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471.
Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops, and therefore results in an increase in crop yield. However, little is known about the combined effect of elevated CO2 and N species on plant growth and development. Two growth-chamber experiments were conducted to determine the effects of NH4^+/NO3^- ratio and elevated CO2 concentration on the physiological development and water use of tomato seedlings. Tomato was grown for 45 d in containers with nutrient solutions varying in NH4^+/NO3^- ratios and CO2 concentrations in growth chambers. Results showed that plant height, stem thickness, total dry weight, dry weight of the leaves, stems and roots, G value (total plant dry weight/seedling days), chlorophyll content, photosynthetic rate, leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were increased with increasing proportion of NO3- in nutrient solutions in the elevated CO2 treatment. Plant biomass, plant height, stem thickness and photosynthetic rate were 67%, 22%, 24% and 55% higher at elevated CO2 concentration than at ambient CO2 concentration, depending on the values of NH4^+/NO3^- ratio. These results indicated that elevating CO2 concentration did not mitigate the adverse effects of 100% NH4^+-N (in nutrient solution) on the tomato seedlings. At both CO2 levels, NH4^+/NO3^- ratios of nutrient solutions strongly influenced almost every measure of plant performance, and nitrate-fed plants attained a greater biomass production, as compared to ammonium-fed plants. These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings. 相似文献
472.
473.
研究了高压汞灯光源下己唑醇在不同pH缓冲液中的光化学降解特性及NO3-和NO2-对光解的影响.结果表明,己唑醇在水溶液中的光解符合一级动力学规律.不同pH值缓冲溶液中的光解速率排序为:pH=7>pH=9>pH=5.在己唑醇水溶液中添加不同浓度的NO3-及NO2-,均会不同程度地影响己唑醇的光解速率.在0~20mg·L-1的浓度范围内,NO3-对己唑醇的光解均表现为促进作用,且随着添加浓度的增大促进作用增强;NO2-在0.4和2mg·L-1浓度下,对己唑醇的光解有一定的促进作用,而在10~20mg·L-1浓度时,表现为抑制作用. 相似文献
474.
475.
In this investigation, the adsorption measure of linezolid antibiotic onto MgO nanoparticles and ZnO–MgO nanocomposites were performed. The adsorbents were characterized by different techniques such as XRD, SEM, TEM and BET. The parameters influence such as the pH, adsorbent dosage and temperature was tested and evaluated by Box–Behnken Design combined with response surface methodology. Performing adsorption tests at optimal conditions set as 0.5 g L−1 of adsorbent, pH 10 and 308 K make admit to obtain high adsorption turnover (123.45 and 140.28 mg g−1 for MgO nanoparticles and ZnO–MgO nanocomposites, respectively). A good compromise between predicted and experimental data in this research was observed. The experimental equilibrium data fitting to Langmuir, Freundlich, Tempkin and Dubinin–Radushkevich models indicate that the Langmuir model is a best model for evaluation of adsorption behavior. Kinetic evaluation of experimental data indicated that the adsorption operations followed well pseudo-second-order models. The adsorption capacity of ZnO–MgO nanocomposites is higher than MgO nanoparticles that because of the ZnO–MgO nanocomposites have high specific surface area. 相似文献
476.
通过对贵州省电解锰行业生产废水循环模式的调查,针对水质、水量特征进行改造:电解锰生产冷却循环水的强制排污水可降级作为电解产品和阴极板的冲洗水使用,处理后的含铬锰废水可作为制液氨水和电解清槽用水。进行以上优化后,电解锰生产废水闭路循环是可以实现的。 相似文献
477.
本文根据酵母废液的水质特点,采用了常温升流式厌氧污泥床处理工艺,即温度在26.8-28.0℃,进水COD为7129-9823mg·l^-1时,达到CDO去除率66.0-71.0%,同时,沼气产率为2.4-3.0L·l^-1·d^-1,沼气中烷含量为61.5-69.1%。该法耗能小,沼气可回收,经济效果明显。 相似文献
478.
Many numerical computer codes used to simulate multi-species reactive transport and biodegradation have been developed in recent years. Such numerical codes must be validated by comparison of the numerical solutions with an analytical solution. In this paper, a method for deriving analytical solutions of the partial differential equations describing multiple species multi-dimensional transport with first-order sequential reactions is presented. Although others have developed specific solutions of multi-species transport equations, here a more general analytical approach, capable of describing any number of reactive species in multiple dimensions is derived. A substitution method is used to transform the multi-species reactive transport problem to one that can be solved using previously published single-species solutions for various initial and boundary conditions. One- and three-dimensional examples are presented to illustrate the steps involved in extending single-species solutions to a four-species system with sequential first-order reactions. 相似文献
479.
Gibbsite calcined at 400°C (GB400) was prepared, and its ability to adsorb rhodium(III) was investigated. Optimal pH, effect of contact time, temperature, adsorption isotherms, and recovery percentage were evaluated. The optimal pH was 6.3. The adsorption equilibrium was achieved within 24 h. The adsorption rate was found to be of pseudo-first order. The experimental data were fitted to both the Freundlich (r = 0.90–0.93) and Langmuir (r = 0.94–0.96) equations. The amount of rhodium(III) adsorbed decreased with increasing temperature. Rhodium(III) being adsorbed from phosphate or sulfate plating solution was recovered using hydrochloric acid and sodium hydroxide solutions at 1, 10, and 100 mmol L?1. 相似文献
480.