北极中央区海冰密集度与云量相关性分析   总被引：2，自引：0，他引：2  

纪旭鹏  赵进平 《海洋学报》2015,37(11):92-104

本文使用海冰密集度以及低云、中云、高云的日平均数据,借助滑动相关分析方法,研究了北极中央区海冰密集度与云量之间的相关性,分析了海冰与云的相互作用机制。研究表明,在春季海冰融化季节(4、5月)、秋季海冰冻结季节(10、11月),低云与海冰密集度之间表现为较好的负相关,表明在这段时间内冰区海面蒸发强烈,对低云的形成有重要贡献。在10月和11月,中云与海冰密集度也有很好的负相关,表明秋季低云可以通过抬升形成中云。高云与海冰密集度之间并没有明显的相关性,可能原因:一方面海冰的空间分布对高云无影响,另一方面,高云主要影响到达的短波辐射,从而影响海冰的融化和冻结速度,与海冰厚度有直接显著的关系,而与海冰密集度的关系不明显。此外,在海冰密集度与低云存在较好负相关的情况下会出现某些年份相关性不好的情况,我们的研究发现这是北极中央区与周边海区发生了海冰交换或云交换的结果。  相似文献   

加拿大海盆北部营养盐限制作用研究   总被引：1，自引：1，他引：0  

李宏亮  陈建芳  高生泉  卢勇  金海燕  白有成  庄燕培  张海生 《海洋学报》2015,37(11):147-154

利用2008年夏季中国第三次北极科学考察获得的营养盐、叶绿素a、温度和盐度等数据资料,结合现场营养盐添加实验的结果讨论西北冰洋加拿大海盆北部营养盐对浮游植物生长的限制作用。结果表明:由于融冰水稀释作用,加拿大海盆B80站约20m深度存在较强的盐跃层,阻碍了水体上下混合。较低浓度的溶解无机氮(DIN)和硅酸盐(分别为0.31μmol/L和0.94μmol/L)以及严重偏离Redfield比值的N/P、N/Si比值(分别为0.42和0.32)表明加拿大海盆表层水体存在N和Si限制。根据现场营养盐加富实验各培养组叶绿素a浓度变化、营养盐吸收总量差异和浮游植物种群结构,进一步表明氮是北冰洋海盆首要限制营养盐,而Si则抑制了硅质生物的生长。同时,较小的硝酸盐半饱和常数(Ks)证明即使在营养盐充足的情况下北冰洋海盆浮游植物生长速率也处于较低水平。计算得到各培养组营养盐吸收比例(N/P比值)均大于Redfield比值,可能是培养实验过程中以微型、微微型浮游植物为主,硅藻等小型浮游植物为辅造成的。  相似文献   

Gauging perceptions of ocean acidification in Alaska     

《Marine Policy》2015

While ocean acidification (OA) poses a significant threat to ocean-related ecosystems and communities reliant on marine fisheries, aquaculture, and coral reef systems, limited public understanding and awareness can prevent coastal regions from being able to adequately assess the need for OA adaptation or mitigation. This study assessed public understanding of OA and how social and demographic factors influence the public’s concern for OA. The analysis was based on 311 questionnaires from full-time Alaska residents. The results showed that most Alaskans self-reported to have a basic awareness of OA, and subsequently were able to recognize that CO₂ emissions related to human activity are the dominant driver of changing ocean conditions. However, there was a low recognition of how natural variability in the marine environment affects OA, and most respondents were not very confident in their understanding of OA-related science. Moreover, even though many communities in Alaska are reliant on commercial and subsistence fishing activities, the respondents had a low awareness of fisheries-related OA risk. Given the ongoing debate associated with climate change research, evaluating CO₂ mitigation efforts through the perspective of OA could give individuals an unbiased way to assess the pros and cons of more intensive efforts to curb CO₂ emissions. Furthermore, using OA communication to enhance the understanding of how natural variability influences OA around the state and the potential economic implications for Alaska fisheries would help residents and stakeholders make informed decisions when considering fisheries management plans, food security, and job diversity as OA intensifies. Solidifying the understanding that any reduction in pH and intensification of OA can have implications for marine species that are irreversible on human timescales will reinforce not only that OA is an immediate concern, but also the importance of taking action now.  相似文献   

Mesoscale surface circulation and variability of Southern Indian Ocean derived by combining satellite altimetry and drifter observations   总被引：1，自引：1，他引：0  

BENNY N. Peter  SHENBAKAVALLI Ranjan  MAZLAN Hashim  MOHD Nadzri Re  MOHD Razali Mahmud 《海洋学报(英文版)》2015,34(9):12-22

High resoultion Eulerian mean velocity field has been derived by combining the satellite tracked surface drifter data with satellite altimetry and ocean surface winds. The drifter data used in this study includes Argos and surface drifter data from Global Drifter Program. Maps of Sea Level Anomaly(MSLA) weekly files with a resolution of(1/3)° in both Latitude and Longitude for the period 1993–2012 have been used. The Ekman current is computed using ocean surface mean wind fields from scatterometers onboard ERS 1/2,Quikscat and ASCAT. The derived mean velocity field exhibits the broad flow of Antarctic Circumpolar Current with speeds up to 0.6 m/s.Anomalous field is quite significant in the western part between 20° and 40°E and in the eastern part between 80°E and 100°E with velocity anomaly up to 0.3 m/s. The estimated mean flow pattern well agrees with the dynamic topography derived from in-situ observations. Also,the derived velocity field is consistent with the in-situ ADCP current measurements. Eddy kinetic energy illustrates an increasing trend during 1993–2008 and is in phase coherence with the Southern Annular Mode by three month lag. Periodic modulations are found in the eddy kinetic energy due the low frequency Antarctic Circumpolar Wave propagation.  相似文献   

西北冰洋表-底层碳动力学耦合作用的同位素(¹³C,₂₃₄Th)指示     

张润  陈敏  马嫱  曹建平  邱雨生 《海洋学报(英文版)》2015,34(6):26-33

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/238 U 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, d13 C signatures of surface sediments(d13Csed) are positively correlated to those of weighted d13 CPOC in upper ocean(d13Csed =13.64+1.56×d13CPOC, r2=0.73, p0.01), 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 234 Th 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 d13 C record an indicator of paleo-CO2 in the western Arctic Ocean.  相似文献   

孙吴地区中侏罗世白云母花岗岩的年代学与地球化学:对蒙古-鄂霍茨克洋闭合时间的限定   总被引：10，自引：1，他引：9  

李宇  丁磊磊  许文良  王枫  唐杰  赵硕  王子进 《岩石学报》2015,31(1):56-66

本文对孙吴地区白云母花岗岩行了锆石LA-ICP-MS U-Pb年代学和岩石地球化学研究,确定其形成时代、岩石成因,从而揭示区域构造背景。孙吴地区白云母花岗岩中的锆石均呈半自形-自形,振荡生长环带明显,暗示其岩浆成因。测年结果显示,白云母花岗岩形成于168Ma,为中侏罗世岩浆事件的产物。岩体具有高硅(Si O2=74.61%~80.16%)、富铝(Al2O3=10.59%~13.90%)、贫铁(Fe2O3=0.11%~0.3%)等特征,在化学上属于准铝质-过铝质(A/CNK=0.97~1.13)系列。孙吴地区白云母花岗相对富集轻稀土元素(LREEs)和大离子亲石元素(LILEs),亏损重稀土元素(HREEs)和高场强元素(HFSEs)。锆石的εHf(168Ma)=+7.53~+11.66,二阶段的模式年龄(tDM2)变化于595~966Ma之间。上述特征表明,孙吴地区中侏罗世白云母花岗岩的岩浆起源于新增生加厚陆壳物质的部分熔融。结合在大兴安岭与小兴安岭衔接地区变质杂岩和冀北-辽西地区区域性地层不整合面的存在,表明大兴安岭西坡-冀北-辽西地区中侏罗世经历了一次与蒙古-鄂霍茨克洋闭合有关的陆壳加厚过程。因此,研究区内中侏罗世白云母花岗岩的形成应与蒙古-鄂霍茨克洋闭合过程中的陆-陆碰撞作用有关,而与古环太平洋向欧亚大陆的俯冲作用无关,其形成时代也限定额尔古纳地块西北部蒙古-鄂霍茨克洋的闭合时间应为中侏罗世。  相似文献   

原特提斯洋的俯冲、增生及闭合:阿尔金-祁连-柴北缘造山系早古生代增生/碰撞造山作用   总被引：20，自引：18，他引：2  

张建新  于胜尧  李云帅  喻星星  林宜慧  毛小红 《岩石学报》2015,31(12):3531-3554

分布在青藏高原北缘的阿尔金-祁连-柴北缘早古生代造山系被认为是原特提斯构造域最北部的构造拼合体。与其北侧具有长期增生历史的中亚造山系相比,特提斯造山拼合体被认为是各种来自冈瓦纳大陆北部大陆块体相互碰撞的产物。然而,与典型的阿尔卑斯和喜马拉雅碰撞造山带相比,阿尔金-祁连-柴北缘早古生代造山系包括有大量蛇绿岩、弧岩浆杂岩、俯冲-增生杂岩等,因此一些学者认为青藏高原北部的早古生代造山系为沿塔里木和华北克拉通边界向南逐渐增生的增生型造山带。但是,增生造山模式又很难解释南阿尔金-柴北缘地区普遍存在的与大陆俯冲有关的UHP变质岩、广泛分布的巴罗式变质作用和相关的岩浆作用,以及与碰撞造山有关的变形构造等。在本文中,通过对已有研究资料的综合总结,结合一些新的研究资料,我们提出在青藏高原东北缘的阿尔金-祁连-柴北缘造山系中,早古生代时期存在两种不同类型的造山作用,即增生和碰撞造山作用,其主要标志是北祁连-北阿尔金的HP/LT变质带、蛇绿混杂岩及与洋壳俯冲有关的构造岩浆作用,以及分布在柴北缘-南阿尔金与大陆俯冲和陆陆碰撞有关的UHP变质带、区域巴罗式变质作用、深熔作用、相关的岩浆活动及伸展垮塌作用等,并建立了一个反映原特提斯洋俯冲、增生、闭合及碰撞造山作用的构造模式。  相似文献   

鲁西北地区理疗热矿水的形成条件及找矿靶区          下载免费PDF全文

张保建  刘福义高宗军张凤禹郝栓虎臧建军 《中国地质》2015,(4):1170-1178

鲁西北地区赋存发育碳酸盐岩类裂隙-岩溶型与砂岩类裂隙-孔隙型2种理疗热矿水,碳酸盐岩类裂隙-岩溶型理疗热矿水主要为氟·锶水;砂岩类裂隙-孔隙型理疗热矿水主要为锶水和溴·锶水。根据对理疗热矿水形成条件的分析,研究区内的鲁西地块阳谷-齐河凸起与坳(凹)陷区内的顶部风化壳岩溶发育的基底凸起(潜山)是碳酸盐岩类裂隙-岩溶型理疗热矿水的找矿靶区;华北坳陷区内深大断裂及坳(凹)陷边缘较大断裂附近的次级构造发育区是砂岩类裂隙-孔隙型理疗热矿水的找矿靶区。  相似文献   

Secondary Calcification of Planktic Foraminifera from the Indian Sector of Southern Ocean     

Rahul MOHAN  Suhas S. SHETYE  Manish TIWARI  Narayanpillai ANILKUMAR 《《地质学报》英文版》2015,89(1):27-37

This study focused on planktic foraminifera in plankton tows and surface sediments from the western Indian sector of Southern Ocean in order to evaluate the potential foraminiferal secondary calcification and/or dissolution in the sediment. It is found that the symbiotic foraminiferal species are abundant in the subtropical region, whereas non-symbiotic species dominate in the sub-Antarctic and polar frontal regions. The distribution of the symbiotic and non-symbiotic foraminiferal species is controlled by temperature, salinity, light, nutrients and phytoplankton biomass. There is also a lateral southern extent in abundance of planktic foraminifera from surface sediments to plankton tows. The shell weights of the planktic foraminifera N. pachyderma, G. bulloides and G. ruber within the surface sediments are on an average heavier by 27%, 34% and 40% respectively than shells of the same size within the plankton tows, indicative of secondary calcification. The planktic foraminiferal isotopes show the presence of heavier isotopes in the surface sediment foraminifera as compared to plankton tows, thus confirming secondary calcification. Secondary calcification in G. ruber occurs in the euphotic zone, whereas in case of N. pachyderma and G. bulloides it is at deeper depths. We also observed a decrease in the shell spines in surface sediment foraminifera as compared to plankton tows, indicative of the morphological changes that foraminifera underwent during gametogenesis.  相似文献   

全球海洋人为碳储量估算及时空分布研究进展     

Huang Peng  Chen Liqi  Cai Minggang 《地球科学进展》2015,30(8):952-959

海洋是全球最大的碳汇,确定海洋中人为碳含量及其时空变化是一件具有挑战性的工作。就当前海洋人为碳含量确定方法、人为碳储量及其随时间变化进行综述总结。研究表明海洋仍然可以吸收并储藏大量的人为碳,但未来对于海洋吸收储藏人为碳的研究仍具有诸多不确定性。已有证据表明稳态海洋的概念不完全正确,需要在非稳态条件下重新定义人为碳并开展研究。同时需要积累更多的观测数据,采用包括观测和模式模拟等手段来研究不同时间尺度的人为碳的吸收和储藏过程。  相似文献