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18 results for “photodegradation”
Physical and microbial processing of dissolved organic nitrogen (DON) (Photodegradation Experiment) along an oligotrophic marsh/mangrove/estuary ecotone (Taylor Slough and Florida Bay) for August 2003 in Everglades National Park (FCE), South Florida, USA
A better understanding of the biogeochemical cycling of nutrients entering Florida Bay is a key issue regarding the restoration of the Everglades. In addition to precipitation, the other major source of freshwater to Florida Bay is from Taylor Slough and the C-111 Basin in the northeast section of the Bay. While it is known that these areas deliver significant amounts of N to the Bay, a significant portion of this is in the form of dissolved organic N (DON). The sources, environmental fate and bioavailability to microorganisms of this DON are however, not known. Should this DON be readily available, any increased load as a function of restoration changes might have an impact on internal phytoplankton bloom dynamics. No significant flocculation or precipitation of DOM occurred with increase in salinity, meaning that terrestrial DOM does not get trapped in the sediments but stays in the water column where it subjected to photolysis and advective transport. Sunlight has a significant effect on the chemical characteristics of DOM. While the DOC levels did not change significantly during photo-exposure, the optical characteristics of the DOM were modified. The environmental implications of this are conflicting: photo-induced polymerization may stabilize the DOM by reducing its bioavailability while photolysis may make the DOM more labile. Overall, DON bioavailability was relatively low in this region. Even though the amount of DON loaded to the bay may be significant, the fraction of DON available for microbial cycling is much smaller. The amount of N supplied by recycling may be a significant portion of the total DIN pool. All this must be considered in context with the proposed CERP modifications to flows. As of the latest initial Comprehensive Everglades Restoration Project (CERP) update, the flows to Taylor Slough and C-111/Panhandle Basis are not predicted to change very much from base conditions. Therefore we do not expect any great increases in TN loading in this
Photodegradation of phenol (τOH) by TiO2-based nanophotocatalysts determined in line with the SAPNet methodology
<p>The independent variable (predictor) is the intensity of photoluminescence at 398 nm and with use of logistic regression model connects ability of photocatalytic degradation of phenol (endpoint) with this experimentally derived property. The equation goes as follow:<br> 4.32(±2.10) – 0.051(±0.03)(PL398)</p> <p>The developed model is included into the SAPNet workflow (Structure-Activity Prediction Network). In an additional step of SAPNet workflow developed model correlates the structure of a nanomaterial to the selected endpoint- photodegradation of phenol (τOH) by titanium dioxide synthesized in the presence of ionic liquids (IL). </p> <p>Each sample is described by surface area, the amount of nitrogen and carbon atoms, ionic liquid decomposition rate (ΔIL), molar ratio and the type of cations and anions, that influences photoluminescence </p>
Photodegradation and biodegradation of dissolved organic carbon from four lakes of varying trophic status in Pennsylvania and Florida in 2016
The enclosed data are results from a series of monthly (May-August) experiments conducted in 2016. We measured changes in five variables (dissolved organic carbon (DOC), dissolved inorganic carbon, dissolved oxygen, the spectral slope ratio, and the DOC specific ultraviolet absorbance at 320 nm). Groundwater samples adjacent to four lakes of varying trophic status were used to assess changes in the above variables due to photodegradation and biodegradation. Three lakes (Lacawac, Giles, and Waynewood) are located in the Pocono region of Pennsylvania. The fourth lake (Annie) is located in Venus, FL. Details of the experiment can be found in Dempsey et al. 2020 (accepted at Biogeosciences). In this study, we used groundwater (terrestrial DOC) to simulate storm water inputs to the surface of a lake. We assessed the relative importance of photodegradation and biodegradation by measuring changes in the above variables. All experiments were conducted on the surface of Lake Lacawac (PA). Here, we provide our raw data from the experiments. Outgassing of carbon dioxide (CO2) from freshwater ecosystems comprises 12-25% of the total carbon flux from soils and bedrock. This CO2 is largely derived from both biodegradation and photodegradation of terrestrial dissolved organic carbon (DOC) entering lakes from wetlands and soils in the watersheds of lakes. In spite of the significance of these two processes in regulating rates of CO2 outgassing, their relative importance remains poorly understood in lake ecosystems. In this study, we used groundwater from the watersheds of one subtropical and three temperate lakes of differing trophic status to simulate the effects of increases in terrestrial DOC from storm events. We assessed the relative importance of biodegradation and photodegradation in oxidizing DOC to CO2. We measured changes in DOC concentration, colored dissolved organic carbon (SUVA320 and Sr), dissolved oxygen, and dissolved inorganic carbon (DIC) in short-term experiment
Photodegradation of carboxyl DOC from permafrost soils collected from the North Slope of Alaska in the summer of 2015
Dissolved organic carbon (DOC) was leached from permafrost soils near the Toolik Field Station in the Alaskan Arctic and then characterized for its photochemical properties. The photodegradation of carboxyl carbon (C) within permafrost DOC was quantified by 13C nuclear magnetic resonance (NMR).
Data and code from: Soil decomposer can regulate the legacy effect of photodegradation on forest marcescent litter decomposition, but emerging microplastics disrupt this
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Data From: Shedding light on cobalamin photodegradation in the ocean
<p>Cobalamin, vitamin B<sub>12</sub>, is an important micronutrient that has been investigated for decades in the marine context because it is required for phytoplankton growth. The biologically active forms (Me-B<sub>12</sub>, Ado-B<sub>12</sub>) and the synthetic form (CN-B<sub>12</sub>) quickly convert to OH-B<sub>12</sub> after light exposure in various aqueous solutions, but puzzlingly have been frequently reported to dominate dissolved cobalamin pools in the sunlit ocean. Here we document photodegradation timescales for these cobalamin forms in natural seawater using targeted mass spectrometry, providing quantitative evidence that OH-B<sub>12</sub> is expected to be the dominant dissolved form in irradiated seawater. Then, through high resolution mass spectrometry, we identify four photodegradation products of OH-B<sub>12</sub> which represent potential building blocks microbes could salvage and remodel to satisfy cellular cobalamin requirements. Taken together, these results clarify the impact of light on marine cobalamin dynamics, laying a foundation for a more quantitative understanding of the role of cobalamin in microbial communities and biogeochemical cycles.</p>
Photodegradation of plant litter cuticles enhances microbial decomposition by increasing uptake of non-rainfall moisture
<p>Litter decomposition plays a central role in carbon cycling in terrestrial ecosystems worldwide. In drylands, which cover 40% of the Earth's land surface, photodegradation and biotic decomposition driven by non-rainfall moisture are important mechanisms of litter decay, though studies have only recently begun examining interactions between these two processes. We describe a novel priming mechanism in which photodegradation and biotic decay of the cuticle of plant litter increases litter absorption of non-rainfall moisture (fog, dew, and water vapor), supporting greater microbial decomposition.</p> <p>We used several field experiments in a coastal fog desert and a series of in situ observations to demonstrate a relationship between solar radiation, cuticle integrity, water absorption rates, and mass loss.</p> <p>Experimentally attenuating solar radiation for 36 months slowed mass loss, reduced cuticle degradation, and decreased litter moisture uptake relative to litter under ambient sunlight controls. In a separate field experiment, removing the cuticle of recently senesced grass tillers increased mass loss four-fold over 6 months relative to controls. Tillers with degraded cuticles also absorbed 3.8 times more water following an overnight dew event than did those with intact cuticles. Finally, fungal growth was consistently greater on the sun-facing side of in situ tillers than on the shaded side, coincident with greater cuticle degradation.</p> <p>We present a conceptual model where the cuticle of plant litter acts as a water-resistant barrier that is first degraded by solar radiation and surficial microbes, increasing litter's ability to absorb enough water during non-rainfall moisture events to support substantial biotic decomposition inside the tissue. Considering how photodegradation and non-rainfall moisture are both substantial drivers of litter decomposition in drylands, understanding how they interact under realistic field conditions will help us better predict how these systems are responding to changing climate regimes.</p>
Data from: Photodegradation modifies microplastic effects on soil properties and plant performance
<p>Microplastics in soil affect plant-soil systems depending on their shape and polymer type. However, previous research has not yet considered the effects of degraded plastics, which are the plastic materials actually present in the environment. We selected 8 microplastics representing different shapes (fibers, films and foams) and polymer types, and exposed them to UV-C degradation. Each microplastic was mixed with soil at a concentration of 0.4% (w/w). The phytometer Daucus carota grew in each pot. At harvest, soil properties and plant biomass were measured.</p> <p>Photodegradation altered microplastics physical and chemical properties, impacting plant-soil systems. Microplastics degradation effects on plant and soil were observed with fibers and foams, but there were negligible effects with films. The latter could be explained by the polymer structure of films and manufacturer's additives, potentially delaying their degradation.</p> <p>Degraded fibers increased soil respiration more than their non-degraded counterparts, as photodegradation increased the positive effects of fibers on soil water retention. The emergence of oxygenated groups during degradation may have increased the hydrophilicity of fibers, enhancing their ability to retain water. Degraded foams increased soil respiration, which could be related to the possible leaching of organic substances with lower partition coefficients, which may promote soil microbial activity.</p> <p>By contrast, degraded foams decreased soil aggregation, likely as degradation produced larger holes increasing their permeability. Also, the increase of hydrophilic molecules could have decreased soil particle cohesiveness. Degraded fibers and foams increased shoot and root mass as a result of microplastic effects on soil properties. Photodegraded microplastics affected root traits, which could be linked to microplastic effects on soil water status and plant coping strategies.</p>
Photodegradation of plant litter cuticles enhances microbial decomposition by increasing uptake of non-rainfall moisture
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Data From: Shedding light on cobalamin photodegradation in the ocean
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Data from: Photodegradation modifies microplastic effects on soil properties and plant performance
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Impacts of urbanization and nutrient fertilization on mass loss and nutrient dynamics during photodegradation of plant litter
To understand the potential impacts of N deposition on mass loss and chemical dynamics during aridland decomposition, we assessed N and phosphorus (P) dynamics of decomposing litter in a long-term N+P enrichment experiment in both urban (with N deposition) and outlying areas (without N deposition) of the Sonoran Desert. Litter was decomposed with and without UV radiation for 9 months, measuring mass loss, litter chemistry, and bacterial biomass. UV radiation significantly accelerated mass loss and altered N and P dynamics, and there was an impact of the urban environment and experimental fertilization on nutrient dynamics. Overall, these patterns suggest that the aridland urban environment, where rates of N deposition are elevated, alters nutrient dynamics during decomposition but not the fraction of litter lost to photodegradation.
UV Litter Decomposition: The role of photodegradation in surface litter decomposition in grasslands along UV-B gradient
Process-based models of plant litter decomposition typically underestimate the rates of decomposition in arid and semi-arid grasslands. Recent research, including our field studies, suggests that photodegradation, the decomposition of material through solar radiation, may play an important role in arid and semi-arid grassland ecosystems. The contribution of photodegradation to overall rates of decomposition is not well understood or quantified. The goal of this project is to investigate the effects of ultraviolet radiation on rates of plant litter decomposition for two grass species, Andropogon gerardii and Bouteloua gracilis, in three grassland sites: Cedar Creek (MN), Shortgrass Steppe (CO), and Sevilleta (NM).
Synthesis of Bismuth Oxyhalide (BiOBrzI(1-z)) Solid Solutions for Photodegradation of Methylene Dye
<p>BiOBr<sub>z</sub>I<sub>(1-z)</sub> (0 ≤ z ≤ 1) materials were successfully prepared through hydrothermal method. Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), X-ray diffractometer (XRD), and scanning electron microscope (SEM) was used to determine the surface area, microstructure, crystal structure, and morphology of the resultant products. The photocatalytic performance of BiOBr<sub>z</sub>I<sub>(1-z)</sub> materials was examined through methylene blue (MB) degradation under ultraviolet (UV) light and solar irradiation. The XRD shows that BiOBr<sub>z</sub>I<sub>(1-z) </sub>materials crystallized into a tetragonal crystal structure with (102) peak slightly shifting to lower diffraction angle with increase in the amount of iodide (I<sup>-</sup>). BiOBr<sub>0.6</sub>I<sub>0.4 </sub>materials showed a point of zero charge of 5.29 and presented the highest photocatalytic activity in the removal of MB with 99 and 88% efficiency under solar and UV irradiation, respectively. The kinetics studies of MB removal by BiOBr<sub>z</sub>I<sub>(1-z) </sub>materials shows that the degradation process followed nonlinear pseudo-first-order model indicating that the removal of MB depends on the population of the adsorption sites. Trapping experiments confirmed that photogenerated holes (h<sup>+</sup>) and superoxide radicals (<sup>•</sup>O<sub>2</sub><sup>−</sup>) are the key species responsible for the degradation of MB. The experimental results agree with nonlinear fitting.</p>
Fluorescence spectra presenting kinetic photodegradation of ciprofloxacin and levofloxacin
<p><span>First derivative synchronous fluorescence spectroscopy (FDSFS) was applied to detect and quantify ciprofloxacin (CIP) and levofloxacin (LEV) simultaneously with their photodegradation products, where the photolytic pathway for each analyte was found to be pH dependant. Under the guidance of early published articles, the structure of the produced photolytic products could be concluded, and further related to their resultant fluorescence spectra. The proposed method was subjected to a full validation procedure which enables its application in investigating the photodegradation kinetics for both drugs. The obtained kinetic parameters were in accordance with previous reports and could be linked to predict the antibacterial activity of the resultant photodegradation products. These facts prove the suitability of the suggested FDSFS to serve as a stability-indicating assay method and to trace the photofate of CIP and LEV in the ecosystem as potential contaminants. Furthermore, the greenness of the suggested analytical methodology was evaluated via </span><span>the ˝</span> <span>Green Analytical Procedure Index˝ (GAPI), which classifies it as an eco-friendly assay. Eventually, no extraction, treatment, or preparation steps were needed during all analysis steps, which renders the proposed assay an appealing tool in environmental analysis. </span></p>
Enhancement of carbamazepine photodegradation using hybrid of phosphorescent carbon dots coupled with highly porous TiO2 photocatalyst
<p>Data used for creation of the Figures for publication</p>
Fluorescence spectra presenting kinetic photodegradation of ciprofloxacin and levofloxacin
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Photodegraded Edible Food Dyes
ClinicalTrials.gov study NCT04708704. IPD Sharing: NO. Countries: 1. Publications: 0.
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