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1.
As a rule, the hydrodynamic modeling of processes in fresh waters is performed with the use of potential temperature θ and potential density ρ*. However, the formulae of potential temperature for natural waters given by Phillips (1977), Gill (1982) and others take into account only adiabatic correction. They do not consider such important characteristics of natural waters as temperature of maximal density Tmd (S,P) remoting of real temperatures T(S,P) in situ from Tmd (T -Tmd), changes of Tmd with decreasing of pressure P (depth Z), and the equation of water state. Tmd=Tmd(P) is the property of molecular structures of water (Horne, 1969). It is determined by the equation of water state:for example, for lacustrine waters in the form of Chen, Millero, (1986) ρ=ρ(S,T,P), where ρ,S are density and salinity natural water. There is given and discussed a new formula for the calculation of potential temperature. It is established that potential densities calculated according to the new formula suggested by us show the entire thermodynamic similarity of characteristics within T in situ. It is not observed while using the old formulae. 相似文献
2.
Lake Gucheng is located in the southeast of Nanjing, with an area of 24.3 km2, an average depth of 2 meters. The macrophytes of the lake were used to be abundant and their biomass was about 4.96 mg·m-2. The annual average contents of total phosphorus (TP), total nitrogen (TN), PO3- -P, CODMn and BOD5 0.03, 1.31, 0.005, 3.61 and 1.46 mg·L-1, respectively. Thus, the water quality of this lake is quite well. Recently, the water quality in pari of the lake became worse because of some unreasonable exploitation and utilization of bioresources. The interactions between phytoplankton (N1), macrophyte (N2), fish (N3), crab (N4) were studied here. The macrophyte has great influences on both phytoplanktons, fish and crab, controlling the water quality and maintaining the fishery productivity. On the other hand, the phytoplankton, fish and crab also influence the macrophyte. It is key method of ecological management to maintain the macrophyte by fishery culture. Therefore, a modified Lotka-Volterra model has been established to estimate the interaction between N1, N2, N3, N4 and the influences of some water environmental parameters on these aquatic organism, environmental and economic effect. The main model consists four compart-mental models and four submodels, involved 12 external variables, 8 state variables, 19 universal constants and 11 parameters. The values of most parameters were found from our experiments and calibrated by the model and actually measured data. The model has been validated by comparison the computed and experimental data of phytoplankton and macrophyte. The theoretical outputs showed a good agreement with the measured data. This model predicated that if the standing crop offish and crab was higher than 2.65 ·m-2 during springtime in this lake, macrophytes would not grow, chlorophyll a content would arrive 34.8 mg·m-3 and the water quality would decrease. If the macrophyte grow well, the maximum fishery productivity would be about 1 600 t. In this case, the annually averaged phytoplankton chlorophyll a content should be 3.69 mg·m-3, which is lower than the criterion (10 mg·m-3) for eutrophic state. From 1991 to 1996, Lake Gucheng was managed with this model, its water quality maintain quite well, chlorophyll a content decreased from 3.51 (1991) to 1.89 mg·m-3 (1994). Meanwhile, the fishery productivity increased and the economic effect heightened year by year. 相似文献
3.
Contrary to general international perception, Canada does not have an unlimited supply of freshwater. However, because Canada has a small population, it does have a generous water allocation on a per capita basis. Nor is Canada immune from water quality problems:its cold continental climate, urbanization and industrial activities all contribute to water quality concerns and deterioration. Generally, the authority to manage water in Canada is held by the country''s provincial governments. The Great Lakes basin is the world''s largest freshwater ecosystem and is located in Canada''s industrial heartland. Water issues, starting with phosphorus in the 1960''s, created international headlines. In the 1970''s toxics became the predominant issue and this led to the Great Lakes Water Quality Agreement which established the ecosystem approach to water quality management. This approach is now the standard approach to water quality management and has been successfully applied to a number of other lake and river ecosystems in Canada. While there have been improvements in the water quality of the Great Lakes much remains to be done on toxic elimination and the large contaminant stores in the sediments. Atmospheric deposition has become a significant source of chemicals from outside the basin The Canadian prairies, the agricultural heartland of Canada, is one major ecozone that has not been selected to have current and potential water quality problems examined by a federal government program. Both the quantity and quality of water in this region are potentially significant factors limiting economic diversification and sustainable development in this vast and ecologically disturbed region. 相似文献
4.
It have been measured the denitrification rates (DR) of sediment in Saginaw Bay, Lake Huron, by N2 production method. Triplicate samples of sediment core were collected at two GLERL long-term monitoring sites of the Bay in July and August of 1995. The DR are 48.81 -24.99 and 32.81-40.51 micromol N2 -2h-1 in the Inner and Outer regions of Saginaw Bay, respectively.The characters of DR in Saginaw Bay were studied also in this paper. The DR were influenced by the interactions between the Saginaw River as a main pollution source and the Lake Huron as a reservoir of high quality water. The impacts of zebra mussels (Dreissena Polymorpha) on denitrification in Saginaw Bay, Lake Huron, were discussed, Significant differences in NH4+ exchange fluxes were detected in the inner and outer bays. The molar ratios of N2:TIN were similar at both sampling sites. Measured DR were positively correlated to O2 consumption rates in the headspace. Additionally, a negative correlation between NH4+ and NO3- concentrations in the overlying water was found. 相似文献
5.
A model on a physico-biological engineering experiment for purifying water in Wulihu Bay of Lake Taihu by using Trapa natans var. bispinosa was constructed. The state variables in water in the physico-biological engineering were ammonium nitrogen (NH4+-N); nitrate nitrogen (NO3--N); nitrite nitrogen (NO2--N); phosphate phosphorus (PO43--P); dissolved oxygen (DO); nitrogen (N) and phosphorus (P) in detritus; biomass density, N and P in phytoplankton and in Trapa natans var. bispinosa, N and P in the substance adsorbed by the membrane of the engineering and the rootstocks of Trapa natans var. bispinosa. The state variables in bottom mud layer were PO43--P in the core water,exchangeable P and N. The external forcing functions were solar radiation, water temperature, NH4+-N; NO3--N; NO2--N; PO43--P; N and P in detritus; DO; phytoplankton concentrations in inflow water and the retention time of the water in physico-biological engineering channel. The main physical, chemical and biological processes considered in the model were:growth of Trapa natans var. bispinosa and phytoplankton; oxidation of NH4+-N and NO2--N, of detritus break down; N and P sorption by the enclosure cloth of the experimental engineering and by the rootstocks of Trapa natans var. bispinosa in water; reaeration of water; uptake of P, NH4+-N, NO3--N by phytoplankton and Trapa natans var. bispinosa:mortality of the phytoplankton and Trapa natans var. bispinosa:settling of detritus; and nutrient release from sediment. Comparison of calculated results and observed results showed that the model was constructed reasonably for the experiment. The mechanism of purifying lake water in the experiment engineering was discussed by the use of the model. 相似文献
6.
An avenue to integrate theoretical, experimental and field research methods to forecast water quality in water bodies for different scenarios of water management is proposed. Exploration of the laws of organization, stability and controllability of laboratory "ideal" water microbial communities (model ecosystems) is the basis to build the following biophysical research chain:to formalize with primary field information a conceptual block-diagram of a water ecosystem →to real chemical and other density-dependent and population-growth-controlling factors → to find our limiting factors for natural ecosystems → to conduct experiments with isolated chemical factors and hydrobionts to derive kinetic dependencies and quantitative parameters→ to transfer regularities of operation and kinetic dependencies to the natural ecosystem→ retrospective verification of the model on the base of available field and derived theoretical-experimental data →prognostic calculations for the scenario. Efficiency of the approach is demonstrated in microalgal "blooming" models for Krasnoyarsk and Kantat reservoirs and in prognostication of radioecological state of great Yenisei river:1) radionuclide distribution in the Yenisei''s bottom sediment is nonuniform-"spotty"; 2) it is theoretically shown, that due to biological interactions and tro-phical radioniclide migration there is "spotive" type of space radionuclide distribution. The research is to make use of the novel methods of ecological biophysics:Monitoring:spectral analysis of surface waters (algal pigments), fluorescent techniques to evaluate productivity and condition of algae; rapid bioassays for water toxicity (bioluminescence, chemotaxis techniques). Kinetic experiments:microcosms on evaluating self-purification rates; special cultivators to evaluate the rates of growth of hydrobionts and radioactive engulfing, nutrition spectra; methods of finding growth limiting factors. Models:application of Bellman Principle to optimizing the river water use; theory and peculiarities of microbiological decomposition of pollutants in the river ecosystem. The composition of Prognostication Simulation Model is the next:1) hydrodynamical unit to calculate 2-dimensional space-time rate of stream on any depth; 2) hydrophysical unit to calculate:water temperature and level of solar radiation inside the water body; 3) ecosystem unit to calculate dynamic of concentration of phytoplankton, zooplankton, bacteria, major chemical matters and pollutants in water, content pollutants inside of hydrobionfs cells and dynamic of bentos; 4) radioe-cological unit to forecast the dynamic of radionuclides in the water body and bottom, their hydro-bont''s concentration; 5) database. Reservoirs and river models are provided by monitoring and kinetic experiments data. 相似文献
7.
The water quality of Lake Taihu has declined markedly in the past two or three decades. We used modern non-parametric statistical methods to analyse the water quality record for 1989-1993 (samples collected at 2-monthly intervals). Phytoplankton blooms have been a particular problem, as the very high peak chlorophyll a concentrations in the Meiliang (up to 0.4 g·m-3) and the coastal regions (up to 0.5 g·m-3) indicate. However, over a large area of the middle of the lake, peak chlorophyll a concentrations were much lower (0.01-0.03 g·m-3). In this deeper, turbid part of the lake there may often be insufficient underwater light to support rapid phytoplankton growth; grazing by the abundant benthic bivalves may also be important. Total phosphorus (P) concentrations in the coastal waters increased significantly (p < 5%). Suspended solids concentrations also increased significantly, and as a result transparency decreased. However, phytoplankton probably usually only account for a small proportion of the suspended material, so the parallel increase in total P and suspended solids may be coincidental. Significant increases in chlorophyll a were not observed, but phytoplankton blooms are often short-lived (e.g. days to weeks), and thus may not always be detected by the 2-monthly sampling. 相似文献
8.
Tritium concentrations are used to trace water circulation in the Urumqi and Turfan basins in the Xinjiang, western China. Tritium analyses were made for 77 water samples of river waters, groundwaters, spring waters, lake waters and glacier ice collected in summers in 1992 and 1994. The tritium concentrations in the waters are in a wide range from 0 to 125 TU, most of which are considerably high compared with those of most waters in Japan, because tritium levels in precipitation in the area are over ten times as high as those in Japan. River waters originating in glacier regions contain melt glacier, the proportion of which is over 0.5 to river water. The mean resi-dence time of circulating meteoric water in the mountain regions is estimated to be about 15 years. Most groundwaters and spring waters in the flat regions are mainly derived from river waters originating in glacier regions. The groundwater of greatest tritium concentrations in wells in Urumqi City is derived from Urumqi River about 25 years ago. It takes several ten years for river water to pass the underground to many springs. Some groundwaters and spring waters have taken a long time more than 40 years to travel under the ground. Enrichment of tritium in lake water by evaporation is considered to estimate the contribution of groundwater flow to the recharge of lake. Various contributions of groundwater to lakes are inferred for the various type of salinity in closed or semi-closed lakes. The inflow rates of groundwater to salt lakes are small as against fresh water lakes. 相似文献
9.
In this paper, statistics are taken on the co-seismic response of underground fluid in Yunnan to the Nepal MS8.1 earthquake, and the co-seismic response characteristics of the water level and water temperature are analyzed and summarized with the digital data. The results show that the Nepal MS8.1 earthquake had greater impact on the Yunnan region, and the macro and micro dynamics of fluids showed significant co-seismic response. The earthquake recording capacity of water level and temperature measurement is significantly higher than that of water radon and water quality to this large earthquake; the maximum amplitude and duration of co-seismic response of water level and water temperature vary greatly in different wells. The changing forms are dominated by fluctuation and step rise in water level, and a rising or falling restoration in water temperature. From the records of the main shock and the maximum strong aftershock,we can see that the greater magnitude of earthquake, the higher ratio of the occurrence of co-seismic response, and in the same well, the larger the response amplitude, as well as the longer the duration. The amplitude and duration of co-seismic response recorded by different instruments in a same well are different.Water temperature co-seismic response almost occurred in wells with water level response, indicating that the well water level and water temperature are closely related in co-seismic response, and the well water temperature seismic response was caused mainly by well water level seismic response. 相似文献
10.
Lake Taihu, the third largest fresh water lake in China, with a surface area of 2 338 km2, is located in the Changjiang River Delta, the most advanced economic zone in China. During the last two decades, the rapid economic development of local agriculture and industry both in the urban and rural areas of the region has made great advances. Great quantieis of pollutants have been discharged into the lake, its nutrient content has increased continuously, and phytoplankton blooms have occurred in some areas. Water quality protection in Lake Taihu is very important because of its close relation with economical development and people''s daily life. It is urgent to have comprehensive pollution control in Lake Taihu. Based on water quality monitoring data in Lake Taihu from 1987 to 1994, the dynamic variations of water quality and eutrophication trends have been analyzed, showing obvious spatial and temporal variations. The main water quality factors were compared with the standard for drinking water and indicate considerable change with the seasons. Some basic strategies to protect water quality and prevent eutrophication are discussed. 相似文献
11.
Colin J. Whitfield Julian Aherne John J. Gibson Tim A. Seabert Shaun A. Watmough 《水文研究》2010,24(15):2143-2155
Spatial and temporal variability in surface water chemistry, organic soil chemistry and hydrologic indicators were investigated at three poor‐fen complexes in two boreal catchments in Northern Alberta to provide insight into the dominant controls on surface water chemistry. Improved understanding of these controls is required to enable prediction of runoff chemistry in the region under changing atmospheric deposition conditions. Surface water chemistry exhibited considerable variability; within each fen conductivity, dissolved organic carbon (DOC), and Cl− tended to decrease and pH tended to increase with increasing distance from the lake edge. Variations in evaporative isotopic enrichment in 2H and 18O, expressed as deuterium excess, were used to distinguish between throughflow waters and those that were more evaporatively enriched. Throughflow surface waters were more acidic primarily due to higher concentrations of DOC and NO3−. Exchangeable base saturation and pH of organic soils were strongly related to surface water chemistry at two of the fen complexes, demonstrating the capacity for cation exchange to influence surface water chemistry. Fen surface water concentrations of most elements and DOC increased during the summer period (between June and August), while pH of water decreased. Evaporative concentration of the surface waters was a dominant driver, with surface water temperature increasing at both catchments. Localized groundwater discharge was an important contributor of base cations to the fens, while the organic soils are sinks for atmospherically deposited SO42−, N and Cl−. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
12.
In this study, a methodology for clustering 18 lakes in Alberta, Canada using the data of 19 water quality parameters for a period of 11 years (1988–2002) is presented. The methods consist of (i) principal component analysis (PCA) to determine the dominant water quality parameters, (ii) cluster analysis techniques to develop the characteristics of the clusters, and (iii) pattern‐match lakes to determine the appropriate cluster for each of the lakes. The PCA revealed that three principal components (PCs) were able to explain ～88% of the variability and the dominant water quality parameters were total dissolved solids, total phosphorus, and chlorophyll‐a. We obtained five clusters for the period 1994–1997 by using the dominant parameters with water quality deteriorating as the cluster number increased from 1 to 5. Upon matching cluster patterns with the entire dataset, it was observed that some of the lakes belonged to the same cluster all the time (e.g., cluster 1 for lakes Elkwater, Gregg, and Jarvis; cluster 3 for Sturgeon; cluster 4 for Moonshine; and cluster 5 for Saskatoon), while others changed with time. This methodology could be applied in other regions of the world to identify the most suitable source waters and prioritize their management. It could be helpful to analyze the natural controlling processes, pollution types, impact of seasonal changes and overall quality of source waters. This methodology could be used for monitoring water bodies in a cost effective and efficient way by sampling only less number of dominant parameters instead of using a large set of parameters. 相似文献
13.
Carbon dioxide (CO2) and methane (CH4) concentrations and evasion rates were measured in surface waters draining Mer Bleue peatland (Ontario, Canada) between spring and autumn 2005. All sites exhibit a consistent pattern of supersaturation throughout the year, which is broadly related to hydrological and temperature changes between spring snowmelt and autumn freezing. Both measurements and estimates of CO2 and CH4 evasion from open water to the atmosphere suggest that parts of the catchment (including beaver dams) are significant degassing hot spots. We present data showing how vertical gaseous carbon fluxes compare with lateral carbon fluxes and make an initial estimate of the importance to the overall carbon budget of CO2 and CH4 evasion to the atmosphere from water surfaces at Mer Bleue. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
14.
Three techniques for obtaining soil water solutions (gravitational and matrical waters extracted using both in situ tension lysimeters and in vitro pressure chambers) and their later chemical analysis were performed in order to know the evolution of the soil‐solution composition when water moves down through the soil, from the Ah soil horizon to the BwC‐ or C‐horizons of forest soils located in western Spain. Additionally, ion concentrations and water volumes of input waters to soil (canopy washout) and exported waters (drainage solutions from C‐horizons) were determined to establish the net balance of solutes in order to determine the rates of leaching or retention of ions. A generalized process of sorption or retention of most components (even Cl?) was observed, from the soil surface to the C‐horizon, in both gravitational and matrical waters, with H4SiO4, Mn2+, Na+, and SO42? being the net exported components from the soil through the groundwater. These results enhance the role of the recycling effect in these forest soils. The net percentages of elements retained in these forest soils, considering the inputs and the outputs balance, were 68% K+, 85% Ca2+, 58% Mg2+, 7% Al3+, 5% Fe3+, 34% Zn2+, 57% Cl?, and 20% NO3?, and about 75% of dissolved organic carbon was mineralized. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
15.
《Marine pollution bulletin》2009,58(6-12):313-324
This study investigated the seasonal and spatial dynamics of nutrients and phytoplankton biomass at 12 stations in Hong Kong (HK) waters during a three year period from 2004 to 2006 after upgraded sewage treatment and compared these results to observations before sewage treatment. Pearl River estuary (PRE) discharge significantly increased NO3 and SiO4 concentrations, particularly in western and southern waters when rainfall and river discharge was maximal in summer. Continuous year round discharge of sewage effluent resulted in high NH4 and PO4 in Victoria Harbour (VH) and its vicinity. In winter, spring and fall, the water column at all stations was moderately mixed by winds and tidal currents, and phytoplankton biomass was relatively low compared to summer. In summer, the mean surface phytoplankton chl biomass was generally >9 μg L−1 in most areas as a result of thermohaline stratification, and high nutrients, light, and water temperature. In summer, the potential limiting nutrient is PO4 in the most productive southern waters and it seldom decreased to limiting levels (∼0.1 μM), suggesting that phytoplankton growth may be only episodically limiting. The mean bottom dissolved oxygen (DO) remained >3.5 mg L−1 at most stations, indicating that the eutrophication impact in HK waters was not as severe as expected for such a eutrophic area. After the implementation of chemically enhanced primary sewage treatment in 2001, water quality in VH improved as indicated by a significant decrease in NH4 and PO4 and an increase in bottom DO. In contrast, there were an increase in chl a and NO3, and a significant decrease in bottom DO in southern waters in summer, suggesting that hypoxic events are most likely to occur in this region if phytoplankton biomass and oxygen consumption keep increasing and exceed the buffering capacity of HK waters maintained by monsoon winds, tidal mixing and zooplankton grazing. Therefore, future studies on the long-term changes in nutrient loading from PRE and HK sewage discharge will be crucial for developing future strategies of sewage management in HK waters. 相似文献
16.
The introduction of the four-arm dipmeter well-logging tool has permitted hole asymmetry to be recognised and hole ellipticity to be measured and oriented. Many wells in Alberta, western Canada, have been shown to exhibit depth ranges over which they are non-circular as a result of caving of their walls. These break-outs occur so as to elongate the holes in a northwest-southeast direction. This direction of elongation is consistent between the break-outs in a given well, and between wells distributed over an area of more than 3 × 105 km2. Asymmetric hole elongation occurs in siltstones, sandstones, limestones, dolomites and one shale formation, and through the stratigraphic column from Devonian to Cretaceous. It is unrelated to dip of the strata. The hypothesis is advanced that the break-outs are caused by concentration of stress at the walls of the wells, in a stress field with large, unequal horizontal principal stresses, the larger oriented NE-SW. It is shown that a normal stress field (with the largest principal stress, σ1, vertical) is unlikely to produce large enough horizontal stresses to produce the break-outs. Consequently our hypothesis requires σ1 to be horizontal and oriented NE-SW. The vertical principal stress could be either σ2 (strike-slip stress field) or σ3 (thrust stress field). The orientation of σ1 at right angles to the Rocky Mountains fold axes suggests the possibility that the stress field responsible for the thrust faulting in the mountains is still present. A strike-slip stress field is also possible. The most prominent system of surface joints outcropping in Alberta, shown by Babcock to have sets oriented NE-SW and NW-SE, could have been formed in the proposed stress field. Direct measurements of the stress tensor at two or three points, if they verified this interpretation, would combine with the oil well break-outs to demonstrate a remarkably uniform stress field over a substantial part of the North American plate. The stresses in the Alberta crust here proposed may be related to tractions now acting on the edges and underside of the North American plate, including those producing postglacial uplift of Hudson's Bay; or may be residual stresses from past tectonic events such as the Laramide compression of the Rocky Mountains. 相似文献
17.
Corinne Tarits Robin W. Renaut Jean‐Jacques Tiercelin Alain Le Hriss Jo Cotten Jean‐Yves Cabon 《水文研究》2006,20(9):2027-2055
Lake Baringo, a freshwater lake in the central Kenya Rift Valley, is fed by perennial and ephemeral rivers, direct rainfall, and hot springs on Ol Kokwe Island near the centre of the lake. The lake has no surface outlet, but despite high evaporation rates it maintains dilute waters by subsurface seepage through permeable sediments and faulted lavas. New geochemical analyses (major ions, trace elements) of the river, lake, and hot spring waters and the suspended sediments have been made to determine the main controls of lake water quality. The results show that evaporative concentration and the binary mixing between two end members (rivers and thermal waters) can explain the hydrochemistry of the lake waters. Two zones are recognized from water composition. The southern part of the lake near sites of perennial river inflow is weakly influenced by evaporation, has low total dissolved species (TDS), and has a seasonally variable load of mainly detrital suspended sediments. In contrast, waters of the northern part of the lake show evidence for strong evaporation (TDS of up to eight times inflow). Authigenic clay minerals and calcite may be precipitating from those more concentrated fluids. The subaerial hot‐spring waters have a distinctive chemistry and are enriched in some elements that are also present in the lake water. Comparison of the chemical composition of the inflowing surface waters and lake water shows (1) an enrichment of some species (HCO3?, Cl, SO42?, F, Na, B, V, Cr, As, Mo, Ba and U) in the lake, (2) a depletion in SiO2 in the lake, and (3) a possible hydrothermal origin for most F. The rare earth element distribution and the F/Cl and Na/Cl ratios give valuable information on the rate of mixing of the river and hydrothermal fluids in the lake water. Calculations imply that thermal fluids may be seeping upward locally into the lake through grid‐faulted lavas, particularly south of Ol Kokwe Island. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
18.
There are six classes of water and five geologic environments in the subarctic Nahanni karst. During the summers of 1972 and 1973, 214 water samples were collected from 15 of the 30 hydrogeologic categories. Linear discriminant function analysis, using five measured and two derived chemical variables, indicates that there are statistically significant (0.005 level) differences in water chemistry between similar waters in different geologic environments, between waters in the same geologic environment, and between waters in different hydrogeological categories. Geological environment labels a natural water because it determines the availability of soil CO2 and of soluble minerals. Measurements indicate that mean soil log PCO2 is greatest in areas of shale mantled by till (?2.39), and least in areas of sandy fluvioglacial drift (?3.27). Low values on the sandy drift are due to the sparse shrub vegetation, and to the high degree of soil aeration; soils in areas of shale are clay-rich and support a dense boreal forest. Hydrology influences water chemistry because it determines how much CO2 natural waters pick up from the environment and how much they subsequently lose to the atmosphere, and as a result, whether they dissolve or deposit soluble materials. The similarity between mean calculated log PCO2 in natural waters (?2.92) and mean measured soil log PCO2 (?2.80) suggests that natural waters in Nahanni are dose to equilibrium with mean soil CO2 levels. 相似文献
19.
Groundwater discharges in the western Canadian oil sands region impact river water quality. Mapping groundwater discharges to rivers in the oil sands region is important to target water quality monitoring efforts and to ensure injected wastewater and steam remain sequestered rather than eventually resurfacing. Saline springs composed of Pleistocene‐aged glacial meltwater exist in the region, but their spatial distribution has not been mapped comprehensively. Here we show that formation waters discharge into 3 major rivers as they flow through the Athabasca Oil Sands Region adjacent to many active oil sands projects. These discharges increase river chloride concentrations from river headwaters to downstream reaches by factors of ~23 in the Christina River, ~4 in the Clearwater River, and ~5 in the Athabasca River. Our survey provides further evidence for the substantial impact of formation water discharges on river water quality, even though they comprise less than ~2% of total streamflow. Geochemical evidence supporting formation water discharges as the leading control on river salinity include increases in river chloride concentrations, Na/(Na + Ca) ratios, Cl/(Cl + SO4) ratios and decreases in 87Sr/86Sr ratios; each mixing trend is consistent with saline groundwater discharges sourced from Cretaceous or Devonian aquifers. These regional subsurface‐to‐surface connections signify that injected wastewater or steam may potentially resurface in the future, emphasizing the critical importance of mapping groundwater flow paths to understand present‐day streamflow quality and to predict the potential for injected fluids to resurface. 相似文献
20.
Time‐lapse seismic modelling of CO2 fluid substitution in the Devonian Redwater Reef,Alberta, Canada
Common shot ray tracing and finite difference seismic modelling experiments were undertaken to evaluate variations in the seismic response of the Devonian Redwater reef in the Alberta Basin, Canada after replacement of native pore waters in the upper rim of the reef with CO2. This part of the reef is being evaluated for a CO2 storage project. The input geological model was based on well data and the interpretation of depth‐converted, reprocessed 2D seismic data in the area. Pre‐stack depth migration of the ray traced and finite difference synthetic data demonstrate similar seismic attributes for the Mannville, Nisku, Ireton, Cooking Lake, and Beaverhill Lake formations and clear terminations of the Upper Leduc and Middle Leduc events at the reef margin. Higher amplitudes at the base of Upper‐Leduc member are evident near the reef margin due to the higher porosity of the foreslope facies in the reef rim compared to the tidal flat lagoonal facies within the central region of the reef. Time‐lapse seismic analysis exhibits an amplitude difference of about 14% for Leduc reflections before and after CO2 saturation and a travel‐time delay through the reservoir of 1.6 ms. Both the ray tracing and finite difference approaches yielded similar results but, for this particular model, the latter provided more precise imaging of the reef margin. From the numerical study we conclude that time‐lapse surface seismic surveys should be effective in monitoring the location of the CO2 plume in the Upper Leduc Formation of the Redwater reef, although the differences in the results between the two modelling approaches are of similar order to the effects of the CO2 fluid replacement itself. 相似文献