Septal patterns in Agetolites from the Xiazhen Formation (Upper Ordovician) at Zhuzhai,Yushan County,Jiangxi Province,South China     

SUN Ning  DongJin LEE  WANG XunLian 《中国科学:地球科学(英文版)》2014,57(2):247-257

Patterns of septal insertion were analyzed in three species of Agetolites from the Upper Ordovician in Yushan County,Jiangxi Province of China.Agetolites is a peculiar coral possessing features of both tabulate(e.g.,mural pores)and rugose corals(e.g.,well-developed septa).Septal patterns have long been considered to be indicative of the origin of corals,and the pattern of septal insertion in Agetolites has been known to be typical of rugosans.This study,however,reveals that the patterns in Agetolites are rather random and cannot be an indication of its rugosan affinity.It is suggested that Agetolites probably has a closer phylogenetic relation with tabulates than with either rugosans or scleractinians.Two insertion patterns of the first six septa were detected(Types Ⅰ and Ⅱ).Type I is interpreted as scleractinian pattern whereas Type II as typical pattern of rugosans.Types 1 and 2 are septal patterns of the second stage recognized in this study.Type 1 insertion occurs in six sectors located in the center of each interseptal space,suggesting scleractinian pattern of insertion.Type 2 insertion occurs in four sectors that are comparable with alar and counter sectors in rugose corals.Four patterns of the third(Types A–D)and fourth stages(Types a–d)of septal insertion have also been recognized in Agetolites.Type A only occurs in two adjacent sectors possibly due to the incompleteness of septal development.Type B presents rugosan pattern.Types C and D resemble scleractinian pattern in most aspects.Types a,b,and c present no clear attribution to rugosan or scleractinian pattern probably due to the incompleteness of septal development whereas Type d is observable in rugose corals.  相似文献   

Fluctuation of Cadmium Load on a Tide‐Influenced Waterfront Lake in the Middle‐Lower Reaches of the Yangtze River          下载免费PDF全文

Hua Wang  Yiyi Zhou  Yong Pang  Xianmin Wang 《洁净——土壤、空气、水》2014,42(10):1402-1408

  相似文献   

吕宋海峡西侧海域混合层盐度低频变化特征分析     

沈华 《海洋学研究》2014,32(1):11-18

利用WOD09和Argo剖面资料,结合SODA、OFES、GPCP和WHOI等资料分析了吕宋海峡西侧海域混合层盐度1984—2010年间的长期变化趋势和年代际变化特征,并利用混合层盐度平衡方程探讨了其变化机理。研究结果表明:(1)吕宋海峡西侧海域的盐度整体上呈现下降趋势,线性趋势为-0.020/a;(2)以1999年为界,吕宋海峡西侧海域的盐度在1999年之前为正距平,最大正距平值可达0.14,平均值为0.05,在1999年之后为负距平,最大负距平值为-0.22,平均值为-0.06;(3)影响该海域混合层盐度的长期变化趋势和年代际变化的主要因素为平流作用,特别是黑潮入侵的变化。  相似文献   

黑河下游绿洲植被优势种生物量空间分布及蒸腾耗水估算   总被引：2，自引：1，他引：1  

张华  张兰  赵传燕  彭守璋  郑祥霖 《地理科学》2014,34(7):876-881

基于典型样点试验,建立了研究区植被优势种柽柳、胡杨与苦豆子地上生物量与其生态参数关系模型;利用高分辨率遥感影像Geoeye-1对植被优势种进行分类得到生态参数,实现了其地上部分生物量空间分布估算;最后利用生物量与蒸腾系数关系,估算植被优势种蒸腾耗水。结果显示：植被优势种总生物量为2.53×10⁶t,河流距离对生物量影响显著。根据试验测得的植被优势种蒸腾系数估算出总蒸腾耗水量为10.89×10⁸t,柽柳、胡杨与苦豆子所占比例分别为12.94%,82.93%与4.13%。  相似文献   

鄂尔多斯盆地白垩系沙漠相沉积特征及其水文地质意义   总被引：15，自引：1，他引：14  

谢渊  王剑  江新胜  李明辉  谢正温  罗建宁  侯光才  刘方  王永和  张茂省  朱桦  王德潜  孙永明  曹建科 《沉积学报》2005,23(1):73-83

白垩纪鄂尔多斯盆地在燕山期抬升-沉降及气候演变的背景条件下,受水力、风力等地质作用,经历了早白垩世宜君-洛河期→环河期与罗汉洞期→泾川期两个沙漠沉积演化阶段。其中,洛河期和罗汉洞期是沙漠发育的两个主要时期,形成了旱谷、沙丘、丘间及沙漠湖等多类型沙漠亚相碎屑岩沉积。沙丘沉积砂岩作为白垩系沙漠相最主要的沉积岩石,具有分布稳定、厚度巨大、含盐量低、孔隙空间发育、储水性和透水性强等特点,不但具有良好的地下水赋存和循环条件,而且一般赋存着水质较好的地下水。  相似文献   

微量元素在湖积物、土壤的垂向分布与稻谷中的分配   总被引：22，自引：7，他引：15       下载免费PDF全文

廖启林  黄顺生  范迪富  吴新民  朱伯万  翁志华  华明  陈宝  冯金顺 《第四纪研究》2005,25(3):331-339

报道了“江苏省国土生态地球化学调查”项目有关湖积物、土壤柱微量元素垂向分布及稻谷样元素分配研究的初步成果。通过对有关样品元素含量的分析对比,指出洪泽湖沉积柱元素垂向分布与其动荡的沉积环境关系密切、太湖局部沉积物在其目前20cm以上深度存在人为重金属污染,这二湖沉积物中其氮与总有机碳含量呈显著正相关;认为城市化可使当地土壤环境受重金属等污染的深度显著加大、城市土壤环境受人为活动的影响要显著高于农村;发现Mo易富集于稻米、重金属与营养元素易富集于稻皮、各元素在米-谷间的分配关系不确定。  相似文献   

Statistical prediction of heavy rain in South Korea     

Keon Tae SOHN  Jeong Hyeong LEE  Soon Hwan LEE  Chan Su RYU 《大气科学进展》2005,22(5):703-710

1. Introduction In recent decades, extreme weather events seem to be growing in frequency and risk due to water-related disasters. According to the World Meteorological Or- ganization report (ISDR and WMO, 2004) on World Water Day, 22 March 2004, the economic losses caused by water-related disasters, including floods, droughts and tropical cyclones, are on an increasing trend as follows: the yearly mean in the 1970s was about 131 billion US dollars, 204 billion dollars in the 1980s, and …  相似文献   

Climate change signal analysis for Northeast Asian surface temperature     

Jeong-Hyeong LEE  Byungsoo KIM  Keon-Tae SOHN  Won-Tae KOWN  Seung-Ki MIN 《大气科学进展》2005,22(2):159-171

Climate change detection, attribution, and prediction were studied for the surface temperature in the Northeast Asian region using NCEP/NCAR reanalysis data and three coupled-model simulations from ECHAM4/OPYC3, HadCM3, and CCCma GCMs (Canadian Centre for Climate Modeling and Analysis general circulation model). The Bayesian fingerprint approach was used to perform the detection and attribution test for the anthropogenic climate change signal associated with changes in anthropogenic carbon dioxide (CO2) and sulfate aerosol (SO42-) concentrations for the Northeast Asian temperature. It was shown that there was a weak anthropogenic climate change signal in the Northeast Asian temperature change. The relative contribution of CO2 and SO42- effects to total temperature change in Northeast Asia was quantified from ECHAM4/OPYC3 and CCCma GCM simulations using analysis of variance. For the observed temperature change for the period of 1959-1998, the CO2 effect contributed 10%-21% of the total variance and the di  相似文献   

Impact of land use changes on surface warming in China   总被引：29，自引：1，他引：28  

ZHANG Jingyong  DONG Wenjie  WU Lingyun  WEI Jiangfeng  CHEN Peiyan  Dong-Kyou LEE 《大气科学进展》2005,22(3):343-348

Land use changes such as urbanization, agriculture, pasturing, deforestation, desertification and irrigation can change the land surface heat flux directly, and also change the atmospheric circulation indirectly, and therefore affect the local temperature. But it is difficult to separate their effects from climate trends such as greenhouse-gas effects. Comparing the decadal trends of the observation station data with those of the NCEP/NCAR Reanalysis (NNR) data provides a good method to separate the effects because the NNR is insensitive to land surface changes. The effects of urbanization and other land use changes over China are estimated by using the difference between the station and the NNR surface temperature trends. Our results show that urbanization and other land use changes may contribute to the observed 0.12℃ (10 yr)- 1 increase for daily mean surface temperature, and the 0.20℃ (10 yr)- 1 and 0.03℃ (10 yr)-1 increases for the daily minimum and maximum surface temperatures, respectively. The urban heat island effect and the effects of other land-use changes mayalso play an important role in the diurnal temperature range change. The spatial pattern of the differences in trends shows a marked heterogeneity.The land surface degradation such as deforestation and desertification due to human activities over northern China, and rapidly-developed urbanization over southern China, may have mostly contributed to the increases at stations north of about 38°N and in Southeast China, respectively. Furthermore, the vegetation cover increase due to irrigation and fertilization may have contributed to the decreasing trend of surface temperature over the lower Yellow River Basin. The study illustrates the possible impacts of land use changes on surface temperature over China.  相似文献   

热带大洋对纬向和经向风应力的联合响应   总被引：1，自引：0，他引：1       下载免费PDF全文

陈华  王彰贵  刘式适  邓自旺  闵锦忠 《地球物理学报》2005,48(5):985-991

考虑了经向风应力和纬向风应力联合作用下热带大洋的响应问题.结果表明,只有一阶的经向风应力或具有辐合辐散的经向风应力才对最后的速度场和位势场造成影响.零阶的扰动温跃层和纬圈流受风应力的直接驱动和Kelvin波、Rossby短波的影响,而Rossby短波由经向风应力直接造成;二阶模则受风应力的直接驱动和Rossby短波的作用,同时经向风应力也产生了附加的Rossby短波.另外,在西边界处存在很强的暖水补充到赤道的现象,经向风应力有使暖水向赤道输送的作用,而西风应力使西边界处的暖水向东输送.  相似文献