The importance of bioturbation to continental slope sediment structure and benthic processes off Cape Hatteras, North Carolina

Even though the continental slope off Cape Hatteras has sediment accumulation rates on the order of 1 cm/year, large areas of soft sediment are intensively reworked by infaunal organisms. Primary sedimentary structures have been completely replaced with biogenic structures. Surface sedimentary structures are dominated by the bioturbational activities of a deep burrowing infauna (to at least 30 cm). The layer actively mixed by the benthos, as evidenced by sediment profile and X-ray images, is estimated to range from 5 to 20 cm, with the residence time for particles within the surface mixed layer ranging from about 4.5 to 18 years. The biological mixing parameter (G) ranges from 0.4 to 5.5, which indicates moderate to strong biological mixing relative to accumulation and strata formation. Bioturbation contributes to the dynamic forces affecting the surface sediments by decreasing compaction of sediment layers and dilating sediment fabrics by sediment mixing, and introducing large water-filled burrows and voids to subsurface sediments. The sediment profile images captured numerous subsurface feeding voids, and worms in the process of making deep burrows, many of which extended below the 5 to 10 cm average depth of the apparent color redoxpotential discontinuity layer. High rates of accumulation of organic-rich sediment lead to high standing stocks of benthos and intensive feeding/burrowing activity that result in organic rich stratagraphic sequences that are thoroughly mixed. Cape Hatteras is a apparent focusing point for the transport of shallow water sediments to the deep sea. Sediments across other areas of the continental slope just 100's of kilometers south of Cape Hatteras are not as thoroughly mixed or biologically active.     

Building capacity for integrated coastal management in developing countries

The need for building human and institutional capacity has been identified in Agenda 21 of the UNCED conference as well as by a number of international environmental institutions as essential for integrated coastal management (ICM) and sustainable development in developing coastal states. There is a growing need for coastal management practitioners and organizations with expertise in planning and implementation for ICM. The application of strategies for institutional development and building human capacity in coastal management and other fields shows that short-term intensive training efforts and long-term institutional strengthening programs are appropriate to address the issues and needs of ICM. An overview of the experience of the URI/USAID International Coastal Resources Management Program in Sri Lanka, Thailand and Ecuador presents lessons learned for strengthening ICM efforts in developing countries.     

An analysis of 3.5 kHz acoustic reflections and sediment physical properties

Near-bottom normal incidence acoustic reflection data and sediment physical property data are used to study the relationships between acoustic reflections and sediment physical properties. A pinger-hydrophone experiment was performed to obtain the necessary acoustic reflection data. In addition, a standard piston core was retrieved in the acoustic survey area for physical property analysis. The piston core was sampled and 13 properties were measured at 55 locations within the top 12 m of the core. Correlation studies amongst the sediment physical properties resulted in the following strong correlations: acoustic impedance ($\text{Z}$) and porosity ($\text{N}$), (0.96); water content ($\text{WC}$) and $\text{Z}$, (0.95); bulk density ($\text{BD}$) and $\text{Z}$, (0.99).The empirical orthonormal function (EOF) method was employed for acoustic signal analysis. This method assumes no a-priori models of the sediment or causality. The EOF method reduced the acoustic data to 8 functions that contained 97.6% of the sample variance. The EOFs were subsequently analysed by using cepstrum analysis which reveals time delay information and enhances detecting zones of reflectivity. The result of the sediment physical property and cepstrum analysis indicates that zones of reflectivity are essentially zones of relatively high acoustic impedance, low porosity, and low phi (high mean grain size).     

辽东湾海底残留地貌和残留沉积

全新世以来,世界海面大幅度上升,渤海海区发生了明显的海侵,玉木冰期低海面时期的近海广大陆域皆沉溺于海平面以下。辽东湾由于地质构造复杂及沉积作用速度分布不均匀等因素,海底保存了一部分玉木冰期低海面时期陆地或滨海区的地貌形态及相应的老沉积物的遗迹。它们虽然经过了后期水动力条件及沉积作用的改造,但是,仍不同程度地反映出原始地貌的迹象和某种残留沉积的特征。 关于辽东湾残留地貌和残留沉积的问题,过去曾有报道;本文在以往调査的基础上,结合近期有关资料,对此作进一步的探讨。     

Study of the fauna inhabiting the holdfasts of Laminaria hyperborea (gunn.) fosl. along some environmental and geographical gradients

A survey of the holdfast fauna of Laminaria hyperborea was carried out at thirty-five sites around the UK, mostly along the North Sea and south coasts.Data from different age classes of holdfast from a polluted and unpolluted site indicate that volume of holdfast space is a most important measurement of sample size, a minimum size of sample being one litre and, preferably, three.Gradients of increased heavy metals were defined down the North Sea and west coasts and, by utilising measurements of kelp penetration, water clarity gradients were determined as increasing northwards on the west coast and both north and southwards on the North Sea coast from a point near Tyne and Wear county. Analysis of holdfast fauna showed numerous gradients of total numbers, species and diversity which correlate closely with the heavy metal and water clarity gradients, or with undetermined parameters analogous to latitude and longitude. Where there were increases of heavy metals or decreases of water clarity, various reciprocal relationships between suspension feeders and all other trophic groups were commonly observed. In the North Sea numbers of suspension feeders increased while numbers of all other trophic groups declined. On the west coast a heavy metal increase correlated with a decreasing species richness of all trophic categories except suspension feeders, while with total numbers only suspension feeders showed an increase. On the south coast transect neither gradient existed, and only here did all trophic categories covary, except at one very polluted site where the same reciprocal relationship was again indicated.In terms of species similarity the North Sea showed a greater pool of common species than occurred between sites of other regions and between North Sea sites with other regions, despite the widest range of heavy metal levels and wate clarity that existed there. Between-site similarity appeared to be much more dependent on geographical proximity than on the two measured environmental factors. It is suggested that effects of clarity-reduction can be measured by trophic analysis more successfully than by species presence or absence, and that changes of holdfast fauna along the North Sea coast are due largely to pollution.     

Concentrations of suspended matter and particulate cadmium,copper, lead and zinc in the Indian sector of the antarctic ocean

The concentrations of suspended matter and particulate Cd, Cu, Pb and Zn were determined for 36 samples collected at 6 stations in the Antarctic Ocean during December, 1970 and January, 1971 using membrane filters. The concentration of suspended matter was determined gravimetrically and trace metal levels were determined using anodic stripping voltammetry. For waters deeper than 100 m the concentration of suspended matter was < 100 μg l^?1. Concentrations up to 542 μg l^?1 were recorded between surface and 100 m. Individual concentrations of the metals were scattered with depth. Average concentrations of particulate metals were: Cd, 3.5 ng l^?1; Cu, 100 ng l^?1; Pb, 35 ng l^?1; and Zn, 230 ng ;l^?1 These measurements represent non-steady state conditions of early Antarctic summer as the ice pack disintegrates and biological activity increases.     

鱼类生长激素的体内代谢、分泌调控和作用机制研究的进展

主要对１９８３－１９９６年间关于鱼类生长激素的体内代谢、分泌调控和作用机制的研究进展予以综合评述。通过鱼类划性放射免疫测定法的建立和体风代谢动力学研究，证实，外源生长激素在鱼体内不会产生积累。鱼类生长激素的分泌调控受下丘脑分泌的生长激素释放因子（ＧＨＲＦ）和释放抑制因子（ＳＲＩＦ）的双重；促性腺激素释放激素（ＧｎＲＨ）、雌二醇（Ｅ２）、促甲状腺素释放激素（ＴＲＨ）和神经肽（ＮＹＰ）对鱼类生长激素的     

艾比湖地区冰消期以来气候演化的植物学证据

本文根据植物生态学分析方法，通过对艾比湖ＺＫｏｏＢ孔中孢粉组合及植被生态的定量分析，阐述了北疆内陆干旱区冰消期以来的气候演化状况。孢粉组合特征及其植被生态的定量分析研究表明，受大气降水以及大气和土壤中相对湿度波动变化的影响，艾比湖地区的生态环境特征在最近１５０００ａ中至少经历了１０次比较明显的波动变化，并且与全球气候变化过程基本符合，表明中国西部干旱半干旱地区晚更新世以的气候环境演化过程是在全球变     

Cyclone and bioturbation effects on sediments from coral reef lagoons

Despite the severity of tropical cyclone ‘Winifred’, which crossed the Great Barrier Reef on 1 February 1986, there were little long-term effects on lagoon surface sediments from reefs in its path. Short-term effects were apparent only at one particularly exposed area. These were: an increase in proportion of the coarse fraction, the establishment of sand ripples, and the destruction of the mounds produced by callianassid shrimps (normally the dominant topographic feature). Within six weeks this area was indistinguishable from a typical reef lagoon. This is probably the result of sediment reworking by callianassid shrimp, involving selective burial of the coarse fragments and transport to the surface of finer particles. Sediment turnover rates by callianassids are commensurate with change to the sediment within the relatively short period observed. The sediment fauna responded quickly to the changes in sediment type. Immediately after the cyclone the disturbed area supported a fauna typical of the coarse sediments on the shallow reef flat, as the sediment reverted to a more normal type so the fauna changed back to that typical of a reef lagoon.     

预报指标自动归纳和实时自动推理预报系统

本文结合实际应用介绍一种人工智能系统。系统的重要特点是,根据预报指标经验知识的产生过程的机理性知识所设计成功的系统主程序之一的“预报指标自动归纳程序”,能够通过对多因子历史资料的分析归纳,自动生成含有较全面知识规则的规则库。有关专家只须凭感性经验提供可能因子和原始资料,系统便能帮助升华出理性的经验规则,自动建成某一专项业务的应用预报系统。对这种“母系统”的反复使用,就可以根据不同类别的资料生成相应的多种应用系统。既适用于气象上风雨暑寒各类天气预报,也适用于其他某些专业,如水文、地震等的定性预报或分析。 本文除简单介绍系统的构造、功能、设计原理之外,还给出一个应用实例,介绍了如何使用本系统去产生应用性系统的具体方法步骤。