Tracing the source of bottled water using stable isotope techniques

The Indian Summer Monsoon (ISM) precipitation recharges ground water aquifers in a large portion of the Indian subcontinent. Monsoonal precipitation over the Indian region brings moisture from the Arabian Sea and the Bay of Bengal (BoB). A large difference in the salinity of these two reservoirs, owing to the large amount of freshwater discharge from the continental rivers in the case of the BoB and dominating evaporation processes over the Arabian Sea region, allows us to distinguish the isotopic signatures in water originating in these two water bodies. Most bottled water manufacturers exploit the natural resources of groundwater, replenished by the monsoonal precipitation, for bottling purposes. The work presented here relates the isotopic ratios of bottled water to latitude, moisture source and seasonality in precipitation isotope ratios. We investigated the impact of the above factors on the isotopic composition of bottled water. The result shows a strong relationship between isotope ratios in precipitation (obtained from the GNIP data base)/bottled water with latitude. The approach can be used to predict the latitude at which the bottled water was manufactured. The paper provides two alternative approaches to address the site prediction. The limitations of this approach in identifying source locations and the uncertainty in latitude estimations are discussed. Furthermore, the method provided here can also be used as an important forensic tool for exploring the source location of bottled water from other regions. Copyright (C) 2011 John Wiley & Sons, Ltd.

Thermodynamics of oxygen in liquid copper, lead and copper lead alloys

Solid oxide galvanic cells of the type Pt, Ni-NiO I Solid electrolyte ( Ometa,, Cermet. Pt were used to measure the activity coefficient of oxygen in liquid copper at 11 00 and 1 300eC, and in lead at 11 00'C. Similar cells were used to study the activity coefficient of oxygen in the whole range of Cu + Pb alloys at 1100'C and in lead-rich alloys at 900 and 750'C.The results obtained are discussed in terms of proposed solution models. An equation based on the formation of 'species' of the form M,O in solutions of oxygen in binary alloys is shown to fit the experimental data.

Thermodynamic study of oxygen in liquid lead tin alloys

The activity coefficients of oxygen in liquid lead-tin alloys have been measured between 550 and 1100°C by use of solid oxide galvanic cells Pt, Ni-NiO I Zr02 Solid electrolyte I 0 (Pb + Sn), Cermet, Pt Pt, Fe-FeO I Zr02 Solid electrolyte I O(Pb + Sn), Cermet, Pt Alcock and Richardson's quasi-chemical equation, with the coordination number of atoms set to 2, is found to predict successfully the activity coefficients of oxygen in these alloys.The relative partial molar enthalpy and entropy of oxygen ?t 1 atom per cent in the alloys have been calculated from ttva variation of the activity coefficient with temperature. The addition of tin to an unsaturated solution of oxygen in lead is shown to decrease significantly both the partial molar enthalpy and entropy of oxygen. As the measurements were restricted to a narrow range between 750-1100'C in lead-rich alloys, however, the pronounced variation of the partial molar enthalpy of oxygen with temperature at constant alloy composition predicted by the quasi-chemical model could not be verified.

Activities of oxygen and lead in Pb-Ag O solutions

The reversible e.m.f. of galvanic cells: stainlesssteel,Ir,Pb+PbO|CaO+ZrO2|Ag+Pb+PbO,Ir,stainlesssteel,I and Pt,Ni+NiO|CaO+ZrO2|O(Pb+Ag),Cermet,Pt,II incorporating solid oxide electrolytes were measured as a function of alloy composition. In lead-rich alloys, the temperature dependence of the e.m.f. of cell I was also investigated. Since the solubility of oxygen in the alloy is small, the relative partial molar properties of lead in the binary Ag + Pb system can be calculated from the e.m.f. of this cell. The Gibbs free energies obtained in this study are combined with selected calorimetric data to provide a complete thermodynamic discription of liquid Ag + Pb Alloys. The activity coefficient of oxygen in the whole range of Ag + Pb alloys at 1273 K have been obtained from the e.m.f. of cell II; and these are found to deviate positively from Alcock and Richardson's quasichemical equation when the average co-ordination number of all the atoms is assigned a value of 2.

Gibbs energy of formation of lead zirconate

The Gibbs energy of formation of zirconia-saturated lead zirconate was determined by emf measurements on the solid state cells and at 800 to 1400 K. The results obtained differ significantly from those reported in the literature based on vapor-pressure measurements, using Knudsen effusion and transportation techniques and assuming that the vapor phase consisted entirely of monomeric PbO molecules. A reanalysis of the data obtained in the earlier vapor-pressure studies, using mass-spectrometric measurements on polymeric PbO species in the gas phase, gives Gibbs energies of formation of lead zirconate which are in better agreement with those obtained in this study. Recent electrochemical measurements using CaO-ZrO2 and PbF2 solid electrolytes are in good agreement with the present study. The results obtained in this study are also consistent with the phase diagram which shows decomposition of the zirconate to tetragonal zirconia and a liquid phase rich in PbO at 1843 K.

Gibbs energy formation of lead titanate

The Gibbs energy of formation of titania-saturated lead titanate has been determined by e.m.f. measurements on the solid state cell;Pt,Ir,Pb + Pb1−xTiO3−x + TiO2(rutile)/CaO-ZrO2/Ni + NiO,Pt in the temperature range 1075–1350 K. The results obtained are significantly different from those reported in the literature based upon vapour pressure measurements, employing Knudsen effusion and transportation techniques, and assuming that the vapor phase consisted entirely of monomeric PbO molecules. A reanalysis of the data obtained in the earlier vapor pressure studies using mass spectrometric measurements on polymeric PbO species in the gas phase, gives Gibbs energies of formation of lead titanate which are in better agreement with those obtained in this study. Earlier electrochemical measurements by Mehrotra et al. and more recent electrochemical measurements by Schmahl et al. both employing CaO-ZrO2 solid electrolytes are in good agreement with the present study. The electro-chemical measurements by Schmahl et al. using PbF 2 solid electrolyte give a slightly more positive Gibbs energy of formation. There was no evidence supporting the formation of compounds other than Pb1−xTiO3−x from yellow PbO and rutile form of TiO2 in the temperature range covered in this study.Résumé L'enthalpie libre de formation du titanate de plomb saturé en oxyde de titane a été déterminée par des mesures de FEM de la pile: Pt,Ir,Pb + Pb1−xTiO3−x + TiO2(rutile)/CaO-ZrO2/Ni + NiO,Pt dans le domaine de températures 1075–1350 K. Les résultats obtenus, different appréciablement de ceux publiés, déterminés par mesures de tensions de vapeur (techniques de transport et d'effusion de Knudsen) en supposant que la phase gazeuse etait uniquement constituée de molécules monomériques de PbO. Une réanalyse des résultats de la littérature, à partir de mesures par spectrométrie de masse sur les polymères de PbO gazeux, donne des enthalpies libres de formation du titanate de plomb se rapprochant de celles obtenues dans cette étude. Les mesures de Mehrotra et al. et plus récemment de Schmahl et al. utilisant toutes deux l'électrolyte CaO-ZrO2 concordent bien avec celles de la présente étude. Les mesures de Schmahl et al., à l'aide de l' électrolyte solide PbF2, donnent une enthalpie de formation légèrement plus positive. Pour la gammede températures étudiée, rien ne permet de supposer que des composés autres que Pb1−x TiO3−x puissent se former à partir du PbO Gaune) et du rutile (TiO2).

Potentiometric determination of the Gibbs energies of formation of lead aluminates

The Gibbs energies of formation of three compounds in the PbO-Al2O3 system—2PbO · Al2O3, PbO · Al2O3, andPbO· 6Al2O3—have been determined from potentiometric measurements on reversible solid-state galvanic cells [dformula Pt, Ir | Pb, alpha-Al[sub 2]O[sub 3], PbO [center-dot] 6Al[sub 2]O[sub 3] | ZrO[sub 2]-CaO | NiO, Ni | Pt] [dformula Pt | NiO, Ni | ZrO[sub 2]-CaO | Pb, PbO [center-dot] 6Al[sub 2]O[sub 3], PbO [center-dot] Al[sub 2]O[sub 3] | Ir, Pt] and [dformula Pt | NiO, Ni | ZrO[sub 2]-CaO | Pb, PbO [center-dot] Al[sub 2]O[sub 3], 2PbO [center-dot] Al[sub 2]O[sub 3] | Ir, Pt] in the temperature range 850–1375 K. The results are discussed in the light of reported phase diagrams for the PbO-Al2O3system. The partial pressures of different lead oxide species, PbnOn, n = 1–6, in the gas phase in equilibrium withthe aluminates are calculated by combining the results of this study with the mass-spectrometric data of Drowart et al.(1) for polymerization equilibria in the gas phase. The concentration of oxygen in lead in equilibrium with the aluminatesare also derived from the results and the literature data on the Gibbs energy of solution of oxygen in liquid lead.

The fluorescence of Nd3+ in lead borate and bismuth borate glasses with large stimulated emission cross section

The stimulated emission cross section σp for the 1060 nm transition of Nd3+ in lead borate and bismuth borate glasses has been determined from fluorescence measurements. The compositional dependence of σp, which has been evaluated using radiative transition probability, refractive index of the host glass, effective fluorescence linewidth, and position of the band, with PbO/Bi2O3 content is investigated. The σp values of the 1060 nm band of Nd3+ for lead borate and bismuth borate glasses are found to be in the range 2.6–5.7×10−20 cm2 at 298 K and 3.0–6.3×10−20 cm2 at 4.2 K. The σp values are comparatively large suggesting the possible utilization of these materials in laser applications.

Influence of surge impedance of the connecting lead in response time measurement of u.h.v. damped capacitive voltage dividers

In the determination of the response time of u.h.v. damped capacitive impulse voltage dividers using the CIGRE IMR-1MS group (1) method and the arrangement suggested by the International Electrotechnical Commission (the I EC square loop),the surge impedance of the connecting lead has been found to influence the accuracy of determination. To avoid this difficulty,a new graphical procedure is proposed. As this method uses only those data points which can be determined with good accuracy, errors in response-time area evaluation do not influence the result.

Electrochemical detection and removal of lead in water using poly(propylene imine) modified re-compressed exfoliated graphite electrodes

Modification of exfoliated graphite (EG) electrode with generation 2 poly(propylene imine) dendrimer by electrodeposition resulted in an electrochemical sensor which was used to detect lead ions in water to a limit of 1 ppb and a linear response between 2.5 and 40 ppb using square wave anodic stripping voltammetry (SW-ASV). Pb(II) was also removed from spiked water sample using a 40-mm diameter unmodified EG electrode with an applied potential of -1,000 mV for 180 min. A removal efficiency of 99% was calculated from a 150 mL sample. The results obtained in both cases using SW-ASV, correlated with atomic absorption spectroscopy.