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491.
Haie, Naim and Andrew A. Keller, 2012. Macro, Meso, and Micro‐Efficiencies in Water Resources Management: A New Framework Using Water Balance. Journal of the American Water Resources Association (JAWRA) 48(2): 235‐243. DOI: 10.1111/j.1752‐1688.2011.00611.x Abstract: One of the most important performance indicators for water resources systems (WRSs) management is efficiency. Here, water balance, based on mass conservation, is utilized to systemically develop three levels of composite efficiency indicators for a WRS, which are configurable based on two types of water totals: total inflow and total consumption (outflow that effectively is not available for reuse). The indices characterize hydrology of an area by including in their formulations the flow dynamics at three integrated levels. Furthermore, the usefulness of water is incorporated into the indicators by defining two weights: one for quality, and the other for beneficial attributes of water use. Usefulness Criterion is the product of quality and beneficial weights, emphasizing the equal significance of the two dimensions. Both of these weights depend on the system itself and the priorities of the supervising organization, which also are shaped by the objectives and values of the given society. These concepts lead to the definition of Macro, Meso, and Micro‐Efficiencies, which form a set of integrated indicators that explicitly promotes stakeholder involvement in evaluation and design of WRSs. Macro, Meso, and Micro‐Efficiencies should be maximized for both water totals, which is an integrated prerequisite for sustainability and is less promoted by competing stakeholders. To demonstrate this new framework, it is applied to published data for urban and agricultural cases and some results are explained. 相似文献
492.
水资源系统的弹塑性及其安全机理分析 总被引:1,自引:0,他引:1
针对水资源安全存在的问题,分析了"人"对水资源安全系统的作用,明确提出"人"是水资源安全的主体。运用弹塑性理论,提出了水资源安全系统的弹性与塑性内涵。在水资源安全系统的弹性范围,推导出水资源安全的平衡方程、相容方程和本构方程,并进而分析了水资源安全系统从安全状态到危险状态的转化过程,即系统表现出的弹性、弹塑性、塑性极限以及完全破坏状态模式,从数学和力学角度描述了水资源安全的机理。当"人"的扰动力大于水资源安全系统的弹性界限时,水资源安全系统就会出现塑性变形,即出现威胁水资源安全的问题,若扰动力进一步增大,水资源安全系统就会出现严重破坏或崩溃。 相似文献
493.
Quantifying the importance of diffuse minewater pollution in a historically heavily coal mined catchment 总被引:1,自引:0,他引:1
Mayes WM Gozzard E Potter HA Jarvis AP 《Environmental pollution (Barking, Essex : 1987)》2008,151(1):165-175
There has been considerable progress in developing treatment systems for point sources of minewater pollution in recent years; however, there remains a knowledge gap in the characterisation and remediation of diffuse minewater sources. Data are presented from the River Gaunless catchment, a historically heavily coal mined catchment in the northeast of England. Instream iron (Fe) loadings were monitored alongside loadings arising from point minewater discharges over a 12-month period to assess the dynamic importance of diffuse sources of minewater pollution. In low flow, diffuse sources account for around 50% of instream loading, a proportion which increases to 98% in high flow conditions. The low flow sources appear to be dominated by direct discharge of contaminated groundwater to surface waters in lower reaches of the catchment. In high flow, resuspended Fe-rich sediments, which are both naturally occurring and derived from historic mining, become the dominant diffuse source of Fe in the water column. 相似文献
494.
Yang H Xing Y Xie P Ni L Rong K 《Environmental pollution (Barking, Essex : 1987)》2008,151(3):559-568
Although studies on carbon burial in lake sediments have shown that lakes are disproportionately important carbon sinks, many studies on gaseous carbon exchange across the water-air interface have demonstrated that lakes are supersaturated with CO(2) and CH(4) causing a net release of CO(2) and CH(4) to the atmosphere. In order to more accurately estimate the net carbon source/sink function of lake ecosystems, a more comprehensive carbon budget is needed, especially for gaseous carbon exchange across the water-air interface. Using two methods, overall mass balance and gas exchange and carbon burial balance, we assessed the carbon source/sink function of Lake Donghu, a subtropical, eutrophic lake, from April 2003 to March 2004. With the overall mass balance calculations, total carbon input was 14 905 t, total carbon output was 4950 t, and net carbon budget was +9955 t, suggesting that Lake Donghu was a great carbon sink. For the gas exchange and carbon burial balance, gaseous carbon (CO(2) and CH(4)) emission across the water-air interface totaled 752 t while carbon burial in the lake sediment was 9477 t. The ratio of carbon emission into the atmosphere to carbon burial into the sediment was only 0.08. This low ratio indicates that Lake Donghu is a great carbon sink. Results showed good agreement between the two methods with both showing Lake Donghu to be a great carbon sink. This results from the high primary production of Lake Donghu, substantive allochthonous carbon inputs and intensive anthropogenic activity. Gaseous carbon emission accounted for about 15% of the total carbon output, indicating that the total output would be underestimated without including gaseous carbon exchange. 相似文献
495.
Abu-Allaban M Gillies JA Gertler AW Clayton R Proffitt D 《Environmental monitoring and assessment》2007,132(1-3):155-163
A source apportionment study was carried out to estimate the contribution of motor vehicles to ambient particulate matter
(PM) in selected urban areas in the USA. Measurements were performed at seven locations during the period September 7, 2000
through March 9, 2001. Measurements included integrated PM2.5 and PM10 concentrations and polycyclic aromatic hydrocarbons (PAHs). Ambient PM2.5 and PM10 were apportioned to their local sources using the chemical mass balance (CMB) receptor model and compared with results obtained
using scanning electron microscopy (SEM). Results indicate that PM2.5 components were mainly from combustion sources, including motor vehicles, and secondary species (nitrates and sulfates).
PM10 consisted mainly of geological material, in addition to emissions from combustion sources. The fractional contributions of
motor vehicles to ambient PM were estimated to be in the range from 20 to 76% and from 35 to 92% for PM2.5 and PM10, respectively. 相似文献
496.
Precipitation chemistry programs in different regions of the world have different quality control limits for ion balance parameter
IPD in wet deposition monitoring (R). The range of R values was calculated by assuming sample rainwater models in this paper. It was found that R was influenced by the inorganic ion types, total ion concentrations (IS) and the accuracy of the measurements (a
i
). R was defined and calculated as a function of a
i
and ion concentration C
i
. R values of different types of wet deposition (including ocean type, continent type and combined oceanic and continental deposition)
were different. There were also differences between the samples of the same type if the samples had different total ion concentrations.
When IS>100 μeq/L, the ranges of R of ocean type deposition, continent type deposition and combined oceanic and continental deposition were 5∼7%, 5∼9% and 5∼11%,
respectively. When IS<50 μeq/L, if a
i
was 100%, the range of R was 33∼71% because of the lower accuracy. It was also found that R of each criterion was in the range of R as calculated in this paper when IS≥50 μeq/L, but when IS<50 μeq/L, the criteria varied greatly in their R values. 相似文献
497.
Landfill leachates usually need to be treated before discharged, and using soil-plant systems for this has gained substantial interest in Sweden and in the UK. A three-year field study was conducted in central Sweden to quantify plant response, treatment efficiency and impact on groundwater quality of landfill leachate irrigation of short-rotation willow coppice (Salix). Two willow varieties were tested and four irrigation regimes in sixteen 400-m2 plots. The willow plants did not react negatively, despite very high annual loads of nitrogen (≤2160 kg N/ha), chloride (≤8600 kg Cl/ha) and other elements. Mean annual growth was 1.5, 9.8 and 12.6 tonnes DM/ha during years 1-3. For one of two willow varieties tested, relative leaf length accurately predicted growth rate. Irrigation resulted in elevated groundwater concentrations of all elements applied. Treatment efficiency varied considerably for different elements, but was adequate when moderate loads were applied. 相似文献
498.
Estimation of Nitrogen and Phosphorus in Effluent from the Striped Catfish Farming Sector in the Mekong Delta,Vietnam 总被引:1,自引:0,他引:1
In this study an attempt is made to estimate nitrogen and phosphorus discharged to the environment from the striped catfish
(Pangasianodon hypophthalmus) farming sector in the Mekong Delta (8°33′–10°55′N, 104°30′–106°50′E), South Vietnam. The sector accounted for 687,000 t
production in 2007 and 1,094,879 t in 2008, with over 95% of the produce destined for export to over 100 countries. Commercial
and farm-made feeds are used in catfish farming, currently the former being more predominant. Nitrogen discharge levels were
similar for commercial feeds (median 46.0 kg/t fish) and farm-made feeds (median 46.8 kg/t fish); whilst, phosphorus discharge
levels for commercial feeds (median 14.4 kg/t fish) were considerably lower than for farm-made feeds (median 18.4 kg/t fish).
Based on the median nutrient discharge levels for commercial feeds, striped catfish production in the Mekong Delta discharged
31,602 t N and 9,893 t P, and 50,364 t N and 15,766 t P in 2007 and 2008, respectively. However, the amount of nutrients returned
directly to the Mekong River may be substantially less than this as a significant proportion of the water used for catfish
farming as well as the sludge is diverted to other agricultural farming systems. Striped catfish farming in the Mekong Delta
compared favourably with other cultured species, irrespective of the type of feed used, when the total amounts of N and P
discharged in the production of a tonne of production was estimated. 相似文献
499.
A.M. Thompson T. Wilson J.M. Norman A.L. Gemechu A. Roa‐Espinosa 《Journal of the American Water Resources Association》2008,44(6):1548-1563
Abstract: The summertime heating of runoff in urban areas is recognized as a common and consistent urban climatological phenomenon. In this study, a simple thermal urban runoff model (TURM) is presented for the net energy flux at the impervious surfaces of urban areas to account for the heat transferred to runoff. The first step in developing TURM consists of calculating the various factors that control how urban impervious areas absorb heat and transfer it to moving water on the surface. The runoff temperature is determined based on the interactions of the physical characteristics of the impervious areas, the weather, and the heat transfer between the moving film of runoff and the impervious surface common in urban areas. Key surface and weather factors that affect runoff temperature predictions are type of impervious surface, air temperature, humidity, solar radiation before and during rain, rainfall intensity, and rainfall temperature. Runoff from pervious areas is considered separately and estimated using the Green‐Ampt Mein‐Larson rainfall excess method. Pervious runoff temperature is estimated as the rainfall temperature. Field measurements indicate that wet bulb temperature can be used as a surrogate for rainfall temperature and that runoff temperatures from sod average just 2°C higher than rainfall temperatures. Differences between measured and predicted impervious runoff temperature average approximately 2°C, indicating that TURM is a useful tool for determining runoff temperatures for typical urban areas. 相似文献
500.
The photodegradation of persistent and bioaccumulative perftuorooctanoic acid (PFOA) in water by 185 nm vacuum ultraviolet (VUV) light was examined to develop an effective technology to deal with PFOA pollution. PFOA degraded very slowly under irradiation of 254 nm UV light. However, 61.7% of initial PFOA was degraded by 185 nm VUV light within 2 h, and defluorination ratio reached 17.1%. Pseudo first-order-kinetics well simulated its degradation and defluorination. Besides, fluoride ion formed in water, 4 shorter-chain perfluorinated carboxylic acids (PFCAs), that is, perfluoroheptanoic acid, perfluorohexanoic acid, perfluoropentanoic acid, and perfluorobutanoic acid. These were identified as intermediates by LC-MS measurement. These PFCAs consecutively formed and further degraded with irradiation time. According to the mass balance calculation, no other byproducts were formed. It was proposed that PFCAs initially are decarboxylated by 185 nm light, and the radical thus formed reacts with water to form shorter-chain PFCA with one less CF2 unit. 相似文献