Growth and certain chemical constituents of tobacco plants exposed to air ions

Controlled experiments were performed in Faraday cages on the effects of positive and negative air ions on flue-cured tobacco plants. Continuous exposures for 15 days to air ions showed no significant differences in any plant growth characteristic between the treated and control plants. Standard errors in the measurement of the growth parameters for ion exposed plants were, however, consistently higher than those of control plants. Spatial variation in concentration gradients of air ions produced by corona discharge might have contributed to masking of the relatively small effects of air ions on biological organisms observed in previous experiments in this laboratory. No significant difference was observed between the experimental and control plants in nicotine, total alkaloid, and reducing sugar contents. Total nitrogen content was slightly higher for treated than control plants.     

Effects of small air ions on net blotch disease of barley

Small positive air ions significantly reduced the number of lesions and percentage of leaf area covered by lesions of net blotch disease of barley. Appearance of disease symptoms was delayed by three days when plants were exposed to an atmosphere of positive ions. No such effect was observed for negative air ions. Height and dry weight were significantly stimulated by unipolar ions.     

Effects of air ions on germination ofHelminthosporium teres

Effects of host — pathogen interactions with respect to relatively high concentrations of artificially produced air ions were studied in the laboratory. Continuous and long exposures ofHelminthosporium teres in the culture medium and under controlled conditions to positive air ions, produced a time — delay of about 6 hours on spore germination. Negative ions produced no such effect. Temporary structural abnormalities of the germ tubes were observed for two to three hours when exposed to either positive or negative air ions. Sprayed inoculum of spores on actual leaf surfaces of barley plants, exposed to positive ions, suppressed germination for a considerably longer time than those observed in the culture medium.     

Destruction of human hemoglobin in the presence of water and negative air ions generated by corona discharge

A buffered solution containing hemoglobin was exposed to negative air ions that were generated by corona discharge. In two hours, the optical absorbance at 405 nm decreased to ca., 40% of the value observed prior to the exposure to air ions. After 18 1/2 hours, the absorbance was further decreased to ca. 5% of the original values. The hemoglobin solution exposed to air for this duration did not show any appreciable change in absorbance at 405 nm. Concomitant with the decrease of absorbance at 405 nm, that at 205 nm increased several fold. The molecular weight of the specie(s) which absorbed strongly at 205 nm was ca. 400 daltons. Similar results were obtained when hemoglobin was exposed to ozone (O₃) instead of air ions. From these results and our earlier conclusion that O₃ is generated from negative air ions in the presence of water, it can be concluded that the destruction of hemoglobin was by O₃.     

Enhancement of evaporation rates from thin layers of liquids exposed to air ions

A beta-ray gauge system was used to study evaporation rates and drying times of liquids exposed to relatively high fluxes of air ions of either polarity produced by a corona discharge. Evaporation rates from thin layers of water, ethyl alcohol, and carbon tetrachloride increased considerably when exposed to air ions, compared to untreated liquids under constant environmental conditions. Drying times of liquid layers exposed to air ions were shortened by a factor of at least two over liquids that had not been exposed to ions. The drying time of a liquid layer was found to increase with the decrease of ion fluxes at the liquid surface. Threshold values of 1.9×10¹¹ positive ions and 2.7×10¹¹ negative ions cm^–2 s^–1 were established below which no increase in the evaporation rates were observed for ethyl alcohol and carbon tetrachloride. The evaporation rate of water at these same ion fluxes was significantly higher than that of the control. The present experiments indicate that a stream of air ions could play a major role in the observed enhancement of evaporation rates.     

Physical effects of negative air ions in a wet sauna

 The physical effects of negative air ions on humans were determined in an experimental sauna room equipped with an ionizer. Thirteen healthy persons took a wet sauna bath (dry bulb temperature 42° C, relative humidity 100%, 10 min exposure) with or without negative air ions. The subjects were not told when they were being exposed to negative air ions. There were no differences in the moods of these persons or changes in their blood pressures between the two saunas. The surface temperatures of the foreheads, hands, and legs in the sauna with negative ions were significantly higher than those in the sauna without ions. The pulse rates and sweat produced in the sauna with ions were singificantly higher than those in the sauna without ions. The results suggest that negative ions may amplify the effects on humans of the sauna. Received: 31 March 1995 / Revised: 25 July 1995 / Accepted: 26 July 1996     

空气负离子浓度分布的影响因素研究综述

近年来随着生态旅游的日益兴起,空气负离子作为一种生态保健旅游资源越来越受到人们的关注。研究空气负离子浓度分布规律可以指导人们在合适的地点、合适的时间充分利用自然状态下产生的空气负离子调养身心。通过查阅国内近十多年有关空气负离子的文献资料,对空气负离子浓度分布规律及其影响因素的有关研究进展进行了综述。现有的研究表明,空气负离子浓度变化及其分布主要受到气象、时空、植物和水体等因素的影响。今后,应加强空气负离子的产生机制及其生态学效应等方面的研究,以便更好地为空气负离子资源的合理开发和生态环境保护提供理论依据。     

The effects of negative air ions on various physiological functions during work in a hot environment

The effects of negative air-ions on human physical performance has been investigated. Twenty-one healthy males, 20–25 years old (X=23.6±2.6) were exposed to two 180-min rest and exercise sessions two weeks apart. The subjects were randomly assigned into either an experimental group (n=12) or to a control group (n=9). The experimental group performed the first session in neutral air conditions and the second one in air containing 1.36 to 1.90×10⁵ negative air ions and 1.40 to 1.66×10² positive air ions/ml. The control group performed both sessions under neutral air conditions. All sessions were held at T_a=40±1C and 25±5% RH. Each session included one hour of resting under the respective ionization conditions, followed by 3 30-min cycle ergometer work bouts, separated by 7-min rest periods. The mechanical work-load during the bicycle exercise was 1.64±0.6 W/kg BW. The experimental group showed a significant reduction with negative air-ions in heart rate (HR), in rectal temperature, and in the rating of perceived exertion (RPE), all when compared with their own neutral session. The control group showed no significant changes between the first and the second exposure. Although not statistically significant, being exposed to negative air-ions seems also to reduce total sweat rate and minute ventilation (V_E), and to increase O₂ pulse. It is suggested that under the conditions of this study negative air ions canimprove various cardiovascular and thermoregulatory functions as well as subjective feelings during physical effort. It is felt that such positive influences may be augmented by increasing the exposure time to negative ionized air and/or prolonging the stressful conditions.With the technical assistance of M. Sheinovitz.     

Electroculture of tomato plants in a commercial hydroponics greenhouse

An experiment was conducted to evaluate the effects of air ion treatment on tomato plants (Lycopersicon esculentum P. Miller) in terms of: (1) growth and health; (2) fruit yield and quality; and (3) economic factors. The plants were grown by a commercial greenhouse (G.H.) grower employing soilless culture techniques. An air ion generator and emitters were installed in such fashion that 864 plants were exposed to a high negative air ion density flux, while 576 plants grew in an area which received relatively few ions. Normal operational procedures, with certain modifications, were employed for plant culture, feed/irrigation, and environmental control. Plants responded vigouously to air ion stimulation, which equated to shortening of the seeding-to-harvest time period by two weeks as measured by vine growth, main stem height, time to blossoming, fruit set, and fruit yield. Throughout the first four-month growth period plant growth was good and no serious physiological disorders nor insect damage were observed. During the sixth harvest week a virus infection appeared in both control and ion-treated plants, but was not of sufficient severity to ruin the experimnent. Foliage and fruit samples were subjected to laboratory analyses. In general, the stimulated plants contained higher percentages of mineral elements than those of the controls. Fruit from ion-treated plants has more ascorbic and citric acid than that from control plants. Although there were no wide differences in fruit texture or flavor, a taste panel verdict indicated that fruit from the stimulated plants tasted better. An unexpected benefit was marked decrease in white fly infestation. All these factors combined with the low cost of air-ion treatment suggest that this modality offers potential for greenhouse cultivation of garden crops.     

Generation of negative air ions by wheat seedlings in a high voltage electrization of soil

It was shown that plantlets of wheat (Triticum vulgare) are capable of generating negative aeroions during the electrization of soil by high-voltage impulses. Soil electrization was carried out either from the moment of planting of seeds or from the appearance of the first seedlings. The concentration of negative ions was measured in the air at a distance of 50 cm from plants. In both variants, similar growth-related changes in the concentration of negative ions were observed. The generation of negative ions began on day 6 after the planting of seeds and reached a concentration of 380 x 10(3) ion/cm3. During the next three days, this level remained unchanged. On day 10, the generation of negative aeroions increased abruptly; on days 10-14, it was twofold as high as on days 7-9. The level of generation of negative aeroions by plants stimulated from the moment of appearance of plantlets was 5-8% higher than by plants stimulated from the moment of planting. The intensity of generation of negative aeroions upon additional illumination and in full darkness remained unchanged.     

Absence of harmful effects of protracted negative air ionisation

The absence of harmful effects of protracted negative air ionisation was studied in 5 weather-sensitive women and 5 normal men chosen at random. Negative ions were generated by the Modulion of Amcor-Amron (Herzliya, Israel). The patients were exposed separately during 8 sleeping hours and 8 working hours to the apparatus at 1–2 m distance in a 4 × 4 m room, for 2 months. Thus they were exposed to a daily uptake of 1 × 10⁴ negative ions/cm³ for 16 h/day during 2 months. Urinary 17-KS, 17-OH, adrenaline and noradrenaline excretion was not affected by the negative ionisation. However serotonin, 5-HIAA, histamine and thyroxine excretion — if increased before — diminished by 50% on an average. There were no changes in body weight, blood pressure, pulse, respiratory rate, oral morning temperature, dynamometer grip strength, routine liver function tests, urinary pH, albumen, glucose, ketones, bilirubin, or occult blood, red and white blood count and ECG records. The EEG revealed the typical changes due to negative air ionisation: stabilising of frequency, increased amplitudes, spreading of brainwaves from the perceptive occipital area to the conceptive frontal area and synchronisation of both hemisphere tracings.     

Effects of atmospheric small negative ions on the oxygen consumption of mouse liver cells

The effects of small negative air ions on the oxygen uptake of isolated mouse liver cells were studied by exposing the liver cells to varying ion concentrations. For concentrations of the order of 1–2 × 10⁵ ions/cm³, the oxygen uptake was always higher than in the normal atmospheric conditions of 3–8 × 10²/ions/cm³. For intermediate concentrations varying effects of activation and inhibition were observed. A statistical analysis showed that the oxygen uptake increased by approximately 14% when liver cells were exposed to ion concentrations of values 1–9 times the normal, by approximately 9% when exposed to 10–99 times the normal, and by approximately 38% when exposed to 100–999 times the normal. The significance and possible implications of the results are discussed.     

Influence of artificial air ionization on the electroencephalogram of the awake rat

Rats exposed during three weeks to high concentrations of positive air ions (80,000 ions/ml) exhibit signs of lowered brain arousal. Amplitude of electrocorticograms recorded with fronto-frontal and occipito-occipital derivations increases. Amplitude of theta hippocampic rhythm increases as the frequency decreases. Power spectrum analysis of theta hippocampic rhythm shows that the low frequency band (5.6 Hz) is the most enhanced one.Similar exposure to negative air ions induces modifications that are not so important. The frequency of theta hippocampic rhythm is, however, significantly increased. A slight increase in vigilance level is probable.These different effects of air ion polarity on vigilance level could explain some effects of air ions upon acquisition task.     

The influence of small atmospheric ions on human well-being and mental performance

Two experimental series were carried out to investigate a possible influence of small atmospheric ions on human beings under well-controlled conditions. In Experiment I, six female subjects were individually exposed in a climatic chamber to high concentrations of positive atmospheric ions, negative atmospheric ions and no ions. Physiological measurements were made, mental performances were tested and subjective votings were recorded. No significant effects of positive or negative atmospheric ions were found. — in Experiment II, 12 male and female subjects were selected out of 125 persons, all tested individually for feeling of discomfort when exposed to positive air ions in short selection experiments. These subjects were exposed twice to the same three ion conditions as in Experiment I. For the selected subjects no significant influence of the ions was found.Presented at the Second Colloquim Bioklimatische Wirkungen luftelektrischer und elektromagnetischer Faktoren, Technische Universität, Munich 16–18 September 1976.     

The response of sweet corn to HF and SO2 under field conditions

“Marcorss” sweet corn plants grown in field plots were exposed continuously in open-top chambers for 32 days to ambient air, charcoal-filtered air or charcoal-filtered air containing HF (ca. 0.5 μgF m⁻³), SO₂ (ca. 235 μg m⁻³), or the two pollutants combined. Elliptical chlorotic leasions appeared after 23 days on leaves of plants exposed to SO₂/HF, and shortly thereafter on plants exposed to all other treatments. At harvest, the number of plants with lesions was significantly greater in chambers supplied with SO₂/HF than in chambers with SO₂, HF, or filtered air.

The different treatments had no effect on fresh or dry weights of leaves, husks, or tassels, height of plants, or number of kernels per ear. Exposure to SO₂/HF reduced the fresh and dry weights of stalks. There were fewer mature ears in the SO₂/HF and unfiltered air treatments than in the others. The reduction in yield from SO₂/HF was about the same as that ascribed to ambient photochemical oxidants in the unfiltered air treatment.

HF combined with SO₂ had no effect on accumulation of S as compared with SO₂ alone, but there was a striking reduction in accumulation of foliar F in plants exposed to SO₂/HF as compared with HF alone.     

The effects of air ions on brain levels of serotonin in mice

Mice were maintained in a controlled pollutant-free microenvironment and were exposed for 12, 24, 48 and 72 hr to 3 different concentrations of small positive or negative air ions: 2–4 × 10³ ions/cm³, 3–4 × 10⁴ ions/cm³ or 3.5–5 × 10⁵ ions/cm³. Spectrophotofluorometric assays of brain serotonin levels of air ion-treated mice showed statistically significant differences as early as 12 hours from those of mice kept in untreated pollutant-free air. Essentially no deviation from control values were observed at 24 and 48 hours. After 72 hours of exposure sharp decreases took place in all groups with the single exception of the animals exposed to 3–4 × 10⁴ positive ions/cm³. The hypothesis that alterations in mood and affect associated with certain meteorological conditions, e.g. winds such as the foehn, sirocco, etc. might depend upon air ion-induced changes in brain levels of serotonin was examined in the light of recent advances in neurophysiology and neuropharmacology.     

Water vapour fluxes and their impact under elevated CO2 in a C4-tallgrass prairie

We measured leaf-level stomatal conductance, xylem pressure potential, and stomate number and size as well as whole plant sap flow and canopy-level water vapour fluxes in a C4-tallgrass prairie in Kansas exposed to ambient and elevated CO₂. Stomatal conductance was reduced by as much as 50% under elevated CO₂ compared to ambient. In addition, there was a reduction in stomate number of the C4 grass, Andropogon gerardii Vitman, and the C3 dicot herb, Salvia pitcheri Torr., under elevated CO₂ compared to ambient. The result was an improved water status for plants exposed to elevated CO₂ which was reflected by a less negative xylem pressure potential compared to plants exposed to ambient CO₂. Sap flow rates were 20 to 30% lower for plants exposed to elevated CO₂ than for those exposed to ambient CO₂. At the canopy level, evapotranspiration was reduced by 22% under elevated CO₂. The reduced water use by the plant canopy under elevated CO₂ extended the photosynthetically-active period when water became limiting in the ecosystem. The result was an increased above- and belowground biomass production in years when water stress was frequent.     

The effect of exposure to negative air ions on the recovery of physiological responses after moderate endurance exercise

 This study examined the effects of negative air ion exposure on the human cardiovascular and endocrine systems during rest and during the recovery period following moderate endurance exercise. Ten healthy adult men were studied in the presence (8,000–10,000 cm⁻³) or absence (200–400 cm⁻³) of negative air ions (25° C, 50% humidity) after 1 h of exercise. The level of exercise was adjusted to represent a 50–60% load compared with the subjects’ maximal oxygen uptake, which was determined using a bicycle ergometer in an unmodified environment (22–23° C, 30–35% humidity, 200–400 negative air ions·cm⁻³). The diastolic blood pressure (DBP) values during the recovery period were significantly lower in the presence of negative ions than in their absence. The plasma levels of serotonin (5-HT) and dopamine (DA) were significantly lower in the presence of negative ions than in their absence. These results demonstrated that exposure to negative air ions produced a slow recovery of DBP and decreases in the levels of 5-HT and DA in the recovery period after moderate endurance exercise. 5-HT is thought to have contributed to the slow recovery of DBP. Received: 29 July 1996 / Revised: 3 April 1997 / Accepted: 28 October 1997     

Ozone effects on high light-induced photoinhibition in Phaseolus vulgaris

In this study the response to photoinhibition of photosynthesis and subsequent recovery was examined in plants of Phaseolus vulgaris L. cultivar ‘Pinto’ exposed to charcoal-filtered air or to ozone (O₃) at 150 nL L⁻¹ either for 3 h, or for 5 h. The responses were analysed using chlorophyll fluorescence imaging and by conventional fluorometry. Compared to control plants maintained in charcoal-filtered air, in plants exposed for 3 h to O₃ and then subjected to high light treatment, the results show an increased tolerance to photoinhibition. Plants exposed to the same O₃ concentration but for the longer 5-h period, were not tolerant to the photoinhibition treatment and, instead showed visible symptoms of damage (chlorosis and necrosis) clearly attributable to the longer O₃ exposure. Here the detrimental effects of O₃ aggravated the effects of the high light photoinhibitory treatment. The leaves exposed to the shorter O₃ treatment (150 nL L⁻¹ for 3 h) developed an ability to counteract the negative effects of a high light exposure probably because the O₃ had activated an antioxidant system able to protect the photosynthetic machinery.     

Electrohydrodynamic mortality of insects: a plausible mechanism

 An electrohydrodynamic (EHD) system with a point-to-plane electrode, which produced air ions within a strong electric field, was used to study mortalities of pupae, larvae, and adults of Tribolium confusum (TC) and larvae of Plodia interpunctella (PI). The treatments included a neutral air stream, negative ions, positive ions, and the air stream superimposed with ions of either polarity. The negative ions caused the maximum mortality in TC pupae and PI larvae whereas the TC adults were least affected, but the negative ion flux was higher than the positive one at the constant high voltage of the power supply used in the present experiments. The differences in the mean mortalities of the treatment groups were highly significant (P<0.0001). Mortality was primarily attributed to the body fluid losses caused by the electric wind of the EHD system. Mortality and weight loss relationships were linear with negative slopes (r ²=0.52, and r ²=0.98 for TC and PI, respectively). The superimposition of the air stream with either positive or negative ion fluxes increased the survival fractions compared with those of the ion fluxes alone. Received: 27 May 1996 / Accepted: 9 September 1996