Quantitative Mass Balance Research Articles

Hydrothermal alteration and elemental mass balance for the Surda Copper Deposit, Singhbhum Shear Zone, Eastern India: implications for both copper and magnetite–apatite mineralization

This paper explores the geological relationships, mineralogical and geochemical characteristics, and quantitative elemental mass balance constraints of the hydrothermal alteration zones within the uraniferous Surda copper deposit in the Singhbhum Shear Zone in eastern India, which is affiliated with an iron oxide–copper–gold system. Five distinct alteration zones are identified: a proximal potassic (biotitization) zone containing magnetite–apatite; a central chloritization zone containing copper, uranium, gold and magnetite; distal silicification (quartz) and albitization zones; and a transitional chlorite–sericitization zone. Evidence suggests these zones originated from mafic precursors linked to a subduction zone. Magnetite mineralization shows both magmatic ( δ 18 O + 2.0 to +4.8‰) and hydrothermal ( δ 18 O + 0.4 to +0.6‰) signatures. Hydrothermal magnetite–apatite formed at temperatures of 440 to 550°C, with continued crystallization at lower temperatures (280 to 360°C) concurrent with copper sulfide and uranium precipitation from an Fe-rich, isotopically heavy fluid ( δ 34 S + 4.55 to +9.66‰). Major elements (Ca, Na, Mg) and some minor and rare earth elements decrease from weakly altered mafic rocks to late alteration zones, reflecting the breakdown of Ca-bearing hornblende, biotite and plagioclase. Potassium decreases from early to late alteration zones due to mineral transformations. Mass-balanced geochemical data align with hydrothermal alteration mineral assemblages, indicating processes such as mineral dissolution, element absorption and sulfide behaviour. Overall, the study highlights the complex hydrothermal alteration processes shaping the Surda copper deposit and provides insights into ore formation mechanisms.

Establishment of SI-traceable purity assessment of Fumonisin B1 using a combination of quantitative 1H NMR and mass balance

The accurate purity assessment of Fumonisin B1 (FB1) is of great challenge due to the lack of inherent chromophore, which is important for the development of FB1 certified reference material. In this study, differential scanning calorimetry (DSC), mass balance and quantitative 1H nuclear magnetic resonance (qH NMR) methods were developed and validated for international system of unit (SI) traceable purity assessment of in-house prepared FB1. The thermodynamic analysis showed no typical melting peak was observed for FB1, indicating DSC was not applicable for purity assessment of FB1. A high-performance liquid chromatography coupled with corona charged aerosol detector (HPLC-CAD) method was developed and an isocratic elution procedure was optimized for the chromatographic purity analysis of FB1. The linear range of optimized HPLC-CAD method could not cover the concentration range of FB1 and the structure-related impurity in the raw material, which was identified to be partial hydrolyzed FB1 (pHFB1). The correction factor used to correct the chromatographic purity obtained by area normalization method was approximately 0.2 %. Moisture (0.30 %) and pHFB1 (0.48 %) were the main impurities according to the mass balance analysis. A mixture of dimethyl sulfoxide-d6 and trifluoroacetic acid-d was confirmed to be a suitable deuterated solvent for accurate qH NMR analysis of FB1. The purity obtained by mass balance (99.13 % with uncertainty of 0.06 %) and qH NMR (99.12 % with uncertainty of 0.28 %) showed good consistency and equivalent precision. These methods are expected to be applicable to development of FB1 certified reference material with metrological traceability to the SI unit to ensure comparable and reliable detection results.

Development of certified reference materials for four polyunsaturated fatty acid esters

Certified reference materials (CRMs) with high accuracy and traceability are essential tools for the validation of analytical methods and calibration of equipment. In this study, purity CRMs for four polyunsaturated fatty acids (PUFAs) esters, namely, cis-(4,7,10,13,16,19)- Docosahexaenoic acid methyl ester (DHA-ME), cis-4,7,10,13,16,19- Docosahexaenoic acid ethyl ester (DHA-EE), cis-(5,8,11,14,17)- Eicosapentaenoic acid methyl ester (EPA-ME) and cis-(5,8,11,14,17)- Eicosapentaenoic acid ethyl ester (EPA-EE), were first developed according to the ISO Guide. The CRMs’ purity values were assigned based on the average of quantitative nuclear magnetic resonance and mass balance approaches. The certified value with expanded uncertainties (k = 2, 95% confidence interval) were determined to be (98.8 ± 0.4) %, (99.0 ± 0.3) %, (98.9 ± 0.4) % and (98.9 ± 0.4) % for DHA-ME, DHA-EE, EPA-ME and EPA-EE, respectively. The four PUFAs esters were homogeneous and stable for 12 months at −4 °C and 7 days at 50 °C.

Establishment of Si-Traceable Purity Assessment of Fumonisin B1 Using a Combination of Quantitative 1h Nmr and Mass Balance

Establishment of Si-Traceable Purity Assessment of Fumonisin B1 Using a Combination of Quantitative 1h Nmr and Mass Balance

CO2 capture by 1-ethyl-3-methylimidazolium acetate: Solubility at low pressure and quantification of chemisorption and physisorption

Although chemisorptive ionic liquids (ILs) are widely expected as promising CO2 absorbents, rigorous thermodynamic analyses for such systems remain challenging due to the inevitable co-existence of chemisorption and physisorption. In this work, an experimental approach combining quantitative NMR (qNMR) spectroscopy and mass balance is proposed to straightforwardly quantify the chemisorption and physisorption of CO2 in chemisorptive absorbent, and 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) is selected for an exemplary study. The total CO2 solubility in [Emim][OAc] is measured by the pressure drop method, of which the chemisorption part is quantified by qNMR and the physisorption part is then determined by mass balance. Correspondingly, a large set of CO2 solubilities at four temperatures (298.15 K, 313.15 K, 323.15 K, and 348.15 K) covering the low pressure range below 100 kPa are determined, where the chemisorption and physisorption contribution are distinguished quantitatively. Following that, thermodynamic analyses for the CO2 absorption by [Emim][OAc] are made from chemisorption and physisorption point of view, respectively.

Evaluation of energy recovery potential in wastewater treatment based on codigestion and combined heat and power schemes

The future goal for wastewater treatment industry is to transform existing wastewater treatment plants (WWTPs) into water and energy recovery facilities (WERFs). The first step to reach this goal is to achieve energy-neutral or energy-positive status in its operations. This research study develops a systematic quantitative analysis to assess the performance of different wastewater treatment scenarios. The effects of the influent wastewater strength (or concentration), plant capacity, primary treatment efficiency, and different supplemental feedstock have been evaluated to assess the potential for energy recovery in WTTPs. Further, energy performance of the WWTP is optimized using different combined heat and power (CHP) schemes. For the first time, a quantitative mass and energy balance methodology was used to evaluate carbon and energy balance and combined heat and power system optimization. Increasing the primary treatment efficiency, process equipment upgrades, and use of supplemental biodegradable organic waste are identified as influential factors. Increasing the removal of chemical oxygen demand (COD) by 10% in primary treatment resulted in an estimated reduction in total energy requirement by 8.5% and increased recoverable energy by 8.8%. This result illustrates that influent wastewater COD strength and the plant capacity may have significant impact on the energy recovery potential. Energy production from a WERF can be enhanced by codigesting sewage sludge with highly biodegradable organic waste. Further analysis shows that specifying an appropriate CHP engine is integral in minimizing the energy losses.

Arsenic and iron speciation and mobilization during phytostabilization of pyritic mine tailings

Particulate and dissolved metal(loid) release from mine tailings is of concern in (semi-)arid environments where tailings can remain barren of vegetation for decades and, therefore, become highly susceptible to dispersion by wind and water. Erosive weathering of metalliferous tailings can lead to arsenic contamination of adjacent ecosystems and increased risk to public health. Management via phytostabilization with the establishment of a vegetative cap using organic amendments to enhance plant growth has been employed to reduce both physical erosion and leaching. However, prior research suggests that addition of organic matter into the oxic weathering zone of sulfide tailings has the potential to promote the mobilization of arsenate. Therefore, the objective of the current work was to assess the impacts of phytostabilization on the molecular-scale mechanisms controlling arsenic speciation and lability. These impacts, which remain poorly understood, limit our ability to mitigate environmental and human health risks. Here we report on subsurface biogeochemical transformations of arsenic and iron from a three-year phytostabilization field study conducted at a Superfund site in Arizona, USA. Legacy pyritic tailings at this site contain up to 3 g kg−1 arsenic originating from arsenopyrite that has undergone oxidation to form arsenate-ferrihydrite complexes in the top 1 m. Tailings were amended in the top 20 cm with 100, 150, or 200 g kg−1 (300–600 t ha−1) of composted organic matter and seeded with native halotolerant plant species. Treatments and an unamended control received irrigation of 360 ± 30 mm y−1 in addition to 250 ± 160 mm y−1 of precipitation. Cores to 1 m depth were collected annually for three years and sectioned into 20 cm increments for analysis by synchrotron iron and arsenic X-ray absorption spectroscopy (XAS) coupled with quantitative wet chemical and mass balance methods. Results revealed that >80% of arsenic exists in ammonium oxalate-extractable and non-extractable phases, including dominantly ferrihydrite and jarosite. Arsenic release during arsenopyrite oxidation resulted in both downward translocation and As(V) attenuation by stable Fe(III)(oxyhydr)oxide and Fe(III) (hydroxy)sulfate minerals over time, highlighting the need for sampling at multiple depths and time points for accurate interpretation of arsenic speciation, lability, and translocation in weathering profiles. Less than 1% of total arsenic was highly-labile, i.e. water-extractable, from all treatments, depths, and years, and more than 99% of arsenate released by arsenopyrite weathering was attenuated by association with secondary minerals. Although downward translocation of both arsenic and iron was detected during phytostabilization by temporal enrichment analysis, a similar trend was measured for the uncomposted control, indicating that organic amendment associated with phytostabilization practices did not significantly increase arsenic mobilization over non-amended controls.

Which heterogeneous glacier melting patterns can be robustly observed from space? A multi-scale assessment in southeastern Tibetan Plateau

Region-wide investigation of glacier change in High Mountain Asia marked the strongest recession in southeastern Tibetan Plateau (SETP) in recent decades. However, evident differences of quantitative glacier mass balance (MB) estimations on fine scales exist in the prior reports. The large uncertainties in current geodetic observations over this region highlight the need for more independent validations and investigations on the spatial variability of glacier change. This study enriched glacier MB estimates over the SETP by using the newly released global Digital Elevation Model (DEM) - the TanDEM-X and analyzed the spatial pattern of glacier change on multi-spatial scales by comparing available satellite-based geodetic observations. Results reveal that the TanDEM-X - SRTM elevation differences, which show no obvious horizontal shifts and no significant elevation-dependent bias, provide reliable elevation change information over this challenging area. On the regional scale, the geodetic datasets (the ASTER elevation change rates data, TanDEM-X- SRTM differences, ICESat) achieved a highly consistent estimate of glacier MB at −4.11 ± 1.52 Gt a−1 (−0.60 ± 0.16 m w.e. a−1) during 2000 and 2010s. On the subregional scale, the two gridded geodetic datasets revealed a clear contrast between moderate thinning of spring-accumulation type glaciers in the south and significantly more negative glacier MB of summer-accumulation type glaciers in the north. Glacier-wide MB showed high heterogeneity, which was closely related to the combined effect of topographic variation and climate forcings. We observed similar glacier thinning rates between debris-covered land-terminating glaciers and clean-ice glaciers (−0.50 ± 0.32 m w.e. a−1) but remarkable more negative MB (−0.89 ± 0.36 m w.e. a−1) of debris-covered glaciers connected with glacial lakes, which may indicate different evolution process of debris-covered glaciers in the monsoon-influenced region. This study demonstrates that current satellite-based geodetic observations achieve overall consistent patterns of glacier mass changes even over the most challenging mountainous areas (complicated terrain and climate). With the global TanDEM-X DEM and increasing observations from the mission, we expect improved consistency in glacier MB estimation on large spatial scales as well as detailed investigation of glacier mass change variability in the future.

Toward hydrogen economy: Selective guaiacol hydrogenolysis under ambient hydrogen pressure

The conversion of guaiacol into the nylon precursors, cyclohexanol and cyclohexanone, is catalyzed by palladium supported on high surface area ceria (Pd/HS CeO2) under mild conditions (100 °C, ≤1 bar H2) via sequential hydrodemethoxylation and hydrogenation. In contrast, the 2-methoxycyclohexanol side product is generated by direct guaiacol hydrogenation. Reaction selectivity is determined by competing CO bond hydrogenolysis versus arene hydrogenation. Hydrogenolysis selectivity increases as H2 pressure decreases, and over 80 % H2 is incorporated into the products at 1 bar H2. Higher reactivity of guaiacol than anisole implies that the hydroxyl group is essential in Pd/HS CeO2 catalysis. Participation of water in the conversion is evidenced by deuterium incorporation at non-exchangeable positions when the reaction is performed in D2O. The combination of near quantitative mass balance of H2, high recyclability, and use of water as a solvent offers a simple, green and efficient conversion of lignin-derived aromatics into commercial products.

Energy autarky of small scale wastewater treatment plants by enhanced carbon capture and codigestion – A quantitative analysis

Municipal wastewater treatment plants (WWTPs) can achieve energy self-sufficiency (autarky) while complying with increasing discharge standards. We evaluated three energy-positive wastewater treatment scenarios classified as “Basic”, “Moderate”, and “Advanced” configurations. A quantitative mass and energy balance model was developed to analyze the energy recovery potentials of these configurations. Enhanced COD capture, codigestion with locally available biodegradable wastes, and aeration energy optimization were considered as the main approaches to achieve an energy autarky or energy-positive status. Data from existing operating plants were used to validate the model performance. This paper presents a detailed quantitative analysis of two (basic and moderate) energy-neutral or energy-positive wastewater treatment configurations. In addition, a novel and practically feasible energy-positive wastewater treatment scheme incorporating advanced solids separation is presented with energy analysis and a case study. This model can be useful to quickly assess the energy recovery potential of small scale wastewater treatment systems.

Quantitative mass balance, tissue distribution, pharmacokinetics and biotransformation pathway of praliciguat, a clinical-stage sgc stimulator, after oral administration in rats

Quantitative mass balance, tissue distribution, pharmacokinetics and biotransformation pathway of praliciguat, a clinical-stage sgc stimulator, after oral administration in rats

Assessment of the Purity of Emodin by Quantitative Nuclear Magnetic Resonance Spectroscopy and Mass Balance

Assessment of the Purity of Emodin by Quantitative Nuclear Magnetic Resonance Spectroscopy and Mass Balance

Rapid growth of organic aerosol nanoparticles over a wide tropospheric temperature range

Nucleation and growth of aerosol particles from atmospheric vapors constitutes a major source of global cloud condensation nuclei (CCN). The fraction of newly formed particles that reaches CCN sizes is highly sensitive to particle growth rates, especially for particle sizes <10 nm, where coagulation losses to larger aerosol particles are greatest. Recent results show that some oxidation products from biogenic volatile organic compounds are major contributors to particle formation and initial growth. However, whether oxidized organics contribute to particle growth over the broad span of tropospheric temperatures remains an open question, and quantitative mass balance for organic growth has yet to be demonstrated at any temperature. Here, in experiments performed under atmospheric conditions in the Cosmics Leaving Outdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN), we show that rapid growth of organic particles occurs over the range from [Formula: see text]C to [Formula: see text]C. The lower extent of autoxidation at reduced temperatures is compensated by the decreased volatility of all oxidized molecules. This is confirmed by particle-phase composition measurements, showing enhanced uptake of relatively less oxygenated products at cold temperatures. We can reproduce the measured growth rates using an aerosol growth model based entirely on the experimentally measured gas-phase spectra of oxidized organic molecules obtained from two complementary mass spectrometers. We show that the growth rates are sensitive to particle curvature, explaining widespread atmospheric observations that particle growth rates increase in the single-digit-nanometer size range. Our results demonstrate that organic vapors can contribute to particle growth over a wide range of tropospheric temperatures from molecular cluster sizes onward.

Cinnamon Gulch revisited: Another look at separating natural and mining-impacted contributions to instream metal load

Baseline, premining data for streams draining abandoned mine lands is virtually non existent, and indirect methods for estimating premining conditions are needed to establish realistic, cost effective cleanup goals. One such indirect method is the proximal analog approach, in which premining conditions are estimated using data from nearby mineralized areas that are unaffected by mining. In this paper, we combine the proximal analog approach with a quantitative mass balance framework using data from a spatially-detailed synoptic sampling campaign. The combined approach is applied to Cinnamon Gulch, a headwater stream with numerous draining adits. Synoptic sampling results indicate that three of the top five metal sources are affected by mining activities, and stream segments draining these sources account for a large percentage of overall metal loading within the study reach. These initial calculations overestimate the effects of mining, as the affected stream segments were likely acidic and metal rich prior to mining. Premining loads and concentrations were therefore determined through a replacement approach in which the chemistry of each mining-affected stream segment is revised based on proximal analog concentrations. The revised loading profiles indicate that 15–17% of the Al, Cd, Cu, Mn, Ni, and Zn loads are attributable to mining, whereas the mining contribution for Pb is 40%. Premining concentrations of Al, Cd, Cu, Mn, and Zn are estimated to be in excess of aquatic life standards over the length of the study reach.

Probing Contaminant Transport to and from Clay Surfaces in Organic Solvents and Water Using Solution Calorimetry.

Clays, in tailings, are a significant ongoing environmental concern in the mining and oilsands production industries, and clay rehabilitation following contamination poses challenges episodically. Understanding the fundamentals of clay behavior can lead to better environmental impact mitigation strategies. Systematic calorimetric measurements are shown to provide a framework for parsing the synergistic and antagonistic impacts of trace (i.e., parts per million level) components on the surface compositions of clays. The enthalpy of solution of as-received and "contaminated" clays, in as-received and "contaminated" organic solvents and water, at 60 °C and atmospheric pressure, provides important illustrative examples. Clay contamination included pre-saturation of clays with water and organic liquids. Solvent contamination included the addition of trace water to organic solvents and trace organic liquids to water. Enthalpy of solution outcomes are interpreted using a quantitative mass and energy balance modeling framework that isolates terms for solvent and trace contaminant sorption/desorption and surface energy effects. Underlying surface energies are shown to dominate the energetics of the solvent-clay interaction, and organic liquids as solvents or as trace contaminants are shown to displace water from as-received clay surfaces. This approach can be readily extended to include pH, salts, or other effects and is expected to provide mechanistic and quantitative insights underlying the stability of clays in tailings ponds and the behaviors of clays in diverse industrial and natural environments.

Inhibition of residual n-hexane in anaerobic digestion of lipid-extracted microalgal wastes and microbial community shift.

Converting lipid-extracted microalgal wastes to methane (CH4) via anaerobic digestion (AD) has the potential to make microalgae-based biodiesel platform more sustainable. However, it is apparent that remaining n-hexane (C6H14) from lipid extraction could inhibit metabolic pathway of methanogens. To test an inhibitory influence of residual n-hexane, this study conducted a series of batch AD by mixing lipid-extracted Chlorella vulgaris with a wide range of n-hexane concentration (∼10g chemical oxygen demand (COD)/L). Experimental results show that the inhibition of n-hexane on CH4 yield was negligible up to 2g COD/L and inhibition to methanogenesis became significant when it was higher than 4g COD/L based on quantitative mass balance. Inhibition threshold was about 4g COD/L of n-hexane. Analytical result of microbial community profile revealed that dominance of alkane-degrading sulfate-reducing bacteria (SRB) and syntrophic bacteria increased, while that of methanogens sharply dropped as n-hexane concentration increased. These findings offer a useful guideline of threshold n-hexane concentration and microbial community shift for the AD of lipid-extracted microalgal wastes.

Metabolic disposition of the anti-cancer agent [14C]laromustine in male rats

1. Laromustine (VNP40101M, also known as Cloretazine) is a novel sulfonylhydrazine alkylating (anticancer) agent. This article describes the use of quantitative whole-body autoradiography (QWBA) and mass balance to study the tissue distribution, the excretion mass balance and pharmacokinetics after intravenous administration of [14C]VNP40101M to rats. A single 10 mg/kg IV bolus dose of [14C]VNP40101M was given to rats.2. The recovery of radioactivity from the Group 1 animals over a 7-day period was an average of 92.1% of the administered dose, which was accounted for in the excreta and carcass. Most of the radioactivity was eliminated within 48 h via urine (48%), with less excreted in feces (5%) and expired air accounted for (11%). The plasma half-life of [14C]laromustine was approximately 62 min and the peak plasma concentration (Cmax) averaged 8.3 μg/mL.3. The QWBA study indicated that the drug-derived radioactivity was widely distributed to tissues through 7 days post-dose after a single 10 mg/kg IV bolus dose of [14C]VNP40101M to male pigmented Long–Evans rats. The maximum concentrations were observed at 0.5 or 1 h post-dose for majority tissues (28 of 42). The highest concentrations of radioactivity were found in the small intestine contents at 0.5 h (112.137 µg equiv/g), urinary bladder contents at 3 h (89.636 µg equiv/g) and probably reflect excretion of drug and metabolites. The highest concentrations in specific organs were found in the renal cortex at 1 h (28.582 µg equiv/g), small intestine at 3 h (16.946 µg equiv/g), Harderian gland at 3 h (12.332 µg equiv/g) and pancreas at 3 h (12.635 µg equiv/g). Concentrations in the cerebrum (1.978 µg equiv/g), cerebellum (2.109 µg equiv/g), medulla (1.797 µg equiv/g) and spinal cord (1.510 µg equiv/g) were maximal at 0.5 h post-dose and persisted for 7 days.4. The predicted total body and target organ exposures for humans given a single 100 µCi IV dose of [14C]VNP40101M were well within the medical guidelines for maximum radioactivity exposures in human subjects.

Purity assessment of organic calibration standards using a combination of quantitative NMR and mass balance.

Quantitative NMR spectroscopy (qNMR) has been examined for purity assessment using a range of organic calibration standards of varying structural complexities, certified using the traditional mass balance approach. Demonstrated equivalence between the two independent purity values confirmed the accuracy of qNMR and highlighted the benefit of using both methods in tandem to minimise the potential for hidden bias, thereby conferring greater confidence in the overall purity assessment. A comprehensive approach to purity assessment is detailed, utilising, where appropriate, multiple peaks in the qNMR spectrum, chosen on the basis of scientific reason and statistical analysis. Two examples are presented in which differences between the purity assignment by qNMR and mass balance are addressed in different ways depending on the requirement of the end user, affording fit-for-purpose calibration standards in a cost-effective manner.

Establishment of the purity values of carbohydrate certified reference materials using quantitative nuclear magnetic resonance and mass balance approach

This work described the assignment of purity values to six carbohydrate certified reference materials, including glucose, fructose, galactose, lactose, xylose and sucrose, according to the ISO Guides 34 and 35. The CRMs’ purity values were assigned based on the weighted average of quantitative nuclear magnetic resonance method and mass balance approach with high resolution liquid chromatography – evaporative light scattering detection. All the six CRMs with following value amount fractions: glucose (GBW10062) at a certified purity P±U (k=2) of (0.99±0.005)%; fructose (GBW10063) at (0.99±0.005)%; galactose (GBW10064) at (0.99±0.007)%; lactose (GBW10065) at (0.99±0.008)%; xylose (GBW10066) at (0.99±0.007)% and sucrose (GBW10067) at (0.99±0.008)%, respectively were certified. The homogeneity of the CRMs was determined by an in-house validated liquid chromatographic method. Potential degradation during storage was also investigated and a shelf-life based on this value was established.

Soil ingestion rate determination in a rural population of Alberta, Canada practicing a wilderness lifestyle

The inadvertent ingestion of contaminated soil can be a major pathway for chemical exposure to humans. Few studies to date have quantified soil ingestion rates to develop exposure estimates for human health risk assessments (HHRA), and almost all of those were for children in suburban/urban environments. Here we employed a quantitative mass balance tracer approach on a rural population practicing outdoor activities to estimate inadvertent soil ingestion. This study followed 9 subjects over a 13day period in Cold Lake, Alberta, near the largest in situ thermal heavy oil (bitumen) extraction operation in the world. The mean soil ingestion rate in this study using Al Ce, La, and Si tracers was 32mgd−1, with a 90th percentile of 152mgd−1 and median soil ingestion rate of 18mgd−1. These soil ingestion values are greater than the standard recommended soil ingestion rates for HHRA from Health Canada, and are similar to soil ingestion estimates found in the only other study on a rural population.