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11.
给出了轨道交通车辆横向偏移量的计算方法 ,并应用列车 -线路动力耦合模型 ,分析了广州地铁三号线的安全限界变化问题。确定了当前按 80km/h行车速度设计的建筑限界能满足 13 0km/h行车速度的要求 ,限界尺寸不需改动可保证列车运行安全平稳  相似文献   
12.
通过滇池鲤鱼与松花坝水库和国内外同类鲤鱼的元素含量对比,确认滇池鲤鱼受工业污水的危害影响主要是As、Se。鱼体As、Se含量目前已经超过正常值,Ni、Cr、Cu、Fe、Pb比正常值偏低,其它元素属正常值范围。为了避免过多的元素富集,建议滇池鲤鱼以半年到一年为生长捕捞期为宜。  相似文献   
13.
The alpine musk deer (Moschus chrysogaster) is a key species of some terrestrial ecosystems, it has an important economic and conservative significance as a kind of medical animal in China. Due to the interaction between natural forces and human disturbance, the habitats of alpine musk deer are fragmented and isolated in different mountains and the populations are confronted with many problems of survival. In this paper, we discuss the impact of habitat fragmentation and isolation on alpine musk deer populations based on the investigation on the population densities and sizes and environmental factors in different reserves, as well as on the analysis of its ecological adaptability. We found that the alpine musk deer has strong ecological adaptability; the population development of alpine musk deer may benefit from the reduction of the forest area and even from the fragmentation and isolation of the habitat to a certain extent. However, deforestion should not be encouraged only for the alpine musk deer population, but should also be based on the overall consideration of biodiversity conservation.  相似文献   
14.
农业生产地域分工与农产品专业化生产是使农业从自然经济阶段向以市场为导向的商品农产品生产转变的一个标志。本文在分析该区农业布局现状及其存在问题的基础上,提出了农业总体布局的设想与不同类型地域农业开发的主攻方向与对策,并对市场经济体制下粮食、棉花、猪、禽、水产品等农产品生产基地的地域选择、建设规模与技术措施等进行了探讨。  相似文献   
15.
The effectiveness of inorganic alumino-silicate sorbents (alumina and kaolinite) to adsorb airborne lead and cadmium from the effluent stream of a simulated waste incinerator was studied. A 20 kW (68,000 BTU/h) flow reactor was used to achieve the temperature and residence times typical of a waste incinerator. Solutions containing lead or cadmium were introduced yielding airborne metals concentrations between 15 and 150 ppm. Gas samples were drawn into a particle impactor that collected the airborne particles and condensed phase metal aerosols, separating them into ten size ranges from 0.2 μm to greater than 10 μm. Metals to sorbent mass ratios between 0.03 and 1.56 were investigated. Scavenging efficiency increased as the ratio of sorbent to injected metal mass was increased. The scavenging efficiencies were as high as 76% for lead scavenged by kaolinite to as low as 14% for cadmium scavenged by alumina.  相似文献   
16.
/ Why are some environmental risks distributed disproportionately in the neighborhoods of the minorities and the poor? A hypothesis was proposed in a recent study that market dynamics contributed to the current environmental inequity. That is, locally unwanted land uses (LULUs) make the host communities home to more poor people and people of color. This hypothesis was allegedly supported by a Houston case study, whereby its author analyzed the postsiting changes of the socioeconomic characteristics of the neighborhoods surrounding solid waste facilities. I argue that such an analysis of postsiting changes alone is insufficient to test the causation hypothesis. Instead, I propose a conceptual framework for analysis of environmental equity dynamics and causation. I suggest that the presiting neighborhood dynamics and the characteristics of control neighborhoods be analyzed as the first test for the causation hypothesis. Furthermore, I present theories of neighborhood change and then examine alternative hypotheses that these theories offer for explaining neighborhood changes and for the roles of LULUs in neighborhood changes. These alternative hypotheses should be examined when analyzing the relationship between LULUs and neighborhood changes in a metropolitan area. Using this framework of analysis, I revisited the Houston case. First, I found no evidence that provided support for the hypothesis that the presence of LULUs made the neighborhoods home to more blacks and poor people, contrary to the conclusion made by the previous study. Second, I examined alternative hypotheses for explaining neighborhood changes-invasion-succession, other push forces, and neighborhood life-cycle; the former two might offer better explanation.KEY WORDS: Environmental equity and justice; Locally unwanted lane uses; Siting; Market dynamics; Invasion-succession; Neighborhood changes  相似文献   
17.
Jiao  Youzhou  Xue  Huizan  He  Chao  Wang  Zigang  Ma  Xiaoran  Liu  Xinxin  Liu  Liang  Chang  Chun  Petracchini  Francesco  Li  Panpan 《Environment, Development and Sustainability》2022,24(4):4709-4726
Environment, Development and Sustainability - Anaerobic digestion (AD) is an attractive straw resource treatment technology as it can improve the utilization efficiency of straw resource. Raw straw...  相似文献   
18.
张晓  胡春  张丽丽  石宝友 《环境科学学报》2020,40(11):3895-3904
采用醇助水热法制备了新型生物质炭修饰的α-FeOOH类芬顿催化剂(BC-FeOOH),并通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)对催化剂进行了表征,证明生物质炭(BC)成功引入到α-FeOOH中.以罗丹明B(RhB)为目标污染物,考察了BC修饰量、催化剂及H2O2投加量对其催化效率的影响.结果表明,BC的引入可以极大地提高FeOOH的类芬顿催化性能.在pH中性、催化剂投加量0.6 g·L-1、H2O2初始浓度10 mmol·L-1的条件下,BC-FeOOH(22.2% BC)对RhB的降解率可达到90%,重复利用5次活性仍可保持在80%左右,且铁离子溶出浓度仅为0.08 mg·L-1.进一步通过ESR在不同体系中的测试结果表明,BC的引入不仅可促进H2O2有效还原分解产生更多的羟基自由基(·OH),而且增强了催化剂与污染物RhB的相互作用,促使污染物失电子氧化降解,从而提高了FeOOH的催化活性及催化稳定性.  相似文献   
19.
太湖北部小流域沉积物重金属污染特征与评价   总被引:1,自引:0,他引:1  
孙恬  王延华  叶春  陈西 《中国环境科学》2020,40(5):2196-2203
近几十年来重金属的沉积记录、来源及污染水平受到了广泛关注.为探明太湖北部小流域重金属的污染来源和环境质量状况,本研究分析了柱状沉积物中8种重金属(Mn、Cr、Zn、Cu、As、Pb、Ni和Co)含量.运用主成分分析法判定污染源,富集因子法表征重金属富集特征,通过熵权模糊模型对沉积物中重金属污染状况进行评价.结果显示,所有重金属含量均较高,高低依次为Mn > Cr > Zn > Cu > As > Pb > Ni > Co.其中Mn含量最高,为380.06~767.69μg/g.沉积物重金属污染的主要贡献因子为交通排放、农业污染和煤炭燃烧.As的富集指数最大(2.89~15.61).其中77.59%的沉积层属于显著富集,受人类活动影响最为显著.熵权模糊综合评价结果表明,Cu(0.483)和As(0.352)的权重值最大,是沉积物中的首要污染物,且65.52%的沉积层重金属含量处于中度污染水平.  相似文献   
20.
Carbon–silica materials with hierarchical pores consisting of micropores and mesopores were prepared by introducing nanocarbon microspheres derived from biomass sugar into silica gel channels in a hydrothermal environment.The physicochemical properties of the materials were characterized by nitrogen physical adsorption(BET),scanning electron microscopy(SEM),and thermogravimetric(TG),and the adsorption properties of various organic waste gases were investigated.The results showed that microporous carbon materials were introduced successfully into the silica gel channels,thus showing the high adsorption capacity of activated carbon in high humidity organic waste gas,and the high stability and mechanical strength of the silica gel.The dynamic adsorption behavior confirmed that the carbon–silica material had excellent adsorption capacity for different volatile organic compounds(VOCs).Furthermore,the carbon–silica material exhibited excellent desorption characteristics:adsorbed toluene was completely desorbed at 150℃,thereby showing superior regeneration characteristics.Both features were attributed to the formation of hierarchical pores.  相似文献   
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