Stratification and tributyltin variability in San Diego Bay

Tributyltin (TBT), a biocidal antifoulant in many marine paints, was measured in near-surface and near-bottom water over a 25 h period at the entrance to a marina in San Diego Bay, USA. Surface water concentrations varied from 20 to 225 nanograms per liter (ng dm^?3) as TBT chloride and bottom water varied from non-detectable (<1 ng dm^?3) to 77 ng dm^?3. Surface water concentrations varied, with highest concentrations associated with ebbing tides, and lowest concentrations with flooding tides, indicating that the yacht basin is a source of TBT. Bottom water TBT concentrations were almost always lower than corresponding surface water concentrations. The highest bottom water concentrations were associated with flooding tides and lowest surface water TBT concentrations. Physical water column measurements indicate that vertical stratification developed during ebbing tides and dissipated during flooding tides. This accounted for maximum bottom water and minimum surface water TBT concentrations during flooding tides, due, at least in part, to vertical mixing and dilution during flood tides.     

Two-step explicit finite element method for two-layer flow analysis

A finite element method for the analysis of two-layer density flows is presented in this paper. The standard Galerkin method based on linear interpolation functions is used to yield discrete spatial variables. For numerical integration in time, an explicit two-step selective lumping method is used. Here it is applied to a flow analysis of Ishikari Bay, at the mouth of Ishikari River. This case demonstrates a procedure that yields a numerically stable solution.     

胶州湾海水溶解有机物三维荧光特征研究

应用三维荧光光谱(excitation-emission matrix spectroscopy, EEMs)研究了不同河流输入有机物对胶州湾海水中溶解有机物荧光特征的影响。结果表明,生活污水和工业废水的排放使附近海水中类腐殖质荧光位置发生红移;类蛋白荧光在海泊河附近最强,类腐殖质荧光在李村河附近最强,中心海区荧光强度最弱,表明沿岸河流输入是胶州湾海水中有机物的主要来源,而中心海区有机物主要来源于现场生物活动。不同河口附近区域样品中有机物的类蛋白和类腐殖质荧光强度之间相关性不同,表明河流输入有机物的影响。胶州湾大部分海水中有机物的类蛋白与类腐殖质荧光强度之间的比值较大,表明可能受到了人类活动产生类蛋白有机物的污染。研究结果对于分析海水中有机物来源以及河流排放污染物的迁移等过程具有一定的指导意义。     

Detection of Supernova Neutrinos on the Earth for Large θ_(13)

Supernova （SN） neutrinos detected on the Earth are subject to the shock wave effects, the Mikheyev- Smirnov-Wolfenstein （MSW） effects, the neutrino collective effects and the Earth matter effects. Considering the recent experimental result about the large mixing angle 013 （-8.8°） provided by the Daya Bay Collaboration and applying the available knowledge for the neutrino conversion probability in the high resonance region of SN, PH , which is in the form of hypergeometric function in the case of large 813, we deduce the expression of PH taking into account the shock wave effects. It is found that PH is not zero in a certain range of time due to the shock wave effects. After considering all the four physical effects and scanning relevant parameters, we calculate the event numbers of SN neutrinos for the ＂Garehing＂ distribution of neutrino energy spectrum. From the numerical results, it is found that the behaviors of neutrino event numbers detected on the Earth depend on the neutrino mass hierarchy and neutrino spectrum parameters including the dimensionless pinching parameter βa （where a refers to neutrino flavor）, the average energy 〈Ea〉, and the SN neutrino luminosities La. Finally, we give the ranges of SN neutrino event numbers that will be detected at the Daya Bay experiment.     

Variations of δ15N-Values and Hydrolyzable Amino Acids in Settling Particles in the Ocean

Abstract

The modification of nitrogen isotopic signals during particle sedimentation in the sea is of great interest for the use of sedimentary δ¹⁵N-values as a paleoceanographic tool. The effect of organic matter degradation on such modification was studied by analyzing nitrogen, hydrolyzable amino acids (THAA) and δ¹⁵N-values in a suit of marine settling particles collected from the Bay of Bengal, Indian Ocean, by using time-series sediment traps, and in underlying sediments. The flux of settling particles showed temporal variations which are related to the monsoons, the major climatic feature of this marine region. During high flux periods settling particles are enriched in nitrogenous material that is less degraded and exhibit higher δ¹⁵N-values than particles showing characteristics of degradation. At the sediment surface more than 95% of the settling particulate nitrogen is lost and the δ¹⁵N-values of the residual sedimentary nitrogen are higher than those of settling particles. The observed increase is interpreted to be due to fractionation during degradation of organic matter.     

胶州湾海域Landsat8/OLI数据处理中多种大气校正方法的评价

海洋水色遥感研究中,精确的水体遥感反射比R_rs(λ)光谱数据是应用海洋光学卫星数据反演海洋生物地球物理参数的关键。实际工作中,遥感反射比是根据遥感仪器接收到的辐亮度经大气吸收和散射校正、太阳距离以及太阳高度角校正后计算出来的。因此对卫星传感器数据进行大气校正是我们得到精确的水体遥感反射比光谱数据的关键因素之一,也是海洋水色遥感研究中的一个重要问题。胶州湾是黄海西部的一个半封闭海湾,是北温带海湾生态系统的重要代表,该海域内规划了大范围的海洋牧场养殖区域,水体生物光学性质复杂。Landsat是美国NASA的陆地卫星计划,最初是为了观测陆地而研发,但是其高空间分辨率(30 m)的优势在海洋遥感监测中表现突出,使得其成为卫星遥感监测河流、湖泊、内陆环湾等水体不可忽略的数据源之一。基于QA(quality assurance) Score光谱质量评价体系对Landsat8/OLI数据处理中五种大气校正算法在胶州湾海域的大气校正结果进行了评价分析。五种大气校正算法分别是NASA(National Aeronautics and Space Administration)标准近红外大气校正算法(Seadas采用为默认大气校正算法,记为Seadas Default);Acolite 默认大气校正算法—暗光谱拟合算法（dark spectrum fitting,记为Acolite DSF）;以及Acolite指数外推算法（exponential extrapolation）,根据算法中所使用波段的不同,分别记为Acolite SWIR, Acolite Red/NIR, Acolite NIR/SWIR。分析结果表明在胶州湾海域Seadas Default的大气校正算法得到的R_rs(λ)数据QA得分为1的概率（83.95%）要远大于Acolite DSF（49.66%）,Acolite SWIR（4.13%）,Acolite Red/NIR（7.25%）,Acolite NIR/SWIR（1.38%）四种大气校正算法。Acolite DSF大气校正算法优于Acolite SWIR,Acolite Red/NIR,Acolite NIR/SWIR。应用MODIS/Aqua卫星数据对Seadas Default大气校正算法和Acolite DSF大气校正算法处理Landsat8/OLI卫星数据得到的R_rs(λ)在443,483,561和655 nm的数据进行了对比分析,结果表明在各个波段的Seadas Default算法所得的大气校正结果都要优于Acolite DSF算法。据此,建议在胶州湾及其附近海域应用Landsat8/OLI数据进行遥感应用研究时以NASA标准近红外大气校正算法为首选。     

Effect of open boundary condition on numerical simulation of three-dimensional hydrothermal behavior of Biscayne Bay,Florida

A three-dimensional time dependent free-surface model has been used to simulate the velocity and temperature distributions in Biscayne Bay, an estuarine basin in South Florida. Comparisons with tide gauge data and airborne infrared temperature data have been made. Analyses of three-dimensional velocity structure, phase relationships of velocity with depth and horizontal location have been conducted. One of the major concerns with three-dimensional models is the specification of conditions at open-boundaries, since it is rare that complete time dependent variations of variables at these boundaries are available. Two sets of approximate boundary conditions at the Biscayne Bay-Atlantic Ocean interface have been used for computations. It was found that specification of averaged surface height variation at open boundaries yield significantly better results than specification of estimated values of velocity.     

A numerical modelling study of the flow and salinity structure in the Godavari Estuary,east coast of India

The Godavari Estuary in Andhra Pradesh (a state bordering the east coast of India) communicates with the Bay of Bengal. Conditions in the estuary are characterized by a seasonally varying freshwater discharge and an intrusion of salt water from the bay dependent upon the flow associated with the semi-diurnal component of the astronomical tide. A numerical model is applied to simulate the flow and salinity structures, which in the case of the Godavari Estuary have also been determined observationally and are documented in the literature. Observational data on the flow and salinity structure during two seasons are used in a comparison with theoretical results derived using a turbulent energy equation. Reasonable agreement is obtained between the model results and the observational data; in particular, streamlines are computed for the tidally averaged (or mean) component of the density-controlled flow.