Effects Of Simulated Solar Radiation Research Articles

Solar photolysis of soluble microbial products as precursors of disinfection by-products in surface water

In the Pearl River Delta area, the upstream municipal wastewater is commonly discharged into rivers which are a pivotal source of downstream drinking water. Solar irradiation transforms some of the dissolved organic matter discharged from the wastewater, also affecting the formation of disinfection by-products in subsequent drinking water treatment plants. The effect of simulated solar radiation on soluble microbial products extracted from activated sludge was documented in laboratory experiments. Irradiation was found to degrade macromolecules in the effluent, yielding smaller, more reactive intermediate species which reacted with chlorine or chloramine to form higher levels of noxious disinfection by-products. The soluble microbial products were found to be more active in formation of disinfection by-products regard than naturally-occurring organic matter. The results show that solar irradiation induced the formation of more trihalomethane (THMs), chloral hydrate (CH) and trichloronitromethane (TCNM), causing greater health risks for downstream drinking water.

Oxidation of arsenite to arsenate on birnessite in the presence of light.

The effect of simulated solar radiation on the oxidation of arsenite [As(III)] to arsenate [As(V)] on the layered manganese oxide, birnessite, was investigated. Experiments were conducted where birnessite suspensions, under both anoxic and oxic conditions, were irradiated with simulated solar radiation in the presence of As(III) at pH 5, 7, and 9. X-ray absorption spectroscopy (XAS) was used to determine the nature of the adsorbed product on the surface of the birnessite. The oxidation of As(III) in the presence of birnessite under simulated solar light irradiation occurred at a rate that was faster than in the absence of light at pH 5. At pH 7 and 9, As(V) production was significantly less than at pH 5 and the amount of As(V) production for a given reaction time was the same under dark and light conditions. The first order rate constant (kobs) for As(III) oxidation in the presence of light and in the dark at pH 5 were determined to be 0.07 and 0.04 h−1, respectively. The As(V) product was released into solution along with Mn(II), with the latter product resulting from the reduction of Mn(IV) and/or Mn(III) during the As(III) oxidation process. Post-reaction XAS analysis of As(III) exposed birnessite showed that arsenic was present on the surface as As(V). Experimental results also showed no evidence that reactive oxygen species played a role in the As(III) oxidation process.Electronic supplementary materialThe online version of this article (doi:10.1186/s12932-016-0037-5) contains supplementary material, which is available to authorized users.

Spore sensitivity to sunlight and freezing can restrict dispersal in wood-decay fungi.

Assessment of the costs and benefits of dispersal is central to understanding species' life-history strategies as well as explaining and predicting spatial population dynamics in the changing world. While mortality during active movement has received much attention, few have studied the costs of passive movement such as the airborne transport of fungal spores. Here, we examine the potential of extreme environmental conditions to cause dispersal mortality in wood-decay fungi. These fungi play a key role as decomposers and habitat creators in forest ecosystems and the populations of many species have declined due to habitat loss and fragmentation. We measured the effect of simulated solar radiation (including ultraviolet A and B) and freezing at −25°C on the spore germinability of 17 species. Both treatments but especially sunlight markedly reduced spore germinability in most species, and species with thin-walled spores were particularly light sensitive. Extrapolating the species' laboratory responses to natural irradiance conditions, we predict that sunlight is a relevant source of dispersal mortality at least at larger spatial scales. In addition, we found a positive effect of spore size on spore germinability, suggesting a trade-off between dispersal distance and establishment. We conclude that freezing and particularly sunlight can be important sources of dispersal mortality in wood-decay fungi which can make it difficult for some species to colonize isolated habitat patches and habitat edges.

Solar-simulated radiation and heat treatment induced metalloproteinase-1 expression in cultured dermal fibroblasts via distinct pathways: Implications on reduction of sun-associated aging

BackgroundSun exposure is an important environmental factor affecting human beings. Most knowledge regarding solar aging focused on light radiation (photoaging), and little emphasis has been placed on heat, a factor that is also closely associated with sun exposure. ObjectiveThis study was launched to evaluate the effects of simulated solar radiation (SSR) and environmental heat on skin fibroblasts in terms of dermal aging. MethodsCultured human dermal fibroblasts were treated with moderate amount of SSR (200J/cm2) and heat (+2°C). The metalloproteinase-1 (MMP-1) expression was used as a surrogate marker for dermal aging and the involved regulatory mechanisms were explored. ResultsBoth treatment conditions did not affect viability but significantly increased the expressions of MMP-1. In parallel, both treatments increased the intracellular levels of reactive oxygen species (ROS), but the increase induced by SSR is much greater than heat. In contrast, transient receptor potential vanilloid 1 (TRPV-1), the sensor of environmental heat, was upregulated by heat but not SSR treatment. Pretreating fibroblasts with antioxidant abrogated the SSR-induced MMP-1 but has limited effect on heat-induced MMP-1. On the other hand, TRPV-1 antagonist pretreatment reduced heat-induced MMP-1 in fibroblasts but not their SSR-treated counterparts. ConclusionBoth SSR and heat induced MMP-1 expression in dermal fibroblasts but through different pathways. As current strategies for reducing sun-related aging focused on filtering of light and use of antioxidants, future strategies design to reduce solar aging should also incorporate heat-induced aging into consideration.

Effect of simulated solar radiation on the interaction of humic acids with naphthalene

The equilibrium constants of binding of naphthalene with a series of humic acids were determined by the fluorescence quenching method. The effect of irradiation on the extent of the interaction of naphthalene with humic acids was examined. Based on the data obtained, preliminary conclusions on the structure of humic acids of raised bog peat before and after modification were made.

Anterior Clinoidectomy

Sun exposure is an important environmental factor affecting human beings. Most knowledge regarding solar aging focused on light radiation (photoaging), and little emphasis has been placed on heat, a factor that is also closely associated with sun exposure.This study was launched to evaluate the effects of simulated solar radiation (SSR) and environmental heat on skin fibroblasts in terms of dermal aging.Cultured human dermal fibroblasts were treated with moderate amount of SSR (200 J/cm2) and heat (+2 °C). The metalloproteinase-1 (MMP-1) expression was used as a surrogate marker for dermal aging and the involved regulatory mechanisms were explored.Both treatment conditions did not affect viability but significantly increased the expressions of MMP-1. In parallel, both treatments increased the intracellular levels of reactive oxygen species (ROS), but the increase induced by SSR is much greater than heat. In contrast, transient receptor potential vanilloid 1 (TRPV-1), the sensor of environmental heat, was upregulated by heat but not SSR treatment. Pretreating fibroblasts with antioxidant abrogated the SSR-induced MMP-1 but has limited effect on heat-induced MMP-1. On the other hand, TRPV-1 antagonist pretreatment reduced heat-induced MMP-1 in fibroblasts but not their SSR-treated counterparts.Both SSR and heat induced MMP-1 expression in dermal fibroblasts but through different pathways. As current strategies for reducing sun-related aging focused on filtering of light and use of antioxidants, future strategies design to reduce solar aging should also incorporate heat-induced aging into consideration.

The effects of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced erythema, DNA damage and sunburn cell formation in human skin

alpha-Hydroxy acids (alphaHAs) are reported to reduce signs of aging in the skin and are widely used cosmetic ingredients. Several studies suggest that alphaHA can increase the sensitivity of skin to ultraviolet radiation. More recently, beta-hydroxy acids (betaHAs), or combinations of alphaHA and betaHA have also been incorporated into antiaging skin care products. Concerns have also arisen about increased sensitivity to ultraviolet radiation following use of skin care products containing beta-HA. To determine whether topical treatment with glycolic acid, a representative alphaHA, or with salicylic acid, a betaHA, modifies the short-term effects of solar simulated radiation (SSR) in human skin. Fourteen subjects participated in this study. Three of the four test sites on the mid-back of each subject were treated daily Monday-Friday, for a total of 3.5 weeks, with glycolic acid (10%), salicylic acid (2%), or vehicle (control). The fourth site received no treatment. After the last treatment, each site was exposed to SSR, and shave biopsies from all four sites were obtained. The endpoints evaluated in this study were erythema (assessed visually and instrumentally), DNA damage and sunburn cell formation. Treatment with glycolic acid resulted in increased sensitivity of human skin to SSR, measured as an increase in erythema, DNA damage and sunburn cell formation. Salicylic acid did not produce significant changes in any of these biomarkers. Short-term topical application of glycolic acid in a cosmetic formulation increased the sensitivity of human skin to SSR, while a comparable treatment with salicylic acid did not.

Phototoxicity of oil sands–derived polycyclic aromatic compounds to japanese medaka (Oryzias latipes) embryos

Alkylated polycyclic aromatic compounds (PACs), which are rich in dibenzothiophenes, are present in natural and reclaimed aquatic environments in the oil sands region of northern Alberta (Canada). An oil sands-derived PAC extract has been shown to induce signs of blue sac disease in Japanese medaka (Oryzias latipes) embryos. Information regarding exposure to and effects of oil sands PACs is available, but little of this information concerns the impact of modifying factors. The present study focuses on the effect of simulated solar radiation on oil sands-derived PAC toxicity to Japanese medaka embryos. Photomodification of the oil sands PAC extract caused reduced toxicity with an increase in the duration of ultraviolet (UV) exposure. Generally, mortality and developmental endpoints and, to a lesser extent, growth were affected by photomodification. Coexposures of the PAC mixture and UV caused slight increases in toxicity for mortality and embryonic developmental endpoints at the longest duration of UV exposure tested (16 h). Based on the modest phototoxicity of the oil sands PAC extract to Japanese medaka embryos, enhanced toxicity associated with UV irradiation may not be a concern for embryos of fish species that are common to the oil sands region. However, testing the effects of differing levels of UV irradiation on larval fish and invertebrates that may differ in their PAC bioaccumulation would improve our understanding concerning the importance of UV irradiation as a modifying factor in oil sands environmental risk assessment.

Effects of solar simulated radiation on the human immune system: influence of phototypes and wavebands.

We have shown that skin-types I/II are much more susceptible to UVR-induced suppression of the induction phase of contact hypersensitivity than skin-types III/IV. Studies with a UVB sunscreen have provided indirect evidence that UVA is more immunosuppressive than it is erythemogenic. Overall, our studies show a lack of direct correlation between erythema and immunosuppression.

The Effect of Simulated Solar Radiation on Escherichia coli: The Relative Roles of UV-B, UV-A, and Photosynthetically Active Radiation.

The relative role of components of solar radiation (UV-B, UV-A, and photosynthetically active radiation) as well as the effect of simulated sunlight upon the physiological state of Escherichia coli in fresh water were evaluated. Simulated solar radiation had a sublethal effect on E. coli populations in a short-time exposure by provoking loss of culturability and the formation of viable but nonculturable cells. Prolonged exposure increased the damage to cells but cellular integrity was never affected. However, important differences between the way the sunlight components acted were detected. After photosynthetically active radiation (PAR) exposure, cells remained metabolically active but only 10% of the cells were culturable. When cells were exposed to UV-A, the culturable fraction was similar to the one obtained after PAR irradiation, although formation of viable but nonculturable cells was not observed. For UV-B radiation short-time exposures (6 h) were enough to provoke loss of culturability and a reduction in activity similar to that of simulated sunlight exposed cells. The effect of simulated solar radiation on E. coli cells was mainly attributable to shorter wavelengths, but a synergistic interaction of the UV-B, UV-A and PAR components was detected. </hea

Effects of simulated solar radiation on conidial germination of Metarhizium anisopliae in different formulations

The effects of exposure time to simulated solar radiation on conidial germination of Metarhizium anisopliae were evaluated with different formulations to determine whether some of them could enhance the ultraviolet (UV) tolerance of conidia. Conidial suspensions were prepared in water plus 10% emulsifiable oils; vegetable oil; mineral oils; and in water plus 0.05% Tween 80. Equal volumes (7.2 μl) of each 1 × 10 8/ml conidial suspension were placed into Petri dishes, and exposed to 2, 4 and 6 h solar radiation from an ‘Oriel’ sunlight simulator. Unexposed plates of all formulations were the controls. After irradiation, the formulations were diluted with equal volumes of Shellsol T or 0.05% Tween 80, and the resultant suspensions incubated on Sabouraud-Dextrose-Agar at 27 ± 0.5 °C. Conidial viability was assessed after 24 and 48 h incubation. Germination decreased for all treatments when the time of exposure to simulated solar radiation increased. Peanut oil, Shellsol plus Ondina, water plus Emoleo ®, Codacide ®, Natur'l oil ®, Ashlade ® significantly enhanced conidial tolerance ( P < 0.05) against UV light for up to 6 h of exposure compared with water plus Cropspray ®, Cutinol ®, Actipron ® and Tween. Unexposed control plates of all formulations showed that germination of conidia was more advanced than in those plates subjected to simulated sunlight, thus confirming that UV exposure delays germination.

Effect of simulated solar radiation on mixed outdoor atmospheric bacterial populations

Slit and Andersen cascade impact samplers were used to collect ambient atmospheric bacteria under clear conditions at noon and night onto Luria-Bertani agar surfaces. The bacteria were then directly exposed to simulated solar radiation (SSR) for increasing periods to evaluate the lethal effect of SSR. The results showed that SSR had marked differential lethal effects depending on the accumulated total solar irradiance, solar spectral property, bacterial species composition, and bacterial laden particle size. The simulated extraterrestrial solar spectrum had a greater lethality than the simulated terrestrial solar spectrum on the atmospheric bacteria collected at night (P<0.05); no such difference was found for the bacteria collected at noon. Statistical differences found only for the bacteria collected at night indicates that daytime solar radiation exposure could eliminate some sensitive bacterial populations from the ambient atmosphere. Sunlight exposure survival of the bacteria collected at noon linearly increased with respect to particle size. For each micrometer increase in particle aerodynamic diameter, there is an almost 11% increase in survival up to at least 7 μm aerodynamic diameter particles. The higher sunlight sensitivity of airborne bacteria in small particles could provide a partial explanation for the preponderance of large-sized culturable bacterial particles in the atmosphere during clear days.

Effect of simulated solar radiation on mixed outdoor atmospheric bacterial populations

Slit and Andersen cascade impact samplers were used to collect ambient atmospheric bacteria under clear conditions at noon and night onto Luria-Bertani agar surfaces. The bacteria were then directly exposed to simulated solar radiation (SSR) for increasing periods to evaluate the lethal effect of SSR. The results showed that SSR had marked differential lethal effects depending on the accumulated total solar irradiance, solar spectral property, bacterial species composition, and bacterial laden particle size. The simulated extraterrestrial solar spectrum had a greater lethality than the simulated terrestrial solar spectrum on the atmospheric bacteria collected at night ( P<0.05); no such difference was found for the bacteria collected at noon. Statistical differences found only for the bacteria collected at night indicates that daytime solar radiation exposure could eliminate some sensitive bacterial populations from the ambient atmosphere. Sunlight exposure survival of the bacteria collected at noon linearly increased with respect to particle size. For each micrometer increase in particle aerodynamic diameter, there is an almost 11% increase in survival up to at least 7 μm aerodynamic diameter particles. The higher sunlight sensitivity of airborne bacteria in small particles could provide a partial explanation for the preponderance of large-sized culturable bacterial particles in the atmosphere during clear days.

A single exposure of solar simulated radiation suppresses contact hypersensitivity responses both locally and systemically in humans: quantitative studies with high-frequency ultrasound

Ultraviolet radiation (UVR)-induced suppression of cutaneous cell-mediated immunity plays an important role in the development of photocarcinogenesis in the mouse and a similar role is suspected in humans. Cell-mediated immunity is readily tested in vivo by measuring the contact hypersensitivity (CHS) response to topically applied haptens. CHS in humans is usually determined clinically, with a subjective scoring system. However, these subjective scores cannot be statistically analysed. This paper compares four methods currently used to quantify CHS elicitation responses in humans. The data show that ultrasound images provide the most accurate and reproducible measurements of the clinically observed CHS response. We also demonstrate that assessment of the primary allergic response is a useful indicator of the magnitude of the elicitation response and can be used to avoid severe CHS reactions in volunteers. There are few human studies investigating the effects of solar simulated radiation (SSR) exposure on immunosuppression. In this study we demonstrate SSR is highly immunosuppressive in all subjects tested. Irradiating a small area of skin with a single exposure to 3MEDs of SSR completely suppressed CHS both locally (12/12 volunteers) and systemically (10/12 volunteers). Our data do not support a role for a genetic susceptibility to UVR-induced immunosuppression in humans.

Effects of simulated solar radiation on type I and type III collagens, collagenase (MMP-1) and stromelysin (MMP-3) gene expression in human dermal fibroblasts cultured in collagen gels

Understanding the mechanisms responsible for photodamage to the skin is most important for dermatology, 3-D cultures have been used as tools to mimic the in vivo situation for several years. We irradiated such a system containing human dermal fibroblasts cultured in collagen gels, a well-known model considered to be a dermal equivalent, which reproduces the interaction between cells and the surrounding extracellular matrix. The effects of solar irradiation (315–800 nm) on the stead-state levels of the mRNAs of extracellular matrix components (type 1 and III collagens) and their degrading enzymes (interstitial collagenase, MMP-1 and stromelysin 1, MMP-3) were measured. Exposure to low levels of solar radiation (0–10 J cm 2 in the UVA, i.e. suberythemal UVA doses) caused a transient decrease in type 1 procollagen mRNA, an increase in MMP-mRNA, and no change in type III procollagen mRNA steady-state levels. These results describe the early changes in the connective tissue of the skin following exposure to low level solar stimulation, and may help explain the long-term changes in photodamaged skin.

Effects of simulated solar radiation on the bioaccumulation of polycyclic aromatic hydrocarbons by the duckweed Lemna gibba

AbstractLight (particularly ultraviolet B) results in photomodification of polycyclic aromatic hydrocarbons (PAHs) to products with increased polarity and water solubility and enhanced toxicity relative to the parent compounds. The uptake and depuration kinetics of three representative PAHs, anthracene (ANT), phenanthrene (PHE), and benzo [a]pyrene (BAP), and their photomodified products were determined for Lemna gibba. The 14C‐labeled PAHs were delivered to the plants in their aqueous growth medium either via a dimethylsulfoxide (DMSO) carrier or adsorbed directly to sand placed in the medium. Assimilation was carried out under simulated solar radiation (SSR) and in darkness. The potential sites of PAH action within the plants were defined by identifying the subcellular location of both intact and photomodified PAHs following assimilation. Lemna gibba had a high capacity for intact ANT, PHE, and BAP in the dark regardless of the two routes of delivery. Depuration was also rapid. Net assimilation of all three PAHs in the dark was always higher when the chemicals were delivered with DMSO than from sand, although first‐order kinetics were apparent with both delivery systems. The relative levels of assimilation were PHE &gt; ANT &gt; BAP. Polycyclic aromatic hydrocarbons were rapidly assimilated under SSR, albeit net assimilation for both the intact and photomodified forms was generally lower under SSR compared with darkness. This was also reflected in the bioconcentration factors, which were highest in darkness for each PAH and dropped significantly under SSR and after photomodification. Both intact and photooxidized PAHs accumulated preferentially in the thylakoids and microsomes of L. gibba, suggesting these to be the subcellular compartments most at risk from PAH damage.

Seasonal adjustment of solar heat gain independent of coat coloration in a desert mammal.

Despite the apparent importance of solar radiation as a source of heat for free-living animals, there exists no substantial body of empirical data describing physiological responses to solar radiation under the range of convective conditions likely to occur in nature. We therefore quantified effects of simulated solar radiation and wind on metabolic heat production in the rock squirrel, Spermophilus variegatus. This diurnal mammal inhabits the Sonoran Desert and seasonally replaces its pelage in a fashion in which it retains constant external appearance but incorporates optical and structural changes that are thought to significantly alter heat-transfer properties of the coat. At a given wind speed, the presence of 950 W m-2 of simulated solar radiation reduces metabolic heat production by 15% (at a wind speed of 4 m s-1) to 37% (at a wind speed of 0.25 m s-1). Independent of effects of irradiance, metabolic heat production significantly increases with wind speed such that as wind speed is increased from 0.25 m s-1 to 4.0 m s-1, metabolic heat production is elevated by 66% (sunlight absent) or 88% (sunlight present). Previous analyses demonstrated that when exposed to identical radiative and convective environments rock squirrels with summer pelages accrue solar heat loads 33%-71% lower than those experienced by animals with winter coats. This reduction of solar heat gain during the extremely hot Sonoran Desert summer apparently constitutes a previously unappreciated mode of thermal adaptation by seasonal adjustment of radiative heat gain without changes in the animal's appearance.

The surface structure and reactivity of black carbon

Abstract Fourier transform infrared (FT-IR) spectroscopy has been the most definitive analytical tool in a comprehensive program on the structure and reactivity of black carbon (in the form of n -hexane soot). In combination with other techniques, it has revealed the soot structure, as produced by high temperature incomplete combustion, to be predominantly aromatic with a surface coverage by oxygen-containing functional groups of about 0.5. Particularly well suited to following net changes in surface groups, and gas phase reactant/product concentrations, FT-IR has been the key technique in determining the kinetics and mechanisms of some important heterogeneous reactions of black carbon with gas phase oxidant molecules. For example, the reaction of NO 2 /N 2 O 4 with soot follows a dual path mechanism, down to 2 p.p.m., which is reflected in the rate law: initial rate = (k 1 + k 2 [ soot ] 1 2 ) P NO2 . On the other hand, catalytic decomposition initiates the reaction with ozone, followed by the formation of surface carboxylic groups and gaseous CO 2 and H 2 O. The evidence suggests that dissociation of ozone yields a steady-state concentration of excited oxygen atom which is actually the oxidant. FTIR combined with chemical measurements has proven that a high solubility observed for carbon particles exposed to ozone has its origin in the hydrolysis of the surface carboxylics. Significant effects of simulated solar radiation on the reactions, especially in the soot/SO 2 /H 2 O/O 2 system, has been revealed by FTIR. Infrared will continue its central role in the examination of increasingly complex systems containing black carbon, particularly through its interface with ancillary techniques.

An FT-IR Study of the Effect of Simulated Solar Radiation and Various Particulates on the Oxidation of SO2

Short- and long-term studies of the effect of black carbon and other particulates on the oxidation of SO2 with and without the presence of oxygen, water vapor, and simulated solar radiation, have been carried out. FT-IR studies involving isotopic oxygen-18, sulfur dioxide-18, and D2O in these reactions confirm the requirement of water vapor and oxygen for this oxidation. Such experiments conducted at 298 K demonstrate only the formation of ionic sulfates, while the reactions conducted under simulated solar radiation show the formation of both covalent and ionic sulfate species. These observations have implications for the retention or diminution of catalytic activity by the soot. The reaction vessel walls, SiO2, and particulate black carbon, all act as catalysts for the conversion of S(IV) to S(VI), the amounts depending primarily on the surface area of the solid.

The effect of solar radiation on the survival of Entomophaga grylli (Entomophthorales: Entomophthoraceae) conidia

Laboratory studies on the effects of simulated solar radiation on Entomophaga grylli conidial viability showed definite interactions between the duration and intensity of exposure to the light source. When either variable was increased, the viability of E. grylli conidia was reduced. An exponential decay model was developed based on combining these two factors into a single predictive variable, exposure to cummulative solar radiation in Langleys. A minimum of approximately 3 Langleys was required before conidial viability decreased, with nearly 100% noted after exposure to 20 Langleys. The exponential decay model when applied to conidial viability data collected in the field provided an excellent fit; however, parameter estimates were significantly different from laboratory estimates as conidia were found to survive different periods of time in different habitats. The model predicted over 95% mortality in the most open habitats after exposure to ca. 50 Langleys. As expected, conidia exposed in lower canopy areas and in canopies with more dense foliage survived significantly longer (ca. 95% mortality after exposure to 700 Langleys).