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631.
M.S. Bedinger James R. Harrill 《Journal of the American Water Resources Association》2006,42(4):827-839
ABSTRACT: Devils Hole is a collapse depression connected to the regional carbonate aquifer of the Death Valley ground water flow system. Devils Hole pool is home to an endangered pupfish that was threatened when irrigation pumping in nearby Ash Meadows lowered the pool stage in the 1960s. Pumping at Ash Meadows ultimately ceased, and the stage recovered until 1988, when it began to decline, a trend that continued until at least 2004. Regional ground water pumping and changes in recharge are considered the principal potential stresses causing long term stage changes. A regression was found between pumpage and Devils Hole water levels. Though precipitation in distant mountain ranges is the source of recharge to the flow system, the stage of Devils Hole shows small change in stage from 1937 to 1963, a period during which ground water withdrawals were small and the major stress on stage would have been recharge. Multiple regression analyses, made by including the cumulative departure from normal precipitation with pumpage as independent variables, did not improve the regression. Drawdown at Devils Hole was calculated by the Theis Equation for nearby pumping centers to incorporate time delay and drawdown attenuation. The Theis drawdowns were used as surrogates for pumpage in multiple regression analyses. The model coefficient for the regression, R2= 0.982, indicated that changes in Devils Hole were largely due to effects of pumping at Ash Meadows, Amargosa Desert, and Army 1. 相似文献
632.
Aaron C. Kite‐Powell Anna K. Harding 《Journal of the American Water Resources Association》2006,42(4):975-987
ABSTRACT: Approximately 4.5 million people in the United States who rely on well water are exposed to nitrate‐N concentrations exceeding the 10 mg/l standard. In this study in the Southern Willamette Valley in Oregon we reassessed nitrate‐N in rural wells sampled in 2000–2001, compared nitrate‐N concentrations among geological units, and surveyed residents about their perceptions of well water quality. Nitrate‐N concentrations were again sampled in 2002 and found to have increased significantly from the previous period. With rapid population growth in the area, the potential health risk in drinking well water that exceeds 10 mg/l nitrate‐N warrants continued public education. Nitrate‐N concentrations were found to be higher in the Holocene alluvium of the Willamette River and the Pleistocene sand and gravel post‐Missoula Flood deposits. Researchers conducting future studies may choose to stratify and monitor wells by geologic unit and by other parameters that estimate input of nutrients to the environment. Opinions differed between agricultural landowners and nonagricultural landowners with regard to the impact that agricultural fertilizers may have on water quality. Participants were supportive of a range of regulatory actions that might be used by homeowners or landowners to address ground water contamination. Given that the area is now designated a Groundwater Management Area, understanding local stakeholders’perceptions is critical and strategic and has the potential to help public agencies manage potential conflicts of opinion among stakeholders, build consensus, and help guide the approach to restoring ground water quality. 相似文献
633.
用纳滤膜分离技术处理发电厂循环冷却水 总被引:2,自引:1,他引:2
简要介绍了纳滤膜的定义和原理,并且对用纳滤膜处理厂循环冷却水进行工艺和经济技术分析。 相似文献
634.
P. Herzsprung K. Friese R. Frömmichen J. Göttlicher M. Koschorreck W. V. Tümpling Jr. K. Wendt-Potthoff 《Water, Air, & Soil Pollution: Focus》2002,2(3):123-140
In the past five years, enclosures have beeninstalled in an acidic mining lake in Lusatia to investigate insitu remediation processes. They were treated with straw, withstraw and Carbokalk, or with Carbokalk alone, where Carbokalkis a by-product of the sugar industry (solid precipitate ofnon-sugars after lime clarification of extracted sugar beetjuice). Sediment samples were taken as cores to get informationabout the behaviour of organic and inorganic components insediment pore-water with depth. Vertical distributions of pH,soluble reactive phosphate, nitrate, ammonium, silica,aluminium, iron, manganese, calcium, magnesium, sodium,potassium, sulphate, and DOC were measured. The resultingprofiles, each consisting of 15 data points at differentdepths, were compared by cluster analysis. The similarities ofsediment cores from different treated enclosures relating toprofiles of chemical components were discussed. Increasedconcentrations of potassium and sulphate were found in pore-water after substrate treatment. The data imply dissolution ofpotassium iron sulphate hydroxide minerals (jarosite) after anincrease of pH caused by dissolution of lime and by sulphatereducing processes which were stimulated by organic substrateaddition. 相似文献
635.
Estimation of Cumulative Frequency Distribution for Carbon Monoxide Concentration from Wind-Speed Data, in Buenos Aires (Argentina) 总被引:2,自引:0,他引:2
In this article we apply and test a methodology to estimate cumulative frequency distribution for air pollutant concentration from wind-speed data. We use the inverse relationship after Simpson et al. (Atmospheric Environment, 19, 75–82, 1985) between the opposing percentile values in the statistical distributions for air pollutant concentrations and wind-speed data. This relationship is valid, irrespective of the statistical distributions of both variables, if an inverse relationship between them is also applicable. The available data are five years of 8-h average carbon monoxide concentration and 8-h mean wind-speed, observed in Buenos Aires (Argentina). The performance of the obtained empirical expressions in estimating cumulative frequency distributions for 8-h CO is statistically evaluated. The results show that it is possible to obtain an acceptable cumulative frequency distribution for 8-h CO concentration at the site if the cumulative frequency distribution for wind-speed is known. Q–Q plots show a good agreement between estimated and observed values. From our data, the mean relative error of the estimations was found to be as much as 8.0%. 相似文献
636.
This paper presents an integrated system for the assessmentof technical and non-technical measures that are putforward in order to reduce air pollution levels in urbanareas. In contrast to the majority of the currentlyemployed assessment tools, this system allows for theevaluation of any proposed air pollution control measure interms of its combined impact on air quality and socialwelfare, by correlating the environmental and economicaspects of alternative air pollution abatement solutions.Based on the multi-pollutant, multi-effect concept, thesystem presented aims in providing policy-makers with areliable tool for the objective assessment of the mostcost-effective packages of measures, the latter beingallocated according to the particular features and needs ofthe areas examined. 相似文献
637.
638.
临夏回族自治州旅游客源市场分析与定位 总被引:2,自引:0,他引:2
本文在临夏州客源市场调查与分析的基础上,确定其客源市场应定位在周边地区,包括兰州、定西、甘南、青海省西宁、同仁等地市;在完善和发展观光休闲旅游的基础上,发展文化修学游、民族节庆体验游、生态休闲度假游、黄河三峡风情游、穆斯林民俗游、古生物考古游,并提出了相应的市场开发策略。 相似文献
639.
隧洞施工通风系统事故树分析 总被引:4,自引:0,他引:4
在采矿、铁路、公路及水利水电工程中,常常采用长距离隧洞或隧道来穿越高山。而隧洞的施工以其施工技术复杂、难度大、风险高,经常成为控制工程工期的主要环节,隧洞施工中的通风换气系统,关系到施工能否顺利进行和施工作业人员的人身安全,根据隧洞施工通风系统的运行特点,采用安全系统分析中的事故树(FTA)方法,对隧洞施工中通风系统的安全性进行定性分析,找出影响通风安全的主要因素,并提出了通风安全管理对策,可以保证施工作业的顺利进行和人身安全,提高整个施工作业的安全度。 相似文献
640.
基于小波包分析的爆破振动危害评价初探 总被引:2,自引:0,他引:2
结合振动主频的质点振速判据是对单一质点振速判据的补充和完善.但该判据的振动主频是通过FFT变换的频谱分析的方法获得的,不能体现爆破振动波形的多主振频带特征,而且由于方法本身的局限性使得主振频率发生的时间段不能确定.小波包分析法则克服了FFT频谱分析的局限,有效地分解和重构原始信号中的细节信号,并将其作为评价不同频率细节信号的爆破振动危害效果的基础.本文针对爆破振动的小波包分析法进行了研究,对各小波包细节信号加载条件下的不同危害效果进行了讨论,得到了相应的质点振速判据,并将该方法所得到的判据与FFT变换的频谱分析方法所得到的判据进行了对比.结果表明,基于小波包分析法的质点振速判据更加符合爆破振动危害的真实情况. 相似文献