Comparison of the plant-damaging spectral solar ultraviolet radiation between three locations in Eastern USA in the year 2000

The National Ultraviolet Monitoring Center (NUVMC) maintains a network of Brewer Spectrophotometers that collect spectrally resolved, full sky ultraviolet (UV) irradiance values throughout the day. Using these data, an investigation into the spectral UV irradiances at several Brewer locations has been carried out by employing plant action spectra that represent a generalized response of plants to UV exposure. Analysis was performed for the year 2000 on the Chicago, Virgin Islands, and Shenandoah Brewer sites of the Eastern USA, which are of varying latitude, elevation, and atmospheric composition. The weighted and unweighted UV data grouped in SZA ranges of 10° increments is analyzed seasonally, highlighting the seasonal atmospheric differences between the sites. Results obtained in this paper suggest that UV data, when weighted with certain plant action spectra, show the potential sensitivity of plants to small changes in UV irradiances.     

Exchange of ozone and nitrogen oxides between the atmosphere and coniferous forest

The deposition flux of O₃ to a Douglas fir forest in the Netherlands was monitored by eddy correlation during nine months. At the same time the concentration gradients of NO, NO₂ and O₃ were determined over the forest. The canopy resistance to O₃ uptake was calculated from the measurements and it compared well with model estimates. The sensitivity of the stomatal resistance to humidity calculated in the model was adapted to improve the comparison. A multi-layered model of canopy exchange which included the influence of chemical reactions between NO and O₃ and soil emissions was used to interpret the results for NO₂. The observed fluxes of NO₂ away from the surface into the atmosphere were probably caused by soil emissions of NO. The soil-emitted NO was converted to NO₂ in the trunk space and vented into the atmosphere. The model showed that the NO₂ flux above the canopy was either away or towards the canopy depending on the strength of the soil emission and the amount of NO₂ taken up in the canopy. A canopy compensation point for NO₂ could be established above which deposition was the main process and below which emission was observed. The model calculations supported the observations which indicated a compensation point of approximately 10 ppb NO₂.     

Growth and marketable-yield responses of potato to increased CO2 and ozone

Central to the CHanging climate and potential Impacts on Potato yield and quality project (CHIP) was the consideration of the potential impacts of ozone and CO₂ on growth and yield of future European Potato crops. Potato crops, cv. Bintje, were exposed to ambient or elevated ozone; targeted daily average, 60 nl l⁻¹ for 8 h, and ambient or elevated CO_2; targeted 680 μl l⁻¹ averaged over the full growing season, in open top chambers (OTCs) at six European sites in 1998 and 1999, or to elevated CO₂ (550 μl l⁻¹) in Free Air Carbon dioxide Enrichment facilities (FACE) at two sites in both years. Some OTC experiments included 550 μl l⁻¹. Above and below ground biomass were measured at two destructive harvests; at maximum leaf area (MLA) and at final-harvest. Final-harvest fresh weight yields of marketable-size tubers, >35 mm diameter, from ambient conditions ranged from 1 to 12 kg m⁻². There was no consistent (P>0.1) CO₂×O₃ interaction for growth or yield variables at either harvest. No consistent effects of ozone were detected at the maximum-leaf-area harvest. However, at final harvest, ozone had reduced both above-ground biomass and tuber dry weight (P<0.05), particularly of the largest (>50 mm) size class. These yield losses showed linear relationships both with accumulated ozone exposure; AOT40 expressed as nl l⁻¹ h over 40 nl l⁻¹, and with yields from chambered ambient-ozone treatments (P<0.05) but, because of partial confounding between the treatment AOT40s and the ambient-ozone yields in the data, the two relationships were not completely independent. Yields from ambient-ozone treatments, however, explained a significant (P<0.01) amount of the residual variation in ozone effects unexplained by AOT40. When averaged over all experiments, mean dry weights and tuber numbers from both harvests were increased by elevated CO₂. Only green leaf number at the MLA harvest was reduced. The CO₂ responses varied between sites and years. For marketable-size tubers, this variation was unrelated to variation in ambient-CO₂ treatment yields. Yield increases resulting from the 680 μl l⁻¹ and 550 μl l⁻¹ treatments were similar. Thus elevating [CO₂] from 550 to 680 μl l⁻¹ was less effective than elevating [CO₂] from ambient to 550 μl l⁻¹. On average, CO₂ elevation to 680 μl l⁻¹ increased the dry weight of marketable-size tubers by about 17%, which far exceeded the average ozone-induced yield loss of about 5%. The net effect of raising CO₂ and O₃ concentrations on the European potato crop would be an increase marketable yield.     

Ozonation of seawater improves the survival of larval southern rock lobster, Jasus edwardsii, in culture from egg to juvenile

Phyllosoma larvae of the southern rock lobster, Jasus edwardsii, were cultured from egg to juvenile. For larvae reared from hatch to Stage III, survival was highest and bacterial contamination was lowest in seawater ozonated at low and moderate levels (400 and 500 mV oxidation-reduction potential, ORP). By contrast, at high ozonation (600 mV), all larvae suffered deformities at the moult to Stage II and terminally starved, while in unozonated water (about 300 mV), all larvae died at Stage III probably as a consequence of Vibrio bacteria proliferation. In a second experiment between Stages VI to VIII, larval survival was highest in ozonated water that had been filtered through activated charcoal and coral sand, compared to ozonated water with no filtration or filtered only through activated charcoal. Ozonated water with the combined filtration was used subsequently but there were ongoing deformities, so the level was progressively reduced from 400 mV at Stage VIII to 330 mV at Stage X, at which time ozonation was discontinued. Larvae were then cultured in unozonated water to metamorphosis of eight pueruli at 377 to 437 days after hatch, of which two survived to juvenile. Ozonation was thus effective up to Stage IX in improving culture water to minimise bacterial disease without problems of larval deformities.     

The influence of plastic composition and ventilation area on ozone diffusion through some food packaging materials

Regulatory approval of ozone has increased commercial interest in the development of applications to ensure produce quality and safety. However, ozone sometimes fails to inactivate microorganisms on packaged produce and this may be a consequence of poor diffusion into packages. Gaseous ozone (900 ± 12 μL/L) was applied to several common plastic films with a range of ventilation areas and diffusion through them determined. A semi-quantitative method using the reaction of ozone with indigo trisulfonate or with indigo carmine dye solutions was used. Dye de-colorization occurred relatively rapidly (in less than 1 h) after exposure to ozone, indicating that it diffused through all tested materials. Although the extent of ozone diffusion followed the sequence of high-density polyethylene > polypropylene > low density polyethylene, differences among them were small and not significant (P > 0.05). Ozone diffusion was also determined through a low density polyethylene film with ventilation areas of 1.3, 5.2, and 10.4% created by circular holes 6.5 mm in diameter. Gradual but modest increases in ozone diffusion occurred as the ventilation area increased.     

应用臭氧·液体菌种生产无公害金针菇技术研究

[目的]为了改变金针菇生产周期长、常规消毒药剂残留量大、对人体的刺激严重等缺点。[方法]试验设置臭氧消毒+液体菌种、甲醛消毒+液体菌种、臭氧消毒+固体菌种、甲醛消毒+固体菌种4个组合处理,以甲醛消毒+固体菌种为对照研究比较了臭氧和液体菌种的应用技术。[结果]臭氧+液体菌种组合比对照菌丝长满培养袋时间短10 d左右,产量和产品质量明显提高,污染率下降。[结论]液体菌种和臭氧消毒在金针菇生产上是值得推广的技术。     

臭氧在果品保鲜中的应用研究

臭氧是一种强氧化剂,具有消毒杀菌、漂白、脱色、除臭、去味等作用.本文介绍了臭氧的特性及产生方法,臭氧的作用机理,在冷库中的应用和使用中应注意的问题.     

臭氧对冻虾仁微生物的控制及在生产应用的研究

采用臭氧消毒对冻虾仁中的微生物进行控制，冻虾仁总菌数大大减少，同时有效地抑制了冻虾仁中常见的致病菌的发生率，且感官特性无显著变化。     

地表臭氧含量增加和UV-B辐射增强对大豆生物量和产量的影响

利用开顶式气室(OTC)设置4个处理对大豆进行O3与UV-B增强的大田试验,通过观测生物量和产量研究两者对大豆生长的影响。T1为O3含量100nmol/mol的处理,T2为UV-B辐射强度比CK增加10%的处理,T3为T1和T2的复合处理,CK为自然空气。结果表明,O3含量与UV-B辐射增强的单因素对大豆株高、叶面积、茎干重等生物量都有不同程度的负影响,而两者复合后对各生物量的影响效果不一致,在分枝期至结荚期拮抗作用居多,而协同作用则多出现在生育期末期。在整个生育期,各处理均表现为茎分配指数变化幅度较小,CK、T1、T2、T3的根和叶分配指数逐渐降低,且荚分配指数呈快速上升的趋势。由此可见,O3和UV-B辐射单因子胁迫对大豆生物量和产量均产生不同程度的负效应,而两者的复合作用并不是两个单独作用的简单累加。     

臭氧对设施蔬菜病虫害的应用效果

为明确臭氧水及气体在设施蔬菜病虫害防治中的应用效果,在设施条件下研究了臭氧水处理不同作物种子、臭氧水浇灌防治土传病害、臭氧气体对设施蔬菜主要病虫害的防治以及对蔬菜作物的伤害试验。结果表明,用臭氧功能水处理种子,在适宜浓度下能够促进作物种子的代谢和萌发;对发病初期的黄瓜根腐病、番茄青枯病、辣椒疫病等土传病害有一定的抑制作用。使用臭氧发生设备在温室内释放臭氧气体,对黄瓜霜霉病、白粉病、角斑病及灰霉病等气传病害有一定的防治效果;在室内可控条件下,释放臭氧30s,连续释放10次,每次间隔时间10min时,对烟粉虱、南美斑潜蝇的杀灭效果可达100%。总结出温室内臭氧释放的最佳浓度为0.8～1.0mg/m3,既能有效防治温室蔬菜病虫害,又不会对蔬菜作物生长发育产生伤害。