Abstract: The same techniques commonly used for remediation of sites contaminated with metals can... more Abstract: The same techniques commonly used for remediation of sites contaminated with metals can also be applied for sites contaminated with radionuclides. However, certain additional aspects have to be considered. Among them are the type of radionuclide, its half-life, and legal issues. Special attention has to be given to health protection of workers and people living close to the site. In certain cases, the noble gas radon can be an important issue requiring attention during remediation. For selecting an appropriate rehabilitation approach, the former use of the site needs to be known because the measures differ much for oil and gas production and treatment, uranium mining and milling, uranium enrichment or reprocessing, nuclear weapon testing or cleaning-up nuclear facilities after severe accidents.
Recently, Particle Swarm Optimization (PSO) techniques have attracted many researchers to optimiz... more Recently, Particle Swarm Optimization (PSO) techniques have attracted many researchers to optimize model parameters in several fields of research. This paper explains, for the first time, how to interface the hydroPSO R optimization package with the PHREEQC geochemical model, version 2.3.1. Sorption of metals on minerals is a key process in treatment water, natural aquatic environments, and other water related technologies. Sorption processes can be simulated by means of surface complexation models. However, determining thermodynamic constants for surface species from batch experiments requires a robust parameter estimation tool that does not get stuck in local minima. In this work, uranium at low concentrations was sorbed on quartz at different pH. Results show that hydroPSO delivers more reliable thermodynamic parameter values than PEST when both are coupled to PHREEQC using the same thermodynamic input data (Nair et al., 2014). Post-processing tools included in hydroPSO are helpf...
Groundwater arsenic (As) concentrations above 10 μg/L (World Health Organization; WHO standard) a... more Groundwater arsenic (As) concentrations above 10 μg/L (World Health Organization; WHO standard) are frequently found in the Titas Upazila in Bangladesh. This paper evaluates the groundwater chemistry and the mechanisms of As release acting in an underground aquifer in the middle-northeast part of the Titas Upazila in Bangladesh. Previous measurements and analyses of 43 groundwater samples from the region of interest (ROI) are used. Investigation is based on major ions and important trace elements, including total As and Fe in groundwater samples from shallow (8–36 m below ground level: mbgl) and deep (85–295 mbgl) tube wells in the aforementioned ROI. Principal hydrochemical facies are Ca–HCO3, with circumneutral pH. The different redox-sensitive constituents (e.g., As, Fe, Mn, NH4, and SO4) indicate overlapping redox zones, leading to differences regarding the redox equilibrium. Multivariate statistical analysis (factor analysis) was applied to reduce 20 chemical variables to four factors but still explain 81% of the total variance. The component loadings give hints as to the natural processes in the shallow aquifers, in which organic matter is a key reactant. The observed chemistry of As, Fe, and Mn can be explained by simultaneous equilibrium between Fe-oxide and SO4 reduction and an equilibrium of rhodochrosite precipitation/dissolution. A correlation test indicates the likeliness of As release by the reductive dissolution of Fe-oxides driven by the degradation of sediments organic matter. Other mechanisms could play a role in As release, albeit to a lesser extent. Reactive transport modeling using PHREEQC reproduced the observed chemistry evolution using simultaneous equilibrium between Fe-oxide and SO4 reduction and the equilibrium of rhodochrosite dissolution/precipitation alongside organic matter oxidation.
Increasing water demand in Kurdistan region has prompted the need to quantify the available groun... more Increasing water demand in Kurdistan region has prompted the need to quantify the available groundwater resources. In semi-arid region, the groundwater recharge estimation is difficult due to the large variability of hydrological events in space and time. Shaqlawa-Harrir basin covered an area about 1150 km2, and rainfall is the main source for replenishment of moisture and recharge of ground water in the area. Groundwater recharge estimated by employing water balance method based on climatic data, water table fluctuation method (WTF), where measured water table rises are correlated to recharge events (rainfall) and estimating the specific yield of the zone of fluctuation of the groundwater level is required, and environmental tracer (CMB) method depending on chloride concentration in rainfall and groundwater. Four temperature-based equations methods were used to estimate the potential evapotranspiration, actual evapotranspiration, water surplus and deficit. Horton’s infiltration cap...
The increasing urbanisation of originally agricultural and forested areas has made groundwater re... more The increasing urbanisation of originally agricultural and forested areas has made groundwater reserves subject to new influences that endanger their quality. While general influence of chemical fertilizers on the chemical composition of groundwater has been studied, the input of substances due to urban influence has been described primarily through examples of local contamination (Sewage seepage, garbage dumps, oil accidents, etc.). The cumulative effect of various factors, such as street traffic, sewage leaks, garden fertilisation, salt – spreading, etc. is usually expressed as “diffusive influence” on the quality of groundwater. The total effect of these factors and the spreading and exchange of chemical substances on the vertical and horizontal seepage are beeing studied in a mainly residential suburban region. The work is beeing carried out at the Technical University of Munich, as part of “Sonderforschungsbereich 81” of the “Deutsche Forschungs-gemeinschaft”.
Abstract: The same techniques commonly used for remediation of sites contaminated with metals can... more Abstract: The same techniques commonly used for remediation of sites contaminated with metals can also be applied for sites contaminated with radionuclides. However, certain additional aspects have to be considered. Among them are the type of radionuclide, its half-life, and legal issues. Special attention has to be given to health protection of workers and people living close to the site. In certain cases, the noble gas radon can be an important issue requiring attention during remediation. For selecting an appropriate rehabilitation approach, the former use of the site needs to be known because the measures differ much for oil and gas production and treatment, uranium mining and milling, uranium enrichment or reprocessing, nuclear weapon testing or cleaning-up nuclear facilities after severe accidents.
Recently, Particle Swarm Optimization (PSO) techniques have attracted many researchers to optimiz... more Recently, Particle Swarm Optimization (PSO) techniques have attracted many researchers to optimize model parameters in several fields of research. This paper explains, for the first time, how to interface the hydroPSO R optimization package with the PHREEQC geochemical model, version 2.3.1. Sorption of metals on minerals is a key process in treatment water, natural aquatic environments, and other water related technologies. Sorption processes can be simulated by means of surface complexation models. However, determining thermodynamic constants for surface species from batch experiments requires a robust parameter estimation tool that does not get stuck in local minima. In this work, uranium at low concentrations was sorbed on quartz at different pH. Results show that hydroPSO delivers more reliable thermodynamic parameter values than PEST when both are coupled to PHREEQC using the same thermodynamic input data (Nair et al., 2014). Post-processing tools included in hydroPSO are helpf...
Groundwater arsenic (As) concentrations above 10 μg/L (World Health Organization; WHO standard) a... more Groundwater arsenic (As) concentrations above 10 μg/L (World Health Organization; WHO standard) are frequently found in the Titas Upazila in Bangladesh. This paper evaluates the groundwater chemistry and the mechanisms of As release acting in an underground aquifer in the middle-northeast part of the Titas Upazila in Bangladesh. Previous measurements and analyses of 43 groundwater samples from the region of interest (ROI) are used. Investigation is based on major ions and important trace elements, including total As and Fe in groundwater samples from shallow (8–36 m below ground level: mbgl) and deep (85–295 mbgl) tube wells in the aforementioned ROI. Principal hydrochemical facies are Ca–HCO3, with circumneutral pH. The different redox-sensitive constituents (e.g., As, Fe, Mn, NH4, and SO4) indicate overlapping redox zones, leading to differences regarding the redox equilibrium. Multivariate statistical analysis (factor analysis) was applied to reduce 20 chemical variables to four factors but still explain 81% of the total variance. The component loadings give hints as to the natural processes in the shallow aquifers, in which organic matter is a key reactant. The observed chemistry of As, Fe, and Mn can be explained by simultaneous equilibrium between Fe-oxide and SO4 reduction and an equilibrium of rhodochrosite precipitation/dissolution. A correlation test indicates the likeliness of As release by the reductive dissolution of Fe-oxides driven by the degradation of sediments organic matter. Other mechanisms could play a role in As release, albeit to a lesser extent. Reactive transport modeling using PHREEQC reproduced the observed chemistry evolution using simultaneous equilibrium between Fe-oxide and SO4 reduction and the equilibrium of rhodochrosite dissolution/precipitation alongside organic matter oxidation.
Increasing water demand in Kurdistan region has prompted the need to quantify the available groun... more Increasing water demand in Kurdistan region has prompted the need to quantify the available groundwater resources. In semi-arid region, the groundwater recharge estimation is difficult due to the large variability of hydrological events in space and time. Shaqlawa-Harrir basin covered an area about 1150 km2, and rainfall is the main source for replenishment of moisture and recharge of ground water in the area. Groundwater recharge estimated by employing water balance method based on climatic data, water table fluctuation method (WTF), where measured water table rises are correlated to recharge events (rainfall) and estimating the specific yield of the zone of fluctuation of the groundwater level is required, and environmental tracer (CMB) method depending on chloride concentration in rainfall and groundwater. Four temperature-based equations methods were used to estimate the potential evapotranspiration, actual evapotranspiration, water surplus and deficit. Horton’s infiltration cap...
The increasing urbanisation of originally agricultural and forested areas has made groundwater re... more The increasing urbanisation of originally agricultural and forested areas has made groundwater reserves subject to new influences that endanger their quality. While general influence of chemical fertilizers on the chemical composition of groundwater has been studied, the input of substances due to urban influence has been described primarily through examples of local contamination (Sewage seepage, garbage dumps, oil accidents, etc.). The cumulative effect of various factors, such as street traffic, sewage leaks, garden fertilisation, salt – spreading, etc. is usually expressed as “diffusive influence” on the quality of groundwater. The total effect of these factors and the spreading and exchange of chemical substances on the vertical and horizontal seepage are beeing studied in a mainly residential suburban region. The work is beeing carried out at the Technical University of Munich, as part of “Sonderforschungsbereich 81” of the “Deutsche Forschungs-gemeinschaft”.
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