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1.
A biomonitoring study using the ozone-sensitive bioindicator plant Nicotiana tabacum cv. Bel-W3 was conducted in the city of Valencia (eastern Spain) and surrounding areas in 2002. Plants were exposed to ambient air at seven sites, including four traffic-exposed urban sites, a large urban garden and a suburban and a rural station, for six consecutive 2-week periods using highly standardised methods. Foliar injury was registered at all stations in at least one of the exposure periods. The urban stations submitted to intense traffic showed lower ozone injury than the less traffic-exposed stations. Strong changes in the intensity of ozone injury were observed for the different exposure periods. Leaf injury was significantly related to both mean ozone values (24 and 12 h means) and cumulative exposure indices (AOT20, AOT40). However, correlation strength was moderate (r s?=?0.39 to 0.58), suggesting that the plant response to ozone was modified by environmental factors. The use of sensitive bioindicators like tobacco Bel-W3 in cities provides complementary information to that of continuously operating air quality monitors, as the impact of ambient ozone levels is directly measured.  相似文献   

2.
Incidence and severity of foliar symptoms due to ambient ozone exposures were documented on mature black cherry (Prunus serotina) in two National Parks [Great Smoky Mountains National Park (GRSM) and Shenandoah National Park (SHEN)] in the Appalachian Mountains of the eastern USA during the summer of 1991-1993. Three plots in each park containing 30 trees each (Big Meadows in SHEN had 60 trees) with 90 and 120 trees total trees were evaluated in GRSM and SHEN, respectively. Plots were established at different elevations adjacent to ozone monitoring stations. Samples of foliage were collected and three exposed branches from the upper- crown and three branches from the mid-to-lower crown were examined for symptoms of foliar ozone injury. Incidence was greatest in 1991 at both locations; 60% and 45% for GRSM and SHEN, respectively. In 1992 and 1993, incidence was very similar in both parks, with approximately 33% of the trees affected. Black cherry at the highest elevations exhibited the greatest amount of symptoms in both parks all three years of the study. These sites also exhibited the highest ozone concentrations. In addition, the percent of trees injured by ozone was positively correlated with SUM06 and W126. These results along with forest surveys and open-top chamber studies indicate that black cherry may be a reliable bioindicator of foliar injury due to ambient ozone.  相似文献   

3.
The atmospheric deposition of air pollutants was studied by means of monitoring canopy throughfall at six forest stands. The investigation was carried out in Norway spruce (Picea abies L. Karst.) forests in Southern Bavaria with high ambient ammonia concentrations due to either adjacent intensive agriculture or poultry housing. Five monitoring plots transected the forest edges and forest interior from the edge, at 50, 150, about 400 m and about 800m to the interior. Additionally, nutrient concentration in soil solution was sampled with suction cups at each plot, and C/N ratio of the humus layer was also determined. The variation of ambient ammonia concentration between three of the six investigated sites was estimated using diffusive samplers. In order to compare the effects of atmospheric deposition on European beech (Fagus sylvatica L.) and Norway spruce additional monitoring plotswere installed under each of these species in a mixed beech and spruce stand. Bulk deposition and soil water samples were analysed for major ions (NO3 -, NH4 +, SO4 2-, Cl-, Na+, K+, Mg2+, Ca2+M).The results show a substantial increase of deposition towards the forest edges for all ions. This so called 'edge effect' continued in most cases until a distance from 50 to 150 m from edge. For both ambient ammonia concentrations and nitrogen deposition, it can be concluded that increased dry deposition is the main reason for the edge effect. Over 76% of the nitrogen ratios in throughfall deposition between the edge and 50 m distance into the spruce forest exceed 1.0. Except for potassium, beech generally showed lower ratios than spruce.Due to high nitrogen deposition the forest floor, C/N ratios were lower at stand edges when compared to their interior. In contrast to the increase of nitrogen deposition at the edge, nitrate export below the main rooting zone was lower at the edge. Nitrate export was generally lower under beech than spruce. Nitrogen budgets of some plots were negative, indicating a reduction of total ecosystem nitrogen stock.The results show that forest edges, especially in areas with high air pollution, receive much more atmospheric deposition than the interior parts of closed forest stands. As many deposition studies in forests were conducted at field stations in the central parts of forests the estimated deposition for the whole forest may be underestimated. This may be important to consider in geo-statistical studies and models aiming to estimate spatial critical deposition values, especially with an increasing fragmentation of the forest cover.  相似文献   

4.
Concentrations of ozone and nitrogen oxides, together with air temperature and solar radiation intensity, were measured at several heights on a tower standing through the canopy of a red pine forest in summer and in autumn. In the summer observation, the diurnal variation patterns of ozone concentration both above and below the canopy were all similar and parallel to the solar radiation intensity. Using the data collected immediately above the canopy, deviation from the Leighton relationship and variations of concentration sums [O3] + [NO] and [NO2] + [NO] were examined, and as a result, it was supposedthat ozone was photochemically formed there in the daytime, probably because hydrocarbons emitted from pine trees broke the photostationary state among ozone and nitrogen oxides. The vertical temperature profile exhibited an inversion at the leaf-layer, which must have hindered vertical mixing of the air and made the trunk space more or less isolated from the upper atmosphere. These observations led to an idea that the similarity of the ozone variation pattern at every height was caused by the photochemical formation that proceeded simultaneously above and below the canopy rather than by vertical transport. Such situations of ozone formation were supported by observation of two maximums in the ozone vertical profile, one immediately above the canopy and another in the trunk space. Another feature of the ozone profile was a deep minimum in the leaf layer, which indicated ozone deposition onto leaf surfaces. This study thus revealed concurrence of ozone formation and deposition, and left two potentially important implications worthy of further investigation: (1) a forest is not always a sink but can be a source of ozone in sunlit conditions, and (2) deposition of ozone to trees can take place not only from outside but also from inside of a forest. In the autumn observation, however, the ozone formation was barely recognizable above the canopy and no longer found in the trunk space; in addition, the ozone concentration minimum in the leaf layer disappeared, suggesting that the deposition or removal was dependent on temperature.  相似文献   

5.
Plants represent one of the major sinks for tropospheric ozone that, at high concentrations, can affect plants' physiological activity with consequent serious damage. A research project has been promoted by the Lombardy Foundation for the Environment to investigate the effects of air pollution on forest ecosystems. The areas of study are located on the southern slopes of the Italian Alps in two valleys, only 10 km apart, selected because of their different plant injury: Val Gerola and Val Masino. Air quality (O3, NOx, SOx, VOC) and meteorological parameters were monitored during four summer seasons (1994-97) using automatic sampling devices providing hourly mean values for each variable. Data analysis showed very different ambient ozone concentrations at the two sites, with average concentration values observed in the more damaged valley (Val Gerola) twice those measured at the other site. Multivariate data analyses have been used to interpret the observed differences in long-term O3 exposure between the two sites and to identify possible underlying processes.  相似文献   

6.
Biolley  J.P.  Lauga  B.  Cagnon  C.  Duran  R.  Salvado  J. C.  Goulas  P. 《Water, air, and soil pollution》1998,106(3-4):355-368
From sowing till emergence of the fourth trifoliolate leaf, beans were exposed for seven hr a day to four ozone concentrations in open-top chambers: filtered air (FA), non-filtered air (NF), non-filtered air plus 30 ppb ozone (NF+) and non-filtered air plus 60 ppb ozone (NF++). Controls in ambient air of open plots (AA) were also available. The free polyphenolic pool of the first trifoliolate leaf was systematically investigated using HPLC. The groups of phenolics to which the three main chromatographic signals belonged were identified as hydroxycinnamic acid derivative for peak No 1 and flavonoids for peaks Nos 4 and 6. The metabolic regulation of phenolic accumulation could be recognized as different clusters based on specific phenolic patterns that reflected some of the tested atmospheric conditions. The comparison of AA and NF conditions revealed a ‘chamber effect’. FA and NF atmospheres gave rise to almost the same phenolic equilibriums dominated by a hydroxycinnamic acid derivative (about 53% of the total phenolics). Ozone addition was associated with a regular reduction of the percentage of peak No 1: about 40% for NF+ and 19% for NF++. Therefore, the significant decrease of the vacuolar storage of this phenolic compound (from 23 mg g-1 dry weight for NF to about 3 mg g-1 dry weight for NF++) can be regarded as a useful tool for monitoring long-term exposure to elevated ozone concentrations.  相似文献   

7.
The level and distribution of tropospheric ozone in remote and wildness areas of the Maurienne valley, a main axis in European transport, were determined during summertime 2004 and 2005. A comprehensive distribution of biological and chemical sensors based on the commonly used ozone sensitive Bel-W3 tobacco and the passive sampling system, was set up. A significant positive correlation was observed between the two methods and the continuous ozone monitors set in three instrumental co-locations. Moreover, results from this air quality network showed that, within a natural pathway of mass airflow, altitude and climate induced variations in plant responsiveness to ozone. Three different ozone diurnal patterns could thus be clearly identified. Biological sensing to determine ozone levels in regional-scale air quality assessment proved to be accurate at low altitudes. However, Tobacco response was limited in harsh mountainous conditions. This was probably due to a decrease of plant sensitivity.  相似文献   

8.
The perceived health of forest ecosystems over large temporal and spatial scales can be strongly influenced by the frames of reference chosen to evaluate both forest condition and the functional integrity of sustaining forest processes. North American forests are diverse in range, species composition, past disturbance history, and current management practices. Therefore the implications of changes in environmental stress from atmospheric pollution and/or global climate change on health of these forests will vary widely across the landscape. Forest health surveys that focus on the average forest condition may do a credible job of representing the near-term trends in economic value while failing to detect fundamental changes in the processes by which these values are sustained over the longer term. Indications of increased levels of environmental stress on forest growth and nutrient cycles are currently apparent in several forest types in North America. Measurements of forest ecophysiological responses to air pollutants in integrated case studies with four forest types (southern pine, western pine, high elevation red spruce, and northeastern hardwoods) indicate that ambient levels of ozone and/or acidic deposition can alter basic processes of water, carbon, and nutrient allocation by forest trees. These changes then provide a mechanistic basis for pollutant stress to enhance a wider range of natural stresses that also affect and are affected by these resources. Future climatic changes may ameliorate (+ CO2) or axacerbate (+ temperature, + UV-B) these effects. Current projections of forest responses to global climate change do not consider important physiological changes induced by air pollutants that may amplify climatic stresses. These include reduced rooting mass, depth, and function, increased respiration, and reduced water use efficiency. Monitoring and understanding the relative roles of natural and anthropogenic stress in influencing future forest health will require programs that are structured to evaluate responses at appropriate frequencies across gradients in both forest resources and the stresses that influence them. Such programs must also be accompanied by supplemental process -oriented and pattern -oriented investigations that more thoroughly test cause and effect relationships among stresses and responses of both forests and the biogeochemical cycles that sustain them.  相似文献   

9.
A low-cost, accurate and sensitive passive measurement method for ozone has been developed and tested. The method is based on the reaction of ozone with indigo carmine which results in colourless reaction products which are detected spectrophotometrically after exposure. Coated glass filters are mounted in a short polystyrene badge-type vessel in which the diffusion path is restricted by a Teflon membrane filter. From wind tunnel experiments good concentration-independent linearity has been found. The detection limit of the method is about 23 ppbv for 1 hour exposure. Tests with interfering oxidants, such as peroxyacetyl nitrate and NO2, indicated no significant effects for common ambient conditions. No humidity effect was found when the relative humidity varied from 20 to 80%. The uptake rate of the sampler is dependent on wind velocity. In general an average air velocity of approximately 0.5 m/s is necessary to ensure a stable collection rate of ozone. This implies the necessity to measure wind speed during exposure or to place the samplers in the wind stream of a small fan. The method is suitable for hourly to daily mean measurements of ambient ozone. Under field conditions an accuracy of 11 ± 9% (40 experiments) was established in comparison to a continuous UV photometric monitor.  相似文献   

10.
Three bush bean cultivars (Lit, Groffy and Stella) were grown under four levels of ozone exposure (ambient air+50 ppb O3 ambient air+25 ppb O3, ambient air and charcoal filtered air) in open- top chambers. Number and leaf injury statistics showed significant reduction in the number of healthy leaves as the level of O3 increased. The area based leaf injury percentages of the cvs. Lit, Groffy and Stella were 69.8, 57.9 and 71.1% at the highest O3 level, 24.1, 19.6 and 30.3% at the 2nd highest O3 level, and 4.5, 0.7 and 5.6% at the ambient air, respectively. The plants grown in the filtered air revealed no injury symptoms. The stomatal conductances were found to decrease gradually in each cultivar as the O3 level increased. At the highest O3 level, Chlorophyll fluorescence measurements on the 2nd leaf from the top on 24th day of exposure resulted in significantly the highest Fv/Fm values, the lowest f0 and the highest Fm values whereas the 4th leaf showed the smallest Fm and correspondingly the smallest Fv/Fm values. This is an indication of photosystem II damage after accumulation of a high ozone dose in the 4th leaf. The photosynthetic rate of the 2nd leaf measured on 30th day of exposure was comparatively higher at the highest exposure but the data taken from the same leaf on 40th day of exposure showed significantly lower photosynthetic rate than the plants in ambient air. Both chlorophyll fluorescence and photosynthetic measurements indicated that ozone stressed leaves experience a stimulation of photosynthesis (possibly due to increased assimilate demand) prior to irreversible damage. Bush bean leaves need to accumulate a critical ozone dose(an AOT40 of presumably > 18 ppm-h) for reduction of the photosynthetic capacitys.  相似文献   

11.
In 1992 a cooperative project, Clover Sweden, was initiated. The aim was to study if subterranean clover could be used as a bioindicator in the different climate zones in Sweden by studying the impact of ambient ozone concentrations on this species in different parts of the country during three consecutive summer seasons. Plants of subterranean clover, Trifolium subterraneum, L., were exposed to ambient air at 24 sites from north to south Sweden. The project was designed to be compatible with the international programme, ICP Crops within the UNECE and the Convention on Long Range Transboundary Air Pollution. The results showed that subterranean clover is a useful bioindicator of ozone in all agricultural areas of Sweden, with the exception for very cool and rainy summers resulting in poor growth of the plants. In 1992, and especially in 1994, ozone injury was detected at almost all sites in Sweden, reflecting the higher ozone levels of those summers as compared to 1993, when ozone concentrations were generally low and not much injury was detected. Typical injury was chlorotic and bifacial necrotic lesions on parts of the leaf surface. It is concluded that at mean ozone concentrations of 25 ppb (24 h mean) and 30 ppb (7 h mean) there is a potential risk for injury on 10% of the leaves. When % injured leaves was plotted against AOT (Accumulated exposure Over a Threshold) using different thresholds, it became obvious that a threshold of 20 ppb ozone should be used in order to fully protect from leaf injury under Swedish conditions.  相似文献   

12.
Peña  R. M.  García  S.  Herrero  C.  Lucas  T. 《Water, air, and soil pollution》2000,117(1-4):289-303
Measurements of ozone were carried out at two different sites in the area surrounding a thermal power plant located in the Northwest of Spain during 1993–1995. The concentration of O3 in the ambient air varied from 6 to 257 μg m-3 exhibiting a wide temporal, seasonal and spatial variation. On a few occasions 1-hr ozone concentration was more than 180 μg m-3, which represents the maximum 1-hr limit of ozone in ambient air as prescribed by the European Commission.  相似文献   

13.
Nocturnal cooling of air within a forest canopy and the resulting temperature profile may drive local thermally driven motions, such as drainage flows, which are believed to impact measurements of ecosystem-atmosphere exchange. To model such flows, it is necessary to accurately predict the rate of cooling. Cooling occurs primarily due to radiative heat loss. However, much of the radiative loss occurs at the surface of canopy elements (leaves, branches, and boles of trees), while radiative divergence in the canopy air space is small due to high transmissivity of air. Furthermore, sensible heat exchange between the canopy elements and the air space is slow relative to radiative fluxes. Therefore, canopy elements initially cool much more quickly than the canopy air space after the switch from radiative gain during the day to radiative loss during the night. Thus in modeling air cooling within a canopy, it is not appropriate to neglect the storage change of heat in the canopy elements or even to assume equal rates of cooling of the canopy air and canopy elements. Here a simple parameterization of radiatively driven cooling of air within the canopy is presented, which accounts implicitly for radiative cooling of the canopy volume, heat storage in the canopy elements, and heat transfer between the canopy elements and the air. Simulations using this parameterization are compared to temperature data from the Morgan-Monroe State Forest (IN, USA) FLUXNET site. While the model does not perfectly reproduce the measured rates of cooling, particularly near the top of the canopy, the simulated cooling rates are of the correct order of magnitude.  相似文献   

14.
Bioindication of air pollution effects has received considerable attention in recent years. It has been almost entirely focused on individual species and relatively little notice has been given to ecosystem level process and function monitors. Longterm research projects in the Niepolomice Forest in southern Poland and the Colstrip area in southeast Montana, U.S.A., were analyzed for both organismic and system level indicators and monitors for SO, trace elements, and fluoride pollution originating in nearby coal-fired industrial processes. Species of lichens exhibited changes in morphology and survival and pine species exhibited pollutant accumulation in needles at both sites. Declines in Scotch pine growth in Poland of up to 20% were compared with declines in western wheatgrass rhizone biomass in Montana to illustrate system wide effects on primary productivity. Directly observable declines in decomposition rate were noted for both sites at higher pollution levels and tied to system wide occurrences of nutrient deficiency and toxicant buildup in soil pools. Pollutant increases in deer antler composition, changes in grasshopper dietary patterns, and lichen density and health were postulated to have system level implications as well.  相似文献   

15.
The stress by air pollution at the systematicPan-European 16 × 16 km2 forest (crown) condition monitoring network, is discussed by comparingsite-specific estimates of critical and presentconcentration and deposition levels for S and Ncompounds and ozone. Results indicate that theexceedance of critical levels, related to directabove-ground impacts, decrease going from O3 >SO2 > N compounds. Critical N loads related toeffects on the forest understorey are exceeded atapproximately 25% of the plots, located mainly inWestern and Central Europe. Critical N loads relatedto effects on trees are hardly ever exceeded, but mostlikely, this is an under estimate. Critical aciddeposition levels are exceeded at approximately 30%of the plots with a low base saturation, where acidinputs may release toxic Al. This is especially thecase in Central and Eastern Europe, where presentloads are high and in boreal forest in SouthernScandinavia where critical loads are low. Although theuncertainties in the calculated exceedances is large,the spatial pattern, which is most important for acorrelative study, seems reliable, implying that thecritical load concept is suitable for regional risk assessments.  相似文献   

16.
Ozone concentrations were measured at a wind-exposed edge of a 60 year-old 15–20 m tall Norway spruce forest in south-west Sweden and simultaneously over a barley field 5 km away for 27 days, At the forest site, measurements were performed at 3 and 13 m height 15 m in front of the forest edge, at 3 m height 15 m into the forest, and at 3 and 13 m height 45 m into the forest. Measurements at 3 m were made with three replicate tubes separated by 10 m. Differences between replicates were small. At 13 m height, the concentration (24-hr-average) 45 m into the forest was 95% of that in front of the forest edge. The average concentration at 3 m height did not vary strongly with the distance into the forest, but was 86% of that at 13 m in front of the forest edge. For AOT40 (Accumulated Exposure Over Threshold 40 ppb ozone), the differences between different positions were larger. At the 13 m level the AOT40 (day and night) was 88% of that in front of the forest 45 m into the forest. The AOT40 at 3 m was 71% of that at 13 m outside the forest. At the crop site, the ozone concentration at 1.1 m (0.1 m above the canopy), was 78% of that at 9 m (06.00–22.00). The AOT40 at 1.1 m above the ground, however, was only 50% of that at 9 m, indicating that serious errors can arise if ozone monitoring data are used uncorrnected in dose-response relationships based on measurements performed at plant height. The ozone concentration for the whole period differed very little between 9 m height at the crop site and 13 m height at the forest site outside the forest during daytime conditions (06.00–22.00). Night-time (22.00–06.00) values were only 21% at the crop site of those at the forest site due to the stronger night inversion development in the agricultural environment compared to the wind exposed forest edge. The results suggest that variations in topography and vegetation are important to consider when combining ozone monitoring data with dose-response functions.  相似文献   

17.
寇太记  朱建国 《土壤学报》2013,50(3):501-506
依托O3FACE(Free-Air O3 Enrichment)研究平台,研究了大气臭氧(O3)浓度增加对拔节期水稻根系呼吸和生物量积累分配的影响,利用特制集气装置分析了厌氧—有氧条件对根系呼吸的影响。结果表明,O3浓度升高水稻冠层和总生物量略有降低,而根干物重和根/冠比分别显著降低14.7%和10.4%。9∶1和9.5∶0.5的纯N2∶O2配比利于根系呼吸,纯N2或空气、CO2饱和蒸馏水条件不同程度降低了根系呼吸速率;高臭氧处理、对照处理的水稻根系呼吸速率分别在CO2饱和蒸馏水、纯N2条件下最小,表明尽管不同根系测定条件影响根系呼吸速率,但影响程度也受植物生长的大气环境制约。臭氧污染处理水稻根系的呼吸速率在气态测定条件下显著高于正常大气处理23.6%～52.7%,在CO2饱和蒸馏水测定条件下未达到显著水平,臭氧污染效应明显降低。两个环境生长的水稻根系呼吸均随测定根系气态环境供氧量的增加呈凸二次函数变化,5%～10%比例的氧气供应促进了根系呼吸,较强的厌氧环境(纯N2)和有氧环境(Air)均不利于水稻根系呼吸。  相似文献   

18.
Forest ecosystems have been widely fragmented by human land use. Fragmentation induces significant microclimatic and biological differences at the forest edge relative to the forest interior. Increased exposure to solar radiation and wind at forest edges reduces soil moisture, which in turn affects leaf litter decomposition. We investigate the effect of forest fragmentation, soil moisture, soil macrofauna and litter quality on leaf litter decomposition to test the hypothesis that decomposition will be slower at a forest edge relative to the interior and that this effect is driven by lower soil moisture at the forest edge. Experimental plots were established at Wytham Woods, UK, and an experimental watering treatment was applied in plots at the forest edge and interior. Decomposition rate was measured using litter bags of two different mesh sizes, to include or exclude invertebrate macrofauna, and containing leaf litter of two tree species: easily decomposing ash (Fraxinus excelsior L.) and recalcitrant oak (Quercus robur L.). The decomposition rate was moisture-limited at both sites. However, the soil was moister and decomposition for both species was faster in the forest interior than at the edge. The presence of macrofauna accelerated the decomposition rate regardless of moisture conditions, and was particularly important in the decomposition of the recalcitrant oak. However, there was no effect of the watering treatment on macrofauna species richness and abundance. This study demonstrates the effect of forest fragmentation on an important ecosystem process, providing new insights into the interacting effects of moisture conditions, litter quality, forest edge and soil macrofauna.  相似文献   

19.
Long range transport of episodic concentrations of O3 into the Appalachian Mountains of Virginia was recorded in the summer season of 1979 and 1980. Continuous monitoring of O3 indicated monthly averages of ? 0.05 ppm O3 and several periods averaged ? 0.08 ppm O3. Open-top chambers were used to test the effect of ambient doses of the pollutant on the growth of 8 planted forest tree species native to the area. Height growth was suppressed for all species at the end of the second growing season when grown in open plots (no chamber) and ambient chambers compared to those grown in charcoal-filtered air supplied chambers. Height growth trends of open < ambient chamber < filtered air chamber were consistent. Virginia pine and green ash were significantly taller (p=0.10) when grown within filtered air chambers. Tulip poplar and green ash manifested purple stippling on the adaxial leaf surface and sweetgum developed purple coloration under open or ambient chamber conditions; other species exhibited no visible injury.  相似文献   

20.
Episodes of pollution resulting from high concentrations of environmental ozone frequently occur in different parts of the world. The ozone can affect human health, natural vegetation, and agricultural productivity. The monitoring of ozone concentrations is essential to aid investigation of its effects and it is also required to assess progress in public management of this pollutant. A new effective and simple technique is presented for the determination of ambient ozone concentrations using a visual procedure. The method is based on the reaction between the dye indigo and ozone, with the formation of colorless products. The bleaching intensity is proportional to the amount of ozone. An indigo color standard scale was developed with the utilization of digital image-based (DIB) calibration and printed as a wheel-chart test kit. Ozone sampling is performed using a passive sampler containing a filter impregnated with indigo. The amount of reacted ozone can be determined by visual comparison using the wheel-chart test kit. The method enables determination of ozone concentrations from 2 to 97 ppb, with intervals of 3 ppb. It does not require an energy source or any post-sampling chemical treatment or analysis, and the ozone concentration can be known immediately, in situ, at the end of the sampling period. The method offers substantial advantages in large-scale mapping and monitoring of ozone or measurements concerning occupational exposure to ozone.  相似文献   

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