Formation of chemogenic calcite in super-anoxic seawater — Framvaren, southern Norway

Framvaren, a super-anoxic fjord in southern Norway, contains 7–8 mmoll⁻¹ of sulphide and a total carbonate concentration of 18.5 mmol kg⁻¹ in the bottom water. The chemistry of calcium has been studied, considering sources, biogenic and chemical processes and sedimentary sinks. Calcium associated with the bacteria biomass at the redox interface (18m depth) appears to be the primary source of dissolved calcium in the deep, anoxic water. Excess calcium and high total carbonate cause supersaturation of calcite, which is precipitated chemogenically. Calcite (and presumably some aragonite) is identified both in sediment trap material and the bottom sediments below the depth of supersaturation.     

Nocdap results: On the relationship of extreme waves and currents for design of offshore structures

Simultaneous wind, wave, and current data during 21 storms spanning four winters at Tromsøflaket (230 m depth) were analysed to determine joint probabilities of occurrence. Waves were measured with a Waverider Buoy, winds with a recording anemometer onboard a vessel and currents at up to five depths with Aandera RCM-4 current meters. Measured currents were filtered to separate tidal currents from residual currents. In most of the statistical analyses, the actual current profiles were replaced with a simplified “equivalent” profile (constant above 50 m depth) whose magnitude was chosen to give the same drag load on a single pile as the actual profile when both profiles were combined with wave orbital velocities. The data suggest that the equivalent current is weakly correlated with the wave height. Within the range of the data analysed, an in-line equivalent residual current of 30 cm sec⁻¹ is adequate for design drag force calculations.The data presented here are used to illustrate a procedure for data analysis and are not suitable for use as design criteria.     

Paleomagnetic events in the brunhes and Matuyama epochs identified from magnetic profiles reduced to the pole

Eleven oceanic magnetic profiles associated with the paleomagnetic time scale younger than the beginning of the Matuyama epoch (2.43 my) have been reduced to the pole, altered to conform to a 3 cm yr^-1 spreading rate, and then all halves added and averaged to obtain a representative symmetric magnetic profile. This final stacked profile emphasizes the subtle anomalies associated with minor paleomagnetic events and minimizes randomly occurring anomalies. The axial anomaly of the stacked profile shows no evidence of the Laschamp event (centered at 0.025 my); however, a minimum at 0.15 my may correspond to the Blake event. A physical model of the stacked magnetic profile consists of a thin, highly magnetized layer with a 40% magnetization decrease at 10 km from the profile center. Magnetization values were modified from Irving and Talwani and the Blake event included. The stacked profile shows two minor anomalies centered at 1.97 my and 2.17 my. The younger anomaly corresponds with the younger Olduvai event (centered at 1.965 my) on the Cox time scale and the W anomaly (centered at 1.99 my) of Emilia and Heinrichs. The older anomaly lies between the older Olduvai event (2.12 my) of Cox and the X anomaly of Heirtzler, and Emilia and Heinrichs; additional work is required to assess the significance of this older event.This material was presented at the Fall Annual Meeting of the American Geophysical Union, December 8, 1971.     

长江口泥沙絮凝静水沉降动力学模式的试验研究

细颗粒泥沙在咸水中的絮凝沉降是河流泥沙向海输送过程中在河口区发生的重要现象，是河口拦门沙形成与发育的主要原因之一。本文根据室内模拟试验研究，提出长江口泥沙絮凝静水沉降的二级动力学模式，通过该式求得不同泥沙含量和盐度情况下絮凝沉降的衰减系数，半衰期和平均沉降速率等动力学参数，定量地分析泥沙含量和盐度对泥沙絮凝沉降过程的影响。     

合浦珠母贝铁的穆斯堡尔谱学研究

应用^57Fe穆斯堡尔谱学的方法研究了四个不同生长期合浦珠母贝铁的化学状态和Fe^2 /Fe^3 的值，它们的Fe^2 和Fe^3 的相对含量分别为4.1%～29.4%和76.6%～95.9%,Fe^2 /Fe^3 值的变化为0.043～0.42。3个月龄的Fe^2 /Fe^3 值大于10个月龄，从10个月龄到22个月龄的Fe^2 /Fe^3 值呈增加的趋势，这可能反映了不同生长期合浦珠母贝对不同价态的铁的需求。     

浙江主要气象灾害概述

气象灾害每年都有,只是轻重程度不同。就全国和全省范围来说,很少有真正风调雨顺的年份。本文根据1951～1988年38年的气象历史资料及有关政府部门的材料、简报、报道,统计出台风、洪涝、海上大风和强对流等几种主要气象灾害对浙江经济造成损失和伤亡人数。文中对主要气象灾害的特点、一般规律和灾情作了概述,并列出一些典型实例,提出了预防气象灾害的意见。     

CHIMEHERB人工皮使用的体会

从1989年4月～1990年10月,我科在69例病人中使用CHIMEHERB人工皮,覆盖治疗了供皮区,Ⅱ°烧伤创面、脱痂创面的残余肉芽创面.临床应用表明:CHIMEHERB人工皮能加快创面的愈合,是目前较好的一种创面覆盖物,用人工皮覆盖创面2～3天后,人工皮干燥,不需再换药,可减轻病人的痛苦.     

Improved form of wind wave frequency spectrum

The lower frequency part of the theoretical wind wave spectrum proposed by the authors (Wen et al. , 1988a, b,c) has been improved and the form of spectrum is appreciably simplified. In addition to the field data collected in the Bohai Sea region and used in the previous papers, those obtained in the Huanghai Sea, the East China Sea and the South China Sea have been employed so that the improved spectra can be verified on a more extensive observational basis. Computed results agree with the observations well. Further comparisons have been made between the proposed spectra and the JONSWAP spectrum. Though the two types of spectrum are close to each other in form, the former shows, as a whole, better agreement with the observation than the latter. By introducing an improved relation between the peak-ness factor and significant wave steepness, the spectrum contains only significant wave height and period as parameters. For spectra given in this form, the computed peak frequencies coincide approximately wit     

Baroclinic Buoyancy-Inertia Joint Stability Parameter

At present, the barotropic buoyant stability parameter has been derived from a vertical virtual displacement of a water parcel. The barotropic inertial stability parameter in the eccentrically cyclogeostrophic, basic current field was derived in 2003 from a horizontal cross-stream virtual displacement of a parcel. By expressing acceleration of a parcel due to a virtual displacement, which is arbitrarily sloping within a vertical section across the basic current, in terms of natural coordinates, we derived the vertical component of baroclinic buoyant stability parameter B ₂ ², the horizontal component of baroclinic inertial stability parameter I ₂ ², the baroclinic joint stability parameter J ², its buoyant component B ² and its inertial component I ². B ² is far greater than I ₂ ², and when neglecting relative vorticity except for vertical shear, a downward convex curve of J ² plotted against the slope of a virtual displacement follows a trend of B ² curve. If a parcel displaces along a horizontal surface or an isopycnal surface, however, B ² vanishes, and J ² becomes equal to I ². Actual parcel is apt to displace not only along the bottom slope, but also along the sea surface and an isopycnal interfacial surface, which is approximately equivalent to an isentropic surface, preferred by lateral mixing and exchange of momentum. Such actual displacement makes B ² vanishing, and grants I ² an important role. The present analysis of I ² examining effects due to curvature and horizontal and vertical shear vorticities are useful in deepening our understanding of baroclinic instability in actual oceanic streams.