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861.
862.
Estimation of groundwater evaporation and salt flux from Owens Lake, California, USA 总被引:3,自引:0,他引:3
S. W. Tyler S. Kranz M. B. Parlange J. Albertson G. G. Katul G. F. Cochran B. A. Lyles G. Holder 《Journal of Hydrology》1997,200(1-4):110-135
Groundwater evaporation and subsequent precipitation of soluble salts at Owens Lake in eastern California have created one of the single largest sources of airborne dust in the USA, yet the evaporation and salt flux have not been fully quantified. In this study, we compare eddy correlation, microlysimeters and solute profiling methods to determine their validity and sensitivity in playa environments. These techniques are often used to estimate evaporative losses, yet have not been critically compared at one field site to judge their relative effectiveness and accuracy. Results suggest that eddy correlation methods are the most widely applicable for the variety of conditions found on large playa lakes. Chloride profiling is shown to be highly sensitive to thermal and density-driven fluxes in the near surface and, as a result, appears to underestimate yearly groundwater evaporation. Yearly mean groundwater evaporation from the playa surface estimated from the three study areas was found to range from 88 to 104 mm year−1, whereas mean evaporation from the brine-covered areas was 872 mm year−1. Uncertainties on these mean rates were estimated to be ±25%, based on comparisons between eddy correlation and lysimeter estimates. On a yearly basis, evaporation accounts for approximately 47 × 106 m3 of water loss from the playa surface and open-water areas of the lake. Over the playa area, as much as 7.5 × 108 kg (7.5 × 105 t) of salt are annually concentrated by evaporation at or near the playa surface, much of which appears to be lost during dust storms in area. 相似文献
863.
The identifiability of parameters in a water quality model of the Biebrza River, Poland 总被引:1,自引:0,他引:1
The identifiability of model parameters of a steady state water quality model of the Biebrza River and the resulting variation in model results was examined by applying the Monte Carlo method which combines calibration, identifiability analysis, uncertainty analysis, and sensitivity analysis. The water quality model simulates the steady state concentration profiles of chloride, phosphate, ammonium, and nitrate as a function of distance along a river. The water quality model with the best combination of parameter values simulates the observed concentrations very well. However, the range of possible modelled concentrations obtained for other more or less equally eligible combinations of parameter values is rather wide. This range in model outcomes reflects possible errors in the model parameters. Discrepancies between the range in model outcomes and the validation data set are only caused by errors in model structure, or (measurement) errors in boundary conditions or input variables. In this sense the validation procedure is a test of model capability, where the effects of calibration errors are filtered out. It is concluded that, despite some slight deviations between model outcome and observations, the model is successful in simulating the spatial pattern of nutrient concentrations in the Biebrza River. 相似文献
864.
Jadeitic rocks within high pressure metamorphic zone from northeastern Jiangxi Province and their forming and surviving conditions 总被引:1,自引:0,他引:1
Guoqing Zhou 《中国科学D辑(英文版)》1997,40(5):477-484
There is a close relation in time, space and origin between the NEJXO, NEJXDFZ and HPMZ from NEJXP which are located in and
constrained by both Yangtze Craton and Cathaysia. These HPMRs principally include (i) Jd-Q-Ab schist, (ii) Lw-Jd-Ab schist,
(iii) Jd-Ab schist, and (iv) Gl-schist. The Jd is nearly pure (Jd91-98). Jd surrounded by Ab is separated from Q and survived
due to the reaction between Jd and Q, while Lw encircled by Ab remains as a pseudomorph composed of CZo+An. The minerals associated
with Jd are Lw, Gl, Ab, Q, CZo, An, Pa, II, Ru, Sp, Ap, and Zr. According to the textures, the mineral paragenesis is classified
into four groups (i) PI-Am-Q, (ii) Jd-I,w-GI-Q, (iii) CZo-An-Ab-Q, (iv) Ab-Ana-Ser-Ur, corresponding to (i) 1.0–0.93 Ga, 250°C,
2–3 × 108 Pa; (ii) 0.93–0.79 Ga, 300–350°C, 5–12 × 108 Pa; (iii) 0.79–0.223 Ga, 350–400–120°C, 12–5–3 × 108 Pa; and (iv) < 0. 223 Ga, < 120–50°C, < 3 × 108 Pa, in time, temperature and pressure respectively. A clockwiseP-T-t path is isothermal increasing inP (up to 45 km)—isothermal decreasing inP (up to 5 km)— nearly isobar decreasing in T.
Project supported by the National Natural Science Foundation of China. 相似文献
865.
Sm/Nd isotopic age determination showed that Xiongshan dike swarm was at 585.7 Ma ± 30 Ma. The trace element geochemistry
and Sr/Nd/Pb isotope gemhemistry studies indicate that the dike swarm was products of back-arc basin spreading ridge and the
magma originated from the depleted mantle region which was metasomatized by LILE-rich liquids/melts derived from subduction
slab.
Project supported by the National Natural Science Foundation of China. 相似文献
866.
Yousheng Xu Hongsen Xie Jie Guo Haifei Zheng Yueming Zhang Maoshuang Song 《中国科学D辑(英文版)》1997,40(4):398-402
NaCI-H2O is the most fundamental ternary system in geology. Until now, the measurements of electrical conductivity of NaCl solutions
are still little at high pressures (> O.5 GPa) We measured the conductivity of 0.01 m NaCl solution at 0.4–5.0 GPa and 25-500°C.
The results are consistent with that of Quist and Marshall (1968) at 0.4 GPa. The conductivity of NaCl solution increases
with increasing temperature. The results also show that the conductivity of NaCl solution changes little with increasing pressure
below 1.5 GPa and changes rapidly with increasing pressure above 1.5 GPa. The rapid increase of the conductivity of NaCl solution
may play an important role in many geological processes (such as the genesis of ore deposits under hydrothermal condition)
and other fields.
Project supported by the National Natural Science Foundation of China. 相似文献
867.
868.
Numerical modeling of 3-D terrain effect on MT field 总被引:1,自引:0,他引:1
Using the boundary element method, the numerical modeling problem of three-dimensional terrain effect on magnetotelluric (MT)
field is solved. This modeling technique can be run on PC in the case of adopting special net division. The result of modeling
test for 2-D terrain by this modeling technique is basically coincident with that by 2-D modeling technique, but there is
a great difference between the results of 3-D and 2-D modeling for 3-D terrain.
Project supported by the National Natural Science Foundation of China. 相似文献
869.
Properties of wave velocity for two types of granitoids at high pressure and temperature and their geological meaning 总被引:1,自引:0,他引:1
Shufeng Yang Hanlin Chen Jishuang Jiang Guoqiang Zhu Hongshen Xie Wei Hou Yueming Zhang Huigang Xu 《中国科学D辑(英文版)》1997,40(5):470-476
The wave velocity for two types of granitoids was measured using the analytic method of full-wave vibration at high pressure
and high temperature. The laws of velocity changes for them differ with the pressure boost and temperature rise, and the velocity
change of S-type is more violent than that of I-type. The “softening point” of compressional wave velocity (V μ) is also revealed
during the measurement for two types of granitoids imitating the pressure and temperature at a certain depth. But the depth
of “softening”, Vp after “softening” and the percentage of Vp’s drop around the “sofrening point” for two types of granitoids are obviously different. The depth of “softening” is 15 km
approximately and Vp after “softening” is 5.62 km/s for S-type granitoid. But for I-type granitoid the depth of “softening” is 26 km approximately
and Vp after “softening” is 6. 08 km/s. Through careful analysis of rock slices after the experiment, it was found that the “softening”
of elastic-wave velocity is caused by the partial melting of granite. Combined with the results of geophysical prospecting,
these results suggest that the low-velocity layers developing in the interior of Earth crust are related to thc partial melting
of different types of granitoids. The formation of the low-velocity layer in the upper-middle Earth crust is closely related
to the development of S-type granitoid, but that in the lower Earth crust is closely related to the development of I-type
granitoid. 相似文献
870.
Evolution model and formation mechanism of bio-thermocatalytic transitional zone gas 总被引:1,自引:0,他引:1
As a new genetic type of natural gas exploration area, the bio-thermocatalytic transitional zone gas (BTTZG) has been highly
stressed by geologists both at home and abroad. Systematic study on the generation mechanism of hydrocarbon at the transitional
zone is presented. Based on simulating experiments and geochemistry analysis of the source rock with lower evolution, a hydrocarbon-forming
model at the transitional zone has been established. The mechanism is proposed that under the condition of low temperature
and pressure combining with extremely active structural stress and clay mineral catalysis, BTTZG is formed by de-group of
soluble organic matter and polarized compositions through orthocarbon ion as well as by condensation polymerization of aromatic
ring-rich insoluble organic matter. This mechanism controls the formation of BTTZG, and furthermore, BTTZG is the product
of superimposition and interaction of all the factors mentioned above. 相似文献