Paleoceanographic records in the Chukchi Basin, western Arctic Ocean during the late Quaternary   总被引：1，自引：0，他引：1  

WANG Rujian  XIAO Wenshen  SHAO Lei  CHEN Jianfang  GAO Aiguo 《海洋学报(英文版)》2012,31(1):83-94

The late Quaternary paleoceanographic changes in the western Arctic Ocean are revealed by quantitative studies of foraminiferal abundance, ice-rafted detritus (IRD) and its mineralogical and petrological compositions, planktonic Neogloboquadrina pachyderma (sin.) (Nps)-δ¹⁸O and -δ¹³C, biogenic and non-biogenic components in Core M03 token from the Chukchi Basin during the Second Chinese National Arctic Expedition cruise. Seven IRD events appeared at MIS 7, 5, 3 and 1. These IRD were carried in massive icebergs, which were exported to the Beaufort Sea through the M'Clure Strait Ice Stream, Canadian Arctic Archipelago, and then transported into the Chukchi Basin by the Beaufort Gyre. Low IRD deposition occurred during the glacial times when more extended ice cover and weakened Beaufort Gyre, while the open water condition and the intensified Beaufort Gyre during interglacial periods favored the IRD deposition. Therefore, the IRD events not only indicate the provenance of coarser detritus and ice export events, but also reflect the evolutionary histories of the Beaufort Gyre and North American ice sheet. Seven light Nps-δ¹⁸O and -δ¹³C excursions could respond to enhanced rates of sea ice formation resulting in the production and sinking of isotopically light brines, but was irrelevant to the warm Atlantic water and freshwater inputs. Whereas, the heavy Nps-δ¹⁸O and -δ¹³C values separately reflect the lessened Arctic freshwater and Pacific water, and well-ventilated surface water from the continental shelf and halocline water. Variations of CaCO₃ content and planktonic foraminiferal abundance during the interglacial and glacial periods can demonstrate the incremental or diminishing input of the Atlantic water, while the total organic carbon (TOC) and opal contents increased and decreased during the glacial and interglacial periods, respectively, which could be related to the TOC degradation, opal dissolution and redox conditions of interface between the bottom water and sediments.  相似文献   

加拿大海盆与楚科奇海沉积物岩芯中好气异养细菌的分布          下载免费PDF全文

陈皓文  高爱国 《极地研究》2008,20(1):40-47

本文用MPN法测定了两种培养温度下加拿大海盆与楚科奇海10根沉积物岩芯中182份样品的好气异养细菌(GAB)的检出率和含量。结果发现沉积物中GAB检出率高,GAB平均值为4.46×107个·g-1(4℃)和5.47×107个·g-1(25℃)。最高GAB含量出现于20-22cm层,GAB含量在沉积物各层位间波动,总体上呈现中下层沉积物GAB含量低于表层之势。25℃培养时能提高GAB检出率和含量。温度的提高将可能改变测区沉积物GAB的生存环境和生存状况。纬度区间的差异似显出测区中部GAB检出率和含量高于高、低纬度区间之状(4℃培养明显于25℃)。浅水区沉积物中的GAB含量较低,而水越深则GAB含量似越高,以25℃为明显。  相似文献   

Spatial distribution of pico-and nano-phytoplankton and bacteria in the Chukchi Sea in relation to water masses     

ZHANG Fang  HE Jianfeng  LIN Ling  LIU Ying  WANG Xiaoying  DING Chen 《极地研究(英文版)》2012,23(4):237-243

We evaluated the relationships between water masses and pico- and nano-phytoplankton and bacterial abundance in the Chukchi Sea. The abundance of picoplankton ranged from 0.01 ~ 103 cells.mL1 （100 m, station R05） to 2.21 x 103 cells.mL-1 （10 m, station R05） and that of nanoplankton ranged from 0.03 x 103 cells.mL-I （100 m, station R07） to 2.21 ~ 104 cells.mLq （10 m, station R05）. The lowest abundance of bacteria in the whole water column （0.21 x 106 cells.mLq） was at 100 m at station R17, and the highest （9.61 x 106 cells.mLL） was at 10 m at station R09. Melting sea ice affected the physical characteristics of the Chukchi Sea by reducing salinity of the surface mixed layer, resulting in greater hydrodynamic stability of the water column. These changes were accompanied by increased bacterial abundance. The warm Pacific water brought nutrients into the Chukchi Sea, resulting in greater abundance of bacteria and nano-phytoplankton in the Chukchi Sea than in other regions of the Arctic Ocean. However, the abundance of pico-phytoplankton, which was related to chlorophyll a concentration, was higher in Anadyr water than in the other two water masses. The structures ofpico- and nanoplankton communities coupled with the water masses in the Chuk- chi Sea can serve as indicators of the inflow of warm Pacific water into the Chukchi Sea.  相似文献   

Iceberg discharge to the Chukchi shelf during the Younger Dryas     

Jenna C. Hill  Neal W. Driscoll 《Quaternary Research》2010,74(1):57-62

The extent of glaciation in northwestern Alaska, the source of sediment supply to the Chukchi shelf and slope, and the movement of sea ice and icebergs across the shelf during the last glacial maximum (LGM) remain poorly constrained. Here we present geophysical and geological data from the outer Chukchi margin that reveal a regionally extensive, heavily ice-scoured surface ∼ 5-8 m below the modern seafloor. Radiocarbon dating of this discrete event yields age estimates between 10,600 and 11,900 ¹⁴C yr BP, indicating the discharge event occurred during the Younger Dryas. Based on mineralogy of the ice-rafted debris, the icebergs appear to be sourced from the northwestern Alaskan margin, which places important constraints on the ice extent in northern Alaska during the LGM as well as existing circulation models for the region.  相似文献   

北冰洋楚科奇边缘地的地球物理场与构造格局     

李官保  刘晨光  华清锋  韩国忠  刘保华 《海洋学报》2014,36(10):69-79

利用高分辨率水深、重力、地磁和多道反射地震数据,综合分析了楚科奇边缘地及其周边区域的地形地貌和地球物理场特征,划分了区域构造单元。研究表明,楚科奇边缘地不仅是楚科奇大陆架外缘独特的地形单元,也是一个相对独立的构造单元,与周边的加拿大洋盆、阿尔法-门捷列夫大火山岩省、北楚科奇陆架盆地和阿拉斯加被动陆缘等构造单元在地球物理场和区域构造上具有截然不同的特征。楚科奇边缘地是一个地壳减薄的微陆块,新生代早、中期发生了大规模的E-W向构造拉伸作用,基底断块的差异性升降塑造了当前的地形地貌和沉积层的发育。边缘地可能形成于北楚科奇盆地侏罗纪-早白垩纪的张裂作用,而内部盆-脊相间排列的构造格局则可能与加拿大海盆相边缘地俯冲作用停止后的均衡调整有关。  相似文献   

The composition and origination of particles from surface water in the Chukchi Sea,Arctic Ocean     

YU Xiaoguo  LEI Jijiang  YAO Xuying  ZHU Jihao  JIN Xiaobing 《极地研究(英文版)》2014,(3):147-154

Suspended particle samples were collected at 11 stations on the shelf and slope regions of the Chukchi Sea and the central Arctic Ocean during the fifth Chinese National Arctic Research Expedition （summer 2012）. The particle concentration, total organic carbon （TOC）, total nitrogen （TN） and the isotopic composition of the samples were analyzed. The suspended particle concentration varied between 0.56 and 4.01 mg.Ll; the samples collected from the sea ice margin have higher concentrations. The organic matter content is higher in the shelf area （TOC： 9.78%-20.24%; TN： 0.91‰-2.31%）, and exhibits heavier isotopic compositions （δ13C： -23.29‰ to -26.33‰ PDB; δ15N： 6.14‰-7.78‰）, indicating that the organic matter is mostly marine in origin with some terrigenous input. In the slope and the central Arctic Ocean, the organic matter content is lower （TOC： 8.06%- 8.96%; TN： 0.46%-0.72%）, except for one sample （SR15）, and has lighter isotopic compositions （δ13C： -26.93‰ to -27.78‰ PDB; δ15N： 4.13‰-4.84‰）. This indicates that the organic matter is mostly terrestrially-derived in these regions. The extremely high amount of terrigenous organic matter （TOC： 27.94%; TN： 1.16%; δ13C： -27.43‰ PDB; δ15N： 3.81‰） implies that it was carried by transpolar currents from the East Siberian Sea. Material, including sea ice algae, carried by sea ice are the primary source for particles in the sea ice margins. Sea ice melting released a substantial amount of biomass into the shelf, but a large amount of detrital and clay minerals in the slope and the central Arctic Ocean.  相似文献   

极区海洋锚碇测流系统的设计和布放   总被引：1，自引：0，他引：1  

矫玉田  赵进平  史久新  吴伟  张洪新 《海洋技术学报》2008,27(1):22-25

中国第二次北极科学考察期间,在白令海峡和北冰洋楚科奇海布放了一套潜标和两套明标,这是我国首次在极区布放锚碇观测系统。潜标和明标在本次考察结束前被成功回收,获得了最长为45 d的连续观测资料。文中通过介绍这次布放过程,对极区锚碇系统的相关技术问题进行了讨论,包括观测站位和层次的选择,锚碇系统的设计,布放步骤等,为在海冰存在的低温海域布放锚碇系统提供参考。  相似文献   

Modeling seasonal variations of ocean and sea ice circulation in the Beaufort and Chukchi Seas： A model-data fusion study     

Kohei Mizobata  Walter Johnson  Koji Shimada  Moto Ikeda 《极地研究(英文版)》2008,19(2):168-184

A 3.8-kin Coupled Ice-Ocean Model （C1OM） was implemented to successfully reproduce many observed phenomena in the Beaufort and Chukchi seas, including the Bering-inflow-originated coastal current that splits into three branches： Alaska Coastal Water （ACW） , Central Channel, and Herald Valley branches. Other modeled phenomena include the Beaufort Slope Current （BSC） , the Beaufort Gyre, the East Siberian Current （ ESC）, mesoscale eddies, seasonal landfast ice, sea ice ridging, shear, and deformation. Many of these downscaling processes can only be captured by using a high-resolution CIOM, nested in a global climate model. The seasonal cycles for sea ice concentration, thickness, velocity, and other variables are well reproduced with Solid validation by satellite measurements. The seasonal cycles for upper ocean dynamics and thermodynamics are also well reproduced, which include the formation of the cold saline layer due to the injection of salt during sea ice formation, the BSC, and the subsurface upwelling in winter that brings up warm, even more saline Atlantic Water along the shelfbreak and shelf along the Beaufort coast.  相似文献   

Crop booms at the forest frontier: Triggers,reinforcing dynamics,and the diffusion of knowledge and norms     

《Global Environmental Change》2019

Crop booms in forest frontiers are a major contributor to deforestation and global change. Because of their non-linearity, intensity, and unpredictability, booms are specific instances of land change, namely land system regime shifts, which require an analysis going beyond that of their drivers or individual actors’ decisions. So far, the combined effect of behavioral dynamics at the household, village, and higher levels, which are often mutually-reinforcing, have not been considered in the empirical analysis of crop booms. In this paper, we aim to further the understanding and the theory behind the dynamics of crop booms and land regime shifts. We focus on the smallholder-driven northern Laos rubber boom and analyze two case study areas with different intensity of rubber expansion. We use a combination of household surveys and interviews with villagers, government officials and private sector actors to analyze the preconditions, triggers and reinforcing effects at household and higher levels that help explain the timing and extent of the boom. In particular, we focus on the role of information transmission and imitation in household decisions to adopt and expand rubber. Our findings show that the rapid expansion of rubber in northern Laos was in part the result of household decisions spurred by economic and policy triggers that changed the real and perceived benefits of growing rubber. In addition, there were higher-level and mutually-reinforcing dynamics, such as the conversion of village communal forests, a rush for land, and individual behavior contingent on others’, including imitation. The transmission of information through social networks played a key role in rubber adoption decisions, but the diffusion of new norms and values was also important and may have accelerated adoption decisions. Rubber adoption and expansion decisions thus had normative and informational, as well as knowledge-based and imitation components.  相似文献   

Particulate organic carbon export fluxes on Chukchi Shelf,western Arctic Ocean,derived from 210Po/210Pb disequilibrium     

HE Jianhua  YU Wen  LIN Wuhui  MEN Wu  CHEN Liqi 《中国海洋湖沼学报》2015,33(3)

Fluxes of particulate organic carbon(POC) were derived from 2 10 Po/ 210 Pb disequilibrium during the 4th Chinese National Arctic Research Expedition(CHINARE-4) from July 1 to September 28,2010. Average residence times of particulate 2 10 P o in the euphotic zone were-16.00 a to 1.54 a,which are higher than those of dissolved 2 10 Po(-6.89 a to-0.70 a). Great excesses of dissolved 210 Po were observed at all stations,with an average 2 10 Po/ 210 Pb ratio of 1.91±0.20,resulting from 2 10 Pb atmospheric deposition after sea ice melt. POC fluxes from the euphotic zone were estimated by two methods(E and B) in the irreversible scavenging model. Estimated POC fluxes were 945–126 mmol C/(m2·a) and 1 848–109 mmol C/(m2·a) by methods E and B,respectively,both decreasing from low to high latitude. The results are comparable to previous works for the same region,indicating efficient biological pumping in the Chukchi Sea. The results can improve understanding of the carbon cycle in the western Arctic Ocean.  相似文献