Changes in species richness of vascular plants under the impact of air pollution: a global perspective

Aim To investigate the general pattern of changes in species richness and diversity of vascular plants due to environmental contamination and associated habitat changes imposed by point polluters, and identify the sources of variation in the response of plant communities to industrial pollution. Location Global. Methods We collected species richness and diversity data from 86 studies that were conducted around 60 atmospheric point polluters worldwide and reported in 95 papers (published in 1953–2007). We used meta‐analysis to search for a general effect and to compare between polluter types and plant groups, and linear regression to describe the latitudinal gradient and to quantify relationships between pollution and effect size. Results Although the species richness of vascular plants generally decreased with pollution, the effects were not uniform across the studies. Polluters that cause soil acidification imposed a stronger detrimental effect on plant diversity than industries whose emissions increased soil pH. An overall adverse effect was primarily due to the contribution of non‐ferrous smelters and aluminium plants; the effects of other SO₂‐emitting industries were less detrimental, albeit negative, and the effects of chemical plants, fertilizer factories and cement industries did not differ from zero. Longevity of the pollution impact only made a slight contribution to the detected variation, while adverse effects increased with increase in pollution load. Main conclusions This study is the first demonstration of geographical variation in the responses of plant communities to aerial emissions: adverse effects increased from high to low latitudes, and this pattern was explained primarily by increases in both the diversity of original (undisturbed) communities and mean summer temperatures. The latter result suggests that under a future warmer climate the existing pollution loads may become more harmful. Model calculations indicate that a detectable depauperation of plant communities is unlikely if the polluter emits < 1500 t of SO₂ annually.     

Analysis of the emission of SO2, NOx,and suspended particles from the thermal power plants Kostolac (Serbia)

The environmental situation related to the thermal power basin of Kostolac for the most part represents the result of the influence of the thermal power plants (TPPs) of Kostolac A, Kostolac B, and the open-pit lignite mine. The quality of air is monitored by continuously measuring concentrations of the overall precipitation matters and gases such as CO₂, SO₂, NO_x, CO, and O₃. Values significantly exceeding the legal limits have been found for pollutants in the surroundings of the TPPs Kostolac A and B and in the direction of dominant winds. The paper analyzes the impact of different scenarios of emission of harmful matters from the blocks of TPPs Kostolac A and B on the quality of air in this part of Serbia. The Gaussian model has been used to evaluate dispersion of gas substances and suspended particulates as well as parameters related to the surroundings. Calculations have been made relating to ground-level concentrations of sulfur dioxide, nitrogen oxide, and suspended particles at varying distances from the emission source.     

Bark pH and susceptibility to toxic air pollutants as independent causes of changes in epiphytic lichen composition in space and time

Abstract:The lichen composition on wayside Quercus robur in the Netherlands was related to bark properties (pH, EC, NH₄⁺, SO₄²⁻, NO₃⁻) and levels of air pollution (SO₂and NH₃). The pH of the bark and the susceptibility to toxic substances appear to be the two major primary factors affecting epiphytic lichen composition. These factors have independent effects on the lichen composition. Most of the so-called nitrophytic species appear to have a low sensitivity to toxic effects of SO₂; their only requirement being a high bark pH. An increased bark pH appears to be the primary cause of the enormous increase in nitrophytic species and the disappearance of acidophytic species over the last decade in the Netherlands. Measurements of ambient NH₃concentrations in air show that there is a nearly linear relationship between the NH₃concentration and the abundance of nitrophytes on Quercus. The abundance of nitrophytes was not correlated with SO₂concentrations. Most of the acidophytic species appear very sensitive to NH₃since in areas with concentrations of 35 μg m⁻³or more, all acidophytic species have disappeared. Current methods using species diversity to estimate or monitor SO₂air pollution need some modification, otherwise the air quality may be erroneously considered to be relatively good in areas with high NH₃levels.     

Are predators negative or positive predictors of farmland bird species community on a large geographical scale?

Species distribution models (SDMs) are numerical tools that combine species occurrence/density or species richness with environmental data in order to predict particular species’ distribution. In most cases only abiotic environmental parameters are used as predictors, while biotic interactions which control distribution of species and influence the goodness of fit of the SDM, such as predator–prey systems, have been broadly neglected. For this reason, we tested the usefulness of easy to detect predators, such as the Common Buzzard and the Common Raven, as positive and negative predictors, respectively, of farmland bird species richness. We analyzed factors affecting the density of both predators and farmland bird species using data from 958 1 × 1 km² study plots in Poland and a set of 22 environmental variables. Next, we also included these predators’ densities as additional predictors of farmland bird species. Habitat and climatological predictors were aggregated using the Principal Components Analysis and then related to the Common Raven's and the Common Buzzard's densities as well as farmland bird species richness using General Additive Models. Finally, completed models were assessed according to information – theoretic criteria. Our results showed that all the analyzed groups occurred in open areas; the Common Buzzard and passerine bird species preferred traditional farmland, while the Common Raven reached its highest density in modern intensive farmland. Importantly, we documented a significant increase in the goodness of fit of SDMs for farmland bird species, having added the density of predators as negative (Common Raven) and positive (Common Buzzard) predictors. Consequently, our findings suggest that species’ specific models can improve the predictive power of SDMs and can be used as an effective tool for predicting bird diversity with higher accuracy.     

Projected Effects of Climate Change on Patterns of Vertebrate and Tree Species Richness in the Conterminous United States

General circulation models (GCM) predict that increasing levels of atmospheric carbon dioxide (CO₂) and other greenhouse gases will lead to dramatic changes in climate. It is known that the spatial variability of species richness over continental spatial scales is strongly correlated with contemporary climate. Assuming that this relationship between species richness and climate persists under conditions of increased CO₂, what changes could we expect to occur in terms of species richness? To address this question, I used observed relationships between contemporary richness and climate, coupled with climate projections from five GCM, to project these future changes. These models predict that the richness of vertebrate ectotherms will increase over most of the conterminous United States. Mammal and bird richness are predicted to decrease in much of the southern US and to increase in cool, mountainous areas. Woody plant richness is likely to increase throughout the North and West and to decrease in the southwestern deserts. These projections represent changes that are likely to occur over long time scales (millennia); short-term changes are expected to be mainly negative.     

Long distance nitrogen air pollution effects on lichens in Europe

The epiphytic lichen flora of 25 European ICP-IM monitoring sites, all situated in areas remote from air pollution sources, was statistically related to measured levels of SO₂in air, NH₄⁺, NO₃⁻ and SO₄²⁻ in precipitation, annual bulk precipitation, and annual average temperature. Significant regression models were calculated for eleven acidophytic species. Several species show a strong negative correlation with nitrogen compounds. At concentrations as low as 0·3 mg N l⁻¹in precipitation, a decrease of the probability of occurrence is observed for Bryoria capillaris, B. fuscescens, Cetraria pinastri, Imshaugia aleurites and Usnea hirta. The observed pattern of correlations strongly suggests a key role of NH₄⁺ in determining the species occurrence, but an additional role of NO₃⁻ cannot be ruled out. Some species show a distinct response to current levels of SO₂as well. It may be concluded that long distance nitrogen air pollution has strong influence on the occurrence of acidophytic lichen species.     

Bird abundance and species richness on Florida lakes: influence of trophic status,lake morphology,and aquatic macrophytes

Data from 46 Florida lakes were used to examine relationships between bird abundance (numbers and biomass) and species richness, and lake trophic status, lake morphology and aquatic macrophyte abundance. Average annual bird numbers ranged from 7 to 800 birds km^–2 and bird biomass ranged from 1 to 465 kg km^–2. Total species richness ranged from 1 to 30 species per lake. Annual average bird numbers and biomass were positively correlated to lake trophic status as assessed by total phosphorus (r = 0.61), total nitrogen (r = 0.60) and chlorophyll a (r = 0.56) concentrations. Species richness was positively correlated to lake area (r = 0.86) and trophic status (r = 0.64 for total phosphorus concentrations). The percentage of the total annual phosphorus load contributed to 14 Florida lakes by bird populations was low averaging 2.4%. Bird populations using Florida lakes, therefore, do not significantly impact the trophic status of the lakes under natural situations, but lake trophic status is a major factor influencing bird abundance and species richness on lakes. Bird abundance and species richness were not significantly correlated to other lake morphology or aquatic macrophyte parameters after the effects of lake area and trophic status were accounted for using stepwise multiple regression. The lack of significant relations between annual average bird abundance and species richness and macrophyte abundance seems to be related to changes in bird species composition. Bird abundance and species richness remain relatively stable as macrophyte abundance increases, but birds that use open-water habitats (e.g., double-crested cormorant, Phalacrocorax auritus) are replaced by species that use macrophyte communities (e.g., ring-necked duck, Aythya collaris).     

Early needle senescence and thinning of the crown structure of Picea abies as induced by chronic SO2pollution. I. Model deduction and analysis

Regarding time ranges of years, a rationale has been developed which is capable of explaining observed ‘spruce decline’ symptoms observed when spruce is exposed to air containing ambient levels of SO₂. It integrates and interrelates (i) ecophysiological data (tree morphology, assimilate partitioning, canopy turnover, senescence physiology, stomatal conductance, canopy throughfall, sulphur metabolism, tonoplast symport), (ii) pedological data (soil leaching, cation recycling, litter decomposition, forest nutrition), and (iii) meteorological data (site elevation, length of the annual trunk growth period, SO₂-pollution). Furthermore, it can explain field observations at numerous sites of spruce decline in central Europe where SO₂ is implicated as a factor of forest decline: (i) thinning of the canopy structure; (ii) early needle senescence; (iii) cation deficiency; (iv) low SO₂ tolerance at sites with depleted soils in the mountains; (v) synergism of SO₂pollution and acidic precipitation; (vi) recovery after liming, fertilization and after decreasing SO₂ pollution; and (vii) higher SO₂ tolerances of deciduous angiosperms. Different SO₂tolerance strategies are identified that are employed by more SO₂-tolerant tree species. Ecophysiological SO₂tolerance factors interact in a complex synergistic or antagonistic manner. It is concluded that chronic SO₂ pollution at ambient concentrations predisposes mainly evergreen gymnosperms to suffer under synergistic environmental stresses (frost, drought, pathogens, etc.). Thinning of the crown structure is massive at extreme sites, where several stresses act simultaneously on the trees (depleted soils, high SO₂ pollution, acidic rain, etc.). Mathematical formulations allow precise definitions of terms such as cooperativity, synergism, antagonism, vitality, predisposition, latency, etc. This universal rationale, which is applicable to all tree species, is exemplified here for Norway spruce (Picea abies [L.] Karst.). Integration of parameters yields an ordinary differential equation, which can be solved analytically. It predicts reversible dynamics of crown structures and gives an ecophysiological background to‘damage’.     

基于环境库兹涅茨曲线的我国大气污染防治重点区域环境空气质量与经济增长关系研究

改革开放以来,中国经济迅猛发展,但大气污染等环境问题日益突出。进入21世纪,我国通过颁布实施多项大气污染防治政策,将京津冀及周边地区、长三角地区、珠三角地区等大气污染较严重的区域划定为重点区域,针对性制定治污措施和实施减排工程,努力推动区域环境空气质量改善。基于2000-2019年我国31个省（自治区、直辖市）（以下简称31个省份）GDP,以及SO₂、PM₁₀、NO₂三项大气污染物浓度数据,利用环境库兹涅茨曲线（EKC,Environmental Kuznets Curve）模型,对31个省份和京津冀及周边地区、长三角地区、珠三角地区的经济增长情况、大气污染物浓度演变以及二者之间的关系进行了系统全面的分析评估。研究结果显示：（1）近年来实施的各项大气污染防治政策,特别是2013年以来颁布实施的《大气污染防治行动计划》《打赢蓝天保卫战三年行动计划》,推动环境空气质量改善的同时,促进了经济发展与环境保护长期关系协调性逐步增强,除NO₂浓度呈U型外,31个省份SO₂浓度、PM₁₀浓度与人均GDP的EKC曲线呈倒U型和倒N型,并处于快速下降阶段。（2）京津冀及周边地区SO₂浓度与人均GDP呈倒U型,且处于快速下降阶段;PM₁₀和NO₂浓度均呈现U型关系,且均处于上升期。（3）长三角地区SO₂、PM₁₀浓度与人均GDP呈现倒U型和U型,但均处于下降阶段;NO₂浓度与人均GDP无相关关系。（4）珠三角地区SO₂、PM₁₀和NO₂浓度与人均GDP均呈现倒U型关系,且均处于下降阶段。为此,建议"十四五"期间我国政府要继续实施新一轮的大气污染防治行动计划,聚焦机动车NO_x污染管控,大力推动NO₂浓度稳步下降,以实现我国环境空气质量持续改善,为统筹经济高质量发展和生态环境高水平保护奠定坚实基础。     

Spatial patterns of woody plant and bird diversity: functional relationships or environmental effects?

Aim To understand cross‐taxon spatial congruence patterns of bird and woody plant species richness. In particular, to test the relative roles of functional relationships between birds and woody plants, and the direct and indirect environmental effects on broad‐scale species richness of both groups. Location Kenya. Methods Based on comprehensive range maps of all birds and woody plants (native species > 2.5 m in height) in Kenya, we mapped species richness of both groups. We distinguished species richness of four different avian frugivore guilds (obligate, partial, opportunistic and non‐frugivores) and fleshy‐fruited and non‐fleshy‐fruited woody plants. We used structural equation modelling and spatial regressions to test for effects of functional relationships (resource–consumer interactions and vegetation structural complexity) and environment (climate and habitat heterogeneity) on the richness patterns. Results Path analyses suggested that bird and woody plant species richness are linked via functional relationships, probably driven by vegetation structural complexity rather than trophic interactions. Bird species richness was determined in our models by both environmental variables and the functional relationships with woody plants. Direct environmental effects on woody plant richness differed from those on bird richness, and different avian consumer guilds showed distinct responses to climatic factors when woody plant species richness was included in path models. Main conclusions Our results imply that bird and woody plant diversity are linked at this scale via vegetation structural complexity, and that environmental factors differ in their direct effects on plants and avian trophic guilds. We conclude that climatic factors influence broad‐scale tropical bird species richness in large part indirectly, via effects on plants, rather than only directly as often assumed. This could have important implications for future predictions of animal species richness in response to climate change.     

Meteorological factors and ambient bacterial levels in a subtropical urban environment

We conducted a study to investigate the characteristics and determinants of ambient bacteria in Taipei, Taiwan from August 2004 to March 2005. We monitored ambient culturable bacteria in Shin-Jhuang City, an urban area in the Taipei metropolitan areas, using duplicate Burkard Portable Air Samplers with R2A agar. The average concentration of total bacteria was 1,986 colony-forming units per cubic meter of air (CFU/m³) (median?=?780 CFU/m³) over the study period, with the highest level in autumn. Most bacterial taxa had similar seasonal variation, with higher concentrations in autumn and winter. During the study period, Gram negative rods and cocci were predominant. Multivariate analyses indicated that wind speed and wind direction significantly influenced ambient bacterial distribution. Temperature and relative humidity were also important environmental factors positively associated with ambient bacterial concentrations. We observed statistically significant relationships between ambient bacteria and air pollutants, including sulfur dioxide (SO₂), ozone, particulate matter (aerodynamic diameter ≤10 μm (PM₁₀)), methane and total hydrocarbons. The concentrations of methane and total hydrocarbons during the previous day were positively associated with total bacteria and Gram negative rods, respectively. Ozone level on the previous day had a negative relationship with Gram negative cocci. SO₂ level with a 3-day lag was positively correlated with concentrations of both total bacteria and Gram negative cocci. In the future, more longitudinal studies are needed to confirm the relationships and possible mechanisms between ambient bacteria and meteorological factors, as well as to evaluate the ecological and health impacts of ambient bacteria.     

The influence of a native tree species mix component on bird communities in non‐native coniferous plantations in Ireland

Capsule Norway Spruce plantations with Scots Pine as a secondary tree species had higher bird densities than pure Norway Spruce. Shrub cover was the most important structural variable, influencing bird density, species richness and Simpson’s diversity.

Aims To investigate whether incorporating a native tree component into non‐native coniferous plantations had any effect on bird communities or vegetation structure.

Methods Birds were surveyed in plantations of Norway Spruce mixed with Oak and Scots Pine, each paired with a plantation of pure Norway Spruce. distance was used to generate bird densities. Bird density, species richness and Simpson’s diversity were compared between each mix type and pure Norway Spruce. glms were used to investigate relationships between structural components of plantations and bird data.

Results Bird communities of mixed plantations differed only slightly in their composition from pure Norway Spruce. Bird density was significantly higher in Scots Pine mixes than in Oak mixes or pure Norway Spruce. Neither species richness nor Simpson’s diversity differed significantly between the plantation types. Some vegetation components differed between the plantations and shrub cover was positively associated with bird density, species richness and Simpson’s diversity. The presence of rides also increased bird density.

Conclusions There is a positive effect on bird communities of including a native tree species in non‐native coniferous plantations, but the magnitude of the effect is small. The influence of shrub cover on birds suggests that forest management may play an important role in determining the utility of plantations for birds. We recommend the establishment of mixed tree species plantations where possible, although, in the case of Oak mixes, the Norway Spruce appeared to suppress growth of the Oak and thus may be restricting its effect on birds. Changes in management, such as planting Oaks in clumps or heavier thinning of the coniferous component, could address this problem.     

Epiphytic macrolichen community correlates with modeled air pollutants and forest conditions

Novel systems combining bioindicators, models, and remote sensing are possible cost-effective methods to monitor regional-scale pollution. Epiphytic macrolichen communities have been widely used as air pollution bioindicators, however these communities are also affected by microclimate conditions as influenced by forest structure. We used the Finnish epiphytic macrolichen survey method SFS5670 to collect data in 27 spruce and birch dominated forests in southern Finland and northwestern Russia. The method measures the abundance and physiological damage of Hypogymnia physodes and Bryoria spp., and the frequency of 13 epiphytic macrolichen species of known sensitivity which can be used to calculate the widely used Index of Atmospheric Purity (IAP). The location of the sites represents an east–west gradient of air pollution conditions of SO₂, SO₄^2?, NO₂, NH₃ + NH₄⁺, and HNO₃ + NO₃^?. We also recorded living and dead forest structure characteristics at these sites, which we initially chose to be as similar as possible on either side of the border. Abundance and damage of H. physodes were correlated with forest structure but not with air pollution, indicating that these macrolichen variables may not be reliable bioindicators at low air pollution concentrations. However, the Index of Atmospheric Purity, calculated from observed presence/absence data of multiple epiphytic macrolichen species, was strongly correlated with sulfur and nitrogen pollutant concentrations. These results suggest that the IAP as calculated using data from the Finnish epiphytic macrolichen survey method may be a useful air pollution indicator in combination with modeled data, even in relatively clean regions.     

RANKING OF EPIPHYTIC LICHEN SENSITIVITY TO AIR POLLUTION USING SURVEY DATA: A COMPARISON OF INDICATOR SCALES

Epiphytic lichens were recorded on wayside trees in the Netherlands. Four statistical methods were used to detect the relationship between presence and abundance of lichen species and measured atmospheric concentrations of SO₂NO₂and NH₃. The observed relationships were compared to published indicater scales of lichen sensitivity to atmospheric pollution. For SO₂, a good agreement was found between all scales and calculated sensitivities based on presence or absence of species. For NO₂and NH₃the correspondence was less obvious. The sensitivity to NH₃was inversely related to Wirth's acidity indicator scale. Species that react positively to NH₃tend to be sensitive to SO₂and NO₂.     

The toxicity of sulphur dioxide to Diplocarpon rosae Wolf causing blackspot of roses

Germination of conidia of Diplocarpon rosae Wolf is inhibited in a solution made by dissolving 35 p.p.m. sulphur dioxide in water. Inhibition is permanent after exposure for 3 hr. Gaseous SO₂ in air under controlled conditions at 100μg./m³ markedly reduces infection of rose leaves after exposure for 2 days. Blackspot of roses is checked or eliminated in areas where SO₂ pollution of air exceeds 100/μ./m.³.     

Species Richness and Patterns of Invasion in Plants, Birds, and Fishes in the United States*

We quantified broad-scale patterns of species richness and species density (mean # species/km²) for native and non-indigenous plants, birds, and fishes in the continental USA and Hawaii. We hypothesized that the species density of native and non-indigenous taxa would generally decrease in northern latitudes and higher elevations following declines in potential evapotranspiration, mean temperature, and precipitation. County data on plants (n = 3004 counties) and birds (n=3074 counties), and drainage (6 HUC) data on fishes (n = 328 drainages) showed that the densities of native and non-indigenous species were strongly positively correlated for plant species (r = 0.86, P < 0.0001), bird species (r = 0.93, P<0.0001), and fish species (r = 0.41, P<0.0001). Multiple regression models showed that the densities of native plant and bird species could be strongly predicted (adj. R² = 0.66 in both models) at county levels, but fish species densities were less predictable at drainage levels (adj. R² = 0.31, P<0.0001). Similarly, non-indigenous plant and bird species densities were strongly predictable (adj. R² = 0.84 and 0.91 respectively), but non-indigenous fish species density was less predictable (adj. R² = 0.38). County level hotspots of native and non-indigenous plants, birds, and fishes were located in low elevation areas close to the coast with high precipitation and productivity (vegetation carbon). We show that (1) native species richness can be moderately well predicted with abiotic factors; (2) human populations have tended to settle in areas rich in native species; and (3) the richness and density of non-indigenous plant, bird, and fish species can be accurately predicted from biotic and abiotic factors largely because they are positively correlated to native species densities. We conclude that while humans facilitate the initial establishment, invasions of non-indigenous species, the spread and subsequent distributions of non-indigenous species may be controlled largely by environmental factors. The U.S. Government’s right to retain a non-exclusive, royalty-free licence in and to any copyright is acknowledged.     

The Novel Relationship between Urban Air Pollution and Epilepsy: A Time Series Study

MethodsA hospital record-based study was carried out in Xi’an, a heavily-polluted metropolis in China. Daily baseline data were obtained. Time-series Poisson regression models were applied to analyze the association between air pollution and epilepsy.ResultsA 10 μg/m³ increase of NO₂, SO₂, and O₃ concentrations corresponded to 3.17% (95%Cl: 1.41%, 4.93%), 3.55% (95%Cl: 1.93%, 5.18%), and -0.84% (95%Cl: -1.58%, 0.09%) increase in outpatient-visits for epilepsy on the concurrent days, which were significantly influenced by sex and age. The effects of NO₂ and SO₂ would be stronger when adjusted for PM_2.5. As for O₃, a -1.14% (95%Cl: -1.90%, -0.39%) decrease was evidenced when adjusted for NO₂. The lag models showed that the most significant effects were evidenced on concurrent days.ConclusionsWe discovered previously undocumented relationships between short-term air pollution exposure and epilepsy: while NO₂ and SO₂ were positively associated with outpatient-visits of epilepsy, O₃ might be associated with reduced risk.     

Assessment of Modeled Indoor Air Concentrations of Particulate Matter,Gaseous Pollutants,and Volatile Organic Compounds Emitted from Candles

Candle burning is regarded as an important source of airborne pollutants in indoor environments. Indoor concentrations of aldehydes, benzo(a)pyrene, sulphur dioxide (SO₂), nitrogen oxides (NO_x), and particulate matter (PM) produced from the burning of scented candles and raw materials with different melting point/oil content (50/1, 55/9, and 65/6) were predicted using a single compartment mass balance model and compared to regulatory or guideline limits. Scented candles may be responsible for indoor acrolein concentrations that could become relevant to health only in the case of chronic exposure. Indoor concentrations of fine PM and SO₂ emitted from 65/6 wax burning under worst-case environmental and behavioral conditions were greater than their respective acute guideline limits. However, other waxes had levels of PM and SO₂ well below the recommended values. Indoor concentrations of nitrogen dioxide emitted from raw wax burning should be further investigated. The degree of pureness of raw waxes significantly affected the predicted indoor concentrations of PM and SO₂. In particular, 65/6 wax was criticized for its high content of impurities.     

Early diagnosis of SO2-stress by volatile emissions in some crop plants

Summary Fumigation experiments with SO₂ performed on the seedlings of three plant species viz, tomato (Lycopersicon esculentum), mung bean (Vigna radiata) and maize (Zea mays) resulted in the emission of volatiles. Acetaldehyde and ethanol were produced in the fumigated plants. In addition, there was also an increased production of ethylene and ethane. The production of these volatiles was positively correlated to the SO₂ concentrations of 4.2 and 8.3 mol m^–3 (0.1 and 0.2 ppm). Ethylene was emitted primarily from SO₂-stressed yet healthy leaves, whereas high ethane levels were detected in leaves with visible injury symptoms. However, with the appearance of visible injury symptoms, there was a decline in ethylene, acetaldehyde and ethanol emissions. Synthesis of ethylene and ethane seems to be a result of different metabolic pathways. Ethane evolution and its inhibition by antioxidants indicate SO₂-mediated lipid peroxidation by free radical species formed during sulphite oxidation. Perturbation in the cellular respiratory machinery results in the formation of acetaldehyde and ethanol. Since the rates of emissions of ethane, acetaldehyde and ethanol fromplant species were positively correlated to their relative resistance to SO₂, the production of these gases could be used as a reliable diagnostic tool for biomonitoring air pollution (SO₂) stress.Abbreviations ADH alcohol dehydrogenase - NaHSO₃ sodium metabisulphite - O ₂ ^– superoxide radical - OH hydroxyl radical - pO₂ oxygen partial pressure - SO₂ sulphur dioxide - SO ₃ ^– sulphite radical - SOD superoxide dismutase