The influence of cloudiness on UV global irradiance (295–385 nm)

Two years of continuous measurements of UV (295–385 nm) irradiance recorded at Granada (37.18°N, 3.58°W, 660 m a.m.s.l.), Spain, were combined with concurrent synoptic cloud observations to establish the relative influence of clouds on UV irradiance. A marked influence of cloud cover on UV irradiance is evident, but negligible for fractional cloud coverage below 3 octas. The ratio of UV irradiance to the total solar irradiance increases with cloud cover, especially for cloud cover greater than 4 octas, highlighting the different effects of cloud on total solar irradiance and UV irradiance. In order to determine the effect of cloud on UV irradiance, we considered a cloud modification factor, defined as the ratio between the UV measurements and the corresponding clear sky UV irradiance that would be expected for the same time period and atmospheric conditions. It is shown that the effect of cloud for UV wavelengths is less than that for the whole solar spectrum and less than that for the visible part of the spectrum. On the other hand, the small influence of cloud cover for intermediate cloudiness was accompanied by low variability and variability increases with increasing cloud cover.     

Selenium treatment alters the effects of UV radiation on chemical and production parameters in hybrid buckwheat

Ambient UV radiation is recognised as an important environmental factor in the regulation of plant growth and development, and selenium (Se) as a beneficial nutrient that can increase plant tolerance to different environmental constraints. The effects on hybrid buckwheat plants of full (+UV) and reduced (?UV) ambient UV radiation without (?Se) and with (+Se) foliar Se treatment (10?mg?L^?1 sodium selenate) provided the four conditions of Se?UV–, Se–+UV, +Se?UV and +Se+UV. Plant morphological, biochemical and physiological properties were examined, along with leaf elemental composition and content, efficiency of Se enrichment, and production parameters. Leaf anatomical parameters under all conditions were mainly affected by UV radiation, and less so by Se. +Se+UV plants showed a trade-off between primary and secondary metabolism, which resulted in high levels of protective substances (e.g. anthocyanins, UV absorbing compounds), and low levels of photosynthetic pigments. All +UV plants were significantly shorter in comparison to those under the reduced ?UV, while biomass production was highest for ?Se+UV plants and lowest for +Se+UV plants. +Se plants accumulated ～20-fold greater Se content compared to ?Se plants, and full ambient UV radiation partly reduced this effect. +UV plants showed increased phosphorus content in leaves, independent of Se status, while +Se plants showed increased K content. Si content was increased by Se treatment and decreased by the full UV exposure. Se treatment and the ambient UV radiation, separately have positive effects on growth and production of this hybrid buckwheat, while the combination of the Se treatment and ambient UV resulted in lower yields. However, under these conditions (+Se+UV), the buckwheat plants established good protection against the different environmental constraints that are becoming more and more frequent due to changes to our climate.     

Degradative Oxidation of 2,4,6 Trichlorophenol Using Advanced Oxidation Processes – A Comparative Study

In the present study, a comparative assessment of 2,4,6-T (2,4,6-Trichlorophenol) degradation by different AOPs (Advanced Oxidation Processes – UV, UV/ H₂O₂, Fenton, UV/Fenton and UV/TiO₂) in the laboratory scale is performed. The effects of different reactant concentrations and pH are assessed. 2,4,6-T removal, Total Organic Carbon mineralization (TOC) and dechlorination are monitored. Of all the AOPs, UV/Fenton process is more effective in degrading 2,4,6-T. The optimum conditions obtained for the best degradation with UV/Fenton are: pH?=?3, Fe⁺² concentration of about 5 ppm, and peroxide concentration of 100 ppm for an initial 100 ppm of 2,4,6 T concentration at room temperature. In these conditions, a pseudo first-order rate constant is evaluated. The degradation rate of 2,4,6 T followed the order: $$ {{{\text{UV}}} \mathord{\left/ {\vphantom {{{\text{UV}}} {{\text{Feton}}}}} \right. \kern-\nulldelimiterspace} {{\text{Feton}}}} > {{{\text{UV}}} \mathord{\left/ {\vphantom {{{\text{UV}}} {{\text{TiO}}_{\text{2}} > {{{\text{UV}}} \mathord{\left/ {\vphantom {{{\text{UV}}} {{\text{H}}_{\text{2}} {\text{O}}_{\text{2}} > {\text{Feton}}}}} \right. \kern-\nulldelimiterspace} {{\text{H}}_{\text{2}} {\text{O}}_{\text{2}} > {\text{Feton}}}}}}} \right. \kern-\nulldelimiterspace} {{\text{TiO}}_{\text{2}} > {{{\text{UV}}} \mathord{\left/ {\vphantom {{{\text{UV}}} {{\text{H}}_{\text{2}} {\text{O}}_{\text{2}} > {\text{Feton}}}}} \right. \kern-\nulldelimiterspace} {{\text{H}}_{\text{2}} {\text{O}}_{\text{2}} > {\text{Feton}}}}}} > {\text{UV}} $$      

Effect of Germination and UV‐C Radiation on the Accumulation of Flavonoids and Saponins in Black Bean Seed Coats

In the present study, we evaluated UV‐C radiation and germination treatments as an approach to increase the concentration of bioactive molecules in black bean seed coats. Black beans were germinated for 20 h under UV‐C radiation. Germination rate was higher in seeds radiated with UV‐C light compared with the control (nonirradiated seeds). Flavonoid content was increased twofold in seed coats of beans germinated for 10 h under UV‐C compared with the control. Quercetin‐3O‐glucoside was the major flavonoid identified in stressed seed coats. Furthermore, the application of UV‐C radiation during germination increased the content of soyasaponin Af, Ba, and αg, and it induced the de novo biosynthesis of soyasaponins (phaseoside I, soyasaponin deacetyl Af, and soyasaponin deactyl Ah) not present in the control. Germination of black beans under UV‐C radiation was an effective and simple approach to increase the concentration of bioactive molecules in black bean seed coats.     

The Oxidation of Di-(2-Ethylhexyl) Phthalate (DEHP) in Aqueous Solution by UV/H2O2 Photolysis

The oxidation of di-(2-ethylhexyl) phthalate (DEHP) in solution using UV/H₂O₂ and direct UV photolysis are analyzed in this study. It was found that DEHP was 100% removal in the solution by 180-min UV/H₂O₂ treatment and 73.5% removal by 180-min direct UV photolysis. The effect of different factors, such as DEHP concentration, H₂O₂ concentration, and UV light intensity, on photochemical degradation was investigated. The degradation mechanism of DEHP and the acute toxicity of intermediates were also studied. The photochemical degradation process was found to follow pseudo-first-order kinetics. The results of our study suggested that the concentration with 40 mg/L H₂O₂ and 5 μg/mL DEHP in the solution at pH 7 with 10.0?×?10^?6 Einstein l^?1?s^?1 UV was the optimal condition for the photochemical degradation of DEHP. The photochemical degradation with UV/H₂O₂ can be an efficient method to remove DEHP in wastewater.     

Comparison of the plant-damaging spectral solar ultraviolet radiation between three locations in Eastern USA in the year 2000

The National Ultraviolet Monitoring Center (NUVMC) maintains a network of Brewer Spectrophotometers that collect spectrally resolved, full sky ultraviolet (UV) irradiance values throughout the day. Using these data, an investigation into the spectral UV irradiances at several Brewer locations has been carried out by employing plant action spectra that represent a generalized response of plants to UV exposure. Analysis was performed for the year 2000 on the Chicago, Virgin Islands, and Shenandoah Brewer sites of the Eastern USA, which are of varying latitude, elevation, and atmospheric composition. The weighted and unweighted UV data grouped in SZA ranges of 10° increments is analyzed seasonally, highlighting the seasonal atmospheric differences between the sites. Results obtained in this paper suggest that UV data, when weighted with certain plant action spectra, show the potential sensitivity of plants to small changes in UV irradiances.     

Insensitivity of soybean photosynthesis to ultraviolet‐b radiation under phosphorus deficiency

Soybean [Glycine max (L.) Merr. cv Essex] was grown in sand in a greenhouse under 2 levels of biologically effective ultraviolet‐B radiation (effective daily dose: 0 and 11.5 kJ/m² UV‐BBE and 2 levels of P (6.5 and 52 μM). Plants were grown in each treatment combination up to the fifth trifoliolate stage. UV‐B radiation had no affect on plant growth and net photosynthesis at 6.5 μM P supply but decreased both these parameters when grown in the higher P concentration. Reductions in net photosynthesis were apparently due to direct effects on the photosynthetic machinery, since chlorophyll concentration and stanatal conductance were unaffected by UV‐B radiation. Both UV‐B radiation and reduced P supply increased the level of UV‐B absorbing compounds in leaf tissues and their effects were additive. The reduced sensitivity of P deficient plants to UV‐B radiation may be the result of this increase in UV absorbing compounds and possibly uv protective mechanisms associated with growth inhibition.     

Direct and indirect effects of ultraviolet-B radiation on soil biota, decomposition and nutrient fluxes in dune grassland soil systems

 Enhanced UV radiation did not show any effect on the decomposition of a mixed litter of the dune grassland plant species Calamagrostis epigeios and Carex arenaria. Also, leaching of nutrients from lysimeters filled with dune grassland soils was not affected by enhanced UV radiation. Negative UV effects on the fungal biomass in the first part of the experiment were later reversed into positive ones. Clear effects of both UV-A and UV-B were found on Collembola, both on total number of individuals and on the number of species. The decreased number of species under UV radiation could have been due to a decrease in UV-sensitive species. The role of pigmentation is discussed. Received: 6 July 1999     

测定土壤硝态氮的紫外分光光度法和镉柱还原法比较

使用改进的紫外分光光度法(校正因素法)和基于镉柱还原的流动注射分析法(镉柱还原法)测定了中国10种不同类型土壤的NO3–-N含量,分析了两种方法的差异性及其适用性。统计分析表明,改进紫外分光光度法与镉柱还原法测定的结果具有极显著的相关性,测定样品的准确度介于89%~104%,具有可比性。在浓度适用上略有差异,对NO3–-N含量极低的土壤样品,采用镉柱还原法可提高精确度;对于NO3–-N含量高的土样选用紫外法可提高测定精确度,测定结果变异性低于镉柱还原法,且紫外法测定值都要高于镉柱还原法。从仪器操作及校准角度来看,紫外法测定操作过程简便,影响因子较少,对NO3–-N批量快速测定更为适用。     

Emulsifying and foaming properties of ultraviolet-irradiated egg white protein and sodium caseinate

The physicochemical and functional properties of ultraviolet (UV)-treated egg white protein (EW) and sodium caseinate (SC) were investigated. UV irradiation of the proteins was carried out for 30, 60, 90, and 120 min. However, the SC samples were subjected to extended UV irradiation for 4 and 6 h as no difference was found on the initial UV exposure time. Formol titration, SDS-PAGE, and FTIR analyses indicated that UV irradiation could induce cross-linking on proteins and led to improved emulsifying and foaming properties (P < 0.05). These results indicated that the UV-irradiated EW and SC could be used as novel emulsifier and foaming agents in broad food systems for stabilizing and foaming purposes.     

Evaluation of chemical and photochemical oxidation processes for degradation of phosmet on lowbush blueberries (Vaccinium angustifolium)

Chemical and photochemical oxidation processes were evaluated for their ability to degrade residual phosmet on lowbush blueberries and for their role in the conversion of phosmet to phosmet oxon--a toxic metabolite of phosmet. Chemical processes included 1 ppm of aqueous ozone, 1% hydrogen peroxide, 100 ppm of chlorine, and UV, whereas photochemical processes included hydrogen peroxide/UV, chlorine/UV, and ozone/hydrogen peroxide/UV. Phosmet applied as Imidan 2.5EC under laboratory conditions resulted in a mean residual concentration of 44.4 ppm, which was significantly degraded (p < 0.05) by ozone and chlorine, yielding reductions of 57.7 and 46%, respectively. Interaction between phosmet (Imidan 2.5EC) and any chemical or photochemical treatment did not result in conversion to phosmet oxon. Residual analysis of commercially grown blueberries revealed mean phosmet (Imidan 70W) levels of 10.65 ppm and phosmet oxon levels of 12.49 ppm. Treatment of commercial blueberries resulted in significant reductions in phosmet regardless of treatment type; however, only UV, hydrogen peroxide/UV, and ozone treatments degraded phosmet (Imidan 70W) to less toxic metabolites and reduced phosmet oxon levels. Treatment-induced conversion of phosmet to phosmet oxon was noticeably influenced by variations between phosmet formulations. Acceleration of photochemical degradation by UV was not observed. Selective oxidation by ozone represents a significant postharvest process for degrading residual phosmet on lowbush blueberries.     

Photolysis, Sonolysis, and Photosonolysis of Trichloroethane (TCA), Trichloroethylene (TCE), and Tetrachloroethylene (PCE) Without Catalyst

Photolysis, sonolysis, and photosonolysis of common groundwater contaminants, namely 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene, were investigated using a flow-through photosono reactor system. Simulated groundwater containing the chlorinated volatile organic compounds (VOCs) was exposed to ultraviolet light (UV), ultrasonication (US), and UV and US concurrently (UVUS), without a photo catalyst. VOC removal efficiencies of the UV, US, and UVUS treatment processes were computed from the VOC concentrations in influent and effluent of the reactor. The process using UVUS exhibited larger degradation efficiencies than that with UV and US separately in most cases; however, statistical analysis showed that the UVUS treatment efficiency is likely to be additive of the UV and US treatment efficiencies. The results also showed that the increase of the detention time from 26 to 60 min had no significant effect on the VOC removal efficiencies in these processes.     

Surfactant-Assisted Sono-breakage of Wastewater Particles for Improved UV Disinfection

Ultraviolet (UV) disinfection of wastewater is adversely affected by the presence of particle-associated bacteria. Earlier studies have shown that disrupting these particles by ultrasonic cavitation can enhance the UV disinfection of wastewater. However, the use of ultrasound as a pretreatment technology for UV disinfection is hindered by its high energy demand. In this work, the addition of several organic solutes, including 1-propanol, 1-hexanol, and pentyl acetate, to promote the cavitation process and to improve the breakage of wastewater particles was examined. It was found that the enhancement in the cavitation and the breakage efficiency of particles was positively related to the hydrophobicity of surfactant. In addition, particle breakage was a function of the concentration of surfactant as well as the delivered ultrasound energy density. Sonication of wastewater samples containing small amounts of 1-hexanol (16 mM) or pentyl acetate (12 mM) increased the UV disinfection efficiency and decreased the required UV dose to achieve the disinfection target by a factor of more than 2.5.     

紫外线对水产养殖循环水的杀菌效果

为了研究循环水水产养殖系统紫外杀菌的效果,在循环水系统中对单灯管紫外装置杀灭养殖水中粪大肠菌群的效果进行了试验,研究了紫外灯功率、循环水流速和水的紫外光线透射率对杀菌效果的影响。结果表明,单位水体的紫外线功率越大,杀菌效果越好;水体通过紫外灯杀菌器的流速越大,单次通过杀菌器的杀菌量减少,但由于水体循环次数增加,总杀菌效果加大;254?nm紫外线透射率越大,杀菌效果越好。在理论分析和试验数据的基础上,建立了循环水紫外线杀菌系统的模型,并得到了粪大肠菌群的一价失活系数为0.0062?m2/J。对失活速率常数较小的菌群,增大紫外灯功率杀灭效果较好,而增加日循环次数杀灭效果提高不明显。该研究的结果可为循环水系统紫外线杀菌系统的设计和运行提供依据。     

Effects of UV-B filtration on the chemistry and decomposition of Fraxinus excelsior leaves

Several studies have demonstrated a range of effects of outdoor UV-B supplementation during the growing season on leaf chemistry including carbohydrate extractability and on the subsequent decomposition of leaf litter. However, this study investigates the effects of several levels of UV radiation on leaf carbohydrate chemistry and subsequent decomposition using filtration of ambient sunlight. Fraxinus excelsior seedlings were grown outdoors in the UK under ambient solar irradiation and under filtration treatments which excluded either UV-B or both UV-A and UV-B. After one year of decomposition in the litter layer of a mixed semi-natural woodland, the loss of dry mass was 10% greater, relative to starting mass, in the leaves which had received no UV at all or no UV-B throughout the growing season (P < 0.05). Analysis of the cell wall material before decomposition revealed no significant trends in total carbohydrate and lignin content with UV exclusions, no change in foliar nitrogen and C-to-N ratio and a 2% increase in foliar carbon (P < 0.05) only with the combined exclusion of UV-A and UV-B. A sequential extraction of carbohydrate with a series of extractants (phosphate buffer, ammonium oxalate, urea, sodium hydroxide and formic acid) showed no trends with UV exclusions but digestion with the fungal enzyme mixture Driselase revealed that exclusion of UV-B only caused rhamnose and mannose residues of the cell-wall polysaccharides to resist Driselase digestion whist exclusion of all UV had the opposite effect. Whereas some studies have reported that elevated UV-B radiation from lamp supplementation can increase rates of subsequent leaf decomposition, the higher UV-B levels in the ambient controls of this filtration study resulted in 29% lower decomposition rates than the filtered-UV treatments.     

Long-term global earth surface ultraviolet radiation exposure derived from ISCCP and TOMS satellite measurements

A long-term (1983–2000) global dataset of Earth’s surface daily-integrated UV exposure was developed from a combination of ISCCP-D1 3 h reflectance measurements (in order to resolve the diurnal variation of cloud conditions) and TOMS total ozone amount. The inversion algorithm developed in our previous study was employed with modifications addressing the conversion of visible reflectance to UV albedo and narrowband UV albedo to broadband albedo over the range of 280–400 nm. Validation of the product was carried out using ground-based measurements at six stations. In general, good agreements between the estimated and measured daily UV exposure are found at most stations; the relative mean and root mean square (RMS) difference varies from 3 to 14% and from 20 to 45%, respectively. Among the stations, San Diego has a fairly low mean difference (9%) and the lowest RMS difference (33%), owing to the prevailing clear sky or uniform cloud cover condition. The RMS difference increases with cloud amount, which is largely caused by mismatch between satellite and ground-based measurements. The effect of diurnal variation in atmospheric opacity associated primarily with cloud on the estimation of daily erythemal UV doses is investigated with both ground-based measurements and ISCCP-D1 data. It is found that daily erythemal UV doses estimated from only a noontime satellite “snapshot” may incur errors larger than 20%, which may be reduced for long-term averaging.     

A comparison of methods for measuring phytotoxicity from foliar sprays of ammonium nitrate

In a series of experiments, plants of Salvia splendens ’St. John's Fire’ were sprayed to run‐off with NH₄NO₃ solutions that varied from 0.10–1.87 M (0.8–15.0% NH₄NO₃). Damage to young fully expanded leaves was determined by measuring percent visually estimated necrosis, leakage of UV (264 nm) absorbing constituents, K, Ca and phosphate, and post‐treatment dry weight:fresh weight ratio. The average correlation coefficient of percent visually estimated necrosis was 0.992 with leakage of UV absorbing constituents, 0.956 with leakage of phosphate, 0.951 with dry weightfresh weight ratio, 0.919 with leakage of Ca and 0.741 with leakage of K. Leakage of UV absorbing constituents consistently provided the best correlation with the visual degree of leaf burn.     

Stabilization of Lipids in a Biodegradable Zein‐Oleate Film by Incorporation of Antioxidants

Zein has been studied extensively for use as an edible, biodegradable food film. To function as such, as much as 40–50% oleic acid is added as a plasticizing agent. Over the course of time, these films became discolored and developed off‐odors. It was speculated that this was due to oxidation of incorporated oleic acid. This study sought to reduce oxidative changes in film lipids by incorporation of antioxidants. Incorporation of 4,000 ppm of BHA into the films eliminated peroxide formation during accelerated UV storage conditions. Gas chromatography and headspace (GC‐HS) chromatography revealed that total volatile components of UV‐treated control films were 9× higher than fresh control volatiles. Comparison of the profiles led to the demonstration of major differences in peaks of a specific region, suggesting the presence of oxidation products in that region. Differences in UV‐treated BHA films and UV‐treated control films appeared in the same specific region of the chromatogram. Solid‐phase microextraction analysis of volatile components of the various film components and films also demonstrated a major increase in peaks associated with oxidation due to UV treatment and reduction of oxidative products in UV‐treated BHA films. Antioxidant treatment was thus found to protect the films against oxidative deterioration.     

Photodegradation of Sulfamethoxazole Applying UV- and VUV-Based Processes

The efficiency of UV- and VUV-based processes (UV, VUV, UV/H₂O₂, and VUV/H₂O₂) for removal of sulfamethoxazole (SMX) in Milli-Q water and sewage treatment plant (STP) effluent was investigated at 20??C. The investigated factors included initial pH, variety of inorganic anions (NO ₃ ^? and HCO ₃ ^? ), and humic acid (HA). The results showed that the degradation of SMX in Milli-Q water at both two pH (5.5 and 7.0) followed the order of VUV/H₂O₂ > VUV > UV/H₂O₂ > UV. All the experimental data well fitted the pseudo-first order kinetic model and the rate constant (k) and half-life time (t _1/2) were determined accordingly. Indirect oxidation of SMX by generated ^?OH was the main degradation mechanism in UV/H₂O₂ and VUV/H₂O₂, while direct photolysis predominated in UV processes. The quenching tests showed that some other reactive species along with ^?OH radicals were responsible to the SMX degradation under VUV process. The addition of 20?mg?L^?1 HA significantly inhibited SMX degradation, whereas, the inhibitive effects of NO ₃ ^? and HCO ₃ ^? (0.1?mol?L^?1) were observed as well in all processes except in UV irradiation for NO ₃ ^? . The removal rate decreased 1.7?C3.6 times when applying these processes to STP effluent due to the complex constituents, suggesting that from the application point of view the constituents of these complexes in real STP effluent should be considered carefully prior to the use of UV-based processes for SMX degradation.     

New technique for rose production in soilless culture system and disease reduction

Rose flower is one of the most important cut flowers, with the world's highest production rate. Soilless culture has been increasingly popular in plant production worldwide in the past few decades. In two separate trials, the efficacy of Trichoderma harzianum, Anearobacillus migululanas, slow filtration, and UV ultraviolet (UV) treatment and sand filtration in eliminating Fusarium oxyporum, artificially added in the recirculating nutrient solution, was evaluated with Rosea hybrid plants grown in closed soilless systems. The dynamics of these fungi in the recirculating nutrient solution and in the sand filter was also investigated. T. harzianum, A. migululanas, UV treatment and slow sand filtration were effective in reducing Fusarium root rot. However, slow sand filtration may be a more feasible disinfection method than UV because of lower costs of installation and maintenance and for its adaptability to a wide range of production systems. Moreover, these disinfection techniques can be successfully combined with the application of antagonistic microorganisms.