ACS Environmental Au最新文献

Secondary organic aerosol (SOA) has been shown to significantly impact climate, air quality, and human health. Hydroxyl dicarboxylic acids (OHDCA) are generally of secondary origin and ubiquitous in the atmosphere, with high concentrations in South China. This study explored the formation of representative OHDCA species based on time-resolved measurements and explainable machine learning. Malic acid, the most commonly studied OHDCA, had higher concentrations in the noncontinental air (63.7 ± 33.3 ng m^-3) than in the continental air (7.5 ± 1.4 ng m^-3). Machine learning quantitatively revealed the high relative importance of aromatics and monoterpenes SOA, as well as aqueous processes, in the noncontinental air, due to either shared precursors or similar formation pathways. Isoprene SOA, particle surface area, and ozone corrected for titration loss (O _x ) also elevated the concentrations of malic acid in the continental air. Aqueous photochemical formation of malic acid was confirmed given the synergy between LWC, temperature, and O _x . Moreover, the OHDCA-like SOA might have facilitated a relatively rare particle growth from early afternoon to midnight in the case with the highest malic acid concentrations. This study enhances our understanding of the formation of OHDCA and its climate impacts.

CO is both a key intermediate in the electrocatalytic conversion of CO₂ and a valuable C₁ resource, with the potential to reduce carbon emissions and mitigate the energy crisis. However, industrially emitted CO remains underutilized due to inefficiencies and economic challenges. Electrocatalytic CO reduction offers a promising approach for the efficient and environmentally friendly utilization of CO-containing flue gases. Nevertheless, current technologies face limitations, such as low operating currents and difficulties in adaptation to complex reaction gas components. Here, we report a low-cost silver-doped porous copper oxide (Ag-pCuO) catalyst. The doping of a moderate amount of Ag (0.875% doping) endows porous CuO with highly selective Cu-Ag active sites, enhanced CO adsorption, and improved surface valence stability, allowing Ag_0.875%-pCuO to achieve remarkable catalytic performance in a carbon-doped titanium-based membrane electrode assembly electrolytic cell. It achieves a remarkable C₂₊ faradic efficiency of up to 94% at a high current density of -4 A under a simulated calcium carbide furnace gas atmosphere and demonstrates exceptional stability, with only a 6.08% decline in C₂₊ faradic efficiency after over 110 h of continuous operation. In summary, this research presents a novel approach for applying Ag-doped copper-based catalysts to industrially utilize CO-containing flue gases, especially from calcium carbide furnaces.

Amino-containing compounds are key precursors to highly toxic nitrogenous disinfection byproducts (DBPs) and odorous DBPs, posing a critical challenge for drinking water utilities. This study systematically evaluated the adsorption performance of six commercial powdered activated carbons (PACs) for removing soluble amino-containing compounds using amino acids as model compounds. Among them, PHF and AN PAC demonstrated superior removal efficiencies for six tested amino acids, ranging from 77 to 98% for PHF PAC and 83 to 96% for AN PAC. Subsequent analysis focused on PHF, AN, and HB PACs to investigate adsorption kinetics and effects of water parameters, including initial amino acid concentration, pH, and natural organic matter (NOM) on removal efficiencies. Optimal removal efficiencies were observed for PHF and AN PACs at pH levels between 6 and 8, while increased NOM levels significantly reduced amino acid adsorption. Finally, a hydrogen/deuterium isotopic labeling-based nontargeted analysis was applied to evaluate the removal of amino-containing compounds from source water (represented by Suwannee River standard reference materials). PHF exhibited the highest removal efficiency, achieving a 47% reduction in the total ion chromatogram (TIC) intensity of labeled amino-containing features, followed by AN at 21% and HB at 19%. The decrease in the TIC intensity and number of labeled amino-containing features aligned with the trends observed in adsorption, establishes a consistent ranking of PHF > AN > HB PAC. PAC can be seamlessly integrated into existing drinking water treatment processes and applied on an as-needed basis. Our results could provide valuable guidance for its effective application in water treatment plants.

The composition and environmental impacts of inorganic additives in consumer plastics have received little attention within the plastic pollution discipline relative to organic additives. In this work, X-ray florescence spectroscopy, loss-on-ignition, and inductively coupled plasma mass spectrometry were used to qualitatively and quantitatively characterize inorganic additives from up to 80 consumer plastic items. On average, consumer plastic goods contained ∼8% inorganic additives by mass. Concentrations of each element often varied by orders of magnitude. The most common elements detected were from the alkali metal, alkaline earth metal, and first-row transition metal groups, with Ca, Ti, and Al being most abundant. The diversity and abundance of inorganic additives was notably higher in consumer-grade plastics than in standard plastics routinely used to assess the fate and impacts of plastic pollution. Sunlight exposure readily liberated most elements from consumer plastics, typically in the <10 and <1 μm fractions. However, the relative percent of photochemical liberation varied considerably across element and plastic articles, suggesting that formulation is a key control of their liberation from consumer plastics. Compared to average upper continental crust concentrations, Sb and Zn were most enriched, with median enrichment factors of 2 and 1 orders of magnitude, respectfully. Mass balance calculations indicate that plastic pollution may represent a substantial proportion of natural riverine elemental fluxes, particularly for Sb and Zn, which could reach ∼13% and ∼4% of the global natural riverine fluxes by 2060, respectively. Localized impacts in many small, highly polluted rivers could be even larger. However, such impacts are highly dependent on the riverine plastic loading rate to the ocean. Overall, these findings highlight the need for increased consideration of inorganic additives when assessing the fate and impacts of consumer plastics leaking into the environment.

Wastewater is a significant source of copper to freshwater environments, which can severely harm aquatic life. The bioavailability and toxicity of copper in water are influenced by its complexation with dissolved organic matter (DOM). Speciation models, like the biotic ligand model (BLM) that guides Cu regulations, assume DOM is dominated by humic substances. Research suggests that anthropogenic compounds in wastewater discharge may be important copper binding ligands, although their identities remain largely unknown. To address this knowledge gap, we identified and quantified organic copper species isolated from 24 h composite wastewater samples by solid phase extraction (SPE) using liquid chromatography (LC) with inductively coupled plasma mass spectrometry (ICPMS) and electrospray ionization mass spectrometry (ESIMS). Analyses of samples across different stages of treatment revealed the net removal of Cu (73%) and DOC (66%). LC-ICPMS showed that certain complexes were selectively removed, while others evaded removal or were generated during treatment. Relatively hydrophobic complexes decreased in abundance from the initial to the secondary treatment stage. In contrast, more hydrophilic organic Cu complexes, likely formed during treatment, showed a significant increase from the secondary to the tertiary stage. The molecular mass and formula of seven discrete chromatographically resolved complexes were identified by LC-Orbitrap MS. Six were detected only in wastewater, and one was detected in all the wastewater and river samples. Identification of these compounds provides additional evidence for the formation of new copper-binding ligands during treatment and confirms the presence of nitrogen- and sulfur-containing compounds with copper-chelating properties in the wastewater. These findings demonstrate the utility of LCMS approaches for identifying and quantifying distinct organic-copper species in wastewater, as well as tracking their changes and removal during the treatment process.