Assessing DNA damage in cnidarians using the Comet assay

The assessment of DNA damage by the Comet assay has been described as a useful non-specific general biomarker of stress in many marine organisms. In field situations it has successfully been employed to distinguish between reference and polluted sites and in the laboratory it has been widely used as a mechanistic tool to determine pollutant effects and mechanisms of DNA damage. To date a wide range of marine vertebrates and invertebrates have been used, however, the usefulness of this assay as a biomarker in cnidarians has not yet been assessed. The aims of this study were to optimize the Comet assay for cnidarian cells and to assess its utility for detecting genotoxic damage in these cells. Cells were isolated from the North American pacific coast temperate sea anemone Anthopleura elegantissima using a non-enzymatic dissociation procedure and viability was determined to be in excess of 90%. Cells were incubated either with (1 h acute exposures) hydrogen peroxide (H(2)O(2)), ethylmethanesulphonate (EMS) or benzo(a)pyrene (B[a]P). In comparison to other marine species, anemone cells exhibited high control or background levels of DNA strand breaks. Despite this, however, we observed dose responses for each of the study chemicals with no reduction in cell viability. This study demonstrates that anemone cells respond to known DNA damaging agents, including B[a]P which requires metabolism to exert its genotoxic effect, and that the Comet assay may prove to be a useful biomarker of stress in cnidarian species.     

A wave model for the Great Barrier Reef

A new wind wave generation model, WAMGBR, is presented that has been adapted from WAM especially for use in the complex geometry of the Great Barrier Reef. A technique (reef parameterization) has been presented that incorporates sub-grid scale dissipation caused by coral reefs. Three other improvements to WAM have been proposed. An explicit/implicit finite difference scheme has been implemented that allows for more efficient modelling (longer time steps) while maintaining diffusive characteristics that are at least as good as those of WAM. An offset in discrete angles creates more uniform diffusive characteristics. And, a transformed spherical coordinate system allows for more efficient grid sizes and smaller grid dependent refraction. Comparisons between modelling techniques and between model and measured data show that WAMGBR produces very good results in the difficult challenge of modelling both non-cyclonic and tropical cyclone waves in the geographically complex environment of the Great Barrier Reef.     

河口涨潮槽的研究进展

河口涨潮槽是河口的重要地貌单元。对河口涨潮槽的发育过程与演化规律的研究在理论上可以丰富河口动力地貌的内容，而在实践上对港口和通航等具有重要的意义。文章认为河口涨潮槽不仅指河口涨潮流作用下形成的冲刷槽，还包括涨潮冲刷坑、涨潮冲刷槽和涨湖水道。国内外关于河口涨潮槽研究较为薄弱，研究内容多集中于涨潮槽的几何形态、涨落槽优势流判别和悬沙输移等方面，定性研究较多，缺乏全面而系统的定量研究，尤其缺乏成因机制方面的深入研究和沉积环境的研究。长江口涨潮槽种类较多，具有一定的研究基础，对其进行系统全面的研究具有重要的意义。     

古代的火山爆发导致了地球冻结吗?

在大约74ka前的一个晴朗的日子里,苏门管腊岛上一座巨大的火山爆发了.     

A note on flow structure in the Great Ouse estuary

Field measurements of vertical profiles of velocity and salinity along with turbulence measurements have been used to examine the effect of density gradients on the flow structure in the Great Ouse estuary. During the flood tide shear and longitudinal density gradients cause well mixed conditions in the lower part of the water column. In the upper part of the water column secondary flow effects induced by transverse density gradients, and acceleration effects can contribute to the formation of stable vertical density gradients. On the ebb tide the vertical density gradient appears to be the dominant factor which determines the structure of the flow. The velocity and shear stress data show the evidence of large scale motions which are consistent with the postulated flood and ebb flow structures.     

A sandwave field in the Outer Thames Estuary,Great Britain

A method of presentation, in which seabed profiles are scale-corrected and replotted in three-dimensional form, has been developed to aid the study of complex areas of the seabed. For sandwave research the continuity of crests can be studied, and the positional relationship of individual features compared. By plotting successive surveys of the same area, changes can be detected and significant movement measured.In the sandwave field at Long Sand Head, Thames Estuary, the sandwaves can be grouped in morphological zones, depending upon their amplitude, wavelength and cross-sectional asymmetry. Despite marked asymmetry, which suggests opposing directions of movement in different zones, little progressive movement occurs, but rather a “flexing” of sinuous crest lines results in displacement of up to 25 m in a year.The study has been supported by side-scan sonar surveys, which emphasize the complexity of the sandwaves within the field and the presence of less stable dune bed forms (American Society of Civil Engineers, 1966), which often lie at considerable angles to the major crests, suggesting a secondary flow regime.     

黄河三角洲洪、枯季泥沙冲淤的数值模拟

本文针对黄河三角洲海岸潮间带广阔、黄河入海水沙变化剧烈、近岸及河口区水动力条件复杂的特点 ,建立了 1个潮流作用下的平面二维动边界全沙数学模型。动边界的处理采用窄缝法 ,并利用此模型对黄河三角洲洪、枯季时悬沙分布以及底床的冲淤进行了数值模拟 ,进而据此探讨了黄河三角洲洪、枯季的冲淤变化规律。     

Did the East Pacific rise subduct beneath the North America plate (western Mexico)?

New data collected between the northernmost tip of the East Pacific rise (18°05'N, 105°35'W) and the Middle America trench provide evidence that the seafloor, which lacks significant sedimentary cover, has a typical spreading-derived abyssal hill topography. The tectonic fabric of this seafloor is concave to the west, as it is today at the tip of the East Pacific rise. Farther to the east, at the outer wall of the trench, the seafloor topography exhibits a north-south trending fabric. We suggest that this fabric originated along the East Pacific rise, as it reached the trench and possibly subducted beneath the North America plate prior to the development of the complex connection of the East Pacific rise with the Rivera transform.     

海域使用管理法制化建设的大跨越——海域使用管理立法工作断想

金秋十月，是收获的季节。十月的北京，引人注目的不只是香山红叶。今年的十月，在北京庄严的人民大会堂，第九届全国人大常委会第二十四次会议通过了《中华人民共和国海域使用管理法》（以下简称《海域法》），中华人民共和国主席江泽民签署第６１号令发布施行。这一天是２００１年１０月２７日。对于全国海洋战线广大干部职工来说，这是一个令人欢欣鼓舞的日子，是一个永远不会忘记的日子。多年来多少人为之呼吁、翘首期盼的《海域法》，终于发布施行，这是我国依法治海的一个重大举措，是海域使用依法管理的一个重要里程碑，是海域使用管…