http://www.sciencedirect.com/science/article/pii/S1674987111000752   总被引：2，自引：0，他引：2  

Jiansheng Shi  Zhao Wang  Zhaoji Zhang  Yuhong Fei  Yasong Li  Feng’e Zhang  Jingsheng Chen  Yong Qian 《地学前缘(英文版)》2011,2(4):593-598

A series of environmentalegeological problems have been caused by over-exploitation of deep groundwater (i.e., confined aquifer water) in the North China Plain. In order to better understand the status of deep groundwater over-exploitation and the resultant environmentalegeological problems on a regional scale, the over-exploitation of groundwater has been assessed by way of the groundwater exploitation potential coefficient (i.e., the ratio of exploitable amount of deep groundwater to current exploitation), cumulative land subsidence, and long-term average lowering rate of the groundwater table. There is a good correlation among the results calculated by the different methods. On a regional scale, deep groundwater has been over-exploited and there is no further exploitation potential under the current conditions. The groundwater exploitation degree index takes the exploitation in 2003 as the reference for the calculations, so the results mainly reflect the degree of current groundwater exploitation. The results of over-exploitation of deep groundwater obtained by land subsidence data and long-term average rate of depression of the water table mainly reflect environmentalegeological problems caused by exploitation of deep groundwater.  相似文献   

Numerical simulation of wave-induced currents combined with parabolic mild-slope equation in curvilinear coordinates     

崔雷  佟飞飞  石峰 《中国海洋工程》2011,25(3):457-468

Researches on breaking-induced currents by waves are summarized firstly in this paper. Then, a combined numerical model in orthogonal curvilinear coordinates is presented to simulate wave-induced current in areas with curved boundary or irregular coastline. The proposed wave-induced current model includes a nearshore current module established through orthogonal curvilinear transformation form of shallow water equations and a wave module based on the curvilinear parabolic approximation wave equation. The wave module actually serves as the driving force to provide the current module with required radiation stresses. The Crank-Nicolson finite difference scheme and the alternating directions implicit method are used to solve the wave and current module, respectively. The established surf zone currents model is validated by two numerical experiments about longshore currents and rip currents in basins with rip channel and breakwater. The numerical results are compared with the measured data and published numerical results.  相似文献   

Experimental researches on reflective and transmitting performances of quarter circular breakwater under regular and irregular waves   总被引：1，自引：1，他引：0  

史艳娇  吴米玲  蒋学炼  李炎保 《中国海洋工程》2011,25(3):469-478

A series of regular and irregular wave experiments are conducted to study the reflective and transmitting performances of quarter circular breakwater (QCB) in comparison with those of semi-circular breakwater (SCB). Based on regular wave tests, the reflection and transmission characteristics of QCB are analyzed and a few influencing factors are investigated. Then, the wave energy dissipation as wave passing over the breakwater is discussed based on the hydraulic coefficients of QCB and SCB. In irregular wave experiments, the reflection coefficients of QCB and their spectrums are studied. Finally, the comparisons between the experimental results and numerical simulations for QCB under regular and irregular wave conditions are presented.  相似文献   

Environmental capacity of chemical oxygen demand in the Bohai Sea: modeling and calculation     

赵喜喜  王修林  石晓勇  李克强  丁东生 《中国海洋湖沼学报》2011,29(1):46-52

A three-dimensional advection-diffusion model coupled with the degradation process is established for describing the transport of chemical oxygen demand (COD). Comparison of the simulated distribution of COD at the surface in the Bohai Sea in August, 2001 with field observations, shows that the model simulates the dataset reasonably well. The Laizhou Bay, Bohai Bay, and Liaodong Bay were contaminated heavily near shore. Based on the optimal discharge flux method, the Environmental Capacity (EC) and allocate...  相似文献   

A new ketosteroid from red alga Acanthophora spicifera     

史大永  郭书举  范晓 《中国海洋湖沼学报》2011,29(3):674-678

A new ketosteroid, along with six known steroids, was isolated from the ethanolic extracts of red alga Acanthophora spicifera (Vahl.) Boergesen. The structures, identified using chemical and spectroscopic methods including 2D NMR, were: (1) 22-hydroxy-5α-cholest-3,6-dione, (2) 6-hydroxycholest-4-ene-3-one, (3) cholest-4-ene-3,6-dione, (4) cholest-5-ene-3β-ol, (5) 5α-cholestane-3,6-dione, (6) β-Sitosterol and (7) Saringosterol. The MTT method was used to test the cytotoxicity of the compounds against the human cancer cell lines, HCT-8, Bel-7402, BGC-823, A549 and HELA. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity against human cancer cell lines.  相似文献   

A spectral mixture model analysis of the Kuroshio variability and the water exchange between the Kuroshio and the East China Sea   总被引：1，自引：0，他引：1  

宋军  薛惠洁  鲍献文  吴德星  柴扉  施磊  姚志刚  王勇智  南峰  万凯 《中国海洋湖沼学报》2011,29(2):446-459

For understanding more about the water exchange between the Kuroshio and the East China Sea,We studied the variability of the Kuroshio in the East China Sea(ECS) in the period of 1991 to 2008 using a three-dimensional circulation model,and calculated Kuroshio onshore volume transport in the ECS at the minimum of 0.48 Sv(1 Sv ;106 m3/s) in summer and the maximum of 1.69 Sv in winter.Based on the data of WOA05 and NCEP,The modeled result indicates that the Kuroshio transport east of Taiwan Island decreased since 2000.Lateral movements tended to be stronger at two ends of the Kuroshio in the ECS than that of the middle segment.In addition,we applied a spectral mixture model(SMM) to determine the exchange zone between the Kuroshio and the shelf water of the ECS.The result reveals a significantly negative correlation(coefficient of-0.78) between the area of exchange zone and the Kuroshio onshore transport at 200 m isobath in the ECS.This conclusion brings a new view for the water exchange between the Kuroshio and the East China Sea.Additional to annual and semi-annual signals,intra-seasonal signal of probably the Pacific origin may trigger the events of Kuroshio intrusion and exchange in the ECS.  相似文献   

Synthesis and protein tyrosine phosphatase 1B inhibition activities of two new synthetic bromophenols and their methoxy derivatives     

������  ʷ����  ��־ǿ 《中国海洋湖沼学报》2011,29(6):1237-1242

3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)-1,2-benzenediol (1) is a natural bromophenol isolated from the red algae Rhodomela confervoides that exhibits significant inhibition against protein tyrosine phosphatase 1B (PTP1B). Based on its activity, we synthesized two new synthetic bromophenols and their methoxy derivatives from vanillin using the structure of natural bromophenol 1 as a scaffold. The structures of these bromophenols were elucidated from 1H NMR, 13C NMR, and high resolution electron ionization mass spectrometry as 2,3-dibromo-1-(2p-bromo-6p-(3q,4q-dimethoxybenzyl)- 3p,4p-dimethoxybenzyl)-4,5-dimethoxybenzene(2),2,3-dibromo-1-(2p-bromo-6p-(2q-bromo-4q,5q-dimethoxy-benzyl)-3p,4p-dimethoxybenzyl)-4,5-dimethoxybenzene(3),3,4-dibromo-5-(2p-bromo-6p-(2q-bromo-4q,5q-dihydroxybenzyl)-3p,4p-dihydroxybenzyl)pyrocatechol(4)and 3,4-dibromo-5-(2p-bromo-6p-(3q,4q-dihydroxybenzyl)-3p,4p-dihydroxybenzyl)pyrocatechol (5).PTP1B inhibition activities of these compounds were evaluated using a colorimetric assay,and compounds 3 and 4 demonstrated interesting activity against PTP1B.  相似文献   

The suitability of using leaf area index to quantify soil loss under vegetation cover   总被引：1，自引：0，他引：1  

Wentai Zhang  Dongsheng Yu  Xuezheng Shi  Hongjie Wang  Zhujun Gu  Xiangyan Zhang  Manzhi Tan 《山地科学学报》2011,8(4):564-570

Soil erosion by water under forest cover is a serious problem in southern China. A comparative study was carried out on the use of leaf area index (LAI) and vegetation fractional coverage (VFC) in quantifying soil loss under vegetation cover. Five types of vegetation with varied LAI and VFC under field conditions were exposed to two rainfall rates (40 mm h⁻¹ and 54 mm h⁻¹) using a portable rainfall simulator. Runoff rate, sediment concentration and soil loss rate were measured at relatively runoff stable state. Significant negative exponential relationship (p < 0.05, R² = 0.83) and linear relationship (p < 0.05, R² = 0.84) were obtained between LAI and sediment concentration, while no significant relationship existed between VFC and sediment concentration. The mechanism by which vegetation canopy prevents soil loss was by reducing rainfall kinetic energy and sediment concentration. LAI could better quantify such a role than VFC. However, neither LAI nor VFC could explain runoff rate or soil loss rate. Caution must be taken when using LAI to quantify the role of certain vegetation in soil and water conservation.  相似文献   

Spatial and temporal variations in C₃ and C₄ plant abundance over the Chinese Loess Plateau since the last glacial maximum     

Z. Yao  H. WuM. Liang  X. Shi 《Journal of Arid Environments》2011,75(10):881-889

Stable carbon isotopes of soil organic matter from 12 sites in the southern Chinese Loess Plateau are reviewed to examine spatial and temporal patterns of C₃ and C₄ plants in the arid to semiarid monsoonal region during three key periods - last glacial maximum, mid-Holocene, and modern. We have tentatively corrected the effects of atmospheric CO₂ concentrations and precipitation amounts on the δ¹³C endmembers for C₃ plants to reconstruct the relative proportion of C₄ plants because the δ¹³C values of C₃ plants are variable under different CO₂ and climate conditions. The results indicate that C₄ grasses increase from northwest to southeast spatially, which is consistent with present-day increasing precipitation and temperature patterns. This suggests that for a monsoon-dominant arid to semiarid region, such as the Loess Plateau, warm-season rainfall is a primary factor limiting C₄ plants growth, and thus C₄ grasses have been outcompeted by C₃ grasses/shrubs under cold-dry climate conditions. However, temporal fluctuations in atmospheric CO₂ concentration may also affect plant growth through altering water-use efficiency (WUE). Enhanced drought caused by decreased WUE due to low atmospheric CO₂ concentrations during glacial periods, combined with a cold-dry climate, leads to a decline in C₄ grasses, canceling out any advantages gained from lowered atmospheric CO₂ concentrations. To reconstruct accurately the abundance of C₃ and C₄ plants in an ecosystem and explore their controlling factors, process-based vegetation models integrating CO₂ and climatic parameters interactive with plant physiology are necessary.  相似文献   

Influence of flow velocity and spatial heterogeneity on DNAPL migration in porous media: insights from laboratory experiments and numerical modelling   总被引：1，自引：0，他引：1  

Fei Zheng  Yanwei Gao  Yuanyuan Sun  Xiaoqing Shi  Hongxia Xu  Jichun Wu 《Hydrogeology Journal》2015,23(8):1703-1718

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