Fluorescent dissolved organic matter components as surrogates for disinfection byproduct formation in drinking water: a critical review

Disinfection byproduct (DBP) formation, prediction, and minimization are critical challenges facing the drinking water treatment industry worldwide where chemical disinfection is required to inactivate pathogenic microorganisms. Fluorescence excitation–emission matrices-parallel factor analysis (EEM-PARAFAC) is used to characterize and quantify fluorescent dissolved organic matter (FDOM) components in aquatic systems and may offer considerable promise as a low-cost optical surrogate for DBP formation in treated drinking waters. However, the global utility of this approach for quantification and prediction of specific DBP classes or species has not been widely explored to date. Hence, this critical review aims to elucidate recurring empirical relationships between common environmental fluorophores (identified by PARAFAC) and DBP concentrations produced during water disinfection. From 45 selected peer-reviewed articles, 218 statistically significant linear relationships (R2 ≥ 0.5) with one or more DBP classes or species were established. Trihalomethanes (THMs) and haloacetic acids (HAAs), as key regulated classes, were extensively investigated and exhibited strong, recurrent relationships with ubiquitous humic/fulvic-like FDOM components, highlighting their potential as surrogates for carbonaceous DBP formation. Conversely, observed relationships between nitrogenous DBP classes, such as haloacetonitriles (HANs), halonitromethanes (HNMs), and N-nitrosamines (NAs), and PARAFAC fluorophores were more ambiguous, but preferential relationships with protein-like components in the case of algal/microbial FDOM sources were noted. This review highlights the challenges of transposing site-specific or FDOM source-specific empirical relationships between PARAFAC component and DBP formation potential to a global model

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Dissipation des pesticides à l'interface eau-sédiment : apports de l'analyse isotopique composé-spécifique

River contamination by pesticides on a global scale impacts biodiversity and the production of drinking water. The water – sediment interface in these environments plays a key role in the dissipation of pesticides, although its functioning remains poorly understood. This thesis targeted degradation processes at this interface by developing Compound-Specific Isotope Analysis (CSIA) for a panel of pesticides, from the laboratory scale to rivers. The results made it possible to identify the specific carbon and nitrogen isotopic enrichment factors for different degradation processes (photolysis, biodegradation) in order to interpret the isotope signatures in rivers. The key role of river runoff on the persistence and degradation of pesticides has been identified. Ways to improve the CSIA are proposed to more systematically assess the persistence of pesticides in rivers.La contamination des rivières par les pesticides à l’échelle de la planète impacte la biodiversité et la production d’eau potable. L’interface eau–sédiment des rivières joue un rôle clé dans la dissipation des pesticides mais son fonctionnement reste méconnu. Cette thèse a ciblé les processus de dégradation à cette interface en développant l’analyse isotopique composé-spécifique (AICS) d’un panel de pesticides, de l’échelle du laboratoire jusqu'aux rivières. Les résultats ont permis d’identifier les facteurs d’enrichissement isotopiques en carbone et azote spécifiques pour différents processus de dégradation (photolyse, biodégradation) pour interpréter des signatures isotopiques en rivière. Le rôle clé des écoulements en rivière sur la persistance et la dégradation des pesticides a été identifié. Des pistes d’amélioration de l’AICS sont proposées pour évaluer plus systématiquement la persistance des pesticides dans les rivières

Characterizing the habitat requirements of the Common Redstart (Phoenicurus phoenicurus) in moderately urbanized areas

The clash of checklists

Phase Transfer and Biodegradation of Pesticides in Water–Sediment Systems Explored by Compound-Specific Isotope Analysis and Conceptual Modeling

International audienc

Direct and indirect photodegradation of atrazine and S-metolachlor in agriculturally impacted surface water and associated C and N isotope fractionation

Knowledge of direct and indirect photodegradation of pesticides and associated isotope fractionation can help to assess pesticide degradation in surface waters. Here, we investigated carbon (C) and nitrogen (N) isotope fractionation during direct and indirect photodegradation of the herbicides atrazine and S-metolachlor in synthetic water, mimicking agriculturally impacted surface waters containing nitrates (20 mg L–1) and dissolved organic matter (DOM, 5.4 mgC L–1). Atrazine and S-metolachlor were quickly photodegraded by both direct and indirect pathways (half-lives <5 and <7 days, respectively). DOM slowed down photodegradation while nitrates increased degradation rates. The analysis of transformation products showed that oxidation mediated by hydroxyl radicals (HO•) predominates during indirect photodegradation. UV light (254 nm) caused significant C and N isotope fractionation, yielding isotope enrichment factors ε_C = 2.7 ± 0.3 and 0.8 ± 0.1‰, and ε_N = 2.4 ± 0.3 and –2.6 ± 0.7‰ for atrazine and S-metolachlor, respectively. In contrast, photodegradation under simulated sunlight led to negligible C and slight N isotope fractionation, indicating the influence of the radiation wavelength on the direct photodegradation-induced isotope fractionation. Altogether, this study highlights the relevance of using simulated sunlight to evaluate photodegradation pathways in the environment and the potential of CSIA to distinghuish photodegradation from other dissipation pathways in surface waters

Reaction of DMS and HOBr as a Sink for Marine DMS and an Inhibitor of Bromoform Formation

Recently, we suggested that hypobromous acid (HOBr) is a sink for the marine volatile organic sulfur compound dimethyl sulfide (DMS). However, HOBr is also known to react with reactive moieties of dissolved organic matter (DOM) such as phenolic compounds to form bromoform (CHBr3) and other brominated compounds. The reaction between HOBr and DMS may thus compete with the reaction between HOBr and DOM. To study this potential competition, kinetic batch and diffusion-reactor experiments with DMS, HOBr, and DOM were performed. Based on the reaction kinetics, we modeled concentrations of DMS, HOBr, and CHBr3 during typical algal bloom fluxes of DMS and HOBr (10-13 to 10-9 M s-1). For an intermediate to high HOBr flux (≥10-11 M s-1) and a DMS flux ≤10-11 M s-1, the model shows that the DMS degradation by HOBr was higher than for photochemical oxidation, biological consumption, and sea-air gas exchange combined. For HOBr fluxes ≤10-11 M s-1 and a DMS flux of 10-11 M s-1, our model shows that CHBr3 decreases by 86% compared to a lower DMS flux of 10-12 M s-1. Therefore, the reaction between HOBr and DMS likely not only presents a sink for DMS but also may lead to suppressed CHBr3 formation.ISSN:0013-936XISSN:1520-585