid manure, and decreased for fertilizer-N, and (3) under current practices and conditions, approximately 60% of the shallow aquifer will eventually be affected by downward migration of NO3−, with denitrification protecting the remaining 40%. Recharge variability strongly affected the unsaturated zone lag times and the eventual depth of the NO3− front. Principal components regression demonstrated that VFM parameters and predictions were significantly correlated with hydrogeochemical landscape features. The diverse and sometimes conflicting aspects of N management (e.g. limiting N volatilization versus limiting N losses to groundwater) warrant continued development of large-scale holistic strategies to manage water quality and quantity.

Regional Variability of Nitrate Fluxes in the Unsaturated Zone and Groundwater, Wisconsin, USA

Science.gov (United States)

Green, Christopher T.; Liao, Lixia; Nolan, Bernard T.; Juckem, Paul F.; Shope, Christopher L.; Tesoriero, Anthony J.; Jurgens, Bryant C.

2018-01-01

Process-based modeling of regional NO3- fluxes to groundwater is critical for understanding and managing water quality, but the complexity of NO3- reactive transport processes makes implementation a challenge. This study introduces a regional vertical flux method (VFM) for efficient estimation of reactive transport of NO3- in the vadose zone and groundwater. The regional VFM was applied to 443 well samples in central-eastern Wisconsin. Chemical measurements included O2, NO3-, N2 from denitrification, and atmospheric tracers of groundwater age including carbon-14, chlorofluorocarbons, tritium, and tritiogenic helium. VFM results were consistent with observed chemistry, and calibrated parameters were in-line with estimates from previous studies. Results indicated that (1) unsaturated zone travel times were a substantial portion of the transit time to wells and streams, (2) since 1945 fractions of applied N leached to groundwater have increased for manure-N, possibly due to increased injection of liquid manure, and decreased for fertilizer-N, and (3) under current practices and conditions, approximately 60% of the shallow aquifer will eventually be affected by downward migration of NO3-, with denitrification protecting the remaining 40%. Recharge variability strongly affected the unsaturated zone lag times and the eventual depth of the NO3- front. Principal components regression demonstrated that VFM parameters and predictions were significantly correlated with hydrogeochemical landscape features. The diverse and sometimes conflicting aspects of N management (e.g., limiting N volatilization versus limiting N losses to groundwater) warrant continued development of large-scale holistic strategies to manage water quality and quantity.

Using chemical and microbiological indicators to track the impacts from the land application of treated municipal wastewater and other sources on groundwater quality in a karstic springs basin

Science.gov (United States)

Katz, Brian G.; Griffin, Dale W.

2008-08-01

Multiple chemical constituents (nutrients; N, O, H, C stable isotopes; 64 organic wastewater compounds, 16 pharmaceutical compounds) and microbiological indicators were used to assess the impact on groundwater quality from the land application of approximately 9.5 million liters per day of treated municipal sewage effluent to a sprayfield in the 960-km2 Ichetucknee Springs basin, northern Florida. Enriched stable isotope signatures (δ18O and δ2H) were found in water from the effluent reservoir and a sprayfield monitoring well (MW-7) due to evaporation; however, groundwater samples downgradient from the sprayfield have δ18O and δ2H concentrations that represented recharge of meteoric water. Boron and chloride concentrations also were elevated in water from the sprayfield effluent reservoir and MW-7, but concentrations in groundwater decreased substantially with distance downgradient to background levels in the springs (about 12 km) and indicated at least a tenfold dilution factor. Nitrate-nitrogen isotope (δ15N NO3) values above 10 ‰ in most water samples were indicative of organic nitrogen sources except Blue Hole Spring (δ15N NO3 = 4.6 4.9 ‰), which indicated an inorganic source of nitrogen (fertilizers). The detection of low concentrations the insect repellent N, N-diethyl-metatoluamide (DEET), and other organic compounds associated with domestic wastewater in Devil’s Eye Spring indicated that leakage from a nearby septic tank drainfield likely has occurred. Elevated levels of fecal coliforms and enterococci were found in Blue Hole Spring during higher flow conditions, which likely resulted from hydraulic connections to upgradient sinkholes and are consistent with previoius dye-trace studies. Enteroviruses were not detected in the sprayfield effluent reservoir, but were found in low concentrations in water samples from a downgradient well and Blue Hole Spring during high-flow conditions indicating a human wastewater source. The Upper Floridan aquifer

Metabolic and Cardiovascular Ageing Indices in Relation to Glycated Haemoglobin in Healthy and Diabetic Subjects.

Science.gov (United States)

Suvarna H I, Shruthi; Moodithaya, Shailaja; Sharma, Raghava

2017-01-01

Ageing is a natural phenomenon that has tremendous amount of control over normal physiological functions. Diabetes mellitus and ageing share common symptoms like stiffness and loss of functioning of tissues due to cross-liked proteins and free radicals. Glycated Haemoglobin (HbA1c) is often used as a stable cumulative index of glycemic control and has shown that even in non-diabetic adults, there is a steady increase in HbA1c levels with age. Aim of the study is to evaluate the strength of association of HbA1c with metabolic and cardiovascular ageing indices in subjects between the age group of 40 to 60 yrs. A total of 220 subjects, with (n=110) and without (n=110) diabetes were assessed for the metabolic and cardiovascular ageing indices. BMI, waist hip ratio, fat percentage, Fasting blood sugar and HbA1c were assessed as metabolic ageing indices. The cardiovascular ageing indices measured were resting heart rate, blood pressure and heart rate variability. Ageing indices were compared between subjects with and without diabetes using independent' t' test and showed that the T2DM group exhibit significant accelerated ageing as compared to that of the controls. Pearson's and partial correlation coefficient was used to assess the association of HbA1c with the ageing indices without and with controlling for chronological age, indicated that, strength of association of levels of HBA1c with cardiovascular and other metabolic indices of ageing is statistically significant. The study concludes that the tightness of glycemic control has a significant impact on the biological ageing process. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Influence of gender and age on haematological indicators of Polbar’s breed chickens

Directory of Open Access Journals (Sweden)

Gryzińska Magdalena

2013-01-01

Full Text Available The aim of the study was to determine the values of selected haematological indices of the Polbar breed of chickens by gender and age. There was a significant WBC difference in cocks and hens with age. In each of the periods, cocks were characterized by a lower than hens number of LY. LY and NE declined with increasing age. Most values showed significant (P ≤ 0.05 differences for birds at different ages. These results of the haematological indices from consolidated Polbar breed can be used for comparisons with other breeds of poultry. The study deepens and organizes the knowledge within the possibilities of using and interpreting levels of haematological indicators for monitoring health of hens. In this paper, we managed to obtain information on the level of indicators rarely determined in chickens.

Isotope and minor element geochemistry of high arsenic groundwater from Hangjinhouqi, the Hetao Plain, Inner Mongolia

International Nuclear Information System (INIS)

Deng Yamin; Wang Yanxin; Ma Teng

2009-01-01

High As groundwater is widely distributed in the northwestern Hetao Plain, an arid region with slow groundwater flow. Arsenic concentration in groundwater ranges from 1 to 1000 μg/L. Most water samples have elevated salinities, with Cl and/or HCO 3 as the dominant anions and Na as the dominant cation. High concentrations of As in shallow aquifers are associated with strongly reducing conditions, as evidenced by high concentrations of dissolved organic C (DOC), NH 4 , dissolved sulfide, arsenite and dissolved CH 4 , and relatively low concentrations of NO 3 - and SO 4 2- . Results of the hydrochemical, and H and O isotope geochemical studies indicate that evapotranspiration is an important process controlling the enrichment of Na and Cl as well as trace elements such as As, B, F and Br in groundwater. In Na-HCO 3 -dominated groundwaters, As, B and F were enriched. Decades of irrigation using Yellow River water has resulted in elevation of the groundwater level, which has accelerated salt accumulation in shallow groundwater and surface soil. In addition, irrigation is responsible for the release of some components from aquifer materials and mixing with saline groundwaters, as indicated by minor element and isotope geochemical data. Used to trace groundwater flow paths, Sr isotope composition also indicates that bedrock weathering is one of the primary sources of As in groundwater in the study area.

Investigation of groundwater seepage from the Hanford shoreline of the Columbia River

International Nuclear Information System (INIS)

McCormack, W.D.; Carlile, J.M.V.

1984-11-01

Groundwater discharges to the Columbia River are evaluated by the Hanford Environmental Surveillance and Groundwater Surveillance Programs via monitoring of the Columbia River and Hanford groundwater. Both programs concluded that Hanford groundwater has not adversely affected Columbia River water quality. This report supplements the above programs by investigating the general characteristics of groundwater entering the Columbia River from the Hanford Site. Specific objectives of the investigation were to identify general shoreline areas where Hanford-related materials were entering the river, and to evaluate qualitatively the physical characteristics and relative magnitudes of those discharges. The study was conducted in two phases. Phase 1 involved visual inspection of Columbia River shoreline, within the Hanford Site, for indications of groundwater seepage. As a result of that inspection, 115 springs suspected of discharging groundwater were recorded. During Phase 2, water samples were collected from these springs and analyzed for Hanford-related materials known to be present in the groundwater. The specific materials used as indicators for the majority of samples were tritium or uranium and nitrate. The magnitude and distribution of concentrations measured in the spring samples were consistent with concentrations of these materials measured in groundwater near the sampled spring locations. Water samples were also collected from the Columbia River to investigate the localized effects of groundwater discharges occurring above and below river level. These samples were collected within 2 to 4 m of the Hanford shoreline and analyzed for tritium, nitrate, and uranium. Elevated concentrations were measured in river samples collected near areas where groundwater and spring concentrations were elevated. All concentrations were below applicable DOE Concentration Guides. 8 references, 6 figures, 7 tables

Microbial Functional Gene Diversity Predicts Groundwater Contamination and Ecosystem Functioning

Science.gov (United States)

Zhang, Ping; Wu, Linwei; Rocha, Andrea M.; Shi, Zhou; Wu, Bo; Qin, Yujia; Wang, Jianjun; Yan, Qingyun; Curtis, Daniel; Ning, Daliang; Van Nostrand, Joy D.; Wu, Liyou; Watson, David B.; Adams, Michael W. W.; Alm, Eric J.; Adams, Paul D.; Arkin, Adam P.

2018-01-01

ABSTRACT Contamination from anthropogenic activities has significantly impacted Earth’s biosphere. However, knowledge about how environmental contamination affects the biodiversity of groundwater microbiomes and ecosystem functioning remains very limited. Here, we used a comprehensive functional gene array to analyze groundwater microbiomes from 69 wells at the Oak Ridge Field Research Center (Oak Ridge, TN), representing a wide pH range and uranium, nitrate, and other contaminants. We hypothesized that the functional diversity of groundwater microbiomes would decrease as environmental contamination (e.g., uranium or nitrate) increased or at low or high pH, while some specific populations capable of utilizing or resistant to those contaminants would increase, and thus, such key microbial functional genes and/or populations could be used to predict groundwater contamination and ecosystem functioning. Our results indicated that functional richness/diversity decreased as uranium (but not nitrate) increased in groundwater. In addition, about 5.9% of specific key functional populations targeted by a comprehensive functional gene array (GeoChip 5) increased significantly (P contamination and ecosystem functioning. This study indicates great potential for using microbial functional genes to predict environmental contamination and ecosystem functioning. PMID:29463661

Tile Drainage Density Reduces Groundwater Travel Times and Compromises Riparian Buffer Effectiveness.

Science.gov (United States)

Schilling, Keith E; Wolter, Calvin F; Isenhart, Thomas M; Schultz, Richard C

2015-11-01

Strategies to reduce nitrate-nitrogen (nitrate) pollution delivered to streams often seek to increase groundwater residence time to achieve measureable results, yet the effects of tile drainage on residence time have not been well documented. In this study, we used a geographic information system groundwater travel time model to quantify the effects of artificial subsurface drainage on groundwater travel times in the 7443-ha Bear Creek watershed in north-central Iowa. Our objectives were to evaluate how mean groundwater travel times changed with increasing drainage intensity and to assess how tile drainage density reduces groundwater contributions to riparian buffers. Results indicate that mean groundwater travel times are reduced with increasing degrees of tile drainage. Mean groundwater travel times decreased from 5.6 to 1.1 yr, with drainage densities ranging from 0.005 m (7.6 mi) to 0.04 m (62 mi), respectively. Model simulations indicate that mean travel times with tile drainage are more than 150 times faster than those that existed before settlement. With intensive drainage, less than 2% of the groundwater in the basin appears to flow through a perennial stream buffer, thereby reducing the effectiveness of this practice to reduce stream nitrate loads. Hence, strategies, such as reconnecting tile drainage to buffers, are promising because they increase groundwater residence times in tile-drained watersheds. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Flow of river water into a karstic limestone aquifer - 2. Dating the young fraction in groundwater mixtures in the Upper Floridan aquifer near Valdosta, Georgia

Science.gov (United States)

Plummer, Niel; Busenberg, E.; Drenkard, S.; Schlosser, P.; Ekwurzel, B.; Weppernig, R.; McConnell, J.B.; Michel, R.L.

1998-01-01

-water fraction in Type-2 mixtures containing more than about 10??? river water. Of the 41 water samples measured for 3H/3He dating, dilution of H and low -He concentration limited 3H/3He dating to 16 mixtures in which 3H/3He ages are defined with errors ranging from ??2 to ??7.5 a (1 ??). After correction for dilution with (assumed) CFC-free regional infiltration water and regional paleowater in the Upper Floridan aquifer, adjusted CFC-12 ages agree with 3H/3He ages within 5 a or less in 7 of the 9 co-dated Type-2 mixtures Tritium data and dating based on both CFC-11 and CFC-12 in Type-I mixtures indicate that travel times of infiltration water through the overlying Post-Eocene semi-confining beds exceed 35 a. The CFC and 3H/3He dating indicate that the river fraction in most groundwater entered the groundwater reservoir in the past 20 to 30 a. Few domestic and municipal supply wells sampled intercept water younger than 5 a. Calculated velocities of river water in the Upper Floridan aquifer downgradient of the sinkhole area range from 0.4 to 8.2 m/d. Radiocarbon data indicate that ages of the regional paleowater are on the 10 000-a time scale. An average lag time of approximately 10 to 25 a is determined for discharge of groundwater from the surficial and intermediate aquifers above the Upper Floridan aquifer to the Withlacoochee River.

Filter-separable constituents of groundwater from the Columbia River plateau

International Nuclear Information System (INIS)

Seitz, M.G.; Boggs, S. Jr.

1984-01-01

The purpose of this procedure is to prepare groundwaters from the Columbia River basalt, northeastern Oregon, for batch partitioning experiments by concentration dissolved organic carbon (DOC) in water samples by ultrafiltration. Water samples were double-filtered through 0.4-μm Nuclepore polycarbonate filters to remove particulates before beginning the ultrafiltration process. The results of these experiments do not indicate a consistent relation between the distribution of americium with coexisting basalt and groundwater and the DOC content of the groundwater at 25 0 C, but there is some indication of increasing sorption of americium on basalt with increasing DOC at 90 0 C. However, any simple interpretation of the effects of DOC on the sorption behavior of americium must be made with caution, as there are other variables in the chemistry of the groundwaters that may also have important controls on this process. Another important observation from this set of experiments is that ultrafiltration does not seem to be an effective means of concentrating DOC without affecting the other trace constituents of groundwaters. The observed fractionation of groundwater chemistry as a result of the ultrafiltration procedure is not yet understood. However, for further progress in experiments of this type, it may be necessary to develop an alternative means of concentrating organic compounds that would allow the maintenance of constant values of other trace constituents as an experimental control

Environmental isotope investigation of groundwaters in the region of Taiyuan, Shanxi Province of China

International Nuclear Information System (INIS)

Wei Keqin; Lin Ruifen; Wang Zhixiang

1988-01-01

A comprehensive environmental isotope investigation of several complex groundwater systems and the mixing of groundwater with surface water in the region of Taiyuan, Shanxi Province of China, is presented. Environmental isotopes, including stable isotopes, tritium and uranium series in water and its activity ratio 234 U/ 238 U are applied to divide karstic groundwaters into separate Xishan and Dongshan systems. The Xishan karstic water system shows a great scattering of isotope data. This results from the mixing of karstic groundwater and surface water from the Fenhe River. The Dongshan system is homogeneous and karstic water is tritium free and its age should be more than 50-100 a. The increase in uranium activity ratio, which is correlated with the length of the flow paths, shows the run-off direction of the Dongshan karstic water system towards the major natural outlet, the Lancun Spring. The altitudes of recharge of Xishan and Dongshan karstic waters are evaluated as 1400 m and 1300 m, respectively. The ages of fissure groundwaters in metamorphic rocks are determined in terms of their tritium content. Some practical considerations upon groundwater management are also drawn from isotope results. (author). 9 refs, 10 figs, 9 tabs

Redox reaction rates in shallow aquifers: Implications for nitrate transport in groundwater and streams

Science.gov (United States)

Tesoriero, Anthony J.

2012-01-01

Groundwater age and water chemistry data along flow paths from recharge areas to streams were used to evaluate the trends and transformations of agricultural chemicals. Results from this analysis indicate that median nitrate recharge concentrations in these agricultural areas have increased markedly over the last 50 years from 4 mg N/L in samples collected prior to 1983 to 7.5 mg N/L in samples collected since 1983. The effect that nitrate accumulation in shallow aquifers will have on drinking water quality and stream ecosystems is dependent on the rate of redox reactions along flow paths and on the age distribution of nitrate discharging to supply wells and streams.

Analyses of infrequent (quasi-decadal) large groundwater recharge events in the northern Great Basin: Their importance for groundwater availability, use, and management

Science.gov (United States)

Masbruch, Melissa D.; Rumsey, Christine; Gangopadhyay, Subhrendu; Susong, David D.; Pruitt, Tom

2016-01-01

There has been a considerable amount of research linking climatic variability to hydrologic responses in the western United States. Although much effort has been spent to assess and predict changes in surface water resources, little has been done to understand how climatic events and changes affect groundwater resources. This study focuses on characterizing and quantifying the effects of large, multiyear, quasi-decadal groundwater recharge events in the northern Utah portion of the Great Basin for the period 1960–2013. Annual groundwater level data were analyzed with climatic data to characterize climatic conditions and frequency of these large recharge events. Using observed water-level changes and multivariate analysis, five large groundwater recharge events were identified with a frequency of about 11–13 years. These events were generally characterized as having above-average annual precipitation and snow water equivalent and below-average seasonal temperatures, especially during the spring (April through June). Existing groundwater flow models for several basins within the study area were used to quantify changes in groundwater storage from these events. Simulated groundwater storage increases per basin from a single recharge event ranged from about 115 to 205 Mm3. Extrapolating these amounts over the entire northern Great Basin indicates that a single large quasi-decadal recharge event could result in billions of cubic meters of groundwater storage. Understanding the role of these large quasi-decadal recharge events in replenishing aquifers and sustaining water supplies is crucial for long-term groundwater management.

Application of δ18O, δD, 3H-3He and CFCs to characterize the nitrate contamination of groundwater in Eumsung, Korea

Science.gov (United States)

Ju, Y. J.; Kaown, D.; Hahm, D.; Kim, I.; Lee, S. S.; Koh, E. H.; Kim, M.; Yoon, Y. Y.; Lee, K. K.

2015-12-01

We measured the major ions, stable oxygen and hydrogen isotopes, 3H-3He and CFCs concentration in groundwater to identify the characteristics of nitrate contamination and to understand the groundwater recharge patterns. In this study, 17 groundwater samples were collected for 5days (from March 3rd to 7th, 2015) in Eumseong, Korea. In the study area, NO3- concentrations in some groundwater samples (16 of 17) ranged from 5.7 to 103.7 mg/L (avg. 43.3 mg/L), which were substantially higher than the drinking water quality standard (10 mg/L). These excess NO3- inputs in groundwater seem to be originated from the agricultural use of chemical fertilizers because major ions associated with fertilizers were significantly correlated with NO3-. It seems that major groundwater recharge event during monsoon season is highly probable from the analysis of δ18O and δD. The apparent groundwater age using 3H-3He and CFCs varies from 5 to 40 yrs although the study area is small (1 km2). For the samples showed large deficiency of 3He, the sensitivity analysis was performed using NOBLE 90 in an effort to quantify the degassed amount. Since nitrate sources are quite evenly distributed through the field site, groundwater ages from shallow aquifer is inversely correlated with the nitrate concentrations. Our result implies that the 3H-3He ratio can be a useful indicator of tracing the recharge pattern of groundwater but also the nitrate loading characteristic in a small scale agricultural area. Acknowlegments: Financial support was provided by the "R&D Project on Environmental Management of Geologic CO2 Storage" from the KEITI (Project Number: 2014001810003) and the research project of "Advanced Technology for Groundwater Development and Application in Riversides (Geowater+)" in "Water Resources Management Program (code 11 Technology Innovation C05)" of the MOLIT and the KAIA in Korea.

A city scale study on the effects of intensive groundwater heat pump systems on heavy metal contents in groundwater.

Science.gov (United States)

García-Gil, Alejandro; Epting, Jannis; Garrido, Eduardo; Vázquez-Suñé, Enric; Lázaro, Jesús Mateo; Sánchez Navarro, José Ángel; Huggenberger, P; Calvo, Miguel Ángel Marazuela

2016-12-01

As a result of the increasing use of shallow geothermal resources, hydraulic, thermal and chemical impacts affecting groundwater quality can be observed with ever increasing frequency (Possemiers et al., 2014). To overcome the uncertainty associated with chemical impacts, a city scale study on the effects of intensive geothermal resource use by groundwater heat pump systems on groundwater quality, with special emphasis on heavy metal contents was performed. Statistical analysis of geochemical data obtained from several field campaigns has allowed studying the spatiotemporal relationship between temperature anomalies in the aquifer and trace element composition of groundwater. The relationship between temperature and the concentrations of trace elements resulted in weak correlations, indicating that temperature changes are not the driving factor in enhancing heavy metal contaminations. Regression models established for these correlations showed a very low reactivity or response of heavy metal contents to temperature changes. The change rates of heavy metal contents with respect to temperature changes obtained indicate a low risk of exceeding quality threshold values by means of the exploitation regimes used, neither producing nor enhancing contamination significantly. However, modification of pH, redox potential, electrical conductivity, dissolved oxygen and alkalinity correlated with the concentrations of heavy metals. In this case, the change rates of heavy metal contents are higher, with a greater risk of exceeding threshold values. Copyright © 2016 Elsevier B.V. All rights reserved.

Groundwater quality and hydrochemical properties of Al-Ula Region, Saudi Arabia.

Science.gov (United States)

Toumi, Naji; Hussein, Belal H M; Rafrafi, Sarra; El Kassas, Neama

2015-03-01

Groundwater quality monitoring is one of the most important aspects in groundwater studies in arid environments particularly in developing countries, like Saudi Arabia, due to the fast population growth and the expansion of irrigated agriculture and industrial uses. Groundwater samples have been collected from eight locations in Al-Ula in Saudi Arabia during June 2012 and January 2013 in order to investigate the hydrochemical characteristics and the groundwater quality and to understand the sources of dissolved ions. Physicochemical parameters of groundwater such as electrical conductivity, pH, total dissolved solid, and major cations and anions were determined. Chloride was found to be the dominant anion followed by HCO(-) 3 and SO4 (2-). Groundwater of the study area is characterized by the dominance of alkaline earths (Ca(2+) + Mg(2+)) over alkali metals (Na(+) + K(+)). The analytical results show that the groundwater is generally moderately hard and slightly alkaline in nature. The binary relationships of the major ions reveal that water quality of the Al-Ula region is mainly controlled by rock weathering, evaporation, and ion exchange reactions. Piper diagram was constructed to identify hydrochemical facies, and it was found that majority of the samples belong to Ca-Cl and mixed Ca-Mg-Cl facies. Chemical indices like chloro-alkali indices, sodium adsorption ratio, percentage of sodium, residual sodium carbonate, and permeability index were calculated. Also, the results show that the chemical composition of groundwater sources of Al-Ula is strongly influenced by lithology of country rocks rather than anthropogenic activities.

Establishment of Groundwater Arsenic Potential Distribution and Discrimination in Taiwan

Science.gov (United States)

Tsai, Kuo Sheng; Chen, Yu Ying; Chung Liu, Chih; Lin, Chien Wen

2016-04-01

According to the last 10 years groundwater monitoring data in Taiwan, Arsenic concentration increase rapidly in some areas, similar to Bengal and India, the main source of Arsenic-polluted groundwater is geological sediments, through reducing reactions. There are many researches indicate that high concentration of Arsenic in groundwater poses the risk to water safety, for example, the farm lands irrigation water contains Arsenic cause the concentration of Arsenic increase in soil and crops. Based on the management of water usage instead of remediation in the situation of insufficient water. Taiwan EPA has been developed the procedures of Arsenic contamination potential area establishment and source discriminated process. Taiwan EPA use the procedures to determine the management of using groundwater, and the proposing usage of Arsenic groundwater accordance with different objects. Agencies could cooperate with the water quality standard or water needs, studying appropriate water purification methods and the groundwater depth, water consumption, thus achieve the goal of water safety and environmental protection, as a reference of policy to control total Arsenic concentration in groundwater. Keywords: Arsenic; Distribution; Discrimination; Pollution potential area of Arsenic; Origin evaluation of groundwater Arsenic

Groundwater sustainability strategies

Science.gov (United States)

Gleeson, Tom; VanderSteen, Jonathan; Sophocleous, Marios A.; Taniguchi, Makoto; Alley, William M.; Allen, Diana M.; Zhou, Yangxiao

2010-01-01

Groundwater extraction has facilitated significant social development and economic growth, enhanced food security and alleviated drought in many farming regions. But groundwater development has also depressed water tables, degraded ecosystems and led to the deterioration of groundwater quality, as well as to conflict among water users. The effects are not evenly spread. In some areas of India, for example, groundwater depletion has preferentially affected the poor. Importantly, groundwater in some aquifers is renewed slowly, over decades to millennia, and coupled climate–aquifer models predict that the flux and/or timing of recharge to many aquifers will change under future climate scenarios. Here we argue that communities need to set multigenerational goals if groundwater is to be managed sustainably.