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Organic carbon and nitrogen isotopes in surface sediments from the western arctic ocean and their implications for sedimentary environments

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Acta oceanologica Sinica 2006年第5期25卷 39-54页

作者： CHEN Zhihua SHI Xuefa CAI Deling HAN Yibing YANG Zuosheng ocean University of China Qingdao 266003 China First Institute of oceanography State Oceanic Administration Qingdao 266061 China Key Laboratory of Marine Sedimentology ＆ Environmental Geology of State oceanic Administration First Institute of Oceano-graph State Oceanic AdministrationQingdao 266061 China

Surface sediments from the Chukchi Sea and adjacent arctic deep sea were investigated for organic carbon and nitrogen isotopes （in δ13Corg and δ15Norg） as well as biogeni＇c silica （BSiO2）. δ13Corg and δ15Norg values of surface sediments in the study area fall between the end-member values of marine and terrestrial organic matter from the surrounding lands and seas, their variations reflect the changes of marine productivity and terrestrial supply in the study area. BSiO2 shows a similar distribution pattern with δ13Corg and δ15Norg, and can be used as an indicator of marine productivity. In the central-west Chukchi Sea and the Chukchi Rise, sediments have higher δ13Corg, δ15Norg and BSiO2 values, indicating the region has high marine productivity influenced by the nutrient-rich branches of the Pacific waters. In the coastal zone off northwestern Alaska, δ13Corg and δ15Norg values become lighter, indicating a weakening marine productivity and an increasing terrigenous supply due to the effects of the least nutrient-rich branch of the Pacific waters. In the north and the northeast of the study area （including the Chukchi Plateau, the Canada Basin and the Beaufort shelf）, δ13Corg, δ15Norg and BSiO2 have the lowest values, and the terrigenous organic matter becomes dominant in surface sediments because this region has the longest ice-covered duration, the least nutrient-rich seawater and the increasing supply of terrestrial materials from the Mackenzie River and the northern Alaska under the action of the clockwise Beaufort gyre. Because the subarctic Pacific waters are continuously discharged into the central basin of the arctic ocean through the study area, the nutrient pool in the Chukchi Sea can be considered as a typical open system, the ratio of δ15Norg to BSiO2 content show some tracers that the level of nutrient utilization is contrary to nutrient supply and marine productivity formed in seawater.

关键词： western arctic ocean surface sediments organic carbon and nitrogen isotopes biogenic silica

Distribution of radium-224 in the western arctic ocean

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Acta oceanologica Sinica 2005年第6期24卷 109-116页

作者： QIU Yusheng CHEN Min LI Yanping Department of oceanography Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China Department of Oceanography Xiamen University Xiamen 361005 China

Radium-224 activities in the western arctic ocean were measured viaship-board ^(220)Rn emanation technique during the Second Chinese National arctic Expedition. Theresults showed that the ^(224)Ra activities in the study areas ranged from being less than 0.08 to3.58 Bq/m^3, with an average of 0.23 Bq/m^3. The low ^(224)Ra concentration in the surface water wasattributed to the influence of sea ice melted water. The horizontal distribution of surface^(224)Ra in the western arctic ocean showed a high ^(224)Ra characteristics occurred along the slopearound 160°W, providing evidence for the importance of ice-rafted sediments to controlling thedistribution of radium isotopes in the arctic ocean. Mostly, ^(224)Ra concentrations increased withthe depth in the shelf region and reached a maximum at 75 m at the central Canada Basin, whichfurther confirms the importance of the transport of shelf bottom water to maintaining the upperhalocline layer in the Canada Basin.

关键词： ^(224)Ra distribution western arctic ocean

^(234)Th-derived particulate organic carbon export flux in the western arctic ocean

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Chinese Journal of oceanology and Limnology 2010年第6期28卷 1146-1151页

作者：余雯陈立奇程建平何建华尹明端曾志 Key Laboratory of Global Change and Marine-Atmospheric Chemistry Department of Engineering Physics Tsinghua University Key Laboratory of Particle & Radiation Imaging (Tsinghua University) Ministry of Education

To evaluate the particle dynamics and estimate the POC (particulate organic carbon) export flux from the euphotic zone in the western arctic ocean,234 Th238 U disequilibrium was applied during the second Chinese National arctic Research Expedition (July 15-September 26,2003).The POC export fluxes are estimated from the measured profiles of the 234 Th/238 U activity ratios and the POC/PTh *** average residence times of the particulate and dissolved 234 Th in the euphotic zone are 33 d and 121 d,and their average export fluxes are 480 dpm/m 2 d and 760 dpm/m 2 d,*** scavenging and removal processes of particle reactive elements are active in the upper layer of the Chukchi *** average residence time of 234 Th increases from shelf to basin,while the export fluxes of 234 Th *** estimated POC export fluxes from the euphotic zone vary from 2.1 to 20.3 mmol/m 2 d,indicating that the western arctic ocean is an important carbon sink in summer due to efficient biological pump.

关键词： POC export flux 234Th/238U disequilibrium carbon cycling western arctic ocean

Interaction of an anticyclonic eddy with sea ice in the western arctic ocean:an eddy-resolving model study

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Acta oceanologica Sinica 2013年第3期32卷 54-62页

作者： LI Qun ZHANG Zhanhai WU Huiding Polar Research Institute of China State Oceanic Administration National Marine Environmental Forecasting Center State Oceanic Administration

The dramatic decline of summer sea ice extent and thickness has been witnessed in the western arctic ocean in recent decades, which has motivated scientists to search for possible factors driving the sea ice variability. An eddy-resolving, ice-ocean coupled model covering the entire arctic ocean is implemented, with focus on the western arctic ocean. Special attention is paid to the summer Maskan coastal current （ACC）, which has a high temperature （up to 5℃ or more） in the upper layer due to the solar radiation over the open water at the lower latitude. Downstream of the ACC after Barrow Point, a surface-intensified anticyclonic eddy is frequently generated and propagate towards the Canada Basin during the summer season when sea ice has retreated away from the coast. Such an eddy has a warm core, and its source is high-temperature ACC water. A typical warm-core eddy is traced. It is trapped just below summer sea ice melt water and has a thickness about 60 m. Temperature in the eddy core reaches 2-3℃, and most water inside the eddy has a temperature over 1℃. With a definition of the eddy boundary, an eddy heat is calculated, which can melt 1 600 km2 of 1 m thick sea ice under extreme conditions.

关键词： eddy-resolving anticyclonic eddy sea ice western arctic ocean Alaskan coastal current

Ice rafting history and paleoceanographic reconstructions of Core 08P23 from southern Chukchi Plateau, western arctic ocean since Marine Isotope Stage 3

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Acta oceanologica Sinica 2015年第3期34卷 68-75页

作者： ZHANG Taoliang WANG Rujian XIAO Wenshen CHEN Zhihua CHEN Jianfang CHENG Zhenbo SUN Yechen State Key Laboratory of Marine Geology Tongji University The First Institute of oceanography State Oceanic Adiministration The Second Institute of oceanography State Oceanic Adiministration

Multiproxy investigations have been performed on Core 08P23 collected from the Chukchi Plateau, the western arctic ocean, during the Third Chinese National arctic Expedition. The core was dated back to Ma-rine Isotope Stage （MIS） 3 by a combination of Accelerator Mass Spectrometric （AMS） carbon-14 dating and regional core correlation. A total of five prominent ice-rafted detritus （IRD） events were recognized in MIS 2 and MIS 3. The IRD sources in MIS 3 are originated from vast carbonate rock outcrops of the Canadian arctic Archipelago and clastic quartz in MIS 2 may have a Eurasian origin. Mostδ18O andδ13C values of Neogloboquadrina pachyderma （sinistral）（Nps） in Core 08P23 are lighter than the average values of surface sediments. The lighterδ18O andδ13C values of Nps in the two brown layers in MIS 1 and MIS 3 were resulted from meltwater events; and those in the gray layers in MIS 3 were caused by the enhanced sea ice formation. Theδ18O values varied inversely withδ13C in MIS 2 indicate that the study area was covered by thick sea ice or ice sheet with low temperature and little meltwater, which prevented the biological productivity and sea-atmosphere exchange, as well as water mass ventilation. The covaried light values ofδ18O andδ13C in MIS 1 and MIS 3 were resulted from meltwater and/or brine injection.

关键词： Chukchi Plateau western arctic ocean Marine Isotope Stage 3 ice rafted detritus events oxygen and carbon isotope water mass changes

Regional disparities of phytoplankton in relation to environmental factors in the western arctic ocean during summer of 2010

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Acta oceanologica Sinica 2018年第4期37卷 109-120页

作者： LIN Gengming WANG Yanguo CHEN Yanghang YE Youyin WANG Yu YANG Qingliang Third Institute of oceanography State Oceanic Administration

Global warming has caused arctic sea ice to rapidly retreat,which is affecting phytoplankton,the primary producers at the base of the food chain,as well as the entire ***,few studies with large spatial scales related to the arctic Basin at high latitude have been *** study aimed to investigate the relationship between changes in phytoplankton community structure and ice *** surface and 41 vertically stratified water samples from the western arctic ocean（67.0°–88°26′N,152°–178°54′W） were collected by the Chinese icebreaker R/V Xuelong from July 20 to August 30,2010 during China＇s fourth arctic *** these samples,the species composition,spatial distribution,and regional disparities of phytoplankton during different stages of ice melt were assessed.A total of 157 phytoplankton taxa（〉5 μm） belonging to 69 genera were identified in the study *** most abundant species were Navicula pelagica and Thalassiosira nordenskioeldii,accounting for 31.23% and 14.12% of the total phytoplankton abundance,*** average abundance during the departure trip and the return trip were 797.07×10~2 cells/L and 84.94×10~2 cells/L,*** highest abundance was observed at Sta.R09 in the north of Herald Shoal,where Navicula pelagica was the dominant species accounting for 59.42% of the *** vertical distribution of phytoplankton abundance displayed regional differences,and the maximum abundances were confined to the lower layers of the euphotic zone near the layers of the halocline,thermocline,and *** species abundance of phytoplankton decreased from the low-latitude shelf to the high-latitude basin on both the departure and return *** phytoplankton community structure in the shallow continental shelf changed markedly during different stages of ice melt,and there was shift in dominant species from centric to pennate *** of canonical correspondence analysis（CCA） showed that there were

关键词： phytoplankton regional disparity species composition spatial distribution western arctic ocean

Insights into the coupling of upper ocean-benthic carbon dynamics in the western arctic ocean from an isotopic(^(13)C, ^(234)Th) perspective

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Acta oceanologica Sinica 2015年第6期34卷 26-33页

作者： ZHANG Run CHEN Min MA Qiang CAO Jianping QIU Yusheng College of ocean and Earth Sciences Xiamen University State Key Laboratory of Marine Environmental Science Xiamen University

The coupling of upper ocean-benthic carbon dynamics in the ice-free western arctic ocean （the Chukchi Sea and the Canada Basin） was evaluated during the late July-early September 2003 using natural stable （13C） and radioactive （238U-234Th） isotope tracers. POC export flux estimated from 234Th/238U disequilibria and dissolved CO2 concentration （[CO2（aq）]） pointed out that the strengthened biological pump in the Chukchi Shelf have significantly lowered [CO2（aq）] and altered the magnitude of isotopic （12C/13C） fractionation during carbon fixation in the surface ocean. Further, δ13C signatures of surface sediments （δ13Csed） are positively correlated to those of weighted δ13Cp0C in upper ocean （δ13Csed =13.64＋1.56xδ13Cpoc, r2=0.73, p〈0.01）, suggesting that the POC isotopic signals from upper ocean have been recorded in the sediments, partly due to the rapid export of particles as evidenced by low residence times of the highly particle-reactive 234Th from the upper water column. It is suggested that there probably exists an upper ocean-benthic coupling of carbon dynamics, which likely assures the sedimentary δ13C record an indicator of paleo-CO2 in the western arctic ocean.

关键词： δ13C POC sediment carbon export flux western arctic ocean

Regional estimates of POC export flux derived from thorium-234 in the western arctic ocean

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Acta oceanologica Sinica 2005年第6期24卷 97-108页

作者： MA Qiang CHEN Min QIU Yusheng LI Yanping Department of oceanography Xiamen University Xiamen 361005 China Department of Oceanography Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China Department of Oceanography Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China

In order to elucidate the regional export variation of participate organiccarbon in the western arctic ocean, samples vertically integrated between 0 and 100 m depth orbetween 0 and 30 m/40 m depth were collected for total ^(234)Th measurements and those from 30 m/40m or 100 m depth were collected for paniculate ^(234)Th measurements during the Second Chinesearctic Expedition in July— September 2003. The removal fluxes and residence time of ^(234)Th in theupper water column were calculated by using irreversible steady-state scavenging model. The resultsshowed that, total ^(234)Th was deficit relative to its parent ^(238)U in the western arctic oceanexcept in the western Chukchi shelf and the slope regions around 160°W, indicating that scavengingand removal processes play an important role in element biogeochemical cycle in the arctic ocean. Inthe western Chukchi shelf and the slope regions around 160°W, total ^(234)Th was excess relativeto ^(238)U, ascribing to the horizontal input of ^(234)Th adsorbed by ice-rafted ***-234 removal fluxes decreased from the shelf to the deep ocean, while the residence time of^(234)Th increased from shelf to offshore, demonstrating that particle scavenging and removalprocesses are more active in the shelf regions. The estimated POC export fluxes from 40 m in theshelf regions and from 100 m in the slope and deep ocean varied between 1.6 and 27.5 mmol/(m^2·d),and between 1.8 and 14.4 mmol/(m^2·d), respectively. The averaged POC export fluxes over the entirewater column decreased from the shelf to the deep ocean, indicating that the Chukchi shelf is animportant region for organic carbon sequestration. The high ThE ratios (ratio of POC export fluxderived from ^(234)Th/^(238)U disequilibria to primary production) in the western arctic oceansuggested that the biological pump runs actively in high-latitudes.

关键词： POC export flux ^(234)Th western arctic ocean

Spatial variation in grain-size population of surface sediments from northern Bering Sea and western arctic ocean: Implications for provenance and depositional mechanisms

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Advances in Polar Science 2020年第3期31卷 192-204页

作者： WANG Weiguo YANG Jichao ZHAO Mengwei DONG Linsen JIANG Min HUANG Erhui Third Institute of oceanography Ministry of Natural Resources(MNR)Xiamen 361005China National Deep Sea Center Ministry of Natural Resources(MNR)Qingdao 266237China Pilot National Laboratory for Marine Science and Technology Qingdao 266237China First Institute of oceanography Ministry of Natural Resources(MNR)Qingdao 266061China

In general,sediments in nature comprise populations of various *** information regarding the sources and depositional mechanisms of the populations can be obtained through their temporal and spatial *** this study,the grain size distribution of surface sediments from the Bering Sea and western arctic ocean were fitted and partitioned into populations using a log-normal distribution *** spatial variations in the populations indicate differences in their sources and deposition *** sediments on most of the Bering Sea Shelf originated from the Yukon River,and were transported westward by waves and ***,the presence of a coarser population outside Anadyr Bay was the result of Anadyr River ***,a northward transport trend of fine suspended particles was observed on the west side of the Bering Sea *** sediments in Hope Valley in the south Chukchi Sea also originated from the Yukon *** coarser population on the central Chukchi Sea Shelf originated from coast of Alaska to the east,not the Yukon River,and was transported by sea ice and bottom brine *** populations of sediments from the Chukchi Basin and the base of the Chukchi Sea Slope are the result of sea ice and eddy *** sediments from the western high arctic ocean predominantly comprised five populations,and two unique populations with mode diameters of 50–90μm and 200–400μm,respectively,were ubiquitous in the glacial and interglacial *** was difficult to distinguish whether these two populations originated from sea ice or ***,caution should be exercised when using either the>63μm or>250μm fractions in sediments as a proxy index for iceberg and ice sheet variation in the high arctic ocean.

关键词： Bering Sea western arctic ocean surface sediments grain-size population provenance depositional mechanisms