198 results on '"Kristopher McNeill"'
Search Results
2. UVB-irradiated Laboratory-generated Secondary Organic Aerosol Extracts Have Increased Cloud Condensation Nuclei Abilities: Comparison with Dissolved Organic Matter and Implications for the Photomineralization Mechanism
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Nadine Borders-Dedekind, Sergey Nizkorodov, and Kristopher McNeill
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cloud condensation nuclei ,dissolved organic matter ,photochemistry ,photomineralization ,Chemistry ,QD1-999 - Abstract
During their atmospheric lifetime, organic compounds within aerosols are exposed to sunlight and undergo photochemical processing. This atmospheric aging process changes the ability of organic aerosols to form cloud droplets and consequently impacts aerosol–cloud interactions. We recently reported changes in the cloud forming properties of aerosolized dissolved organic matter (DOM) due to a photomineralization mechanism, transforming high-molecular weight compounds in DOM into organic acids, CO and CO2. To strengthen the implications of this mechanism to atmospheric aerosols, we now extend our previous dataset and report identical cloud activation experiments with laboratory-generated secondary organic aerosol (SOA) extracts. The SOA was produced from the oxidation of α-pinene and naphthalene, a representative biogenic and anthropogenic source of SOA, respectively. Exposure of aqueous solutions of SOA to UVB irradiation increased the dried organic material's hygroscopicity and thus its ability to form cloud droplets, consistent with our previous observations for DOM. We propose that a photomineralization mechanism is also at play in these SOA extracts. These results help to bridge the gap between DOM and SOA photochemistry by submitting two differently-sourced organic matter materials to identical experimental conditions for optimal comparison.
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- 2020
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3. Magnitude and Mechanism of Siderophore-Mediated Competition at Low Iron Solubility in the Pseudomonas aeruginosa Pyochelin System
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Konstanze T. Schiessl, Elisabeth M.-L. Janssen, Stephan M. Kraemer, Kristopher McNeill, and Martin Ackermann
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siderophore ,competition ,iron uptake ,microbial interactions ,pyochelin ,Pseudomonas aeruginosa ,Microbiology ,QR1-502 - Abstract
A central question in microbial ecology is whether microbial interactions are predominantly cooperative or competitive. The secretion of siderophores, microbial iron chelators, is a model system for cooperative interactions. However, siderophores have also been shown to mediate competition by sequestering available iron and making it unavailable to competitors. The details of how siderophores mediate competition are not well understood, especially considering the complex distribution of iron phases in the environment. One pertinent question is whether sequestering iron through siderophores can indeed be effective in natural conditions; many natural environments are characterized by large pools of precipitated iron, and it is conceivable that any soluble iron that is sequestered by siderophores is replenished by the dissolution of these precipitated iron sources. Our goal here was to address this issue, and investigate the magnitude and mechanism of siderophore-mediated competition in the presence of precipitated iron. We combined experimental work with thermodynamic modeling, using Pseudomonas aeruginosa as a model system and ferrihydrite precipitates as the iron source with low solubility. Our experiments show that competitive growth inhibition by the siderophore pyochelin is indeed efficient, and that inhibition of a competitor can even have a stronger growth-promoting effect than solubilization of precipitated iron. Based on the results of our thermodynamic models we conclude that the observed inhibition of a competitor is effective because sequestered iron is only very slowly replenished by the dissolution of precipitated iron. Our research highlights the importance of competitive benefits mediated by siderophores, and underlines that the dynamics of siderophore production and uptake in environmental communities could be a signature of competitive, not just cooperative, dynamics.
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- 2017
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4. Quantification of Hydroxylated Polybrominated Diphenyl Ethers (OH-BDEs), Triclosan, and Related Compounds in Freshwater and Coastal Systems.
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Jill F Kerrigan, Daniel R Engstrom, Donald Yee, Charles Sueper, Paul R Erickson, Matthew Grandbois, Kristopher McNeill, and William A Arnold
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Medicine ,Science - Abstract
Hydroxylated polybrominated diphenyl ethers (OH-BDEs) are a new class of contaminants of emerging concern, but the relative roles of natural and anthropogenic sources remain uncertain. Polybrominated diphenyl ethers (PBDEs) are used as brominated flame retardants, and they are a potential source of OH-BDEs via oxidative transformations. OH-BDEs are also natural products in marine systems. In this study, OH-BDEs were measured in water and sediment of freshwater and coastal systems along with the anthropogenic wastewater-marker compound triclosan and its photoproduct dioxin, 2,8-dichlorodibenzo-p-dioxin. The 6-OH-BDE 47 congener and its brominated dioxin (1,3,7-tribromodibenzo-p-dioxin) photoproduct were the only OH-BDE and brominated dioxin detected in surface sediments from San Francisco Bay, the anthropogenically impacted coastal site, where levels increased along a north-south gradient. Triclosan, 6-OH-BDE 47, 6-OH-BDE 90, 6-OH-BDE 99, and (only once) 6'-OH-BDE 100 were detected in two sediment cores from San Francisco Bay. The occurrence of 6-OH-BDE 47 and 1,3,7-tribromodibenzo-p-dioxin sediments in Point Reyes National Seashore, a marine system with limited anthropogenic impact, was generally lower than in San Francisco Bay surface sediments. OH-BDEs were not detected in freshwater lakes. The spatial and temporal trends of triclosan, 2,8-dichlorodibenzo-p-dioxin, OH-BDEs, and brominated dioxins observed in this study suggest that the dominant source of OH-BDEs in these systems is likely natural production, but their occurrence may be enhanced in San Francisco Bay by anthropogenic activities.
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- 2015
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5. Environmental Photochemistry of Amino Acids, Peptides and Proteins
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Rachel A. Lundeen, Elisabeth M.-L. Janssen, Chiheng Chu, and Kristopher Mcneill
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Amino acids ,Environmental fate ,Natural organic matter ,Photochemistry ,Proteins ,Chemistry ,QD1-999 - Abstract
Amino acids, peptides and proteins are central building blocks of life and of key importance in the biogeochemistry of aquatic ecosystems. In sunlit surface waters, amino acid-based molecules at different levels of structural organization are susceptible to transformation by both direct photochemical reactions and indirect processes caused by photochemically produced reactive oxygen species (e.g. hydroxyl radical or singlet oxygen). Photochemical transformation processes can thereby affect the availability of these crucial nutrient sources in aquatic ecosystems, inhibit the function of microbial extracellular enzymes, or even promote the degradation of amino acid-based pollutant molecules. In this article, the environmental photochemistry of amino acids, peptides and proteins in aquatic systems is reviewed.
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- 2014
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6. Getting the SMILES right: identifying inconsistent chemical identities in the ECHA database, PubChem and the CompTox Chemicals Dashboard
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Juliane Glüge, Kristopher McNeill, and Martin Scheringer
- Abstract
Chemical databases containing information on substances and their identities are important and useful tools, used in many areas of chemistry and cheminformatics. Errors or inconsistencies in the identities of substances in the databases are a major problem, as they can make QSAR predictions inaccurate, make chemical hazard and risk assessments erroneous, and cause problems for the ordering of chemicals and analytical standards. In the present study, we checked the entries of all mono-constituent organic substances registered under REACH (more than 8500 substances) in the database of the European Chemicals Agency (ECHA), PubChem and the CompTox Chemicals Dashboard and flagged compounds with inconsistent chemical identifiers. In total 736 inconsistent entries, and 48 additional entries where the substance identity was not clear, were identified. This shows that data curation activities are still not sufficient in the databases and that more work needs to be done. Additionally, the identified inconsistent entries were analyzed to understand what kind of mismatches have been introduced in the databases and to avoid these mismatches in the future. Data gathering and processing is described in detail in the current study so that further studies can continue with this work for additional substances and databases. In this way, the study makes an important contribution towards improved and more trustworthy databases., Environmental Science: Advances, 2 (4), ISSN:2754-7000
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- 2023
7. Temperature impacts polymer biodegradation rates in soils in predictable ways but with dependencies that differ between soils
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Juliana Laszakovits, Ralf Kägi, Flora Willie, Michael Sander, and Kristopher McNeill
- Abstract
Biodegradable polymers can play an important role in helping to overcome the plastic pollution problem by replacing conventional, persistent polymers in specific applications. These include applications in which plastics are used directly in the environment and cannot be completely recollected (e.g., mulch films and seed coatings) and for bags used to collect biowaste for industrial composting. Temperature is an important system factor that determines the rate at which biodegradable polymers biodegrade in both natural and engineered environments. Yet, there is a limited quantitative understanding of how temperature impacts polymer biodegradation rates in the open environment, specifically in soils. Temperature not only affects the activity of soil microorganisms but also their extracellular enzymes that hydrolyze backbone bonds in biodegradable polymers. Here, we assessed the impact of temperature on the biodegradation of poly-3-hydroxybutyratehydroxyhexanoate (PHBH) in agricultural soils. We incubated PHBH in three different standards soils and at four temperatures (5, 15, 25 and 35 ºC). We determined the amount of residual PHBH in soil over time by extracting PHBH from the soil using a chloroform-methanol mixture and then quantifying the extracted polymer using proton nuclear magnetic resonance spectroscopy (1H NMR). We find that the rate of PHBH biodegradation increased with increasing temperatures in all three soils, but that the rates and temperature dependence of the rates variedbetween soils. The fastest biodegradation occurred in LUFA 6S (clay) followed by LUFA 2.4 (loam), and the slowest biodegradation was in LUFA 2.2 (sandy loam). The soil-dependence likely reflects differences in the abundance and activity of microbial degraders in these soils. At lower incubation temperatures, there was a noticeable lag-phase prior to the onset of biodegradation, which was most pronounced in soil LUFA 2.2 . When the lag-phase is included in the kinetic modeling, the temperature-dependence of the PHBH biodegradation rate can be described reasonably well by the Arrhenius rate law but differs between soils. We further investigated the microbial colonization dynamics of PHBH film surfaces during the lag-phase using optical and scanning electron microscopy. After incubation of solvent-cast PHBH films in the soil at the aforementioned temperatures, microscopic analyses revealed that fungal hyphae were involved in both colonization and initial breakdown of the PHBH films, and that fungal activity increased with increasing temperature. Taken together, these results suggest that a careful determination of the temperature dependence of polymer biodegradation in different soils is needed to predict, from standard tests run at elevated and constant temperature, how quickly biodegradable polymers will biodegrade in the open environment where temperatures are lower and variable.
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- 2023
8. Biodegradation of commercial mulch films in Swiss agricultural soils: Results from combined laboratory, mesocosm and field incubations
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Silvan Arn, Flora Wille, Mattia Cerri, Ralf Kägi, Thomas Bucheli, Franco Widmer, Kristopher McNeill, and Michael Sander
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Non-biodegradable polyethylene mulch films are widely used in agriculture to allow for an extended growing season and to increase crop yields. These mulch films are, however, difficult to completely recollect from the field after use, particularly when they are thin (< 25 µm). Residual mulch film pieces can accumulate in soils over time, thereby negatively impacting soil productivity and possibly turning agricultural soils into sources of plastics to surrounding environments. Mulch films certified as biodegradable in soils promise to be a solution to these problems. While such mulch films are already commercially available, a thorough assessment of the biodegradation dynamics of biodegradable mulch film products in soils in the field is lacking. So far, certification relies exclusively on laboratory soil incubations coupled to respirometric analysis of CO2 formed from the mulch films during biodegradation. Respirometric analyses are, however, very challenging to implement in field incubation studies. Past studies determining concentrations of biodegradable mulch films in field soils and attempts to follow their biodegradation dynamics in the field have relied on approximate quantification approaches, such as determining the decrease in surface area or gravimetric mass of film pieces recollected by hand. To advance a more robust and quantitative analytical approach for residual mulch film quantification in soils, we present a methodology to solvent extract and quantify the main synthetic polymeric components of commercial biodegradable mulch films, poly(butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA), from soil. The methodology is based on exhaustive Soxhlet extraction using chloroform/methanol coupled to quantitative 1H-NMR of the extracted residual PBAT and PLA. We show full recovery of these polymers added to soils in spike-recovery experiments. Here, we use this approach to assess the biodegradation of two commercial biodegradable mulch films in three Swiss agricultural soils in a multiyear incubation study. These incubations are conducted at three experimental incubation scales: flasks in the laboratory, mesocosms in a greenhouse and the actual field. We statistically compare biodegradation rates and extents between three soils, two tested films across the three incubation scales, as well as differences in the relative rates of biodegradation between PBAT and PLA. Thereby, we assess the transferability of biodegradation results from laboratory incubations to field incubations. Our results highlight variations in biodegradation between soils and polyesters and indicate that laboratory soil incubations show faster biodegradation than measured in the same soil in the field.
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- 2023
9. Site-Specific Mineralization of a Polyester Hydrolysis Product in Natural Soil
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Derek C. Batiste, Guilhem X. De Hoe, Taylor F. Nelson, Katharina Sodnikar, Kristopher McNeill, Michael Sander, and Marc A. Hillmyer
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Renewable Energy, Sustainability and the Environment ,General Chemical Engineering ,Environmental Chemistry ,General Chemistry - Published
- 2022
10. Introduction to indoor air quality
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Neil M. Donahue, Kristopher McNeill, Daniel S. Korbel, and Hannah G. Macdonald
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Chemistry (miscellaneous) ,Environmental Chemistry ,Pollution ,Analytical Chemistry - Abstract
Environmental Science: Atmospheres, 3 (4), ISSN:2634-3606
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- 2023
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11. Global Corrections to Reference Irradiance Spectra for Non-Clear-Sky Conditions
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Sarah B. Partanen and Kristopher McNeill
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incident irradiance ,correction factors ,satellite data ,photochemical processes ,non-clear-sky conditions ,reference spectra ,Environmental Chemistry ,General Chemistry - Abstract
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. In this work, incident irradiance satellite data were used to develop global-scale non-clear-sky correction factors for commonly used reference irradiance spectra. Non-clear-sky conditions can decrease incident irradiance by over 90% depending on the geographic location and time of the year, with latitudes above 40°N being most heavily affected by seasons. The impact of non-clear-sky conditions on contaminant half-lives was illustrated in a case study of triclosan in lake Greifensee, which showed a 39% increase in the triclosan half-life over the course of a year under non-clear-sky conditions. A global annual average correction factor of 0.76 was determined as an approximate way to account for non-clear-sky conditions. The correction factors are developed at monthly and seasonal resolutions for every location on the globe between 70°N and 60°S at a 4 km spatial resolution and can be used by researchers, practitioners, and regulators who need improved estimates of incident irradiance., Environmental Science & Technology, 57 (6), ISSN:0013-936X, ISSN:1520-5851
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- 2023
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12. Photochemical Production of Carbon Monoxide from Dissolved Organic Matter: Role of Lignin Methoxyarene Functional Groups
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Rachele Ossola, Richard Gruseck, Joanna Houska, Alessandro Manfrin, Morgan Vallieres, and Kristopher McNeill
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allyl alcohol ,dissolved organic matter photodegradation ,lignin ,mechanism ,carbon cycling ,Dissolved Organic Matter ,carbon monoxide ,quantum yield spectra ,Formaldehyde ,Environmental Chemistry ,methanol ,Photolysis ,model ,hydroxyl radicals ,hydrogen-peroxide ,aqueous-solutions ,General Chemistry ,Carbon Dioxide ,Oxidants ,Photochemical Processes ,rate constants ,center-dot ,methoxy-substituted aromatics ,reaction mechanism ,photoproduction - Abstract
Carbon monoxide (CO) is the second most abundant identified product of dissolved organic matter (DOM) photodegradation after CO2, but its formation mechanism remains unknown. Previous work showed that aqueous photodegradation of methoxy-substituted aromatics (ArOCH3) 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. To test the reasonableness of this mechanism, we investigated the photochemistry of eight lignin model compounds. We first observed that initial CO production rates are positively correlated with initial substrate degradation rates only for models containing at least one ArOCH3 group, regardless of other structural features. We then confirmed that all ArOCH3-containing substrates undergo formal hydrolytic demethylation by detecting methanol and the corresponding phenolic transformation products. Finally, we showed that hydroxyl radicals, likely oxidants to initiate methanol oxidation to CO, form during irradiation of all models. This work proposes an explicit mechanism linking ubiquitous, abundant, and easily quantifiable DOM functionalities to CO photoproduction. Our results further hint that methanol may be an abundant (yet overlooked) DOM photoproduct and a likely precursor of formaldehyde, formic acid, and CO2 and that lignin photodegradation may represent a source of hydroxyl radicals., Environmental Science & Technology, 56 (18), ISSN:0013-936X, ISSN:1520-5851
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- 2022
13. Factors affecting the mixed-layer concentrations of singlet oxygen in sunlit lakes†
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Sarah B. Partanen, Jennifer N. Apell, Jianming Lin, and Kristopher McNeill
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Pollutant ,010504 meteorology & atmospheric sciences ,Singlet Oxygen ,Mixed layer ,Singlet oxygen ,Public Health, Environmental and Occupational Health ,Quantum yield ,General Medicine ,010501 environmental sciences ,Management, Monitoring, Policy and Law ,Atmospheric sciences ,01 natural sciences ,6. Clean water ,Latitude ,Oxygen ,chemistry.chemical_compound ,Chemistry ,Lakes ,chemistry ,13. Climate action ,Epilimnion ,Environmental Chemistry ,Environmental science ,Seasons ,0105 earth and related environmental sciences - Abstract
The steady-state concentration of singlet oxygen within a lake ([1O2]SS) is an important parameter that can affect the environmental half-life of pollutants and environmental fate modelling. However, values of [1O2]SS 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 [1O2]SS within lake epilimnia were identified. It was found that the depth of the epilimnion has the largest impact on depth-averaged [1O2]SS, with a factor of 8.8 decrease in [1O2]SS when epilimnion depth increases from 2 m to 20 m. The next most important factors are the wavelength-dependent singlet oxygen quantum yield relationship and the latitude of the lake, causing variations in [1O2]SS by factors of 3.2 and 2.5 respectively, over ranges of representative values. For a set of representative parameters, the depth-averaged value of [1O2]SS within an average epilimnion depth of 9.0 m was found to be 5.8 × 10−16 M and the near-surface value of [1O2]SS was found to be 1.9 × 10−14 M. We recommend a range of 6 × 10−17 to 5 × 10−15 M as being more representative of [1O2]SS values within the epilimnia of lakes globally and potentially more useful for estimating pollutant lifetimes than those calculated using [1O2]SS values that correspond to near-surface, summer midday values. This work advances our understanding of [1O2]SS inter-lake variability in the environment, and provides estimates of [1O2]SS for practitioners and researchers to assess environmental half-lives of pollutants due to reaction with singlet oxygen., [1O2]SS within lake epilimnia are highly affected by epilimnion depth and are barely affected by DOC concentration within the lake.
- Published
- 2021
14. Best Papers from 2021 published in the Environmental Science journals of the Royal Society of Chemistry
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Paige J. Novak, Neil M. Donahue, Kristopher McNeill, and Peter J. Vikesland
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Environmental Engineering ,Chemistry (miscellaneous) ,Materials Science (miscellaneous) ,Public Health, Environmental and Occupational Health ,Environmental Chemistry ,General Medicine ,Management, Monitoring, Policy and Law ,Pollution ,Analytical Chemistry ,General Environmental Science ,Water Science and Technology - Abstract
Environmental Science: Atmospheres, 2 (4), ISSN:2634-3606
- Published
- 2022
15. Ten years of Environmental Science: Processes & Impacts
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Kristopher McNeill
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Public Health, Environmental and Occupational Health ,Environmental Chemistry ,General Medicine ,Management, Monitoring, Policy and Law - Abstract
Editor-in-Chief Kristopher McNeill reflects on 10 years of Environmental Science: Processes & Impacts.
- Published
- 2023
16. The Overlooked Photochemistry of Iodine in Aqueous Suspensions of Fullerene Derivatives
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Madhusudan Kamat, Kyle Moor, Gabrielle Langlois, Moshan Chen, Kimberly M. Parker, Kristopher McNeill, and Samuel D. Snow
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photochemistry ,Photosensitizing Agents ,Singlet Oxygen ,photosensitizer ,General Engineering ,Iodine ,singlet oxygen ,MS2 bacteriophage ,cationic fullerene ,C60 ,General Physics and Astronomy ,Water ,Iodides ,Suspensions ,General Materials Science ,Fullerenes - Abstract
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. In this work, several photochemical pathways were explored to determine the extent and underlying mechanisms of iodide’s interference in the photosensitization of singlet oxygen by cationic fulleropyrrolidinium ions and rose bengal. Triplet excited state sensitizer lifetimes were measured via laser flash photolysis to probe the role of I– in triplet sensitizer quenching. Singlet oxygen production rates were compared across sensitizers in the presence or absence of I–, SO42–, and other anions. 3,5-Dimethyl-1H-pyrazole was employed as a chemical probe for iodine radical species, such as I·, but none were observed in the photochemical systems. Molecular iodine and triiodide, however, were found in significant quantities when photosensitizers were irradiated in the presence of I– and O2. The formation of I2 in these photochemical systems calls into question the interpretations of prior studies that used I– as a counterion for photosensitizer materials. As an example, MS2 bacteriophages were inactivated here by cationic fullerenes with and without I– present, showing that I– moderately accelerated the MS2 deactivation, likely by producing I2. Production of I2 did not appear to be directly correlated with estimates of 1O2 concentration, suggesting that the relevant photochemical pathways are more complex than direct reactions between 1O2 and I– in the bulk solution. On the basis of the results here, iodine photochemistry may be underappreciated and misunderstood in other environmental systems., ACS Nano, 16 (5), ISSN:1936-0851, ISSN:1936-086X
- Published
- 2022
17. Quantification of Synthetic Polyesters from Biodegradable Mulch Films in Soils
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Kristopher McNeill, Stephanie Christa Remke, Hans-Peter E. Kohler, Taylor F. Nelson, and Michael Sander
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Chloroform ,Polyesters ,Extraction (chemistry) ,Temperature ,Agriculture ,Deuterated chloroform ,General Chemistry ,010501 environmental sciences ,Biodegradation ,01 natural sciences ,Polyester ,Soil ,chemistry.chemical_compound ,Biodegradation, Environmental ,chemistry ,Polylactic acid ,Soil water ,Environmental Chemistry ,Methanol ,0105 earth and related environmental sciences ,Nuclear chemistry - Abstract
Soil biodegradable mulch films composed of the polyester polybutylene adipate-co-terephthalate (PBAT) are being increasingly used in agriculture. Analytical methods to quantify PBAT in field soils are needed to assess its soil occurrence and fate. Here, we report an analytical method for PBAT in soils that couples Soxhlet extraction or accelerated solvent extraction (ASE) with quantitative protonnuclear magnetic resonance (q-1H NMR) spectroscopy detection. The 1H NMR peak areas of aromatic PBAT protons increased linearly with PBAT concentrations dissolved in deuterated chloroform (CDCl3), demonstrating accurate quantitation of PBAT by q-1H NMR. Spike-recovery experiments involving PBAT addition to model sorbents and soils showed increased PBAT extraction efficiencies into chloroform (CHCl3) with methanol (MeOH) as cosolvent, consistent with MeOH competitively displacing PBAT from H-bond donating sites on mineral surfaces. Systematic variations in solvent composition and temperatures in ASE revealed quantitative PBAT extraction from soil with 90/10 volume % CHCl3/MeOH at 110-120 °C. Both Soxhlet extraction and ASE resulted in the complete recovery of PBAT added to a total of seven agricultural soils covering a range of physicochemical properties, independent of whether PBAT was added to soils dissolved in CHCl3, as film, or as particles. Recovery was also complete for PBAT added to soil in the form of a commercial soil biodegradable mulch film with coextractable polylactic acid (PLA). The presented analytical method enables accurate quantification and biodegradation monitoring of PBAT in agricultural field soils.
- Published
- 2019
18. Best papers from 2020 published in the
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Paige J, Novak, Kristopher, McNeill, and Peter J, Vikesland
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Publishing ,Environmental Science ,Periodicals as Topic - Published
- 2021
19. Biodegradation of poly(butylene succinate) in soil laboratory incubations assessed by stable carbon isotope labelling
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Taylor F, Nelson, Rebekka, Baumgartner, Madalina, Jaggi, Stefano M, Bernasconi, Glauco, Battagliarin, Carsten, Sinkel, Andreas, Künkel, Hans-Peter E, Kohler, Kristopher, McNeill, and Michael, Sander
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Carbon Isotopes ,Soil ,Biodegradation, Environmental ,Polymers ,Isotope Labeling ,Polyesters ,Succinates ,Carbon Dioxide ,Butylene Glycols ,Plastics ,Carbon - Abstract
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 (
- Published
- 2021
20. Best Papers from 2020 published in the Environmental Science journals of the Royal Society of Chemistry
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Kristopher McNeill, Peter J. Vikesland, and Paige J. Novak
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Environmental Engineering ,Materials Science (miscellaneous) ,Public Health, Environmental and Occupational Health ,Environmental Chemistry ,Environmental science ,Library science ,General Medicine ,Chemistry (relationship) ,Management, Monitoring, Policy and Law ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,General Environmental Science ,Water Science and Technology - Abstract
The Editors-in-Chief of the Environmental Science journals introduce the Best Papers of 2020.
- Published
- 2021
21. 2019 Best Papers published in the Environmental Science journals of the Royal Society of Chemistry
- Author
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Peter J. Vikesland, Kristopher McNeill, and Paige J. Novak
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Publishing ,Environmental Engineering ,Materials Science (miscellaneous) ,0208 environmental biotechnology ,Public Health, Environmental and Occupational Health ,MEDLINE ,Library science ,02 engineering and technology ,General Medicine ,010501 environmental sciences ,Management, Monitoring, Policy and Law ,01 natural sciences ,020801 environmental engineering ,Environmental Science ,Environmental Chemistry ,Environmental science ,Chemistry (relationship) ,Periodicals as Topic ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,Water Science and Technology ,General Environmental Science ,0105 earth and related environmental sciences - Abstract
The Editors-in-Chief of the Environmental Science journals introduce the Best Papers of 2019.
- Published
- 2020
22. Photochemical Production of Sulfate and Methanesulfonic Acid from Dissolved Organic Sulfur
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Paul R. Erickson, Julie Tolu, Kristopher McNeill, Baptiste Clerc, Lenny H. E. Winkel, and Rachele Ossola
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Mesylates ,Biogeochemical cycle ,Sulfates ,Sulfur Oxides ,chemistry.chemical_element ,General Chemistry ,010501 environmental sciences ,Photochemical Processes ,Photochemistry ,Mass spectrometry ,01 natural sciences ,Methanesulfonic acid ,Sulfur ,chemistry.chemical_compound ,chemistry ,Dissolved organic carbon ,Environmental Chemistry ,Degradation (geology) ,Sulfate ,Photodegradation ,0105 earth and related environmental sciences - Abstract
Photodegradation processes play an important role in releasing elements tied up in biologically refractory forms in the environment, and are increasingly being recognized as important contributors to biogeochemical cycles. While complete photo-oxidation of dissolved organic carbon (to CO2) and dissolved organic phosphorous (to PO43-) has been documented, the analogous photoproduction of sulfate from dissolved organic sulfur (DOS) has not yet been reported. Recent high-resolution mass spectrometry studies showed a selective loss of organic sulfur during photodegradation of dissolved organic matter, which was hypothesized to result in the production of sulfate. Here, we provide evidence of ubiquitous production of sulfate, methanesulfonic acid (MSA), and methanesulfinic acid (MSIA) during photodegradation of DOM samples from a wide range of natural terrestrial environments. We show that photochemical production of sulfate is generally more efficient than the production of MSA and MSIA, as well as volatile S-containing compounds such as CS2 and COS. We also identify possible molecular precursors for sulfate and MSA, and we demonstrate that a wide range of relevant classes of DOS compounds (in terms of S oxidation state and molecular structure) can liberate sulfate upon photosensitized degradation. This work suggests that photochemistry may play a more significant role in the aquatic and atmospheric fate of DOS than currently believed.
- Published
- 2019
23. Intramolecular [2 + 2] Photocycloaddition of Altrenogest: Confirmation of Product Structure, Theoretical Mechanistic Insight, and Bioactivity Assessment
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Kristine H. Wammer, Kristopher McNeill, David M. Cwiertny, Edward P. Kolodziej, Dalma Martinović-Weigelt, James B. Gloer, Nicholas C. Pflug, and Eric V. Patterson
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Pregnane X receptor ,Altrenogest ,Cycloaddition Reaction ,010405 organic chemistry ,Chemistry ,Stereochemistry ,medicine.medical_treatment ,Organic Chemistry ,Photodissociation ,Absolute configuration ,Receptors, Cytoplasmic and Nuclear ,Photochemical Processes ,010402 general chemistry ,Ring (chemistry) ,01 natural sciences ,0104 chemical sciences ,Steroid ,Photoexcitation ,chemistry.chemical_compound ,Intramolecular force ,medicine ,Humans ,Trenbolone Acetate ,Density Functional Theory - Abstract
While studying the environmental fate of potent endocrine-active steroid hormones, we observed the formation of an intramolecular [2 + 2] photocycloaddition product (2) with a novel hexacyclic ring system following the photolysis of altrenogest (1). The structure and absolute configuration were established by X-ray diffraction analysis. Theoretical computations identified a barrierless two-step cyclization mechanism for the formation of 2 upon photoexcitation. 2 exhibited progesterone, estrogen, androgen, and pregnane X receptor activity, albeit generally with reduced potency relative to 1.
- Published
- 2019
24. Sorbic Acid as a Triplet Probe: Triplet Energy and Reactivity with Triplet-State Dissolved Organic Matter via 1O2 Phosphorescence
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Paul R. Erickson, Kristopher McNeill, Markus Schmitt, and Kyle J. Moor
- Subjects
Quenching (fluorescence) ,Singlet oxygen ,Kinetics ,chemistry.chemical_element ,General Chemistry ,010501 environmental sciences ,Photochemistry ,01 natural sciences ,Oxygen ,3. Good health ,chemistry.chemical_compound ,chemistry ,Environmental Chemistry ,Reactivity (chemistry) ,Triplet state ,Phosphorescence ,Sorbic acid ,0105 earth and related environmental sciences - Abstract
Sorbic acid (2,4-hexadienoic acid; HDA) is commonly used as a probe and quencher for triplet-excited chromophoric dissolved organic matter (3CDOM*), an important transient species in natural waters, yet much remains unknown about its reactivity with 3CDOM* and its triplet energy. To better understand the quenching behavior of HDA, we measured HDA quenching rate constants for various humic substance isolates and whole waters with singlet oxygen (1O2) phosphorescence and determined the triplet energy of HDA. Low-temperature phosphorescence measurements determined the triplet energy of HDA to be 217 kJ mol–1, whereas a complementary method based on triplet quenching kinetics found a triplet energy of 184 ± 7 kJ mol–1. Time-resolved 1O2 phosphorescence measurements yielded different HDA quenching rate constants depending on the fitting method. Using an approach that considered the reactivity of the entire triplet pool produced values of (∼1–10) × 108 M–1 s–1, while an approach that considered only the reactivity of the high-energy triplets output higher rate constants ((∼7–30) × 108 M–1 s–1). In addition, the model based on high-energy triplet reactivity found that ∼30–60% of 3CDOM* is not quenched by HDA. Findings from this study provide a more comprehensive view on the use of HDA as a probe for 3CDOM*., Environmental Science & Technology, 53 (14), ISSN:0013-936X, ISSN:1520-5851
- Published
- 2019
25. Differences in photochemistry between seawater and freshwater for two natural organic matter samples
- Author
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Kyle J. Moor, D. James Donaldson, Laura T. Stirchak, and Kristopher McNeill
- Subjects
010504 meteorology & atmospheric sciences ,chemistry.chemical_element ,Artificial seawater ,Fresh Water ,Sodium Chloride ,010501 environmental sciences ,Management, Monitoring, Policy and Law ,Photochemistry ,01 natural sciences ,Oxygen ,chemistry.chemical_compound ,Rivers ,Environmental Chemistry ,Magnesium ,Seawater ,Triplet state ,Anisotropy ,0105 earth and related environmental sciences ,Quenching (fluorescence) ,Singlet oxygen ,Public Health, Environmental and Occupational Health ,General Medicine ,Photochemical Processes ,chemistry ,13. Climate action ,Reactive Oxygen Species ,Oxidation-Reduction ,Fluorescence anisotropy - Abstract
We report changes in the excitation and resolved fluorescence spectra, inferred triplet formation and singlet oxygen formation abilities of two different Natural Organic Matter samples (NOM) in seawater vs. freshwater or NaCl solution. In artificial seawater solution (but not in NaCl solution), the natural water-derived NOM samples Suwannee River Natural Organic Matter (SRNOM) and Nordic Reservoir Natural Organic Matter (NRNOM) display large enhancements in fluorescence intensity. Nearly identical spectra are seen when seawater is replaced by solutions of Mg2+ at its seawater concentration, consistent with magnesium binding to ligand sites of the natural organic matter giving rise to different photophysics. Fluorescence anisotropy measurements show a decrease in anisotropy of SRNOM and NRNOM in seawater, also consistent with Mg2+ binding. Different effects of Mg2+ are seen when the different NOM samples are illuminated: NRNOM exhibits increased formation of its triplet state and also quenching of its triplet by oxygen, compared to its photochemistry in the absence of Mg2+, while SRNOM exhibits a reduction in triplet formation in the presence of Mg2+. These observations imply that the photochemistry of NOM in seawater may be very different from what is expected based on freshwater or NaCl solution measurements.
- Published
- 2019
26. Singlet Oxygen Quantum Yields in Environmental Waters
- Author
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Rachele, Ossola, Oskar Martin, Jönsson, Kyle, Moor, and Kristopher, McNeill
- Abstract
Singlet oxygen (
- Published
- 2021
27. Kinetics and Pathways of the Aqueous Photolysis of Pharmaceutical Pollutants: A Versatile Laboratory or Remote Learning Investigation
- Author
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Meghan O'Connor, Jeffrey M. Buth, Rachele Ossola, Kristopher McNeill, Sarah B. Partanen, William A. Arnold, and Douglas E. Latch
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Pollutant ,Aqueous solution ,Singlet oxygen ,business.industry ,05 social sciences ,Reactive intermediate ,Photodissociation ,050301 education ,First-Year Undergraduate/General ,Second-Year Undergraduate ,Upper-Division Undergraduate ,Analytical Chemistry ,Environmental Chemistry ,Laboratory Instruction ,Physical Chemistry ,Distance Learning/Self Instruction ,Drugs/Pharmaceuticals ,Kinetics ,Photochemistry ,Context (language use) ,General Chemistry ,010501 environmental sciences ,01 natural sciences ,6. Clean water ,Education ,chemistry.chemical_compound ,Reaction rate constant ,chemistry ,13. Climate action ,Personal computer ,Process engineering ,business ,0503 education ,0105 earth and related environmental sciences - Abstract
In this laboratory experiment, students explore the aquatic photochemical fate of ranitidine and cimetidine, two common pharmaceutical pollutants found in wastewater. It provides an engaging environmental context for students to develop knowledge of reaction kinetics and photochemistry as well as skill in using analytical instrumentation. This versatile experiment consists of two basic modules, three optional advanced modules, and additional add-ons that may be performed in various combinations to meet the unique learning objectives of general, analytical, physical, and environmental chemistry courses and science outreach activities. It may be performed as a traditional lab experiment or as an entirely remote exercise with an increased focus on data analysis and interpretation using provided example data sets. All of the photolysis experiments are carried out by preparing solutions of ranitidine or cimetidine in various matrices, irradiating the samples, and periodically removing subsamples for HPLC analysis of the compound of interest. Pseudo-first order kinetic plots are then generated to determine rate constants that are used to draw conclusions about photolysis pathways or to calculate additional kinetic parameters. In the two basic modules, cimetidine is found to degrade appreciably only when irradiated in the presence natural organic matter (NOM), indicating an indirect, photosensitized degradation pathway. In contrast, ranitidine degrades in pure buffer and in the presence of NOM with comparable rate constants, highlighting the predominant role of direct photolysis. In the advanced modules, students calculate ranitidine direct photolysis quantum yields and examine the significance of singlet oxygen as a photochemically produced reactive intermediate. The two basic modules may be completed in two 3 hour lab periods, while the advanced modules require additional time. This experiment requires only an HPLC instrument, inexpensive chemicals, and common glassware and lab equipment if performed in person and a personal computer if performed remotely. ISSN:0021-9584 ISSN:1938-1328
- Published
- 2020
28. Linking Triclosan's Structural Features to Its Environmental Fate and Photoproducts
- Author
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Sarah Kliegman, Kristopher McNeill, Claudia Solá-Gutiérrez, and Jennifer N. Apell
- Subjects
Photolysis ,Substituent ,Quantum yield ,chemistry.chemical_element ,General Chemistry ,010501 environmental sciences ,Photochemistry ,01 natural sciences ,Triclosan ,chemistry.chemical_compound ,chemistry ,Chlorine ,Environmental Chemistry ,Degradation (geology) ,Environmental systems ,Photodegradation ,Degradation pathway ,Water Pollutants, Chemical ,0105 earth and related environmental sciences - Abstract
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. In addition, the photodegradation of two classes of photoproducts-dibenzo-p-dioxins (DDs) and 2,2'-dihydroxylated biphenyls-was also investigated. Degradation of triclosan in near-surface sunlit waters was relatively fast (t1/2 < 5 h). Calculated degradation rates were slower for DDs and faster for dihydroxylated biphenyls in comparison to that for triclosan. In addition, the 2'-Cl substituent was critical for the high quantum yield measured for triclosan and necessary for the photodegradation mechanism that forms DDs and dihydroxylated biphenyls. The 4-Cl substituent was responsible for higher rates of light absorption and the environmentally relevant pKa. Without either of these substituents, the environmental fate of triclosan would be markedly different.
- Published
- 2020
29. Substituent Effects on the Direct Photolysis of Benzotrifluoride Derivatives
- Author
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Jeroen van den Wildenberg, Aline Hänggli, Alessandro Manfrin, and Kristopher McNeill
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Active ingredient ,Photolysis ,Herbicides ,Ultraviolet Rays ,Photodissociation ,Substituent ,food and beverages ,General Chemistry ,010501 environmental sciences ,Pesticide ,01 natural sciences ,Crop protection ,Fluorobenzenes ,chemistry.chemical_compound ,chemistry ,Environmental Chemistry ,Organic chemistry ,0105 earth and related environmental sciences - Abstract
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 CF3 moiety. In the present work, we explore the structure-reactivity relationship between ring substituent and direct photodefluorination for 16 different substituents, by determining fluoride production rates, quantum yields, and half-lives, and found that strong electron-donating groups enhance the reactivity toward hydrolysis. In addition, flufenamic acid, travoprost, dutasteride, cyflumetofen, flutoanil, and teriflunomide were also examined, finding that their direct photochemical reactivity could be qualitatively predicted based on their ring substituents. We provide here a tool to evaluate the environmental persistence of benzotrifluoride contaminants, as well as to design more photodegradable new active ingredients., Environmental Science & Technology, 54 (18), ISSN:0013-936X, ISSN:1520-5851
- Published
- 2020
30. Photochemical production of sulfate from dissolved organic matter and atmospheric aqueous phases: Is there something in common?
- Author
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Lenny H. E. Winkel, Rachele Ossola, Kristopher McNeill, Julie Tolu, and Baptiste Clerc
- Subjects
chemistry.chemical_compound ,Aqueous solution ,Chemistry ,Environmental chemistry ,Dissolved organic carbon ,Sulfate - Abstract
In a recent study, we showed that photodegradation of dissolved organic sulfur (DOS) from a wide range of natural terrestrial environments releases sulfate (SO42–) and other small and highly oxidized S-containing compounds as degradation products, similar to what had already been reported for dissolved organic carbon, nitrogen and phosphorous. However, the underlying chemical mechanism of photoproduction of sulfate is still unknown.To fill this knowledge gap, we selected cysteine as a DOS model compound and we investigated its photodegradation to sulfate using model sensitizers as the source of singlet oxygen (1O2) and triplet excited states (3Sens*), two photochemically produced reactive species ubiquitous in sunlit surface waters. Using a combination of steady-state photochemistry experiments, kinetic modeling and mechanistic knowledge from the biochemistry literature, we reconstructed the molecular events that likely lead to the release of sulfate. We found that the release of SO2 via triplet-sensitized fragmentation of cysteine sulfinic acid, a 1O2 degradation product of cysteine, is a key step in the reaction mechanism. In the presence of oxygen and a photosensitizer, SO2 is then rapidly oxidized to SO42–.Interestingly, nowadays there is great interest in the atmospheric chemistry community on the same transformation (i.e., aqueous phase oxidation of SO2 to SO42–) in the context of extreme haze events. Triplet-induced SO2 oxidation has already been proposed as a potential aqueous phase reaction that might explain the mismatch between measured and modelled sulfate concentrations, but the mechanism of this process is still not established. Our work provides an example of how mechanistic knowledge gained on the (photo)chemical behaviour of dissolved organic matter in aquatic systems can offer insights on processes occurring in atmospheric aqueous phases.
- Published
- 2020
31. Dissolved Organic Matter Singlet Oxygen Quantum Yields: Evaluation Using Time-Resolved Singlet Oxygen Phosphorescence
- Author
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Paul R. Erickson, Sarah B. Partanen, Kristopher McNeill, Kyle J. Moor, and Douglas E. Latch
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Radiation ,Singlet Oxygen ,Chemistry ,Singlet oxygen ,Isolation procedures ,Quantum yield ,General Chemistry ,010501 environmental sciences ,Photochemistry ,01 natural sciences ,Natural organic matter ,Colored dissolved organic matter ,chemistry.chemical_compound ,Rivers ,Dissolved organic carbon ,Environmental Chemistry ,Phosphorescence ,Quantum ,Hydrophobic and Hydrophilic Interactions ,Humic Substances ,0105 earth and related environmental sciences - Abstract
Singlet oxygen (1O2) generation quantum yields from chromophoric dissolved organic matter (CDOM) have been reported for many samples over the past 4 decades. Yet even for standardized isolates such as those from the International Humic Substance Society (IHSS), wide-ranging values exist in the literature. In this manuscript, time-resolved 1O2 phosphorescence was used to determine the 1O2 quantum yields (ΦΔ) of a variety of dissolved organic matter (DOM) isolates and natural waters. In general, the 1O2 quantum yield values in this study are in the middle, although below the median of the range of past reported values (e.g., for Suwannee River Natural Organic Matter IHSS isolate: 1.8% vs 0.23–2.89%). Notably, hydrophobic neutral fractions of DOM isolates were found to possess the highest 1O2 quantum yields, an interesting result given that these fractions are not retained in typical humic and fulvic acid isolation procedures that use XAD resins. The excitation wavelength dependence of 1O2 generation from CDOM was also examined, and an approximate linear decrease with longer excitation wavelength was observed. This work advances the understanding of CDOM photoprocesses, especially in relation to wavelength-dependent 1O2 production, which is valuable for assessing real-world environmental behavior., Environmental Science & Technology, 54 (6), ISSN:0013-936X, ISSN:1520-5851
- Published
- 2020
32. Offering authors a choice: introduction of optional double-blind peer review
- Author
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Peter J. Vikesland, Kristopher McNeill, and Paige J. Novak
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Publishing ,Environmental Engineering ,Multimedia ,Materials Science (miscellaneous) ,Public Health, Environmental and Occupational Health ,General Medicine ,Management, Monitoring, Policy and Law ,computer.software_genre ,Double blind ,Double-Blind Method ,Environmental Chemistry ,Letters ,Psychology ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,computer ,Water Science and Technology ,General Environmental Science - Abstract
The Editors-in-Chief of the Environmental Science journals discuss the introduction of optional double-blind peer review.
- Published
- 2020
33. UV/Vis+ photochemistry database: Structure, content and applications
- Author
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Gerd K. Hartmann, Askar Fahr, B.N. Rajasekhar, Ann Carine Vandaele, David J. Lary, John J. Orlando, Paulo Limão-Vieira, Robert Locht, Andreas Noelle, Kristopher McNeill, Farid Salama, Javier Martin-Torres, Richard P. Wayne, Yuan-Pern Lee, Chenyi Yuan, DF – Departamento de Física, and CeFITec – Centro de Física e Investigação Tecnológica
- Subjects
Medical diagnostic ,Astrochemistry ,Radiation ,010504 meteorology & atmospheric sciences ,Photochemistry ,Photodissociation ,medicine.disease_cause ,Linear dichroism ,01 natural sciences ,Article ,Atomic and Molecular Physics, and Optics ,UV/Vis ,Database ,Spectroscopy ,Radiative transfer ,Database structure ,Ultraviolet visible spectroscopy ,medicine ,Ultraviolet ,0105 earth and related environmental sciences - Abstract
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. The database contains photochemical data including absorption, fluorescence, photoelectron, and circular and linear dichroism spectra, as well as quantum yields and photolysis related data that are critically needed in many scientific disciplines. This manuscript gives an outline regarding the structure and content of the “science-softCon UV/Vis+ Photochemistry Database”. The accurate and reliable molecular level information provided in this database is fundamental in nature and helps in proceeding further to understand photon, electron and ion induced chemistry of molecules of interest not only in spectroscopy, astrochemistry, astrophysics, Earth and planetary sciences, environmental chemistry, plasma physics, combustion chemistry but also in applied fields such as medical diagnostics, pharmaceutical sciences, biochemistry, agriculture, and catalysis. In order to illustrate this, we illustrate the use of the UV/Vis+ Photochemistry Database in four different fields of scientific endeavor., Journal of Quantitative Spectroscopy and Radiative Transfer, 253, ISSN:0022-4073, ISSN:1879-1352
- Published
- 2020
- Full Text
- View/download PDF
34. Mechanistic Insights into Dissolved Organic Sulfur Photomineralization through the Study of Cysteine Sulfinic Acid
- Author
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Baptiste Clerc, Rachele Ossola, and Kristopher McNeill
- Subjects
Organic product ,chemistry.chemical_element ,Hydrogen Peroxide ,General Chemistry ,010501 environmental sciences ,01 natural sciences ,Sulfur ,Kinetics ,chemistry.chemical_compound ,chemistry ,Environmental chemistry ,Dissolved organic carbon ,Environmental Chemistry ,Cysteine sulfinic acid ,Cysteine ,Water Pollutants, Chemical ,0105 earth and related environmental sciences - Abstract
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 (SO42–). We use kinetic analysis, targeted experiments, and previous literature from several fields of chemistry to explain the elementary steps that lead to the release of sulfate. Our analysis indicates that triplet sensitizers act as one-electron oxidants on the sulfinate S lone pair. The resulting radical undergoes C–S fragmentation to form SO2, which becomes hydrated to sulfite/bisulfite (S(IV)). S(IV) is further oxidized to SO42– in the presence of triplet sensitizers and oxygen. We point out that the reaction sequence SO2 ⇌ S(IV) → SO42– is valid independently of the chemical structure of the model compound and might represent a sulfate photoproduction mechanism with general validity for DOS. Our mechanistic investigation revealed that amino acids in general might also be photochemical precursors of CO2, ammonia, acetaldehyde, and H2O2 and that reaction byproducts can influence the rate and mechanism of S(IV) (photo)oxidation., Environmental Science & Technology, 54 (20), ISSN:0013-936X, ISSN:1520-5851
- Published
- 2020
- Full Text
- View/download PDF
35. Assessing the environmental transformation of nanoplastic through 13C-labelled polymers
- Author
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Michael Sander, Kristopher McNeill, and Hans-Peter E. Kohler
- Subjects
chemistry.chemical_classification ,Materials science ,Biomedical Engineering ,Bioengineering ,Nanotechnology ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Transformation (music) ,0104 chemical sciences ,chemistry ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
To assess potential risks posed by plastic nanoparticles, we must study the way in which they transfer and transform in the environment. Using 13C-labelled nanoplastics could provide a safe and effective way to establish whether the plastic is mineralized or whether it persists in the environment.
- Published
- 2019
36. The Case Against Charge Transfer Interactions in Dissolved Organic Matter Photophysics
- Author
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Paul R. Erickson, Kristopher McNeill, Julie A. Korak, Garrett McKay, Fernando L. Rosario-Ortiz, and Douglas E. Latch
- Subjects
chemistry.chemical_classification ,Primary (chemistry) ,General Chemistry ,010501 environmental sciences ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Fluorescence ,Spectral line ,0104 chemical sciences ,Solvent ,Absorbance ,Viscosity ,chemistry ,Dissolved organic carbon ,Environmental Chemistry ,Organic matter ,sense organs ,Ecosystem ,0105 earth and related environmental sciences - Abstract
The optical properties of dissolved organic matter influence chemical and biological processes in all aquatic ecosystems. Dissolved organic matter optical properties have been attributed to a charge-transfer model in which donor–acceptor complexes play a primary role. This model was evaluated by measuring the absorbance and fluorescence response of organic matter isolates to changes in solvent temperature, viscosity, and polarity, which affect the position and intensity of spectra for known donor–acceptor complexes of organic molecules. Absorbance and fluorescence spectral shape were largely unaffected by these changes, indicating that the distribution of absorbing and emitting species was unchanged. Overall, these results call into question the wide applicability of the charge-transfer model for explaining organic matter optical properties and suggest that future research should explore other models for dissolved organic matter photophysics., Environmental Science & Technology, 52 (2), ISSN:0013-936X, ISSN:1520-5851
- Published
- 2017
37. Distribution of intermediate host snails of schistosomiasis and fascioliasis in relation to environmental factors during the dry season in the Tchologo region, Côte d’Ivoire
- Author
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Eliézer K. N’Goran, Nathalie Wandel, Stefanie J. Krauth, Louise Y. Achi, Penelope Vounatsou, Jan Hattendorf, Kristopher McNeill, Seïdinan I. Traoré, and Jürg Utzinger
- Subjects
2. Zero hunger ,0301 basic medicine ,Schistosoma haematobium ,biology ,Fasciola ,fungi ,030231 tropical medicine ,Intermediate host ,Biomphalaria ,Zoology ,Snail ,030108 mycology & parasitology ,Physa ,biology.organism_classification ,03 medical and health sciences ,0302 clinical medicine ,biology.animal ,parasitic diseases ,Bulinus ,Water Science and Technology ,Schistosoma - Abstract
Snail-borne trematodiases, such as fascioliasis and schistosomiasis, belong to the neglected tropical diseases; yet, millions of people and livestock are affected. The spatial and temporal distribution of intermediate host snails plays an important role in the epidemiology and control of trematodiases. Snail distribution is influenced by numerous environmental and anthropomorphic factors. The aim of this study was to assess the distribution and constitution of the snail fauna during the dry season in constructed and natural water bodies in the Tchologo region, northern Cote d’Ivoire, and to relate these findings to environmental factors and human infections. Snails were collected using standard procedures and environmental parameters were assessed from a total of 50 water bodies in and around 30 randomly selected villages. A canonical correspondence analysis was performed to establish the relationship between snail occurrence and environmental factors. Furthermore, a total of 743 people from the same 30 villages and nearby settlements were invited for stool and urine examination for the diagnosis of Fasciola spp., Schistosoma haematobium and Schistosoma mansoni. Snails of medical importance of the genera Biomphalaria, Bulinus, Lymnaea and Physa were found. Differences in snail occurrence from sites sampled in December 2014 and snails sampled in February 2015, as well as between the northern and southern part of the study area, were revealed. Various environmental factors, such as temperature and human activities, were related to the occurrence of intermediate host snail species in the region. Only 2.3% of human participants tested positive for schistosomiasis, while no Fasciola eggs were found in stool samples. We conclude that intermediate host snails of Fasciola and Schistosoma co-occur in water bodies in the Tchologo region and that the distribution of these snails correlates not only with environmental factors, but also with the presence of humans and animals and the environmental contamination of their excreta.
- Published
- 2017
38. Reductive Outer-Sphere Single Electron Transfer Is an Exception Rather than the Rule in Natural and Engineered Chlorinated Ethene Dehalogenation
- Author
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Benjamin Heckel, Martin Elsner, Stefan Cretnik, Sarah Kliegman, Orfan Shouakar-Stash, and Kristopher McNeill
- Subjects
Carbon Isotopes ,Tetrachloroethylene ,Reaction mechanism ,Chemistry ,Inorganic chemistry ,Isotopes of chlorine ,Halogenation ,Electrons ,General Chemistry ,Ethylenes ,010501 environmental sciences ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Trichloroethylene ,0104 chemical sciences ,chemistry.chemical_compound ,Biodegradation, Environmental ,Isotopes of carbon ,Kinetic isotope effect ,Outer sphere electron transfer ,Environmental Chemistry ,Bond cleavage ,0105 earth and related environmental sciences - Abstract
Chlorinated ethenes (CEs) such as perchloroethylene, trichloroethylene and dichloroethylene are notorious groundwater contaminants. Although reductive dehalogenation is key to their environmental and engineered degradation, underlying reaction mechanisms remain elusive. Outer-sphere reductive single electron transfer (OS-SET) has been proposed for such different processes as Vitamin B12-dependent biodegradation and zerovalent metal-mediated dehalogenation. Compound-specific isotope effect (13C/12C, 37Cl/35Cl) analysis offers a new opportunity to test these hypotheses. Defined OS-SET model reactants (CO2 radical anions, S2–-doped graphene oxide in water) caused strong carbon (eC = −7.9‰ to −11.9‰), but negligible chlorine isotope effects (eCl = −0.12‰ to 0.04‰) in CEs. Greater chlorine isotope effects were observed in CHCl3 (eC = −7.7‰, eCl = −2.6‰), and in CEs when the exergonicity of C–Cl bond cleavage was reduced in an organic solvent (reaction with arene radical anions in glyme). Together, this points ...
- Published
- 2017
39. Deconvolution of Mass Spectral Interferences of Chlorinated Alkanes and Their Thermal Degradation Products: Chlorinated Alkenes
- Author
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Kristopher McNeill, Christian Bogdal, Norbert V. Heeb, Peter Lienemann, Lena Schinkel, and Sandro Lehner
- Subjects
Isotope ,Chemistry ,010401 analytical chemistry ,Analytical chemistry ,Atmospheric-pressure chemical ionization ,010501 environmental sciences ,Contamination ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Chlorinated paraffins ,Quadrupole ,Thermal ,Degradation (geology) ,Deconvolution ,0105 earth and related environmental sciences - Abstract
Chlorinated paraffins (CPs) are high production volume chemicals and ubiquitous environmental contaminants. CPs are produced and used as complex mixtures of polychlorinated n-alkanes containing thousands of isomers, leading to demanding analytical challenges. Due to their high degree of chlorination, CPs have highly complex isotopic mass patterns that often overlap, even when applying high resolution mass spectrometry. This is further complicated in the presence of degradation products such as chlorinated alkenes (CP-enes). CP-enes are formed by dehydrochlorination of CPs and are expected thermal degradation products in some applications of CPs, for example, as metal working fluids. A mathematical method is presented that allows deconvolution of the strongly interfered measured isotope clusters into linear combinations of isotope clusters of CPs and CP-enes. The analytical method applied was direct liquid injection into an atmospheric pressure chemical ionization source, followed by quadrupole time-of-flight mass spectrometry (APCI-qTOF-MS), operated in full scan negative ion mode. The mathematical deconvolution method was successfully applied to a thermally aged polychlorinated tridecane formulation (Cl
- Published
- 2017
40. Response to Comment on The Case Against Charge Transfer Interactions in Dissolved Organic Matter Photophysics
- Author
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Fernando L. Rosario-Ortiz, Julie A. Korak, Paul R. Erickson, Kristopher McNeill, Garrett McKay, and Douglas E. Latch
- Subjects
Chemical physics ,Chemistry ,Dissolved organic carbon ,Environmental Chemistry ,Charge (physics) ,02 engineering and technology ,General Chemistry ,010501 environmental sciences ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences ,0105 earth and related environmental sciences - Published
- 2018
41. A streamlined workflow to study direct photodegradation kinetic and transformation products for persistence assessment of a fragrance ingredient in natural waters
- Author
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Jianming Lin, Jennifer N. Apell, Kristopher McNeill, Matthew E. Emberger, Valerie Ciraulo, and Sylvia Gimeno
- Subjects
010504 meteorology & atmospheric sciences ,Quantum yield ,010501 environmental sciences ,Management, Monitoring, Policy and Law ,01 natural sciences ,Persistence (computer science) ,Workflow ,Dissolved organic carbon ,Cyclohexenes ,Environmental Chemistry ,Photodegradation ,0105 earth and related environmental sciences ,Photolysis ,Chemistry ,Natural water ,Public Health, Environmental and Occupational Health ,General Medicine ,Fragrance ingredient ,Kinetics ,Aquatic environment ,Environmental chemistry ,Odorants ,Sunlight ,Degradation (geology) ,Water Pollutants, Chemical ,Half-Life - Abstract
Photodegradation can be an important abiotic degradation process to consider for the fate and persistence assessment of chemical substances in the environment. In this work, using a fragrance ingredient (FI, (E)-4-(2,2,3,6-tetramethylcyclohexyl)but-3-en-2-one) as an example, we developed a streamlined workflow to investigate direct photodegradation of chemicals in the aquatic environment, including laboratory investigation of kinetics and transformation products and estimation of its aquatic environmental half-lives. Direct photodegradation was determined to be the dominant photodegradation process for FI with a quantum yield of 0.25, which was supported by photodegradation experiments conducted in natural sunlight. Accounting for light attenuation by dissolved organic matter in natural waters of different depths resulted in aquatic half-lives of
- Published
- 2019
42. Photodegradation of Fludioxonil and Other Pyrroles: The Importance of Indirect Photodegradation for Understanding Environmental Fate and Photoproduct Formation
- Author
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Kristopher McNeill, Jennifer N. Apell, and Nicholas C. Pflug
- Subjects
Photolysis ,Chemistry ,General Chemistry ,Dioxoles ,010501 environmental sciences ,Pesticide ,Fludioxonil ,01 natural sciences ,Europe ,Environmental chemistry ,Environmental Chemistry ,Pyrroles ,Product (category theory) ,Photodegradation ,Water Pollutants, Chemical ,0105 earth and related environmental sciences - Abstract
Fludioxonil is a pyrrole-containing pesticide whose registration as a plant protection product is currently under review in the United States and Europe. There are concerns over its potential persistence and toxicity in the aquatic environment; however, the pyrrole moiety represents a potential reaction site for indirect photodegradation. In this study, the direct and indirect photodegradation of fludioxonil, along with pyrrole, 3-cyanopyrrole, and 3-phenylpyrrole, were investigated. Results showed that pyrrole moieties are capable of undergoing direct photoionization and sensitized photooxidation to form radical cation species, which then likely deprotonate and react with dissolved oxygen. Additionally, pyrrole moieties can undergo reactions with singlet oxygen (
- Published
- 2019
43. Dos and Do Nots When Assessing the Biodegradation of Plastics
- Author
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Michael Sander, Kristopher McNeill, Hans-Peter E. Kohler, Ramani Narayan, and Michael T. Zumstein
- Subjects
Biodegradation, Environmental ,Waste management ,Chemistry ,MEDLINE ,Environmental Chemistry ,General Chemistry ,Biodegradation ,Plastics - Published
- 2019
44. Reactive Oxygen Species Production from Secondary Organic Aerosols: The Importance of Singlet Oxygen
- Author
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Kurtis T. Malecha, Kristopher McNeill, Gordon J. Getzinger, Nadine Borduas-Dedekind, Sergey A. Nizkorodov, and Alessandro Manfrin
- Subjects
chemistry.chemical_classification ,Biphenyl ,Aerosols ,Reactive oxygen species ,Air Pollutants ,Singlet Oxygen ,Singlet oxygen ,Radical ,General Chemistry ,Hydrogen Peroxide ,010501 environmental sciences ,Photochemistry ,01 natural sciences ,7. Clean energy ,Toluene ,chemistry.chemical_compound ,chemistry ,13. Climate action ,Environmental Chemistry ,Sink (computing) ,Hydrogen peroxide ,Reactive Oxygen Species ,0105 earth and related environmental sciences ,Naphthalene - Abstract
Organic aerosols are subjected to atmospheric processes driven by sunlight, including the production of reactive oxygen species (ROS) capable of transforming their physicochemical properties. In this study, secondary organic aerosols (SOA) generated from aromatic precursors were found to sensitize singlet oxygen (1O2), an arguably underappreciated atmospheric ROS. Specifically, we quantified 1O2, OH radical, and H2O2 quantum yields within photoirradiated solutions of laboratory-generated SOA from toluene, biphenyl, naphthalene, and 1,8-dimethylnaphthalene. At 5 mgC L–1 of SOA extracts, the average steady-state concentrations of 1O2 and of OH radicals in irradiated solutions were 3 ± 1 × 10–14 M and 3.6 ± 0.9 × 10–17 M, respectively. Furthermore, ROS quantum yields of irradiated ambient PM10 extracts were comparable to those from laboratory-generated SOA, suggesting a similarity in ROS production from both types of samples. Finally, by using our measured ROS concentrations, we predict that certain organic compounds found in aerosols, such as amino acids, organo-nitrogen compounds, and phenolic compounds have shortened lifetimes by more than a factor of 2 when 1O2 is considered as an additional sink. Overall, our findings highlight the importance of SOA as a source of 1O2 and its potential as a competitive ROS species in photooxidation processes., Environmental Science & Technology, 53 (15), ISSN:0013-936X, ISSN:1520-5851
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- 2019
45. Sorbic Acid as a Triplet Probe: Reactivity of Oxidizing Triplets in Dissolved Organic Matter by Direct Observation of Aromatic Amine Oxidation
- Author
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Markus Schmitt, Paul R. Erickson, Kristopher McNeill, and Kyle J. Moor
- Subjects
chemistry.chemical_classification ,Direct observation ,Aromatic amine ,General Chemistry ,010501 environmental sciences ,01 natural sciences ,Sorbic Acid ,6. Clean water ,3. Good health ,Kinetics ,chemistry.chemical_compound ,Energy Transfer ,chemistry ,Dissolved organic carbon ,Oxidizing agent ,Environmental Chemistry ,Organic chemistry ,Reactivity (chemistry) ,Amines ,Sorbic acid ,Oxidation-Reduction ,Isomerization ,0105 earth and related environmental sciences - Abstract
Sorbic acid (2,4-hexadienoic acid; HDA) isomerization is frequently used to probe triplet-state dissolved organic matter (3CDOM*) reactivity, but there remain open questions about the reaction kinetics of 3CDOM* with HDA due to the difficulties of directly measuring 3CDOM* quenching rate constants. Using our recently developed approach based on observing the radical cation of N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) formed through oxidation of TMPD by 3CDOM*, we studied 3CDOM* quenching kinetics with HDA monitored via transient absorption spectroscopy. A competition kinetics-based approach utilizing formation yields of TMPD•+ was developed, validated with model sensitizers, and used to determine bimolecular rate constants between 3CDOM* oxidants and HDA for diverse DOM isolates and natural waters samples, yielding values in the range of (2.4–7.7) × 108 M–1 s–1. The unquenchable fraction of TMPD-oxidizing triplets showed that, on average, 41% of 3CDOM* oxidants cannot be quenched by HDA. Conversely, cycloheptatriene quenched nearly all TMPD•+-forming triplets in CDOM, suggesting that most 3CDOM* oxidants possess energies greater than 150 kJ mol–1. Comparing results with our companion study, we found slight, but noticeable differences in the 3CDOM* quenching rate constants by HDA and unquenchable triplet fractions determined by oxidation of TMPD and energy transfer to O2 (1O2 formation) methods. ISSN:0013-936X ISSN:1520-5851
- Published
- 2019
46. Sorbic Acid as a Triplet Probe: Triplet Energy and Reactivity with Triplet-State Dissolved Organic Matter via
- Author
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Kyle J, Moor, Markus, Schmitt, Paul R, Erickson, and Kristopher, McNeill
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Physical Phenomena ,Kinetics ,Radiation ,Singlet Oxygen ,Sorbic Acid - Abstract
Sorbic acid (2,4-hexadienoic acid; HDA) is commonly used as a probe and quencher for triplet-excited chromophoric dissolved organic matter (
- Published
- 2019
47. Photochemical Production of Sulfate and Methanesulfonic Acid from Dissolved Organic Sulfur in Natural Waters
- Author
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Lenny H. E. Winkel, Julie Tolu, Kristopher McNeill, Rachele Ossola, Baptiste Clerc, and Paul R. Erickson
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chemistry.chemical_compound ,Biogeochemical cycle ,chemistry ,Aquatic ecosystem ,Dissolved organic carbon ,Sulfur cycle ,chemistry.chemical_element ,Sulfate ,Photodegradation ,Photochemistry ,Methanesulfonic acid ,Sulfur - Abstract
Despite its importance in biological processes and its influence on metal bioavailability, the biogeochemical cycle of dissolved organic sulfur (DOS) in aquatic systems is still poorly understood. Recent high-resolution mass spectrometry (HRMS) studies showed a selective loss of organic sulfur during photodegradation of dissolved organic matter (DOM), which was hypothesized to result in the production of sulfate. Here, we provide evidence of ubiquitous production of sulfate, methanesulfonic acid (MSA) and methanesulfinic acid (MSIA) during photodegradation of DOM samples from a wide range of natural terrestrial environments. We show that photochemical production of sulfate is generally at least one order of magnitude more efficient than the production of MSA and MSIA, as well as volatile S-containing compounds (i.e., CS2and COS). We also identify possible molecular precursors for sulfate and MSA, and we demonstrate that a wide range of relevant classes of DOS compounds (in terms of S oxidation state and molecular structure) can liberate sulfate upon photosensitized degradation. This work indicates that photochemistry plays a more significant role in the aquatic and atmospheric cycle of DOS than currently believed.
- Published
- 2019
48. Photomineralization mechanism changes the ability of dissolved organic matter to activate cloud droplets and to nucleate ice crystals
- Author
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Nadine Borduas-Dedekind, Rachele Ossola, Robert O. David, Lin S. Boynton, Vera Weichlinger, Zamin A. Kanji, and Kristopher McNeill
- Subjects
13. Climate action ,sense organs ,complex mixtures - Abstract
An organic aerosol particle has a lifetime of approximately 1 week in the atmosphere during which it will be exposed to sunlight. However, the effect of photochemistry on the propensity of organic matter to participate in the initial cloud-forming steps is difficult to predict. In this study, we quantify on a molecular scale the effect of photochemical exposure of naturally occurring dissolved organic matter (DOM) and of a fulvic acid standard on its cloud condensation nuclei (CCN) and ice nucleation (IN) activity. We find that photochemical processing, equivalent to 4.6 d in the atmosphere, of DOM increases its ability to form cloud droplets by up to a factor of 2.5 but decreases its ability to form ice crystals at a loss rate of −0.04 ∘CT50 h−1 of sunlight at ground level. In other words, the ice nucleation activity of photooxidized DOM can require up to 4 ∘C colder temperatures for 50 % of the droplets to activate as ice crystals under immersion freezing conditions. This temperature change could impact the ratio of ice to water droplets within a mixed-phase cloud by delaying the onset of glaciation and by increasing the supercooled liquid fraction of the cloud, thereby modifying the radiative properties and the lifetime of the cloud. Concurrently, a photomineralization mechanism was quantified by monitoring the loss of organic carbon and the simultaneous production of organic acids, such as formic, acetic, oxalic and pyruvic acids, CO and CO2. This mechanism explains and predicts the observed increase in CCN and decrease in IN efficiencies. Indeed, we show that photochemical processing can be a dominant atmospheric ageing process, impacting CCN and IN efficiencies and concentrations. Photomineralization can thus alter the aerosol–cloud radiative effects of organic matter by modifying the supercooled-liquid-water-to-ice-crystal ratio in mixed-phase clouds with implications for cloud lifetime, precipitation patterns and the hydrological cycle.Highlights. During atmospheric transport, dissolved organic matter (DOM) within aqueous aerosols undergoes photochemistry. We find that photochemical processing of DOM increases its ability to form cloud droplets but decreases its ability to form ice crystals over a simulated 4.6 d in the atmosphere. A photomineralization mechanism involving the loss of organic carbon and the production of organic acids, CO and CO2 explains the observed changes and affects the liquid-water-to-ice ratio in clouds.
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- 2019
49. Supplementary material to 'Photomineralization mechanism changes the ability of dissolved organic matter to activate cloud droplets and to nucleate ice crystals'
- Author
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Nadine Borduas-Dedekind, Rachele Ossola, Robert O. David, Lin S. Boynton, Vera Weichlinger, Zamin A. Kanji, and Kristopher McNeill
- Published
- 2019
50. Singlet Oxygen Photooxidation of Peptidic Oxazoles and Thiazoles
- Author
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Kate Lau, Alessandro Manfrin, Kristopher McNeill, and Nadine Borduas-Dedekind
- Subjects
Reaction mechanism ,medicine.drug_class ,Carboxamide ,Peptide ,010402 general chemistry ,Peptides, Cyclic ,01 natural sciences ,Reaction rate ,chemistry.chemical_compound ,Reaction rate constant ,medicine ,Oxazoles ,Oxazole ,chemistry.chemical_classification ,Singlet Oxygen ,010405 organic chemistry ,Singlet oxygen ,Organic Chemistry ,Valine ,Photochemical Processes ,Combinatorial chemistry ,Cycloaddition ,0104 chemical sciences ,Kinetics ,Thiazoles ,chemistry ,Peptides ,Oxidation-Reduction - Abstract
Oxazoles and thiazoles are commonly found moieties in nonribosomal peptides (NRPs) and ribosomally synthesized post-translationally modified peptides (RiPPs), which are important biomolecules present in the environment and in natural waters. From previous studies, they seem susceptible to oxidation by singlet oxygen (1O2); therefore, we designed and synthesized model oxazole- and thiazole-peptides and measured their 1O2 bimolecular reaction rate constants, showing slow photooxidation under environmental conditions. We reasoned their stability through the electron-withdrawing effect of the carboxamide substituent. Reaction products were elucidated and support a reaction mechanism involving cycloaddition followed by a series of rearrangements. The first 1O2 bimolecular reaction rate constant for a RiPP, the thiazole-containing peptide Aerucyclamide A, was measured and found in good agreement with the model peptide’s rate constant, highlighting the potential of using model peptides to study the transformations of other environmentally relevant NRPs and RiPPs., The Journal of Organic Chemistry, 84 (5), ISSN:0022-3263, ISSN:1520-6904
- Published
- 2019
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