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1.
Ozone toxicity can reduce soybean yields by an estimated 5 to 20%. The most economical and practical solution to the problem would be to use ozone‐tolerant cultivars. Because ozone toxicity is an oxidative stress, one would expect that plants having higher concentrations and proper kinds of antioxidants would be more tolerant. To test this hypothesis, 20 soybean lines or cultivars varying in contents of flavonol glycosides (naturally occurring antioxidants) were tested for ozone tolerance in a fumigation chamber and in phyto‐toxic concentrations of ozone in ambient, unfiltered, air in a greenhouse. In general, ozone tolerance was associated with the presence of kaempferol glycosides, particularly K3 through K6 and K9. Lines containing no kaempferol glycosides (OX942 & OX281) were among the most sensitive to ozone stress. The K9 compound has been associated with reduced numbers of stomata, drought tolerance, and slower growth rates, and this could reduce ozone absorption and toxicity, or K9 may be more effective in detoxifying ozone than other glycosides. Lee soybean was more tolerant to ozone and to manganese (Mn) toxicity (also an oxidative stress) than Forrest. Cross tolerances of plant genotypes to these two stresses deserve additional study. Among cultivars compared, Mukden was ozone tolerant, Columbia and Harosoy were sensitive, and Blackhawk was moderately sensitive.  相似文献   

2.
为对比不同气源的介质阻挡放电型低温等离子体发生器的性能参数,分别以氧气和空气为气源,对发生器进行了静态对比试验,研究了放电电极面积、放电电压峰峰值、气体体积流量对放电功率、单周期电荷传输量、O_3浓度、O_3产量和O_3产率的影响。结果表明,当放电电极面积增大时,放电功率和单周期电荷传输量均线性增大,但空气源对应的放电功率和单周期电荷传输量及其增长速率较低;此时,氧气和空气源的O_3浓度整体呈上升趋势而O_3产率则呈下降趋势。当放电电压峰峰值增大时,氧气和空气源的放电功率和单周期电荷传输量均显著增大,且后期增大速率加快;O_3浓度均先升后降而O_3产率则逐渐减小,高浓度和高产率不可兼得。不同放电频率下,氧气源的最大臭氧浓度大于55 mg/L,空气源的最大臭氧质量浓度在4~8 mg/L之间。当气体体积流量增大时,氧气源的放电功率和单周期电荷传输量均先上升后趋于平缓,而空气源的放电功率和单周期电荷传输量则逐渐增大;氧气源的O_3浓度下降,O_3产量上升直至平缓,而空气源的O_3浓度则先增后减,O_3产量逐渐上升但上升速率放缓;氧气源和空气源的O_3产率均随气体体积流量的增大而缓慢上升。以氧气为气源时,气体体积流量不宜超过10 L/min;以空气为气源时,气体体积流量可选取为9 L/min左右。研究结果可为低温等离子体喷射系统优化及柴油机颗粒物捕集器的再生研究提供参考。  相似文献   

3.
A new Model of Ozone Deposition and Detoxification (MODD) is presented. This model describes stomatal ozone uptake and deposition on external plant surfaces and soil; it accounts for diurnal variability of detoxification processes and reactive ozone uptake on cuticular waxes and soil surface. The mechanistic modelling of plant defense reactions is based on the Plöchl et al. (2000) detoxification model in which the dynamics of apoplast chemistry are considered. To estimate ozone deposition fluxes on cuticular waxes and soil surface, we use a revised version of the Morrison and Nazaroff (2002) model developed to account for ozone uptake on material surfaces. This model which has been fully integrated with a soil-plant-atmosphere continuum model ensures a complete coupling between stomatal conductance and O3 exchanges between leaves and the atmosphere. The observed diurnal variations in stomatal conductance which largely control the influx of O3 into the leaf are well reproduced. Model simulations point out that the pool of ascorbate located in the mesophyll cell wall plays a significant role in the detoxification of O3. Besides stomatal conductance, it is the key process involved in the control of ozone flux to the cell wall. A decrease in the pool of ascorbate lengthens the chemical lifetime of O3 in the cell wall then the virtual apoplastic resistance is found to increase with decreasing ascorbate. Although the atmospheric ozone concentration increases as the weather becomes hot and dry, the virtual apoplastic resistance follows the same trend, indicating a decrease of the ascorbate pool in the mesophyll cell wall. Results also indicate that for the pre-senescence period 57% of the ozone is deposited onto the cuticular surfaces, 4% on soil and only 37% is absorbed by stomata. The comparison of modelled and measured data reported in this study indicates that the model is capable of predicting the major features of the patterns of total ozone flux.  相似文献   

4.
Ribas  A.  Filella  I.  Gimeno  B. S.  Peñuelas  J. 《Water, air, and soil pollution》1998,107(1-4):347-365
A field study was conducted from May to October 1995 to assess ozone (O3) phytotoxicity in Catalonia (NE Spain) by determining a percentage value of leaf area injured by ozone on three tobacco cultivars, Bel-W3, Bel-C and Bel-B as bioindicators. Colorimetric parameters were also determined in an effort to have an objective assessment of ozone injury. The study was conducted simultaneously on eight sites where ozone levels and several meteorological parameters were continuosly monitored. Two sets of plants were used at each site. The first one was composed of six plants of each cultivar which were changed every two weeks while the second one involved two plants of each cultivar which were kept in the plots throughout the whole experimental period. Open Top Chambers were also used to test the response of the three cultivars to ozone under controlled conditions. The ozone levels correlated well with ozone injury on the Bel-W3 cultivar but not as well on the other two cultivars. The ozone levels did not fully account for all the observed injury. The response of tobacco plants to ozone concentrations and therefore its biomonitoring capacity depended also on different environmental conditions linked to stomatal behaviour such as temperature, humidity, wind or altitude. These environmental conditions had some effects on the intensity of Ozone injury. Ozone concentrations accumulated over a threshold of 60 ppb (AOT60) when VPD was below 1 KPa. Correlated well with the ozone injury and best explained the intensity tobacco injury symptoms. For large plants growing throughout the whole period of study, Bel-C was the best indicator cultivar for AOT60 over the 3 days prior to the last ozone injury assessment. The colorimetric parameters were indicators of seasonal changes but they were not good ozone damage indicators. It is concluded that tobacco cultivars were good bioindicators but meteorological and other environmental factors need to be considered in there use as biomonitors.  相似文献   

5.
California's 14-year, $25 million acidic deposition program has studied the causes and effects of acidic air pollutants. In contrast to the eastern United States where sulfur-derived (S-derived) by-products from coal combustion dominate precipitation chemistry, nitrogen-derived (N-derived) acids predominate in wet and dry deposition in California. Adverse effects on the human lung have not been observed after short-term exposures to acidity, but extended exposures to ambient acidity may pose a chronic risk. No irreversible, adverse effects on surface waters in the Sierra Nevada mountain range or to the state's forests have been found due to extant acidic inputs. The longer-term outlook for forests is less certain because the impacts observed elsewhere occurred after decades of S and N deposition, but at lower ambient ozone levels. Ozone is the major air pollutant stressor for forests, but atmospheric N has the potential to cause adverse changes in soil nutrient cycling. Impacts on man-made materials in southern California (e.g., galvanized steel) were found to be minor. While California does not have an ambient air quality standard for acidic air pollutants, emissions of precursors have declined since the 1960's due to changes in industrial practices, improvements in technology, and adoption of control measures for ozone. Lowering emissions from motor vehicles will be emphasized to prevent future increases in N deposition.  相似文献   

6.
Ground-level ozone concentrations were estimated for Greece during a summer period of the year 2000 using the regional air quality model UAM-V off-line coupled with the mesoscale meteorological model MM5. An anthropogenic NOx, NMVOCs and CO emission inventory and biogenic NMVOCs emission data were used to support model simulations. The evaluation analysis indicates a quite satisfactory model performance in reproducing ozone levels. The simulated mean ozone concentrations are above the 32-ppb EU phytotoxicity limit over almost all continental and maritime areas of Greece. Over the greater part of the country, the background mean ozone levels range from 40 to 55 ppb. Ozone values higher than the 55-ppb EU human health protection limit reaching 60 ppb dominate part of the southern Aegean Sea that is influenced by the Athens urban plume. In the areas where anthropogenic emission densities are high, the mean ozone levels vary between 20 and 40 ppb. Over the greater part of Greece, the simulated mean daily maximum ozone concentrations range from 50 to 65 ppb. More enhanced maximum ozone concentrations up to 95 ppb mainly dominate over the greater areas of the two largest Greek urban centres (Athens and Thessaloniki) and over the continental and maritime areas south of Athens which are under the influence of the urban plume.  相似文献   

7.
Abstract

Variations in papaya yields and fruit quality between papaya growers in Keaau, Hawai’i are mainly caused by differences in nutrient management. The objectives of this study were to (1) identify soil chemical properties and plant mineral compositions and their correlations in commercial papaya orchards; (2) compare soil chemical properties and plant nutrient concentrations between papaya orchards with low, medium and high fruit yields; (3) compare soil chemical properties and plant nutrient composition between orchards with low, medium and high fruit quality; (4) determine the difference in soil chemical properties, plant nutrient composition, and papaya yield and quality between new and long-term papaya land. Between 2016 and 2018, soil and plant tissue samples were collected from 100 commercial papaya orchards. Soil pH, potassium (K), calcium (Ca), and magnesium (Mg) were below and phosphorus (P) was above the recommended range for papaya. Petiole P, K, Ca, and sulfur (S) concentrations were below the recommended range. Fields with low fruit yields and low fruit quality were deficient in P, K, Ca, and zinc (Zn). Long-term papaya land had significantly (p?<?0.05) lower soil pH, total carbon (C), K, Ca, Mg, and sodium (Na), and higher concentrations of soil P than new papaya land. Nitrogen (N), boron (B), zinc (Zn), and copper (Cu) was significantly higher and Ca was significantly lower in petioles from papaya crops grown on long-term papaya land compared to new papaya land.  相似文献   

8.
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   

9.
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   

10.
Ozone effects on Mediterranean forests were studied for 10 years in southern France. The aim of these studies was to understand the impact of the pollutant on foliar damage among Aleppo pine (Pinus halepensis Mill) and Arolla pine (Pinus cembra L) populations. During the summers of 2001 and 2002, ozone concentrations were measured using UV absorption analysers (4) and passive samplers (29) at two forest monitoring sites: Site 1 in the Nice coastal area for Aleppo pine and Site 2 in the Mercantour mountains for Arolla pine, in the vicinity of tree observation sites. AOT 40 values were quite high (25–33 ppm.h), especially in the Mercantour mountains, for the 5 months of measurement. Foliar damage (defoliation and discoloration) and specific symptoms (chlorotic mottle) were observed on 8 Aleppo pine and 13 Arolla pine plots. For Arolla pines, there was a significant correlation between defoliation and chlorotic mottles. There was also a correlation between mean ozone concentrations measured by passive samplers and chlorotic mottles. These correlations were less significant for Aleppo pine.  相似文献   

11.
The Lizard Peninsula is an isolated area of unique and sensitive ecology and the occurrence of damaging ozone concentrations over the peninsula in spring challenges the successful sustainable management of the area. Ozone concentrations over Goonhilly Downs on the Lizard Peninsula in Cornwall were measured in spring 2002 using continuous monitoring and spatial mapping (diffusion tubes). Data obtained using a continuous ozone monitor (1/03/02 to 31/03/02) showed that the AOT40 5-day values were in a range from 2 to 800 μg m-3 hr (AOT40 is the sum of the differences between the measured hourly ozone concentration (μg m-3) and 80 μg m-3 (when the concentration exceeds 80 μg m-3) for the hours when global radiation exceeds 50 Wm-2). Contour mapping of ozone concentrations measured with diffusion tubes suggested that over a 2 km2 sampling area significant microscale variations were occurring with ozone concentrations ranging between 48–129 μg m-3 for one two-week period and 62–210 μg m-3 for the other.Unusually high diurnal variations in ozone concentrations were also observed at Goonhilly. It is thought that temperature inversions caused the entrapment of ozone at the surface level.  相似文献   

12.
Rock-surface temperatures were measured on a tor and a large block located below the timberline in the Kobugahara Highlands, an upland plateau composed of granodiorite in central Japan (36°N, E139°, 1300 m a.s.l.). Many blocks in the region originate from core stones distributed on the plateau, and there are several block streams in the valley bottoms. The tor is situated at the upper end of one of these block streams. The large block appears to have detached from another tor. The mean air temperature of the coldest month is − 4 °C. Rock-surface temperatures were recorded continually every 30 min from December 1, 2002 through December 13, 2004 by thermistor probes connected to miniature data loggers. The diurnal and the annual freeze–thaw cycles and effective freeze–thaw cycles were recorded at each site. The freezing index of rock-surface temperature showed a marked variability from year to year. In addition, differences in local conditions at observation sites within a given area greatly affected the rock-surface temperature. These are important considerations in relation to local weathering below the timberline.  相似文献   

13.
采用核磁共振(NMR)技术对以葡萄糖、海藻糖、蔗糖、赖氨酸构成的模型食品进行磁共振实验,绘制体系NMR状态图并计算转折点温度,同时在不同温度下进行储藏实验,考察体系中葡萄糖的变化,评估不同储藏温度下的Maillard反应速率.结果表明:模型食品体系含水量不同、非反应组分含量不同,其NMR转折点温度有所不同.低水分含量的体系具有相对高的NMR转折点温度.即使在相同的储藏温度下,含水量相同而非反应组分含量不同的情况下,体系的Maillard反应速率也有所不同.储藏温度处于体系的NMR转折点之下时,体系的Maillard反应速率明显要比在NMR转折点温度之上要慢.由此,可以通过改变食品的配方、含水量等改变体系的NMR转折点温度,可以有效地延长食品的货架期.因此,核磁共振状态图对于评估最佳的储藏温度,以及通过配方设计来延长食品的货价期具有指导意义.  相似文献   

14.
Background, Aim and Scope   Polycyclic aromatic hydrocarbons (PAHs) are formed as a result of incomplete combustion and are among the most frequently occurring contaminants in soils and sediments. PAHs are of great environmental concern due to their ubiquitous nature and toxicological properties. Consequently, extensive research has been conducted into the development of methods to remediate soils contaminated with PAHs. Fenton's reagent or ozone is the most commonly studied chemical oxidation methods. However, the majority of remediation studies use soils that have been artificially contaminated with either one or a limited number of PAH compounds in the laboratory. Hence, it is essential to extend such studies to soils contaminated with multiple PAHs under field conditions. Objectives   The objective of this study is to investigate the capacity of Fenton's reagent and ozone to degrade PAHs in soils. The soils have been collected from a number of different industrial sites and, therefore, will have been exposed to different PAH compounds in varying concentrations over a range of time periods. The capacity of Fenton's reagent and ozone to degrade PAHs in industrially contaminated soils is compared to results obtained in studies using soils artificially contaminated with PAHs in the laboratory. Materials and Methods: Nine soil samples, contaminated with PAHs, were collected from five different industrial sites in Sweden. For the Fenton's reagent procedure, the pH of the soil slurry samples was adjusted to pH 3 and they were kept at a constant temperature of 70oC whilst H2O2 was added. For the ozone procedure, soil samples were mixed with 50% water and 50% ethanol and kept at a constant temperature of 45 oC. Ozone was then continually introduced to each soil sample over a period of four hours. Following the Fenton's reagent and ozone oxidation procedures, the samples were filtered to isolate the solid phase, which was then extracted using pressurized liquid extraction (PLE). The sample extracts were cleaned up using open columns and then analysed by gas chromatography-mass spectrometry (GC-MS). Results: The relative abundance of the detected PAHs varied between soils, associated with different industries. For example, low molecular weight (LMW) PAHs were more abundant in soil samples collected from wood impregnation sites and high overall PAH degradation efficiencies were observed in soils originating from these sites. In the contaminated soils studied, PAHs were more effectively degraded using Fenton's reagent (PAH degradation efficiency of 40-86%) as opposed to ozone (PAH degradation efficiency of 10-70%). LMW PAHs were more efficiently degraded, using ozone as the oxidizing agent, whereas the use of Fenton's reagent resulted in a more even degradation pattern for PAHs with two through six fused aromatic rings. Discussion: The degradation efficiency for both methods was largely dependent on the initial PAH concentration in the soil sample, with higher degradation observed in highly polluted soils. LMW PAHs are more susceptible to degradation than high molecular weight (HMW) PAHs. As a result of this the relative abundance of large (often carcinogenic) PAHs increased after chemical oxidation treatment, particularly after ozone treatment. Repeated Fenton's reagent treatment did not result in any further degradation of soil PAHs, indicating that residual soil PAHs are strongly sorbed. The effectiveness of the two oxidation treatment approaches differed between industrial sites, thus highlighting the importance of further research into the influence of soil properties on the sorption capacity of PAHs. Conclusions: This study demonstrates that the degree to which chemical oxidation techniques can degrade soil bound PAHs chemical degradation is highly dependent on both the concentration of PAHs in the soils and the compounds present, i.e. the various PAH profiles. Therefore, similarities in the PAH degradation efficiencies in the nine soil samples studied were observed with the two chemical oxidation methods used. However, the degradation performance of Fenton's reagent and ozone differed between the two methods. Overall, Fenton's reagent achieved the highest total PAH degradation due to stronger oxidation conditions. LMW PAHs showed higher susceptibility to oxidation, whereas high molecular weight (HMW) PAHs appear to be strongly sorbed to the soils and therefore less chemically available for oxidation. This study highlights the importance of including soils collected from a range of contaminated sites in remediation studies. Such soil samples will contain PAH contaminants of varying concentrations, chemical and physical properties, and have been aged under field conditions. In addition to the chemical and physical properties of the soils, these factors will all influence the chemical availability of PAHs to oxidation. Recommendations and Perspectives: We recommend including aged contaminated soils in chemical degradation studies. In future chemical remediation work, we intend to investigate the potential influence of the chemical and physical properties of PAHs and soil parameters potential influence on the chemical oxidation efficiency in aged contaminated soils. Due to the vast number of contaminated sites there is a great need of efficient remediation methods throughout the world. This study shows the difficulties which may be experienced when applying remediation methods to a variation of contaminated sites.  相似文献   

15.
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   

16.
运用开放式臭氧浓度升高系统（O3-FACE：Ozone-free air controlled enrichment）平台,以武运粳21（粳稻）和两优培九（杂交稻）两个耐性不同的品种为材料,研究了大气臭氧浓度升高对水稻叶片光合作用日变化的影响,旨在为高臭氧浓度条件下水稻生产和国家粮食安全的制定提供理论依据。结果表明,臭氧胁迫未改变光合作用日变化规律,处理和对照下净光合速率和气孔导度日变化相似,均呈现单峰曲线,高峰值出现在11：00—15：00之间;胞间CO2浓度日变化趋势与气孔导度和净光合速率日变化不一致;臭氧处理55 d对净光合速率和气孔导度影响较小,随着处理时间的延长,相关指标降低幅度变大,而胞间CO2浓度没有降低,说明臭氧对水稻的影响是一个累积过程,净光合速率降低的主要因素是由非气孔限制引起的;武运粳21的净光合速率和气孔导度在臭氧处理时的降低幅度小于两优培九,这种品种间的差异表明武运粳21比两优培九对臭氧耐受性强。  相似文献   

17.
臭氧污染对不同品种小麦磷素吸收与分配的影响   总被引：3，自引：0，他引：3  
利用中国稻麦轮作O3-FACE（Free air O3 concentration enrichment）试验平台,研究了小麦（Tritcium aestivum L.）品种的物质积累、磷素的吸收与分配对大气臭氧浓度增加的响应。结果显示,大气臭氧浓度增加50%对供试小麦根和地上部的生物量积累影响差异较大,显著降低了扬麦16、烟农19和嘉兴002的产量,降幅为13.2%-35.7%,但对扬麦15和扬幅麦2号的产量无显著影响。臭氧增加导致5种小麦根系和地上部植株中磷含量呈下降趋势,而籽粒中磷含量却无显著变化。臭氧污染降低了磷在小麦根和籽粒中的积累量,促使小麦植株中磷由根部向地上部转移,增加了籽粒中磷所占比重。高臭氧浓度下扬麦16、烟农19和嘉兴002的磷偏生产力降低9.0-23.8（kg/kg, P2O5）, 磷素利用率显著降低8.2%-20.2%,但扬麦15和扬幅麦2号的磷素偏生产力与利用效率变化不明显。以上结果表明,臭氧污染具有改变小麦物质分配, 影响土壤磷素在土壤-植物系统周转的潜在风险。  相似文献   

18.
The objective of the present study was to determine the degradation products of mancozeb and ethylenethiourea (ETU) and elucidate the possible degradation pathways in solution as a result of chemical oxidation using ozone and chlorine dioxide. This study was developed in a solution at 100 ppm of mancozeb and ETU concentration over the course of 60 min. Two different oxidizing agents used in this study were (1) ozone at 3 ppm and (2) chlorine dioxide at 20 ppm. Ozone was continuously provided throughout the course of the reaction. Degradation products were detected with high-resolution GC-MS. The total analysis time was 4 min per sample combined with rapid GC separation and time-of-flight mass spectrometry (TOFMS). Hydrolysis of mancozeb led to m/z 144 ion fragmentation, which is 5-imidazoledithiocarboxylic acid, as a major degradation product. ETU showed M(+) 102, which corresponds to its mass, indicating this compound was stable in distilled water and did not undergo hydrolysis during 60 min. The average retention times of mancozeb and ETU were approximately 181-189 and 210-230 s, respectively. Ozonation of mancozeb produced ETU as a major product. Treatment of ETU with ozone produced several degradation compounds. From prolonged ozonation, the CS(2) or CS group was removed. Overall, several byproducts identified were M(+) 60, M(+) 84, M(+) 163, M(+) 117, and M(+) 267 by ozone and M(+) 117, M(+) 86, and M(+) 163 by chlorine dioxide treatment. Several of these have been reported, but others have never been reported previously.  相似文献   

19.
The ozone concentration measurement results at two rural stations in Lithuania are presented. Ozone measurements have been carried out at the coastal site since 1980 and at the forested one since 1994. Both stations are far from the influence of the local pollution. The established ozone concentration trends at the coastal station were upward in cold and not so distinct in warm seasons during this monitoring time. The tendency even of a decreasing level in some summer months was established: in June and August. These trend results were very close to the results obtained at other European stations. Comparing ozone levels and courses at both stations, significant differences were determined. Clear differences between monthly daytime and daily ozone concentration averages are observed during the warm season. They were three times larger at a forest site as compared with the results at a coastal one.  相似文献   

20.
循环水养鱼系统中臭氧射流混合设备设计与性能测试   总被引：3，自引：2，他引：1  
为了利用臭氧对养殖水体进行无害化处理,必须使臭氧有效地溶解于水中,以达到净化水质、循环使用的目的。设计结构简单、混合效率高的臭氧混合溶解设备,是实现有效利用臭氧的关键。利用射流器和混合罐相结合的结构,并应用计算流体动力学（Computation Fluid Dynamics,CFD）的模拟方法,对10组射流器进行尺寸参数优选,确定了射流器的主要尺寸参数为：喷射系数0.7、喷嘴直径23?mm、混合管直径42?mm、混合管长度336?mm;通过对研制设备溶解臭氧的监测试验,获得臭氧溶解的变化曲线,臭氧溶解的质量浓度最高可达到0.15?mg/L。根据臭氧溶解曲线和达到的浓度,对养鱼水体进行消毒杀菌、分解有机物、氧化氨氮、凝聚悬浮物处理是完全可行的,达到了设计高效臭氧混合设备的目的。  相似文献   

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