Seasonal and Diurnal Concentrations of Ambient Formaldehyde and Acetaldehyde in Bangkok

The concentration level of carbonyl compounds in Bangkok ambient air were measured in five roadside sites and five residential sites during July 2007 to April 2008. About 250 samples were collected and ten carbonyls were identified. Formaldehyde and acetaldehyde were the most abundant carbonyl compounds found in Bangkok ambient air. The ambient concentration of formaldehyde at the roadside areas in Bangkok during July 2007 to April 2008 ranged from 5.14 to 17.2 ??g/m³ (average 11.53 ??g/m³) while, the ambient concentrations of formaldehyde in residential areas in Bangkok during the same period ranged from 3.06 to 19.9 ??g/m³ (average 9.65 ??g/m³). The concentrations of acetaldehyde in roadside areas ranged from 1.59 to 7.95 ??g/m³ (average 3.51 ??g/m³) while at the residential areas the concentrations of acetaldehyde during the same period ranged from 1.07 to 8.05 ??g/m³ (average 3.11 ??g/m³). Other compounds showed low concentration. The concentrations of formaldehyde and acetaldehyde were low during the rainy season due to rain washout since these compounds are water soluble. The concentrations were high during the cold season due to stable conditions during these months. The concentrations slightly decreased during the summer due to photochemical reactions and photolysis under extreme temperature. Formaldehyde and acetaldehyde showed good correlation during 17:00 P.M. to 05:00 A.M. due to absence of solar radiation that may enhance photochemical reactions and mobile sources may be the sources of emission in the environment. It was also found that the concentrations of formaldehyde and acetaldehyde were low during the night time.     

Spatial and Temporal Variability in Ozone Concentration Level at Two Lithuanian Stations

The ozone concentration measurement results at two rural stations in Lithuania are presented. Ozone measurements have been carried out at the coastal site since 1980 and at the forested one since 1994. Both stations are far from the influence of the local pollution. The established ozone concentration trends at the coastal station were upward in cold and not so distinct in warm seasons during this monitoring time. The tendency even of a decreasing level in some summer months was established: in June and August. These trend results were very close to the results obtained at other European stations. Comparing ozone levels and courses at both stations, significant differences were determined. Clear differences between monthly daytime and daily ozone concentration averages are observed during the warm season. They were three times larger at a forest site as compared with the results at a coastal one.     

Phlorotannins from brown algae (Fucus vesiculosus) inhibited the formation of advanced glycation endproducts by scavenging reactive carbonyls

Accumulation of advanced glycation end products (AGEs) in vivo is associated with aging, diabetes, Alzheimer's disease, renal failure, etc. The objective of this study was to investigate the inhibitory effects of brown algae Fucus vesiculosus phlorotannins on the formation of AGEs. F. vesiculosus phlorotannins were extracted using 70% acetone. The resultant extract was fractionated into dichloromethane, ethyl acetate, butanol, and water fractions. The ethyl acetate fraction was further fractionated into four subfractions (Ethyl-F1 to -F4) using a Sephadex LH-20 column. F. vesiculosus acetone extract or fractions significantly inhibited the formation of AGEs mediated by glucose and methylglyoxal in a concentration-dependent manner. The concentrations of F. vesiculosus extracts required to inhibit 50% of albumin glycation (EC(50)) in the bovine serum albumin (BSA)-methylglyoxal assay were lower than those of aminoguanidine (a drug candidate for diabetic complication), except for F. vesiculosus acetone extract and dichloromethane fraction. In the BSA-glucose assay, F. vesiculosus extracts inhibited BSA glycation more than or as effectively as aminoguanidine, except for Ethyl-F3 and -F4. The ethyl acetate fraction and its four subfractions scavenged more than 50% of methylglyoxal in two hours. The hypothesis whether F. vesiculosus phlorotannins scavenged reactive carbonyls by forming adducts was tested. Phloroglucinol, the constituent unit of phlorotannins, reacted with glyoxal and methylglyoxal. Five phloroglucinol-carbonyl adducts were detected and tentatively identified using HPLC-ESI-MS(n).     

Inhibition of lipid oxidation in pork bundles processing by superheated steam frying

The effect of superheated steam treatment on the oxidative stability of lipids in packaged Zousoon (pork bundles) was investigated. The aroma quality of Zousoon samples was evaluated by sensory analysis and chromatographic analysis of volatiles. Results of this study indicated that oxidation of lipids occurred in pan-fried Zousoon after prolonged storage. Significant amounts of highly volatile compounds such as formaldehyde, acetaldehyde, acetone, and hexanal in Zousoon were identified by a modified method of cysteamine derivatization followed by gas chromatography-mass spectrometry (GC-MS) analysis. Superheated steam was found to be effective in suppressing lipid oxidation in canned Zousoon as compared with Zousoon fried by the conventional method in a frying pan. The superheated steam-fried samples had relatively low thiobarbituric acid reactive substance (TBARS) and peroxide (POV) values before and after storage, whereas samples prepared by pan frying had relatively high TBARS and POV values before and after storage. Superheated steam-fried Zousoon had superior lipid stability to that prepared by the conventional pan-frying method.     

Growth and Leaf Gas Exchange in Three Birch Species Exposed to Elevated Ozone and CO2 in Summer

We examined the effects of ozone and elevated CO₂ concentration in summer on the growth and photosynthetic traits of three representative birch species in Japan (mountain birch, Monarch birch, and white birch). Seedlings of the three birch species were grown in 16 open-top chambers and were exposed to two levels of ozone (6 and 60?nmol?mol^?1 for 7?h per day) in combination with two levels of CO₂ (370?C380 and 600???mol?mol^?1 for daytime) from July to October. No adverse effects of ozone were found in the Monarch birch or the white birch, but elevated ozone in summer reduced branch biomass and net photosynthesis, and accelerated leaf abscission, in the mountain birch. Elevated CO₂ promoted root development and thereby reduced the ratio of shoot dry mass (stem + branch) to root dry mass (S/R ratio) in the mountain birch and white birch. In contrast, there was no difference in dry mass between ambient and elevated CO₂ for the Monarch birch, due to downregulation of photosynthesis. Studies of the combined effect of CO₂ and ozone revealed that elevated CO₂ did not ameliorate the effect of ozone on mountain birch in late summer. In considering the ameliorating effect of CO₂ on ozone damage, it is necessary to take account of the species and the season.     

The Promoter of the Tnt1A Retrotransposon: A Biomarker to Monitor Ozone but not Formaldehyde and Benzene Pollution

Open top chambers (OTCs) are useful tools to assess the impact of atmospheric pollutants on plants in the natural environment. We have previously reported that, in tomato plants, the LTR-GUS construct derived from the Tnt1A promoter of tobacco was activated by a realistic level of ozone pollution. In this study, we used OTCs to fumigate tomato plants with benzene or formaldehyde in order to assess the impact of these pollutants on plant growth and development and evaluate the usefulness of the LTR-GUS construct as a biomarker in plants. Whereas the LTR-GUS construct could be used as an efficient biomarker of realistic levels of ozone pollution, it is to a lesser extent applicable to formaldehyde. Indeed, only unrealistic concentration of pollutant activated the construct though important injuries were observed at a lower concentration. For benzene, no activation could be demonstrated, however, we did not notice any visual impact on plant growth and health for this pollutant.     

Formation of carcinogenic 4(5)-methylimidazole in Maillard reaction systems

4(5)-Methylimidazole has received the attention of federal and state regulatory agencies because of its carcinogenicity and common presence in foods and beverages. In the present study, the formation of 4(5)-methylimidazole in Maillard reaction model systems consisting of D-glucose/NH(3), L-rhamnose/NH(3), methylglyoxal/NH(3), and methylglyoxal/formaldehyde/NH(3) was investigated. 4(5)-Methylimidazole was formed at levels ranging from 0.49 to 0.71 mg/mL in the d-glucose/NH(3) model system. The formation of 4(5)-methylimidazole was slightly higher in the L-rhamnose/NH(3) system (0.91 mg/mL) than in the d-glucose/NH(3) system (0.71 mg/mL) under the conditions used in the present study. A methylglyoxal/NH(3) system produced significantly higher levels of 4(5)-methylimidazole (5.70 mg/mL), suggesting that methylglyoxal is an important precursor of 4(5)-methylimidazole. Ammonolysis of methylglyoxal, which is one of the glucose degradation products, was proposed to form formamide, which subsequently reacted with 2-aminopropanal (α-aminocarbonyl intermediate) formed from methylglyoxal to give 4- or 5-methylimidazole. The levels of 4(5)-methylimidazole found in commercial cola soft drinks range from 0.30 μg/mL (brand 3) to 0.36 μg/mL (brands 1 and 5).     

Influence of heating time and metal ions on the amount of free fatty acids and formation rates of selected carbonyl compounds during the thermal oxidation of canola oil

Canola oil was heated continuously for 8 h at a typical frying temperature (180 °C) in the presence of various concentrations of the metal ions Fe(III), Cu(II), and Al(III) (9.2, 27.5, and 46.0 μg L(-1) of oil) to evaluate changes occurring in the amount of free fatty acids, expressed as acidity index, and in the formation rates of aldehydes. The aldehydes were collected and derivatized in silica cartridges functionalized with C18 and impregnated with an acid solution of 2,4-dinitrophenylhydrazine, after which they were eluted with acetonitrile and analyzed by LC-DAD-MS. Among the substances emitted, the following were identified and quantified: formaldehyde, acetaldehyde, acrolein, propanal, butanal, hexanal, (E)-2-heptenal, and octanal. During heating of the oil, the compounds presenting the highest mean formation rates were acrolein, hexanal, and acetaldehyde. In the study of the metal ions, the addition of ions to the samples generally led to a corresponding increase in the formation rates of the eight substances. The compounds showing the highest relative increases in formation rates were formaldehyde, acetaldehyde, propanal, and heptenal. In terms of catalytic effect, copper proved to be the most efficient in promoting increased formation rates, followed by iron and aluminum.     

Formation and Emission of Chlorinated by-Products from a Bench-Scale Packed-Bed Odor Scrubber

The phenomenon of chlorinated byproduct formation and their possible emission from odor control systems employing chlorine scrubbing solutions was evaluated. Experiments with hypochlorite scrubbing solution were performed with a bench-scale, single-stage, packed-bed odor scrubber to explore the potential for generating toxic air contaminants (TACs) such as chloroform in full-scale operating units. Known concentrations of a mixture of volatile organic compounds (VOCs) commonly found in wastewater were introduced at realistic field concentrations in an airstream to the inlet of a counter-current packed-tower operated with different scrubbing solutions. Formation of TACs was observed in the scrubbing solution under low-, neutral- and high-pH conditions. The addition of a mixture of VOCs: acetone, methylethylketone, formaldehyde and acetaldehyde, produced chloroform under neutral to high pH conditions. Under low-to neutral-pH conditions, toluene and chlorophenol produced chlorotoluenes and chlorophenols as reaction byproducts. Under the bench-scale unit’s operating conditions, trace levels of the reaction byproducts formed were stripped from the re-circulated scrubber solution into the outlet gas. Based on the bench-scale observations and a quasi-steady-state, first-order reaction model applied to the scrubber reservoir and packed tower system, scrubber solution residence time in the liquid reservoir is hypothesized to be an important operating parameter affecting TAC formation in full-scale hypochlorite-based, packed-tower, odor control units.     

Analysis of major photochemical pollutants with meteorological factors for high ozone days in Istanbul, Turkey

Hourly ozone, NO _x and VOC concentrations, measured during 2001–2003 summer periods, are analyzed in order to examine the interaction patterns between the major photochemical pollutants in ?stanbul. 34 high ozone days throughout the summer periods of the three years are determined and examined in the study together with the meteorological parameters like temperature, wind and vertical structure of the atmosphere. The results show that high levels of ozone are observed mostly under anticyclonic conditions with relatively low wind speeds. High ozone days generally experienced maximum concentrations at afternoon hours and minimum concentrations are reached at rush hours due to NO _x – titration by traffic emissions. High negative correlations with NO _x up to -0.84 are observed at the Saraçhane station while higher correlations for VOC species, up to ?0.75, are calculated for Kadiköy station. Some individual episodes experiencing high ozone concentrations up to 310 μg m^?3 in the early morning hours are also studied. It is found that decreasing inversion heights in the early hours of the day led to suppression of pollutants close to surface and thus, an increase in ozone concentrations was observed. Low wind speeds played a major role in the increase of pollution levels in the region. HYSPLIT model is applied to some particular episodes and the results show that the northeasterly transport to the region was dominant, especially in the early-morning maximums.     

Voltammetric assay for the aging of beer

A new method for the evaluation of beer aging, based on a voltammetric analysis of beer distillates, is described. By measuring the current of both acetaldehyde and sulfite voltammetric peaks it is possible to distinguish between fresh, naturally aged, and artificially aged beers. The results obtained for the ratio of acetaldehyde and SO(2) currents correlate well with those given by an expert sensory panel. The kinetics of the combining reaction of sulfite with acetaldehyde was followed for different acetaldehyde/SO(2) molar ratios by using a programmed voltammetric procedure. The formation of an acetaldehyde-sulfite adduct is rapid, and the reaction equilibrium is reached after 30 min, which is in accordance with the results previously obtained by other methods. This voltammetric-based approach seems to be a new attractive tool for detecting chemical equilibria of the addition of sulfite to carbonyls in beer model systems.     

Characterization of volatile compounds in chilled cod (Gadus morhua) fillets by gas chromatography and detection of quality indicators by an electronic nose

Volatile compounds in cod fillets packed in Styrofoam boxes were analyzed during chilled storage (0.5 degrees C) by gas chromatography (GC)-mass spectrometry and GC-olfactometry to screen potential quality indicators present in concentrations high enough for detection by an electronic nose. Photobacterium phosphoreum dominated the spoilage bacteria on day 12 when the fillets were rejected by sensory analysis. Ketones, mainly 3-hydroxy-2-butanone, were detected in the highest level (33%) at sensory rejection, followed by amines (TMA) (29%), alcohols (15%), acids (4%), aldehydes (3%), and a low level of esters (<1%). The electronic nose's CO sensor showed an increasing response with storage time coinciding with the production of ethanol and 2-methyl-1-propanol that were produced early in the storage, followed by the production of 3-methyl-1-butanol, 3-methyl-butanal, 2,3-butandiol, and ethyl acetate. Lipid-derived aldehydes, like hexanal and decanal, were detected in similar levels throughout the storage time and contributed to the overall sweet odors of cod fillets in combination with other carbonyls (3-hydroxy-2-butanone, acetaldehyde, 2-butanone, 3-pentanone, and 6-methyl-5-heptene-2-one).     

直接低温等离子体技术降低柴油机醛酮类污染物排放

为了研究直接低温等离子体（DNTP）技术去除柴油机排气中醛、酮类污染物的效率,采用2,4-二硝基苯肼（DNPH）衍生法和高效液相色谱（HPLC）分析技术,分析了柴油机4种工况原机和DNTP技术处理后醛、酮类污染物比排放量的变化规律。结果表明,DNTP处理前,醛、酮类污染物比排放量随负荷的增加呈先减少后增加的趋势;DNTP处理后,柴油机醛、酮类污染物比排放量显著降低,醛、酮类污染物在75%负荷时的总去除率可达93.8%,25%负荷、50%负荷、75%负荷时,丙烯醛和丙酮、丁醛和丁酮去除率达到100%。     

Determination of methylglyoxal in ruminal fluid by high-performance liquid chromatography using fluorometric detection

There is no reported method for the quantification of methylglyoxal in ruminal fluid. The method reported here is based on the conversion of methylglyoxal to 6-methylpterin, followed by quantification of the resulting pteridinic compound by fluormetric detection using liquid chromatography. Ruminal fluid was collected and preserved with 1 M HCl at -20 degrees C. Cation exchange prior to derivatization was used to eliminate possible interfering peaks. The detection limit of 0.125 microg/mL was calculated. The recoveries were >80%, and the coefficients of variation were <15%. This method has proven to be rugged and accurate for the detection of methylglyoxal concentration in ruminal fluid collected from cows fed diets deficient in degradable intake protein as a marker. Methylglyoxal is produced by ruminal bacteria in response to low nitrogen levels in the rumen. The ruminal methylglyoxal concentration has the potential to be a useful marker to assess ruminal nitrogen status to aid in more accurate diet formulation.     

Clover Sweden — A national three-year study of the effects of tropospheric ozone on Trifolium subterraneum,L.

In 1992 a cooperative project, Clover Sweden, was initiated. The aim was to study if subterranean clover could be used as a bioindicator in the different climate zones in Sweden by studying the impact of ambient ozone concentrations on this species in different parts of the country during three consecutive summer seasons. Plants of subterranean clover, Trifolium subterraneum, L., were exposed to ambient air at 24 sites from north to south Sweden. The project was designed to be compatible with the international programme, ICP Crops within the UNECE and the Convention on Long Range Transboundary Air Pollution. The results showed that subterranean clover is a useful bioindicator of ozone in all agricultural areas of Sweden, with the exception for very cool and rainy summers resulting in poor growth of the plants. In 1992, and especially in 1994, ozone injury was detected at almost all sites in Sweden, reflecting the higher ozone levels of those summers as compared to 1993, when ozone concentrations were generally low and not much injury was detected. Typical injury was chlorotic and bifacial necrotic lesions on parts of the leaf surface. It is concluded that at mean ozone concentrations of 25 ppb (24 h mean) and 30 ppb (7 h mean) there is a potential risk for injury on 10% of the leaves. When % injured leaves was plotted against AOT (Accumulated exposure Over a Threshold) using different thresholds, it became obvious that a threshold of 20 ppb ozone should be used in order to fully protect from leaf injury under Swedish conditions.     

The Effects of Acid Precipitation and Ozone on the Ectomycorrhizae of Red Spruce Saplings

The effects of acid precipitation and ozone on the composition of the ectomycorrhizal community of red spruce saplings were evaluated. In 1986, saplings were excavated from a site in Maine that had been clear-cut in 1979. Saplings were then potted in native soil and transported to Ithaca, New York. With the exception of an ambient control treatment, trees were grown in open-top chambers. Saplings were exposed to five levels of ozone and three levels of acid precipitation beginning in July 1987. Ectomycorrhizae were sampled in 1988 and 1991 after one and four years of treatment, respectively. Although the percentage of root tips infected by ectomycorrhizal fungi was not affected by treatments, a shift in the composition of the ectomycorrhizal community occurred in response to acid precipitation treatments for both sampling years. Among the seven ectomycorrhizal morphotypes identified, the percent composition of one morphotype increased and another decreased in response to higher rain acidity. Alone, ozone treatments did not influence ectomycorrhizal composition; however, a significant interactive response to ozone and acid precipitation was observed in the organic soil horizon in 1988. Such shifts in the composition of the ectomycorrhizal community may indicate that the experimental trees were stressed by pollution treatments.     

Formaldehyde Concentrations in Ambient Air in Urban and Rural Areas in Gunma Prefecture, Japan

We measured formaldehyde concentrations in ambient air at urban (Isesaki) and rural (Annaka) sites in Gunma Prefecture, Japan from June 1998 to March 2003. Measurements were carried out once in a month to obtain daily mean formaldehyde concentrations. At both the sites, mean concentrations of formaldehyde were significantly higher from April to September (summer) than from October to March (winter). Formaldehyde concentrations in Annaka were essentially as high as those in Isesaki in summer, but were significantly lower in winter. At both the sites, concentrations of formaldehyde and oxidants correlated significantly with one another in the summer; correlation coefficients in Annaka and Isesaki were 0.82 and 0.64, respectively. The fraction of formaldehyde formed photochemically based on concentrations of benzene was calculated to be as high as 80% in both the sites in summer. The results suggested that formaldehyde concentrations were high even in rural air, reflecting photochemical reactions rather than automobile exhaust.     

温带针阔混交林内温度和水汽压垂直梯度变化特征

应用长白山针阔混交林2003-2005年空气温度和水汽压梯度观测资料,以4、7、10和1月分别代表春、夏、秋和冬季,分析不同季节典型晴天条件下林内气温、水汽压的垂直分布规律及其日变化特征,以冠层顶部的气温和水汽压为本底值构建林内气温和水汽压随观测高度变化的廓线函数,分析其变化特征。结果表明：(1)林内各观测高度的气温均具有单峰曲线形式的日变化特征,最高值出现在15：00左右,最低值出现在日出前,林内各高度气温日较差以秋季最大,冬季最小,各季气温日较差均随高度的增加而减小;(2)在春、秋和冬季,林内气温表现出随高度增加而升高的趋势,且具有明显的日变化规律,在正午前后林内气温的垂直梯度较小,甚至表现出气温随高度增加而减小的趋势,而其它时刻林内气温的垂直梯度较大,在夏季,各个时刻林内气温均随观测高度的增加而升高;(3)不同季节林内水汽压的日变化特征不同,春、秋和冬季各观测高度水汽压皆呈单峰曲线的分布规律,而夏季则呈双峰曲线形式的日变化规律;(4)同一时刻不同季节林内水汽压垂直分布规律存在显著差异,而同一季节不同时刻的水汽压垂直分布廓线形状相似,夏季林内水汽压随观测高度增加而降低的规律明显,其它季节水汽压的垂直梯度则较小;(5)林内气温和水汽压垂直分布廓线均近似满足对数曲线规律。     

近44年吉首市气温变化统计分析

根据吉首市1960-2003年的气温资料,利用最小二乘法作线性估计,分析气温变化趋势及其差异.结果表明：44年来,除7月平均气温、平均最高气温呈下降趋势外,其余各项均呈上升趋势,以冬季平均气温上升幅度最大,冬暖夏凉趋势明显;20世纪60年代前期至70年代中后期为＂冷期＂,90年代初为＂暖期＂,冷期中有暖变化,暖期中有冷波动.气温变化条件下吉首市农业生产应采取相应的对策.     

Passive Ozone Monitoring for Forest Health Assessment

Critical levels of tropospheric ozone, established for the protection of crops and other plants, are now reported as being exceeded over large forested areas, giving rise to the need for an extensive monitoring program to confirm ambient levels within the forest and to detect related forest health effects. The requirement for an inexpensive monitor that can be used in remote locations prompted the development of the Can Oxy Plate^TM passive ozone monitor and a monitoring protocol by the air pollution research group of the Canadian Forest Service, Forest Health Network. The monitors underwent initial trials in 1996 and operational trials during 1997 that involved two 2-3 week mid summer exposures in the canopy at selected forest health monitoring plots across Canada, and at adjacent forest openings. In both trials monitors were also co-located with the nearest instrumental ozone monitor. This allowed for the production of a field calibration for quality assurance assessment under field conditions. Results from 1996 indicate highly significant correlations with accumulated ambient ozone concentrations from the instrumental monitors at the co-located sites (r=0.88, p=0.0002). However, no such relationship was found between these sites and the forest plots which were up to 200 kilometres away. This may indicate spatial heterogeneity in ozone exposure between the continuous air quality monitoring sites and the forest plots. This information, together with our knowledge that strong gradients of ozone exposure are found within the canopy, underlines the importance of in situ monitoring of ozone exposure of forest health plots at risk to ozone effects.