Responses of pink shrimp Farfantepenaeus brasiliensis (Latreille, 1817) (Penaeoidea) to physico-chemical parameters in a marine protected area: changes in abundance and distribution after 20 years

ABSTRACT

This study analysed the influence of temperature, salinity and sediment texture on the distribution of pink shrimp juveniles (Farfantepenaeus brasiliensis) over a 20-year period. The shrimps were sampled monthly in Fortaleza Bay, north coast of São Paulo, Brazil, in November 1988–October 1989 (period 1) and then 20 years later in November 2008–October 2009 (period 2). In period 1 we captured 80 juveniles whereas in period 2 we captured 226. The abundance and distribution of F. brasiliensis seemed to be modulated by temperature and sediment texture, along with the fishing activity. The management strategies established between the samplings might have been responsible for the higher abundance of juveniles seen during period 2. The strategies included the limitation of fishing effort, regulation of fishing equipment and the establishment of environmental protection areas and temporary fishing ban.     

小清河底泥沉积物的形态分析(Ⅰ)——主成分及次要成分分析方法研究

采用透射电镜 ,红外光谱 ,X ray粉末衍射光谱 ,原子吸收光谱等现代技术对小清河底泥沉积物复杂化合物的形貌及其中无机化合物的物种进行了综合分析 ,结合相应样区的水质分析进一步确认了底泥沉积物中主、次成份的物种以及痕量重金属污染物的分子存在状态 .     

A theoretical framework of tracer methods for marine sediment dynamics

A new theoretical framework of tracer methods is proposed in the present contribution, on the basis of mass conservation. This modet is applicable for both artificial and natural tracers. It can be used to calculate the spatial distribution patterns of sediment transport rate, thus providing independent information and verification for the results derived from empirical formulae. For the procedures of the calculation, first, the tracer concentration and topographic maps of two times are obtained. Then, the spatial and temporal changes in the concentration and seabed etevation are calculated, and the boundary conditions required are determined by fietd observations (such as flow and bedform migration measurements). Finally, based upon eqs. (1) and (13), the transport rate is calculated and expressed as a function of the position over the study area. Further, appropriate modifications to the modet may allow the tracer to have different densities and grain size distributions from the bulk sediment.     

Climatic variations recorded by the sediments from Erhai Lake, Yunnan Province, southwest China during the past 8000 a

Erhai Lake is a large lake with important climatic significance in Yunnan Province, southwest China. The multi-proxy sedimentary records from Erhai Lake indicate the 9 stages of climatic changes with the alternation of warm-dry and cool-wet during the past 8000 a. The variations of Asian monsoon systems were the main cause for the climatic changes in southwest China. The warm-dry period was coincident with the intensification of India monsoon and Northwest Pacific Sub-tropical High Pressure, and the cool-wet corresponding to weak of India monsoon and its main rain belt moving back to southwest China.     

大中型水泵空蚀与泥沙磨损预防及修复技术

比较了焊补修复、非金属材料涂敷、不锈钢板镶嵌、合金粉末喷焊等几种修复大中型水泵空蚀侵蚀方法的优缺点，重点介绍了氧乙炔合金粉末喷焊的特点及应用中应注意的问题。     

Elemental composition in the sediments of the Yangtze and the Yellow Rivers and their tracing implication

Elemental compositions in the surface sediments of the Yangtze River and the Yellow River are quite different. The Yangtze River' s sediment is rich in K, Fe, Mg, Al and most of trace elements, and its elemental composition show remarkable spatial variations, whereas the Yellow River s sediment has higher contents of Ca, Na, Sr, Ba, Zr and Hf, and the elemental composition remains relatively stable. The ratios of some elements are also different in the sediments of the two rivers. The elemental composition of the Yangtze River sediment results from widely distributed igneous rocks and complicated source rocks and strong chemical weathering in the Yangtze River catchment basin, while the main provenance of the Yellow River sediment is the Loess Plateau which has dominant influence on the elemental composition, and the intense physical weathering is another controlling factor. The elements such as Cu, Zn, Sc, Ti, Fe, V, Ni, Cr, Co, Li and element ratios such as La/Sc, La/Co, Th/Co, Ti/Zr and Zr/Y can be used as the tracers to distinguish the Yangtze River sediment from the Yellow River s. The tracers can be used in the study of the mixing and distribution of the substances of the two rivers matters in coastal zones of China.     

一种基于混沌粒子群的泥沙颗粒图像优化算法

针对泥沙颗粒图像与其它领域的颗粒图像的类同性,利用图像处理技术计算泥沙颗粒,提出了一种基于混沌粒子群的泥沙颗粒图像优化算法。该算法在运行的初期为了避免收敛早熟,增强了群体的多样性;通过设定的特定格式迭代产生混沌序列,有效的避免多样性的下降和早熟收敛的产生。在运行的中后期,能够在全局的最优区域进行更加精细的搜索,找到全局最优解的速度更快。实验结果表明,算法较好地解决了河流复杂泥沙颗粒图像的优化问题。     

一种复杂曲流带储层三维构型建模新方法

基于河道迁移演化模拟、侧积层定量三维分布模式及沉积过程模拟提出一种复杂曲流带储层三维构型建模新方法,并根据井数据构建渤海湾盆地A油田明化镇组下段曲流河相储层三维构型机制模型。结果表明:该方法能够在三维空间模拟复杂曲流带储层内部构型元素的大小、三维形态及其空间结构关系,实现对储层连通性、连续性及非均质性的定量表征,是一种快速有效的复杂曲流带储层构型建模新方法。     

平原河流水沙动力学若干研究进展与工程治理实践

综述了河海大学在平原河流水沙动力学问题及河道整治技术创新与实践方面的研究成果,包括含植物水流、沙波床面水沙运动、潜流交换、河网交汇流、桥墩防冲、闸下防淤等基础理论、复杂河网水沙运动模拟与多目标水力调控技术,以及上述理论方法在解决长江、淮河、珠江等流域多个大中型复杂河网防洪、排涝、水运、环境等诸多实际问题中的应用,展望了我国平原河流治理今后需重点关注的问题。     

大丰港匡围工程对潮流泥沙影响的模拟研究

建立了大丰港临近海域平面二维潮流泥沙数值模型,模拟计算了研究区域大小潮特征时刻的水沙空间分布特征。模型利用实测数据进行验证,计算结果与实测潮位、流速、流向及含沙量数据吻合良好。在模型验证良好的基础上,模拟围垦工程建设前后周围流场和悬沙场的变化。研究发现:围垦工程使得工程向海一侧流速减小。对于悬沙浓度,涨急时刻工程北部含沙量减小,落急时刻工程向海测含沙量增大。