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1. A ubiquitous tire rubber–derived chemical induces acute mortality in coho salmon

   https://doi.org/10.1126/science.abd6951  

   Tian, Zhenyu; Zhao, Haoqi; Peter, Katherine T.; Gonzalez, Melissa; Wetzel, Jill; Wu, Christopher; Hu, Ximin; Prat, Jasmine; Mudrock, Emma; Hettinger, Rachel; et al (December 2020, Science)

   In U.S. Pacific Northwest coho salmon (Oncorhynchus kisutch), stormwater exposure annually causes unexplained acute mortality when adult salmon migrate to urban creeks to reproduce. By investigating this phenomenon, we identified a highly toxic quinone transformation product ofN-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), a globally ubiquitous tire rubber antioxidant. Retrospective analysis of representative roadway runoff and stormwater-affected creeks of the U.S. West Coast indicated widespread occurrence of 6PPD-quinone (<0.3 to 19 micrograms per liter) at toxic concentrations (median lethal concentration of 0.8 ± 0.16 micrograms per liter). These results reveal unanticipated risks of 6PPD antioxidants to an aquatic species and imply toxicological relevance for dissipated tire rubber residues. 

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2. Poorly quantified trends in ammonium nitrate remain critical to understand future urban aerosol control strategies

   https://doi.org/10.1126/sciadv.adt8957  

   Ward, Ryan X; Baliaka, Haroula D; Schulze, Benjamin C; Kerr, Gaige H; Crounse, John D; Hasheminassab, Sina; Bahreini, Roya; Dillner, Ann M; Russell, Armistead; Ng, Nga L; et al (May 2025, Science Advances)

   Despite decades of progress in reducing nitrogen oxide (NO_x) emissions, ammonium nitrate (AN) remains the primary inorganic component of particulate matter (PM) in Los Angeles (LA). Using aerosol mass spectrometry over multiple years in LA illustrates the controlling dynamics of AN and their evolution over the past decades. These data suggest that much of the nitric acid (HNO₃) production required to produce AN in LA occurs during the nighttime via heterogeneous hydrolysis of N₂O₅. Further, we show that US Environmental Protection Agency–codified techniques for measuring total PM_2.5fail to quantify the AN component, while low-cost optical sensors demonstrate good agreement. While previous studies suggest that declining NO_xhas reduced AN, we show that HNO₃formation is still substantial and leads to the formation of many tens of micrograms per cubic meter of AN aerosol. Continued focus on reductions in NO_xwill help meet the PM_2.5standards in the LA basin and many other regions. 

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3. Direct electrosynthesis and separation of ammonia and chlorine from waste streams via a stacked membrane-free electrolyzer

   https://doi.org/10.1038/s41467-024-52830-4  

   Gao, Jianan; Ma, Qingquan; Wang, Zhiwei; Rittmann, Bruce E; Zhang, Wen (December 2024, Nature Communications)

   Abstract Electrosynthesis, a viable path to decarbonize the chemical industry, has been harnessed to generate valuable chemicals under ambient conditions. Here, we present a membrane-free flow electrolyzer for paired electrocatalytic upcycling of nitrate (NO₃⁻) and chloride (Cl⁻) to ammonia (NH₃) and chlorine (Cl₂) gases by utilizing waste streams as substitutes for traditional electrolytes. The electrolyzer concurrently couples electrosynthesis and gaseous-product separation, which minimizes the undesired redox reaction between NH₃and Cl₂and thus prevents products loss. Using a three-stacked-modules electrolyzer system, we efficiently processed a reverse osmosis retentate waste stream. This yielded high concentrations of (NH₄)₂SO₄(83.8 mM) and NaClO (243.4 mM) at an electrical cost of 7.1 kWh per kilogram of solid products, while residual NH₃/NH₄⁺(0.3 mM), NO₂⁻(0.2 mM), and Cl₂/HClO/ClO⁻(0.1 mM) pollutants in the waste stream could meet the wastewater discharge regulations for nitrogen- and chlorine-species. This study underscores the value of pairing appropriate half-reactions, utilizing waste streams to replace traditional electrolytes, and merging product synthesis with separation to refine electrosynthesis platforms. 

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4. Syntheses and crystal structures of three triphenylsulfonium salts of manganese(II), iron(III) and cobalt(II)

   https://doi.org/10.1107/S2056989025006668  

   Callaway, Waylan; Elterman, Matthew; Krasilnikov, Nikita; Roberts, Gavin; Rutan, Davis; Spencer, Ty; Padgett, Clifford W; Lynch, Will E (August 2025, Acta Crystallographica Section E Crystallographic Communications)

   Bis(triphenylsulfonium) tetrachloridomanganate(II), (C₁₈H₁₅S)₂[MnCl₄] (I), triphenylsulfonium tetrachloridoferrate(III), (C₁₈H₁₅S)[FeCl₄] (II), and bis(triphenylsulfonium) tetrachloridocobaltate(II), (C₁₈H₁₅S)₂[CoCl₄] (III), crystallize in the monoclinic space groupsP2₁/n[(I) and (III)] andP2₁/c[(II)]. Compounds (I) and (III) each contain two crystallographically independent triphenylsulfonium (TPS⁺) cations in the asymmetric unit, whereas (II) has one. In all three compounds, the sulfonium centers adopt distorted trigonal–pyramidal geometries, with S—C bond lengths falling roughly in the 1.78–1.79 Å range and C—S—C angles observed at about 101 to 106°. The [MCl₄]ⁿ⁻anions (M= Mn²⁺, Fe³⁺, Co²⁺;n= 2,1,2) adopt slightly distorted tetrahedral geometries, withM—Cl bond lengths in the 2.19–2.38 Å range and Cl—M—Cl angles of approximately 104–113°. Hirshfeld surface analyses shows that H...H and H...C contacts dominate the TPS⁺cation environments, whereas H...Cl and shortM—S interactions link each [MCl₄]ⁿ⁻anion to the surrounding cations. In (I) and (III), inversion-centered π–π stacking further consolidates the crystal packing, while in (II) no π–π interactions are observed. 

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5. Quaternary Ammonium‐Containing Polyelectrolyte Brush Particles for Removal of Perrhenate Anion From Water: Effect of N ‐Substituents

   https://doi.org/10.1002/marc.202401087  

   Ojima, Kingsley_O; Dayarathne, Sachini_H; Kelly, Michael_T; Zhao, Bin (February 2025, Macromolecular Rapid Communications)

   Abstract Radioactive pertechnetate (TcO₄⁻) from the nuclear fuel cycle presents a severe risk to the environment due to its large solubility in water and non‐complexing nature. By utilizing the chaotropic properties of TcO₄⁻and its nonradioactive surrogate perrhenate (ReO₄⁻) and the principle of chaotropic interactions, a series of quaternary ammonium‐containing polyelectrolyte brush‐grafted silica particles are designed and applied to remove ReO₄⁻from water. These cationic hairy particles (HPs) are synthesized by surface‐initiated atom transfer radical polymerization of 2‐(N,N‐dimethylamino)ethyl methacrylate and subsequent quaternization with various halogen compounds. Dynamic light scattering (DLS) studies showed that the HPs with sufficiently longN‐alkyl andN‐benzyl substituents underwent sharp size reduction transitions in water when titrated with a KReO₄solution, indicating strong chaotropic interactions between the brushes and ReO₄⁻. All the HPs exhibited fast adsorption kinetics; the HPs with longerN‐alkyl andN‐benzyl substituents showed higher capabilities of removing ReO₄⁻than those with shorterN‐alkyls. Moreover, the brush particles with longerN‐substituents displayed a significantly stronger ability in selective adsorption of ReO₄⁻than the particles with shorterN‐substituents in the presence of competing anions, such as F⁻, Cl⁻, NO₃⁻, and SO₄²⁻. This work opens a new avenue to design high‐performance adsorbent materials for TcO₄⁻and ReO₄⁻. 

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