A Novel Chondroitin AC Lyase With Broad Substrate Specificity From Pedobacter rhizosphaerae: Cloning, Expression, and Characterization

Chondroitin AC lyase (ChSaseAC) is one of the essential polysaccharides lyases in low molecular chondroitin sulfate production. In this work, a novel PrChSaseAC from Pedobacter rhizosphaerae was successfully cloned, expressed in Escherichia coli. After optimizing the induction, the recombinant PrChSaseAC could be expressed efficiently at 0.1 mM IPTG, 25°C, and 12 h induction. Then, it was purified with Ni-NTA affinity chromatography. The characterization of the purified PrChSaseAC showed that it had high specific activity and good storage stability, which would favor the production of low molecular weight chondroitin sulfate. It also displayed activity toward chondroitin sulfate C and hyaluronic acid. PrChSaseAC had the highest activity at pH 7.5, 37°C, 10 mM Ca2+, and 5 mg/ml of chondroitin sulfate A. Molecular docking of substrate and enzyme showed the interactions between the enzyme and substrate; it revealed that the enzyme showed high activity to CS-A and hyaluronic acid, but lower activity to CS-C attributed to the structure of the binding pocket. The high stability and specific activity of the enzyme will benefit the industrial production or clinical treatment.

The Utilization of Lapindo Mud Waste for Aluminium Sulfate Production

The Lapindo mudflow disaster in East Java Province, or also known as LUSI (LUmpur “mud”-SIdoarjo) has become spectacular longest ongoing disaster in recent memory since 2006. The utilization of volcanic Lapindo mud could be the promising solution to prevent further environmental damage. The chemical composition of Lapindo mud contained of 44.1% SiO2, 23.7% Fe2O3, 13% Al2O3, 7.02% CaO, 5.35% MoO3, 2.53% K2O, 1.84% TiO2 and 0.7% Na2O. Aluminium sulfate (Al2(SO4)3) or “alum” have been widely used as coagulation compound in water treatment, paper and textiles industry. Aluminium sulfate can be synthesized from aluminium oxide (Al2O3) from Lapindo mud with acidic solutions (H2SO4). The aim of this work was to synthesize aluminum sulfate from Lapindo mud by using extraction process. The impact of H2SO4 concentration and heating time to the production of aluminium sulfate have been investigated. The results showed that the aluminium sulfate can be synthesized from Lapindo mud by using H2SO4. Based on XRF analysis, the variation of heating time and H2SO4 concentration affect the aluminium sulfate conversion. The increasing of heating time and H2SO4 concentration directly enhance the conversion until reach the optimum condition. The optimum condition for aluminium sulfate synthesis from Lapindo mud (75.78% conversion) was found to be 90 min for heating time with H2SO4 concentration of 80%

Multiphase processes in the EC-Earth Earth System model and their relevance to the atmospheric oxalate, sulfate, and iron cycles

Understanding how multiphase processes affect the iron-containing aerosol cycle is key to predict ocean biogeochemistry changes and hence the feedback effects on climate. For this work, the EC-Earth Earth system model in its climate-chemistry configuration is used to simulate the global atmospheric oxalate (OXL), sulfate (SO42−), and iron (Fe) cycles, after incorporating a comprehensive representation of the multiphase chemistry in cloud droplets and aerosol water. The model considers a detailed gas-phase chemistry scheme, all major aerosol components, and the partitioning of gases in aerosol and atmospheric water phases. The dissolution of Fe-containing aerosols accounts kinetically for the solution’s acidity, oxalic acid, and irradiation. Aerosol acidity is explicitly calculated in the model, both for accumulation and coarse modes, accounting for thermodynamic processes involving inorganic and crustal species from sea salt and dust. Simulations for present-day conditions (2000–2014) have been carried out with both EC-Earth and the atmospheric composition component of the model in standalone mode driven by meteorological fields from ECMWF’s ERA-Interim reanalysis. The calculated global budgets are presented and the links between the 1) aqueous-phase processes, 2) aerosol dissolution, and 3) atmospheric composition, are demonstrated and quantified. The model results are supported by comparison to available observations. We obtain an average global OXL net chemical production of 12.61 ± 0.06 Tg yr−1 in EC-Earth, with glyoxal being by far the most important precursor of oxalic acid. In comparison to the ERA-Interim simulation, differences in atmospheric dynamics as well as the simulated weaker oxidizing capacity in EC-Earth result overall in a ~30 % lower OXL source. On the other hand, the more explicit representation of the aqueous-phase chemistry in EC-Earth compared to the previous versions of the model leads to an overall ~20 % higher sulfate production, but still well correlated with atmospheric observations. The total Fe dissolution rate in EC-Earth is calculated at 0.806 ± 0.014 Tg Fe yr−1 and is added to the primary dissolved Fe (DFe) sources from dust and combustion aerosols in the model (0.072 ± 0.001 Tg Fe yr−1). The simulated DFe concentrations show a satisfactory comparison with available observations, indicating an atmospheric burden of ∼0.007 Tg Fe, and overall resulting in an atmospheric deposition flux into the global ocean of 0.376 ± 0.005 Tg Fe yr−1, well within the range reported in the literature. All in all, this work is a first step towards the development of EC-Earth into an Earth System Model with fully interactive bioavailable atmospheric Fe inputs to the marine biogeochemistry component of the model.

A comprehensive observation-based multiphase chemical model analysis of sulfur dioxide oxidations in both summer and winter

Sulfate is one of the main components of haze fine particles, and its formation mechanism remains controversial. A lack of detailed and comprehensive field data hinders the accurate evaluation of relative roles of prevailing sulfate formation pathways. Here, we analyzed the sulfate production rates using a state-of-the-art multiphase model constrained to the observed concentrations of transition metal, nitrogen dioxide, ozone, hydrogen peroxide and other important parameters in winter and summer in the North China Plain. Our results showed that aqueous transition metal ion (TMI)-catalyzed oxidation was the most important pathway followed by the surface oxidation of Mn in both winter and summer while the hydroxyl and Criegee radical oxidations contribute significantly in summer. In addition, we also modeled the published cases for the fog and cloud conditions. It is found that nitrogen dioxide oxidation is the dominant pathway for the fog in a higher pH range while hydroperoxide and ozone oxidations dominated for the cloud.

Description and evaluation of the tropospheric aerosol scheme in the Integrated Forecasting System (IFS-AER, cycle 47R1) of ECMWF

This article describes the IFS-AER aerosol scheme used operationally in the Integrated Forecasting System (IFS) cycle 47R1, operated by the European Centre for Medium Range Weather Forecasts (ECMWF) in the framework of the Copernicus Atmosphere Monitoring Services (CAMS). It represents an update of the Rémy et al. (2019) article which focused on cycle 45R1 of IFS-AER. The parameterizations of sources and sinks that have been updated since cycle 45R1 are described, as well as changes in the configuration used operationally within CAMS. As compared to cycle 45R1, a greater integration of aerosol and chemistry has been achieved. Primary aerosol sources have been updated, with the implementation of new dust and seasalt aerosol emission schemes. New dry and wet deposition parameterizations have also been implemented. Sulfate production rates are now provided by the global chemistry component of the IFS. This paper aims to describe most of the updates that have been implemented since cycle 45R1 and not only the ones that are used operationally in cycle 47R1; components that are not used operationally will be clearly flagged. Cycle 47R1 of IFS-AER has been evaluated against a wide range surface and total column observations. The final simulated products such as Particulate Matter (PM) and Aerosol Optical Depth (AOD) generally show a significant increase in skill as compared to results obtained with cycle 45R1. Similarly, the simulated surface concentration of sulphate, organic matter and sea-salt aerosol is improved by cycle 47R1 as compared to cycle 45R1. Some imbalances persist, such as a too high surface concentration of nitrate and organic matter. The new wet and dry deposition schemes that have been implemented into cycle 47R1 have a mostly positive impact on simulated AOD, PM and speciated aerosol surface concentration.

Life cycle assessment and process simulation of prospective battery-grade cobalt sulfate production from Co-Au ores in Finland

Purpose The soaring demand for cobalt for lithium-ion batteries has increased interest in the utilization of non-conventional cobalt sources. Such raw materials include complex ores containing minerals such as cobaltite and skutterudite, which, while rare, occur around the world, including in Finland, Canada, and the USA. The goal of this study was to evaluate the cradle-to-gate impacts of cobalt sulfate recovery from unutilized cobalt- and gold-bearing ores with the use of process simulation. Methods A literature analysis was conducted to establish the state-of-the-art processing methods for complex cobalt ores containing significant amounts of gold. The drafted process was simulated using HSC Sim software to obtain a mass and energy balance, which was compiled into a life cycle inventory (LCI). The environmental impact categories (global warming, acidification, eutrophication, ozone depletion, photochemical smog creation, water use) were calculated in GaBi software. Uncertainty regarding the possible future raw material composition was studied, and the simulation was used to investigate process performance and to evaluate the effect of variation in the process parameters on the environmental impact indicators. Results and discussion The results indicated that the main cobalt mineral type (cobaltite, linnaeite) had only minor effects on the evaluated impact categories. With cobaltite-dominated ores (High As case), the global warming potential (GWP) was estimated to be 20.9 kg CO2-eq, of which 12.7 kg CO2-eq was attributed to the hydrometallurgical process. With linnaeite-dominated ores, the equivalent values were 20.4 kg CO2-eq and 11.0 kg CO2-eq. The production of a high grade concentrate was observed to greatly decrease the impacts of the hydrometallurgical process, but the cobalt losses in the beneficiation stage and the mineral processing impacts would likely increase. The simulation showed that there is still potential to improve the cobalt recovery (to approximately 96%), which would also affect the indicator values. Conclusions The impacts were estimated prior to intensive metallurgical testing to determine the possible high impact areas in the process. Based on this, it is suggested that, during hydrometallurgical processing, improved treatment of cobalt-containing wash waters and the optimization of oxygen utilization efficiency in pressure leaching are the most significant ways to decrease the environmental impacts. Optimal solutions for the concentrate could be found when experimental data on the minerals processing steps becomes available.

Towards a chemical mechanism of the oxidation of aqueous sulfur dioxide via isoprene hydroxyl hydroperoxides (ISOPOOH)

In-cloud chemistry has important ramifications for atmospheric particulate matter formation and gas-phase chemistry. Recent work has shown that, like hydrogen peroxide (H2O2), the two main isomers of isoprene hydroxyl hydroperoxide (ISOPOOH) oxidize sulfur dioxide dissolved in cloud droplets (SO2,aq) to sulfate. The work revealed that the pathway of SO2,aq oxidation with ISOPOOH differs from that of H2O2. We investigate the chemical mechanisms of oxidation of SO2,aq with ISOPOOH in the cloud-relevant pH range of 3–6 and compare them with the previously reported mechanisms of oxidation of SO2,aq with H2O2, methyl hydroperoxide and peroxyacetic acid. The organic products of the reaction are identified, and two pathways are proposed. For 1,2-ISOPOOH, a higher yield pathway via proposed radical intermediates yields methyl vinyl ketone (MVK) and formaldehyde, which can react to hydroxymethanesulfonate (HMS) when SO2,aq is present. A lower yield non-fragmentation oxygen addition pathway is proposed that results in the formation of isoprene-derived diols (ISOPOH). Based on global simulations, this mechanism is not a significant pathway for formation of MVK and formaldehyde relative to their gas-phase formation but, as previously reported, it can be regionally important for sulfate production. The study adds to previous work that highlights similarities and differences between gas-phase and cloud-droplet processing of reactive organic carbon.