Theoretical wind wave frequency spectra in shallow water

The method developed by Wen et al. (1988 a) for deriving theoretical wind wave frequency spectrum in deep water is extended to the case of water of finite depth, in which a parameter η=H/d is introduced, where H and d represent the average wave height and water depth respectively. The derived spectra reduce to those in deep water when η=0. The case of η=1/2 corresponds to waves impending to break because of the effect of the bottom. Simplified forms of spectra are given. The theoretical results agree with the observed spectra well.     

Anthropogenic trace metals in sediment and settling particulate matter on a high-energy continental shelf (Sydney,Australia)

The anthropogenic contribution of trace metals to settling particulate matter (SPM) and surficial sediments was determined on the high-energy continental shelf adjacent to Sydney, Australia. Settling particulate matter and surficial sediment was collected in the vicinity of a major sewage outfall and at five control sites on the middle shelf (80-100 m water depth). Sediment traps were deployed on 10 occasions for up to 2 weeks during the summer and winter of 1995 and SPM was analyzed for Ag, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Cobalt, Fe, Mn and Ni act conservatively in SPM and in sediments regionally and are used as normalizing elements to determine anthropogenic enrichment. Surficial sediments and SPM are enriched in Ag, Cr, Cu, Pb and Zn near a major ocean outfall and at four of the five control sites, although sewage particles contribute < 5% of trace metals in the total sample. Silver is the most sensitive trace metal tracer for establishing the presence of sewage particulate matter. Sewage particulate matter flux near the outfall was estimated using a two end-member mixing model and is below 0.5 g m(-2) day(-1) during all deployment periods. The mean sewage particulate matter flux at sampling locations 30 km and 60 km north of the outfall are <0.13 g m(-2) day(-1) and <0.01 g m(-2) day(-1), respectively, indicating an efficient dispersal of anthropogenic material on this high energy continental shelf.     

大西洋中脊的热液矿泉

在过去10年中，通过国际合作，对大西洋中肯的热液矿泉及周围地质背景进行了研究。TAG热液矿泉位于26°N，45°W，距大西洋中脊轴数公里，它是世界卜已发现的最大热液矿泉之一．这个活动的热泉位于一直径为10m的烟囱上，该烟囱位于一直径为150－200m、高40m的椭圆形硫化矿山上．在这个硫化矿山附近几公里范围内还发现了几个不活动的热泉。TAG靠近两条转换断层之间的大西洋中脊．区域重力调查表明，TAG北部的剪切带在向北漂移．分析TAG海底玄武岩表明，源岩在10－15km深处．从旁侧声纳资料看出，TAG由两个复杂的烟囱组成．近海底地球…     

福建漳浦前湖湾有孔虫群落及其沉积环境

对福建漳浦前湖湾潮间带两个钻孔岩心和表层沉积物中的有孔虫进行分析研究,有孔虫出现在钻孔最上部厚约2.46-2.96m的砂层中.根据群落优势种生态和非种特征判断,该段各样品有孔虫沉积环境均为近岸浅水环境,尽管其间海面有过3次上下波动变化.根据地层关系判断,其当为现代的产物.     

俄罗斯沿岸更新世盆地类型

俄罗斯沿岸地区受到分别属于大西洋、北冰洋和太平洋的14个海的海水冲刷，海岸线的总长度超过60000km。在更新世，这些盆地经历过不止一次的幅度不同的海平面的升降作用。在海退时期，广阔的陆架地区变干了，而在海侵时期，沿岸平原和低山岸区被海水淹没。在东北     

Variations of antioxidant efficiency and presence of endosymbiotic diatoms in the Antarctic porifera Haliclona dancoi

The role of endosymbiotic diatoms as pro-oxidant stressors in porifera has been investigated in the Antarctic sponge Haliclona dancoi in which the presence of diatoms is influenced by marked seasonal variations during the austral summer. Both chlorophaeopigments and frustules were absent in sponge tissues sampled in early November at the beginning of the summer and increased from the mid of December with slightly shifted temporal trends. The efficiency of antioxidant defenses in the sponge showed a marked response to symbionts with clearly enhanced values corresponding to the peak of diatoms.     

Cytochrome P450 differences in normal and imposex-affected female whelk Buccinum undatum from the open North Sea

Normal and imposex-affected female Buccinum undatum were sampled from the open North Sea at three locations, one with low, and two with high shipping densities. Cytochrome P450 components and P450 aromatase activity were determined in the microsomal fractions isolated from pooled digestive gland/gonads. Cytochrome P450 aromatase activity was significantly higher (P < 0.05) in normal females collected in the low shipping density area (1,325 +/- 295 fmol/h/mg protein) than levels from imposex animals from a high shipping density area (620 +/- 287 fmol/h/mg protein). A negative correlation was found between aromatase activity and organotin body burden (r = -0.99). Levels of CYP450, cytochrome b5 and NADPH cytochrome c reductase activity did not show differences among groups. This is the first field evidence of depressed aromatase activity in imposex affected females, although additional research under laboratory controlled conditions is required to fully understand the mechanisms underlying the development of imposex in this species.     

通过对重力波曳力的参数化来减小数值天气预报和大气环流模式中的系统性误差

一、引 言 由于地形性激发的中尺度重力波的中断,在加拿大气候中心大气环流谱模式中有时候采用了波的曳力效应的参数化。这一参数化的细节以及它在大气环流模式气候模拟中影响的讨论,可见Boer等人(1985)的工作。 最近,人们利用激发重力波次尺度地形的更好的描绘,来修改这一参数化方案。还有,使用Lindzen(1981)的波饱和概念来描述曳力效应。这一关于地形重力波曳力参数化的作法已在加拿大气候中心的大气环流谱模式中广泛试验,在加拿大气象中心的业务的谱数值预报模式中也正在普遍进行试验。本文的目的所在于概述在这些模式中正在普遍使用的波的曳力方案,并且证明这一方案在消除中期预报和大气环流模拟的系统性误差方面的用处。     

Macrofauna impact on Ulva rigida C. Ag. production and relationship with environmental variables in the lagoon of Venice

The grazing pressure of the macrofaunal invertebrates associated with the biomass of Ulva rigida in the Venice lagoon, their species composition and relationship with environmental variables have been studied. Fifteen sampling campaigns were carried out during different seasons both in the central basin of the lagoon, dominated by macroalgae (especially U. rigida C. Ag.) and in the southern basin, prevalently populated by seagrasses (especially Zostera marina L.). Replicate experiments were conducted in the field by exposing Ulva fronds in net cages of 10 and 1 mm (control) mesh-sizes to allow or prevent grazer entrance. The grazing pressure was determined as Ulva growth rate difference in the cages. In the absence of invertebrate herbivores, Ulva exhibited per cent relative growth rates (%RGRs) ranging from 1.5 to 9.5% day(-1), whereas in their presence the %RGRs were significantly lower (from -2.5 to 3.4% day(-1)) and frequently negative, especially in the station dominated by macroalgae. In this area, peak grazing rates and macrofauna biomasses of up to 8.6% day(-1) and 1,480 g m(-2) fwt (84.4 ash-free dry weight), respectively, were found. On the whole, during in field experiments in the Ulva-dominated station, herbivores removed an amount of biomass whose percentage ranged from 59 to 165% (mean: 103%) of the biomass yield (grazers excluded) found in the cages. These results suggest the possibility that grazers could act as an important factor affecting Ulva production in the Venice lagoon. Macrofauna populations were analysed by means of multivaliate techniques applied to biological variables only and biological and environmental variables together. Data of individual abundance, after a log(x + 1) transformation and the calculation of the Bray-Curtis matrix, were classified using the Cluster Analysis and ordinated by means of the Non-Metric Multidimensional Scaling (MDS) technique, in accordance with the strategies used in the study of multispecies distributions. Finally, biological and environmental variables were analysed together by means of correlation matrices and the Principal Component Analysis.