Evaluating hydrochemical data from shallow groundwater in Laxemar from a microbiological perspective

International Nuclear Information System (INIS)

Hallbeck, Lotta

2008-01-01

Oxygen is one of the chemical species that can corrode a copper canister in a KBS-3 repository. It is therefore important to determine whether oxygen dissolved in precipitation or groundwater could reach repository depth by means of groundwater transport. This can be determined by gaining an understanding of the oxygen-consuming microbial processes that take place in shallow groundwater in the area of interest. This report evaluates hydrogeochemical data from shallow groundwater in the Laxemar area from a microbiological perspective. Hydrogeochemical data were gathered from soil pipes at depths from 1.6 to 16.5 m and from percussion-drilled boreholes having mid-point depths of between 28.5 and 131 m. Only a few of the percussion-drilled boreholes had packers installed; the sampled sections were therefore very extended, allowing groundwaters from many different depths to mix. Oxygen and oxygen reduction potential (ORP) were not measured in groundwater from soil pipes or percussion drilled boreholes. The report therefore focuses on parameters that indicated ongoing anaerobic microbial processes, such as nitrite, ferrous iron, dissolved manganese, and sulphide, that were found in many soil pipes. Even though many of the soil pipes were located in similar environments and at relatively similar depths, ranging from 3.5 to 6 m, they displayed individual chemical profiles in terms of chemical species related to microbial activity. The microbial activity could not be linked to the classes of soil pipe, i.e. recharge, discharge, or intermittent. Existing soil pipes and percussion-drilled boreholes could be used for additional sampling to measure microbial parameters. Such sampling would benefit from the careful hypothesis-driven description of the sampling parameters and experience-guided choice of sampling methods

Groundwater chemistry of shallow aquifers in the coastal zones of Cochin, India

Digital Repository Service at National Institute of Oceanography (India)

Laluraj, C.M.; Gopinath, G.; DineshKumar, P.K.

Laluraj et al.: Groundwater chemistry of shallow aquifers - 133 - APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 3(1): 133-139. http://www.ecology.kee.hu ● ISSN 1589 1623  2005, Penkala Bt., Budapest, Hungary GROUNDWATER CHEMISTRY OF SHALLOW AQUIFERS... post monsoon (November 2003) in the coastal zones of Cochin. Laluraj et al.: Groundwater chemistry of shallow aquifers - 134 - APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 3(1): 133-139. http://www.ecology.kee.hu ● ISSN 1589 1623  2005, Penkala...

Modelling the response of shallow groundwater levels to combined climate and water-diversion scenarios in Beijing-Tianjin-Hebei Plain, China

Science.gov (United States)

Li, Xue; Ye, Si-Yuan; Wei, Ai-Hua; Zhou, Peng-Peng; Wang, Li-Heng

2017-09-01

A three-dimensional groundwater flow model was implemented to quantify the temporal variation of shallow groundwater levels in response to combined climate and water-diversion scenarios over the next 40 years (2011-2050) in Beijing-Tianjin-Hebei (Jing-Jin-Ji) Plain, China. Groundwater plays a key role in the water supply, but the Jing-Jin-Ji Plain is facing a water crisis. Groundwater levels have declined continuously over the last five decades (1961-2010) due to extensive pumping and climate change, which has resulted in decreased recharge. The implementation of the South-to-North Water Diversion Project (SNWDP) will provide an opportunity to restore the groundwater resources. The response of groundwater levels to combined climate and water-diversion scenarios has been quantified using a groundwater flow model. The impacts of climate change were based on the World Climate Research Programme's (WCRP's) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset for future high (A2), medium (A1B), and low (B1) greenhouse gas scenarios; precipitation data from CMIP3 were applied in the model. The results show that climate change will slow the rate of decrease of the shallow groundwater levels under three climate-change scenarios over the next 40 years compared to the baseline scenario; however, the shallow groundwater levels will rise significantly (maximum of 6.71 m) when considering scenarios that combine climate change and restrictions on groundwater exploitation. Restrictions on groundwater exploitation for water resource management are imperative to control the decline of levels in the Jing-Jin-Ji area.

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 water derives in part from groundwater—water that has spent some time in the subsurface (e.g. soil, unsaturated zone, saturated zone). However, because groundwater residence times vary from months to millennia, determining the proportion of shallow and deep groundwater contribution can be challenging. Groundwater dating with anthropogenic gases and natural geochemical tracers can decipher the origin of groundwater contribution to rivers, particularly when repeat samplings are carried out in different hydrological conditions. Here, we present two different applications of this approach from three hydrological observatories (H+ hydrogeological network; Aghrys and Armorique observatories) in western France, all these observatories belonging to the OZCAR national network. We carried out a regional investigation of mean groundwater ages in hard rock aquifers in Brittany, using long-term chronicles from hydrological observatories and regional monitoring sites. We determined the mean residence-time (RT) and annual renewal rate (RR) of four compartments of these aquifers: the direct contribution of a very young water component (i.e. RT less than 1-2 yr), the upper variably saturated zone (RR 27-33%), the weathered layer (RR 1.8-2.1%) and the fractured zone (RR 0.1%). From these values and a nitrate chronicle, we were able to determine the respective contributions of each compartment to the largest river in Brittany, the Vilaine, which drains 30% of the region. We found that the deep fractured compartment with very slow renewal times contributed to 25-45% of river water in winter and 30-60% in summer. The very young water which includes direct precipitation and soil fluxes constituted 40-65% of the winter river water (Aquilina et al., 2012). To complement these estimates, we investigated the relationship between dissolved silica and groundwater age in the Armorique hydrological observatory in northern Brittany. We computed the silica concentration expected along the

Hydrogeological Characteristics of Groundwater Yield in Shallow ...

African Journals Online (AJOL)

Hydrogeological Characteristics of Groundwater Yield in Shallow Wells of the ... of Water Resources and Lower Niger River Basin Development Authority in Ilorin. ... moment correlation, multiple and stepwise multiple regression analysis.

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

Manually operated tube wells that tap into shallow aquifers remain a critical source of untreated drinking water in south Asia and an estimated 37 million people are still exposed to elevated levels of As in Bangladesh(1). This field effort sought to address two questions. What mechanisms control the partitioning of As between groundwater and sediment? How does groundwater transport affect the spatial variability of dissolved As? Understanding the source of groundwater variability is essential for understanding how [As] will change with time, especially as Bangladesh and its water demands develop. Arsenic mobility and transport within the shallow aquifer was investigated at a 0.5 km2 site where [As] increases from conditions measured by spiking freshly collected sediment was remarkably uniform: Kd = 1.5 ± 0.5 L/kg, at 14 of 15 locations. Push- pull tests were used to alter groundwater [As] surrounding a well, without disturbing the sediment. The aquifer responded to the imposed dis-equilibrium by either adsorbing or desorbing As within a few days. These results provide further evidence that groundwater [As] is controlled by As sorption reactions with the sediment that reach equilibrium rapidly compared to the time scale of groundwater flow. A simple reactive-transport model for the site based on the measured partitioning coefficient, Kd, however, supports the notion that the [As] gradient observed reflects the gradual removal of As by groundwater flow over hundreds to thousands of years. The onset of irrigation and industrial pumping at this site has induced a reversal in flow, consequently groundwater now moves from high [As] into low [As] areas. This change could result in rising [As] to levels >50 μg/L in the village within the next few decades. The rapid economic development of Bangladesh could induce similar changes in groundwater flow, and thus As concentrations, elsewhere. This suggests that periodic monitoring of shallow wells low in As within regions of

Characterization of the shallow groundwater system in an alpine watershed: Handcart Gulch, Colorado, USA

Science.gov (United States)

Kahn, Katherine G.; Ge, Shemin; Caine, Jonathan S.; Manning, A.

2008-01-01

Water-table elevation measurements and aquifer parameter estimates are rare in alpine settings because few wells exist in these environments. Alpine groundwater systems may be a primary source of recharge to regional groundwater flow systems. Handcart Gulch is an alpine watershed in Colorado, USA comprised of highly fractured Proterozoic metamorphic and igneous rocks with wells completed to various depths. Primary study objectives include determining hydrologic properties of shallow bedrock and surficial materials, developing a watershed water budget, and testing the consistency of measured hydrologic properties and water budget by constructing a simple model incorporating groundwater and surface water for water year 2005. Water enters the study area as precipitation and exits as discharge in the trunk stream or potential recharge for the deeper aquifer. Surficial infiltration rates ranged from 0.1-6.2??0-5 m/s. Discharge was estimated at 1.28??10-3 km3. Numerical modeling analysis of single-well aquifer tests predicted lower specific storage in crystalline bedrock than in ferricrete and colluvial material (6.7??10-5-2.10??0-3 l/m). Hydraulic conductivity in crystalline bedrock was significantly lower than in colluvial and alluvial material (4.3??10-9 -2.0??10-4 m/s). Water budget results suggest that during normal precipitation and temperatures water is available to recharge the deeper groundwater flow system. ?? Springer-Verlag 2007.

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

Shallow ground-water conditions, Tom Green County, Texas

Science.gov (United States)

Lee, J.N.

1986-01-01

Most of the water needs of Tom Green County, Texas, are supplied by ground water; however, the city of San Angelo is supplied by surface water. Groundwater withdrawals during 1980 (latest year for which data are available) in Tom Green County totaled about 15,300 acre-feet, all derived from shallow aquifers. Shallow aquifers in this report refer to the ground-water system generally less than 400 feet deep that contains water with less than a 10,000 milligrams per liter concentration of dissolved solids; aquifers comprising this system include: The Leona, Comanche Peak, Trinity, Blaine, San Angelo, Choza, Bullwagon, Vale, Standpipe, and Arroyo aquifers.

Impact of the climate change to shallow groundwater in Baltic artesian basin

Science.gov (United States)

Lauva, D.; Bethers, P.; Timuhins, A.; Sennikovs, J.

2012-04-01

The purpose of our work was to find the long term pattern of annual shallow ground water changes in region of Latvia, ground water level modelling for the contemporary climate and future climate scenarios and the model generalization to the Baltic artesian basin (BAB) region. Latvia is located in the middle part of BAB. It occupies about 65'000 square kilometers. BAB territory (480'000 square kilometres) also includes Lithuania, Estonia as well as parts of Poland, Russia, Belarus and the Baltic Sea. Territory of BAB is more than seven times bigger than Latvia. Precipitation and spring snow melt are the main sources of the ground water recharge in BAB territory. The long term pattern of annual shallow ground water changes was extracted from the data of 25 monitoring wells in the territory of Latvia. The main Latvian groundwater level fluctuation regime can be described as a function with two maximums (in spring and late autumn) and two minimums (in winter and late summer). The mathematical model METUL (developed by Latvian University of Agriculture) was chosen for the ground water modelling. It was calibrated on the observations in 25 gauging wells around Latvia. After the calibration we made calculations using data provided by an ensemble of regional climate models, yielding a continuous groundwater table time-series from 1961 to 2100, which were analysed and split into 3 time windows for further analysis: contemporary climate (1961-1990), near future (2021-2050) and far future (2071-2100). The daily average temperature, precipitation and humidity time series were used as METUL forcing parameters. The statistical downscaling method (Sennikovs and Bethers, 2009) was applied for the bias correction of RCM calculated and measured variables. The qualitative differences in future and contemporary annual groundwater regime are expected. The future Latvian annual groundwater cycle according to the RCM climate projection changes to curve with one peak and one drought point

A generalized regression model of arsenic variations in the shallow groundwater of Bangladesh

Science.gov (United States)

Taylor, Richard G.; Chandler, Richard E.

2015-01-01

Abstract Localized studies of arsenic (As) in Bangladesh have reached disparate conclusions regarding the impact of irrigation‐induced recharge on As concentrations in shallow (≤50 m below ground level) groundwater. We construct generalized regression models (GRMs) to describe observed spatial variations in As concentrations in shallow groundwater both (i) nationally, and (ii) regionally within Holocene deposits where As concentrations in groundwater are generally high (>10 μg L−1). At these scales, the GRMs reveal statistically significant inverse associations between observed As concentrations and two covariates: (1) hydraulic conductivity of the shallow aquifer and (2) net increase in mean recharge between predeveloped and developed groundwater‐fed irrigation periods. Further, the GRMs show that the spatial variation of groundwater As concentrations is well explained by not only surface geology but also statistical interactions (i.e., combined effects) between surface geology and mean groundwater recharge, thickness of surficial silt and clay, and well depth. Net increases in recharge result from intensive groundwater abstraction for irrigation, which induces additional recharge where it is enabled by a permeable surface geology. Collectively, these statistical associations indicate that irrigation‐induced recharge serves to flush mobile As from shallow groundwater. PMID:27524841

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.

In situ disinfection of sewage contaminated shallow groundwater: a feasibility study.

Science.gov (United States)

Bailey, Morgan M; Cooper, William J; Grant, Stanley B

2011-11-01

Sewage-contaminated shallow groundwater is a potential cause of beach closures and water quality impairment in marine coastal communities. In this study we set out to evaluate the feasibility of several strategies for disinfecting sewage-contaminated shallow groundwater before it reaches the coastline. The disinfection rates of Escherichia coli (EC) and enterococci bacteria (ENT) were measured in mixtures of raw sewage and brackish shallow groundwater collected from a coastal community in southern California. Different disinfection strategies were explored, ranging from benign (aeration alone, and aeration with addition of brine) to aggressive (chemical disinfectants peracetic acid (PAA) or peroxymonosulfate (Oxone)). Aeration alone and aeration with brine did not significantly reduce the concentration of EC and ENT after 6 h of exposure, while 4-5 mg L(-1) of PAA or Oxone achieved >3 log reduction after 15 min of exposure. Oxone disinfection was more rapid at higher salinities, most likely due to the formation of secondary oxidants (e.g., bromine and chlorine) that make this disinfectant inappropriate for marine applications. Using a Lagrangian modeling framework, we identify several factors that could influence the performance of in-situ disinfection with PAA, including the potential for bacterial regrowth, and the non-linear dependence of disinfection rate upon the residence time of water in the shallow groundwater. The data and analysis presented in this paper provide a framework for evaluating the feasibility of in-situ disinfection of shallow groundwater, and elucidate several topics that warrant further investigation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Quality assessment of groundwater from shallow aquifers in Hong ...

African Journals Online (AJOL)

Quality assessment of groundwater from shallow aquifers in Hong area, Adamawa state, northeastern Nigeria. ... The high content of fluoride and iron in the groundwater may have contributed to the high EC and TDS especially during the rainy season when the rate of leaching and infiltration is high. Keywords: Quality ...

Chlorate origin and fate in shallow groundwater below agricultural landscapes

International Nuclear Information System (INIS)

Mastrocicco, Micòl; Di Giuseppe, Dario; Vincenzi, Fabio; Colombani, Nicolò; Castaldelli, Giuseppe

2017-01-01

In agricultural lowland landscapes, intensive agricultural is accompanied by a wide use of agrochemical application, like pesticides and fertilizers. The latter often causes serious environmental threats such as N compounds leaching and surface water eutrophication; additionally, since perchlorate can be present as impurities in many fertilizers, the potential presence of perchlorates and their by-products like chlorates and chlorites in shallow groundwater could be a reason of concern. In this light, the present manuscript reports the first temporal and spatial variation of chlorates, chlorites and major anions concentrations in the shallow unconfined aquifer belonging to Ferrara province (in the Po River plain). The study was made in 56 different locations to obtain insight on groundwater chemical composition and its sediment matrix interactions. During the monitoring period from 2010 to 2011, in June 2011 a nonpoint pollution of chlorates was found in the shallow unconfined aquifer belonging to Ferrara province. Detected chlorates concentrations ranged between 0.01 and 38 mg/l with an average value of 2.9 mg/l. Chlorates were found in 49 wells out of 56 and in all types of lithology constituting the shallow aquifer. Chlorates concentrations appeared to be linked to NO 3 − , volatile fatty acids (VFA) and oxygen reduction potential (ORP) variations. Chlorates behaviour was related to the biodegradation of perchlorates, since perchlorates are favourable electron acceptors for the oxidation of labile dissolved organic carbon (DOC) in groundwater. Further studies must take into consideration to monitor ClO 4 − in pore waters and groundwater to better elucidate the mass flux of ClO 4 − in shallow aquifers belonging to agricultural landscapes. - Highlights: • Chlorates were found in agricultural shallow wells after fertilizers spreading. • Chlorates concentrations appeared to be linked to NO 3 − , VFA and ORP variations. • Chlorates behaviour was

The origin of high hydrocarbon groundwater in shallow Triassic aquifer in Northwest Guizhou, China.

Science.gov (United States)

Liu, Shan; Qi, Shihua; Luo, Zhaohui; Liu, Fangzhi; Ding, Yang; Huang, Huanfang; Chen, Zhihua; Cheng, Shenggao

2018-02-01

Original high hydrocarbon groundwater represents a kind of groundwater in which hydrocarbon concentration exceeds 0.05 mg/L. The original high hydrocarbon will significantly reduce the environment capacity of hydrocarbon and lead environmental problems. For the past 5 years, we have carried out for a long-term monitoring of groundwater in shallow Triassic aquifer in Northwest Guizhou, China. We found the concentration of petroleum hydrocarbon was always above 0.05 mg/L. The low-level anthropogenic contamination cannot produce high hydrocarbon groundwater in the area. By using hydrocarbon potential, geochemistry and biomarker characteristic in rocks and shallow groundwater, we carried out a comprehensive study in Dalongjing (DLJ) groundwater system to determine the hydrocarbon source. We found a simplex hydrogeology setting, high-level water-rock-hydrocarbon interaction and obviously original hydrocarbon groundwater in DLJ system. The concentration of petroleum hydrocarbon in shallow aquifer was found to increase with the strong water-rock interaction. Higher hydrocarbon potential was found in the upper of Guanling formation (T 2 g 3 ) and upper of Yongningzhen formation (T 1 yn 4 ). Heavily saturated carbon was observed from shallow groundwater, which presented similar distribution to those from rocks, especially from the deeper groundwater. These results indicated that the high concentrations of original hydrocarbon in groundwater could be due to the hydrocarbon release from corrosion and extraction out of strata over time.

Chlorate origin and fate in shallow groundwater below agricultural landscapes.

Science.gov (United States)

Mastrocicco, Micòl; Di Giuseppe, Dario; Vincenzi, Fabio; Colombani, Nicolò; Castaldelli, Giuseppe

2017-12-01

In agricultural lowland landscapes, intensive agricultural is accompanied by a wide use of agrochemical application, like pesticides and fertilizers. The latter often causes serious environmental threats such as N compounds leaching and surface water eutrophication; additionally, since perchlorate can be present as impurities in many fertilizers, the potential presence of perchlorates and their by-products like chlorates and chlorites in shallow groundwater could be a reason of concern. In this light, the present manuscript reports the first temporal and spatial variation of chlorates, chlorites and major anions concentrations in the shallow unconfined aquifer belonging to Ferrara province (in the Po River plain). The study was made in 56 different locations to obtain insight on groundwater chemical composition and its sediment matrix interactions. During the monitoring period from 2010 to 2011, in June 2011 a nonpoint pollution of chlorates was found in the shallow unconfined aquifer belonging to Ferrara province. Detected chlorates concentrations ranged between 0.01 and 38 mg/l with an average value of 2.9 mg/l. Chlorates were found in 49 wells out of 56 and in all types of lithology constituting the shallow aquifer. Chlorates concentrations appeared to be linked to NO 3 - , volatile fatty acids (VFA) and oxygen reduction potential (ORP) variations. Chlorates behaviour was related to the biodegradation of perchlorates, since perchlorates are favourable electron acceptors for the oxidation of labile dissolved organic carbon (DOC) in groundwater. Further studies must take into consideration to monitor ClO 4 - in pore waters and groundwater to better elucidate the mass flux of ClO 4 - in shallow aquifers belonging to agricultural landscapes. Copyright © 2017 Elsevier Ltd. All rights reserved.

A global-scale two-layer transient groundwater model : Development and application to groundwater depletion

NARCIS (Netherlands)

de Graaf, Inge E.M.|info:eu-repo/dai/nl/338038612; van Beek, Rens L.P.H.|info:eu-repo/dai/nl/14749799X; Gleeson, Tom; Moosdorf, Nils; Schmitz, Oliver|info:eu-repo/dai/nl/314003975; Sutanudjaja, Edwin H.|info:eu-repo/dai/nl/314571477; Bierkens, Marc F.P.|info:eu-repo/dai/nl/125022794

2017-01-01

Groundwater is the world's largest accessible source of freshwater to satisfy human water needs. Moreover, groundwater buffers variable precipitation rates over time, thereby effectively sustaining river flows in times of droughts and evaporation in areas with shallow water tables. In this study,

The tritium content of precipitation and groundwater at Yola, Nigeria ...

African Journals Online (AJOL)

Tritium is a radioactive isotope of hydrogen which occurs in precipitation. In groundwater studies tritium measurements give information on the time of recharge to the system; the tritium content of precipitation being used to estimate the input of tritium to the groundwater system. At Yola, the tritium ontents in precipitation and ...

Modeling contribution of shallow groundwater to evapotranspiration and yield of maize in an arid area.

Science.gov (United States)

Gao, Xiaoyu; Huo, Zailin; Qu, Zhongyi; Xu, Xu; Huang, Guanhua; Steenhuis, Tammo S

2017-02-21

Capillary rise from shallow groundwater can decrease the need for irrigation water. However, simple techniques do not exist to quantify the contribution of capillary flux to crop water use. In this study we develop the Agricultural Water Productivity Model for Shallow Groundwater (AWPM-SG) for calculating capillary fluxes from shallow groundwater using readily available data. The model combines an analytical solution of upward flux from groundwater with the EPIC crop growth model. AWPM-SG was calibrated and validated with 2-year lysimetric experiment with maize. Predicted soil moisture, groundwater depth and leaf area index agreed with the observations. To investigate the response of model, various scenarios were run in which the irrigation amount and groundwater depth were varied. Simulations shows that at groundwater depth of 1 m capillary upward supplied 41% of the evapotranspiration. This reduced to 6% at groundwater depth of 2 m. The yield per unit water consumed (water productivity) was nearly constant for 2.3 kg/m 3 . The yield per unit water applied (irrigation water productivity) increased with decreasing irrigation water because capillary rise made up in part for the lack of irrigation water. Consequently, using AWPM-SG in irrigation scheduling will be beneficial to save more water in areas with shallow groundwater.

Recharge Area of Groundwater of Jakarta Basin

International Nuclear Information System (INIS)

Wandowo; Abidin, Zainal; Alip; Djiono

2002-01-01

Groundwater inside the earth contained in a porous and permeable layers called aquifers. Depend on the hydrogeological structure, the aquifers may be composed of independent layers separated each other by impermeable boundaries. Such a condition may effect the location of recharge where water is able to infiltrate and goes to the aquifers. The objective of this research is to find out and to locate the recharge area of Jakarta basin by utilizing stable isotopes 2H and 18O . The work was done by collecting shallow and deep groundwater samples throughout Jabotabek area and precipitations from different altitudes. Since the stable isotopes composition of precipitation is subject to the altitude, the recharge area would be able to be identified by assessing the correlation of stable isotopes composition of precipitation and corresponding groundwater population. The data obtained from this study suggested that shallow groundwater is originated from local recharge while deep groundwater is recharged from the area having altitude of 125 -230 meters, it correspond to the area between Depok and Bogor

Groundwater quality in the North San Francisco Bay shallow aquifer, California

Science.gov (United States)

Bennett, George L.; Fram, Miranda S.

2018-02-23

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The North San Francisco Bay Shallow Aquifer constitutes one of the study units being evaluated.

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)

Concentrations and potential health hazards of organochlorine pesticides in (shallow) groundwater of Taihu Lake region, China.

Science.gov (United States)

Wu, Chunfa; Luo, Yongming; Gui, Tong; Huang, Yujuan

2014-02-01

A total of 27 shallow groundwater samples were collected from the Taihu Lake region (TLR), to determine the concentrations of 14 organochlorine pesticide (OCP) species, identify their possible sources, and estimate health risk of drinking the shallow groundwater. All OCP species occurred in the shallow groundwater of TLR with high detection frequency except p, p'-dichlorodiphenyldichlorothane (p, p'-DDD) and p, p'-dichlorodiphenyltrichloroethane (p, p'-DDT). DDTs and hexachlorocyclohexanes (HCHs) were the dominant OCP contaminants in the shallow groundwater of TLR, and they account for 44.2% total OCPs. The low α-HCH/γ-HCH ratio, high β-HCH/(α+γ)-HCH ratio and β-HCH being the dominant HCH isomers for the majority of samples suggest that the HCHs were mainly from the historical use of lindane after a period of degradation. p, p'-DDE being the dominant DDT metabolite for all the samples indicated that the DDTs were mainly from the historical residues. Compositional analysis also suggested that there were fresh input sources of heptachlors, aldrins and endrins in addition to the historical residues. Correlation analysis indicated the hexachlorobenzene (HCB) impurity in the shallow groundwater of TLR was likely from the historical application of lindane and technical HCH (a mixture of HCH isomers that is produced by photochlorination of benzene). Carcinogenic risk values for α-HCH, heptachlor, heptachlor epoxide, aldrins and dieldrin in the shallow groundwater in majority area of TLR were found to be >10(-6), posing a potentially serious cancer risk to those dependant on shallow groundwater for drinking water. © 2013.

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

Transport and potential attenuation of nitrogen in shallow groundwaters in the lower Rangitikei catchment, New Zealand.

Science.gov (United States)

Collins, S; Singh, R; Rivas, A; Palmer, A; Horne, D; Manderson, A; Roygard, J; Matthews, A

2017-11-01

Intensive agricultural activities are generally associated with nitrogen leaching from agricultural soils, and this nitrogen has the potential to percolate and contaminate groundwater and surface waters. We assessed surface water and groundwater interactions, and nitrogen leaching and its potential attenuation in shallow groundwater in the lower Rangitikei River catchment (832km 2 ), New Zealand. We combined regional- and local-scale field surveys and experiments, nutrient budget modelling, and hydraulic and geochemical methods, to gain an insight into leaching, transformation and transport of nitrogen via groundwaters to the river in the study area. Concurrent river flow gaugings (in January 2015) and a piezometric map, developed from measured depths to groundwater in 110 bores (in October 2014), suggest groundwater discharges to the Rangitikei River in the upper parts of the study area, while there is groundwater recharge near the coast. The groundwater redox characterisation, based on sampling and analysis of 15 mostly shallow bores (shallow groundwater piezometers (3-6mbgl) using single-well push-pull tests. We found generally low levels (shallow groundwater piezometers (>5mbgl), despite being installed under intensive land uses, such as dairying and cropping. Our in-field push-pull tests showed NO 3 -N reduction at four shallow groundwater piezometers, with the rates of reduction varying from 0.04mgNL -1 h - 1 to 1.57mgNL -1 h - 1 . This highlights the importance of a sound understanding of not only the sources, but also transport and transformation, or fate, of nutrients leached from farms, to mitigate the likely impacts of land use on water quality and ecosystem health in agricultural catchments. Copyright © 2017 Elsevier B.V. All rights reserved.

Shallow and Deep Groundwater Contributions to Ephemeral Streamflow Generation

Science.gov (United States)

Zimmer, M. A.; McGlynn, B. L.

2016-12-01

Our understanding of streamflow generation processes in low relief, humid landscapes is limited. To address this, we utilized an ephemeral-to-intermittent drainage network in the Piedmont region of the United States to gain new understanding about the drivers of ephemeral streamflow generation, stream-groundwater interactions, and longitudinal expansion and contraction of the stream network. We used hydrometric and chemical data collected within zero through second order catchments to characterize streamflow and overland, shallow soil, and deep subsurface flow across landscape positions. Results showed bi-directionality in stream-groundwater gradients that were dependent on catchment storage state. This led to annual groundwater recharge magnitudes that were similar to annual streamflow. Perched shallow and deep water table contributions shifted dominance with changes in catchment storage state, producing distinct stream hydrograph recession constants. Active channel length versus runoff followed a consistent relationship independent of storage state, but exhibited varying discharge-solute hysteresis directions. Together, our results suggest that temporary streams can act as both important groundwater recharge and discharge locations across the landscape, especially in this region where ephemeral drainage densities are among the highest recorded. Our results also highlight that the internal catchment dynamics that generate temporary streams play an important role in dictating biogeochemical fluxes at the landscape scale.

Emulation of recharge and evapotranspiration processes in shallow groundwater systems

Science.gov (United States)

Doble, Rebecca C.; Pickett, Trevor; Crosbie, Russell S.; Morgan, Leanne K.; Turnadge, Chris; Davies, Phil J.

2017-12-01

In shallow groundwater systems, recharge and evapotranspiration are highly sensitive to changes in the depth to water table. To effectively model these fluxes, complex functions that include soil and vegetation properties are often required. Model emulation (surrogate modelling or meta-modelling) can provide a means of incorporating detailed conceptualisation of recharge and evapotranspiration processes, while maintaining the numerical tractability and computational performance required for regional scale groundwater models and uncertainty analysis. A method for emulating recharge and evapotranspiration processes in groundwater flow models was developed, and applied to the South East region of South Australia and western Victoria, which is characterised by shallow groundwater, wetlands and coastal lakes. The soil-vegetation-atmosphere transfer (SVAT) model WAVES was used to generate relationships between net recharge (diffuse recharge minus evapotranspiration from groundwater) and depth to water table for different combinations of climate, soil and land cover types. These relationships, which mimicked previously described soil, vegetation and groundwater behaviour, were combined into a net recharge lookup table. The segmented evapotranspiration package in MODFLOW was adapted to select values of net recharge from the lookup table depending on groundwater depth, and the climate, soil and land use characteristics of each cell. The model was found to be numerically robust in steady state testing, had no major increase in run time, and would be more efficient than tightly-coupled modelling approaches. It made reasonable predictions of net recharge and groundwater head compared with remotely sensed estimates of net recharge and a standard MODFLOW comparison model. In particular, the method was better able to predict net recharge and groundwater head in areas with steep hydraulic gradients.

Effects of intensive urbanization on the intrusion of shallow groundwater into deep groundwater: Examples from Bangkok and Jakarta

International Nuclear Information System (INIS)

Onodera, Shin-ichi; Saito, Mitsuyo; Sawano, Misa; Hosono, Takahiro; Taniguchi, Makoto; Shimada, Jun; Umezawa, Yu; Lubis, Rachmat Fajar; Buapeng, Somkid; Delinom, Robert

2008-01-01

Asian megacities have severe pollution problems in both coastal and urban areas. In addition, the groundwater potential has decreased and land subsidence has occurred because of intensive groundwater pumping in urban areas. To prevent the adverse effects of urbanization on groundwater quality, it is necessary to confirm the changes in groundwater flow and contaminant transport caused by urbanization. We examined the effects of urbanization on contaminant transport in groundwater. The research areas were located around Bangkok, Thailand, and akarta, Indonesia, cities with populations of approximately 8 and 12 million, respectively. Each metropolitan city is located on a river delta and is adjacent to a bay. We measured the water level and collected water samples at boreholes at multiple depths (100 to 200 m) in 2004 and 2006 in Bangkok and Jakarta, respectively. The current hydraulic potential is below sea level in both cities because of prior excess abstraction of groundwater. As a result, the direction of groundwater flow is now downward in the coastal area. The Cl - concentration and δ 18 O distributions in groundwater suggest that the decline in hydraulic potential has caused the intrusion of seawater and shallow groundwater into deep groundwater. Concentrations of Mn and NO3 - -N in groundwater suggest the intrusion of these contaminants from shallow to deep aquifers with downward groundwater flow and implies an accumulation of contaminants in deep aquifers. Therefore, it is important to recognize the possibility of future contaminant transport with the discharge of deep groundwater into the sea after the recovery of groundwater potential in the coastal areas

Decomposition of groundwater level fluctuations using transfer modelling in an area with shallow to deep unsaturated zones

Science.gov (United States)

Gehrels, J. C.; van Geer, F. C.; de Vries, J. J.

1994-05-01

Time series analysis of the fluctuations in shallow groundwater levels in the Netherlands lowlands have revealed a large-scale decline in head during recent decades as a result of an increase in land drainage and groundwater withdrawal. The situation is more ambiguous in large groundwater bodies located in the eastern part of the country, where the unsaturated zone increases from near zero along the edges to about 40 m in the centre of the area. As depth of the unsaturated zone increases, groundwater level reacts with an increasing delay to fluctuations in climate and influences of human activities. The aim of the present paper is to model groundwater level fluctuations in these areas using a linear stochastic transfer function model, relating groundwater levels to estimated precipitation excess, and to separate artificial components from the natural groundwater regime. In this way, the impact of groundwater withdrawal and the reclamation of a 1000 km 2 polder area on the groundwater levels in the adjoining higher ground could be assessed. It became evident that the linearity assumption of the transfer functions becomes a serious drawback in areas with the deepest groundwater levels, because of non-linear processes in the deep unsaturated zone and the non-synchronous arrival of recharge in the saturated zone. Comparison of the results from modelling the influence of reclamation with an analytical solution showed that the lowering of groundwater level is partly compensated by reduced discharge and therefore is less than expected.

Characterizing Groundwater Level and Flow Pattern in a Shallow ...

African Journals Online (AJOL)

Bheema

This study characterize groundwater yield and flow pattern on a shallow ... simple process of weathering, fractured fissure systems, networks of joints and ..... lowest yield in wells that are deeper than the mean well depth in the study area.

Inducing mineral precipitation in groundwater by addition of phosphate

Directory of Open Access Journals (Sweden)

Hartmann Thomas

2011-10-01

Full Text Available Abstract Background Induced precipitation of phosphate minerals to scavenge trace elements from groundwater is a potential remediation approach for contaminated aquifers. The success of engineered precipitation schemes depends on the particular phases generated, their rates of formation, and their long term stability. The purpose of this study was to examine the precipitation of calcium phosphate minerals under conditions representative of a natural groundwater. Because microorganisms are present in groundwater, and because some proposed schemes for phosphate mineral precipitation rely on stimulation of native microbial populations, we also tested the effect of bacterial cells (initial densities of 105 and 107 mL-1 added to the precipitation medium. In addition, we tested the effect of a trace mixture of propionic, isovaleric, formic and butyric acids (total concentration 0.035 mM. Results The general progression of mineral precipitation was similar under all of the study conditions, with initial formation of amorphous calcium phosphate, and transformation to poorly crystalline hydroxylapatite (HAP within one week. The presence of the bacterial cells appeared to delay precipitation, although by the end of the experiments the overall extent of precipitation was similar for all treatments. The stoichiometry of the final precipitates as well as Rietveld structure refinement using x-ray diffraction data indicated that the presence of organic acids and bacterial cells resulted in an increasing a and decreasing c lattice parameter, with the higher concentration of cells resulting in the greatest distortion. Uptake of Sr into the solids was decreased in the treatments with cells and organic acids, compared to the control. Conclusions Our results suggest that the minerals formed initially during an engineered precipitation application for trace element sequestration may not be the ones that control long-term immobilization of the contaminants. In

Temporal-spatial variations and influencing factors of nitrogen in the shallow groundwater of the nearshore vegetable field of Erhai Lake, China.

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Chen, Anqiang; Lei, Baokun; Hu, Wanli; Wang, Hongyuan; Zhai, Limei; Mao, Yanting; Fu, Bin; Zhang, Dan

2018-02-01

Nitrogen export from the nearshore vegetable field of Erhai Lake seriously threatens the water quality of Erhai Lake, which is the second largest highland freshwater lake in Yunnan Province, China. Among the nitrogen flows into Erhai Lake, shallow groundwater migration is a major pathway. The nitrogen variation and influencing factors in the shallow groundwater of the nearshore vegetable field of Erhai Lake are not well documented. A 2-year field experiment was conducted to determine the concentrations of nitrogen species in the shallow groundwater and their influencing factors in the nearshore vegetable field of Erhai Lake. The results showed that concentrations of TN, NO 3 - -N, and NO 2 - -N gradually increased with increasing elevation and distance from Erhai Lake, but the opposite was observed for NH 4 + -N in the shallow groundwater. The concentrations of nitrogen species in the rainy season were greater than those in the dry season. NO 3 - -N accounted for more than 79% of total nitrogen in shallow groundwater. Redundancy analysis showed that more than 70% of the temporal and spatial variations of nitrogen concentrations in the shallow groundwater were explained by shallow groundwater depth, and only approximately 10% of variation was explained by the factors of soil porosity, silt clay content of soil, and NH 4 + -N and NO 3 - -N concentrations of soil (p shallow groundwater depth had more notable effects on nitrogen concentrations in the shallow groundwater than other factors. This result will strongly support the need for further research regarding the management practices for reducing nitrogen concentrations in shallow groundwater.

Climate change impact on shallow groundwater conditions in Hungary: Conclusions from a regional modelling study

Science.gov (United States)

Kovács, Attila; Marton, Annamária; Tóth, György; Szöcs, Teodóra

2016-04-01

A quantitative methodology has been developed for the calculation of groundwater table based on measured and simulated climate parameters. The aim of the study was to develop a toolset which can be used for the calculation of shallow groundwater conditions for various climate scenarios. This was done with the goal of facilitating the assessment of climate impact and vulnerability of shallow groundwater resources. The simulated groundwater table distributions are representative of groundwater conditions at the regional scale. The introduced methodology is valid for modelling purposes at various scales and thus represents a versatile tool for the assessment of climate vulnerability of shallow groundwater bodies. The calculation modules include the following: 1. A toolset to calculate climate zonation from climate parameter grids, 2. Delineation of recharge zones (Hydrological Response Units, HRUs) based on geology, landuse and slope conditions, 3. Calculation of percolation (recharge) rates using 1D analytical hydrological models, 4. Simulation of the groundwater table using numerical groundwater flow models. The applied methodology provides a quantitative link between climate conditions and shallow groundwater conditions, and thus can be used for assessing climate impacts. The climate data source applied in our calculation comprised interpolated daily climate data of the Central European CARPATCLIM database. Climate zones were determined making use of the Thorntwaite climate zonation scheme. Recharge zones (HRUs) were determined based on surface geology, landuse and slope conditions. The HELP hydrological model was used for the calculation of 1D water balance for hydrological response units. The MODFLOW numerical groundwater modelling code was used for the calculation of the water table. The developed methodology was demonstrated through the simulation of regional groundwater table using spatially averaged climate data and hydrogeological properties for various time

Radon concentration distributions in shallow and deep groundwater around the Tachikawa fault zone.

Science.gov (United States)

Tsunomori, Fumiaki; Shimodate, Tomoya; Ide, Tomoki; Tanaka, Hidemi

2017-06-01

Groundwater radon concentrations around the Tachikawa fault zone were surveyed. The radon concentrations in shallow groundwater samples around the Tachikawa fault segment are comparable to previous studies. The characteristics of the radon concentrations on both sides of the segment are considered to have changed in response to the decrease in groundwater recharge caused by urbanization on the eastern side of the segment. The radon concentrations in deep groundwater samples collected around the Naguri and the Tachikawa fault segments are the same as those of shallow groundwater samples. However, the radon concentrations in deep groundwater samples collected from the bedrock beside the Naguri and Tachikawa fault segments are markedly higher than the radon concentrations expected from the geology on the Kanto plane. This disparity can be explained by the development of fracture zones spreading on both sides of the two segments. The radon concentration distribution for deep groundwater samples from the Naguri and the Tachikawa fault segments suggests that a fault exists even at the southern part of the Tachikawa fault line. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical characteristics of surface systems in the Simpevarp area. Visualisation and statistical evaluation of data from surface water, precipitation, shallow groundwater, and regolith

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-01-15

The Swedish Nuclear Fuel and Waste management Co (SKB) initiated site investigations for a deep repository for spent nuclear fuel at two different sites in Sweden, Forsmark and Oskarshamn, in 2002. This report evaluates the results from chemical investigations of the surface system in the Simpevarp area in Oskarshamn, i.e. both the Laxemar subarea and the Simpevarp subarea, during the period Nov 2002 - Mar 2005. The evaluation includes data from surface waters (lakes, streams and the sea), precipitation, shallow groundwater and regolith (till, soil, peat, sediments and biota) in the area. The main focus of the study is to visualize the vast amount of data collected hitherto in the site investigations, and to give a chemical characterisation of the investigated media at the site. The results will be used to support the site descriptive models, which in turn are used for safety assessment studies and for the environmental impact assessment. The data used consist of water chemical composition in lakes, streams and coastal sites, and in precipitation, predominantly sampled on a monthly basis, and in groundwater from soil tubes and wells. Moreover, regolith data includes information on the chemical composition of till, soil, sediment and vegetation samples from the area. The characterisations include all measured chemical parameters, i.e. major and minor constituents, trace elements, nutrients, isotopes and radio nuclides, as well as field measured parameters. The evaluation of data from each medium has been divided into the following parts: Characterisation of individual sampling sites, and comparisons within and among sampling sites as well as comparisons with local, regional and national reference data. Analysis of time trends and seasonal variation (for surface waters). Exploration of relationships among the various chemical parameters. For all investigated parameters, the report presents selected statistics for each sampling site, as well as for available reference

Chemical characteristics of surface systems in the Simpevarp area. Visualisation and statistical evaluation of data from surface water, precipitation, shallow groundwater, and regolith

International Nuclear Information System (INIS)

Troejbom, Mats; Soederbaeck, Bjoern

2006-01-01

The Swedish Nuclear Fuel and Waste management Co (SKB) initiated site investigations for a deep repository for spent nuclear fuel at two different sites in Sweden, Forsmark and Oskarshamn, in 2002. This report evaluates the results from chemical investigations of the surface system in the Simpevarp area in Oskarshamn, i.e. both the Laxemar subarea and the Simpevarp subarea, during the period Nov 2002 - Mar 2005. The evaluation includes data from surface waters (lakes, streams and the sea), precipitation, shallow groundwater and regolith (till, soil, peat, sediments and biota) in the area. The main focus of the study is to visualize the vast amount of data collected hitherto in the site investigations, and to give a chemical characterisation of the investigated media at the site. The results will be used to support the site descriptive models, which in turn are used for safety assessment studies and for the environmental impact assessment. The data used consist of water chemical composition in lakes, streams and coastal sites, and in precipitation, predominantly sampled on a monthly basis, and in groundwater from soil tubes and wells. Moreover, regolith data includes information on the chemical composition of till, soil, sediment and vegetation samples from the area. The characterisations include all measured chemical parameters, i.e. major and minor constituents, trace elements, nutrients, isotopes and radio nuclides, as well as field measured parameters. The evaluation of data from each medium has been divided into the following parts: Characterisation of individual sampling sites, and comparisons within and among sampling sites as well as comparisons with local, regional and national reference data. Analysis of time trends and seasonal variation (for surface waters). Exploration of relationships among the various chemical parameters. For all investigated parameters, the report presents selected statistics for each sampling site, as well as for available reference

Remediating Contaminant Plumes in Groundwater with Shallow Excavations Containing Coarse Reactive Media.

Science.gov (United States)

Hudak, Paul F

2018-02-01

A groundwater flow and mass transport model tested the capability of shallow excavations filled with coarse, reactive media to remediate a hypothetical unconfined aquifer with a maximum saturated thickness of 5 m. Modeled as contaminant sinks, the rectangular excavations were 10 m downgradient of an initial contaminant plume originating from a source at the top of the aquifer. The initial plume was approximately 259 m long, 23 m wide, and 5 m thick, with a downgradient tip located approximately 100 m upgradient of the site boundary. The smallest trench capable of preventing offsite migration was 11 m long (measured perpendicular to groundwater flow), 4 m wide (measured parallel to groundwater flow), and 3 m deep. Results of this study suggest that shallow trenches filled with coarse filter media that partially penetrate unconfined aquifers may be a viable alternative for remediating contaminated groundwater at some sites.

Groundwater level responses to precipitation variability in Mediterranean insular aquifers

Science.gov (United States)

Lorenzo-Lacruz, Jorge; Garcia, Celso; Morán-Tejeda, Enrique

2017-09-01

Groundwater is one of the largest and most important sources of fresh water on many regions under Mediterranean climate conditions, which are exposed to large precipitation variability that includes frequent meteorological drought episodes, and present high evapotranspiration rates and water demand during the dry season. The dependence on groundwater increases in those areas with predominant permeable lithologies, contributing to aquifer recharge and the abundance of ephemeral streams. The increasing pressure of tourism on water resources in many Mediterranean coastal areas, and uncertainty related to future precipitation and water availability, make it urgent to understand the spatio-temporal response of groundwater bodies to precipitation variability, if sustainable use of the resource is to be achieved. We present an assessment of the response of aquifers to precipitation variability based on correlations between the Standardized Precipitation Index (SPI) at various time scales and the Standardized Groundwater Index (SGI) across a Mediterranean island. We detected three main responses of aquifers to accumulated precipitation anomalies: (i) at short time scales of the SPI (24 months). The differing responses were mainly explained by differences in lithology and the percentage of highly permeable rock strata in the aquifer recharge areas. We also identified differences in the months and seasons when aquifer storages are more dependent on precipitation; these were related to climate seasonality and the degree of aquifer exploitation or underground water extraction. The recharge of some aquifers, especially in mountainous areas, is related to precipitation variability within a limited spatial extent, whereas for aquifers located in the plains, precipitation variability influence much larger areas; the topography and geological structure of the island explain these differences. Results indicate large spatial variability in the response of aquifers to precipitation in

Simulation of shallow groundwater levels: Comparison of a data-driven and a conceptual model

Science.gov (United States)

Fahle, Marcus; Dietrich, Ottfried; Lischeid, Gunnar

2015-04-01

Despite an abundance of models aimed at simulating shallow groundwater levels, application of such models is often hampered by a lack of appropriate input data. Difficulties especially arise with regard to soil data, which are typically hard to obtain and prone to spatial variability, eventually leading to uncertainties in the model results. Modelling approaches relying entirely on easily measured quantities are therefore an alternative to encourage the applicability of models. We present and compare two models for calculating 1-day-ahead predictions of the groundwater level that are only based on measurements of potential evapotranspiration, precipitation and groundwater levels. The first model is a newly developed conceptual model that is parametrized using the White method (which estimates the actual evapotranspiration on basis of diurnal groundwater fluctuations) and a rainfall-response ratio. Inverted versions of the two latter approaches are then used to calculate the predictions of the groundwater level. Furthermore, as a completely data-driven alternative, a simple feed-forward multilayer perceptron neural network was trained based on the same inputs and outputs. Data of 4 growing periods (April to October) from a study site situated in the Spreewald wetland in North-east Germany were taken to set-up the models and compare their performance. In addition, response surfaces that relate model outputs to combinations of different input variables are used to reveal those aspects in which the two approaches coincide and those in which they differ. Finally, it will be evaluated whether the conceptual approach can be enhanced by extracting knowledge of the neural network. This is done by replacing in the conceptual model the default function that relates groundwater recharge and groundwater level, which is assumed to be linear, by the non-linear function extracted from the neural network.

Relative Contribution of Monsoon Precipitation and Pumping to Changes in Groundwater Storage in India

Science.gov (United States)

Asoka, Akarsh; Gleeson, Tom; Wada, Yoshihide; Mishra, Vimal

2017-01-01

The depletion of groundwater resources threatens food and water security in India. However, the relative influence of groundwater pumping and climate variability on groundwater availability and storage remains unclear. Here we show from analyses of satellite and local well data spanning the past decade that long-term changes in monsoon precipitation are driving groundwater storage variability in most parts of India either directly by changing recharge or indirectly by changing abstraction. We find that groundwater storage has declined in northern India at the rate of 2 cm/yr and increased by 1 to 2 cm/yr in southern India between 2002 and 2013. We find that a large fraction of the total variability in groundwater storage in north-central and southern India can be explained by changes in precipitation. Groundwater storage variability in northwestern India can be explained predominantly by variability in abstraction for irrigation, which is in turn influenced by changes in precipitation. Declining precipitation in northern India is linked to Indian Ocean warming, suggesting a previously unrecognized teleconnection between ocean temperatures and groundwater storage.

INVESTIGATION OF STABLE ISOTOPE OF 18O AND 2H IN SHALLOW GROUNDWATER FROM KARAWANG AREA

Directory of Open Access Journals (Sweden)

E. Ristin Pujiindiyati

2010-06-01

Full Text Available Karawang area is well known as an agriculture area and 2% area is utilized for industries. Clean water demands increase due to developing industry development and population increasement. The origin of groundwater is necessary to keep the sustainability of water resources in this area. Stable isotopes such as 18O and 2H can be used as a parameter to trace the ground water origin. The methods used were Epstein-Mayeda and Zinc reduction for analysis 18O and 2H, respectively. Sampling period was conducted in major dry season in year 2002. The result showed that evaporation effect had influenced to the content of both isotopes in its shallow groundwater that caused a slope shift from its local meteoric line. The origin of its shallow groundwater was from rainwater infiltrating directly in less than 10 m altitude. Citarum River showed more depleted values in both isotopes compared to shallow groundwater and it indicated that its water might originate from spring at the altitude of 600 m.     Keywords: oxygene-18, deuterium, groundwater, isotope

Shallow groundwater quality and geochemistry in the Fayetteville Shale gas-production area, north-central Arkansas, 2011

Science.gov (United States)

Kresse, Timothy M.; Warner, Nathaniel R.; Hays, Phillip D.; Down, Adrian; Vengosh, Avner; Jackson, Robert B.

2012-01-01

analyses. Additionally, no statistical difference existed between chloride concentrations from water-quality data collected for this study from 94 wells located less than 2 miles from a gas-production well and 33 wells located 2 miles or more from a gas-production well; a Wilcoxon rank-sum test showed a p-value of 0.71. Major ion chemistry was investigated to understand the effects of geochemical and reduction-oxidation (redox) processes on the shallow groundwater in the study area along a continuum of increased rock-water interaction represented by increases in dissolved solids concentration. Groundwater in sandstone formations is represented by a low dissolved solids concentration (less than 30 mg/L) and slightly acidic water type. Shallow shale aquifers were represented by dissolved solids concentrations ranging upward to 686 mg/L, and water types evolving from a dominantly mixed-bicarbonate and calcium-bicarbonate to a strongly sodium-bicarbonate water type. Methane concentration and carbon isotopic composition were analyzed in 51 of the 127 samples collected for this study. Methane occurred above a detection limit of 0.0002 mg/L in 32 of the 51 samples, with concentrations ranging upward to 28.5 mg/L. Seven samples had methane concentrations greater than or equal to 0.5 mg/L. The carbon isotopic composition of these higher concentration samples, including the highest concentration of 28.5 mg/L, shows the methane was likely biogenic in origin with carbon isotope ratio values ranging from -57.6 to -74.7 per mil. Methane concentrations increased with increases in dissolved solids concentrations, indicating more strongly reducing conditions with increasing rock-water interaction in the aquifer. As such, groundwater-quality data collected for this study indicate that groundwater chemistry in the shallow aquifer system in the study area is a result of natural processes, beginning with recharge of dilute atmospheric precipitation and evolution of observed groundwater

Occurrence, behavior and distribution of high levels of uranium in shallow groundwater at Datong basin, northern China

Energy Technology Data Exchange (ETDEWEB)

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

2014-02-01

Geochemical investigations of uranium (U) occurrence in the environments were conducted at Datong basin of northern China. The results suggest that U contents were generally < 1 mg/kg for the igneous and metamorphic rocks, typically 2–5 mg/kg for the Carboniferous and Permian sedimentary rocks and around 3 mg/kg for sediments and topsoil, respectively. U in the Quaternary aquifer sediments may be primarily associated with carnotite from the Carboniferous and Permian coal-bearing clastic rocks around the basin. Shallow groundwater had U concentrations of < 0.02–288 μg/L (average 24 μg/L), with 24% of the investigated boreholes above the WHO provisional guideline of 30 μg/L for U in drinking water. Average U concentration for surface water was 5.8 μg/L. In oxidizing waters, uranyl (UO{sub 2}{sup 2+}) species is dominant and strongly adsorbed onto iron (hydro)xides, while it would be preferentially complexed with carbonate in the alkaline groundwater, forming highly soluble uranyl-carbonate complexes at Datong. Under reducing conditions, uranous (U(IV)) species is ready to precipitate or bind to organic matter, therefore having a low mobility. At the study area, high U groundwater (> 30 μg/L) occurs at the alluvial plains due to intermediate redox and enhanced alkaline conditions. The abnormally high levels of U in groundwater (> 100 μg/L) are locally found at the west alluvial plains. By contrast, U co-precipitation with secondary carbonate minerals like Ca{sub 2}UO{sub 2}(CO{sub 3}){sub 3} in the dominant Ca–Mg–Na–HCO{sub 3} type groundwater may prevail at the east alluvial plains. Besides, bedrocks such as Carboniferous and Permian sedimentary rocks, especially the coal-bearing strata which have higher U contents at the west mountain areas may also account for the abnormally high levels of U in groundwater. - Highlights: • High U groundwater occurs at the alluvial plains of Datong basin. • Redox state, complexation and adsorption are responsible

Understanding the hydrologic impacts of wastewater treatment plant discharge to shallow groundwater: Before and after plant shutdown

Science.gov (United States)

Hubbard, Laura E.; Keefe, Steffanie H.; Kolpin, Dana W.; Barber, Larry B.; Duris, Joseph W.; Hutchinson, Kasey J.; Bradley, Paul M.

2016-01-01

Effluent-impacted surface water has the potential to transport not only water, but wastewater-derived contaminants to shallow groundwater systems. To better understand the effects of effluent discharge on in-stream and near-stream hydrologic conditions in wastewater-impacted systems, water-level changes were monitored in hyporheic-zone and shallow-groundwater piezometers in a reach of Fourmile Creek adjacent to and downstream of the Ankeny (Iowa, USA) wastewater treatment plant (WWTP). Water-level changes were monitored from approximately 1.5 months before to 0.5 months after WWTP closure. Diurnal patterns in WWTP discharge were closely mirrored in stream and shallow-groundwater levels immediately upstream and up to 3 km downstream of the outfall, indicating that such discharge was the primary control on water levels before shutdown. The hydrologic response to WWTP shutdown was immediately observed throughout the study reach, verifying the far-reaching hydraulic connectivity and associated contaminant transport risk. The movement of WWTP effluent into alluvial aquifers has implications for potential WWTP-derived contamination of shallow groundwater far removed from the WWTP outfall.

Relations between precipitation, groundwater withdrawals, and changes in hydrologic conditions at selected monitoring sites in Volusia County, Florida, 1995--2010

Science.gov (United States)

Murray, Louis C.

2012-01-01

A study to examine the influences of climatic and anthropogenic stressors on groundwater levels, lake stages, and surface-water discharge at selected sites in northern Volusia County, Florida, was conducted in 2009 by the U.S. Geological Survey. Water-level data collected at 20 monitoring sites (17 groundwater and 3 lake sites) in the vicinity of a wetland area were analyzed with multiple linear regression to examine the relative influences of precipitation and groundwater withdrawals on changes in groundwater levels and lake stage. Analyses were conducted across varying periods of record between 1995 and 2010 and included the effects of groundwater withdrawals aggregated from municipal water-supply wells located within 12 miles of the project sites. Surface-water discharge data at the U.S. Geological Survey Tiger Bay canal site were analyzed for changes in flow between 1978 and 2001. As expected, water-level changes in monitoring wells located closer to areas of concentrated groundwater withdrawals were more highly correlated with withdrawals than were water-level changes measured in wells further removed from municipal well fields. Similarly, water-level changes in wells tapping the Upper Floridan aquifer, the source of municipal supply, were more highly correlated with groundwater withdrawals than were water-level changes in wells tapping the shallower surficial aquifer system. Water-level changes predicted by the regression models over precipitation-averaged periods of record were underestimated for observations having large positive monthly changes (generally greater than 1.0 foot). Such observations are associated with high precipitation and were identified as points in the regression analyses that produced large standardized residuals and/or observations of high influence. Thus, regression models produced by multiple linear regression analyses may have better predictive capability in wetland environments when applied to periods of average or below average

Transport and potential attenuation of nitrogen in shallow groundwaters in the lower Rangitikei catchment, New Zealand

Science.gov (United States)

Collins, S.; Singh, R.; Rivas, A.; Palmer, A.; Horne, D.; Manderson, A.; Roygard, J.; Matthews, A.

2017-11-01

Intensive agricultural activities are generally associated with nitrogen leaching from agricultural soils, and this nitrogen has the potential to percolate and contaminate groundwater and surface waters. We assessed surface water and groundwater interactions, and nitrogen leaching and its potential attenuation in shallow groundwater in the lower Rangitikei River catchment (832 km2), New Zealand. We combined regional- and local-scale field surveys and experiments, nutrient budget modelling, and hydraulic and geochemical methods, to gain an insight into leaching, transformation and transport of nitrogen via groundwaters to the river in the study area. Concurrent river flow gaugings (in January 2015) and a piezometric map, developed from measured depths to groundwater in 110 bores (in October 2014), suggest groundwater discharges to the Rangitikei River in the upper parts of the study area, while there is groundwater recharge near the coast. The groundwater redox characterisation, based on sampling and analysis of 15 mostly shallow bores ( 5 m bgl), despite being installed under intensive land uses, such as dairying and cropping. Our in-field push-pull tests showed NO3-N reduction at four shallow groundwater piezometers, with the rates of reduction varying from 0.04 mg N L- 1 h-1 to 1.57 mg N L- 1 h-1. This highlights the importance of a sound understanding of not only the sources, but also transport and transformation, or fate, of nutrients leached from farms, to mitigate the likely impacts of land use on water quality and ecosystem health in agricultural catchments.

Shallow groundwater quality and associated non-cancer health risk in agricultural areas (Poyang Lake basin, China).

Science.gov (United States)

Soldatova, Evgeniya; Sun, Zhanxue; Maier, Sofya; Drebot, Valeriia; Gao, Bai

2018-03-24

Owing to their accessibility, shallow groundwater is an essential source of drinking water in rural areas while usually being used without control by authorities. At the same time, this type of water resource is one of the most vulnerable to pollution, especially in regions with extensive agricultural activity. These factors increase the probability of adverse health effects in the population as a result of the consumption of shallow groundwater. In the present research, shallow groundwater quality in the agricultural areas of Poyang Lake basin was assessed according to world and national standards for drinking water quality. To evaluate non-cancer health risk from drinking groundwater, the hazard quotient from exposure to individual chemicals and hazard index from exposure to multiple chemicals were applied. It was found that, in shallow groundwater, the concentrations of 11 components (NO 3 - , NH 4 + , Fe, Mn, As, Al, rare NO 2 - , Se, Hg, Tl and Pb) exceed the limits referenced in the standards for drinking water. According to the health risk assessment, only five components (NO 3 - , Fe, As, rare NO 2 - and Mn) likely provoke non-cancer effects. The attempt to evaluate the spatial distribution of human health risk from exposure to multiple chemicals shows that the most vulnerable area is associated with territory characterised by low altitude where reducing or near-neutral conditions are formed (lower reaches of Xiushui and Ganjiang Rivers). The largest health risk is associated with the immune system and adverse dermal effects.

In situ treatment of cyanide-contaminated groundwater by iron cyanide precipitation

International Nuclear Information System (INIS)

Ghosh, R.S.; Dzombak, D.A.; Luthy, R.G.; Smith, J.R.

1999-01-01

Groundwater contamination with cyanide is common at many former or active industrial sites. Metal-cyanide complexes typically dominate aqueous speciation of cyanide in groundwater systems, with iron-cyanide complexes often most abundant. Typically, metal-cyanide complexes behave as nonadsorbing solutes in sand-gravel aquifer systems in the neutral pH range, rendering cyanide relatively mobile in groundwater systems. Groundwater pump-and-treat systems have often been used to manage cyanide contamination in groundwater. This study examined the feasibility of using in situ precipitation of iron cyanide in a reactive barrier to attenuate the movement of cyanide in groundwater. Laboratory column experiments were performed in which cyanide solutions were passed through mixtures of sand and elemental iron filings. Removal of dissolved cyanide was evaluated in a variety of cyanide-containing influents under various flow rates and sand-to-iron weight ratios. Long-term column tests performed with various cyanide-containing influents under both oxic and anoxic conditions, at neutral pH and at flow rates typical of sand-gravel porous media, yielded effluent concentrations of total cyanide as low as 0.5 mg/L. Effluent cyanide concentrations achieved were close to the solubilities of Turnbull's blue-hydrous ferric oxide solid solutions, indicating co-precipitation of the two solids. Maximum cyanide removal efficiency was achieved with approximately 10% by weight of iron in the sand-iron mixtures; higher iron contents did not increase removal efficiency significantly. Results obtained indicate that in situ precipitation is a promising passive treatment approach for cyanide in groundwater

Ground-Water Hydrology and Projected Effects of Ground-Water Withdrawals in the Sevier Desert, Utah

OpenAIRE

United States Geological Survey

1983-01-01

The principal ground-water reservoir in the Sevier Desert is the unconsolidated basin fill. The fill has been divided generally into aquifers and confining beds, although there are no clearcut boundaries between these units--the primary aquifers are the shallow and deep artesian aquifers. Recharge to the ground-water reservoir is by infiltration of precipitation; seepage from streams, canals, reservoirs, and unconsumed irrigation water; and subsurface inflow from consolidated rocks in mount...

Tritium in Precipitation, Surface and Groundwaters in the Zagreb Area

International Nuclear Information System (INIS)

Horvatincic, N.; Baresic, J.; Sironic, A.; Krajcar Bronic, I.; Obelic, B.

2011-01-01

Radioactive isotope tritium (3H) and stable isotopes of hydrogen (2H/1H) and oxygen (18O/16O) were measured in Sava River, precipitation and groundwater at 3 monitoring wells (piezometers) and 1 production well of the Petrusevec aquifer, close to the Sava River. Samples were collected monthly during 2010. The investigation is included in the Regional IAEA Project RER/8/016 Using Environmental Isotopes for Evaluation of Streamwater/Groundwater Interactions in Selected Aquifers in the Danube Basin. Sava River is a tributary of Danube River and the aim of the investigation is to determine the influence of surface stream of Sava River to the groundwater of aquifer used for water exploitation. In this work only 3H results were presented. 3H was measured by liquid scintillation counter Quantulus 1220, using electrolytic enrichment for all samples. 3H activity in precipitation showed slight seasonal fluctuation between 4 TU and 14 TU, with higher values in summer. 3H activity of Sava River and groundwater of the Petrusevec aquifer followed 3H of precipitation till May 2010. Significant increase of 3H in Sava River was observed in June, (199 @ 20) TU, and in the next month it fell down at 6 TU. Increase of 3H was also observed in groundwater but with damped response (maximum 60 TU) and with delay of 2 - 3 months related to Sava River. Different response of different piezometers and the well indicated the different infiltration times of surface water of Sava River to groundwater of the Petrusevec aquifer. The increased 3H activity in surface and groundwaters was caused by release of tritiated water from the Krsko Nuclear Power Plant, 30 km upstream from Zagreb. The results of 3H, 2H/1H and 18O/16O measurements will be used to determine the infiltration time of groundwater of the Petrusevec aquifer using conceptual and mathematical models. (author)

Transient changes in shallow groundwater chemistry during the MSU ZERT CO2 injection experiment

Science.gov (United States)

Apps, J.A.; Zheng, Lingyun; Spycher, N.; Birkholzer, J.T.; Kharaka, Y.; Thordsen, J.; Kakouros, E.; Trautz, R.

2011-01-01

Food-grade CO2 was injected into a shallow aquifer through a perforated pipe placed horizontally 1-2 m below the water table at the Montana State University Zero Emission Research and Technology (MSU-ZERT) field site at Bozeman, Montana. The possible impact of elevated CO2 levels on groundwater quality was investigated by analyzing 80 water samples taken before, during, and following CO2 injection. Field determinations and laboratory analyses showed rapid and systematic changes in pH, alkalinity, and conductance, as well as increases in the aqueous concentrations of trace element species. The geochemical data were first evaluated using principal component analysis (PCA) in order to identify correlations between aqueous species. The PCA findings were then used in formulating a geochemical model to simulate the processes likely to be responsible for the observed increases in the concentrations of dissolved constituents. Modeling was conducted taking into account aqueous and surface complexation, cation exchange, and mineral precipitation and dissolution. Reasonable matches between measured data and model results suggest that: (1) CO2 dissolution in the groundwater causes calcite to dissolve. (2) Observed increases in the concentration of dissolved trace metals result likely from Ca+2-driven ion exchange with clays (smectites) and sorption/desorption reactions likely involving Fe (hydr)oxides. (3) Bicarbonate from CO2 dissolution appears to compete for sorption with anionic species such as HAsO4-2, potentially increasing dissolved As levels in groundwater. ?? 2011 Published by Elsevier Ltd.

Groundwater sampling from shallow boreholes (PP and PR) and groundwater observation tubes (PVP) at Olkiluoto in 2004

Energy Technology Data Exchange (ETDEWEB)

Hirvonen, H. [Teollisuuden Voima Oyj, Eurajoki (Finland)

2005-11-15

Groundwater sampling from the shallow boreholes and groundwater observation tubes was performed in summer 2004 (PP2, PP3, PP7, PP8, PRl, PVPl, PVP3A, PVP3B, PVP4A and PVP4B) and in autumn 2004 (PP2, PP3, PP5, PP7, PP8, PP9, PP36, PP37, PP39, PR1, PR2, PVP1, PVP3A, PVP3B, PVP4A, PVP8A, PVP9A, PVP9B, PVP10B, PVP11, PVP12, PVP13, PVP14 and PVP20). The results from previous samplings have been used in the hydrogeochemical baseline characterization at Olkiluoto and some of the latest results have also been part of the ONKALO monitoring program. This study contains data on preliminary pumping of the sampling points and pumping for groundwater sampling and chemical analyses in the laboratory. This study also includes comparison with analytical results obtained between 1995-2004. The total dissolved solids (TDS) of groundwater samples were mainly below 1000 mg/L. According to Davis's TDS classification, these waters were fresh waters. The only exception was the water sample from shallow borehole PP7 (1400mg/L and 1450mg/L), which was brackish. Several different groundwater types were observed, but the most common water type was Ca-HCO{sub 3} (five samples). Analytical results from 1995-2003 were compared. During 2001-2003 in groundwater samples from sampling points PVP1, PVP9A and PP7 all measured main parameters changed considerably, but from summer 2003 to autumn 2004 the greatest alterations occurred in PR2, PVP1, PVP3A and PVP3B waters. These changes can be seen in almost all parameters. For other samples only minor changes in results were observed during the reference period. (orig.)

Natural and anthropogenic factors affecting the shallow groundwater quality in a typical irrigation area with reclaimed water, North China Plain.

Science.gov (United States)

Gu, Xiaomin; Xiao, Yong; Yin, Shiyang; Pan, Xingyao; Niu, Yong; Shao, Jingli; Cui, Yali; Zhang, Qiulan; Hao, Qichen

2017-09-22

In this study, the hydrochemical characteristics of shallow groundwater were analyzed to get insight into the factors affecting groundwater quality in a typical agricultural dominated area of the North China Plain. Forty-four shallow groundwater samples were collected for chemical analysis. The water type changes from Ca·Na-HCO 3 type in grass land to Ca·Na-Cl (+NO 3 ) type and Na (Ca)-Cl (+NO 3 +SO 4 ) type in construction and facility agricultural land, indicating the influence of human activities. The factor analysis and geostatistical analysis revealed that the two major factors contributing to the groundwater hydrochemical compositions were the water-rock interaction and contamination from sewage discharge and agricultural fertilizers. The major ions (F, HCO 3 ) and trace element (As) in the shallow groundwater represented the natural origin, while the nitrate and sulfate concentrations were related to the application of fertilizer and sewage discharge in the facility agricultural area, which was mainly affected by the human activities. The values of pH, total dissolved solids, electric conductivity, and conventional component (K, Ca, Na, Mg, Cl) in shallow groundwater increased from grass land and cultivated land, to construction land and to facility agriculture which were originated from the combination sources of natural processes (e.g., water-rock interaction) and human activities (e.g., domestic effluents). The study indicated that both natural processes and human activities had influences on the groundwater hydrochemical compositions in shallow groundwater, while anthropogenic processes had more contribution, especially in the reclaimed water irrigation area.

A comparison of forest and agricultural shallow groundwater chemical status a century after land use change

International Nuclear Information System (INIS)

Kellner, Elliott; Hubbart, Jason A.; Ikem, Abua

2015-01-01

Considering the increasing pace of global land use change and the importance of groundwater quality to humans and aquatic ecosystems, studies are needed that relate land use types to patterns of groundwater chemical composition. Piezometer grids were installed in a remnant bottomland hardwood forest (BHF) and a historic agricultural field (Ag) to compare groundwater chemical composition between sites with contrasting land use histories. Groundwater was sampled monthly from June 2011 to June 2013, and analyzed for 50 physiochemical metrics. Statistical tests indicated significant differences (p < 0.05) between the study sites for 32 out of 50 parameters. Compared to the Ag site, BHF groundwater was characterized by significantly (p < 0.05) lower pH, higher electrical conductivity, and higher concentrations of total dissolved solids and inorganic carbon. BHF groundwater contained significantly (p < 0.05) higher concentrations of all nitrogen species except nitrate, which was higher in Ag groundwater. BHF groundwater contained significantly (p < 0.05) higher concentrations of nutrients such as sulfur, potassium, magnesium, calcium, and sodium, relative to the Ag site. Ag groundwater was characterized by significantly (p < 0.05) higher concentrations of trace elements such as arsenic, cadmium, cobalt, copper, molybdenum, nickel, and titanium. Comparison of shallow groundwater chemical composition with that of nearby receiving water suggests that subsurface concentration patterns are the result of contrasting site hydrology and vegetation. Results detail impacts of surface vegetation alteration on subsurface chemistry and groundwater quality, thereby illustrating land use impacts on the lithosphere and hydrosphere. This study is among the first to comprehensively characterize and compare shallow groundwater chemical composition at sites with contrasting land use histories. - Highlights: • Shallow groundwater chemical composition was compared at floodplain sites. �

A comparison of forest and agricultural shallow groundwater chemical status a century after land use change

Energy Technology Data Exchange (ETDEWEB)

Kellner, Elliott, E-mail: rekfh3@mail.missouri.edu [School of Natural Resources, University of Missouri, Columbia, MO 65211 (United States); Hubbart, Jason A. [Water Resources Program, School of Natural Resources, Department of Forestry, University of Missouri, Columbia, MO 65211 (United States); Ikem, Abua, E-mail: Ikema@lincolnu.edu [Lincoln University, Department of Agriculture and Environmental Sciences, 204 Foster Hall, 904 Chestnut Street, Jefferson City, MO 65101 (United States)

2015-10-01

Considering the increasing pace of global land use change and the importance of groundwater quality to humans and aquatic ecosystems, studies are needed that relate land use types to patterns of groundwater chemical composition. Piezometer grids were installed in a remnant bottomland hardwood forest (BHF) and a historic agricultural field (Ag) to compare groundwater chemical composition between sites with contrasting land use histories. Groundwater was sampled monthly from June 2011 to June 2013, and analyzed for 50 physiochemical metrics. Statistical tests indicated significant differences (p < 0.05) between the study sites for 32 out of 50 parameters. Compared to the Ag site, BHF groundwater was characterized by significantly (p < 0.05) lower pH, higher electrical conductivity, and higher concentrations of total dissolved solids and inorganic carbon. BHF groundwater contained significantly (p < 0.05) higher concentrations of all nitrogen species except nitrate, which was higher in Ag groundwater. BHF groundwater contained significantly (p < 0.05) higher concentrations of nutrients such as sulfur, potassium, magnesium, calcium, and sodium, relative to the Ag site. Ag groundwater was characterized by significantly (p < 0.05) higher concentrations of trace elements such as arsenic, cadmium, cobalt, copper, molybdenum, nickel, and titanium. Comparison of shallow groundwater chemical composition with that of nearby receiving water suggests that subsurface concentration patterns are the result of contrasting site hydrology and vegetation. Results detail impacts of surface vegetation alteration on subsurface chemistry and groundwater quality, thereby illustrating land use impacts on the lithosphere and hydrosphere. This study is among the first to comprehensively characterize and compare shallow groundwater chemical composition at sites with contrasting land use histories. - Highlights: • Shallow groundwater chemical composition was compared at floodplain sites. �

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)

Groundwater quality in the shallow aquifers of the Tulare, Kaweah, and Tule Groundwater Basins and adjacent highlands areas, Southern San Joaquin Valley, California

Science.gov (United States)

Fram, Miranda S.

2017-01-18

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The shallow aquifers of the Tulare, Kaweah, and Tule groundwater basins and adjacent highlands areas of the southern San Joaquin Valley constitute one of the study units being evaluated.

Risk of diarrhoea from shallow groundwater contaminated with enteropathogens in the Kathmandu Valley, Nepal.

Science.gov (United States)

Shrestha, Sadhana; Haramoto, Eiji; Malla, Rabin; Nishida, Kei

2015-03-01

Shallow groundwater is the main water source among many alternatives in the Kathmandu Valley, Nepal, which has a rapidly growing population and intermittent piped water supply. Although human pathogens are detected in groundwater, its health effects are unclear. We estimated risk of diarrhoea from shallow groundwater use using quantitative microbial risk assessment. Escherichia coli, Giardia cyst and Cryptosporidium oocyst levels were analysed in dug and tube wells samples. E. coli concentrations were converted to those of enteropathogenic E. coli (EPEC). Risks from EPEC in dug wells and from Cryptosporidium and Giardia in both dug and tube wells were higher than the acceptable limit (water treatment decreased the risk six-fold and decreased risk overestimation. Because removal efficiency of POU water treatment has the largest impact on total risk, increasing the coverage and efficiency of POU water treatment could be a practical risk management strategy in the Kathmandu Valley and similar settings.

Presence of Antibiotics in Shallow Groundwater in the Northern and Southwestern Regions of China.

Science.gov (United States)

Chen, Liang; Lang, Hang; Liu, Fei; Jin, Song; Yan, Tao

2018-05-01

Antibiotics are widely used, and there is a serious concern about its adverse impacts on the environment and human health. To our knowledge, prior to this work, there was no evidence of the potential presence of antibiotics in groundwater in China, despite populous speculations. This study reported the detection of 35 target antibiotics of 6 groups (chloramphenicois, lincosamides, marcrolides, quinolones, sulfonamides, and tetracyclines), in shallow groundwater samples collected in northern and southwestern China. Thirty-four of thirty-five target antibiotics were detected in the groundwater samples; 73 of 74 monitoring wells contained at least one antibiotic; and at least two antibiotics were detected in 72 of the 74 wells. Ofloxacin (1199.7 ng/L), lincomycin (860.7 ng/L), and norfloxacin (441.9 ng/L) as well as antibiotics with the highest detection frequency such as sulfapyridine (70%), norfloxacin (69%), and lincomycin (64%) were detected at elevated concentrations. The highest detection frequency and concentration of lincosamides were observed in those groundwater samples, but no clear distribution patterns were observed for the six antibiotic groups. Moreover, shallow groundwater in southwestern China seemed to contain most antibiotics, likely due to the high antibiotics discharge and frequent exchange of groundwater with surface matrices. The findings from this work suggest that groundwater in China has been widely contaminated by antibiotics, and presumably other pharmaceutical compounds that have not been investigated to date. © 2017, National Ground Water Association.

Nitrate in shallow groundwater in typical agricultural and forest ecosystems in China, 2004-2010.

Science.gov (United States)

Zhang, Xinyu; Xu, Zhiwei; Sun, Xiaomin; Dong, Wenyi; Ballantine, Deborah

2013-05-01

The nitrate-nitrogen (NO3(-)-N) concentrations from shallow groundwater wells situated in 29 of the Chinese Ecosystem Research Network field stations, representing typical agro- and forest ecosystems, were assessed using monitoring data collected between 2004 and 2010. Results from this assessment permit a national scale assessment of nitrate concentrations in shallow groundwater, and allow linkages between nitrate concentrations in groundwater and broad land use categories to be made. Results indicated that most of the NO3(-)-N concentrations in groundwater from the agro- and forest ecosystems were below the Class 3 drinking water standard stated in the Chinese National Standard: Quality Standard for Ground Water (ecosystems (4.1 +/- 0.33 mg/L) than in forest ecosystems (0.5 +/- 0.04 mg/L). NO3(-)-N concentrations were relatively higher (> 10 mg N /L) in 10 of the 43 wells sampled in the agricultural ecosystems. These elevated concentrations occurred mainly in the Ansai, Yucheng, Linze, Fukang, Akesu, and Cele field sites, which were located in arid and semi-arid areas where irrigation rates are high. We suggest that improvements in N fertilizer application and irrigation management practices in the arid and semi-arid agricultural ecosystems of China are the key to managing groundwater nitrate concentrations.

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.

Sources and behaviour of nitrogen compounds in the shallow groundwater of agricultural areas (Poyang Lake basin, China).

Science.gov (United States)

Soldatova, Evgeniya; Guseva, Natalia; Sun, Zhanxue; Bychinsky, Valeriy; Boeckx, Pascal; Gao, Bai

2017-07-01

Nitrogen contamination of natural water is a typical problem for various territories throughout the world. One of the regions exposed to nitrogen pollution is located in the Poyang Lake basin. As a result of agricultural activity and dense population, the shallow groundwater of this area is characterised by a high concentration of nitrogen compounds, primarily NO 3 - , with the concentration varying from 0.1mg/L to 206mg/L. Locally, high ammonium content occurs in the shallow groundwater with low reduction potential Eh (shallow groundwater of the Poyang Lake basin has Eh>100mV. To identify sources of nitrogen species and the factors that determine their behaviour, the dual stable isotope approach (δ 15 N and δ 18 О) and physical-chemical modelling were applied. Actual data were collected by sampling shallow groundwater from domestic water supply wells around the lake. The δ 18 О values from -4.1‰ to 13.9‰ with an average value of 5.3 permille indicate a significant influence of nitrification on nitrogen balance. The enrichment of nitrate with the 15 N isotope indicates that manure and domestic sewage are the principal sources of nitrogen compounds. Inorganic nitrogen speciation and thermodynamic calculations demonstrate the high stability of nitrate in the studied groundwater. Computer simulation and field observations indicate the reducing conditions formed under joint effects of anthropogenic factors and appropriate natural conditions, such as the low-level topography in which decreased water exchange rate can occur. The simulation also demonstrates the growth in pH of the groundwater as a consequence of fertilisation, which, in turn, conduced to the clay mineral formation at lower concentrations of aqueous clay-forming components than the ones under the natural conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

A simplified model of soakaway infiltration interaction with a shallow groundwater table

DEFF Research Database (Denmark)

Roldin, Maria; Locatelli, Luca; Mark, Ole

2013-01-01

This paper presents a new and simplified modeling concept for soakaway infiltration in the presence of a shallow groundwater table, including representation of the local groundwater mound and its effects on the infiltration rate. The soil moisture retention curve is used to represent the influence......, and its effects on the infiltration rate, can be represented even if the spatial resolution of the groundwater flow model is coarser than the extent of the mound. The new model has been run for a number of scenarios and soil parameters, and the results compared to the output from a two...... of the mound on infiltration rates. The model is intended to be used in situations when distributed urban drainage models with soakaways or similar infiltration devices are coupled to distributed groundwater flow models. With this new modeling concept, the local mounding from small-scale infiltration systems...

Untangling the effects of shallow groundwater and deficit irrigation on irrigation water productivity in arid region: New conceptual model.

Science.gov (United States)

Xue, Jingyuan; Huo, Zailin; Wang, Fengxin; Kang, Shaozhong; Huang, Guanhua

2018-04-01

Water scarcity and salt stress are two main limitations for agricultural production. Groundwater evapotranspiration (ET g ) with upward salt movement plays an important role in crop water use and water productivity in arid regions, and it can compensate the impact of deficit irrigation on crop production. Thus, comprehensive impacts of shallow groundwater and deficit irrigation on crop water use results in an improvement of irrigation water productivity (IWP). However, it is difficult to quantify the effects of groundwater and deficit irrigation on IWP. In this study, we built an IWP evaluation model coupled with a water and salt balance model and a crop yield estimation model. As a valuable tool of IWP simulation, the calibrated model was used to investigate the coupling response of sunflower IWP to irrigation water depths (IWDs), groundwater table depth (GTDs) and groundwater salinities (GSs). A total of 210 scenarios were run in which five irrigation water depths (IWDs) and seven groundwater table depths (GTDs) and six groundwater salinities (GSs) were used. Results indicate that increasing GS clearly increases the negative effect on a crop's actual evapotranspiration (ET a ) as salt accumulation in root zone. When GS is low (0.5-1g/L), increasing GTD produces more positive effect than negative effect. In regard to relatively high GS (2-5g/L), the negative effect of shallow-saline groundwater reaches a maximum at 2m GTD. Additionally, the salt concentration in the root zone maximizes its value at 2.0m GTD. In most cases, increasing GTD and GS reduces the benefits of irrigation water and IWP. The IWP increases with decreasing irrigation water. Overall, in arid regions, capillary rise of shallow groundwater can compensate for the lack of irrigation water and improve IWP. By improving irrigation schedules and taking advantages of shallow saline groundwater, we can obtain higher IWP. Copyright © 2017 Elsevier B.V. All rights reserved.

Groundwater quality in the shallow aquifers of the Monterey Bay, Salinas Valley, and adjacent highland areas, California

Science.gov (United States)

Burton, Carmen

2018-05-30

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The shallow aquifers of the groundwater basins around Monterey Bay, the Salinas Valley, and the highlands adjacent to the Salinas Valley constitute one of the study units.

Occurrence of steroid hormones and antibiotics in shallow groundwater impacted by livestock waste control facilities

Science.gov (United States)

Bartelt-Hunt, Shannon; Snow, Daniel D.; Damon-Powell, Teyona; Miesbach, David

2011-04-01

Wastewater impoundments at concentrated animal feeding operations (CAFOs) represent a potential source of veterinary pharmaceuticals and steroid hormone contamination to shallow groundwater. This study investigates the occurrence of seventeen veterinary pharmaceuticals and thirteen steroid hormones and hormone metabolites in lagoons and adjacent groundwater at operating swine and beef cattle facilities. These sites were chosen because subsurface geology and previous monitoring of nitrate, ammonia and chloride levels in shallow ground water strongly indicated direct infiltration, and as such represent worst cases for ground water contamination by waste water. Pharmaceutical compounds detected in samples obtained from cattle facilities include sulfamerazine; sulfamethazine; erythromycin; monensin; tiamulin; and sulfathiazole. Lincomycin; ractopamine; sulfamethazine; sulfathiazole; erythromycin; tiamulin and sulfadimethoxine were detected in wastewater samples obtained from swine facilities. Steroid hormones were detected less frequently than veterinary pharmaceuticals in this study. Estrone, testosterone, 4-androstenedione, and androsterone were detected in wastewater impoundments at concentrations ranging from 30 to 3600 ng/L, while only estrone and testosterone were detected in groundwater samples at concentrations up to 390 ng/L. The co-occurrence of veterinary pharmaceutical and steroid hormone contamination in groundwater at these locations and the correlation between pharmaceutical occurrence in lagoon wastewater and hydraulically downgradient groundwater indicates that groundwater underlying some livestock wastewater impoundments is susceptible to contamination by veterinary pharmaceuticals and steroid hormones originating in wastewater lagoons.

Occurrence of steroid hormones and antibiotics in shallow groundwater impacted by livestock waste control facilities.

Science.gov (United States)

Bartelt-Hunt, Shannon; Snow, Daniel D; Damon-Powell, Teyona; Miesbach, David

2011-04-25

Wastewater impoundments at concentrated animal feeding operations (CAFOs) represent a potential source of veterinary pharmaceuticals and steroid hormone contamination to shallow groundwater. This study investigates the occurrence of seventeen veterinary pharmaceuticals and thirteen steroid hormones and hormone metabolites in lagoons and adjacent groundwater at operating swine and beef cattle facilities. These sites were chosen because subsurface geology and previous monitoring of nitrate, ammonia and chloride levels in shallow ground water strongly indicated direct infiltration, and as such represent worst cases for ground water contamination by waste water. Pharmaceutical compounds detected in samples obtained from cattle facilities include sulfamerazine; sulfamethazine; erythromycin; monensin; tiamulin; and sulfathiazole. Lincomycin; ractopamine; sulfamethazine; sulfathiazole; erythromycin; tiamulin and sulfadimethoxine were detected in wastewater samples obtained from swine facilities. Steroid hormones were detected less frequently than veterinary pharmaceuticals in this study. Estrone, testosterone, 4-androstenedione, and androsterone were detected in wastewater impoundments at concentrations ranging from 30 to 3600ng/L, while only estrone and testosterone were detected in groundwater samples at concentrations up to 390ng/L. The co-occurrence of veterinary pharmaceutical and steroid hormone contamination in groundwater at these locations and the correlation between pharmaceutical occurrence in lagoon wastewater and hydraulically downgradient groundwater indicates that groundwater underlying some livestock wastewater impoundments is susceptible to contamination by veterinary pharmaceuticals and steroid hormones originating in wastewater lagoons. Copyright © 2010 Elsevier B.V. All rights reserved.

Status and understanding of groundwater quality in the Monterey-Salinas Shallow Aquifer Study Unit, 2012–13: California GAMA Priority Basin Project

Science.gov (United States)

Burton, Carmen; Wright, Michael

2018-05-30

by anthropogenic sources. Nitrate concentrations were significantly higher in modern groundwater, indicating recent inputs of nitrate to the shallow aquifer system. Nitrate was positively correlated with agricultural land use, indicating that irrigation-return water could be leaching nitrogen fertilizer and naturally present nitrate to elevate nitrate concentrations in shallow groundwater.The salinity indicators total dissolved solids, chloride, and sulfate all had natural sources in the MS-SA study unit, primarily marine sediments. Concentrations of the constituents were elevated as a result of evaporative concentration of irrigation water or precipitation. Sulfate concentrations were significantly correlated to agricultural land use, indicating that agricultural land-use practices are a contributing source of sulfate to groundwater.The samples with most of the detections of VOCs were from sites in the Pajaro Valley and northern part of the Salinas Valley. Most of the samples with pesticide detections were from sites in the Salinas Valley study area. The herbicide simazine was positively correlated to the percentage of agricultural land use, and its concentrations were higher in modern groundwater than in pre-modern groundwater.Perchlorate, similar to nitrate, has natural and anthropogenic sources. Correlations of perchlorate to dissolved oxygen, nitrate, and percentage of agricultural land use indicated that the irrigation-return water could be leaching naturally present perchlorate, as well as perchlorate from historical applications of Chilean nitrate fertilizer, to increase perchlorate concentrations in groundwater.The quality of the water in the shallow aquifer system from this study was compared with the quality of water in the public drinking-water aquifer in a previous GAMA (MS-PA) study in the same area. The shallow system was more oxic and had more sites with modern groundwater than the public drinking-water aquifer, which was more anoxic and had sites

Characteristics of Leachate and Their Effect on Shallow Groundwater Quality (Case Study : TPA Cipayung, Depok)

Science.gov (United States)

Widiastuti, Atika; Hartono, Djoko M.; Moersidik, Setyo S.; Gusniani, Irma

2018-03-01

The problems arising from landfill activity is leaked leachate that is not absorbed well into leachate stabilization pond which furthermore contaminates shallow groundwater around landfill, include Cipayung landfill. The aims of this study is to determine the characteristics of leachate and their effect on shallow groundwater quality around landfill based on temperature, pH, Total Suspended Solids (TSS), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Nitrogen (TN), Mercury (Hg), and fecal coliform. Data were analyzed based on leachate samples at influent point, effluent point, and 7 sampling points of residents’s well with distance variation every 100 meters within 300 meters radius having leachate stabilization pond as benchmark. According to the standard of Indonesia’s Ministry of Environment and Forestry law No. 59 of 2016, the results showed that leachate quality was still above the standard of BOD, COD, and Total Nitrogen parameters; 4178.0 mg/L, 70556.0 mg/L and 373.3 mg/L for influent point, and 3142.0 mg/L, 9055.2 mg/L, and 350 mg/L for the effluent point. Pollution Index of shallow groundwater is between lightly and moderately contaminated. This study showed that the further the distance between sampling point and leachate stabilization pond is, the lower the Polution Index is.

Organic carbon input in shallow groundwater at Aspo, southeastern Sweden

International Nuclear Information System (INIS)

Wallin, B.

1993-01-01

The variation in carbon and oxygen isotopes in calcite fissure fillings and dissolved carbonate from shallow groundwaters has been examined at Aspo, southeastern Sweden. The shallow water lens is refilled by meteoric water and is considered as an open system. The σ 13 C-signatures of the dissolved carbonate fall within a narrow range of -15.8 to -17.4 per-thousand, indicative of organic an organic carbon source. The low σ 13 C-values suggest that input of soil-CO 2 is the dominating carbon source for the system. σ 13 C and σ 18 O-values in the calcite fissure fillings show a wide range in values with a possible two end-member mixing of early post glacial atmospheric CO 2 dominated system to a present day soil-CO 2 dominating carbon source

Septic Systems Contribution to Phosphorus in Shallow Groundwater: Field-Scale Studies Using Conventional Drainfield Designs.

Directory of Open Access Journals (Sweden)

Sara Mechtensimer

Full Text Available Septic systems can be a potential source of phosphorus (P in groundwater and contribute to eutrophication in aquatic systems. Our objective was to investigate P transport from two conventional septic systems (drip dispersal and gravel trench to shallow groundwater. Two new in-situ drainfields (6.1 m long by 0.61 m wide with a 3.72 m2 infiltrative surface were constructed. The drip dispersal drainfield was constructed by placing 30.5 cm commercial sand on top of natural soil and the gravel trench drainfield was constructed by placing 30.5 cm of gravel on top of 30.5 cm commercial sand and natural soil. Suction cup lysimeters were installed in the drainfields (at 30.5, 61, 106.7 cm below infiltrative surface and piezometers were installed in the groundwater (>300 cm below infiltrative surface to capture P dynamics from the continuum of unsaturated to saturated zones in the septic systems. Septic tank effluent (STE, soil-water, and groundwater samples were collected for 64 events (May 2012-Dec 2013 at 2 to 3 days (n = 13, weekly (n = 29, biweekly (n = 17, and monthly (n = 5 intervals. One piezometer was installed up-gradient of the drainfields to monitor background groundwater (n = 15. Samples were analyzed for total P (TP, orthophosphate-P (PO4-P, and other-P (TP-PO4-P. The gravel trench drainfield removed significantly (p300 cm in the groundwater, both systems had similar TP reductions of >97%. After 18 months of STE application, there was no significant increase in groundwater TP concentrations in both systems. We conclude that both drainfield designs are effective at reducing P transport to shallow groundwater.

Septic Systems Contribution to Phosphorus in Shallow Groundwater: Field-Scale Studies Using Conventional Drainfield Designs

Science.gov (United States)

Mechtensimer, Sara

2017-01-01

Septic systems can be a potential source of phosphorus (P) in groundwater and contribute to eutrophication in aquatic systems. Our objective was to investigate P transport from two conventional septic systems (drip dispersal and gravel trench) to shallow groundwater. Two new in-situ drainfields (6.1 m long by 0.61 m wide) with a 3.72 m2 infiltrative surface were constructed. The drip dispersal drainfield was constructed by placing 30.5 cm commercial sand on top of natural soil and the gravel trench drainfield was constructed by placing 30.5 cm of gravel on top of 30.5 cm commercial sand and natural soil. Suction cup lysimeters were installed in the drainfields (at 30.5, 61, 106.7 cm below infiltrative surface) and piezometers were installed in the groundwater (>300 cm below infiltrative surface) to capture P dynamics from the continuum of unsaturated to saturated zones in the septic systems. Septic tank effluent (STE), soil-water, and groundwater samples were collected for 64 events (May 2012–Dec 2013) at 2 to 3 days (n = 13), weekly (n = 29), biweekly (n = 17), and monthly (n = 5) intervals. One piezometer was installed up-gradient of the drainfields to monitor background groundwater (n = 15). Samples were analyzed for total P (TP), orthophosphate-P (PO4–P), and other–P (TP—PO4-P). The gravel trench drainfield removed significantly (p300 cm in the groundwater, both systems had similar TP reductions of >97%. After 18 months of STE application, there was no significant increase in groundwater TP concentrations in both systems. We conclude that both drainfield designs are effective at reducing P transport to shallow groundwater. PMID:28107505

3D modeling of groundwater heat transport in the shallow Westliches Leibnitzer Feld aquifer, Austria

Science.gov (United States)

Rock, Gerhard; Kupfersberger, Hans

2018-02-01

For the shallow Westliches Leibnitzer feld aquifer (45 km2) we applied the recently developed methodology by Kupfersberger et al. (2017a) to derive the thermal upper boundary for a 3D heat transport model from observed air temperatures. We distinguished between land uses of grass and agriculture, sealed surfaces, forest and water bodies. To represent the heat flux from heated buildings and the mixture between different land surfaces in urban areas we ran the 1D vertical heat conduction module SoilTemp which is coupled to the heat transport model (using FEFLOW) on a time step basis. Over a simulation period of 23 years the comparison between measured and observed groundwater temperatures yielded NSE values ranging from 0.41 to 0.92 including readings at different depths. The model results showed that the thermal input signals lead to distinctly different vertical groundwater temperature distributions. To overcome the influence of specific warm or cold years we introduced the computation of an annual averaged groundwater temperature profile. With respect to the use of groundwater cooling or heating facilities we evaluated the application of vertically averaged statistical groundwater temperature distributions compared to the use of temperature distributions at selected dates. We concluded that the heat transport model serves well as an aquifer scale management tool to optimize the use of the shallow subsurface for thermal purposes and to analyze the impacts of corresponding measures on groundwater temperatures.

Seasonal variations in the tritium content of groundwaters of the Vienna Basin, Austria

International Nuclear Information System (INIS)

Davis, G.H.; Payne, B.R.; Dincer, T.; Florkowski, T.; Gattinger, T.

1967-01-01

Monthly analyses of tritium from 22 sources of groundwater of the Vienna Basin have been made since April 1965 with a view to elucidating the complex groundwater surface water relations and ascertaining the movement of groundwaters. The sources are classified broadly into four groups: (1) Non-thermal springs including karst springs of the bordering mountains; (2) thermal springs rising along faults that border the floor of the Vienna Basin; (3) wells on the floor of the Basin; and (4) large groundwater overflows on the floor of the Basin. The following are among significant findings: All groundwaters sampled showed the effect of local recharge by high tritium precipitation in the exceptionally wet summer of 1965; Groundwater overflows thought to represent discharge from the main groundwater reservoir were generally higher in tritium than other groundwaters indicating rapid shallow circulation from nearby streams. Thermal springs believed representative of deep circulation all showed the effect of mixing with shallow waters recharged from current precipitation. All showed appreciable tritium content, even at the minimum levels. The highest tritium contents in well-waters were from the upper part of the Basin where water levels are very deep and streams lose water in crossing the alluvium. Well-waters in the area of shallow water in the lower Basin were generally lower in tritium than those of the upper Basin, but all showed the effect of recharge in the summer of 1965. Samples taken during drilling of a deep exploratory well show a decrease in tritium with depth, but even at 140 m depth the tritium content was 13 T.U. indicating relatively rapid circulation throughout thc principal aquifer. (author)

Shallow groundwater intrusion to deeper depths caused by construction and drainage of a large underground facility. Estimation using 3H, CFCs and SF6 as trace materials

International Nuclear Information System (INIS)

Hagiwara, Hiroki; Iwatsuki, Teruki; Hasegawa, Takuma; Nakata, Kotaro; Tomioka, Yuichi

2015-01-01

This study evaluates a method to estimate shallow groundwater intrusion in and around a large underground research facility (Mizunami Underground Research Laboratory-MIU). Water chemistry, stable isotopes (δD and δ 18 O), tritium ( 3 H), chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF 6 ) in groundwater were monitored around the facility (from 20 m down to a depth of 500 m), for a period of 5 years. The results show that shallow groundwater inflows into deeper groundwater at depths of between 200–400 m. In addition, the content of shallow groundwater estimated using 3 H and CFC-12 concentrations is up to a maximum of about 50%. This is interpreted as the impact on the groundwater environment caused by construction and operation of a large facility over several years. The concomitant use of 3 H and CFCs is an effective method to determine the extent of shallow groundwater inflow caused by construction of an underground facility. (author)

Intensive rice agriculture deteriorates the quality of shallow groundwater in a typical agricultural catchment in subtropical central China.

Science.gov (United States)

Wang, Yi; Li, Yuyuan; Li, Yong; Liu, Feng; Liu, Xinliang; Gong, Dianlin; Ma, Qiumei; Li, Wei; Wu, Jinshui

2015-09-01

High nitrogen (N) concentrations in rural domestic water supplies have been attributed to excessive agricultural N leaching into shallow groundwater systems; therefore, it is important to determine the impact of agriculture (e.g., rice production) on groundwater quality. To understand the impact of agricultural land use on the N concentrations in the shallow groundwater in subtropical central China, a large observation program was established to observe ammonium-N (NH4-N), nitrate-N (NO3-N), and total N (TN) concentrations in 161 groundwater observation wells from April 2010 to November 2012. The results indicated that the median values of NH4-N, NO3-N, and TN concentrations in the groundwater were 0.15, 0.39, and 1.38 mg N L(-1), respectively. A total of 36.3 % of the water samples were categorized as NH4-N pollution, and only a small portion of the samples were categorized as NO3-N pollution, based on the Chinese Environmental Quality Standards for Groundwater of GB/T 14848-93 (General Administration of Quality Supervision of China, 1993). These results indicated of moderate groundwater NH4-N pollution, which was mainly attributed to intensive rice agriculture with great N fertilizer application rates in the catchment. In addition, tea and vegetable fields showed higher groundwater NO3-N and TN concentrations than other agricultural land use types. The factorial correspondence analysis (FCA) suggested that the flooded agricultural land use types (e.g., single-rice and double-rice) had potential to impose NH4-N pollution, particularly in the soil exhausting season during from July to October. And, the great N fertilizer application rates could lead to a worse NO3-N and TN pollution in shallow groundwater. Hence, to protect groundwater quality and minimize NH4-N pollution, managing optimal fertilizer application and applying appropriate agricultural land use types should be implemented in the region.

Spatial characteristics of cadmium in topsoils in a typical e-waste recycling area in southeast China and its potential threat to shallow groundwater

Energy Technology Data Exchange (ETDEWEB)

Wu, Chunfa, E-mail: wchf1680@sina.com [Department of Agricultural Resources and Environment, Nanjing University of Information Science and Technology, 219 Ningliu Road, Nanjing 210044 (China); Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008 (China); Luo, Yongming [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008 (China); Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 17 Chunhui Rd, Yantai 264003 (China); Deng, Shaopo; Teng, Ying; Song, Jing [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Road, Nanjing 210008 (China)

2014-02-01

Informal electrical and electronic waste (e-waste) recycling often creates secondary sources of cadmium (Cd) pollution. To characterize the total Cd concentration (Cd{sub total}) in topsoil and evaluate the threat of Cd in topsoils to shallow groundwater, 187 topsoil samples and 12 shallow groundwater samples were collected in a typical e-waste recycling area in southeast China. Soil organic matter content, soil pH and Cd{sub total} in topsoil, pH and dissolved Cd concentration in shallow groundwater were measured. Cd{sub total} in the topsoils showed an inverse distribution trend with soil pH in that high Cd concentrations (and low pH values) were found in the surrounding area of the metal recycling industrial park where there were many family-operated e-waste recycling facilities before the industrial park was established and with low concentrations (and high pH values) in other areas, and they had similar spatial correlation structures. Cd accumulation and acidification were synchronous in topsoils, and soil pH was significantly correlated with Cd{sub total} in topsoils with low to moderate negative correlation coefficient (r = − 0.24), indicating that both of them maybe correlated with informal recycling. The shallow groundwater in the surrounding area of the metal recycling industrial park was seriously contaminated by Cd, and topsoil Cd accumulation and acidification in the surrounding area of e-waste recycling sites significantly increase the risk of shallow groundwater contaminated by Cd. Action is urgently required to control Cd accumulation and acidification by improving the recycling operations of e-wastes in order to reduce the risk of Cd leaching from topsoils and shallow groundwater contamination. - Highlights: • We characterize the Cd{sub total} in topsoils, pH and SOM in a typical e-waste recycling area. • The relationships between Cd{sub total} in topsoils, pH, and SOM were studied. • Impact of topsoil Cd accumulation and acidification on

Spatial characteristics of cadmium in topsoils in a typical e-waste recycling area in southeast China and its potential threat to shallow groundwater

International Nuclear Information System (INIS)

Wu, Chunfa; Luo, Yongming; Deng, Shaopo; Teng, Ying; Song, Jing

2014-01-01

Informal electrical and electronic waste (e-waste) recycling often creates secondary sources of cadmium (Cd) pollution. To characterize the total Cd concentration (Cd total ) in topsoil and evaluate the threat of Cd in topsoils to shallow groundwater, 187 topsoil samples and 12 shallow groundwater samples were collected in a typical e-waste recycling area in southeast China. Soil organic matter content, soil pH and Cd total in topsoil, pH and dissolved Cd concentration in shallow groundwater were measured. Cd total in the topsoils showed an inverse distribution trend with soil pH in that high Cd concentrations (and low pH values) were found in the surrounding area of the metal recycling industrial park where there were many family-operated e-waste recycling facilities before the industrial park was established and with low concentrations (and high pH values) in other areas, and they had similar spatial correlation structures. Cd accumulation and acidification were synchronous in topsoils, and soil pH was significantly correlated with Cd total in topsoils with low to moderate negative correlation coefficient (r = − 0.24), indicating that both of them maybe correlated with informal recycling. The shallow groundwater in the surrounding area of the metal recycling industrial park was seriously contaminated by Cd, and topsoil Cd accumulation and acidification in the surrounding area of e-waste recycling sites significantly increase the risk of shallow groundwater contaminated by Cd. Action is urgently required to control Cd accumulation and acidification by improving the recycling operations of e-wastes in order to reduce the risk of Cd leaching from topsoils and shallow groundwater contamination. - Highlights: • We characterize the Cd total in topsoils, pH and SOM in a typical e-waste recycling area. • The relationships between Cd total in topsoils, pH, and SOM were studied. • Impact of topsoil Cd accumulation and acidification on shallow groundwater quality

In situ precipitation and sorption of arsenic from groundwater: Laboratory and ex situ field tests

International Nuclear Information System (INIS)

Whang, J.M.; Adu-Wusu, K.; Frampton, W.H.; Staib, J.G.

1997-01-01

Permeable, reactive walls may provide long term, low-maintenance prevention of off-site migration of contaminated groundwater. Laboratory and ex situ field tests conducted on several arsenic-contaminated groundwaters indicate that both precipitation and sorption can remove arsenic to levels of less than 10 ppb. Precipitation has been induced by adjusting pH, adding selected cations, and/or reducing the oxidation-reduction potential. Adjusting pH or adding cations was most effective when there were high levels of other ionic species with which arsenic could coprecipitate. Reducing the oxidation-reduction potential was effective on a variety of groundwaters. Humate was an effective sorbent at low pH; aluminum and iron materials were effective over a large range of conditions. Long term performance of precipitation systems can be limited by formation of precipitate on reactive surfaces. Long term sorption can be reduced by competing ions, such as phosphate. Laboratory and ex situ field tests indicate that reactive walls may have lifetimes of decades or more

Spatial characteristics of cadmium in topsoils in a typical e-waste recycling area in southeast China and its potential threat to shallow groundwater.

Science.gov (United States)

Wu, Chunfa; Luo, Yongming; Deng, Shaopo; Teng, Ying; Song, Jing

2014-02-15

Informal electrical and electronic waste (e-waste) recycling often creates secondary sources of cadmium (Cd) pollution. To characterize the total Cd concentration (Cdtotal) in topsoil and evaluate the threat of Cd in topsoils to shallow groundwater, 187 topsoil samples and 12 shallow groundwater samples were collected in a typical e-waste recycling area in southeast China. Soil organic matter content, soil pH and Cdtotal in topsoil, pH and dissolved Cd concentration in shallow groundwater were measured. Cdtotal in the topsoils showed an inverse distribution trend with soil pH in that high Cd concentrations (and low pH values) were found in the surrounding area of the metal recycling industrial park where there were many family-operated e-waste recycling facilities before the industrial park was established and with low concentrations (and high pH values) in other areas, and they had similar spatial correlation structures. Cd accumulation and acidification were synchronous in topsoils, and soil pH was significantly correlated with Cdtotal in topsoils with low to moderate negative correlation coefficient (r=-0.24), indicating that both of them maybe correlated with informal recycling. The shallow groundwater in the surrounding area of the metal recycling industrial park was seriously contaminated by Cd, and topsoil Cd accumulation and acidification in the surrounding area of e-waste recycling sites significantly increase the risk of shallow groundwater contaminated by Cd. Action is urgently required to control Cd accumulation and acidification by improving the recycling operations of e-wastes in order to reduce the risk of Cd leaching from topsoils and shallow groundwater contamination. Copyright © 2013. Published by Elsevier B.V.

Reconnoitering the effect of shallow groundwater on land surface temperature and surface energy balance using MODIS and SEBS

Directory of Open Access Journals (Sweden)

F. Alkhaier

2012-07-01

Full Text Available The possibility of observing shallow groundwater depth and areal extent using satellite measurements can support groundwater models and vast irrigation systems management. Moreover, these measurements can help to include the effect of shallow groundwater on surface energy balance within land surface models and climate studies, which broadens the methods that yield more reliable and informative results. To examine the capacity of MODIS in detecting the effect of shallow groundwater on land surface temperature and the surface energy balance in an area within Al-Balikh River basin in northern Syria, we studied the interrelationship between in-situ measured water table depths and land surface temperatures measured by MODIS. We, also, used the Surface Energy Balance System (SEBS to calculate surface energy fluxes, evaporative fraction and daily evaporation, and inspected their relationships with water table depths. We found out that the daytime temperature increased while the nighttime temperature decreased when the depth of the water table increased. And, when the water table depth increased, net radiation, latent and ground heat fluxes, evaporative fraction and daily evaporation decreased, while sensible heat flux increased. This concords with the findings of a companion paper (Alkhaier et al., 2012. The observed clear relationships were the result of meeting both conditions that were concluded in the companion paper, i.e. high potential evaporation and big contrast in day-night temperature. Moreover, the prevailing conditions in this study area helped SEBS to yield accurate estimates. Under bare soil conditions and under the prevailing weather conditions, we conclude that MODIS is suitable for detecting the effect of shallow groundwater because it has proper imaging times and adequate sensor accuracy; nevertheless, its coarse spatial resolution is disadvantageous.

Geochemical and isotopic variations in shallow groundwater in areas of the Fayetteville Shale development, north-central Arkansas

International Nuclear Information System (INIS)

Warner, Nathaniel R.; Kresse, Timothy M.; Hays, Phillip D.; Down, Adrian; Karr, Jonathan D.; Jackson, Robert B.; Vengosh, Avner

2013-01-01

Highlights: • No evidence for shallow groundwater contamination in Fayetteville Shale, Arkansas. • Methane in groundwater is low and likely associated with shallow aquifer processes. • No relationship between methane and salinity in groundwater and shale-gas wells. • δ 13 C CH4 and δ 13 C DIC suggest biogenic origin for dissolved methane. • Water-aquifer rock interaction controls majority of water chemistry. - Abstract: Exploration of unconventional natural gas reservoirs such as impermeable shale basins through the use of horizontal drilling and hydraulic fracturing has changed the energy landscape in the USA providing a vast new energy source. The accelerated production of natural gas has triggered a debate concerning the safety and possible environmental impacts of these operations. This study investigates one of the critical aspects of the environmental effects; the possible degradation of water quality in shallow aquifers overlying producing shale formations. The geochemistry of domestic groundwater wells was investigated in aquifers overlying the Fayetteville Shale in north-central Arkansas, where approximately 4000 wells have been drilled since 2004 to extract unconventional natural gas. Monitoring was performed on 127 drinking water wells and the geochemistry of major ions, trace metals, CH 4 gas content and its C isotopes (δ 13 C CH4 ), and select isotope tracers (δ 11 B, 87 Sr/ 86 Sr, δ 2 H, δ 18 O, δ 13 C DIC ) compared to the composition of flowback-water samples directly from Fayetteville Shale gas wells. Dissolved CH 4 was detected in 63% of the drinking-water wells (32 of 51 samples), but only six wells exceeded concentrations of 0.5 mg CH 4 /L. The δ 13 C CH4 of dissolved CH 4 ranged from −42.3‰ to −74.7‰, with the most negative values characteristic of a biogenic source also associated with the highest observed CH 4 concentrations, with a possible minor contribution of trace amounts of thermogenic CH 4 . The majority of

An Assessment of Peri-Urban Groundwater Quality from Shallow Dug Wells, Mzuzu, Malawi

Science.gov (United States)

Holm, R.; Felsot, A.

2012-12-01

Throughout Malawi, governmental, non-governmental, religious and civic organizations are targeting the human need for water. Diarrheal diseases, often associated with unsafe drinking water, are a leading cause of mortality in children under five in Malawi with over 6,000 deaths per year (World Health Organization, 2010). From January to March 2012, a field study was undertaken in Malawi to study water quality and develop a public health risk communication strategy. The region studied, Area 1B, represents a comparatively new peri-urban area on the edge of Mzuzu city. Area 1B is serviced by a piped municipal water supply, but many shallow dug wells are also used for household water. Groundwater samples were collected from 30 shallow dug well sites and analyzed for nitrate, total coliform, Escherichia coli, total hardness, total alkalinity and pH. In addition to water quality analyses, a structured household questionnaire was administered to address water use, sanitation, health, consumption patterns, and socioeconomics. Results showed that more than half of the groundwater samples would be considered of unacceptable quality based on World Health Organization (WHO) standards for E. coli contamination. Low levels of nitrate were found in groundwater, but only one well exceeded WHO standards. The structured questionnaire revealed that some residents were still consuming groundwater despite the access to safer municipal water. In general, the widespread E. coli contamination was not statistically correlated with well depth, latrine proximity, or surface features. Similarly, nitrate concentrations were not significantly correlated with proximity to latrines. On the other hand, nitrate was correlated with well depth, which is expected given the high potential for leaching of anionic highly water soluble compounds. E. coli was significantly correlated with nitrate concentration. Projects targeting the need for clean water need to recognize that households with access to a

Assessing Changes in Precipitation and Impacts on Groundwater in Southeastern Brazil using Regional Hydroclimate Reconstruction

Science.gov (United States)

Nunes, A.; Fernandes, M.; Silva, G. C., Jr.

2017-12-01

Aquifers can be key players in regional water resources. Precipitation infiltration is the most relevant process in recharging the aquifers. In that regard, understanding precipitation changes and impacts on the hydrological cycle helps in the assessment of groundwater availability from the aquifers. Regional modeling systems can provide precipitation, near-surface air temperature, together with soil moisture at different ground levels from coupled land-surface schemes. More accurate those variables are better the evaluation of the precipitation impact on the groundwater. Downscaling of global reanalysis very often employs regional modeling systems, in order to give more detailed information for impact assessment studies at regional scales. In particular, the regional modeling system, Satellite-enhanced Regional Downscaling for Applied Studies (SRDAS), might improve the accuracy of hydrometeorological variables in regions with spatial and temporal scarcity of in-situ observations. SRDAS combines assimilation of precipitation estimates from gauge-corrected satellite-based products with spectral nudging technique. The SRDAS hourly outputs provide monthly means of atmospheric and land-surface variables, including precipitation, used in the calculations of the hydrological budget terms. Results show the impact of changes in precipitation on groundwater in the aquifer located near the southeastern coastline of Brazil, through the assessment of the water-cycle terms, using a hydrological model during dry and rainy periods found in the 15-year numerical integration of SRDAS.

Spatial and temporal small-scale variation in groundwater quality of a shallow sandy aquifer

DEFF Research Database (Denmark)

Bjerg, Poul Løgstrup; Christensen, Thomas Højlund

1992-01-01

The groundwater quality of a shallow unconfined sandy aquifer has been characterized for pH, alkalinity, chloride, nitrate, sulfate, calcium, magnesium, sodium and potassium in terms of vertical and horizontal variations (350 groundwater samples). The test area is located within a farmland lot....... The geology of the area described on the basis of 31 sediment cores appears relatively homogeneous. Large vertical and horizontal variations were observed. The vertical variations are strongly affected by the deviating composition of the agricultural infiltration water. The horizontal variations show very...

Comparison of physico-chemical parameters of groundwater from shallow aquifers near 2 thermal power plants in Punjab

International Nuclear Information System (INIS)

Gill, S.K.; Sahota, S.K.; Sahota, G.P.S.; Sahota, B.K.; Sahota, H.S.

1993-01-01

Physico-chemical parameters of groundwater from shallow aquifers near thermal power plants at Bathinda and Ropar have been measured. Increase in metallic content of water is noted in both the cases due to deposition of coal fly ash from the power plants on the soil. High values of calcium chloride, calcium carbonate and total dissolved solids are observed in Bathinda groundwater while Ropar groundwater is rich in ferric, fluoride and nitrate contents. (author). 8 refs., 1 fig., 1 tab

Sources and behaviour of nitrogen compounds in the shallow groundwater of agricultural areas (Poyang Lake basin, China)

Science.gov (United States)

Soldatova, Evgeniya; Guseva, Natalia; Sun, Zhanxue; Bychinsky, Valeriy; Boeckx, Pascal; Gao, Bai

2017-07-01

Nitrogen contamination of natural water is a typical problem for various territories throughout the world. One of the regions exposed to nitrogen pollution is located in the Poyang Lake basin. As a result of agricultural activity and dense population, the shallow groundwater of this area is characterised by a high concentration of nitrogen compounds, primarily NO3-, with the concentration varying from 0.1 mg/L to 206 mg/L. Locally, high ammonium content occurs in the shallow groundwater with low reduction potential Eh ( 100 mV. To identify sources of nitrogen species and the factors that determine their behaviour, the dual stable isotope approach (δ15N and δ18О) and physical-chemical modelling were applied. Actual data were collected by sampling shallow groundwater from domestic water supply wells around the lake. The δ18О values from - 4.1‰ to 13.9‰ with an average value of 5.3 permille indicate a significant influence of nitrification on nitrogen balance. The enrichment of nitrate with the 15N isotope indicates that manure and domestic sewage are the principal sources of nitrogen compounds. Inorganic nitrogen speciation and thermodynamic calculations demonstrate the high stability of nitrate in the studied groundwater. Computer simulation and field observations indicate the reducing conditions formed under joint effects of anthropogenic factors and appropriate natural conditions, such as the low-level topography in which decreased water exchange rate can occur. The simulation also demonstrates the growth in pH of the groundwater as a consequence of fertilisation, which, in turn, conduced to the clay mineral formation at lower concentrations of aqueous clay-forming components than the ones under the natural conditions.

Groundwater-quality data in the North San Francisco Bay Shallow Aquifer study unit, 2012: results from the California GAMA Program

Science.gov (United States)

Bennett, George L.; Fram, Miranda S.

2014-01-01

Groundwater quality in the 1,850-square-mile North San Francisco Bay Shallow Aquifer (NSF-SA) study unit was investigated by the U.S. Geological Survey (USGS) from April to August 2012, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program’s Priority Basin Project (PBP). The GAMA-PBP was developed in response to the California Groundwater Quality Monitoring Act of 2001 and is being conducted in collaboration with the SWRCB and Lawrence Livermore National Laboratory (LLNL). The NSF-SA study unit was the first study unit to be sampled as part of the second phase of the GAMA-PBP, which focuses on the shallow aquifer system.

Precipitation patterns and moisture fluxes in a sandy, tropical environment with a shallow water table

Science.gov (United States)

Minihane, M. R.; Freyberg, D. L.

2011-08-01

Identifying the dominant mechanisms controlling recharge in shallow sandy soils in tropical climates has received relatively little attention. Given the expansion of coastal fill using marine sands and the growth of coastal populations throughout the tropics, there is a need to better understand the nature of water balances in these settings. We use time series of field observations at a coastal landfill in Singapore coupled with numerical modeling using the Richards' equation to examine the impact of precipitation patterns on soil moisture dynamics, including percolation past the root zone and recharge, in such an environment. A threshold in total precipitation event depth, much more so than peak precipitation intensity, is the strongest event control on recharge. However, shallow antecedent moisture, and therefore the timing between events along with the seasonal depth to water table, also play significant roles in determining recharge amounts. For example, at our field site, precipitation events of less than 3 mm per event yield little to no direct recharge, but for larger events, moisture content changes below the root zone are linearly correlated to the product of the average antecedent moisture content and the total event precipitation. Therefore, water resources planners need to consider identifying threshold precipitation volumes, along with the multiple time scales that capture variability in event antecedent conditions and storm frequency in assessing the role of recharge in coastal water balances in tropical settings.

Groundwater-quality data in the Monterey–Salinas shallow aquifer study unit, 2013: Results from the California GAMA Program

Science.gov (United States)

Goldrath, Dara A.; Kulongoski, Justin T.; Davis, Tracy A.

2016-09-01

Groundwater quality in the 3,016-square-mile Monterey–Salinas Shallow Aquifer study unit was investigated by the U.S. Geological Survey (USGS) from October 2012 to May 2013 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program’s Priority Basin Project. The GAMA Monterey–Salinas Shallow Aquifer study was designed to provide a spatially unbiased assessment of untreated-groundwater quality in the shallow-aquifer systems in parts of Monterey and San Luis Obispo Counties and to facilitate statistically consistent comparisons of untreated-groundwater quality throughout California. The shallow-aquifer system in the Monterey–Salinas Shallow Aquifer study unit was defined as those parts of the aquifer system shallower than the perforated depth intervals of public-supply wells, which generally corresponds to the part of the aquifer system used by domestic wells. Groundwater quality in the shallow aquifers can differ from the quality in the deeper water-bearing zones; shallow groundwater can be more vulnerable to surficial contamination.Samples were collected from 170 sites that were selected by using a spatially distributed, randomized grid-based method. The study unit was divided into 4 study areas, each study area was divided into grid cells, and 1 well was sampled in each of the 100 grid cells (grid wells). The grid wells were domestic wells or wells with screen depths similar to those in nearby domestic wells. A greater spatial density of data was achieved in 2 of the study areas by dividing grid cells in those study areas into subcells, and in 70 subcells, samples were collected from exterior faucets at sites where there were domestic wells or wells with screen depths similar to those in nearby domestic wells (shallow-well tap sites).Field water-quality indicators (dissolved oxygen, water temperature, pH, and specific conductance) were measured, and samples for analysis of inorganic

[Assessment of shallow groundwater nitrate concentrations in typical terrestrial ecosystems of Chinese Ecosystem Research Network (CERN) during 2004-2009].

Science.gov (United States)

Xu, Zhi-Wei; Zhang, Xin-Yu; Sun, Xiao-Min; Yuan, Guo-Fu; Wang, Sheng-Zhong; Liu, Wen-Hua

2011-10-01

The nitrate-N (NO3(-) -N) concentrations of 38 shallow groundwater wells from 31 of the typical terrestrial ecosystems on Chinese Ecosystem Research Network (CERN) were assessed using the monitoring data from 2004 to 2009. The results showed that the average values of NO3(-) -N concentrations were significantly higher in the agricultural (4.85 mg x L(-1) +/- 0.42 mg x L(-1)), desert (oasis) (3.72 mg x L(-1) +/- 0.42 mg x L(-1)) and urban ecosystems (3.77 mg x L(-1) 0.51 mg x L(-1)) than in the grass (1.59 mg x L(-1) +/- 0.35 mg L(-1)) and forest ecosystems (0.39 mg x L(-1) +/- 0.03 mg x L(-1)). Nitrate was the major form of nitrogen, with between 56% to 88% of nitrogen in the nitrate-N form in the shallow groundwater of desert (oasis), urban and agricultural ecosystems. Nitrate-N concentrations for some agricultural ecosystems (Ansai, Yanting, Yucheng) and desert (oasis) ecosystems (Cele, Linze, Akesu) analysis exceeded the 10 mg x L(-1) World Health Organization drinking water standards between 14.3% and 84.6%. Significant seasonality was found in Ansai, Fengqiu, Yanting agricultural ecosystems and the Beijing urban ecosystem using the relatively high frequency monitoring data, with the higher nitrate concentrations usually found during summer and winter months. The monitoring results indicated that the shallow groundwater of agricultural ecosystems was contaminated by agricultural management practices, i.e. fertilization, while the shallow groundwater of forest ecosystems was under natural condition with no contamination from human activities.

Solute transport dynamics in small, shallow groundwater-dominated agricultural catchments: insights from a high-frequency, multisolute 10 yr-long monitoring study

Directory of Open Access Journals (Sweden)

A. H. Aubert

2013-04-01

Full Text Available High-frequency, long-term and multisolute measurements are required to assess the impact of human pressures on water quality due to (i the high temporal and spatial variability of climate and human activity and (ii the fact that chemical solutes combine short- and long-term dynamics. Such data series are scarce. This study, based on an original and unpublished time series from the Kervidy-Naizin headwater catchment (Brittany, France, aims to determine solute transfer processes and dynamics that characterise this strongly human-impacted catchment. The Kervidy-Naizin catchment is a temperate, intensive agricultural catchment, hydrologically controlled by shallow groundwater. Over 10 yr, five solutes (nitrate, sulphate, chloride, and dissolved organic and inorganic carbon were monitored daily at the catchment outlet and roughly every four months in the shallow groundwater. The concentrations of all five solutes showed seasonal variations but the patterns of the variations differed from one solute to another. Nitrate and chloride exhibit rather smooth variations. In contrast, sulphate as well as organic and inorganic carbon is dominated by flood flushes. The observed nitrate and chloride patterns are typical of an intensive agricultural catchment hydrologically controlled by shallow groundwater. Nitrate and chloride originating mainly from organic fertilisers accumulated over several years in the shallow groundwater. They are seasonally exported when upland groundwater connects with the stream during the wet season. Conversely, sulphate as well as organic and inorganic carbon patterns are not specific to agricultural catchments. These solutes do not come from fertilisers and do not accumulate in soil or shallow groundwater; instead, they are biogeochemically produced in the catchment. The results allowed development of a generic classification system based on the specific temporal patterns and source locations of each solute. It also considers the

Influence of the tension-saturated zone on contaminant migration in shallow water-table regimes

International Nuclear Information System (INIS)

Gillham, R.W.

1982-01-01

Groundwater discharge represents a major pathway for the return to the biosphere of contaminants that are released to the subsurface environment. An understanding of the transport processes in groundwater discharge zones is therefore an important consideration in pathway analyses associated with the environmental assessment of proposed waste-management facilities. Shallow water tables are a common characteristic of groundwater discharge zones, particularly in humid climatic regions. In this paper, the results of field tests, laboratory tests and numerical simulations are used to show that under shallow water-table conditions, the zone of tension saturation can result in a rapid and highly disproportionate water-table response to precipitation. It is further shown that this response can result in complex migration patterns that would not be predicted by the classical approaches to solute transport modelling and that the response could result in large and highly transient inputs to surface water

Microbiology of transitional groundwater of the porous overburden and underlying shallow fractured bedrock aquifers in Olkiluoto, Finland. October 2005 - January 2006

International Nuclear Information System (INIS)

Pedersen, K.

2007-05-01

The subsurface biosphere on Earth appears to be far more expansive and metabolically and phylogenetically complex than previously thought. A diverse suite of subsurface environments has been reported to support microbial ecosystems, extending from a few meters below the surface to several thousand meters. The discovery of a deep biosphere will have several important implications for underground repositories for radioactive wastes. The main potential effects of microorganisms in the context of a KBS-3 type repository for spent fuel in the bedrock of Olkiluoto are: (1) Oxygen reduction and maintenance of anoxic and reduced conditions. (2) Bio-immobilisation and bio-mobilisation of radionuclides, and the effects from microbial metabolism on radionuclide mobility. (3) Sulphate reduction to sulphide and the risk for copper sulphide corrosion. The main objective of this study was to characterize the geochemistry, biomass and microbial diversity of shallow subsurface groundwater at Olkiluoto, from 4.0 m down to 14.9 m. This objective also permitted the determination of whether or not there is any transition in the shallow depths at Olkiluoto to microbial conditions associated with the deep subsurface. This was the second investigation that covered both shallow and some moderately deep groundwater microbiology in Olkiluoto. The analysis of microbiology is very important for proper understanding of the evolution of geochemical processes in and around the underground research facility ONKALO being constructed at Olkiluoto by Posiva since autumn 2004, as well as for the planned KBS-3 type spent fuel repository at Olkiluoto. There are several conclusions from this investigation that are of importance for ONKALO. The following present day conclusions can be drawn. Continued investigations will update and test them: The shallow biosphere was dominated by oxygen consuming microorganisms that block oxygen migration to deeper groundwater. This effect was most pronounced during the

Dissolved gasesous hydrocarbons in shallow groundwater of Lower Saxony, Germany - Revisited 2016

Science.gov (United States)

Schloemer, Stefan; Illing, Christian J.; Blumenberg, Martin; Oest, Johanna; Elbracht, Jörg

2017-04-01

Many concerns arise within the public and government/political institutions over potential groundwater contamination from deep drilling operations. For this reason we initiated a baseline study in 2014 on the distribution of dissolved methane, ethane and propane in shallow groundwater ( 1000 groundwater wells, Schloemer et al., 2016) of Lower Saxony, which includes the major petroleum and natural gas provinces in Germany. We observed a variation of dissolved methane concentration over 7 orders of magnitude (20 nl/l to 60 ml/l [v/v]). Methane delta13C compositions ranged from -110‰ to +25‰ vs VPDB, narrowly clustering around -70‰ at high concentrations but being increasingly more variable at lower concentrations (-40‰ to -80‰)). Most of the data are clearly indicative for methanogenic processes, samples unusually enriched in delta13C can best be explained by secondary methane oxidation. Although some general regional trend can be observed, results are highly variable within short lateral distances or within different aquifers/filter depths. Frequently ethane (27% of samples, median 50nl/l) and occasionally propane (8%, median 23nl/l) has been detected. Lacking the carbon isotope composition of these homologues and thus solely based on the extremely low concentrations and atypical ethane/propane ratios, these have been tentatively interpreted as ubiquitous microbial background. From the original 2014 sample set around 100 wells have been selected for consecutive testing through 2015. In spring 2016 a total number of 1100 wells have been sampled, 700 of which had already been part of the initial study, providing us with the unique opportunity to assess long term variations. The overall comparison of these 700 samples revealed only small relative variations in methane concentrations (mostly ± 5‰ in 25% of samples). Minor variations could be related to uncertainties in laboratory analysis (± 10% in concentration, ± 0.5‰ delta13C). To which extent the

Hydrogeology and water quality of the shallow ground-water system in eastern York County, Virginia. Water resources investigation

International Nuclear Information System (INIS)

1993-01-01

The report describes the hydrogeology and water quality of the shallow ground-water system in the eastern part of York County, Va. The report includes a discussion of (1) the aquifers and confining units, (2) the flow of ground water, and (3) the quality of ground water. The report is an evaluation of the shallow ground-water system and focuses on the first 200 ft of sediments below land surface. Historical water-level and water-quality data were not available for the study area; therefore, a network of observation wells was constructed for the study. Water levels were measured to provide an understanding of the flow of ground water through the multiaquifer system. Water samples were collected and analyzed for major inorganic constituents, nutrients, and metals. The report presents maps that show the regional distribution of chloride and iron concentrations. Summary statistics and graphical summaries of selected chemical constituents provide a general assessment of the ground-water quality

Relating groundwater to seasonal wetlands in southeastern Wisconsin, USA

Science.gov (United States)

Skalbeck, J.D.; Reed, D.M.; Hunt, R.J.; Lambert, J.D.

2009-01-01

Historically, drier types of wetlands have been difficult to characterize and are not well researched. Nonetheless, they are considered to reflect the precipitation history with little, if any, regard for possible relation to groundwater. Two seasonal coastal wetland types (wet prairie, sedge meadow) were investigated during three growing seasons at three sites in the Lake Michigan Basin, Wisconsin, USA. The six seasonal wetlands were characterized using standard soil and vegetation techniques and groundwater measurements from the shallow and deep systems. They all met wetland hydrology criteria (e.g., water within 30 cm of land surface for 5% of the growing season) during the early portion of the growing season despite the lack of appreciable regional groundwater discharge into the wetland root zones. Although root-zone duration analyses did not fit a lognormal distribution previously noted in groundwater-dominated wetlands, they were able to discriminate between the plant communities and showed that wet prairie communities had shorter durations of continuous soil saturation than sedge meadow communities. These results demonstrate that the relative rates of groundwater outflows can be important for wetland hydrology and resulting wetland type. Thus, regional stresses to the shallow groundwater system such as pumping or low Great Lake levels can be expected to affect even drier wetland types. ?? Springer-Verlag 2008.

Study of interaction of shallow groundwater and river along the Cisadane and Ciliwung river of Jakarta basin and its management using environmental isotopes

International Nuclear Information System (INIS)

Sidauruk, P.; Syafalni; Satrio

2012-01-01

The environmental isotopes were employed to study the interaction of shallow groundwater and river along the Cisadane River and Ciliwung River in Jakarta basin. The rapid growth and development of Jakarta and its surrounding cities, coupled with increasing industrial and other business sectors have impacted on the demand of the water supply for the area. These investigations have been conducted to determine the interaction between shallow groundwater and the river. The 14 C results showed that the groundwater samples (above 40 m) which were close to the river influenced the iso-age contour of 14 C, which indicated the contributions of river water. The analysis of stable isotopes 18 O and Deuterium from the river implied that the river water from upstream to downstream was influenced by the mixing of the river water with the human activities in the upstream (the isotopic compositions becoming enriched). Further, the 18 O and Deuterium data revealed that rivers of Cisadane and Ciliwung are contributing to recharge the shallow groundwater in Jakarta, especially in the nearby river bank. In general, the quality of the shallow groundwater along the rivers is good and is suitable as fresh water resource. Due to pollution and declining water table problems in the Jakarta basin, the artificial recharge wells is shown to be a good way out to delineate the problems as indicated by pilot project conducted at Kelurahan Kramat Jati, using infiltration basin method. (author)

Relationship of Shallow Groundwater Quality to Hydraulic Fracturing Activities in Antrim and Kalkaska Counties, MI

Science.gov (United States)

Stefansky, J. N.; Robertson, W. M.; Chappaz, A.; Babos, H.; Israel, S.; Groskreutz, L. M.

2015-12-01

Hydraulic fracturing (fracking) of oil and natural gas (O&G) wells is a widely applied technology that can increase yields from tight geologic formations. However, it is unclear how fracking may impact shallow groundwater; previous research into its effects has produced conflicting results. Much of the worry over potential impacts to water quality arises from concerns about the produced water. The water produced from O&G formations is often salty, contains toxic dissolved elements, and can be radioactive. If fracking activities cause or increase connectivity between O&G formations and overlying groundwater, there may be risks to aquifers. As one part of a groundwater quality study in Antrim and Kalkaska Counties, MI, samples were collected from the unconfined glacial aquifer (3-300 m thick) and produced water from the underlying Antrim formation, a shallow (180-670 m deep) natural gas producing black shale. Groundwater samples were collected between 200 to 10,000 m distance from producing Antrim gas wells and from a range of screened intervals (15-95 m). Samples were analyzed for major constituents (e.g., Br, Cl), pH, conductivity, and dissolved oxygen (DO). The specific conductance of groundwater samples ranged from 230-1020 μS/cm; DO ranged from 0.4-100% saturation. Preliminary results show a slight inverse correlation between specific conductance and proximity to producing Antrim wells. The observed range of DO saturation in glacial aquifer groundwater appears to be related to both screened depth of the water wells and proximity to Antrim wells. During sampling, some well owners expressed concerns about the effects of fracking on groundwater quality and reported odd smells and tastes in their water after O&G drilling occurred near their homes. The results of this study and reported observations provide evidence to suggest a potential hydrogeological connection between the Antrim formation and the overlying glacial aquifer in some locations; it also raises

Pathways of coupled arsenic and iron cycling in high arsenic groundwater of the Hetao basin, Inner Mongolia, China: an iron isotope approach

Science.gov (United States)

Guo, Huaming; Liu, Chen; Lu, Hai; Wanty, Richard B.; Wang, Jun; Zhou, Yinzhu

2013-01-01

High As groundwater is widely distributed all over the world, which has posed a significant health impact on millions of people. Iron isotopes have recently been used to characterize Fe cycling in aqueous environments, but there is no information on Fe isotope characteristics in the groundwater. Since groundwater As behavior is closely associated with Fe cycling in the aquifers, Fe isotope signatures may help to characterize geochemical processes controlling As concentrations of shallow groundwaters. This study provides the first observation of Fe isotope fractionation in high As groundwater and evaluation of Fe cycling and As behaviors in shallow aquifers in terms of Fe isotope signatures. Thirty groundwater samples were taken for chemical and isotopic analysis in the Hetao basin, Inner Mongolia. Thirty-two sediments were sampled as well from shallow aquifers for Fe isotope analysis. Results showed that groundwater was normally enriched in isotopically light Fe with δ56Fe values between −3.40‰ and 0.58‰ and median of −1.14‰, while heavier δ56Fe values were observed in the sediments (between −1.10‰ and 0.75‰, median +0.36‰). In reducing conditions, groundwaters generally had higher δ56Fe values, in comparison with oxic conditions. High As groundwaters, generally occurring in reducing conditions, had high δ56Fe values, while low As groundwaters normally had low δ56Fe values. Although sediment δ56Fe values were generally independent of lithological conditions, a large variation in sediment δ56Fe values was observed in the oxidation–reduction transition zone. Three pathways were identified for Fe cycling in shallow groundwater, including dissimilatory reduction of Fe(III) oxides, re-adsorption of Fe(II), and precipitation of pyrite and siderite. Dissimilatory reduction of Fe(III) oxides resulted in light δ56Fe values (around −1.0‰) and high As concentration (>50 μg/L) in groundwater in anoxic conditions. Re-adsorption of isotopically

Groundwater and surface-water interactions near White Bear Lake, Minnesota, through 2011

Science.gov (United States)

Jones, Perry M.; Trost, Jared J.; Rosenberry, Donald O.; Jackson, P. Ryan; Bode, Jenifer A.; O'Grady, Ryan M.

2013-01-01

Hugo, Minnesota. Water-quality analyses of pore water from nearshore lake-sediment and well-water samples, seepage-meter measurements, and hydraulic-head differences measured in White Bear Lake also indicated groundwater was potentially flowing into White Bear Lake from shallow glacial aquifers to the east and south. Negative temperature anomalies determined in shallow waters in the water-quality survey conducted in White Bear Lake indicated several shallow-water areas where groundwater may be flowing into the lake from glacial aquifers below the lake. Cool lake-sediment temperatures (less than 18 degrees Celsius) were measured in eight areas along the northeast, east, south, and southwest shores of White Bear Lake, indicating potential areas where groundwater may flow into the lake. Stable isotope analyses of well-water, precipitation, and lake-water samples indicated wells downgradient from White Bear Lake screened in the glacial buried aquifer or open to the Prairie du Chien-Jordan aquifer receive a mixture of surface water and groundwater; the largest surface-water contributions are in wells closer to White Bear Lake. A wide range in oxygen-18/oxygen-16 and deuterium/protium ratios was measured in well-water samples, indicating different sources of water are supplying water to the wells. Well water with oxygen-18/oxygen-16 and deuterium/protium ratios that plot close to the meteoric water line consisted mostly of groundwater because deuterium/protium ratios for most groundwater usually are similar to ratios for rainwater and snow, plotting close to meteoric water lines. Well water with oxygen-18/oxygen-16 and deuterium/protium ratios that plot between the meteoric water line and ratios for the surface-water samples from White Bear Lake consists of a mixture of surface water and groundwater; the percentage of each source varies relative to its ratios. White Bear Lake is the likely source of the surface water to the wells that have a mixture of surface water and

Conceptual model of recharge to southeastern Badain Jaran Desert groundwater and lakes from environmental tracers

International Nuclear Information System (INIS)

Gates, John B; Edmunds, W Mike; Darling, W George; Ma Jinzhu; Pang Zhonghe; Young, Adam A

2008-01-01

Sources of groundwater recharge to the Badain Jaran Desert in China have been investigated using geochemical and isotopic techniques. Stable isotope compositions (δ 18 O and δ 2 H) of shallow groundwater and surface water from oasis lakes evolve from a starting composition considerably depleted compared to local unsaturated zone moisture, confirming inferences from chloride mass balance that direct infiltration of precipitation is not a volumetrically important source of recharge to the shallow aquifer in the study area. Shallow phreatic and deeper confined groundwater bodies appear unconnected based on chemical composition and radiocarbon activities. Hydrogeologic evidence points toward a bordering mountain range (Yabulai) as a likely recharge zone, which is consistent with tracer results. A mean residence time in the range of 1-2 ka for the desert's southeastern margin is inferred from radiocarbon. These results reveal that some replenishment to the desert aquifer is occurring but at a rate much lower than previously suggested, which is relevant for water resources planning in this ecologically sensitive area

Shallow groundwater in the Matanuska-Susitna Valley, Alaska—Conceptualization and simulation of flow

Science.gov (United States)

Kikuchi, Colin P.

2013-01-01

estimated during field investigations on several small streams. Regional groundwater flow patterns were characterized by synthesizing previous water-table maps with a synoptic water-level measurement conducted during 2009. Time-series water-level data were collected at groundwater and lake monitoring stations over the study period (2009–present). Comparison of historical groundwater-level records with time-series groundwater-level data collected during this study showed similar patterns in groundwater-level fluctuation in response to precipitation. Groundwater-age data collected during previous studies show that water moves quickly through the groundwater system, suggesting that the system responds quickly to changes in climate forcing. Similarly, the groundwater system quickly returns to long-term average conditions following variability due to seasonal or interannual changes in precipitation. These analyses indicate that the groundwater system is in a state of dynamic equilibrium, characterized by water-level fluctuation about a constant average state, with no long-term trends in aquifer-system storage. To address the second study goal, a steady-state groundwater flow model was developed to simulate regional groundwater flow patterns. The groundwater flow model was bounded by physically meaningful hydrologic features, and appropriate internal model boundaries were specified on the basis of conceptualization of the groundwater system resulting in a three-layer model. Calibration data included 173 water‑level measurements and 18 measurements of streamflow gains and losses along small streams. Comparison of simulated and observed heads and flows showed that the model accurately simulates important regional characteristics of the groundwater flow system. This model is therefore appropriate for studying regional-scale groundwater availability. Mismatch between model-simulated and observed hydrologic quantities is likely because of the coarse grid size of the model and

Seasonal change of residence time in spring water and groundwater at a mountainous headwater catchment

Science.gov (United States)

Nagano, Kosuke; Tsujimura, Maki; Onda, Yuichi; Iwagami, Sho; Sakakibara, Koichi; Sato, Yutaro

2017-04-01

Determination of water age in headwater is important to consider water pathway, source and storage in the catchment. Previous studies showed that groundwater residence time changes seasonally. These studies reported that mean residence time of water in dry season tends to be longer than that in rainy season, and it becomes shorter as precipitation and discharge amount increases. However, there are few studies to clarify factors causing seasonal change in mean residence time in spring water and groundwater based on observed data. Therefore, this study aims to reveal the relationship between mean residence time and groundwater flow system using SFconcentration in spring and 10 minutes interval hydrological data such as discharge volume, groundwater level and precipitation amount in a headwater catchment in Fukushima, Japan. The SF6 concentration data in spring water observed from April 2015 to November 2016 shows the mean residence time of springs ranged from zero to 14 years. We also observed a clear negative correlation between discharge rate and residence time in the spring. The residence time in shallow groundwater in rainy season was younger as compared with that in low rainfall period. Therefore, the shallow groundwater with young residence time seems to contribute to the spring in rainy season, causing shorter residence time. Additionally, the residence time of groundwater ranged from 3 to 5 years even in low rainfall period. The residence time in high groundwater table level in ridge was older as compared with that in low groundwater table level. These suggest that the contribution of groundwater with older age in the ridge becomes dominant in the low discharge.

Microbial effects on the release and attenuation of arsenic in the shallow subsurface of a natural geochemical anomaly

International Nuclear Information System (INIS)

Drahota, Petr; Falteisek, Lukáš; Redlich, Aleš; Rohovec, Jan; Matoušek, Tomáš; Čepička, Ivan

2013-01-01

Critical factors leading to arsenic release and attenuation from the shallow subsurface were studied with multidisciplinary approach in the natural gold–arsenic geochemical anomaly at Mokrsko (Czech Republic). The results show that microbial reduction promotes arsenic release from Fe(III) (hydr)oxides and Fe(III) arsenates, thereby enhancing dissolved arsenic in the shallow groundwater at average concentration of 7.76 mg/L. In the organic-rich aggregates and wood particles, however, microbial sulfate reduction triggers the formation of realgar deposits, leading to accumulation of As in the distinct organic-rich patches of the shallow subsurface. We conclude that precipitation of realgar in the shallow subsurface of soil/sediment depends on specific and non-trivial combination of water and rock chemistry, microbial community composition and spatial organisation of the subsurface zone, where speciation in saturated environments varied on a centimeter scale from reduced (decomposed wood, H 2 S and realgar present) to oxidized (goethite and arsenate minerals are present). Highlights: •Very high As(III) concentrations were detected in the shallow groundwater. •Arsenic is bound to Fe(III) (hydr)oxides, Fe(III) arsenates and newly-formed realgar. •Reductive dissolution of Fe(III) and As(V) minerals by bacteria leads to mobilization of arsenic. •Precipitation of realgar is constrained to anaerobic domains around and within organic particles. -- Microbial reduction of Fe(III) and As(V) minerals leads to mobilization of As and induces a mineralogical transition toward realgar formation

Installation of groundwater observation tubes OL-PVP39 - 40 and drilling of shallow drillhole OL-PP90 at Olkiluoto in Eurajoki 2013

Energy Technology Data Exchange (ETDEWEB)

Toropainen, V. [Suomen Malmi Oy, Espoo (Finland)

2013-11-15

In order to extend the groundwater monitoring network at Olkiluoto, Posiva Oy contracted Suomen Malmi Oy (Smoy) to install new groundwater observation tubes to two locations and to drill one shallow drillhole with a standpipe. The identification numbers of the groundwater observation tubes are OL-PVP39, OL-PVP40A and 40B, and the shallow drillhole is named OL-PP90. The observation tubes were installed and the shallow hole drilled between July 29th and August 6th in 2013. The drilling rig used in the installation work was a GM-200 rig. Drilling equipment consisted of casing tubes (v 90/77 mm) with drilling bit, 55 mm geo rods and 64 mm drilling bits and T76-equipment for drilling the shallow hole. Monitoring pipes (PVC, v 60/52 mm) were lowered into the holes inside the casings. The monitoring pipes consist of a lower section of riser pipe, a middle section of screen pipe and an upper section of riser pipe. The screen pipe slot size is 0.3 mm and the length of the screen section is two or three metres. Protective stainless steel covers with lock-up caps were installed around the monitoring tubes and the shallow drillholes. In addition to the installation of the tubes, the work included water level measurements after installation. The core samples of the shallow drillhole were logged and reported by geologist. Geological logging included the following parameters: lithology, foliation, fracture parameters, fractured zones, core loss, weathering, fracture frequency, RQD and rock quality. (orig.)

Hydrogeochemical investigation of groundwater in shallow coastal aquifer of Khulna District, Bangladesh

Science.gov (United States)

Islam, S. M. Didar-Ul; Bhuiyan, Mohammad Amir Hossain; Rume, Tanjena; Azam, Gausul

2017-12-01

Groundwater acts as a lifeline in the coastal regions to meet out the domestic, drinking, irrigational and industrial needs. To investigate the hydrogeochemical characteristics of groundwater and its suitability, twenty samples were collected from the shallow tubewells of study area having screen depth 21-54 m. The water quality assessment has been carried out by evaluating the physicochemical parameters such as temperature, pH, EC, TDS and major ions i.e., Na+, K+, Ca2+, Mg2+, Cl-, SO4 2-, NO3 -, HCO3 -. Results found that, the water is slightly alkaline and brackish in nature. The trends of cations and anions are Na+ > Ca2+ > Mg2+ > K+ and Cl- > HCO3 - > SO4 2- > NO3 -, respectively and Na-Cl-HCO3 is the dominant groundwater type. The analyzed samples were also characterized with different indices, diagram and permissible limit i.e., electric conductivity (EC), total dissolved solids (TDS), chloride content (Cl), soluble sodium percentage (SSP), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), magnesium adsorption ratio (MAR), Kelley's ratio (KR), Wilcox diagram and USSL diagram, and results showed that groundwater are not suitable for drinking and irrigational use. The factors responsible for the geochemical characterization were also attempted by using standard plot and it was found that mixing of seawater with entrapped water plays a significant role in the study area.

The Roles of Shallow and Deep Groundwater Storage During Drought at Panola Mountain Research Watershed, Georgia, U.S.A.

Science.gov (United States)

Aulenbach, B. T.; Peters, N. E.

2016-12-01

Southeastern U.S. experiences recurring droughts, which can reduce water availability and can result in water-limiting conditions. Monthly water budgets were estimated at Panola Mountain Research Watershed, a small 41-hectare forested watershed near Atlanta, Georgia, from 1985 through 2015, to quantify the effects of climatic variability on groundwater (GW) storage. A relation between stream base flow and watershed GW storage was developed. The relation indicated that both shallow and deep GW storage contribute to base-flow runoff, except for the bottom third (78 mm) of the range in observed shallow soil moisture. The base flow-storage relation was then used to estimate monthly evapotranspiration (ET) using a closed water budget approach. Growing season droughts were almost always preceded by low GW storage at the onset of the growing season. The low base flow and GW storage conditions were caused by low precipitation (P) during the dormant season, and to a lesser extent, carryover of low GW storage conditions from the previous growing season. Growing season P had little impact on drought, as most P ultimately resulted in ET instead of deeper GW recharge. Water-limited growing season conditions were indicated when potential ET (PET) >> ET, and occurred during months having a large "P-deficit", PET - P, and when shallow storage was already near its observed minimum—such that the P-deficits exceeded the extractable water in shallow storage. These observations can be used to hypothesize how projected future increases in temperature, and how resulting increases in PET affect water budgets in Southeastern U.S. The dormant season will become shorter and ET will increase, causing decreased GW recharge during the dormant season, and will result in more frequent and severe growing season droughts. Higher growing season PET would increase the frequency and duration of water limiting conditions due to higher P-deficits and more frequent occurrences of low shallow storage.

Evaluation of ground-water flow and hydrologic budget for Lake Five-O, a seepage lake in northwestern Florida

Science.gov (United States)

Grubbs, J.W.

1995-01-01

Temporal and spatial distributions of ground-water inflow to, and leakage from Lake Five-O, a softwater, seepage lake in northwestern Florida, were evaluated using hydrologic data and simulation models of the shallow ground-water system adjacent to the lake. The simulation models indicate that ground-water inflow to the lake and leakage from the lake to the ground-water system are the dominant components in the total inflow (precipitation plus ground-water inflow) and total outflow (evaporation plus leakage) budgets of Lake Five-O. Simlulated ground-water inflow and leakage were approximately 4 and 5 times larger than precipitation inputs and evaporative losses, respectively, during calendar years 1989-90. Exchanges of water between Lake Five-O and the ground-water system were consistently larger than atmospheric-lake exchanges. A consistent pattern of shallow ground-water inflow and deep leakage was also evident throughout the study period. The mean time of travel from ground-water that discharges at Lake Five-O (time from recharge at the water table to discharge at the lake) was estimated to be within a range of 3 to 6 years. Flow-path evaluations indicated that the intermediate confining unit probably has a negligible influence on the geochemistry of ground-water inflow to Lake Five-O. The hydrologic budgets and flow-path evaluations provide critical information for developing geochemical budgets for Lake Five-O and for improving the understanding of the relative importance of various processes that regulate the acid-neutralizing capacity of softwater seepage lakes in Florida.

Turbulence effects on warm-rain formation in precipitating shallow convection revisited

Directory of Open Access Journals (Sweden)

A. Seifert

2016-09-01

Full Text Available Two different collection kernels which include turbulence effects on the collision rate of liquid droplets are used as a basis to develop a parameterization of the warm-rain processes autoconversion, accretion, and self-collection. The new parameterization is tested and validated with the help of a 1-D bin microphysics model. Large-eddy simulations of the rain formation in shallow cumulus clouds confirm previous results that turbulence effects can significantly enhance the development of rainwater in clouds and the occurrence and amount of surface precipitation. The detailed behavior differs significantly for the two turbulence models, revealing a considerable uncertainty in our understanding of such effects. In addition, the large-eddy simulations show a pronounced sensitivity to grid resolution, which suggests that besides the effect of sub-grid small-scale isotropic turbulence which is parameterized as part of the collection kernel also the larger turbulent eddies play an important role for the formation of rain in shallow clouds.

Groundwater geochemistry and its implications for arsenic mobilization in shallow aquifers of the Hetao Basin, Inner Mongolia

International Nuclear Information System (INIS)

Guo Huaming; Yang Suzhen; Tang Xiaohui; Li Yuan; Shen Zhaoli

2008-01-01

Arsenic concentrations in shallow groundwaters from the Hetao Basin of Inner Mongolia range between 0.6 and 572 μg/L. High As groundwaters generally occur in the shallow alluvial-lacustrine aquifers, which are mainly composed of black (or dark grey) fine sands in a reducing environment. They are characterized by high concentrations of dissolved Fe, Mn, HCO 3 - , P and S 2- , and low concentrations of NO 3 - and SO 4 2- . Low SO 4 2- coupled with high S 2- suggests that SO 4 2- reduction has been an active process. In the reducing groundwaters, inorganic As(III) accounts for around 75% of total dissolved As. Total As contents in the sediments from three representative boreholes are observed to be 7.3-73.3 mg/kg (average of 18.9 mg/kg). The total As is mildly-strongly correlated with total Fe and total Mn, while a quite weak correlation exists between total As and total S, suggesting that the As is associated with Fe-Mn oxides, rather than sulfides in the sediments. It is found in the sequential extraction that chemically active As is mainly bound to Fe-Mn oxides, up to 3500 μg/kg. The mobilization of As under reducing conditions is believed to include reductive dissolution of Fe-Mn oxides and reduction of adsorbed As. Although exchangeable As is labile and very vulnerable to hydrogeochemical condition, the contribution is relatively limited due to the low concentrations. The competition between As and other anions (such as HPO 4 2- ) for binding sites on Fe-Mn oxides may also give rise to the release of As into groundwater. Slow groundwater movement helps accumulation of the released As in the groundwaters

Perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion

Science.gov (United States)

Xiaobo Zhou; Matthew J. Helmers; Heidi Asbjornsen; Randy Kolka; Mark D. Tomer

2010-01-01

Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (NO3-N) concentrations in soil and shallow groundwater and to...

The impact of river infiltration on the chemistry of shallow groundwater in a reclaimed water irrigation area.

Science.gov (United States)

Yin, Shiyang; Wu, Wenyong; Liu, Honglu; Bao, Zhe

2016-10-01

Reclaimed water reuse is an effective method of alleviating agricultural water shortages, which entails some potential risks for groundwater. In this study, the impacts of wastewater reuse on groundwater were evaluated by combination of groundwater chemistry and isotopes. In reclaimed water infiltration, salt composition was affected not only by ion exchange and dissolution equilibrium but also by carbonic acid equilibrium. The dissolution and precipitation of calcites and dolomites as well as exchange and adsorption between Na and Ca/Mg were simultaneous, leading to significant changes in Na/Cl, (Ca+Mg)/Cl, electrical conductivity (EC) and sodium adsorption ratio (SAR). The reclaimed water was of the Na-Mg-Ca-HCO 3 -Cl type, and groundwater recharged by reclaimed water was of the Na-Mg-HCO 3 and Mg-Na-HCO 3 types. The hydrogeological conditions characterized by sand-clay alternation led to both total nitrogen (TN) and total phosphorus (TP) removal efficiencies >95%, and there was no significant difference in those contents between aquifers recharged by precipitation and reclamation water. >40years of long-term infiltration and recharge from sewage and reclaimed water did not cause groundwater contamination by nitrogen, phosphorus and heavy metals. These results indicate that characteristics of the study area, such as the lithologic structure with sand-clay alternation, relatively thick clay layer, and relatively large groundwater depth have a significant role in the high vulnerability. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of the Local Grid Refinement package to an inset model simulating the interactions of lakes, wells, and shallow groundwater, northwestern Waukesha County, Wisconsin

Science.gov (United States)

Feinstein, D.T.; Dunning, C.P.; Juckem, P.F.; Hunt, R.J.

2010-01-01

Groundwater use from shallow, high-capacity wells is expected to increase across southeastern Wisconsin in the next decade (2010-2020), owing to residential and business growth and the need for shallow water to be blended with deeper water of lesser quality, containing, for example, excessive levels of radium. However, this increased pumping has the potential to affect surface-water features. A previously developed regional groundwater-flow model for southeastern Wisconsin was used as the starting point for a new model to characterize the hydrology of part of northwestern Waukesha County, with a particular focus on the relation between the shallow aquifer and several area lakes. An inset MODFLOW model was embedded in an updated version of the original regional model. Modifications made within the inset model domain include finer grid resolution; representation of Beaver, Pine, and North Lakes by use of the LAK3 package in MODFLOW; and representation of selected stream reaches with the SFR package. Additionally, the inset model is actively linked to the regional model by use of the recently released Local Grid Refinement package for MODFLOW-2005, which allows changes at the regional scale to propagate to the local scale and vice versa. The calibrated inset model was used to simulate the hydrologic system in the Chenequa area under various weather and pumping conditions. The simulated model results for base conditions show that groundwater is the largest inflow component for Beaver Lake (equal to 59 percent of total inflow). For Pine and North Lakes, it is still an important component (equal, respectively, to 16 and 5 percent of total inflow), but for both lakes it is less than the contribution from precipitation and surface water. Severe drought conditions (simulated in a rough way by reducing both precipitation and recharge rates for 5 years to two-thirds of base values) cause correspondingly severe reductions in lake stage and flows. The addition of a test well

Bacterial contamination of tile drainage water and shallow groundwater under different application methods of liquid swine manure.

Science.gov (United States)

Samarajeewa, A D; Glasauer, S M; Lauzon, J D; O'Halloran, I P; Parkin, Gary W; Dunfield, K E

2012-05-01

A 2 year field experiment evaluated liquid manure application methods on the movement of manure-borne pathogens (Salmonella sp.) and indicator bacteria (Escherichia coli and Clostridium perfringens) to subsurface water. A combination of application methods including surface application, pre-application tillage, and post-application incorporation were applied in a randomized complete block design on an instrumented field site in spring 2007 and 2008. Tile and shallow groundwater were sampled immediately after manure application and after rainfall events. Bacterial enumeration from water samples showed that the surface-applied manure resulted in the highest concentration of E. coli in tile drainage water. Pre-tillage significantly (p tile water and to shallow groundwater within 3 days after manure application (DAM) in 2008 and within 10 DAM in 2007. Pre-tillage also decreased the occurrence of Salmonella sp. in tile water samples. Indicator bacteria and pathogens reached nondetectable levels within 50 DAM. The results suggest that tillage before application of liquid swine manure can minimize the movement of bacteria to tile and groundwater, but is effective only for the drainage events immediately after manure application or initial rainfall-associated drainage flows. Furthermore, the study highlights the strong association between bacterial concentrations in subsurface waters and rainfall timing and volume after manure application.

Study of Factors Influencing Oxygen-18 Isotopic Contents of Dissolved Sulphate in the Shallow Groundwater In Karawang Area

International Nuclear Information System (INIS)

Ristin Pujiindiyati, E.; Bungkus Pratikno

2010-01-01

The study was conducted to investigate the factors influencing oxygen-18 isotopic contents of dissolved sulphate in shallow groundwater from Karawang area. The δ 18 O is a relative abundance of O-18 compared to O-16 in CO 2 gas. CO 2 gas was released from the equilibrium between water samples and CO 2 gas, and from the reduction of sulphate samples with graphite. From this investigation, the δ 18 O (H 2 O) values were in the range of -3.21 0 / 00 to 6.25 0 / 00 whereas the δ 18 O (SO 4 2- ) values were 9.64 0 / 00 to 20.72 0 / 00 . The wide variation of δ 18 O (SO 4 2- ) values might be result due to inhomogeneity of sulphate sources in groundwater where the groundwater sulphates were generally derived from the dissolution of marine evaporites rocks. The groundwaters and Citarum River near waters to Johar site showed lowering of δ 18 O (SO 4 2- ) values. It might be related to the present of the traditional market in this location. The lowering of these values might be due to the increase of the sulphate reduction process caused by anaerobic bacteria growth in organic garbage deposition. Plotting between δ 18 O (SO 4 2- ) and δ 18 O (H 2 O) exhibited that the oxygen contribution from H 2 O to form sulphate was less than 25%. This indicated that the shallow groundwater in Karawang is located in a non-saturated zone and had a biotic condition. (author)

Groundwater-quality data for the Madera/Chowchilla–Kings shallow aquifer study unit, 2013–14: Results from the California GAMA Program

Science.gov (United States)

Shelton, Jennifer L.; Fram, Miranda S.

2017-02-03

Groundwater quality in the 2,390-square-mile Madera/Chowchilla–Kings Shallow Aquifer study unit was investigated by the U.S. Geological Survey from August 2013 to April 2014 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment Program’s Priority Basin Project. The study was designed to provide a statistically unbiased, spatially distributed assessment of untreated groundwater quality in the shallow aquifer systems of the Madera, Chowchilla, and Kings subbasins of the San Joaquin Valley groundwater basin. The shallow aquifer system corresponds to the part of the aquifer system generally used by domestic wells and is shallower than the part of the aquifer system generally used by public-supply wells. This report presents the data collected for the study and a brief preliminary description of the results.Groundwater samples were collected from 77 wells and were analyzed for organic constituents, inorganic constituents, selected isotopic and age-dating tracers, and microbial indicators. Most of the wells sampled for this study were private domestic wells. Unlike groundwater from public-supply wells, the groundwater from private domestic wells is not regulated for quality in California and is rarely analyzed for water-quality constituents. To provide context for the sampling results, however, concentrations of constituents measured in the untreated groundwater were compared with regulatory and non-regulatory benchmarks established for drinking-water quality by the U.S. Environmental Protection Agency, the State of California, and the U.S. Geological Survey.Of the 319 organic constituents assessed in this study (90 volatile organic compounds and 229 pesticides and pesticide degradates), 17 volatile organic compounds and 23 pesticides and pesticide degradates were detected in groundwater samples; concentrations of all but 2 were less than the respective benchmarks. The fumigants 1,2-dibromo-3-chloropropane (DBCP

Hydro-ecological controls on dissolved carbon dynamics in groundwater and export to streams in a temperate pine forest

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Deirmendjian, Loris; Loustau, Denis; Augusto, Laurent; Lafont, Sébastien; Chipeaux, Christophe; Poirier, Dominique; Abril, Gwenaël

2018-02-01

We studied the export of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) from forested shallow groundwater to first-order streams, based on groundwater and surface water sampling and hydrological data. The selected watershed was particularly convenient for such study, with a very low slope, with pine forest growing on sandy permeable podzol and with hydrology occurring exclusively through drainage of shallow groundwater (no surface runoff). A forest plot was instrumented for continuous eddy covariance measurements of precipitation, evapotranspiration, and net ecosystem exchanges of sensible and latent heat fluxes as well as CO2 fluxes. Shallow groundwater was sampled with three piezometers located in different plots, and surface waters were sampled in six first-order streams; river discharge and drainage were modeled based on four gauging stations. On a monthly basis and on the plot scale, we found a good consistency between precipitation on the one hand and the sum of evapotranspiration, shallow groundwater storage and drainage on the other hand. DOC and DIC stocks in groundwater and exports to first-order streams varied drastically during the hydrological cycle, in relation with water table depth and amplitude. In the groundwater, DOC concentrations were maximal in winter when the water table reached the superficial organic-rich layer of the soil. In contrast, DIC (in majority excess CO2) in groundwater showed maximum concentrations at low water table during late summer, concomitant with heterotrophic conditions of the forest plot. Our data also suggest that a large part of the DOC mobilized at high water table was mineralized to DIC during the following months within the groundwater itself. In first-order streams, DOC and DIC followed an opposed seasonal trend similar to groundwater but with lower concentrations. On an annual basis, leaching of carbon to streams occurred as DIC and DOC in similar proportion, but DOC export occurred in

Hydro-ecological controls on dissolved carbon dynamics in groundwater and export to streams in a temperate pine forest

Directory of Open Access Journals (Sweden)

L. Deirmendjian

2018-02-01

Full Text Available We studied the export of dissolved inorganic carbon (DIC and dissolved organic carbon (DOC from forested shallow groundwater to first-order streams, based on groundwater and surface water sampling and hydrological data. The selected watershed was particularly convenient for such study, with a very low slope, with pine forest growing on sandy permeable podzol and with hydrology occurring exclusively through drainage of shallow groundwater (no surface runoff. A forest plot was instrumented for continuous eddy covariance measurements of precipitation, evapotranspiration, and net ecosystem exchanges of sensible and latent heat fluxes as well as CO2 fluxes. Shallow groundwater was sampled with three piezometers located in different plots, and surface waters were sampled in six first-order streams; river discharge and drainage were modeled based on four gauging stations. On a monthly basis and on the plot scale, we found a good consistency between precipitation on the one hand and the sum of evapotranspiration, shallow groundwater storage and drainage on the other hand. DOC and DIC stocks in groundwater and exports to first-order streams varied drastically during the hydrological cycle, in relation with water table depth and amplitude. In the groundwater, DOC concentrations were maximal in winter when the water table reached the superficial organic-rich layer of the soil. In contrast, DIC (in majority excess CO2 in groundwater showed maximum concentrations at low water table during late summer, concomitant with heterotrophic conditions of the forest plot. Our data also suggest that a large part of the DOC mobilized at high water table was mineralized to DIC during the following months within the groundwater itself. In first-order streams, DOC and DIC followed an opposed seasonal trend similar to groundwater but with lower concentrations. On an annual basis, leaching of carbon to streams occurred as DIC and DOC in similar proportion, but DOC export

Nutrient Enrichment in Estuaries from Discharge of Shallow Ground Water, Mt. Desert Island, Maine

Science.gov (United States)

Culbertson, Charles W.; Huntington, Thomas G.; Caldwell, James M.

2007-01-01

Nutrient enrichment from atmospheric deposition, agricultural activities, wildlife, and domestic sources is a concern at Acadia National Park because of the potential problem of water-quality degradation and eutrophication in its estuaries. Water-quality degradation has been observed at the Park?s Bass Harbor Marsh estuary but not in Northeast Creek estuary. Previous studies at Acadia National Park have estimated nutrient inputs to estuaries from atmospheric deposition and surface-water runoff, but the importance of shallow ground water that may contain nutrients derived from domestic or other sources is unknown. Northeast Creek and Bass Harbor Marsh estuaries were studied to (1) identify shallow ground-water seeps, (2) assess the chemistry of the water discharged from selected seeps, and (3) assess the chemistry of ground water in shallow ground-water hyporheic zones. The hyporheic zone is defined here as the region beneath and lateral to a stream bed, where there is mixing of shallow ground water and surface water. This study also provides baseline chemical data for ground water in selected bedrock monitoring wells and domestic wells on Mt. Desert Island. Water samples were analyzed for concentrations of nutrients, wastewater compounds, dissolved organic carbon, pH, dissolved oxygen, temperature and specific conductance. Samples from bedrock monitoring wells also were analyzed for alkalinity, major cations and anions, and trace metals. Shallow ground-water seeps to Northeast Creek and Bass Harbor Marsh estuaries at Acadia National Park were identified and georeferenced using aerial infrared digital imagery. Monitoring included the deployment of continuously recording temperature and specific conductance sensors in the seep discharge zone to access marine or freshwater signatures related to tidal flooding, gradient-driven shallow ground-water flow, or shallow subsurface flow related to precipitation events. Many potential shallow ground-water discharge zones were

Multivariate analysis of the heterogeneous geochemical processes controlling arsenic enrichment in a shallow groundwater system.

Science.gov (United States)

Huang, Shuangbing; Liu, Changrong; Wang, Yanxin; Zhan, Hongbin

2014-01-01

The effects of various geochemical processes on arsenic enrichment in a high-arsenic aquifer at Jianghan Plain in Central China were investigated using multivariate models developed from combined adaptive neuro-fuzzy inference system (ANFIS) and multiple linear regression (MLR). The results indicated that the optimum variable group for the AFNIS model consisted of bicarbonate, ammonium, phosphorus, iron, manganese, fluorescence index, pH, and siderite saturation. These data suggest that reductive dissolution of iron/manganese oxides, phosphate-competitive adsorption, pH-dependent desorption, and siderite precipitation could integrally affect arsenic concentration. Analysis of the MLR models indicated that reductive dissolution of iron(III) was primarily responsible for arsenic mobilization in groundwaters with low arsenic concentration. By contrast, for groundwaters with high arsenic concentration (i.e., > 170 μg/L), reductive dissolution of iron oxides approached a dynamic equilibrium. The desorption effects from phosphate-competitive adsorption and the increase in pH exhibited arsenic enrichment superior to that caused by iron(III) reductive dissolution as the groundwater chemistry evolved. The inhibition effect of siderite precipitation on arsenic mobilization was expected to exist in groundwater that was highly saturated with siderite. The results suggest an evolutionary dominance of specific geochemical process over other factors controlling arsenic concentration, which presented a heterogeneous distribution in aquifers. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Environmental Science and Health, Part A, to view the supplemental file.

Geochemical and isotopic variations in shallow groundwater in areas of the Fayetteville Shale development, north-central Arkansas

Science.gov (United States)

Warner, Nathaniel R.; Kresse, Timothy M.; Hays, Phillip D.; Down, Adrian; Karr, Jonathan D.; Jackson, R.B.; Vengosh, Avner

2013-01-01

Exploration of unconventional natural gas reservoirs such as impermeable shale basins through the use of horizontal drilling and hydraulic fracturing has changed the energy landscape in the USA providing a vast new energy source. The accelerated production of natural gas has triggered a debate concerning the safety and possible environmental impacts of these operations. This study investigates one of the critical aspects of the environmental effects; the possible degradation of water quality in shallow aquifers overlying producing shale formations. The geochemistry of domestic groundwater wells was investigated in aquifers overlying the Fayetteville Shale in north-central Arkansas, where approximately 4000 wells have been drilled since 2004 to extract unconventional natural gas. Monitoring was performed on 127 drinking water wells and the geochemistry of major ions, trace metals, CH4 gas content and its C isotopes (δ13CCH4), and select isotope tracers (δ11B, 87Sr/86Sr, δ2H, δ18O, δ13CDIC) compared to the composition of flowback-water samples directly from Fayetteville Shale gas wells. Dissolved CH4 was detected in 63% of the drinking-water wells (32 of 51 samples), but only six wells exceeded concentrations of 0.5 mg CH4/L. The δ13CCH4 of dissolved CH4 ranged from −42.3‰ to −74.7‰, with the most negative values characteristic of a biogenic source also associated with the highest observed CH4 concentrations, with a possible minor contribution of trace amounts of thermogenic CH4. The majority of these values are distinct from the reported thermogenic composition of the Fayetteville Shale gas (δ13CCH4 = −35.4‰ to −41.9‰). Based on major element chemistry, four shallow groundwater types were identified: (1) low ( 100 mg/L and Ca–HCO3 dominated, (3) TDS > 100 mg/L and Na–HCO3dominated, and (4) slightly saline groundwater with TDS > 100 mg/L and Cl > 20 mg/L with elevated Br/Cl ratios (>0.001). The Sr (87Sr/86Sr = 0.7097�

Groundwater fluxes in a shallow seasonal wetland pond: The effect of bathymetric uncertainty on predicted water and solute balances

Science.gov (United States)

Trigg, Mark A.; Cook, Peter G.; Brunner, Philip

2014-09-01

The successful management of groundwater dependent shallow seasonal wetlands requires a sound understanding of groundwater fluxes. However, such fluxes are hard to quantify. Water volume and solute mass balance models can be used in order to derive an estimate of groundwater fluxes within such systems. This approach is particularly attractive, as it can be undertaken using measurable environmental variables, such as; rainfall, evaporation, pond level and salinity. Groundwater fluxes estimated from such an approach are subject to uncertainty in the measured variables as well as in the process representation and in parameters within the model. However, the shallow nature of seasonal wetland ponds means water volume and surface area can change rapidly and non-linearly with depth, requiring an accurate representation of the wetland pond bathymetry. Unfortunately, detailed bathymetry is rarely available and simplifying assumptions regarding the bathymetry have to be made. However, the implications of these assumptions are typically not quantified. We systematically quantify the uncertainty implications for eight different representations of wetland bathymetry for a shallow seasonal wetland pond in South Australia. The predictive uncertainty estimation methods provided in the Model-Independent Parameter Estimation and Uncertainty Analysis software (PEST) are used to quantify the effect of bathymetric uncertainty on the modelled fluxes. We demonstrate that bathymetry can be successfully represented within the model in a simple parametric form using a cubic Bézier curve, allowing an assessment of bathymetric uncertainty due to measurement error and survey detail on the derived groundwater fluxes compared with the fixed bathymetry models. Findings show that different bathymetry conceptualisations can result in very different mass balance components and hence process conceptualisations, despite equally good fits to observed data, potentially leading to poor management

Hydrologic assessment of the shallow groundwater flow system beneath the Shinnecock Nation tribal lands, Suffolk County, New York

Science.gov (United States)

Noll, Michael L.; Rivera, Simonette L.; Busciolano, Ronald J.

2016-12-02

Defining the distribution and flow of shallow groundwater beneath the Shinnecock Nation tribal lands in Suffolk County, New York, is a crucial first step in identifying sources of potential contamination to the surficial aquifer and coastal ecosystems. The surficial or water table aquifer beneath the tribal lands is the primary source of potable water supply for at least 6 percent of the households on the tribal lands. Oyster fisheries and other marine ecosystems are critical to the livelihood of many residents living on the tribal lands, but are susceptible to contamination from groundwater entering the embayment from the surficial aquifer. Contamination of the surficial aquifer from flooding during intense coastal storms, nutrient loading from fertilizers, and septic effluent have been identified as potential sources of human and ecological health concerns on tribal lands.The U.S. Geological Survey (USGS) facilitated the installation of 17 water table wells on and adjacent to the tribal lands during March 2014. These wells were combined with other existing wells to create a 32-well water table monitoring network that was used to assess local hydrologic conditions. Survey-grade, global-navigation-satellite systems provided centimeter-level accuracy for positioning wellhead surveys. Water levels were measured by the USGS during May (spring) and November (fall) 2014 to evaluate seasonal effects on the water table. Water level measurements were made at high and low tide during May 2014 to identify potential effects on the water table caused by changes in tidal stage (tidal flux) in Shinnecock Bay. Water level contour maps indicate that the surficial aquifer is recharged by precipitation and upgradient groundwater flow that moves from the recharge zone located generally beneath Sunrise Highway, to the discharge zone beneath the tribal lands, and eventually discharges into the embayment, tidal creeks, and estuaries that bound the tribal lands to the east, south, and

Ground-water discharge determined from measurements of evapotranspiration, other available hydrologic components, and shallow water-level changes, Oasis Valley, Nye County, Nevada

International Nuclear Information System (INIS)

Reiner, S.R.; Laczniak, R.J.; DeMeo, G.A.; Smith LaRue, J.; Elliott, P.E.; Nylund, W.E.; Fridrich, C.J.

2002-01-01

Oasis Valley is an area of natural ground-water discharge within the Death Valley regional ground-water flow system of southern Nevada and adjacent California. Ground water discharging at Oasis Valley is replenished from inflow derived from an extensive recharge area that includes the northwestern part of the Nevada Test Site (NTS). Because nuclear testing has introduced radionuclides into the subsurface of the NTS, the U.S. Department of Energy currently is investigating the potential transport of these radionuclides by ground water flow. To better evaluate any potential risk associated with these test-generated contaminants, a number of studies were undertaken to accurately quantify discharge from areas downgradient in the regional ground-water flow system from the NTS. This report refines the estimate of ground-water discharge from Oasis Valley. Ground-water discharge from Oasis Valley was estimated by quantifying evapotranspiration (ET), estimating subsurface outflow, and compiling ground-water withdrawal data. ET was quantified by identifying areas of ongoing ground-water ET, delineating areas of ET defined on the basis of similarities in vegetation and soil-moisture conditions and computing ET rates for each of the delineated areas. A classification technique using spectral-reflectance characteristics determined from satellite imagery acquired in 1992 identified eight unique areas of ground-water ET. These areas encompass about 3,426 acres of sparsely to densely vegetated grassland, shrubland, wetland, and open water. Annual ET rates in Oasis Valley were computed with energy-budget methods using micrometeorological data collected at five sites. ET rates range from 0.6 foot per year in a sparse, dry saltgrass environment to 3.1 feet per year in dense meadow vegetation. Mean annual ET from Oasis Valley is estimated to be about 7,800 acre-feet. Mean annual ground-water discharge by ET from Oasis Valley, determined by removing the annual local precipitation

Installation of groundwater observation tubes OL-PVP36-38 and drilling of shallow drillholes OL-PP70-71 at Olkiluoto in Eurajoki 2011

International Nuclear Information System (INIS)

Toropainen, V.

2012-05-01

In order to widen the groundwater monitoring network at Olkiluoto, Posiva Oy contracted Suomen Malmi Oy (Smoy) to install new groundwater observation tubes to three locations and to drill two shallow drillholes with standpipes. The identification numbers of the groundwater observation tubes are OL-PVP36, OL-PVP37A, 37B, 37C, OL-PVP38A, 38B, 38C and 38D, and the shallow drillholes are named OL-PP70 and OL-PP71. The observation tubes were installed and the shallow holes drilled between September 22nd and October 12th in 2011. The drilling rig used in the installation work was a GM-200 rig. Drilling equipment consisted of casing tubes (90/77 mm) with drilling bit, 55 mm geo rods and 64 mm drilling bits and T76-equipment for drilling the shallow holes. Monitoring pipes (PVC, 60/52 mm) were lowered into the holes inside the casings. The monitoring pipes consist of a lower section of riser pipe, a middle section of screen pipe and an upper section of riser pipe. The screen pipe slot size is 0.3 mm and the length of the screen section is two metres. Protective stainless steel covers with lock-up caps were installed around the monitoring tubes and the shallow drillholes. In addition to the installation of the tubes, the work included water level measurements after installation. The core samples of the shallow drillholes were logged and reported by geologist. Geological logging included the following parameters: lithology, foliation, fracture parameters, fractured zones, core loss, weathering, fracture frequency, RQD and rock quality. (orig.)

Installation of groundwater observation tubes OL-PVP36-38 and drilling of shallow drillholes OL-PP70-71 at Olkiluoto in Eurajoki 2011

Energy Technology Data Exchange (ETDEWEB)

Toropainen, V. [Suomen Malmi Oy, Espoo (Finland)

2012-05-15

In order to widen the groundwater monitoring network at Olkiluoto, Posiva Oy contracted Suomen Malmi Oy (Smoy) to install new groundwater observation tubes to three locations and to drill two shallow drillholes with standpipes. The identification numbers of the groundwater observation tubes are OL-PVP36, OL-PVP37A, 37B, 37C, OL-PVP38A, 38B, 38C and 38D, and the shallow drillholes are named OL-PP70 and OL-PP71. The observation tubes were installed and the shallow holes drilled between September 22nd and October 12th in 2011. The drilling rig used in the installation work was a GM-200 rig. Drilling equipment consisted of casing tubes (90/77 mm) with drilling bit, 55 mm geo rods and 64 mm drilling bits and T76-equipment for drilling the shallow holes. Monitoring pipes (PVC, 60/52 mm) were lowered into the holes inside the casings. The monitoring pipes consist of a lower section of riser pipe, a middle section of screen pipe and an upper section of riser pipe. The screen pipe slot size is 0.3 mm and the length of the screen section is two metres. Protective stainless steel covers with lock-up caps were installed around the monitoring tubes and the shallow drillholes. In addition to the installation of the tubes, the work included water level measurements after installation. The core samples of the shallow drillholes were logged and reported by geologist. Geological logging included the following parameters: lithology, foliation, fracture parameters, fractured zones, core loss, weathering, fracture frequency, RQD and rock quality. (orig.)

Appraising options to reduce shallow groundwater tables and enhance flow conditions over regional scales in an irrigated alluvial aquifer system

Science.gov (United States)

Morway, Eric D.; Gates, Timothy K.; Niswonger, Richard G.

2013-01-01

Some of the world’s key agricultural production systems face big challenges to both water quantity and quality due to shallow groundwater that results from long-term intensive irrigation, namely waterlogging and salinity, water losses, and environmental problems. This paper focuses on water quantity issues, presenting finite-difference groundwater models developed to describe shallow water table levels, non-beneficial groundwater consumptive use, and return flows to streams across two regions within an irrigated alluvial river valley in southeastern Colorado, USA. The models are calibrated and applied to simulate current baseline conditions in the alluvial aquifer system and to examine actions for potentially improving these conditions. The models provide a detailed description of regional-scale subsurface unsaturated and saturated flow processes, thereby enabling detailed spatiotemporal description of groundwater levels, recharge to infiltration ratios, partitioning of ET originating from the unsaturated and saturated zones, and groundwater flows, among other variables. Hybrid automated and manual calibration of the models is achieved using extensive observations of groundwater hydraulic head, groundwater return flow to streams, aquifer stratigraphy, canal seepage, total evapotranspiration, the portion of evapotranspiration supplied by upflux from the shallow water table, and irrigation flows. Baseline results from the two regional-scale models are compared to model predictions under variations of four alternative management schemes: (1) reduced seepage from earthen canals, (2) reduced irrigation applications, (3) rotational lease fallowing (irrigation water leased to municipalities, resulting in temporary dry-up of fields), and (4) combinations of these. The potential for increasing the average water table depth by up to 1.1 and 0.7 m in the two respective modeled regions, thereby reducing the threat of waterlogging and lowering non-beneficial consumptive use

Hydrogeology and groundwater evaluation of a shallow coastal aquifer, southern Akwa Ibom State (Nigeria)

Science.gov (United States)

Edet, Aniekan

2017-09-01

The rapid expansion of economic activities in coastal parts of Nigeria has triggered an uncoordinated development of groundwater leading to stress on the resource. Hence a study was conducted to assess the hydrogeological characteristics of the shallow coastal aquifer of southern Akwa Ibom State, Nigeria. Emphasis was on the hydraulic characteristics, quality with respect to domestic and irrigation purposes and influence of seawater. The study result revealed that the aquifer consist of intercalations of clayey sand and sand. The aquifer is characterized by high hydraulic conductivity and transmissivity values. The groundwater flow direction is southwards with higher groundwater depletion in the dry season. Groundwater samples from hand dug wells and boreholes were evaluated based on World Health Organization standard and some indices, respectively, for drinking and irrigation uses. The groundwaters are fit for drinking and domestic uses. However, more than 70 % of the pH values are not within the allowable limits of between 6.5 and 9.2 for drinking and domestic use. Therefore, it is recommended that neutralizing filter containing calcite or ground limestone should be applied to raise the pH of the groundwater. Of the 10 parameters used to assess the water for irrigation use, only sodium adsorption ratio (SAR), magnesium hazard (MH) and magnesium ratio indicated the excellent quality of these waters. Na+-K+-HCO3 - constitute the dominant water type. Total dissolved solids and ratios of Na+/Cl-, Mg2+/Cl-, and Ca2+/SO4 2- and saltwater mixing index (SMI) suggest some level of seawater intrusion in the area.

Application of helium isotopes in shallow groundwaters for geothermal energy exploration in the Upper Rhine Graben

International Nuclear Information System (INIS)

Freundt, Florian

2017-01-01

The helium isotope system is an established tool in hydrology for identifying mantle fluids in deep aquifers. This study applies the helium tracer system for the first time in shallow, unconfined aquifers of the Upper Rhine Graben. The Graben is a part of the Cenozoic Rift system of Western and Central Europe, a continental rift zone with unusually high geothermal gradients, making it an ideal region of Germany for geothermal energy development. The aim of this study is to develop a suite of natural groundwater tracers able to achieve a cost and effort reduction in geothermal prospection. The 3 He/ 4 He-ratio is therefore applied, as part of a multi-tracer approach including 3 H, δ 18 O, δ 2 H, δ 13 C, 14 C and 222 Rn, to identify and locate fault zones with suitable permeabilities for power plant operation. Three target areas along the graben were studied, each located on one of the main fault lines. A mantle-derived helium signature could be identified and separated from tritiogenic helium in a shallow aquifer in the north-west of the Graben. The mixing component of mantle-derived fluid in the shallow groundwater is calculated to reach up to 5%, based on the analysis of the 3 He/ 4 He isotope system. The employed method proves that the local permeability of the fault zone is high. The origin of the locally occurring upwelling of salinated water can be redetermined by the data.

High-throughput DNA microarray detection of pathogenic bacteria in shallow well groundwater in the Kathmandu Valley, Nepal.

Science.gov (United States)

Inoue, Daisuke; Hinoura, Takuji; Suzuki, Noriko; Pang, Junqin; Malla, Rabin; Shrestha, Sadhana; Chapagain, Saroj Kumar; Matsuzawa, Hiroaki; Nakamura, Takashi; Tanaka, Yasuhiro; Ike, Michihiko; Nishida, Kei; Sei, Kazunari

2015-01-01

Because of heavy dependence on groundwater for drinking water and other domestic use, microbial contamination of groundwater is a serious problem in the Kathmandu Valley, Nepal. This study investigated comprehensively the occurrence of pathogenic bacteria in shallow well groundwater in the Kathmandu Valley by applying DNA microarray analysis targeting 941 pathogenic bacterial species/groups. Water quality measurements found significant coliform (fecal) contamination in 10 of the 11 investigated groundwater samples and significant nitrogen contamination in some samples. The results of DNA microarray analysis revealed the presence of 1-37 pathogen species/groups, including 1-27 biosafety level 2 ones, in 9 of the 11 groundwater samples. While the detected pathogens included several feces- and animal-related ones, those belonging to Legionella and Arthrobacter, which were considered not to be directly associated with feces, were detected prevalently. This study could provide a rough picture of overall pathogenic bacterial contamination in the Kathmandu Valley, and demonstrated the usefulness of DNA microarray analysis as a comprehensive screening tool of a wide variety of pathogenic bacteria.

Influence of lateral groundwater flow in a shallow aquifer on eco-hydrological process in a shrub-grass coexistence semiarid area

Science.gov (United States)

Wang, Siru; Sun, Jinhua; Lei, Huimin; Zhu, Qiande; Jiang, Sanyuan

2017-04-01

Topography has a considerable influence on eco-hydrological processes resulting from the patterns of solar radiation distribution and lateral water flow. However, not much quantitative information on the contribution of lateral groundwater flow on ecological processes such as vegetation growth and evapo-transpiration is available. To fill this gap, we used a simple eco-hydrological model based on water balance with a 3D groundwater module that uses Darcy's law. This model was applied to a non-contributing area of 50km2 dominated by grassland and shrubland with an underlying shallow aquifer. It was calibrated using manually and remotely sensed vegetation data and water flux data observed by eddy covariance system of two flux towers as well as water table data obtained from HOBO recorders of 40 wells. The results demonstrate that the maximum hydraulic gradient and the maximum flux of lateral groundwater flow reached to 0.156m m-1 and 0.093m3 s-1 respectively. The average annual maximum LAI in grassland, predominantly in low-lying areas, improved by about 5.9% while that in shrubland, predominantly in high-lying areas, remained the same when lateral groundwater flow is considered adequately compared to the case without considering lateral groundwater flow. They also show that LAI is positively and nonlinearly related to evapotranspiration, and that the greater the magnitude of evapotranspiration, the smaller the rate of increase of LAI. The results suggest that lateral groundwater flow should not be neglected when simulating eco-hydrological process in areas with a shallow aquifer.

Characterization and comparison of iron oxyhydroxide precipitates from biotic and abiotic groundwater treatments

DEFF Research Database (Denmark)

Arturi, Katarzyna R.; Bender Koch, Christian; Søgaard, Erik G.

2017-01-01

Removal of iron is an important step in groundwater treatment for drinking water production. It is performed to prevent organoleptic issues and clogging in water supply systems. Iron can be eliminated with a purely physico-chemical (abiotic) method or biotically with the help of iron......-oxidizing bacteria (FeOB). Each of the purification methods requires different operating conditions and results in formation of iron oxyhydroxide (FeOOH) precipitates. Knowledge about the differences in composition and properties of the biotic and abiotic precipitates is desirable from a technical, but also...

Modelling of seasonal dynamics of Wetland-Groundwater flow interaction in the Canadian Prairies

Science.gov (United States)

Ali, Melkamu; Nussbaumer, Raphaël; Ireson, Andrew; Keim, Dawn

2015-04-01

Wetland-shallow groundwater interaction is studied at the St. Denis National Wildlife Area in Saskatchewan, Canada, located within the northern glaciated prairies of North America. Ponds in the Canadian Prairies are intermittently connected by fill-spill processes in the spring and growing season of some wetter years. The contribution of the ponds and wetlands to groundwater is still a significant research challenge. The objective of this study is to evaluate model's ability to reproduce observed effects of groundwater-wetland interactions including seasonal pattern of shallow groundwater table, intended flow direction and to quantify the depression induced infiltration from the wetland to the surrounding uplands. The integrated surface-wetland-shallow groundwater processes and the changes in land-energy and water balances caused by the flow interaction are simulated using ParFlow-CLM at a small watershed of 1km2 containing both permanent and seasonal wetland complexes. We compare simulated water table depth with piezometers reading monitored by level loggers at the watershed. We also present the strengths and limitations of the model in reproducing observed behaviour of the groundwater table response to the spring snowmelt and summer rainfall. Simulations indicate that the shallow water table at the uphill recovers quickly after major rainfall events in early summer that generates lateral flow to the pond. In late summer, the wetland supplies water to the surrounding upland when the evapotranspiration is higher than the precipitation in which more water from the root zone is up taken by plants. Results also show that Parflow-CLM is able to reasonably simulate the water table patterns response to summer rainfall, while it is insufficient to reproduce the spring snowmelt infiltration which is the most dominant hydrological process in the Prairies.

Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA

Science.gov (United States)

Mills, Taylor J.; Mast, M. Alisa; Thomas, Judith C.; Keith, Gabrielle L.

2016-01-01

Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water systems. This study presents groundwater chemistry and solid-phase geochemical data from the Uncompahgre River Basin in Western Colorado, an irrigated alluvial landscape underlain by Se-rich Cretaceous marine shale. We analyzed Se species, major and trace elements, and stable nitrogen and oxygen isotopes of nitrate in groundwater and aquifer sediments to examine processes governing selenium release and transport in the shallow groundwater system. Groundwater Se concentrations ranged from below detection limit (groundwater nitrate concentrations that maintain oxidizing conditions in the aquifer despite low dissolved oxygen concentrations. High nitrate concentrations in non-irrigated soils and nitrate isotopes indicate nitrate is largely derived from natural sources in the Mancos Shale and alluvial material. Thus, in contrast to areas that receive substantial NO3 inputs through inorganic fertilizer application, Se mitigation efforts that involve limiting NO3 application might have little impact on groundwater Se concentrations in the study area. Soluble salts are the primary source of Se to the groundwater system in the study area at-present, but they constitute a small percentage of the total Se content of core material. Sequential extraction results indicate insoluble Se is likely composed of reduced Se in recalcitrant organic matter or discrete selenide phases. Oxidation of reduced Se species that constitute the majority of the Se pool in the study area could be a potential source of Se in the future as soluble salts are progressively depleted.

Comparative Influences of Precipitation and River Stage on Groundwater Levels in Near-River Areas

Directory of Open Access Journals (Sweden)

Incheol Kim

2015-12-01

Full Text Available The sustainable performance of foundations of various urban buildings and infrastructures is strongly affected by groundwater level (GWL, as GWL causes changes in the stress state within soil. In the present study, the components affecting GWL were investigated, focusing on the effects of precipitation and river stage. These components were analyzed using a six-year database established for hydrological and groundwater monitoring data. Five study regions for which daily measured precipitation, river stage, and GWL data were available were compared. Different periods of precipitation, geographical characteristics, and local surface conditions were considered in the analysis. The results indicated that key influence components on GWL are different depending on the hydrological, geological, and geographical characteristics of the target regions. River stage had the strongest influence on GWL in urban areas near large rivers with a high ratio of paved surface. In rural areas, where the paved surface area ratio and soil permeability were low, the moving average showed a closer correlation to GWL than river stage. A moving average-based method to predict GWL variation with time was proposed for regions with a low ratio of paved surface area and low permeability soils.

High arsenic (As concentrations in the shallow groundwaters of southern Louisiana: Evidence of microbial controls on As mobilization from sediments

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Ningfang Yang

2016-03-01

Full Text Available Study region: The Mississippi Delta in southern Louisiana, United States. Study focus: The probable role that microbial respiration plays in As release from the shallow aquifer sediments. New hydrological insights for the region: Shallow groundwaters in southern Louisiana have been reported to contain elevated As concentrations, whereas mechanisms responsible for As release from sediments have rarely been studied in this region. Microbial respiration is generally considered the main mechanism controlling As release in reducing anoxic aquifers such as the shallow aquifers in southern Louisiana and those of the Bengal basin. This study investigates the role microbial respiration plays in As release from shallow aquifer sediments in southern Louisiana through sediment incubation experiments and porewater analysis. Arsenic concentrations were the lowest in the sterilized control experiments, slightly higher in the un-amended experiments, and the highest in the experiments amended with acetate, and especially those amended with both acetate and AQDS (9,10-anthraquinone-2,6-disulfonic acid. Although Fe and Mn generally decreased at the beginning of all the experiments, they did follow a similar trend to As after the decrease. Porewater analysis showed that As and Fe concentrations were generally positively correlated and were higher in the coarse-grained sediments than in the fine-grained sediments. Results of the investigation are consistent with microbial respiration playing a key role in As release from the shallow aquifers sediments in southern Louisiana. Keywords: Groundwater, Arsenic, Microbial respiration

Oskarshamn site investigation. Monitoring of shallow groundwater chemistry 2009

International Nuclear Information System (INIS)

Ericsson, Ulf

2010-06-01

In 2009 sampling of shallow ground water in water wells in soil has been performed in a regular programme at eight sites within the site investigation area at Oskarshamn. The purpose of the activity is to monitor (long term observation) and characterise the shallow ground water in the site investigation area. Some physical and chemical parameters were measured directly in the field but most parameters were analysed at different laboratories. The ground water sampling activity consisted of one programme, chemical programme class 5 (reduced). The large number of sites and parameters analysed have generated a large amount of data, which will later be used for advanced analysis and modelling. In this report the evaluation aims to give a simple overview of the results and to describe the quality of the data sampled 2009. As an addition radon activity was measured at fourteen sites in the area. Seven of these sites were the same as in the regular programme. The results showed a large variation between the wells. The concentrations of major ions and conductivity ranged from low to high or very high values. The concentration of HCO 3 also varied extensively throughout the investigation area, but since the concentrations were above 60 mg/l in most wells the results indicate a good ground water quality with respect to acidification. The concentration of heavy metals and trace elements also varied. High concentration of Pb in some of the wells indicated pollution. Since Pb had a similar relation to Al as most other elements it was argued that high concentrations of lead probably can be explained by the natural composition of minerals within the site investigation area. The ratio of δ 18 O showed a good relationship with the conductivity. The activity of tritium ( 3 H) was markedly lower in two of the wells. This might be an indication of older groundwater in these wells. The average hydrogen isotope ratio of deuterium (δ 2 H) varied with similar values in most wells. The �

Oskarshamn site investigation. Monitoring of shallow groundwater chemistry 2009

Energy Technology Data Exchange (ETDEWEB)

Ericsson, Ulf (Medins Biologi AB, Moelnlycke (Sweden))

2010-06-15

In 2009 sampling of shallow ground water in water wells in soil has been performed in a regular programme at eight sites within the site investigation area at Oskarshamn. The purpose of the activity is to monitor (long term observation) and characterise the shallow ground water in the site investigation area. Some physical and chemical parameters were measured directly in the field but most parameters were analysed at different laboratories. The ground water sampling activity consisted of one programme, chemical programme class 5 (reduced). The large number of sites and parameters analysed have generated a large amount of data, which will later be used for advanced analysis and modelling. In this report the evaluation aims to give a simple overview of the results and to describe the quality of the data sampled 2009. As an addition radon activity was measured at fourteen sites in the area. Seven of these sites were the same as in the regular programme. The results showed a large variation between the wells. The concentrations of major ions and conductivity ranged from low to high or very high values. The concentration of HCO{sub 3} also varied extensively throughout the investigation area, but since the concentrations were above 60 mg/l in most wells the results indicate a good ground water quality with respect to acidification. The concentration of heavy metals and trace elements also varied. High concentration of Pb in some of the wells indicated pollution. Since Pb had a similar relation to Al as most other elements it was argued that high concentrations of lead probably can be explained by the natural composition of minerals within the site investigation area. The ratio of delta18O showed a good relationship with the conductivity. The activity of tritium (3H) was markedly lower in two of the wells. This might be an indication of older groundwater in these wells. The average hydrogen isotope ratio of deuterium (delta2H) varied with similar values in most wells

Regional Variability of Agriculturally-Derived Nitrate-Nitrogen in Shallow Groundwater in China, 2004–2014

Directory of Open Access Journals (Sweden)

Jing Li

2018-05-01

Full Text Available Increasing diffuse nitrate loading of groundwater has long been a major environmental and health concern in China, but little is known about the spatial and temporal variability of nitrate concentrations in groundwater at regional scales. The aim of this study was to assess the spatial distribution and variation of nitrate-nitrogen (NO3−-N concentrations in groundwater. We used groundwater quality monitoring data and soil physical characteristics from 21 agro-ecosystems in China for years 2004 to 2014. The results indicated that NO3−-N concentrations were highly variable in shallow groundwater across the landscape. Over the study period, most of the NO3−-N concentrations were below the World Health Organization permissible limit for drinking water (<10 mg N·L. NO3−-N concentrations in groundwater neither significantly increased nor decreased in most agro-ecosystems, but fluctuated with seasons. In addition, groundwater NO3−-N under purple soil (6.81 mg·L−1 and Aeolian sandy soil (6.02 mg·L−1 were significantly higher (p < 0.05 than that under other soil types, and it was medium-high (4.49 mg·L−1 under aquic cinnamon soil. Elevated nitrate concentrations occurred mainly in oasis agricultural areas of northwestern China, where farmlands with coarse-textured soils use flood irrigation. Therefore, arid and semi-arid areas are expected to sustain high NO3−-N concentrations in groundwater. Mitigation strategies can prevent this problem, and include control of N fertilizer input, balanced fertilization, proper rotation system, adoption of improved irrigation methods, and establishment of environmental policies.

Perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion.

Science.gov (United States)

Zhou, Xiaobo; Helmers, Matthew J; Asbjornsen, Heidi; Kolka, Randy; Tomer, Mark D

2010-01-01

Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (NO3-N) concentrations in soil and shallow groundwater and to assess the potential for perennial filter strips (PFS) to mitigate increases in NO3-N levels. The study, conducted at the Neal Smith National Wildlife Refuge (NSNWR) in central Iowa, consisted of a balanced incomplete block design with 12 watersheds and four watershed-scale treatments having different proportions and topographic positions of PFS planted in native prairie grasses: 100% rowcrop, 10% PFS (toeslope position), 10% PFS (distributed on toe and as contour strips), and 20 PFS (distributed on toe and as contour strips). All treatments were established in fall 2006 on watersheds that were under bromegrass (Bromus L.) cover for at least 10 yr. Nonperennial areas were maintained under a no-till 2-yr corn (Zea mays L.)--soybean [Glycine max. (L.) Merr.] rotation since spring 2007. Suction lysimeter and shallow groundwater wells located at upslope and toeslope positions were sampled monthly during the growing season to determine NO3-N concentration from 2005 to 2008. The results indicated significant increases in NO3-N concentration in soil and groundwater following grassland-to-cropland conversion. Nitrate-nitrogen levels in the vadose zone and groundwater under PFS were lower compared with 100% cropland, with the most significant differences occurring at the toeslope position. During the years following conversion, PFS mitigated increases in subsurface nitrate, but long-term monitoring is needed to observe and understand the full response to land-use conversion.

California GAMA Program: Sources and transport of nitrate in shallow groundwater in the Llagas Basin of Santa Clara County, California

International Nuclear Information System (INIS)

Moran, J E; McNab, W; Esser, B; Hudson, G; Carle, S; Beller, H; Kane, S; Tompson, A B; Letain, T; Moore, K; Eaton, G; Leif, R; Moody-Bartel, C; Singleton, M

2005-01-01

A critical component of the State Water Resource Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program is to assess the major threats to groundwater resources that supply drinking water to Californians (Belitz et al., 2004). Nitrate is the most pervasive and intractable contaminant in California groundwater and is the focus of special studies under the GAMA program. This report presents results of a study of nitrate contamination in the aquifer beneath the cities of Morgan Hill and Gilroy, CA, in the Llagas Subbasin of Santa Clara County, where high nitrate levels affect several hundred private domestic wells. The main objectives of the study are: (1) to identify the main source(s) of nitrate that issue a flux to the shallow regional aquifer (2) to determine whether denitrification plays a role in the fate of nitrate in the subbasin and (3) to assess the impact that a nitrate management plan implemented by the local water agency has had on the flux of nitrate to the regional aquifer. Analyses of 56 well water samples for major anions and cations, nitrogen and oxygen isotopes of nitrate, dissolved excess nitrogen, tritium and groundwater age, and trace organic compounds, show that synthetic fertilizer is the most likely source of nitrate in highly contaminated wells, and that denitrification is not a significant process in the fate of nitrate in the subbasin except in the area of recycled water application. In addition to identifying contaminant sources, these methods offer a deeper understanding of how the severity and extent of contamination are affected by hydrogeology and groundwater management practices. In the Llagas subbasin, the nitrate problem is amplified in the shallow aquifer because it is highly vulnerable with high vertical recharge rates and rapid lateral transport, but the deeper aquifers are relatively more protected by laterally extensive aquitards. Artificial recharge delivers low-nitrate water and provides a means of long

Concurrent arsenic and microbe removal from groundwater using iron electro-coagulation: Mechanisms of E.coli attenuation

Science.gov (United States)

Delaire, C.; Van Genuchten, C. M.; Amrose, S. E.; Gadgil, A.

2013-12-01

Around 60 million people in South Asia drink groundwater from arsenic contaminated shallow aquifers. Research over the last two decades has focused on arsenic removal alone to mitigate this problem, largely ignoring possible microbial contamination of shallow groundwater. However, diarrheal diseases are still prevalent in the region and recently, fecal indicators and pathogens were detected in shallow tubewells in Bangladesh. Comprehensive treatment technologies addressing both microbial and arsenic contamination are needed and may have a higher social acceptability, contributing to their sustainability in resource poor areas. Iron electro-coagulation (EC) is a low-cost and low-waste process using small amounts of electricity to produce Fe(III)-oxides that serve as an adsorbent for arsenic and a coagulant for microbes. Iron EC relies on the oxidative dissolution of a Fe(0) anode to produce Fe(II) ions that rapidly oxidize and precipitate in the presence of oxygen. In the process, strong oxidants generated by Fenton-like reactions convert As(III) into As(V), which is more amenable to adsorption. In this work, we demonstrate that iron EC can simultaneously remove arsenic and the model organism E.coli in South Asian synthetic groundwater. We find that E.coli is attenuated because it adheres to iron precipitates and is trapped in aggregates that settle out. Some inactivation (~20%, as probed by membrane permeability stains) also takes place, likely due to oxidative stress caused by strong oxidants produced in Fenton-like reactions. We find that pH has a significant effect on E.coli removal from South Asian synthetic groundwater. The iron dosages required to achieve 4-log attenuation (from an initial concentration of 10^6.4 CFU/mL) at pH 6.6. and 7.5 are 25 and 140 mg-Fe/L respectively, other parameters being equal. In this pH range, iron precipitates generated in synthetic groundwater have a negative surface charge, whose variation cannot entirely explain the

The combined use of MODFLOW and precipitation-runoff modeling to simulate groundwater flow in a diffuse-pollution prone watershed.

Science.gov (United States)

Elçi, A; Karadaş, D; Fistikoğlu, O

2010-01-01

A numerical modeling case study of groundwater flow in a diffuse pollution prone area is presented. The study area is located within the metropolitan borders of the city of Izmir, Turkey. This groundwater flow model was unconventional in the application since the groundwater recharge parameter in the model was estimated using a lumped, transient water-budget based precipitation-runoff model that was executed independent of the groundwater flow model. The recharge rate obtained from the calibrated precipitation-runoff model was used as input to the groundwater flow model, which was eventually calibrated to measured water table elevations. Overall, the flow model results were consistent with field observations and model statistics were satisfactory. Water budget results of the model revealed that groundwater recharge comprised about 20% of the total water input for the entire study area. Recharge was the second largest component in the budget after leakage from streams into the subsurface. It was concluded that the modeling results can be further used as input for contaminant transport modeling studies in order to evaluate the vulnerability of water resources of the study area to diffuse pollution.

Use of mineral/solution equilibrium calculations to assess the potential for carnotite precipitation from groundwater in the Texas Panhandle, USA

Science.gov (United States)

Ranalli, Anthony J.; Yager, Douglas B.

2016-01-01

This study investigated the potential for the uranium mineral carnotite (K2(UO2)2(VO4)2·3H2O) to precipitate from evaporating groundwater in the Texas Panhandle region of the United States. The evolution of groundwater chemistry during evaporation was modeled with the USGS geochemical code PHREEQC using water-quality data from 100 groundwater wells downloaded from the USGS National Water Information System (NWIS) database. While most modeled groundwater compositions precipitated calcite upon evaporation, not all groundwater became saturated with respect to carnotite with the system open to CO2. Thus, the formation of calcite is not a necessary condition for carnotite to form. Rather, the determining factor in achieving carnotite saturation was the evolution of groundwater chemistry during evaporation following calcite precipitation. Modeling in this study showed that if the initial major-ion groundwater composition was dominated by calcium-magnesium-sulfate (>70 precent Ca + Mg and >50 percent SO4 + Cl) or calcium-magnesium-bicarbonate (>70 percent Ca + Mg and  mHCO3− + 2mCO3−2) carnotite saturation was achieved. If, however, the initial major-ion groundwater composition is sodium-bicarbonate (varying amounts of Na, 40–100 percent Na), calcium-sodium-sulfate, or calcium-magnesium-bicarbonate composition (>70 percent HCO3 + CO3) and following the precipitation of calcite, the concentration of calcium was less than the carbonate alkalinity (2mCa+2 < mHCO3- + 2mCO3−2) carnotite saturation was not achieved. In systems open to CO2, carnotite saturation occurred in most samples in evaporation amounts ranging from 95 percent to 99 percent with the partial pressure of CO2 ranging from 10−3.5 to 10−2.5 atm. Carnotite saturation occurred in a few samples in evaporation amounts ranging from 98 percent to 99 percent with the partial pressure of CO2 equal to 10−2.0 atm. Carnotite saturation did not occur in any groundwater with the system closed

Application of helium isotopes in shallow groundwaters for geothermal energy exploration in the Upper Rhine Graben

Energy Technology Data Exchange (ETDEWEB)

Freundt, Florian

2017-07-12

The helium isotope system is an established tool in hydrology for identifying mantle fluids in deep aquifers. This study applies the helium tracer system for the first time in shallow, unconfined aquifers of the Upper Rhine Graben. The Graben is a part of the Cenozoic Rift system of Western and Central Europe, a continental rift zone with unusually high geothermal gradients, making it an ideal region of Germany for geothermal energy development. The aim of this study is to develop a suite of natural groundwater tracers able to achieve a cost and effort reduction in geothermal prospection. The {sup 3}He/{sup 4}He-ratio is therefore applied, as part of a multi-tracer approach including {sup 3}H, δ{sup 18}O, δ{sup 2}H, δ{sup 13}C, {sup 14}C and {sup 222}Rn, to identify and locate fault zones with suitable permeabilities for power plant operation. Three target areas along the graben were studied, each located on one of the main fault lines. A mantle-derived helium signature could be identified and separated from tritiogenic helium in a shallow aquifer in the north-west of the Graben. The mixing component of mantle-derived fluid in the shallow groundwater is calculated to reach up to 5%, based on the analysis of the {sup 3}He/{sup 4}He isotope system. The employed method proves that the local permeability of the fault zone is high. The origin of the locally occurring upwelling of salinated water can be redetermined by the data.

Laboratory evaluation of the potential for in situ treatment of chromate-contaminated groundwater by chemical precipitation

International Nuclear Information System (INIS)

Thornton, E.C.; Beck, M.A.; Jurgensmeier, C.A.

1995-03-01

The objective of this paper is to present the results of a series of small-scale batch tests performed to assess the effectiveness of chemical precipitation in the remediation of chromate-contaminated groundwater. These tests involved treatment of chromate solutions with ferrous and sulfide ions. In addition, tests were conducted that involved treatment of mixtures of chromate-contaminated groundwater and uncontaminated soil with the ferrous ion. A combination of ferrous sulfate and sodium sulfide was also tested in the groundwater treatment tests, since this approach has been shown to be an efficient method for treating electroplating wastewaters

Sources and flow of north Canterbury Plains groundwater, New Zealand

International Nuclear Information System (INIS)

Taylor, C.B.; Brown, L.J.; Stewart, M.K.; Brailsford, G.W.; Wilson, D.D.; Burden, R.J.

1989-01-01

Geological, hydrological, isotope (tritium and 18 O) and chemical evidence is interpreted to give a mutually consistent picture of the recharge sources and flow patterns of the important groundwater resource in the deep Quaternary deposits of the Canterbury Plains between Selwyn R. and Ashley R. The study period for tritium measurements extends over 27 years, encompassing the peak and decline of thermonuclear tritium fallout in this region. Major rivers emerging from mountain catchments to the west of the Plains are depleted in 18 O relative to average low-level precipitation. Most of the groundwater is river-recharged, but some areas with significant local precipitation recharge are clearly identified by 18 O and chemical concentrations. Artesian groundwater underlying Christchurch ascends from deeper aquifers into the shallowest aquifer via gaps in the confining layers; much of this flow is induced by withdrawal. The Christchurch aquifers are recharged by infiltration from Waimakariri R. in its central Plains reaches, and the resulting flow regime is E- and SE-directed; satisfactory water quality of the deeper Christchurch aquifer appears to be guaranteed for the future provided the river can be maintained in its present condition. Shallow groundwater, and water recharged to depth by other rivers, irrigation and local precipitation on the unconfined western areas of the Plains, are more susceptible to agricultural and other pollutants; none of this water is encountered in the deeper aquifers under Christchurch. (author). 15 refs., 12 figs

The source of groundwater and solutes to Many Devils Wash at a former uranium mill site in Shiprock, New Mexico

Science.gov (United States)

Robertson, Andrew J.; Ranalli, Anthony J.; Austin, Stephen A.; Lawlis, Bryan R.

2016-04-21

The Shiprock Disposal Site is the location of the former Navajo Mill (Mill), a uranium ore-processing facility, located on a terrace overlooking the San Juan River in the town of Shiprock, New Mexico. Following the closure of the Mill, all tailings and associated materials were encapsulated in a disposal cell built on top of the former Mill and tailings piles. The milling operations, conducted at the site from 1954 to 1968, created radioactive tailings and process-related wastes that are now found in the groundwater. Elevated concentrations of constituents of concern—ammonium, manganese, nitrate, selenium, strontium, sulfate, and uranium—have also been measured in groundwater seeps in the nearby Many Devils Wash arroyo, leading to the inference that these constituents originated from the Mill. These constituents have also been reported in groundwater that is associated with Mancos Shale, the bedrock that underlies the site. The objective of this report is to increase understanding of the source of water and solutes to the groundwater beneath Many Devils Wash and to establish the background concentrations for groundwater that is in contact with the Mancos Shale at the site. This report presents evidence on three working hypotheses: (1) the water and solutes in Many Devils Wash originated from the operations at the former Mill, (2) groundwater in deep aquifers is upwelling under artesian pressure to recharge the shallow groundwater beneath Many Devils Wash, and (3) the groundwater beneath Many Devils Wash originates as precipitation that infiltrates into the shallow aquifer system and discharges to Many Devils Wash in a series of springs on the east side of the wash. The solute concentrations in the shallow groundwater of Many Devils Wash would result from the interaction of the water and the Mancos Shale if the source of water was upwelling from deep aquifers or precipitation.In order to compare the groundwater from various wells to groundwater that has been

Analysis on the Change in Shallow Groundwater Level based on Monitoring Electric Energy Consumption - A Case Study in the North China Plain

Science.gov (United States)

Wang, L.; Wolfgang, K.; Steiner, J. F.

2016-12-01

Groundwater has been over-pumped for irrigation in the North China Plain in the past decades causing a drastic decrease in the groundwater level. Shallow groundwater can be recharged by rainfall, and the aquifer could be rehabilitated for sustainable use. However, understanding and maintaining the balance of the aquifer - including climatic as well as anthropogenic influences - are fundamental to enable such a sustainable groundwater management. This is still severely obstructed by a lack of measurements of recharge and exploitation. A project to measure groundwater pumping rate at the distributed scale based on monitoring electric energy consumption is going on in Guantao County (456 km2) located in the southern part of the North China Plain. Considerably less costly than direct measurements of the pumping rate, this approach enables us to (a) cover a larger area and (b) use historic electricity data to reconstruct water use in the past. Pumping tests have been carried out to establish a relation between energy consumption and groundwater exploitation. Based on the results of the pumping tests, the time series of the pumping rate can be estimated from the historical energy consumption and serves as the input for a box model to reconstruct the water balance of the shallow aquifer for recent years. This helps us to determine the relative contribution of recharge due to rainfall as well as drawdown due to groundwater pumping for irrigation. Additionally, 100 electric meters have been installed at the electric transformers supplying power for irrigation. With insights gained from the pumping tests, real-time monitoring of the groundwater exploitation is achieved by converting the measured energy consumption to the water use, and pumping control can also be achieved by limiting the energy use. A monitoring and controlling system can then be set up to implement the strategy of sustainable groundwater use.

Determinants of the use of alternatives to arsenic-contaminated shallow groundwater: an exploratory study in rural West Bengal, India.

Science.gov (United States)

Delaire, Caroline; Das, Abhijit; Amrose, Susan; Gadgil, Ashok; Roy, Joyashree; Ray, Isha

2017-10-01

Shallow groundwater containing toxic concentrations of arsenic is the primary source of drinking water for millions of households in rural West Bengal, India. Often, this water also contains unpleasant levels of iron and non-negligible fecal contamination. Alternatives to shallow groundwater are increasingly available, including government-built deep tubewells, water purchased from independent providers, municipal piped water, and household filters. We conducted a survey of 501 households in Murshidabad district in 2014 to explore what influenced the use of available alternatives. Socioeconomic status and the perceived likelihood of gastrointestinal (GI) illness (which was associated with dissatisfaction with iron in groundwater) were the primary determinants of the use of alternatives. Arsenic knowledge was limited. The choice amongst alternatives was influenced by economic, social, and aesthetic factors, but not by health risk perceptions. The use of purchased water was rarely exclusive and was strongly associated with socioeconomic status, suggesting that this form of market-based water provision does not ensure universal access. Demand for purchased water appeared to decrease significantly shortly after free piped water became available at public taps. Our results suggest that arsenic mitigation interventions that also address co-occurring water problems (iron, GI illness) could be more effective than a focus on arsenic alone.

Controls on selenium distribution and mobilization in an irrigated shallow groundwater system underlain by Mancos Shale, Uncompahgre River Basin, Colorado, USA

Energy Technology Data Exchange (ETDEWEB)

Mills, Taylor J.; Mast, M. Alisa; Thomas, Judith; Keith, Gabrielle

2016-10-01

Elevated selenium (Se) concentrations in surface water and groundwater have become a concern in areas of the Western United States due to the deleterious effects of Se on aquatic ecosystems. Elevated Se concentrations are most prevalent in irrigated alluvial valleys underlain by Se-bearing marine shales where Se can be leached from geologic materials into the shallow groundwater and surface water systems. This study presents groundwater chemistry and solid-phase geochemical data from the Uncompahgre River Basin in Western Colorado, an irrigated alluvial landscape underlain by Se-rich Cretaceous marine shale. We analyzed Se species, major and trace elements, and stable nitrogen and oxygen isotopes of nitrate in groundwater and aquifer sediments to examine processes governing selenium release and transport in the shallow groundwater system. Groundwater Se concentrations ranged from below detection limit (< 0.5 μg L{sup −1}) to 4070 μg L{sup −1}, and primarily are controlled by high groundwater nitrate concentrations that maintain oxidizing conditions in the aquifer despite low dissolved oxygen concentrations. High nitrate concentrations in non-irrigated soils and nitrate isotopes indicate nitrate is largely derived from natural sources in the Mancos Shale and alluvial material. Thus, in contrast to areas that receive substantial NO{sub 3} inputs through inorganic fertilizer application, Se mitigation efforts that involve limiting NO{sub 3} application might have little impact on groundwater Se concentrations in the study area. Soluble salts are the primary source of Se to the groundwater system in the study area at-present, but they constitute a small percentage of the total Se content of core material. Sequential extraction results indicate insoluble Se is likely composed of reduced Se in recalcitrant organic matter or discrete selenide phases. Oxidation of reduced Se species that constitute the majority of the Se pool in the study area could be a potential

Modelling of the dissolution and reprecipitation of uranium under oxidising conditions in the zone of shallow groundwater circulation.

Science.gov (United States)

Dutova, Ekaterina M; Nikitenkov, Aleksei N; Pokrovskiy, Vitaly D; Banks, David; Frengstad, Bjørn S; Parnachev, Valerii P

2017-11-01

Generic hydrochemical modelling of a grantoid-groundwater system, using the Russian software "HydroGeo", has been carried out with an emphasis on simulating the accumulation of uranium in the aqueous phase. The baseline model run simulates shallow granitoid aquifers (U content 5 ppm) under conditions broadly representative of southern Norway and southwestern Siberia: i.e. temperature 10 °C, equilibrated with a soil gas partial CO 2 pressure (P CO2 , open system) of 10 -2.5 atm. and a mildly oxidising redox environment (Eh = +50 mV). Modelling indicates that aqueous uranium accumulates in parallel with total dissolved solids (or groundwater mineralisation M - regarded as an indicator of degree of hydrochemical evolution), accumulating most rapidly when M = 550-1000 mg L -1 . Accumulation slows at the onset of saturation and precipitation of secondary uranium minerals at M = c. 1000 mg L -1 (which, under baseline modelling conditions, also corresponds approximately to calcite saturation and transition to Na-HCO 3 hydrofacies). The secondary minerals are typically "black" uranium oxides of mixed oxidation state (e.g. U 3 O 7 and U 4 O 9 ). For rock U content of 5-50 ppm, it is possible to generate a wide variety of aqueous uranium concentrations, up to a maximum of just over 1 mg L -1 , but with typical concentrations of up to 10 μg L -1 for modest degrees of hydrochemical maturity (as indicated by M). These observations correspond extremely well with real groundwater analyses from the Altai-Sayan region of Russia and Norwegian crystalline bedrock aquifers. The timing (with respect to M) and degree of aqueous uranium accumulation are also sensitive to Eh (greater mobilisation at higher Eh), uranium content of rocks (aqueous concentration increases as rock content increases) and P CO2 (low P CO2 favours higher pH, rapid accumulation of aqueous U and earlier saturation with respect to uranium minerals). Copyright © 2017 Elsevier Ltd. All rights

Dynamics of trace elements in shallow groundwater of an agricultural land in the northeast of Mexico

Science.gov (United States)

Mora, Abrahan; Mahlknecht, Jürgen; Hernández-Antonio, Arturo

2017-04-01

The citrus zone located in northeastern Mexico covers an area of 8000 km2 and produces 10% of the Mexican citrus production. The aquifer system of this zone constitutes the major source of water for drinking and irrigation purposes for local population and provides base flows to surface water supplied to the city of Monterrey ( 4.5 million inhabitants). Although the study area is near the recharge zones, several works have reported nitrate pollution in shallow groundwater of this agricultural area, mainly due to animal manure and human waste produced by infiltration of urban sewers and septic tanks. Thus, the goals of this work were to assess the dynamics of selected trace elements in this aquifer system and determine if the trace element content in groundwater poses a threat to the population living in the area. Thirty-nine shallow water wells were sampled in 2010. These water samples were filtered through 0,45 µm pore size membranes and preserved with nitric acid for storage. The concentrations of Cd, Cs, Cu, Mo, Pb, Rb, Si, Ti, U, Y, and Zn were measured by ICP-MS. Also, sulfate concentrations were measured by ion chromatography in unacidified samples. Principal Component Analysis (PCA) performed in the data set show five principal components (PC). PC1 includes elements derived from silicate weathering, such as Si and Ti. The relationship found between Mo and U with sulfates in PC2 indicates that both elements show a high mobility in groundwater. Indeed, the concentrations of sulfate, Mo and U are increased as groundwater moves eastward. PC3 includes the alkali trace elements (Rb and Cs), indicating that both elements could be derived from the same source of origin. PC4 represents the heavy trace elements (Cd and Pb) whereas PC5 includes divalent trace elements such as Zn and Cu. None of the water samples showed trace element concentrations higher than the guideline values for drinking water proposed by the World Health Organization, which indicates that the

Groundwater salinity in coastal aquifer of Karachi, Pakistan

International Nuclear Information System (INIS)

Mashiatullah, A.; Qureshi, R.M.; Ahmad, E.; Tasneem, M.A.; Sajjad, M.I.; Khan, H.A.

2002-01-01

Potable groundwater salinity has become a problem of great concern in the Karachi Metropolis, which is not only the most populous and biggest industrial base but also the largest coastal dwelling of Pakistan. Stable isotope techniques [O/sup 18/ content of Oxygen in the water molecular and C/sup 13/ content of the Total Dissolved Inorganic Carbon (TDIC)] have been used, in conjunction with physiochemical tools (temperature, dissolved oxygen, pH, redox electrical conductivity, salinity), to examine the quality of potable water and the source of salinity. Surface water samples (12 No.) were collected from polluted streams, namely: Layeri River, Malir River; Hub River/Hub Lake and the Indus River. Shallow groundwater samples (7 No. ) were collected from operating dug wells. Relatively deep groundwater samples (12 No.) were collected from operating dug wells, relatively deep groundwater samples (12 No.) were collected from pumping wells/tube-wells. Physicochemical analysis of water samples was completed in the field. In the laboratory, water samples were analyzed for O/sup 18/ content of oxygen in the water molecule and C/sup 13/ content of the TDIC, using specific gas extraction systems and a modified GD-150 gas source mass spectrometer. It is concluded from this preliminary investigation that the potable aquifer system in coastal Karachi hosts a mixture of precipitation (rainwater only) from hinterlands, trapped seawater in relatively deep aquifer system, as well as intruded seawater under natural infiltration conditions and/or induced recharge conditions (in shallow aquifers). (author)

Effect of Organic Matter on Cr(VI Removal from Groundwaters by Fe(II Reductive Precipitation for Groundwater Treatment

Directory of Open Access Journals (Sweden)

Anna Gröhlich

2017-06-01

Full Text Available Due to its toxicity, Cr(VI is undesirable in groundwater. Its chemical reduction to Cr(III species, followed by precipitation is the most widely practiced treatment technique for the removal of Cr(VI from polluted waters. The resulting Cr(III species present low solubility, is much less toxic, and can be subsequently removed either by precipitation, or by adsorption onto iron oxy-hydroxides and co-precipitation. The effects of several parameters, such as the pH value of water to be treated, the applied Fe(II dose, and the presence of appropriate mineral surfaces, are well investigated and understood. However, the impact of the presence of humic acids (HAs in this process has only been considered by rather few studies. The main aim of this study was to determine the effect of humic substances on Fe(II reductive precipitation of Cr(VI within a pH range relevant for drinking water treatment. Jar test experiments were performed, using artificial groundwater of defined composition and initial Cr(VI concentration 100 μg/L, ferrous sulphate dosages 0.25–2 mg Fe(II/L, and pH values 6.5–8. It was found that Cr(VI and total chromium (Cr(total can be reliably removed in the absence of HAs in the tested pH range with the addition of Fe(II dosage of 1 mg Fe(II/L. Further on, the results indicated that the reduction of Cr(VI is only slightly affected by the presence of HAs. However, increased residual total Cr concentrations were found at lower Fe(II dosages and/or higher pH values. Additionally, the removal of the Cr(III species formed during Cr(VI reduction was strongly inhibited by the presence of HAs under the examined experimental conditions, since residual concentrations higher than 60 μg/L were determined. The results of this study will have implications to the ongoing discussion of a new, stricter, European Union regulation limit, regarding the presence of total chromium in drinking water.

Vertical Hydraulic Conductivity of Unsaturated Zone by Infiltrometer Analysis of Shallow Groundwater Regime (KUISG

Directory of Open Access Journals (Sweden)

Arkan Radhi Ali

2018-02-01

Full Text Available A hydrogeologic model was developed and carried out in Taleaa district of 67km2 . The study adopted a determination of KUISG depends upon the double rings infiltrometer model. The tests were carried out in a part of Mesopotamian  Zone which is covered with quaternary deposits  . In general the groundwater levels are about one meter below ground surface.  Theoretically, the inclination angle of the saturated water phase plays an important role in the determination of KUISG. The experimental results prove that the angle of inclination of the saturated phase is identical to the angle of internal friction of the soil. This conclusion is supported by the comparison of the results that obtained from falling head test and infiltrometer measurements for estimating the hydraulic conductivitiy values for ten locations within the study area. The determination of vertical hydraulic conductivity by current infiltrometer model is constrained to only the shallow groundwater regime.7

A geochemical approach to determine sources and movement of saline groundwater in a coastal aquifer.

Science.gov (United States)

Anders, Robert; Mendez, Gregory O; Futa, Kiyoto; Danskin, Wesley R

2014-01-01

Geochemical evaluation of the sources and movement of saline groundwater in coastal aquifers can aid in the initial mapping of the subsurface when geological information is unavailable. Chloride concentrations of groundwater in a coastal aquifer near San Diego, California, range from about 57 to 39,400 mg/L. On the basis of relative proportions of major-ions, the chemical composition is classified as Na-Ca-Cl-SO4, Na-Cl, or Na-Ca-Cl type water. δ(2)H and δ(18)O values range from -47.7‰ to -12.8‰ and from -7.0‰ to -1.2‰, respectively. The isotopically depleted groundwater occurs in the deeper part of the coastal aquifer, and the isotopically enriched groundwater occurs in zones of sea water intrusion. (87)Sr/(86)Sr ratios range from about 0.7050 to 0.7090, and differ between shallower and deeper flow paths in the coastal aquifer. (3)H and (14)C analyses indicate that most of the groundwater was recharged many thousands of years ago. The analysis of multiple chemical and isotopic tracers indicates that the sources and movement of saline groundwater in the San Diego coastal aquifer are dominated by: (1) recharge of local precipitation in relatively shallow parts of the flow system; (2) regional flow of recharge of higher-elevation precipitation along deep flow paths that freshen a previously saline aquifer; and (3) intrusion of sea water that entered the aquifer primarily during premodern times. Two northwest-to-southeast trending sections show the spatial distribution of the different geochemical groups and suggest the subsurface in the coastal aquifer can be separated into two predominant hydrostratigraphic layers. © 2013, National Ground Water Association.

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

A report on isotope hydrology of groundwater in Bangladesh: implications for characterization and mitigation of arsenic in groundwater

Energy Technology Data Exchange (ETDEWEB)

Aggarwal, P K; Froehlich, K [International Atomic Energy Agency, Isotope Hydrology Section, Vienna (Austria); Basu, A R; Poreda, R J [Department of Earth Sciences, University of Rochester Rochester, New York (United States); Kulkarni, K M [Bhabha Atomic Research Centre, Isotope Hydrology Section, Trombay, Mumbai (India); Tarafdar, S A; Ali, Mohamed; Ahmed, Nasir [Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Hussain, Alamgir; Rahman, Mizanur; Ahmed, Syed Reazuddin [Bangladesh Water Development Board, Dhaka (Bangladesh)

2000-12-01

An investigation of the source and dynamics of groundwater in Bangladesh has been conducted with environmental isotope tracers. The primary objective of this study was to provide a scientific basis for developing mitigation strategies by characterizing the mechanism of arsenic mobilization in groundwater and the present and future status of arsenic contamination in deeper aquifers. About 55 shallow and deep groundwater samples ranging in depth from 10 to 335 m were collected and analyzed for their chemical and isotopic compositions. Distinct patterns of isotope compositions are found in shallow and deep groundwaters. Arsenic contamination is found to be present mostly in shallow groundwater to depths of less than 70 m. Groundwater samples from deep wells containing elevated arsenic concentrations are found to contain water mostly from shallow aquifers and do not indicate arsenic contamination of deeper aquifers. However, depth in itself is not a criterion that can be reliably or easily used to find arsenic-free, safe drinking water. Water with high arsenic concentrations sampled from 'deep' wells may not be representative of deep aquifers, and presently uncontaminated water from somewhat deeper wells ({approx}100 m) may not remain so over a long period of time. Increased exploitation of deep groundwater ({approx}300 m) such as in the Barisal area appears to be possible without fear of arsenic contamination from shallow aquifers. However, the potential for groundwater mining is clearly evident and the sustainability of this resource needs to be evaluated. The exponential increase in groundwater exploitation between 1979 and 1999 does not appear to have affected the overall hydrodynamics of shallow and deep aquifers and, by implication, the arsenic mobilization processes. Currently favored mechanisms of arsenic mobilization are found to be inconsistent with isotope data. The most likely process of arsenic mobilization may involve desorption from the sediments as a

A report on isotope hydrology of groundwater in Bangladesh: implications for characterization and mitigation of arsenic in groundwater

International Nuclear Information System (INIS)

Aggarwal, P.K.; Froehlich, K.; Basu, A.R.; Poreda, R.J.; Kulkarni, K.M.; Tarafdar, S.A.; Mohamed Ali; Nasir Ahmed; Alamgir Hussain; Mizanur Rahman; Syed Reazuddin Ahmed

2000-12-01

An investigation of the source and dynamics of groundwater in Bangladesh has been conducted with environmental isotope tracers. The primary objective of this study was to provide a scientific basis for developing mitigation strategies by characterizing the mechanism of arsenic mobilization in groundwater and the present and future status of arsenic contamination in deeper aquifers. About 55 shallow and deep groundwater samples ranging in depth from 10 to 335 m were collected and analyzed for their chemical and isotopic compositions. Distinct patterns of isotope compositions are found in shallow and deep groundwaters. Arsenic contamination is found to be present mostly in shallow groundwater to depths of less than 70 m. Groundwater samples from deep wells containing elevated arsenic concentrations are found to contain water mostly from shallow aquifers and do not indicate arsenic contamination of deeper aquifers. However, depth in itself is not a criterion that can be reliably or easily used to find arsenic-free, safe drinking water. Water with high arsenic concentrations sampled from 'deep' wells may not be representative of deep aquifers, and presently uncontaminated water from somewhat deeper wells (∼100 m) may not remain so over a long period of time. Increased exploitation of deep groundwater (∼300 m) such as in the Barisal area appears to be possible without fear of arsenic contamination from shallow aquifers. However, the potential for groundwater mining is clearly evident and the sustainability of this resource needs to be evaluated. The exponential increase in groundwater exploitation between 1979 and 1999 does not appear to have affected the overall hydrodynamics of shallow and deep aquifers and, by implication, the arsenic mobilization processes. Currently favored mechanisms of arsenic mobilization are found to be inconsistent with isotope data. The most likely process of arsenic mobilization may involve desorption from the sediments as a result of

Structure of Fe(III) precipitates generated by Fe(0) electrocoagulation in the presence of groundwater ions

Science.gov (United States)

van Genuchten, C. M.; Pena, J.; Addy, S. E.; Gadgil, A. J.

2012-12-01

Electrocoagulation (EC) using Fe(0) electrodes is an inexpensive and efficient technology capable of removing a variety of contaminants from water supplies. Because of its ease of use and modest electricity and Fe(0) requirements, EC has potential as an arsenic-removal technology for rural South Asia, where millions drink groundwater contaminated by arsenic. In EC, a small external voltage applied to a sacrificial Fe(0) anode in contact with an electrolyte (e.g. pumped groundwater containing arsenic) promotes the oxidative dissolution of Fe ions, which polymerize and create reactive hydrous ferric oxides (HFO) in-situ with a high affinity for binding contaminants. The chemical composition of the electrolyte influences EC performance. For example, major inorganic ions present in groundwater (e.g. Ca, Mg, P, As(V), Si) alter the pathway by which FeO6 oligomers polymerize to form crystalline Fe (oxyhydr)oxide minerals. Because the precipitate structure largely determines properties that govern the efficiency of EC systems (e.g. precipitate reactivity and colloidal stability), it is essential to understand the individual and interdependent structural effects of common groundwater ions. In this work, we integrate Fe K-edge EXAFS spectroscopy with the Pair Distribution Function (PDF) technique to create a detailed description of EC precipitate structure as a function of electrolyte chemistry. EC precipitate samples were generated in a range of individual and combined concentrations of Ca, Mg, P, As(V), and Si, encompassing most of the typical levels found in natural groundwater. Combining complementary EXAFS and PDF techniques with batch uptake experiments and general chemical reasoning, we obtain structural representations of EC precipitates that are inaccessible with any single characterization technique. Our results indicate that the presence of As(V), P, and Si oxyanions promote the formation of nanoscale material bearing similar, but not identical, intermediate

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

Water resources management strategies and its implications on hydrodynamic and hydrochemical changes of costal groundwater: Case of Grombalia shallow aquifer, NE Tunisia

Science.gov (United States)

Lachaal, Fethi; Chekirbane, Anis; Chargui, Sameh; Sellami, Haykel; Tsujimura, Maki; Hezzi, Hmida; Faycel, Jelassi; Mlayah, Ammar

2016-12-01

Information on groundwater quantity as well as quality is required by water managers and decision-makers for defining a sustainable management strategy. This requires a comprehensive assessment of the surface water and groundwater resources. This paper provides an assessment of water resources management strategy in the Grombalia region (Northeast Tunisia) and its impact on quantity and quality evolution of groundwater resources based on an approach that combines (i) hydro-climatic data, (ii) field monitoring, (iii) historic piezometric records, and (iv) geochemical and stable isotopes (δ18O and δ2H) analyses. We apply this approach to identify the origin of the various water resources and outline how the actual water management impact the quantity and quality of the groundwater in the region. As consequence of poor water resources management, the shallow groundwater levels have been disrupted: a groundwater rise is observed in the centre and a piezometric drawdown is observed in the upstream regions. Groundwater quality degradation was registered especially in the centre and downstream zones.

Impact of mixing chemically heterogeneous groundwaters on the sustainability of an open-loop groundwater heat pump

Science.gov (United States)

Burté, L.; Farasin, J.; Cravotta, C., III; Gerard, M. F.; Cotiche Baranger, C.; Aquilina, L.; Le Borgne, T.

2017-12-01

Geothermal systems using shallow aquifers are commonly used for heating and cooling. The sustainability of these systems can be severely impacted by the occurrence of clogging process. The geothermal loop operation (including pumping of groundwater, filtering and heat extraction through exchangers and cooled water injection) can lead to an unexpected biogeochemical reactivity and scaling formation that can ultimately lead to the shutdown of the geothermal doublet. Here, we report the results of investigations carried out on a shallow geothermal doublet (dynamic). Hydrochemical data collected at the pumping well showed that groundwater was chemically heterogeneous long the 11 meters well screen. While the aquifer was dominantly oxic, a localized inflow of anoxic water was detected and evaluated to produce about 40% of the total flow . The mixture of chemically heterogeneous water induced by pumping lead to the oxidation of reductive species and thus to the formation of biogenic precipitates responsible for clogging. The impact of pumping waters of different redox potential and chemical characteristics was quantified by numerical modeling using PHREEQC. These results shows that natural chemical heterogeneity can occur at a small scale in heterogeneous aquifers and highlight the importance of their characterization during the production well testing and the geothermal loop operation in order to take preventive measures to avoid clogging.

Shifts in pore connectivity from precipitation versus groundwater rewetting increases soil carbon loss after drought

Energy Technology Data Exchange (ETDEWEB)

Smith, Ashly P.; Bond-Lamberty, Benjamin; Benscoter, Brian W.; Tfaily, Malak M.; Hinkle, Ross; Liu, Chongxuan; Bailey, Vanessa L.

2017-11-06

Droughts and other extreme precipitation events are predicted to increase in intensity, duration and extent, with uncertain implications for terrestrial carbon (C) sequestration. Soil wetting from above (precipitation) results in a characteristically different pattern of pore-filling than wetting from below (groundwater), with larger, well-connected pores filling before finer pore spaces, unlike groundwater rise in which capillary forces saturate the finest pores first. Here we demonstrate that pore-scale wetting patterns interact with antecedent soil moisture conditions to alter pore-, core- and field-scale C dynamics. Drought legacy and wetting direction are perhaps more important determinants of short-term C mineralization than current soil moisture content in these soils. Our results highlight that microbial access to C is not solely limited by physical protection, but also by drought or wetting-induced shifts in hydrologic connectivity. We argue that models should treat soil moisture within a three-dimensional framework emphasizing hydrologic conduits for C and resource diffusion.

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.

Groundwater response to heavy precipitation

International Nuclear Information System (INIS)

Waring, C.; Bradd, J.; Hankin, S.

2003-05-01

An investigation of the groundwater response to heavy rainfall at Lucas Heights Science and Technology Centre (LHSTC) is required under the conditions of Facility Licence F0001 for the ANSTO's Replacement Research Reactor. Groundwater continuous hydrograph monitoring has been used for this purpose. Hydrograph data from four boreholes are presented showing the rainfall recorded during the same period for comparison. The drought conditions have provided only limited cases where groundwater responded to a rainfall event. The characteristic response was local, caused by saturated soil contributing water directly to the borehole and the falling head as the water was redistributed into he aquifer in a few hours. Hydrograph data from borehole near the head of a gully showed that groundwater flow from the plateau to the gully produced a peak a fe days after the rainfall event and that the water level returned to its original level after about 10 days. The hydrograph data are consistent with an imperfect multi-layer groundwater flow regime, developed from earlier seismic and geophysical data, with decreasing rate of flow in each layer due to decreasing hydraulic conductivity with depth. The contrast in hydraulic conductivity between the thin permeable soil layer and the low permeable sandstone forms an effective barrier to vertical flow

Application of Isotope Techniques in the Assessment of Groundwater Resource in Water Resources Region 10, Philippines

International Nuclear Information System (INIS)

Racadio, Charles Darwin T.; Mendoza, Norman DS.; Castañeda, Soledad S.; Abaño, Susan P.; Rongavilla, Luis S.; Castro, Joey

2015-01-01

Groundwater has been the primary source of drinking water of about 50% of the people in the Philippines and the numbers continue to rise. However, data and information on groundwater resources are generally spasmodic or sparse in the country. A specific remedy to address this gap is the use of isotope hydrological techniques. A pilot project utilizing this technique was done in Water Resources Region X with the aim of demonstrating the effectiveness and efficiency of these approach in groundwater resources assessment. When optimized, the technique will be replicated in other areas of the country. Groundwater samples from springs deep wells hand pumps and dug wells and river water were collected within the study area from September 2012 to June 2014. Monthly integrated precipitation samples were also collected at different points within the study area from October 2012 to March 2015. Samples were analyzed for stable isotope (δ”2H and δ”1”8O) using Laser Water Isotope Analyzer and tritium for groundwater dating. Results showed that aquifers in the study area are recharged by infiltrated rain during the heavy rainfall moths (May to November for Cagayan-Tagaloan Basin, and December to April for Agusan Basin). Water in Agusan Basin is isotopically enriched compared with the water in Cagayan-Tagaloan Basin. There appears to be interaction between shallow unconfined aquifer and deep semi-confined aquifer in Cagayan de Oro City. Shallow aquifers appear to be recharged by local precipitation. Groundwater in the study area is of Ca-Mg-HCO 3 type, which is characteristic of dynamic water with short residence time. Tritium-helium aging puts the water at ages between 18 to 72 years. Recharged rates of 422 to 625 mm/year were calculated for Cagayan de Oro City.(author)

Redox control of arsenic mobilization in Bangladesh groundwater

International Nuclear Information System (INIS)

Zheng, Y.; Stute, M.; Geen, A. van; Gavrieli, I.; Dhar, R.; Simpson, H.J.; Schlosser, P.; Ahmed, K.M.

2004-01-01

Detailed hydrochemical measurements, δ 34 S SO4 and 3 H analyses were performed on 37 groundwater samples collected during February 1999, January and March 2000 from 6 locations in eastern and southeastern Bangladesh to examine redox processes that lead to As mobilization in groundwater. The study sites were chosen based on available nation-wide As surveys to span the entire spectrum of As concentrations in Bangladesh groundwater, and to represent 3 of 5 major geological units of the Ganges-Brahmaputra Delta: uplifted Pleistocene terrace, fluvial flood plain and delta plain. Arsenic was found to be mobilized under Fe-reducing conditions in shallow aquifers ( 4 -reducing conditions, suggesting that authigenic sulfide precipitation does not constitute a significant sink for As in these groundwaters. The redox state of the water was characterized by a variety of parameters including dissolved O 2 , NO 3 - , Mn 2+ , Fe 2+ concentrations, and SO 4 2- /Cl - ratios. High dissolved [As] (> 50 μg/l; or > 0.7 μM ) were always accompanied by high dissolved [HCO 3 - ] (> 4 mM), and were close to saturation with respect to calcite. Groundwater enriched in As (200-800 μg/l; or 2.7-10.7 μM) and phosphate (30-100 μM) but relatively low in dissolved Fe (5-40 μM) probably resulted from re-oxidation of reducing, As and Fe enriched water. This history was deduced from isotopic signatures of δ 34 S SO4 and 3 H 2 O ( 3 H) to delineate the nature of redox changes for some of the reducing groundwaters. In contrast, As is not mobilized in presumed Pleistocene aquifers, both shallow (30-60 m) and deep (150-270 m), because conditions were not reducing enough due to lack of sufficient O 2 demand

Groundwater penetrating radar and high resolution seismic for locating shallow faults in unconsolidated sediments

International Nuclear Information System (INIS)

Wyatt, D.E.

1993-01-01

Faults in shallow, unconsolidated sediments, particularly in coastal plain settings, are very difficult to discern during subsurface exploration yet have critical impact to groundwater flow, contaminant transport and geotechnical evaluations. This paper presents a case study using cross-over geophysical technologies in an area where shallow faulting is probable and known contamination exists. A comparison is made between Wenner and dipole-dipole resistivity data, ground penetrating radar, and high resolution seismic data. Data from these methods were verified with a cone penetrometer investigation for subsurface lithology and compared to existing monitoring well data. Interpretations from these techniques are compared with actual and theoretical shallow faulting found in the literature. The results of this study suggests that (1) the CPT study, combined with the monitoring well data may suggest that discontinuities in correlatable zones may indicate that faulting is present (2) the addition of the Wenner and dipole-dipole data may further suggest that offset zones exist in the shallow subsurface but not allow specific fault planes or fault stranding to be mapped (3) the high resolution seismic data will image faults to within a few feet of the surface but does not have the resolution to identify the faulting on the scale of our models, however it will suggest locations for upward continuation of faulted zones (4) offset 100 MHz and 200 MHz CMP GPR will image zones and features that may be fault planes and strands similar to our models (5) 300 MHz GPR will image higher resolution features that may suggest the presence of deeper faults and strands, and (6) the combination of all of the tools in this study, particularly the GPR and seismic may allow for the mapping of small scale, shallow faulting in unconsolidated sediments

Remediation of arsenic-contaminated groundwater by in-situ stimulating biogenic precipitation of iron sulfides.

Science.gov (United States)

Pi, Kunfu; Wang, Yanxin; Xie, Xianjun; Ma, Teng; Liu, Yaqing; Su, Chunli; Zhu, Yapeng; Wang, Zhiqiang

2017-02-01

Severe health problems due to elevated arsenic (As) in groundwater have made it urgent to develop cost-effective technologies for As removal. This field experimental study tested the feasibility of in-situ As immobilization via As incorporation into newly formed biogenic Fe(II) sulfides in a typical As-affected strongly reducing aquifer at the central part of Datong Basin, China. After periodic supply of FeSO 4 into the aquifer for 25 d to stimulate microbial sulfate reduction, dissolved sulfide concentrations increased during the experiment, but the supplied Fe(II) reacted quickly with sulfide to form Fe(II)-sulfides existing majorly as mackinawite as well as a small amount of pyrite-like minerals in sediments, thereby restricting sulfide build-up in groundwater. After the completion of field experiment, groundwater As concentration decreased from an initial average value of 593 μg/L to 159 μg/L, with an overall As removal rate of 73%, and it further declined to 136 μg/L adding the removal rate up to 77% in 30 d after the experiment. The arsenite/As total ratio gradually increased over time, making arsenite to be the predominant species in groundwater residual As. The good correlations between dissolved Fe(II), sulfide and As concentrations, the increased abundance of As in newly-formed Fe sulfides as well as the reactive-transport modeling results all indicate that As could have been adsorbed onto and co-precipitated with Fe(II)-sulfide coatings once microbial sulfate reduction was stimulated after FeSO 4 supply. Under the strongly reducing conditions, sulfide may facilitate arsenate reduction into arsenite and promote As incorporation into pyrite or arsenopyrite. Therefore, the major mechanisms for the in-situ As-contaminated groundwater remediation can be As surface-adsorption on and co-precipitation with Fe(II) sulfides produced during the experimental period. Copyright © 2016. Published by Elsevier Ltd.

Spatiotemporal variation of the surface water effect on the groundwater recharge in a low-precipitation region: Application of the multi-tracer approach to the Taihang Mountains, North China

Science.gov (United States)

Sakakibara, Koichi; Tsujimura, Maki; Song, Xianfang; Zhang, Jie

2017-02-01

Groundwater recharge variations in time and space are crucial for effective water management, especially in low-precipitation regions. To determine comprehensive groundwater recharge processes in a catchment with large seasonal hydrological variations, intensive field surveys were conducted in the Wangkuai Reservoir watershed located in the Taihang Mountains, North China, during three different times of the year: beginning of the rainy season (June 2011), mid-rainy season (August 2012), and dry season (November 2012). Oxygen and hydrogen isotope and chemical analyses were conducted on the groundwater, spring water, stream water, and reservoir water of the Wangkuai Reservoir watershed. The results were processed using endmember mixing analysis to determine the amount of contribution of the groundwater recharging processes. Similar isotopic and chemical signatures between the surface water and groundwater in the target area indicate that the surface water in the mountain-plain transitional area and the Wangkuai Reservoir are the principal groundwater recharge sources, which result from the highly permeable geological structure of the target area and perennial large-scale surface water, respectively. Additionally, the widespread and significant effect of the diffuse groundwater recharge on the Wangkuai Reservoir was confirmed with the deuterium (d) excess indicator and the high contribution throughout the year, calculated using endmember mixing analysis. Conversely, the contribution of the stream water to the groundwater recharge in the mountain-plain transitional area clearly decreases from the beginning of the rainy season to the mid-rainy season, whereas that of the precipitation increases. This suggests that the main groundwater recharge source shifts from stream water to episodic/continuous heavy precipitation in the mid-rainy season. In other words, the surface water and precipitation commonly affect the groundwater recharge in the rainy season, whereas the

Nitrate Leaching under Vegetable Fields above a Shallow Aquifer in Slovenia

International Nuclear Information System (INIS)

Zupanc, V.; Sturm, M.; Lojen, S.; Marsic-Kacjana, N.; Pintar, M.; Adu-Gyamfi, J.; Bracic-Zeleznik, B.; Urbanc, J.

2012-01-01

Shallow aquifers can be prone to nitrate pollution, especially in rural, high rainfall zones under intensive vegetable production, as well as in areas with urban and industrial pollution. Due to its mobility in the soil, nitrate is the most problematic pollutant in intensive agricultural production areas. The risk of nitrate leaching is closely related to the excessive application of organic and inorganic nitrogen (N) fertilizers and can occur at and after harvest, as well as during the crop cycle, because of excessive irrigation or heavy precipitation. The impact of agriculture on groundwater quality can be minimized through improved nitrogen and water management (irrigation) practices, which should be evaluated with regard to their production, polluting effects and cost effectiveness. Most of the Slovenian highly fertile arable lands occur on plains in the shallow groundwater recharge zones, and are used for intensive fresh vegetable production, an important source of income generation for the farmers. These shallow alluvial aquifers are, however, one of the country's most important sources of drinking water. This leads to a conflict of interest between drinking water resource protection and agricultural production. The common farming practice in Slovenia is to broadcast fertilizer applications which often results in extensive nitrate leaching. Thus nitrate management in agriculture is a contentious issue, as adequate nitrogen fertilization is required to ensure reasonable crop yields, yet excessive N fertilization can lead to groundwater pollution. Through an IAEA technical cooperation project SLO 5002 Protecting Groundwater and Soil Pollutants using Nuclear echniques, various irrigation, nitrogen and cropping system management strategies for the production of vegetables with a shorter growing period were assessed at a benchmark site in Slovenia during the years 2006 and 2007. Four irrigation and fertilization treatments were applied: (1) 50% drip irrigation of

The Effects of Different Scales of Topographic Variation on Shallow Groundwater Flow in an Arctic Watershed

Science.gov (United States)

Nicholaides, K. D.; O'Connor, M.; Cardenas, M. B.; Neilson, B. T.; Kling, G. W.

2017-12-01

Arctic permafrost degradation is occurring as global temperatures increase. In addition, recent evidence shows the Arctic is shifting from a sink to a source of carbon to the atmosphere. However, the cause of this shift is unclear, as is the role of newly exposed organic soil carbon leaching into groundwater and transported to surface water. This soil carbon may be photo-oxidized to CO2 or microbially respired to CO2 and methane, adding greenhouse gases to the atmosphere. The fate of carbon in permafrost is largely governed by the length of time spent in transport and the surface or subsurface route it follows. However, groundwater flow regimes within shallow active layer aquifers overlying permafrost is poorly understood. We determined to what extent smaller scale topography influences groundwater flow and residence times in arctic tundra. The study focused on Imnavait Creek watershed, a 1st-order drainage on the Alaskan North Slope underlain by continuous permafrost. We used direct measurements of hydraulic conductivities and porosities over a range of depths as well as basin-scale topography to develop vertically-integrated groundwater flow models. By systematically decreasing the amount of topographic detail, we were able to compare the influence of more detailed topography on groundwater flow estimates. Scaling up this model will be a useful tool in understanding how larger basins in permafrost will respond to future climate change and their contributions to greenhouse gases in the atmosphere.

The characteristic and influence factors of extinction depth of shallow groundwater on the high-latitude region: a case study on the Sanjiang Plain, northeast China.

Science.gov (United States)

Wang, Xihua

2018-03-01

Accurate estimation of extinction depth of shallow groundwater (EDSG) and identification of its influence factors are important for sustainable management of groundwater resources, ecological protection, and human health in intensively irrigated region. In this study, the ratio of actual groundwater depth and EDSG (RAE) method was used to understand the spatial variability of EDSG in the Sanjiang Plain, one of China's largest grain production bases and China's largest inland freshwater wetland region. The study showed a large spatial variation of EDSG in the region. Spatially, the sites, which were in the northeast and center had the deepest and the shallowest EDSG, whereby, indicate that it has higher and lower pumping potential capacity. Many factors including climate, soil parameters, vegetation and topography affected the EDSG. We also identified an area of 3.86 × 10 10  m 2 , which accounting for 35.3% of the entire Sanjiang Plain, has exceeded the ESGD by over exploited for years. Knowledge of the variation and influence factors of EDSG for a certain plant system and the current shallow groundwater condition in the higher latitude region can be a key to the development of preventive actions for large quantity pumping groundwater and protection regional and sustainable development of irrigated agriculture.

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.

Characterization of Chlorinated Aliphatic Hydrocarbons and Environmental Variables in a Shallow Groundwater in Shanghai Using Kriging Interpolation and Multifactorial Analysis.

Directory of Open Access Journals (Sweden)

Qiang Lu

Full Text Available CAHs, as a cleaning solvent, widely contaminated shallow groundwater with the development of manufacturing in China's Yangtze River Delta. This study focused on the distribution of CAHs, and correlations between CAHs and environmental variables in a shallow groundwater in Shanghai, using kriging interpolation and multifactorial analysis. The results showed that the overall CAHs plume area (above DIV was approximately 9,000 m(2 and located in the 2-4 m underground, DNAPL was accumulated at an area of approximately 1,400 m(2 and located in the 6-8m sandy silt layer on the top of the muddy silty clay. Heatmap of PPC for CAHs and environmental variables showed that the correlation between "Fe(2+" and most CAHs such as "1,1,1-TCA", "1,1-DCA", "1,1-DCE" and "%TCA" were significantly positive (p<0.001, but "%CA" and/or "%VC" was not, and "Cl-" was significantly positive correlated with "1,1-DCA" and "1,1-DCE" (p<0.001. The PCA demonstrated that the relative proportions of CAHs in groundwater were mostly controlled by the sources and the natural attenuation. In conclusion, the combination of geographical and chemometrics was helpful to establishing an aerial perspective of CAHs and identifying reasons for the accumulation of toxic dechlorination intermediates, and could become a useful tool for characterizing contaminated sites in general.

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.

Water-rock interaction and chemistry of groundwaters from the Canadian Shield

International Nuclear Information System (INIS)

Frape, S.K.; Fritz, P.; McNutt, R.H.

1984-01-01

The chemical and isotopic compositions of groundwaters in the crystalline rocks of the Canadian Shield reflect different degrees of rock-water interactions. The chemistry of the shallow, geochemically immature ground waters and especially of the major cations is controlled by local rock compositions, whereby dissolution reactions dominate. Conservative constituents, such as chloride and bromide, however, are not entirely a result of such reactions but appear to be readily added from leachable salts during the initial stages of the geochemical evolution of these waters. Their concentration changes little as major cations increase, until concentrations of Total Dissolved Solids (TDS) reach 3000 to 5000 mg l -1 . The isotopic composition of these shallow waters reflects local, present day precipitations. In contrast to the shallow groundwaters, the isotopic and chemical compositions of the deep, saline waters and brines are determined by extensive, low-temperature rock-water interactions. This is documented in major ion chemistries, 18 O contents and strontium isotopic compositions. These data indicate that the deep brines have been contained in hydrologically isolated pockets. The almost total loss of primary compositions make discussions on the origin of these brines very speculative. However, all brines from across the Canadian Shield have a very similar chemical composition, which probably reflects a common geochemical history. (author)

Groundwater Origins and Circulation Patterns Based on Isotopes in Challapampa Aquifer, Bolivia

Directory of Open Access Journals (Sweden)

Etzar Gómez

2016-05-01

Full Text Available Aridity and seasonality of precipitation are characteristics of the highland region in Bolivia. Groundwater becomes an important and safe source of water when surficial bodies are intermittent and affected by natural and anthropogenic contamination. Decades of exploitation of the Challapampa aquifer, combined with lack of information required to understand the groundwater circulation, represent a challenge for reservoir management. This study analyzes isotopic compositions of deuterium and oxygen-18 in different stages in the hydrologic cycle to assess flow patterns in the aquifer, especially in the alluvial fan of River Paria, where records are more extensive in space and time. Interpretations are based on existing and new data. Some implications, such as the age of water, the evaporation effect in groundwater and some thermal intrusions are supported by stable isotopes, tritium, radiocarbon, and electrical conductivity records. New results confirm that modern precipitation over the mountains surrounding the study area is the most important origin of water for shallow aquifers until exploited depths, 100 m below surface. The origin of water in deeper depths, 400 m, seems related to infiltration at higher altitudes and longer residence times.

Research Project on CO2 Geological Storage and Groundwater Resources: Water Quality Effects Caused by CO2 Intrusion into Shallow Groundwater

Energy Technology Data Exchange (ETDEWEB)

Birkholzer, Jens; Apps, John; Zheng, Liange; Zhang, Yingqi; Xu, Tianfu; Tsang, Chin-Fu

2008-10-01

One promising approach to reduce greenhouse gas emissions is injecting CO{sub 2} into suitable geologic formations, typically depleted oil/gas reservoirs or saline formations at depth larger than 800 m. Proper site selection and management of CO{sub 2} storage projects will ensure that the risks to human health and the environment are low. However, a risk remains that CO{sub 2} could migrate from a deep storage formation, e.g. via local high-permeability pathways such as permeable faults or degraded wells, and arrive in shallow groundwater resources. The ingress of CO{sub 2} is by itself not typically a concern to the water quality of an underground source of drinking water (USDW), but it will change the geochemical conditions in the aquifer and will cause secondary effects mainly induced by changes in pH, in particular the mobilization of hazardous inorganic constituents present in the aquifer minerals. Identification and assessment of these potential effects is necessary to analyze risks associated with geologic sequestration of CO{sub 2}. This report describes a systematic evaluation of the possible water quality changes in response to CO{sub 2} intrusion into aquifers currently used as sources of potable water in the United States. Our goal was to develop a general understanding of the potential vulnerability of United States potable groundwater resources in the event of CO{sub 2} leakage. This goal was achieved in two main tasks, the first to develop a comprehensive geochemical model representing typical conditions in many freshwater aquifers (Section 3), the second to conduct a systematic reactive-transport modeling study to quantify the effect of CO{sub 2} intrusion into shallow aquifers (Section 4). Via reactive-transport modeling, the amount of hazardous constituents potentially mobilized by the ingress of CO{sub 2} was determined, the fate and migration of these constituents in the groundwater was predicted, and the likelihood that drinking water

Quantity and quality of groundwater discharge in a hypersaline lake environment

Science.gov (United States)

Anderson, R.B.; Naftz, D.L.; Day-Lewis, F. D.; Henderson, R.D.; Rosenberry, D.O.; Stolp, B.J.; Jewell, P.

2014-01-01

indicates that under chemically reducing conditions, arsenic- (As) bearing minerals could dissolve while Se-bearing minerals will likely precipitate out of solution, possibly explaining why the shallow groundwater below and within the mirabilite salt layer contains low concentrations of Se (0.9–2.3 μg/L).

Assessing groundwater storage changes using remote sensing-based evapotranspiration and precipitation at a large semiarid basin scale

NARCIS (Netherlands)

Gokmen, M.; Vekerdy, Z.; Lubczynski, M.; Timmermans, J.; Batelaan, Okke; Verhoef, W.

2013-01-01

A method is presented that uses remote sensing (RS)-based evapotranspiration (ET) and precipitation estimates with improved accuracies under semiarid conditions to quantify a spatially distributed water balance, for analyzing groundwater storage changes due to supplementary water uses. The method is

Anomalous migration of shallow groundwater and gases in the Beijing region and the 1976 Tangshan earthquake

Energy Technology Data Exchange (ETDEWEB)

Shi, H. (Seismological Brigade of Beijing, China); Cai, Z.; Gao, M.

1980-02-01

The character and cause of blowing out of gases and emission of sound from dry wells and of water becoming muddy and changing of level in water wells of the Beijing region immediately before the 1976 Tangshan earthquake and its strong aftershocks are investigated. These phenomena, taken as possible precursors of the earthquakes as well as the motivating force, mechanism, geological background and material sources of the anomalous migration are discussed. Besides, the paper also deals with the relation between these anomalies and the Tangshan earthquake and the significance of the study of groundwater as far as earthquake prediction is concerned. No gaseous gushing from great depth in considerable quantities appeared so that migration should be regarded only as the migration of shallow groundwater and gases. This is referred to the consequence of the action on certain hydrogeological structures of an impulse-like extra tectonic stress field on the active faults in the Beijing region under a unified regional stress field. The present authors suppose that further studies of the anomalous migration of groundwater and gases possibly may be fruitful to earthquake prediction work.

Anomalous migration of shallow groundwater and gases in the Beijing region and the 1976 Tangshan earthquake

Energy Technology Data Exchange (ETDEWEB)

Shi, H.; Cai, Z.; Gao, M.

1980-02-01

The character and cause of blowing out of gases and emission of sound from dry wells and of water becoming muddy and changing of level in water wells of the Beijing region immediately before the 1976 Tangshan earthquake and its strong aftershocks are investigated. These phenomena, taken as possible precursors of the earthquakes as well as the motivating force, mechanism, geological background and material sources of the anomalous migration, are discussed. In addition, the paper also deals with the relation between these anomalies and the Tangshan earthquake and the significance of the study of groundwater as far as earthquake prediction is concerned. No gaseous gushing from great depth in considerable quantities appeared so that migration should be regarded only as the migration of shallow groundwater and gases. This is referred to as the consequence of the action on certain hydrogeological structures of an impulse-like extra tectonic stress field on the active faults in the Beijing region under a unified regional stress field. The present authors suppose that further studies of the anomalous migration of groundwater and gases possibly may be fruitful to earthquake prediction work.

Dynamics of Agricultural Groundwater Extraction

NARCIS (Netherlands)

Hellegers, P.J.G.J.; Zilberman, D.; Ierland, van E.C.

2001-01-01

Agricultural shallow groundwater extraction can result in desiccation of neighbouring nature reserves and degradation of groundwater quality in the Netherlands, whereas both externalities are often not considered when agricultural groundwater extraction patterns are being determined. A model is

Stochastic modeling of wetland-groundwater systems

Science.gov (United States)

Bertassello, Leonardo Enrico; Rao, P. Suresh C.; Park, Jeryang; Jawitz, James W.; Botter, Gianluca

2018-02-01

Modeling and data analyses were used in this study to examine the temporal hydrological variability in geographically isolated wetlands (GIWs), as influenced by hydrologic connectivity to shallow groundwater, wetland bathymetry, and subject to stochastic hydro-climatic forcing. We examined the general case of GIWs coupled to shallow groundwater through exfiltration or infiltration across wetland bottom. We also examined limiting case with the wetland stage as the local expression of the shallow groundwater. We derive analytical expressions for the steady-state probability density functions (pdfs) for wetland water storage and stage using few, scaled, physically-based parameters. In addition, we analyze the hydrologic crossing time properties of wetland stage, and the dependence of the mean hydroperiod on climatic and wetland morphologic attributes. Our analyses show that it is crucial to account for shallow groundwater connectivity to fully understand the hydrologic dynamics in wetlands. The application of the model to two different case studies in Florida, jointly with a detailed sensitivity analysis, allowed us to identify the main drivers of hydrologic dynamics in GIWs under different climate and morphologic conditions.

Hydrochemistry in surface water and shallow groundwater. Site descriptive modelling SDM-Site Forsmark

Energy Technology Data Exchange (ETDEWEB)

Troejbom, Mats (Mopelikan, Norrtaelje (SE)); Soederbaeck, Bjoern (Swedish Nuclear Fuel and Waste Management Co., Stockholm (SE)); Johansson, Per-Olof (Artesia Grundvattenkonsult AB, Taeby (SE))

2007-10-15

mineral has a central role in the forming of today's hydrochemistry in surface systems, and probably also on the composition of the dilute, non-brackish, groundwater in the upper parts of the fractured bedrock. The rich supply of calcium and the high alkalinity affects the structure of the whole ecosystem, for example by forming the oligotrophic hardwater lakes which are characteristic for the area. One major issue in the report is if there can be found any indications on deep groundwater discharge in the surface system. According to observations in surface water and shallow groundwater, and to the hydrological/hydrochemical conceptual model, there is probably no ongoing deep discharge into the freshwater surface system. In restricted areas there are, however, indications that relict marine remnants, which also includes deep saline signatures, prevail in the groundwater at relatively shallow depths in the Quaternary deposits, but not reach the surface due to the downwards directed groundwater flow pattern that generally prevail in the area. This hydrochemical pattern could according to the conceptual model probably be explained by influence from marine remnants formed under a previous hydrological regime and these signatures are preserved because of stagnant conditions in some areas

Hydrochemistry in surface water and shallow groundwater. Site descriptive modelling SDM-Site Forsmark

International Nuclear Information System (INIS)

Troejbom, Mats; Soederbaeck, Bjoern; Johansson, Per-Olof

2007-10-01

mineral has a central role in the forming of today's hydrochemistry in surface systems, and probably also on the composition of the dilute, non-brackish, groundwater in the upper parts of the fractured bedrock. The rich supply of calcium and the high alkalinity affects the structure of the whole ecosystem, for example by forming the oligotrophic hardwater lakes which are characteristic for the area. One major issue in the report is if there can be found any indications on deep groundwater discharge in the surface system. According to observations in surface water and shallow groundwater, and to the hydrological/hydrochemical conceptual model, there is probably no ongoing deep discharge into the freshwater surface system. In restricted areas there are, however, indications that relict marine remnants, which also includes deep saline signatures, prevail in the groundwater at relatively shallow depths in the Quaternary deposits, but not reach the surface due to the downwards directed groundwater flow pattern that generally prevail in the area. This hydrochemical pattern could according to the conceptual model probably be explained by influence from marine remnants formed under a previous hydrological regime and these signatures are preserved because of stagnant conditions in some areas

F/H seepage basin groundwater influent, effluent, precipitated sludge characterization task technical plan

International Nuclear Information System (INIS)

Siler, J.L.

1993-01-01

A treatability study to support the development of a remediation system which would reduce the contaminant levels in groundwater removed from the aquifers in the vicinity of the F/H seepage basins and southwest of the Mixed Waste Management Facility (MWMF) at the Savannah River facility was conducted. Proposed changes in the remediation system require an additional study to determine whether precipitated sludge generated from the proposed remediation system will be hazardous as defined by RCRA. Several contaminants, such as lead and mercury, are above the groundwater protection standards. The presence of radionuclides and other contaminants in the sludge does not present a problem provided that the sludge can pass the Toxicity Characteristic Leaching Procedure (TCLP) test. The study has been developed in such a manner as to cover the possible range of treatment options that may be used

Tritium activity concentrations and residence times of groundwater collected in Rokkasho, Japan

International Nuclear Information System (INIS)

Hasegawa, Hidenao; Ueda, Shinji; Kakiuchi, Hideki; Hisamatsu, Shun'ichi; Akata, Naofumi

2015-01-01

Tritium ( 3 H) concentrations were measured in groundwater samples from four surface wells (4-10 m deep), four shallow wells (24-26.5 m deep) and a 150-m-deep well in the Futamata River catchment area, which is adjacent to the large-scale commercial spent nuclear fuel reprocessing plant in Rokkasho, Japan. The 3 H concentrations in most of the surface- and shallow-well samples (<0.03-0.57 Bq l -1 ) were similar to those in precipitation (annual mean: 0.31-0.79 Bq l -1 ), suggesting that the residence time of the water in those wells was 0-15 y. The 3 H concentrations in the samples from a 26-m-deep well and the 150-m-deep well were lower than those in the other wells, indicating that groundwater with a long residence time exists in deep aquifers and the estuary area of the catchment. It is not clear whether 3 H released during test operation of the plant with actual spent nuclear fuel affected the 3 H concentrations observed in this study. (authors)

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

Adsorptive properties of alluvial soil for arsenic(V) and its potential for protection of the shallow groundwater among Changsha, Zhuzhou, and Xiangtan cities, China.

Science.gov (United States)

Chen, Hongwei; Mei, Jinhua; Luo, Yueping; Qiu, Anni; Wang, Huan

2017-02-01

The study area is among Changsha, Zhuzhou, and Xiangtan cities, which was under agricultural use and natural conditions about 10 years ago and now is becoming part of the metropolis because of the urban expansion. This study aims to investigate the mechanisms and capabilities of the local alluvial soil layer for protecting the local shallow groundwater from arsenic pollution by field surveys and batch experiments. The field surveys showed that there was an acidic tendency of the groundwater, and phosphate, nitrate, and arsenic in the groundwater significantly increased comparing to their reference values. It indicates that the disturbance of the former agricultural land due to the change of land use may be responsible for these changes. From the experimental results, the maximum adsorption capacity of the soil for As(V) was as low as 0.334 mg/g, and lower As(V) adsorption capacities were obtained at higher As(V) concentration, higher pH, and lower temperature. The presence of H 2 PO 4 - and SiO 3 2- posed negative, while HCO 3 - slight positive, and SO 4 2- , NO 3 - and Cl - negligible influences on the As(V) adsorption. The surface-derived organic matter played a negative role in the adsorption process, and low specific surface area influenced adsorption capacity of the soil. The study reveals that the local soil layer shows poor potential for protection of the local shallow groundwater from As(V) pollution, and the change trends of the groundwater environments due to more intensive anthropogenic activities will further weaken this potential and increase the risk of the groundwater contamination.

Groundwater influence on soil moisture memory and land-atmosphere interactions over the Iberian Peninsula

Science.gov (United States)

Martinez-de la Torre, Alberto; Miguez-Macho, Gonzalo

2017-04-01

We investigate the memory introduced in soil moisture fields by groundwater long timescales of variation in the semi-arid regions of the Iberian Peninsula with the LEAFHYDRO soil-vegetation-hydrology model, which includes a dynamic water table fully coupled to soil moisture and river flow via 2-way fluxes. We select a 10-year period (1989-1998) with transitions from wet to dry to again wet long lasting conditions and we carry out simulations at 2.5 km spatial resolution forced by ERA-Interim and a high-resolution precipitation analysis over Spain and Portugal. The model produces a realistic water table that we validate with hundreds of water table depth observation time series (ranging from 4 to 10 years) over the Iberian Peninsula. Modeled river flow is also compared to observations. Over shallow water table regions, results highlight the groundwater buffering effect on soil moisture fields over dry spells and long-term droughts, as well as the slow recovery of pre-drought soil wetness once climatic conditions turn wetter. Groundwater sustains river flow during dry summer periods. The longer lasting wet conditions in the soil when groundwater is considered increase summer evapotranspiration, that is mostly water-limited. Our results suggest that groundwater interaction with soil moisture should be considered for climate seasonal forecasting and climate studies in general over water-limited regions where shallow water tables are significantly present and connected to land surface hydrology.

Global Precipitation Responses to Land Hydrological Processes

Science.gov (United States)

Lo, M.; Famiglietti, J. S.

2012-12-01

Several studies have established that soil moisture increases after adding a groundwater component in land surface models due to the additional supply of subsurface water. However, impacts of groundwater on the spatial-temporal variability of precipitation have received little attention. Through the coupled groundwater-land-atmosphere model (NCAR Community Atmosphere Model + Community Land Model) simulations, this study explores how groundwater representation in the model alters the precipitation spatiotemporal distributions. Results indicate that the effect of groundwater on the amount of precipitation is not globally homogeneous. Lower tropospheric water vapor increases due to the presence of groundwater in the model. The increased water vapor destabilizes the atmosphere and enhances the vertical upward velocity and precipitation in tropical convective regions. Precipitation, therefore, is inhibited in the descending branch of convection. As a result, an asymmetric dipole is produced over tropical land regions along the equator during the summer. This is analogous to the "rich-get-richer" mechanism proposed by previous studies. Moreover, groundwater also increased short-term (seasonal) and long-term (interannual) memory of precipitation for some regions with suitable groundwater table depth and found to be a function of water table depth. Based on the spatial distributions of the one-month-lag autocorrelation coefficients as well as Hurst coefficients, air-land interaction can occur from short (several months) to long (several years) time scales. This study indicates the importance of land hydrological processes in the climate system and the necessity of including the subsurface processes in the global climate models.

Preliminary Study Contamination of Organochlorine Pesticide (Heptachlor) and Heavy Metal (Arsenic) in Shallow Groundwater Aquifer of Semarang Coastal Areas

Science.gov (United States)

Rochaddi, Baskoro; Adhi Suryono, Chrisna; Atmodjo, Warsito; Satriadi, Alfi

2018-02-01

The present study was conducted to assess the level of pesticide and heavy metal contamination in shallow aquifer of Semarang coastal areas. Results indicated that Heptachlor and Arsenic were detected in the water samples in the range 0.023-0.055 μg L-1 and 0,03-1,63 μg L-1, respectively. Compared to the standard limits of the organochlorine contents in the water sample by World Health Organization (WHO) limits and Indonesian Drinking and Domestic Water Quality Standard for Ground Water (IWQS), groundwater of Semarang Coastal Areas was contaminated with pesticide and heavy metal. This study has proven the presence of organochlorine and heavy metal contamination of some shallow aquifer supplies in the coastal areas of Semarang.

Characterization of mechanisms and processes of groundwater salinization in irrigated coastal area using statistics, GIS, and hydrogeochemical investigations.

Science.gov (United States)

Bouzourra, Hazar; Bouhlila, Rachida; Elango, L; Slama, Fairouz; Ouslati, Naceur

2015-02-01

Coastal aquifers are at threat of salinization in most parts of the world. This study was carried out in coastal shallow aquifers of Aousja-Ghar El Melh and Kalâat el Andalous, northeastern of Tunisia with an objective to identify sources and processes of groundwater salinization. Groundwater samples were collected from 42 shallow dug wells during July and September 2007. Chemical parameters such as Na(+), Ca(2+), Mg(2+), K(+), Cl(-), SO4 (2-), HCO3 (-), NO3 (-), Br(-), and F(-) were analyzed. The combination of hydrogeochemical, statistical, and GIS approaches was used to understand and to identify the main sources of salinization and contamination of these shallow coastal aquifers as follows: (i) water-rock interaction, (ii) evapotranspiration, (iii) saltwater is started to intrude before 1972 and it is still intruding continuously, (iv) irrigation return flow, (v) sea aerosol spray, and finally, (vi) agricultural fertilizers. During 2005/2006, the overexploitation of the renewable water resources of aquifers caused saline water intrusion. In 2007, the freshening of a brackish-saline groundwater occurred under natural recharge conditions by Ca-HCO3 meteoric freshwater. The cationic exchange processes are occurred at fresh-saline interfaces of mixtures along the hydraulic gradient. The sulfate reduction process and the neo-formation of clays minerals characterize the hypersaline coastal Sebkha environments. Evaporation tends to increase the concentrations of solutes in groundwater from the recharge areas to the discharge areas and leads to precipitate carbonate and sulfate minerals.

Rapid breakthrough of pesticides via biopres into tile drains and shallow groundwater: a combined experimental and model study

Science.gov (United States)

Klaus, J.; Zehe, E.; Palm, J.; Schroeder, B.

2009-04-01

Preferential flow in macropores is a key process which strongly affects infiltration and may cause rapid transport of pesticides into depths of 80 to 150 cm. At these depths they experience a much slower degradation, may leach into shallow groundwater or enter a tile-drain and are transported in surface water bodies. Therefore, preferential transport is an environ¬mental problem because the topsoil is bypassed, which has been originally thought to act as a filter to protect the subsoil and shallow groundwater. To get a better insight in the process of pesticide transport in agricultural soils an irrigation experiment was performed on a 400 m² field site. The experimental plot is located in the Weiherbach valley, south-west Germany, which basic geology consists of Loess and Keuper layers, the soil at the test site is a gleyic Colluvisol. The distance of the irrigation site to the Weiherbach brook is aprox. 12 m, the field is drained with a tile-drain in about 1.2 m depth and the shows runoff over the entire year. Three hours before the irrigation started the farmer applied a pesticide solution consisting of Isoproturon and Flufenacet according to conventional agricultural practice. The irrigation took place in three time blocks (80 min, 60 min, 80 min) and had a total irrigation rate of 33.6 mm measured with ten precipitation samplers. During the first block a tracer solution of 1600 g Bromide and 2000 g Brilliant Blue was irrigated on the test site. The drainage outlet was instrumented with a pressure probe to measure the water level. About 50 water samples were taken on the day of the experiment from the drainage outlet by hand, and in an eight hour interval for six days with an automatic sample procedure. Discharge at the drainage outlet showed two peaks in response irrigation. The breakthrough of the tracer into the brook is much faster then the reaction of the discharge on the precipitation impulse. To gain insight in the vertical transport behaviour three

The Virginia Beach shallow ground-water study

Science.gov (United States)

Johnson, Henry M.

1999-01-01

IntroductionVirginia Beach is a rapidly growing city of more than 425,000 people. Sources of fresh water within the city, however, are limited. Prior to 1998, the Virginia Beach Public Utilities Department met the city's water needs by purchasing treated drinking water from the City of Norfolk. Because Norfolk had to meet its own requirements, the amount of water available to Virginia Beach was limited to about 30 million gallons per day (mgd) and even less during droughts. This water supply was supplemented with ground water from city-owned, community, and private wells. In many parts of the city, however, ground water cannot be used because of high concentrations of chloride, iron, and (or) sulfur, which give the water an unpleasant taste.In early 1998, a pipeline came on-line that can carry up to 45 mgd of water from Lake Gaston to Virginia Beach. The Gaston pipeline has alleviated concerns about water supply and quality for most residents living north of the "Green Line." These residents primarily use ground water only for small-scale domestic activities such as watering lawns, filling ponds and pools, and washing cars. City water and sewer services have been extended beyond the Green Line into the "Transition Area." Residents and businesses south of the Transition Area, however, continue to rely on ground water to meet most of their needs for potable and non-potable water. To help assure a continued, reliable supply of ground water, the U.S. Geological Survey (USGS), in cooperation with the City of Virginia Beach Public Utilities Department, has begun an assessment of the shallow ground-water resources underlying the City of Virginia Beach.

Hydrochemistry in surface water and shallow groundwater. Site descriptive modelling SDM-Site Laxemar

Energy Technology Data Exchange (ETDEWEB)

Troejbom, Mats (Mopelikan, Norrtaelje (Sweden)); Soederbaeck, Bjoern; Kalinowski, Birgitta (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden))

2008-10-15

elevated areas, meteoric recharge has a great influence on the observed hydrochemistry, which is usually characterised by dilute fresh waters of low ionic strength. In lower areas close to the coast, there are indications of ongoing flushing of marine relicts since the area was covered by sea water. At most locations in the Laxemar-Simpevarp area, this flushing is more or less completed and concentrations of marine ions may be explained by deposition and anthropogenic sources. As much as 2/3 of the Cl input to the surface system has been estimated to originate from anthropogenic sources as road salt. One important question in the hydrochemical evaluation is whether there are any indications of deep groundwater discharge in the surface system. It can be concluded from observations in shallow groundwater that deep groundwater signatures are present in the Quaternary deposits in potential deep discharge areas beneath lakes and brackish bays. On land, no deep signatures have been detected neither in surface water nor in groundwater, which indicates that shallow meteoric recharge/discharge patterns dominate and that potential regional deep discharge is too dilute to be detected in surface water

Hydrochemistry in surface water and shallow groundwater. Site descriptive modelling SDM-Site Laxemar

International Nuclear Information System (INIS)

Troejbom, Mats; Soederbaeck, Bjoern; Kalinowski, Birgitta

2008-10-01

elevated areas, meteoric recharge has a great influence on the observed hydrochemistry, which is usually characterised by dilute fresh waters of low ionic strength. In lower areas close to the coast, there are indications of ongoing flushing of marine relicts since the area was covered by sea water. At most locations in the Laxemar-Simpevarp area, this flushing is more or less completed and concentrations of marine ions may be explained by deposition and anthropogenic sources. As much as 2/3 of the Cl input to the surface system has been estimated to originate from anthropogenic sources as road salt. One important question in the hydrochemical evaluation is whether there are any indications of deep groundwater discharge in the surface system. It can be concluded from observations in shallow groundwater that deep groundwater signatures are present in the Quaternary deposits in potential deep discharge areas beneath lakes and brackish bays. On land, no deep signatures have been detected neither in surface water nor in groundwater, which indicates that shallow meteoric recharge/discharge patterns dominate and that potential regional deep discharge is too dilute to be detected in surface water

Arsenic in groundwater of the Paraiba do Sul delta, Brazil: An atmospheric source?

Science.gov (United States)

Mirlean, N; Baisch, P; Diniz, D

2014-06-01

High concentrations of arsenic (>50μg L(-1)) have been detected for the first time in groundwater of the wave-dominated Paraiba do Sul delta, Brazil. The deltaic shallow groundwater aquifer is enriched in arsenic fixed by authigenic sulfides. A study of palynomorphs confirmed that aquifer sediments were formed in inter-dune lakes/swamps lately covered by eolian sands. The organic sediments of contemporaneous inter-dune lake/swamp contain very high concentration of As: up to 180mg kg(-1) and 163μg L(-1) in dry gyttja material and interstitial water, respectively. The As in recent lake/swamp sediments is retained by iron hydroxides in upper and probably by sulfides in lower layers. In the absence of connection of inter-dune lakes/swamps with fluvial currents, the atmospheric input of As could be considered as the principal source in sediments. The calculation demonstrates the possibility of high concentrations of As accumulation in sediments of inter-dune lakes/swamps from atmospheric precipitations within several centuries before they will be covered by eolian sands and turned into shallow aquifer. Considering the commonalities of wave-dominated delta formations, we can predict more prevalent As accumulation in delta plain groundwater. Copyright © 2014 Elsevier B.V. All rights reserved.

Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach

Science.gov (United States)

Hassan, S.M. Tanvir; Lubczynski, Maciek W.; Niswonger, Richard G.; Zhongbo, Su

2014-01-01

The structural and hydrological complexity of hard rock systems (HRSs) affects dynamics of surface–groundwater interactions. These complexities are not well described or understood by hydrogeologists because simplified analyses typically are used to study HRSs. A transient, integrated hydrologic model (IHM) GSFLOW (Groundwater and Surface water FLOW) was calibrated and post-audited using 18 years of daily groundwater head and stream discharge data to evaluate the surface–groundwater interactions in semi-arid, ∼80 km2 granitic Sardon hilly catchment in Spain characterized by shallow water table conditions, relatively low storage, dense drainage networks and frequent, high intensity rainfall. The following hydrological observations for the Sardon Catchment, and more generally for HRSs were made: (i) significant bi-directional vertical flows occur between surface water and groundwater throughout the HRSs; (ii) relatively large groundwater recharge represents 16% of precipitation (P, 562 mm.y−1) and large groundwater exfiltration (∼11% of P) results in short groundwater flow paths due to a dense network of streams, low permeability and hilly topographic relief; deep, long groundwater flow paths constitute a smaller component of the water budget (∼1% of P); quite high groundwater evapotranspiration (∼5% of P and ∼7% of total evapotranspiration); low permeability and shallow soils are the main reasons for relatively large components of Hortonian flow and interflow (15% and 11% of P, respectively); (iii) the majority of drainage from the catchment leaves as surface water; (iv) declining 18 years trend (4.44 mm.y−1) of groundwater storage; and (v) large spatio-temporal variability of water fluxes. This IHM study of HRSs provides greater understanding of these relatively unknown hydrologic systems that are widespread throughout the world and are important for water resources in many regions.

Locating Shallow Groundwater Discharge to Streams Near Concentrated Animal Feeding Operations Using Aerial Infrared Thermography: A Novel Potential Pollution Detection Method

Science.gov (United States)

Mapes, K. L.; Pricope, N. G.

2017-12-01

The Cape Fear River Basin (CFRB) has some of the highest densities of concentrated animal feeding operations (CAFO) in the United States (factoryfarmmap.org) and was recently named one of the country's most endangered rivers (americanrivers.org). There is high potential for CAFO land use to degrade stream water quality by introducing pollutants, primarily nitrates and fecal coliform, into sub-surface and surface waters. The regionally high water table in the Lower CFRB increases the risk of water quality degradation due to increased connectivity of ground- and surface water. The Lower CFRB is periodically subjected to frequent or intense hurricanes, which have been shown to exacerbate water quality issues associated with CAFOs. Additionally, the growing population in this region is placing more pressure on an already taxed water source and will continue to rely on the Cape Fear River for drinking water and wastewater discharge. While there are documented occurrences of groundwater contamination from CAFOs, we still have little understanding on how and where pollution may be entering streams by shallow sub-surface discharge. Shallow groundwater discharge to streams is becoming easier to detect using thermal infrared imaging cameras onboard unmanned aerial systems. The temperature differences between groundwater and stream water are easily distinguished in the resulting images. While this technology cannot directly measure water quality, it can locate areas of shallow groundwater discharge that can later be tested for pollutants using conventional methods. We will utilize a thermal infrared camera onboard a SenseFly eBee Plus to determine the feasibility of using this technology on a larger scale within the Lower CFRB as an inexpensive means of identifying sites of potential pollution input. Aerial surveys will be conducted in two sub-watersheds: one containing swine CAFO and a control that lacks swine CAFO. Information from this study can be integrated into

Spatial and temporal variations of evapotranspiration, groundwater and precipitation in Amazonia

Science.gov (United States)

Niu, J.; Riley, W. J.; Shen, C.; Melack, J. M.; Qiu, H.

2017-12-01

We used wavelet coherence analysis to investigate the effects of precipitation (P) and groundwater dynamics (total water storage anomaly, TWSA) on evapotranspiration (ET) at kilometer, sub-basin, and whole basin scales in the Amazon basin. The Amazon-scale averaged ET, P, and TWSA have about the same annual periodicity. The phase lag between ET and P (ΦET-P) is 1 to 3 months, and between ET and TWSA (ΦET-TWSA) is 3 to 7 months. The phase patterns have a south-north divide due to significant variation in climatic conditions. The correlation between ΦET-P and ΦET-TWSA is affected by the aridity index (the ratio between potential ET (PET) and P, PET / P), of each sub-basin, as determined using the Budyko framework at the sub-basin level. The spatial structure of ΦET-P is negatively correlated with the spatial structure of annual ET. At Amazon-scale during a drought year (e.g., 2010), both phases decreased, while in the subsequent years, ΦET-TWSA increased, indicating strong groundwater effects on ET immediately following dry years Amazon-wide.

Evaluation of groundwater levels in the South Platte River alluvial aquifer, Colorado, 1953-2012, and design of initial well networks for monitoring groundwater levels

Science.gov (United States)

Wellman, Tristan

2015-01-01

The South Platte River and underlying alluvial aquifer form an important hydrologic resource in northeastern Colorado that provides water to population centers along the Front Range and to agricultural communities across the rural plains. Water is regulated based on seniority of water rights and delivered using a network of administration structures that includes ditches, reservoirs, wells, impacted river sections, and engineered recharge areas. A recent addendum to Colorado water law enacted during 2002-2003 curtailed pumping from thousands of wells that lacked authorized augmentation plans. The restrictions in pumping were hypothesized to increase water storage in the aquifer, causing groundwater to rise near the land surface at some locations. The U.S. Geological Survey (USGS), in cooperation with the Colorado Water Conservation Board and the Colorado Water Institute, completed an assessment of 60 years (yr) of historical groundwater-level records collected from 1953 to 2012 from 1,669 wells. Relations of "high" groundwater levels, defined as depth to water from 0 to 10 feet (ft) below land surface, were compared to precipitation, river discharge, and 36 geographic and administrative attributes to identify natural and human controls in areas with shallow groundwater.

Data of groundwater from boreholes, river water and precipitation for the Horonobe Underground Research Laboratory project. 2011-2010

Energy Technology Data Exchange (ETDEWEB)

Amano, Yuki; Yamamoto, Yoichi; Nanjyo, Isao; Murakami, Hiroaki; Yokota, Hideharu; Yamazaki, Masanori; Iwatsuki, Teruki [Japan Atomic Energy Agency, Geological Isolation Research and Development Directorate, Horonobe, Hokkaido (Japan); Kunimaru, Takanori [Japan Atomic Energy Agency, Geological Isolation Research and Development Directorate, Mizunami, Gifu (Japan); Oyama, Takahiro [Central Research Inst. of Electric Power Industry, Tokyo (Japan)

2012-02-15

In the Horonobe Underground Research Laboratory (URL) Project, groundwater from boreholes, river water and precipitation have been analyzed for the environmental monitoring since the fiscal year 2001. This report shows the data set of water chemistry since the fiscal year 2001 to the fiscal year 2010. (author)

Data of groundwater from boreholes, river water and precipitation for the Horonobe Underground Research Laboratory project. 2011-2010

International Nuclear Information System (INIS)

Amano, Yuki; Yamamoto, Yoichi; Nanjyo, Isao; Murakami, Hiroaki; Yokota, Hideharu; Yamazaki, Masanori; Iwatsuki, Teruki; Kunimaru, Takanori; Oyama, Takahiro

2012-02-01

In the Horonobe Underground Research Laboratory (URL) Project, groundwater from boreholes, river water and precipitation have been analyzed for the environmental monitoring since the fiscal year 2001. This report shows the data set of water chemistry since the fiscal year 2001 to the fiscal year 2010. (author)

Estimating evapotranspiration and groundwater flow from water-table fluctuations for a general wetland scenario

Science.gov (United States)

Weber, Lisa C.; Wiley, Michael J.; Wilcox, Douglas A.

2016-01-01

The use of diurnal water-table fluctuation methods to calculate evapotranspiration (ET) and groundwater flow is of increasing interest in ecohydrological studies. Most studies of this type, however, have been located in riparian wetlands of semi-arid regions where groundwater levels are consistently below topographic surface elevations and precipitation events are infrequent. Current methodologies preclude application to a wider variety of wetland systems. In this study, we extended a method for estimating sub-daily ET and groundwater flow rates from water-level fluctuations to fit highly dynamic, non-riparian wetland scenarios. Modifications included (1) varying the specific yield to account for periodic flooded conditions and (2) relating empirically derived ET to estimated potential ET for days when precipitation events masked the diurnal signal. To demonstrate the utility of this method, we estimated ET and groundwater fluxes over two growing seasons (2006–2007) in 15 wetlands within a ridge-and-swale wetland complex of the Laurentian Great Lakes under flooded and non-flooded conditions. Mean daily ET rates for the sites ranged from 4.0 mm d−1 to 6.6 mm d−1. Shallow groundwater discharge rates resulting from evaporative demand ranged from 2.5 mm d−1 to 4.3 mm d−1. This study helps to expand our understanding of the evapotranspirative demand of plants under various hydrologic and climate conditions. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

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

Precipitation and temperature drive seasonal variation in bioaccumulation of polycyclic aromatic hydrocarbons in the planktonic food webs of a subtropical shallow eutrophic lake in China.

Science.gov (United States)

Tao, Yuqiang; Yu, Jing; Xue, Bin; Yao, Shuchun; Wang, Sumin

2017-04-01

Hydrophobic organic contaminants (HOCs) are toxic and ubiquitous in aquatic environments and pose great risks to aquatic organisms. Bioaccumulation by plankton is the first step for HOCs to enter aquatic food webs. Trophic status is considered to dominate variations in bioaccumulation of HOCs in plankton in temperate and frigid deep oligotrophic waters. However, long-term driving factors for bioaccumulation of HOCs in planktonic food webs of subtropical shallow eutrophic waters have not been well investigated. China has the largest subtropical lake density in the Northern Hemisphere. Due to limited field data, long-term variations in the bioaccumulation of HOCs in these lakes are almost unknown. Here we take Lake Xuanwu as an example to investigate long-term variations in the bioaccumulation, and biomagnification of polycyclic aromatic hydrocarbon (PAHs) in planktonic food webs of subtropical shallow eutrophic lakes in China, and elucidate the driving factors. Our results indicate that temperature rather than nutrients dominates long-term dynamics of planktonic biomass in this lake. Precipitation significantly enhances the concentrations of the PAHs, and total suspended particles, and consequently affects the distribution of the PAHs in the water column. Biomass dilution induced by temperature dominates bioaccumulation of the PAHs by both phytoplankton and zooplankton (copepods and cladocerans). Biomagnification of the PAHs from phytoplankton to zooplankton is positively correlated with temperature. Our study suggests that temperature and precipitation drive long-term variations in the bioaccumulation of the PAHs in the planktonic food webs of this subtropical shallow eutrophic lake. Lake Xuanwu has a similar mean annual temperature, annual precipitation, sunshine duration, and nutrient levels as other subtropical shallow eutrophic lakes in China. This study may also help to understand the bioaccumulation of HOCs in planktonic food webs of other subtropical shallow

Verification of a 1-dimensional model for predicting shallow infiltration at Yucca Mountain

International Nuclear Information System (INIS)

Hevesi, J.A.; Flint, A.L.; Flint, L.E.

1994-01-01

A characterization of net infiltration rates is needed for site-scale evaluation of groundwater flow at Yucca Mountain, Nevada. Shallow infiltration caused by precipitation may be a potential source of net infiltration. A 1-dimensional finite difference model of shallow infiltration with a moisture-dependant evapotranspiration function and a hypothetical root-zone was calibrated and verified using measured water content profiles, measured precipitation, and estimated potential evapotranspiration. Monthly water content profiles obtained from January 1990 through October 1993 were measured by geophysical logging of 3 boreholes located in the alluvium channel of Pagany Wash on Yucca Mountain. The profiles indicated seasonal wetting and drying of the alluvium in response to winter season precipitation and summer season evapotranspiration above a depth of 2.5 meters. A gradual drying trend below a depth of 2.5 meters was interpreted as long-term redistribution and/or evapotranspiration following a deep infiltration event caused by runoff in Pagany Wash during 1984. An initial model, calibrated using the 1990 to 1 992 record, did not provide a satisfactory prediction of water content profiles measured in 1993 following a relatively wet winter season. A re-calibrated model using a modified, seasonally-dependent evapotranspiration function provided an improved fit to the total record. The new model provided a satisfactory verification using water content changes measured at a distance of 6 meters from the calibration site, but was less satisfactory in predicting changes at a distance of 18 meters

Verification of a 1-dimensional model for predicting shallow infiltration at Yucca Mountain

International Nuclear Information System (INIS)

Hevesi, J.; Flint, A.L.; Flint, L.E.

1994-01-01

A characterization of net infiltration rates is needed for site-scale evaluation of groundwater flow at Yucca Mountain, Nevada. Shallow infiltration caused by precipitation may be a potential source of net infiltration. A 1-dimensional finite difference model of shallow infiltration with a moisture-dependent evapotranspiration function and a hypothetical root-zone was calibrated and verified using measured water content profiles, measured precipitation, and estimated potential evapotranspiration. Monthly water content profiles obtained from January 1990 through October 1993 were measured by geophysical logging of 3 boreholes located in the alluvium channel of Pagany Wash on Yucca Mountain. The profiles indicated seasonal wetting and drying of the alluvium in response to winter season precipitation and summer season evapotranspiration above a depth of 2.5 meters. A gradual drying trend below a depth of 2.5 meters was interpreted as long-term redistribution and/or evapotranspiration following a deep infiltration event caused by runoff in Pagany Wash during 1984. An initial model, calibrated using the 1990 to 1992 record, did not provide a satisfactory prediction of water content profiles measured in 1993 following a relatively wet winter season. A re-calibrated model using a modified, seasonally-dependent evapotranspiration function provided an improved fit to the total record. The new model provided a satisfactory verification using water content changes measured at a distance of 6 meters from the calibration site, but was less satisfactory in predicting changes at a distance of 18 meters

Delineating sources of groundwater recharge in an arsenic-affected Holocene aquifer in Cambodia using stable isotope-based mixing models

Science.gov (United States)

Richards, Laura A.; Magnone, Daniel; Boyce, Adrian J.; Casanueva-Marenco, Maria J.; van Dongen, Bart E.; Ballentine, Christopher J.; Polya, David A.

2018-02-01

Chronic exposure to arsenic (As) through the consumption of contaminated groundwaters is a major threat to public health in South and Southeast Asia. The source of As-affected groundwaters is important to the fundamental understanding of the controls on As mobilization and subsequent transport throughout shallow aquifers. Using the stable isotopes of hydrogen and oxygen, the source of groundwater and the interactions between various water bodies were investigated in Cambodia's Kandal Province, an area which is heavily affected by As and typical of many circum-Himalayan shallow aquifers. Two-point mixing models based on δD and δ18O allowed the relative extent of evaporation of groundwater sources to be estimated and allowed various water bodies to be broadly distinguished within the aquifer system. Model limitations are discussed, including the spatial and temporal variation in end member compositions. The conservative tracer Cl/Br is used to further discriminate between groundwater bodies. The stable isotopic signatures of groundwaters containing high As and/or high dissolved organic carbon plot both near the local meteoric water line and near more evaporative lines. The varying degrees of evaporation of high As groundwater sources are indicative of differing recharge contributions (and thus indirectly inferred associated organic matter contributions). The presence of high As groundwaters with recharge derived from both local precipitation and relatively evaporated surface water sources, such as ponds or flooded wetlands, are consistent with (but do not provide direct evidence for) models of a potential dual role of surface-derived and sedimentary organic matter in As mobilization.

Understanding shallow groundwater contamination in Bwaise slum, Kampala, Uganda

Science.gov (United States)

Nyenje, P. M.; Havik, J.; Foppen, J. W.; Uhlenbrook, S.

2012-04-01

Groundwater in unsewered urban areas is heavily contaminated by onsite sanitation activities and is believed to be an important source of nutrients ex-filtrating into streams and thus contributing to eutrophication of Lakes in urban areas. Currently the fate of nutrients and especially phosphorus leached into groundwater in such areas is not well known. In this study, we undertook an extensive investigation of groundwater in Bwaise slum, Kampala Uganda to understand the distribution and fate of sanitation-related nutrients N and P that are leached into groundwater. Transects of monitoring wells were installed in Bwaise slum and downstream of the slum. From these wells, water levels were measured and water quality analyses done to understand the distribution and composition of the nutrients, how they evolve downstream and the possible subsurface processes affecting their fate during transport. These findings are necessary to evaluate the risk of eutrophication posed by unsewered areas in urban cities and to design/implement sanitation systems that will effectively reduce the enrichment of these nutrients in groundwater. Key words: fate, groundwater, nutrients, processes, slums

Relationships between precipitation and surface water chemistry in three Carolina bays

International Nuclear Information System (INIS)

Monegue, R.L.; Jagoe, C.H.

1995-01-01

Carolina Bays are shallow freshwater wetlands, the only naturally occurring lentic systems on the southeastern coastal plain. Bays are breeding sites for many amphibian species, but data on precipitation/surface water relationships and long-term chemical trends are lacking. Such data are essential to interpret major fluctuations in amphibian populations. Surface water and bulk precipitation were sampled bi-weekly for over two years at three bays along a 25 km transect on the Savannah River Site in South Carolina. Precipitation chemistry was similar at all sites; average pH was 4.56, and the major ions were H + (30.8 % of total), and SO 4 (50.3% of total). H + was positively correlated with SO 4 , suggesting the importance of anthropogenic acids to precipitation chemistry. All three bays, Rainbow Bay (RB), Thunder Bay (TB), and Ellenton Bay (EB), contained soft (specific conductivity 5--90 microS/cm), acidic water (pH 4.0--5.9) with DOM from 4--40 mg/L. The major cation for RB, TB, and EB, respectively, was: Mg (30.8 % of total); Na (27% of total); and Ca (34.2% of total). DOM was the major anion for all bays, and SO 4 represented 13 to 28 % of total anions. H + was not correlated to DOM or SO, in RB; H + was positively correlated to DOM and SO 4 in TB, and negatively correlated to DOM and SO 4 in EB. Different biogeochemical processes probably control pH and other chemical variables in each bay. While surface water H + was not directly correlated with precipitation H + , NO 3 , or SO 4 , precipitation and shallow groundwater are dominant water sources for these bays. Atmospheric inputs of anthropogenic acids and other chemicals are important factors influencing bay chemistry

Redox zonation for different groundwater flow paths during bank filtration: a case study at Liao River, Shenyang, northeastern China

Science.gov (United States)

Su, Xiaosi; Lu, Shuai; Yuan, Wenzhen; Woo, Nam Chil; Dai, Zhenxue; Dong, Weihong; Du, Shanghai; Zhang, Xinyue

2018-03-01

The spatial and temporal distribution of redox zones in an aquifer is important when designing groundwater supply systems. Redox zonation can have direct or indirect control of the biological and chemical reactions and mobility of pollutants. In this study, redox conditions are characterized by interpreting the hydrogeological conditions and water chemistry in groundwater during bank infiltration at a site in Shenyang, northeast China. The relevant redox processes and zonal differences in a shallow flow path and deeper flow path at the field scale were revealed by monitoring the redox parameters and chemistry of groundwater near the Liao River. The results show obvious horizontal and vertical components of redox zones during bank filtration. Variations in the horizontal extent of the redox zone were controlled by the different permeabilities of the riverbed sediments and aquifer with depth. Horizontally, the redox zone was situated within 17 m of the riverbank for the shallow flow path and within 200 m for the deep flow path. The vertical extent of the redox zone was affected by precipitation and seasonal river floods and extended to 10 m below the surface. During bank filtration, iron and manganese oxides or hydroxides were reductively dissolved, and arsenic that was adsorbed onto the medium surface or coprecipitated is released into the groundwater. This leads to increased arsenic content in groundwater, which poses a serious threat to water supply security.

Ecosystem-groundwater interactions under changing land uses: Linking water, salts, and carbon across central Argentina

Science.gov (United States)

Jobbagy, E. G.; Nosetto, M. D.; Santoni, C. S.; Jackson, R. B.

2007-05-01

Although most ecosystems display a one-way connection with groundwater based on the regulation of deep water drainage (recharge), this link can become reciprocal when the saturated zone is shallow and plants take up groundwater (discharge). In what context is the reciprocal link most likely? How is it affected by land use changes? Has it consequences on salt and carbon cycling? We examine these questions across a precipitation gradient in the Pampas and Espinal of Argentina focusing on three vegetation change situations (mean annual rainfall): afforestation of humid (900-1300 mm) and subhumid grassland (700-900 mm/yr of rainfall), annual cultivation of subhumid grasslands (700-800 mm/yr), and annual cultivation of semiarid forests (500-700 mm). Humid and subhumid grasslands have shallow (measurements. Groundwater contributions enhance carbon uptake in plantations compared to grasslands as suggested by aboveground biomass measurements and satellite vegetation indexes from sites with and without access to groundwater. Where rainfall is 15 m deep) and recharge under natural conditions is null. The establishment of crops, however, triggers the onset of recharge, as evidenced by vadose zones getting wetter and leached of atmospheric chloride. Cropping may cause water table raises leading to a two-way coupling of ecosystems and groundwater in the future, as it has been documented for similar settings in Australia and the Sahel. In the Pampas land use change interacts with groundwater consumption leading to higher carbon uptake (humid and subhumid grasslands) and salt accumulation (subhumid grasslands). In the Espinal (semiarid forest) land use change currently involves a one-way effect on groundwater recharge that may switch to a reciprocal connection if regional water table raises occur. Neglecting the role of groundwater in flat sedimentary plains can obscure our understanding of carbon and salt cycling and curtail our attempts to sustain soil and water resources under

An Improved GRACE Terrestrial Water Storage Assimilation System For Estimating Large-Scale Soil Moisture and Shallow Groundwater

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Girotto, M.; De Lannoy, G. J. M.; Reichle, R. H.; Rodell, M.

2015-12-01

The Gravity Recovery And Climate Experiment (GRACE) mission is unique because it provides highly accurate column integrated estimates of terrestrial water storage (TWS) variations. Major limitations of GRACE-based TWS observations are related to their monthly temporal and coarse spatial resolution (around 330 km at the equator), and to the vertical integration of the water storage components. These challenges can be addressed through data assimilation. To date, it is still not obvious how best to assimilate GRACE-TWS observations into a land surface model, in order to improve hydrological variables, and many details have yet to be worked out. This presentation discusses specific recent features of the assimilation of gridded GRACE-TWS data into the NASA Goddard Earth Observing System (GEOS-5) Catchment land surface model to improve soil moisture and shallow groundwater estimates at the continental scale. The major recent advancements introduced by the presented work with respect to earlier systems include: 1) the assimilation of gridded GRACE-TWS data product with scaling factors that are specifically derived for data assimilation purposes only; 2) the assimilation is performed through a 3D assimilation scheme, in which reasonable spatial and temporal error standard deviations and correlations are exploited; 3) the analysis step uses an optimized calculation and application of the analysis increments; 4) a poor-man's adaptive estimation of a spatially variable measurement error. This work shows that even if they are characterized by a coarse spatial and temporal resolution, the observed column integrated GRACE-TWS data have potential for improving our understanding of soil moisture and shallow groundwater variations.

The application of surface electrical and shallow geothermic methods in monitoring network design.

Science.gov (United States)

Gilkeson, R.H.; Cartwright, K.

1983-01-01

There are a variety of surface geophysical methods that are routinely used in geologic investigations. The three broad applications of these methods to evaluate the impact of waste disposal on shallow groundwater flow systems are: 1) evaluation of proposed waste disposal sites; 2) monitoring of site performance; and 3) investigation of contaminant migration at existing sites. Electrical and shallow geothermic are two surface geophysical methods that have application to waste disposal investigations. Of the electrical methods, electrical resistivity has the greatest application with a variety of techniques available. The distribution of temperature in shallow geologic materials (shallow geothermics) may define characteristics of shallow groundwater flow systems including zones of recharge and discharge and lithologic variation in the shallow geologic materials.-from Authors

Tritium activity concentrations and residence times of groundwater collected in Rokkasho, Japan.

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Hasegawa, Hidenao; Ueda, Shinji; Akata, Naofumi; Kakiuchi, Hideki; Hisamatsu, Shun'ichi

2015-11-01

Tritium ((3)H) concentrations were measured in groundwater samples from four surface wells (4-10 m deep), four shallow wells (24-26.5 m deep) and a 150-m-deep well in the Futamata River catchment area, which is adjacent to the large-scale commercial spent nuclear fuel reprocessing plant in Rokkasho, Japan. The (3)H concentrations in most of the surface- and shallow-well samples (<0.03-0.57 Bq l(-1)) were similar to those in precipitation (annual mean: 0.31-0.79 Bq l(-1)), suggesting that the residence time of the water in those wells was 0-15 y. The (3)H concentrations in the samples from a 26-m-deep well and the 150-m-deep well were lower than those in the other wells, indicating that groundwater with a long residence time exists in deep aquifers and the estuary area of the catchment. It is not clear whether (3)H released during test operation of the plant with actual spent nuclear fuel affected the (3)H concentrations observed in this study. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Selection of geohydrologic boundaries for ground-water flow models, Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Downey, J.S.; Gutentag, E.D.; Kolm, K.E.

1990-01-01

The conceptual ground-water model of the southern Nevada/Death Valley, California region presented in this paper includes two aquifer systems: a shallow, intermontane, mostly unconfined aquifer composed of unconsolidated or poorly consolidated sediments and consolidated, layered volcanics, and a deep, regional multiple-layered, confined aquifer system composed of faulted and fractured carbonate and volcanic rocks. The potentiometric surfaces of both aquifer systems indicate that ground water leaks vertically from the deeper to the shallower geologic units, and that water in the shallower aquifer may not flow beyond the intermontane subbasin, whereas water in the deeper aquifer may indicate transbasinal flow to the playas in Death Valley. Most of the hydrologic boundaries of the regional aquifer systems in the Yucca Mountain region are geologically complex. Most of the existing numerical models simulating the ground-water flow system in the Yucca Mountain region are based on limited potentiometric-head data elevation and precipitation estimates, and simplified geology. These models are two-dimensional, and are not adequate. The alternative approach to estimating unknown boundary conditions for the regional ground-water flow system involves the following steps: (1) Incorporate known boundary-conditions data from the playas in Death Valley and the Ash Meadows spring line; (2) use estimated boundary data based on geological, pedological, geomorphological, botanical, and hydrological observations; (3) test these initial boundary conditions with three-dimensional models, both steady-state and transient; (4) back-calculate the boundary conditions for the northern, northwestern, northeastern and eastern flux boundaries; (5) compare these calculated values with known data during model calibration steps; and (6) adjust the model. 9 refs., 6 figs

Groundwater geochemical studies at the Altnabreac research site

International Nuclear Information System (INIS)

Kay, R.L.F.; Bath, A.H.

1982-12-01

Results of chemical and isotopic analyses of Altnabreac groundwaters are presented. They are used to define the origin and maturation scheme of groundwaters to depths approaching 300 m in crystalline rocks (granites and metasediments). Samples are derived from packer-isolated zones in 3 deep (approx. 300 m) boreholes, temporal monitoring of 17 shallow boreholes (less than 41 m deep) and about 60 springs and other surface waters as well as from 1981-82 aggregated monthly rainfall. Stable oxygen and hydrogen isotope ratios show all waters to be wholly meteoric in origin and the precipitation input to be well mixed. 3 H (tritium) contents suggest that recharge occurs on discrete upland areas where there tends to be downward movement with essentially horizontal flow, resulting in slight discharge, under the remaining ground. Samples abstracted from boreholes frequently contain significant levels of 3 H indicating a component of post-1953 recharge. This results from hydraulic connection to the borehole water column in deep boreholes or directly to the surface storage in the case of shallow boreholes. On the basis of 14 C and 4 He contents, details of which are being reported separately, the oldest analysed water (from 259 to 281 m in borehole A1B) has an age of about 10 4 years. The results are discussed. (author)

Recharge processes and vertical transfer investigated through long-term monitoring of dissolved gases in shallow groundwater

Science.gov (United States)

de Montety, V.; Aquilina, L.; Labasque, T.; Chatton, E.; Fovet, O.; Ruiz, L.; Fourré, E.; de Dreuzy, J. R.

2018-05-01

We investigated temporal variations and vertical evolution of dissolved gaseous tracers (CFC-11, CFC-12, SF6, and noble gases), as well as 3H/3He ratio to determine groundwater recharge processes of a shallow unconfined, hard-rock aquifer in an agricultural catchment. We sampled dissolved gas concentration at 4 locations along the hillslope of a small experimental watershed, over 6 hydrological years, between 2 and 6 times per years, for a total of 20 field campaigns. We collected groundwater samples in the fluctuation zone and the permanently saturated zone using piezometers from 5 to 20 m deep. The purpose of this work is i) to assess the benefits of using gaseous tracers like CFCs and SF6 to study very young groundwater with flows suspected to be heterogeneous and variable in time, ii) to characterize the processes that control dissolved gas concentrations in groundwater during the recharge of the aquifer, and iii) to understand the evolution of recharge flow processes by repeated measurement campaigns, taking advantage of a long monitoring in a site devoted to recharge processes investigation. Gas tracer profiles are compared at different location of the catchment and for different hydrologic conditions. In addition, we compare results from CFCs and 3H/3He analysis to define the flow model that best explains tracer concentrations. Then we discuss the influence of recharge events on tracer concentrations and residence time and propose a temporal evolution of residence times for the unsaturated zone and the permanently saturated zone. These results are used to gain a better understanding of the conceptual model of the catchment and flow processes especially during recharge events.

Status and understanding of groundwater quality in the North San Francisco Bay Shallow Aquifer study unit, 2012; California GAMA Priority Basin Project (ver. 1.1, February 2018)

Science.gov (United States)

Bennett, George L.

2017-07-20

Groundwater quality in the North San Francisco Bay Shallow Aquifer study unit (NSF-SA) was investigated as part of the Priority Basin Project of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is in Marin, Mendocino, Napa, Solano, and Sonoma Counties and included two physiographic study areas: the Valleys and Plains area and the surrounding Highlands area. The NSF-SA focused on groundwater resources used for domestic drinking water supply, which generally correspond to shallower parts of aquifer systems than that of groundwater resources used for public drinking water supply in the same area. The assessments characterized the quality of untreated groundwater, not the quality of drinking water.This study included three components: (1) a status assessment, which characterized the status of the quality of the groundwater resources used for domestic supply for 2012; (2) an understanding assessment, which evaluated the natural and human factors potentially affecting water quality in those resources; and (3) a comparison between the groundwater resources used for domestic supply and those used for public supply.The status assessment was based on data collected from 71 sites sampled by the U.S. Geological Survey for the GAMA Priority Basin Project in 2012. To provide context, concentrations of constituents measured in groundwater were compared to U.S. Environmental Protection Agency (EPA) and California State Water Resources Control Board Division of Drinking Water regulatory and non-regulatory benchmarks for drinking-water quality. The status assessment used a grid-based method to estimate the proportion of the groundwater resources that has concentrations of water-quality constituents approaching or above benchmark concentrations. This method provides statistically unbiased results at the study-area scale and permits comparisons to other GAMA Priority Basin Project study areas.In the NSF-SA study unit as a whole, inorganic

Effect of irrigation return flow on groundwater recharge in an overexploited aquifer in Bangladesh

Science.gov (United States)

Touhidul Mustafa, Syed Md.; Shamsudduha, Mohammad; Huysmans, Marijke

2016-04-01

Irrigated agriculture has an important role in the food production to ensure food security of Bangladesh that is home to over 150 million people. However, overexploitation of groundwater for irrigation, particularly during the dry season, causes groundwater-level decline in areas where abstraction is high and surface geology inhibits direct recharge to underlying shallow aquifer. This is causing a number of potential adverse socio-economic, hydrogeological, and environmental problems in Bangladesh. Alluvial aquifers are primarily recharged during monsoon season from rainfall and surface sources. However, return flow from groundwater-fed irrigation can recharge during the dry months. Quantification of the effect of return flow from irrigation in the groundwater system is currently unclear but thought to be important to ensure sustainable management of the overexploited aquifer. The objective of the study is to investigate the effect of irrigation return flow on groundwater recharge in the north-western part of Bangladesh, also known as Barind Tract. A semi-physically based distributed water balance model (WetSpass-M) is used to simulate spatially distributed monthly groundwater recharge. Results show that, groundwater abstraction for irrigation in the study area has increased steadily over the last 29 years. During the monsoon season, local precipitation is the controlling factor of groundwater recharge; however, there is no trend in groundwater recharge during that period. During the dry season, however, irrigation return-flow plays a major role in recharging the aquifer in the irrigated area compared to local precipitation. Therefore, during the dry season, mean seasonal groundwater recharge has increased and almost doubled over the last 29 years as a result of increased abstraction for irrigation. The increase in groundwater recharge during dry season has however no significant effect in the improvement of groundwater levels. The relation between groundwater

Sustainability and policy for the thermal use of shallow geothermal energy

International Nuclear Information System (INIS)

Hähnlein, Stefanie; Bayer, Peter; Ferguson, Grant; Blum, Philipp

2013-01-01

Shallow geothermal energy is a renewable energy resource that has become increasingly important. However, the use has environmental, technical and social consequences. Biological, chemical, and physical characteristics of groundwater and subsurface are influenced by the development of this resource. To guarantee a sustainable use it is therefore necessary to consider environmental and technical criteria, such as changes in groundwater quality and temperature. In the current study a comprehensive overview of consequences of geothermal systems in shallow aquifers is provided. We conclude that there is still a lack of knowledge on long-term environmental consequences. Due to local differences in geology and hydrogeology as well as in technical requirements, it is not recommendable to define only static regulations, such as fixed and absolute temperature thresholds. Flexible temperature limits for heating and cooling the groundwater and subsurface are therefore advisable. The limits should be oriented on previously undisturbed temperatures, and chemical, physical and biological conditions of aquifers. Based on these findings, recommendations for a sustainable policy for shallow geothermal systems are provided including a potential legal framework for a sustainable use. - Highlights: • We provide an overview of consequences of geothermal systems in shallow aquifers. • Static regulations for heating or cooling groundwater are not recommendable. • Temperature limits should be flexible and orientated on background values. • Suggestions for a sustainable policy for shallow geothermal systems are provided. • A potential legal framework for a sustainable use is presented

Hydrogeological characterization and assessment of groundwater ...

Indian Academy of Sciences (India)

In this perspective, assessment of groundwater quality in shallow aquifers in vicinity of the ... contributes about 60% of the total wastewater that gets discharged from ...... tern and effective groundwater management; Proc. Indian. Nat. Sci. Acad.

Changing Precipitation Patterns or Waning Glaciers? Identifying Water Supply Vulnerabilities to Climate Change in the Bolivian Andes

Science.gov (United States)

Guido, Z. S.; McIntosh, J. C.; Papuga, S. A.

2010-12-01

The Bolivian Andes have become an iconic example for the impacts of climate change. Glaciers are rapidly melting and some have already completely disappeared. More than 75 percent of the water consumed by 2 million people living on the flanks of the Bolivian Andes comes from mountains and it is often cited that the dwindling ice threatens the water supply of the expanding and destitute population living in the twin cities of La Paz and El Alto. However, the wet and the warm seasons and the cold and dry seasons coincide, causing high precipitation and ice melt—and therefore high streamflows—to occur only in the austral summer (October-March); during the austral winter, cold conditions limit glacier melt. This suggests that reductions in the water supply could be influenced more by changing precipitation amounts than continued glacial mass-wasting. We hypothesize that precipitation is the principal component of groundwater recharge for the aquifers at the base of the central Cordillera Real. Oxygen and hydrogen isotopes from rivers partially fed by glaciers, groundwater, and glacial melt water can help determine the relative contribution of precipitation and glacial melt to important water supplies. During the dry season in August 2010, we sampled 23 sites that follow the flow path of water in the Condiriri watershed, beginning in the glacial headwaters and ending several kilometers upriver from Lake Titicaca. We collected five samples at the toe of the Pequeño Alpamayo glacier and four samples from three tributary rivers that drain glaciated headwaters, which include meltwater from the Pequeño Alpamayo glacier. W also collected 14 water samples from shallow and deep wells in rural communities within 40 kilometers of the glaciers. If the isotopic values of groundwater are similar to rain values, as we suspect, precipitation is likely the largest contributor to groundwater resources in the region and will suggest that changing precipitation patterns present the

Groundwater flow and potential effects on evaporite dissolution in the Paradox Basin, SE Utah

Science.gov (United States)

Reitman, N.; Ge, S.; Mueller, K. J.

2012-12-01

A hydrogeologic study was conducted in the portion of the Paradox Basin south of the Needles District of Canyonlands National Park, Utah. Geology of the study area comprises fractured and faulted Paleozoic sandstone, limestone, and shale, which are underlain by evaporite cycles of the Paradox Formation. The evaporite deposits deform and dissolve when they come in contact with groundwater, generating land subsidence, saline groundwater, and salt input to the Colorado River. Active faults in the region slip at a rate of approximately 2 mm/year, likely due to evaporite dissolution. The objective of this study is to better understand groundwater flow and solute transport dynamics and to help determine the rate and timing of subsurface salt dissolution, which is an important control on the salt tectonics in the region. Study methods include hydrologic fieldwork, laboratory tests, and numerical modeling. No groundwater wells exist in the study area. Water samples from springs and seeps were collected throughout the study area. Analysis of total dissolved solids (TDS), stable oxygen (δ18O) and deuterium (δD) isotopes, spring and seep locations, and prior data are used to gain a preliminary understanding of the shallow groundwater flow in the region. Stable isotope ratios of oxygen (18O/16O) and deuterium (D/H) are used to constrain the source of spring water. Measured δ values are compared to predicted δ values for precipitation from WaterIsotopes.org for each sample site. Measured isotopic values range from -14.9 ‰ to -10.7 ‰ for δ18O and -108 ‰ to -78 ‰ for δD. The majority of samples from above 2000 m match predicted isotopic values for precipitation. Most samples taken below 2000 m are lighter than predicted isotopic values for precipitation. The TDS of spring samples measured in the lab show they range from 184 mg/L to 1552 mg/L with the majority of samples between 220 - 430 mg/L. TDS shows a weak correlation (R2 = 0.54) with altitude, where lower TDS

Potential impact of climate change on groundwater resources in the Central Huai Luang Basin, Northeast Thailand.

Science.gov (United States)

Pholkern, Kewaree; Saraphirom, Phayom; Srisuk, Kriengsak

2018-08-15

The Central Huai Luang Basin is one of the important rice producing areas of Udon Thani Province in Northeastern Thailand. The basin is underlain by the rock salt layers of the Maha Sarakham Formation and is the source of saline groundwater and soil salinity. The regional and local groundwater flow systems are the major mechanisms responsible for spreading saline groundwater and saline soils in this basin. Climate change may have an impact on groundwater recharge, on water table depth and the consequences of waterlogging, and on the distribution of soil salinity in this basin. Six future climate conditions from the SEACAM and CanESM2 models were downscaled to investigate the potential impact of future climate conditions on groundwater quantity and quality in this basin. The potential impact was investigated by using a set of numerical models, namely HELP3 and SEAWAT, to estimate the groundwater recharge and flow and the salt transport of groundwater simulation, respectively. The results revealed that within next 30years (2045), the future average annual temperature is projected to increase by 3.1°C and 2.2°C under SEACAM and CanESM2 models, respectively, while the future precipitation is projected to decrease by 20.85% under SEACAM and increase by 18.35% under the CanESM2. Groundwater recharge is projected to increase under the CanESM2 model and to slightly decrease under the SEACAM model. Moreover, for all future climate conditions, the depths of the groundwater water table are projected to continuously increase. The results showed the impact of climate change on salinity distribution for both the deep and shallow groundwater systems. The salinity distribution areas are projected to increase by about 8.08% and 56.92% in the deep and shallow groundwater systems, respectively. The waterlogging areas are also projected to expand by about 63.65% from the baseline period. Copyright © 2018 Elsevier B.V. All rights reserved.

Mitigating Groundwater Depletion in North China Plain with Cropping System that Alternate Deep and Shallow Rooted Crops

Directory of Open Access Journals (Sweden)

Xiao-Lin Yang

2017-06-01

Full Text Available In the North China Plain, groundwater tables have been dropping at unsustainable rates of 1 m per year due to irrigation of a double cropping system of winter wheat and summer maize. To reverse the trend, we examined whether alternative crop rotations could save water. Moisture contents were measured weekly at 20 cm intervals in the top 180 cm of soil as part of a 12-year field experiment with four crop rotations: sweet potato→ cotton→ sweet potato→ winter wheat-summer maize (SpCSpWS, 4-year cycle; peanuts → winter wheat-summer maize (PWS, 2-year cycle; ryegrass–cotton→ peanuts→ winter wheat-summer maize (RCPWS, 3-year cycle; and winter wheat-summer maize (WS, each year. We found that, compared to WS, the SpCSpWS annual evapotranspiration was 28% lower, PWS was 19% lower and RCPWS was 14% lower. The yield per unit of water evaporated improved for wheat within any alternative rotation compared to WS, increasing up to 19%. Average soil moisture contents at the sowing date of wheat in the SpCSpWS, PWS, and RCPWS rotations were 7, 4, and 10% higher than WS, respectively. The advantage of alternative rotations was that a deep rooted crop of winter wheat reaching down to 180 cm followed shallow rooted crops (sweet potato and peanut drawing soil moisture from 0 to 120 cm. They benefited from the sequencing and vertical complementarity of soil moisture extraction. Thus, replacing the traditional crop rotation with cropping system that involves rotating with annual shallow rooted crops is promising for reducing groundwater depletion in the North China Plain.

Hydro-geochemical paths of multi-layer groundwater system in coal mining regions - Using multivariate statistics and geochemical modeling approaches.

Science.gov (United States)

Liu, Pu; Hoth, Nils; Drebenstedt, Carsten; Sun, Yajun; Xu, Zhimin

2017-12-01

Groundwater is an important drinking water resource that requires protection in North China. Coal mining industry in the area may influence the water quality evolution. To provide primary characterization of the hydrogeochemical processes and paths that control the water quality evolution, a complex multi-layer groundwater system in a coal mining area is investigated. Multivariate statistical methods involving hierarchical cluster analysis (HCA) and principal component analysis (PCA) are applied, 6 zones and 3 new principal components are classified as major reaction zones and reaction factors. By integrating HCA and PCA with hydrogeochemical correlations analysis, potential phases, reactions and connections between various zones are presented. Carbonates minerals, gypsum, clay minerals as well as atmosphere gases - CO 2 , H 2 O and NH 3 are recognized as major reactants. Mixtures, evaporation, dissolution/precipitation of minerals and cation exchange are potential reactions. Inverse modeling is finally used, and it verifies the detailed processes and diverse paths. Consequently, 4 major paths are found controlling the variations of groundwater chemical properties. Shallow and deep groundwater is connected primarily by the flow of deep groundwater up through fractures and faults into the shallow aquifers. Mining does not impact the underlying aquifers that represent the most critical groundwater resource. But controls should be taken to block the mixing processes from highly polluted mine water. The paper highlights the complex hydrogeochemical evolution of a multi-layer groundwater system under mining impact, which could be applied to further groundwater quality management in the study area, as well as most of the other coalfields in North China. Copyright © 2017 Elsevier B.V. All rights reserved.

Pesticides in groundwater in the Anacostia River and Rock Creek watersheds in Washington, D.C., 2005 and 2008

Science.gov (United States)

Koterba, Michael T.; Dieter, Cheryl A.; Miller, Cherie V.

2010-01-01

preliminary review of the data collected in 2005 and 2008 indicated that differences in the surficial geology, land use (as a surrogate for pesticide use), and above-average precipitation for most of 2004 through 2008, as well as differences in the number and performance of USGS laboratory methods used, could have led to more pesticides detected in groundwater samples collected in 2008 than in groundwater samples collected in 2005. Thus, although data from both years of collection were used for interpretive analysis, emphasis was placed on the analysis of the data obtained in 2008. The presence of pesticides in shallow groundwater (less than approximately 100 ft (feet), or 30 m (meters), below land surface) indicated at least the upper surficial aquifer in Washington, D.C. was susceptible to contamination. One or more herbicides or insecticides were detected in groundwater samples collected from 50 percent of the shallow wells sampled in 2005, and from 62 percent of the shallow wells sampled in 2008. Differences among types of pesticides in shallow groundwater were apparent. The most frequently detected class of herbicides was the s-triazine compounds-atrazine, simazine, or prometon, or the atrazine-degradate compounds-2-chloro-4-ethylamino-6-amino-s-triazine (desethylatrazine or CIAT) and 2-chloro-4-isopropylamino-6-amino-s-triazine (hydroxyatrazine or OIET). The next most frequently detected classes of herbicides were the chloroacetanilides, including metolachlor and acetochlor, and the ureic herbicides, including diuron (and degradate, 3,4-dichloroaniline), fluometuron, metsulfuron methyl, sulfameturon, bromacil, and tebuthiuron. Insecticides also were detected, but less frequently than herbicides, with one or more insecticides present in groundwater samples from 38 percent of shallow wells sampled in 2008. Detected insecticides included parent or degradate compounds commonly used for either nonspecific or haustellate (sucking) insects, including chlorpyri

Simulating deep convection with a shallow convection scheme

Directory of Open Access Journals (Sweden)

C. Hohenegger

2011-10-01

Full Text Available Convective processes profoundly affect the global water and energy balance of our planet but remain a challenge for global climate modeling. Here we develop and investigate the suitability of a unified convection scheme, capable of handling both shallow and deep convection, to simulate cases of tropical oceanic convection, mid-latitude continental convection, and maritime shallow convection. To that aim, we employ large-eddy simulations (LES as a benchmark to test and refine a unified convection scheme implemented in the Single-column Community Atmosphere Model (SCAM. Our approach is motivated by previous cloud-resolving modeling studies, which have documented the gradual transition between shallow and deep convection and its possible importance for the simulated precipitation diurnal cycle.

Analysis of the LES reveals that differences between shallow and deep convection, regarding cloud-base properties as well as entrainment/detrainment rates, can be related to the evaporation of precipitation. Parameterizing such effects and accordingly modifying the University of Washington shallow convection scheme, it is found that the new unified scheme can represent both shallow and deep convection as well as tropical and mid-latitude continental convection. Compared to the default SCAM version, the new scheme especially improves relative humidity, cloud cover and mass flux profiles. The new unified scheme also removes the well-known too early onset and peak of convective precipitation over mid-latitude continental areas.

Isotope method to study the replenishment the lakes and downstream groundwater in Badain Jaran desert

International Nuclear Information System (INIS)

Chen Jiansheng; Fan Zhechao; Gu Weizu; Zhao Xia; Wang Jiyang

2003-01-01

In the paper, the sources of spring water and well water of Qilian Mountain's north side, Longshou Mountain, Badain Jaran Desert, Gurinai, Guaizi Lake, and Ejina Basin are studied by the methods of environmental isotopes and water chemistry. The groundwater of downstream areas (such as Badain Jaran Desert) is found that it is recharged by the precipitation of Qilian Mountain, and the average recharge elevation is 3300 m. Lots of naked limestones layers exist at the mountaintop of Qilian Mountain. The snow water of Qilian Mountain melts and directly infiltrates into deep layer passing through karst stratum or Big Fault in Front of the Mountain, and directly recharges into Badain Jaran Desert and its downstream areas passing through Longshou Mountain. The calcareous cementation and travertine, found in the lakes of the desert, approve that the groundwater passed the limestone layer. Confined water recharges shallow aquifer by means of leakage. The groundwater recharge volume is six hundreds millions cubic meters per year by calculating the evaporation amount, and the age of confined groundwater is 20-30 years. (authors)

Spatial distribution of triazine residues in a shallow alluvial aquifer linked to groundwater residence time.

Science.gov (United States)

Sassine, Lara; Le Gal La Salle, Corinne; Khaska, Mahmoud; Verdoux, Patrick; Meffre, Patrick; Benfodda, Zohra; Roig, Benoît

2017-03-01

At present, some triazine herbicides occurrence in European groundwater, 13 years after their use ban in the European Union, remains of great concern and raises the question of their persistence in groundwater systems due to several factors such as storage and remobilization from soil and unsaturated zone, limited or absence of degradation, sorption in saturated zones, or to continuing illegal applications. In order to address this problem and to determine triazine distribution in the saturated zone, their occurrence is investigated in the light of the aquifer hydrodynamic on the basis of a geochemical approach using groundwater dating tracers ( 3 H/ 3 He). In this study, atrazine, simazine, terbuthylazine, deethylatrazine, deisopropylatrazine, and deethylterbuthylazine are measured in 66 samples collected between 2011 and 2013 from 21 sampling points, on the Vistrenque shallow alluvial aquifer (southern France), covered by a major agricultural land use. The frequencies of quantification range from 100 to 56 % for simazine and atrazine, respectively (LQ = 1 ng L -1 ). Total triazine concentrations vary between 15 and 350 ng L -1 and show three different patterns with depth below the water table: (1) low concentrations independent of depth but related to water origin, (2) an increase in concentrations with depth in the aquifer related to groundwater residence time and triazine use prior to their ban, and (3) relatively high concentrations at low depths in the saturated zone more likely related to a slow desorption of these compounds from the soil and unsaturated zone. The triazine attenuation rate varies between 0.3 for waters influenced by surface water infiltration and 4.8 for water showing longer residence times in the aquifer, suggesting an increase in these rates with water residence time in the saturated zone. Increasing triazine concentrations with depth is consistent with a significant decrease in the use of these pesticides for the last 10 years on

Identification of hydrogeochemical processes and pollution sources of groundwater nitrate in Leiming Basin of Hainan island, Southern China

Science.gov (United States)

Shaowen, Y.; Zhan, Y., , Dr; Li, Q.

2017-12-01

Identifying the evolution of groundwater quality is important for the control and management of groundwater resources. The main aims of the present study are to identify the major factors affecting hydrogeochemistry of groundwater resources and to evaluate the potential sources of groundwater nitrate in Leiming basin using chemical and isotopic methods. The majority of samples belong to Na-Cl water type and are followed by Ca-HCO3 and mixed Ca-Na-HCO3. The δ18O and δ2H values in groundwater indicate that the shallow fissure groundwater is mainly recharged by rainfall. The evaporated surface water is another significant origin of groundwater. The weathering and dissolution of different rocks and minerals, input of precipitation, evaporation, ion exchange and anthropogenic activities, especially agricultural activities, influence the hydrogeochemistry of the study area. NO- 3 concentration in the groundwater varies from 0.7 to 51.7 mg/L and high values are mainly occurred in the densely populated area. The combined use of isotopic values and hydrochemical data suggests that the NO- 3 load in Leiming basin is not only derived from agricultural activities but also from other sources such as waste water and atmospheric deposition. Fertilizer is considered as the major source of NO- 3 in the groundwater in Leiming basin.

Groundwater sustainability assessment in coastal aquifers

Indian Academy of Sciences (India)

The present work investigates the response of shallow, coastal unconfined aquifers to anticipated overdraft conditions and climate change effect using numerical simulation. The groundwater flow model MODFLOW and variable density groundwater model SEAWAT are used for this investigation. The transmissivity and ...

Investigation of the climate-driven periodicity of shallow groundwater level fluctuations in a Central-Eastern European agricultural region

Science.gov (United States)

Garamhegyi, Tamás; Kovács, József; Pongrácz, Rita; Tanos, Péter; Hatvani, István Gábor

2018-05-01

The distribution and amount of groundwater, a crucial source of Earth's drinking and irrigation water, is changing due to climate-change effects. Therefore, it is important to understand groundwater behavior in extreme scenarios, e.g. drought. Shallow groundwater (SGW) level fluctuation under natural conditions displays periodic behavior, i.e. seasonal variation. Thus, the study aims to investigate (1) the periodic behavior of the SGW level time series of an agriculturally important and drought-sensitive region in Central-Eastern Europe - the Carpathian Basin, in the north-eastern part of the Great Hungarian Plain, and (2) its relationship to the European atmospheric pressure action centers. Data from 216 SGW wells were studied using wavelet spectrum analysis and wavelet coherence analyses for 1961-2010. Locally, a clear relationship exists between the absence of annual periodic behavior in the SGW level and the periodicity of droughts, as indicated by the self-calibrating Palmer Drought Severity Index and the Aridity Index. During the non-periodic intervals, significant drops in groundwater levels (average 0.5 m) were recorded in 89% of the wells. This result links the meteorological variables to the periodic behavior of SGW, and consequently, drought. On a regional scale, Mediterranean cyclones from the Gulf of Genoa (northwest Italy) were found to be a driving factor in the 8-yr periodic behavior of the SGW wells. The research documents an important link between SGW levels and local/regional climate variables or indices, thereby facilitating the necessary adaptation strategies on national and/or regional scales, as these must take into account the predictions of drought-related climatic conditions.

Breakthrough of two pesticides into tile drain and shallow groundwater: comparison of tile drain reaction and soil profiles within a field scale irrigation experiment

Science.gov (United States)

Klaus, Julian; Zehe, Erwin; Elsner, Martin; Palm, Juliane; Schneider, Dorothee; Schröder, Boris; Steinbeiss, Sibylle; West, Stephanie

2010-05-01

Preferential flow in macropores is a key process which strongly affects infiltration and may cause rapid transport of pesticides into depths of 80 to 150 cm. At these depths they experience a much slower degradation, may leach into shallow groundwater or enter a tile-drain and are transported into surface water bodies. Therefore, preferential transport might be an environmental problem, if the topsoil is bypassed, which has been originally thought to act as a filter to protect the subsoil and shallow groundwater. To investigate the behaviour of two pesticides with different chemical characteristics and to compare their transport behaviour in soil and into the tile drain an irrigation experiment was performed on a 400 m² field site. The experimental plot is located in the Weiherbach valley, south-west Germany, which basic geology consists of Loess and Keuper layers, the soil at the test site is a gleyic Colluvisol. The distance of the irrigation site to the Weiherbach brook is approximately 12 m, the field is drained with a tile-drain in about 1.2 m depth and shows discharge over the entire year. Three hours before the irrigation started, the farmer applied a pesticide solution consisting of Isoproturon (80 g) and Flufenacet (20 g) (IPU and FLU) according to conventional agricultural practice on the field plot. The irrigation took place in three time blocks (80 min, 60 min, 80 min) with in total 33.6 mm of precipitation. During the first block 1600 g of Bromide were mixed in the irrigation water. The drainage outlet was instrumented with a pressure probe. About 50 water samples ware taken during the experimental day, and several samples more the days after the experiment. They were analysed for the pesticides, bromide and water isotopes. In the two days after the experiment three soil profiles were excavated and soil samples were taken on a 10x10 cm² scheme. One week after the experiment two additional profiles were excavated. The soil was analysed for IPU, FLU

Spatial and temporal variations in shallow wetland groundwater quality

Science.gov (United States)

Schot, Paul P.; Pieber, Simone M.

2012-02-01

SummaryWetlands worldwide are threatened by environmental change. Differences in groundwater composition is one of the factors affecting wetland terrestrial floristic biodiversity. However, few studies discuss variations in wetland groundwater composition. This study presents an analysis of local-scale spatial and short-term temporal variations in 15 groundwater composition parameters of the 7 km2 Naardermeer wetland nature reserve in The Netherlands. Data is available from a network of 35 groundwater wells with 2-4 filters each, at depths between 50 and 800 cm, which were sampled about monthly over a 1-year period, totalling 1042 chemical analysis from 103 filter screens. Relative standard deviations indicate large differences in variation between parameters. Largest spatial and temporal variations were found for nutrients (NO3-, PO43-, NH4+) and redox sensitive parameters (Fe, Mn), and lowest variations for macroions and SiO2. A horizontal zonation in groundwater concentrations has been found related to soil type and soil wetness, with largest horizontal decrease in NO3- and SO42-, and largest increase in Fe and SiO2, going in the groundwater flow direction from dry sandy soils to wet peat/clay soils. No clear horizontal patterns have been found for the macroions. Spatial zonations in the north-south direction and with depth are absent for all parameters. Spatial and temporal variations were found to be related. 3D-maps indicate highest temporal fluctuations at filter screens with lowest median concentrations for NO3-, SO42- and Fe, but the reverse pattern for SiO2. High temporal variations of nutrients and redox sensitive parameters could not be traced back to a seasonal trend. The spatial and temporal variability of groundwater quality parameters as presented in this study, together with their reported effects on different vegetation types, may be used to design efficient monitoring schemes by nature managers having set specific vegetation development targets

Investigating riparian groundwater flow close to a losing river using diurnal temperature oscillations at high vertical resolution

Directory of Open Access Journals (Sweden)

T. Vogt

2012-02-01

Full Text Available River-water infiltration is of high relevance for hyporheic and riparian groundwater ecology as well as for drinking water supply by river-bank filtration. Heat has become a popular natural tracer to estimate exchange rates between rivers and groundwater. However, quantifying flow patterns and velocities is impeded by spatial and temporal variations of exchange fluxes, insufficient sensors spacing during field investigations, or simplifying assumptions for analysis or modeling such as uniform flow. The objective of this study is to investigate lateral shallow groundwater flow upon river-water infiltration at the shoreline of the riverbed and in the adjacent riparian zone of the River Thur in northeast Switzerland. Here we have applied distributed temperature sensing (DTS along optical fibers wrapped around tubes to measure high-resolution vertical temperature profiles of the unsaturated zone and shallow riparian groundwater. Diurnal temperature oscillations were tracked in the subsurface and analyzed by means of dynamic harmonic regression to extract amplitudes and phase angles. Subsequent calculations of amplitude attenuation and time shift relative to the river signal show in detail vertical and temporal variations of heat transport in shallow riparian groundwater. In addition, we apply a numerical two-dimensional heat transport model for the unsaturated zone and shallow groundwater to obtain a better understanding of the observed heat transport processes in shallow riparian groundwater and to estimate the groundwater flow velocity. Our results show that the observed riparian groundwater temperature distribution cannot be described by uniform flow, but rather by horizontal groundwater flow velocities varying over depth. In addition, heat transfer of diurnal temperature oscillations from the losing river through shallow groundwater is influenced by thermal exchange with the unsaturated zone. Neglecting the influence of the unsaturated zone

CO2/Brine transport into shallow aquifers along fault zones.

Science.gov (United States)

Keating, Elizabeth H; Newell, Dennis L; Viswanathan, Hari; Carey, J W; Zyvoloski, G; Pawar, Rajesh

2013-01-02

Unintended release of CO(2) from carbon sequestration reservoirs poses a well-recognized risk to groundwater quality. Research has largely focused on in situ CO(2)-induced pH depression and subsequent trace metal mobilization. In this paper we focus on a second mechanism: upward intrusion of displaced brine or brackish-water into a shallow aquifer as a result of CO(2) injection. Studies of two natural analog sites provide insights into physical and chemical mechanisms controlling both brackish water and CO(2) intrusion into shallow aquifers along fault zones. At the Chimayó, New Mexico site, shallow groundwater near the fault is enriched in CO(2) and, in some places, salinity is significantly elevated. In contrast, at the Springerville, Arizona site CO(2) is leaking upward through brine aquifers but does not appear to be increasing salinity in the shallow aquifer. Using multiphase transport simulations we show conditions under which significant CO(2) can be transported through deep brine aquifers into shallow layers. Only a subset of these conditions favor entrainment of salinity into the shallow aquifer: high aspect-ratio leakage pathways and viscous coupling between the fluid phases. Recognition of the conditions under which salinity is favored to be cotransported with CO(2) into shallow aquifers will be important in environmental risk assessments.

Vulnerability of shallow groundwater and drinking-water wells to nitrate in the United States

Science.gov (United States)

Nolan, Bernard T.; Hitt, Kerie J.

2006-01-01

Two nonlinear models were developed at the national scale to (1) predict contamination of shallow ground water (typically drinking. The new models have several advantages over previous national-scale approaches. First, they predict nitrate concentration (rather than probability of occurrence), which can be directly compared with water-quality criteria. Second, the models share a mechanistic structure that segregates nitrogen (N) sources and physical factors that enhance or restrict nitrate transport and accumulation in ground water. Finally, data were spatially averaged to minimize small-scale variability so that the large-scale influences of N loading, climate, and aquifer characteristics could more readily be identified. Results indicate that areas with high N application, high water input, well-drained soils, fractured rocks or those with high effective porosity, and lack of attenuation processes have the highest predicted nitrate concentration. The shallow groundwater model (mean square error or MSE = 2.96) yielded a coefficient of determination (R2) of 0.801, indicating that much of the variation in nitrate concentration is explained by the model. Moderate to severe nitrate contamination is predicted to occur in the High Plains, northern Midwest, and selected other areas. The drinking-water model performed comparably (MSE = 2.00, R2 = 0.767) and predicts that the number of users on private wells and residing in moderately contaminated areas (>5 to ≤10 mg/L nitrate) decreases by 12% when simulation depth increases from 10 to 50 m.

Chemical barriers for controlling groundwater contamination

International Nuclear Information System (INIS)

Morrison, S.J.; Spangler, R.R.

1993-01-01

Chemical barriers are being explored as a low-cost means of controlling groundwater contamination. The barrier can intercept a contaminant plume and prevent migration by transferring contaminants from the groundwater to immobile solids. A chemical barrier can be emplaced in a landfill liner or in an aquifer cutoff wall or can be injected into a contaminant plume. Chemical barriers can be classified as either precipitation barriers or sorption barriers depending upon the dominant mode of contaminant extraction. In a precipitation barrier, contaminants are bound in the structures of newly formed phases; whereas, in a sorption barrier, contaminants attach to the surfaces of preexisting solids by adsorption or some other surface mechanism. Sorption of contaminants is pH dependent. A precipitation barrier can control the pH of the system, but alkaline groundwater may dominate the pH in a sorption barrier. A comparison is made of the characteristics of precipitation and sorption barriers. Experimental data on the extraction of uranium and molybdenum from simulated groundwater are used to demonstrate these concepts. 10 refs., 9 figs., 1 tab

Groundwater-level trends and implications for sustainable water use in the Kabul Basin, Afghanistan

Science.gov (United States)

Mack, Thomas J.; Chornack, Michael P.; Taher, Mohammad R.

2013-01-01

The Kabul Basin, which includes the city of Kabul, Afghanistan, with a population of approximately 4 million, has several Afghan, United States, and international military installations that depend on groundwater resources for a potable water supply. This study examined groundwater levels in the Kabul Basin from 2004 to 2012. Groundwater levels have increased slightly in rural areas of the Kabul Basin as a result of normal precipitation after the drought of the early 2000s. However, groundwater levels have decreased in the city of Kabul due to increasing water use in an area with limited recharge. The rate of groundwater-level decrease in the city is greater for the 2008–2012 period (1.5 meters per year (m/yr) on average) than for the 2004–2008 period (0–0.7 m/yr on average). The analysis, which is corroborated by groundwater-flow modeling and a non-governmental organization decision-support model, identified groundwater-level decreases and associated implications for groundwater sustainability in the city of Kabul. Military installations in the city of Kabul (the Central Kabul subbasin) are likely to face water management challenges resulting from long-term groundwater sustainability concerns, such as the potential drying of shallow water-supply wells. Installations in the northern part of the Kabul Basin may have fewer issues with long-term water sustainability. Groundwater-level monitoring and groundwater-flow simulation can be valuable tools for assessing groundwater management options to improve the sustainability of water resources in the Kabul Basin.

Global simulation of interactions between groundwater and terrestrial ecosystems

Science.gov (United States)

Braakhekke, M. C.; Rebel, K.; Dekker, S. C.; Smith, B.; Van Beek, L. P.; Sutanudjaja, E.; van Kampenhout, L.; Wassen, M. J.

2016-12-01

In many places in the world ecosystems are influenced by the presence of a shallow groundwater table. In these regions upward water flux due to capillary rise increases soil moisture availability in the root zone, which has strong positive effect on evapotranspiration. Additionally it has important consequences for vegetation dynamics and fluxes of carbon and nitrogen. Under water limited conditions shallow groundwater stimulates vegetation productivity, and soil organic matter decomposition while under saturated conditions groundwater may have a negative effect on these processes due to lack of oxygen. Furthermore, since plant species differ with respect to their root distribution, preference for moisture conditions, and resistance to oxygen stress, shallow groundwater also influences vegetation type. Finally, processes such as denitrification and methane production occur under strictly anaerobic conditions and are thus strongly influenced by moisture availability. Most global hydrological models and several land surface models simulate groundwater table dynamics and their effects on land surface processes. However, these models typically have relatively simplistic representation of vegetation and do not consider changes in vegetation type and structure and are therefore less suitable to represent effects of groundwater on biogeochemical fluxes. Dynamic global vegetation models (DGVMs), describe land surface from an ecological perspective, combining detailed description of vegetation dynamics and structure and biogeochemical processes. These models are thus more appropriate to simulate the ecological and biogeochemical effects of groundwater interactions. However, currently virtually all DGVMs ignore these effects, assuming that water tables are too deep to affect soil moisture in the root zone. We have implemented a tight coupling between the dynamic global ecosystem model LPJ-GUESS and the global hydrological model PCR-GLOBWB. Using this coupled model we aim to

Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China

International Nuclear Information System (INIS)

Li, Chengcheng; Gao, Xubo; Wang, Yanxin

2015-01-01

Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F − concentration of up to 14.1 mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F − concentrations above the WHO provisional drinking water guideline of 1.5 mg/L. Groundwater with high F − concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO 3 − content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F − mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F − in groundwater of the intermediate and deep aquifers. - Highlights: • High-F − groundwater widely occurs in Yuncheng Basin of northern China. • High-F − groundwater is Na and HCO 3 -rich and Ca-poor, with high pH. • Major hydrogeochemical processes are mineral dissolution, ion exchange and evaporation. • Shallow groundwater leakage/evaporite dissolution may cause F enrichment in lower aquifers

Shallow groundwater quality in the Village of Patchogue, Suffolk County, New York

Science.gov (United States)

Abbene, Irene J.

2010-01-01

The onsite disposal of wastewater within the Patchogue River Basin-a riverine estuary that discharges into Great South Bay, Suffolk County, Long Island, N.Y. -has adversely affected water quality and aquatic habitats within both the tidal and non-tidal portions of the river. In response to increased development within the approximately 14 square mile basin, the Village of Patchogue has expanded efforts to manage and protect the local groundwater resources, which sustain freshwater base flow and aquatic habitats. Water-quality samples from 10 shallow wells within the Village were collected in March 2009, before the start of seasonal fertilizer application, to document the effects of onsite wastewater disposal on groundwater discharging into the Patchogue River. Each sample was analyzed for physical properties (pH, dissolved oxygen, specific conductance, and temperature), nutrients, organic carbon, major ions, and trace elements. Water samples from eight wells were analyzed for stable isotopes of nitrogen. The nitrate concentration in one well was 40 milligrams per liter (mg/L), which exceeded the U.S. Environmental Protection Agency (USEPA) and New York State Department of Health (NYSDOH) maximum contamination level in drinking water of 10 mg/L. Sodium concentrations at nine wells exceeded the USEPA Drinking Water Advisory Taste Threshold of 60 mg/L. Dissolved iron concentrations at three wells exceeded the NYSDOH and USEPA Secondary Drinking Water Standard of 300 micrograms per liter (?g/L). Nitrogen isotope signatures (d15N) were determined and compared with those reported from previous studies in Nassau and Suffolk Counties to identify possible sources of the nitrate. Local variations in measured ammonia, nitrate, total nitrogen, phosphorus, and organic carbon concentrations and d15N signatures indicate that nitrate enters the surficial aquifer from several sources (fertilizer, septic waste, and animal waste) and reflects biogeochemical processes such as

Heat as a groundwater tracer in shallow and deep heterogeneous media: Analytical solution, spreadsheet tool, and field applications

Science.gov (United States)

Kurylyk, Barret L.; Irvine, Dylan J.; Carey, Sean K.; Briggs, Martin A.; Werkema, Dale D.; Bonham, Mariah

2017-01-01

Groundwater flow advects heat, and thus, the deviation of subsurface temperatures from an expected conduction‐dominated regime can be analysed to estimate vertical water fluxes. A number of analytical approaches have been proposed for using heat as a groundwater tracer, and these have typically assumed a homogeneous medium. However, heterogeneous thermal properties are ubiquitous in subsurface environments, both at the scale of geologic strata and at finer scales in streambeds. Herein, we apply the analytical solution of Shan and Bodvarsson (2004), developed for estimating vertical water fluxes in layered systems, in 2 new environments distinct from previous vadose zone applications. The utility of the solution for studying groundwater‐surface water exchange is demonstrated using temperature data collected from an upwelling streambed with sediment layers, and a simple sensitivity analysis using these data indicates the solution is relatively robust. Also, a deeper temperature profile recorded in a borehole in South Australia is analysed to estimate deeper water fluxes. The analytical solution is able to match observed thermal gradients, including the change in slope at sediment interfaces. Results indicate that not accounting for layering can yield errors in the magnitude and even direction of the inferred Darcy fluxes. A simple automated spreadsheet tool (Flux‐LM) is presented to allow users to input temperature and layer data and solve the inverse problem to estimate groundwater flux rates from shallow (e.g., regimes.

Environmental Isotopes Method For Study Of The Migration Of Nitrate Pollutant In The Shallow Groundwater Of Bantar Gebang Sanitary Landfill, Bekasi

International Nuclear Information System (INIS)

Syafalni

2002-01-01

An investigation was carried out to determine the influence of sanitary landfill of the Bantar Gebang, Bekasi on the origin and migration of pollutant in the shallow groundwater situated in and around the disposal site of Bantar Gebang landfill. The study revealed that domestic shallow wells are becoming increasingly polluted with nitrate in the region which have been distributed more than I Ian from the site. Based on the environmental isotope method (analysis of 18 O and 2 H) and hydrochemistry evaluation, it showed the same trend. The level of nitrate in the observation wells were found vary widely from 0.0 to 94.43 ppm for sampling period of April-May 2001 and 0.0 to 23.9 ppm for sampling period of August-September 2001. Some of the observation wells have indicated exceeding the maximum permissible limit specified for drinking water

Response of groundwater level and surface-water/groundwater interaction to climate variability: Clarence-Moreton Basin, Australia

Science.gov (United States)

Cui, Tao; Raiber, Matthias; Pagendam, Dan; Gilfedder, Mat; Rassam, David

2018-03-01

Understanding the response of groundwater levels in alluvial and sedimentary basin aquifers to climatic variability and human water-resource developments is a key step in many hydrogeological investigations. This study presents an analysis of groundwater response to climate variability from 2000 to 2012 in the Queensland part of the sedimentary Clarence-Moreton Basin, Australia. It contributes to the baseline hydrogeological understanding by identifying the primary groundwater flow pattern, water-level response to climate extremes, and the resulting dynamics of surface-water/groundwater interaction. Groundwater-level measurements from thousands of bores over several decades were analysed using Kriging and nonparametric trend analysis, together with a newly developed three-dimensional geological model. Groundwater-level contours suggest that groundwater flow in the shallow aquifers shows local variations in the close vicinity of streams, notwithstanding general conformance with topographic relief. The trend analysis reveals that climate variability can be quickly reflected in the shallow aquifers of the Clarence-Moreton Basin although the alluvial aquifers have a quicker rainfall response than the sedimentary bedrock formations. The Lockyer Valley alluvium represents the most sensitively responding alluvium in the area, with the highest declining (-0.7 m/year) and ascending (2.1 m/year) Sen's slope rates during and after the drought period, respectively. Different surface-water/groundwater interaction characteristics were observed in different catchments by studying groundwater-level fluctuations along hydrogeologic cross-sections. The findings of this study lay a foundation for future water-resource management in the study area.

Interaction between shallow and deep aquifers in the Tivoli Plain (Central Italy) enhanced by groundwater extraction: A multi-isotope approach and geochemical modeling

International Nuclear Information System (INIS)

Carucci, Valentina; Petitta, Marco; Aravena, Ramon

2012-01-01

In the Tivoli Plain (Rome, Central Italy) the interaction between shallow and deep groundwater flow systems enhanced by groundwater extraction has been investigated using isotopic and chemical tracers. A conceptual model of the groundwater flowpaths has been developed and verified by geochemical modeling. A combined hydrogeochemical and isotopic investigation using ion relationships such as DIC/Cl − , Ca/(Ca + Mg)/SO 4 /(SO 4 + HCO 3 ), and environmental isotopes (δ 18 O, δ 2 H, 87 Sr/ 86 Sr, δ 34 S and δ 13 C) was carried out in order to determine the sources of recharge of the aquifer, the origin of solutes and the mixing processes in groundwater of Tivoli Plain. Multivariate statistical methods such as principal component analysis and Cluster analyses have confirmed the existence of different geochemical facies and the role of mixing in the chemical composition of the groundwater. Results indicate that the hydrochemistry of groundwater is characterized by mixing between end-members coming directly from carbonate recharge areas and to groundwater circulating in a deeply buried Meso-Cenozoic carbonate sequence. The travertine aquifer is fed by both flow systems, but a local contribution by direct input in the Plain has also been recognized. The stable isotope data ( 18 O, 2 H, 13 C and 34 S) supports the flow system conceptual model inferred from the geochemical data and represents key data to quantify the geochemical mixing in the different groundwaters of the Plain. The results of numerical modeling (PHREEQC) are consistent with the flowpaths derived from the hydrogeochemical conceptual model. The inverse models performed generated the main geochemical processes occurring in the groundwater flow system, which also included mixing. Geochemical and isotope modeling demonstrate an increasing influence of groundwater from the deeply buried aquifer in the travertine aquifer, enhanced by lowering of the travertine aquifer water table due to quarry pumping.

Assessing the recharge of a coastal aquifer using physical observations, tritium, groundwater chemistry and modelling.

Science.gov (United States)

Santos, Isaac R; Zhang, Chenming; Maher, Damien T; Atkins, Marnie L; Holland, Rodney; Morgenstern, Uwe; Li, Ling

2017-02-15

Assessing recharge is critical to understanding groundwater and preventing pollution. Here, we investigate recharge in an Australian coastal aquifer using a combination of physical, modelling and geochemical techniques. We assess whether recharge may occur through a pervasive layer of floodplain muds that was initially hypothesized to be impermeable. At least 59% of the precipitation volume could be accounted for in the shallow aquifer using the water table fluctuation method during four significant recharge events. Precipitation events rates were estimated in the area underneath the floodplain clay layer rather than in the sandy area. A steady-state chloride method implied recharge rates of at least 200mm/year (>14% of annual precipitation). Tritium dating revealed long term net vertical recharge rates ranging from 27 to 114mm/year (average 58mm/year) which were interpreted as minimum net long term recharge. Borehole experiments revealed more permeable conditions and heterogeneous infiltration rates when the floodplain soils were dry. Wet conditions apparently expand floodplain clays, closing macropores and cracks that act as conduits for groundwater recharge. Modelled groundwater flow paths were consistent with tritium dating and provided independent evidence that the clay layer does not prevent local recharge. Overall, all lines of evidence demonstrated that the coastal floodplain muds do not prevent the infiltration of rainwater into the underlying sand aquifer, and that local recharge across the muds was widespread. Therefore, assuming fine-grained floodplain soils prevent recharge and protect underlying aquifers from pollution may not be reasonable. Copyright © 2016 Elsevier B.V. All rights reserved.

Mixing-induced groundwater denitrification beneath a manured field in southern Alberta, Canada

International Nuclear Information System (INIS)

McCallum, J.E.; Ryan, M.C.; Mayer, B.; Rodvang, S.J.

2008-01-01

Contamination of shallow groundwater by NO 3 - from manure may occur under fields where manure is spread as fertilizer and for disposal. Attenuation of NO 3 - in groundwater occurs through denitrification under certain conditions, or NO 3 - -contaminated younger groundwater may mix with older groundwater, lowering the NO 3 - concentration. In this study, δ 15 N and δ 18 O values of NO 3 - , and δ 18 O and δ 2 H values in groundwater under a manured field were evaluated to determine if groundwater NO 3 - concentrations were influenced through mixing of shallower, manure-impacted groundwater with older groundwater, or if denitrification was reducing NO 3 - concentrations. The younger groundwater showed clear evidence of manure impact with elevated Cl - (∼85 mg L -1 ) and NO 3 - concentrations (∼50 mg NO 3 -N L -1 ), and δ 15 N and δ 18 O values of NO 3 - consistent with a manure source. Vertical hydraulic gradients and δ 18 O and δ 2 H values in groundwater suggest older, more reduced groundwater is upwelling locally and mixing with the shallow groundwater. Decreasing NO 3 :Cl ratios, decreasing dissolved O 2 concentrations, and increasing δ 15 N and δ 18 O values of NO 3 - suggest that denitrification occurs locally in the aquifer. The extent of denitrification is proportional to the fraction of deeper groundwater in the aquifer. Denitrification apparently does not proceed in the younger, manure-impacted groundwater in the absence of mixing

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) ...

Characterization of shallow groundwater at TNX

International Nuclear Information System (INIS)

Nichols, R.L.

1993-01-01

The Savannah River Site (SRS), located on 300 square miles along the Savannah River near Aiken, South Carolina, is owned by the Department of Energy and operated by Westinghouse Savannah River Company. The site''s mission is to support the national security through the production of nuclear weapons material. With the recent reduction of the nation''s nuclear stockpile and the stronger focus on the cleanup of sites where nuclear operations activities have left behind soil and groundwater contamination, identifying and remediating all inactive wastes has become a primary goal.The TNX Area is located adjacent to the Savannah River in the western portion of SRS (Figure 1). The area is a pilot-scale test facility for the Savannah River Technology Center. Pilot-scale testing and evaluation of chemical processes at TNX have included support of the Defense Waste Processing Facility (DWPF), Separations Area, and fuel and target manufacturing areas. Wastewater generated during tests was discharged to unlined basins through a network of underground process sewers.A discussion of waste disposal activities for the TNX Area is included in this report to identify the major sources of contaminants that have impacted the groundwater

Groundwater quality in the shallow aquifers of the Monterey Bay, Salinas Valley, and adjacent highland areas, Southern Coast Ranges, California

Science.gov (United States)

Burton, Carmen

2018-05-30

The Monterey-Salinas Shallow Aquifer study unit covers approximately 7,820 square kilometers (km2) in Santa Cruz, Monterey, and San Luis Obispo Counties in the Central Coast Hydrologic Region of California. The study unit was divided into four study areas—Santa Cruz, Pajaro Valley, Salinas Valley, and Highlands. More than 75 percent of the water used for drinking-water supply in the Central Coast Hydrologic Region of California is groundwater, and there are more than 8,000 well driller’s logs for domestic wells (California Department of Water Resources, 2013).

Application of S. H. and O. stable isotopes to groundwater research in China

International Nuclear Information System (INIS)

Pan Shulan

1988-01-01

The δD, δ 18 O and δ 34 S of a lot of samples from the groundwater in the Tai-Yuan area have been determined. The precipitation line (in the Tai-Yuan area) we obtained is δD=7.6δ 18 O+10. A mixing line for west mountain karstic water and shallow water has been worked out, it is δD=5.6δ 18 O-16. It has been concluded that the quantity supplied by shallow water to Jin Spring is about 34%. Two karstic water systems are divided into the West Mountain system and East Mountain system. The Lan Spring belongs to the east one. S-isotope data indicates that there is less supply to the Lan Spring from the West Mountain system. Some sample preparation methods and mass spectrometric measurements in our laboratory are described. (author). 4 refs, 9 figs, 8 tabs

Deuterium, oxygen-18 and tritium in precipitation, surface and groundwater in the far east of Russia

Energy Technology Data Exchange (ETDEWEB)

Chelnokov, George; Kharitonova, Natalia; Bragin, Ivan; Vasil' eva, Maria [Far East Geological Insitute Rus. Acad. of Sci., 690022, Prospect 100 letya 159, Vladivostok (Russian Federation)

2013-07-01

This is the first report describing the parallel measurement of deuterium (δD), tritium ({sup 3}H), and oxygen-18 (δ{sup 18}O) in precipitation, seawater, surface and groundwater in relation to the Russian Far East. dD and δ{sup 18}O demonstrate that the studied waters have a meteoric origin, and variations are the result of water-rock-gas interactions. All studied waters reveal obvious 'latitudinal' and 'continental' effects: there is a universal decrease in δ{sup 18}O and δD from the south to the north, and from the ocean inland. The background level of {sup 3}H is 20 TU in Amursky region's rivers, 13 TU in Primorsky region's rivers, and 5.5 TU in one of the Kuril Islands. The majority of studied groundwaters have short residence times. (authors)

Simulating the effects of ground-water withdrawals on streamflow in a precipitation-runoff model

Science.gov (United States)

Zarriello, Philip J.; Barlow, P.M.; Duda, P.B.

2004-01-01

Precipitation-runoff models are used to assess the effects of water use and management alternatives on streamflow. Often, ground-water withdrawals are a major water-use component that affect streamflow, but the ability of surface-water models to simulate ground-water withdrawals is limited. As part of a Hydrologic Simulation Program-FORTRAN (HSPF) precipitation-runoff model developed to analyze the effect of ground-water and surface-water withdrawals on streamflow in the Ipswich River in northeastern Massachusetts, an analytical technique (STRMDEPL) was developed for calculating the effects of pumped wells on streamflow. STRMDEPL is a FORTRAN program based on two analytical solutions that solve equations for ground-water flow to a well completed in a semi-infinite, homogeneous, and isotropic aquifer in direct hydraulic connection to a fully penetrating stream. One analytical method calculates unimpeded flow at the stream-aquifer boundary and the other method calculates the resistance to flow caused by semipervious streambed and streambank material. The principle of superposition is used with these analytical equations to calculate time-varying streamflow depletions due to daily pumping. The HSPF model can readily incorporate streamflow depletions caused by a well or surface-water withdrawal, or by multiple wells or surface-water withdrawals, or both, as a combined time-varying outflow demand from affected channel reaches. These demands are stored as a time series in the Watershed Data Management (WDM) file. This time-series data is read into the model as an external source used to specify flow from the first outflow gate in the reach where these withdrawals are located. Although the STRMDEPL program can be run independently of the HSPF model, an extension was developed to run this program within GenScn, a scenario generator and graphical user interface developed for use with the HSPF model. This extension requires that actual pumping rates for each well be stored

Chase the direct impact of rainfall into groundwater in Mt. Fuji from multiple analyses including microbial DNA

Science.gov (United States)

Kato, Kenji; Sugiyama, Ayumi; Nagaosa, Kazuyo; Tsujimura, Maki

2016-04-01

A huge amount of groundwater is stored in subsurface environment of Mt. Fuji, the largest volcanic mountain in Japan. Based on the concept of piston flow transport of groundwater an apparent residence time was estimated to ca. 30 years by 36Cl/Cl ratio (Tosaki et al., 2011). However, this number represents an averaged value of the residence time of groundwater which had been mixed before it flushes out. We chased signatures of direct impact of rainfall into groundwater to elucidate the routes of groundwater, employing three different tracers; stable isotopic analysis (delta 18O), chemical analysis (concentration of silica) and microbial DNA analysis. Though chemical analysis of groundwater shows an averaged value of the examined water which was blended by various water with different sources and routes in subsurface environment, microbial DNA analysis may suggest the place where they originated, which may give information of the source and transport routes of the water examined. Throughout the in situ observation of four rainfall events showed that stable oxygen isotopic ratio of spring water and shallow groundwater obtained from 726m a.s.l. where the average recharge height of rainfall was between 1500 and 1800 m became higher than the values before a torrential rainfall, and the concentration of silica decreased after this event when rainfall exceeded 300 mm in precipitation of an event. In addition, the density of Prokaryotes in spring water apparently increased. Those changes did not appear when rainfall did not exceed 100 mm per event. Thus, findings shown above indicated a direct impact of rainfall into shallow groundwater, which appeared within a few weeks of torrential rainfall in the studied geological setting. In addition, increase in the density of Archaea observed at deep groundwater after the torrential rainfall suggested an enlargement of the strength of piston flow transport through the penetration of rainfall into deep groundwater. This finding was

Isotope characterization of shallow aquifers in the Horombe region, South of Madagascar

International Nuclear Information System (INIS)

Fareze, L.P.; Rajaobelison, J.; Ramaroson, V.; Raoelina Andriambololona; Andriamiarintsoa, G.; Razafitsalama, P.R.; Rahobisoa, J.J.; Randrianarison, H.; Ranaivoarisoa, A.; Marah, H.

2011-01-01

The present study deals with the problem of evaluation of the recharge mechanism and the characterization of the groundwater flow system in the basement shallow aquifer, which is one of the groundwater resource in the semi-arid South region of Madagascar. Stable isotopes (deuterium and oxygen-18) and tritium are used to achieve with accuracy the hydrogeological and geochemical dynamics study. Chemical analysis is used to provide complementary information to the investigation. A space distribution of tritium concentration and isotopic composition in groundwater shows evidence of two opposite categories of aquifers, which is confirmed by the chemical analysis results and by the geological features of the study site. Some groundwater flow path directions have been identified in the study area thanks to the tritium concentration space distribution and the geological formation. Besides, the groundwater recharge of the shallow aquifers in the South of Madagascar has been characterized by the exponential mixing model.

Field scale interaction and nutrient exchange between surface water and shallow groundwater in the Baiyang Lake region, North China Plain

DEFF Research Database (Denmark)

Brauns, Bentje; Bjerg, Poul Løgstrup; Song, Xianfang

2016-01-01

in Hebei Province, China, was undertaken. The study showed a high influence of low-quality surface water on the shallow aquifer. Major inflowing pollutants into the aquifer were ammonium and nitrate via inflow from the adjacent Fu River (up to 29.8mg/L NH4-N and 6.8mg/L NO3-N), as well as nitrate via...... vertical transport from the field surface (up to 134.8mg/L NO3-N in soil water). Results from a conceptual model show an excess nitrogen input of about 320kg/ha/a. Nevertheless, both nitrogen species were only detected at low concentrations in shallow groundwater, averaging at 3.6mg/L NH4-N and 1.8mg/L NO3......-N. Measurement results supported by PHREEQC-modeling indicated cation exchange, denitrification, and anaerobic ammonium oxidation coupled with partial denitrification as major nitrogen removal pathways. Despite the current removal capacity, the excessive nitrogen fertilization may pose a future...

Groundwater flow in a closed basin with a saline shallow lake in a volcanic area: Laguna Tuyajto, northern Chilean Altiplano of the Andes

Energy Technology Data Exchange (ETDEWEB)

Herrera, Christian, E-mail: cherrera@ucn.cl [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Custodio, Emilio [Department of Geo-Engineering, Technical University of Catalonia/Barcelona Tech (UPC), Barcelona (Spain); Chong, Guillermo [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Lambán, Luis Javier [Geological Institute of Spain (IGME), Zaragoza (Spain); Riquelme, Rodrigo; Wilke, Hans [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Jódar, Jorge [Department of Geo-Engineering, Technical University of Catalonia/Barcelona Tech (UPC), Barcelona (Spain); Urrutia, Javier; Urqueta, Harry [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); Sarmiento, Alvaro [Departamento de Ciencias Geológicas, Universidad Católica del Norte, Casilla 1280, Antofagasta (Chile); and others

2016-01-15

Laguna Tuyajto is a small, shallow saline water lake in the Andean Altiplano of northern Chile. In the eastern side it is fed by springs that discharge groundwater of the nearby volcanic aquifers. The area is arid: rainfall does not exceed 200 mm/year in the rainiest parts. The stable isotopic content of spring water shows that the recharge is originated mainly from winter rain, snow melt, and to a lesser extent from some short and intense sporadic rainfall events. Most of the spring water outflowing in the northern side of Laguna Tuyajto is recharged in the Tuyajto volcano. Most of the spring water in the eastern side and groundwater are recharged at higher elevations, in the rims of the nearby endorheic basins of Pampa Colorada and Pampa Las Tecas to the East. The presence of tritium in some deep wells in Pampa Colorada and Pampa Las Tecas indicates recent recharge. Gas emission in recent volcanoes increase the sulfate content of atmospheric deposition and this is reflected in local groundwater. The chemical composition and concentration of spring waters are the result of meteoric water evapo-concentration, water–rock interaction, and mainly the dissolution of old and buried evaporitic deposits. Groundwater flow is mostly shallow due to a low permeability ignimbrite layer of regional extent, which also hinders brine spreading below and around the lake. High deep temperatures near the recent Tuyajto volcano explain the high dissolved silica contents and the δ{sup 18}O shift to heavier values found in some of the spring waters. Laguna Tuyajto is a terminal lake where salts cumulate, mostly halite, but some brine transfer to the Salar de Aguas Calientes-3 cannot be excluded. The hydrogeological behavior of Laguna Tuyajto constitutes a model to understand the functioning of many other similar basins in other areas in the Andean Altiplano. - Highlights: • Recent volcanism formations play a key role in producing recharge. • Groundwater can flow across local

Groundwater flow in a closed basin with a saline shallow lake in a volcanic area: Laguna Tuyajto, northern Chilean Altiplano of the Andes

International Nuclear Information System (INIS)

Herrera, Christian; Custodio, Emilio; Chong, Guillermo; Lambán, Luis Javier; Riquelme, Rodrigo; Wilke, Hans; Jódar, Jorge; Urrutia, Javier; Urqueta, Harry; Sarmiento, Alvaro

2016-01-01

Laguna Tuyajto is a small, shallow saline water lake in the Andean Altiplano of northern Chile. In the eastern side it is fed by springs that discharge groundwater of the nearby volcanic aquifers. The area is arid: rainfall does not exceed 200 mm/year in the rainiest parts. The stable isotopic content of spring water shows that the recharge is originated mainly from winter rain, snow melt, and to a lesser extent from some short and intense sporadic rainfall events. Most of the spring water outflowing in the northern side of Laguna Tuyajto is recharged in the Tuyajto volcano. Most of the spring water in the eastern side and groundwater are recharged at higher elevations, in the rims of the nearby endorheic basins of Pampa Colorada and Pampa Las Tecas to the East. The presence of tritium in some deep wells in Pampa Colorada and Pampa Las Tecas indicates recent recharge. Gas emission in recent volcanoes increase the sulfate content of atmospheric deposition and this is reflected in local groundwater. The chemical composition and concentration of spring waters are the result of meteoric water evapo-concentration, water–rock interaction, and mainly the dissolution of old and buried evaporitic deposits. Groundwater flow is mostly shallow due to a low permeability ignimbrite layer of regional extent, which also hinders brine spreading below and around the lake. High deep temperatures near the recent Tuyajto volcano explain the high dissolved silica contents and the δ"1"8O shift to heavier values found in some of the spring waters. Laguna Tuyajto is a terminal lake where salts cumulate, mostly halite, but some brine transfer to the Salar de Aguas Calientes-3 cannot be excluded. The hydrogeological behavior of Laguna Tuyajto constitutes a model to understand the functioning of many other similar basins in other areas in the Andean Altiplano. - Highlights: • Recent volcanism formations play a key role in producing recharge. • Groundwater can flow across local

The short-term effects of management changes on watertable position and nutrients in shallow groundwater in a harvested peatland forest.

Science.gov (United States)

Finnegan, J; Regan, J T; Fenton, O; Lanigan, G J; Brennan, R B; Healy, M G

2014-09-01

Management changes such as drainage, fertilisation, afforestation and harvesting (clearfelling) of forested peatlands influence watertable (WT) position and groundwater concentrations of nutrients. This study investigated the impact of clearfelling of a peatland forest on WT and nutrient concentrations. Three areas were examined: (1) a regenerated riparian peatland buffer (RB) clearfelled four years prior to the present study (2) a recently clearfelled coniferous forest (CF) and (3) a standing, mature coniferous forest (SF), on which no harvesting took place. The WT remained consistently below 0.3 m during the pre-clearfelling period. Results showed there was an almost immediate rise in the WT after clearfelling and a rise to 0.15 m below ground level (bgl) within 10 months of clearfelling. Clearfelling of the forest increased dissolved reactive phosphorus concentrations (from an average of 28-230 μg L(-1)) in the shallow groundwater, likely caused by leaching from degrading brash mats. Copyright © 2014 Elsevier Ltd. All rights reserved.

Arsenic release from shallow aquifers of the Hetao basin, Inner Mongolia: evidence from bacterial community in aquifer sediments and groundwater.

Science.gov (United States)

Li, Yuan; Guo, Huaming; Hao, Chunbo

2014-12-01

Indigenous microbes play crucial roles in arsenic mobilization in high arsenic groundwater systems. Databases concerning the presence and the activity of microbial communities are very useful in evaluating the potential of microbe-mediated arsenic mobilization in shallow aquifers hosting high arsenic groundwater. This study characterized microbial communities in groundwaters at different depths with different arsenic concentrations by DGGE and one sediment by 16S rRNA gene clone library, and evaluated arsenic mobilization in microcosm batches with the presence of indigenous bacteria. DGGE fingerprints revealed that the community structure changed substantially with depth at the same location. It indicated that a relatively higher bacterial diversity was present in the groundwater sample with lower arsenic concentration. Sequence analysis of 16S rRNA gene demonstrated that the sediment bacteria mainly belonged to Pseudomonas, Dietzia and Rhodococcus, which have been widely found in aquifer systems. Additionally, NO3(-)-reducing bacteria Pseudomonas sp. was the largest group, followed by Fe(III)-reducing, SO4(2-)-reducing and As(V)-reducing bacteria in the sediment sample. These anaerobic bacteria used the specific oxyanions as electron acceptor and played a significant role in reductive dissolution of Fe oxide minerals, reduction of As(V), and release of arsenic from sediments into groundwater. Microcosm experiments, using intact aquifer sediments, showed that arsenic release and Fe(III) reduction were microbially mediated in the presence of indigenous bacteria. High arsenic concentration was also observed in the batch without amendment of organic carbon, demonstrating that the natural organic matter in sediments was the potential electron donor for microbially mediated arsenic release from these aquifer sediments.

Recharge sources and residence times of groundwater as determined by geochemical tracers in the Mayfield Area, southwestern Idaho, 2011–12

Science.gov (United States)

Hopkins, Candice B.

2013-01-01

Parties proposing residential development in the area of Mayfield, Idaho are seeking a sustainable groundwater supply. During 2011–12, the U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources, used geochemical tracers in the Mayfield area to evaluate sources of aquifer recharge and differences in groundwater residence time. Fourteen groundwater wells and one surface-water site were sampled for major ion chemistry, metals, stable isotopes, and age tracers; data collected from this study were used to evaluate the sources of groundwater recharge and groundwater residence times in the area. Major ion chemistry varied along a flow path between deeper wells, suggesting an upgradient source of dilute water, and a downgradient source of more concentrated water with the geochemical signature of the Idaho Batholith. Samples from shallow wells had elevated nutrient concentrations, a more positive oxygen-18 signature, and younger carbon-14 dates than deep wells, suggesting that recharge comes from young precipitation and surface-water infiltration. Samples from deep wells generally had higher concentrations of metals typical of geothermal waters, a more negative oxygen-18 signature, and older carbon-14 values than samples from shallow wells, suggesting that recharge comes from both infiltration of meteoric water and another source. The chemistry of groundwater sampled from deep wells is somewhat similar to the chemistry in geothermal waters, suggesting that geothermal water may be a source of recharge to this aquifer. Results of NETPATH mixing models suggest that geothermal water composes 1–23 percent of water in deep wells. Chlorofluorocarbons were detected in every sample, which indicates that all groundwater samples contain at least a component of young recharge, and that groundwater is derived from multiple recharge sources. Conclusions from this study can be used to further refine conceptual hydrological models of the area.

Groundwater Recharge Assessment in a Remote Region of Colombia Through Citizen Science

Science.gov (United States)

Gomez, A. M.; Wise, E.; Riveros-Iregui, D.

2017-12-01

Understanding water dynamic and storage is essential for decision making in hydrology issues. In remote groundwater-dependent regions affected by population displacement and land over exploitation, especially in developing economies, limited data hinders the production of information necessary to formulate and implement effective water management plans. The community science research approach, which seeks to solve scientific questions with the participation of the community at various levels, represents an opportunity in these regions. We present results of a citizen science project developed to improve the conceptualization of groundwater flow path and to estimate the monthly direct recharge to the shallow aquifer in a remote rural region, the Man River watershed, located in one of the last foothills between the Western and Central Andes cordillera in Colombia. This project was conducted by: i) implementing a water level monitoring network aided by the community to collect weekly data from 2007 to 2010; ii) comparing the precipitation data and water table time series to identify the response of the shallow aquifer to the wet season; iii) conceptualizing specific groundwater-surface interactions through water table spatial analysis; and iv) estimating direct groundwater recharge using the Water Table Fluctuation method. Water quality test results were shared with the local community. Results show that groundwater interacts with the main tributaries to the Man River. Two scenarios were identified related to water table temporal behavior: (1) the water table rises during the transition from the dry to the wet season (between March and April), and (2) it increases one month after this transition. In general, groundwater levels descend in November, which is the end of the wet season. The work with the community provided useful insights for interpreting the collected data and allowed for information exchange concerning the groundwater quality and methods for improving

Water-level changes and directions of ground-water flow in the shallow aquifer, Fallon area, Churchill County, Nevada

Science.gov (United States)

Seiler, R.L.; Allander, K.K.

1993-01-01

The Truckee-Carson-Pyramid Lake Water Rights Settlement Act of 1990 directed the U.S. Fish and Wildlife Service to acquire water rights for wetland areas in the Carson Desert, Nevada. The public is concerned that htis acquisition of water rights and delivery of the water directly to wildlife areas would result in less recharge to the shallow ground water in the Fallon area and cause domestic wells to go dry. In January 1992, the U.S. Geological Survey, in cooperation with U.S. Fish and Wildlife Service, began a study of the shallow ground-water system in the Fallon area in Churchill County, Nevada. A network of 126 wells in the study area was monitored. Between January and November 1992, water levels in most wells declined, usually less than 2 feet. The maximum measured decline over this period was 2.68 feet in a well near Stillwater Marsh. Between April and July, however, water levels rose in irrigated areas, typically 1 to 2 feet. Newlands Project water deliveries to the study area began soon after the turn of the century. Since then, water levels have risen more than 15 feet across much of the study area. Water lost from unlined irrigtiaon canals caused the stage in Big Soda Lake to rise nearly 60 feet; ground-water levels near the lake have risen 30 to 40 feet. The depth to water in most irrigated areas is now less than 10 feet. The altitude of the water table ranges from 4.025 feet above sea level 11 miles west of Fallon to 3,865 feet in the Stillwater Marsh area. Ground water flows eastward and divides; some flow goes to the northeast toward the Carson Sink and Stillwater areas, and some goes southeastward to Carson Lake.

Groundwater flow in a closed basin with a saline shallow lake in a volcanic area: Laguna Tuyajto, northern Chilean Altiplano of the Andes.

Science.gov (United States)

Herrera, Christian; Custodio, Emilio; Chong, Guillermo; Lambán, Luis Javier; Riquelme, Rodrigo; Wilke, Hans; Jódar, Jorge; Urrutia, Javier; Urqueta, Harry; Sarmiento, Alvaro; Gamboa, Carolina; Lictevout, Elisabeth

2016-01-15

Laguna Tuyajto is a small, shallow saline water lake in the Andean Altiplano of northern Chile. In the eastern side it is fed by springs that discharge groundwater of the nearby volcanic aquifers. The area is arid: rainfall does not exceed 200mm/year in the rainiest parts. The stable isotopic content of spring water shows that the recharge is originated mainly from winter rain, snow melt, and to a lesser extent from some short and intense sporadic rainfall events. Most of the spring water outflowing in the northern side of Laguna Tuyajto is recharged in the Tuyajto volcano. Most of the spring water in the eastern side and groundwater are recharged at higher elevations, in the rims of the nearby endorheic basins of Pampa Colorada and Pampa Las Tecas to the East. The presence of tritium in some deep wells in Pampa Colorada and Pampa Las Tecas indicates recent recharge. Gas emission in recent volcanoes increase the sulfate content of atmospheric deposition and this is reflected in local groundwater. The chemical composition and concentration of spring waters are the result of meteoric water evapo-concentration, water-rock interaction, and mainly the dissolution of old and buried evaporitic deposits. Groundwater flow is mostly shallow due to a low permeability ignimbrite layer of regional extent, which also hinders brine spreading below and around the lake. High deep temperatures near the recent Tuyajto volcano explain the high dissolved silica contents and the δ(18)O shift to heavier values found in some of the spring waters. Laguna Tuyajto is a terminal lake where salts cumulate, mostly halite, but some brine transfer to the Salar de Aguas Calientes-3 cannot be excluded. The hydrogeological behavior of Laguna Tuyajto constitutes a model to understand the functioning of many other similar basins in other areas in the Andean Altiplano. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrogeological and biogeochemical constrains of arsenic mobilization in shallow aquifers from the Hetao basin, Inner Mongolia

International Nuclear Information System (INIS)

Guo Huaming; Zhang Bo; Li Yuan; Berner, Zsolt; Tang Xiaohui; Norra, Stefan; Stueben, Doris

2011-01-01

Little is known about the importance of drainage/irrigation channels and biogeochemical processes in arsenic distribution of shallow groundwaters from the Hetao basin. This investigation shows that although As concentrations are primarily dependent on reducing conditions, evaporation increases As concentration in the centre of palaeo-lake sedimentation. Near drainage channels, groundwater As concentrations are the lowest in suboxic-weakly reducing conditions. Results demonstrate that both drainage and irrigation channels produce oxygen-rich water that recharges shallow groundwaters and therefore immobilize As. Groundwater As concentration increases with a progressive decrease in redox potential along the flow path in an alluvial fan. A negative correlation between SO 4 2- concentrations and δ 34 S values indicates that bacterial reduction of SO 4 2- occurs in reducing aquifers. Due to high concentrations of Fe (>0.5 mg L -1 ), reductive dissolution of Fe oxides is believed to cause As release from aquifer sediments. Target aquifers for safe drinking water resources are available in alluvial fans and near irrigation channels. - Research highlights: → Low As groundwaters occur in alluvial fans. → We find low As groundwaters near irrigation and drainage channels. → Both hydrogeologic conditions and biogeochemical processes control As distribution. - Both hydrogeologic conditions and biogeochemical processes control As distribution of shallow groundwaters, which results in the occurrence of low As groundwater in alluvial fans and near irrigation channels and drainage channels.

Groundwater Recharge Process in the Morondava Sedimentary Basin, Southwestern Madagascar

International Nuclear Information System (INIS)

Mamifarananahary, E.; Rajaobelison, J.; Ramaroson, V.; Rahobisoa, J.J.

2007-01-01

The groundwater recharge process in the Morondava Sedimentary basin was determined using chemical and isotopic tools. The results showed that the main recharge into shallow aquifer is from infiltration of evaporated water. Into deeper aquifer, it is done either from direct infiltration of rainfall from recharge areas on the top of the hill in the East towards the low-lying discharge areas in the West, or from vertical infiltration of evaporated shallow groundwater. The tritium contents suggest that recharge from shallow aquifers is from recent rainfall with short residence time while recharge into deeper aquifers is from older rainfall with longer residence time.

The characteristics of hydrogeochemical zonation of groundwater in inland plain

Science.gov (United States)

Xin-yu, HOU; Li-ting, XING; Yi, YANG; Wen-jing, ZHANG; Guang-yao, CHI

2018-05-01

To find out the hydrochemical zoning of groundwaterin the inland plain, taking Jiyang plain as an example, based on mathematical statistics, ion ratio coefficient and isotopic analysis method, the characteristics of water chemical composition and its zoning at different depths of 500m were studied. The result shows: ①The groundwater flow system in the study area can be divided into local flow system, intermediate flow system and regional flow system. ②The hydrochemical type of shallow groundwater is complex. The hydrochemical types of middle confined water are mainly ClṡSO4—MgṡNa and SO4ṡCl—NaṡMg. The deep confined water is mainly HCO3. ③The TDS of shallow groundwater increases gradually along the direction of groundwater flow. ④The shallow saltwater and freshwater are alternately distributed in horizontal direction, and saltwater is distributed sporadically in the interfluve area with sporadic punctate or banded, and hydrochemical types are mainly ClṡSO4—NaṡMgṡCa. Conclusion: Groundwater in the study area is affected by complicated hydrogeochemical action, mainly in the form of filtration, cation exchange and evaporation. The inland plain area is characterized by hydrogeochemical zonation in horizontal and vertical.

Investigation of Geochemical Characteristics and Controlling Processes of Groundwater in a Typical Long-Term Reclaimed Water Use Area

Directory of Open Access Journals (Sweden)

Yong Xiao

2017-10-01

Full Text Available The usage of reclaimed water can efficiently mitigate water crises, but it may cause groundwater pollution. To clearly understand the potential influences of long-term reclaimed water usage, a total of 91 samples of shallow and deep groundwater were collected from a typical reclaimed water use area during the dry and rainy seasons. The results suggest both shallow and deep groundwater are mainly naturally alkaline freshwater, which are composed mainly of Ca-HCO3, followed by mixed types such as Ca-Na-HCO3 and Ca-Mg-HCO3. A seasonal desalination trend was observed in both shallow and deep aquifers due to dilution effects in the rainy season. Groundwater chemical compositions in both shallow and deep aquifers are still dominantly controlled by natural processes such as silicate weathering, minerals dissolution and cation exchange. Human activities are also the factors influencing groundwater chemistry. Urbanization has been found responsible for the deterioration of groundwater quality, especially in shallow aquifers, because of the relative thin aquitard. Reclaimed water usage for agricultural irrigation and landscape purposes has nearly no influences on groundwater quality in rural areas due to thick aquitards. Therefore, reclaimed water usage should be encouraged in arid and semiarid areas with proper hydrogeological condition.

Mixing of shallow and deep groundwater as indicated by the chemistry and age of karstic springs

Science.gov (United States)

Toth, David J.; Katz, Brian G.

2006-06-01

Large karstic springs in east-central Florida, USA were studied using multi-tracer and geochemical modeling techniques to better understand groundwater flow paths and mixing of shallow and deep groundwater. Spring water types included Ca-HCO3 (six), Na-Cl (four), and mixed (one). The evolution of water chemistry for Ca-HCO3 spring waters was modeled by reactions of rainwater with soil organic matter, calcite, and dolomite under oxic conditions. The Na-Cl and mixed-type springs were modeled by reactions of either rainwater or Upper Floridan aquifer water with soil organic matter, calcite, and dolomite under oxic conditions and mixed with varying proportions of saline Lower Floridan aquifer water, which represented 4-53% of the total spring discharge. Multiple-tracer data—chlorofluorocarbon CFC-113, tritium (3H), helium-3 (3Hetrit), sulfur hexafluoride (SF6)—for four Ca-HCO3 spring waters were consistent with binary mixing curves representing water recharged during 1980 or 1990 mixing with an older (recharged before 1940) tracer-free component. Young-water mixing fractions ranged from 0.3 to 0.7. Tracer concentration data for two Na-Cl spring waters appear to be consistent with binary mixtures of 1990 water with older water recharged in 1965 or 1975. Nitrate-N concentrations are inversely related to apparent ages of spring waters, which indicated that elevated nitrate-N concentrations were likely contributed from recent recharge.

Pharmaceutical compounds in shallow groundwater in non-agricultural areas of Minnesota: study design, methods, and data, 2013

Science.gov (United States)

Elliott, Sarah M.; Erickson, Melinda L.

2014-01-01

The U.S. Geological Survey, in cooperation with the Minnesota Pollution Control Agency, completed a study on the occurrence of pharmaceutical compounds and other contaminants of emerging concern in shallow groundwater in non-agricultural areas of Minnesota during 2013. This report describes the study design and methods for the study on the occurrence of pharmaceuticals and other contaminants of emerging concern, and presents the data collected on pharmaceutical compounds. Samples were analyzed by the U.S. Geological Survey National Water Quality Laboratory for 110 pharmaceutical compounds using research method 9017. Samples from 21 of 45 wells had detectable concentrations of at least one of the 110 compounds analyzed. One sample contained detectable concentrations of nine compounds, which was the most detected in a single sample. Fewer than five compounds were detected in most samples. Among all samples, 27 of the 110 compounds were detected in groundwater from at least one well. Desmethyldiltiazem and nicotine were the most frequently detected compounds, each detected in 5 of 46 environmental samples (one well was sampled twice so a total of 46 environmental samples were collected from 45 wells). Caffeine had the highest detectable concentration of all the compounds at 2,060 nanograms per liter.

Vulnerability of deep groundwater in the Bengal Aquifer System to contamination by arsenic

Science.gov (United States)

Burgess, W.G.; Hoque, M.A.; Michael, H.A.; Voss, C.I.; Breit, G.N.; Ahmed, K.M.

2010-01-01

Shallow groundwater, the primary water source in the Bengal Basin, contains up to 100 times the World Health Organization (WHO) drinking-water guideline of 10g l 1 arsenic (As), threatening the health of 70 million people. Groundwater from a depth greater than 150m, which almost uniformly meets the WHO guideline, has become the preferred alternative source. The vulnerability of deep wells to contamination by As is governed by the geometry of induced groundwater flow paths and the geochemical conditions encountered between the shallow and deep regions of the aquifer. Stratification of flow separates deep groundwater from shallow sources of As in some areas. Oxidized sediments also protect deep groundwater through the ability of ferric oxyhydroxides to adsorb As. Basin-scale groundwater flow modelling suggests that, over large regions, deep hand-pumped wells for domestic supply may be secure against As invasion for hundreds of years. By contrast, widespread deep irrigation pumping might effectively eliminate deep groundwater as an As-free resource within decades. Finer-scale models, incorporating spatial heterogeneity, are needed to investigate the security of deep municipal abstraction at specific urban locations. ?? 2010 Macmillan Publishers Limited. All rights reserved.

Multivariate autoregressive modelling and conditional simulation of precipitation time series for urban water models

NARCIS (Netherlands)

Torres-Matallana, J.A.; Leopold, U.; Heuvelink, G.B.M.

2017-01-01

Precipitation is the most active flux and major input of hydrological systems. Precipitation controls hydrological states (soil moisture and groundwater level), and fluxes (runoff, evapotranspiration and groundwater recharge).
Hence, precipitation plays a paramount role in urban water systems.

Groundwater suppression and diversion structures applied to closed shallow land burial trenches

International Nuclear Information System (INIS)

Davis, E.C.; Melroy, L.A.; Huff, D.D.

1984-01-01

Shallow depth to groundwater, surface drainage, and subsurface flow during storm events are major environmental concerns of low-level radioactive waste management operations in humid regions. At two waste disposal sites within the Oak Ridge National Laboratory (ORNL), groups of closed trenches have experienced these problems and have been shown to collect and hold intratrench water with seasonal fluctuations ranging from 1 to 2 m. In an attempt to correct these water-related problems, Solid Waste Storage Area Four (SWSA-4) was equipped in September 1975 with asphalt-lined drainage ways designed to prevent reinfiltration of storm drainage from the 13.8 ha upslope catchment. At 49-Trench Area of SWSA-6 the entire 0.44 ha trench area was capped with a bentonite clay cover in 1976. These early attempts at hydrologic isolation have not corrected the water problems. In September 1983, two similarly designed engineered drainage projects were initiated at the disposal sites. The SWSA-4 project was designed to divert surface runoff around the trench area and drain a portion of the shallow subsurface flow which originates upslope of the site. The second project, a passive French drain constructed in SWSA-6, was aimed strictly at suppressing the site water table thus preventing its intersection with the bottoms of disposal trenches. Post-construction monitoring for performance evaluation has shown that the water table in the 49-trench area has been suppressed to a depth >4.9 m below the ground surface over 50% of the site with a maximum drawdown of 4 m at the drains deepest point. The SWSA-4 project evaluation is just being completed and data show that 56 +/- 15% of the Winter-Spring 1984 runoff was diverted around SWSA 4. As a result, a 44% reduction in 90 Sr flux was calculated from observed discharges and a previously established relation between flow rate and 90 Sr concentration

The distribution of methane in groundwater in Alberta (Canada) and associated aqueous geochemistry conditions

Science.gov (United States)

Humez, Pauline; Mayer, Bernhard; Nightingale, Michael; Becker, Veith; Kingston, Andrew; Taylor, Stephen; Millot, Romain; Kloppmann, Wolfram

2016-04-01

Development of unconventional energy resources such as shale gas and coalbed methane has generated some public concern with regard to the protection of groundwater and surface water resources from leakage of stray gas from the deep subsurface. In terms of environmental impact to and risk assessment of shallow groundwater resources, the ultimate challenge is to distinguish: (a) natural in-situ production of biogenic methane, (b) biogenic or thermogenic methane migration into shallow aquifers due to natural causes, and (c) thermogenic methane migration from deep sources due to human activities associated with the exploitation of conventional or unconventional oil and gas resources. We have conducted a NSERC-ANR co-funded baseline study investigating the occurrence of methane in shallow groundwater of Alberta (Canada), a province with a long record of conventional and unconventional hydrocarbon exploration. Our objective was to assess the occurrence and sources of methane in shallow groundwaters and to also characterize the hydrochemical environment in which the methane was formed or transformed through redox processes. Ultimately our aim was to determine whether methane was formed in-situ or whether it migrated from deeper formations into shallow aquifers. Combining hydrochemical and dissolved and free geochemical gas data from 372 groundwater samples obtained from 186 monitoring wells of the provincial groundwater observation well network (GOWN) in Alberta, it was found that methane is ubiquitous in groundwater in Alberta and is predominantly of biogenic origin. The highest concentrations of dissolved biogenic methane (> 0.01 mM or > 0.2 mg/L), characterized by δ13CCH4 values deep thermogenic gas that had migrated in significant amounts into shallow aquifers either naturally or via anthropogenically induced pathways. This study shows that the combined interpretation of aqueous geochemistry data in concert with the chemical and isotopic composition of dissolved and

Contraction and Expansion of the Upper Zambezi Wetlands in Response to Precipitation Regime Changes and Impacts on Carbon, Energy and Water Fluxes

Science.gov (United States)

Lowman, L.; Barros, A. P.

2017-12-01

The Upper Zambezi River Basin (UZRB) serves as the headwater catchment of the fourth-largest river in Africa, provides essential freshwater resources to arid and semi-arid regions within its boundaries, and recharges the Northern Kalahari Aquifer. Shallow and clayey soils give way to seasonal waterlogging, especially along drainage lines, favoring the establishment of wetlands. Woodland savanna, grasslands and miombo dominate the UZRB's diverse ecosystem, marking a complex transition zone between the Congo tropical rainforest and the Kalahari Desert that reflects spatial rainfall gradients. Satellite imagery shows that permanent wetlands are located in low-lying convergence zones in the northeast and northwest corners of UZRB where surface-groundwater interactions are most vigorous. However, orographic precipitation gradients cannot fully explain interannual changes in wetland area and vegetation density. We hypothesize that changes in vegetation density result from nonlinear interactions and feedbacks among precipitation, canopy biophysical properties, soil moisture and groundwater processes modulated by topography and regional hydrogeology. This work aims to understand how changes in vegetation density, particularly in and around permanent and intermittent wetlands, impact carbon, energy and water fluxes. Using the MODIS Nadir BRDF-Adjusted Reflectance product, a seasonally-varying wetland class is derived that reflects inter-annual precipitation and groundwater variability. The Duke Coupled Hydrology Model with Prognostic Vegetation is adapted to include C4 photosynthesis for the UZRB grasslands and used to simulate changes in canopy density and impacts on gross primary productivity, evapotranspiration, and soil moisture at high spatial and temporal resolution. Initial results using the column-wise model provide a baseline for understanding surface fluxes before incorporating groundwater and subsurface flows crucial to investigating the implicit nonlinearities

Database dictionary for the results of groundwater tracer tests using tritiated water, conducted at the Oak Ridge National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Thompson, B.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Civil Engineering; Huff, D.D. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.

1997-05-01

In 1977, the United States Geological Survey (USGS) conducted two tracer tests at the Oak Ridge National Laboratory (ORNL) using tritiated water to study the relative importance of bedding-plane openings on shallow groundwater flow. Through a cooperative agreement between the USGS and the US Department of Energy (DOE), the data were made available to researchers at the Oak Ridge National Laboratory (ORNL), who organized the data into a data management format. The results of these groundwater tracer tests have been compiled into a collection of four SAS data sets. This report documents these SAS data sets, including their structure, methodology, and content. The SAS data sets include information on precipitation, tritium, water levels, and well construction for wells at or near ORNL radioactive waste burial grounds 4, 5, and 6.

A study on groundwater infiltration in the Horonobe area, northern Hokkaido, Japan

International Nuclear Information System (INIS)

Yokota, Hideharu; Yamamoto, Yoichi; Maekawa, Keisuke; Hara, Minoru

2011-01-01

In the Horonobe area of northern Hokkaido, the Japan Atomic Energy Agency has been carrying out various hydrological observations to estimate the recharge rate. Subsurface earth temperature and soil moisture content have been observed at HGW-1 site (GL-0.7m to GL-2.3m, since 2005) and Hokushin Meteorological Station (GL-0.1m to GL-1.1m, since 2008). The results have revealed groundwater infiltration and recharge occurring throughout year, the shallow groundwater-infiltration velocity depending on the depth and the position of the Zero Flux Plane. For the estimation of boundary conditions in groundwater flow simulation, in this study, the shallow groundwater-flow system has been examined qualitatively on the basis of the variation of the subsurface earth temperature and the soil moisture content. In the future, it is necessary to quantitatively assess the shallow groundwater infiltration and recharge rate, the intermediate runoff, and the evapotranspiration based on the observed data of the weighing lysimeter, and the other measurement stations in the area. (author)

Simulation and assessment of groundwater flow and groundwater and surface-water exchanges in lakes of the northeast Twin Cities Metropolitan Area, Minnesota, 2003 through 2013: Chapter B 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.; Roth, Jason L.; Trost, Jared J.; Christenson, Catherine A.; Diekoff, Aliesha L.; Erickson, Melinda L.

2017-09-05

Water levels during 2003 through 2013 were less than mean water levels for the period 1925–2013 for several lakes in the northeast Twin Cities Metropolitan Area in Minnesota. Previous periods of low lake-water levels generally were correlated with periods with less than mean precipitation. Increases in groundwater withdrawals and land-use changes have brought into question whether or not recent (2003–13) lake-water-level declines are solely caused by decreases in precipitation. A thorough understanding of groundwater and surface-water exchanges was needed to assess the effect of water-management decisions on lake-water levels. To address this need, the U.S. Geological Survey, in cooperation with the Metropolitan Council and the Minnesota Department of Health, developed and calibrated a three-dimensional, steady-state groundwater-flow model representing 2003–13 mean hydrologic conditions to assess groundwater and lake-water exchanges, and the effects of groundwater withdrawals and precipitation on water levels of 96 lakes in the northeast Twin Cities Metropolitan Area.Lake-water budgets for the calibrated groundwater-flow model indicated that groundwater is flowing into lakes in the northeast Twin Cities Metropolitan Area and lakes are providing water to underlying aquifers. Lake-water outflow to the simulated groundwater system was a major outflow component for Big Marine Lake, Lake Elmo, Snail Lake, and White Bear Lake, accounting for 45 to 64 percent of the total outflows from the lakes. Evaporation and transpiration from the lake surface ranged from 19 to 52 percent of the total outflow from the four lakes. Groundwater withdrawals and precipitation were varied from the 2003‒13 mean values used in the calibrated model (30-percent changes in groundwater withdrawals and 5-percent changes in precipitation) for hypothetical scenarios to assess the effects of groundwater withdrawals and precipitation on water budgets and levels in Big Marine Lake, Snail Lake

Human impact on regional groundwater composition through intervention in natural flow patterns and changes in land use

Science.gov (United States)

Schot, P. P.; van der Wal, J.

1992-06-01

The relations between groundwater composition, land use, soil conditions and flow patterns on a regional scale are studied for the Gooi and Vechtstreek area in the Netherlands. This densely populated area consists of a glacier-created ridge with dry sand soils bordered by the Vecht and Eem River plains with wet peat and clay soils. R-mode factor analysis and Q-mode cluster analysis were applied to a set of 1349 groundwater analyses to determine the factors controlling groundwater composition and the main resulting water types. The results indicate that groundwater composition in the study area is affected on a regional scale by human activities through changes in land use and intervention in natural flow patterns. On the ridge, ground water is recharged by precipitation, which dissolves carbonates from the matrix of the sandy aquifer. Increased solute concentrations in shallow ground water, especially of nitrate, sulphate and potassium, indicate increased pollution resulting from urbanization and increasingly intensive agricultural activity over the past decades. In the Vecht River plain infiltration occurs as a result of drainage of polders and groundwater extraction on the ridge. Recharge occurs by precipitation and from polluted surface water to which ammonium, organic complexes and carbonic acid are added through decomposition of organic matter in the peat and clay soils. The carbonic acid results in enhanced dissolution of carbonates present in the soil and the underlying sandy aquifer. Oxygen depletion and subsequent low redox potentials result in denitrification, dissolution of manganese and iron oxides, and sulphate reduction. The flow of ground water from high-level to low-level polders causes displacement of a former stagnant brakish groundwater body under the Vecht River plain accompanied by increased mixing of fresh and brackish ground water.

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.

Evaluation of effects of changes in canal management and precipitation patterns on salinity in Biscayne Bay, Florida, using an integrated surface-water/groundwater model

Science.gov (United States)

Lohmann, Melinda A.; Swain, Eric D.; Wang, John D.; Dixon, Joann

2012-01-01

Biscayne National Park, located in Biscayne Bay in southeast Florida, is one of the largest marine parks in the country and sustains a large natural marine fishery where numerous threatened and endangered species reproduce. In recent years, the bay has experienced hypersaline conditions (salinity greater than 35 practical salinity units) of increasing magnitude and duration. Hypersalinity events were particularly pronounced during April to August 2004 in nearshore areas along the southern and middle parts of the bay. Prolonged hypersaline conditions can cause degradation of water quality and permanent damage to, or loss of, brackish nursery habitats for multiple species of fish and crustaceans as well as damage to certain types of seagrasses that are not tolerant of extreme changes in salinity. To evaluate the factors that contribute to hypersalinity events and to test the effects of possible changes in precipitation patterns and canal flows into Biscayne Bay on salinity in the bay, the U.S. Geological Survey constructed a coupled surface-water/groundwater numerical flow model. The model is designed to account for freshwater flows into Biscayne Bay through the canal system, leakage of salty bay water into the underlying Biscayne aquifer, discharge of fresh and salty groundwater from the Biscayne aquifer into the bay, direct effects of precipitation on bay salinity, indirect effects of precipitation on recharge to the Biscayne aquifer, direct effects of evapotranspiration (ET) on bay salinity, indirect effects of ET on recharge to the Biscayne aquifer, and maintenance of mass balance of both water and solute. The model was constructed using the Flow and Transport in a Linked Overland/Aquifer Density Dependent System (FTLOADDS) simulator, version 3.3, which couples the two-dimensional, surface-water flow and solute-transport simulator SWIFT2D with the density-dependent, groundwater flow an solute-transport simulator SEAWAT. The model was calibrated by a trial

Potential effects of the Hawaii Geothermal Project on ground-water resources on the island of Hawaii

Science.gov (United States)

Sorey, M.L.; Colvard, E.M.

1994-01-01

In 1990, the State of Hawaii proposed the Hawaii Geothermal Project for the development of as much as 500 MW of electric power from the geothermal system in the East Rift Zone of Kilauea Volcano. This report uses data from 31 wells and 8 springs to describe the properties of the ground-water system in and adjacent to the East Rift Zone. Potential effects of this project on ground-water resources are also discussed. Data show differences in ground-water chemistry and heads within the study area that appear to be related to mixing of waters of different origins and ground-water impoundment by volcanic dikes. East of Pahoa, the ground-water system within the rift is highly transmissive and receives abundant recharge from precipitation; therefore, the pumping of freshwater to support geothermal development in that part of the rift zone would have a minimal effect on ground-water levels. To the southwest of Pahoa, dike impoundment reduces the transmissivity of the ground-water system to such an extent that wells might not be capable of supplying sufficient fresh water to support geothermal operations. Contamination of ground-water resources by accidental release of geothermal fluids into shallow aquifers is possible because of corrosive conditions in the geothermal wells, potential well blowouts, and high ground-water velocities in parts of the region. Hydrologic monitoring of water level, temperature, and chemistry in observation wells should continue throughout development of geothermal resources for the Hawaii Geothermal Project for early detection of leakage and migration of geothermal fluids within the groundwater system.

Shallow Groundwater Temperatures and the Urban Heat Island Effect: the First U.K City-wide Geothermal Map to Support Development of Ground Source Heating Systems Strategy

Science.gov (United States)

Patton, Ashley M.; Farr, Gareth J.; Boon, David P.; James, David R.; Williams, Bernard; Newell, Andrew J.

2015-04-01

The first UK city-wide heat map is described based on measurements of groundwater from a shallow superficial aquifer in the coastal city of Cardiff, Wales, UK. The UK Government has a target of reducing greenhouse gas emissions by 80% by 2050 (Climate Change Act 2008) and low carbon technologies are key to achieving this. To support the use of ground source heating we characterised the shallow heat potential of an urban aquifer to produce a baseline dataset which is intended to be used as a tool to inform developers and to underpin planning and regulation. We exploited an existing network of 168 groundwater monitoring boreholes across the city, recording the water temperature in each borehole at 1m depth intervals up to a depth of 20m. We recorded groundwater temperatures during the coldest part of 2014, and repeat profiling of the boreholes in different seasons has added a fourth dimension to our results and allowed us to characterise the maximum depth of seasonal temperature fluctuation. The temperature profiles were used to create a 3D model of heat potential within the aquifer using GOCAD® and the average borehole temperatures were contoured using Surfer® 10 to generate a 2D thermal resource map to support future assessment of urban Ground Source Heat Pumps prospectively. The average groundwater temperature in Cardiff was found to be above the average for England and Wales (11.3°C) with 90% of boreholes in excess of this figure by up to 4°C. The subsurface temperature profiles were also found to be higher than forecast by the predicted geothermal gradient for the area. Potential sources for heat include: conduction from buildings, basements and sub-surface infrastructure; insulation effects of the urban area and of the geology, and convection from leaking sewers. Other factors include recharge inhibition by drains, localised confinement and rock-water interaction in specific geology. It is likely to be a combination of multiple factors which we are hoping

A conceptual model for groundwater - surface water interactions in the Darling River Floodplain, N.S.W., Australia

Science.gov (United States)

Brodie, R. S.; Lawrie, K.; Somerville, P.; Hostetler, S.; Magee, J.; Tan, K. P.; Clarke, J.

2013-12-01

Multiple lines of evidence were used to develop a conceptual model for interaction between the Darling River and associated floodplain aquifers in western New South Wales, Australia. Hydrostratigraphy and groundwater salinities were mapped using airborne electromagnetics (AEM), validated by sonic-core drilling. The AEM was highly effective in mapping groundwater freshening due to river leakage in discrete zones along the river corridor. These fresh resources occurred in both the unconfined Quaternary aquifers and the underlying, largely semi-confined Pliocene aquifers. The AEM was also fundamental to mapping the Blanchetown Clay aquitard which separates these two aquifer systems. Major-ion chemistry highlighted a mixing signature between river waters and groundwaters in both the Quaternary and Pliocene aquifers. Stable isotope data indicates that recharge to the key Pliocene aquifers is episodic and linked to high-flow flood events rather than river leakage being continuous. This was also evident when groundwater chemistry was compared with river chemistry under different flow conditions. Mapping of borehole levels showed groundwater mounding near the river, emphasising the regional significance of losing river conditions for both aquifer systems. Critically, rapid and significant groundwater level responses were measured during large flood events. In the Pliocene aquifers, continuation of rising trends after the flood peak receded confirms that this is an actual recharge response rather than hydraulic loading. The flow dependency of river leakage can be explained by the presence of mud veneers and mineral precipitates along the Darling River channel bank when river flows are low. During low flow conditions these act as impediments to river leakage. During floods, high flow velocities scour these deposits, revealing lateral-accretion surfaces in the shallow scroll plain sediments. This scouring allows lateral bank recharge to the shallow aquifer. During flood

Microbiology of Olkiluoto Groundwater 2004 - 2006

International Nuclear Information System (INIS)

Pedersen, K.

2008-02-01

The microbiology of shallow and deep groundwater in Olkiluoto, Finland, was analysed for almost three years from 2004 to 2006. The extensive sampling and analysis programme produced a substantial database, including 60 analytical datasets on the microbiology of Olkiluoto groundwater, which is described and interpreted here. One part of this database comprises 39 complete analytical datasets on microbiology, chemistry, and dissolved gas composition assembled on four sampling campaigns from measurements from 16 shallow observation tubes and boreholes ranging in depth from 3.5 to 24.5 m. The second part of the database contains 21 datasets on microbiology and chemistry covering 13 deep boreholes ranging in depth from 35 to 450 m. In addition, the database contains 33 completed analyses of gas covering 14 deep boreholes ranging in depth from 40 to 742 m. Most of these analyses were completed before the onset of ONKALO construction, and the remaining samples were collected before ONKALO construction had extended below a depth of 100 m; therefore, this dataset captures the undisturbed conditions before the building of ONKALO. Shallow groundwater in Olkiluoto contained dissolved oxygen at approximately 10% or less of saturation. The presence of aerobic and anaerobic microorganisms, including methane-oxidizing bacteria, has been documented. The data confirm earlier suggested processes of oxygen reduction in the shallow part of the bedrock. These microbial processes reduce intruding oxygen in the shallow groundwater using dissolved organic carbon and methane as the main electron donors. Microbiological and geochemical data strongly suggest that the anaerobic microbial oxidation of methane (ANME) is active at a depth down to approximately 300 m in Olkiluoto, as has been suggested previously, based on interpretations of geochemical data. However, proof of the presence and activity of ANME microorganisms is needed before the existence of active ANME processes in Olkiluoto

Groundwater quality and hydrogeological characteristics of Malacca state in Malaysia

Directory of Open Access Journals (Sweden)

Shirazi Sharif Moniruzzaman

2015-03-01

Full Text Available Groundwater quality and aquifer productivity of Malacca catchment in Peninsular Malaysia are presented in this article. Pumping test data were collected from 210 shallow and 17 deep boreholes to get well inventory information. Data analysis confirmed that the aquifers consisting of schist, sand, limestone and volcanic rocks were the most productive aquifers for groundwater in Malacca state. GIS-based aquifer productivity map was generated based on bedrock and discharge capacity of the aquifers. Aquifer productivity map is classified into three classes, namely high, moderate and low based on discharge capacity. Groundwater potential of the study area is 35, 57 and 8% of low, moderate and high class respectively. Fifty two shallow and 14 deep aquifer groundwater samples were analyzed for water quality. In some cases, groundwater quality analysis indicated that the turbidity, total dissolved solids, iron, chloride and cadmium concentrations exceeded the limit of drinking water quality standards.

Arsenic Contamination in Groundwater of Bangladesh: Perspectives on Geochemical, Microbial and Anthropogenic Issues

Directory of Open Access Journals (Sweden)

Shafi M. Tareq

2011-11-01

Full Text Available A groundwater, sediment and soil chemistry and mineralogical study has been performed to investigate the sources and mobilization process of Arsenic (As in shallow aquifers of Bangladesh. The groundwater from the shallow aquifers is characterized by high concentrations of Arsenic (47.5–216.8 µg/L, iron (0.85–5.83 mg/L, and phosphate, along with high electrical conductivity (EC. The groundwater has both very low oxidation-reduction potential (Eh and dissolved oxygen (DO values indicating reducing conditions. By contrast, the deep aquifers and surface waters (pond, canal have very low concentrations of Arsenic ( < 6 µg/L, iron (0.12–0.39 mg/L, and phosphate along with a relatively low EC. Furthermore, the values of Eh and DO are high, indicating oxic to suboxic conditions. Arsenic is inversely correlated with Eh values in the upper aquifer, whereas no relationship in the deeper aquifer is observed. These results suggest that As mobilization is clearly linked to the development of reducing conditions. The clayey silt, enriched in Fe, Mn, Al oxides and organic matter, and deposited in the middle unit of shallow aquifers, contains moderately high concentrations of As, whereas the sediments of deep aquifers and silty mud surface soils from paddy fields and ponds contain a low content of As (Daudkandi area. Arsenic is strongly correlated with the concentrations of Fe, Mn and Al oxides in the core samples from the Daudkandi and Marua areas. Arsenic is present in the oxide phase of Fe and Mn, phyllosilicate minerals and in organic matter in sediments. This study suggests that adsorption or precipitation of As-rich Fe oxyhydroxide on the surface or inner sites of biotite might be responsible for As concentrations found in altered biotite minerals by Seddique et al. Microbially or geochemically mediated reductive dissolution of Fe oxyhydroxides is the main mechanism for As release. The reducing conditions are caused by respiratory decomposition of

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.

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.

Regression models for estimating concentrations of atrazine plus deethylatrazine in shallow groundwater in agricultural areas of the United States

Science.gov (United States)

Stackelberg, Paul E.; Barbash, Jack E.; Gilliom, Robert J.; Stone, Wesley W.; Wolock, David M.

2012-01-01

Tobit regression models were developed to predict the summed concentration of atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] and its degradate deethylatrazine [6-chloro-N-(1-methylethyl)-1,3,5,-triazine-2,4-diamine] (DEA) in shallow groundwater underlying agricultural settings across the conterminous United States. The models were developed from atrazine and DEA concentrations in samples from 1298 wells and explanatory variables that represent the source of atrazine and various aspects of the transport and fate of atrazine and DEA in the subsurface. One advantage of these newly developed models over previous national regression models is that they predict concentrations (rather than detection frequency), which can be compared with water quality benchmarks. Model results indicate that variability in the concentration of atrazine residues (atrazine plus DEA) in groundwater underlying agricultural areas is more strongly controlled by the history of atrazine use in relation to the timing of recharge (groundwater age) than by processes that control the dispersion, adsorption, or degradation of these compounds in the saturated zone. Current (1990s) atrazine use was found to be a weak explanatory variable, perhaps because it does not represent the use of atrazine at the time of recharge of the sampled groundwater and because the likelihood that these compounds will reach the water table is affected by other factors operating within the unsaturated zone, such as soil characteristics, artificial drainage, and water movement. Results show that only about 5% of agricultural areas have greater than a 10% probability of exceeding the USEPA maximum contaminant level of 3.0 μg L-1. These models are not developed for regulatory purposes but rather can be used to (i) identify areas of potential concern, (ii) provide conservative estimates of the concentrations of atrazine residues in deeper potential drinking water supplies, and (iii) set priorities

Quality of shallow groundwater and manure effluents in a livestock farm

Directory of Open Access Journals (Sweden)

Smoroń Sylwester

2016-06-01

Full Text Available The aim of the study was to assess the quality of shallow groundwater on the site pens and runoff from livestock manure heaps, in three selected farms involved in animal production and vegetable crops in the area of Plateau Proszowice. The analysis mainly included water from farm wells and effluents from manure. Additionally, water from drainage ditch running nearby farms was collected, before inflow of effluent (i.e. ditch water without manure effluent and below inflow of effluent from heap of manure (i.e. ditch water containing manure effluent. Samples of the research material were collected from April 2012 to March 2014 at monthly intervals and analysed for the content of NO3-N, NH4-N, PO4-P, K, Na and Cl. Based on the obtained results it was found that water from the farm wells near the livestock buildings and from manure storage sites, was heavily polluted by the majority of these contaminants. The highest concentration of these pollutants, except for the NO3-N, was found in manure effluent – it exceeded a few dozen to a few hundred to any standards for water quality. There was also a significant deterioration in the quality of drainage ditch water because of the penetration of contaminants into ditch water from heaps of improperly stored manure. The water of the farm wells was characterized by excessive concentrations of NO3-N which disqualified it for drinking purposes.

Environmental isotope-aided studies on river water and groundwater interaction in the region of Seoul and Taegu

International Nuclear Information System (INIS)

Jong Sung Ahn

1988-01-01

Environmental isotope-aided studies on river water and groundwater interaction in the Han River Basin in areas especially occupied by crystalline rocks and limestone have been undertaken. The result indicates that the groundwater in the Seoul area is recharged by the Han River whereas in non-urban areas it is replenished by the infiltration of precipitation, the crystalline rock aquifers are recharged by downward percolation of shallow groundwater stored in overlying alluvium. Older groundwater having a very low concentration of tritium, ranging from 0 to 2 TU, was observed at the lower Han River basin near Bupyeong. It may indicate that the water sampled was recharged at a much earlier time than the other groundwater sampled, maybe, as early as the pre-thermonuclear period. The same interaction study conducted in the Karst area has shown that there is clearly no systematic differences of tritium level between surface water and groundwater and that the residence time of groundwater in limestone is very short, probably not longer than a few months. The areas recharged by the water from the overlying alluvium into the sedimentary rock aquifer were restricted only along the Kumho River channel and its tributaries in a clastic sedimentary rock area. Bedrock groundwater whose tritium level and stable isotope composition were less than 14 TU and -6.8 respectively was observed in the central part of Taegu city. (author). 15 refs, 21 figs, 8 tabs

Use of environmental isotopes for studying human induced change in groundwater environment in Lahore, Pakistan

International Nuclear Information System (INIS)

Ahmad, M.; Akram, W.; Sajjad, M.I.; Rafiq, M.; Tasneem, Azam M.

2002-01-01

Lahore is the second biggest city of Pakistan where groundwater is the only source of drinking water supply for the city. On the other hand, the quality of groundwater is being degraded due to various human activities especially due to waste disposal practices. Untreated domestic and industrial wastes are discharged into open channels, drains, etc. which leads to surface water and groundwater pollution. This study was undertaken to assess the changes in groundwater environment due to such activities. Water samples were collected on periodical basis from existing handpumps, tube wells and drains and analyzed for isotopic ( 2 H, 3 H, 13 C, 18 O) and major dissolved ions. Samples having high nitrate were analyzed for 15 N. Selected samples were also analyzed for Coliform bacteria. Results of only selected parameters are discussed here. The data showed that quality of shallow groundwater has deteriorated at most of the locations and concentrations of several chemical parameters are higher than WHO permissible levels for drinking water. Comparison with a previous study carried out in 1991, indicated a clear increasing trend of total dissolved salts in groundwater. An outstanding feature of the data is the increasing trend of nitrate concentrations both in shallow and deep groundwater. Results of nitrate analysis indicate that concentrations vary from 10 to 188 mg/l in shallow groundwater and 9 to 41 mg/l in deep groundwater. Frequency histogram of nitrate concentrations is shown. Nitrates which were generally a few ppm have increased at almost all the surveyed locations and have even crossed the WHO limit of 45 mg/l at several shallow locations. High nitrate waters exist as isolated pockets. Results of tritium analysis indicated that shallow groundwater has generally high tritium values. Presence of more nitrate at shallow depths, occurrence of high nitrate waters as isolated pockets and high tritium in contaminated waters suggest that nitrates are derived from as

Mercury (II) reduction and co-precipitation of metallic mercury on hydrous ferric oxide in contaminated groundwater.

Science.gov (United States)

Richard, Jan-Helge; Bischoff, Cornelia; Ahrens, Christian G M; Biester, Harald

2016-01-01

Mercury (Hg) speciation and sorption analyses in contaminated aquifers are useful for understanding transformation, retention, and mobility of Hg in groundwater. In most aquifers hydrous ferric oxides (HFOs) are among the most important sorbents for trace metals; however, their role in sorption or mobilization of Hg in aquifers has been rarely analyzed. In this study, we investigated Hg chemistry and Hg sorption to HFO under changing redox conditions in a highly HgCl2-contaminated aquifer (up to 870μgL(-1) Hg). Results from aqueous and solid phase Hg measurements were compared to modeled (PHREEQC) data. Speciation analyses of dissolved mercury indicated that Hg(II) forms were reduced to Hg(0) under anoxic conditions, and adsorbed to or co-precipitated with HFO. Solid phase Hg thermo-desorption measurements revealed that between 55 and 93% of Hg bound to HFO was elemental Hg (Hg(0)). Hg concentrations in precipitates reached more than 4 weight %, up to 7000 times higher than predicted by geochemical models that do not consider unspecific sorption to and co-precipitation of elemental Hg with HFO. The observed process of Hg(II) reduction and Hg(0) formation, and its retention and co-precipitation by HFO is thought to be crucial in HgCl2-contaminated aquifers with variable redox-conditions regarding the related decrease in Hg solubility (factor of ~10(6)), and retention of Hg in the aquifer. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrochemical evaluation and identification of geochemical processes in the shallow and deep wells in the Ramganga Sub-Basin, India.

Science.gov (United States)

Rajmohan, Natarajan; Patel, Neelam; Singh, Gaurav; Amarasinghe, Upali A

2017-09-01

Groundwater samples were collected from 44 wells in the Ramganga Sub-Basin (RSB), India, and analysed for major ions, nutrients and trace metals. The primary goal of this study is to evaluate the hydrochemistry and to identify the geochemical processes that govern the water chemistry in the shallow and deep tube wells in the study area using geochemical methods. The knowledge of changes in hydrochemistry of the aquifers is important for both groundwater recharge and use in the region. This study found that there are substantial differences of water chemistry between shallow and deep wells. In the shallow wells, the average concentrations of total dissolved solid (TDS), Na, K, Ca, Mg, HCO 3 , Cl, SO 4 , NO 3 , PO 4 , F, Cu, Mn, Fe and Cr are twofold higher than the deep wells. The concentrations of dissolved silica in the groundwater do not vary with the depth, which implies that the variation in the water chemistry is not due to mineral dissolution alone. Major ion ratios and saturation indices suggest that the water chemistry is predominantly controlled by dissolution of carbonate minerals, silicate weathering and ion exchange reactions. Thermodynamic evaluation (ion activity ratios and stability filed diagrams) indicates that the kaolinite and gibbsite controlled the water chemistry in the both shallow and deep wells. In addition, the groundwater chemistry in the shallow wells is affected by the vertical infiltration of contaminated water from surface contamination sources and nitrification process. In the deep wells, absence of NO 3 and low concentrations of Cl, SO 4 , PO 4 and F imply the role of regional flow and denitrification in the groundwater. Results concluded that proper management plan is necessary to protect the shallow aquifer in the RSB since shallow aquifer pumping is less expensive than the deeper one.

Groundwater Ecosystems Vary with Land Use across a Mixed Agricultural Landscape.

Science.gov (United States)

Korbel, K L; Hancock, P J; Serov, P; Lim, R P; Hose, G C

2013-01-01

Changes in surface land use may threaten groundwater quality and ecosystem integrity, particularly in shallow aquifers where links between groundwater and surface activities are most intimate. In this study we examine the response of groundwater ecosystem to agricultural land uses in the shallow alluvial aquifer of the Gwydir River valley, New South Wales, Australia. We compared groundwater quality and microbial and stygofauna assemblages among sites under irrigated cropping, non-irrigated cropping and grazing land uses. Stygofauna abundance and richness was greatest at irrigated sites, with the composition of the assemblage suggestive of disturbance. Microbial assemblages and water quality also varied with land use. Our study demonstrates significant differences in the composition of groundwater ecosystems in areas with different surface land use, and highlights the utility of groundwater biota for biomonitoring, particularly in agricultural landscapes. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Nitrate pollution of shallow ground water in chaj doab

International Nuclear Information System (INIS)

Hussain, S. D.; Akram, W.; Ahmad, M.; Rafiq, M.

2000-01-01

Chaj Doab is an interfluvial tract of land bounded by the rivers Chenab and Jhelum. Agriculture is the main economic activity in the area. In order to increase crop production,. natural and industrial fertilizers are excessively used. Shallow groundwater is the main source of water for domestic and agricultural usage. Nitrate in the soil is carried to the groundwater by precolating water. Concentration of nitrate in groundwater which used to be less than 3 mg/l has crossed the WHO limit of 45 mg/l at several places principally due to the excessive use of fertilizers. In order to avoid serious consequences of nitrate pollution of groundwater, application of fertilizers will have to be judiciously practiced. (author)

Submarine groundwater discharge within a landslide scar at the French Mediterranean coast

NARCIS (Netherlands)

Oehler, Till; Mogollón, José M.; Moosdorf, Nils; Winkler, Andreas; Kopf, Achim; Pichler, Thomas

2017-01-01

Submarine groundwater discharge (SGD), the flow of fresh and saline groundwater from the seabed into the coastal ocean, has been intensively investigated in the recent years. This research has usually been restricted to shallow water and intertidal areas, whereas knowledge about groundwater seepage

Determining the extent of groundwater interference on the performance of infiltration trenches

OpenAIRE

Locatelli, Luca; Mark, Ole; Mikkelsen, Peter Steen; Arnbjerg-Nielsen, Karsten; Wong, Tony; Binning, Philip John

2015-01-01

Infiltration trenches are widely used in stormwater management, but their capacity decreases when installed in areas with shallow groundwater where infiltration is limited by groundwater drainage. Here the hydrological performance of single infiltration trenches in areas with shallow water tables is quantified in terms of their capability to reduce peak flow, peak volume and annual stormwater runoff volume. To simulate the long term hydrological performance of infiltration trenches two differ...

Erratum: Mixing of shallow and deep groundwater as indicated by the chemistry and age of karstic springs

Science.gov (United States)

Toth, David J.; Katz, Brian G.

2006-09-01

Large karstic springs in east-central Florida, USA were studied using multi-tracer and geochemical modeling techniques to better understand groundwater flow paths and mixing of shallow and deep groundwater. Spring water types included Ca-HCO3 (six), Na-Cl (four), and mixed (one). The evolution of water chemistry for Ca-HCO3 spring waters was modeled by reactions of rainwater with soil organic matter, calcite, and dolomite under oxic conditions. The Na-Cl and mixed-type springs were modeled by reactions of either rainwater or Upper Floridan aquifer water with soil organic matter, calcite, and dolomite under oxic conditions and mixed with varying proportions of saline Lower Floridan aquifer water, which represented 4-53% of the total spring discharge. Multiple-tracer data—chlorofluorocarbon CFC-113, tritium (3H), helium-3 (3Hetrit), sulfur hexafluoride (SF6)—for four Ca-HCO3 spring waters were consistent with binary mixing curves representing water recharged during 1980 or 1990 mixing with an older (recharged before 1940) tracer-free component. Young-water mixing fractions ranged from 0.3 to 0.7. Tracer concentration data for two Na-Cl spring waters appear to be consistent with binary mixtures of 1990 water with older water recharged in 1965 or 1975. Nitrate-N concentrations are inversely related to apparent ages of spring waters, which indicated that elevated nitrate-N concentrations were likely contributed from recent recharge.

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)

Effect of wheat-maize straw return on the fate of nitrate in groundwater in the Huaihe River Basin, China.

Science.gov (United States)

Li, Rongfu; Ruan, Xiaohong; Bai, Ying; Ma, Tianhai; Liu, Congqiang

2017-08-15

Straw return is becoming a routine practice in disposing of crop residues worldwide. However, the potential effect of such operation on the chemistry of local groundwater is not well documented. Here, shallow groundwater in an area where wheat-maize straw return is practiced was analyzed, and the seasonal changes in the nitrate concentration and the isotope compositions of NO 3 - and H 2 O were determined along two flow paths. Measured δD and δ 18 O in waters indicated that the groundwater was mainly recharged by atmospheric precipitation, while measured δ 15 N and δ 18 O in nitrate suggested that the sources for groundwater NO 3 - included urea fertilizer, soil nitrogen, and sewage/manure. Reduced NO 3 - concentrations coincided with an enrichment of organic matter in the groundwater of the straw return area, revealing an environmental condition that facilitates nitrate reduction, whereas increased δ 15 N-NO 3 - and δ 18 O-NO 3 - along the flow path suggested the occurrence of denitrification. Further analyses showed that, compared to the cases in the absence of straw return, as much as 80% and 90% of groundwater nitrate was removed in low and high water seasons in the straw return area, pointing to a potential positive effect of straw return to groundwater quality. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of Mg²⁺ on CaCO₃ precipitation during subsurface reactive transport in a homogeneous silicon-etched pore network

Energy Technology Data Exchange (ETDEWEB)

Boyd, Victoria [Univ. of Illinois, Urbana-Champaign, IL (United States); Yoon, Hongkyu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zhang, Changyong [Exxon Mobil Upstream Research Company, Houston, TX (United States); Oostrom, Martinus [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hess, Nancy J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fouke, Bruce W. [Univ. of Illinois, Urbana-Champaign, IL (United States); Valocchi, Albert J. [Univ. of Illinois, Urbana-Champaign, IL (United States); Werth, Charles J. [Univ. of Illinois, Urbana-Champaign, IL (United States)

2014-04-04

Calcium carbonate (CaCO₃) geochemical reactions exert a fundamental control on the evolution of porosity and permeability in shallow-to-deep subsurface siliciclastic and limestone rock reservoirs. As a result, these carbonate water-rock interactions play a critically important role in research on groundwater remediation, geological carbon sequestration, and hydrocarbon exploration. A study was undertaken to determine the effects of Mg²⁺ concentration on CaCO₃ crystal morphology, precipitation rate, and porosity occlusion under flow and mixing conditions similar to those in subsurface aquifers.

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)

Assessing the influence of groundwater and land surface scheme in the modelling of land surface-atmosphere feedbacks over the FIFE area in Kansas, USA

DEFF Research Database (Denmark)

Larsen, Morten Andreas Dahl; Højmark Rasmussen, Søren; Drews, Martin

2016-01-01

The land surface-atmosphere interaction is described differently in large scale surface schemes of regional climate models and small scale spatially distributed hydrological models. In particular, the hydrological models include the influence of shallow groundwater on evapotranspiration during dry...... by HIRHAM simulated precipitation. The last two simulations include iv) a standard HIRHAM simulation, and v) a fully coupled HIRHAM-MIKE SHE simulation locally replacing the land surface scheme by MIKE SHE for the FIFE area, while HIRHAM in standard configuration is used for the remaining model area...

Groundwater suppression and surface water diversion structures applied to closed shallow land burial trenches

International Nuclear Information System (INIS)

Davis, E.C.; Stansfield, R.G.; Melroy, L.A.; Huff, D.D.

1984-01-01

Shallow depth to groundwater, surface drainage, and subsurface flow during storm events are major environmental concerns of low-level radioactive waste management operations in humid regions. At two waste disposal sites within the Oak Ridge National Laboratory (ORNL), groups of closed trenches have experienced these problems and have been shown to collect and hold water with seasonal fluctuations ranging from 1 to 2 m. In an attempt to correct these water-related problems, the older of the two sites [Solid Waste Storage Area Four (SWSA 4)] was equipped in September 1975 with asphalt lined drainage-ways designed to prevent infiltration of storm drainage from a 13.8-ha upslope catchment. At the second site (49-Trench area of SWSA 6), the entire 0.44-ha trench area was capped with a bentonite clay cover in 1976. These attempts have not corrected the water problems. In September 1983, engineered drainage projects were initiated at both the disposal sites. The SWSA 4 project was designed to divert surface runoff and shallow subsurface flow which originates upslope of the site away from the disposal area. The second project, a passive French drain constructed in SWSA 6, was aimed strictly at suppressing the site water table, thus preventing its intersection with the bottoms of disposal trenches. Postconstruction monitoring for performance evaluation has shown that the water table in the 49-Trench area has been suppressed to a depth > 4.9 m below the ground surface over 50% of the site as compared to a depth of only 2.1 m for certain parts of the same area observed during seasonally wet months prior to drain construction. The SWSA 4 project evaluation indicates that 56% of the Winter-Spring 1984 runoff was diverted around SWSA 4 via the drainage system

Impacts of the 2013 Extreme Flood in Northeast China on Regional Groundwater Depth and Quality

Directory of Open Access Journals (Sweden)

Xihua Wang

2015-08-01

Full Text Available Flooding’s impact on shallow groundwater is not well investigated. In this study, we analyzed changes in the depth and quality of a regional shallow aquifer in the 10.9 × 104 km2 Sanjiang Plain, Northeast China, following a large flood in the summer of 2013. Pre- (2008–2012 and post-flood records on groundwater table depth and groundwater chemistry were gathered from 20 wells across the region. Spatial variability of groundwater recharge after the flood was assessed and the changes in groundwater quality in the post-flood period were determined. The study found a considerable increase in the groundwater table after the 2013 summer flood across the region, with the largest (3.20 m and fastest (0.80 m·s−1 rising height occurring in western Sanjiang Plain. The rising height and velocity gradually declined from the west to the east of the plain. For the entire region, we estimated an average recharge height of 1.24 m for the four flood months (June to September of 2013. Furthermore, we found that the extreme flood reduced nitrate (NO3− and chloride (Cl− concentrations and electrical conductivity (EC in shallow groundwater in the areas that were close to rivers, but increased NO3− and Cl− concentrations and EC in the areas that were under intensive agricultural practices. As the region’s groundwater storage and quality have been declining due to the rapidly increasing rice cultivation, this study shows that floods should be managed as water resources to ease the local water shortage as well as shallow groundwater pollution.

The origin of groundwater composition in the Pampeano Aquifer underlying the Del Azul Creek basin, Argentina

International Nuclear Information System (INIS)

Zabala, M.E.; Manzano, M.; Vives, L.

2015-01-01

The Pampean plain is the most productive region in Argentina. The Pampeano Aquifer beneath the Pampean plain is used mostly for drinking water. The study area is the sector of the Pampeano Aquifer underlying the Del Azul Creek basin, in Buenos Aires province. The main objective is to characterize the chemical and isotopic compositions of groundwater and their origin on a regional scale. The methodology used involved the identification and characterization of potential sources of solutes, the study of rain water and groundwater chemical and isotopic characteristics to deduce processes, the development of a hydrogeochemical conceptual model, and its validation by hydrogeochemical modelling with PHREEQC. Groundwater samples come mostly from a two-depth monitoring network of the “Dr. Eduardo J. Usunoff” Large Plains Hydrology Institute (IHLLA). Groundwater salinity increases from SW to NE, where groundwater is saline. In the upper basin groundwater is of the HCO 3 -Ca type, in the middle basin it is HCO 3 -Na, and in the lower basin it is ClSO 4 –NaCa and Cl–Na. The main processes incorporating solutes to groundwater during recharge in the upper basin are rain water evaporation, dissolution of CO 2 , calcite, dolomite, silica, and anorthite; cationic exchange with Na release and Ca and Mg uptake, and clay precipitation. The main processes modifying groundwater chemistry along horizontal flow at 30 m depth from the upper to the lower basin are cationic exchange, dissolution of silica and anorthite, and clay precipitation. The origin of salinity in the middle and lower basin is secular evaporation in a naturally endorheic area. In the upper and middle basins there is agricultural pollution. In the lower basin the main pollution source is human liquid and solid wastes. Vertical infiltration through the boreholes annular space during the yearly flooding stages is probably the pollution mechanism of the samples at 30 m depth. - Highlights: • The work studies the

The origin of groundwater composition in the Pampeano Aquifer underlying the Del Azul Creek basin, Argentina

Energy Technology Data Exchange (ETDEWEB)

Zabala, M.E., E-mail: mzabala@faa.unicen.edu.ar [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, C1033AAJ Ciudad Autónoma de Buenos Aires (Argentina); Instituto de Hidrología de Llanuras “Dr. Eduardo J. Usunoff”, Av. República Italia 780, 7300 Azul, Provincia Buenos Aires (Argentina); Manzano, M., E-mail: marisol.manzano@upct.es [Escuela de Ingeniería de Caminos, Canales y Puertos y de Ingeniería de Minas, Universidad Politécnica de Cartagena, P° de Alfonso XIII 52, E-30203 Cartagena (Spain); Vives, L., E-mail: lvives@faa.unicen.edu.ar [Instituto de Hidrología de Llanuras “Dr. Eduardo J. Usunoff”, Av. República Italia 780, 7300 Azul, Provincia Buenos Aires (Argentina)

2015-06-15

The Pampean plain is the most productive region in Argentina. The Pampeano Aquifer beneath the Pampean plain is used mostly for drinking water. The study area is the sector of the Pampeano Aquifer underlying the Del Azul Creek basin, in Buenos Aires province. The main objective is to characterize the chemical and isotopic compositions of groundwater and their origin on a regional scale. The methodology used involved the identification and characterization of potential sources of solutes, the study of rain water and groundwater chemical and isotopic characteristics to deduce processes, the development of a hydrogeochemical conceptual model, and its validation by hydrogeochemical modelling with PHREEQC. Groundwater samples come mostly from a two-depth monitoring network of the “Dr. Eduardo J. Usunoff” Large Plains Hydrology Institute (IHLLA). Groundwater salinity increases from SW to NE, where groundwater is saline. In the upper basin groundwater is of the HCO{sub 3}-Ca type, in the middle basin it is HCO{sub 3}-Na, and in the lower basin it is ClSO{sub 4}–NaCa and Cl–Na. The main processes incorporating solutes to groundwater during recharge in the upper basin are rain water evaporation, dissolution of CO{sub 2}, calcite, dolomite, silica, and anorthite; cationic exchange with Na release and Ca and Mg uptake, and clay precipitation. The main processes modifying groundwater chemistry along horizontal flow at 30 m depth from the upper to the lower basin are cationic exchange, dissolution of silica and anorthite, and clay precipitation. The origin of salinity in the middle and lower basin is secular evaporation in a naturally endorheic area. In the upper and middle basins there is agricultural pollution. In the lower basin the main pollution source is human liquid and solid wastes. Vertical infiltration through the boreholes annular space during the yearly flooding stages is probably the pollution mechanism of the samples at 30 m depth. - Highlights: • The

Field demonstration of improved shallow land burial practices for low-level radioactive solid wastes: preliminary site characterization and progress report

International Nuclear Information System (INIS)

Vaughan, N.D.; Haase, C.S.; Huff, D.D.; Lee, S.Y.; Walls, E.C.

1982-12-01

A 5-year field demonstration (ETF) of improved shallow land burial practices for low-level radioactive solid wastes in a humid environment evaluates the use of a trench liner and grout as alternate trench treatments for improving shallow land burial site performance in the humid East. The ETF is located within the Copper Creek thrust block of the Valley and Ridge Province of east Tennessee and is underlain by strata of the Middle to Late Cambrian Conasauga Group. The Maryville Limestone formation, which is composed of ribbon-bedded and interclastic limestones and dark grey shales and mudstones, comprises the bedrock immediately beneath the site. The bedrock and residuum structure are characterized by anticlinal folds with numerous joints and fractures, some of which are filled with calcite. Seismic and electrical resistivity geophysical methods were useful in characterizing the thickness of residuum and presence of structural features. Soils are illitic and range from podzolic to lithosols to alluvial in the vicinity of the ETF, but the original soil solum was removed in 1975 when the mixed hardwood forest was cleared and the site was planted in grasses. The remaining residuum consists of acidic soil aggregate and extensively weathered siltstone and sandstone which exhibit the original rock structure. Mean annual precipitation at the site is 1500 mm, although during the initial study period (10-1-80 to 9-30-81) the annual total was 939 mm. Runoff was estimated to be about 50% of the precipitation total, based on observations at two Parshall flumes installed at the site. Storm runoff is quite responsive to rainfall, and the lag time between peak rainfall and runoff is less than 15 min during winter storms. Tracer studies of the ground-water system, suggest that ground-water flow has two distinct components, one associated with fracture flow and the other with intergranular flow

Supplemental Groundwater Remediation Technologies to Protect the Columbia River at Hanford, WA

International Nuclear Information System (INIS)

Thompson, K.M.; Petersen, Scott W.; Fruchter, Jonathan S.; Ainsworth, Calvin C.; Vermeul, Vince R.; Wellman, Dawn M.; Szecsody, Jim E.; Truex, Michael J.; Amonette, James E.; Long, Philip E.

2007-01-01

Nine projects have been recently selected by the US Department of Energy (EM-22) to address groundwater contaminant migration at the Hanford Site. This paper summarizes the background and objectives of these projects. Five of the selected projects are targeted at hexavalent chromium contamination in Hanford 100 Area groundwater. These projects represent an integrated approach towards identifying the source of hexavalent chromium contamination in the Hanford 100-D Area and treating the groundwater contamination. Currently, there is no effective method to stop strontium-90 associated with the riparian zone sediments from leaching into the river. Phytoremediation may be a possible way to treat this contamination. Its use at the 100-N Area will be investigated. Another technology currently being tested for strontium-90 contamination at the 100-N Area involves injection (through wells) of a calcium-citrate-phosphate solution, which will precipitate apatite, a natural calcium-phosphate mineral. Apatite will adsorb the strontium-90, and then incorporate it as part of the apatite structure, isolating the strontium-90 contamination from entering the river. This EM-22 funded apatite project will develop a strategy for infiltrating the apatite solution from ground surface or a shallow trench to provide treatment over the upper portion of the contaminated zone, which is unsaturated during low river stage.

Heavy metal contamination and human health risk assessment in drinking water from shallow groundwater wells in an agricultural area in Ubon Ratchathani province, Thailand.

Science.gov (United States)

Wongsasuluk, Pokkate; Chotpantarat, Srilert; Siriwong, Wattasit; Robson, Mark

2014-02-01

Most local people in the agricultural areas of Hua-ruea sub-district, Ubon Ratchathani province (Thailand), generally consume shallow groundwater from farm wells. This study aimed to assess the health risk related to heavy metal contamination in that groundwater. Samples were randomly collected from 12 wells twice in each of the rainy and the dry seasons and were analyzed by inductive coupled plasma spectrometry-mass spectrometry (ICP-MS). The concentration of detected metals in each well and the overall mean were below the acceptable groundwater standard limits for As, Cd, Cr, Cu, Hg, Ni and Zn, but Pb levels were higher in four wells with an overall average Pb concentration of 16.66 ± 18.52 μg/l. Exposure questionnaires, completed by face-to-face interviews with 100 local people who drink groundwater from farm wells, were used to evaluate the hazard quotients (HQs) and hazard indices (HIs). The HQs for non-carcinogenic risk for As, Cu, Zn and Pb, with a range of 0.004-2.901, 0.053-54.818, 0.003-6.399 and 0.007-26.80, respectively, and the HI values (range from 0.10 to 88.21) exceeded acceptable limits in 58 % of the wells. The HI results were higher than one for groundwater wells located in intensively cultivated chili fields. The highest cancer risk found was 2.6 × 10(-6) for As in well no. 11. This study suggested that people living in warmer climates are more susceptible to and at greater risk of groundwater contamination because of their increased daily drinking water intake. This may lead to an increased number of cases of non-carcinogenic and carcinogenic health defects among local people exposed to heavy metals by drinking the groundwater.

Groundwater flow and hydrogeochemical evolution in the Jianghan Plain, central China

Science.gov (United States)

Gan, Yiqun; Zhao, Ke; Deng, Yamin; Liang, Xing; Ma, Teng; Wang, Yanxin

2018-05-01

Hydrogeochemical analysis and multivariate statistics were applied to identify flow patterns and major processes controlling the hydrogeochemistry of groundwater in the Jianghan Plain, which is located in central Yangtze River Basin (central China) and characterized by intensive surface-water/groundwater interaction. Although HCO3-Ca-(Mg) type water predominated in the study area, the 457 (21 surface water and 436 groundwater) samples were effectively classified into five clusters by hierarchical cluster analysis. The hydrochemical variations among these clusters were governed by three factors from factor analysis. Major components (e.g., Ca, Mg and HCO3) in surface water and groundwater originated from carbonate and silicate weathering (factor 1). Redox conditions (factor 2) influenced the geogenic Fe and As contamination in shallow confined groundwater. Anthropogenic activities (factor 3) primarily caused high levels of Cl and SO4 in surface water and phreatic groundwater. Furthermore, the factor score 1 of samples in the shallow confined aquifer gradually increased along the flow paths. This study demonstrates that enhanced information on hydrochemistry in complex groundwater flow systems, by multivariate statistical methods, improves the understanding of groundwater flow and hydrogeochemical evolution due to natural and anthropogenic impacts.

Groundwater monitoring program plan and conceptual site model for the Al-Tuwaitha Nuclear Research Center in Iraq.

Energy Technology Data Exchange (ETDEWEB)

Copland, John Robin; Cochran, John Russell

2013-07-01

The Radiation Protection Center of the Iraqi Ministry of Environment is developing a groundwater monitoring program (GMP) for the Al-Tuwaitha Nuclear Research Center located near Baghdad, Iraq. The Al-Tuwaitha Nuclear Research Center was established in about 1960 and is currently being cleaned-up and decommissioned by Iraqs Ministry of Science and Technology. This Groundwater Monitoring Program Plan (GMPP) and Conceptual Site Model (CSM) support the Radiation Protection Center by providing: A CSM describing the hydrogeologic regime and contaminant issues, recommendations for future groundwater characterization activities, and descriptions of the organizational elements of a groundwater monitoring program. The Conceptual Site Model identifies a number of potential sources of groundwater contamination at Al-Tuwaitha. The model also identifies two water-bearing zones (a shallow groundwater zone and a regional aquifer). The depth to the shallow groundwater zone varies from approximately 7 to 10 meters (m) across the facility. The shallow groundwater zone is composed of a layer of silty sand and fine sand that does not extend laterally across the entire facility. An approximately 4-m thick layer of clay underlies the shallow groundwater zone. The depth to the regional aquifer varies from approximately 14 to 17 m across the facility. The regional aquifer is composed of interfingering layers of silty sand, fine-grained sand, and medium-grained sand. Based on the limited analyses described in this report, there is no severe contamination of the groundwater at Al-Tuwaitha with radioactive constituents. However, significant data gaps exist and this plan recommends the installation of additional groundwater monitoring wells and conducting additional types of radiological and chemical analyses.

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

Groundwater discharge by evapotranspiration, flow of water in unsaturated soil, and stable isotope water sourcing in areas of sparse vegetation, Amargosa Desert, Nye County, Nevada

Science.gov (United States)

Moreo, Michael T.; Andraski, Brian J.; Garcia, C. Amanda

2017-08-29

This report documents methodology and results of a study to evaluate groundwater discharge by evapotranspiration (GWET) in sparsely vegetated areas of Amargosa Desert and improve understanding of hydrologic-continuum processes controlling groundwater discharge. Evapotranspiration and GWET rates were computed and characterized at three sites over 2 years using a combination of micrometeorological, unsaturated zone, and stable-isotope measurements. One site (Amargosa Flat Shallow [AFS]) was in a sparse and isolated area of saltgrass (Distichlis spicata) where the depth to groundwater was 3.8 meters (m). The second site (Amargosa Flat Deep [AFD]) was in a sparse cover of predominantly shadscale (Atriplex confertifolia) where the depth to groundwater was 5.3 m. The third site (Amargosa Desert Research Site [ADRS]), selected as a control site where GWET is assumed to be zero, was located in sparse vegetation dominated by creosote bush (Larrea tridentata) where the depth to groundwater was 110 m.Results indicated that capillary rise brought groundwater to within 0.9 m (at AFS) and 3 m (at AFD) of land surface, and that GWET rates were largely controlled by the slow but relatively persistent upward flow of water through the unsaturated zone in response to atmospheric-evaporative demands. Greater GWET at AFS (50 ± 20 millimeters per year [mm/yr]) than at AFD (16 ± 15 mm/yr) corresponded with its shallower depth to the capillary fringe and constantly higher soil-water content. The stable-isotope dataset for hydrogen (δ2H) and oxygen (δ18O) illustrated a broad range of plant-water-uptake scenarios. The AFS saltgrass and AFD shadscale responded to changing environmental conditions and their opportunistic water use included the time- and depth-variable uptake of unsaturated-zone water derived from a combination of groundwater and precipitation. These results can be used to estimate GWET in other areas of Amargosa Desert where hydrologic conditions are similar.

A groundwater mass flux model for screening the groundwater-to-indoor-air exposure pathway

Energy Technology Data Exchange (ETDEWEB)

McHugh, T.; Blanc, P.C. de; Connor, J. [Groundwater Services Inc, Houston, TX (United States)

2003-07-01

The potential for human exposure via volatilisation of groundwater contaminants into indoor air has been a focus of increasing concern in recent years. At a small number of sites, elevated indoor vapour concentrations have been measured within buildings overlying shallow groundwater contaminated with chlorinated solvents, causing public concern over the potential for similar problems at other corrective action sites. In addition, use of the screening-levelmodel developed by Johnson and Ettinger (1991) for the groundwater-to-indoor-air exposure pathway has suggested that low microgram per litre (ug/L)-range concentrations of either chlorinated or non-chlorinated volatile organic compounds dissolved in groundwater could result in indoor vapour concentrations in excess of applicable risk-based exposure limits. As an alternative screening tool, this paper presents a groundwater mass flux model for evaluation of transport to indoor air. The mass flux model is intended to serve as a highly conservative screening tool that over-predicts groundwater-to-indoor-air mass flux, yet still provides sufficient sensitivity to identify sites for which the groundwater-to-indoor air exposure pathway is not a concern. (orig.)

Determining shallow aquifer vulnerability by the DRASTIC model ...

Indian Academy of Sciences (India)

Shallow aquifer vulnerability has been assessed using GIS-based DRASTIC model by incorporating the major geological and hydrogeological factors that affect and control the groundwater contamination in a granitic terrain. It provides a relative indication of aquifer vulnerability to the contamination. Further, it has been ...

Determination of groundwater characteristics and water budget in the Edremit Plain by means of isotopes

International Nuclear Information System (INIS)

Onhon, E.

1983-08-01

Detailed field investigations with environmental isotopes (O-18, D, T, C-14 and C-13) have been conducted to study the replenishment process and flow dynamics of groundwater system in Edremit plain, which is an area of 200 m 2 size located in the eastern part of Turkey. Along with conventional hydrogeological and hydrochemical data collected from the study area, results of environmental isotopic analyses performed on water samples systematically collected from the area, enabled to delineate the source and origin of recharge to the shallow groundwater aquifers and as well provided information on various dynamic parameters of groundwater flow. In addition to basic flow dynamic characteristics of the shallow aquifer in the study area, environmental isotopes were used to investigate the hydraulic interconnections between deeper thermal groundwater system and the upper shallow aquifers. Results of all the environmental isotopic analyses and their interpretation are given

the use of anion geochemistry in mapping groundwater facies in the ...

African Journals Online (AJOL)

Admin

GLOBAL JOURNAL OF GEOLOGICAL SCIENCES VOL 8, NO. 2, 2010: 155- 166 ... The first two types exist in both shallow – and deep – groundwater environments while the ...... Toth J., 1966b Groundwater geology, movement, chemistry and ...

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.

Isotope method for the recognition of groundwater formation in China's preselected high level radioactive waste disposal repository site

International Nuclear Information System (INIS)

Guo Yonghai; Wang Ju; Liu Shufen; Su Rui; Lu Chuanhe

2005-01-01

Yemaquan region in Beishan area. Gansu province, is one of the preselected sites of disposal repository for high level radioactive waste (HLW) in our country. Hydrogeological condition is an important aspect for site evaluation and the groundwater formation is a key factor to reflect the hydrogeological conditions for a certain area. Isotopic method is the one of the important means to determine the groundwater formation. Through the sampling and analysis of shallow groundwater isotopes of Yemaquan region, combined with geological, hydrogeological and hydrogeochemical characteristics, the issue of groundwater formation in the study region was discussed. The main cognition is that the groundwater in the region was formed from the infiltration of modern rainfall and the strong evaporation was happened for the shallow groundwater, which indicates the circulation conditions were relatively good for the shallow groundwater. This cognition provides very important hydrogeological information and basis for the evaluation of Yemaquan preselected site. (authors)

Continuous Long-Term Modeling of Shallow Groundwater-Surface Water Interaction: Implications for a Wet Prairie Restoration

Science.gov (United States)

Wijayarathne, D. B.; Gomezdelcampo, E.

2017-12-01

The existence of wet prairies is wholly dependent on the groundwater and surface water interaction. Any process that alters this interaction has a significant impact on the eco-hydrology of wet prairies. The Oak Openings Region (OOR) in Northwest Ohio supports globally rare wet prairie habitats and the precious few remaining have been drained by ditches, altering their natural flow and making them an unusually variable and artificial system. The Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model from the US Army Engineer Research and Development Center was used to assess the long-term impacts of land-use change on wet prairie restoration. This study is the first spatially explicit, continuous, long-term modeling approach for understanding the response of the shallow groundwater system of the OOR to human intervention, both positive and negative. The GSSHA model was calibrated using a 2-year weekly time series of water table elevations collected with an array of piezometers in the field. Basic statistical analysis indicates a good fit between observed and simulated water table elevations on a weekly level, though the model was run on an hourly time step and a pixel size of 10 m. Spatially-explicit results show that removal of a local ditch may not drastically change the amount of ponding in the area during spring storms, but large flooding over the entire area would occur if two other ditches are removed. This model is being used by The Nature Conservancy and Toledo Metroparks to develop different scenarios for prairie restoration that minimize its effect on local homeowners.

Arsenic release and geochemical evolution of groundwater in an alluvial aquitard, West Bengal, India.

Science.gov (United States)

Desbarats, A. J.; Pal, T.; Mukherjee, P. K.; Beckie, R. D.

2017-12-01

According to the World Health Organization, contamination of groundwater by geogenic arsenic (As) represents the largest mass poisoning in history. At a field site in West Bengal, India, the source of As affecting a shallow aquifer was traced to silty sediments filling an abandoned river meander. Along with As-bearing phases, these sediments also contain 0.46 % organic carbon. The release of As within the channel fill is investigated using a geochemical mass balance model supported by detailed field observations of aqueous chemistry, sequential extraction analyses of sediment chemistry, and analyses of sediment mineralogy. The model explores the evolution of groundwater chemistry along a flow path extending from its recharge point in an abandoned channel pond, through the channel-fill sequence, to the underlying aquifer. Variations in groundwater composition within the host sediments are explained in terms of mineral weathering driven by organic carbon decay. The model yields reaction coefficients expressing amounts of minerals (and gases) reacting or precipitating along the flow path. Arsenic and phosphorus cycles appear closely linked as these species are hosted by goethite, Fe-rich chlorite, and vivianite. Arsenic is released through the rapid reductive dissolution of goethite and the slower weathering of chlorite. Concomitantly, some As is sequestered in precipitating vivianite. These competing processes reach equilibrium deeper in the channel-fill sequence as groundwater As concentrations stabilize. Using groundwater residence time in channel fill obtained from a numerical flow model and the calculated reaction coefficients, rates of organic carbon oxidation, goethite dissolution, and net As release are estimated at 1.15 mmol C L-1 a-1, 0.18 mmol L-1 a-1, and 4.57 10-4 mmol L-1 a-1, respectively. Fine-grained yet slightly permeable deposits such as channel-fill silts containing reactive organic carbon and As-bearing goethite and phyllosilicates are localized

Impact of urbanization coupled with drought situations on groundwater quality in shallow (basalt) and deeper (granite) aquifers with special reference to fluoride in Nanded-Waghala Municipal Corporation, Nanded District, Maharashtra (India).

Science.gov (United States)

Pandith, Madhnure; Kaplay, R D; Potdar, S S; Sangnor, H; Rao, A D

2017-09-01

Rapid expansion in urbanization and industrialization coupled with recent drought conditions has triggered unplanned groundwater development leading to severe stress on groundwater resources in many urban cities of India, particularly cities like Nanded, Maharashtra. In the quest of tapping drinking water requirement, due to recent drought conditions, people from the city are piercing through entire thickness of shallow basalt aquifers to reach productive deeper granite aquifers. Earlier reports from Nanded and surrounding districts suggest that deeper granite aquifer is contaminated with fluoride (geogenic). The study aimed to find out variations in fluoride concentration in shallow basalt (10-167 m) and deeper granite aquifers (below 167 m) and to find out the relationship between fluoride and other ions. Study suggests that concentration of fluoride in shallow basalt aquifer is within maximum permissible limits of Bureau of Indian Standards and deeper granite aquifer contains as high as 4.9 mg/l of fluoride and all samples from granite aquifers are unfit for human consumption. The groundwater from basalt aquifer is mainly Ca-HCO 3- Cl type, and from granite aquifer, it is Ca-Na-Cl type. The correlation plot between F - vs. pH, Na + and HCO 3 - shows a positive correlation and an inverse relationship with Ca 2+ in both aquifers. As recommendations, it is suggested that granite aquifers should not be tapped for drinking purposes; however, in drought situations, water from this aquifer should be blended with treated surface water before supplying for drinking purposes. Efforts may be made to utilize 1.35 MCM of rainwater from available rooftop, which is sufficient to cater for the needs of ~40,800 people annually. Most effective defluoridation techniques like electrolytic de-fluoridation (EDF), ion exchange and reverse osmosis may be adopted along with integrated fluorosis mitigation measures.

Detection of Waterborne Protozoa, Viruses, and Bacteria in Groundwater and Other Water Samples in the Kathmandu Valley, Nepal

Science.gov (United States)

Haramoto, E.

2018-03-01

In this study, the prevalence of various waterborne pathogens in water samples collected in the Kathmandu Valley, Nepal, and the applicability of Escherichia coli as an indicator of pathogen contamination in groundwater were assessed. Fifty-three water samples, including shallow groundwater and river water, were analyzed to examine the presence of protozoan (oo)cysts via fluorescence microscopy and that of viral and bacterial genomes via quantitative PCR. At least one of the seven types of pathogens tested (i.e., Cryptosporidium, Giardia, human adenoviruses, noroviruses of genogroups I and II, group A rotaviruses, and Vibrio cholerae) was detected in 68% (15/22) of the shallow dug well water samples; groundwater in the shallow dug wells was more contaminated compared with that in shallow tube wells (8/15, 53%). River water and sewage samples were contaminated with extremely high concentrations of multiple pathogens, whereas a tap water sample supplied by a water tanker tested positive for human adenoviruses and V. cholerae. The detection of host-specific Bacteroidales genetic markers revealed the effects of human and animal feces on groundwater contamination. The tested pathogens were sometimes detected even in E. coli-negative groundwater samples, indicative of the limitations of using E. coli as an indicator for waterborne pathogens in groundwater.

Temperature-induced impacts on groundwater quality and arsenic mobility in anoxic aquifer sediments used for both drinking water and shallow geothermal energy production.

Science.gov (United States)

Bonte, Matthijs; van Breukelen, Boris M; Stuyfzand, Pieter J

2013-09-15

Aquifers used for the production of drinking water are increasingly being used for the generation of shallow geothermal energy. This causes temperature perturbations far beyond the natural variations in aquifers and the effects of these temperature variations on groundwater quality, in particular trace elements, have not been investigated. Here, we report the results of column experiments to assess the impacts of temperature variations (5°C, 11°C, 25°C and 60°C) on groundwater quality in anoxic reactive unconsolidated sandy sediments derived from an aquifer system widely used for drinking water production in the Netherlands. Our results showed that at 5 °C no effects on water quality were observed compared to the reference of 11°C (in situ temperature). At 25°C, As concentrations were significantly increased and at 60 °C, significant increases were observed pH and DOC, P, K, Si, As, Mo, V, B, and F concentrations. These elements should therefore be considered for water quality monitoring programs of shallow geothermal energy projects. No consistent temperature effects were observed on Na, Ca, Mg, Sr, Fe, Mn, Al, Ba, Co, Cu, Ni, Pb, Zn, Eu, Ho, Sb, Sc, Yb, Ga, La, and Th concentrations, all of which were present in the sediment. The temperature-induced chemical effects were probably caused by (incongruent) dissolution of silicate minerals (K and Si), desorption from, and potentially reductive dissolution of, iron oxides (As, B, Mo, V, and possibly P and DOC), and mineralisation of sedimentary organic matter (DOC and P). Copyright © 2013 Elsevier Ltd. All rights reserved.

Tree Growth Response to Drought Along a Depth to Groundwater Gradient in Northern Wisconsin

Science.gov (United States)

Ciruzzi, D. M.; Loheide, S. P., II

2017-12-01

Understanding complex spatial and temporal patterns of drought-induced forest stress requires knowledge of the physiological drivers and ecosystem attributes that lead to or inhibit tree mortality. Prevailing meteorological conditions leading to drought may have lesser effect on vegetation that has evolved to avoid drought by accessing deeper soil moisture reserves or shallow groundwater to meet evapotranspiration demand. This is especially true in arid and semi-arid regions, yet groundwater use by trees is rarely explored in temperate systems and the extent to which groundwater use reduces drought vulnerability in these climates and regions is unknown. We explored responses of radial growth in temperate tress to wet and dry years across a depth to groundwater gradient from 1 to 9 meters in sandy forests in northern Wisconsin. The spatial patterns of tree growth in this watershed show areas where tree growth is influenced by depth to groundwater. Preliminary results showed trees in areas of shallower groundwater with low variability in tree growth and indicated that tree growth remains consistent during both wet and dry years. Conversely, trees in areas of deeper groundwater showed higher variability in tree growth during wet and dry years. We hypothesize that even in this humid region, the sandy soils do not retain sufficient moisture leading to potentially frequent water stress in trees and reductions in productivity. However, where and when accessible, we suspect trees use shallow groundwater to sustain evapotranspiration and maintain consistent growth during dry periods.

The aquatic geochemistry of arsenic in volcanic groundwaters from southern Italy

International Nuclear Information System (INIS)

Aiuppa, Alessandro; D'Alessandro, Walter; Federico, Cinzia; Palumbo, Barbara; Valenza, Mariano

2003-01-01

This paper discusses the abundance, speciation and mobility of As in groundwater systems from active volcanic areas in Italy. Using literature data and new additional determinations, the main geochemical processes controlling the fate of As during gas-water-rock interaction in these systems are examined. Arsenic concentrations in the fluids range from 0.1 to 6940 μg/l, with wide differences observed among the different volcanoes and within each area. The dependence of As content on water temperature, pH, redox potential and major ions is investigated. Results demonstrate that As concentrations are highest where active hydrothermal circulation takes place at shallow levels, i.e. at Vulcano Island and the Phlegrean Fields. In both areas the dissolution of As-bearing sulphides is likely to be the main source of As. Mature Cl-rich groundwaters, representative of the discharge from the deep thermal reservoirs, are typically enriched in As with respect to SO 4 -rich ''steam heated groundwaters''. In the HCO 3 - groundwaters recovered at Vesuvius and Etna, aqueous As cycling is limited by the absence of high-temperature interactions and by high-Fe content of the host rocks, resulting in oxidative As adsorption. Thermodynamic modelling suggests that reducing H 2 S-rich groundwaters are in equilibrium with realgar, whereas in oxidising environments over-saturation with respect to Fe oxy-hydroxides is indicated. Under these oxidising conditions, As solubility decreases controlled by As co-precipitation with, or adsorption on, Fe oxy-hydroxides. Consistent with thermodynamic considerations, As mobility in the studied areas is enhanced in intermediate redox environments, where both sulphides and Fe hydroxides are unstable

Hanford 100-N Area In Situ Apatite and Phosphate Emplacement by Groundwater and Jet Injection: Geochemical and Physical Core Analysis

Energy Technology Data Exchange (ETDEWEB)

Szecsody, James E.; Vermeul, Vincent R.; Fruchter, Jonathan S.; Williams, Mark D.; Rockhold, Mark L.; Qafoku, Nikolla; Phillips, Jerry L.

2010-07-01

The purpose of this study is to evaluate emplacement of phosphate into subsurface sediments in the Hanford Site 100-N Area by two different technologies: groundwater injection of a Ca-citrate-PO4 solution and water-jet injection of sodium phosphate and/or fish-bone apatite. In situ emplacement of phosphate and apatite adsorbs, then incorporates Sr-90 into the apatite structure by substitution for calcium. Overall, both technologies (groundwater injection of Ca-citrate-PO4) and water-jet injection of sodium phosphate/fish-bone apatite) delivered sufficient phosphate to subsur¬face sediments in the 100-N Area. Over years to decades, additional Sr-90 will incorporate into the apatite precipitate. Therefore, high pressure water jetting is a viable technology to emplace phosphate or apatite in shallow subsurface sediments difficult to emplace by Ca-citrate-PO4 groundwater injections, but further analysis is needed to quantify the relevant areal extent of phosphate deposition (in the 5- to 15-ft distance from injection points) and cause of the high deposition in finer grained sediments.

Contrasting patterns of groundwater evapotranspiration in grass and tree dominated riparian zones of a temperate agricultural catchment

Science.gov (United States)

Satchithanantham, Sanjayan; Wilson, Henry F.; Glenn, Aaron J.

2017-06-01

Consumptive use of shallow groundwater by phreatophytic vegetation is a significant part of the water budget in many regions, particularly in riparian areas. The influence of vegetation type on groundwater level fluctuations and evapotranspiration has rarely been quantified for contrasting plant communities concurrently although it has implications for downstream water yield and quality. Hourly groundwater evapotranspiration (ETG) rates were estimated for grass and tree riparian vegetation in southwestern Manitoba, Canada using two modified White methods. Groundwater table depth was monitored in four 21 m transects of five 3 m deep monitoring wells in the riparian zone of a stream reach including tree (Acer negundo; boxelder) and grass (Bromus inermis; smooth brome) dominated segments. The average depths to the groundwater table from the surface were 1.4 m and 1 m for the tree and grass segments, respectively, over the two-year study. During rain free periods of the growing season ETG was estimated for a total of 70 days in 2014 and 79 days in 2015 when diurnal fluctuations were present in groundwater level. Diurnal groundwater level fluctuations were observed during dry periods under both segments, however, ETG was significantly higher (p < 0.001) under trees compared to grass cover in 2014 (a wet year with 72% higher than normal growing season precipitation) and 2015 (a drier year with 15% higher than normal growing season precipitation). The two methods used to estimate ETG produced similar daily and seasonal values for the two segments. In 2014, total ETG was approximately 50% (148 mm) and 100% (282-285 mm) of reference evapotranspiration (ETref, 281 mm) for the grass and tree segments, respectively. In 2015, total ETG was approximately 40% (106-127 mm) and 120% (369-374 mm) of ETref (307 mm) for the grass and tree segments, respectively. Results from the study show the tree dominated portions of the stream reach consumed approximately 2.4 ML ha-1 yr-1 more

Evaluation of organic contamination in urban groundwater surrounding a municipal landfill, Zhoukou, China.

Science.gov (United States)

Han, D M; Tong, X X; Jin, M G; Hepburn, Emily; Tong, C S; Song, X F

2013-04-01

This paper investigates the organic pollution status of shallow aquifer sediments and groundwater around Zhoukou landfill. Chlorinated aliphatic hydrocarbons, monocylic aromatic hydrocarbons, halogenated aromatic hydrocarbons, organochlorine pesticides and other pesticides, and polycyclic aromatic hydrocarbons (PAHs) have been detected in some water samples. Among the detected eleven PAHs, phenanthrene, fluorine, and fluoranthene are the three dominant in most of the groundwater samples. Analysis of groundwater samples around the landfill revealed concentrations of PAHs ranging from not detected to 2.19 μg/L. The results show that sediments below the waste dump were low in pollution, and the shallow aquifer, at a depth of 18-30 m, was heavily contaminated, particularly during the wet season. An oval-shaped pollution halo has formed, spanning 3 km from west to east and 2 km from south to north, and mainly occurs in groundwater depths of 2-4 m. For PAH source identification, both diagnostic ratios of selected PAHs and principal component analysis were studied, suggesting mixed sources of pyro- and petrogenic derived PAHs in the Zhoukou landfill. Groundwater table fluctuations play an important role in the distribution of organic pollutants within the shallow aquifer. A conceptual model of leachate migration in the Quaternary aquifers surrounding the Zhoukou landfill has been developed to describe the contamination processes based on the major contaminant (PAHs). The groundwater zone contaminated by leachate has been identified surrounding the landfill.

Is evaporative colling important for shallow clouds?

Science.gov (United States)

Gentine, P.; Park, S. B.; Davini, P.; D'Andrea, F.

2017-12-01

We here investigate and test using large-eddy simulations the hypothesis that evaporative cooling might not be crucial for shallow clouds. Results from various Shallow convection and stratocumulus LES experiments show that the influence of evaporative cooling is secondary compared to turbulent mixing, which dominates the buoyancy reversal. In shallow cumulus subising shells are not due to evaporative cooling but rather reflect a vortical structure, with a postive buoyancy anomaly in the core due to condensation. Disabling evaporative cooling has negligible impact on this vortical structure and on buoyancy reversal. Similarly in non-precipitating stratocumuli evaporative cooling is negeligible copmared to other factors, especially turbulent mixing and pressure effects. These results emphasize that it may not be critical to icnlude evaporative cooling in parameterizations of shallow clouds and that it does not alter entrainment.

Characterization of shallow unconsolidated aquifers in West Africa using different hydrogeological data sources as a contribution to the promotion of manual drilling and low cost techniques for groundwater exploration

Science.gov (United States)

Fussi, Fabio; Fumagalli, Letizia; Bonomi, Tullia; Kane, Cheikh H.; Fava, Francesco; Di Mauro, Biagio; Hamidou, Barry; Niang, Magatte; Wade, Souleye; Colombo, Roberto

2016-04-01

Manual drilling refers to several drilling methods that rely on human energy to construct a borehole and complete a water supply (Danert, 2015). It can be an effective strategy to increase access to groundwater in low income countries , but manual drilling can be applied only where shallow geological layers are relatively soft and water table is not too deep. It is important therefore to identify those zones where shallow hydrogeological conditions are suitable, investigating the characteristics of shallow porous aquifers. Existing hydrogeological studies are generally focused in the characterization of deep fractures aquifers, more productive and able to ensure water supply for large settlements. Information concerning shallow porous aquifers are limited. This research has been carried out in two different study areas in West Africa (North-Western Senegal and Eastern Guinea). Aim of the research is the characterization of shallow aquifer using different methods and the identification of hydrogeological condition suitable for manual drilling implementation. Three different methods to estimate geometry and hydraulic properties of shallow unconsolidated aquifers have been used: The first method is based on the analysis of stratigraphic data obtained from borehole logs of the national water point database in both countries. The following steps have been implemented on the original information using the software TANGAFRIC, specifically designed for this study: a) identification of most frequent terms used for hydrogeological description in Senegal and Guinea database; b) definition of standard categories and manual codification of data; c) automatic extraction of average distribution of textural classes at different depth intervals in the unconsolidated aquifer; d) estimation of hydraulic parameters using conversion tables between texture and hydraulic conductivity available in the literature. . The second method is based on the interpretation of pump and recovery test

Biogeochemistry of Arsenic in Groundwater Flow Systems: The Case of Southern Louisiana

Science.gov (United States)

Johannesson, K. H.; Yang, N.; Datta, S.

2017-12-01

Arsenic (As) is a highly toxic and carcinogenic metalloid that can cause serious health effects, including increased risk of cancers, infant mortality, and reduced intellectual and motor function in children to populations chronically exposed to As. Recent estimates suggest that more than 140 million people worldwide are drinking As-contaminated groundwater (i.e., As ≥ 10 µg kg-1), and the most severely affected region is the Ganges-Brahmaputra-Meghna delta in Bangladesh and India (i.e., Bengal Basin). Arsenic appears to be mobilized to Bengal Basin groundwaters by reductive dissolution of Fe oxides in aquifer sediments with the source of the labile organic matter occurring in the aquifer sediments. Studies within the lower Mississippi River delta of southern Louisiana (USA) also reveal high As concentrations (up to 640 µg kg-1) in shallow groundwaters. It is not known what affects, if any, the elevated groundwater As has had on local communities. The regional extent of high As shallow groundwaters is controlled, in part, by the distribution of Holocene sediments, deltaic deposits, and organic-rich sediments, similar to the Bengal Basin. Field and laboratory studies suggest that As is largely of geogenic origin, and further that microbial reduction of Fe(III)/Mn(IV) oxides/oxyhydroxides within the sediments contributes the bulk of the As to the groundwaters. Incubation studies are supported by biogeochemical reactive transport modeling, which also indicates reductive dissolution of metal oxides/oxyhydroxides as the likely source of As to these groundwaters. Finally, reactive transport modeling of As in shallow groundwaters suggests that sorption to aquifer mineral surfaces limits the transport of As after mobilization, which may explain, in part, the heterogeneous distribution of As in groundwaters of southern Louisiana and, perhaps, the Bengal Basin.

Hydrogeochemical signatures and evolution of groundwater impacted by the Bayan Obo tailing pond in northwest China

Energy Technology Data Exchange (ETDEWEB)

Huang, Xiang [Institute of Water Sciences and College of Engineering, Peking University, Beijing (China); Shaanxi Key Laboratory of Comprehensive Utilization of Tailing Resources, Shangluo University, Shaanxi (China); Deng, Hailin, E-mail: hailin.deng@gmail.com [CSIRO Land and Water, Private Bag No. 5, Wembley, WA 6913 (Australia); Zheng, Chunmiao [Institute of Water Sciences and College of Engineering, Peking University, Beijing (China); School of Environmental Science and Engineering, South University of Science and Technology of China, Shenzhen (China); Department of Geological Science, University of Alabama, Tuscaloosa, AL (United States); Cao, Guoliang [Institute of Water Sciences and College of Engineering, Peking University, Beijing (China)

2016-02-01

Uncontrolled leakage from mine tailing ponds can pose a serious environmental threat. Groundwater quality in a semi-arid region with extensive worries about the leakage from one of world's largest tailing ponds is studied herein through an integrated hydrogeochemical analysis and multivariate statistical analysis. Results show that elevated concentrations of NO{sub 2}{sup −}, B, Mn, NH{sub 4}{sup +}, F{sup −}, and SO{sub 4}{sup 2−} in groundwater were probably caused by leakage from the tailing pond and transported with the regional groundwater flow towards downstream Yellow River. While NO{sub 2}{sup −} contamination is only limited to areas close to the pond, high B concentrations persist within the contaminated plume originating from the tailing pond. Our current study shows that there is no geochemical evidence for U and Th contamination in groundwater due to leakage from the Bayan Obo tailing pond. Combining effects which includes regional variations, pond leaking and downstream mixing, mineral precipitation and dissolution, redox processes, ion exchange processes and agricultural activities, controlled groundwater hydrogeochemical signatures in the studied area. This study demonstrate that an increase in knowledge of evolution of groundwater quality by integrating field hydrochemical data and multivariate statistical analysis will help understand major water–rock interactions and provide a scientific basis for protection and rational utilization of groundwater resources in this and other tailing-impacted areas. - Highlights: • Combining hydrogeochemical methods and multivariate statistical analysis. • First reporting geochemical processes in aquifers nearby Bayan Obo REE tailing pond. • No geochemical evidence for uranium and thorium contamination in shallow groundwater.

Shallow rainwater lenses in deltaic areas with saline seepage

NARCIS (Netherlands)

Louw, de P.G.B.; Eeman, S.; Siemon, B.; `Voortman, B.R.; Gunnink, J.; Baaren, E.S.; Oude Essink, G.H.P.

2011-01-01

In deltaic areas with saline seepage, freshwater availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence and

Shallow rainwater lenses in deltaic areas with saline seepage

NARCIS (Netherlands)

De Louw, Perry G.B.; Eeman, Sara; Siemon, Bernhard; Voortman, Bernard R.; Gunnink, Jan; Van Baaren, Esther S.; Oude Essink, Gualbert

2011-01-01

In deltaic areas with saline seepage, fresh water availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence

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.

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

NITRATE POLLUTION IN SHALLOW GROUNDWATER OF A HARD ROCK REGION IN SOUTH CENTRAL INDIA

Science.gov (United States)

Brindha, K.; Rajesh, R.; Murugan, R.; Elango, L.

2009-12-01

Groundwater forms a major source of drinking water in most parts of the world. Due to the lack of piped drinking water supply, the population in rural areas depend on the groundwater resources for domestic purposes. Hence, the quality of groundwater in such regions needs to be monitored regularly. Presence of high concentration of nitrate in groundwater used for drinking is a major problem in many countries as it causes health related problems. Most often infants are affected by the intake of high nitrate in drinking water and food. The present study was carried out with the objective of assessing the nitrate concentration in groundwater and determining the causes for nitrate in groundwater in parts of Nalgonda district in India which is located at a distance of about 135 km towards ESE direction from Hyderabad. Nitrate concentration in groundwater of this area was analysed by collecting groundwater samples from forty six representative wells. Samples were collected once in two months from March 2008 to March 2009. A total of 244 groundwater samples were collected during the study. Soil samples were collected from fifteen locations during May 2009 and the denitrifying bacteria were isolated from the soil using spread plate method. The nitrate concentration in groundwater samples were analysed in the laboratory using Metrohm 861 advanced compact ion chromatograph using appropriate standards. The highest concentration of nitrate recorded during the sampling period was 879.65mg/l and the lowest concentration was below detection limit. The maximum permissible limit of nitrate for drinking water as per Bureau of Indian Standards is 45mg/l. About 13% of the groundwater samples collected from this study area possessed nitrate concentration beyond this limit. The nitrate concentration was high in the southeastern part of the study area. This implies that the nitrate concentration in groundwater tends to increase along the flow direction. Application of fertilizers is one

Characteristics and factors of groundwater contamination in Asian coastal megacities

Science.gov (United States)

Saito, M.; Onodera, S. I.; Jin, G.; Shimizu, Y.; Admajaya, F. T.

2017-12-01

For the sustainable use of groundwater resources for the future, it is important to conserve its quality as well as quantity. Especially in the developing megacities, land subsidence and groundwater pollution by several contaminants (e.g. nitrogen, trace metals and organic pollutants etc.) is one of a critical environmental problems, because of the intensive extraction of groundwater and huge amount of contaminant load derived from domestic wastewater as well as agricultural and industrial wastewater. However, the process of groundwater degradation, including depletion and contamination with urbanization, has not been examined well in the previous studies. In the present study, we aim to confirm the characteristics and factors of groundwater contamination in coastal Asian megacities such as Osaka and Jakarta. In Osaka, groundwater was used as a water resource during the period of rapid population increase before 1970, and consequently groundwater resources have been degraded. Hydraulic potential of groundwater has been recovered after the regulation for abstraction. However, it is still below sea level in the deeper aquifer (>20 m) of some regions, and higher Cl-, NH4+-N and PO43-P concentrations were detected in these regions. The results also suggest that shallower aquifer (>10 m) is influenced by infiltration of sewage to groundwater. In the Jakarta metropolitan area, current hydraulic potential is below sea level in because of prior excess abstraction of groundwater. As a result, the direction of groundwater flow is now downward in the coastal area. The distribution of Cl- and Mn concentration in groundwater suggests that the decline in hydraulic potential has caused the intrusion of seawater and shallow groundwater into deep groundwater. It implies an accumulation of contaminants in deep aquifers. On the other hands, NO3-N in groundwater is suggested to be attenuated by the processes of denitrification and dilution in the coastal area.

Investigating local variation in groundwater recharge along a topographic gradient, Walnut Creek, Iowa, USA

Science.gov (United States)

Schilling, K.E.

2009-01-01

Groundwater recharge is an important component to hydrologic studies but is known to vary considerably across the landscape. The purpose of this study was to examine 4 years of water-level behavior in a transect of four water-table wells installed at Walnut Creek, Iowa, USA to evaluate how groundwater recharge varied along a topographic gradient. The amount of daily water-table rise (WTR) in the wells was summed at monthly and annual scales and estimates of specific yield (Sy) were used to convert the WTR to recharge. At the floodplain site, Sy was estimated from the ratio of WTR to total rainfall and in the uplands was based on the ratio of baseflow to WTR. In the floodplain, where the water table is shallow, recharge occurred throughout the year whenever precipitation occurred. In upland areas where the water table was deeper, WTR occurred in a stepped fashion and varied by season. Results indicated that the greatest amount of water-table rise over the 4-year period was observed in the floodplain (379 mm), followed by the upland (211 mm) and sideslopes (122 mm). Incorporating spatial variability in recharge in a watershed will improve groundwater resource evaluation and flow and transport modeling. ?? Springer-Verlag 2008.

GSFLOW - Coupled Ground-Water and Surface-Water Flow Model Based on the Integration of the Precipitation-Runoff Modeling System (PRMS) and the Modular Ground-Water Flow Model (MODFLOW-2005)

Science.gov (United States)

Markstrom, Steven L.; Niswonger, Richard G.; Regan, R. Steven; Prudic, David E.; Barlow, Paul M.

2008-01-01

The need to assess the effects of variability in climate, biota, geology, and human activities on water availability and flow requires the development of models that couple two or more components of the hydrologic cycle. An integrated hydrologic model called GSFLOW (Ground-water and Surface-water FLOW) was developed to simulate coupled ground-water and surface-water resources. The new model is based on the integration of the U.S. Geological Survey Precipitation-Runoff Modeling System (PRMS) and the U.S. Geological Survey Modular Ground-Water Flow Model (MODFLOW). Additional model components were developed, and existing components were modified, to facilitate integration of the models. Methods were developed to route flow among the PRMS Hydrologic Response Units (HRUs) and between the HRUs and the MODFLOW finite-difference cells. This report describes the organization, concepts, design, and mathematical formulation of all GSFLOW model components. An important aspect of the integrated model design is its ability to conserve water mass and to provide comprehensive water budgets for a location of interest. This report includes descriptions of how water budgets are calculated for the integrated model and for individual model components. GSFLOW provides a robust modeling system for simulating flow through the hydrologic cycle, while allowing for future enhancements to incorporate other simulation techniques.

Salinization of the soil solution decreases the further accumulation of salt in the root zone of the halophyte Atriplex nummularia Lindl. growing above shallow saline groundwater.

Science.gov (United States)

Alharby, Hesham F; Colmer, Timothy D; Barrett-Lennard, Edward G

2018-01-01

Water use by plants in landscapes with shallow saline groundwater may lead to the accumulation of salt in the root zone. We examined the accumulation of Na + and Cl - around the roots of the halophyte Atriplex nummularia Lindl. and the impacts of this increasing salinity for stomatal conductance, water use and growth. Plants were grown in columns filled with a sand-clay mixture and connected at the bottom to reservoirs containing 20, 200 or 400 mM NaCl. At 21 d, Na + and Cl - concentrations in the soil solution were affected by the salinity of the groundwater, height above the water table and the root fresh mass density at various soil depths (P soil solution therefore had a feedback effect on further salinization within the root zone. © 2017 John Wiley & Sons Ltd.

Impact of climate changes during the last 5 million years on groundwater in basement aquifers.

Science.gov (United States)

Aquilina, Luc; Vergnaud-Ayraud, Virginie; Les Landes, Antoine Armandine; Pauwels, Hélène; Davy, Philippe; Pételet-Giraud, Emmanuelle; Labasque, Thierry; Roques, Clément; Chatton, Eliot; Bour, Olivier; Ben Maamar, Sarah; Dufresne, Alexis; Khaska, Mahmoud; Le Gal La Salle, Corinne; Barbecot, Florent

2015-09-22

Climate change is thought to have major effects on groundwater resources. There is however a limited knowledge of the impacts of past climate changes such as warm or glacial periods on groundwater although marine or glacial fluids may have circulated in basements during these periods. Geochemical investigations of groundwater at shallow depth (80-400 m) in the Armorican basement (western France) revealed three major phases of evolution: (1) Mio-Pliocene transgressions led to marine water introduction in the whole rock porosity through density and then diffusion processes, (2) intensive and rapid recharge after the glacial maximum down to several hundred meters depths, (3) a present-day regime of groundwater circulation limited to shallow depth. This work identifies important constraints regarding the mechanisms responsible for both marine and glacial fluid migrations and their preservation within a basement. It defines the first clear time scales of these processes and thus provides a unique case for understanding the effects of climate changes on hydrogeology in basements. It reveals that glacial water is supplied in significant amounts to deep aquifers even in permafrosted zones. It also emphasizes the vulnerability of modern groundwater hydrosystems to climate change as groundwater active aquifers is restricted to shallow depths.

Evaluation of drought impact on groundwater recharge rate using SWAT and Hydrus models on an agricultural island in western Japan

Directory of Open Access Journals (Sweden)

G. Jin

2015-06-01

Full Text Available Clarifying the variations of groundwater recharge response to a changing non-stationary hydrological process is important for efficiently managing groundwater resources, particularly in regions with limited precipitation that face the risk of water shortage. However, the rate of aquifer recharge is difficult to evaluate in terms of large annual-variations and frequency of flood events. In our research, we attempt to simulate related groundwater recharge processes under variable climate conditions using the SWAT Model, and validate the groundwater recharge using the Hydrus Model. The results show that annual average groundwater recharge comprised approximately 33% of total precipitation, however, larger variation was found for groundwater recharge and surface runoff compared to evapotranspiration, which fluctuated with annual precipitation variations. The annual variation of groundwater resources is shown to be related to precipitation. In spatial variations, the upstream is the main surface water discharge area; the middle and downstream areas are the main groundwater recharge areas. Validation by the Hydrus Model shows that the estimated and simulated groundwater levels are consistent in our research area. The groundwater level shows a quick response to the groundwater recharge rate. The rainfall intensity had a great impact on the changes of the groundwater level. Consequently, it was estimated that large spatial and temporal variation of the groundwater recharge rate would be affected by precipitation uncertainty in future.

Shallow Aquifer Methane Gas Source Assessment

Science.gov (United States)

Coffin, R. B.; Murgulet, D.; Rose, P. S.; Hay, R.

2014-12-01

Shale gas can contribute significantly to the world's energy demand. Hydraulic fracturing (fracking) on horizontal drill lines developed over the last 15 years makes formerly inaccessible hydrocarbons economically available. From 2000 to 2035 shale gas is predicted to rise from 1% to 46% of the total natural gas for the US. A vast energy resource is available in the United States. While there is a strong financial advantage to the application of fracking there is emerging concern about environmental impacts to groundwater and air quality from improper shale fracking operations. Elevated methane (CH4) concentrations have been observed in drinking water throughout the United States where there is active horizontal drilling. Horizontal drilling and hydraulic-fracturing can increase CH4 transport to aquifers, soil and the vadose zone. Seepage can also result from casing failure in older wells. However, there is strong evidence that elevated CH4 concentrations can be associated with topographic and hydrogeologic features, rather than shale-gas extraction processes. Carbon isotope geochemistry can be applied to study CH4source(s) in shallow vadose zone and groundwater systems. A preliminary TAMU-CC isotope data set from samples taken at different locations in southern Texas shows a wide range of CH4 signatures suggesting multiple sources of methane and carbon dioxide. These data are interpreted to distinguish regions with methane contributions from deep-sourced horizontal drilling versus shallow system microbial production. Development of a thorough environmental assessment using light isotope analysis can provide understanding of shallow anthropogenic versus natural CH4sources and assist in identifying regions that require remedial actions.