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201.
Errors in environmental resource management over the years have created pollution problems in some areas which are difficult to handle, regardless of the development of knowledge and technologies. This is particularly true in the case of soil pollution. The negative effects of persistent pollutants have been observed for a long time. For instance, lead and cadmium remain in the soil for centuries, during which time they are absorbed by plants and simultaneously cause secondary air pollution. The authors made an attempt to describe and assess the possible options of dealing with the problem of contaminated land in Katowice District. Considering the necessity of a multilateral approach, a pairwise comparison technique has been chosen as the most suitable to show the complexity of the problem. The different variants of actions aimed at preventing the pollutants from getting into the food chain were analyzed against a set of criteria, consisting of the following issues: time, cost, effectiveness, social acceptance, feasibility. The relative importance of actions were judged by the team of experts using the Saaty method. Also, a two-perspective assessment (the two different stakeholders), which involves considering the perspective of an owner of a piece of contaminated land and an ecologist has been performed. The results of comparative, multicriteria and multi-perspective assessment indicate the following:- the best method for contaminated agricultural land management is willful and controlled cultivation,- other recommended actions are deep ploughing and phytoremediation,- there is not much acceptance for the other methods.  相似文献   
202.
The condition of 25 stream sites in the Yakima River Basin, Washington, were assessed by the U.S. Geological Survey's National Water-Quality Assessment Program. Multimetric condition indices were developed and used to rank sites on the basis of physical, chemical, and biological characteristics. These indices showed that sites in the Cascades and Eastern Cascades ecoregions were largely unimpaired. In contrast, all but two sites in the Columbia Basin ecoregion were impaired, some severely. Agriculture (nutrients and pesticides) was the primary factor associated with impairment and all impaired sites were characterized by multiple indicators of impairment. All indices of biological condition (fish, invertebrates, and algae) declined as agricultural intensity increased. The response exhibited by invertebrates and algae suggested a threshold response with conditions declining precipitously at relatively low levels of agricultural intensity and little response at moderate to high levels of agricultural intensity. This pattern of response suggests that the success of mitigation will vary depending upon where on the response curve the mitigation is undertaken. Because the form of the community condition response is critical to effective water-quality management, the National Water-Quality Assessment Program is conducting studies to examine the response of biota to gradients of land-use intensity and the relevance of these responses to water-quality management. These land-use gradient pilot studies will be conducted in several urban areas starting in 1999.  相似文献   
203.
This paper introduces some of the issues that are relevant to the spatially explicit modeling of land use systems. A short overview is given of the ways and means in which a number of different land use change models describe the land use system. Specific attention is given to the empirical modeling approach used in the CLUE (Conversion of Land Use and its Effects) modeling framework. This approach is demonstrated for three case studies in China, Ecuador and the Atlantic Zone of Costa Rica. These case-studies illustrate the methodology for multi-scale analysis of land use driving factors and their application in spatially explicit modeling exercises. Model functioning, performance and limitations are discussed. The presented case-studies indicate that empirical modeling results can contribute to a better theoretic imbedding of land use change research in scale sensitive and integrated theories.  相似文献   
204.
A study of climate change and anthropogenic impacts in West Africa   总被引:3,自引:0,他引:3  
BACKGROUND, AIM AND SCOPE: During the last decades ecological conditions in West Africa have dramatically changed. Very evident is the climate change, which has resulted in a southward shift of the climate zones, e.g. a spread of the desert (Sahara) into the Sahelian zone. After the drought period of the early 1970s and 1980s, livestock density increased resulting in an intensification of grazing pressure. This anthropogenous phenomenon leads to similar landscape changes as those caused by the climate. Only very few investigations exist on vegetation dynamics, climate changes and land use changes for the Sudanian zone. The paper presents data on changes of precipitation, of land use, of the geographical range of species, and of the composition of the flora, which have to be regarded as proofs of the sahelisation of large areas of the Sudanian zone. MATERIALS AND METHODS: Area of investigation: Burkina Faso. Precipitation data analysis: precipitation data from 67 stations; time series analysis and geo-statistical spatial interpolation. Analysis of land use change: Landsat satellite MSS and ETM+ data, acquired for two different dates between 1972 and 2001 analyzed by the software ERDAS/IMAGINE version 8.6 and ArcView 3.2 with the Spatial Analyst extension. Intensive ground truthing (160 training areas). Inventory of the flora: based on the data of the Herbarium Senckenbergianum (FR) in Frankfurt, Germany, and of the herbarium of the university of Ouagadougou (OUA), Burkina Faso, as well as on various investigations on the vegetation of Burkina Faso carried out in the years 1990 to 2005 by the team of the senior author. Life form analysis of the flora: based on the inventory of permanent plots. RESULTS AND DISCUSSION: Precipitation: Remarkable latitudinal shift of isohyets towards the South translates to a general reduction of average rainfall in great parts of the country. The last decade (1990-1999) shows some improvement, however, the more humid conditions of the 1950's and 1960's are not yet established again. Landcover change: In the study region the extent of arable fields and young fallows increased during the last 30 years from 580 km(2) in 1972 to 2870 km(2) in 2001. This means an average land cover conversion rate of 0.9% per year for the 6 departments considered. Change of the distribution of Sahelian and Sudanian species: Several species, mentioned in older literature as strictly Sahelian, today also occur in the Sudanian zone. Parallel to the spread of former strictly Sahelian species into the Sudanian zone, some former Sahelo-Sudanian species have withdrawn from the Sahel. Changes of the life form spectra of the flora: Considering their life form spectra, the flora of heavily grazed and of protected areas in the Sudanian zone show great differences. On areas intensively grazed the percentage of therophytes is evidently higher than on protected areas. Just the opposite is true for the phanerophytes. Their percentage is higher on the protected area than on the grazed zones. At the first glance, it is obvious to link the changes in flora and vegetation with the climate changes that have occurred during the last five decades (decrease of annual precipitation). However, not only climatic conditions have changed, but also population has increased, the percentage of land intensively used for agriculture and pasturing has increased and the time for soil regeneration today is much shorter than it was some decades ago. Thus, the landscape of the Sudanian zone has become a more Sahelian character. A comparison of the flora of an intensively used area of the Sudanian zone with that of a protected area shows a remarkable change in the life form spectra. The spectrum of the intensively used area is almost identical with that of the typical Sahelian flora. This comparison shows that the anthropogenic influence plays a greater role in the sahelisation of the Sudanian zone than the climate change. CONCLUSION: Climate change and anthropogenic influence both, lead to a sahelisation of landscape and flora. Thus in many parts of the Sudanian zone of West Africa sahelisation phenomena will remain and even increase independently from the reestablishment of the more humid climate conditions of the 1950ies. RECOMMENDATIONS AND PERSPECTIVES: In order to maintain some parts of the characteristic Sudanian landscape with its characteristic flora and vegetation, the number and size of protected areas should be augmented. For all protected areas it has to be ensured, that protection is reality, i.e. respected an understood by local people, not only fiction. As long as the enlargement of intensively used areas continues the sahelisation of flora, vegetation and landscape will continue too.  相似文献   
205.
Previous research addressing the unequal distribution of locally desirable land (LDL) has mainly ignored their associated environments (i.e., rural or urban). However, this study proposed a new framework that treats rural and urban regions separately. In rural areas, the LDLs included all public lands. In urbanized areas, the LDLs were defined as green open spaces. Potential inequities in the distribution of LDL were assessed with respect to socioeconomic characteristics of residents in the State of Georgia. Using US Census Bureau Data (2000), Census Block Groups (CBGs) adjacent to LDLs were compared to CBGs outside of LDLs on four socioeconomic variables (per capita income, occupation, education, and race) in urban, suburban and rural environments. Results showed that CBGs adjacent to LDLs were composed of statistically significant upper-class communities containing fewer blue-collar workers, more whites, and higher income and higher educated people in rural, suburban and urban areas.  相似文献   
206.
鱼红霞 《四川环境》2008,27(6):63-67
衔接土地利用规划和建设项目的土地一级开发伴随着土地政策的改革而出现。目前土地一级开发环境影响评价处于起步阶段,缺乏对这项工作系统的研究。本文结合工作中的实践经验,从土地一级开发环境影响评价实施的意义、作用和评价目的等方面对土地一级开发的环境影响评价进行了论述,分析了其环境影响评价存在的问题,总结了土地一级开发环境影响评价的技术要点,并对完善土地一级开发环境影响评价制度提出建议。  相似文献   
207.
农村生活污水治理措施   总被引:1,自引:0,他引:1  
蒋克彬  彭松  王明明 《四川环境》2008,27(5):114-117
介绍了适合于国内农村生活污水治理的一些技术与措施。沼气技术是当前处理农村生活污水的较佳选择。  相似文献   
208.
园林树木栽培学是一门实践性很强的有关园林绿化领域的专业课、必修课.1995年以来,本人在园林树木栽培学各论教学中尝试重点讲解、课堂点评的教学方法,取得了较好的教学效果.  相似文献   
209.
根据《江苏统计年鉴 (1 999)》等相关资料 ,对江苏耕地资源利用中存在的一些问题进行了分析与总结 ,在此基础上 ,对实现江苏耕地资源可持续利用的相关对策进行了探讨  相似文献   
210.
为探究城市建设用地集聚对城市建设用地利用效率的作用机理,文章基于2003—2017年中国278个地级及以上城市面板数据,通过构建多产出随机前沿生产函数模型测度城市建设用地利用效率,采用时间-空间双固定的空间杜宾模型探讨了不同程度的城市建设用地集聚对利用效率的影响机理与差异。结果表明:(1)从时空特征上来看,样本考察期内中国城市建设用地利用效率总体上呈稳步提升趋势,东部城市建设用地效率最高,西部次之,中部最低。(2)从全国维度的空间计量模型回归结果来看,城市建设用地集聚所带来的规模效应和外溢效应对城市建设用地利用效率具有改进作用,有利于利用效率进一步提升。(3)从不同城市建设用地集聚度分群回归结果来看,高集聚城市(东部发达地区)的直接效应显示随着城市建设用地集聚度的提高,利用效率也不断提高;间接效应中,建设用地集聚度的提高对周边城市的利用效率产生先带动后抑制的"倒U"形作用。低集聚城市(中西部欠发达地区)的直接效应和间接效应均显示,随着城市建设用地集聚的提高,其利用效率存在"先降后升"的"U"形曲线特征。可见,在城市发展的不同阶段,城市建设用地集聚对城市土地利用效率存在差异化影响。因此,中国城市发展应立足当前发展阶段特征,制定差别化的供地政策,促进城市建设用地集聚,针对性地提升区域要素利用效率,支撑经济社会进一步发展。  相似文献   
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