Feeding ecology of mesopelagic zooplankton of the subtropical and subarctic North Pacific Ocean determined with fatty acid biomarkers     

S.E. Wilson  D.K. Steinberg  F.-L.E. Chu  J.K.B. Bishop 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(10):1278-1294

Mesopelagic zooplankton may meet their nutritional and metabolic requirements in a number of ways including consumption of sinking particles, carnivory, and vertical migration. How these feeding modes change with depth or location, however, is poorly known. We analyzed fatty acid (FA) profiles to characterize zooplankton diet and large particle (>51 μm) composition in the mesopelagic zone (base of euphotic zone ?1000 m) at two contrasting time-series sites in the subarctic (station K2) and subtropical (station ALOHA) Pacific Ocean. Total FA concentration was 15.5 times higher in zooplankton tissue at K2, largely due to FA storage by seasonal vertical migrators such as Neocalanus and Eucalanus. FA biomarkers specific to herbivory implied a higher plant-derived food source at mesotrophic K2 than at oligotrophic ALOHA. Zooplankton FA biomarkers specific to dinoflagellates and diatoms indicated that diatoms, and to a lesser extent, dinoflagellates were important food sources at K2. At ALOHA, dinoflagellate FAs were more prominent. Bacteria-specific FA biomarkers in zooplankton tissue were used as an indicator of particle feeding, and peaks were recorded at depths where known particle feeders were present at ALOHA (e.g., ostracods at 100–300 m). In contrast, depth profiles of bacterial FA were relatively constant with depth at K2. Diatom, dinoflagellate, and bacterial biomarkers were found in similar proportions in both zooplankton and particles with depth at both locations, providing additional evidence that mesopelagic zooplankton consume sinking particles. Carnivory indices were higher and increased significantly with depth at ALOHA, and exhibited distinct peaks at K2, representing an increase in dependence on other zooplankton for food in deep waters. Our results indicate that feeding ecology changes with depth as well as by location. These changes in zooplankton feeding ecology from the surface through the mesopelagic zone, and between contrasting environments, have important consequences for the quality and quantity of organic material available to deeper pelagic and benthic food webs, and for organic matter sequestration.  相似文献   

PHYSICAL GEOGRAPHICAL BACKGROUND OF THE CULTURE OF TRADITIONAL CHINESE RESIDENTIAL ARCHITECTURE     

储少莹  沙润  石高俊 《中国地理科学(英文版)》1999,9(1):26-32

ThetheSisistoexplainthebasicfactorsreferringtothetraditionalChineseresidentialarchitecturebasicallyfinalizedintheMingandQingdynastiesinthecountry'sspecificphysicalenvironment.Restrainedbyaxialfactors,itadaptsitselftotheself-sufficientnatural~nomy.Itisfiexiblydesigned,rsoablyfunctioned,economicallyconstructedandfeaturedbyremarkablelocalcharacteristics.IINFLUENCEOFCLIMATEONTRADITIONalarSIOCNTIAnANCnITh~arNinetyPercentofChina'spopulationinhabitstheeasternareawithinthedemarcati…  相似文献   

Observational constraints of sterile neutrinos in galaxies     

M. H. Chan  M.-C. Chu 《Astrophysics and Space Science》2009,319(2-4):143-147

We study a model in which degenerate sterile neutrinos account for galactic dark matter. We fit the rotation curves of 5 dwarf galaxies with the degenerate sterile neutrinos in hydrostatic equilibrium. Also we estimate the range of sterile neutrino mass by calculating the upper and lower bounds of the mass densities of sterile neutrino halos in the outermost regions of 21 normal galaxies. The observed rotation curves of 5 dwarf galaxies and 21 normal galaxies are consistent with having sterile neutrinos with mass (26–30) eV, and the similarity of the rotation curves of different galaxies emerges naturally in our model.  相似文献   

T/P�״�߶ȼƺ���ɢ��ϵ��½�ر���۲�Ӧ��     

褚永海  李建成  金涛勇  汪海洪 《大地测量与地球动力学》2009,29(3):104-108

????13??T/P???????????????????????????????????????????????????????????????????????????????????Ubari-Murzuq????????????????????????????????????????′????????????????????????С?????Ku???κ?C???ι?????????????????????????????Ｐ???????仯??????  相似文献   

First cosmic ray exposure dating (in situ produced 10Be) of the late pleistocene and holocene glaciation in the Nanhutashan Mountains (Taiwan)     

J. Carcaillet  L. L. Siame  H.‐T. Chu  D. L. Bourls  W.‐C. Lu  J. Angelier  P. Dussouillez 《地学学报》2007,19(5):331-336

In Taiwan, efficient climate‐driven strong erosion processes are the leading cause for low preservation of geomorphic landforms. Despite the absence of present‐day glaciers, glacial relicts have been reported in high altitude areas. These scarce landforms provide opportunities for reconstructing the timing of the last deglaciation in a region where glacial history is poorly documented. We have collected boulders and striated bedrocks in the Nanhutashan area and calculated surface exposure ages based on in‐situ produced ¹⁰Be concentrations. The oldest glacial remains, dated at 11.1 ± 3.3 ka, correspond to the last glacial advance. The Holocene is characterized by a continuous retreat of the ice‐cap until at least 7.2 ± 1.0 ka. Our results are in agreement with a scenario where changes of monsoon regimes lead to a strong reduction of the winter monsoon during the early Holocene, causing a decrease of snow supply and disequilibrium of the hydrological budget.  相似文献   

南极半岛东北海域表层沉积有机质来源及其沉积环境     

韩喜彬  赵军  初凤友  潘建明  唐灵刚  许冬  边叶萍  葛倩 《海洋学报》2015,37(8):26-38

采用气相色谱-质谱技术对南极半岛东北海域海底表层沉积物的总有机碳、有机质碳同位素(δ13 Corg)和生物标志化合物等进行了测试分析。研究区表层沉积物总有机碳TOC平均值高于现代深海沉积物中的平均含量。δ13 Corg的变化说明该海域有机碳来源呈海洋水生生物来源和陆源混合的特征。正构烷烃的峰型分布、主峰碳、饱和烃轻重比C-21/C+22和(C21+C22)/(C28+C29)、甾烷组合和藿烷组合证实研究区西部表层沉积物有机质来源以陆源高等植物为主,其陆源可能来自于附近的南极半岛和南舍得兰群岛;研究区东部表层沉积物有机质来源偏以海源为主,且以低等浮游生物、藻类及细菌生物等海源输入为主。碳优势指数(Carbon preference index,CPI)、奇偶优势指数(Odd-even Predominance,OEP)和甾烷C29ααα20S/(20S+20R)比值显示研究区D1-7站位和D5-9沉积物有机质演化程度较高,D5-2和D2-4站位的有机质演化程度低,其他站位介于中间状态。饱和烃中姥鲛烷、植烷及其比值(Pr/Ph)等组合显示研究区西部以氧化-弱还原的沉积环境为主,其可能是受高温低盐别林斯高晋海水流和附近火山喷发的影响所致;研究区东部以还原—强还原沉积环境为主,可能是受低温高盐的威德尔底层水(WSBW)和威德尔海深层水(WSDW)影响所致。  相似文献   

富钴结壳中矿物组成对稀土元素分布的制约     

张平萍  初凤友  李小虎 《海洋学报》2015,37(5):136-147

为探讨富钴结壳中矿物组成对稀土元素分布的制约,对约翰斯顿岛富钴结壳中矿物组成及稀土元素特征进行了研究。依据主要矿物组成,富钴结壳可以分为3种类型,分别命名为A、B、C。由A到C,水羟锰矿含量逐渐降低,B类中磷灰石含量最高,C类中水钠锰矿和钙锰矿含量最高。A类结壳中富集REE3+、Ce,B类结壳中富集Ce和Y。A类富钴结壳中,REE3+、Y以专属吸附的方式富集在铁氧化物上,Ce3+氧化成Ce4+与其他REE分离,吸附在锰矿物上。B类结壳中,稀土元素主要以独立矿物的形式存在,另有部分Ce、LREE3+吸附于铁相中,部分Y存在于磷灰石中。C类结壳中,稀土元素主要赋存在锰矿物中,部分Y存在于磷灰石中。  相似文献   

Using Shoreline Video Assessment for coastal planning and restoration in the context of climate change in Kien Giang,Vietnam     

Van Cuong  Chu  Russell  Michael  Brown  Sharon  Dart  Peter 《Ocean Science Journal》2015,50(2):413-432

Kien Giang, bordering Cambodia in the Mekong River Delta, is one of the two most vulnerable provinces in the region to coastal erosion and flooding. Coastal protection can conflict with current land use and economic development activities. The conditions of the mangrove forest and mainland coastline of the Kien Giang province were assessed using the Shoreline Video Assessment Method (SVAM) backed up with information from satellite images. Half of the 206 km Kien Giang coastline has been eroded or is being eroded. Protective mangrove forests naturally occurred in 74% of the coastline but have been under threat from illegal cutting, erosion and coastal retreat. Accurate information on the state of the coastline and mangrove forest health provided invaluable data for developing a new coastal rehabilitation plan to guard against future sea level rise. In contrast to the current boundary management of land and natural resources, this plan divided the provincial coastline into 19 sections based on the landscape condition and exposure to erosion. Priority strategic actions for erosion management, mangrove restoration and sustainable livelihood development for local communities for each section of coast were developed based on an integrated cross sectoral approach and practical experience in the Conservation and Development of the Kien Giang Biosphere Reserve Project.

  相似文献   

A multi-proxy reconstruction of spatial and temporal variations in Asian summer temperatures over the last millennium   总被引：1，自引：0，他引：1  

Feng?Shi  Quansheng?GeEmail author  Bao?Yang  Jianping?Li  Fengmei?Yang  Fredrik?Charpentier?Ljungqvist  Olga?Solomina  Takeshi?Nakatsuka  Ninglian?Wang  Sen?Zhao  Chenxi?Xu  Keyan?Fang  Masaki?Sano  Guoqiang?Chu  Zexin?Fan  Narayan?P.?Gaire  Muhammad?Usama?Zafar 《Climatic change》2015,131(4):663-676

To investigate climate variability in Asia during the last millennium, the spatial and temporal evolution of summer (June–July–August; JJA) temperature in eastern and south-central Asia is reconstructed using multi-proxy records and the regularized expectation maximization (RegEM) algorithm with truncated total least squares (TTLS), under a point-by-point regression (PPR) framework. The temperature index reconstructions show that the late 20th century was the warmest period in Asia over the past millennium. The temperature field reconstructions illustrate that temperatures in central, eastern, and southern China during the 11th and 13th centuries, and in western Asia during the 12th century, were significantly higher than those in other regions, and comparable to levels in the 20th century. Except for the most recent warming, all identified warm events showed distinct regional expressions and none were uniform over the entire reconstruction area. The main finding of the study is that spatial temperature patterns have, on centennial time-scales, varied greatly over the last millennium. Moreover, seven climate model simulations, from the Coupled Model Intercomparison Project Phase 5 (CMIP5), over the same region of Asia, are all consistent with the temperature index reconstruction at the 99 % confidence level. Only spatial temperature patterns extracted as the first empirical orthogonal function (EOF) from the GISS-E2-R and MPI-ESM-P model simulations are significant and consistent with the temperature field reconstruction over the past millennium in Asia at the 90 % confidence level. This indicates that both the reconstruction and the simulations depict the temporal climate variability well over the past millennium. However, the spatial simulation or reconstruction capability of climate variability over the past millennium could be still limited. For reconstruction, some grid points do not pass validation tests and reveal the need for more proxies with high temporal resolution, accurate dating, and sensitive temperature signals, especially in central Asia and before AD 1400.  相似文献   

梭梭(Haloxylon ammodendron)主根周围土壤特征   总被引：1，自引：0，他引：1  

楚新正  马倩  马晓飞  徐莉  马婕 《中国沙漠》2014,34(1):170-175

通过建立米级的空间尺度进行分层取样,研究了准噶尔盆地南缘建群种——梭梭(Haloxylon ammodendron)主根周围土壤的含水率、容重、pH值、电导率和养分含量的变化状况。结果表明:(1)土壤含水量在表层5cm处最小,土壤容重在0~40cm土层变动幅度不大,但随着与茎基垂线距离的增加,二者出现显著变化(p0.05)。(2)土壤pH值和电导率在主根区周围呈现聚集现象,最大聚集率均在0~1m圈层,但随着距离的增加,土层深度逐渐成为主导因素。(3)土壤养分在表层5cm处聚集,但水平聚集范围中除有机质和全氮可扩增到3~4m外,全磷和速效养分均在0~2m。本研究结论对于荒漠区耐盐性植被的合理密植有一定的理论意义。  相似文献