Application of spectral coherence analysis to describe the relationships between ambient ozone exposure and crop growth

Growth season-based time series spectral coherence analysis was performed between weekly changes in hourly ambient O(3) concentrations and weekly changes in alfalfa height growth. Weekly median hourly O(3) concentration and the corresponding weekly cumulative integral (sum of all hourly concentrations within the week) were used as indicators of weekly O(3) spectral density and coherence with the change in weekly alfalfa height growth. In general, the weekly cumulative integral performed much better than the weekly median O(3) concentration. A conceptual analysis of the results is presented, along with a recommendation that crop growth stage-based cumulative integrals merit further evaluation towards a better understanding of cause-effect relationships.     

Origin of Bel-W3, Bel-C and Bel-B tobacco varieties and their use as indicators of ozone

Since 1962, the tobacco variety Bel-W3 (Nicotiana tabacum L.), has been used in many countries as an indicator of the presence of phytotoxic concentrations of O(3). It is super-sensitive to O(3) and may produce easily recognizable symptoms for several weeks on the new, fully expanded leaves. Bel-B and Bel-C, tolerant and sensitive to O(3), respectively, are sometimes used along with Bel-W3. Information is provided on the origin and nature of these varieties. This includes their use as indicators of elevated O(3) concentrations, strength and limitations, and the inheritance and nature of resistance to O(3) in Bel-B. The varieties were the product of research initiated in 1957 to determine the cause and to reduce losses from tobacco weather fleck. Bel-C and Bel-B display the classical upper leaf surface injury; whereas, Bel-W3 develops primarily bifacial lesions. Data are provided to show differences in the amounts of acute and chronic injury on each variety when exposed to different O(3) exposure doses in controlled environments and under field conditions. There is discussion of the influence of environmental factors on response to O(3) by the varieties and the possibility of synergistic action of O(3) and SO(3) when tobacco is exposed to mixtures of these gases. The methods and results obtained with Bel-W3 in the Dutch National Monitoring Network for Air Pollution are presented in detail. Use of Bel-W3 world-wide as an indicator of elevated O(3) concentrations has been a significant factor in increasing the awareness of O(3) as a pollutant.     

Intraspecific responses of six Indian clover cultivars under ambient and elevated levels of ozone

Intraspecific variation in six cultivars of clover Trifolium alexandrinum L., (Bundel, Wardan, JHB-146, Saidi, Fahli, and Mescavi) has been studied with ambient and elevated O₃ (ambient?+?10 ppb O₃) in open top chambers. Significant effect of elevated O₃ was detected on different morphological, physiological, and biochemical parameters depicting differential response among the test cultivars. Results showed that the magnitude of O₃ induced foliar injury symptoms varied in all the cultivars. Ozone significantly depressed photosynthetic rate, stomatal conductance, and photosynthetic efficiency, although variations were cultivar specific. Ozone treatment diminished total biomass of all the cultivars; reduction was highest in Wardan with least O₃ resistance followed by Bundel, JHB-146, Saidi, Mescavi, and Fahli. According to the cumulative sensitive index, variations in the sensitivity showed that two cultivars (Wardan and Bundel) were sensitive to elevated O₃, while other three cultivars (Fahli, Saidi, and Mescavi) were resistant, and JHB-146 showed intermediate sensitivity. Therefore, the present study supported the selection of sensitive cultivar of clover as a bioindicator for O₃ under Indian conditions for the areas experiencing higher concentrations of O₃.     

Differential protection of ethylenediurea (EDU) against ambient ozone for five cultivars of tropical wheat

The antiozonant EDU (ethylenediurea) was used to assess the impact of ambient O₃ under field conditions on five cultivars of tropical wheat (Triticum aestivum L.). EDU solution (0 ppm and 400 ppm) was applied as soil drench (100 ml plant^?1) 10 days after germination (DAG) at an interval of 12 days. EDU-treated plants showed significant increments in stomatal conductance, photosynthetic rate, variable fluorescence, total chlorophyll, ascorbic acid, proline and protein contents and protective enzymes (POX, SOD and APX) activities in HUW468, HUW510 and HUW234 cultivars, while, a reverse trend was observed for lipid peroxidation. EDU application restored grain yield significantly by maintaining higher levels of antioxidants, metabolites and enzymes in cultivars HUW468 and HUW510. Sonalika and PBW343 showed least response of measured parameters under EDU treatment suggesting their greater resistance to O₃. EDU, thus proved its usefulness in screening suitable wheat cultivars for areas experiencing elevated concentrations of O₃.     

Bee pollens as biological indicators: An ecological assessment of pollution in Northern Turkey via ICP-MS and XPS analyses

Environmental Science and Pollution Research - In this study, pollens were collected from 25 different locations of Northern Turkey to investigate pollution monitoring. Surface chemistry of pollen...     

Air pollution models as descriptors of cause-effect relationships

The problem of air pollution modeling is treated beginning from a philosophical standpoint, in which a model is viewed as a ‘universal statement’ and a complementary set of ‘singular statements’ from which specific cause-effect relationships are deduced; proceeding to the formulation of a specific model from fundamental physical principles. In the course of the analyses, a number of basic issues are examined. These include the types of information that an air pollution model is capable of providing (it is shown that specific events are not predictable, only the set of possible events can be described); the problem of model ‘validation’ (even with a perfect model and error-free input data and observations, discrepancies will exist between predicted and observed quantities); the character and representation of long-range dispersion (the conventional concepts of transport and diffusion become ill-defined when applied within the context of longrange dispersion models); and other topics relevant to the use of models in decision making processes.     

The use of mosses as environmental metal pollution indicators

The possibility of using mosses as environmental indicators of metal pollution has been investigated. Mosses of the species Bryum argenteum were collected from different parts of Piedmont (Italy), ranging from highly polluted areas to nearly uncontaminated mountain areas. Periodical samplings were planned in every site on a monthly base, in order to check variations of metal uptake throughout one year; correlations with pluviometric and thermal patterns were investigated for all sampling stations. On every moss sample 20 elements, ranging from major (K, P, Al, Ca, Fe and Mg) to minor (Mn, Na, Ti and Zn) and trace (As, Ba, Cd, Co, Cr, Cu, Li, Ni, Pb and Sr), were quantitatively determined by inductively coupled plasma-atomic emission spectrometry or graphite furnace-atomic absorption spectrometry, depending on the needed sensitivity. Statistical analyses, carried out with principal component analysis and cluster analysis methods, revealed that a good correlation exists between metal content in mosses and pollution degree in the areas sampled.     

Use of passive ambient ozone (O3) samplers in vegetation effects assessment

A stochastistic, Weibull probability model was developed and verified to simulate the underlying frequency distributions of hourly ozone (O3) concentrations (exposure dynamics) using the single, weekly mean values obtained from a passive (sodium nitrite absorbent) sampler. The simulation was based on the data derived from a co-located continuous monitor. Although at the moment the model output may be considered as being specific to the elevation and location of the study site, the results were extremely good. This effort for the approximation of the O3 exposure dynamics can be extended to other sites with similar data sets and in developing a generalized understanding of the stochastic O3 exposure-plant response relationships, conferring measurable benefits to the future use of passive O3 samplers, in the absence of continuous monitoring.     

On the statistical analysis of ambient ozone data when measurements are missing

Two methods are proposed to deal with missing observations, which frequently pose problems in the statistical analysis of ambient ozone data. The first is based on exceedances of the data over thresholds and provides a flexible and general class of models for statistical analysis of air pollution data. The second uses the measured values of related variables to impute missing observations. They are applied to data for three sites in E Texas.     

Time series analysis of ambient air pollution effects on daily mortality

Although the growths of ambient pollutants have been attracting public concern, the characteristic of the associations between air pollutants and mortality remains elusive. Time series analysis with a generalized additive model was performed to estimate the associations between ambient air pollutants and mortality outcomes in Shenzhen City for the period of 2012–2014. The results showed that nitrogen dioxide (NO₂)-induced excess risks (ER) of total non-accidental mortality and cardiovascular mortality were significantly increased (6.05% (95% CI 3.38%, 8.78%); 6.88% (95% CI 2.98%, 10.93%), respectively) in interquartile range (IQR) increase analysis. Also, these associations were strengthened after adjusting for other pollutants. Moreover, similar associations were estimated for sulfur dioxide (SO₂), particulate matter with an aerodynamic diameter of <10 μm (PM₁₀), and total non-accidental mortality. There were significant higher ERs of associations between PM₁₀ and mortality for men than women; while there were significant higher ERs of associations between PM₁₀/NO₂ and mortality for elders (65 or elder) than youngers (64 or younger). Season analyses showed that associations between NO₂ and total non-accidental mortality were more pronounced in hot seasons than in warm seasons. Taken together, NO₂ was positively associated with total non-accidental mortality and cardiovascular mortality in Shenzhen even when the concentrations were below the ambient air quality standard. Policy measures should aim at reducing residents’ exposure to anthropogenic NO₂ emissions.     

Norway spruce and spruce shoot aphid as indicators of traffic pollution

Two-year-old Norway spruce (Picea abies (L.) Karst) seedlings were exposed to traffic emissions along roadsides with three different traffic densities and speed limits; highway, street and a quiet local road. The responses of the exposed seedlings as a host plant and those of spruce shoot aphid (Cinara pilicornis Hartig) were studied. The concentrations of soluble N and free amino acids, defence chemicals (total phenolics, monoterpenes) were analysed, and aphid growth and reproduction were studied. Along the highway, street and at the local road control site, the atmospheric concentrations of black carbon (BC) and oxides of N (NO(x)) were measured for 1 week during the experiment. The BC data indicate deposition of organic particulate compounds along the highway and street. The NO(x) concentrations along the highway and street showed great diurnal variation, but the average NO(x) concentrations were relatively low. Thus, no changes in N metabolism or growth of the exposed Norway spruce seedlings were found. Along the street, the concentrations of many individual free amino acids, such as proline, as well as total amino acid concentrations, were lower than at the associated control site. Correspondingly, there was also no increase in spruce shoot aphid mean relative growth rate. The aphid reproduction, however, increased along the highway and is suggested to be due to more conducive microclimatic conditions at the exposure site or lack of natural enemies. No changes in defence chemicals (total phenolics, monoterpenes) in relation to the traffic exposure were found. Instead, the microclimatic conditions (temperature, solar irradiation) seemed to affect the concentration of total phenolics.     

Sensitivity analysis of an ozone deposition model

In this study, sophisticated sensitivity analyses of a detailed ozone dry deposition model were performed for five soil types (sand, sandy loam, loam, clay loam, clay) and four land use categories (agricultural land, grass, coniferous and deciduous forests). Deposition velocity and ozone flux depend on the weather situation, physiological state of the plants and numerous surface-, vegetation-, and soil-dependent parameters. The input data and the parameters of deposition-related calculations all have higher or lower spatial and temporal variability. We have investigated the effect of the variability of the meteorological data (cloudiness, relative humidity and air temperature), plant-dependent (leaf area index and maximum stomatal conductance) and soil-dependent (soil moisture) parameters on ozone deposition velocity. To evaluate this effect, two global methods, the Morris method and the Monte Carlo analysis with Latin hypercube sampling were applied. Additionally, local sensitivity analyses were performed to estimate the contribution of non-stomatal resistances to deposition velocity. Using the Monte Carlo simulations, the ensemble effect of several nonlinear processes can be recognised and described. Based on the results of the Morris method, the individual effects on deposition velocity are found to be significant in the case of soil moisture and maximum stomatal conductance. Temperature and leaf area index are also important factors; the former is primarily in the case of agricultural land, while the latter is for grass and coniferous forest. The results of local sensitivity analyses reveal the importance of non-stomatal resistances.     

The effect of ambient ozone pollution and acidic rain on the growth and chlorophyll content of green and white ash

Two- and three-year old green ash (Fraxinus americana L.) and white ash (Fraxinus pennsylvanica Marsh.) seedlings were exposed to combinations of ambient ozone and acidic ambient rainfall in New Brunswick, New Jersey. During the 3-year study the potted seedlings did not develop typical foliar ozone toxicity symptoms, despite the occurrence of as many as 78 h in exceedance of the National Ambient Air Quality Standard of 0.12 ppm. Although the pH of the rainfall was as low as 3.6 and averaged 4.1, no symptoms were observed resulting from the ambient precipitation. The rate of shoot growth in terms of height and diameter was generally not affected by either of the pollutants during the growing season. Although the chlorophyll content of white ash foliage was low following frequent rainfall in the early summer of 1984, there was no statistically significant evidence that acid raid or ambient ozone decreased chlorophyll in ash seedlings during the 3-year study.     

A review of biomarker compounds as source indicators and tracers for air pollution

An overview of the application of organic geochemistry to the analysis of organic matter on aerosol particles is presented here. This organic matter is analyzed as solvent extractable bitumen/ lipids by gas chromatography-mass spectrometry. The organic geochemical approach assesses the origin, the environmental history and the nature of secondary products of organic matter by using the data derived from specific molecular analyses. Evaluations of production and fluxes, with cross-correlations can thus be made by the application of the same separation and analytical procedures to samples from point source emissions and the ambient atmosphere. This will be illustrated here with typical examples from the ambient atmosphere (aerosol particles) and from emissions of biomass burning (smoke). Organic matter in aerosols is derived from two major sources and is admixed depending on the geographic relief of the air shed. These sources are biogenic detritus (e.g., plant wax, microbes, etc.) and anthropogenic particle emissions (e.g., oils, soot, synthetics, etc.). Both biogenic detritus and some of the anthropogenic particle emissions contain organic materials which have unique and distinguishable compound distribution patterns (C₁₄-C₄₀). Microbial and vascular plant lipids are the dominant biogenic residues and petroleum hydrocarbons, with lesser amounts of the pyrogenic polynuclear aromatic hydrocarbons (PAH) and synthetics (e.g., chlorinated compounds), are the major anthropogenic residues. Biomass combustion is another important primary source of particles injected into the global atmosphere. It contributes many trace substances which are reactants in atmospheric chemistry and soot paniculate matter with adsorbed biomarker compounds, most of which are unknown chemical structures. The injection of natural product organic compounds into smoke occurs primarily by direct volatilization/steam stripping and by thermal alteration based on combustion temperature. Although the molecular composition of organic matter in smoke particles is highly variable, the molecular tracers are generally still source specific. Retene has been utilized as a tracer for conifer smoke in urban aerosols, but is not always detectable. Dehydroabietic acid is generally more concentrated in the atmosphere from the same emission sources. Degradation products from biopolymers (e.g., levoglucosan from cellulose) are also excellent tracers. An overview of the biomarker compositions of biomass smoke types is presented here. Defining additional tracers of thermally-altered and directly-emitted natural products in smoke aids the assessment of the organic matter type and input from biomass combustion to aerosols. The precursor to product approach of compound characterization by organic geochemistry can be applied successfully to provide tracers for studying the chemistry and dispersion of ambient aerosols and smoke plumes. Presented at the 6th FECS Conference on Chemistry and the Environment, Atmospheric Chemistry and Air Pollution, August 26–28, 1998, Copenhagen.     

Monitoring ambient ozone with a network of passive samplers: a feasibility study

Ambient levels of ozone have been measured at 46 mountain forest, desert, Class I Wilderness areas and other remote locations using a network of passive samplers. Typical values were 40-80 ppb (2 week samples) and exhibited temporal variations (studied for up to 1 year) as well as changes with elevation (studied up to 10 500 ft (3 200 m)). The performance of the passive sampler was evaluated with respect to reproducibility, field controls, data capture (>0.95), precision for co-located samples (av. = 11.9%, n = 103), and the role of other atmospheric oxidants as potential interferents (2 locations). Suggestions for additional sampler performance evaluation and network operation are outlined.     

PIXE trace element analysis of an aquatic plant as indicator of heavy metal pollution

A new way of detecting trace elements in water is developed by using charged $\text{P}$article $\text{I}$nduced $\text{X}$-ray $\text{E}$mission (PIXE) analysis of cell walls of $\text{Chara corallina}$, a fresh water alga.     

Assessing plant response to ambient ozone: growth of young apple trees in open-top chambers and corresponding ambient air plots

Open-top chambers (OTCs) and corresponding ambient air plots (AA) were used to assess the impact of ambient ozone on growth of newly planted apple trees at the Montague Field research center in Amherst, MA. Two-year-old apple trees (Malus domestica Borkh 'Rogers Red McIntosh') were planted in the ground in circular plots. Four of the plots were enclosed with OTCs where incoming air was charcoal-filtered (CF); four were enclosed with OTCs where incoming air was not charcoal-filtered (NF) and four were not enclosed, allowing access to ambient air conditions (AA). Conditions in both CF and NF OTCs resulted in increased tree growth and changed incidence of disease and arthropod pests, compared to trees in AA. As a result, we were not able to use the OTC method to assess the impact of ambient ozone on growth of young apple trees in Amherst, MA.