楚科奇海和加拿大海盆表层沉积物中好气异养细菌的地理分布

本文用MPN法测定楚科奇海和加拿大海盆表层沉积物中好气异养细菌(GAB)的含量,并对其地理学分布进行分析。结果表明,研究区GAB的检出率高达100%。4℃时GAB的含量范围、平均含量为4.00×102-2.40×106个.g-1、1.71×106个.g-1。25℃时GAB的含量范围、平均含量为2.40×105-2.40×107个.g-1、1.10×107个.g-1。无论是含量范围,还是平均含量,均是25℃时的培养结果大于4℃时的培养结果。GAB含量的地理分布趋势是随纬度增高,含量呈降低趋势。在经度变化上则为由东向西,含量呈降低趋势。对沉积物所处水深的分析,表明其在4℃培养得出来的GAB含量随水深增加有下降的趋势,25℃培养出来的GAB含量受环境影响较小,与水深变化关系不明显。     

白令海和楚科奇海水文特征和水团结构的初步分析

根据我国首次北极科学考察所获 CTD资料 ,分析了白令海和楚科奇海的水文特征和水团结构。研究表明 :(1 )该两海域温、盐度的分布有着明显的区域性差异。楚科奇海的温、盐度普遍低于白令海。 (2 )夏季 ,白令海大部分水域温度垂直分布的突出特点是 :在 2 0 m和 2 5 0 m间存在温度低于 3°C的中层冷水。 (3 )在楚科奇海北纬 70°以北海域 ,不论是水温或盐度皆明显减小 ,从而在此区域形成强的温、盐度锋带。 (4)在白令海存在三种水团 ,而楚科奇海的水团则大致分为两类     

2008年夏季楚科奇陆架海域近底层水温大幅快速变化事件研究

2008年夏季中国第3次北极科学考察期间,利用锚碇潜标对北冰洋楚科奇陆架海域进行了为期33 d的海流剖面、近底层温度与盐度连续观测。观测数据显示楚科奇陆架海域近底层海水温度出现了两次较大幅度的快速升降现象。结合此次科学考察R断面温盐深仪(CTD)观测资料、以及卫星遥感海表温度(SST)和海表风场等资料,综合分析表明:观测到的这种快速升、降温现象不仅发生在近底层;这种快速升、降温现象应该是由海水温度锋面在夏季整体缓慢北移的同时存在短暂南北摆动所导致;温度锋面的季节性北移属于北极气候特征,而温度锋面短暂的南北摆动则与短期天气过程有关。     

Application of an optical nitrate profiler to high- and low-turbidity coastal shelf waters

Here, we report the results of high-resolution nitrate measurements using an optical nitrate profiler(in situ ultraviolet spectrophotometer, ISUS) along transect across a high-turbidity shelf(East China Sea) and a lowturbidity shelf(Chukchi Sea). The ISUS-measured nitrate concentrations closely reproduced the results measured by conventional bottle methods in low-turbidity waters. However, for high-turbidity waters of the East China Sea(salinity<30), a correction factor of 1.19 was required t...     

融冰期北极楚科奇海陆架中心区硅限制与来源补充

相对氮亏损(N:P约为7,小于16)的太平洋入流水携带的营养盐是支撑北冰洋上层生态系统的重要物质基础。海冰消退,光限制消失,楚科奇海陆架存在强烈的营养盐消耗与利用,广泛认为其表现为氮限制,因此该区域重点关注氮元素循环,对于硅元素的相关研究较少。本文基于2016年中国第七次北极科学考察和中国-俄罗斯首次联合北极科学考察两个同步进行的航次调查结果,全面展示了融冰期整个楚科奇海陆架区的营养盐分布格局。结果显示,硝酸盐和亚硝酸盐表层基本耗尽;硅酸盐表现为中心低,周围高,陆架中心区是强烈的硅限制区域,受到硅和氮的共同限制。沿着太平洋入流方向,S01、R01、LV77-01站位30 m以深硅酸盐浓度高于太平洋入流水端员,说明沉积物孔隙水向底层水释放硅酸盐,因此在浅水陆架区孔隙水可作为上层海洋硅酸盐的潜在来源。本研究结合文献数据计算得到楚科奇海陆架沉积物-水界面硅酸盐年通量为630.78 mmol·m^-2·a^-1,总量为3.75×10¹¹ mol·a^-1,是太平洋入流水所携带硅酸盐年通量的一半(6.59×10¹¹ mol·a^-1),表明沉积物孔隙水也是楚科奇海陆架硅酸盐的重要来源。     

楚科奇海陆架沉积物中几种低环的多环芳烃的垂直分布特征

于2014年中国第6次北极科学考察期间,采集了楚科奇海陆架4根沉积物柱状样,据此开展了其中几种低环的多环芳烃(PAHs)的总体水平调查,并结合~(210)Pb测年,探讨了其垂直分布特征及历史沉降规律。结果表明,楚科奇海陆架沉积物中几种低环PAHs含量变化范围为50—1 553 ng·g~(–1),总体处于较低水平,且与粒径变化关系不明显。楚科奇海陆架区沉积物的沉积速率为0.05—0.19 cm·a~(–1),低环PAHs垂直变化较小,总体受人类影响极少,局部高值可能受到石油渗漏或成岩作用等过程的影响。     

Results of recent Pacific-Arctic ice-ocean modeling studies at the Naval Postgraduate School

Summary of results from a high - resolution pan - Arctic ice - ocean model are presented for the northern North Pacific, Bering, Chukchi, and Beaufort seas. The main focus is on the mean circulation, communication from the Gulf of Alaska across the Bering Sea into the western Arctic Ocean and on mesoscale eddy activity within several important ecosystems. Model results from 1979 -2004 are compared to observations whenever possible. The high spatial model resolution at 1/12o （or -9 - km） in the horizontal and 45 levels in the vertical direction allows for representation of eddies with diameters as small as 36 km. However, we believe that upcoming new model integrations at even higher resolution will allow us to resolve even smaller eddies. This is especially important at the highest latitudes where the Rossby radius of deformation is as small as 10 km or less.     

Geology of the Pedwardine district,Herefordshire and Powys

The stratigraphy of the Pedwardine inlier of Precambrian (Longmyndian), Tremadoc, and what are now shown to be upper Llandovery rocks is described. The inlier is surrounded by Silurian rocks, including upper Llandovery (two very small areas), Wenlock, Ludlow and Přídolí (Red Downton Formation). The Ludlow rocks provide a distal record of the mass movement recorded more fully in the Wigmore Rolls area to the east. The Pedwardine area lies along the Church Stretton Fault Zone. Though ill-exposed, it shows evidence of the history of faulting, including thrusting. © 1997 John Wiley & Sons, Ltd.     

Depth distribution of radiolarians from the Chukchi and Beaufort Seas, western Arctic

The depth distributions of the radiolarian fauna in the Chukchi and Beaufort Seas, marginal seas of the western Arctic Ocean, were examined quantitatively in depth-stratified plankton tows from 4 or 5 intervals above 500 m and in surface sediments from various depths between 163 and 2907 m. The radiolarian assemblage from the water column in September 2000 was dominated by Amphimelissa setosa and followed by the Actinomma boreale/leptoderma group, Pseudodictyophimus gracilipes and Spongotrochus glacialis. These species are related to the Arctic Surface Water shallower than 150 m. This assemblage is similar to that in the Greenland Sea relating to the ice edge, but did not contain typical Pacific radiolarians in spite of the flow of water of Pacific origin in this region. The living depth of Ceratocyrtis historicosa was restricted to the relatively warm water between 300 and 500 m corresponding to the upper Arctic Intermediate Water (AIW) originating from the Atlantic Ocean. Radiolarian assemblages in the surface sediments are similar to those in the plankton tows, except for common Cycladophora davisiana in sediment samples below 500 m. C. davisiana is probably a deep-water species adapted to the lower AIW or the Canadian Basin Deep Water ventilated from the shelves.