The impact of human activities on the flushing properties of a semi-enclosed lagoon: Xiaohai, Hainan, China   总被引：1，自引：0，他引：1  

Gong W  Shen J  Jia J 《Marine environmental research》2008,65(1):62-76

In this study, a Lagrangian particle tracking model driven by hydrodynamic fields was used to investigate the changes of flushing properties in Xiaohai Lagoon resulting from natural evolution and influences of human activities. Comparisons of residence times between 1936 and 2001 indicate that the flushing efficiency of the lagoon has deteriorated greatly during the past seven decades. Over this period, the average residence time of the lagoon has increased from 45 to 71 days, an increase of 59%. The Lagrangian residual velocity has decreased from 1936 to 2001 in the large portions of the lagoon, and the spatial distribution pattern of the residual current has changed significantly. The well-developed horizontal circulations in 1936 disappeared. Instead, the horizontal Lagrangian residual velocity showed uniformly seaward motion with reduced velocity in 2001. Human activities have incurred great impacts on the deterioration of flushing efficiency. The reduction of river inflow imposed the most significant impact, causing an increase of average residence time by 33%. The land reclamation in the lagoon came as the second most significant factor, causing an increase of 15%. Closure of the North Opening had posed minor impact. The model results suggest that restoring the river inflow, as well as the dredging of the tidal channel and the inner lagoon, should be the top proprieties for future water quality management.  相似文献   

福建建宁地区中元古代侵入岩的矿物标型特征及其成因探讨     

张之Shen  杨玲雅 《福建地质》1992,11(2):90-96

摘要福建建宁地区中元古代韩家、严塘二个岩体来自上地幔,其副矿物有28种。副矿物有三个结晶阶段,以富含自然铁、铬铁矿和富铪锆石为特征。锆石具高柱面指数和高锥面指数。变石英闪长岩和变英云闪长岩的锆石类型有二个主型和七个亚型。根据其副矿物标型组合及标型矿物特征,认为其物质来自幔源为主成因的岩浆。  相似文献   

川滇黔桂地区泥盆系层序地层分析   总被引：20，自引：1，他引：19  

覃建雄  陈洪德  田景春  彭军  侯中健  寿建峰  杨晓宁  沈安江  陈子炓 《沉积学报》2000,18(2):172-179

根据层序关键界面、体系域叠置关系及内部构型特征,结合生物地层资料,右江盆地泥盆系可划分为17个三级层序,其中下统 7个、中统 5个、上统 5个,包括 9个Ⅰ型层序、8个Ⅱ型层序,代表17次三级相对海平面变化产物。在此基础上,对不同沉积背景的层序进行了对比,建立了相应的层序格架模型。结果表明,不同沉积相带的层序内部构型和成因格架存在一定的差异,但由于海平面变化这一共同因素的影响,它们仍可进行对比和追踪。  相似文献   

LATE QUATERNARY FAULTING OF JIALI FAULT     

Ren Jinwei  Shen Jun  Cao Zhongquan  Wang Yipeng 《地学前缘》2000,(Z1)

LATE QUATERNARY FAULTING OF JIALI FAULT1　ChungS ,LoC ,LeeT ,etal.DiachronousupliftoftheTibetanplateaustarting 40Myrago[J].Nature ,1998,394:76 9～773. 2　ColemanM ,HodgesK .EvidenceforTibetanplateauupliftbefore 14Myragofromanewminimumageforeast westexten sion[J].Nature ,1995 ,374:49～ 5 2 . 3　HarlandWB ,ArmstrongRL ,CoxAV ,etal.Ageologictimescale 1989[J].Cambridge ,U .K :CambridgeUnivPress,1990 . 4　HarrisonTM ,CopelandP ,KiddWSF ,etal.RaisingTibet[J].…  相似文献   

THE NORTHWARD PROPAGATION OF THE ARC TECTONICS OF THE NORTHEAST PAMIR AND NORTHWEST TARIM BASIN     

Li Yingzhen  Shen Jun 《地学前缘》2000,(Z1)

THE NORTHWARD PROPAGATION OF THE ARC TECTONICS OF THE NORTHEAST PAMIR AND NORTHWEST TARIM BASINThisworkispartoftheresearchproject“themechanismofJiashistrongearthquakeswarmandprediction ofearthquakeriskinthenortheastPamir  相似文献   

STUDY ON THE BASIC IGNEOUS EVENT IN CENTRAL QIANGTANG, TIBET     

Li Cai  Yang Deming  Wang Tianwu  Yang Rihong  Liu ShenWT  ”BX 《地学前缘》2000,(Z1)

STUDY ON THE BASIC IGNEOUS EVENT IN CENTRAL QIANGTANG, TIBET  相似文献   

Extraction of plasmid-like DNA and high-quality total DNA from Porphyra yezoensis   总被引：3，自引：0，他引：3  

Guo Baotai  Dai Jixun  Shen Songdong  Bi Yuping  Shan Lei  Li Guangcun 《海洋学报(英文版)》2000,19(2):83-88

I~ODWrIONExtraction of DNA from Porphyra po~nsis is very difficult due tO its high content ofpolysaccharides. TO avoid the interference Of POlysaccharides, HOng et al. (1992) used LiCI tosoften Porphyra thalli cells to release DNA directly without lysing the thalli, hoWever, the procedure is problematic in the isolation of high-quality DNA. Kitade et al. (1996) established a complicated procedure which includes the grindiflg of material in liquid nitrogen, lysing of material inextra…  相似文献   

南四湖底泥污染及其变化过程     

张祖陆  孙娟  王琳  Shen Ji 《地理学报(英文版)》2004,14(1):121-125

In order to research the changing process of the pollution from the formation of Nansihu Lake, this study determined the isotope age and depositional rate and analyzed the organic geo-chemical quotas and heavy metal quotas of two sedimentary profiles of Weishan and Dushan lakes. Research results showed that from the formation of Nansihu Lake, the change of the pollution could be divided into four phrases. At the early phrase of the formation, the organic matters of the lake mainly derived from the exotic matters and had a close relation to the effect on the water and sands from the Huanghe (Yellow) River. At the middle and late phrases of the development, the endogenous matters of the lake became the main and stable source of the organic matters. The overflow of the Huanghe River, the excavation of the Grand Canal and the cut of trees caused the changes of the historic pollution. In recent 20 years, the modem industrial pollution from the organic matters and heavy metals has an increasingly heavy tendency.  相似文献   

广东雷电活动的对流潜热特征   总被引：2，自引：1，他引：1  

杨兆礼  万齐林  陈子通 《广东气象》2011,33(6):43-46

基于LIS和Latent Heat Research Product等TRMM卫星产品及广东省闪电定位仪观测资料对广东雷电活动进行了分析,结果发现:粤北、粤东和粤西等convLHMean(对流潜热)上下层差值为50K/h以上的较大正值区域基本对应着较高的山脉地形,说明对流潜热的垂直变化与广东地区山地抬升作用有一定的关系...  相似文献   

Background Seismicity and Its Application to Seismic Hazard Assessment in the North China Region     

Wang Hui  Cao Jianling  Shen Xuhui 《中国地震研究》2011,25(4):395-408

The historical earthquake activity is intense in the North China region. However, no middle-sized earthquakes have occurred in the last decades in the region since the MS6.2 earthquake in the Zhangbei region in 1998. The quiescence of moderate and strong earthquakes is quite prominent in North China. In this paper, we use small earthquake records in 1970~2009 to study background seismic activity in the North China region. The spatial distributions of seismic parameters are presented, including b-value, the maximum magnitude and annual occurrence probability of earthquakes of M≥6.0. Our results show regions with low b-value that include the Yuncheng region in the Shanxi rift, the Suqian region located in the Tancheng-Lujiang fault zone and the Shijiazhuang region in the Taihangshan block. Our analysis on the synthetic spatial pattern of seismicity indicate that seismicity in the North China region is mainly affected by the regional dynamic factors of deep structures.  相似文献