Enhanced photochemical production of reactive intermediates at the wetland soil-water interface

Self Cite

Hydroxyl radical ( • OH) is a powerful oxidant abundantly found in nature and plays a central role in numerous environmental processes. On-site detection of • OH is highly desirable for real-time assessments of • OH-centered processes and yet is restrained by a lack of an analysis system suitable for field applications. Here, we report the development of a flow-injection chemiluminescence analysis (FIA-CL) system for the continuous field detection of • OH. The system is based on the reaction of • OH with phthalhydrazide to generate 5-hydroxy-2,3-dihydro-1,4phthalazinedione, which emits chemiluminescence (CL) when oxidatively activated by H 2 O 2 and Cu 3+ . The FIA-CL system was successfully validated using the Fenton reaction as a standard • OH source. Unlike traditional absorbance-or fluorescence-based methods, CL detection could minimize interference from an environmental medium (e.g., organic matter), therefore attaining highly sensitive • OH detection (limits of detection and quantification = 0.035 and 0.12 nM, respectively). The broad applications of FIA-CL were illustrated for on-site 24 h detection of • OH produced from photochemical processes in lake water and air, where the temporal variations on • OH productions (1.0−12.2 nM in water and 1.5−37.1 × 10 7 cm −3 in air) agreed well with sunlight photon flux. Further, the FIA-CL system enabled field 24 h field analysis of • OH productions from the oxidation of reduced substances triggered by tidal fluctuations in coastal soils. The superior analytical capability of the FIA-CL system opens new opportunities for monitoring • OH dynamics under field conditions.

Section: Flow-injection Chemiluminescence Analysis Systemmentioning

confidence: 99%

Field Quantification of Hydroxyl Radicals by Flow-Injection Chemiluminescence Analysis with a Portable Device

Yu,

Zheng,

Tan

et al. 2024

Self Cite

“…To investigate the optimal concentration of Fe-based materials, cell proliferation and survival assays of JD37 exposed to the Febased materials of various concentrations (0.1, 1.0, and 5.0 g L −1 ) for different times (1,2,4,8,16, and 24 h) were evaluated with the MTT assay (Nanjing Jiancheng Bioengineering Institute, China). The MTT product was measured at 570 nm on a microplate reader (Infinite M200 PRO, Tecan, Switzerland).…”

Section: Cytotoxicity Of Fe-based Materials On Jd37mentioning

confidence: 99%

“…However, excessive ROS produced by chemical reagents would bring serious impact on the ecological environment and threaten organisms. , Moderate amounts of ROS produced by cell metabolic activities can be a feasible and friendly solution for the degradation of refractory pollutants. Currently, the hot spots of ROS generation via rhizosphere microbial metabolism and regulation have been receiving considerable attention. − Meanwhile, it has been proven that iron-containing minerals can positively regulate microbial extracellular production of ROS. , Therefore, biogenic ROS generation and pollutant degradation mediated by Fe-based materials can be an important biogeochemical process.…”

Section: Introductionmentioning

confidence: 99%

Fe-Based Nanomaterials and Plant Growth Promoting Rhizobacteria Synergistically Degrade Polychlorinated Biphenyls by Producing Extracellular Reactive Oxygen Species

Liu

Zheng

et al. 2023

Plant growth promoting rhizobacteria (PGPR) produce extracellular reactive oxygen species (ROS) to protect plants from external stresses. Fe-based nanomaterials can potentially interact with PGPR and synergistically degrade organic pollutants, yet they have received no study. Here, we studied how the interaction between a typical PGPR (Pseudomonas chlororaphis, JD37) and Fe-based nanomaterials facilitated the degradation of 2,4,4′-trichlorobiphenyl (PCB28), by comparing the zerovalent iron of 20 nm (nZVI20), 100 nm (nZVI100), and 5 μm; iron oxide nanomaterials (α-Fe2O3, γ-Fe2O3, and Fe3O4) of ca. 20 nm; and ferrous and ferric salts. Although all Fe materials (0.1 g L–1) alone could not degrade aqueous PCB28 (0.1 mg L–1) under dark or aerobic conditions, nZVI20, nZVI100, α-Fe2O3, and Fe2+ promoted PCB28 degradation by JD37, with the half-life of PCB28 shortened from 16.5 h by JD37 alone to 8.1 h with nZVI100 cotreatment. Mechanistically, the nanomaterials stimulated JD37 to secrete phenazine-1-carboxylic acid and accelerated the NADH/NAD+ conversion, promoting O2 *– generation; JD37 increased Fe(II) dissolution from the nanomaterials, facilitating *OH generation; and the ROS gradually degraded PCB28 into benzoic acid through dihydroxy substitution, oxidation to quinone, and Michael addition. These findings provide a new strategy of nanoenabled biodegradation of organic pollutants by applying Fe-based nanomaterials and PGPR.

“…Dissolved organic matter (DOM) is a heterogeneous mixture containing complex molecules that are ubiquitous in aquatic environments. , DOM can absorb sunlight and generate photochemically produced reactive intermediates (PPRIs) including excited triplet-state DOM ( 3 DOM*), singlet oxygen ( 1 O 2 ), hydroxyl radical ( • OH), and others. − Notably, 3 DOM* is both the major source of other PPRIs and a strong oxidant itself; thus, it has significant impacts on the transformation of aquatic contaminants, biomolecules, and element cycling. ,− However, unlike other PPRIs that exist as single and distinct species, 3 DOM* is a complex assortment of excited states at various triplet energies and reduction potentials. , Consequently, it is challenging to accurately characterize its properties, − and most available measurement techniques can only provide generalized information. ,, …”

Section: Introductionmentioning

confidence: 99%

Reassessing the Quantum Yield and Reactivity of Triplet-State Dissolved Organic Matter via Global Kinetic Modeling

Du,

Tang,

Yang

et al. 2024

Measuring the quantum yield and reactivity of triplet-state dissolved organic matter ( 3 DOM*) is essential for assessing the impact of DOM on aquatic photochemical processes. However, current 3 DOM* quantification methods require multiple fitting steps and rely on steady-state approximations under stringent application criteria, which may introduce certain inaccuracies in the estimation of DOM photoreactivity parameters. Here, we developed a global kinetic model to simulate the reaction kinetics of the hv/DOM system using four DOM types and 2,4,6trimethylphenol as the probe for 3 DOM*. Analyses of residuals and the root-mean-square error validated the exceptional precision of the new model compared to conventional methods. 3 DOM* in the global kinetic model consistently displayed a lower quantum yield and higher reactivity than those in local regression models, indicating that the generation and reactivity of 3 DOM* have often been overestimated and underestimated, respectively. The global kinetic model derives parameters by simultaneously fitting probe degradation kinetics under different conditions and considers the temporally increasing concentrations of the involved reactive species. It minimizes error propagation and offers insights into the interactions of different species, thereby providing advantages in accuracy, robustness, and interpretability. This study significantly advances the understanding of 3 DOM* behavior and provides a valuable kinetic model for aquatic photochemistry research.