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991.
溪谷输变电站工程场地具有较复杂的双层地质结构.岩土体拉分变形明显.场地后缘及底部岩土体的主应力和剪应力集中明显,堆积体内部岩体处于拉分松弛状态.岩土体的潜在变形模式以蠕滑-拉裂为主.在水库蓄水与地震共同作用的极限工况下.场地处于潜在不稳定状态. 相似文献
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994.
The Yitong(伊通) basin is a Late Mesozoic and Cenozoic continental sedimentary basin in Northeast China.On the basis of well tests and seismic data,we use the 2D modeling technique to rebuild the pressure evolution and hydrocarbon migration in the Moliqing(莫里青) fault depression of the Yitong basin.Based on the modeling results,four conclusions are drawn as follows.(1) The Eocene Shuangyang(双阳) Formation within the Moliqing fault depression had entirely undergone three epi-sodic cycles of pressure accumulation... 相似文献
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Source Apportionment of PAHs Using Two Mathematical Models for Mangrove Sediments in Shantou Coastal Zone,China 总被引:2,自引:0,他引:2
Thirty-five surface sediment samples collected from three mangroves in Shantou coastal zone, China in 2007 were analyzed for
a suite of polycyclic aromatic hydrocarbons (PAHs). Two mathematical models were used to determine the profiles and relative
contributions of PAH sources to the mangroves. The two models are principal component analyses (PCA) with multiple linear
regression analysis (MLR) and positive matrix factorization (PMF). Both models identified five factors and gave excellent
correlation coefficients between predicted and measured levels of 16 PAH compounds, but the results had some differences.
The PAH contribution rate attributed to vehicular emission sources identified by PCA-MLR was 37.20%, but the rate identified
by PMF was only 12.37%. The main sources identified by PCA-MLR were combination of biomass/coal combustion and vehicular emissions,
whereas the main source identified by PMF was only biomass/coal combustion. The PMF analysis was the preferred model for the
paper data set. 相似文献
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998.
Sorption and desorption behavior of lead on a Chinese kaolin 总被引:1,自引:0,他引:1
Shengli Wang Zhongren Nan Xinde Cao Qin Liao Jiao Liu Wenfei Wu Ting Zhou Cuicui Zhao Wangqiang Jin 《Environmental Earth Sciences》2011,63(1):145-149
The sorption and desorption of Pb on kaolin from Suzhou, China were investigated. The sorption experiment was conducted in
a 0.01 M NaNO3 aqueous solution with respect to the effects of initial Pb concentration, pH, solid/solution ratio, and temperature. Langmuir
and Freundlich models well described equilibrium isotherms of Pb sorption. Less than 5% of Pb sorbed was desorbed with 0.01 M
NaNO3 extraction, suggesting a dominant specific sorption of Pb. As the initial pH increased, the sorption of Pb on the kaolin
increased. More than 60% of Pb was sorbed at pH 2.69 far below the point of zero net charge of the kaolin at 4.2, indicating
a mechanism of Pb inner-sphere complex or by chemisorption. Lead sorption decreased with increasing temperature, indicating
a process of exothermic sorption. 相似文献
999.
Sheng Kui Cao Qi Feng Yong Hong Su Zong Qiang Chang Hai Yang Xi 《Environmental Earth Sciences》2011,62(8):1597-1607
Seasonal variations in foliar stable carbon composition (δ13C) and nitrogen (N), phosphorus (P) and potassium (K) concentrations of Populus euphratica Olivier and Tamarix ramosissima Ledeb, as well as correlations between foliar δ13C values and N, P and K concentrations were studied in the Ejina oasis in the lower reaches of the Heihe River, northwestern
China. Foliar δ13C values, and P and K concentrations significantly differed between species. Foliar δ13C signatures in T. ramosissima were significantly more enriched than those in P. euphratica, but P and K concentrations of P. euphratica were higher. The seasonal variations and patterns of these were similar. The total foliar δ13C values and N, P and K concentrations in both P. euphratica and T. ramosissima showed a descending trend. There were significantly positive correlations between foliar δ13C values and N and P concentration of both P. euphratica and T. ramosissima. For the relationship between foliar δ13C and K concentration, there appeared oppositely positive and negative correlations in P. euphratica and T. ramosissima, respectively, but they were not significant. The simple positive correlations of δ13C–P% and δ13C–N% suggested that N and P in P. euphratica and T. ramosissima behave in a similar manner. This study also showed that there were nutrient deficiencies; N and P nutriments were the co-limiting
factors in P. euphratica, while it was P nutriment in T. ramosissima. 相似文献
1000.
Deep convection in polar oceans plays a critical role in the variability of global climate. In this study, we investigate potential impacts of atmosphere–sea ice–ocean interaction on deep convection in the Southern Ocean (SO) of a climate system model (CSM) by changing sea ice–ocean stress. Sea ice–ocean stress plays a vital role in the horizontal momentum exchange between sea ice and the ocean, and can be parameterized as a function of the turning angle between sea ice and ocean velocity. Observations have shown that the turning angle is closely linked to the sea-ice intrinsic properties, including speed and roughness, and it varies spatially. However, a fixed turning angle, i.e., zero turning angle, is prescribed in most of the state-of-the-art CSMs. Thus, sensitivities of SO deep convection to zero and non-zero turning angles are discussed in this study. We show that the use of a non-zero turning angle weakens open–ocean deep convection and intensifies continental shelf slope convection. Our analyses reveal that a non-zero turning angle first induces offshore movement of sea ice transporting to the open SO, which leads to sea ice decrease in the SO coastal region and increase in the open SO. In the SO coastal region, the enhanced sea-ice divergence intensifies the formation of denser surface water descending along continental shelf by enhanced salt flux and reduced freshwater flux, combined with enhanced Ekman pumping and weakened stratification, contributing to the occurrence and intensification of continental shelf slope convection. On the other hand, the increased sea ice in the open SO weakens the westerlies, enhances sea-level pressure, and increases freshwater flux, whilst oceanic cyclonic circulation slows down, sea surface temperature and sea surface salinity decrease in the open SO response to the atmospheric changes. Thus, weakened cyclonic circulation, along with enhanced freshwater flux, reduced deep–ocean heat content, and increased stability of sea water, dampens the open–ocean deep convection in the SO, which in turn cools the sea surface temperature, increases sea-level pressure, and finally increases sea-ice concentration, providing a positive feedback. In the CSM, the use of a non-zero turning angle has the capability to reduce the SO warm bias. These results highlight the importance of an accurate representation of sea ice–ocean coupling processes in a CSM. 相似文献