An interfacial Gerstner-type trapped wave

Coastally trapped rotational interfacial waves are studied theoretically by using a Lagrangian formulation of fluid motion in a rotating ocean. The waves propagate along the interface between two immiscible inviscid incompressible fluid layers of finite depths and different densities, and are trapped at a straight wall due to the Coriolis force. For layers of finite depth, solutions are sought as series expansions after a small parameter. Comparison is made with the irrotational interfacial Kelvin wave. Both types of waves are identical to first order, having zero vorticity. The second order solution yields a relation between the vorticity and the velocity shear in the wave motion. Requiring that the mean motion in both layers is irrotational, then follows the well-known Stokes drift for interfacial Kelvin waves. On the other hand, if the mean forward drift is identically zero, we obtain the second order vorticity in the Gerstner-type wave. The solutions in both layers for the Gerstner-type interfacial wave are given analytically to second order. It is shown that small density differences and thin upper layers both act to yield a shape of the material interfacial with broader crests and sharper troughs. These effects also tend to make the particle trajectories at the interface in both layers become distorted ellipses which are flatter on the upper side. It is concluded that the effect of air excludes the possibility of observing the exact Gerstner wave in deep water.     

Gas chromatographic–mass spectrometric analysis of polychlorostyrene congener mixtures in sediments,human sera and cord sera

Complex mixtures of polychlorostyrenes are produced and released into the environment by reaction of chlorine with graphite at high temperatures, e.g. in electrodes. The occurrence of these compounds in the environment or human tissues is often indicative of pollution from electrolytic processes. Combined gas chromatography coupled to electron impact and negative ion chemical ionization mass spectrometry is described here for the analysis of these compounds in sediments, human venous sera and cord sera. This method has allowed a specific congener identification and quantification of the chlorostyrene mixtures present in fluvial sediments polluted by effluents from a chlorine-alkali plant. Besides octachlorostyrene, the mixture of compounds identified involved the six possible heptachlorostyrenes, fifteen hexachlorostyrenes and seven pentachlorostyrenes, having concentrations in the range of 76–16 000 ng g⁻¹ dry weight. In human sera from the population exposed to airborne emissions from this plant these compounds ranged between 17 and 63 ng L⁻¹ and the distributions were dominated by octachlorostyrene, three heptachlorostyrenes, including β,β-2,3,4,5,6-heptachlorostyrene, and α-2,3,4,5,6-hexachlorostyrene. Both distribution patterns showed major differences in composition despite the common pollution source that was influencing both types of samples. The method also revealed qualitative differences between maternal and cord sera from the exposed population.     

近代海相沉积型海域大桥施工关键技术研究

近代海相沉积型海域是我国沿海典型地质条件, 由于其构造独特和力学特性复杂, 在建造大桥时必须采取针对性的措施. 因此从跨海大桥施工的测控技术、桥墩桩基和栈桥寿命维护等方面出发, 探讨沉积型海域跨海大桥施工的关键技术, 并在平潭海峡大桥施工中得到了实际应用.     

养殖水域悬浮沉积物对几种酚类环境激素污染物的吸附行为

采用高效液相色谱法研究了宁波市象山港某养殖场悬浮沉积物对壬基酚、辛基酚及双酚A 3种酚类环境激素的吸附行为. 结果表明: 壬基酚、辛基酚及双酚A在悬浮沉积物上的吸附是一个复合动力学过程, 吸附量具有波动特征; 吸附等温线可用Henry线性分配模型及Freundlich模型进行数学描述; 沉积物对3种酚类环境激素的平衡吸附量大小为壬基酚>辛基酚>双酚A; 有机质含量影响壬基酚、辛基酚及双酚A在沉积物中的吸附行为, 3种沉积物的平衡吸附量大小表现为加腐殖酸沉积物>沉积物原样>去除有机质的沉积物; 酚类环境激素在沉积物中的浓度积累增大了养殖水域底栖生物的接触风险.     

海岸带侵蚀灾害研究进展及思考

在当今全球海平面上升的背景下,海岸侵蚀灾害已严重威胁着海岸带生存和生活环境,逐渐成为各相关领域的一个热点研究课题。因此,在总结中国典型海岸段侵蚀灾害的基础上,深刻探讨国内外海岸带侵蚀研究现状,并就此提出存在的两个关键性问题。最后,指出今后应重点加强以下5个方面的研究: (1)海岸侵蚀与地质环境条件的相关关系; (2)海岸侵蚀分区特征与发育分布规律; (3)侵蚀海岸的变形破坏模式; (4)岩土体在各种侵蚀因子作用下力学特性变化; (5)海岸稳定性的评价机制。     

大亚湾表层沉积物中生源要素的季节分布及污染评价

2006年7月至2007年11月采集了大亚湾10个采样点春、夏、秋和冬4季表层沉积物样品,分析了沉积物中的生物硅(BSi)、有机碳(TOC)、总氮(TN)和总磷(TP)含量。结果表明:大亚湾生源要素含量与国内外港湾相比属于中等水平;春季BSi、TP的平均含量分别为1.09%、0.043%;夏季BSi、TOC、TN、TP的平均含量分别为1.21%、1.05%、0.37%、0.043%;秋季BSi、TP的平均含量分别为0.99%、0.038%;冬季BSi、TOC、TN、TP的平均含量分别为1.09%、0.84%、0.11%、0.039%。根据TN/TP和TOC/TN比值判断,大亚湾沉积物为磷限制;夏季TOC主要来源于水生有机碳,冬季为混合来源。夏季表层沉积物中BSi、TOC、TN和TP的平均含量均高于其他季节;其中夏季各站位TN的含量较冬季要高,反映了夏季较高的硅藻生产力以及较丰富的地表径流。大亚湾大部分采样点TOC和TN的污染基本属于Ⅱ类,TP属于Ⅰ类,可能对底栖生物群落具有一定毒害作用。     

DPSIR = A Problem Structuring Method? An exploration from the “Imagine” approach

The Drivers, Pressures, State, Impact and Response or DPSIR framework has been with us for over a decade now and it is widely used as a means to assess and measure and, eventually provide a guide to managing the environment. With its repertoire of diagnostic and analytical components the DPSIR can be argued to be a Problem Structuring Method or PSM. Criticisms of the framework abound but it has a resilience which is noteworthy. Some argue that DPSIR, by its nature, is a narrowly formulated, engineering device, incompatible with the multiple perspectives which human interaction in global ecology requires. Is there a value in DPSIR being more flexible in expression and experience of users? In this article it is shown how the DPSIR framework was applied within a multi-methodology approach called Imagine in a number of coastal management projects around the Mediterranean and in other contexts. The article argues that DPSIR, whilst admittedly limited in its scope and approach can, if applied in a participatory and systemic multi-methodology, combine with other tools and help to create outcomes of value to local populations.     

Extraction of Nonylphenol and Nonylphenol Ethoxylates from River Sediments: Comparison of Different Extraction Techniques

Summary Five different extraction techniques (Soxhlet, automated Randall, accelerated solvent extraction, microwave-assisted solvent extraction and extraction with a surfactant solution) have been evaluated for the determination of nonylphenol (NP) and nonylphenol ethoxylates (NPEO) in river sediments. All the techniques were applied to the same three samples collected from northern Italian rivers. The analyses were performed with two RP columns, with different stationary reversed phases—a classical C₁₈ phase and a hexyl–phenyl phase. The recoveries and reproducibility of the different extraction techniques were comparable and all the methods gave reliable results. The variance of the results was dominated by the variance in sample homogeneity, sample preparation, and chromatographic analysis. A choice between the methods can be made on the basis of the cost and safety of each technique. Preliminary results obtained from use of a water-based extraction method with a surfactant solution (Tween-80), and its application to analysis of sediment and of worm tissue, are also presented.Presented at: Chemical Analysis and Risk Assessment of Emerging Contaminants, Barcelona, Spain, November 28–30, 2002     

应用地质累积指数评价成都市河流表层沉积物重金属污染

根据流经成都市内的三条河流(府河、南河、沙河)表层沉积物重金属资料,应用地质累积指数法对重金属污染进行了评价研究。结果表明,河流主要的重金属污染物是Cr,地质累积指数分级多在0~1之间,属于无污染-中度污染范畴。     

Investigation of anthropic effects connected with metal ions concentration, organic matter and grain size in Bormida river sediments

An investigation on the sediment composition and grain size was carried out along the Bormida river (Piedmont, Northern Italy). The samples were taken both in the riverbed and on its banks. Multivariate statistical exploratory methods permitted to identify possible sources of primary pollution. In particular, principal component analysis (PCA) showed that there are probably at least three anthropogenic main causes of pollution, one connected with Cr, Ni and Sn, the second with cadmium and the last one with mercury. Some correlations were found between heavy metal ion concentrations and organic matter and/or the sediment grain size. Differences between the samples collected in the riverbed and on the banks were identified and the relationships between the principal components and the distance of the samples from the riverbed and from the hot spot represented by the ACNA industrial site were also analyzed.