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911.
植物物候对气候变化非常敏感,可作为环境变化对植物生理活动影响的指示。植物物候的变化不仅可反映和预测全球环境的变化,还对地球物质循环和能量流动过程有着重要的影响。因此,结合植物生长背景,全面分析植物物候影响因素,探究植物物候对气候变化的响应是十分必要的。本文基于不同的气候类型下植物物候的研究,介绍了不同气候类型本身存在的气象、地域差异,总结不同气候类型下植物物候地域性特征;总结了热带亚热带气候、温带气候、寒带气候、高原山地气候4大类气候类型下植物物候变化及影响因素;讨论了当前物候研究的主要问题,并对未来研究进行了展望。综述表明,植物物候响应随气候类型呈现出不一致性,不同气候类型下影响植物物候的关键因素也不同。植物物候研究需结合植物生长环境,综合讨论相关影响因素。 相似文献
912.
Effects of environmental factors on N2O emission from and CH4 uptake by the typical grasslands in the Inner Mongolia 总被引:8,自引:0,他引:8
The fluxes of N2O emission from and CH4 uptake by the typical semi-arid grasslands in the Inner Mongolia, China were measured in 1998-1999. Three steppes, i.e. the ungrazed Leymus chinensis (LC), the moderately grazed Leymus chinensis (LC) and the ungrazed Stipa grandis (SG), were investigated, at a measurement frequency of once per week in the growing seasons and once per month in the non-growing seasons of the LC steppes. In addition, four diurnal-cycles of the growing seasons of the LC steppes, each in an individual stage of grass growth, were measured. The investigated steppes play a role of source for the atmospheric N2O and sink for the atmospheric CH4, with a N2O emission flux of 0.06-0.21 kg N ha(-1) yr(-1) and a CH4 uptake flux of 1.8-2.3 kg C ha(-1) yr(-1). Soil moisture primarily and positively regulates the spatial and seasonal variability of N2O emission. The usual difference in soil moisture among various semi-arid steppes does not lead to significantly different CH4 uptake intensities. Soil moisture, however, negatively regulates the seasonal variability in CH4 uptake. Soil temperature of the most top layer might be the primary driving factor for CH4 uptake when soil moisture is relatively low. The annual net emission of N2O and CH4 from the ungrazed LC steppe, the moderately grazed LC steppe and the ungrazed SG steppe is at a CO2 equivalent rate of 7.7, 0.8 and -7.5 kg CO2-C ha(-1) yr(-1), respectively, which is at an ignorable level. This implies that the role of the semi-arid grasslands in the atmospheric greenhouse effect in terms of net emission of greenhouse gases (CO2, CH4 and N2O) may exclusively depend upon the net exchange of net ecosystem CO2 exchange. 相似文献
913.
不同栽培模式下耕层土壤盐分演变规律研究 总被引:1,自引:0,他引:1
通过定位试验对有机栽培、无公害栽培和常规栽培模式下土壤盐分动态进行了研究。结果表明,有机栽培和无公害栽培模式中土壤盐分差异不显著,常规与无公害栽培模式中土壤盐分差异显著(F0.05=9.04),常规与有机栽培模式下的土壤盐分差异也极显著(F0.01=9.37)。常规栽培与无公害栽培环境中,全年土壤全盐量变化表现为两个积盐期:春季和秋季,以春季积盐最明显;有机栽培环境中,从7月份即出现了积盐过程,并且土壤全盐量变化趋势与气温变化基本一致。 相似文献
914.
A fungal strain capable of utilizing metsulfuron-methyl as sole carbon and energy sources was isolated from a metsulfuron-methyl treated soil. The degradation characteristics of metsulfuron-methyl by this fungal strain were investigated in liquid culture and soil. More than 79% of metsulfuron-methyl at concentrations of 0.10 mgl(-1), 1.0 mgl(-1) and 10.0 mgl(-1) in pure culture was degraded by strain MD after incubation for 7 days, whereas only 5.6%, 8.6% and 13.1% of metsulfuron-methyl were degraded at levels of 0.10 mgl(-1), 1.0mgl(-1) and 10.0 mgl(-1) in the controls, respectively. The incorporation of strain MD into soil was found to substantially increase the degradation of metsulfuron-methyl. Degradation was 7.5 and 3.8 times faster in strain MD amended soils than in sterilized and fresh soils. The results show that addition of the isolated strain MD enhances degradation of metsulfuron-methyl in water and soil. 相似文献
915.
A significant problem with UV disinfection of wastewater is the accumulation of fouling materials at sleeve-water interfaces. It has been shown that automated chemical and/or mechanical cleaning can remove most fouling materials satisfactorily. However, permanent foulants, which cannot be removed completely by typical cleaning operations, always remain on the quartz sleeves. These permanent foulants reduce UV transmittance, in turn reducing disinfecting effectiveness. This research investigated the origins, formation, and composition of permanent fouling. Four instrumental analyses were used: atomic force microscope (AFM), X-ray fluorescence (XRF), scanning electron microscope combined with energy dispersive X-ray microanalysis (SEM/EDX), and sleeve UV transmittance (SUVT). It appeared that permanent foulants were trapped initially by microscale holes and peaks on fresh sleeve surfaces. Based on the topography and roughness measurements from the AFM, after long-term regular chemical and mechanical cleaning, the wipers of cleaning systems damage sleeve surfaces, creating scratches or holes with larger surface areas. Foulants are trapped more easily, and are attached tightly to the surfaces of these scratches or to each other. The results from XRF and SEM/EDX showed that the main fouling components were aluminum, iron, magnesium, calcium, and phosphorus. These could not be related to wastewater quality. For the specific cases studied, chemical plus mechanical cleaning is more effective in removing foulants and avoiding the accumulation of permanent foulants than mechanical cleaning alone; in most cases, SUVT was higher than 90% after chemical plus mechanical cleaning, whereas mechanical cleaning alone achieved only approximately 30% SUVT after long-term usage. 相似文献
916.
烟气脱硫石膏及其建材资源化研究 总被引:17,自引:0,他引:17
介绍了作者在烟气脱硫石膏及其作为主要原料制备建筑石膏、粉刷石膏、石膏砌块(条板)、纸面石膏板、腻子、水泥缓凝剂、二水石膏胶结材等建材资源化方面的研究结果。结果表明,烟气脱硫石膏的品位较高,便于利用,是建材工业的宝贵资源,应进一步加大研究开发力度。 相似文献
917.
918.
919.
将冷阱用于液样浓缩器(LSC)/色谱/质谱(GC/MS)装置中,可对饮用水中挥发性有机污染物进行快速定性、定量分析.此方法适用于对饮用水及天然水体中挥发性有机污染物的普查和监测. 相似文献
920.
采用污泥活性炭(SAC)、TiO2/SAC、Fe3O4/SAC作为敏化剂,结合微波处理技术对污泥进行了预处理,通过分析滤液中COD、DNA、氮、磷、有机物的含量及组分,探索微波+敏化剂的最佳处理条件.SAC负载TiO2和Fe3O4后强化了其对电磁波的介电损耗和磁滞损耗,tan δε分别增加了1.8和1.3倍,tan δμ分别增加到0.26和0.67.TiO2/SAC投加量为0.25g/gSS时,样品滤液的COD浓度是1900mg/L,是原污泥和单独微波处理的4.52倍和1.86倍;Fe3O4/SAC投加量为0.35g/gSS时,样品滤液的COD浓度是2540mg/L,是原污泥和单独微波处理的6.05倍和2.45倍,Fe3O4/SAC强化污泥破壁效果更好.此时,样品滤液中TN、TP、蛋白质、多糖浓度分别为原污泥的7.7倍、16倍、7.49倍和71.69倍,微生物胞内和胞外聚合物中的物质大量释放,滤液中的溶解性有机物大大增加.微波+敏化剂的预处理方法有利于对污泥中氮、磷及有机物进行资源化利用与回收. 相似文献