Analysis of the exchange of groundwater and river water by using Radon-222 in the middle Heihe Basin of northwestern China   总被引：9，自引：1，他引：8  

Y.?WuEmail author  X.?Wen  Y.?Zhang 《Environmental Geology》2004,45(5):647-653

In arid regions of western China, water resources come from mountain watersheds and disappear in the desert plain. The exchange of surface water and groundwater takes place two or three times in a basin. It is essential to analyze the interaction of groundwater with surface water to use water resources effectively and predict the change in the water environment. The conventional method of analysis, however, measures only the flow of a stream and cannot determine groundwater seepage accurately. As the concentration of Radon-222 (²²²Rn) in groundwater is much higher than in surface water, the use of ²²²Rn was examined as an indicator for the analysis of the interaction between surface water and groundwater. Measurement of the ²²²Rn concentration in surface water was conducted to detect groundwater seepage into a stream in the middle Heihe Basin of northwestern China. Furthermore, the simultaneous groundwater flow into and out of a stream from the aquifers was quantified by solving the ²²²Rn mass balance equation, in which the losses of gas exchange and radioactive decay of ²²²Rn are considered. Meanwhile, river runoff was gauged to determine the exchange rates between surface water and groundwater. The result shows that ²²²Rn isotope can be used as a good environmental tracer with high sensitivity for the interaction between surface water and groundwater, especially in the fractured aquifer system, karst aquifer system and discharge basins.  相似文献   

Impact of Mining Activities upon Environment in Panzhihua Region, Southwestern China     

TENGY~  NIS~  WANG J~  ZHANG C~ XU Z~  TUO X~ 《地球科学进展》2004,(Z1)

Mining activities have left huge uncovered slopes, large areas of gangue ground and extensive railings dams. In this paper, we studied some impacts of mining activities upon environment in Panzhihua region, southwestern China. The environmental impacts include ecological destruction, geological disasters, environmental pollution, land damage, solid waste and occupational health effect in study area. The author suggested that local government should take some measure to reduce environmental impact in Panzhihua City. First, the countermeasure of reducing environmental impact is to set up ecological rehabilitation and environmental management system, which ensure the sustainable development of resources, environment, economy and society in this region. Second, the area needs to be monitored regularly for trace metal and other pollutants to forewarn urban eco-environmental safety.  相似文献   

A numerical method of moments for solute transport in physically and chemically nonstationary formations: linear equilibrium sorption with random K<Subscript>d</Subscript>     

B. X.?HuEmail author  J.?Wu  D.?Zhang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2004,18(1):22-30

A Lagrangian perturbation method is applied to develop a method of moments for solute flux through a three-dimensional nonstationary flow field. The flow nonstationarity stems from medium nonstationarity and internal and external boundaries of the study domain. The solute flux is described as a space-time process where time refers to the solute flux breakthrough through a control plane (CP) at some distance downstream of the solute source and space refers to the transverse displacement distribution at the CP. The analytically derived moment equations for solute transport in a nonstationarity flow field are too complicated to solve analytically, a numerical finite difference method is implemented to obtain the solutions. This approach combines the stochastic model with the flexibility of the numerical method to boundary and initial conditions. The developed method is applied to study the effects of heterogeneity and nonstationarity of the hydraulic conductivity and chemical sorption coefficient on solute transport. The study results indicate all these factors will significantly influence the mean and variance of solute flux.  相似文献   

Properties and limitations of sequential indicator simulation   总被引：2，自引：0，他引：2  

X.?EmeryEmail author 《Stochastic Environmental Research and Risk Assessment (SERRA)》2004,18(6):414-424

The sequential indicator algorithm is a widespread geostatistical simulation technique that relies on indicator (co)kriging and is applicable to a wide range of datasets. However, such algorithm comes up against several limitations that are often misunderstood. This work aims at highlighting these limitations, by examining what are the conditions for the realizations to reproduce the input parameters (indicator means and correlograms) and what happens with the other parameters (other two-point or multiple-point statistics). Several types of random functions are contemplated, namely: the mosaic model, random sets, models defined by multiple indicators and isofactorial models. In each case, the conditions for the sequential algorithm to honor the model parameters are sought after. Concurrently, the properties of the multivariate distributions are identified and some conceptual impediments are emphasized. In particular, the prior multiple-point statistics are shown to depend on external factors such as the total number of simulated nodes and the number and locations of the samples. As a consequence, common applications such as a flow simulation or a change of support on the realizations may lead to hazardous interpretations.  相似文献   

Über röhrenförmige Lösungserscheinungen im Kalke bei Amt-Mitterbach bei St. ägyd am Neuwalde,Niederösterreich     

Franz X. Schaffer 《International Journal of Earth Sciences》1932,23(5):276-278

Ohne Zusammenfassung  相似文献   

Anthropogenic vs. lithogenic origins of trace elements (As, Cd, Pb, Rb, Sb, Sc, Sn, Zn) in water column particles: northwestern Mediterranean Sea   总被引：1，自引：0，他引：1  

F. E. Grousset  C. R. Quetel  B. Thomas  O. F. X. Donard  C. E. Lambert  F. Guillard  A. Monaco 《Marine Chemistry》1995,48(3-4)

The distribution of heavy metal was analyzed in water column particles collected in autumn (October 1985) and spring (March 1986) by two series of sediment traps from a mooring located in the northeastern Mediterranean Sea continental slope. Four traps were set, at 50, 100, 300, 600 m depths on the mooring in 645 m deep water in the Lacaze-Duthier canyon. The total metal concentrations were determined by ICP-MS. Results show that Rb and Sc contents display typical shale values. As, Cd, Pb, Sb, Zn (normalized to Sc) display high enrichment factors (up to 50) over shale compositions. Distinctive temporal variability as well as the respective contributions of local (Têt, Aude) and remote (Rhône) rivers and Sahara-derived aerosols have been identified. Fluxes of most elements observed in the upper 100 m can be attributed to atmospheric fluxes. In the deepest traps (300 and 600 m) these fluxes are, however, mostly dominated by riverine particles advected from the continental shelf. Most of the trace-element enrichments are more likely to be related to the anthropogenic input rather than to biological cycling. Isotopic composition of lead determined by ICP-MS enabled to evaluate that the proportion of anthropogenic lead derived from European gasoline consumption ranged between 50 and 100%.  相似文献   

Dissolved Cd behaviour in some selected french and chinese estuaries. Consequences on Cd supply to the ocean     

F. Elbaz-Poulichet  J.M. Martin  W.W. Huang  J.X. Zhu 《Marine Chemistry》1987,22(2-4)

Few data on dissolved trace metals in rivers and estuaries are presently available. This paper is an attempt to provide additional data on dissolved concentrations obtained in polluted and so-called unpolluted river estuarine systems. Data for two major French rivers (Gironde, Rhône) have been compared with the Chinese Yellow River (Huanghe) and Yangtze River (Changjiang). Dissolved Cd concentrations have been measured by differential pulse anodic stripping voltammetry. Average concentrations range from 15 ng kg⁻¹ to 50 ng kg⁻¹ (0.13–0.45 nmol kg⁻¹) in the French rivers and are below 4 ng kg⁻¹ (0.040 nmol kg⁻¹) in the Chinese rivers.In all the estuaries studied the dissolved Cd concentrations depict a systematic bulge in the mixing zone which is attributed largely to remobilization processes from particulate matter when the chlorinity increases. Other parameters that may also play a significant role for remobilization are discussed. The processes concerned lead us to reassess the net Cd river input to the oceans, and this should be taken into account for a more precise evaluation of the residence time of oceanic Cd.  相似文献   

A note on non-linear hydrodynamic forces on a body submerged below a free surface     

G.X. Wu 《Applied Ocean Research》1993,15(6):371-372

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Dike distribution in the Oman-United Arab Emirates ophiolite     

Nicolas  A.  Ildefonse  B.  Boudier  F.  Lenoir  X.  Ben Ismail  W. 《Marine Geophysical Researches》2000,21(3-4):269-287

Mafic dikes and dunite veins are observed in the mantle section of the Oman – United Arab Emirates (O-UAE) ophiolites, as well as diabase dikes and hydrothermal veins in the crust section. They have been systematically measured during the mapping of this ophiolite and are represented by their trajectories in the folded map 3 in the back of this volume, and by local stereoplots included in this study. Mafic dikes in the mantle section correspond to basaltic melt being injected at decreasing temperatures from above or at peridotite solidus, down to below 450°C. Hydrothermal veins associated with dioritic dikes issued from hydrous melting of host gabbros are observed down to the base of the crust, bearing evidence for sea water penetration into basal gabbros at or above 900°C, that is very close to the ridge axis. Dike orientations record the stress field at the time of their injection. In most places, all types of dikes are dominantly parallel to the general trend of the nearest sheeted dike complex; thus the stress field has not visibly changed from melt injection in the asthenosphere below the ridge of origin to injection in a lithosphere up to a few Myr old, at distances beyond 100 km from the axis. Local preferred orientations, when they are considered in the frame of the paleo-ridge system of O-UAE, result in a coherent model throughout the belt: the sheeted dike complex dips moderately away from the presumed ridge axis and the mantle dikes, toward this axis. These opposite directions are explained by the presumed effect of subsidence toward the axis for the sheeted dikes and by the central feeding from an asthenospheric uprise for the mantle dikes.  相似文献   

Current status of mobile and static sampling gears used in resource surveys     

Reid  David G.; Annala  John; Rosen  Shale; Pol  Mike; Cadrin  Steve X.; Walsh  Stephen J. 《ICES Journal of Marine Science》2007,64(8):1607-1609

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