长江河口横沙东滩自然演变及工程影响

横沙东滩(含横沙浅滩)是长江河口主要浅滩之一,在浅滩两侧(北港和北槽主槽)水流控制下,受浅滩横比降形成的过滩水流和较强的风浪作用影响,滩面长期以来少有淤涨。通过对1995～2002年的地形资料(吴淞基面)进行研究分析表明:从总体上看随着北港主槽向南岸进逼,造成横沙东滩窜沟西部到白条子沙之间的滩区北沿明显内凹;随着长江口深水航道治理双导堤工程的实施,在北导堤产生的堵汊、导流和拦沙的作用下,白条子沙至横沙东滩沟滩面出现微淤;而横沙东滩窜沟以东滩面难以淤高。采用促淤工程和就近吹泥上滩方式,增加横沙东滩的滩面高程以加快造地,从而达到既疏浚航道又增加湿地面积的双赢效果。     

赤道西太平洋末次盛冰期以来的浮游有孔虫氧碳稳定同位素记录

对西太平洋暖池核心区MD01—2386柱状样最上部5m进行了高分辨率的浮游有孔虫Globigerinoides ruber和Pulleniatina obliquiloculata的氧、碳稳定同位素分析,结合AMS^14C测年,研究表明其属于末次盛冰期-全新世的沉积。赤道西太平洋海区末次盛冰期以来δ^18O值显著降低,但有几次回返事件。表层浮游有孔虫G．ruber比次表层温跃层属种P．obliquiloculata对于环境变化的响应要快,但后者变化的幅度较大。这两个种的氧、碳同位素差值反映出温跃层深度自末次盛冰期以来逐渐加深,并存在周期性的回返事件,说明西太平洋暖池晚第四纪冰期旋回存在气候不稳定性。     

基于海洋资源环境承载力的海上油田环境保护管理研究

文章结合《资源环境承载能力监测预警技术方法(试行)》,通过分析海洋资源环境承载能力与海上油田环境保护管理的相关性,提出了海上油田全生命周期环境保护管理的新思路。同时结合海上油田的项目特点,探讨了现阶段海洋资源环境承载力监测预警技术在功能区划、管控要求和监测预警中可能存在的不协调、不一致和不断变化的问题,并提出了统一用海类型及其管控要求、差异化政策措施和动态分析的建议。     

Wintertime rates of net primary production and nitrate and ammonium uptake in the southern Benguela upwelling system

The elevated levels of primary productivity associated with eastern boundary currents are driven by nutrient- rich waters upwelled from depth, such that these regions are typically characterised by high rates of nitrate-fuelled phytoplankton growth. Production studies from the southern Benguela upwelling system (SBUS) tend to be biased towards the summer upwelling season, yet winter data are required to compute annual budgets and understand seasonal variability. Net primary production (NPP) and nitrate and ammonium uptake were measured concurrently at six stations in the SBUS in early winter. While euphotic zone NPP was highest at the stations nearest to the coast and declined with distance from the shore, a greater proportion was potentially exportable from open-ocean surface waters, as indicated by the higher specific nitrate uptake rates and f-ratios (ratio of nitrate uptake to total nitrogen consumption) at the stations located off the continental shelf. Near the coast, phytoplankton growth was predominantly supported by ammonium despite the high ambient nitrate concentrations. Along with ammonium concentrations as high as 3.6 µmol l^–1, this strongly suggests that nitrate uptake in the inshore SBUS, and by extension carbon drawdown, is inhibited by ammonium, at least in winter, although this has also been hypothesised for the summer.     

Reproductive biology of Parazoanthus axinellae (Schmidt, 1862) and Savalia savaglia (Bertoloni, 1819) (Cnidaria,Zoantharia) from the NW Mediterranean coast

Despite the wide distribution of zoanthids, little is known about their pattern of reproduction. Here we investigate the reproductive biology of two Mediterranean species, the common Parazoanthus axinellae (Schmidt) and the rare Savalia savaglia (Bertoloni). For both species, samples were collected during an annual cycle, from January to December 2005, in the Western Mediterranean (Ligurian Sea, Italy). Both species are gonochoric. In P. axinellae the sex‐ratio (n colonies = 30) showed a slight predominance of male colonies (M/F = 1.35), whereas in the population of S. savaglia (n colonies = 15) a predominance of females was found (M/F = 0.3). In P. axinellae the first gametocytes were visible in March, whereas in S. savaglia they became visible in May. Both species reproduce at the end of autumn when seawater temperature begins to decrease. Parazoanthus axinellae (10 m depth) spawns eggs and sperms in November, whereas S. savaglia (67 m depth) spawns in December. In P. axinellae sexes were segregated on a rocky wall, with males occurring deeper, whereas male and female colonies of S. savaglia were irregularly dispersed in the population. The maximum number of oocytes differed between the species, being higher in P. axinellae than in S. savaglia.     

Benthic nutrient fluxes along the Laurentian Channel: Impacts on the N budget of the St. Lawrence marine system

Water column concentrations and benthic fluxes of dissolved inorganic nitrogen (DIN) and oxygen (DO) were measured in the Gulf of St. Lawrence and the Upper and Lower St. Lawrence Estuary (USLE and LSLE, respectively) to assess the nitrogen (N) budget in the St. Lawrence (SL) system, as well as to elucidate the impact of bottom water hypoxia on fixed-N removal in the LSLE. A severe nitrate deficit, with respect to ambient phosphate concentrations (N*∼−10 μmol L⁻¹), was observed within and in the vicinity of the hypoxic bottom water of the LSLE. Given that DO concentrations in the water column have remained above 50 μmol L⁻¹, nitrate reduction in suboxic sediments, rather than in the water column, is most likely responsible for the removal of fixed N from the SL system. Net nitrate fluxes into the sediments, derived from pore water nitrate concentration gradients, ranged from 190 μmol m⁻² d⁻¹ in the hypoxic western LSLE to 100 μmol m⁻² d⁻¹ in the Gulf. The average total benthic nitrate reduction rate for the Laurentian Channel (LC) is on the order of 690 μmol m⁻² d⁻¹, with coupled nitrification-nitrate reduction accounting for more than 70%. Using average nitrate reduction rates derived from the observed water column nitrate deficit, the annual fixed-N elimination within the three main channels of the Gulf of St. Lawrence and LSLE was estimated at 411 × 10⁶ t N, yielding an almost balanced N budget for the SL marine system.     

基于测井频谱分析的松科二井登娄库组地层沉积速率研究

松辽盆地科学钻探工程松科二井获取了白垩纪陆相沉积资料,其中连续、多参数、高分辨率的地球物理测井资料为研究松辽盆地地层的沉积速率变化规律提供了机会。本文利用GR、Th、K、Th/K多种测井数据,采用天文旋回的方法来计算松科二井登娄库组地层的沉积速率,并探讨影响地层沉积的主控因素。多种测井数据的频谱分析结果表明了登娄库组地层记录着米兰科维奇旋回信息,这说明登娄库组沉积过程受天文轨道驱动力影响。Th测井数据对天文旋回信息的敏感性强,综合考虑多种测井数据的测试结果获得了连续、相对准确的地层沉积速率。登娄库组地层沉积速率从下往上整体呈现为由高到低的趋势。登二段至登三段时期地层沉积主要受盆地断陷活动控制,地层整体具有高沉积速率特征,最高达到16.2 cm/ka。随后至登四段时期由于断陷活动逐渐减弱,盆地向区域坳陷的构造格局转化,登四段整体具有沉积速率较低的特征,最低为5.9cm/ka。该研究建立了松科二井登娄库组地层连续的沉积速率剖面,为揭示松辽盆地由断陷活动过渡到坳陷活动的地质规律提供了测井证据。     

长春台磁暴特征研究

依据长春地震台记录的磁暴资料,系统总结了第19、20、21三个太阳活动周磁暴特征,并对全球M_s≥7.8级地震的发生与太阳黑子活动、磁暴的关系进行了初步探讨。     

The biogeochemical sulfur cycle in the marine boundary layer over the Northeast Pacific Ocean

The major components of the marine boundary layer biogeochemical sulfur cycle were measured simultaneously onshore and off the coast of Washington State, U.S.A. during May 1987. Seawater dimethylsulfide (DMS) concentrations on the continental shelf were strongly influenced by coastal upwelling. Concentration further offshore were typical of summer values (2.2 nmol/L) at this latitude. Although seawater DMS concentrations were high on the biologically productive continental shelf (2–12 nmol/L), this region had no measurable effect on atmospheric DMS concentrations. Atmospheric DMS concentrations (0.1–12 nmol/m³), however, were extremely dependent upon wind speed and boundary layer height. Although there appeared to be an appreciable input of non-sea-salt sulfate to the marine boundary layer from the free troposphere, the local flux of DMS from the ocean to the atmosphere was sufficient to balance the remainder of the sulfur budget.