Community Structure and Dynamics of Phytoplankton in the Western Subarctic Pacific Ocean: A Synthesis   总被引：1，自引：1，他引：1  

Hongbin Liu  Koji Suzuki  Hiroaki Saito 《Journal of Oceanography》2004,60(1):119-137

The phytoplankton community in the western subarctic Pacific (WSP) is composed mostly of pico- and nanophytoplankton. Chlorophyll a (Chl a) in the <2 μm size fraction accounted for more than half of the total Chl a in all seasons, with higher contributions of up to 75% of the total Chl a in summer and fall. The exception is the western boundary along the Kamchatka Peninsula and Kuril Islands and the Oyashio region where diatoms make up the majority of total Chl a during the spring bloom. Among the picophytoplankton, picoeukaryotes and Synechococcus are approximately equally abundant, but the former is more important in term of carbon biomass. Despite the lack of a clear seasonal variation in Chl a concentration, primary productivity showed a large seasonal variation, and was lowest in winter and highest in spring. Seasonal succession in the phytoplankton community is also evident with the abundance of diatoms peaking in May, followed by picoeukaryotes and Synechococcus in summer. The growth of phytoplankton (especially >10 μm cell size) in the western subarctic Pacific is often limited by iron bioavailability, and microzooplankton grazing keeps the standing stock of pico- and nano-phytoplankton low. Compared to the other HNLC regions (the eastern equatorial Pacific, the Southern Ocean, and the eastern subarctic Pacific), iron limitation in the Western Subarctic Gyre (WSG) may be less severe probably due to higher iron concentrations. The Oyashio region has similar physical condition, macronutrient supply and phytoplankton species compositions to the WSG, but much higher phytoplankton biomass and primary productivity. The difference between the Oyashio region and the WSG is also believed to be the results of difference in iron bioavailability in both regions. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

西太平洋翁通-爪哇海台晚第四纪浮游有孔虫群与古温度变化   总被引：3，自引：1，他引：3  

金海燕  翦知湣  刘东升 《海洋地质与第四纪地质》2003,23(4):65-71

通过对翁通-爪哇海台ODP807站的浮游有孔虫进行定量分析,结合已有的氧、碳稳定同位素数据,揭示了晚第四纪赤道西太平洋表层海水温度及上部海水垂向结构的冰期／间冰期变化特征。研究表明,自530kaBP以来,西太平洋暖池区的表层海水温度(SST)和温跃层深度(DOT)都经历过显著的变化,其中年平均SST的冰期／间冰期变化幅度达4．2℃,DOT的波动范围更是超过100m,这进一步论证了西太平洋暖池的不稳定性。频谱分析还揭示出SST和DOT变化不仅具有典型的100ka冰期／间冰期旋回,还有热带地区特有的半岁差周期,说明研究区的古海洋学变化既有高纬驱动的作用,也有热带驱动的影响。  相似文献   

青藏高原中部湖泊沉积物中Zr/Rb值及其环境意义   总被引：14，自引：1，他引：14  

陈诗越  王苏民  金章东  沈吉 《海洋地质与第四纪地质》2003,23(4):35-38

由于青藏高原及其周边地区构造复杂,湖泊沉积物中的粒级差别很大,单一的测量方法往往难以奏效。Rb、Zr是表生地球化学过程中的稳定元素,但它们之间也存在显著差别,Rb一般富集在细颗粒中,Zr则在粗颗粒中含量较高。研究发现,湖泊沉积物中Zr/Rb比值与粘土(<2μm)含量存在显著相关,Zr/Rb值反映了湖泊沉积物的粒度大小。Zr/Rb比值所揭示的青藏高原中部280万年来经历的3次大的环境演化过程与岩性变化、孢粉指标反映的环境特征是一致的。  相似文献   

理县黄土地层与环境记录   总被引：3，自引：0，他引：3  

王书兵  蒋复初  田国强 《海洋地质与第四纪地质》2006,26(3):115-119

理县黄土堆积厚度为7.30 m,可分为S0、S1古土壤层和L1黄土层。光释光结果显示,理县黄土沉积始于末次间冰期,约130 kaBP。磁化率、粒度、碳酸盐含量等经典气候替代指标分析表明,它们可以反映青藏高原东部气候环境变迁。环境记录显示,末次冰期间冰阶(即氧同位素3阶段)期间该区呈现出极端冷湿的气候环境。理县地区气候演化更接近于印度季风强度记录的变化,而与格陵兰冰心和深海氧同位素记录相似性稍差。  相似文献   

The recreational fishery off Majorca Island (western Mediterranean): some implications for coastal resource management   总被引：3，自引：0，他引：3  

Morales-Nin  Beatriz; Moranta  Joan; Garcia  Cristina; Tugores  Maria Pilar; Grau  Antoni Maria; Riera  Francisco; Cerda  Margalida 《ICES Journal of Marine Science》2005,62(4):727-739

  相似文献   

Validity of sea surface temperature observed with the TRITON buoy under diurnal heating conditions     

Yoshimi Kawai  Hiroshi Kawamura  Sumio Tanba  Kentaro Ando  Kunio Yoneyama  Norio Nagahama 《Journal of Oceanography》2006,62(6):825-838

In order to investigate the validity of buoy-observed sea surface temperature (SST), we installed special instruments to measure near-surface ocean temperature on the TRITON buoy moored at 2.07°N, 138.06°E from 2 to 13 March 2004, in addition to a standard buoy sensor for the regular SST measurement at 1.5-m depth. Large diurnal SST variations were observed during this period, and the variations of the temperatures at about 0.3-m depth could be approximately simulated by a one-dimensional numerical model. However, there was a notable discrepancy between the buoy-observed 1.5-m-depth SST (SST_1.5m) and the corresponding model-simulated temperature only during the daytime when the diurnal rise was large. The evaluation of the heat balance in the sea surface layer showed that the diurnal rise of the SST_1.5m in these cases could not be accounted for by solar heating alone. We examined the depth of the SST_1.5m sensor and the near-surface temperature observed from a ship near the buoy, and came to the conclusion that the solar heating of the buoy hull and/or a disturbance in the temperature field around the buoy hull would contribute to the excessive diurnal rise of the SST_1.5m observed with the TRITON buoy. However, the temperature around the hull was not sufficiently homogenized, as suggested in a previous paper. For the diurnal rise of the SST_1.5m exceeding 0.5 K, the daytime buoy data became doubtful, through dynamics that remain to be clarified. A simple formula is proposed to correct the unexpected diurnal amplitude of the buoy SST_1.5m.  相似文献   

上新世——早更新世青藏高原北缘隆升的磁性地层学证据   总被引：9，自引：0，他引：9  

郑洪波  陈惠忠  靳鹤龄  李孝泽  董光荣 《海洋地质与第四纪地质》2002,22(2):57-62

对新疆叶城剖面西域砾岩及下伏第三纪地层的磁性地层学研究表明 ,西域砾岩的沉积时代为晚上新世至早更新世 ,磁性地层年龄为 3.5至 <1.8Ma。阿图什组沉积于早上新世 ,古地磁年龄为 4 .6～ 3.5 Ma。阿图什组以砂岩和粉砂岩为主夹薄层砾岩 ,为河流相及冲积扇前缘相。西域砾岩以厚层砾岩为主夹风成粉砂岩 ,为典型洪积—冲积扇堆积。西域砾岩的沉积反映了青藏高原北缘晚上新世至早更新世强烈的隆起和剥蚀  相似文献   

9810号台风期间厦门近岸海域磷的分布特征   总被引：1，自引：0，他引：1  

吴国琳  杨逸萍 《台湾海峡》2001,20(1):84-90

于1998年10号台风期间及台风解除后一周内，对九龙江口和西海域表层水中总磷（TP）、溶解态无机磷（DIP）、溶解态有机磷（DOP）、颗粒态磷（PP）、颗粒态无机磷（PIP）和颗粒态有机磷（POP）进行了为期9d（10月26日至11月3日）的现场观测。根据观测结果，讨论了台风对上述各形态磷的分布特征的影响，认为台风伴随的增水、入海径流量的骤增和底质再悬浮的加剧导致表层水体中各形态磷含量的短期增加。  相似文献   

Primary productivity in the western tropical Pacific and equatorial warm waters   总被引：1，自引：0，他引：1  

Chen Xingqun  Zhang Ming  Chen Qihuan 《海洋学报(英文版)》2001,20(1):117-129

ＩＮＴＲＯＤＵＣＴＩＯＮＢｙｓｔｕｄｙｉｎｇｃｈｌｏｒｏｐｈｙｌｌａｎｄｐｒｉｍａｒｙｐｒｏｄｕｃｔｉｖｉｔｙｉｎｏｃｅａｎ ,ｅｉｔｈｅｒｉｎｔｈｅｂｉｇ ｓｃａｌｅｏｒｉｎｔｈｅｓｍａｌｌｓｃａｌｅ ,ｔｈｅｐｒｏｄｕｃｔｉｖｉｔｙｄｉｓｔｒｉｂｕｔｉｏｎａｎｄｖａｒｉａｔｉｏｎｏｆｍａｒｉｎｅｏｒｇａｎｉｃｍａｔｅｒｉａｌｉｎｔｈｅｔｅｍｐｏ ｒａｌａｎｄｓｐａｔｉａｌｃａｎｂｅｕｎｄｅｒｓｔｏｏｄ .Ｔｈｅｓｅａａｒｅａｓ ,ｓｉｔｕａｔｉｎｇｉｎｔｈｅｗｅｓｔｅｒｎｔｒｏｐｉｃａｌＰａｃｉｆｉｃ…  相似文献   

青藏高原边缘地区晚更新世人类遗存与生存模式   总被引：7，自引：1，他引：6       下载免费PDF全文

高星  周振宇  关莹 《第四纪研究》2008,28(6):969-977

自20世纪80年代在青海小柴旦发现旧石器遗存以来,青藏高原边缘地区已经发现了10余处旧石器时代遗址,年代属晚更新世晚期。这些遗存显示,古人类在距今30ka左右开始尝试向这些高海拔地区扩散,但直至距今15ka以后才有更多的人群迁徙至此。通过对这些遗存分布位置、古环境特征、年代测定和石器技术、组合分析,得以管窥古人类对该地区的开发利用过程,并进而阐释史前人类技术发展、生存模式演变和古环境的耦合关系。  相似文献