The double solid reactant method: II. An application to the shallow groundwaters of the Porto Plain,Vulcano Island (Italy)

This paper presents an example of application of the double solid reactant method (DSRM) of Accornero and Marini (Environmental Geology, 2007a), an effective way for modeling the fate of several dissolved trace elements during water–rock interaction. The EQ3/6 software package was used for simulating the irreversible water–rock mass transfer accompanying the generation of the groundwaters of the Porto Plain shallow aquifer, starting from a degassed diluted crateric steam condensate. Reaction path modeling was performed in reaction progress mode and under closed-system conditions. The simulations assumed: (1) bulk dissolution (i.e., without any constraint on the kinetics of dissolution/precipitation reactions) of a single solid phase, a leucite-latitic glass, and (2) precipitation of amorphous silica, barite, alunite, jarosite, anhydrite, kaolinite, a solid mixture of smectites, fluorite, a solid mixture of hydroxides, illite-K, a solid mixture of saponites, a solid mixture of trigonal carbonates and a solid mixture of orthorhombic carbonates. Analytical concentrations of major chemical elements and several trace elements (Cr, Mn, Fe, Ni, Cu, Zn, As, Sr and Ba) in groundwaters were satisfactorily reproduced. In addition to these simulations, similar runs for a rhyolite, a latite and a trachyte permitted to calculate major oxide contents for the authigenic paragenesis which are comparable, to a first approximation, with the corresponding data measured for local altered rocks belonging to the silicic, advanced argillic and intermediate argillic alteration facies. The important role played by both the solid mixture of trigonal carbonates as sequestrator of Mn, Zn, Cu and Ni and the solid mixture of orthorhombic carbonates as scavenger of Sr and Ba is emphasized.

冬至初春黄海暖流的路径和起源

主要根据近几年来中韩黄海水循环动力学合作调查结果,结合有关观测资料,进一步分析了冬至初春黄海暖流的路径和起源.与以往类似研究不同的主要有两点:(1)初步探讨了黄海暖流路径的季节和年际变异,并指出这种变异与北向风的强弱密切相关;(2)通过分析济州岛西侧海域混合水的去向,进一步确认了部分混合水绕济州岛运行,并进入济州海峡这一事实.同时,初步揭示进入黄海的混合水,即黄海暖流水,含有更多的东海陆架水成分.     

Cross-Calibration and Long-Term Monitoring of the Microwave Radiometers of ERS, TOPEX, GFO, Jason, and Envisat

The radiometers on board the satellites ERS-1, TOPEX/Poseidon, ERS-2, GFO, Jason-1, and Envisat measure brightness temperatures at two or three different frequencies to determine the total columnal water vapor content and wet tropospheric path delay, a major correction to the altimeter range measurements. In order to asses the long-term stability of the path delay, the radiometers are calibrated against vicarious cold and hot references, against each other, and against several atmospheric models. Four of these radiometers exhibit significant drifts in at least one of the channels, resulting in yet unmodeled errors in path delay of up to 1 mm/year, thus limiting the accuracy at which global sea level rise can be inferred from the altimeter range measurements.     

1998年长江巨洪与厄尔尼诺事件

1997～ 1 998年出现了 2 0世纪中最强的一次厄尔尼诺事件。根据长江洪水与厄尔尼诺事件的实测资料 ,指出 1 998年的长江巨洪与这次厄尔尼诺事件具有较密切的关系。同时讨论了厄尔尼诺事件影响长江洪水的物理途径 ,这对长江巨洪的长期及超长期预报具有较重要的指示作用     

随机激励下非线性海洋结构物响应分析方法研究进展

对在随机载荷作用下非线性海洋结构物的运动响应分析的各种方法进行了综述,对有些方法的基本原理做了阐述,并指出一些最新的研究进展和今后进一步研究的方向。     

无舵翼水下机器人路径跟踪控制研究

针对无舵翼水下机器人的各种不同任务要求下的路径跟踪控制进行研究。通过模拟人的运动行为,建立了虚拟避碰声纳模型。根据地形跟踪的方法提出基于虚拟声纳的路径跟踪控制方法,并通过考虑纵向速度对于其他各个自由度运动的影响设计了运动控制器。通过海上试验验证了所提出的路径跟踪控制方法对于无舵翼水下机器人是可以满足实际需要的。     

Late Holocene estuarine–inner shelf interactions; is there evidence of an estuarine retreat path for Tampa Bay, Florida?

The purpose of this study was to determine if and how a large, modern estuarine system, situated in the middle of an ancient carbonate platform, has affected its adjacent inner shelf both in the past during the last, post-glacial sea-level rise and during the present. An additional purpose was to determine if and how this inner shelf seaward of a major estuary differed from the inner shelves located just to the north and south but seaward of barrier-island shorelines. Through side-scan sonar mosaicking, bathymetric studies, and ground-truthing using surface grab samples as well as diver observations, two large submarine sand plains were mapped – one being the modern ebb-tidal delta and the other interpreted to be a relict ebb-tidal delta formed earlier in the Holocene. The most seaward portion of the inner shelf studied consists of a field of lobate, bathymetrically elevated, fine-sand accumulations, which were interpreted to be sediment-starved 3D dunes surrounded by small 2D dunes composed of coarse molluscan shell gravel. Additionally, exposed limestone hardbottoms supporting living benthic communities were found as well. This modern shelf sedimentary environment is situated on a large, buried shelf valley, which extends eastward beneath the modern Tampa Bay estuary. These observations plus the absence of an incised shelf valley having surficial bathymetric expression, and the absence of sand bodies normally associated with back-tracking estuarine systems indicate that there was no cross-shelf estuarine retreat path formed during the last rise in sea level. Instead, the modern Tampa Bay formed within a mid-platform, low-relief depression, which was flooded by rising marine waters late in the Holocene. With continued sea-level rise in the late Holocene, this early embayment was translated eastward or landward to its present position, whereby a larger ebb-tidal delta prograded out onto the inner shelf. Extensive linear sand ridges, common to the inner shelves to the north and south, did not form in this shelf province because it was a low-energy, open embayment lacking the wave climate and nearshore zone necessary to create such sand bodies. The distribution of bedforms on the inner shelf and the absence of seaward-oriented 2D dunes on the modern ebb-tidal delta indicate that the modern estuarine system has had little effect on its adjacent inner shelf.     

An Experi mental Study on Wave-Induced Dynamic Stresses in Seabed

1 .IntroductionEvery year ,Taiwanis subjectedtotwo or three typhoonintrusions in average which always causedisasters . Most of the disasters which occur around the coastal zone are due to seabed instability andcoastal structure destruction caused bytyphoo…     

南海毛蚶形态特征对体重的相关分析

随机选取同龄南海毛蚶Scapharca subcrenata雌性62只、雄性59只,测量壳长、壳厚、壳高、后闭壳肌直径、放射肋数及活体重。采用通径分析方法研究南海毛蚶5个形态特征对体重的总效应,并以综合决定系数为确定形态性状重要性的准则。结果表明,两性中壳厚、壳高和壳长与体重均为正相关(p<0.01),直接和间接途径都不是体重的限制因素。壳厚、壳高的平均综合决定系数分别为0.423和0.412,是影响体重最主要因素且都具有育种意义。     

电磁波信号在对流层中路径弯曲改正的级数展开式

大气折射延迟是空间大地测量中的一个主要误差源。本文严格地给出了中性大气路径弯曲改正的原理性公式。通过对各种因素量级的分析,在亚毫米量级的精度上给出了一个以视天顶距正切和正割乘积为参数的级数展开模型。新模型在球对称大气模型下,级数展开模型的精度达到了毫米量级,理论上可以展开到任意阶次,且可允许观测高度角小到5°。