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PubMed1994

Influence of the atmospheric conductivity on the ozone exposure of plants under ambient conditions: Considerations for establishing ozone standards to protect vegetation.

This paper provides results of ozone flux density measurements above a permanent grassland ecosystem as they relate to an establishment of air quality guidelines or standards. Using a resistance analogue, the product of zone concentration measured at a standard measurement height and the conductivity of the atmosphere reflect the maximum possible ozone flux density towards the envelope of the plants. In other words, this product can be regarded as the ozone exposure potential of the atmosphere for plants. It could be shown that ozone concentrations between 100 and 180 microg m(-3) are likely to have a great phytotoxic potential and are more important than concentrations greater than 180 microg m(-3). From the results presented one can deduce that the application of dose-response relationships based on chamber experiments to ambient conditions results in an overestimation of, for example, yield loses. Any guideline or standard has to take into account the influence of the atmospheric conductivity on the absorbed dose of ozone.

Journal Article↗
PubMed1996

Nitrate reductase activity as an indicator of ponderosa pine response to atmospheric nitrogen deposition in the San Bernardino Mountains.

Determinations of nitrate reductase (NR) activity in ponderosa pine (Pinus ponderosa Dougl. ex. Laws.) needles were performed during summer 1994 in two areas (consisting of six different sites) with different nitrogen (N) deposition levels in the San Bernardino Mountains, southern California. Nitrate reductase activity was used as an integrative indicator of atmospheric nitrogen deposition to pine trees (direct uptake of N species from the atmosphere and N transported from the soil). Deposition of nitrate (NO3-) to pine branches was measured in order to determine dry atmospheric inputs of the oxidized N species to tree foliage. High NR activity was detected in all of the experimental sites. Activity of the enzyme was significantly higher at the locations characterized by higher NO3- deposition to branches--slight positive correlation between branch deposited NO3- and NR activity was found. However, high variability of NR in time and between the experimental sites discredit the NR assay as a reliable indicator of N deposition for ponderosa pine in the field conditions. This could be caused by substantial interference from other abiotic and biotic factors with tropospheric ozone as probably the most important one.

Journal Article↗
PubMed2005

Atmospheric dynamics in the "Laboratory Biosphere" with wheat and sweet potato crops.

Laboratory Biosphere is a 40-m3 closed life system equipped with 12,000 W of high pressure sodium lamps over planting beds with 5.37 m2 of soil. Atmospheric composition changes due to photosynthetic fixation of carbon dioxide and corresponding production of oxygen or the reverse, respiration, are observed in short timeframes, e.g., hourly. To focus on inherent characteristics of the crop as distinct from its area or the volume of the chamber, we report fixation and respiration rates in mmol h-1 m-2 of planted area. An 85-day crop of USU Apogee wheat under a 16-h lighted/8-h dark regime peaked in fixation rate at about 100 mmol h-1 m-2 approximately 24 days after planting. Light intensity was about 840 micromoles m-2 s-1. Dark respiration peaked at about 31 mmol h-1 m-2 at the same time. Thereafter, both fixation and respiration declined toward zero as harvest time approached. A residual soil respiration rate of about 1.9 mmol h-1 m-2 was observed in the dark closed chamber for 100 days after the harvest. A 126-day crop of Tuskegee TU-82-155 sweet potato behaved quite differently. Under a 680 micromoles m-2 s-1, 18-h lighted/6-h dark regime, fixation during lighted hours rose to a plateau ranging from about 27 to 48 mmol h-1 m-2 after 42 days and dark respiration settled into a range of 12-23 mmol h-1 m-2. These rates continued unabated until the harvest at 126 days, suggesting that tuber biomass production might have continued at about the same rate for some time beyond the harvest time that was exercised in this experiment. In both experiments CO2 levels were allowed to range widely from a few hundred to about 3000 ppm, which permitted observation of fixation rates both at varying CO2 concentrations and at each number of days after planting. This enables plotting the fixation rate as a function of both variables. Understanding the atmospheric dynamics of individual crops will be essential for design and atmospheric management of more complex CELSS which integrate the simultaneous growth of several crops as in a sustainable remote life support system.

Biomass↗
PubMed2004

High abundance of gaseous and particulate 4-oxopentanal in the forestal atmosphere.

Atmospheric concentrations of 4-oxopentanal (4-OPA) in both gas and particulate phase were measured at the experimental forest, 200 km north of Sapporo, Japan, from August 13 to 15, 2001. 4-OPA was collected using an annular denuder sampling system and measured with a gas chromatography employing benzylhydroxyl oxime derivatization. Its gas phase concentrations ranged from 180 ng m(-3) (44 pptv) to 1570 ng m(-3) (384 pptv), whereas those in the particulate phase were from below the detection limit (25 ng m(-3)) to 207 ng m(-3). The particulate 4-OPA accounted for 28% (particle/(gas+particle)) of the total concentration as the maximum at 06:00 on August 15th (average: 10%). The particulate concentrations of 4-OPA were found to be comparable to those of pinonic acid, indicating that 4-OPA is also an important constituent of organic aerosols in the forestal atmosphere. Here, we report, for the first time, the concentrations of 4-OPA in both gas and particulate phase and its diurnal variations in the forestal atmosphere.

Air Pollutants↗
PubMed2005

Determination of atmospheric nitrate particulate size distribution and dry deposition velocity for three distinct areas.

In this study, both atmospheric particulates and dry deposited particulates were collected at a highway intersection, coastal location and suburban area in Taichung, Taiwan for the characterization of nitrate containing particulates (NCPs) in size distribution and dynamic properties. Collected particulates were placed in contact with nitron (C20H16N4) to form distinctive products of NCPs, which were examined by a SEM. For total atmospheric particulates, the sum of NCP and non-nitrate containing particulate (NNCP), the average shape factor values are 1.69, 1.49, and 1.36 for the highway intersection, coastal area and suburban area, respectively. The calculated shape factors show no significant differences with sizes. Dry deposition fluxes and atmospheric concentrations at various size ranges were estimated. The mass distributed in fine particle range (<or=2.5 microm) were 45%, 40%, and 43% for NCP at the highway intersection, coastal, and suburban areas, respectively. The average dry deposition velocities (Vds) of total particulate are 2.5, 1.5, and 1.2 cm s(-1) for highway intersection, coastal area, and suburban area, respectively. The highest Vd was observed from samples taken at highway intersection, suggesting that dust resuspension and particulates from vehicles in the ambient air is of great significance. The Vds of total particulates range over three orders of magnitude for size ranges from 0.32 to 18 microm. The value of Vd increases with the diameter of particles significantly.

Air Movements↗
PubMed2005

Composition of torched crude oil organic particulate emitted by refinery and its similarity to atmospheric aerosol in the surrounding area.

The absolute contents and relative distributions of organic aerosols [n-alkanes, n-alkanoic and n-alkenoic acids, n-alkan-2-ones and polycyclic aromatic hydrocarbons (PAH)] were determined in torched gases emitted during the crude oil extraction and in the free atmosphere of the Hassi-Messaoud city (Algeria). Monocarboxylic acids, both saturated and monounsaturated (from 9802 to 20,057 ng m(-3)), accounted for the major fraction of the total particulate organic matter identified both in torch exhaust and atmospheric particulate. n-Alkanes were also abundant both in the direct emission (from 460 to 632 ng m(-3)) and city atmosphere (462 ng m(-3)) and displayed a peculiar fingerprint characterised by the presence of a set of branched congeners around even carbon-numbered homologues and a strong even-to-odd predominance along the whole carbon number range (C16-C34). Whilst n-alkan-2-ones were absent in the city and poor in smokes emitted from the torches (from 31 to 42 ng m(-3)), PAH were present at low extents in all sites (from 18 to 65 ng m(-3)). The incomplete thermal combustion of torched crude oil was very likely the main source of these particle-bound organic constituents in the city and its surrounding region.

Air Pollutants↗
PubMed2005

Decrease of atmospheric deposition of heavy metals in an urban area from 1994 to 2002 (Paris, France).

Total atmospheric deposition, i.e. both wet and dry ones, was sampled during three different sampling periods between 1994 and 2002. The aim of this study is to determine the temporal variation of the atmospheric deposition fluxes of four heavy metals (Cd, Cu, Pb and Zn) in an urban area (Paris region, France). The global pattern shows a decrease of the fluxes for most of elements during this period. Indeed, the atmospheric deposition fluxes measured in 2001-2002 were lower than those measured during the 1994-1997 period by factors reaching 16, 2.5, 4 and 7.5 at Créteil and 7, 1, 6 and 4.5 at Chatou for Cd, Cu, Pb and Zn, respectively. At the Paris site, the decreasing factors were 2.5 and 3 for Cd and Pb, respectively while Cu and Zn fluxes were nearly similar during the whole studied period.

Air Pollutants↗
PubMed2006

Characterization of atmospheric dry deposition particulates in Kobe, Japan.

The sources and character of individual metal and metalloid particles from atmospheric dry depositions in Kobe, Japan were investigated. Japan faces long-range pollutant transportation from northeastern Asia during winter and spring. Information regarding their properties and sources is useful for evaluating their affects on the environment and human health. Individual metal and metalloid particles that were collected for every 24 h on the plate, which was designed to reduce a local turbulence, were characterized for their composition, diameter, and deposition fluxes using a field emission scanning electron microscope with an energy dispersive X-ray spectrometer. Approximately 3,000 metal and metalloid particles were classified into 14 types based on their composition and further classified into four groups based on their distribution patterns. They are (A) Fe-O, Fe-Ba-Sb-Cu-S-Ti-O, Fe-Zn-O, Zn-O, Ni-O, and Mn-Fe-O; (B) Cu-Zn-O and Cu-Sn-O; (C) Pb-O, Sn-Sb-O, and Ag-O; (D) Pb-Zn-Cl-Si-S-O and Bi-Cl-O. From these data, this study suggests their sources as the Asian continent (Group A), local source (Group B), multiple sources (Group C), and incineration process (Group D). This study shows (1) the sources and character of individual metal and metalloid particles from short-term atmospheric depositions in Kobe, Japan and (2) application of individual particle analysis for atmospheric depositions.

Air Pollutants↗
PubMed2006

Atmospheric deposition of polybrominated diphenyl ethers (PBDEs) in coastal areas in Korea.

Atmospheric bulk samples were collected monthly, for one year, from urban, suburban, and rural sites located in the coastal areas of Korea, for the assessment of depositional fluxes and seasonal variations in atmospheric concentrations of PBDEs. Twenty individual PBDE congeners were found in atmospheric samples, and their depositional fluxes varied from 10.1 to 89.0 microg/m2/year. The highest depositional fluxes were found in two urbanized areas, with a strong urban-rural gradient. The relationship between PBDE and particulate depositional fluxes showed significant correlation for all locations, which suggested the association of PBDEs to particulate phase. Deca-BDE (BDE 209) was the predominant congener (>93%) in all deposition samples, which is consistent with a high consumption of deca-BDE for the flame-retardant market in Korea. Seasonal variability was observed in PBDE concentrations for the two urban sites, whereas no seasonal trend was found for either the suburban or the rural location.

Air Pollutants↗
PubMed2005

[In vivo spetrometric analysis of the electrical impedance of the first leaf of maize (Zea mays L.) as a function of soil and atmosphere hydrous conditions].

In vivo spectrometric analysis of the electrical impedance of the first leaf of maize (Zea mays L.) as a function of soil and atmosphere hydrous conditions. We have measured the electrical resistance and capacitance of the first leaf of maize aged 14 days. The plants were cultivated at different levels of soil and atmospheric humidity and submitted to quiet or agitated air. In 'control' plants cultivated in quiet air under moderate relative humidity (HRA) (50 to 60%), the amplitude of the spectrometric bioimpedance spectrum (CSB) increased with the quantity of water available to the roots. Agitated air or elevated HRA increased the magnitude of the CSB in plants cultivated at 40% of the maximal retention capacity (CRM) of the soil. On the other hand, the CSB decreased in plants cultivated at 60% of the CRM or in hydroponics. This was accompanied by a dramatic decrease in the electrical resistance. The action of the atmospheric factors studied depends on the quantity of water where the roots are bathing.

Air↗
PubMed2005

Atmospheric polycyclic aromatic hydrocarbons (PAHs) in Asia: a review from 1999 to 2004.

Polycyclic aromatic hydrocarbons (PAHs) are present in both gaseous and particulate phases. These compounds are considered to be atmospheric contaminants and are human carcinogens. Many studies have monitored atmospheric particulate and gaseous phases of PAH in Asia over the past 5 years. This work compares and discusses different sample collection, pretreatment and analytical methods. The main PAH sources are traffic exhausts (AcPy, FL, Flu, PA, Pyr, CHR, BeP) and industrial emissions (BaP, BaA, PER, BeP, COR, CYC). PAH concentrations are highest in areas of traffic, followed by the urban sites, and lowest in rural sites. Meteorological conditions, such as temperature, wind speed and humidity, strongly affect PAH concentrations at all sampling sites. This work elucidates the characteristics, sources and distribution, and the healthy impacts of atmospheric PAH species in Asia.

Air Pollutants↗
PubMed2006

Active carbon-pools in rhizosphere of wheat (Triticum aestivum L.) grown under elevated atmospheric carbon dioxide concentration in a Typic Haplustept in sub-tropical India.

Study on active and labile carbon-pools can serve as a clue for soil organic carbon dynamics on exposure to elevated level of CO2. Therefore, an experimental study was conducted in a Typic Haplustept in sub-tropical semi-arid India with wheat grown in open top chambers at ambient (370 micromol mol-1) and elevated (600 micromol mol-1) concentrations of atmospheric CO2. Elevated atmospheric CO2 caused increase in yield and carbon uptake by all plant parts, and their preferential partitioning to root. Increases in fresh root weight, volume and length have also been observed. Relative contribution of medium-sized root to total root length increased at the expense of very fine roots at elevated CO2 level. All active carbon-fractions gained due to elevated atmospheric CO2 concentration, and the order followed their relative labilities. All the C-pools have recorded a significant increase over initial status, and are expected to impart short-to-medium-term effect on soil carbon sequestration.

Air Pollutants↗
PubMed2004

Atmospheric concentrations of the Cl atom, ClO radical, and HO radical in the coastal marine boundary layer.

Atmospheric concentrations of chlorine atom (Cl*), chlorine monoxide radical (ClO*), and hydroxyl radical (HO*) in the coastal marine boundary layer are estimated in this study. A steady-state approach to their concentrations in equilibrium with other atmospheric chemical species is used. Measurements of atmospheric trace species, HCl, Cl2, HCHO, H2O2, CH3OOH, CH4, CO, SO2, NO, NO2, and O3, were performed at four sites in Taiwan during the spring of 1999. The results indicate that the concentrations of the Cl* atom and the ClO* and HO* radicals decrease significantly with cloud cover. The calculated average daytime concentrations of Cl*, ClO*, and HO* are 3 x 10(5), 1 x 10(7), and 6 x 10(5) molecules/cm3, respectively. Due to the high reactivity of Cl* with hydrocarbons and its concentration level competitive to that of HO*, Cl* should be a significant sink for hydrocarbons in these cases.

Air Pollutants↗
PubMed2004

Ground based radon-222 observations and their application to atmospheric studies.

The aim of this paper is to review recent trends in the application of ground based radon observations to atmospheric research. In spite of over four decades of atmospheric radon monitoring, only in the past decade has the potential of this passive tracer been realised through a series of atmospheric model evaluation studies. Firstly, the key operational requirements for baseline radon detectors are briefly discussed, including lower limit of detection and response time. Then, current radon-related benchmarks for the evaluation of regional and global models are reviewed, with particular consideration given to the implications of data availability, resolution, site location and model spatial/temporal resolution. An 8-year subset of radon observations from the Cape Grim Baseline Air Pollution Station is used to suggest new benchmarks that exploit long-term data sets. Lastly an overview is presented of a technique that uses radon to estimate regional fluxes of climatically sensitive gases, with specific examples for CO2, CH4 and N2O.

Air Pollutants, Radioactive↗
PubMed2004

In situ sensing of the middle atmosphere with balloonborne near-infrared laser diodes.

Since 1997, two near-infrared laser diode sensors have been developed with the support of the CNES, the French space agency, to provide in situ data of H(2)O, CH(4) and CO(2) in the middle atmosphere. The realized instruments were flown from stratospheric balloons within the framework of European campaigns for the study of stratospheric ozone and water vapor and were involved in the validation of the ODIN and ENVISAT satellites. In this paper, we describe the developed laser probing technique, we report atmospheric measurements and finally we discuss future perspectives, particularly the in situ laser sensing of the lower atmosphere of Mars and the implication of the laser hygrometers in balloon campaigns at mid-latitudes and tropical regions to investigate the sources and sinks of stratospheric H(2)O.

Air↗
PubMed2004

Concentration characteristics of atmospheric PCBs for urban and rural area, Korea.

Mean concentrations of total PCBs (gas+particle) detected in urban and rural atmospheres were 130.41+/-62.57 pg/m(3) and 39.65+/-34.04 pg/m(3), respectively. The concentration distribution of PCB homologs in the urban and rural area decreased with increasing Cl substitutions and showed significant correlation coefficients (P>0.05) with the octanol-air partition coefficient (K(OA)) and vapor pressure, respectively. The fractions (%) of total PCBs were 28% for tri-CBs, 25% for tetra-CBs and 24% for penta-CBs in urban air and 45% for tri-CBs, 24% for tetra-CBs, and 21% for penta-CBs in rural air. The sum of those homologs was 77% for urban and 90% for rural air. Therefore, these homologs were identified as the main components of PCB homologs compared to other homologs (>penta-CBs). The Clausius-Clapeyron (CC) plot was applied to atmospheric PCB data, relating PCB partial vapor pressure (logarithm P) to inverse absolute temperature (1/T). The slopes obtained from Clausius-Clapeyron plots were -3888 (R(2)=0.75, P<0.0001) for urban and -1902 (R(2)=0.22, P<0.1) for rural air. The slope for urban air was approximately two times higher than that of rural air, possibly because the atmospheric concentration of lower molecular weight congeners in urban air may be predominantly influenced by local sources relative to rural air.

Journal Article↗
PubMed2004

Assessment of lichen diversity by index of atmospheric purity (IAP), index of human impact (IHI) and other environmental factors in an urban area (Grenoble, southeast France).

An assessment of air quality in the Grenoble area was made using the index of atmospheric purity (IAP). The survey area was divided into 198 units (0.7 x 1 km), in which 345 average lichen relevés were analyzed according to the Braun-Blanquet method. Each relevé station was characterized in the field by a subjective index of human impact (IHI) calculated according to four local environmental parameters influencing the epiphytic lichen flora: urbanization (urban, suburban or rural area), road traffic (low or high), local developments (stations located within crop fields, green areas, housing sites or car parks), and exposure (trees isolated, in rows or grouped). Eighty-three epiphytic lichen species and two algae were recorded and grouped into three ecological categories defined according to bark type and nutrient needs: nitrophytic, neutrophytic and acidophytic species. IAP values, varying from 5.9 to 71.7, were clustered into five categories in order to produce an air-quality map. The geographical pattern of the IAP map showed no clear connection with local sources of pollution, such as the vicinity of a road or an industrial plant, and was not correlated with annual mean values of SO(2), NO(2) and NO for the years 1994-1997. IAP appeared to be influenced by environmental artificiality as shown by a polynomial trend observed between IAP and IHI, even if IAP values were broadly scattered. Multivariate analysis (canonical correspondence) showed that high IAP values could be observed in stations of "natural" environments at high elevations and in stations of "artificial" environments at low elevations. It was also shown that IAP varied in relation to the relative proportion of ecological groups of lichen relevés: although a majority of neutrophytic species (>50%) with a much lower percentage of nitrophytic species generally characterized high IAP, a predominance of acidophytic or nitrophytic species led to a decrease in the IAP. A correlation between nitrophytic species and artificiality of the environment was also shown. Furthermore, IAP, initially created to characterize atmospheric pollution or atmospheric purity by means of the lichen flora, is shown to be influenced by other parameters such as environmental and landscape factors.

Air Pollutants↗
PubMed2004

Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in mosses (Hypnum cupressiforme) in Hungary.

The atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) was investigated in Hungary by analyzing a moss (Hypnum cupressiforme) species as a bioindicator. In the autumn of 1997, samples were collected at 29 sites distributed across Hungary. The concentrations of total PAH at these sites were in the range of 0.1567-10.45 x 10(4) microg kg(-1) with a mean value of 1.87 x 10(4) microg kg(-1). More than 99% of the total PAHs atmospheric deposition were low molecular weight PAHs (up to 3 ring compounds). The total PAH values showed no correlation with metal concentrations. However, most of the sites in this region showed a positive linear relationship between PAHs levels and traffic volume (r2 = 0.83; P < 0.001) while no relationship existed between PAH levels and population (r2 = 0.01; P > 0.1). Atmospheric deposition of PAHs at different regions in Hungary may be due to incomplete combustion of fuel. The total concentrations of PAHs were compared to the PAH levels in vegetation samples collected from different regions around the world. The highest PAHs concentrations accumulated were found in Hypnum cupressiforme than other vegetation species. A greater affinity for PAH compounds by Hypnum cupressiforme than other moss species probably caused larger amounts of accumulation. A relationship between accumulations of PAH compounds in Hypnum cupressiforme and octanol-air partition coefficients was obtained and is briefly discussed.

Air Pollutants↗