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21.
Biju A. George Hector M. Malano Ahmad Raza Khan Anju Gaur Brian Davidson 《Environmental Modeling and Assessment》2009,14(6):691-704
To keep pace with population and economic growth, the city of Hyderabad, India, will need to identify and develop new supply
sources almost continually. Increasing population growth rate, declining surface water resources, overexploitation of groundwater,
deterioration of ground water quality and poor sewage treatment are the major water-related issues in Hyderabad. This paper
reviews the current situation facing policy makers who need to come to terms with the problem of restricted water supply and
increasing demand in an urban centre such as Hyderabad, India. The City Water Balance model developed in this study can be
used to analyse different scenarios that include water conservation, urban wastewater reuse and improvement of distribution
and conveyance efficiency. Water conservation programs, which include a 5% conveyance efficiency improvement, reusing 90 million
cubic metres (MCM) of urban runoff and adoption of water harvesting by 0.5 million households together with recycling 120
MCM of wastewater recycling wastewater would be sufficient to meet the water demand by 2031, if the population grows at a
rate of 2.5%. 相似文献
22.
Hector Hernan Rodríguez Omar Espinoza-Navarro Ivan Silva Douglas Needham María Eugenia Castro Luis Sarabia Juan Inostroza Leonella Jimenez 《Environmental science and pollution research international》2011,18(3):497-502
Introduction and aims
The Chilean Altiplano ecosystem is conserved free from contaminants and pollutants because of the absence of major local human activities such as agriculture or other industries. We studied the effects of paraoxon on proliferation and apoptosis of testicular cells during active spermatogenesis in Dugesia gonocephala collected from a pristine river (Guacollo) in the Altiplano region nearby Visviri town, Chile. 相似文献23.
Historical decline in coral reef growth after the Panama Canal 总被引:1,自引:0,他引:1
The Panama Canal is near its vessel size and tonnage handling capacity, and Panamanians have decided to expand it. The expansion of the Canal may consider the historical long-lasting impacts on marine coastal habitats particularly on sensitive coral reefs. These potential impacts were discussed during the national referendum as were other equally important issues, such as its effects on forests, watersheds, and water supply. Coral growth rates provide a direct measure of coral fitness and past environmental conditions comparable to analyses of tree rings. We examined stable isotopes, metal geochemical tracers, and growth rates on a century-long (1880-1989) chronology based on 77 cores of the dominant reef-building coral Siderastrea siderea collected near the Caribbean entrance to the canal. Our results showed a gradual decline in coral growth unrelated to changes in sea surface temperature but linked to runoff and sedimentation to coastal areas resulting from the construction and operation of the Panama Canal. 相似文献
24.
Agricultural income from growing crops is susceptible to a variety of risks—the price of output and the actual amount of output are generally the largest risk variables. This article focuses on yield risk rather than price risk by reviewing innovation in risk transfer for natural hazard risk in agriculture. While many higher-income countries have long-standing crop insurance programs, these programs are not appropriate for lower-income countries. Lower-income countries can ill-afford the subsidies that are used in most multiple peril crop insurance programs throughout the world. Still, lower-income countries have large numbers of small farms increasing the need for agricultural insurance to protect against common problems that create disastrous losses for many individual farm households. 相似文献
25.
Ali Fares H. Hamdhani Viktor Polyakou A. Dogan Hector Valenzuela 《Journal of the American Water Resources Association》2006,42(6):1527-1535
Abstract: Efficient water resource management is one of the most important policy issues facing agriculture in Hawaii in the years ahead. Soil water sensors, multisensor capacitance probes (MCP), have been successfully used for different water management projects. These MCPs monitor water content at multiple depths and at various locations in real-time. The objectives of this study were to determine the effect of water content on field soil bulk density of Wahiawa silty clay tropical soil; measure field saturated hydraulic conductivity of this tropical soil: calibrate MCP system for this soil: and monitor and evaluate real-time soil water content variations under a tomato crop using the calibrated MCP system. Sensor calibration was conducted under laboratory conditions. Soil bulk density at different water contents and saturated hydraulic conductivity were measured on the field. Bulk density increased with increasing water content: there was a 30 percent bulk density increase as a result of 0.25 cm3 cm-3 water content variation. Compared with the manufacturer's calibration, site specific laboratory calibration of MCP gave a more accurate determination of soil water. Field determined saturated hydraulic conductivity was higher than laboratory determined values reported in the literature for the same soil type. Real-time soil water content monitoring within the root zone showed substantial variations due to water input (irrigation and rainfall) and water output (evapotranspiration and deep percolations). However, water content variations were much further reduced in the soil layer below the root zone. 相似文献
26.
Monterde i Bort H 《Journal of Safety Research》2004,35(3):329-335
PROBLEM: This study tests whether the original factorial structure of a recklessness questionnaire can be maintained for the current Spanish population of older drivers. JUSTIFICATION: Our recent interest in dedicating special attention to senior citizen mobility (Monterde, 2001), is due to the impending increase of the aging population in Western countries; this has led us to reinitiate the psychometric study of the construct validity, revising and including older drivers in the psychometric aspects of those evaluation instruments that will then be used in the Spanish psycho-medical check of drivers and in research. METHODS: Factorial analysis was used to determine validity. RESULTS: There was an appearance of a different psychological pattern in elderly drivers, specifically, a psychological anxiety trait related to the task of driving. Furthermore, interesting data were found about the attitude of this sector toward the "traffic society" and toward some of the measures included in Spanish legislation that affect especially older drivers (such as the psycho-medical check). IMPACT ON INDUSTRY, RESEARCH AND PRACTICE: These results suggest the possible existence of some kind of "compensation phenomenon," which could have influence over the scores obtained and their interpretation. Consequently, the evaluation instruments should be tested and, if necessary, adapted or specifically created for use with this age group. 相似文献
27.
Ilie S. Racotta Elena Palacios Ana M. Ibarra José Luis Ramírez Fabiola Arcos Olivia Arjona 《Marine Biology》2008,153(6):1245-1256
Induction of triploidy in aquatic organisms has increased worldwide in the last two decades, mostly because triploids have
better growth than diploids. According to a physiological hypothesis, partial or total sterility of triploids allows the accumulation
of reserves in muscle and other tissues instead of being transferred to the gonad. The present study analyzes lipid, protein,
carbohydrate, and fatty acid levels in muscle and gonads of Nodipecten subnodosus triploids and diploids over 18 months from June 2001 to December 2002. An important increase in gonadosomatic index of diploids
scallops was observed from May to June 2002 reaching the highest values in August. Such increase was not observed in triploid
scallops. Changes in biochemical composition in female gonad were in general related to the accumulation of reserves during
gonad development of diploid scallops. This accumulation was lower for triploid scallops, in accordance to their sterility,
especially for carbohydrates and acylglycerides. Adductor muscle index as well as protein and carbohydrate levels in muscle
increased in both ploidy groups during the reproductive period indicating no mobilization of reserves to sustain gonad development
in both ploidy groups. These results partially support the physiological hypothesis on the advantage of triploids: in a rich
food locality no mobilization of reserves is needed to sustain gametogenesis. This, together with a possible lower efficiency
of energy assimilation at high food concentration for triploids, may be the reason for an apparent lack of superiority of
N. subnodosus triploids in terms of adductor muscle growth. Only the levels of particular highly unsaturated fatty acids levels (namely
20:4n-6 and 20:5n-3) in muscle of diploid and triploid decreased during the reproductive period, indicating a possible transfer of selected
fatty acids to gonads, even in triploids. The muscle of triploids has a slightly but significantly higher proportion of 22:6n-3 compared to diploids, which can have implications for the nutritional and commercial value of triploid adductor muscle. 相似文献
28.
Hector Hito Sepulveda 《Journal of Coastal Conservation》2012,16(1):63-64
In a paper published recently in the Journal of Coastal Conservation, Al-Ghamdi (J Coast Conserv 14:63–69, 2010) analyzes the wastewater multi-pot outfall of Jeddah using CORMIX2 for average ambient conditions. Both the near–field and
the far–field mixing are calculated with CORMIX2. It is found in Al-Ghamdi (J Coast Conserv 14:63–69, 2010) that the near-field extends 187.5 m downstream from the diffuser, where the dilution reaches 1,047.8. It is at this same
distance, 187.5 m, that the plume touches the water surface. The far-field dilution and plume width is calculated as the plume
finally fills the entire water depth at a distance of 18,927 m downstream. From these analyses, it is concluded that local
and international standards for treated wastewater are met and that the plume “will not pose any treats to the local venerable
environment”. These findings, if correct, will help to protect the surrounding marine environment. However, is argued here
that the use of CORMIX2, particularly for the far-field environment is not well justified and that the inherent simplifications
in the software and its use, mainly the characterization of the physical environment, undermine the main conclusions. 相似文献
29.
Vassilios A. Tsihrintzis Hector R. Fuentes Rao K Gadipudi 《Journal of the American Water Resources Association》1996,32(2):317-331
ABSTRACT: Agricultural and urban activities in the West Wellfield Interim Protection Area (WWIPA), located in West Dade County in South Florida, have the potential to impact both the environmentally sensitive Everglades and the Biscayne Aquifer. The Hydrological Simulation Program-FORTRAN (HSPF) is used to simulate surface runoff, ground water recharge, and transport of sediments, nutrients, and pesticides in the WWIPA, as a basis to quantify impacts and evaluate alternatives. Presented are four model test runs that consider current conditions, the effect of future urbanization of the agricultural land, as well as two preventive actions to minimize pollution levels. Preventive actions include application of minimum required rates of fertilizers and replacement of fertilizers by sewage sludge. Model results show that under current practices, sediments, nutrients, and pesticides are present in surface runoff and nutrients enter the ground water, and that both urbanization and preventive actions result in pollutant reductions. 相似文献
30.
Soft subgrades’ stabilization by using various fly ashes 总被引:1,自引:0,他引:1
Aykut Senol Tuncer B. Edil Md.Sazzad Bin-Shafique Hector A. Acosta Craig H. Benson 《Resources, Conservation and Recycling》2006,46(4):365-376
This publication presents the results of research involving different types of self-cementing fly ashes (without any other activators) for the stabilization of four different types of soft subgrades from various road sites in Wisconsin, USA. The strength approaches were applied to estimate the optimum mixture design and to determine the thickness of the stabilized layer. The stabilized soil samples were prepared by mixing fly ash at different contents at varying water contents. The performance of fly ash stabilized subbase depends both on the specific source of fly ash and the engineering properties of soils. It is suggested that the performance analysis of fly ash should be based upon the laboratory tests such as index properties, compaction, unconfined compressive strength and CBR tests of a specific site. This is suggested rather than using the study of the physical properties and chemical composition of fly ash and soil. As disclosed in the literature, the strength gain due to stabilization depends mainly upon three factors; ash content, molding water content and compaction delay. The samples were subjected to unconfined compression strength and California bearing ratio (CBR) tests after 7 days curing time to develop water content–strength relationship. To evaluate the impact of compaction delay that commonly occurs in the field during construction, the sets of samples were compacted 2 h later after mixing with water. The unconfined compression strength and CBR tests were performed and used to determine the thickness of the stabilized layer in pavement design. All of these factors were taken into account throughout this research. 相似文献