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951.
Liu Yi nan Sun Fengxia Cui Yueju Pan Xiaodong Ma Mingzhi Zhang Xin Du Jianguo 《地球科学进展》2017,32(8):810-817
The hydrochemical types and origins of underground water in Songyuan and vicinity, Liaoning Province were discussed based on the hydrochemical composition, δD and δ18O. The water samples from eight wells were collected 4 times during 2014 to 2015. The main ion concentrations of water were analyzed with an Ion Chromatography. Isotopic compositions of hydrogen and oxygen were analyzed with the Liquid Water Isotope Analyzer. The mineralization (TDS) of the water ranged from 125.4 mg/L to 19 350.9 mg/L. Values of δD and δ18O ranged from -71.7‰ to -98.1‰ and from -9.0‰ to -12.5‰, respectively. The isotopic data indicated that the water originated from meteorological precipitation. The chemical compositions of Taolaizhao phreatic water were influenced by the human activity while the other water samples collected from artesian well were less affected by the human activity. Water in Changling, Dongdashi, Taohaotai, Qianan and Ningjiang were characterized by HCO3-Na with low TDS values. Such chemical types of water with fluctuations of Na+, SO 4 2 - and δ18O drift were resulted from dissolving silicate minerals and adding surfactant during oil exploitation. Fresh water in Fuyu well was Cl-Na type, which was influenced by acid injection during oil exploitation. Water in Qianguo well was characterized by Cl-Na type with TDS up to 19 350.9 mg/L, the obvious fluctuations of hydrogen and oxygen isotopes and increasing ion concentrations in the Qianguo well may be caused by the earthquakes that occurred in the sampling duration. The results will provide the background of hydrochemistry, and will be of benefit to monitoring earthquake and certificating seismic-chemical anomalies in the future. 相似文献
952.
由于北京的地理位置较为特殊,地质构造较为复杂,冲洪积扇和古河道等作用较为多样,第四纪地层剖面标准化工作进行的还不够详尽,发展较其他城市稍显滞后。本文通过前人对北京市平原区第四纪地层的划分,在已有基准孔网和三维结构的基础上,对常营地区第四纪地层进行了更为详尽的标准化分层(共分为39层),进而利用计算机建立了标准地层数据库,完成了三维准自动化地质体模型构建工作,实现了地面沉降模型与视电阻率属性模型的耦合显示,进行了基本分析,验证了研究区相同流域,距离1km2的区域通过标准化分层自动构建地质体模型。 相似文献
953.
Debris flows can be extremely destructive because they can increase in magnitude via progressive entrainment. In this paper, a total of 18 landslide-type debris flows and 268 channelized debris flows in Wenchuan earthquake and Taiwan region, as well as other regions were collected to analyze the entrainment rate of debris flows in each triggering condition. Results show that there is a power relationship between volume of initial triggered mass and final deposited debris for landslide type debris flow. The debris flows during 2008 and 2013 in Wenchuan earthquake-region have smaller entrainment rate than that from 2001 t0 2009 in Taiwan. The entrainment rate of debris flow events from 2001 to 2009 in Taiwan shows a decaying tendency as elapsed time. Comparison of the entrainment rate in the two earthquake-hit regions with other regions proves that entrainment rate has a close relation with major sediment availability and secondary rainstorm conditions. 相似文献
954.
Decoupled simulation of groundwater flow and heat transport assuming constant fluid density and viscosity is computationally efficient and simple. However, by neglecting the effects of variable density and viscosity, numerical solution of heat transport may be inaccurate. This study investigates the conditions under which the density and viscosity effects on heat transport modeling can be neglected without any significant loss of computational accuracy. A cross-section model of aquifer-river interactions at the Hanford 300 Area in Washington State was employed as the reference frame to quantify the role of fluid density and viscosity in heat transport modeling. This was achieved by comparing the differences in simulated temperature distributions with and without considering variable density and viscosity, respectively. The differences between the two sets of simulations were found to be minor under the complex field conditions at the Hanford 300A site. Based on the same model setup but under different prescribed temperature gradients across the simulation domain, a series of heat transport scenarios were further examined. When the maximum temperature difference across the simulation domain is within 15°C, the mean discrepancy between the simulated temperature distributions with and without considering the effects of variable density and viscosity is approximately 2.5% with a correlation coefficient of above 0.8. Meanwhile, the speedup in runtime is roughly 225% when the maximum temperature difference is at 15°C. This work provides some quantitative guidelines for when heat transport may be simulated by assuming constant density and viscosity as a reasonable compromise between accuracy and efficiency. 相似文献
955.
956.
Little information is available concerning the performance of grass strips for erosion control from steep cropland. An experiment was conducted on 5‐m‐long grass strips with slopes of 3°~15° that were subjected to silt laden runoff and simulated rainfall, to investigate the sediment trapping processes. The grass strips had three treatments including intact grass control (C), no litter (dead grass material covering the soil surface was removed) (NL), and no litter or leaves (only 2~3 cm grass stems and roots were reserved) (NLL). Generally the grass strips had a high effectiveness in trapping sediment from steep cropland runoff. Sediment trapping efficiency (STE) decreased with increasing slope gradient, and even for a 15° slope, STE was still more than 40%. Most sediment deposited in the backwater region before each grass strips. The removal of grass litter or/and leaves had no significant influence on STE. The sediment median size (D50) in inflow was greater than that in outflow, and the difference (ΔD50) decreased with increasing slope. A positive power relationship between STE and ΔD50 can be obtained. Grass strips were more effective in trapping sediments coarser than 10 or 25 µm, but sediments finer than 1 µm were more readily removed from runoff than particles in the range of 2 to approximately 10 µm. Grass litter had less influence on flow velocity than leaves because the deposited sediment partially covered the litter layer. Mean flow velocity and its standard deviation were negatively correlated with STE, and they can help make good estimation of STE. Results from this study should be useful in planting and managing forage grass to effectively conserve soil loss by runoff from steep slopes on the Loess Plateau of China. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
957.
958.
???????????????????У?????????????????????????????????????????????????????????????????????????????????????GPS??InSAR?????????????е??????÷?????????????????????????????????Ч???????????????????????????? 相似文献
959.
Wei Zhong Jibin Xue Jun Ouyang Yanming Zheng Qiaohong Ma Xuefeng Yu 《Journal of Paleolimnology》2010,44(3):777-788
Two cores were recovered from raised peat bogs on the tropical northern Leizhou Peninsula, south China. Multiple sediment
variables including organic matter (OM) content, the stable carbon isotope signature of OM, low-frequency magnetic susceptibility
and degree of humification, indicate that the regional paleoclimate played an important role in determining the nature of
peat that accumulated. Based on comparison with other climate proxies, the bulk peat δ13C record was interpreted as an indicator of variation in the East Asian (EA) summer monsoon, and to a lesser extent, the Indian
summer monsoon, during the last glacial period between ~49 and 10 cal ka BP. More negative bulk δ13C values reflect wetter and warmer conditions, and thus a strong EA summer monsoon. More positive values indicate drier and
cooler conditions. A warm and wet period occurred between ~46 and 28 cal ka BP, implying a strengthening of the EA summer
monsoon. A climate shift occurred at ~22 cal ka BP and the driest and coldest period appeared between ~19 and 16 cal ka BP,
suggesting weakening of the EA summer monsoon. After ~12 cal ka BP, climate shifted towards wetter and warmer conditions again.
It has been suggested that variations in orbitally induced solar insolation played a role in the last glacial climate of the
study region. Several millennial—scale arid and cold phases characterized by C4 plants, or by more positive δ13C values during periods when C3 plants dominated, show agreement with the Greenland GISP2 ice core and the Chinese stalagmite
records. Interactions between high northern latitude cold air advection and summer moisture transported across the tropical
ocean, and the migration of the mean position of the Intertropical Convergence Zone (ITCZ) would have favored these millennial–scale
phases. Additionally, changes in heat transport to the North Atlantic would also have influenced climate in the region. 相似文献
960.
利用1990年以来江西省交通运输及相关统计数据,在分析和评价全省各地市客、货运量状况的基础上,运用地域非均衡系数、区域位势商指标,对江西省客、货流运输联系的空间演化特征及趋势进行了探讨。研究表明,全省在交通运输业快速发展的同时,客、货运输在空间分布上已由低水平的集中趋向均衡发展,客运的廊道效应初显,在京九铁路、浙赣铁路、昌九高速、赣粤高速沿线地区客流较为集中;货运重心南移,极化效应减弱,随着全省各地市的资源优势开始转为经济优势,货运地位出现有序演变。结合江西省经济发展所处阶段,对其运输化发展阶段进行了初步的分析和讨论。 相似文献