武汉东湖沉积物中重金属生物有效性研究

沉积物中的酸挥发性硫化物(AVS)是预测厌氧沉积物中重金属生物有效性的重要参数,SEM/AVS大于1时沉积物中重金属具有潜在生物毒性,小于1时则无生物有效性. 本文研究了东湖三个不同污染负荷的站点的同步提取金属SEM(Cu, Zn, Pb, Cd, Ni, Co, Ag, Cr)和SEM/AVS的深度分布,研究表明东湖沉积物中主要重金属是Zn, Cr和Cu,约占SEM总量的90%. I站、II站沉积物中AVS是重金属生物有效性的主控因子之一,对重金属的深度分布影响较大,重金属不具有生物有效性;III站沉积物中AVS对重金属的深度分布影响较小,重金属具有潜在的生物毒性. 相关分析表明,I站、II站沉积物中Cr、Ni、Ag、Cd与AVS在P<0.05有显著性相关,AVS对这些金属的深度分布具有更强的控制作用;虽然两站沉积物中Cr的含量差别不大,东湖I站沉积物中Cr/AVS比值(0.02)显著高于II站(0.003),沉积物中Cr与硫化物的结合主要是受还原反应的影响.     

南海北部陆缘深水-超深水盆地成因机制分析

本文以海洋地质调查和油气勘探开发中积累的地质和地球物理资料的解释和分析为基础,描述和划分了南海北部被动陆缘地壳岩石圈结构构造单元,由陆向海划分出近端带、细颈化带、远端带和洋陆转换带（OCT,含边缘高地）四个构造单元.从细颈化带到OCT基本处于现今陆架坡折带之外的深水-超深水区的范围,以强烈的地壳薄化和发育大型拆离断层控制的拆离盆地为特征.这些深水-超深水盆地的同裂陷阶段均经历了早期均一断陷、中晚期拆离式断陷的演化过程,受控于南海北部大型拆离断层作用及其所导致的岩石圈临界破裂过程.新的深水-超深水盆地形成机理的认识为南海北部陆缘岩石圈的非瞬时伸展破裂过程的分析提供了新的视角,同时,陆缘深水-超深水盆地具有独特的构造-沉积体系配置和构造-热演化过程,将为科学评价南海北部陆缘深水-超深水盆地油气勘探潜力提供新的思路.     

南北地震带垂直形变速率梯度与强震活动研究

垂直形变梯度能够有效反映区域构造运动的垂直差异变化程度。 我们利用长时间段的水准资料结合GPS资料计算垂直形变梯度值, 计算结果显示垂直形变速率梯度的空间分布与构造分布具有显著的相关性, 南北地震带垂直形变速率梯度异常最显著区域在鲜水河断裂带、 龙门山断裂带和小江—则木河断裂带附近, 其次是青藏高原东北缘地区的庄浪河断裂带与冷龙岭断裂带交会区域, 2016年门源6.4级地震就发生在这一异常区域内, 但是从垂直形变速率梯度的高梯度区域分布来看, 在天祝至景泰一带也有发生强震的背景。 三大断裂交会区域是整个南北地震带构造活动最为强烈的区域, 应该注意该地区未来强震发生的危险性。     

Vertical seismic profiling using distributed acoustic sensing with scatter-enhanced fibre-optic cable at the Cu–Au New Afton porphyry deposit,British Columbia,Canada

Wireline logs and vertical seismic profile data were acquired in two boreholes intersecting the main mineralized zone at the Cu–Au New Afton porphyry deposit, Canada, with the objectives of imaging lithological contacts, fault zones that may have acted as conduits that channelled the mineralization, and alteration zones. Log data provide physical rock properties for the main lithologies and alteration zones. Calliper logs reveal many faults and caved-in zones generally indicating rocks with low integrity at the borehole wall. The preponderance of these zones, as indicated by the logs, suggests that their response may dominate the seismic-reflection wavefield. Outside fault zones, compressional and shear-wave velocities exhibit significant variability due to porosity, the heterogeneity of volcanic fragmental rocks and alteration. Distributed acoustic sensing was used to acquire vertical seismic profiling data in the two boreholes surveyed with wireline logs. Straight and helically wound fibre-optic cables housed standard fibres and a fibre engineered to increase the intensity of backscattering at the distributed acoustic sensing interrogator. Standard and engineered optical fibres placed in the two boreholes were daisy-chained together to form two 5-km-long continuous fibres that were interrogated at once with two interrogators. A new generation of interrogator connected to the engineered fibres provided field data with lower noise level and higher signal-to-noise ratio. These data with higher signal-to-noise ratio from straight fibre-optic cable were processed and used for depth imaging. Depth images benefitted from new migration weights that account for the directional sensitivity of the straight fibre-optic cable and limit the extent of migration artefacts. Migration results show several reflectors with shallow dips to the northwest, some explained by faults intersecting the surveyed boreholes. The main sub-vertical lithological and alteration contacts at New Afton generated downgoing reflections that were not considered in the migration.     

常熟台倾斜观测资料的异常特征分析

在研究常熟台水管仪与垂直摆多年倾斜观测资料的基础上,利用潮汐因子调和分析、Nakai拟合检验、小波分析等方法对台站周边约250km范围内发生的高邮-宝应M_S 4.9及如东近海M_S 3.8等地震前的异常信息进行了提取,对数据异常分析方法进行评判,旨在为以后地震前及时发现地震提供参考。     

The vertical distribution of maraena whitefish (Coregonus maraena) early juveniles in different times of day in a newly created oligotrophic lake

Diel vertical distribution of strictly pelagic juvenile (23–47 mm total length) maraena whitefish Coregonus maraena (Bloch, 1779) was repeatedly investigated in spring primarily using hydroacoustics in the artificial post-mining Most Lake in the Czech Republic. At the same time, an ichthyoplankton trawl was used to identify acoustical targets. During the day, fish performed extensive shoaling behaviour in depths between 2 and approximately 40 m and were not accessible for trawling. By evening, with decreasing light intensity, shoals started to disintegrate and at night fish were relatively homogeneously distributed in the water column from the surface down to a depth of 40 m. Juvenile maraena whitefish could be caught by trawl as the only fish species at night. Shoaling behaviour started again approximately 1.5 h before sunrise. The data showed steep decreases in fish density between the two surveys in spring which indicates significant mortality of early juvenile coregonids as a result of poor availability of zooplankton in a highly oligotrophic post-mining lake.     

青藏高原东缘岩石圈结构对现今地表垂向运动影响的数值分析

参考青藏高原东缘松潘-甘孜地块至四川盆地陡变地形起伏和地壳密度结构的横向差异,本文建立了二维牛顿黏性流体有限元模型,计算分析构造加载、陡变地形和重力效应控制下青藏高原东缘岩石圈变形特征,探讨横向不均匀的地壳密度结构、陡变地形和岩石圈流变性质对区域现今垂向运动的影响.计算结果显示：在构造加载作用下,松潘-甘孜地块至四川盆地地表抬升微弱.区域横向不均匀的地壳密度结构驱使松潘-甘孜地块地壳整体抬升,速率高达2 mm·a^-1,四川盆地整体下沉,速率约1 mm·a^-1,与龙门山两侧现今观测到的地表垂向变形模式相近.龙门山地区陡变地形驱使柔性地壳流动,调整区域地壳局部变形;岩石圈流变结构影响重力驱动作用下的模型变形量值和岩石圈变形耦合程度,松潘-甘孜地块较低的中地壳黏滞系数引起上、下地壳的变形解耦;模型较高的岩石圈地幔黏滞系数使重力驱动作用下区域垂向变形量降低.因此,青藏高原东缘地壳密度结构差异、地形起伏和岩石圈流变性质是现今区域垂向变形的重要动力学控制因素.     

新疆精河6.6级地震周边地区密度构造、均衡异常以及岩石圈挠曲机理

依据EIGEN-6C4重力模型和ETOPO1高程模型数据,围绕新疆精河6.6级地震展开岩石圈均衡与挠曲机理研究,得到如下结论：（1）震中附近的布格与自由空气重力异常分别为-221和-92mGal(10~(-5 )m·s~(-2)）,震中位于重力异常高梯度带上;（2）震中周边地区地壳厚度约为50km,密度结构总体变化平缓,东西方向地壳厚度变化较小,但自南向北地壳厚度逐渐变薄,精河6.6级地震初始破裂发生在上中地壳分界面附近;（3）震中附近岩石圈承载的垂向构造应力为20MPa左右,震中位于岩石圈垂向构造应力极大值附近的高梯度带上;（4）地震周边地区岩石圈有效弹性厚度最优解为26km,加载比最优解为F_1=1,F_2=F_3=0,表明该区域岩石圈相对坚硬,且导致岩石圈变形的初始加载全部来自地表．     

Assessing shipping water vertical loads on a fixed structure by convolution model and wet dam-break tests

Estimation of loads derived from shipping water events in naval and offshore structures is of importance to improve their structural design or to predict changes in their dynamics. For the case of vertical loads on deck of a fixed structure, it is possible to estimate analytically their evolution in time by considering the distribution of shipping water elevations. However, the classical approach to estimate this distribution (i.e., dam-break method) tends to overestimate the amount of water on deck and does not follow the generated decay trends observed experimentally. In the present work, the time evolution of the vertical loads due to shipping water events was studied analytically and experimentally. The validation of the use of a convolution model to estimate the time evolution of vertical loads is presented, aiming to improve the results obtained with classical approaches. A systematic experimental study has been conducted using the wet dam-break method to generate isolated shipping water events, measuring the slow-varying vertical loads on a rectangular fixed structure. A force balance and a high-speed camera have been used at the same sampling rate to monitor the vertical loads and the shipping water evolution on the deck. Results demonstrated that the use of the convolution model improved the representation of the time series of loads compared with the traditional dam-break approach. With this new method, it was possible to capture the peaks and the decay tendencies observed in the experimental data in an approximated way.     

The vertical mode method in the problems of flexural-gravity waves diffracted by a vertical cylinder

The linear three-dimensional problem of ice loads acting on a vertical circular cylinder frozen in an ice cover of infinite extent is studied. The loads are caused by an uni-directional hydroelastic wave propagating in the ice cover towards the cylinder mounted to the see bottom in water of constant depth. There are no open water surfaces in this problem. The deflection of the ice cover is described by the Bernoulli–Euler equation of a thin elastic plate of constant thickness. At the contact line between the ice cover and the surface of the cylinder, some edge conditions are imposed. In this study, the edge of the ice plate is either clamped to the cylinder or has no contact with the cylinder surface, with the plate edge being free of stresses and shear forces. The water is of finite constant depth, inviscid and incompressible. The problem is solved by both the vertical mode method and using the Weber integral transform in the radial coordinate. Each vertical mode corresponds to a root of the dispersion relation for flexural-gravity waves. It is proved that these two solutions are identical for the clamped edge conditions. This result is non-trivial because the vertical modes are non-orthogonal in a standard sense, they are linearly dependent, the roots of the dispersion relation can be double and even triple, and the set of the modes could be incomplete. A general solution of the wave-cylinder interaction problem is derived by the method of vertical modes and applied to different edge conditions on the contact line. There are three conditions of solvability in this problem. It is shown that these conditions are satisfied for any parameters of the problem.