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981.
Mohamed Lahlou Dale Colyer 《Journal of the American Water Resources Association》2000,36(5):1003-1012
ABSTRACT: This study examines water consumption characteristics in Casablanca and analyzes approaches for sustainable water demand management. Research procedures involve the development and estimation of water demand models for the residential/commercial, industrial, and institutional sectors; forecasts of water demand to 2010; and simulation of the effects of a complex of water conservation methods on the forecasted demands. The results indicate that residential/commercial water demand is weakly responsive to price changes (elasticity =?0.448) while institutional water demand is slightly more responsive (elasticity =?0.648). The conservation approaches used in the simulations included public education, plumbing code revisions to require use of water conservation devices, leak detection and repair, pricing policy, metering, and pressure reduction. The results indicate that considerable saving in water use can be attained through a comprehensive water demand management program. 相似文献
982.
Joseph S. Stibrich Thomas J. Charles 《Journal of the American Water Resources Association》2000,36(6):1263-1269
ABSTRACT: This paper describes how a hydrologic model proved to be a valuable tool to help interested parties understand impacts to four threatened and endangered fish species in the Upper Colorado River. In 1994, the Ute Water Conservancy District initiated permitting and design of the Plateau Creek pipeline replacement. The project was considered a major Federal action and therefore subject to the National Environmental Policy Act. Under Section 7 of the Endangered Species Act, the U.S. Fish and Wildlife Service (USFWS) entered the process to develop a Biological Opinion (BO) and determined that the project could potentially impact the endangered fish in the 15‐mile reach of the Colorado River. The Section 7 consultation was directed by a Core Committee comprised of stakeholders in the Upper Colorado River watershed. Hydrologic modeling became the evaluation tool for comparing flow reductions to USFWS target recovery flows and defining make‐up flow requirements to meet those targets. The Colorado River Recovery Implementation Program was designated to provide the make‐up flows. The USFWS released a final BO in December 1997, approving diversions through 2015. An Environmental Impact Statement for the project was completed and the Record of Decision was issued by the Bureau of Land Management in early 1998. 相似文献
983.
Christine L. Jocoy 《Journal of the American Water Resources Association》2000,36(4):811-821
ABSTRACT: Research on the condition of drinking water provision in the United States documents the inequitable financial impact of environmental regulations on small water systems (those serving 3,300 or fewer people). While a variety of federal and state financial assistance programs are available for water systems, few quantitative analyses have evaluated the success of these programs in alleviating the problems of small systems. A case study of the largest aid initiative for water supply infrastructure in Pennsylvania provides the empirical framework through which to analyze government funding opportunities for water systems. This study examines the allocation practices of the Pennsylvania Infrastructure Investment Authority (PENNVEST) to water systems of varying sizes. Utilizing data from PENNVEST applications and the Pennsylvania Department of Environmental Protection, the distribution of PENNVEST award recipients and denied applicants by size characteristics are compared. The study indicates that very small water systems (those serving 500 or fewer) do not apply for or receive funds with the same frequency as their larger counterparts. Understanding the allocation of awards from PENNVEST offers insight into the ability of small communities to access capital for water supply infrastructure. 相似文献
984.
985.
Polychlorinated naphthalenes (PCNs) and non-ortho chlorinated biphenyls (non-ortho CBs) were analysed in blubber, nuchal fat, liver, muscle, kidney and brain of three male harbour porpoises (Phocoena phocoena) from the west coast of Sweden. To estimate spatial variation, PCNs and non-ortho CBs were analysed in six blubber samples collected at different anatomical sites of each animal. Highest wet weight concentrations of ΣPCNs were detected in the lipid rich tissues (blubber and nuchal fat) and liver (520–730 and 520 pg/g, respectively) and lowest in brain (22 pg/g). TetraCNs were most abundant in muscle, kidney and brain, while the hexaCNs were most abundant in the lipid rich tissues and liver. The highest lipid weight concentration recorded (11 ng/g) was for the hexaCN congeners no. 66/67 in liver. These coeluting hexaCN congeners accounted for 80–100% of total hexaCNs in all tissues examined.Concentrations of Σnon-ortho CBs were highest in lipid rich tissues (220–280 pg/g wet weight). Non-ortho CB no. 77 and 169 constituted between 62–86% and 4.9–9.3%, respectively, of total Σnon-ortho CBs. No major variation of Σnon-ortho CB concentrations was found between the six different blubber sites but higher ΣPCN concentrations (wet weight) were found dorsally at the peduncle. Toxic equivalent concentrations (TEQs) showed that non-ortho CB no. 126 was the main contributor to total TEQs in all tissues, except liver in which hexaCN congener nos. 66/67 contributed to about 50% of total TEQs. 相似文献
986.
和田河年径流变化规律研究 总被引:15,自引:1,他引:14
根据和田河实测年径流资料,应用小波分析、R/S分析等多种方法,探讨了在气候变化和人类活动影响下,和田河年径流变化规律及其成因。结果表明,和田河年径流存在减少趋势,且具有一定的持续性。通过径流变化的影响因素分析表明,上游出山口处两支流的径流变化主要受气温升高的影响,下游入塔里木河处除受降水减少的影响外,主要是由于人类对水土资源开发进程的加快,人类活动是其径流变化的主要原因。 相似文献
987.
Resistance of the generalist moth Trichoplusia ni (Noctuidae) to a novel chemical defense in the invasive plant Conium maculatum 总被引:1,自引:0,他引:1
Summary.
Conium maculatum is an apiaceous species native to Eurasia that is highly toxic to vertebrates due to the presence of piperidine alkaloids,
including coniine and γ-coniceine. More than 200 years after invading the United States this species remains mostly free from
generalist insect herbivores. The presence of novel chemical defenses in the introduced range could provide invasive species
with a competitive advantage relative to native plants. The cabbage looper (Trichoplusia ni) is a generalist lepidopteran found throughout the US that occasionally feeds on C. maculatum. We evaluated the toxicity of piperidine alkaloids to T. ni and determined putative resistance mechanisms, both behavioral and physiological, that allows this insect to develop successfully
on C. maculatum foliage. T. ni larvae raised on diets enriched with coniine and γ-coniceine showed a decrease in consumption and longer development time,
but no effects on growth were found at any alkaloid concentration. In a diet choice experiment T. ni larvae showed no avoidance of alkaloid-enriched diets, suggesting that the deterrence produced by alkaloids was related to
a post-ingestive metabolic response. The ability of T. ni to consume diets high in alkaloid content could be due to at least three different mechanisms: 1) a decreased consumption
rate, 2) efficient excretion of at least 1/3 of ingested alkaloids unmetabolized in frass, and 3) partial detoxification of
alkaloids by cytochrome P450 s, as shown by the decreased larval growth in the presence of piperonyl butoxide, a P450 inhibitor.
Even though T. ni tolerates C. maculatum alkaloids, the use of this species as a host plant could be ecologically disadvantageous due to prolonged larval growth and
thus increased exposure to predators. Novel plant secondary compounds do not guarantee increased resistance to generalist
herbivores. 相似文献
988.
树舌灵芝多糖对肝纤维化大鼠的肝功能的影响 总被引:2,自引:0,他引:2
观察树舌灵芝多糖对肝纤维化大鼠的肝功能的影响.采用经典的四氯化碳肝纤维化模型,造模同时给予树舌灵芝多糖干预,4周后采血测血清AST、ALB、A/G、HDL,实验中观察大鼠的一般状况.树舌灵芝多糖能显著降低四氯化碳肝纤维化大鼠血清ALIT、Mb、A/G水平.在肝纤维化的病理进程中,采取树舌灵芝多糖进行干预,可改善大鼠肝功能.表3,参5. 相似文献
989.
Nina H. Fefferman James F. A. Traniello Rebeca B. Rosengaus Daniel V. CalleriII 《Behavioral ecology and sociobiology》2007,61(4):565-577
Understanding the origin of disease resistance in social insects is difficult due to the lack of well-established phylogenies
of presocial and eusocial species and the absence of extant basal and intermediate forms. Moreover, comprehensive accounts
of infection-control traits in social insect lineages are not available. Therefore, to explore the evolution of pathogen control
in social insects we used cellular automata models to analyze the efficacy of immunity and nest hygiene, which we assumed
were basal traits, and allogrooming, which likely followed the transition to eusociality, and their interactions with colony
demography and patterns of worker spatial distribution. Models showed that nest hygiene provided an immediate survival benefit
and that immunity lowered overall disease susceptibility under both constant and periodic exposure scenarios. Allogrooming
increased survivorship in chronically challenged colonies but also increased pathogen transmission rates under conditions
of periodic exposure. Colonies having demographies biased towards young or old individuals had slightly higher mortality than
those with heterogeneous demographies. The distribution of older individuals relative to the nest center had no significant
effect on susceptibility and provided only a minor survival advantage. Models indicated that nest hygiene and immunity function
on different temporal scales and can interact with demography to lower disease risks. Our results suggest how infection control
systems in social insects could have been built upon the inducible immune defenses and nest hygienic behaviors of solitary
and presocial ancestors and served as important preadaptations to manage disease exposure and transmission in colonies of
eusocial species. 相似文献
990.