黄东海海区总悬浮物散射特性研究

我国黄东海水体散射特性非常复杂,这是造成该海域水色区划特点显著的原因之一。文中利用2003年4月黄东海试验数据(HD200304)对总悬浮物(TSM,Total Suspended Matter)的后向散射概率~bbs和单位散射系数bs*进行研究。基于对现场数据的统计分析,我们开发了总悬浮物后向散射概率模型,通过相对偏差分析表明,有近90%的样品反演相对偏差控制在±30%之内。对总悬浮物单位散射系数研究时,选择555 nm为参考波段,开发了不同波段间总悬浮物单位散射系数关系模型,通过相对偏差分析表明,有近94%的样品反演相对偏差在±10%之内,反演效果非常好。     

海洋测绘中影像图与港口航道图的镶嵌技术运用

文中介绍陆地影像图与港口航道图镶嵌的制图工艺,影像图与港口航道图镶嵌后的成图质量评价。简单阐述了作者在绘制该图种过程中的一些体会,以及影像图取代现有港口航道图上陆地地形的可行性。     

一种准确通用的台风路径预报模式

应用天气学理论,对台风云图的晴空区轴线制约台风移动的规律进行物理解释。根据台风云团与晴空区之间存在的干、湿梯度力和推动台风前进的惯性力的互相关系,建立台风移向预报方程和轨迹预报方程,分析论证了台风移向变化的物理过程,把影响台风移动的复杂因子转化为单一的预报因子。     

改进的Hough变换在机场跑道检测中的应用

提出了一种改进的Hough变换方法用于机场跑道的检测。传统Hough变换存在计算量大等缺陷,本文利用直线边缘的梯度相位信息把Hough变换中θ的取值限定在一个较小的范围内,同时减少用于计算的像素点数,大大降低了计算量。通过实验证明了本文方法切实可行。     

Environmental limitations on recruitment from seed in invasive Spartina densiflora on a southern European salt marsh

The South American cordgrass, Spartina densiflora, has invaded a range of different habitats that can support different native species assemblages on salt marshes in the Gulf of Cadiz, Spain. Little is known about the mechanisms of invasion. We examined the potential for seed germination and recruitment in a field transplant experiment, representing a wide range of environments, on elevational gradients across marshes with muddy and sandy sediments. The biotic resistance of native, perennial vegetation (where present) to recruitment of the alien was also investigated. Spartina densiflora seeds were able to germinate over a greater than 2-m range of elevation in the tidal frame. Germination success on unvegetated muddy sediments was related to sediment redox potential, with poor germination at strongly negative redox potentials on the lower sites. On sandy, well-drained sediments, germination was apparently constrained by water availability at the highest elevations. Comparison of vegetated and cleared plots on the upper marsh showed that there was a negative relationship between the presence of Atriplex portulacoides and germination on the muddy sediments. Recruitment (survival of seedlings for 12 weeks) was seen only on unvegetated muddy sediments at the highest elevation. Hence the invasive success and wide elevational tolerance of S. densiflora on the marshes of the Gulf of Cadiz are not reflected in its short-term ability to become established from its prolific seed production. Colonization of sub-optimal habitats may be largely by vegetative propagules and clonal growth.     

Dissolved inorganic carbon (DIC) and its carbon isotopic composition in sediment pore waters from the Shenhu area,northern South China Sea

The Shenhu area is one of the most favorable places for the occurrence of gas hydrates in the northern continental slope of the South China Sea. Pore water samples were collected in two piston cores (SH-A and SH-B) from this area, and the concentrations of sulfate and dissolved inorganic carbon (DIC) and its carbon isotopic composition were measured. The data revealed large DIC variations and very negative δ ¹³C-DIC values. Two reaction zones, 0–3 mbsf and below 3 mbsf, are identified in the sediment system. At site SH-A, the upper zone (0–3 mbsf) shows relatively constant sulfate and DIC concentrations and δ ¹³C-DIC values, possibly due to bioturbation and fluid advection. The lower zone (below 3 mbsf) displays good linear gradients for sulfate and DIC concentrations, and δ ¹³C-DIC values. At site SH-B, both zones show linear gradients, but the decreasing gradients for δ ¹³C-DIC and SO₄ ²⁻ in the lower zone below 3 mbsf are greater than those from the upper zone, 0–3 mbsf. The calculated sulfate-methane interface (SMI) depths of the two cores are 10.0 m and 11.1 m, respectively. The depth profiles of both DIC and δ ¹³C-DIC showed similar characteristics as those in other gas hydrate locations in the world oceans, such as the Blake Ridge. Overall, our results indicate an anaerobic methane oxidation (AMO) process in the sediments with large methane flux from depth in the studied area, which might be linked to the formation of gas hydrates in this area.     

氮磷营养盐对中肋骨条藻生长及硝酸还原酶活性的影响

通过实验室培养,在不同氮磷浓度及氮磷比率的营养条件下,对中肋骨条藻（Skeletonema costatum）的生长及藻细胞硝酸还原酶的活性进行研究。实验结果表明,中肋骨条藻属于营养型藻类,氮磷营养盐的添加,极大地促进了藻细胞的增殖。在接种后的第4～5天,各培养组藻密度达到最大值并与对照组形成极显著性差异（P〈0．01）。实验进一步发现,环境中的氮、磷浓度及氮磷比率都会影响中肋骨条藻的生长及藻细胞硝酸还原酶活性（NRA）。此外,在各培养组中,中肋骨条藻硝酸还原酶活性的最大值（NRAmax）均出现在指数生长期（接藻后第1,2天）,早于最大藻密度的出现时间（第4,5天）,这表明藻对营养盐的同化速率与生长速率并不一致,后者存在一定的滞后效应。在本实验条件下,中肋骨条藻的硝酸还原酶活性存在一定的阈值。     

Communities structure of the planktonic halophiles in the solar saltern of Sfax,Tunisia

The composition and distribution of the main planktonic halophilic micro-organisms (heterotrophic and autotrophic picoplankton, nanoplankton, phytoplankton, ciliates) and metazooplankton were investigated in six ponds of increasing salinity in the solar salt works of Sfax, Tunisia, from January to December 2003. Marked changes in the composition and biomass of the communities were found along the salinity gradient, especially at salinities of 150 and 350. Autotrophic picoplankton, nanoplankton, diatoms, dinoflagellates and ciliates characterized the less salted ponds. Planktonic biomass was the highest at intermediate salinity as a consequence of a bloom of Ochromonas. Species richness of phytoplankton, ciliates and zooplankton greatly decrease above a salinity of 150 and typical halophiles (Dunaliella salina, cyanobacteria, Fabrea salina and Artemia salina) were found between 150 and 350 salinity. In this environment, F. salina appeared more adapted than the brine shrimp to survive during phytoplankton blooms. The halophilic plankton was however almost entirely composed of heterotrophic prokaryotes in the crystallizers. We thus observed a progressive disappearance of the autotrophic planktonic communities along the salinity gradient. Multivariate analysis of the communities provides evidence that ponds represent discrete aquatic ecosystems within this salt works.     

Macrofaunal communities in the habitats of intertidal marshes along the salinity gradient of the Schelde estuary

The macrobenthos is important in benthic remineralization processes; it represents a trophic link and is also often used as a bio-indicator in monitoring programs. Variations of the environmental parameters strongly influence the structure of the macrobenthic communities in the marshes and since macrobenthos is the most important food item for marsh-visiting fish species in the Schelde, the variation in food resources can have a strong effect on the higher trophic level. The present study deals with the variation in macrobenthic communities in different habitats of intertidal marshes along the salinity gradient and the differences between the marsh creeks and the intertidal part of the estuary. The study measured density and species richness together with the biomass, and sampled a large intertidal channel and a smaller creek within five marshes along the salinity gradient of the Schelde estuary every six weeks between May and October in 2000.     

Resolving physically and biologically driven suspended particulate matter dynamics in a tidal basin with a distribution-based model

Understanding suspended particulate matter (SPM) dynamics in coastal waters is crucial to assess changes in coastal sediment budgets and biogeochemical fluxes. SPM dynamics are subject to various physical and biological factors and processes such as, e.g. tidal currents and aggregation which can be enhanced by extracellular polymeric substances (EPS) that are produced by algae and bacteria. It is still unclear how the different factors and processes interact and together determine SPM dynamics. To unravel the interacting processes and factors, we propose a new distribution-based modeling approach. Based on the derivation of explicit equations for size distribution characteristics of SPM such as the average radius, we derived a model of reduced complexity characterized by low initialization and parameterization effort as well as low computational cost. The proposed 0D model includes the processes of aggregation and fragmentation due to shear, aggregation due to differential settling, deposition, resuspension and tidal exchange, and describes the evolution of the SPM concentration in the water column linked by the settling velocity to the change of the mass average radius of the aggregate distribution. A systematic parameter variation for critical bottom shear stress of erosion, the size of resuspended aggregates, the fractal dimension, the collision efficiency, and the aggregate strength has been performed and compared to observations in the back-barrier basin of Spiekeroog Island in the German Wadden Sea. This analysis confirms the hypothesis that in winter biological influences on SPM dynamics are smaller compared to summer. This is mainly reflected by a significant shift in the various parameters. We hence conclude that biological control mechanisms have a much more quantitative relevance for SPM dynamics than currently represented by state-of-the-art SPM transport models.