The Terrestrial Biogeochemical Cycle of barium: A proposed study to examine barium flux in Mojave Desert dust

Barium is a relatively abundant element in the crustal environments, Ba quantities can range from anywhere between 200ppm to 900ppm. Most common forms of Ba-minerals found in the environment are barite (BaSO4), witherite (BaCO3) and hollandite (Ba2Mn8O16). Ba is a useful element; it is used in various industries as a component in drilling fluids, in medical research and in manufacturing of various substances such as glass, ceramics, printing paper etc. However high quantity of Ba can be potentially toxic for the human body and can impair plant growth. It is therefore, important to review the terrestrial biogeochemical cycle of Ba, which is less studied and less understood than the oceanic biogeochemical cycle of Ba. Additionally, terrestrial systems face a diverse climate and are not as stable as the oceanic systems. Due to this the terrestrial biogeochemical cycle of barium is continuously changing and is more dynamic than the oceanic cycle. By studying one part of the cycle, i.e. the interaction of Ba in the atmosphere with the geosphere in the Mojave desert, NV, I propose a study to test the hypothesis that occurrence of, Ba-mineral, barite, in desert soils is mainly driven by dust flux. The proposal includes methodology for dust collection, sample analysis using XRF, XRD and SEM.EDS techniques and potential budget and timeline. Evidence supporting this claim would suggest that dust transports such minerals, affects the soil chemistry of desert soils and the interaction of various terrestrial systems

Public Health Service Drinking Water Standards

The Standards published herein have been promulgated as Public Health Regulations in the Federal Register. As such they became effective April 5, 1962, as the Standards to which drinking water and water supply systems used by carriers and others subject to Federal quarantine regulations must conform. The Division of Environmental Engineering and Food Protection is responsible for the application of these Standards to all carrier water supplies. These Standards supersede the Public Health Service Drinking Water Standards- 1946, as amended in 1956. The new Standards were developed with the assistance of an Advisory Committee appointed by the Public Health Service to revise the Standards of 1946. The Committee in its deliberations took cognizance of man\u27s changing environment and its effect on water supplies. Accordingly, new sections, such as one on radioactivity, have been added and substantive changes have been made elsewhere. The new Standards are in a form believed useful in evaluating the quality and safety of water supplies generally and they are hereby recommended for such use

Public Health Service Drinking Water Standards

The Standards published herein have been promulgated as Public Health Regulations in the Federal Register. As such they became effective April 5, 1962, as the Standards to which drinking water and water supply systems used by carriers and others subject to Federal quarantine regulations must conform. The Division of Environmental Engineering and Food Protection is responsible for the application of these Standards to all carrier water supplies. These Standards supersede the Public Health Service Drinking Water Standards- 1946, as amended in 1956. The new Standards were developed with the assistance of an Advisory Committee appointed by the Public Health Service to revise the Standards of 1946. The Committee in its deliberations took cognizance of man\u27s changing environment and its effect on water supplies. Accordingly, new sections, such as one on radioactivity, have been added and substantive changes have been made elsewhere. The new Standards are in a form believed useful in evaluating the quality and safety of water supplies generally and they are hereby recommended for such use

Hydration of Heavy Alkaline-Earth Cations Studied by Molecular Dynamics Simulations and X-ray Absorption Spectroscopy

The physicochemical properties of the three heaviest alkaline-earth cations, Sr2+, Ba2+, and Ra2+ in water have been studied by means of classical molecular dynamics (MD) simulations. A specific set of cation-water intermolecular potentials based on ab initio potential energy surfaces has been built on the basis of the hydrated ion concept. The polarizable and flexible model of water MCDHO2 was adopted. The theoretical-experimental comparison of structural, dynamical, energetic, and spectroscopical properties of Sr2+ and Ba2+ aqueous solutions is satisfactory, which supports the methodology developed. This good behavior allows a reasonable reliability for the predicted Ra2+ physicochemical data not experimentally determined yet. Simulated extended X-ray absorption fine-structure (EXAFS) and X-ray absorption near-edge spectroscopy spectra have been computed from the snapshots of the MD simulations and compared with the experimental information available for Sr2+ and Ba2+. For the Ra2+ case, the Ra L3-edge EXAFS spectrum is proposed. Structural and dynamical properties of the aqua ions for the three cations have been obtained and analyzed. Along the [M(H2O)n]m+ series, the M-O distance for the first-hydration shell is 2.57, 2.81, and 2.93 Å for Sr2+, Ba2+, and Ra2+, respectively. The hydration number also increases when one is going down along the group: 8.1, 9.4, and 9.8 for Sr2+, Ba2+, and Ra2+, respectively. Whereas [Sr(H2O)8]2+ is a typical aqua ion with a well-defined structure, the Ba2+ and Ra2+ hydration provides a picture exhibiting an average between the ennea- and the deca-hydration. These results show a similar chemical behavior of Ba2+ and Ra2+ aqueous solutions and support experimental studies on the removal of Ra-226 of aquifers by different techniques, where Ra2+ is replaced by Ba2+. A comparison of the heavy alkaline ions, Rb+ and Cs+, with the heavy alkaline-earth ions is made.Universidad de Sevilla US-126447

The Aquatic Biota and Groundwater Quality of Springs in the Lincoln Hills, Wisconsin Driftless, and Northern till Plains Sections of Illinois

ID: 8307INHS Technical Report prepared for Environmental Protection Trust Fund Commission and Illinois Department of Natural Resources Division of Energy and Environmental AssessmentU of I OnlyRestriction applied due to concern over geolocation information of springs on private property

Integrated treatment of brackish groundwater

As freshwater resources become more limited, Australian coastal cities have begun building seawater desalination plants, and inland communities have begun investigating the option of treating brackish groundwater to supplement their water supply. Membrane reverse osmosis (RO) is the leading technology applied in municipal desalination. Despite the advances in technology, membrane scaling is a common problem causing membrane failure, decline in membrane flux and deterioration of product water quality. Since inland plants cannot dispose of RO concentrate into the ocean, they operate at high water recovery in order to minimize the volume of RO concentrate. Antiscalants (AS) are often added during RO pretreatment to prevent membrane scaling. Water recovery percentages (Rw) are then limited by AS efficacy and yet large volumes of RO concentrate are frequently disposed of in evaporation ponds. Therefore, it is important to find novel technologies to combat scaling issues. The integration of a ‘High-pH pretreatment’ in inland desalination plants is a promising choice for facilitating the removal of scale-forming precursors and other contaminants negatively affecting the desalination process. In a comprehensive project, this study investigated the efficacy of ‘High-pH pretreatment’ for membrane scale control and the removal of specific pollutants such as boron. The first phase of the project highlighted the differences between inland and seawater desalination and critically reviewed the existing strategies for RO concentrate minimization towards zero liquid discharge (ZLD) in inland desalination. In contrast to previous studies, the groundwater and RO concentrate collected for these experiments had a magnesium concentration higher than the calcium concentration. Furthermore, no previous studies evaluated the ‘High-pH pretreatment’ on magnesium-dominated water as this study does. The investigation continued further to assess the efficacy and utilization of two scale control technologies: acid/AS addition and ‘High-pH pretreatment’. Therefore, the second phase of this study evaluated ‘High-pH pretreatment’ of a RO concentrate followed by secondary RO to increase overall water Rw in an existing inland desalination system. The results showed that the lime and soda ash softening treatment followed by pH readjustment and AS addition, allowed the overall water Rw to increase from 80 to 97%. Experimental trials also confirmed CaCO3 and CaO recovery from the precipitated sludge through CO2 gas injection to selectively dissolve magnesium. This success provided a further opportunity to explore ‘High-pH pretreatment’ of RO concentrate followed by other advanced desalination technologies such as air-gap membrane distillation (AGMD). In the third phase of the study, two scale control strategies, ‘High-pH pretreatment’ and AS addition, for RO concentrate minimization were further investigated in a labscale AGMD system. The results indicated that the first option was more efficient in terms of preventing scale build up in the AGMD system. Following ‘High-pH pretreatment’, pH readjustment and AS addition, the use of AGMD minimized the existing RO concentrate with a TDS level of 10.8 g/L by a concentration factor of 3.2. In addition, the ‘High pH-pretreatment’, using lime and soda ash, facilitated the operation of the AGMD system at a higher temperature, thus permeate flux also increased. Boron can also be present in groundwater due to natural or anthropogenic sources. It can produce harmful effects on human health depending on both the frequency and extent of exposure. Boron removal is considered to be very complex. In fact, it is largely unclear whether softening pretreatments can enhance boron removal in groundwater desalination systems. Therefore, the final phase of this study investigated the feasibility of ‘High-pH pretreatment’ for boron removal from magnesiumdominated groundwater samples obtained from an existing inland desalination facility. Before commencing the experiments, the brackish groundwater was spiked with 5 mg/L of boron. The results revealed that the lime and soda ash softening treatment achieved 33% boron removal by sorption of hydroxyborate ions onto precipitated magnesium silicate. An additional 9% boron removal was achieved with magnesium chloride addition before the softening treatment, or by a secondary polishing treatment by means of adsorption with MgO. This solution can safely facilitate compliance with strict boron standards in inland desalination plants using RO or electrodialysis technology. This study evaluated the efficacy of integrating a ‘High-pH pretreatment’ in inland desalination plants treating magnesium-dominated groundwater. The novel approach overcame AS limitations and increased freshwater Rw in the inland desalination plant. It also enabled partial removal of other contaminants such as boron. Since groundwater quality is site-specific, selection and optimization of the most suitable treatment for every single process must be based on raw water characteristics

Treating produced water from hydraulic fracturing: Composition effects on scale formation and desalination system selection

Produced water from unconventional gas and oil extraction may be hypersaline with uncommon combinations of dissolved ions. The aim of this analysis is to aid in the selection of produced water treatment technology by identifying the temperature, pH, and recovery ratio under which mineral solid formation from these produced waters is likely to occur. Eight samples of produced water from the Permian Basin and the Marcellus shale are discussed, with an average TDS of about 177 g/L but significant variability. Crystallization potential is quantified by the saturation index, and activity coefficients are calculated using the Pitzer model. The method is applied to estimate solid formation in the treatment of two design case samples: a 183 g/L sample representing the Permian Basin water and a 145 g/L sample representing the Marcellus. Without pretreatment, the most likely solids to form, defined by highest saturation index, are: CaCO[subscript 3], FeCO[subscript 3], MgCO[subscript 3], MnCO[subscript 3], SrCO[subscript 3], BaSO[subscript 4], CaSO[subscript 4], MgSO[subscript 4] and SrSO[subscript 4]. Some options for mitigating the formation of these scales are discussed. With appropriate pretreatment, it is estimated that recovery ratios of as high as 40–50% are achievable before NaCl, a major constituent, is likely to limit further concentration without significant crystallization.Center for Clean Water and Clean Energy at MIT and KFUPM (Project R4-CW-08)MIT Energy InitiativeMIT Martin Family Society of Fellows for Sustainabilit