Tectonic Significance of the Taitung Canyon, Huatung Basin, East of Taiwan

Since the beginning of formation of Proto-Taiwan, the subducting Philippine (PH) Sea plate has moved continuously through time in the N307° direction with respect to Eurasia (EU), tearing the EU plate. The subducting EU plate includes a continental part in the north and an oceanic part in the south. The boundary B between these two domains corresponds to the eastern prolongation of the northeastern South China Sea ocean-continent transition zone. In the Huatung Basin (east of Taiwan), the Taitung Canyon is N065° oriented and is close and parallel to B. Seismic profiles show that the southern flank of the canyon corresponds to a fault with a normal component of a few tens of meters in the sediments and possible dextral shearing. Several crustal earthquakes of magnitude >%6 are located beneath the trend of the Taitung Canyon and focal mechanisms suggest that the motion is right-lateral. Thus, faulting within the sedimentary sequence beneath the Taitung Canyon is a consequence of underlying dextral strike-slip crustal motions. As the continental part of the EU slab located north of B has been recently detached, some subsequent dextral strike-slip motion might be expected within the EU slab, along the ocean-continent transition zone, which is a potential zone of weakness. We suggest that the dextral strike-slip motion along the ocean-continent boundary of the EU slab might trigger the observed dextral strike-slip motion within the overlying PH Sea crust and the associated faulting within the sediments of the Huatung Basin, beneath the Taitung Canyon. An erratum to this article is available at .     

The dynamic behaviour of a river-dominated tidal inlet, River Murray, Australia

Australia's largest river, the River Murray, discharges to the southern ocean through a coastal lagoon and river-dominated tidal inlet. Increased water extractions upstream for irrigation have led to significantly reduced flows at the mouth and, as a result, the area is undergoing rapid change, particularly with regard to the rate at which sediment is being transported into the lagoon. Based on detailed and accurate bathymetric surveys it has been possible to estimate that the rate of lagoon in-filling is of the order of 100,000 m³ per year for the period June 2000 to May 2003, although the actual rate shows significant year to year variability. Dredging of the lagoon commenced in 2000 in an attempt to reverse the trend.In an effort to understand the behaviour of the inlet a one-dimensional numerical model of the inlet has been developed. The model extends the original of van de Kreeke by including a dynamic inlet throat area based on predicted river flows and a sediment transport module to predict the resulting net sediment transport. Comparisons with water level data collected on both the ocean and lagoon sides of the mouth have shown that the model is able to predict the attenuation and lag of the tidal signal reasonably well. The sediment transport model was based on predicted sediment concentrations in the surf zone and was found to predict the rate of sediment in-filling to an acceptable level of accuracy. It is envisaged that the model will be a useful management tool, especially since it is possible to manipulate river discharges to the mouth.     

Comparison of two three-dimensional hydrodynamic modeling systems for coastal tidal motion

A comparison of two three-dimensional numerical modeling systems for tidal elevations and velocities in the coastal waters is presented. The two modeling systems are: (1) the Princeton Ocean Model (POM) and (2) the MIKE 3 flow model. The model performance results for Singapore's coastal waters show that the predicted tidal elevations from the two hydrodynamic modeling systems are almost identical and are in very good agreement with field measurement data. The simulated tidal current velocities match well with field measurement data at the selected stations, but it seems that the POM provides the slightly better simulation, compared to the MIKE 3 flow model. The depth profiles of the velocities obtained from the two modeling systems may be greatly different at some time, due to the vertical diffusion coefficient calculated from different turbulent sub-models in the two modeling systems. The POM generally predicts larger peak tidal velocities. The maximum speed differences for the model results from the two modeling systems occur in the top and differ from time to time and from location to location, reaching up to 20%.     

Spatial Patterns in Nutrient and In Vivo Fluorescence Distributions in the Marginal Ice Zone and the Seasonally Open Oceanic Zone in the Indian Sector of the Antarctic Ocean, in Austral Summer

Surface temperature, salinity, concentrations of silicate (Si) and nitrate + nitrite (N), and in vivo fluorescence (Fluor) were investigated in the marginal ice zone (MIZ) and the seasonally open oceanic zone (SOOZ) (32–40°E, 64–69°S) from February 23 to 28 1992. In the MIZ the mean Si and N were 67.8 ± 2.2 M and 32.5 ± 1.7 M, respectively. There was a trend that low N values coincided with high Fluor values. Observation conducted at one point (64°S, 38°E) revealed a diel variation pattern in Fluor. Applying this pattern of deviation from noon value, all Fluor data were normalized to value at local noon. In the MIZ a significant negative correlation was observed between the normalized Fluor and N but not Si. On the other hand, Si decreased continuously from south to north in the SOOZ and was negatively correlated with the normalized Fluor. Difference in Si concentration was about 30 M between the sea around 64°S and the MIZ, while the difference in N concentration was estimated as less than 10 M. If diatoms take up silicate and nitrogen at an approximate ratio of 1:1, additional nitrogenous nutrients other than nitrate and nitrite (e.g. ammonia, urea etc.) would be required. In this case, an f-ratio of lower than 33% is obtained. It is suggested that in the MIZ abundance of phytoplankton community dominated by non-diatom increases utilizing nitrate while in the SOOZ abundance of phytoplankton community dominated by diatoms increases consuming Si and regenerated nitrogen.     

南麂列岛潮间带环境本底调查

本文系根据１９９２年８月和１９９３年２月（夏、冬两季）对南麂列岛潮间带的环境本底调查以及对水质、底质、生物样监测结果的资料整理而成。调查结果表明，潮间带水质、底质除个别断面外，均处于良好状态。生物体重金属残留量全部低于全国海岸带调查时统一的标准，生态环境条件较好。     

东部沿海滩涂和浅海资源大开发之我见

介绍了浙江东南沿海的台州市及所属玉环县、温州市及所属乐清市、瓯海区等地面实施海洋“蓝色工程”的丰富实践和新鲜经验。文中借鉴浙东南沿海大开发的成功经验,结合我国东部沿海其它地区特别是苏北沿海的实际,提出了做出滩涂开发利用、发展海洋经济的总体战略构想。     

波浪底摩擦力对重砂富集的影响——以鲁南近岸区为例

根据浅水波浪的底摩擦效应，对鲁南灵山湾和臼－岚山镇近岸区进行了波浪的海底摩擦力计算。波浪的海底摩擦力等值图与已知滨海锆石砂矿资料对比表明，底摩擦力大于０．１８Ｎ／ｍ＾２的动力分选区有利于重矿物砂富集。据此，进一步预测了鲁南近岸带的砂矿富集区。     

南麂列岛海洋自然保护区潮间带贝类资源时空分布

为了解南麂列岛海洋自然保护区潮间带贝类十多年来的动态变化,在1992年研究基础上,于2003年度再赴南麂列岛对岩、沙相贝类进行了研究.本次调查鉴定出贝类105种,其中岩相93种、沙相12种,6种为南麂列岛新记录种,对岩相、沙相贝类组合的生态特征进行了分析,岩相多样性和均匀度指数(1.25~2.20和0.54~0.70)高于沙相的(0.23~0.95和0.17~0.94).岩相贝类数量为3025.70g/m2和2660个/m2,生物量垂直分布为低潮区最高(6471.99g/m2),中潮区居中(3772.09g/m2),高潮区最小(78.35g/m2),栖息密度为中潮区最大(4245个/m2),低潮区居中(2973个/m2),高潮区最小(439个/m2).沙相贝类数量为16.81g/m2和11个/m2,低潮区(29.43g/m2和11个/m2)大于中潮区(14.01g/m2和10个/m2).通过与以往资料比对发现,岩礁贝类数量有所增加,沙滩贝类数量则明显下降,监控区贝类数量明显多于其他区域,对贝类资源变化产生影响的相关因子作了分析探讨.     

软土海岸地区测量控制点标志的设立

分析了软土、湿地、滩涂地区特殊地理环境对测量控制点的影响;主要探讨了此类地区控制点标志的设计、施工。借助于建筑桩基技术和道桥施工方法,首次成功实现了某三角洲湿地滩涂地区统一布网。几年来,结合滩涂湿地测量、海岸防护和滩涂开发工程对部分控制点进行了初步检测,给出了部分检测数据。应用和检测均表明:桩基标石可较好地解决软土、湿地、滩涂地区控制点布设难题,显著提高软土海岸地区测量控制点标志的稳固性,从而延长控制网的可使用期。