Investigation of Ground-Level Ozone and High-Pollution Episodes in a Megacity of Eastern China

Differential Optical Absorption Spectroscopy (DOAS) was used for the long-term observation of ground-level ozone (O₃) from March 2010 to March 2013 over Shanghai, China. The 1-hour average concentration of O₃ was 27.2 ± 17.0 ppbv. O₃ level increased during spring, reached the peak in late spring and early summer, and then decreased in autumn and finally dropped to the bottom in winter. The highest monthly average O3 concentration in June (41.1 ppbv) was nearly three times as high as the lowest level recorded in December (15.2 ppbv). In terms of pollution episodes, 56 hourly samples (on 14 separate days) in 2010 exceeded the 1-hour ozone limit of 200 μg/m³ specified by the Grade II of the Chinese Ambient Air Quality Standards (CAAQS, revised GB 3095-2012). Utilizing the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, the primary contribution to high ozone days (HODs) was identified as the regional transportation of volatile organic compounds (VOC) and high concentrations of O₃ from the chemical industrial zone in the Jinshan district of Shanghai. HODs showed higher concentrations of HONO and NO₂ than non-episode conditions, implying that HONO at high concentration during HODs was capable of increasing the O₃ concentration. The photolysis rate of HONO was estimated, suggesting that the larger number of OH radicals resulting from high concentrations of HONO have a considerable impact on ozone concentrations.     

A possible approach to the investigation of reacting sites of ozone in rat lung

As edematogenic agents, thiocarbamides and ozone share several pharmacological and toxicological features in common. In view of these striking similarities, an attempt was made to find out whether or not thiocarbamides and ozone interact with the same cellular constituents of the lungs. This was accomplished by incubating first, a constant amount of ¹⁴C-thiourea with lung slices of O₃-tolerant and control rats followed by subcellular fractionation and radio-activity determination. The results of this study reveal a substantial and significant reduction in binding of ¹⁴C-thiourea to all sub-cellular fractions of lungs of O₃-tolerant rats as compared to the rats exposed to ambient air. The data suggest that repeated exposure to a progressively increasing concentration of ozone inhibits ¹⁴C-thiourea binding in the lung by reducing binding sites by directly destroying binding sites or via an effect on cell population.     

Long-term ozone effects on vegetation, microbial community and methane dynamics of boreal peatland microcosms in open-field conditions

To study the effects of elevated ozone concentration on methane dynamics and a sedge species, Eriophorum vaginatum, we exposed peatland microcosms, isolated by coring from an oligotrophic pine fen, to double ambient ozone concentration in an open‐air ozone exposure field for four growing seasons. The field consists of eight circular plots of which four were fumigated with elevated ozone concentration and four were ambient controls. At the latter part of the first growing season (week 33, 2003), the methane emission was 159±14 mg CH₄ m^?2 day^?1 (mean±SE) in the ozone treatment and 214±8 mg CH₄ m^?2 day^?1 under the ambient control. However, towards the end of the experiment the ozone treatment slightly, but consistently, enhanced the methane emission. At the end of the third growing season (2005), microbial biomass (estimated by phospholipid fatty acid biomarkers) was higher in peat exposed to ozone (1975±108 nmol g^?1 dw) than in peat of the control microcosms (1589±115 nmol g^?1 dw). The concentrations of organic acids in peat pore water showed a similar trend. Elevated ozone did not affect the shoot length or the structure of the sedge E. vaginatum leaves but it slightly increased the total number of sedge leaves towards the end of the experiment. Our results indicate that elevated ozone concentration enhances the general growth conditions of microbes in peat by increasing their substrate availability. However, the methane production did not reflect the increase in the concentration of organic acids, probably because hydrogenotrophic methane production dominated in the peat studied. Although, we used isolated peatland microcosms with limited size as study material, we did not find experimental factors that could have hampered the basic conclusions on the effects of ozone.     

Acute and chronic toxicity of the pesticide methyl parathion to the rotifer Brachionus angularis (Rotifera) at different algal (Chlorella vulgaris) food densities

Methyl parathion is a commonly used insecticide in Mexico to eradicate insect pests. We evaluated the effects of this insecticide on rotifer B. angularis using both acute and chronic toxicity tests. Median lethal concentration (LC₅₀) of methyl parathion for B. angularis for a 24-h bioassay in the presence and absence of an algal diet was derived. Elevated LC₅₀ due to the survival of a greater number of test individuals in the presence of food was observed. Regardless of the toxicant concentration, population growth curves of the animals maintained at the low food level (0.75×10⁶ cells ml^-1) had a longer lag phase than those at the high food level (1.5×10⁶ cells ml^-1). Regardless of food level, an increase in the toxicant concentration in the medium resulted in decreased population growth. The lowest peak population density (50 ind. ml^-1) was observed at the highest toxicant concentration and the lower food level. The highest population density (200 ind. ml^-1) was observed in the controls at high food level. The rates of population increase per day (r) in the controls were higher (from 0.14 to 0.37 depending on the food level). Irrespective of food level, there was a decrease in the r values with increasing pesticide concentration in the medium. In order to detect the effect of population density on the growth rates in relation to the toxicant stress, we plotted the daily growth rate against initial density for the entire duration of the experiment. We observed the existence of a significantly inverse relation at all treatments except at the low food level and high toxicant concentrations (0.625 and 1.25 mg l^-1). We discuss the role of algae in the toxicity of methyl parathion to zooplankton.     

The reactions of susceptible and resistant tomato cultivars to strains of Verticillium albo-atrum

Three strains of Verticillium albo-atrum causing severe wilt of tomato (T), progressive (Hp ) and fluctuating (HF) wilt of hop, were inoculated through the roots of four tomato cultivars at different inoculum concentrations. Symptoms were assessed visually 42 days after inoculation, and quantitatively on the change in total leaf area compared with controls. Distribution of mycelium and tyloses was determined by sections at 2 cm intervals of root, stem and petiole. Cultivars Loran Blood and Moscow showed resistance to disease expression at all levels of inoculum concentration with the T strain. Bonny Best and Potentate were both susceptible to this strain, but whereas in Potentate, disease severity increased from mild to severe with increase in inoculum concentration, Bonny Best was severely diseased at the lowest level of inoculum. All cultivars showed some susceptibility to the HP and HF strains; the ‘resistance’ of Loran Blood and Moscow was no longer apparent and Bonny Best was most severely affected. The relative susceptibilities to the strains were HF Bonney Best > Loran Blood > Potentate > Moscow, HP Bonny Best > Loran Blood, Moscow > Potentate, T Bonny Best > Potentate > Loran Blood, Moscow. In general, vascular colonization was less in the cultivars Loran Blood and Moscow with all three fungal strains at io⁵propagules/ml level of inoculum, but this was not always correlated with an increase in disease severity. With the exception of the host-pathogen combinations Bonny Best/T, Bonny Best/HF, Potentate/T and Moscow/T, increasing the inoculum concentration to 10⁷propagules/ml increased disease severity but had little or no effect of increasing vascular colonization. In Bonny Best/T, Bonny Best/HF and Potentate/T vascular colonization was reduced with the higher level of inoculum. Moscow showed complete resistance to symptom expression and little vascular colonization with the T strain at 10⁵prop./ml. At 10⁷prop./ml resistance was maintained but there was very extensive growth of mycelium in the vessels. Tylosis resulted from an interaction of host, fungal strain and the level of inoculum and was not always correlated with the degree of vascular colonization. Contrary to previous reports the resistant varieties Loran Blood and Moscow developed acute disease symptoms after inoculation with HP and HF and these were associated with a high level of tylosis rather than mycelial growth. Tylosis and disease severity but not mycelial growth increased with higher levels of inoculum. The results suggested that susceptibility to Verticillium wilt was a complex response depending on host cultivar, fungal strain and the initial inoculum concentration. In some cultivar-pathogen combinations susceptibility was directly proportional to the amount of mycelium present in the vessels, while in others a physiological resistance mechanism independent of the degree of colonization appeared to operate. In a third category, increased disease development rather than resistance was associated with high levels of tylosis.     

Effects of elevated CO2 on the protein concentration of food crops: a meta-analysis

Meta‐analysis techniques were used to examine the effect of elevated atmospheric carbon dioxide [CO₂] on the protein concentrations of major food crops, incorporating 228 experimental observations on barley, rice, wheat, soybean and potato. Each crop had lower protein concentrations when grown at elevated (540–958 μmol mol^?1) compared with ambient (315–400 μmol mol^?1) CO₂. For wheat, barley and rice, the reduction in grain protein concentration was ～10–15% of the value at ambient CO₂. For potato, the reduction in tuber protein concentration was 14%. For soybean, there was a much smaller, although statistically significant reduction of protein concentration of 1.4%. The magnitude of the CO₂ effect on wheat grains was smaller under high soil N conditions than under low soil N. Protein concentrations in potato tubers were reduced more for plants grown at high than at low concentrations of ozone. For soybean, the ozone effect was the reverse, as elevated CO₂ increased the protein concentration of soybean grown at high ozone concentrations. The magnitude of the CO₂ effect also varied depending on experimental methodology. For both wheat and soybean, studies performed in open‐top chambers produced a larger CO₂ effect than those performed using other types of experimental facilities. There was also indication of a possible pot artifact as, for both wheat and soybean, studies performed in open‐top chambers showed a significantly greater CO₂ effect when plants were rooted in pots rather than in the ground. Studies on wheat also showed a greater CO₂ effect when protein concentration was measured in whole grains rather than flour. While the magnitude of the effect of elevated CO₂ varied depending on the experimental procedures, a reduction in protein concentration was consistently found for most crops. These findings suggest that the increasing CO₂ concentrations of the 21st century are likely to decrease the protein concentration of many human plant foods.     

Distinct responses to ozone of abaxial and adaxial stomata in three Euramerican poplar genotypes

Ozone induces stomatal sluggishness, which impacts photosynthesis and transpiration. Stomatal responses to variation of environmental parameters are slowed and reduced by ozone and may be linked to difference of ozone sensitivity. Here we determine the ozone effects on stomatal conductance of each leaf surface. Potential causes of this sluggish movement, such as ultrastructural or ionic fluxes modification, were studied independently on both leaf surfaces of three Euramerican poplar genotypes differing in ozone sensitivity and in stomatal behaviour. The element contents in guard cells were linked to the gene expression of ion channels and transporters involved in stomatal movements, directly in microdissected stomata. In response to ozone, we found a decrease in the stomatal conductance of the leaf adaxial surface correlated with high calcium content in guard cells compared with a slight decrease on the abaxial surface. No ultrastructural modifications of stomata were shown except an increase in the number of mitochondria. The expression of vacuolar H⁺/Ca²⁺‐antiports (CAX1 and CAX3 homologs), β‐carbonic anhydrases (βCA1 and βCA4) and proton H⁺‐ATPase (AHA11) genes was strongly decreased under ozone treatment. The sensitive genotype characterized by constitutive slow stomatal response was also characterized by constitutive low expression of genes encoding vacuolar H⁺/Ca²⁺‐antiports.     

Variable growth and reproduction response of the spruce shoot aphid, Cinara pilicornis, to increasing ozone concentrations

Spruce shoot aphid, Cinara pilicornis Hartig (Homoptera: Lachnidae), is an aphid species that has shown enhanced performance on trees exposed to SO₂ or mixtures of air pollutants, whereas results with ozone have been contradictory. Using a 4-week chamber fumigation experiment, we tested how different population dynamic parameters of aphids are affected by ozone (O₃). Mean relative growth rate (MRGR), development time and reproduction rate of C. pilicornis were determined using 7h day-time O₃ concentrations of 0, 40, 80 and 160 ppb. Development period from birth to reproductive stage was fastest at 80 ppb during early shoot elongation, while reproduction and intrinsic rate of population increase was not significantly affected by ozone concentration. There was a significant negative correlation between ozone concentration and the MRGR of first instar nymphs in the third fumigation week. In feeding test performed on seedlings after fumigation, the MRGR was reduced on shoots which had been exposed to 80 ppb O₃. The results suggest that elevated O₃ concentration during early shoot elongation period may stimulate population development of C. pilicornis, but on maturing shoots, high O₃ concentration has a negative effect on aphid performance. This might be due to accelerated ageing of O₃ exposed shoots.     

休眠卵孵化对策与食物浓度对萼花臂尾轮虫(Brachionus calyciflorus)两品系干雌体种群增长的影响

周期性孤雌繁殖的轮虫靠休眠卵度过不良环境,等环境适宜时休眠卵孵化出干雌体,再次通过孤雌繁殖建立种群。通常休眠卵要经历一段休眠期再孵化,但也有些休眠卵生成后很快孵化,称为早孵化现象。有关休眠卵不同孵化对策如何影响其干雌体克隆种群的增长,目前尚不清楚。分别观测了萼花臂尾轮虫（Brachionus calyciflorus）的两个品系H1（窄温度生态位）和D1（宽温度生态位）的休眠卵在不同孵化对策和不同食物浓度下所生产的干雌体克隆群的种群增长差异。孵化对策包括早孵化（early hatching,EH）和晚孵化（late hatching,LH）;食物浓度包括高食物浓度（high food concentration,HF：2×10⁶个细胞/mL）和低食物浓度（low food concentration,LF：5×10⁵个细胞/mL）,每个品系下各设置4个实验组（LH-HF、LH-LF、EH-HF、EH-LF）,每组10个重复。结果发现,对D1品系来说：孵化对策和食物浓度对最大种群数量具有显著的综合影响（P=0.002）,但两因素间不存在交互作用（P=0.911）;早孵化的干雌体种群在最大种群数量上显著高于晚孵化的干雌体种群（P=0.001）。对H1品系：孵化对策和食物浓度对最大种群数量综合影响显著（P<0.001）,且两个因素之间存在交互作用（P<0.001）;高食物浓度下,EH干雌体克隆群的最大种群数量显著低于LH干雌体克隆群（P<0.001）。高食物浓度下干雌体克隆群开始有性生殖的密度阈值,D1品系EH组显著高于LH组（P=0.041）;而H1品系EH组却显著低于LH组（P=0.022）。最高种群密度下,H1品系的有性生殖率在两种孵化对策之间存在显著差异（P=0.044）,EH种群的有性生殖率低于LH种群,而D品系却未见有性生殖率在不同孵化对策间存在明显差异。本研究结果显示休眠卵的孵化对策会影响其后代干雌体种群的增长特性,其影响的结果可能与种群的生境适应相关。     

Inoculum Density-Dependent Mortality and Colonization of the Phyllosphere by Pseudomonas syringae

Pseudomonas syringae inocula containing cell concentrations ranging from 10⁵ to 10⁹ cells per ml were applied to the primary leaves of bean plants. The plants were incubated under conditions of high temperature and illumination and low relative humidity. Bacterial mortality rates and the proportional population decline of the inoculum were lowest at the highest inoculum concentrations. Addition of a high concentration of heat-killed cells to the inoculum containing a low concentration of viable cells significantly reduced both the mortality rate and the proportional population decline of the viable cells. The mechanisms underlying this density-dependent mortality may include cooperative protective effects of extracellular factors, such as bacterial extracellular polysaccharides, and physical protection by neighboring cells. Although epiphytic populations derived from inoculum concentrations of 10⁸ or 10⁹ cells per ml tended toward 10⁶ CFU/g, the presumed carrying capacity of the leaf, populations derived from lower inoculum concentrations never achieved this carrying capacity. Assuming that epiphytic populations of P. syringae reside in discrete protected sites, our results suggest that at low inoculum concentrations, following a period of environmental stress, the number of viable cells may have dropped to zero in some sites; hence, the carrying capacity of the leaf could not be achieved.     

The role of low-level ozone exposure and mycorrhizas in chemical quality and insect herbivore performance on Scots pine seedlings

The effects of low‐level ozone exposure and suppression of natural mycorrhizas on the above‐ground chemical quality of Scots pine (Pinus sylvestris L.) needles and insect herbivore performance were studied in a two‐year field experiment. Seedlings were fumigated with the ozone doses 1.5–1.7 times the ambient, and natural mycorrhizal infection level was about 35% reduced in roots with fungicide propiconazole. On ozone‐exposed seedlings the mean relative growth rate (MRGR) of Lygus rugulipennis Popp. nymphs was lower than on ambient ozone seedlings, but Gilpinia pallida Klug sawfly larvae grew better on elevated ozone seedlings than on ambient ozone seedlings. MRGR of Schizolachnus pineti Fabr. and Cinara pinea L. aphid nymphs or Neodiprion sertifer Geoffr. sawfly larvae or the oviposition of L. rugulipennis and N. sertifer were not affected by ozone exposure. Although ozone exposure did not affect total phenolics, total terpene, total or individual resin acid, total free amino acid, nutrient or sugar concentrations in needles, MRGR of L. rugulipennis positively correlated with total terpenes and MRGR of G. pallida positively with total amino acids. In addition, ozone exposure increased serine and proline concentration and marginally also starch concentration in needles. When mycorrhizas were reduced with fungicide, only MRGR of L. rugulipennis nymphs increased, but performance of other insect herbivores studied was not changed. However, number of L. rugulipennis eggs correlated positively with mycorrhizal infection level and also with total sugars. Reduction of mycorrhizas did not strongly affect the concentrations of analysed compounds in needles, because only phosphorus and potassium and some individual resin acids were reduced by fungicide treatment. These results suggest that low‐level ozone exposure and moderately declined mycorrhizal infection do not drastically affect either the above‐ground chemical quality of Scots pine seedlings or performance of studied insect herbivores.     

An ozone response relationship for four Phleum pratense genotypes based on modelling of the phytotoxic ozone dose (POD)

In the last decade extensive research has focused on the development of dose–response relationships based on stomatal plant ozone uptake (phytotoxic ozone dose, POD). So far most work has concentrated on crops and forest trees. This study provides a flux-based dose–response function for timothy (Phleum pratense), a widespread grassland species, which can be used in risk assessment for ground-level ozone. In 1996 and 2001 timothy was exposed in open-top chambers to ozone concentrations ranging from around 10 nmol mol⁻¹ in the charcoal filtered treatments up to 60 nmol mol⁻¹ in the fumigated treatments (08:00–20:00) in. In 1996 there was a negative effect of ozone on biomass production in the non-filtered treatment while in 2001 no such ozone effect in the non-filtered treatment could be seen. Measurements of stomatal conductance on four timothy genotypes in 2001 were used to calibrate a Jarvis-type multiplicative stomatal conductance model. The maximum conductance varied between the genotypes, from 477 to 589 mmol O₃ m⁻² s⁻¹ (projected leaf area). The model includes functions describing the reduction of stomatal conductance of senescing leaves and the direct effects on stomatal conductance by light, temperature and water vapour pressure deficit. A function describing ozone induced senescence of the leaves was included since exposure to ozone is known to cause premature senescence. The function for ozone was applied when it suggested ozone to be more limiting to stomatal conductance than phenology. To avoid overestimation of stomatal conductance in days with high VPD, a function reflecting the effect on leaf water potential on stomatal conductance was included. Comparison between modelled and measured conductance for the four timothy genotypes resulted in an r² value at 0.57 and a very small average deviation of observed from modelled values. The calibrated stomatal conductance model was used to estimate the accumulated POD, i.e. the accumulated stomatal flux of ozone, of the plants in the 1996 and 2001 experiments. The strongest relationship between ozone relative effects on biomass was obtained when POD was accumulated from 105 degree days after emergence to 1000 degree days after emergence, and integrated using an uptake rate threshold of 7 nmol m⁻² s⁻¹ (POD₇). The response relationship between biomass and POD₇ resulted in an r² value of 0.71 over all four genotypes. This r² value was somewhat higher than for the corresponding relationship based on the accumulated ozone exposure over 40 nmol mol⁻¹ (AOT40; r² = 0.66). With an uptake rate threshold at 7 nmol m⁻² s⁻¹, ozone concentrations above ∼20 nmol mol⁻¹, contribute to reduce the biomass production of timothy if meteorological conditions promote maximum stomatal conductance.     

Identification of Regions with High Ozone Concentrations Aiming the Impact Assessment on Childhood Asthma

High concentrations of near-surface ozone are known to have negative impacts on human health, especially among risk groups such as persons with respiratory problems, children, and the elderly. The aim of this work was to identify regions with high ozone concentrations and very low concentrations of other pollutants, where further studies will be performed regarding the specific impact of ozone on childhood asthma. For that, the concentrations of ozone and of its precursors at remote areas were assessed and compared with those observed at an urban area influenced by traffic. Measurements using passive samplers were compared with those performed with continuous monitors and it was possible to conclude that measurements with passive samplers had satisfactory reproducibility and precision. For O₃, the comparison of both methods showed a maximum absolute difference of +4.10 μ g.m^?3 and relative differences lower than ?8.8%. The maximum absolute difference for NO₂ was +5.2 μ g.m^?3 and the relative differences were greater than 12% only for very low concentrations (2–3 μ g.m^?3). Comparing with one urban site, the results obtained at remote sites showed significantly lower concentrations of nitrogen dioxide (12 to 20 times) and volatile organic compounds (2 to 8 times) and greater ozone concentrations (2 to 3 times). It was inferred that the lower concentrations of nitrogen dioxide were the main reason for the greater ozone concentrations found at the remote sites. The remote areas studied showed very high ozone concentrations and very low concentrations of other pollutants, being an adequate zone to perform further studies regarding the specific impact of ozone on childhood asthma without the confounding effects of other pollutants.     

Medico-genetic characteristics of the Udegey in the Maritime Territory

The results of medico-genetical investigation of Udegey population of Primorski territory were described. These studies were carried out by Moscow Institute of Medical Genetics. Marriage structure of population investigated was studied which demonstrated a low level of inbreeding and high frequency of intranational marriages. The structure of population morbidity was characterized by the absence of accumulation of specific hereditary pathology. Data obtained are of great interest for comparative analysis of populations of a different marriage structure.     

不同秧苗素质和移栽密度条件下臭氧胁迫对水稻光合作用、物质生产和产量的影响

近地层臭氧浓度升高使水稻生长受抑进而使产量下降,但这种影响是否因不同栽培条件而异尚不清楚。2011年依托先进的稻田臭氧FACE(Free Air gas Concentration Enrichment)技术平台,以汕优63为供试材料,臭氧设置大气臭氧浓度(Ambient)和高臭氧浓度(比Ambient高50%),秧苗素质设置弱苗(移栽时无分蘖)和壮苗(移栽时带两个分蘖),移栽密度设置低密度(16穴/m2)、中密度(24穴/m2)和高密度(32穴/m2),研究不同秧苗素质和移栽密度条件下臭氧胁迫对水稻生长和产量的影响。结果表明:高浓度臭氧使水稻结实期叶片SPAD值、净光合速率、气孔导度和蒸腾速率明显下降,但胞间CO2浓度和叶温无显著变化。高浓度臭氧对水稻拔节前物质生产量没有影响,但使拔节至抽穗期、抽穗至成熟期物质生产量平均分别降低13%和29%,进而使成熟期生物产量和籽粒产量均显著下降。方差分析表明,臭氧与秧苗素质间没有互作效应,但臭氧与移栽密度的互作对最终产量的影响达显著水平。以上结果表明,臭氧胁迫使水稻生长后期光合受阻,导致物质生产和产量显著下降;适当增加移栽密度可能会减少臭氧胁迫下水稻产量的损失。     

Effect of ozone on spore germination,spore production and biomass production in two <Emphasis Type="Italic">Aspergillus</Emphasis> species

The ability of ozone gas to reduce food spoilage is relatively well documented, but the developmental effects of the gas on food spoilage fungi are not well known. In this study two model aspergilli, Aspergillus nidulans and Aspergillus ochraceus were used to study the effects of ozone on spore germination, sporulation and biomass production. These effects were examined under three levels of ozone; two high level ozone exposures (200 and 300 μmol mol⁻¹) and one low level exposure (0.2 μmol mol⁻¹). The two species behaved noticeably different to each other. Ozone was more effective in reducing growth from spore inocula than mycelia. No spore production could be detected in A. nidulans exposed to continuous low level O₃, whereas the same treatment reduced spores produced in A. ochraceus by 94%. Overall the work suggests that ozone exposure is an effective method to prevent spread of fungal spores in a food storage situation.     

Female preference in complex acoustical environments in the midwife toads Alytes obstetricans and Alytes cisternasii

Gravid females of Alytes obstricans and Alytes cisternasii weretested with synthetic calls in seven-speaker playback tests.A first, "mean-centered" test presented calls with frequenciesrepresenting an array of different calls spanning over the rangeof the population (±2.25 SD). In this test, females ofboth species approached a synthetic call that was lower thanthe average call frequency of the male population although thedifference was significant only for A. obstetricans. The regressionbetween female weight and size and preferred frequency was notsignificant in either species. These results confirm the reportedtrends of females preferring lower frequency calls (correspondingto larger males) based on two-speaker playback tests for A.obstetricans. For A. cisternasii, the lack of significance ofthe seven-speaker test suggests that the preference trend previouslyfound in two-speaker tests may be obscured in more complex acousticalenvironments. A second "supernormal stimulus" test presentedfemales with calls ranging from the lowest frequency valuesof the male population (–2.25 SD) and lower, up to –6.75SD beyond the range. In both species females preferentiallyapproached calls higher than the mean frequency of the stimuluspresented. This result suggests that in both cases selectionfor low frequencies is not open ended, and that the preferredfrequency is within the range of the male population.     

Growth and reproduction of aphids and levels of free amino acids in Scots pine and Norway spruce in an open-air fumigation with ozone

To estimate the susceptibility of conifer seedlings to aphids under future tropospheric ozone levels, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings were exposed to ambient and elevated ozone levels in an open-air exposure system. Growth and reproduction of the aphids Schizolachnus pineti and Cinara pinea on Scots pine and Cinara pilicornis on Norway spruce were monitored. Levels of free amino acids in foliage and young shoots were used as indicators of host plant quality. In elevated treatment plots the ozone doses were between 1.2 and 1.7 times the dose in ambient plots in 1990–93. Half of the seedling material in 1992–93 was subjected to nitrogen fertilization treatment to evaluate the effects of increased N deposition. In 1990, population density of S. pineti on pine did not differ between ambient and elevated ozone treatments during growing season, but remained higher in the elevated ozone plot than in the ambient plot at the end of the growing season. This was associated with elevated levels of glutamic acid in foliage. In August 1992, the numbers of S. pineti were consistent between the two ambient ozone plots, but deviated highly between the two ozone-fumigated plots. Glycine concentration in pine foliage was elevated by ozone, but free amino acid concentrations were not related to aphid performance. In 1993, ozone and nitrogen did not significantly affect the relative growth rate (RGR) of S. pineti or C. pinea nymphs on Scots pine, but glutamic acid concentration in foliage was increased by nitrogen fertilization. On Norway spruce, fecundity of C. pilicornis females was higher in elevated ozone treatment, but RGR of nymphs was not affected in 1992. In 1993, RGR of C. pilicornis nymphs was increased by nitrogen fertilization in June, but not affected by ozone. Nitrogen fertilization increased the levels of total free amino acids, aspartic acid, glutamic acid and proline in elongating shoots of Norway spruce, and ozone reduced the concentrations of valine and γ-butyric acid. Our results suggest that availability of nitrogen from soil has a stronger impact on the concentrations of free amino acids in conifer seedlings than ozone. Some episodes of high ozone concentration may increase free amino acids in foliage. Aphid response to ozone was extremely variable, in agreement with previous laboratory experiments. The expected 20–70% increase in ambient concentrations of tropospheric ozone may in some occasions enhance aphid performance on Scots pine and Norway spruce seedlings, but in most cases the ozone effect on the susceptibility of conifer seedlings to sucking insect pests is not important.     

Development of human health damage factors for tropospheric ozone considering transboundary transport on a global scale

Purpose

Air pollutants such as tropospheric ozone and PM_2.5 travel through large areas. The damage factors (DFs) presented by existing researches in life cycle impact assessment do not take into consideration transboundary movement. A previous study used a global chemistry transport model (CTM), to develop health damage factors for ten different regions around the world by considering the transboundary movement of PM_2.5. Under the same assessment procedure, this research is designed to calculate the ozone DFs by region and to find the effects of wide range movement on the DFs.

Methods

The DFs by regions are defined as changes in disability-adjusted life years (DALYs) derived from changes in tropospheric ozone concentration around the world which is induced by an increase in emissions of the unit amount of nitrogen oxides (NO_x) and non-methane volatile organic compounds (NMVOC). DFs for ten regions are calculated as follows. Firstly, the concentration change of worldwide ozone caused by a change in emission of a substance from one region is estimated with a global scale CTM for both NO_x and NMVOC. Secondly, DALY changes on the world due to a change in concentration of ozone are estimated by using population data and epidemiological concentration-response functions for mortality and morbidity. Finally, the above calculations are done for all targeted ten regions.

Results and discussion

DFs of NO_x and NMVOC for ten regions were calculated as 0.3–4.2?×?10^?5 DALY/kg and 0.2–5.6?×?10^?6 DALY/kg, respectively. It was found DFs might be underestimated around 10 to 70 % by region if the transboundary movement is not taken into consideration. In many regions in the northern hemisphere, about 60 % of damage occurs outside the emission area, which is larger than that of southern hemispheric regions due to a larger population exposed to downwind places. In regions of China and India, however, the influence on other regions accounted for only 10 % because these regions involve larger influences in the source region. The impact of NO titration effect can be seen in cold seasons in many regions, but it was found that the effect is remarkable on an annual average only in Europe, a cold region with large emissions.

Conclusions

The human health DFs of NO_x and NMVOC considering effects of transboundary movement of tropospheric ozone are estimated for ten regions by using a global CTM. As a future work, it is important to show the interannual sensitivity of the DFs through chronological assessments.

     

Differences in above- and below-ground responses to ozone between two populations of a perennial grass

Our study examined the influence of elevated ozone levels on the growth and mycorrhizal colonization of two populations of Elymus glaucus L. (blue wildrye). We hypothesized that ozone would reduce carbon availability to the plants, particularly below ground, and would affect mycorrhizal colonization. Because of the wide geographic range of E. glaucus, two populations of plants were selected from areas of contrasting ozone histories to examine intraspecies variation in response to ozone. Two populations of E. glaucus (southern California versus northern California) exposed in a factorial experiment involving ozone, mycorrhizal inoculation with Glomus intraradices Schenck and Smith, and plant source population. Ozone had a subtle effect on leaf area and number of tillers but did not affect overall root:shoot ratio in either population. The impact of ozone on above-ground growth characteristics was most pronounced in the southern population that came from a high-ozone environment, while below-ground responses such as reduced arbuscular colonization was most pronounced in the northern population which originated in a low-ozone environment. Further analysis of soil characteristics from the northern population of plants revealed a significant reduction in active soil bacterial biomass and an increase in total fungi per gram dry weight soil, suggesting a possible role for ozone in altering soil processes. Whether or not population differences in response to ozone were due to genetic shifts resulting from prior ozone remains to be determined. However, these subtle but important differences in population response to ozone above- and below-ground have significant implications in any attempt to generalize plant response, even within a species. Future research efforts need to include better characterization of intraspecific variation in response to ozone as well as possible adaptive strategies that may result from chronic ozone exposure.