Species In Groundwater Research Articles

Heavy metal distribution trend and speciation in groundwaters within the lower cross river hydrological basin, SE-Nigeria

Heavy metal distribution trend and speciation in groundwaters within the lower cross river hydrological basin, SE-Nigeria

Ferrous sulfide nanoparticles control mercury speciation and bioavailability to methylating bacteria in contaminated groundwater: Impacts of mercury species

Mercury speciation in groundwater affects its removal effectiveness and methylation potential. Yet, most studies focus on the removal of inorganic dissolved Hg(II) and few studies explored the mercury methylation before and after the treatment. This study comprehensively explored the removal performance of three model mercury species, namely, dissolved inorganic divalent Hg (Hg(II), including free Hg2+ and Hg2+ complexes with Cl− and OH−), Hg2+ bound to dissolved organic matter (Hg-DOM), and HgS nanoparticles by FeS nanoparticles and further investigated the resultant impacts on the microbial methylation of Hg. Among three different stabilizers (starch, carboxymethyl cellulose (CMC), carboxymethyl starch (CMS)), CMC stabilized FeS nanoparticles (CMC-FeS) demonstrated best physical stability and highest mercury uptake. The CMC-FeS nanoparticles efficiently immobilized the three mercury species within 20 h. The sorption isotherm data of Hg(II) and Hg-DOM were well fitted by the dual-mode isotherm model and the maximum sorption capacities were 3358.28 and 2396.38 mg/g, respectively. Hg(II) and Hg-DOM were predominantly removed via ion exchange, chemical precipitation, and surface complexation whereas HgS was mainly immobilized through heteroaggregation. The simple treatment greatly reduced the bioavailable Hg species, thereby diminishing the net MeHg production by 70.2 %, 32.7 %, and 11.3 %, respectively. This study provides compelling evidence that FeS nanoparticles efficiently removed various mercury species in groundwater and remarkably inhibited the microbial methylation of mercury.

Precipitation of arsenic-bearing solids as a secondary control on arsenic speciation in groundwater: Evidence from field study and geochemical analysis

Among the mechanisms controlling elevated arsenic (As) speciation in groundwater, dissolution-precipitation of As-bearing solids, possibly as colloids, has not been systematically evaluated even though reported groundwater saturation states often indicate super- or near-saturation with respect to multiple solids. In this contribution, a detailed geochemical analysis was performed on well-constrained groundwater quality data collected through (a) sustained sampling (n = 84) over 2.5 y at a newly-identified site in the middle Gangetic plain of India; and (b) metadata analysis on studies conducted worldwide (n = 414). Groundwater saturation indices, speciation (EH-pH), and mineral solubilities (logC-pH) were calculated, consistent with a carefully-selected and updated thermodynamic database. Results suggest that under oxidizing conditions, secondary precipitation of solids similar to scorodite [FeAsO4·2H2O(s)] and pharmacolite [CaHAsO4·2H2O(s)] influences the As(V) concentrations in groundwater. In addition, groundwater at the investigated site was saturated with calcite [CaCO3(s)] and rhodochrosite [MnCO3(s)]. Evidence of colloidal forms of As-containing and As-free solids was found from SEM-EDS characterization of solids collected on 0.2 μm filter membranes used to sample groundwater. XPS analysis showed that the relative As(V) and As(III) signatures in these solids were consistent with the prevalence of dissolved As(V) and As(III) in groundwater, independently quantified using IC-ICP-MS. HR-TEM-SAED characterization of these solids indicated the possible presence of poorly crystalline scorodite- and pharmacolite-like phases along with calcite and lepidocrocite [γ–FeOOH(s)] in a predominantly amorphous matrix. Also, a possible role of Mn in inducing As immobilization in calcite was suggested with the identification of ∼ 1:1 Mn:As atomic ratios in these solids, consistent with significant (p < 0.05) correlation of dissolved total As and total Mn. These findings imply that solubility-driven secondary processes may exert additional controls on the eventual fate and transport of arsenic in mixed-redox state shallow groundwaters, apart from the known primary mobilization mechanisms. To the best of our knowledge, this is the first study that has characterized colloidal arsenic in groundwater and related it to prevailing mechanisms.

Establishing a weighted methodology for human health risk assessment of cadmium based on its equilibrium speciation in groundwater

A weighted human health risk evaluation methodology that integrated fuzzy-synthetic evaluation and chemical equilibrium simulation was proposed. The method was applied to study the potential toxicity and morphological characteristics of cadmium (Cd) species in groundwater. The concentrations and activities of 15 Cd (II) ion species were conducted by Visual MINTEQ for optimizing average daily dose through ingestion pathway in the health risk model. Both carcinogenic and non-carcinogenic health risk of Cd (II) species for adults and children were conducted. The health risk assessment revealed that metal species of Cd2+ and CdCl + posed carcinogenic risk to adults. The carcinogenic risk of Cd2+ with the value 8.03E-04 and 5.43E-04 for adults and children demonstrated high carcinogenicity, respectively. Non-carcinogenic risk values for Cd (II) ion species were all less than 1 except for Cd2+. It was noteworthy that the non-carcinogenic risk index of Cd2+ and CdCl+ were slightly higher than those after weight assignment. Besides, the investigation indicated that conventional risk assessment may overestimate or underestimate risk levels and the health risk of Cd (II) species principally depended on their metal speciation associated affecting factor of pH in groundwater. The Nemero index for Cd (II) species showed a slight contamination accounted for a percentage of 13.33% of the sampling areas. Therefore, the methodology identified Cd2+ and CdCl + as the targeted species for contamination through the assessment. This strategy provided a solution of correlation degree optimization for groundwater health risk assessment and a reference for the administration to manage groundwater pollution.

Arsenic-Bearing Serpentine-Group Minerals: Mineral Synthesis with Insights for the Arsenic Cycle

AbstractWhen present at elevated levels in drinking water, arsenic is toxic, and magnesian clays are gaining recognition as a source of elevated arsenic in groundwater. In the crust and upper mantle of Earth, arsenic incorporation into clay minerals is influenced by geochemical conditions associated with hydrothermal fluids and metamorphic processes (e.g. serpentinization), meaning that As is a useful tracer of fluid-flow in the deep Earth. To improve understanding of arsenic speciation in groundwater, sediments, soils, and hydrothermal-metamorphic systems, the present study examined arsenic incorporation into magnesian clays by synthesis of serpentine minerals (200oC, 10 d) with varied concentrations of Si, Al, As5+, and As3+. The synthesis experiments produced two distinct crystal types, tubular and platy serpentines, each with 10–15% randomly interstratified talc layers. X-ray absorption spectroscopy indicated that As5+ and As3+ occurred in the tetrahedral sheet. Single-crystal analysis revealed that tubular crystals contained up to 1 wt.% arsenic [Mg2.8(Si1.8As0.2)O5(OH)4] (mean 0.2 wt.% As). The mean composition of platy, high-Al crystals is (Mg1.8Al0.7)(Si2.0)O5(OH)4, and that of platy, medium-Al crystals with As3+ is (Mg2.07Al0.52) (Si1.97As3+0.03)O5(OH)4. Charge, geometry, and radius of tetrahedral AsO43– oxyanions are similar to tetrahedral SiO44–, and this facilitates fixation of As5+ into the tetrahedral sheet of clay minerals. The geometry and size of the larger As3+ in tetrahedral sites (as a pyramidal AsO33– oxyanion) may limit incorporation relative to As5+. Arsenic-bearing Mg clays crystallize in alkaline environments where AsO43– or AsO33– are the dominant As species and where high pH accompanies crystallization of serpentine, talc, chlorite, or Mg-smectite. The presence of tetrahedral As in these clays raises the possibility of tetrahedral As in other Mg clays (e.g. sepiolite or kerolite) as well.

Total arsenic and inorganic arsenic speciation in groundwater intended for human consumption in Uruguay: Correlation with fluoride, iron, manganese and sulfate

Medical Geology is a growing field in Uruguay and the groundwater quality has been the focus of multiple studies, being As levels one of its main concerns. The aim of this study was the application of analytical methodologies for the assessment of total arsenic and inorganic arsenic species, fluoride, iron, manganese and sulfate in groundwater samples from private wells, used for human consumption, and to evaluate the possible correlations among these parameters. The accuracy of the methods was ensured by using certified reference materials. A total of 48 groundwater samples from Uruguay were analyzed. The concentration ranges found were: tAs (1.72–120.48) μg L−1, F− (0.024–1.528) mg L−1, Fe (0.62–211.38) μg L−1 and Mn (0.11–8.705) μg L−1. Almost half of the samples presented tAs concentration levels above those recommended by WHO for drinking water (10 μg L−1), with the corresponding risks for human health. Results showed higher As(V) levels in the samples, which is in agreement with the oxidant conditions of the wells. Pearson correlations were performed, resulting in strong positive correlations for As/F−, As(V)/F− and As(V)/SO42−. As levels in groundwater and its relationship with other inorganic parameters, should be deeply studied to prevent long-term health effects.

Complexation of UO2(CO3)34- with Mg2+ at varying temperatures and its effect on U(vi) speciation in groundwater and seawater.

The ternary alkaline earth metal uranyl tricarbonate complexes, MnUO2(CO3)32n-4 (M = Mg and Ca), have been considered to be the major U(vi) species contributing to uranium mobility in natural water. Although MgUO2(CO3)32- can account for a substantial portion of U(vi) in a Mg2+-rich aqueous system and most processes regarding uranium are subjected to variable temperatures, chemical thermodynamic data for the prediction of the formation of MgUO2(CO3)32- at variable temperatures are still unknown. To fill the knowledge gap in the current chemical thermodynamic database, ultraviolet/visible (UV/Vis) absorption spectroscopy was employed to determine the formation constants (log K') of MgUO2(CO3)32- at varying temperatures of 10-85 °C in 0.5 mol kg-1 NaCl. The formation constants at infinite dilution, log K°, were obtained with specific ion interaction theory (SIT), and an increasing tendency of log K° with temperature was observed. Using calorimetric titration, the endothermic molar enthalpy of reaction (ΔrHm) of Mg2+ complexation with UO2(CO3)34- was determined at 25 °C. According to the chemical thermodynamic data obtained in this work, approximation models for the prediction of the temperature-dependent formation constant at a given temperature were examined and the constant enthalpy approximation with modification to the isoelectric reaction showed a satisfactory agreement with our experimental results. Finally, the effects of temperature on U(vi) speciation in Mg2+-rich groundwater and U(vi) extraction from seawater by amidoxime derivatives were examined. For the first time, this work provides important chemical thermodynamic data of MgUO2(CO3)32n-4 to assess the impact of temperature on U(vi) behaviour in groundwater and seawater.

Formation of CaUO2(CO3)32- and Ca2UO2(CO3)3(aq) complexes at variable temperatures (10-70 °C).

The ternary complexation of calcium uranyl tricarbonate species, CaUO2(CO3)32- and Ca2UO2(CO3)3(aq), which are the predominant U(vi) complexes in groundwater and seawater, was investigated at variable temperatures from 10 to 70 °C. Time-resolved laser fluorescence spectroscopy (TRLFS), calcium ion-selective electrode potentiometry, and ultraviolet/visible (UV/Vis) absorption spectroscopy were complementarily employed to determine the formation constants (log Kx13, x = 1 and 2 for mono- and dicalcium complexes, respectively). at infinite dilution (zero ionic strength) was determined by correction using specific ion interaction theory (SIT), and an increasing tendency of with temperature was observed. In addition, the molar enthalpy of complexation (ΔrHm) was measured by calorimetry at 25 °C. Based on thermodynamic data obtained in this work, the approximation models were examined for the prediction of the temperature effect on the complexation, and the constant enthalpy approximation with the chemical complexation reaction modified to an isoelectric reaction showed a satisfactory prediction of in the temperature range of 10-70 °C. Finally, the results of U(vi) speciation in groundwater indicated that the dominance of calcium uranyl tricarbonate complexes would be weakened at elevated temperatures by the strongly enhanced hydrolysis of U(vi).

Establishing a method to assess comprehensive effect of gradient variation human health risk to metal speciation in groundwater

A method was proposed to evaluate comprehensive effects of pHs and total metal concentration (TMC) variation for metal speciation human health risk in groundwater. The method used for the health assessment considered comprehensive and mutative effects caused by oral ingestion of groundwater based on human health risk assessment model and MINTEQ simulation. The results demonstrated that the dissolution rate of Ni2+ was affected by pH and Ni total concentration (total-Ni). With the increase of pH, the Ni2+ dissolved rate was smaller in the higher total-Ni at same pH. Ni2+ was dominant components contributed to health risk in groundwater. With the increase of pH in various total-Ni, HINi keep constant at first, and then decreased gradually. The HINi values of Ni speciation above acceptable level only in high total-Ni with alkaline conditions. The obtained results to verify that metals speciation were determined in health risk, and variation factors (pH and metal total concentration) played important role in risk estimation. These results provide basic information of heavy metal pollution control as well as remediation management.

Mercury in the unconfined aquifer of the Isonzo/Soča River alluvial plain downstream from the Idrija mining area

This work aims at evaluating mercury (Hg) occurrence, spatial distribution and speciation in groundwater of the Isonzo/Soča River upper alluvial plain downstream from the Idrija Hg mine (Western Slovenia). Several wells and piezometers were sampled both in static and dynamic mode. Total (THg) and filtered (FHg) concentrations were generally higher in static (THg, 1.87–855 ng L−1; FHg, 0.20–13.61 ng L−1) than in dynamic mode (THg, 0.08–78.77 ng L−1; FHg, 0.28–6.65 ng L−1). The estimated background value accounts for 2–3 ng L−1.On the basis of hydrochemistry and isotopic composition, the main sources of groundwater were established. Hg concentrations in the Slovenian sector, supplied by local rainfall, are comparable to values measured close to the Isonzo River. Possible further Hg local sources have been suggested. Stability field analysis for the aqueous Hg species revealed that in the presence of chloride Hg solubility may be increased by the formation of chlorocomplexes. Mercury that rarely enters reduced surrounding conditions can be bound to sulphur to form polysulphide species depending on the pH of water.Since Hg-contaminated alluvial sediments of the Isonzo River may act as a secondary Hg source in groundwater, a borehole was dug down to the water table. Mercury content and speciation revealed that cinnabar (HgS) is the prevalent form followed by the matrix-bound Hg (Hgbound). Variations of the physico-chemical boundary conditions, as well as the raising/lowering of the water table, may be locally responsible for the slight variability of Hg concentrations in the aquifer.

Rare earth elements sorption to iron oxyhydroxide: Model development and application to groundwater

Iron oxyhydroxides are among the most important colloids that control rare earth elements (REE) concentrations and transport in natural hydrosystems. In this study, REE surface complexation to iron oxyhydroxides (Fe(OH)3(a)) was described by using the Donnan diffuse layer model and a two-site (i.e. ≡FesOH and ≡FewOH) model. The specific surface area and pH of zero charge were fixed as 100000 m2/mol and 8.0, respectively. The surface site density for weak and strong binding sites were fixed at 0.1 moL/mol Fe (≡FewOH) and 0.001 moL/mol Fe (≡FesOH) respectively. The two site types were used with pKa1int = 7.29 and pKa2int = 8.93. Using linear free energy relationship, the estimated equilibrium surface complexation constants (log K) increased from light REE (LREE) to heavy REE (HREE). Results of REE modeling calculation using the determined log K revealed a good fit of experimental data, showing an order of sorption on iron oxyhydroxides: HREE > MREE > LREE and preferential sorption of HREE at a lower pH. However, sorption edges only showed a slight change with ionic strength (0.1–0.7 moL/L) for the whole REE series. The generalized model was subsequently used to evaluate the impact of iron oxyhydroxides on REE speciation in groundwater. Application of the model to “model groundwater” showed that iron oxyhydroxide complexes of REE were significant in near neutral and weakly alkaline pH. This study contributes to putting forward a comprehensive database which would be useful for the application of surface complexation model to describe REE sorption by amorphous ferric hydroxides in nature.

The geochemistry of uranium occurrences and speciation in groundwater of Chinnar sub basin, South India

An attempt has been made in Chinnar sub basin of Dharmapuri district, South India to isolate the geochemistry of uranium occurrences in groundwater. The geology of the area is mainly of charnockite and granite gneiss. Groundwater samples were collected for two different seasons post and pre monsoon in two different litho units (granite gneiss and charnockite) and analysed for major, minor and uranium concentrations. Higher uranium (18.45 μg L−1) has been recorded during pre monsoon season in granite gneiss with increasing pH. The saturation index calculation for the groundwater isolated minerals like uaraninite, coffinite, haiweeite and soddyite to be precipitating and uranium oxides like UO2.25, UO2.25beta, UO2.33beta as oversaturated. The Eh-pH diagram attempted represents solubility of uraninite within the pH range of 6.0 to 8.0. The study isolate uranium in groundwater of the study area is controlled by the presence of (U4O9) uranium oxide.

Comparing Modeled and Measured Mercury Speciation in Contaminated Groundwater: Importance of Dissolved Organic Matter Composition.

In addition to analytical speciation, reliable Hg species modeling is crucial for predicting the mobility and toxicity of Hg, but geochemical speciation codes have not yet been tested for their prediction accuracy. Our study compares analyses of Hg species in highly Hg-contaminated groundwater (Hgtot: 0.02-4 μmol·L(-1)) at three sites with predictions of Hg speciation obtained from three geochemical codes (WHAM, Visual MINTEQ, PHREEQC) with and without implementation of Hg complexation by dissolved organic matter (DOM). Samples were analyzed for chemical composition, elemental, inorganic, and DOM-bound Hg (Hg(0), Hginorg, HgDOM). Hg-DOM complexation was modeled using three approaches: binding to humic/fulvic acids, binding to thiol-groups, or a combination of both. Results of Hg(0) modeling were poor in all scenarios. Prediction accuracy for Hginorg and HgDOM strongly depended on the assumed DOM composition. Best results were achieved when weaker binding sites, simulated by WHAMs DOM submodel, were combined with strongly binding thiol groups. Indications were found that thiol-DOM ratios in groundwater are likely to be lower than in surface water, highlighting the need for analytical thiol quantification in groundwater DOM. This study shows that DOM quality is a crucial parameter for prediction of Hg speciation in groundwater by means of geochemical modeling.

Corrosion behaviour of copper under biotic and abiotic conditions in anoxic ground water: electrochemical study

Finnish nuclear waste disposal program proposes to dispose spent nuclear fuel in tightly sealed copper canisters in a geological repository; here, copper acts as a corrosion barrier. The key argument for such materials selection is that copper is resistant to corrosion in oxygen-free water. However, the presence and colonization of microbial species in ground water in the geological repository may initiate, facilitate and accelerate corrosion of copper under such conditions. In this study, the results from experiments that were designed to simulate the final stage of the deep geological nuclear waste repository, when the temperature has already stabilized to the level of the surrounding bedrock and all oxygen included at the construction stage has been consumed, are reported, both in the presence and absence of micro-organisms retrieved from the repository site. The experiments were performed for 10 months, during which the copper specimens were subjected to electrochemical measurements. After the tests, the specimens were investigated in terms of microstructure and weight changes, while the test media was characterized with respect to selected chemical species. Analysis concentrated on EIS data in the light of results obtained by other methods. In the presence of micro-organisms, e.g., sulphate-reducing bacteria, the development of Cu2S is the primary surface process on copper specimens, with its corrosion protection properties being regulated by the growth of the biofilm. As compared to two-layered Cu2O films that grow on the specimen surfaces in the absence of bacteria, Cu2S films were essentially less susceptible for the attack by Cl−. Under abiotic conditions, passivity breakdown by Cl− resulting in the localized type of attack detected on the surfaces is the probable reason for an essentially higher corrosion rate than in the biotic system.

Determination of total arsenic and speciation of As(III) and As(V) in ground water by charged particle activation analysis

The ability of charged particle activation analysis (CPAA) to determine at trace level of arsenic directly in ground water has been reported in this paper. The CPAA has been applied to determine total arsenic, As(III) and As(V) species in ground water collected from eastern part of India using ~16 MeV proton beam. The speciation of As(III) and As(V) was carried out using DOWEX 1 × 8 resin. The total arsenic concentrations were also determined by other conventional techniques for validation and values are in good agreement with that obtained by CPAA. As(III) concentration was found to be double than that of As(V) in ground water sample.

Heavy Metal Assessment of Groundwaters in the Vicinities of Dumpsites in Calabar Metropolis, South-Eastern Nigeria

Assessment of heavy metal contents in groundwater in vicinities of dumpsites within the Calabar metropolis was carried out. The dumpsites included those located at Akai-Effa, Anantigha, Bogobiri, LEMNA road and Marina beach. The choice of dumpsites was guided by magnitude of operation, history and longevity as related to possible metal speciation, leachate fate and disperssivity. Studied heavy metals included; Fe, Mn, Cu, Zn, Pb, Cd, Cr, Ni, Co and As. Results and interpretation revealed generally the highest concentration of selected metals to be in the vicinities of the Akai-Effa dumpsite (an abandoned and reclaimed automobile repair and scrap metal dumpsite with a long history of operation). This was followed by the Bogobiri dumpsite with a relatively shorter period of operation but a history of frequent incineration of refuse. Hydrochemical modelling indicated the aqueous species of metals to be predominantly free mobile ions, oxides and hydroxides. Other multi-element complexes were also identified at varying degrees of dominance and these were largely hydrated arsenates. Metal speciation in groundwater was adjudged to be controlled by dumpsites longevity, refuse type and associated activities. Current levels and speciation trend create a need for temporal and spatial monitoring for possible hazard prognosis and human health concerns.

Characterization of groundwater composition in Punjab state with special emphasis on uranium content, speciation and mobility

Abstract Groundwaters (borewell and handpump) were sampled from two districts (Bathinda and Mansa) of Punjab state and analyzed for their major ionic concentrations and uranium isotope compositions in order to assess the possible origins of the waters and water–rock interactions that occurred in the deep aquifer system. The major ionic concentrations of waters were plotted on a Piper diagram and grouped into four dominant hydrochemical facies as (Na+K)-SO4+Cl type (69% – 73%), (Ca+Mg)-SO4+Cl type (6% – 21%), (Ca+Mg)–HCO3 type (4% – 6%) and (Na+K)-HCO3 type (2% – 19%). It was observed that mobility of uranium in groundwater was very much influenced by TDS (total dissolved solids). To investigate the various mechanisms for deriving the elevated uranium concentrations in groundwater, 234U/238U activity ratios (ARs) were calculated using the determined activity levels of 234U and 238U. The mean ARs was found to be near unity (i.e. secular equilibrium) in the study regions confirmed that uranium in groundwaters was mainly resulted from its host/parent rocks through weathering processes. The concentration of HCO3 − in ground water showed one order of magnitude higher than the total dissolved SiO2 indicates that carbonate weathering was the dominant process due to major water–rock interaction. The uranium speciation in groundwaters was investigated by an equilibrium model calculation using MEDUSA (make equilibrium diagrams using sophisticated algorithms) under the influence of redox conditions and complexant concentration. At the observed range of pH values, the predominant redox speciation of uranium was observed as hydroxo-carbonato complexes of (UO2)2(CO3)(OH)3 − and hydroxyl complexes of UO2(OH)3 − which might be caused for increasing the solubility of uranium. Due to very low concentration of phosphate in groundwater, its effects on U(VI)-aqueous speciation was negligible.

Response to Comment on “Iodine-129 and Iodine-127 Speciation in Groundwater at Hanford Site, U.S.: Iodate Incorporation into Calcite”

ADVERTISEMENT RETURN TO ISSUEPREVCorrespondence/Rebut...Correspondence/RebuttalNEXTResponse to Comment on “Iodine-129 and Iodine-127 Speciation in Groundwater at Hanford Site, U.S.: Iodate Incorporation into Calcite”Saijin Zhang*†, Chen Xu†, Danielle Creeley†, Yi-Fang Ho†, Hsiu-Ping Li†, Russell Grandbois†, Kathleen A. Schwehr†, Daniel I. Kaplan‡, Chris M. Yeager§, Dawn Wellman∥, and Peter H. Santschi†View Author Information† Department of Marine Science, Texas A&M University at Galveston, Texas 77554, United States‡ Savannah River National Laboratory (SRNL), Aiken, South Carolina 29802 , United States§ Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87545, United States∥ Pacific Northwest National Laboratory (PNNL), Richland, Washington 99352, United States*Corresponding author at: 200 Seawolf Pkwy, Bldg. 3029, Galveston TX, USA 77554. Tel +1 409 354 4530; fax: + 1 409 740 4787 E-mail address: [email protected]Cite this: Environ. Sci. Technol. 2013, 47, 22, 13205–13206Publication Date (Web):November 4, 2013Publication History Published online4 November 2013Published inissue 19 November 2013https://doi.org/10.1021/es4046132Copyright © 2013 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views381Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (145 KB) Get e-AlertsSUBJECTS:Calcite,Freezing,Groundwaters,Iodine,Precipitation Get e-Alerts

Comment on “Iodine-129 and Iodine-127 Speciation in Groundwater at the Hanford Site, U.S.: Iodate Incorporation into Calcite”

ADVERTISEMENT RETURN TO ISSUEPREVCorrespondence/Rebut...Correspondence/RebuttalNEXTComment on “Iodine-129 and Iodine-127 Speciation in Groundwater at the Hanford Site, U.S.: Iodate Incorporation into Calcite”Zunli Lu*View Author Information Department of Earth Sciences, Syracuse University, Syracuse, New York, 13244, United States*E-mail: [email protected]Cite this: Environ. Sci. Technol. 2013, 47, 22, 13203–13204Publication Date (Web):November 4, 2013Publication History Published online4 November 2013Published inissue 19 November 2013https://doi.org/10.1021/es404049sCopyright © 2013 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views381Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (131 KB) Get e-AlertsSUBJECTS:Calcite,Freezing,Groundwaters,Iodine,Remediation Get e-Alerts

Iodine-129 and Iodine-127 Speciation in Groundwater at the Hanford Site, U.S.: Iodate Incorporation into Calcite

The geochemical transport and fate of radioiodine depends largely on its chemical speciation that is greatly affected by environmental factors. This study reports, for the first time, the speciation of stable and radioactive iodine in the groundwater from the Hanford Site. Iodate was the dominant species and accounted for up to 84% of the total iodine present. The alkaline pH (pH ∼ 8) and predominantly oxidizing environment may have prevented reduction of the iodate. In addition, groundwater samples were found to have large amounts of calcite precipitate which were likely formed as a result of CO2 degassing during removal from the deep subsurface (>70m depth). Further analyses indicated that between 7 and 40% of the dissolved (127)I and (129)I that was originally in the groundwater had coprecipitated in the calcite. Iodate was the main species incorporated into calcite and this incorporation process could be impeded by elevating the pH and decreasing ionic strength in groundwater. This study provides critical information for predicting the long-term fate and transport of (129)I. Furthermore, the common sampling artifact resulting in the precipitation of calcite by degassing CO2, had the unintended consequence of providing insight into a potential solution for the in situ remediation of groundwater (129)I.