Particle fluxes in San Pedro Basin, California: A four-year record of sedimentation and physical forcing     

Lisa E. Collins  William BerelsonDouglas E. Hammond  Angela Knapp  Richard SchwartzDoug Capone 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(8):898-914

Moored sediment traps were deployed from January 2004 through December 2007 at depths of 550 and 800 m in San Pedro Basin (SPB), CA (33°33.0′N, 118°26.5′W). Additionally, floating sediment traps were deployed at 100 and 200 m for periods of 12-24 h during spring 2005, fall 2007, and spring 2008. Average annual fluxes of mass, particulate organic carbon (POC), ??¹³C_org, particulate organic nitrogen (PON), ??¹⁵N-PON, biogenic silica (bSiO₂), calcium carbonate (CaCO₃), and detrital material (non-biogenic) were coupled with climate records and used to examine sedimentation patterns, vertical flux variability, and organic matter sources to this coastal region. Annual average flux values were determined by binning data by month and averaging the monthly averages. The average annual fluxes to 550 m were 516±42 mg/m² d for mass (sdom of the monthly averages, n=117), 3.18±0.26 mmol C/m² d for POC (n=111), 0.70±0.05 mmol/m² d for CaCO₃ (n=110), 1.31±0.21 mmol/m² d for bSiO₂ (n=115), and 0.35±0.03 mmol/m² d for PON (n=111). Fluxes to 800 and to 550 m were similar, within 10%. Annual average values of ??¹³C_org at 550 m were −21.8±0.2‰ (n=108), and ??¹⁵N averages were 8.9±0.2‰ (n=95). The timing of both high and low flux particle collection was synchronous between the two traps. Given the frequency of trap cup rotation (4-11 days), this argues for particle settling rates ≥83 m/d for both high and low flux periods. The moored traps were deployed over one of the wettest (2004-2005, 74.6 cm rainfall) and driest (2006-2007, 6.6 cm) rain years on record. There was poor correlation (Pearson's correlation coefficient, 95% confidence interval) of detrital mass flux with: C_org/N ratio (r=0.10, p=0.16); ??¹⁵N (r=−0.19, p=0.02); and rainfall (r=0.5, p=0.43), suggesting that runoff does not immediately cause increases in particle fluxes 15 km offshore. ??¹³C_org values suggest that most POC falling to the basin floor is marine derived. Coherence between satellite-derived chlorophyll a records from the trap location (±9 km² resolution) and SST data indicates that productivity and export occurs within a few days of upwelling and both of these parameters are reasonable predictors of POC export, with a time lag of a few days to 2 weeks (with no time lag—SeaWiFS chlorophyll a and POC flux, r=0.25, p=0.0014; chlorophyll a and bSiO₂ flux, r=0.28, p=0.0002).  相似文献   

Phytoplankton composition and biomass across the southern Indian Ocean   总被引：2，自引：0，他引：2  

Louise Schlüter  Peter HenriksenTorkel Gissel Nielsen  Hans H. Jakobsen 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(5):546-556

Phytoplankton composition and biomass was investigated across the southern Indian Ocean. Phytoplankton composition was determined from pigment analysis with subsequent calculations of group contributions to total chlorophyll a (Chl a) using CHEMTAX and, in addition, by examination in the microscope. The different plankton communities detected reflected the different water masses along a transect from Cape Town, South Africa, to Broome, Australia. The first station was influenced by the Agulhas Current with a very deep mixed surface layer. Based on pigment analysis this station was dominated by haptophytes, pelagophytes, cyanobacteria, and prasinophytes. Sub-Antarctic waters of the Southern Ocean were encountered at the next station, where new nutrients were intruded to the surface layer and the total Chl a concentration reached high concentrations of 1.7 ??g Chl a L⁻¹ with increased proportions of diatoms and dinoflagellates. The third station was also influenced by Southern Ocean waters, but located in a transition area on the boundary to subtropical water. Prochlorophytes appeared in the samples and Chl a was low, i.e., 0.3 ??g L⁻¹ in the surface with prevalence of haptophytes, pelagophytes, and cyanobacteria. The next two stations were located in the subtropical gyre with little mixing and general oligotrophic conditions where prochlorophytes, haptophytes and pelagophytes dominated. The last two stations were located in tropical waters influenced by down-welling of the Leeuwin Current and particularly prochlorophytes dominated at these two stations, but also pelagophytes, haptophytes and cyanobacteria were abundant. Haptophytes Type 6 (sensuZapata et al., 2004), most likely Emiliania huxleyi, and pelagophytes were the dominating eucaryotes in the southern Indian Ocean. Prochlorophytes dominated in the subtrophic and oligotrophic eastern Indian Ocean where Chl a was low, i.e., 0.043-0.086 ??g total Chl a L⁻¹ in the surface, and up to 0.4 ??g Chl a L⁻¹ at deep Chl a maximum. From the pigment analyses it was found that the dinoflagellates of unknown trophy enumerated in the microscope at the oligotrophic stations were possibly heterotrophic or mixotrophic. Presence of zeaxanthin containing heterotrophic bacteria may have increased the abundance of cyanobacteria determined by CHEMTAX.  相似文献   

中西太平洋金枪鱼延绳钓渔获组成及其多样性分析     

李勇  戴小杰  朱江峰  许柳雄 《海洋湖沼通报》2011,(2):52-58

根据2009年6～11月金枪鱼延绳钓观察员海上采集的数据,对中西太平洋S2°05′～S7°51′,W159°48′～W168°10′海域的延绳钓渔获物组成进行了分析.126个站点(钩次)的种类组成分析表明,该作业区域的渔获物有鱼类35种,隶属于9目22科30属;鲸类2种,隶属于1目2科2属;龟鳖类1种.反映种类组成多样...  相似文献   

印度洋热含量在南海夏季风爆发中的作用     

于乐江  冯俊乔 《热带海洋学报》2011,(4)

利用Scripps海洋研究所0—400m上层海洋热含量资料和美国环境监测中心/国家大气研究中心(National Centers for Environmental Prediction/National Center for Atmospheric Research,NCEP/NCAR)的再分析资料,运用经验正交分解(empirical orthogonal function,EOF)等统计方法,研究在有ENSO影响和去除ENSO影响的情况下,前期春季印度洋热含量如何影响南海夏季风爆发。结果表明,在没有扣除ENSO信号的情况下,热带印度洋热含量EOF分解第一模态呈东西相反变化的空间分布。印度洋东部热含量为正(负)异常、西部为负(正)异常时,南海夏季风爆发较早(晚),印度洋上层热含量主要通过影响热带印度洋上空大气的垂直运动和高低层辐散辐合,进而影响季风纬向环流的强弱,来影响南海夏季风爆发的早晚。在扣除ENSO信号的情况下,印度洋热含量CEOF(conditional EOF)第一模态的空间分布类似于EOF第一模态的空间分布;第二模态表现为除小部分海区外,热带印度洋热含量呈一致变化的海盆模态。这两个模态对南海夏...  相似文献   

热带西太平洋海域上层海洋热含量的CSEOF分析   总被引：4，自引：0，他引：4  

吴晓芬  许建平  张启龙  刘增宏 《热带海洋学报》2011,(6)

基于月平均Argo温、盐度剖面、纬向风和Ni o3.4指数等资料,利用循环平稳经验正交函数(CSEOF)分解法、最大熵谱分析和相关分析等方法,研究了热带西太平洋海域上层(0—700m)海洋热含量的时空变化特征,并探讨了其年际变化的可能原因。结果表明,热带西太平洋海域上层海洋热含量距平场具有显著的东-西向反位相振荡,且这种振荡除了具有较明显的季节变化外,还存在着较强的准2a振荡。此外,热含量距平场还存在着负-正-负的三极式经向模态,该模态除了具有明显的季节变化外,还存在着显著的准4a振荡。进一步分析表明,热含量的准2a振荡与ENSO事件的发生有着非常密切的联系,并对赤道西太平洋纬向风异常有1—2月的滞后响应。  相似文献   

Deep-sea suprabenthos assemblages (Crustacea) off the Balearic Islands (western Mediterranean): Mesoscale variability in diversity and production     

J.E. Cartes  V. Mamouridis  E. Fanelli 《Journal of Sea Research》2011,65(3):340-354

The composition of suprabenthic crustacean assemblages, their diversity, production (P) and production/biomass (P/B) ratios, were analyzed at species level along two transects situated to the north (N) and south (S) of Mallorca (Balearic Islands, western Mediterranean) at depths between 134 m and 760 m, based on a ca. bi-monthly sampling performed between August 2003 and June 2004. Differences with depth and season in assemblage composition and diversity were analyzed as a function of the contrasting environmental features (e.g. water mass dynamics) of the two areas. We identified 187 species (18 decapods, 5 euphausiids, 16 mysids, 76 gammaridean amphipods, 13 hyperiids, 1 caprellid, 21 isopods and 37 cumaceans). Substantial mesoscale variability in the deep-sea suprabenthic assemblages coupled with diversity trends between the N and S transects were found. Seasonality was the most important gradient influencing the dynamics of suprabenthos over the upper (350 m) and middle (650–750 m) slope in the N area. Conversely, the S area appeared to be more stable temporally with depth as the main gradient inducing assemblage differences. Different depth-related patterns were observed both for diversity and P/B. To the north diversity was very low at the shelf-break, increasing on the upper-slope (H′ > 3.00) and then decreasing again on the middle-slope. To the south diversity increased smoothly downward, reaching the highest values on the middle-slope. Regarding productivity, P/B was highest at intermediate depths to the north (over ca. 450–500 m), while to the south highest P/Bs were found deeper (over ca. 600–650 m). The higher P/B at intermediate depths found along N are likely due to higher % of organic matter (OM) in sediments, a product of oceanographic frontal systems. In particular, P/B was higher along N among omnivores and detritus feeders (e.g. Andaniexis mimonectes, Lepechinella manco and combined cumaceans), coupled to enriched OM in sediments, while along S mesoplanktonic carnivores (Rhachotropis spp.) had higher P/Bs. We conclude that on the north slope the influence of frontal systems and more active flow dynamics of different water masses (WIW and LIW) increases natural disturbance in the area, increasing productivity and diversity of suprabenthic peracarids in the Benthic Boundary Layer. Also, species showed a displacement of their average distributions (their Centres of Gravity, CoG) to shallower depths along N, which is another indicator of more favorable habitat conditions for suprabenthos in the 400–500 m range at N.  相似文献   

黄海绿潮应急溯源数值模拟初步研究   总被引：2，自引：0，他引：2  

吴玲娟  曹丛华  黄娟  曹雅静  高松  白涛 《海洋科学集刊》2011,50(6):44-47

基于三维全动力POM 海洋模式, 根据2008 年6 月1 日海监飞机监测绿潮所在位置, 采用拉格朗日粒子追踪法反向积分, 追溯绿潮来源。数值模拟结果显示, 回溯至5 月中旬, 绿潮主要来源于黄海南部江苏连云港和盐城近海海域。黄海绿潮溯源数值模拟, 为政府相关部门了解绿潮的源头, 并采取相应的措施提供依据, 进而为保护生态环境、防灾减灾做贡献。  相似文献   

中国卫星海洋观测系统及其传感器(1988—2025)     

贺明霞  贺双颜  王云飞  杨倩  唐军武  胡传民 《中国海洋大学学报(自然科学版)》2011,41(12):91-103

全面收集1988—2025年中国地球观测卫星(和飞船)计划,包括历史的、运行中的和列入未来计划的。详细介绍风云卫星系列(FY-n)、海洋卫星系列(HY-n)、资源卫星系列(ZY-n)、环境卫星系列(HJ-n)、中国遥感卫星系列(CRS-n)、灾害监测星座/北京小卫星(DMC/BJ-1)、神舟飞船系列(SZ-n)和天宫空间站系列(TG-n)等8个卫星(和飞船、空间站)系列。这些卫星(和飞船、空间站)系列都提供对海洋的观测,从而构成中国卫星海洋观测系统。按装载的传感器分类,进而给出中国的海色、海表温度、海面高度、海面风场和合成孔径雷达(SAR)卫星观测系统。对中国海洋观测卫星与国际海洋观测卫星装载的传感器性能作了比较和讨论,指出差距。列出目前在轨运行的中国海洋卫星观测系统38个传感器及其类似的国外卫星传感器。  相似文献   

若干西边界潜流的气候态分布特征     

臧楠  王凡  吴德星 《中国海洋大学学报(自然科学版)》2011,41(9):1-8

"西边界潜流(WBUC)"是海洋环流中的重要现象,与表层环流相比,对次表层潜流的结构认识不足。本文利用SODA、OFES和ARGO资料,分析了北太平洋中的棉兰老潜流(MUC)和吕宋潜流(LUC)、南太平洋中的大堡礁潜流(GBRUC)和东澳大利亚潜流(EAUC)及南印度洋中的阿加勒斯潜流(AUC)的气候态空间分布特征,并且根据地转流反向的判据,分析WBUC的发生条件。  相似文献   

The domestic divide: Access to the Internet in New Zealand     

Jeremy Greenbrook‐Held  Philip S. Morrison 《New Zealand geographer》2011,67(1):25-38

We use unit records of the 2006 census to show that access to the Internet in the home varies geographically in New Zealand primarily as a result of demographic and socio‐economic differences among individuals. Of particular significance is the much lower rates of domestic access experienced by Māori and Pacific Island individuals even after controlling for differences in their age, gender, education, income, occupation and settlement type. While differences in Internet access by ethnicity has been noted before, it is the magnitude and persistence of this difference in New Zealand after controlling for correlated factors that renders this study unique. Our results have important implications in an education environment increasingly reliant on Web access, but they also raise questions about the extent of access to the Internet outside the home.  相似文献