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951.
文章利用大气边界层风速廓线的理论和实验研究结果,重新推导了高斯扩散沉积模式中烟轴高度、地面反射系数及输送因子表达式,从而导出了能描述风速随高度变化的新的高斯扩散沉积模式。 文章还利用数值计算的结果讨论了风速廓线对地面相对浓度的影响。 相似文献
952.
对苏州河截流区外河段(城郊段)东大盈河口—北新泾,按河道形态,支流与城镇分布等因素,沿程采集24个底泥柱样,测定其不同部位不同深度底泥中COD_(Cr)和NH_3-N含量,分析COD_(Cr)和NH_3-N在沿程和垂向上的分布特征及其成因。结果表明,底泥中污染沿程分布呈不规则波状起伏,东大盈河、蕴藻浜、盐铁塘、封浜、华漕港、新槎浦等支流口,浮泥层中COD_(Cr)含量达2万mg/kg,超过背景值2—3倍,支流口下游200m范围内均较高;黄渡小支流口、华漕港支流口浮泥层中NH_3-H含量达250mg/kg,超过背景值3倍。在垂向分布上,底泥柱样都出现峰值分布,在某些弯道及支流口出现递减分布。底泥耗氧污染程度主要与支流及其排污量有关,其次是弯道凸岸处污染物易于沉积富集。这为苏州河市郊段环境综合治理、底泥疏浚和处置提供了科学依据。 相似文献
953.
954.
绿洲节水系统监控与绿洲开发 总被引:3,自引:0,他引:3
本文把绿洲与绿洲节约用水作为复杂的系统处理,提出了绿洲节水系统的组元、变元及结构图示.在对敦煌绿洲节水系统进行个例分析的基础上,论证了监控绿洲节水系统与坚持高效率开发绿洲的基本途径。 相似文献
955.
土地资源系列研究方法的探讨——以新疆呼图壁县绿洲为例 总被引:4,自引:1,他引:4
新疆呼图壁县位于天山中段北麓,准噶尔盆地南缘,总面积9394km2,绿洲面积1131km2,占全县总面积的12%。 相似文献
956.
湘江水体中重金属的化学形态及分布特征的研究 总被引:14,自引:0,他引:14
水体中重金属的生态效应和迁移转化规律与其化学形态密切相关。本文结合湘江重金属水容量与背景值的研究,较系统地研究了铜、铅、镉和锌的化学形态及其在全江段水中的分布特征。应用阳极溶出伏安法,得到湘江水中重金属总量、溶解态含量和悬浮态含量的分配与分布特征,还有溶解态所包含的金属的主要存在形态及与之共存的其它多种形态(包括悬浮态)共十种,该文对其形成、分配和相互转化进行了综合分析。 相似文献
957.
Functional zones in cities constitute the most conspicuous components of newly developed urban areas,and have been a hot spot for domestic and foreign investors in China,which not only show the expanse of urban space accompanied by the shifts both in landscape(from rural to urban)and land use(from less extensive to extensive),but also display the transformation of regional ecological functions.By using the theories and methods of landscape ecology,the structure of landscapes and landscape ecological planning can be analyzed and evaluated for studying the urban functional zones‘layout.In 1990,the Central Govermment of China declared to develop and open up Pudong New Area so as to promote economic development in Shanghai.Benefited from the advantages of Shanghai‘s location and economy,the government of Pudong New Area has successively built up 7 different functional zones over the past decade according to their functions and strategic goals.Based on the multi-spectral satellite imageries taken in 1990,1997and 2000,a landscape ecolgy analysis was carried out for Pudong New Area of Sanghai ,supported by GIS technology.Green space(including croplands )and built-up areas are the major factors considered in developing urban landscape.This paper was mainly concerned with the different spatial patterns and dynamics of green space,built-up areas and new buildings in different functional zones,as influenced by different spatial patterns and dynamics of green space,built-up areas and new buildings in different functional zones,as influenced by different functional layouts and development strategies.The rapid urbanization in Pudong New Area resulted in a more homogeneous landscape.Agricultural landscape and suburban landscape were gradually replaced by urban landscape as the degree of urbanization increased.As a consequence of urbanization in Pudong,not only built-up patches,but also newly-built patches and green patches merged into one large patch,which should be attributed to the construction policy of extensive green space as the urban development process in Pudong New Area.The shape of green area of 7 functional zones became more and more regular because of the horticultural needs in Shanghai urban planning.Some suggestions were finally made for the study of future urban planning and layout. 相似文献
958.
Mei Li Yao Zhang Chenglei Pei Jinwen Zhang Chunlei Cheng Xiufeng Lian Mubai Chen Bo Huang Zhong Fu Zhen Zhou 《环境科学学报(英文版)》2023,35(2):806-822
The real-time detection of the mixing states of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs in ambient particles is of great significance for analyzing the source, aging process, and health effects of PAHs and nitro-PAHs; yet there is still few effective technology to achieve this type of detection. In this study, 11 types of PAH and nitro-PAH standard samples were analyzed using a high performance-single particle aerosol mass spectrometer (HP-SPAMS) in lab studies. The identification principles ‘parent ions’ and ‘mass-to-charge (m/z) = 77’ of each compound were obtained in this study. It was found that different laser energies did not affect the identification of the parent ions. The comparative experiments of ambient atmospheric particles, cooking and biomass burning emitted particles with and without the addition of PAHs were conducted and ruled out the interferences from primary and secondary organics on the identification of PAHs. Besides, the reliability of the characteristic ions extraction method was evaluated through the comparative study of similarity algorithm and deep learning algorithm. In addition, the real PAH-containing particles from vehicle exhaust emissions and ambient particles were also analyzed. This study improves the ability of single particle mass spectrometry technology to detect PAHs and nitro-PAHs, and HP-SPAMS was superior to SPAMS for detecting single particles containing PAHs and nitro-PAHs. This study provides support for subsequent ambient observations to identify the characteristic spectrum of single particles containing PAHs and nitro-PAHs. 相似文献
959.
合肥台CTS-1分析系统网络组建 总被引:1,自引:0,他引:1
本文阐述了利用UNIX和WIN98/2000互联的局域网技术,对CTS-1系统进行优化配置,组建CTS-1网络分析系统,实现CTS-1系统数据共享,提高地震分析的效率,确保数据备份。利用代理软件用一个MODEM让各个子机同时上网,同时充分利用台站现有的计算机设备,最大限度的实现地震监控、速报、分析以及地震研究的同时开展。 相似文献
960.
Chen WH 《Journal of the Air & Waste Management Association (1995)》2003,53(2):136-142
An experimental investigation on waste combustion characteristics of a mass burn incinerator is conducted in this study. Three different charging modes, including operator manipulation, periodic feeding, and temperature control, are taken into consideration. The results indicate that the burning characteristics in the combustion chambers are closely related to the operating modes. For the operator manipulation where the wastes are sent into the incinerator in two short periods, the entire temperature distribution of the primary combustion chamber can be partitioned into two parts, thereby yielding waste group combustion. Temperature oscillations in both the primary and secondary combustion chambers are characterized for the periodic feeding. However, because of the shorter charging period and smaller amount of waste, the burning interaction between the two chambers is initially weak and becomes notable in the final stage. When temperature control is performed, the burning oscillation of the primary combustion chamber is further amplified so the combustion interaction is drastic. These exhibitions are mainly caused by the competition between endothermic and exothermic reactions. The instantaneous heat exchange efficiency of the cyclone heat recovery system (CHRS) installed in the incineration system is also evaluated to obtain details of energy recovery behaviors. As a result, the efficiency tends to decrease linearly with increasing temperature of hot flue gas. This arises from the fact that heat loss from the gas to the environment is increased when the temperature of the former is higher, even though the temperature gradient across the cyclone is enlarged. 相似文献