In-Situ Observation of Fluid Mud in the North Passage of Yangtze Estuary, China

Observations of fluid mud were made in the lower North Passage of the Yangtze Estuary in February 2000, on 10 -11 August 2000, on 30 - 31 August 2000 (after two strong typhoons), on 21 - 24 August 2000 (neap tide) and on 3 -6 September 2000 (mean tide) respectively. In situ data show that the fluid mud in this area consists of fine cohesive sediment (median size 7.23 μm). The formation and movement of fluid mud varied during the neap-spring and flood-ebb tidal cycle. Observations suggest that fluid mud phenomena in this area may be categorised in a three-fold manner as slack water, storm and saltwedge features. The thickness of the fluid mud layer of slack water during the neap tide ranged from 0.2 to 0.96 m, whereas during the mean tide, the thickness ranged from 0.17 to 0.73 m, and the thickness of the fluid mud layer was larger during slack water than at the flood peak. Shoals cover an area of 800 km^2 with a water depth smaller than 5 m. Erosion of these extensive intertidal mudflats due to storm action provides an abundant sediment source. This is particularly significant in this estuary when the tidal level is lower than 5 m. The lower North Passage is a typical zone of saltwater wedging, so the saltwedge fluid mud has the most extensive spatial range in the estuary.     

北美洲东南近海布莱克海岭中气体水合物赋存沉积区域内自生碳酸盐矿物的分带特点

自生碳酸盐矿物的分布特点，是体现孔隙水地球化学特征的一个侧面。在布莱克海岭气体水合物赋存的沉积区域里(ODP994#、995#、997#)就利用这点来评价成岩作用。碳酸盐矿物的分布特点揭示了三个独特的成岩分带：(1)在上部20mbsf (bsf：below seafloor，海底以下深度)处的碳酸盐矿物主要是生物成因的，没有显示成岩作用的存在。这个区域的方解石FOC和8180值(PDB)反映了海相碳酸盐的特点，是与海水平衡的条件下沉淀形成的；(2)在20mbsf和100mbsf深度，方解石的FOC值明显呈现负数(低至-7．0‰)，自生白云石较普遍可见(2—40wt％)，δ^13C值在3．6‰～13．7‰之间；(3)在，100mbsf以下，白云石从含量丰富减低至微量分布，而分散状的菱铁矿成为主要出现的矿物。菱铁矿的δ^1C和δ^18O值分别在5．0‰～10．9‰、2．9‰～7．6‰之间变化。把溶解无机碳(DIC)的δ^1C剖面分布特点和孔隙水的浓集梯度趋势与自生碳酸盐矿物的δ^13C和δ^18O值对比，我们发现，自生碳酸盐矿物在一个独特的深度区域里形成，呈带状分布。在20mbsf深度及以下，无机碳的δ^13C DIC出现最小负值(≤-38‰)、方解石白云石出现δ^13C负值，这种现象的出现是伴随着孔隙水碱度的增加、硫酸盐的亏损和孔隙间Ca^ 2 、Mg^ 2 离子的减少一起发生的，这表明自生方解石和自生白云石的形成是在硫酸盐还原带的底部开始(21mbsf左右)而在100mbsf附近深处大量出现。菱铁矿的形成很显然是在120～450mbsf之间发生，这个区间在气体水合物赋存的沉积物区域内和上部(赋存区域200—450mbsf)。菱铁矿的δ^13C和δ^18O值从它们出现的薄层一直到沉积物底部都几乎一致。然而，现在孔隙水中的δ^13C DIC仅仅与120～450mbsf间的菱铁矿的δ^13C值相似。此外，从菱铁矿中计算出来的与之平衡的δ^18O值与120～450mbsf区段处菱铁矿的δ^18O测量值很好地匹配起来。该区段以高碱度(40-120mm)、低Ca^ 2 、Mg^ 2 浓集度为特征，这符合菱铁矿的形成条件。     

Bacterial killing by Mytilus hemocyte monolayers as a model for investigating the signaling pathways involved in mussel immune defence

The signaling pathways involved in mussel immune defence were investigated utilizing a model of killing of Escherichia coli by Mytilus galloprovincialis hemocytes in a co-culture setting. In particular, the role played by different mitogen activated protein kinases (MAPKs) and by the production of eicosanoids were investigated utilising specific cell permeant, pharmacological enzyme inhibitors. Hemocyte pretreatment with the p38 MAPK inhibitor SB203580 significantly reduced bacterial killing, whereas PD98059 (an inhibitor of ERK--extracellularly regulated kinase--MAPK activation) had no significant effect. Wortmannin also inhibited bacterial killing, indicating a crucial role for PI3-kinase activation in the immune response. Killing of E. coli was also reduced by inhibitors of both PLA2 and cyclooxygenase activities, indicating that eicosanoid production is involved in mediating the response to bacterial challenge. The results demonstrate that bacterial killing by mussel hemocytes is particularly sensitive to inhibitors of the key steps involved in the transduction of bacterial signals into the host cell. Moreover, these data indicate that the hemocyte bactericidal activity can be suitably utilized not only for identifying the signaling pathways involved in the response to bacterial infection, but also as a potential investigative-toxicology model to test drugs and contaminants for their effect on the overall mussel immune defence.     

新钻探技术的试验

在实现深海钻探计划和随后的大洋钻探计划的漫长岁月里 ,钻探技术在不断地改进。由于研制出了新的不同的设备和工艺 ,我们成功地获得了连续的沉积建造剖面 ,使得能够极为详细和可靠地恢复沉积盖层的形成史、海洋环流的变化、气候的波动和生物的演化史。但是 ,至今尚未彻底克服在基岩中钻孔所遇到的困难。当在硬质岩石出露的洋底表面区域进行钻探时 ,困难特别大 ,例如在洋中脊的轴部。稳定钻孔 ,特别是重返该钻孔的问题也没有解决。当在若干航次中采用一般工艺进行钻探时 ,确实有顺利钻入基底足够深度的例子 (例如太平洋中的 50 4B孔和印度…     

大尺度海岸行为

大尺度海岸行为ＪｅｆｆｒｅｙＨ．Ｌｉｓｔ等该题目是指对海岸和近岸沉积系统的了解，以及对发生在该系统中的变化的预测。Ｌｉｓｔ（１９９３）定义大尺度海岸行为是几十年的时间尺度内、几至几十公里空间范围内的海岸物理演化．Ｔｅｒｗｉｎｄｔ和Ｗｉｊｎｂｅｒｇ（１...     

Histopathological biomarkers in estuarine fish species for the assessment of biological effects of contaminants

The increasing emphasis on the assessment and monitoring of estuarine ecosystems has highlighted the need to deploy appropriate biological indices for these locations. Fish diseases and histopathology, with a broad range of causes, are increasingly being used as indicators of environmental stress since they provide a definite biological end-point of historical exposure. This study reports on the histopathological alterations observed in selected organs and tissues of three species of estuarine fish (Platichthys flesus, Pomatoschistus minutus and Zoarces viviparus), captured from four British estuaries (the Tyne, Tees, Mersey and Alde), differently impacted by contaminants, including PAHs. A biannual sampling regime was used to identify the important seasonal variations that occur in terms of the observed biological effects. Inflammatory lesions and hepatocellular fibrillar inclusions attained their highest prevalence in P. flesus captured from the Tyne, Tees and Mersey. The presence of pre-neoplastic and neoplastic toxicopathic lesions was highest in P. flesus captured from these sites, when compared to fish from the Aide reference site. In particular, the prevalence of hepatic foci of cellular alteration (up to 43.3%) and hepatocellular adenoma (up to 10%) were highest in P. flesus captured from the Mersey estuary. Intersex (ovotestis) was only recorded in male P.flesus captured from the Mersey estuary (up to 8.3%) and from male Z. viviparous captured from the Tyne estuary (25%). Pathologies associated with the gill and the kidney were also most prevalent in fish captured from the Tyne, Tees and Mersey estuaries. This study has successfully applied histopathology to an estuarine monitoring program, both for the recording of toxicopathic lesions in the liver and other organs, and for the detection of the endpoint of endocrine disruption, intersex. As such, it provides a powerful integrative tool for the assessment of biological effects of contaminants in these environments.     

Can turbidity caused by Corophium volutator (Pallas) activity be used to assess sediment toxicity rapidly?

The standard toxicity test organism, Corophium volutator, exhibits a behavioural response to contaminated sediments that causes increased turbidity of overlying water. We quantify the effects of this response to an estuarine sediment spiked with copper and hydrocarbon contaminated sediments from an oil installation in the North Sea. Turbidity measured 24 h after the start of a toxicity test shows a strong relationship with contaminant concentrations and with mortality after 10 days. Turbidity measurements can therefore give a rapid indication of sediment toxicity, permitting a reduction in storage time of sediments to be used in dilution series and toxicity identification evaluation (TIE) tests, reducing the likelihood of contaminants degrading prior to testing.     

太平洋西南部铁锰矿化的矿物学特征

太平洋西南部铁锰矿化的矿物学特征Ａ．Ｈ．Ｋａｎ等在对克马德克和新赫布里底岛弧—海沟构造系不同地貌构造的地质采样过程中（１９９０年科学考察船“ＡＨｅｃＭＨｏＢ院士”号第１７航次），在一系列测站上采集到不同的铁锰形成物（ＭＯ）。详细研究这些形成物具有特殊...