155°E断面夏季温、盐度的基本特征

有关太平洋海洋环流,特别是对亚热带(又称副热带)、热带和赤道带环流的调查研究,近数十年来在国内、外海洋学界已蓬勃展开。其中,日本气象厅于1967年至今在137°E断面上每年进行1-2次定期海洋观测,并于1972-1979年、1987-1995年在155°E断面上每年夏季进行一次观测。根据上述经向断面观测资料,许多学者对137°E断面的海流结构,温、盐分布,水团及其变异,以及与ENSO现象的关系作了细致的分析研究(邹娥梅等,1993;顾玉荷,1996;Guan,1986;Masuzawa,1967);关于155°E断面的研究,则着重于太平洋赤道区域海流结构和它的变异及其与ENSO现象的关系等(顾玉荷,1990;Guan,1986)。本文拟根据155°E断面1972-1979年夏季(6-7月)日本气象厅的海洋水文气象观测资料(其中1974年无资料),分析研究该断面(北亚热带、热带和赤道带海域)的温、盐度分布特征和热、盐含量及其年际变异,并探讨其与ENSO现象之间的关系。 155°E断面北起30°N,南至11°S,自北向南横穿北亚热带、热带、赤道带和南半球热带。测站的密度以1975-1977年最密(设55个测站),1972年和1973年次之(分别设测站33个和40个),1978年和1979年测站稀疏,仅为15个和12个。采样深度间隔于30m以浅为10m,50-150m层间为25m,150-300m层间为50m,300-1000m层间为100m。图1为断面的位置和站位分布(5028站至5058站每相邻两站中间省略一站位)。 为了便于分析断面上各纬度带的水文特征及年际变异,将该断面自北向南划分为4个纬度带,即北亚热带(18°-30°N)、北半球热带(2°-18°N,以下简称北热带)、赤道带(2°N-2°S)和南半球热带(2°S以南,以下简称南热带)。其中北热带又划分为北赤道流区(8°-18°N)和北赤道逆流区(2°-8°N)。     

Prehistoric damaging earthquake promoted the decline of "Heluo Ancient State" in Early China

The emergence of the "Ancient State" is considered an important stage in the discourse on human civilizations.Based on its complex and hierarchical social structure,the Shuanghuaishu site of Henan Province is regarded as an "Ancient state",specifically the "Heluo Ancient State".The site is situated in the middle reaches of the Yellow River region and played a key role in prehistoric China.However,the reasons behind its decline are unclear.Here,we conducted an integrated investigation of the arch...     

Rectifying the Neoproterozoic Stratigraphic Framework of Eastern Jiangnan Orogen, Southeast China

Studies on the metamorphic and related magmatic rocks within the Jiangnan Orogen, southern China, are important to understand the formation and evolution of this Neoproterozoic orogen because they can provide evidence for revealing the tectonic evolution of the South China Block. Following on from earlier attempts at stratigraphic correlation and creating a framework for the low-grade metamorphosed basement, new first-hand information on the composition and deformation of the East Jiangnan Orogen basement indicates that the sedimentary rocks in the north are composed of the sequential Shangxi Group (Gp) and the overlying Likou Gp, with a clear regional unconformity in between. The Likou Gp includes the Zhentou Formation (Fm.) and the Dengjia Fm., with the previously named Puling Fm. only basalt interbeds within the Dengjia Fm. The Xucun granodiorite pluton of ~830 Ma intrudes the Shangxi Gp, thereby resulting in a 100 m-wide hornfels zone within the wall rocks, indicating that the formation of the group occurred earlier than that of the pluton. By contrast, the southern metamorphic rocks of the Xikou Gp and the overlying Jingtan Fm. are flaky, disordered, and strongly deformed. The Jingtan Fm. is roughly equivalent to the Heshangzhen Gp and includes the Zhoujiacun conglomerates in the lower part and a rhyolite in the upper part with interbedded basalt. This assessment of Neoproterozoic stratigraphic sequences and magmatic rocks in the east of the Jiangnan Orogen differs from and rectifies previous studies, emphasizing that explanation of analytical results, particularly geochronology, should be consistent with facts gathered in the field.     

岩溶区砂糖桔短期种植对土壤氮转化过程的影响

利用¹⁵N同位素成对标记法并结合MCMC数值模型,研究岩溶区乔灌地开垦种植砂糖桔4年后土壤氮转化特征。结果显示:乔灌地开垦种植砂糖桔后,土壤有机氮矿化速率由2.93 mg N·kg^-1·d^-1显著下降至0.60 mg N·kg^-1·d^-1,土壤无机氮的供应能力降低,土壤有机氮矿化速率与土壤有机碳、全氮和全钙含量呈显著正相关性,与铁、铝、钾和黏粒比例呈显著负相关性;土壤铵态氮微生物同化速率由1.76 mg N·kg^-1·d^-1显著降低为0.10 mg N·kg^-1·d^-1,在砂糖桔地铵态氮微生物同化速率与有机氮矿化速率的比值仅为0.17。乔灌地土壤自养硝化速率高达11.06 mg N·kg^-1·d^-1,而硝态氮微生物同化作用微弱,硝态氮异化还原速率仅为0.64 mg N·kg^-1·d^-1,导致硝态氮净产生速...