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351.
Istanbul has experienced rapid increases in population to more than 12 million people, which has created infrastructure problems of water supply and wastewater treatment and disposal. In this article, the achievements and approaches of the Istanbul Water and Sewerage Administration (ISKI) to solve the water shortage problem and to improve services are summarized. Istanbul had a very severe water shortage problem in 1994 because of ignorance of the implementation of the needed projects. After reviewing the reasons and causes of the problem, new priority criteria adopted after 1994 are given. Following the implementation of the projects determined according to the aforementioned criteria, water supplied has exceeded the water demand. The added capacity is equal to one to three times of the capacity built up to 1994 for water treatment, service reservoirs, pumping stations, transmission lines, and the water distribution network; water quality has been improved the meet local and international potable water standards. Unaccounted for water has been reduced from 60% to 27%. The percentage of treated wastewater has been increased from 10% to 90% in 8 years, resulting in drastic improvements and rehabilitation of the Golden Horn and coastal water quality. Through improved customer services, complaints were reduced from 33% in 1994 to 0.3%. Some of the main criteria and the approaches behind this success are summarized.
Published online 相似文献
352.
Brazil produces approximately 242,000 t of waste per day, 76% of it being dumped outdoors and only 0.9% recycled, including composting, which is an alternative still little known in Brazil. In search of a better destination for residues produced by domestic activities, composting stands as a feasible alternative. Organic compost from waste may be used for various purposes, among which are soil recovery, commercial production, pastures, lawns and reforestry and agriculture. However, the quality of the compost determines the growth and the development of plants. The effect of compost made from urban waste on corn plant (Zea mays L.) growth was investigated. Two types of compost were used: the selected compost (SC), produced from organic waste selectively collected; and the non-selected compost (NSC), taken from a 15-year-old cell from the Canabrava land-fill, located in Salvador, Bahia, Brazil (altitude 51 m, 12°22′–13°08′S, 38°08′–38°47′W). Corn was seeded in polyethylene pots, with soil-compost mixing substrate in the proportion of 0, 15, 30, 45 and 60 t ha−1 equivalent doses. Chemical analyses of the compost and growth properties of the plant like chlorophyll content; height and stem diameter; aerial and radicular dry biomasses, were used to evaluate compost quality. Plants cultivated with SC presented a superior gain, being of 52.5% in stem diameter, 71.1 and 81.2% in root and stem biomasses, respectively. Chlorophyl content alterations were observed in plants from treatments using 30 t compost ha−1 dose onwards. Conventional and multivariate statistical methods were used to evaluate these results. The beneficial action of organic compost in plant growth was confirmed with this research. 相似文献
353.
354.
Predicting Opportunities for Greening and Patterns of Vegetation on Private Urban Lands 总被引:1,自引:1,他引:1
Troy AR Grove JM O'Neil-Dunne JP Pickett ST Cadenasso ML 《Environmental management》2007,40(3):394-412
This paper examines predictors of vegetative cover on private lands in Baltimore, Maryland. Using high-resolution spatial
data, we generated two measures: “possible stewardship,” which is the proportion of private land that does not have built
structures on it and hence has the possibility of supporting vegetation, and “realized stewardship,” which is the proportion
of possible stewardship land upon which vegetation is growing. These measures were calculated at the parcel level and averaged
by US Census block group. Realized stewardship was further defined by proportion of tree canopy and grass. Expenditures on
yard supplies and services, available by block group, were used to help understand where vegetation condition appears to be
the result of current activity, past legacies, or abandonment. PRIZM™ market segmentation data were tested as categorical
predictors of possible and realized stewardship and yard expenditures. PRIZM™ segmentations are hierarchically clustered into
5, 15, and 62 categories, which correspond to population density, social stratification (income and education), and lifestyle
clusters, respectively. We found that PRIZM 15 best predicted variation in possible stewardship and PRIZM 62 best predicted
variation in realized stewardship. These results were further analyzed by regressing each dependent variable against a set
of continuous variables reflective of each of the three PRIZM groupings. Housing age, vacancy, and population density were
found to be critical determinants of both stewardship metrics. A number of lifestyle factors, such as average family size,
marriage rates, and percentage of single-family detached homes, were strongly related to realized stewardship. The percentage
of African Americans by block group was positively related to realized stewardship but negatively related to yard expenditures. 相似文献
355.
This paper examines the relationship between North American beef consumption and deforestation in South and Central America.
Some writers have argued that consumption of hamburgers in North America, particularly hamburgers consumed in fast food restaurants,
contributes to the depletion of the rainforest in South and Central America. We survey the published policy literature on
the causes of rainforest depletion in the region. We also review the published estimates of the rate and extent of clearing
of rainforest that has occurred in South and Central America since 1970. Finally, we review the data on beef imports and consumption
in Canada and the United States in a effort to assess the importance of South and Central America as suppliers of beef to
the North American market. We conclude that the relationship between beef consumption in North America should not be considered
an important cause of forest depletion in South and Central America. Domestic policies and market forces in the countries
where rainforests are located are the leading causes of rainforest depletion in this region. This lesson seems to have been
lost on some popular and even some textbook writers on this subject.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
356.
357.
Allan R. Ruff 《Journal of Environmental Planning and Management》1988,31(1):53-60
In Canada, increasing costs of maintenance, a shifting perception of what makes a city beautiful, a recognition of the needs and the importance of urban wildlife, and changing recreational demands are all contributing to a pressure for change in current practice. This study examines the extent to which the ecological approach has influenced the design and management of urban green space in Canada, focusing on the city of Toronto and its surrounding region as an example. 相似文献
358.
都西庙水库初级生产者只有浮游植物,它对太阳能年总辐射量的利用率为0.07%,生态学效率分别为10.5%、0.26%、6.40%,综合鱼产力为17.8g/m~2,各种经济鱼类对浮游植物的能量利用率为0.55%,表明牧食链中能量流动与分配不合理。本文对科学利用和保护该库饵料资源提出了建议。 相似文献
359.
中国生态农业与绿色食品 总被引:8,自引:0,他引:8
本文从农业环境问题和食品安全性出发,阐述了中国生态农业的兴起及特点,绿色食品生产的要求,生态农业与绿色食品的关系。介绍了几种可用于开发绿色食品的优化生态模式。 相似文献
360.
Environmental degradation, competition for resources, increasing food demands, and the integration of agriculture into the
international economy threaten the sustainability of many food production systems. Despite these concerns, the concept of
sustainable food production systems remains unclear, and recent attempts to appraise sustainability have been hampered by
conceptual inconsistencies and the absence of workable definitions. Six perspectives are shown to underpin the concept. Environmental
accounting identifies biophysical limits for agriculture. Sustained yield refers to output levels that can be maintained continuously.
Carrying capacity defines maximum population levels that can be supported in perpetuity. Production unit viability refers
to the capacity of primary producers to remain in agriculture. Product supply and security focuses on the adequacy of food
supplies. Equity is concerned with the spatial and temporal distribution of products dervied from resource use. Many studies
into sustainable agriculture cover more than one of these perspectives, indicating the concept is complex and embraces issues
relating to the biophysical, social, and economic environments. Clarification of the concept would facilitate the development
of frameworks and analytical systems for appraising the sustainability of food production systems.
LRRC Contribution No. 90–46. 相似文献