首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
杨树沟曾经发生过3次泥石流,威胁主沟下游村庄、道路,属于易发泥石流沟,具有局部降雨强度高的气象水文条件,主沟狭长、支沟多的地形地貌环境条件,以及山坡两侧和沟底丰富的物源条件等特点。通过分析泥石流区段冲於特征和基本参数,提出对该泥石流沟的防治对策是"上游拦挡"与"下游排导防护"相结合。上游拦挡工程主要为设置拦挡坝,下游对原有防护堤进行加高、加长,将物源进行导流处理,以防止上游来水直冲居民聚居区。  相似文献   

2.
模糊数学综合评判法在泥石流沟判别与危害评价中的应用   总被引:2,自引:0,他引:2  
以西宁市东川北侧北山寺-中庄间泥石流形成的地质环境背景为基础,以流域面积,沟谷长度等11项因素为背景参数,应用模糊数学综合评法对泥石流沟进行判别与危险程度评介。其计算评介结果表明该方法可行,对监测和整治泥石流具有重要的参考价值。  相似文献   

3.
以西宁市东川北侧北山寺—中庄间泥石流形成的地质环境背景为基础,以流域面积、沟谷长度等11项因素为背景参数,应用模糊数学综合评判法对泥石流沟进行判别与危险程度评价.其计算评价结果表明该方法可行,对监测和整治泥石流具有重要的参考价值.  相似文献   

4.
青海省玛沁县大武镇北山血陇沟于2010年7月发生泥石流灾害,造成下游河源新村、日进村近150户家庭出现不同程度的损失,部分单位房屋围墙倒塌,泥石流灾害造成的直接经济损失达320余万元,危害性较大。在此背景下,文章在对泥石流形成的地质环境进行详细调查的基础上,分析了其发育特征,取得了其动力学参数,提出了相应的防治建议,为泥石流治理提供一定的参考。  相似文献   

5.
文章主要介绍了氧化沟工艺的优化设计,对改良型卡罗塞尔(Carrousel)氧化沟的池型、工艺参数、核心设备进行了选型优化,并结合实例对改良型氧化沟技术的应用进行了较为全面的论述。  相似文献   

6.
欢迎合资合作综合开发松潘牟尼沟旅游区牟尼沟位于四川省松潘县西侧39km处.地处国家级黄龙风景区内,距成都338km。牟尼沟气候宜人,风景秀丽。原始森林、高山灌木、绿色的草甸覆盖着整个泉域,海子、瀑布、树木相映成趣,区域内无人居住,珍稀禽兽随处可见,奇...  相似文献   

7.
氧化沟工艺技术的发展   总被引:8,自引:1,他引:7  
朱静平  柴立民 《四川环境》2004,23(4):57-60,74
本文从氧化沟的构筑形式、曝气设备、处理深度和运行方式等方面较为系统的阐述了其发展情况,并就氧化沟运行中经常出现的一些问题提出了解决对策。  相似文献   

8.
祁祖安 《青海环境》2006,16(2):85-86
河拉沟发育在湟源县城关镇北侧的低山丘陵区,上世纪50年代前,沟域内生态环境良好,很少发生泥石流灾害。以后随着生态环境的破坏,导致泥石流灾害频发,后又经生物和工程治理,泥石流得以基本遏制。本文根据泥石流灾害的发展变化,评述了泥石流综合防治效果及其防治措施的合理性。  相似文献   

9.
条子沟     
正镇街往西北走五里地,就是条子沟。沟长三十里,有四个村子。每个村子都是一个姓,多的二十五六家,少的只有三家。我差不多二十年没回去了,不禁感叹,当年镇街上人都进沟,现在人不来了,野物倒来了。沟口一个石狮子,脑袋是身子的一半,眼睛是脑袋的一半,斑驳得毛发都不清了,躺在烂草里,天旱时把它立起来,天就下雨。镇街上的人从来看不起条子沟的人,因为沟里没有水田,也种不成棉花,他们三六九日来赶集,背一篓柴禾,或掮一根木头,出去卖了,便在镇街的  相似文献   

10.
《中国环保产业》2011,(6):70-70
由北京桑德环境工程有限公司开发的改良型氧化沟污水处理技术,适用于市政污水处理。主要技术内容一、基本原理Carrousel 2000型氧化沟在沟体内存在缺氧区和好氧区,但不能很好地满足缺氧区要求的充足碳源和缺氧条件,因此,脱氮效果不是很好,同时无法去除污水中的磷。改良型氧化沟是在Carrousel 2000型氧化沟的基础上发展起来的,在Carrousel 2000型氧化沟前置厌氧段,污水经厌氧、缺氧、好氧交替运行,可以达到同时去除有机物、脱氮和除磷的目的,而且在这种交替运行状况下,丝状菌不宜生长繁殖,因此改良型Carrousel 2000氧化沟基本不存在污泥膨胀问题。  相似文献   

11.
Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] have been found with increasing occurrence in rivers and streams. Their continued use will require changes in agricultural practices. We compared water quality from four crop-tillage treatments: (i) conventional moldboard plow (MB), (ii) MB with ryegrass (Lolium multiflorum Lam.) intercrop (IC), (iii) soil saver (SS), and (iv) SS + IC; and two drainage control treatments, drained (D) and controlled drainage-subirrigation (CDS). Atrazine (1.1 kg a.i. ha-1), metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazine-5(4H)-one] (0.5 kg a.i. ha-1), and metolachlor (1.68 kg a.i. ha-1) were applied preemergence in a band over seeded corn (Zea mays L.) rows. Herbicide concentration and losses were monitored from 1992 to spring 1995. Annual herbicide losses ranged from < 0.3 to 2.7% of application. Crop-tillage treatment influenced herbicide loss in 1992 but not in 1993 or 1994, whereas CDS affected partitioning of losses in most years. In 1992, SS + IC reduced herbicide loss in tile drains and surface runoff by 46 to 49% compared with MB. The intercrop reduced surface runoff, which reduced herbicide transport. Controlled drainage-subirrigation increased herbicide loss in surface runoff but decreased loss through tile drainage so that total herbicide loss did not differ between drainage treatments. Desethyl atrazine [6-chloro-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine] comprised 7 to 39% of the total triazine loss.  相似文献   

12.
13.
14.
The strategies for reducing population growth include social development and improvement in the educational attainment of women. The decline in Kenya's growth rate was attributed to high female literacy and reduced infant mortality. Another strategy for enhancing fertility decline is to reduce child mortality, particularly from preventable causes such as diarrhea. The entire cost of such a strategy to reduce preventable disease would be about $1.33 per 300 million taxpayers in developed countries. Family planning services must be expanded. Prevention of maternal mortality and AIDS would bring major benefits. Strategies for environmental protection emphasized the already existing plan of action set out in the UNCED document Agenda 21 in Rio de Janeiro. The plan has suffered from inaction. The estimated cost of $625 million was considered to be several times smaller than the costs of inaction. The elimination of subsidies in tropical forests would have an immediate impact. Natural resource accounting at the national level would include the value of natural resources. Pricing would change radically for gasoline if the costs of urban smog, acid rain, low-level ozone pollution, and global warming were taken into account. Strategies for sustainable development pertained to the preceding strategies and others indicated in the Agenda 21 Action Plan. If funding were better targeted to the poorest 20% of global population with high fertility rates, the accomplishments would be heralded. 1.2 million are living in absolute poverty, and aid for nutrition, primary health care, water and sanitation, basic education, and family planning amounts to only 10% of expenditures. An increase to 20% would mean a contribution from Americans of $7.50 per person or 33% of $25 thousand million from all developed countries. Developing countries need to lower their military expenditures, privatize public enterprises, change inappropriate development policies, eliminate corruption, and improve national governance. The debt burden should be reduced.  相似文献   

15.
This study was undertaken to determine the fate of As, Mo, and V (trace elements, TEs) in the sediments of a constructed wetland in use for the remediation of potentially toxic trace element-contaminated agricultural drainwater. After three years of wetland operation, sediment cores were collected to determine changes in TE concentrations as a function of depth and the effects of varying water column depth. All TE concentrations were highest in the top 2 to 4 cm and decreased with depth. Molybdenum accumulated in the wetland sediments, up to levels of 32.5 +/- 4.6, 30.2 +/- 8.9, and 59.3 +/- 26.1 mg kg(-1) in the top 1 cm of sediment at water depths of 15, 30, and 60 cm, respectively. In the top 2 cm of sediment, As accumulated (28.2 +/- 3.0 mg kg(-1)) only at the 60-cm water depth. Below 2 cm, as much as 10 mg kg(-1) of As was lost from the sediment at all water depths. In most cases, V concentrations decreased in the sediment. In this wetland system, the lowest redox potentials were found near the sediment surface and increased with depth. Thus, in general As, Mo, and V concentrations in the sediment were highest under more reducing conditions and lowest under more oxidizing conditions. Most of the accumulated Mo (73%) became water soluble on drying of samples. This has important implications for systems undergoing changes in redox status; for instance, if these wetland sediments are dried, potentially large amounts of Mo may be solubilized.  相似文献   

16.
Scholarly critics such as Wendell Berry, as well as the popular media, frequently refer to problems associated with agriculture as the agricultural crisis or the farm crisis. Despite the identification of a problem or problems as symptomatic of this crisis, scant attention is paid to why the situation is a social crisis as opposed to a problem, tragedy, trend, or simple change in the structure of agriculture. This paper analyzes the use of social crisis as applied to the state of modern agriculture and, by extension, other crises such as those in legitimation and morality. It concludes that, although important social values associated with farming as a way of life may be in danger of being lost, the crisis we may be facing with respect to agriculture is more properly understood as a sociopolitical crisis that has broader implications than simply the loss of farms or traditional farming values. Indeed, what is in danger of being lost is our ability to affect a secure and sustainable political-economic system.  相似文献   

17.
Population,desertification, and migration   总被引:1,自引:0,他引:1  
When an imbalance develops between population numbers and the carrying capacity of the land, the persons thereby displaced are referred to as environmental refugees. The utilization of the land beyond sustainability leads to land degradation and ultimately, desertification. The social and political impacts of long-term environmental migration can be distinguished: a) at the site of origin of the displaced persons by the residual population; b) at rural sites of destination within the nation between the new arrivals and preestablished populations; c) in the cities within the nation; d) in the nonindustrialized foreign countries; and e) in the industrialized foreign countries. In the event that an area which had previously been devoted to pastoralism is converted to agriculture, the displaced pastoralists might respond through armed rebellion. In some instances, the disenchanted urban squatters become a politically restive and even a destabilizing force, as occurred in Sudan in the 1980s, especially in Khartoum and Port Sudan. The foreign countries to which many of the displaced persons are migrating are subjected to increasing levels of migrant-induced economic, cultural, and political strains. The growing problems associated with south-to-north migration across the Mediterranean Sea have recently led France, Italy, Portugal, and Spain to enter into a consultative arrangement with Algeria, Libya, Mauritania, Morocco, and Tunisia. All foreign aid to the nonindustrialized countries that attempts to ameliorate the problem of desertification must adopt integrated approaches that: a) address population issues; b) support environmental education; c) provide for the protection of biodiversity; d) encourage participatory forms of local and national government; e) provide opportunities for income generation outside the livestock sector; and f) foster political security and facilitate ecogeographical (subregional) cooperation.  相似文献   

18.
A person's response to an environment cannot be completely understood within a strict stimulus-response framework. The response sometimes depends, for example, on the person's plans and expectations, often partially or wholly formed before encountering that environment. This article reports three studies designed to explore just such influences on affective responses. Having to plan is itself shown to alter mood. Carrying out one's own plan is shown to be more pleasant than doing the same thing dictated by someone else's plan. A more subtle relationship among plans, expectations, and affect is also shown: liking for a place and positiveness of mood experienced there can, in certain circumstances, be enhanced by a previous violation of expectations and by an environment that had, temporarily, prevented execution of a plan.  相似文献   

19.
Disputes over agriculture and foodproduction have occurred against a background ofdisputed authority with regard to governments,experts, and single issue pressure groups. Consumershave intervened in quite significant ways with manyaltering their buying patterns. The conventionalassessment of consumer ``preferences' throughaggregated purchases fails to reflect the ethicalnature of significant numbers of purchase decisions.Nevertheless, consumers seem to offer a wider basis onwhich to consider ethical issues. The author proposesthat a valuable inclusion of consumer opinion in thedebates would require a move away from neo-classicaleconomics and the selective inclusion of consumeropinion to unravel the complexity of (aggregated)consumer behavior. It is argued that Hirschman'sframework of ``exit, voice, and loyalty' is a moreappropriate tool for the understanding of ethics infood consumption.  相似文献   

20.
Recent food emergencies throughout the world have raised some serious ethical and legal concerns for nations and health organizations. While the legal regulations addressing food risks and foodborne illnesses are considerably varied and variously effective, less is known about the ethical treatment of the subject. The purpose of this article is to discuss the roles, justifications, and limits of ethics of food safety as part of public health ethics and to argue for the development of this timely and emergent field of ethics. The article is divided into three parts. After a short introduction on public health ethics, all levels of food safety processes are described and the role that ethics play in each of these levels is then analyzed. In the second part, different models describing the function of food law are examined. The relationship between these models and the role of ethics of food safety is assessed and discussed in the final part, leading to some relevant comments on the limits of the role and effect of ethics of food safety.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号