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Mercury (Hg), a global contaminant, is emitted mainly in its elemental form Hg⁰ to the atmosphere where it is oxidized to reactive HgII compounds, which efficiently deposit to surface ecosystems. Therefore, the chemical cycling between the elemental and oxidized Hg forms in the atmosphere determines the scale and geographical pattern of global Hg deposition. Recent advances in the photochemistry of gas-phase oxidized HgI and HgII species postulate their photodissociation back to Hg⁰ as a crucial step in the atmospheric Hg redox cycle. However, the significance of these photodissociation mechanisms on atmospheric Hg chemistry, lifetime, and surface deposition remains uncertain. Here we implement a comprehensive and quantitative mechanism of the photochemical and thermal atmospheric reactions between Hg⁰, HgI, and HgII species in a global model and evaluate the results against atmospheric Hg observations. We find that the photochemistry of HgI and HgII leads to insufficient Hg oxidation globally. The combined efficient photoreduction of HgI and HgII to Hg⁰ competes with thermal oxidation of Hg⁰, resulting in a large model overestimation of 99% of measured Hg⁰ and underestimation of 51% of oxidized Hg and ∼66% of HgII wet deposition. This in turn leads to a significant increase in the calculated global atmospheric Hg lifetime of 20 mo, which is unrealistically longer than the 3–6-mo range based on observed atmospheric Hg variability. These results show that the HgI and HgII photoreduction processes largely offset the efficiency of bromine-initiated Hg⁰ oxidation and reveal missing Hg oxidation processes in the troposphere.

Anthropogenic mercury (Hg(0)) emissions oxidize to gaseous Hg(II) compounds, before deposition to Earth surface ecosystems. Atmospheric reduction of Hg(II) competes with deposition, thereby modifying the magnitude and pattern of Hg deposition. Global Hg models have postulated that Hg(II) reduction in the atmosphere occurs through aqueous-phase photoreduction that may take place in clouds. Here we report that experimental rainfall Hg(II) photoreduction rates are much slower than modelled rates. We compute absorption cross sections of Hg(II) compounds and show that fast gas-phase Hg(II) photolysis can dominate atmospheric mercury reduction and lead to a substantial increase in the modelled, global atmospheric Hg lifetime by a factor two. Models with Hg(II) photolysis show enhanced Hg(0) deposition to land, which may prolong recovery of aquatic ecosystems long after Hg emissions are lowered, due to the longer residence time of Hg in soils compared with the ocean. Fast Hg(II) photolysis substantially changes atmospheric Hg dynamics and requires further assessment at regional and local scales. Reduction of gaseous Hg(II) compounds drives atmospheric mercury wet and dry deposition to Earth surface ecosystems. Global Hg models assume this reduction takes place in clouds. Here the authors report a new gas-phase Hg photochemical mechanism that changes atmospheric mercury lifetime and its deposition to the surface.

Mercury is a persistent pollutant with significant public health impacts in polar regions where fish consumption drives human exposure. Atmospheric oxidation pathways control where mercury deposits globally, but the lack of molecular-level observations of oxidized mercury products has hindered the validation of proposed chemical mechanisms. Here, we show the in-situ online detection of individual mercuric halides (HgCl 2 , BrHgCl, HgBr 2 , ClHgI, BrHgI, and HgI 2 ) in the polar boundary layer using atmospheric pressure chemical ionization mass spectrometry. Our observations identify HgBr 2 as the dominant oxidized mercury species at both poles, while HgCl 2 and other halides were also observed in Antarctica. The observed speciation diverges from current model predictions, which favor HgCl 2 and HOHgBr as dominant oxidized forms. Our results show that real-time molecular measurements can substantially advance global mercury monitoring and improve the chemical models used to assess environmental policies and predict deposition patterns. Researchers report real-time molecular detection of oxidized mercury species in the polar atmosphere, revealing discrepancies with current models and advancing understanding of neurotoxic mercury cycling in sensitive ecosystems.

In this study, sixteen secondary metabolites, including two chromones, four dibenzofurans, three lipids, three depsides, two aromatic compounds, a quinone, and a terpene, were detected in the methanol:acetone (1:1 v/v) extract of the lichen Hypotrachyna enderythraea (Zahlbr.) Hale, using High-Performance Liquid Chromatography coupled to Orbitrap Electrospray Ionization tandem Mass Spectrometry (HPLC-Orbitrap ESI tandem MS/MS). These metabolites were characterized by analysis of their exact molecular masses and corresponding fragmentation patterns. The retention times of the identified metabolites were compared with those of standard compounds, confirming the presence of naturally occurring bioactive compounds. Density Functional Theory (DFT) calculations were employed to investigate preferential deprotonation sites in representative polyprotic metabolites. All these findings may contribute to expanding the spectrum of compounds identified within the genus Hypotrachyna and to evaluating their potential biological activities.

A new biosorbent based on Nostoc commune (NC) cyanobacteria, chemically modified with NaOH (NCM), has been prepared, characterized and tested as an effective biomass to remove Pb(II) in aqueous media. The adsorption capacity of NCM was determined to be qe = 384.6 mg g−1. It is higher than several other biosorbents reported in the literature. Structural and morphological characterization were performed by FTIR, SEM/EDX and point zero of charge pH (pHPZC) measurements. NCM biosorbent showed more porous surfaces than those NC with heterogeneous plates including functional adsorption groups such as OH, C = O, COO−, COH or NH. Optimal Pb(II) adsorption occurred at pH 4.5 and 5.5 with a biomass dose of 0.5 g L−1. The experimental data of the adsorption process were well fitted with the Freundlich-isotherm model and pseudo-2nd order kinetics, which indicated that Pb(II) adsorption was a chemisorption process on heterogeneous surfaces of NCM. According to the thermodynamic parameters, this process was exothermic (∆H0 < 0), feasible and spontaneous (∆G0 < 0). NCM can be regenerated and efficiently reused up to 4 times (%D > 92%). NCM was also tested to remove Pb (%R~98%) and Ca (%R~64%) from real wastewater.

In this study, cladodes of Opuntia ficus indica (OFIC), chemically modified with NaOH (OFICM), have been prepared, characterized, and tested as an effective biomass to remove Pb(II) and/or Cd(II) from aqueous media. At an optimum pH of 4.5, the adsorption capacity, qe, of treated OFICM was almost four times higher than that of untreated OFIC. The maximum adsorption capacities (qmax) in the single removal of Pb(II) and Cd(II) were 116.8 and 64.7 mg g−1, respectively. These values were 12.1% and 70.6% higher than those for the corresponding qmax in binary removal, which indicates the strong inhibitive effect of Pb(II) on the co-cation Cd(II) in a binary system. Structural and morphological characterization have been carried out by FTIR, SEM/EDX, and point of zero charge (pHPZC) measurements. The SEM/EDX results confirmed that the metals are adsorbed on the surface. The presence of C-O, C=O, and COO- functional groups were identified by FTIR on both OFIC and OFICM surfaces. On the other hand, we found that the adsorption processes followed the pseudo-second-order kinetics for both single and binary systems, with a fast biosorption rate of Pb(II) and Cd(II). The equilibrium data (adsorption isotherms) were better described by Langmuir and modified-Langmuir models for single and binary systems, respectively. A good regeneration of OFICM was obtained with an eluent of 0.1 M HNO3. Therefore, OFICM can be efficiently reused to remove Pb or Cd, up to three times.

Tropaeolum tuberosum (mashua) is a native Andean tuber recognized for its high nutritional and bioactive compound content. Among the various morphotypes, the black and yellow variants show potential differences in composition and functionality. This study aimed to compare the thermo-energetic, nutritional, and physicochemical characteristics of two morphotypes (black and yellow) of Tropaeolum tuberosum flour from the Peruvian Andes. Flours were obtained from tubers harvested in Ayacucho, Peru, and analyzed using elemental analysis for carbon, hydrogen, nitrogen, and sulfur (CHNS), inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and bomb calorimetry. The empirical formula is CH1.74O0.91N0.06S0.005 for black mashua and CH1.78O0.92N0.05S0.005 for yellow mashua. Black flour exhibited higher protein (17.6% vs. 14.8%) and fat contents (8.0% vs. 6.7%), along with nearly double the iron content. Both flours showed similar starch granule morphology and gelatinization enthalpy (~2 J/g), but the black flour had higher gelatinization temperatures. Calorimetric analysis revealed a greater net calorific value (qNCV) in black mashua flour (4157 ± 22 kcal/kg) than in yellow flour (4022 ± 19 kcal/kg). The thermogravimetric profiles indicated good thermal stability with approximately 30% residual mass. These findings suggested that black mashua flour possesses superior nutritional and energy characteristics, supporting its application in functional food formulations and energy-rich gluten-free products.

Theobroma cacao agro-industrial waste (WTC) has been characterized and tested as an effective biosorbent to remove Cd(II) from aqueous media. At the optimum pH of 5.0, a maximum adsorption capacity of qe,max = 58.5 mg g−1 was determined. The structural and morphological characterization have been conducted by FTIR, SEM/EDX, and TGA measurements. The SEM/EDX results confirmed that the metals are adsorbed on the surface. C-O-C, OH, CH, NH, and C=O functional groups were identified by FTIR. TGA results were consistent with the presence of hemicellulose. Biosorption kinetics were rapid during the first 30 min and then reached equilibrium. The corresponding experimental data were well fitted to pseudo-first and -second order models, the latter being the best. The biosorption isotherm data were also well fitted to Temkin, Langmuir, and Freundlich models, showing that several sorption mechanisms may be involved in the Cd(II) biosorption process, which was characterized as exothermic (ΔH0 < 0), feasible, and spontaneous (ΔG0 < 0). In binary (Cd–Pb and Cd–Cu) and ternary (Cd–Pb–Cu) systems, Cu(II) and particularly Pb(II) co-cations exert strong antagonistic effects. Using HNO3, effective good regeneration of WTC was obtained to efficiently remove Cd(II) up to three times.

Arabica-coffee and Theobroma-cocoa agroindustrial wastes were treated with NaOH and characterized to efficiently remove Pb(II) from the aqueous media. The maximum Pb(II) adsorption capacities, qmax, of Arabica-coffee (WCAM) and Theobroma-cocoa (WCTM) biosorbents (qmax = 303.0 and 223.1 mg·g−1, respectively) were almost twice that of the corresponding untreated wastes and were higher than those of other similar agro-industrial biosorbents reported in the literature. Structural, chemical, and morphological characterization were performed by FT-IR, SEM/EDX, and point of zero charge (pHPZC) measurements. Both the WCAM and WCTM biosorbents showed typical uneven and rough cracked surfaces including the OH, C=O, COH, and C-O-C functional adsorbing groups. The optimal Pb(II) adsorption, reaching a high removal efficiency %R (>90%), occurred at a pH between 4 and 5 with a biosorbent dose of 2 g·L−1. The experimental data for Pb(II) adsorption on WACM and WCTM were well fitted with the Langmuir-isotherm and pseudo-second order kinetic models. These indicated that Pb(II) adsorption is a chemisorption process with the presence of a monolayer mechanism. In addition, the deduced thermodynamic parameters showed the endothermic (ΔH0 > 0), feasible, and spontaneous (ΔG0 < 0) nature of the adsorption processes studied.

Six new phenyl‐1 H ‐pyrazole‐carbaldehyde isonicotinylhydrazone derivatives 1-10 were synthesized and characterized by spectroscopic (FT‐IR, 1H NMR, and 13C NMR) techniques and electrospray ionization–mass spectrometry (ESI–MS). Homonuclear data from 2D‐NMR ( 1 H‐ 1 H NOESY) revealed that 3 and 5 adopt the transE isomeric form. The in vitro antitubercular activity of all the synthesized compounds was determined against Mycobacterium tuberculosis (sensitive H37RV and resistant TB DM97). With respect to the isoniazid (INH) standard drug (MIC = 0.91 μM), all the prepared compounds showed greater antitubercular activity with MIC values in the range of 0.38–0.82 μM against Mtb H37Rv‐sensitive strain. However, the preliminary results indicated that Compounds 1 – 10 tested against the TB DM97‐resistant strain showed low bioactivity. The optimized geometry of Compounds 1 – 10 has been determined by density functional theory (DFT) calculations. For Compounds 1 – 6 , the most stable isomers (in DMSO) exhibited an E geometrical configuration, while Compounds 7–10 exhibited a Z configuration. The global reactivity values indicate that Compounds 1 – 10 are slightly more reactive and less stable than the standard (INH). Additionally, they exhibit a strong binding capacity to biomolecules, comparable to INH. The MEP map reveals that the negative and positive potential sites are predominantly located on the C=O and HN–NH groups, respectively, similar to those observed for INH. Drug‐likeness and ADME properties were evaluated. All compounds showed adequate ADME properties and are drug‐like. Molecular docking studies (Compounds 1 – 10 ) into the active site of mycobacterial InhA showed an acceptable dissociation constant with improved binding energy (from −6.7 to −8.1 kcal mol −1 ) compared to isoniazid (−5.6 kcal mol −1 ). Molecular dynamics simulations revealed that the molecules cmp3 (3) and cmp5 (5) form stable ternary complexes with InhA through persistent hydrogen bonding and hydrophobic interactions. These compounds showed reduced active‐site fluctuations and superior binding free energies compared to INH. The findings represent a significant advancement in the discovery of potential antitubercular agents.