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Using open top chambers, the effects of elevated O₃ (80 nmol mol⁻¹) and elevated CO₂ (700 µmol mol⁻¹), alone and in combination, were studied on young trees of Quercus mongolica. The results showed that elevated O₃ increased malondialdehyde content and decreased photosynthetic rate after 45 days of exposure, and prolonged exposure (105 days) induced significant increase in electrolyte leakage and reduction of chlorophyll content. All these changes were alleviated by elevated CO₂, indicating that oxidative stress on cell membrane and photosynthesis was ameliorated. After 45 days of exposure, elevated O₃ stimulated activities of superoxide dismutase (SOD, EC 1.15.1.1) and ascorbate peroxidase (APX, EC 1.11.1.11), but the stimulation was dampened under elevated CO₂ exposure. Furthermore, ascorbate (AsA) and total phenolics contents were not higher in the combined gas treatment than those in elevated O₃ treatment. It indicates that the protective effect of elevated CO₂ against O₃ stress was achieved hardly by enhancing ROS scavenging ability after 45 days of exposure. After 105 days of exposure, elevated O₃ significantly decreased activities of SOD, catalase (CAT, EC 1.11.1.6) and APX and AsA content. Elevated CO₂ suppressed the O₃-induced decrease, which could ameliorate the oxidative stress in some extent. In addition, elevated CO₂ increased total phenolics content in the leaves both under ambient O₃ and elevated O₃ exposure, which might contribute to the protection against O₃-induced oxidative stress as well.
The effect of different solvents on extraction with liquid carbon dioxide was studied. Extracted polynuclear aromatic hydrocarbons (PAHs) were applied on Sephadex C-50 gel. The model PAHs were phenanthrene, pyrene and benzo(a)pyrene. It is stated that the percentage of PAH model extractions was diminished when water-immiscible solvents (cyclohexane, chloroform and benzene) and methanol were added to the system. The addition of acetone and dimethylformamide caused increases in extraction percentage. The optimum content of both these solvents was shown to be approximately 0.8% in relation to the volume of C02 used .Under these conditions, a single extraction in the presence of acetone made it possible to recover 67% of phenanthrene, 62% of pyrene and 86% of benzo(a)pyrene, whereas in the presence of dimethylformamide these numbers were 66%, 80% and 9%, respectively.
Evidence of changes in weather parameters like ambient temperature, precipitation, wind flow, etc., are prominently visible across the world. These changes have been reported to effect global crop yield. This review compiles both direct and indirect effects of climate change on global crop productivity with highlights on existing local and global scenarios. As a conclusion, it may be stated that thorough understanding of agricultural techniques and analysis of global change factors is highly essential for achieving sustainable agricultural yield over the upcoming years.
Bee anesthesia has long been widely used in scientific research and for practical purposes. Bee anesthesia is usually induced with carbon dioxide. It is required for such procedures as populating mating hives and cages, introducing queen bees and instrumental insemination. The oxygen to nitrogen ratio may play a very important role in the process of awakening. The aim of the experiment was to investigate the survival rate of worker bees after the application of different concentrations of oxygen and nitrogen in their recovery from anesthesia. The general purpose was to determine the optimal gas mixture for the fastest recovery and the longest survival of bees. The results of this study provide a basis for future experiments on queen bees aimed at accelerating the awakening from anesthesia with carbon dioxide during insemination as well as the initiation of laying eggs. The lowest bee mortality in the first days after awakening from anesthesia was observed in the group awoken in a mixture of 48.6% O₂ and 51.4% N₂, but the highest average survival rate was noted in the group awoken in 60% O₂ and 40% N₂.
Soil respiration plays a crucial role in global carbon cycling of terrestrial ecosystems. Changes in atmospheric CO₂ and nitrogen (N) addition across the globe are likely to affect soil respiration. However, the effects of elevated CO₂, and N addition on soil respiration are not fully understood especially in wetland ecosystems. To evaluate the effects of atmospheric CO₂ and N availability on soil respiration, a paired, nested manipulative in situ experiment was performed, using CO₂ fumigation within Open-Top Chambers as the primary factor, and N (as NH₄NO₃) as the secondary factor in a temperate wetland in northeastern China in 2010 and 2011. CO₂ fumigation significantly enhanced soil respiration, according to repeated-measures ANOVA, and the stimulatory effect of CO₂ fumigation on soil respiration was sustained during the whole experimental period regardless of N addition. However, the positive soil respiration effect of N addition alone weakened over time. Moreover, there was a significant interaction between CO₂ fumigation and N addition. Soil temperature explained 50–66% of the variation in soil respiration. Moreover, soil respiration was positively correlated with the root N content and litter decomposition rate. The results suggested that elevated CO₂ concentrations will accelerate soil respiration and ecosystem carbon cycling, thus, limiting soil carbon sequestration, especially when coupled with increasing N deposition.
Soil respiration is a very important factor influencing carbon deposition in peat and reflecting the intensity of soil organic matter decomposition, root respiration, and the ease of transporting gases to the surface. Carbon dioxide release from three different peat soil profiles (0-80 cm) of the Polesie Lubelskie Region (Eastern Poland) was analyzed under laboratory conditions. Peat samples were incubated at 5, 10, and 20°C in aerobic and anaerobic environments, and their CO2-evolution was analyzed up to 14 days. The respiration activity was found to be in the range of 0.013-0.497 g CO2 kg-1 DW d-1. The respiratory quotient was estimated to be in the range of 0.51-1.51, and the difference in respiration rates over 10°C ranged between 4.15 and 8.72 in aerobic and from 1.15 to 6.53 in anaerobic conditions. A strong influence of temperature, depth, the degree of peat decomposition, pH, and nitrate content on respiration activity was found. Lack of oxygen at low temperature caused higher respiration activity than under aerobic conditions. These results should be taken into account when the management of Polish peatlands is considered in the context of climate and carbon storage, and physicochemical properties of soil in relation to soil respiration activity are considered.
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