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1.
太湖水龄分布特征及“引江济太”工程对其的影响 总被引：1，自引：5，他引：1
太湖作为典型的风生流湖泊,风场对水体运输和交换的过程起着重要的作用.基于环境水动力学模型EFDC源程序建立了染色剂模型以及水龄模型,借助水龄研究太湖水体的长期输运过程和更新速率特征,从而为太湖的调水工程管理提供科学依据.本文在研究春、夏、秋、冬季不同风场作用下太湖的水龄季节性分布特征的基础上,结合太湖实测风速、流量数据及"引江济太"工程调水运行的现状,着重分析了望虞河枢纽调水运行以及新沟河工程对太湖水龄分布的影响.数值试验的模拟结果表明:太湖水体交换受季风影响明显,春、夏季的水龄相对较大、水体交换较差;靠近湖流入口处的地方水龄较小,远离入口的地方水龄较大;水流流向与风向一致时水龄减小,水循环加快,反之则减慢.望虞河引水引工程能够减小贡湖及湖心区的水龄,加快贡湖湖区及湖心区的水循环;新沟河工程引水能够减小梅梁湖区的水龄,改善该湖区的水质.引水工程的实施对加快整个太湖的水循环做出重要贡献. 相似文献
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Ships carry ballast water for better stability and to control trim. However, the discharge of ballast water near ports is known to transport invasive species from one coastal area to another. The exchange of ballast water on the high seas is supposed to reduce such invasions of exotic species. In this study, we used denaturing gradient gel electrophoresis (DGGE) to analyze the composition of the bacterial community in ballast water before and after such a mid-ocean exchange, and we also measured total bacterial counts. Our findings confirmed that the ballast water was replaced by the mid-ocean exchange, as indicated by the marked change in the composition of the bacterial community. There was also a significant decrease in bacterial abundance after the mid-ocean exchange. Finally, our findings support the incubation hypothesis, because the composition of the bacterial communities changed over time within the same ballast water. 相似文献
4.
Hyporheic exchange induced by dunes is a key process controlling water fluxes and biogeochemical processes in river networks. Owing to the limitations of instrumental detection at small spatial scales, previous studies have focused mainly on dune-induced hyporheic exchange in homogeneous systems. A low-permeability lens is a natural, widespread heterogeneity in stream beds, and probably affects the processes of water flow and contaminant transportation significantly. To quantitatively analyse the response mechanism of hyporheic exchange to a low-permeability lens, a two-dimensional dune-generated hyporheic exchange model was developed using the VS2DH model. The results indicate a lens in a stream bed can hinder or enhance hyporheic exchange processes, depending on its relative spatial location to dunes. Both the increase in length and thickness of the lens could strengthen its impacts on hyporheic exchange. Regional groundwater–surface water interactions of higher intensity suppress the flow of hyporheic exchange in a stream bed with a low-permeability lens. 相似文献
5.
Water–rock–gas system is simulated using a technique based on the fundamental principles of modern hydrogeochemistry regarding the formation parameters of natural-water chemistry to show that groundwater pollution hazard at a gold-bearing placer is acute for any site of water exchange changing from passive to active. Under passive water exchange, the products of sulfide oxidation are accumulated; whereas under active water exchange, the oxidation products are leached out to form acid drainage flows. The treatment of acid drainage water and the neutralization of acid solutions are more effective under reduction or weakly alkaline conditions. 相似文献
6.
The formation conditions of water exchange and quality in a lake used as a part of water disposal system of an operating copper-nickel metallurgical plant are considered. Water and material budget of the lake is calculated, including process water discharge, atmospheric precipitation, and snow melting. The quantitative and qualitative characteristics of bottom sediments and waters involved in lake water exchange are determined. The migration conditions of heavy metals from bottom sediments are evaluated and their dynamic layers are determined. Some measures are proposed for reducing the adverse impact of the coppernickel plant on water bodies. 相似文献
7.
“引江济淮”工程对安徽菜子湖水龄分布的影响 总被引：2，自引：1，他引：1
菜子湖是"引江济淮"工程的重要输水通道,其水体输运和物质交换将因输水工程发生改变.本文基于环境流体水动力学模型（EFDC）建立了菜子湖水龄模型,在将模型与实测水文数据验证满足精度的前提下,设计14种方案计算菜子湖在季风影响下的水龄,工程实施期间菜子湖在丰、平、枯季的水龄与流场,以及枯水季调水情景下同风速8种风向和强风向3种风速时的水龄.数值试验的模拟结果表明：菜子湖湖体水龄分布具有时空差异性,无风条件下,春、夏、秋、冬季的湖体的平均水龄分别为120.93、33.19、92.92、101.48 d,而在季风影响下,春、夏、秋、冬季平均水龄分别为75.23、32.45、81.80、66.16 d;西部L2湖水龄较长,东部L1湖和南部L3湖水龄较短;输水工程将改变L1和L3湖的流场,对L2湖流场几乎无影响;输水工程实施后,菜子湖水龄分布主要受风场及输水影响,不同风向对菜子湖各湖区影响不同,西南风有助于L1湖水体交换,北风有助于L2湖水体交换,东风有助于L3湖水体交换,而当风向为东北风时,3个湖区水龄均较小;枯水季调水有利于L1湖和L3湖水体交换,但对L2湖水体交换作用不明显. 相似文献
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Meteorological conditions, biochemical processes in water bodies and anthropogenic pressure of a region are the main factors to determine the atmosphere water-body gas exchange. Research on oxygen outflows in the Dnjepr estuary region has shown that though gas exchange with atmosphere permanently exists its intensity varies throughout a day, vegetation period, year. The process of evasion is the most active in the flood plain pools of the river. Oxygen exchange between the atmosphere and a river is to be determined with physical characteristics of water outflow and with the anthropogenic influence. Oxygen absorption from the atmosphere is dominating for the liman water area in spite of differences between its parts. The obtained results have shown that gas exchange between river estuary pools and the atmosphere is of great importance for the oxygen balance of these pools. 相似文献
9.
Changes in zooplankton abundance and diversity after ballast water exchange in regional seas 总被引：2，自引：0，他引：2
A study of the efficiency of ballast water exchange (BWE) in regional seas was carried out to assess this management method in reducing the risk of introducing non-native species. Zooplankton samples were taken before and after exchange on ten voyages where BWE took place (North Sea, English Channel, Irish Sea and Bay of Biscay). Zooplankton abundance was always reduced after exchange, but diversity increased on eight occasions. The greatest changes occurred when the source port water was of low salinity and when exchange took place in deeper waters further from land. However, it was clear that BWE did not remove all the source port taxa and this method is unlikely to provide a consistent and effective method of managing ballast water in regional seas. 相似文献
10.
The following possible techniques of nitrate removal from drinking water are compared with respect to their efficiency: reserved osmosis, electrodialysis and ion exchange. It can be shown by test products that it is possible, in principle, to synthesize nitrate-selective anion exchange resins. Today it is assumed that from this a preferential position of the technology of ion exchange can be expected for the elimination of nitrate from drinking water. 相似文献
11.
Stream–subsurface water interaction induced by natural riffles and constructed riffles/steps was examined in lowland streams in southern Ontario, Canada. The penetration of stream water into the subsurface was analysed using hydrometric data, and the zone of > 10% stream water was calculated from a chemical mixing equation using tracer injection of bromide and background chloride concentrations. The constructed riffles studied induced more extensive hyporheic exchange than the natural riffles because of their steeper longitudinal hydraulic head gradients and coarser streambed sediments. The depth of > 10% stream water zone in a small and a large constructed riffle extended to > 0·2 m and > 1·4 m depths respectively. Flux and residence time distribution of hyporheic exchange were simulated in constructed riffles using MODFLOW, a finite‐difference groundwater flow model. Hyporheic flux and residence time distribution varied along the riffles, and the exchange occurring upstream from the riffle crest was small in flux and had a long residence time. In contrast, hyporheic exchange occurring downstream from the riffle crest had a relatively short residence time and accounted for 83% and 70% of total hyporheic exchange flow in a small and large riffle respectively. Although stream restoration projects have not considered the hyporheic zone, our data indicate that constructed riffles and steps can promote vertical hydrologic exchange and increase the groundwater–surface water linkage in degraded lowland streams. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
12.
A review of the study of water exchange processes in Lake Baikal is given. The major attention is given to the mathematical simulation of the processes of density stratification processes and the effect of different hydrophysical factors on water exchange processes, in particular, the formation of thermobar and vertical circulations in the lake. 相似文献
13.
多环芳烃在城市湖泊气-水界面上的交换 总被引：4，自引：1，他引：3
利用大流量采样器和半渗透膜装置对广州麓湖大气中气态多环芳烃和水体中溶解态多环芳烃进行了连续一年的观测,在此数据基础上,依据国内外通用的双膜理论计算了多环芳烃在广州麓湖水面上的交换通量.结果显示萘、苊、二氢苊的交换通量方向是由湖水挥发进入大气,其它主要化合物都是从大气进入水体;在单个化合物的交换通量中,以菲的通量值为最大,平均达13137.1ng/(m2·d),最高达到21211.22ng/(m2·d),其次为萘、荧蒽、蒽、芘、芴、二氢苊和苊等.各化合物交换通量的季节变化特点大部分都是在夏季达到最大值,在冬季交换通量降到最小值,但唯一例外的是芴,其交换通量却是在夏季降到最低值. 相似文献
14.
目前大量景观类湖泊在人工布局下呈现形状不规整的特点,容易造成湖湾水体滞留形成死水区,水质恶化问题日益突出,本文以星湖为研究区域,建立基于环境流体生态动力学(EFDC)模型的星湖水动力—风场耦合模型,以水龄作为衡量水体交换速率的指标,设计12种工况模拟计算不同出入湖通道布局及流量配比、"引江济星"工程和风场对星湖水龄时空分布的影响.结果表明:星湖水龄存在季节性和空间性分布差异,春季主导风向与湖体流动主方向互斥,抑制了波海湖水体交换,导致水龄在春季较长,而秋季南西南季风促进中心湖等水体交换,致使水龄偏短,也反映出风向的影响存在湖区空间异质性,风向为南东南时星湖整体水龄最小;入湖口通道布局及流量配比对湖区水体交换速率存在影响,以外坑为波海湖入湖口且波海湖、中心湖、仙女湖入流比为4∶3∶3时,星湖整体水龄最小,拟建的青莲湖出水口和仙女湖出水口能有效加快青莲湖东北部和仙女湖东南部的水体交换速率;综合考虑调水引流效益、经济投资、生态开发和占地的成本,方案二为最优调水引流方案.本研究强调入湖口布局、流量大小和比例、及风场等因素对城市内湖水体置换的影响,为人为干扰下的景观湖泊的治理和管控提供科学支撑. 相似文献
15.
This study investigates the Stratosphere-Troposphere Exchange(STE) of water vapor,emphasizes its interdecadal variations over Asia in boreal summer,and discusses the influences of atmospheric heat sources over the Tibetan Plateau and the tropical western North Pacific(WNP) on them by using the Wei method with reanalysis data from the European Centre for Medium-Range Weather Forecasts(ECMWF) for the years of 1958-2001.The climatology shows that the upward transport of water vapor across the tropopause in boreal summer is the most robust over the joining area of the South Asian Peninsula and Indian-Pacific Oceans(defined as AIPO).The upward transport over there can persistently convey the abundant water vapor into the stratosphere and then influence the distribution and variation of the stratospheric water vapor.The analysis shows that interdecadal variations of the water vapor exchange over the AIPO are significant,and its abrupt change occurred in the mid-1970s and the early 1990s.In these three periods,as important channels of the water vapor exchange,the effect of Bay of Bengal-East Asia as well as South China Sea was gradually weakening,while the role of the WNP becomes more and more important.Further studies show that atmospheric heat sources over the Tibetan Plateau and the WNP are two main factors in determining the interdecadal variations of water vapor exchange.The thermal influences over the Tibetan Plateau and the WNP have been greatly adjusted over the pass 44 years.Their synthesis influences the interdecadal variations of the water vapor exchange by changing the Asian summer monsoon,but their roles vary with time and regions.Especially after 1992,the influence of heat source over the Tibetan Plateau remarkably weakens,while the heat source over the WNP dominates the across-tropopause water vapor exchange.Results have important implications for understanding the transport of other components in the atmosphere and estimating the impact of human activities(emission) on global climate. 相似文献
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Commonly measured water quality parameters were compared to heat as tracers of stream water exchange with ground water. Temperature, specific conductance, and chloride were sampled at various frequencies in the stream and adjacent wells over a 2-year period. Strong seasonal variations in stream water were observed for temperature and specific conductance. In observation wells where the temperature response correlated to stream water, chloride and specific conductance values were similar to stream water values as well, indicating significant stream water exchange with ground water. At sites where ground water temperature fluctuations were negligible, chloride and/or specific conductance values did not correlate to stream water values, indicating that ground water was not significantly influenced by exchange with stream water. Best-fit simulation modeling was performed at two sites to derive temperature-based estimates of hydraulic conductivities of the alluvial sediments between the stream and wells. These estimates were used in solute transport simulations for a comparison of measured and simulated values for chloride and specific conductance. Simulation results showed that hydraulic conductivities vary seasonally and annually. This variability was a result of seasonal changes in temperature-dependent hydraulic conductivity and scouring or clogging of the streambed. Specific conductance fits were good, while chloride data were difficult to fit due to the infrequent (quarterly) stream water chloride measurements during the study period. Combined analyses of temperature, chloride, and specific conductance led to improved quantification of the spatial and temporal variability of stream water exchange with shallow ground water in an alluvial system. 相似文献
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A water balance approach for quantifying subsurface exchange fluxes and associated errors in hill reservoirs in semiarid regions 
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下载免费PDF全文 Hill reservoirs are rain water‐harvesting structures that have been increasingly adopted in arid and semi‐arid regions, such as North Africa, to capture and conserve runoff water and for use as alternative water resources in agricultural development. Currently, process‐based information on reservoir hydrology is needed to improve reservoir management practices. The study aims to develop an approach to estimate the reservoir–subsurface exchange flux and its associated error at the annual, monthly, and intra‐monthly time scales to better understand the hydrological functioning and dynamics of hill reservoirs. This approach is based on a hydrological water balance of the hill reservoir by considering all water input and output fluxes and their associated errors. The results demonstrate the ability and relevance of the approach in estimating the net reservoir–subsurface exchange flux and its error estimations at various time scales. Its application on the Kamech catchment (Northern Tunisia) for the 2009–2012 period demonstrates that the net reservoir–subsurface exchange flux is positive, i.e. the infiltration from the hill reservoir to the aquifer dominates over the discharge from the aquifer to the reservoir. Moreover, reservoir–subsurface exchange constitutes the main output component in the water balance. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
18.
不同溶解氧水平下湖泊底泥-水界面磷交换影响因素分析 总被引：15，自引：2，他引：13
在实验室控制条件下,研究了玄武湖底泥在饱和溶解氧、75%、50%、25%、0%溶解氧水平下底泥-水界面磷交换,探讨了溶解氧对底泥-水界面磷交换的影响途径.结果表明:(1)上覆水溶解氧与玄武湖底泥溶解性磷酸盐、溶解性总磷释放速率呈开口向上的抛物线关系;(2)上覆水溶解氧水平可以决定磷在底泥-水界面交换中的转换方向,而且还影响间隙水中溶解氧扩散深度,25%、50%、75%和饱和溶解氧水平下溶解氧最大扩散深度分别为0.974cm、1.377cm、1.687cm和1.948cm,溶解氧在间隙水中最大扩散深度影响底泥-水界面的磷交换;(3)溶解氧可通过影响底泥-水界面处电位、藻类聚磷作用以及pH来影响底泥-水界面的磷交换. 相似文献
19.
Vertical exchange due to horizontal density gradients in lakes; the case of Lake Lucerne 总被引：1，自引：1，他引：0
David C. van Senden Robert Portielje Alex Borer Heinz Ambühl Dieter M. Imboden 《Aquatic Sciences - Research Across Boundaries》1990,52(4):381-398
Recent field investigations have shown that differential mixing causes a significant density driven exchange between the two eastern basins of Lake Lucerne, Gersauersee and Urnersee. The long term vertical mixing characteristics during the winter mixing period and the influence of the resulting exchange flow on water quality are examined through the analysis of ten years (1964 to 1974) of monthly limnological data. Vertical homogenization of the state variables (temperature, electric conductivity and density) occurred on average once every two years in Urnersee, but not once in Gersauersee where the ten year average winter mixed-layer depth extended to 120 m. In Urnersee intense mixing was evident over the whole water column for every year. In contrast intense mixing in the deeper layers of Gersauersee occurred approximately once every four years. A three layer model shows that theT/
20 signature of the Gersauersee intermediate water correlates best with the Urnersee deep water confirming the regular occurrence of a density driven exchange. For the lower layers the oxygen consumption rate in Urnersee was approximately twice that for Gersauersee. It appears the exchange flow can act either as a source or sink for the oxygen balance of Urnersee deep water. The larger rate in Urnersee hypolimnion might also be associated with the larger sediment input to this system. Density driven exchange resulting from differential mixing is probably an important contribution to the vertical water replenishment in many lakes. 相似文献
20.
The interaction between surface and subsurface water has a crucial influence on the biochemistry of stream environments. Even though the river discharge and the flow conditions can seldom be considered to be steady, the influence of this unsteadiness on the hyporheic exchange has often been neglected. In this work, a model for the study of hyporheic exchange during unsteady conditions has been developed. The model provides a sound analytical framework for the analysis of the effects of a varying stream discharge on the exchange between a stream and the hyporheic zone. The effects of the unsteadiness on the water exchange flux, the residence time of the solutes in the bed, and the stored mass are quantified. A synthetic example shows the substantial influence of a flood on the hyporheic exchange, and that the application of a steady model can lead to an underestimation of the exchanged mass, even after the flood has ended. 相似文献