Assessing the photochemical mineralisation of dissolved organic carbon in lakes.

Photochemical mineralisation is an abiotic process by which the organic matter in natural waters, which is mostly dissolved, is eventually transformed into CO by the action of sunlight. The process has important implications for global C cycling, the penetration of sunlight into the water column, photochemical reactions, and microbial processes. Here we applied an approximated photochemical model to assess the extent of CO photogeneration by mineralisation of dissolved organic matter in lakes located between 60°S and 60°N latitude.

Porous Carbon Fabricated by Microbial Pretreatment of Brewer's Grain for the Improvement of Toluene Adsorption Performance.

Porous activated carbons (AC-AN and AC-AO) for toluene adsorption were prepared starting from brewer's grain biomass pretreated with microorganisms ( van Tieghem for AC-AN and RIB40 for AC-AO). The structures and chemical properties of the three activated carbon materials (AC-AN, AC-AO, and AC that was not pretreated with microorganisms) were characterized by N adsorption-desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The adsorption behavior of the three activated carbons for toluene was studied and correlated with the physical and chemical properties of these materials.

Reaction kinetics and molecular characterization of the compounds formed by photosensitized degradation of the plastic additive bisphenol A in the atmospheric aqueous phase.

Bisphenol A (BPA, 4,4'-(propane-2,2-diyl)diphenol) is a common plasticizer that is very widespread in the environment and is also found at significant concentrations in the global oceans, due to contamination by plastics. Here we show that triplet sensitization is an important degradation pathway for BPA in natural surface waters, which could prevail if the water dissolved organic carbon is above 2-3 mg L. Bromide levels as per seawater conditions have the potential to slow down BPA photodegradation, a phenomenon that could not be offset by reaction of BPA with Br (second-order reaction rate constant of (2.

Two birds with one stone: Degradation of pharmaceuticals and elimination of bacteria upon treatment of urban wastewater with a Fenton-like process, based on zero-valent iron at pH 4.

ZVI-Fenton, which is the combination of zero-valent iron (metallic Fe) and HO is a relatively cheap advanced oxidation process for the elimination of contaminants from wastewater. Here we experimentally tested the ZVI-Fenton reaction at pH 4 towards two crucial goals in the treatment of secondary (partially treated) urban wastewater: (i) degradation of pharmaceuticals such as anti-inflammatory drugs (ibuprofen) and antibiotics (cefazolin, sulfamethoxazole), and (ii) elimination of a considerable fraction of bacteria through a combination of acidic pH and strongly oxidising conditions. In detail, ZVI-Fenton at pH 4 achieved degradation of both primary contaminants and potentially problematic transformation intermediates.

Mineral states and sequestration processes involving soil biogenic components in various soils and desert sands of Inner Mongolia.

Soil biogenic components are subject to continuous sequestration, and export from soils into the surrounding air and water environments. However, the processes involving the stability or lability of their mineral states remain still unclear. To assess these issues, we have measured various biogenic components in a number of agricultural, forest, grassland, and deep soils, as well as desert sands from Inner Mongolia, both in the solid state and liquid extracts.

Facet-induced fractionation of humic acid by hematite and the promoted-photodegradation of 17β-estradiol catalyzed by hematite-humic complex.

Hematite is a ubiquitous mineral with different dominant facets in the environment, which could adsorb humic acids (HA) to form photoactive hematite-HA complex. In this study, we prepared hematite nanocubes (HNC), hematite nanoplates (HNP) and hematite nanorhombs (HNR) with dominant facets as {012}, {001} and {104}, respectively. The abilities of the three hematites to adsorb and fractionate HA were compared.

Predicting p Values of Para-Substituted Aniline Radical Cations vs. Stable Anilinium Ions in Aqueous Media.

The focus of p calculations has primarily been on stable molecules, with limited studies comparing radical cations and stable cations. In this study, we comprehensively investigate models with implicit solvent and explicit water molecules, direct and indirect calculation approaches, as well as methods for calculating free energy, solvation energy, and quasi-harmonic oscillator approximation for para-substituted aniline radical cations (R-PhNH) and anilinium cations (R-PhNH) in the aqueous phase. Properly including and positioning explicit HO molecules in the models is important for reliable p predictions.

Dynamic changes, cycling and downward fate of dissolved carbon and nitrogen photosynthetically-derived from glaciers in upper Indus river basin.

Glaciers play key roles in capturing, storing, and transforming global carbon and nitrogen, thereby contributing markedly to their cycles. However, an integrated mechanistic approach is still lacking regarding glacier's primary producers (PP), in terms of stable dissolved inorganic carbon isotope (δC-DIC) and its relationship with dissolved carbon and nitrogen transformation d ynamic changes/cycling. Here, we sampled waters from glaciers, streams, tributaries, and the Indus River (IR) mainstream in the Upper IR Basin, Western Himalaya.

Photodegradation potential of selected non-steroidal anti-inflammatory drugs in a middle-order Alpine river downstream of a wastewater treatment plant, during a year of enduring water scarcity.

The year 2022 was characterised by significant water shortages and droughts in Italy, with the most pronounced impact observed in the North-Western regions, including Piemonte. In conditions of water scarcity, treated wastewater undergoes little dilution by natural flows and this can deeply affect the chemistry of water-poor rivers and streams. However, increased pollution by wastewater would be partially offset by fast photodegradation of pollutants in shallow water and by the longer time allowed to photochemical reactions if water flows more slowly.

Environmental implications of superoxide radicals: From natural processes to engineering applications.

The roles of superoxide radical (O) in the domains of physiological, physical, and material chemistry are becoming increasingly recognized. Although extensive efforts have been directed to understand O functions in diverse aquatic systems, there is a lack of systematic and in-depth review for its kinetics and mechanisms in various environmental scenarios. This review aims to bridge this gap through discussion of O generation pathways under both natural and controlled conditions.

Pollutant Photodegradation Affected by Evaporative Water Concentration in a Climate Change Scenario.

Evaporative water concentration takes place in arid or semi-arid environments when stationary water bodies, such as lakes or ponds, prevalently lose water by evaporation, which prevails over outflow or seepage into aquifers. Absence or near-absence of precipitation and elevated temperatures are important prerequisites for the process, which has the potential to deeply affect the photochemical attenuation of pollutants, including contaminants of emerging concern (CECs). Here we show that water evaporation would enhance the phototransformation of many CECs, especially those undergoing degradation mainly through direct photolysis and triplet-sensitized reactions.

Direct and indirect photodegradation in aquatic systems mitigates photosensitized toxicity in screening-level substance risk assessments of selected petrochemical structures.

Photochemical processes are typically not incorporated in screening-level substance risk assessments due to the complexity of modeling sunlight co-exposures and resulting interactions on environmental fate and effects. However, for many substances, sunlight exerts a profound influence on environmental degradation rates and ecotoxicities. Recent modeling advances provide an improved technical basis for estimating the effect of sunlight in modulating both substance exposure and toxicity in the aquatic environment.

Efficient regulation of cadmium accumulation by carboxymethylammonium chloride in rice: Correlation analysis and expression of transporter gene OsGLR3.

The mechanism of carboxymethylammonium chloride (CC) regulating cadmium (Cd) accumulation in rice was studied in field and hydroponic experiments. Field experiments showed that 0.2-1.

Infancy of peracetic acid activation by iron, a new Fenton-based process: A review.

The exacerbated global water scarcity and stricter water directives are leading to an increment in the recycled water use, requiring the development of new cost-effective advanced water treatments to provide safe water to the population. In this sense, peracetic acid (PAA, CHC(O)OOH) is an environmentally friendly disinfectant with the potential to challenge the dominance of chlorine in large wastewater treatment plants in the near future. PAA can be used as an alternative oxidant to HO to carry out the Fenton reaction, and it has recently been proven as more effective than HO towards emerging pollutants degradation at circumneutral pH values and in the presence of anions.

Solar light photodegradation of nicotine in the presence of aged polystyrene microplastics.

Limited information exists on the potential of aged microplastics to induce photodegradation of organic pollutants under sunlight irradiation. In this work, nicotine (NIC), a widespread emerging contaminant, was used as a model organic substrate to investigate this innovative degradation process. Polystyrene (PS) pellets were artificially aged and became rich in oxygenated moieties with their carbonyl index reaching 0.

Chemical characterization and speciation of the soluble fraction of Arctic PM.

The chemical composition of the soluble fraction of atmospheric particulate matter (PM) and how these components can combine with each other to form different species affect the chemistry of the aqueous phase dispersed in the atmosphere: raindrops, clouds, fog, and ice particles. The study was focused on the analysis of the soluble fraction of Arctic PM samples collected at Ny-Ålesund (Svalbard Islands, Norwegian Arctic) during the year 2012. The concentration values of Na, K, NH, Ca, Mg, Mn, Cu, Zn, Fe, Al, Cl, NO, NO, SO, PO, formate, acetate, malonate, and oxalate in the water-soluble fraction of PM were determined by atomic spectroscopy and ion chromatography.

Possible Effects of Changes in Carbonate Concentration and River Flow Rate on Photochemical Reactions in Temperate Aquatic Environments.

In temperate environments, climate change could affect water pH by inducing enhanced dissolution of CaSO followed by biological sulphate reduction, with the potential to basify water due to H consumption. At the same time, increased atmospheric CO could enhance weathering of carbonate rocks (e.g.

Overlooked Transformation of Nitrated Polycyclic Aromatic Hydrocarbons in Natural Waters: Role of Self-Photosensitization.

Photochemical transformation is an important process that involves trace organic contaminants (TrOCs) in sunlit surface waters. However, the environmental implications of their self-photosensitization pathway have been largely overlooked. Here, we selected 1-nitronaphthalene (1NN), a representative nitrated polycyclic aromatic hydrocarbon, to study the self-photosensitization process.

Global modeling of lake-water indirect photochemistry based on the equivalent monochromatic wavelength approximation: The case of the triplet states of chromophoric dissolved organic matter.

Chromophoric dissolved organic matter (CDOM) plays key role as photosensitizer in sunlit surface-water environments, and it is deeply involved in the photodegradation of contaminants. It has recently been shown that sunlight absorption by CDOM can be conveniently approximated based on its monochromatic absorption at 560 nm. Here we show that such an approximation allows for the assessment of CDOM photoreactions on a wide global scale and, particularly, in the latitude belt between 60°S and 60°N.

Photochemical Implications of Changes in the Spectral Properties of Chromophoric Dissolved Organic Matter: A Model Assessment for Surface Waters.

Chromophoric dissolved organic matter (CDOM) is the main sunlight absorber in surface waters and a very important photosensitiser towards the generation of photochemically produced reactive intermediates (PPRIs), which take part in pollutant degradation. The absorption spectrum of CDOM ((λ), unitless) can be described by an exponential function that decays with increasing wavelength: (λ) = 100 DOC e, where [m] is water depth, DOC [mg L] is dissolved organic carbon, [L mg cm] is a pre-exponential factor, and [nm] is the spectral slope. Sunlight absorption by CDOM is higher when and DOC are higher and is lower, and vice versa.

Assessing the photodegradation potential of compounds derived from the photoinduced weathering of polystyrene in water.

Benzoate (Bz) and acetophenone (AcPh) are aromatic compounds known to be produced by sunlight irradiation of polystyrene aqueous suspensions. Here we show that these molecules could react with OH (Bz) and OH + CO (AcPh) in sunlit natural waters, while other photochemical processes (direct photolysis and reaction with singlet oxygen, or with the excited triplet states of chromophoric dissolved organic matter) are unlikely to be important. Steady-state irradiation experiments were carried out using lamps, and the time evolution of the two substrates was monitored by liquid chromatography.

Feasibility of a Heterogeneous Nanoscale Zero-Valent Iron Fenton-like Process for the Removal of Glyphosate from Water.

Glyphosate is a widely used herbicide, and it is an important environmental pollutant that can have adverse effects on human health. Therefore, remediation and reclamation of contaminated streams and aqueous environments polluted by glyphosate is currently a worldwide priority. Here, we show that the heterogeneous nZVI-Fenton process (nZVI + HO; nZVI: nanoscale zero-valent iron) can achieve the effective removal of glyphosate under different operational conditions.

Photoinduced production of substances with humic-like fluorescence, upon irradiation of water samples from alpine lakes.

Evidence is here provided that irradiation of some lake water samples can trigger the formation of fluorophores with humic-like properties, at the same time increasing water absorbance. This phenomenon is the opposite of photobleaching, which is often observed when natural waters are irradiated. The photoproduced humic-like fluorophores observed here would be of autochthonous rather than allochthonous origin, which marks a difference with the fraction of humic substances that derives from terrestrial sources.