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701.
The underlying mechanisms of interaction between the symbiotic nitrogen-fixation process and main physiological processes, such as assimilation, nutrient allocation, and structural growth, as well as effects of nitrogen fixation on plant responses to global change, are important and still open to more investigation. Appropriate models have not been adequately developed. A dynamic ecophysiological model was developed in this study for a legume plant [Glycine max (L.) Merr.] growing in northern China. The model synthesized symbiotic nitrogen fixation and the main physiological processes under variable atmospheric CO2 concentration and climatic conditions, and emphasized the interactive effects of these processes on seasonal biomass dynamics of the plant. Experimental measurements of ecophysiological quantities obtained in a CO2 enrichment experiment on soybean plants, were used to parameterize and validate the model. The results indicated that the model simulated the experiments with reasonable accuracy. The R2 values between simulations and observations are 0.94, 0.95, and 0.86 for total biomass, green biomass, and nodule biomass, respectively. The simulations for various combinations of atmospheric CO2 concentration, precipitation, and temperature, with or without nitrogen fixation, showed that increasing atmospheric CO2 concentration, precipitation, and efficiency of nitrogen fixation all have positive effects on biomass accumulation. On the other hand, an increased temperature induced lower rates of biomass accumulation under semi-arid conditions. In general, factors with positive effects on plant growth tended to promote each other in the simulation range, except the relationship between CO2 concentration and climatic factors. Because of the enhanced water use efficiency with a higher CO2 concentration, more significant effects of CO2 concentration were associated with a worse (dryer and warmer in this study) climate. 相似文献
702.
This paper introduces an integrated spatial and temporal modeling system developed mathematically for assessing microbial contaminants on animal-grazed farmlands. The model uses fecal coliform, specifically Escherichia coli, as an indicator of fecal contamination and describes the sources, sinks, transport processes, and fate of E. coli contaminants in catchments and associated streams. Spatial features include grazing location, land topography, distance to a nearby stream, and distance through the stream network to the outlet. Temporal features are population dynamics on the land surface, in flow, and on streambeds. The model applies the principles of conservation of mass balance on two different types of pools: grid cells on land surfaces and networked stream segments. The model aims to improve the prediction of the effects of different land management strategies on the fecal contamination of waterways. This is achieved by characterizing the movement of fecal contaminants from land to streams and in-stream mobilization. Processes of attenuation, diffusion, and transport govern the movement. Our study site is a hill land catchment with an area of 140 ha and is used exclusively for animal grazing. The model was calibrated with previous research results, and then tested using the data collected at the outlet of the catchment. The sensitivity of the model predictions was analyzed for different scenarios: effect of stock rate, attenuation rate, and flow volumes. The similar pattern between monitored and predicted E. coli concentration proved that the model captures the key features that control the population dynamics of fecal contaminants. Further experiments are required to expand the model's functionality for covering more mitigation options. 相似文献
703.
Cadmium(II) removal from aqueous solutions by pre-treated biomass of marine alga Padina sp 总被引:1,自引:0,他引:1
In this study, the adsorption properties of a pre-treated biomass from marine alga Padina sp., a biomass collected from Surin Island, Thailand, for removal of cadmium(II) ions from aqueous solutions was investigated. Batch and column experiments were conducted to determine the adsorption properties of the modified biomass. At a pH of 5, the maximum removal capacity of the biomass is 0.53 mmol/g. The kinetics of cadmium(II) adsorption were fast with 90% of adsorption taking place within 35 min. This study demonstrated that the pre-treated biomass of Padina sp. could be used as an efficient biosorbent for the treatment of cadmium(II)-bearing wastewater streams. 相似文献
704.
705.
G. V. Vorobyev A. Yu. Alyabyev T. I. Ogorodnikova A. F. Khamidullin V. N. Vorobyev 《Russian Journal of Ecology》2014,45(2):90-94
Microcalorimetric, gasometric, and nuclear magnetic resonance (NMR) methods have been used to evaluate heat production, gas exchange, and root membrane permeability in dandelion of different morphological forms from populations exposed to different levels of air pollution. The results show that these forms differ in the level of energy metabolism and that the form with a higher metabolic level (T. off. f. dahlstedtii) is more tolerant of air pollution with motor vehicle exhausts. 相似文献
706.
Shinya Inazumi Hiroyasu Ohtsu Yu Otake Makoto Kimura Masashi Kamon 《Journal of Material Cycles and Waste Management》2009,11(1):55-64
An evaluation method that can express the local leakage of leachate from joint sections in steel pipe sheet pile (SPSP) cutoff
walls is discussed in this study. In particular, the evaluation of environmental feasibility (containment of leachates containing
toxic substances) considering a three-dimensional arrangement and hydraulic conductivity distribution of the joint sections
in the SPSP cutoff wall is compared with an evaluation that uses the equivalent hydraulic conductivity. This equivalent hydraulic
conductivity assumes that the joint section and the steel pipe are integrated; therefore, the hydraulic conductivity is substituted
with a uniform permeable layer. However, in an evaluation that employs the equivalent hydraulic conductivity, it is difficult
to consider the local leakage of leachate containing toxic substances from the joint sections in the SPSP cutoff wall. It
was established that evaluations of the environmental feasibility of SPSP cutoff walls with joint sections must take into
account the local leakage of leachates containing toxic substances from the joint sections. Also, it was clarified that technologies
that lower the hydraulic conductivities of joint sections in SPSP cutoff walls and also facilitate the use of sparser joint
arrangements contribute significantly to increasing the environmental feasibility of SPSP cutoff walls at landfill sites. 相似文献
707.
用事故树分析法进行炼厂油罐爆炸事故的环境风险评价 总被引:5,自引:0,他引:5
论述了风险、风险评价、环境风险评价的概念及其主要内容,说明利用事故树分析法进行工程环境风险评价的程序和方法。并运用这种方法对某炼厂油罐爆炸事故进行了大气环境风险评价。 相似文献
708.
Zhang Xuyang Liu Ying Chen Xiaoyang Long Linli Su Yongdong Yu Xiaokun Zhang Hongmei Chen Yongchun An Shikai 《Environmental science and pollution research international》2022,29(40):60117-60132
Environmental Science and Pollution Research - The Huainan mining area is rich in coal resources and has sparse vegetation and many collapsed waterways. Large-scale and long-term underground coal... 相似文献
709.
Russian Journal of Ecology - The aim of this study is to explore the effects of the litter cover thickness and cleaning methods on seed germination and seedling growth of Pinus densata. The overall... 相似文献
710.