Photochemical Chain Scissions Enhance Polyethylene Glycol Biodegradability: from Probabilistic Modeling to Experimental Demonstration.

Polyethylene glycols (PEGs), a major class of water-soluble polymers (WSPs), are widely used in diverse applications, from which PEGs may be released into the environment. This work investigates the effect of PEG reaction with photochemically produced hydroxyl radicals (OH), an important environmental oxidant, on the molecular weight (MW) distribution of PEGs and their subsequent biodegradation in soil and sediment. Monte Carlo simulations demonstrated a pronounced decrease in the PEG MW after only a few OH-reaction-induced chain scissions on initial PEG molecules.

Aquatic Thermal and Photochemical Reactivity of -(1,3-Dimethylbutyl)-'-phenyl--phenylenediamine (6PPD), -Isopropyl-'-phenyl--phenylenediamine (IPPD), and 6PPD-quinone.

A ubiquitously used tire rubber antidegradant, 6PPD (-(1,3-dimethylbutyl)-'-phenyl--phenylenediamine), and its toxic ozonation product, 6PPD-quinone (-(1,3-dimethylbutyl)-'-phenyl--phenylenediamine quinone), have become recognized as important environmental pollutants since 6PPD-quinone (6PPD-Q) was identified as the likely cause of decades of mass Coho salmon kills. The reactivity of 6PPD, 6PPD-Q, and similar phenylenediamines requires study to better understand their environmental fate. This study explores the aquatic reactivity of 6PPD, -isopropyl-'-phenyl-1,4-phenylenediamine (IPPD), and 6PPD-Q through thermal and photochemical pathways using both steady-state photochemistry and time-resolved laser spectroscopy techniques.

An Analytical Workflow to Quantify Biodegradable Polyesters in Soils and Its Application to Incubation Experiments.

Soil biodegradable polyesters are designed to undergo to microbial utilization in aerobic soils, forming carbon dioxide and microbial biomass. These polyesters are thus viable substitutes for conventional, persistent polymers (e.g.

Recent Developments on the Three-Dimensional Structure of Dissolved Organic Matter: Toward a Unified Description.

Advancing a common understanding about the chemical composition, size, and three-dimensional (3D) structure of dissolved organic matter (DOM) is paramount to deciphering its impact on and involvement in environmental processes, such as the fate and transport of contaminants and carbon cycling. Traditionally, DOM has been described as a collection of solvent-separated molecules or macromolecules. More recently, DOM has been depicted as a "supramolecular assembly", a collection of individual molecules and associations of molecules held together by non-covalent interactions.

Potential Role of Photochemistry in Environmental DNA Degradation.

Given the severe loss of species richness across diverse ecosystems, there is an urgent need to assess and monitor biodiversity on a global scale. The analysis of environmental DNA (eDNA), referring to any DNA extracted from environmental samples and subsequently sequenced, is a promising method for performing such biodiversity related studies. However, a comprehensive understanding of the factors that drive distinct eDNA degradation rates under different environmental conditions is currently missing, which limits the spatiotemporal interpretations that are possible from the eDNA-based detection of species.

Chloronitramide anion is a decomposition product of inorganic chloramines.

Inorganic chloramines are commonly used drinking water disinfectants intended to safeguard public health and curb regulated disinfection by-product formation. However, inorganic chloramines themselves produce by-products that are poorly characterized. We report chloronitramide anion (Cl-N-NO) as a previously unidentified end product of inorganic chloramine decomposition.

Marine and terrestrial contributions to atmospheric deposition fluxes of methylated arsenic species.

Arsenic, a toxic element from both anthropogenic and natural sources, reaches surface environments through atmospheric cycling and dry and wet deposition. Biomethylation volatilizes arsenic into the atmosphere and deposition cycles it back to the surface, affecting soil-plant systems. Chemical speciation of deposited arsenic is important for understanding further processing in soils and bioavailability.

Polymers from Plant Oils Linked by Siloxane Bonds for Programmed Depolymerization.

The increased production of plastics is leading to the accumulation of plastic waste and depletion of limited fossil fuel resources. In this context, we report a strategy to create polymers that can undergo controlled depolymerization by linking renewable feedstocks with siloxane bonds. α,ω-Diesters and α,ω-diols containing siloxane bonds were synthesized from an alkenoic ester derived from castor oil and then polymerized with varied monomers, including related biobased monomers.

Molecular Structure and Conformation of Biodegradable Water-Soluble Polymers Control Adsorption and Transport in Model Soil Mineral Systems.

Water-soluble polymers (WSPs) are used in diverse applications, including agricultural formulations, that can result in the release of WSPs to soils. WSP biodegradability in soils is desirable to prevent long-term accumulation and potential associated adverse effects. In this work, we assessed adsorption of five candidate biodegradable WSPs with varying chemistry, charge, and polarity characteristics (i.

Global Corrections to Reference Irradiance Spectra for Non-Clear-Sky Conditions.

Photochemical reactions in surface waters play important roles in element cycling and in the removal of organic contaminants, among other processes. A central environmental variable affecting photochemical processes in surface waters is the incoming solar irradiance, as this initiates these processes. However, clear-sky incident irradiance spectra are often used when evaluating the fate of aquatic contaminants, leading to an overestimation of contaminant decay rates due to photochemical transformation.

Biodegradation of poly(butylene succinate) in soil laboratory incubations assessed by stable carbon isotope labelling.

Using biodegradable instead of conventional plastics in agricultural applications promises to help overcome plastic pollution of agricultural soils. However, analytical limitations impede our understanding of plastic biodegradation in soils. Utilizing stable carbon isotope (C-)labelled poly(butylene succinate) (PBS), a synthetic polyester, we herein present an analytical approach to continuously quantify PBS mineralization to CO during soil incubations and, thereafter, to determine non-mineralized PBS-derived C remaining in the soil.

Photochemical Production of Carbon Monoxide from Dissolved Organic Matter: Role of Lignin Methoxyarene Functional Groups.

Carbon monoxide (CO) is the second most abundant identified product of dissolved organic matter (DOM) photodegradation after CO, but its formation mechanism remains unknown. Previous work showed that aqueous photodegradation of methoxy-substituted aromatics (ArOCH) produces CO considerably more efficiently than aromatic carbonyls. Following on this precedent, we propose that the methoxy aromatic groups of lignin act as the C source for the photochemical formation of CO from terrestrial DOM via a two-step pathway: formal hydrolytic demethylation to methanol and methanol oxidation to CO.

The Overlooked Photochemistry of Iodine in Aqueous Suspensions of Fullerene Derivatives.

Fullerene's low water solubility was a serious challenge to researchers aiming to harness their excellent photochemical properties for aqueous applications. Cationic functionalization of the fullerene cage provided the most effective approach to increase water solubility, but common synthesis practices inadvertently complicated the photochemistry of these systems by introducing iodide as a counterion. This problem was overlooked until recent work noted a potentiation effect which occurred when photosensitizers were used to inactivate microorganisms with added potassium iodide.

Factors affecting the mixed-layer concentrations of singlet oxygen in sunlit lakes.

The steady-state concentration of singlet oxygen within a lake ([O]) is an important parameter that can affect the environmental half-life of pollutants and environmental fate modelling. However, values of [O] are often determined for the near-surface of a lake, and these values typically do not represent the average over the epilimnia of lakes. In this work, the environmental and physical factors that have the largest impact on [O] within lake epilimnia were identified.

UV/Vis photochemistry database: Structure, content and applications.

The "science-softCon UV/Vis Photochemistry Database" (www.photochemistry.org) is a large and comprehensive collection of EUV-VUV-UV-Vis-NIR spectral data and other photochemical information assembled from published peer-reviewed papers.

Singlet Oxygen Quantum Yields in Environmental Waters.

Singlet oxygen (O) is a reactive oxygen species produced in sunlit waters via energy transfer from the triplet states of natural sensitizers. There has been an increasing interest in measuring apparent O quantum yields (Φ) of aquatic and atmospheric organic matter samples, driven in part by the fact that this parameter can be used for environmental fate modeling of organic contaminants and to advance our understanding of dissolved organic matter photophysics. However, the lack of reproducibility across research groups and publications remains a challenge that significantly limits the usability of literature data.

Photochemical fate of medetomidine in coastal and marine environments.

Medetomidine has been authorized in ship hull paints as an antifouling biocide under the biocidal product regulation in Europe since 2016. Its release into marine systems causes concerns over persistence and toxicity. However, the environmental fate of medetomidine has not been fully investigated.

Linking Triclosan's Structural Features to Its Environmental Fate and Photoproducts.

Triclosan is a high-production volume chemical, which has become widely detected in environmental systems because of its widespread usage. Photodegradation has been identified as a major degradation pathway, but the identified photoproducts are also chemicals of concern. In this study, lower chlorinated derivatives of triclosan were synthesized to investigate the impact the chlorine substituents have on the photodegradation rate and the photoproducts produced.

Mechanistic Insights into Dissolved Organic Sulfur Photomineralization through the Study of Cysteine Sulfinic Acid.

Photochemical reactions convert dissolved organic matter (DOM) into inorganic and low-molecular-weight organic products, contributing to its cycling across environmental compartments. However, knowledge on the formation mechanisms of these products is still scarce. In this work, we investigate the triplet-sensitized photodegradation of cysteine sulfinic acid, a (photo)degradation product of cysteine, to sulfate (SO).

Substituent Effects on the Direct Photolysis of Benzotrifluoride Derivatives.

The chemical class of benzotrifluoride derivatives is widely used in active ingredients of various commercial products, such as pharmaceuticals, pesticides, herbicides, and crop protection agents. Past studies have shown that some benzotrifluorides are not stable under UV irradiation in water and convert into benzoic acids due to C-F bond hydrolysis. It was also observed, but never systematically studied, that the ring substituents play an important role on the direct photochemical reactivity of the CF moiety.