共查询到20条相似文献,搜索用时 46 毫秒
1.
Foliar injury and shoot fresh weight responses of soybeans (Glycine max L.) ‘Lee 68’ and ‘Dare’ exposed to mixtures of ozone (O 3) and sulfur dioxide (SO 2) were greater than additive (synergistic), less than additive (antagonistic), or additive. The result depended on the concentrations of O 3 and SO 2, the exposure duration, and the amount of injury caused by each gas singly. Synergism usually occurred when injury from O 3 or SO 2 singly was slight to moderate. Antagonism usually occurred when injury from either gas singly was severe. In many cases of antagonism, the injury and fresh weight effects of the mixture were less than those from SO 2 alone, suggesting that O 3 can sometimes protect soybeans from SO 2. 相似文献
2.
A plant injury mathematical model, applied previously to acute and chronic leaf injury data, is used here to model National Crop Loss Assessment Network (NCLAN) data for 15 cultivars and to calculate species parameters from the cultivar analyses. Percent crop yield reduction is estimated as a function of a new parameter, the effective mean O 3 concentration: m e = [(Σ c h ?1/v)/n] ?v, where c h is the hourly average ambient O 3 concentration for each daytime hour (defined here as 9:00 A.M.–4:00 P.M., always standard time) of data available at an air sampling site for summer (defined here as June 1–August 31), n is the total number of such available hours, and v is an exposure time-concentration parameter, calculated here to be approximately –0.376. Crop yield reduction for soybean is calculated here as z = 0.478 In ( tm e 2-66) – 0.42, where z is the Gaussian transform of percent crop reduction, t is the hours of exposure (525 h is used here; 7 h/day for 75 days), and In indicates that the natural logarithm is taken of the quantity within parentheses. Crop yield reductions for seven plant species are estimated with similar equations for each of the 1824 site-years of 1981–1983 hourly O 3 concentration data available in the National Aerometric Data Bank (NADB). County-average effective mean O 3 concentrations are indicated by shading on a U.S. map. State-average O 3 parameters and estimated percent crop yield reductions are tabulated. The National Ambient Air Quality Standard (NAAQS) for O 3 specifies that, on the average, the second highest daily maximum 1-h average O 3 concentration in a year shall not exceed 0.12 ppm. For years 1981-1983,71% of the NADB sites recorded annual second highest daily maximum 1-h average O3 concentrations below 0.125 ppm (for summer daytime hours). Ambient O 3 concentrations reduced the total U.S. crop yield an estimated 5% for years 1981–1983. (Summer, daytime, and all acronyms are always used herein as defined above.) 相似文献
3.
Numerical sensitivity tests and four months of complete model runs have been conducted for the Routine Deposition Model (RDM). The influence of individual model inputs on dry deposition velocity as a function of land-use category (LUC) and pollutant (SO 2, O 3, SO 2−4 and HNO 3) were examined over a realistic range of values for solar radiation, stability and wind speed. Spatial and temporal variations in RDM deposition velocity ( Vd) during June – September 1996 time period generated using meteorological input from a mesoscale model run at 35 km resolution over north-eastern North America were also examined. Comparison of RDM Vd values to a variety of measurements of dry deposition velocities of SO 2, O 3, SO 2−4 and NHO 3 that have been reported in the literature demonstrated that RDM produces realistic results. Over northeastern NA RDM monthly averaged dry deposition velocities for SO 2 vary from 0.2 to 3.0 cm s −1 with the highest deposition velocities over water surfaces. For O 3, the monthly averaged dry deposition velocities are from 0.05 to 1.0 cm s −1 with the lowest values over water surfaces and the highest over forested areas. For HNO 3, the monthly averaged dry deposition velocities have the range of 0.5 to 6 cm s −1, with the highest values for forested areas. For SO 2−4, they range from 0.05–1.5 cm s −1, with the lowest values over water and the highest over forest. The monthly averaged dry deposition velocities for SO 2 and O 3 are higher in the growing season compared to the fall, but this behaviour is not apparent for HNO 3 and sulphate. In the daytime, the hourly averaged dry deposition velocities for SO 2, O 3, SO 2−4 and HNO 3 are higher than that in the nighttime over most of the vegetated area. The diurnal variation is most evident for surfaces with large values for leaf area index (LAI), such as forests. Based on the results presented in this paper, it is concluded that RDM Vd values can be combined with measured air concentrations over hourly, daily or weekly periods to determine dry deposition amounts and with wet deposition measurements to provide seasonal estimates of total deposition and estimates of the relative importance of dry deposition. 相似文献
4.
Dhaka, the capital of Bangladesh, is among the most polluted cities in the world. This research evaluates seasonal patterns, day-of-week patterns, spatial gradients, and trends in PM 2.5 (<2.5 µm in aerodynamic diameter), PM 10 (<10 µm in aerodynamic diameter), and gaseous pollutants concentrations (SO 2, NO 2, CO, and O 3) monitored in Dhaka from 2013 to 2017. It expands on past work by considering multiple monitoring sites and air pollutants. Except for ozone, the average concentrations of these pollutants showed strong seasonal variation, with maximum during winter and minimum during monsoon, with the pollution concentration of PM 2.5 and PM 10 being roughly five- to sixfold higher during winter versus monsoon. Our comparisons of the pollutant concentrations with Bangladesh NAAQS and U.S. NAAQS limits analysis indicate particulate matter (PM 2.5 and PM 10) as the air pollutants of greatest concern, as they frequently exceeded the Bangladesh NAAQS and U.S. NAAQS, especially during nonmonsoon time. In contrast, gaseous pollutants reported far fewer exceedances throughout the study period. During the study period, the highest number of exceedances of NAAQS limits in Dhaka City (Darus-Salam site) were found for PM 2.5 (72% of total study days), followed by PM 10 (40% of total study days), O 3 (1.7% of total study days), SO 2 (0.38% of total study days), and CO (0.25% of total study days). The trend analyses results showed statistically significant positive slopes over time for SO 2 (5.6 ppb yr ?1, 95% confidence interval [CI]: 0.7, 10.5) and CO (0.32 ppm yr ?1, 95% CI: 0.01, 0.56), which suggest increase in brick kilns operation and high-sulfur diesel use. Though statistically nonsignificant annual decreasing slopes for PM 2.5 (?4.6 µg/m 3 yr ?1, 95% CI: ?12.7, 3.6) and PM 10 (?2.7 µg/m 3 yr ?1, 95% CI: ?7.9, 2.5) were observed during this study period, the PM 2.5 concentration is still too high (~ 82.0 µg/m 3) and can cause severe impact on human health. Implications: This study revealed key insights into air quality challenges across Dhaka, Bangladesh, indicating particulate matter (PM) as Dhaka’s most serious air pollutant threat to human health. The results of these analyses indicate that there is a need for immediate further investigations, and action based on those investigations, including the conduct local epidemiological PM exposure-human health effects studies for this city, in order to determine the most public health effective interventions. 相似文献
5.
ABSTRACT Generalized additive models were used to analyze the time series of daily hospital admissions for cardiovascular and cerebrovascular diseases over the period of 19871995 in three major metropolitan areas—Cook County, IL; Los Angeles County, CA; and Maricopa County, AZ— in the United States. In Cook and Maricopa Counties, admissions information was only available for the elderly (ages 65 and over), while in Los Angeles County, admissions information was available for all ages. In Cook County, daily monitoring information was available on PM 10, CO, SO 2, NO 2, and O 3. In Los Angeles and Maricopa Counties, monitoring information was available daily on the gases, and information on PM 10 was available every sixth day. In Los Angeles County, information on PM 25 was also available every sixth day. In Cook and Los Angeles Counties, associations were found between each pollutant, with the exception of O 3, and admissions for cardiovascular disease, with the gases showing the strongest associations. In two-pollutant models with PM and one of the gases, the effect of the gases remained stable, while the effect of PM became unstable and insignificant. In Maricopa County, the gases, with the exception of O 3, were weakly associated with hospital admissions for cardiovascular disease, while PM was not. In two-pollutant models with two of CO, SO 2, and NO 2, the pattern of results is heterogeneous in the three counties. In all three counties, only weak evidence of any association between air pollution and cere-brovascular admissions was found. 相似文献
6.
Abstract Attaining the National Ambient Air Quality Standard (NAAQS) for ozone (O 3) could cost billions of dollars nationwide. Attainment of the NAAQS is judged on O 3 measurements made by the Federal Reference Method (FRM), ethylene chemiluminescence, or a Federal Equivalent Method (FEM), predominantly ultraviolet (UV) absorption. Starting in the 1980s, FRM monitors were replaced by FEMs so that today virtually all monitoring in the United States uses the UV methodology. This report summarizes a laboratory and collocated ambient air monitoring study of interferences in O 3 monitors. Potential interferences examined in the laboratory included water vapor, mercury, o-nitrophenol, naphthalene, p-tolualdehyde, and mixed reaction products from smog chamber simulations of urban atmospheric photochemistry. UV absorption O 3 monitors modi?ed for humidity equilibration were also collocated with UV FEM O 3 monitors at six sites in Houston, TX, during the 2007 summer O 3 season. The results suggest that humidity and interfering species can positively bias (overestimate) O 3 measured by FEM monitors used to determine compliance with the O 3 standards. The results also suggest that humidity equilibration can mitigate this bias. 相似文献
7.
Ground-based ambient air monitoring was conducted to assess the contribution of crop residue burning of wheat (Triticum aestivum) and rice (Oriza sativa) at different locations in three districts (Kaithal, Kurukshetra, and Karnal) of the agricultural state of Haryana in India for two successive years (2016 and 2017). The Air Quality Index (AQI) and concentration of primary pollutants (SOx, NOx, and PM2.5) were determined in rice and wheat crop season, for burning and non-burning periods. During crop residue burning periods, concentrations of SOx, NOx, and PM2.5 were exceeded the NAAQS values by 78%, 71%, and 53%, respectively. A significant increase in SOx (4.5 times), NOx (3.8 times), and PM2.5 concentration (3.5 times) was observed in stubble burning periods as compared to pre-burning (p < 0.05). A positive and significant correlation among the three pollutant concentrations was observed (p < 0.01). The AQI of KA site in Karnal district fell in severely polluted category during 2016 for rice as well as wheat residue burning period, and of KK site in Kaithal during wheat residue burning in year 2017. Results of present study indicate a remarkable increase in pollutant concentration (SOx, NOx, and PM2.5) during the crop residue burning periods. To the best of our knowledge, the outcomes of present study in this region have not been reported in earlier reports. Hence, there is an urgent need to curb air pollution by adopting sustainable harvesting technologies and management of residues. 相似文献
8.
In order to determine the influence of SO 2 fumigation of soybean plants on yield, a three-year experiment was conducted on 485 plois of soybeans. Single fumigations of S0 2 were applied at 10 different stages of growth in 1968-69 and 7 stages of growth in 1970. A linear relationship was found to exist beiween the percent of leaf area destroyed and ihe percent crop loss with a significant regression coefficient of b = —0.659, or iwo-thirds of one percent crop loss for each percent of area destroyed. No definite significant stage-of-growth effect was found and no treatment effects were significant for the early stages of growth from the 3-leaf to the 15-leaf stage, nor was there any loss in yield without visible leaf injury. 相似文献
9.
ABSTRACT Daily counts of non-accidental deaths in Santiago, Chile, from 1988 to 1996 were regressed on six air pollutants— fine particles (PM 2.5), coarse particles (PM 10–2.5), CO, SO 2, NO 2, and O 3. Controlling for seasonal and meteorological conditions was done using three different models— a generalized linear model, a generalized additive model, and a generalized additive model on previously filtered data. Single- and two-pollutant models were tested for lags of 1-5 days and the average of the previous 2-5 days. The increase in mortality associated with the mean levels of air pollution varied from 4 to 11%, depending on the pollutants and the way season of the year was considered. The results were not sensitive to the modeling approaches, but different effects for warmer and colder months were found. Fine particles were more important than coarse particles in the whole year and in winter, but not in summer. NO 2 and CO were also significantly associated with daily mortality, as was O 3 in the warmer months. No consistent effect was observed for SO 2. Given particle composition in Santiago, these results suggest that combustion-generated pollutants, especially from motor vehicles, may be associated with increased mortality. Temperature was closely associated with mortality. High temperatures led to deaths on the same day, while low temperatures lead to deaths from 1 to 4 days later. 相似文献
10.
Under the National Ambient Air Quality Standards (NAAQS), put in place as a result of the Clean Air Amendments of 1990, three regions in the state of Utah are in violation of the NAAQS for PM 10 and PM 2.5 (Salt Lake County, Ogden City, and Utah County). These regions are susceptible to strong inversions that can persist for days to weeks. This meteorology, coupled with the metropolitan nature of these regions, contributes to its violation of the NAAQS for PM during the winter. During January–February 2009, 1-hr averaged concentrations of PM 10-2.5, PM 2.5, NO x, NO 2, NO, O 3, CO, and NH 3 were measured. Particulate-phase nitrate, nitrite, and sulfate and gas-phase HONO, HNO 3, and SO 2 were also measured on a 1-hr average basis. The results indicate that ammonium nitrate averages 40% of the total PM 2.5 mass in the absence of inversions and up to 69% during strong inversions. Also, the formation of ammonium nitrate is nitric acid limited. Overall, the lower boundary layer in the Salt Lake Valley appears to be oxidant and volatile organic carbon (VOC) limited with respect to ozone formation. The most effective way to reduce ammonium nitrate secondary particle formation during the inversions period is to reduce NO x emissions. However, a decrease in NO x will increase ozone concentrations. A better definition of the complete ozone isopleths would better inform this decision. Implications: Monitoring of air pollution constituents in Salt Lake City, UT, during periods in which PM2.5 concentrations exceeded the NAAQS, reveals that secondary aerosol formation for this region is NOx limited. Therefore, NOx emissions should be targeted in order to reduce secondary particle formation and PM2.5. Data also indicate that the highest concentrations of sulfur dioxide are associated with winds from the north-northwest, the location of several small refineries. 相似文献
11.
A continuous ambient automobile pollution monitoring pr1ogramme was initiated in the Johannesburg region in May 1982 and shows that automobile pollution levels which give rise to photochemical smog have slowly increased since this date. Non-methane hydrocarbons in the city centre exceed the U.S. Environmental Protection Agency (USEPA) standard for more than 50% of the time. Downwind of the city centre, ozone hourly averages have exceeded the USEPA standard on 8 days during the 1984/85 season. In comparison, ozone concentrations of the Sydney region exceeded the USEPA standard on 7 days during the wet 1983/84 season (NSW, 1984). From site comparisons it is found that O 3 data are very similar at out of town stations. It is concluded that these results only arise because the O 3 is formed in a well-mixed layer over the region, leading to a high degree of correlation between O 3 peaks. 相似文献
12.
Abstract Airborne fine particles of PM 2.5-10 and PM 2.5 in Bangkok, Nonthaburi, and Ayutthaya were measured from December 22, 1998, to March 26, 1999, and from November 30, 1999, to December 2, 1999. Almost all the PM 10 values in the high-polluted ( H) area exceeded the Thailand National Ambient Air Quality Standards (NAAQS) of 120 μg/m 3. The low-polluted ( L) area showed low PM 10 (34–74 μg/m 3 in the daytime and 54–89 μg/m 3 at night). PM 2.5 in the H area varied between 82 and 143 μg/m 3 in the daytime and between 45 and 146 μg/m 3 at night. In the L area, PM 2.5 was quite low both day and night and varied between 24 and 54 μg/m 3, lower than the U.S. Environmental Protection Agency (EPA) standard (65 μg/m 3). The personal exposure results showed a significantly higher proportion of PM 2.5 to PM 10 in the H area than in the L area ( H = 0.80 ± 0.08 and L = 0.65 ± 0.04). Roadside PM 10 was measured simultaneously with the Thailand Pollution Control Department (PCD) monitoring station at the same site and at the intersections where police work. The result from dual simultaneous measurements of PM 10 showed a good correlation (correlation coefficient: r = 0.93); however, PM levels near the roadside at the intersections were higher than the concentrations at the monitoring station. The relationship between ambient PM level and actual personal exposures was examined. Correlation coefficients between the general ambient outdoors and personal exposure levels were 0.92 for both PM 2.5 and PM 10. Bangkok air quality data for 1997–2000, including 24-hr average PM 10, NO 2, SO 2, and O 3 from eight PCD monitoring stations, were analyzed and validated. The annual arithmetic mean PM 10 of the PCD data at the roadside monitoring stations for the last 3 years decreased from 130 to 73 μg/m 3, whereas the corresponding levels at the general monitoring stations decreased from 90 to 49 μg/m 3. The proportion of days when the level of the 24-hr average PM 10 exceeded the NAAQS was between 13 and 26% at roadside stations. PCD data showed PM 10 was well correlated with NO 2 but not with SO 2, suggesting that automobile exhaust is the main source of the particulate air pollution. The results obtained from the simultaneous measurement of PM 2.5 and PM 10 indicate the potential environmental health hazard of fine particles. In conclusion, Bangkok traffic police were exposed to high levels of automobile-derived particulate air pollution. 相似文献
13.
We investigated the effect of leaf age on the response of net photosynthesis (A), stomatal conductance ( gwv), foliar injury, and leaf nitrogen concentration (N L) to tropospheric ozone (O 3) on Prunus serotina seedlings grown in open-plots (AA) and open-top chambers, supplied with either carbon-filtered or non-filtered air. We found significant variation in A, g wv, foliar injury, and N L ( P < 0.05) among O 3 treatments. Seedlings in AA showed the highest A and g wv due to relatively low vapor pressure deficit (VPD). Older leaves showed significantly lower A, g wv, N L, and higher foliar injury ( P < 0.001) than younger leaves. Leaf age affected the response of A, g wv, and foliar injury to O 3. Both VPD and N L had a strong influence on leaf gas exchange. Foliar O 3-induced injury appeared when cumulative O 3 uptake reached 8-12 mmol m −2, depending on soil water availability. The mechanistic assessment of O 3-induced injury is a valuable approach for a biologically relevant O 3 risk assessment for forest trees. 相似文献
14.
Cucumber and bean plants were pretreated with different SO 2 concentrations for various lengths of time and subsequently exposed to an injurious O 3 exposure. In cucumber, increasing levels of SO 2 and increasing length of pre-exposure progressively enhanced O 3 injury. In bean O 3 sensitivity progressively decreased with both increasing SO 2 concentration and length of pre-exposure. The effect of SO 2 was not related to measurable increases in tissue S content. SO 2 concentrations as low as 20 ppb can increase O 3 sensitivity in cucumber. 相似文献
15.
We investigated the influence of elevated CO 2 and O 3 on soil N cycling within the soybean growing season and across soil environments (i.e., rhizosphere and bulk soil) at the Soybean Free Air Concentration Enrichment (SoyFACE) experiment in Illinois, USA. Elevated O 3 decreased soil mineral N likely through a reduction in plant material input and increased denitrification, which was evidenced by the greater abundance of the denitrifier gene nosZ. Elevated CO 2 did not alter the parameters evaluated and both elevated CO 2 and O 3 showed no interactive effects on nitrifier and denitrifier abundance, nor on total and mineral N concentrations. These results indicate that elevated CO 2 may have limited effects on N transformations in soybean agroecosystems. However, elevated O 3 can lead to a decrease in soil N availability in both bulk and rhizosphere soils, and this likely also affects ecosystem productivity by reducing the mineralization rates of plant-derived residues. 相似文献
16.
Soybean percent crop reduction was estimated as a function of ambient O 3 concentrations for each of 80 agricultural sites in the National Aerometric Data Bank (NADB) for each available year of data for years 1981-1985. Fourteen O 3 concentration statistics were calculated for each of the resulting 320 site-years of data. The two statistics that correlated best with estimated crop reduction were an effective mean O 3 concentration (1 percent of variance unexplained) and an arithmetic mean O 3 concentration (4 percent unexplained). The worst correlation of the 14 was for the statistic used in the present O 3 National Ambient Air Quality Standard (NAAQS), the second highest daily maximum 1-h O 3 concentration (42 percent unexplained). The number of site-years for estimated percent soybean yield reductions was plotted versus increasing O 3 concentrations for each of the 14 O 3 statistics. A maximum crop reduction line was drawn on each plot. These lines were used to estimate (and list) potential ambient O 3 standards for each of the 14 statistics that would limit soybean crop reduction at agricultural. NADB sites to 5, 10, 15, or 20 percent. 相似文献
17.
Sulphur dioxide has been monitored for many years at several rural sites in east-central England, and its temporal and spatial distribution and sources are reasonably well established. The air quality limit values of the Council of the European Communities are not exceeded. NO, NO 2 and O 3 have also been measured continuously for over 5 years at one rural site and for 2 years at another three sites in this region, and preliminary distribution patterns of these gases are available. The oxides of nitrogen, like SO 2, are greatest on average in winter months, but O 3 is greatest on average in May, although peak hourly events exceeding the World Health Organisation Environmental Health Criteria (WHOEHC) are common during other summer months. The oxides of nitrogen have exceeded the WHOEHC on occasion, and these are thought to have derived mostly from motor vehicles in distant towns, the gases then travelling in shallow inversion layers.Rainwater acidities and other constituents have been measured for over 7 years at several sites in the region, initially on a weekly basis, but in recent years on a daily and then an hourly basis at a few sites, and preliminary distribution patterns are available. Rainwater acidity is greatest on average in Spring, following the O 3 pattern more closely than those of the other gases. Daily deposited acidity is episodal. Hourly concentrations of acidity in rainwater during rain events show more than one type of pattern. 相似文献
18.
Historically, studies of the effects of the main phytotoxic gases (SO 2, O 3, NOx and HF) have focused on determining the threshold for onset of visible foliar injury. The current U.S.A. air quality standards to protect vegetation (500 ppb SO 2 for 3 h and 120 ppb O 3 for l h not to be exceeded more than once per annum) are good examples of the use of this information in the regulatory process. More recently, research has focused on determining the thresholds for effects on economically important yield parameters irrespective of foliar injury. The implication is that long-term seasonal or annual standards may be required to prevent yield losses particularly for the primary pollutants in diffuse-source regions and for secondary pollutants. This paper reviews the literature on thresholds for yield effects of SO 2 and O 3 and concludes that - 1.(a) the current EEC standard for SO2 is adequate to protect most crops and trees and
- 2.(b) more work is required to determine whether the U.S.A. threshold for O3 effects are applicable to the climate and crops of Europe.
Recent results suggest that yield responses vary so much with climatic factors that broad regional standards may not be acceptable. In addition, the effect of one phytotoxic gas must now be assessed against the background of the other gases.Future research on effects of SO 2 and O 3 in particular, will be increasingly influenced by the use of cost-benefit analysis in the regulating process and the consequent demand for dose-response relationships. This approach is fraught with difficulty and particular problems arise - 1.(a) when ‘hypothetical’ relationships are assumed in the absence of good data and
- 2.(b) when the linearity of dose-response relationships are presumed to justify the extrapolation from effects at high concentrations to lower ambient concentrations.
The evidence for nutritional effects of low levels of SO 2 and NOx abrogates this assumption and suggests that for some gases at least, there should be a threshold below which no detrimental effects occur. This paper reviews the recent work aimed at producing dose-response relationships for economically important yield parameters. 相似文献
19.
Exposure and flux-based indices of O 3 risk were compared, at 19 forest locations across Bavaria in southern Germany from 2002 to 2005; leaf symptoms on mature beech trees found at these locations were also examined for O 3 injury. O 3 flux modelling was performed using continuously recorded O 3 concentrations in combination with meteorological and soil moisture data collected from Level II forest sites. O 3 measurements at nearby rural open-field sites proved appropriate as surrogates in cases where O 3 data were lacking at forest sites (with altitude-dependent average differences of about 10% between O 3 concentrations). Operational thresholds of biomass loss for both O 3 indices were exceeded at the majority of the forest locations, suggesting similar risk under long-term average climate conditions. However, exposure-based indices estimated higher O 3 risk during dry years as compared to the flux-based approach. In comparison, minor O 3-like leaf injury symptoms were detected only at a few of the forest sites investigated. Relationships between flux-based risk thresholds and tree response need to be established for mature forest stands for validation of predicted growth reductions under the prevailing O 3 regimes. 相似文献
20.
The present study deals with the evaluation of effects of ambient gaseous air pollution on wheat ( Triticum aestivum L. var. HUW-234) growing in a suburban area situated in eastern Gangetic plain of India, using open top chambers. Eight hourly air monitoring was conducted for ambient concentrations of SO 2, NO 2 and O 3 in filtered chambers (FCs), non-filtered chambers (NFCs) and open plots (OPs). Various morphological, physiological and biochemical parameters were assessed during different developmental stages and finally yield parameters were quantified at the time of harvest.Mean concentrations of SO 2, NO 2 and O 3 were 8.4, 39.9 and 40.1 ppb, respectively during the experiment in NFCs. Concentrations of SO 2, NO 2 and O 3 reduced by 74.6%, 84.7% and 90.4%, respectively in FCs as compared to NFCs. Plants grown in FCs showed higher photosynthetic rate, stomatal conductance, chlorophyll content and Fv/Fm ratio as compared to the plants in NFCs and OPs. Lipid peroxidation, proline, total phenol and ascorbic acid contents and peroxidase activity were higher in plants grown in NFCs. There were improvements in morphological parameters of plants growing in FCs as compared to those in NFCs and OPs. Yield of plants also increased significantly in FCs as compared to those ventilated with ambient air (NFCs) or grown in OPs. During the vegetative phase, NO 2 concentrations were higher than O 3, but O 3 became dominant pollutant during the time of grain setting and filling. The study concludes that O 3 and NO 2 are the main air pollutants in the sub-urban areas causing significant yield reductions in tropical wheat plants. 相似文献
|