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Tarun K Dalai - One of the best experts on this subject based on the ideXlab platform.
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massive production of heavy metals in the ganga hooghly river estuary india global importance of Solute Particle interaction and enhanced metal fluxes to the oceans
Geochimica et Cosmochimica Acta, 2018Co-Authors: Saumik Samanta, Tarun K DalaiAbstract:Abstract The Ganga River System is a major contributor to the global sediment and water discharge to the oceans. The estuary of Ganga (Hooghly) River in India is under increasing influence of anthropogenic contributions via discharge of the industrial and urban effluents. Here we document, based on the investigation of water and suspended sediment samples collected during six periods over two years, that there is extensive production of heavy metals (Co, Ni and Cu) in the estuary such that the annual dissolved fluxes of metals from the Hooghly River are enhanced by up to 230–1770%. Furthermore, the estuarine dissolved metal fluxes, when normalized with water fluxes, are the highest among estuaries of the major rivers in the world. Our simultaneous data on the dissolved, suspended particulate and exchangeable phases allow us to identify the ion-exchange process (coupled adsorption and desorption) as the dominant contributor to the generation of heavy metals in the middle and lower estuary where the estimated anthropogenic contribution is negligible. The estimated contributions from the groundwater are also insufficient to explain the measured metal concentrations in the estuary. A strong positive correlation that is observed between the dissolved heavy metal fluxes and the suspended particulate matter (SPM) fluxes, after normalizing them with the water fluxes, for estuaries of the major global rivers imply that the Solute-Particle interaction is a globally significant process in the estuarine production of metals. Based on this correlation that is observed for major estuaries around the world, we demonstrate that the South Asian Rivers which supply only ∼9% of the global river water discharge but carry elevated SPM load, contribute a far more significant proportion (∼40 ± 2% Ni and 15 ± 1% Cu) to the global supply of the dissolved metals from the rivers.
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dissolved and particulate barium in the ganga hooghly river estuary india Solute Particle interactions and the enhanced dissolved flux to the oceans
Geochimica et Cosmochimica Acta, 2016Co-Authors: Saumik Samanta, Tarun K DalaiAbstract:Abstract In this study, the sources and the cycling of Ba have been evaluated in the Ganga (Hooghly) River estuary using the composition of the suspended sediments and the water samples collected during six seasons of contrasting water discharge over two years (2012 and 2013). In addition, the data on the samples of groundwater from areas adjacent to the estuary, and the industrial effluent water and urban wastewater draining into the estuary are presented. Selective extraction experiments were also performed on the suspended particulate matter of two seasons to assess the distribution of exchangeable concentrations of major ions and Ba. In the mixing zone, the variation patterns of the dissolved Ba concentrations show mid-salinity maxima and are similar to the patterns of variation of the particulate Mg/Al and Mg/Fe, suggesting that the production of dissolved Ba is linked to the adsorption of major ions on to the clay minerals and Fe–Mn oxyhydroxides in the particulate matter. The inference of coupled adsorption–desorption processes is supported by the observations that the particulate Ba/Mg and Ba/K ratios exhibit significant to strong negative correlations with the concentrations of Al, Fe and Mn. The observations of mid-salinity maxima for the concentrations of exchangeable Mg and K, and of the exchangeable Ba concentrations that decrease with salinity provide strong evidence that the Solute-Particle interactions is the major driver in regulating the dissolved Ba distributions in the estuary. The estimates of the quantity of desorbed Ba based on three different approaches suggest that desorption is sufficient to account for the calculated excess Ba (Baxs) concentrations. The contribution of Ba to the dissolved load via dissolution of the particulate carbonate phases is minor, up to 3% of the maximum Baxs concentrations. The estimates of anthropogenic contributions are insignificant, and account for ⩽2% of maximum Baxs in the estuary. Groundwater contributions are less significant and account for up to 5% of the annual Ba flux from the Hooghly estuary. The estimates of Ba flux show that annually (1.5–1.9) × 107 moles of Ba is transported by the Hooghly River. About (3.6–4.3) × 107 moles of Ba is generated annually in the estuary through desorption. Added together, the desorbed and riverine Ba fluxes generate a total Ba flux of (5.1–6.2) × 107 moles per year. Thus, the Solute-Particle interactions enhance the riverine Ba flux by >300%. A compilation of the available data shows that the enhancement of the riverine Ba flux and the fractions of desorbed Ba flux scale with (particulate matter flux/water flux) ratio in several estuaries of the world, suggesting that the process of Solute-Particle interactions is a major driver for the estuarine production of Ba on a global scale. Among the rivers considered in this study, the estuaries of the Hooghly River and the Ganges–Brahmaputra rivers, characterized by very high (sediment flux/water flux) ratio, depict the highest increase in the riverine Ba flux. This unique feature of the Ganga River system is inferred to be resulting from the collective impact of the tectonic activity and the monsoonal rainfall in the catchment areas.
Saumik Samanta - One of the best experts on this subject based on the ideXlab platform.
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massive production of heavy metals in the ganga hooghly river estuary india global importance of Solute Particle interaction and enhanced metal fluxes to the oceans
Geochimica et Cosmochimica Acta, 2018Co-Authors: Saumik Samanta, Tarun K DalaiAbstract:Abstract The Ganga River System is a major contributor to the global sediment and water discharge to the oceans. The estuary of Ganga (Hooghly) River in India is under increasing influence of anthropogenic contributions via discharge of the industrial and urban effluents. Here we document, based on the investigation of water and suspended sediment samples collected during six periods over two years, that there is extensive production of heavy metals (Co, Ni and Cu) in the estuary such that the annual dissolved fluxes of metals from the Hooghly River are enhanced by up to 230–1770%. Furthermore, the estuarine dissolved metal fluxes, when normalized with water fluxes, are the highest among estuaries of the major rivers in the world. Our simultaneous data on the dissolved, suspended particulate and exchangeable phases allow us to identify the ion-exchange process (coupled adsorption and desorption) as the dominant contributor to the generation of heavy metals in the middle and lower estuary where the estimated anthropogenic contribution is negligible. The estimated contributions from the groundwater are also insufficient to explain the measured metal concentrations in the estuary. A strong positive correlation that is observed between the dissolved heavy metal fluxes and the suspended particulate matter (SPM) fluxes, after normalizing them with the water fluxes, for estuaries of the major global rivers imply that the Solute-Particle interaction is a globally significant process in the estuarine production of metals. Based on this correlation that is observed for major estuaries around the world, we demonstrate that the South Asian Rivers which supply only ∼9% of the global river water discharge but carry elevated SPM load, contribute a far more significant proportion (∼40 ± 2% Ni and 15 ± 1% Cu) to the global supply of the dissolved metals from the rivers.
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dissolved and particulate barium in the ganga hooghly river estuary india Solute Particle interactions and the enhanced dissolved flux to the oceans
Geochimica et Cosmochimica Acta, 2016Co-Authors: Saumik Samanta, Tarun K DalaiAbstract:Abstract In this study, the sources and the cycling of Ba have been evaluated in the Ganga (Hooghly) River estuary using the composition of the suspended sediments and the water samples collected during six seasons of contrasting water discharge over two years (2012 and 2013). In addition, the data on the samples of groundwater from areas adjacent to the estuary, and the industrial effluent water and urban wastewater draining into the estuary are presented. Selective extraction experiments were also performed on the suspended particulate matter of two seasons to assess the distribution of exchangeable concentrations of major ions and Ba. In the mixing zone, the variation patterns of the dissolved Ba concentrations show mid-salinity maxima and are similar to the patterns of variation of the particulate Mg/Al and Mg/Fe, suggesting that the production of dissolved Ba is linked to the adsorption of major ions on to the clay minerals and Fe–Mn oxyhydroxides in the particulate matter. The inference of coupled adsorption–desorption processes is supported by the observations that the particulate Ba/Mg and Ba/K ratios exhibit significant to strong negative correlations with the concentrations of Al, Fe and Mn. The observations of mid-salinity maxima for the concentrations of exchangeable Mg and K, and of the exchangeable Ba concentrations that decrease with salinity provide strong evidence that the Solute-Particle interactions is the major driver in regulating the dissolved Ba distributions in the estuary. The estimates of the quantity of desorbed Ba based on three different approaches suggest that desorption is sufficient to account for the calculated excess Ba (Baxs) concentrations. The contribution of Ba to the dissolved load via dissolution of the particulate carbonate phases is minor, up to 3% of the maximum Baxs concentrations. The estimates of anthropogenic contributions are insignificant, and account for ⩽2% of maximum Baxs in the estuary. Groundwater contributions are less significant and account for up to 5% of the annual Ba flux from the Hooghly estuary. The estimates of Ba flux show that annually (1.5–1.9) × 107 moles of Ba is transported by the Hooghly River. About (3.6–4.3) × 107 moles of Ba is generated annually in the estuary through desorption. Added together, the desorbed and riverine Ba fluxes generate a total Ba flux of (5.1–6.2) × 107 moles per year. Thus, the Solute-Particle interactions enhance the riverine Ba flux by >300%. A compilation of the available data shows that the enhancement of the riverine Ba flux and the fractions of desorbed Ba flux scale with (particulate matter flux/water flux) ratio in several estuaries of the world, suggesting that the process of Solute-Particle interactions is a major driver for the estuarine production of Ba on a global scale. Among the rivers considered in this study, the estuaries of the Hooghly River and the Ganges–Brahmaputra rivers, characterized by very high (sediment flux/water flux) ratio, depict the highest increase in the riverine Ba flux. This unique feature of the Ganga River system is inferred to be resulting from the collective impact of the tectonic activity and the monsoonal rainfall in the catchment areas.
Harold A Scheraga - One of the best experts on this subject based on the ideXlab platform.
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simple physics based analytical formulas for the potentials of mean force for the interaction of amino acid side chains in water 1 approximate expression for the free energy of hydrophobic association based on a gaussian overlap model
Journal of Physical Chemistry B, 2007Co-Authors: Mariusz Makowski, And Adam Liwo, Harold A ScheragaAbstract:A physics-based model is proposed to derive approximate analytical expressions for the cavity component of the free energy of hydrophobic association of spherical and spheroidal Solutes in water. The model is based on the difference between the number and context of the water molecules in the hydration sphere of a hydrophobic dimer and of two isolated hydrophobic Solutes. It is assumed that the water molecules touching the convex part of the molecular surface of the dimer and those in the hydration spheres of the monomers contribute equally to the free energy of solvation, and those touching the saddle part of the molecular surface of the dimer result in a more pronounced increase in free energy because of their more restricted mobility (entropy loss) and fewer favorable electrostatic interactions with other water molecules. The density of water in the hydration sphere around a single Solute Particle is approximated by the derivative of a Gaussian centered on the Solute molecule with respect to its standa...
Bogdan Lesyng - One of the best experts on this subject based on the ideXlab platform.
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hydration free energy of a model lennard jones Solute Particle microscopic monte carlo simulation studies and interpretation based on mesoscopic models
Journal of Chemical Physics, 2008Co-Authors: Magdalena Gruziel, Witold R Rudnicki, Bogdan LesyngAbstract:In this study, the hydration of a model Lennard-Jones Solute Particle and the analytical approximations of the free energy of hydration as functions of Solute microscopic parameters are analyzed. The control parameters of the Solute Particle are the charge, the Lennard-Jones diameter, and also the potential well depth. The obtained multivariate free energy functions of hydration were parametrized based on Metropolis Monte Carlo simulations in the extended NpT ensemble, and interpreted based on mesoscopic solvation models proposed by Gallicchio and Levy [J. Comput. Chem. 25, 479 (2004)], and Wagoner and Baker [Proc. Natl. Acad. Sci. U.S.A. 103, 8331 (2006)]. Regarding the charge and the Solute diameter, the dependence of the free energy on these parameters is in qualitative agreement with former studies. The role of the third parameter, the potential well depth not previously considered, appeared to be significant for sufficiently precise bivariate solvation free energy fits. The free energy fits for cations and neutral Solute Particles were merged, resulting in a compact manifold of the free energy of solvation. The free energy of hydration for anions forms two separate manifolds, which most likely results from an abrupt change of the coordination number when changing the size of the anion Particle.
Gary M Hieftje - One of the best experts on this subject based on the ideXlab platform.
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computerized simulation of mixed Solute Particle vaporization in an inductively coupled plasma
Spectrochimica Acta Part B: Atomic Spectroscopy, 1998Co-Authors: Julie A Horner, Gary M HieftjeAbstract:Recent experiments involving aerosol introduction into the inductively coupled plasma have shown that intact droplets and Solute Particles cause enormous fluctuations in analyte emission and mass-spectral signals. Here, Particle-vaporization kinetics are simulated as a detailed function of the operating conditions, fundamental properties and spatial location in the inductively coupled plasma, and as a function of several of the properties of the Particles themselves: diameter, chemical composition and size distribution. These simulations portray the Particle vaporization as proceeding nominally linearly with respect to the Particle radius when the Particles are small, but roughly quadratically with radius when the Particles are very large. Further, the heat- and mass-transfer-limited rates of vaporization are roughly equal for the typical gas-temperature range in the plasma tail flame, so that at any height either process might limit the rate of vaporization. This similarity gives rise to a dynamic, competitive picture of plasma vaporization kinetics.