冬麦田臭氧干沉降过程的观测

地表臭氧作为近地层最主要的大气污染物之一,其不断上升的浓度及其对粮食作物的影响受到越来越多的关注.本研究利用微气象学观测方法,探明自然条件下冬麦田的臭氧沉降过程,分析了影响臭氧沉降过程的环境因子.结果表明: 观测期内(小麦生长旺期)臭氧通量均值为-0.35 μg·m^-2·s^-1(负号表示沉降方向指向地面),臭氧沉降平均速率为0.55 cm·s^-1,空气动力学阻力均值为30 s·m^-1,粘性副层阻力均值为257 s·m^-1,冠层阻力均值为163 s·m^-1,且均存在明显的日变化趋势.臭氧沉降阻力大小受摩擦速度、太阳辐射强度、温度和相对湿度等因素的影响.     

陆地生态系统臭氧通量观测和气孔吸收估算研究进展

近地面大气中臭氧(O3)对植物生长发育和产量会产生不良影响。工业和交通排放的增加使得全球地面O3浓度逐年增加,不断升高的O3浓度已开始影响到我国的粮食产量。O3对植物的影响是由于其进入植物体内发生生化反应所引起的,所以需要建立一种考虑到植物生理生态状况的评估指标来评估O3对植物的影响。其中基于O3通量(特别是植物气孔吸收)的评价指标和方法,被认为比传统的基于O3浓度的评价指标和方法更符合O3对植物的影响机理。介绍了O3对生态系统影响评估方法和评价指标,重点评述了生态系统尺度O3通量观测和气孔吸收估算的主要方法以及在不同生态系统上的研究进展分析了我国关于O3对植物和生态系统影响的研究现状,并对未来的研究工作进行了展望。     

Characteristics and partitioning of ozone dry deposition measured by eddy-covariance technology in a winter wheat field

Aims Anthropogenic pollutants cause an increase in ground-level ozone concentration, which is a known threat to plant growth and yield and has been extensively observed worldwide. Since ozone is only slightly soluble in water, it is deposited mainly through dry deposition in terrestrial ecosystem. The object of this study was to analyze the characteristics of ozone dry deposition and to estimate the contribution of stomatal and non-stomatal ozone deposition pathways to total ozone deposition in a winter wheat field.Methods The research site was a winter wheat (Triticum aestivum) field located in Yongfeng experimental station of Nanjing University of Information Science & Technology. The data used in this study were collected from March 16, 2016 to May 30, 2016. We observed ozone dry deposition with an eddy-covariance system. This system mainly included a 3D sonic anemometer, an open-path infrared absorption spectrometer, a fast-response ozone chemiluminescent analyzer and a slow-response ozone monitor. We simultaneously measured meteorological data including solar radiation (SR), air temperature (T), air relativity humidity (RH), wind speed, net radiation, and rainfall. All raw data were recorded with data-logger and averaged every 30 min.Important findings Half hourly means of ozone concentrations (C_O3), ozone flux (F_O3) and ozone dry deposition velocity (V_d) in the winter wheat field were 32.9 nL·L^-1, -5.09 nmol·m^-2·s^-1, 0.39 cm·s^-1, and the ranges of them were 16-58 nL·L^-1, -2.9- -11.7 nmol·m^-2·s^-1, 0.17-0.63 cm·s^-1, respectively. F_O3 and C_O3/V_d were found to be mismatched with phase peaks occurring at different time intervals. The ecosystem was more effective on ozone dry deposition, under conditions of moderate to high SR (SR ≥ 400 W·m^-2), moderate T and humility (T = 18 °C and RH > 40%). The relationship between V_dmax and SR was this function (y = 1.06 -exp (-0.0094 - x)). V_dmax increased with SR When SR < 400 W·m^-2, and V_dmax reached its maximum when SR =400 W·m^-2. V_dmax maintained its maximum when SR ≥ 400 W·m^-2. The relationship between V_dmax and T was “bell” curve (y = 1.06 - (x - 18)²/169). V_dmax reached its maximum when T = 18 °C. V_dmax decreased with RH when RH < 40 % (y = 0.030x - 0.106). The variation of V_d might uncertainty when RH was high. There was a liner positive relationship between friction velocity (u*) and V_d, but this relationship was not significant. The mean day-to-day and daytime contributions of stomatal and non-stomatal ozone deposition pathway to total ozone deposition were 32%, 68% and 42%, 58%, respectively, during the whole experimental period.     

Spatial and temporal assessment of sources contributing to the annual austral spring mid-tropospheric ozone maxima over the tropical South Atlantic

The primary source of the annual austral spring mid‐tropospheric ozone maxima over the tropical South Atlantic has generally been assumed to be biomass burning. However, ozone precursor emissions from biogenic, lightning, and anthropogenic sources in subequatorial Africa before and during the ozone peak are shown to be comparable, if not greater, in magnitude to regional biomass burning production. Moreover, an investigation of the spatial and temporal characteristics of these ozone precursor sources (i.e. vegetative and microbial activity, lightning‐induced generation, and anthropogenic emissions) suggests that these alternative sources can potentially make a substantial contribution to the seasonal ozone peak. This argument is supported by the practical limitations of atmospheric transport available to regionally produced ozone and ozone precursors.     

Similarities and differences of hyperbaric oxygen and medical ozone applications

Abstract

Hyperbaric oxygen (HBO) treatment is based on the principle of having the patient breath 100% oxygen in an environment above atmospheric pressure. Ozone (O₃) is a colourless gas with a specific odour and consists of three oxygen atoms. The classical scientific understanding is that the world has become a place suitable for life for aerobic organisms with the increasing oxygen in the atmosphere billions of years ago. The formation of ozone after oxygen has then protected aerobic creatures from harmful rays. We now use these two gases for treatment purposes. It is noteworthy that the oxygen and ozone molecules that are formed by the same atom in different numbers are used for similar medical indications. We will try to emphasize the similarities and differences of HBO and medical ozone applications in this article.     

Reduction of severe acute respiratory syndrome coronavirus-2 infectivity by admissible concentration of ozone gas and water

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing the global coronavirus disease 2019 (COVID-19) pandemic. Because complete elimination of SARS-CoV-2 appears difficult, decreasing the risk of transmission is important. Treatment with 0.1 and 0.05 ppm ozone gas for 10 and 20 hr, respectively, decreased SARS-CoV-2 infectivity by about 95%. The magnitude of the effect was dependent on humidity. Treatment with 1 and 2 mg/L ozone water for 10 s reduced SARS-CoV-2 infectivity by about 2 and 3 logs, respectively. Our results suggest that low-dose ozone, in the form of gas and water, is effective against SARS-CoV-2.     

Effects of ultraviolet-B radiation on plants during mild water stress. IV. The insensitivity of soybean internal water relations to ultraviolet-B radiation

The combined effects of ultraviolet-B (UV-B, 280–320 nm) radiation and water stress were investigated on the water relations of greenhouse grown soybean [ Glycine max (L.) Merr. cv. Essex]. On a weighted (Caldwell 1971), total daily dose basis, plants received either 0 or 3 000 effective J m² UV-B_BE supplied by filtered FS-40 sunlamps. The latter dose simulated the solar UV-B radiation anticipated at College Park, Maryland, U.S.A. (39°N latitude) in the event that the global stratospheric ozone column is reduced by 25%. Plants were either well-watered or preconditioned by drought stress cycles. Diurnal measurements of water potential and stomatal conductance were made on the youngest fully expanded leaf. Various internal water relations parameters were determined for detached leaves. Plants were monitored before, during and after water stress. There were no significant differences in leaf water potential or stomatal conductance between treatments before plants were preconditioned to water stress. However, drought stress resulted in significantly lower midday and afternoon leaf water potentials and lower leaf conductances as compared to well-watered plants. UV-B radiation had no additional effect on leaf water potential; however, UV did result in lower leaf conductances in plants preconditioned to water stress. Turgid weight:dry weight ratio, elastic modulus, bound water and relative water content were unaffected by UV-B radiation. Osmotic potentials at full and zero turgor were significantly lower in the drought stressed treatments as compared to well-watered plants.     

Differential responses in two varieties of winter wheat to elevated ozone concentration under fully open‐air field conditions

Two modern cultivars [Yangmai16 (Y16) and Yangfumai 2 (Y2)] of winter wheat (Triticum aestivum L.) with almost identical phenology were investigated to determine the impacts of elevated ozone concentration (E‐O₃) on physiological characters related to photosynthesis under fully open‐air field conditions in China. The plants were exposed from the initiation of tillering to final harvest, with E‐O₃ of 127% of the ambient ozone concentration (A‐O₃). Measurements of pigments, gas exchange rates, chlorophyll a fluorescence and lipid oxidation were made in three replicated plots throughout flag leaf development. In cultivar Y2, E‐O₃ significantly accelerated leaf senescence, as indicated by increased lipid oxidation as well as faster declines in pigment amounts and photosynthetic rates. The lower photosynthetic rates were mainly due to nonstomatal factors, e.g. lower maximum carboxylation capacity, electron transport rates and light energy distribution. In cultivar Y16, by contrast, the effects of E‐O₃ were observed only at the very last stage of flag leaf ageing. Since the two cultivars had almost identical phenology and very similar leaf stomatal conductance before senescence, the greater impacts of E‐O₃ on cultivars Y2 than Y16 cannot be explained by differential ozone uptake. Our findings will be useful for scientists to select O₃‐tolerant wheat cultivars against the rising surface [O₃] in East and South Asia.     

Historical ozone concentrations and flavonoid levels in herbarium specimens of the Antarctic moss Bryum argenteum

Depletion of stratospheric ozone since the mid 1970s has led to significant increases in ultraviolet B (UVB) irradiation over Antarctica. The detrimental effects of UVB on plants are many, but plants produce photoprotective flavonoids that reduce cellular damage. We used herbarium samples of the moss Bryum argenteum collected in Antarctica to compare the levels of flavone aglycones in plants collected before and after the formation of the ozone hole. The interpretation of historical data is difficult, because environmental conditions immediately before sample collection are unknown. Factors such as cloud cover can have a significant influence on UVB dose at ground level, modifying the flavonoid content of the specimen and adding considerable variability to the results. Nevertheless, our results revealed significant relationships between total flavone concentration and pooled year classes ( P = 0.001). Furthermore, regression analysis showed a significant negative relationship of total flavone concentration and the level of ozone immediately before the time of collection ( P = 0.016). In addition, the ratio of luteolin (an ortho -dihydroxylated flavone) to apigenin (a monohydroxylated flavone) increased significantly with several environmental parameters. These included (a) increasing modelled midday UVB radiation ( P = 0.002), (b) increasing modelled midday UVB/PAR ratio ( P < 0.001), and (c) decreasing ozone concentration ( P < 0.001). We emphasise the utility of this ratio in interpreting the historical ozone trends rather than relying on changes in total flavone concentrations alone. These results illustrate that herbarium specimens may reveal historical levels of UVB radiation.     

鲁西北平原冬小麦田臭氧浓度变化特征及对产量的潜在影响和机理分析

近地层高浓度臭氧(O₃)对农作物生长和产量形成有明显的影响。利用在中国科学院禹城综合试验站(山东省)冬小麦(Triticum aestivum)农田生态系统上观测的O₃浓度及微气象资料, 分析了鲁西北平原冬小麦农田生态系统O₃浓度的日变化和季节变化规律, 在此基础上初步分析了O₃浓度与CO₂通量(F_c)的关系, 并用欧洲和美国科学家在实验室得到的O₃浓度-冬小麦产量关系模型估算了O₃对冬小麦产量的潜在影响。结果表明: O₃浓度存在明显的日变化规律, 日最小值和最大值分别出现在7:00和16:00左右。整个观测期间(2011年3-5月)平均O₃浓度为(30.4 ± 20.1) nL·L ^-1(平均值±标准误差); 30 min平均浓度的最大值为93.1 nL·L ^-1。在冬小麦春季生长季节, O₃浓度日平均值呈现逐步增加的趋势, O₃浓度日均增加约为0.17 nL·L ^-1·d ^-1; 白天7 h和12 h平均浓度(M7和M12)分别为45.7和43.1 nL·L ^-1; O₃浓度超过40 nL·L ^-1的3个月累积值(AOT40)为9.8 μL·L ^-1·h; 超过60 nL·L ^-1的O₃浓度累积值(SUM06)为12.6 μL·L ^-1·h; 经过权重修正的O₃污染指标W126为10.1 μL·L ^-1·h。在高浓度O₃ (>60 nL·L ^-1)情况下, CO₂通量与O₃浓度呈现负相关关系, 鲁西北平原O₃对冬小麦光合作用影响的阈值取60 nL·L ^-1比较合适, 该值高于欧洲国家普遍采用的40 nL·L ^-1。基于以上结果, 初步估算得出: 在目前的O₃浓度水平下, 鲁西北平原近地层O₃可能会使冬小麦产量减少5.2%-8.8%。     

Relating Ozone Uptake in Forest Trees to Risk Assessment

This paper reviews the importance of ozone uptake through plant stomata in understanding plant response to ozone and discusses challenges in quantifying ozone uptake in forest trees. Uncertainties in spatial and temporal scaling of ozone uptake from the leaf to the landscape level, insufficient monitoring of ozone in forested areas, and tremendous variability in the composition and structure of forest ecosystems of the United States prevent the current use of ozone uptake in large-scale risk assessments and regulatory decisions.     

A unifying explanation for variation in ozone sensitivity among woody plants

Tropospheric ozone is considered the most detrimental air pollutant for vegetation at the global scale, with negative consequences for both provisioning and climate regulating ecosystem services. In spite of recent developments in ozone exposure metrics, from a concentration‐based to a more physiologically relevant stomatal flux‐based index, large‐scale ozone risk assessment is still complicated by a large and unexplained variation in ozone sensitivity among tree species. Here, we explored whether the variation in ozone sensitivity among woody species can be linked to interspecific variation in leaf morphology. We found that ozone tolerance at the leaf level was closely linked to leaf dry mass per unit leaf area (LMA) and that whole‐tree biomass reductions were more strongly related to stomatal flux per unit leaf mass (r² = 0.56) than to stomatal flux per unit leaf area (r² = 0.42). Furthermore, the interspecific variation in slopes of ozone flux–response relationships was considerably lower when expressed on a leaf mass basis (coefficient of variation, CV = 36%) than when expressed on a leaf area basis (CV = 66%), and relationships for broadleaf and needle‐leaf species converged when using the mass‐based index. These results show that much of the variation in ozone sensitivity among woody plants can be explained by interspecific variation in LMA and that large‐scale ozone impact assessment could be greatly improved by considering this well‐known and easily measured leaf trait.     

Impact of solar ultraviolet-B radiation (290-320 nm) upon marine microalgae

For years scientists and laymen alike have casually noted the impact of solar ultraviolet radiation upon the non-human component of the biosphere. It was not until recently, when human activities were thought to threaten the protective stratospheric ozone shield, that researchers undertook intensive studies into the biological stress caused by the previously neglected short-wavelength edge of the global solar spectrum. Stratospheric ozone functions effectively as an ultraviolet screen by filtering out solar radiation in the 220–320 nm waveband as it penetrates through the atmosphere, thus allowing only small amounts of the longer wavelengths of radiation in this waveband to leak through to the surface of the earth. Although this ultraviolet radiation (UV-B radiation, 290–320 nm) comprises only a small fraction (less than 1%) of the total solar spectrum, it can have a major impact on biological systems due to its actinic nature. Many organic molecules, most notably DNA and proteins, absorb UV-B radiation which can initiate photochemical reactions. It is life's ability, or lack thereof, to cope with enhanced levels of solar UV-B radiation that has generated the concern over the potential depletion of stratospheric ozone. The defense mechanisms that serve to protect both plants and animals from current levels of UV-B radiation are quite varied. Whether these mechanisms will suffice for marine microalgae under conditions of enhanced levels of UV-B radiation is the subject of this review.     

臭氧对微生物杀菌作用的初步研究

以稀释平板计数法 ,测定了臭氧对水体和空气环境的消毒杀菌作用。结果表明 :随着臭氧浓度 (时间 )的增加 ,对各类微生物杀灭率明显上升 ,除了芽孢杆菌外 ,杀灭率可以达到 1 0 0 %。     

臭氧暴露对大豆叶片群体光合作用及产量的影响

臭氧（O₃）已经成为我国许多大中城市夏季的首要污染物,其具有较强的植物毒性,严重威胁农业安全。O₃污染常发生于高温晴天,具有间歇性和累积性的特点,但现有研究多集中于在叶片尺度上探究长期O₃暴露对植物生理过程的影响,而间歇性暴露对植物整株生长和光合生理特性的影响鲜有报道。以大豆为实验对象,依托开顶式气室（OTC）进行间歇性臭氧暴露,探究大豆叶片群体光合作用及产量对间歇性O₃暴露的响应。结果发现（1）间歇性O₃暴露具有累积性和恢复性,在低O₃暴露剂量（AOT40≤2.47μL L^-1 h^-1）处理下,大豆植株的净光合速率降低,但与对照组无显著差异。当AOT40较高时（AOT40≤5.35μL L^-1 h^-1）,大豆植株的净光合速率显著降低,而随着O₃胁迫的消失,大豆植株的净光合速率逐渐回升,并最终恢复。（2）不同的光合参数对间歇性臭氧暴露敏感性不同,其中最大净光合速率最为敏感。在低AOT40下最大净光合速率显著降低,且恢复时间更长。（3） O₃二次暴露后,净光合速率降低幅度较低,且恢复更快,说明间歇性O₃暴露可能会提高大豆的耐受阈值。（4）当AOT40低于5.35μL L^-1 h^-1时,对大豆产量无显著影响,说明间歇性臭氧暴露条件下,大豆减产阈值更高。     

Effects of ultraviolet-B radiation on plants during mild water stress. III. Effects on photosynthetic recovery and growth in soybean

Soybean { Glycine max (L.) Merr. ev. Essex} was grown from seed in a greenhouse under ultraviolet-B (UV-B, 280–320 nm) radiation supplied by filtered FS-40 sunlamps. On a weighted, total daily dose basis these plants received either 0 (control) or 2875 effective J m⁻² day⁻¹ UV-B_BE. When weighted with the generalized plant action spectrum (Caldwell 1971), this simulated the solar ultraviolet-B irradiance expected to occur at College Park, Maryland, USA (39°N) in the event the global stratospheric ozone column is reduced by 23%. The effects of ultraviolet radiation on the photosynthetic recovery from water stress were measured with an infrared gas analyzer. These effects were examined in plants which were either well-watered or previously preconditioned to water stress, during two distinct phenological stages of development. During the early stages of soybean growth, enhanced levels of UV-B reduced net photosynthesis by 25%, and water stress also reduced photosynthesis to nearly the same extent (by 20%). The combination of these two stresses resulted in smaller biomass than that produced by plants exposed to either stress independently. Photosynthesis in older, larger plants was much more sensitive to water stress and was reduced by as much as 50–60% in non-preconditioned plants. Although non-irradiated, non-preconditioned (control) plants recovered to only within 60% of their prestressed value, preconditioned plants recovered to within 70–80% during the 3 day recovery period. Both water stress and UV-B radiation affected non-stomatal conductance, while stomatal conductance was primarily affected by water stress.