Physical and biological correlates of virus dynamics in the southern Beaufort Sea and Amundsen Gulf

As part of the Canadian Arctic Shelf Exchange Study (CASES), we investigated the spatial and seasonal distributions of viruses in relation to biotic (bacteria, chlorophyll-a (chl a)) and abiotic variables (temperature, salinity and depth). Sampling occurred in the southern Beaufort Sea Shelf in the region of the Amundsen Gulf and Mackenzie Shelf, between November 2003 and August 2004. Bacterial and viral abundances estimated by epifluorescence microscopy (EFM) and flow cytometry (FC) were highly correlated (r² = 0.89 and r² = 0.87, respectively), although estimates by EFM were slightly higher (FC = 1.08 × EFM + 0.12 and FC = 1.07 × EFM + 0.43, respectively). Viral abundances ranged from 0.13 × 10⁶ to 23 × 10⁶ ml^− 1, and in surface waters were ~ 2-fold higher during the spring bloom in May and June and ~ 1.5-fold higher during July and August, relative to winter abundances. These increases were coincident with a ~ 6-fold increase in chl a during spring and a ~ 4-fold increase in bacteria during summer. Surface viral abundances near the Mackenzie River were ~ 2-fold higher than in the Mackenzie Shelf and Amundsen Gulf regions during the peak summer discharge, concomitant with a ~ 5.5-fold increase in chl a (up to 2.4 μg l^− 1) and a ~ 2-fold increase in bacterial abundance (up to 22 × 10⁵ ml^− 1). Using FC, two subgroups of viruses and heterotrophic bacteria were defined. A low SYBR-green fluorescence virus subgroup (V2) representing ~ 71% of the total viral abundance, was linked to the abundance of high nucleic acid fluorescence (HNA) bacteria (a proxy for bacterial activity), which represented 42 to 72% of the bacteria in surface layers. A high SYBR-green fluorescence viral subgroup (V1) was more related to high chl a concentrations that occurred in surface waters during spring and at stations near the Mackenzie River plume during the summer discharge. These results suggest that V1 infect phytoplankton, while most V2 are bacteriophages. On the Beaufort Sea shelf, viral abundance displayed seasonal and spatial variations in conjunction with chl a concentration, bacterial abundance and composition, temperature, salinity and depth. The highly dynamic nature of viral abundance and its correlation with increases in chl a concentration and bacterial abundance implies that viruses are important agents of microbial mortality in Arctic shelf waters.     

Calculation of the coefficient and dynamics of water diffusion in graphite joints

1Introduction Comparedwithtraditionaljoiningmethodssuchasrive tingandbolting,adhesivetechnologycansimplifyas semblingprocesses,increaseproductivityandquality,aswellasreduceproductioncost.Thereforeithas beenwidelyusedinmodernshipbuildingengineering,suchass…     

浅水中质量源造波方法

针对质量源造波过程中源区上方水体高度难以确定的问题提出了改进方法,将源区高度值考虑到源强方程中,避免了造波过程中源区上方水体高度值多次试算带来的不便。该方法弥补了质量源造波方法在水深小于1.5 m的浅水中所造波浪与理论波浪之间差距较大的缺陷,尤其是水平网格步长与源区高度值相比小于10的情况,推广了质量源造波方法在浅水中的应用。文中验证了波高对所造波浪的影响以及时间步长对浅水中所造波浪的影响,得出结论:当波高与水深的比值小于0.2时所造波浪波高与理论值的拟合较好;当时间步长小于0.005 s时所造波浪无明显的上下漂浮现象,波形稳定,符合理论波形要求。     

亚丁湾上的护航人

亚丁湾,北临阿拉伯半岛,南望"非洲之角",西接曼德海峡,东濒阿拉伯海及印度洋,是船只快捷往来地中海和印度洋的必经之路,享有"海上生命线"、"黄金水道"之称,是世界各国贸易和能源运输的重要航线。然而索马里海盗的肆虐,彻底打破了这一水域的安宁,尤其是进入2008年后,几乎每天都有船舶遭到袭扰,平均每4天就有一艘船只被劫持。作为世界航运大国和贸易大国,我国每年航经亚丁湾的中国籍船舶就达近3000艘次。     

Estimating salinity to complement observed temperature: 1. Gulf of Mexico

This paper and its companion [Thacker, W.C., Sindlinger, L., 2007-this issue. Estimating salinity to complement observed temperature: 2. Northwestern Atlantic. Journal of Marine Systems. doi:10.1016/j.jmarsys.2005.06.007.] document initial efforts in a project with the goal of developing capability for estimating salinity on a region-by-region basis for the world oceans. The primary motivation for this project is to provide information for correcting salinity, and thus density, when assimilating expendable-bathythermograph (XBT) data into numerical simulations of oceanic circulation, while a secondary motivation is to provide information for calibrating salinity from autonomous profiling floats. Empirical relationships between salinity and temperature, which can be identified from archived conductivity–temperature–depth (CTD) data, provide the basis for the salinity estimates.The Gulf of Mexico was chosen as the first region to explore for several reasons: (1) It's geographical separation from the Caribbean Sea and the North Atlantic Ocean makes it a “small ocean” characterised by a deep central basin surrounded by a substantial continental shelf. (2) The archives contain a relatively large number of CTD data that can be used to establish empirical relationships. (3) The sharp fronts associated with the Loop Current and its rings, which separate water with different thermal and haline characteristics, pose a challenge for estimating salinity. In spite of the shelf and the fronts, the relationship between salinity and temperature was found to be sufficiently regular that a single empirical model could be used to estimate salinity on each pressure surface for the entire Gulf for all seasons. In and below the thermocline, root-mean-square estimation errors are small — less than 0.02 psu for pressures greater than 400 dbar, corresponding to potential density errors of less than 0.015 kg/m³. Errors for estimates nearer to the surface can be an order of magnitude larger.     

墨西哥湾溢油启示录

墨西哥湾原油泄漏事件,让全世界为之震惊,海上石油开采与海上石油运输的生态风险,又一次让世人高度关注。正值＂六·五世界环境日＂之际,本刊选取了墨西哥湾溢油启示、油污基金出台、原油过驳监管等多个题材进行报道,希望能对我国水域环境保护有所借鉴。     

Trace metals in water, sediments and marine organisms from the northern part of the Gulf of Suez, Red Sea

Concentrations of Cd, Pb, Cu and Zn were determined in water, sediments, gastropod (Bulla umpulla) and green algae (Ulva lactuca) collected from five stations in the western side of the northern part of the Gulf of Suez during the period February 1993–January 1994. Sediments recorded the highest concentrations of Cd (2.26–4.40 μg/g) and Pb (13.90–28.34 μg/g), While the highest concentrations of the essential metals Cu and Zn were found in B. umpulla (28.19–72.04 and 60.24–108.74 μg/g, respectively). Water and sediments showed similar spatial distribution patterns for the highest mean values of the different metals. Highest values of the studied metals were found at stations influenced by various pollution sources such as harbours, and sewage and industrial drains. In contrast, the lowest concentrations were observed faraway from any pollution source. Calculations of concentration factors (C.F.) for gastropod and algae showed highest C.F. of Cd (4312.5–8705.9) and Pb (2103.3–8317.9) in algae, and highest C.F. of Cu (5288.9–42376.5) and Zn (3686.7–9631.5) in gastropod.     

Initial results from long-term measurements of atmospheric humidity and related parameters in the marine boundary layer at two locations in the Gulf of Mexico

Measurements of boundary layer moisture have been acquired from Rotronic MP-100 sensors deployed on two NDBC buoys in the northern Gulf of Mexico from June through November 1993. For one sensor, which was retrieved approximately 8 months after deployment, the post- and precalibrations agreed closely and fell well within WMO specifications for accuracy. The second sensor operated continuously from June 1993 to February 1997 (3.5 years). Buoy observations of relative humidity and supporting data were used to calculate specific humidity and the surface fluxes of latent and sensible heat. Specific humidities from the buoys were compared with observations of moisture obtained from nearby ship reports, and the correlations were generally high (0.7–0.9). Surface gravity wave spectra were also acquired. The time series of specific humidity and the other buoy parameters revealed three primary scales of variability, small (h), synoptic (days), and seasonal (months). The synoptic variability was clearly dominant and occurred primarily during September, October, and November. Most of the synoptic variability was due to frontal systems that dropped down into the Gulf of Mexico from the continental US followed by air masses which were cold and dry. Cross-correlation analyses of the buoy data indicated that: (1) the moisture field was highly coherent over distances of 800 km or more in the northern Gulf of Mexico; and (2) both specific humidity and air temperature served as tracers of the motion associated with propagating atmospheric disturbances. These correlation analyses also revealed that the prevailing weather systems generally entered the buoy domain from the South prior to September, but primarily from the North thereafter. Spectra of the various buoy parameters indicated strong diurnal and semidiurnal variability for barometric pressure and sea surface temperature (SST) and lesser variability for air temperature, wind speed and significant wave height. The surface fluxes of latent and sensible heat were dominated by the synoptic events which took place from September through November with the transfer of latent heat being primarily from the ocean to the atmosphere. Finally, an analysis of the surface wave observations from each buoy, which included calculations of wave age and estimates of surface roughness, indicate that major heat and moisture flux events coincide with periods of active wave growth, although the data were insufficient to identify any causal relationships.     

冬季庙岛群岛南部海域浮游植物群落结构及其与环境因子的关系

2013年2月对庙岛群岛南部海域浮游植物群落及环境因子进行了采样调查,并利用PRIMER v6软件包中包含的一系列多元统计程序进行分析。结果表明,此次调查共采集到浮游植物82种,其中硅藻64种,是研究区域浮游植物的主要类群。研究海域根据水环境梯度可划分为5组,组Ⅰ为高温高盐组,组Ⅱ为高p H高营养盐组,组Ⅲ为低营养盐组,组Ⅳ为高磷酸盐和硅酸盐组,组Ⅴ为高p H高无机碳组。依据丰度进行了CLUSTER聚类和MDS标序图分析,结果可将研究站位划分为6个群落组。BIOENV分析结果表明,p H、盐度(Sal)和溶解有机碳(DTOC)组合可以最好地解释本次调查的浮游植物群落结构。     

新型深水绷紧式系泊系统动力特性分析

通过对工作水深为1 500 m的新型绷紧式系泊系统中单根系缆进行动刚度和动张力计算,并与静刚度下计算结果比较,说明了在合成纤维系缆数值计算中考虑其动刚度特性的必要性;传统动刚度计算中将整条系缆作为直线考虑,假定系缆上的应力和应变处处相同,不考虑系缆自身重量,且忽略流体动力作用,这些假设和忽略降低了计算精度;基于集中质量法建立了系缆的动力学模型,提出采用分段动刚度方法通过迭代计算各缆段上的动刚度和动张力,并考虑了系缆自身重量、流体动力和海流等因素的影响;由于传统方法中取预张力作为平均张力计算会降低精度,于是提出基于统计的方法计算各缆段的平均张力,并用于该缆段动刚度的计算。该研究对于绷紧式系泊系统的数值分析和工程应用具有重要的意义。     

Winter intensification and water mass evolution from yearlong current meters in the Northeast Water Polynya

In the summer of 1992, four current meter moorings were deployed in and later retrieved from the Northeast Water (NEW) polynya on the East Greenland Shelf by the USCGC Polar Sea. The moorings provided hourly temperature, salinity and current data for approximately one year. In the NEW, the circulation intensified and steadiness increased during winter. This intensification was most readily observed at 150 m on the southern side of Westwind trough. The surface layer freshened from summer through December due to ice-melt and freshwater runoff mixing down to at least 75 m. From December through early spring, salinity increased probably due to brine rejected during ice formation. Wintertime events showed water at 75 m with temperatures at the freezing point. Knee Water (KW) was not observed in the current meter data. However, a warmer and fresher than KW watermass was observed at 150 m over the shelf and may result from mixing outside the NEW among KW and the major water masses influencing the region. Polar Water and Atlantic Intermediate Water. Several short-lived events of 3 to 7 days duration perturbed the T-S character at each of the current meters. We believe that these T-S shifts were anticyclonic eddies advecting through the NEW polynya. During such perturbations, T-S values found generally at 75 m were observed at 150 m and T-S values generally at 150 m were observed at 250 m. On the northern side of the Westwind trough, the current meter data provided direct evidence for westward flow into the western extent of the trough at a depth of 250 m. This southwesterly current along the northwest slope of the trough at 250 m is in agreement with the summertime ADCP measurements made in 1992 aboard Polar Sea, and is consistent with the flow inferred from summer hydrography measured from Polarstern in 1993.     

Simulated responses of the Gulf of Mexico hypoxia to variations in climate and anthropogenic nutrient loading

A mathematical model was used to simulate monthly responses of the Gulf of Mexico hypoxia to variations in climate and anthropogenic nutrient loading over a 45-year period. We examined six hypothetical future scenarios that are based on observed and projected changes in the Mississippi River discharge, Mississippi River nitrate concentrations, and ambient water temperatures. In particular, we investigated the implications of a 30% decrease in the Mississippi River nitrogen flux, which was recently proposed by the Mississippi River Watershed/Gulf of Mexico Hypoxia Task Force as a measure to reduce the size of the hypoxic zone. Model simulations suggest that the frequency of hypoxia in the northern Gulf of Mexico is highly sensitive to variations in riverine nitrate flux, but also to variations in freshwater discharge and ambient water temperatures. A 30% decrease in the Mississippi River nitrate flux, for example, would reduce the frequency of hypoxia by 37%. Nevertheless, a 20% increase the Mississippi River discharge, which may occur under some climate change scenarios, would produce an increase in the frequency of hypoxia of the same magnitude. Thus, if the potential climatic variations are taken into account, a 30% decrease in the nitrogen flux of the Mississippi River may not be sufficient to accomplish the proposed hypoxia management goal.     

A two-dimensional response to a tropical storm on the Gulf of Mexico shelf

Surface current data from drifting buoys and remotely sensed wind data recorded over the continental shelf in the northeastern Gulf of Mexico during the passage of tropical storm Josephine in October 1996 are examined. Drifter data show the existence of a strong surface jet (velocities reaching 1 m s⁻¹) that moves up the west Florida shelf and westward along the Louisiana–Texas shelf, and lasts for nearly 1 week. The coastal jet occurs during an intense synoptic scale wind event where wind speeds reach 15 m s⁻¹. A simple force balance and statistical analysis are performed to assess the role of strong wind forcing. The primary balance shows an Ekman-type current. The role of local acceleration is greatest when winds are directed along bathymetry. A simple two-dimensional strongly forced shelf response model developed from the linear steady-state momentum equations also indicates larger along-shore currents due to both Ekman-type forcing by cross-shore winds and a cross-shore pressure gradient arising from conservation of mass. Model parameters fit empirically are within 15% of theoretical values. The simple model explains 30% and 46% of the variance in the observed along-shore and cross-shore surface currents, respectively.     

泛北部湾港口群合作与成长的愿景

伴随中国一东盟自由贸易区的建立和发展，泛北部湾区域经济与合作的宏大前景和深厚潜力，已经并将继续展示一个足以令人信服的愿景：以北部湾和南海连成的海域为中心、包容中国和东盟11国100多个各类主要港口的国际港口群，将在不久的将来迅速崛起为世界性的大港及区域航运中心。     

单体热射流水团浮升扩散规律研究

水下航行体热射流排放可能会在水面上形成一定的红外特征,该红外特征会影响到其本身的隐身性能,因而研究热尾流的浮升扩散机理具有重要的意义。建立研究水下单体热射流水团浮升扩散规律的二维数学模型,利用Fluent软件对热射流浮升扩散规律进行二维数值模拟研究,利用SST k-omega湍流模型和有限体积法,得到单体热射流水团在水下浮升的浮升扩散规律及温度分布特性。利用该数学模型进一步研究对比初始速度的大小、方向及温差对单体热射流水团的浮升扩散的影响,分析得到单体热射流水团在几种因素影响下的温度分布规律及其运动轨迹。     

亚丁湾附近海域海盗犯罪的特点、成因及对策研究

近期,亚丁湾海域及索马里沿海海盗犯罪成为此海域海上安全的严重威胁。在认清当前海盗犯罪的特点及其成因的基础上,船方必须采取相应的防范和应急处理措施,确保船舶和船员生命安全。     

北部湾港口资源整合研究

文中系统分析了北部湾港口资源的情况,并分析了北部湾港口资源发展存在核心竞争力不强、“铁路瓶颈”制约、港口自身造血功能差等问题阻碍了港口资源的发展,港口资源需要进行整合。在探讨完港口资源整合具备可行性的基础上,进行了港口资源整合目的、定位、范围和模式等方面的思考,并在此基础上提出北部湾港口资源应该突破瓶颈,做到“六个统一”,走体制创新之路。     

关于长江航运安全方面几个问题的便民解答

一、三峡库区蓄米156米后,库区船舶停泊时应注意哪些事项?答:随着三峡水库156米运行及三峡船闸完建工程实施单线运行,三峡库区航路和锚泊区发生了很大变化,长江海事局结合船舶流量和水情变化实际,在三峡库区调整和增设了150个船舶临时停泊区,其中普通船舶停泊区145个,危险品船舶停泊区5个,对每个停泊区的地点位置、范围及停泊的数量和船舶种类都有具体规定     

Coastal energy impact mitigation in the Gulf: The past reviewed and alternatives for the future

Abstract

With the future of the Coastal Energy Impact Program (CEIP) in question and with oil and gas leasing and drilling activities in the Gulf of Mexico expected to increase, the question arises as to how energy impacts are to be mitigated. It is concluded that CEIP has helped to mitigate coastal energy impacts. If it is left unfunded, an alternative would be to provide Outer Continental Shelf (OCS) royalties to states to be used for impact prevention and mitigation.     

证书有效期的检查缺陷

船舶证书的有效性是关系到船舶PSC检查是否被执行更详细检查的“明显理由”和判定船舶是否被滞留的重要因素。1974年SOLAS公约通过以后,又经过1978年议定书、1988年议定书以及许多次修正案的修正,修正前后内容更改很大。依照不同的议定书及修正案签发的船舶证书在证书格式、检验类型、证书签注和有效期上有很大的不同,是PSC检查官开展日常PSC检查的重点项目,应引起船公司、船级社的高度重视。