Influence of air pollution on the mountain forests along the Tateyama–Kurobe Alpine route

The effects of air pollution on the growth of mountain trees were investigated at Buna-daira (1,180 m a.s.l.), about half the way up Mt. Tateyama, located in Japan. Every year, about 1 million tourists are transported by highland buses through the Tateyama–Kurobe Alpine route. Since the route opened in 1971, some tree species along the road have declined and have been blighted, suggesting that bus exhaust was the cause. However, the level of regional and long-range transboundary air pollution has also increased significantly over the last few decades. The atmospheric NO₂ concentration at the roadside in the forest was highly correlated with the traffic density of buses and penetration of the exhaust into the forest was detected. However, the maximum average NO₂ concentration was lower than 3.5 ppbv during the peak traffic period in the year. At Buna-daira, the total stem cross-sectional area at breast height (BA) of the forest was nearly unchanged from 1999 to 2006, but the BA of Fagus crenata decreased 10% and that of Cryptomeria japonica increased 6%. Neither tree growth nor tree death was significantly correlated with distance from the road. The cause of the decline of F. crenata could not be attributed to the effects of road, i.e., air pollution emitted from the buses or edge effects of the road. This area was more affected by regional, long-range transport of air pollution (O₃, SO₂, etc.). The average atmospheric O₃ concentration in autumn was higher than 40 ppbv and the recent increase in the O₃ concentration may be an important factor of F. crenata decline through the changes in the interspecific relationships between F. crenata and C. japonica, O₃ sensitive and tolerant species, respectively.     

Common ragweed (Ambrosia artemisiifolia L.): allergenicity and molecular characterization of pollen after plant exposure to elevated NO2

Ragweed pollen is the main cause of allergenic diseases in Northern America, and the weed has become a spreading neophyte in Europe. Climate change and air pollution are speculated to affect the allergenic potential of pollen. The objective of this study was to investigate the effects of NO₂, a major air pollutant, under controlled conditions, on the allergenicity of ragweed pollen. Ragweed was exposed to different levels of NO₂ throughout the entire growing season, and its pollen further analysed. Spectroscopic analysis showed increased outer cell wall polymers and decreased amounts of pectin. Proteome studies using two‐dimensional difference gel electrophoresis and liquid chromatography–tandem mass spectrometry indicated increased amounts of several Amb a 1 isoforms and of another allergen with great homology to enolase Hev b 9 from rubber tree. Analysis of protein S‐nitrosylation identified nitrosylated proteins in pollen from both conditions, including Amb a 1 isoforms. However, elevated NO₂ significantly enhanced the overall nitrosylation. Finally, we demonstrated increased overall pollen allergenicity by immunoblotting using ragweed antisera, showing a significantly higher allergenicity for Amb a 1. The data highlight a direct influence of elevated NO₂ on the increased allergenicity of ragweed pollen and a direct correlation with an increased risk for human health.     

The relationship between birch pollen,air pollution and weather types and their effect on antihistamine purchase in two Swedish cities

Exposure to elevated air pollution levels can aggravate pollen allergy symptoms. The aim of this study was to investigate the relationships between airborne birch (Betula) pollen, urban air pollutants NO₂, O₃ and PM₁₀ and their effects on antihistamine demand in Gothenburg and Malmö, Sweden, 2006–2012. Further, the influence of large-scale weather pattern on pollen-/pollution-related risk, using Lamb weather types (LWTs), was analysed. Daily LWTs were obtained by comparing the atmospheric pressure over a 16-point grid system over southern Sweden (scale ~3000 km). They include two non-directional types, cyclonic (C) and anticyclonic (A) and eight directional types depending on the wind direction (N, NE, E…). Birch pollen levels were exceptionally high under LWTs E and SE in both cities. Furthermore, LWTs with dry and moderately calm meteorological character (A, NE, E, SE) were associated with strongly elevated air pollution (NO₂ and PM₁₀) in Gothenburg. For most weather situations in both cities, simultaneously high birch pollen together with high air pollution had larger over-the-counter (OTC) sales of antihistamines than situations with high birch pollen alone. LWTs NE, E, SE and S had the highest OTC sales in both cities. In Gothenburg, the city with a higher load of both birch pollen and air pollution, the higher OTC sales were especially obvious and indicate an increased effect on allergic symptoms from air pollution. Furthermore, Gothenburg LWTs A, NE, E and SE were associated with high pollen and air pollution levels and thus classified as high-risk weather types. In Malmö, corresponding high-risk LWTs were NE, E, SE and S. Furthermore, occurrence of high pollen and air pollutants as well as OTC sales correlated strongly with vapour pressure deficit and temperature in Gothenburg (much less so in Malmö). This provides evidence that the combination of meteorological properties associated with LWTs can explain high levels of birch pollen and air pollution. Our study shows that LWTs represent a useful tool for integrated daily air quality forecasting/warning.     

A change from grass pollen induced allergy to tree pollen induced allergy: 30 years of pollen observation in Switzerland

Pollen monitoring with a Hirst like pollen trap for 30 years in Basel, Switzerland allows understanding of the behaviour of the different plants producing allergenic pollens. It becomes evident that in this time period the different tree pollen like Hazel and Birch increased, whereas in the control, the observed amount of a herb pollen like Artemisa did not change. Moreover, it was observed that in the different trees flowering took place earlier namely at the beginning of the year. This was especially impressive for Hazel, where flowering was shifted ofmore than one month. These aerobiological observations were supported and confirmed by some epidemiological studies, showing that tree pollen allergy has become more important in the last years compared to grass pollen allergy and herb pollen allergy. The reason for the increase of tree pollen counts and the shift in the flowering time depends on the observed increase of the annual temperature, an increased input of nutrients like CO₂or NO_x but probably also a real increase of certain trees, like birch for example, in parks and avenues. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of defoliation on grass growth. A quantitative review

This study describes the seasonal patterns of seed and cone abortion in natural Pinus halepensis trees and assesses the effects of pollen quantity, tree size and cone location on seed and cone abortion. The cone-set ratio was similar to the expected value, based on literature on woody perennials. The seed-ovule ratio, however, was almost twice as high as its expected value. The investment in protective cone elements was high and did not vary with the seed-ovule ratio of a cone. Pollination factors influenced cone abortion, as indicated by the high abortion rate at the end of the pollination period. Furthermore, abortive cones had lower pollination rates and lower pollen loads than well developed cones. Effects of resource availability were assessed as effects of tree size and cone position on twigs. Small trees aborted more cones than big trees and cone abortion was higher in apical cones than in basal cones. Abortion in P. halepensis is selective, mediated by both pollen quantity and resource availability. The relative importance of pollen and resources is suggested to be flexible, probably varying between trees and years. The high seed-ovule ratio of P. halepensis is the result of high pollination rate and selective abortion. The selective abortion might be due to the high allocation to protective cone elements relative to the allocation to seeds.     

Cytological mechanism of pollen abortion resulting from allelic interaction of F1 pollen sterility locus in rice (Oryza sativa L.)

Pollen abortion is one of the major reasons causing the inter-subspecific F₁ hybrid sterility in rice and is due to allelic interaction of F₁ pollen sterility genes. The microsporogenesis and microgametogenesis of Taichung 65 and its three F₁ hybrids were comparatively studied by using techniques of differential interference contrast microscopy, semi-thin section light microscopy, epifluorescence microscopy and TEM. The results showed that there were differences among the cytological mechanisms of pollen abortion due to allelic interaction at the three F₁ pollen sterility loci. The allelic interaction at S-a locus resulted in microspores unable to extend the protoplasm membrane with the enlargement of the microspore at the middle microspore stage and finally producing empty abortive pollen. The allelic interaction at S-b locus caused asynchronous development of microspores at the middle microspore stage producing stainable abortive pollen. The allelic interaction at S-c locus mainly led to the non-dissolution of the generative cell wall and finally caused the hybrid F₁ mainly producing stainable abortive pollen. Genotypic identification indicated that the abortive pollen were those with S ^j allele.     

Cyclic variations in nitrogen uptake rate in soybean plants

Uptake of NO₃⁻ by nonnodulated soybean plants (Glycine max L. Merr. cv Ransom) growing in flowing hydroponic culture at 22 and 14°C root temperatures was measured daily during a 31-day growth period. Ion chromatography was used to determine removal of NO₃⁻ from solution during each 24-hour period. At both root-zone temperatures, rate of NO₃⁻ uptake per plant oscillated with a periodicity of 3 to 5 days. The rate of NO₃⁻ uptake per plant was consistently lower at 14°C than 22°C. The lower rate of NO₃⁻ uptake at 14°C during the initial 5 to 10 days was caused by reduced uptake rates per gram root dry weight, but with time uptake rates per gram root became equal at 14 and 22°C. Thereafter, the continued reduction in rate of NO₃⁻ uptake per plant at 14°C was attributable to slower root growth.     

Neighbourhood density and genetic relatedness interact to determine fruit set and abortion rates in a continuous tropical tree population

Tropical trees may show positive density dependence in fruit set and maturation due to pollen limitation in low-density populations. However, pollen from closely related individuals in the local neighbourhood might reduce fruit set or increase fruit abortion in self-incompatible tree species. We investigated the role of neighbourhood density and genetic relatedness on individual fruit set and abortion in the neotropical tree Jacaranda copaia in a large forest plot in central Panama. Using nested neighbourhood models, we found a strong positive effect of increased conspecific density on fruit set and maturation. However, high neighbourhood genetic relatedness interacted with density to reduce total fruit set and increase the proportion of aborted fruit. Our results imply a fitness advantage for individuals growing in high densities as measured by fruit set, but realized fruit set is lowered by increased neighbourhood relatedness. We hypothesize that the mechanism involved is increased visitation by density-dependent invertebrate pollinators in high-density populations, which increases pollen quantity and carry-over and increases fruit set and maturation, coupled with self-incompatibility at early and late stages due to biparental inbreeding that lowers fruit set and increases fruit abortion. Implications for the reproductive ecology and conservation of tropical tree communities in continuous and fragmented habitats are discussed.     

Long-term air pollution exposure and living close to busy roads are associated with COPD in women

Background

Lung function and exacerbations of chronic obstructive pulmonary disease (COPD) have been associated with short-term exposure to air pollution. However, the effect of long-term exposure to particulate matter from industry and traffic on COPD as defined by lung function has not been evaluated so far. Our study was designed to investigate the influence of long-term exposure to air pollution on respiratory symptoms and pulmonary function in 55-year-old women. We especially focused on COPD as defined by GOLD criteria and additionally compared the effects of air pollution on respiratory symptoms by questionnaire data and by lung function measurements.

Methods

In consecutive cross sectional studies conducted between 1985–1994, we investigated 4757 women living in the Rhine-Ruhr Basin of Germany. NO₂ and PM₁₀ exposure was assessed by measurements done in an 8 km grid, and traffic exposure by distance from the residential address to the nearest major road using Geographic Information System data. Lung function was determined and COPD was defined by using the GOLD criteria. Chronic respiratory symptoms and possible confounders were defined by questionnaire data. Linear and logistic regressions, including random effects were used to account for confounding and clustering on city level.

Results

The prevalence of COPD (GOLD stages 1–4) was 4.5%. COPD and pulmonary function were strongest affected by PM₁₀ and traffic related exposure. A 7 μg/m₃ increase in five year means of PM₁₀ (interquartile range) was associated with a 5.1% (95% CI 2.5%–7.7%) decrease in FEV₁, a 3.7% (95% CI 1.8%–5.5%) decrease in FVC and an odds ratio (OR) of 1.33 (95% CI 1.03–1.72) for COPD. Women living less than 100 m from a busy road also had a significantly decreased lung function and COPD was 1.79 times more likely (95% CI 1.06–3.02) than for those living farther away. Chronic symptoms as based on questionnaire information showed effects in the same direction, but less pronounced.

Conclusion

Chronic exposure to PM₁₀, NO₂ and living near a major road might increase the risk of developing COPD and can have a detrimental effect on lung function.     

响应面法优化麻疯树花粉离体萌发培养基的研究

麻疯树因其种子含油率较高,种子油提炼的生物柴油可部分替代汽油,而成为一种极具潜能的能源作物,但由于产量低,麻疯树在热带、亚热带的发展受到极大限制。杂交育种是提高产量的重要手段,杂交亲本花粉生活力的高低直接影响到育种的成效。因此,寻求麻疯树离体花粉萌发的最适培养基配方,探明花粉萌发培养基中各主要培养基成分间的交互作用对生产上麻疯树杂交结实率和种子产量的提高具有重要意义。该研究以麻疯树开花初期雄花上花药刚散粉时的成熟花粉粒为材料,采用Box-Behnken设计(Box-Behnken design,BBD)的响应面法,对麻疯树花粉离体萌发培养基中各主要培养基成分的浓度配比及各主要培养基成分的交互作用进行了研究。以花粉萌发率为响应指标,建立了4种营养成分(蔗糖、硼酸、硝酸钙、硝酸钾)与花粉萌发率的响应面模型,并对各主要培养基成分的浓度配比进行了优化。通过R软件进行响应面分析的结果表明:4因素对花粉萌发率的影响顺序为蔗糖硼酸硝酸钙硝酸钾;蔗糖与硼酸、蔗糖与硝酸钙、蔗糖与硝酸钾之间的交互作用显著。响应面建模优化后的最佳培养基为13.77%蔗糖+32.14 mg·L~(-1)硼酸+22.21 mg·L~(-1)硝酸钙+19.95 mg·L~(-1)硝酸钾+200 mg·L~(-1)硫酸镁,在此条件下的理论萌发率为99.73%。采用此培养基成分配比得到麻疯树花粉离体试验萌发率为98.97%,与理论响应值相吻合,同时也表明利用BBD设计的响应面模型进行麻疯树花粉离体萌发培养条件优化方法的有效性。     

Reduced sulfur compound exchange between the atmosphere and tropical tree species in southern Cameroon

We measured the concentrations of reduced sulfur compounds in the atmospheric boundary layer over an equatorial African rain forest. Results obtained from a dirigible hot air balloon and a tethered balloon system in the early morning hours reflect a multilayered structure of the atmospheric boundary layer with gradients of COS and CS₂ indicating an uptake/production of these trace gases by the soil/vegetation system. In addition, we studied emission and deposition fluxes of volatile reduced sulfur compounds from tropical tree species using cuvettes to directly measure the exchange behavior of tree twigs. These cuvettes were operated at young trees in a forest clearing near ground level as well as at a mature tree species on top of the forest canopy, employing a specially designed tree top jungle raft (Treetop Raft III, Dirigible version) placed on the canopy crown. The results show qualitative and quantitative disparities between different tree species as well as between individuals of the same species near ground level (young) and at the top of the canopy (mature). We found some correlations between photosynthetic CO₂ assimilation and emission of sulfur compounds. Comparison between measurements at the ground and at the canopy top show that the studied tree species adapts its photosynthetic CO₂ assimilation in response to the climatic conditions at the canopy top. This is accompanied by a quantitative change in trace gas emission. Lower CO₂ fixation rates are accompanied by an increase in the emission of reduced sulfur compounds. We propose the increase of DMS emission at the canopy top to be explained by a potential demand of nitrogen in the foliage resulting in an accumulation of sulfur.     

Biomagnetic monitoring of urban air pollution using moss bags (Sphagnum girgensohnii)

Active moss biomonitoring is widely applied in polluted areas for monitoring of airborne particle-bound trace element pollution. This study explored the suitability of the moss Sphagnum girgensohnii for biomagnetic monitoring in cities. To this end S. girgensohnii moss bags were exposed at three different microenvironments characterized by heavy traffic – street canyons, a city tunnel and parking garages during the summer and autumn of 2011 in the city of Belgrade. The ferro(i)magnetic PM fraction in the moss samples was quantified by Saturated Isothermal Remanent Magnetization (SIRM) and the measured values were compared with the trace element concentration in the moss samples. SIRM values were significantly different across the considered urban microenvironments. Moreover, a high correlation between moss SIRM values and concentrations of Al, Ba, Co, Cr, Cu, Fe, Ni and Pb was found. These results demonstrate that moss bags can be effectively applied for biomagnetic monitoring of the spatio-temporal distribution of road traffic and vehicles derived pollutants in urban areas.     

Gibberellic acid impairs fertilization in Clementine mandarin under cross-pollination conditions

We investigated the effect of gibberellic acid (GA₃) in the fertilization of Clementine mandarin cv. ‘Clemenules’ (Citrus clementina Hort. ex Tan.), a parthenocarpic variety that produces seedless fruit due to its self-incompatible nature, but yields seedy fruits when grown under cross-pollination conditions.Experiments were conducted with on-tree ‘Clemenules’ flowers and ‘Fortune’ mandarin pollen (C. clementina Hort. ex Tan. × C. reticulata Blanco), which is sexually compatible with the former. Preanthesis treatment at −2 days after anthesis (−2 DAA) enhanced ovule abortion in both unpollinated and cross-pollinated (at +2 DAA) flowers. In the latter, the number of pollen tubes reaching the ovules was significantly reduced although pollen grains were not treated; thus, fertilization was partially avoided and seed set was reduced. When GA₃ was applied at anthesis (0 DAA) at the time of pollination, ovule abortion was again enhanced, and pollen tube growth was completely arrested; thus, fertilization was prevented and seed set was impeded. When GA₃ was applied 24 h after pollination (+1 DAA in flowers pollinated at anthesis), pollen tube growth was impaired but not arrested and ovule abortion was enhanced; therefore, fertilization was not prevented but impaired.We conclude that, when applied the days around anthesis, GA₃ (10 mg l⁻¹) impairs fertilization by either enhancing ovule abortion or reducing pollen tube growth, in ‘Clemenules’ flowers under cross-pollination conditions. The intensity of the response depends on the physiological flower state at the moment of treatment.     

Spatial variability of NO and NO2 flux rates from soil of spruce and beech forest ecosystems

In order to evaluate differences in the magnitude of NO and NO₂ flux rates between soil areas in direct vicinity to tree stems and areas of increasing distance to tree stems, we followed in 1997 at the Höglwald Forest site with a fully automated measuring system a complete annual cycle of NO and NO₂ fluxes from soils of an untreated spruce stand, a limed spruce strand, and a beech stand using at each stand measuring chambers which were installed onto the soils in such a way that they formed a stem to stem gradient. Flux data obtained since the end of 1993 from measuring chambers placed at the interstem areas of the stands, which had been used for the calculation of the long year annual mean of NO and NO₂ flux rates from soils of the stands, are compared to both (a) those obtained from the interstem chambers in 1997 and (b) those from the stem to stem gradient chambers. Daily mean NO fluxes obtained in 1997 were in a range of 0.3 – 280.1 g NO-N m^–2 h^–1 at the untreated spruce stand, 0.5 – 273.2 g NO-N m^–2 h^–1 at the limed spruce stand and 0.5 - 368.8 g NO-N m^–2 h^–1 at the beech stand, respectively. Highest NO emission rates were observed during summer, lowest during winter. Daily mean NO₂ fluxes were in a range of –83.1 – 7.6 g NO₂-N m^–2 h^–1 at the untreated spruce stand, -85.1 – 2.1 g NO₂-N m^–2 h^–1 at the limed spruce stand and –77.9 to –2.0 g NO₂-N m^–2 h^–1 at the beech site, respectively. As had been observed for the years 1994–1996, also in 1997 NO emission rates were highest at the untreated spruce stand and lowest at the beech stand and liming of a spruce stand resulted in a significant decrease in NO emission rates. For NO₂ no marked differences in the magnitude of flux rates were found between the three different stands. Results obtained from the stem to stem gradient experiments revealed that at all stands studied NO emission rates were significantly higher (between 1.6- and 2.6-fold) from soil areas close to the tree stems and decreased – except at the beech stand - with increasing distance from the stems, while for NO₂ deposition no marked differences were found. Including the contribution of soil areas in direct vicinity to the beech stems in the estimation of the annual mean NO source strength revealed that the source strength has been underestimated by 40% in the past.     

Air Pollution in China: Mapping of Concentrations and Sources

China has recently made available hourly air pollution data from over 1500 sites, including airborne particulate matter (PM), SO₂, NO₂, and O₃. We apply Kriging interpolation to four months of data to derive pollution maps for eastern China. Consistent with prior findings, the greatest pollution occurs in the east, but significant levels are widespread across northern and central China and are not limited to major cities or geologic basins. Sources of pollution are widespread, but are particularly intense in a northeast corridor that extends from near Shanghai to north of Beijing. During our analysis period, 92% of the population of China experienced >120 hours of unhealthy air (US EPA standard), and 38% experienced average concentrations that were unhealthy. China’s population-weighted average exposure to PM_2.5 was 52 μg/m³. The observed air pollution is calculated to contribute to 1.6 million deaths/year in China [0.7–2.2 million deaths/year at 95% confidence], roughly 17% of all deaths in China.     

Histochemical properties and trace element concentrations in <Emphasis Type="Italic">Parietaria L.</Emphasis>from urban sites (Palermo,Italy)

We examined leaf and pollen histochemical properties in Parietaria L. and measured trace element concentrations in urban sites in Palermo, Sicily, affected by different stress valence levels. Urban pollution affects histochemistry macro-, micro-, and toxic element concentrations in Parietaria. We therefore decided to determine whether this plant can be used as a simple biomonitor or bioaccumulator of pollution contaminants. Samples were collected at various sites in different periods. An increase in phenolic compound levels was a result of the impact of pollution. Histochemical characteristics and trace element concentrations varied according to the period, but not to the place, of sampling. Pollutant concentrations were the highest in the month of February 2002. Trace metal concentrations were the lowest in July. Our investigations have confirmed that Parietaria L. can be used to study the effects of trace elements in the atmosphere in urban sites; in fact, they are veritable accumulators, given that elevated levels of pollutants can be found on their structures with no visible morphological effects. There are differences in accumulation capacity according to the trace elements studied. Pollution alters the content of phenolic compounds and chemical elements in Parietaria L.     

Canopy throughfall of Picea abies (L.) Karst. as depending on trace gas concentrations

At six sites in central Germany consequences of SO₂, NO_X and O₃ deposition and of acid precipitation on canopy throughfall of sulphate, nitrate, ammonium, organic acids and of metal cations from Norway spruce crowns were investigated in the field. Measured canopy throughfall rates (mmol ion kg^-1 needle dw a^-1 are separated in (i) background ion throughfall rates in clean air and (ii) trace gas-(or acid interception)-dependent throughfall rates at ambient trace gas concentrations. Based on synchronously measured pollution, precipitation and canopy throughfall data, statistical response functions are given, which allow the separate estimation of annual rates of sulphur and nitrogen deposition into spruce canopies if only annual means of SO₂ or NO₂ concentrations in air are known. The specific SO₂ deposition rate of (0.841±0.214) mmol S kg^-1 needle dw a^-1 (nPa SO₂ Pa^-1)^-1 is 2.3 times higher than the specific stomatal SO₂ uptake. The NO₂-dependent nitrogen deposition of (2.464±0.707) mmol N kg^-1 needle dw a^-1 (nPa NO₂ Pa^-1)^-1 is 2.2 times higher than the specific stomatal NO_X (NO₂+NO) uptake. These ratios (2.32.2) are explained by the percentage of annual hours with open needle stomata. The shape of observed epicuticular SO₂ and NO_X deposition curves and of stomatal SO₂ and NO_X uptake curves are congruent. As for stomatal NO_X uptake, there is an apparent compensation point at (5 to 8) nPa NO₂ Pa^-1. There is significant SO₂-dependent canopy throughfall of Ca>K>Al>Mg>Fe in this order of relative importance. NO_X deposition in spruce canopies reduces K⁺ throughfall and it weakly promotes throughfall of Mn²⁺ and Zn²⁺. There was no significant codeposition of sulphate and ammonium and no ion exchange of intercepted H₃O⁺ with nutrient cations at the measured ambient pH values of the precipitation water. In the presence of O₃, throughfall of Mn²⁺ is reduced and throughfall of K⁺, Ca²⁺ and Al³⁺ is enhanced. In the cooperative presence of SO₂, NO₂ and O₃ pollution in the field there is a 1.3-fold increase of the annual K⁺ demand and a 1.5-fold Mg²⁺ demand of spruce canopies relative to the situation in clean air. This trace gas-dependent additional cation demand of spruce canopies corresponds to a needle loss percentage of (23 to 33)% if the additional K⁺ and Mg²⁺ throughfall could not be recycled in spruce ecosystems. Observed canopy thinning ranges from (13 to 26)% at the investigated six spruce stands.Abbreviations A_spec Specific needle surface area per kg needle dry matter (m²kg^-1 needle dw) - A_tot Total needle surface of spruce stands (ha ha^-1) - [gas]_a Ambient trace gas concentration (gas=SO₂; NO₂ or O₃) in air (nPa Pa^-1=ppb) - GP Number of days per annual growth period d a^-1) - IC_H30 ⁺ Acid interception rate (Eq H₃O⁺ kg^-1 needle dw a^-1) - k_o Trace gas-independent ion throughfall rate constant (mmol kg^-1 needle dw a^-1) - k_gas SO₂-,NO₂-or O₃-dependent ion throughfall rate per unit of trace gas pollution (mmol kg^-1 needle dw a^-1 (nPa Pa^-1)^-1) - k_H30 Specific H₃O⁺/Me⁺ exchange ratio (mol mol^-1) - L_o Background throughfall rate at [gas]_a=0 (mmol kg^-1 needle dw a^-1) - L_ion Canopy throughfall rate of ions (mmol kg^-1 needle dw a^-1) - L'_ion Trace gas dependent ion throughfall (mEq kg^-1 needle dw a^-1 (nPa Pa^-1)^-1) - LAI Leaf area index of the canopy (m² projected needle surface m^-2 ground) - Me⁺ Equivalents of metal cations (Eq) - N Stock of needles of spuce stands in the field (kg needle dw ha^-1) - P_% Percentage of needle loss relative to a healthy reference (%) - r Pearson correlation coefficient (no dimension) - R COO^--Sum of all organic anion equivalents Cat⁺ - An^- (Eq kg^-1 needle dw a^-1) - An^- Sum of all measured inorganic anion equivalents (Eq kg^-1 needle dw a^-1) - Cat⁺ Sum of all measured inorganic cation equivalents (Eq kg^-1 needle dw a^-1)     

Air pollution effects on structure,proteins and flavonoids in pollen grains of Thuja orientalis L. (Cupressaceae)

Increase in the levels of air pollution due to the increase in industrial and agricultural technology has prompted investigation of mechanisms that contribute to air pollution tolerance in plants. Pollen grains of Thuja orientalis were collected from controlled (less polluted) and polluted areas (mainly SO₂, NO₂, CO, HC and APM). Thuja pollen is considered inaperturate and granulate. The exine is shed during rehydration, leaving the male gametophyte naked. The pollen grains collected from polluted areas are smaller and more fragile compared to control ones. The exine splitting is faster and higher in polluted pollen grains. SDS–PAGE (sodium dodecyl sulphate-polyacrylamide gel electrophoresis) pattern do not show significant differences in polluted pollen than those in the control group. HPLC (high pressure liquid chromatography) analysis demonstrates that air pollution induces flavonoids accumulation to significantly higher levels in polluted pollen than in controlled ones. These observations suggest that plants try to respond suitably by adjusting their metabolism so that minimum damage is done due to air pollutants. Their protective responses may include an increase in antioxidant enzymes and metabolites and induction of protection-related secondary metabolite genes especially flavonoids.     

基于ENVI-met的城市道路绿地植物配置对PM2.5的影响研究

随着城市化的快速发展,大气污染尤其细颗粒物(PM_2.5)已成为制约城市环境的重要因素,相关研究表明,在众多的PM_2.5来源中道路交通是在其中的重要来源之一,而道路绿地植物群落能够消减来自道路的PM_2.5。运用场地观测和ENVI-met模拟相结合的方法探讨城市道路绿地植物群落对PM_2.5的影响,分析仅有乔木(i)、乔木+树篱(ii)、乔木+树篱+灌木(iii)3种模式下的植物群落配置对PM_2.5的影响,揭示绿地植物群落的长度、宽度、高度和LAI对PM_2.5的影响。结果表明:(1)场地观测中的道路绿地植物群落的3种配置模式对PM_2.5的消减率分别是iii(14.2%)>ii(12.9%)>i(9.2%)。(2)绿地中植物的种类、绿地宽度、绿地植物的叶面指数等要素对消减作用起正面作用,高度和长度起负面作用。(3)绿地的长度的一定量的减少可以在绿地后方形成一个宽度约为绿地长度80%的、随着与绿地的距离的增加而宽度递减的较绿地长度更...