ACS Environmental Au最新文献

Heterogeneous Fenton and Fenton-like reactions, as one of the significant development directions of advanced oxidation processes (AOPs), still have some limitations that hinder their large-scale practical application. Organic carbon transfer processes (OCTPs) in AOPs including direct oxidation transfer processes (DOTPs) and changes in the solubility of pollutant reaction intermediates can lead to a significant accumulation of organics on the catalyst. The accumulation of organics severely impacts the sustainability of the catalyst and may lead to erroneous guidance about the mineralization rate of the reaction system. This perspective provides a comprehensive overview of recent research on OCTPs and presents new viewpoints and research directions for heterogeneous AOPs.

Chemical reduction with sodium borohydride has been used for over four decades to probe the presence and function of carbonyl-containing moieties in dissolved organic matter (DOM). One of these structure-property relationships is the attenuation of UV-visible absorbance after borohydride reduction, an effect that has been observed universally across DOM of different origins. We previously demonstrated that DOM with similar bulk physicochemical properties exhibits bifurcating reactivity with borohydride depending on the source (i.e., soil vs. aquatic), as judged by the kinetics of fractional absorbance removal during reduction at a fixed borohydride:DOM mass ratio. This result and data from other studies suggest that a portion of borohydride-reducible chromophores in DOM may be inaccessible to the water solvent, explaining the incomplete absorbance attenuation even at very high borohydride mass excesses. Here, we study the reactivity of five DOM isolates with sodium borohydride via size exclusion chromatography coupled to total organic carbon, absorbance, and fluorescence detectors. Reduction with sodium borohydride resulted in quantifiable yet exceedingly small decreases in DOM molecular weight, suggesting that the reduction of carbonyl groups to alcohols does not markedly impact the DOM secondary structure. Interestingly, higher molecular weight DOM exhibited the most prominent changes in optical properties after reduction, suggesting that larger molecules contain a high proportion of borohydride-reducible moieties. Optical surrogates were inversely correlated to molecular weight across a single isolate, both native and reduced. However, the correlation broke down at lower molecular weights, wherein optical surrogates remained constant with continued decreases in elution volume, suggesting that there is an intrinsic lower limit to the ability of optical surrogates to capture further decreases in molecular weight. Overall, these results provide insights into the DOM structure and help inform future applications of sodium borohydride for studying the DOM source and reactivity.

Natural and anthropogenic emissions of sulfur-bearing species significantly alter the sulfur and energy budgets of the Earth's atmosphere. Simulations of the atmospheric sulfur cycle, sulfate radiative forcing, and predictions of their future changes require a precise understanding of the SO₂ oxidation rates that control the formation of secondary sulfate aerosols. Given the unique single source of radiosulfur (cosmogenic ³⁵S radionuclide), combined measurements of atmospheric radiosulfur in both sulfur dioxide (³⁵SO₂) and sulfate (³⁵SO₄ ^2-) have been employed to constrain sulfur oxidation rates in the atmosphere. This approach employed box model calculations, incorporating several key assumed parameters, including sulfur deposition rates. However, previous calculations did not fully consider uncertainties in parametrizations, necessitating a re-examination of the estimated values. In this study, we applied a new approach to revisit existing combined measurements of ³⁵SO₂ and ³⁵SO₄ ^2- at coastal and inland sites. We estimated the temporospatial variability in SO₂ oxidation rates by incorporating a comprehensive consideration of parametrization uncertainties. We adopted deposition data from nine models of the Atmospheric Chemistry and Climate Model Intercomparison Project. Uncertainties in deposition data and other key parameters, such as cosmogenic ³⁵S production rates and ³⁵SO₂/³⁵SO₄ ^2- ratios in the free troposphere, were evaluated by using a Monte Carlo approach. Our new analysis reveals higher SO₂ oxidation rates than previously estimated, consistent with recent multiphase kinetics studies. Additionally, the potential relationship between changes in SO₂ oxidation rates and sulfate formation pathways was elucidated by comparing these results to sulfate oxygen-17 anomalies. Our approach and findings offer a stringent assessment of how various sulfate formation pathways contribute to the overall SO₂ oxidation rate in the planetary boundary layer and are therefore useful for evaluating the impacts of the atmospheric sulfur cycle on environmental health, public health, and climate.

The aim of this study was to comprehensively assess the effect of environmentally friendly wax coatings, including beeswax, soywax, TopScreen biowax, and a conventional water-based emulsion wax on paper for food packaging applications. A food-grade paper was bar-coated with a single layer of molten wax on both sides, varying in the coating weight, coating thickness, and wax type. Waxes were thoroughly characterized in terms of their functional groups, thermal properties, degree of crystallinity, and crystal morphology using polarized optical microscopy. Thereafter, wax-coated papers were studied in terms of their morphological, mechanical, and water vapor barrier properties. Moreover, the water and oil contact angles were measured to determine the resistance of wax-coated papers to moisture and grease penetration. Wax coatings represent 10-25% of the weight of the coated paper, with a coating thickness of 5-10 μm. Scanning electron microscopy images showed that waxes penetrated the cellulosic fibers of the paper, thereby effectively reducing its porous structure. Water and oil contact angles of the uncoated paper increased after the wax coating. Among the four waxes, beeswax-coated paper was characterized as having superior capability in improving the water vapor barrier of the uncoated paper (by ∼77%). While the percentage elongation at break (EB %) decreased for all four wax-coated papers, tensile strength (TS) and elastic modulus (E) increased, with beeswax showing the highest percent improvement in TS (by ∼26%) and E (by ∼46%). Our results suggest that paper surface modification through ecofriendly wax coatings can be utilized as an alternative for petroleum-based paper coating materials for food packaging applications.

Anaerobic digestion (AD) systems are vital for converting organic waste to green bioenergy but also serve as a non-negligible environmental reservoir for antibiotic-resistance genes (ARGs) and resistant bacteria of environmental and human health concerns. This study profiles the antibiotic resistome of 90 full-scale biogas reactors and reveals that AD microbiomes harbor at least 30 types and 1257 subtypes of ARGs, of which 16% are located on plasmids showing potential mobility. The total abundance of AD-ARGs ranges widely from 0.13 to 7.81 copies per cell and is distributed into 42-739 subtypes, significantly influenced (P < 0.05) by operational conditions like digestion temperature and substrate types. Compared with the ambient and mesophilic digesters, the thermophilic digesters harbor a significantly lower abundance and diversity as well as greatly reduced mobility and host pathogenicity levels (all P < 0.05) of ARGs, revealing that a higher digestion temperature mitigates the overall resistome risks. The comprehensive analysis of basic traits and key traits of the AD resistome is demonstrated to provide crucial quantitative and qualitative insights into the diversity, distribution pattern, and health risks of ARGs in full-scale AD systems. The revealed knowledge offers new guidance for improving environmental resistome management and developing oriented mitigation strategies to minimize the unwanted spread of clinically important antimicrobial resistance from AD systems.