三维荧光光谱及平行因子分析法在CDOM研究中的应用

文章对有色可溶性有机物(Chromophoric dissolved organic matter:CDOM)三维荧光特性的研究进行了综述,指出了三维荧光光谱分析在水体CDOM特性研究中存在的优缺点;阐述了平行因子分析法在水体CDOM研究中的具体应用程序及运用此方法识别得到的水体组分;汇总了当前表征CDOM荧光特性的常用指标;总结了国内外在三维荧光光谱研究水体CDOM特性方面的进展,详述了不同类型水体中CDOM的组分特性、生物地球化学循环的研究热点以及影响CDOM三维荧光光谱特性的一些主要因素;最后,对三维荧光光谱技术在未来的发展及应用进行了展望。     

PC-104 模块在水下原位化学分析仪器中的应用

使用PC-104 嵌入式平台作为控制模块开发了流动注射分析仪的控制和采集系统, 实现了载流驱动、进样控制及CCD(charge coupled device)光谱数据采集等复杂功能。结果表明: PC-104 模块在复杂控制和海量数据采集方面具有很好的实用性, 能大大缩短开发周期, 为结构复杂的水下原位化学分析仪的开发提供良好的控制采集平台。     

东海典型水体的黄色物质光谱吸收及分布特征

水体中的有色可溶性有机物(又称"黄色物质")是遥感监测水质分类的主要参数之一,研究其光谱吸收性质具有重要的实际意义。东海海区受长江冲淡水等陆源输入的影响,水体浑浊,光学性质复杂,以往对该区域CDOM吸收特征的研究相对较少。利用"九○八"我国近海海洋光学调查航次数据,获得了2006-2007年四个季节东海水体样品CDOM的光谱吸收数据,建立了包括杭州湾高浑浊水体、长江冲淡水、外海水体等东海不同水体类型的CDOM光谱模型及其典型波段的吸收系数分布情况。发现近岸受陆源输入影响大的海区其光谱性质与外海有明显区别,主要体现为近岸尤其在杭州湾附近站点短波段吸收系数值非常高,而且随波长增加吸收系数曲线衰减迅速,同时还有一定的季节变化,外海站点短波段吸收值则明显要低。这反映了CDOM的陆源输入特性,愈向外受到海水的混合稀释作用愈显著,验证了CDOM可以作为近岸海水水质监测的重要参数。对该海区内CDOM的实测荧光性质进行了相关分析,结果表明CDOM荧光与吸收系数之间有很好的线性相关关系,可以作为荧光方法遥感监测该海区CDOM的有价值的参考。     

PC-104模块在水下原位化学分析仪器中的应用

使用PC-104嵌入式平台作为控制模块开发了流动注射分析仪的控制和采集系统,实现了载流驱动、进样控制及CCD（charge coupled device）光谱数据采集等复杂功能。结果表明：PC-104模块在复杂控制和海量数据采集方面具有很好的实用性,能大大缩短开发周期,为结构复杂的水下原位化学分析仪的开发提供良好的控制...     

珠江口磨刀门溶解有机物CDOM 三维荧光光谱特征

采用三维荧光对珠江口磨刀门夏秋季有色溶解有机物(CDOM)时空变化进行研究,分析其组成及荧光强度。结果表明, CDOM 三维荧光峰谱包括 UV 类腐殖质 A、陆源 Vis 类腐殖质 C 和海源 Vis类腐殖质M,以及类蛋白质T。在入海过程中,其组成未发生变化,但其荧光强度随盐度增加逐渐减小,反映了CDOM主要来源是陆源,并且主要受海水物理稀释控制,是一种典型的保守混合行为。在定点站位涨落潮周期中, CDOM的荧光强度不仅受到海水稀释的作用,表层水体CDOM受到紫外线的光降解作用,同时中层水体CDOM受到浮游植物的影响,反映了盐度、紫外线强度、生物活动对CDOM具有的共同影响。     

西太平洋冬季上层水体有色溶解有机物的分布和转化特征

为深入解析西太平洋溶解有机碳的生物地球化学过程,本研究于2015年12月至2016年1月,开展了西太平洋上层水体有色溶解有机物（CDOM）吸收光谱和荧光光谱特征研究。研究结果表明,西太平洋上层水体CDOM吸收系数a（320）变化范围为0.01~1.07 m-1,平均值为0.18 m-1;其较高值位于100~200 m水层,表层的海水相对含量较低,主要以有机物的光化学分解为主。采用PARAFAC分析CDOM三维荧光光谱特征,得到1种类腐殖质组分C2（252（310 nm）/405 nm）及2种类蛋白组分C1（224（276 nm）/335 nm）和C3（224（260 nm）/300 nm）,其中类腐殖质荧光组分占总荧光强度的11%~22%,蛋白质荧光组分占总荧光强度的78%~89%,蛋白质荧光中类色氨酸和类络氨酸组分对荧光强度的贡献相当。洋流在大尺度上控制西太平洋CDOM的分布特征,两流交界处和环流形成区域的CDOM相对含量较高,荧光信号较强。西太上层水体CDOM相对含量和荧光信息,与温度、盐度、DO和营养盐等理化因素之间的相关分析结果表明,CDOM主要成分类蛋白质的产生主要受上层水体初级生产过程控制。     

海水有色可溶性有机物质荧光光谱的质量浓度响应

用自制的海水有色可溶性有机物(CDOM)干粉配制不同质量浓度的水溶液,研究其对三维荧光光谱(EEMS)和同步荧光光谱(SFS)的影响。结果表明:当CDOM质量浓度ρ≥62.5 mg/L时,其EEMS均为单一峰,随着质量浓度降低,激发和发射波长向短波长方向移动,这种波长移动变化与质量浓度的变化呈良好的线性相关关系;当ρ≤52.5 mg/L时,其三维荧光光谱显示3个峰。质量浓度在此范围内变化时,EEMS谱形基本不变。不同质量浓度CDOM水溶液的SFS显示,当质量浓度ρ≥150 mg/L时,随着质量浓度降低,激发和发射波长也向短波长方向移动,其谱形也发生变化;当ρ<150 mg/L时,激发和发射波长不发生漂移,谱形不变,荧光强度随质量浓度降低而降低。一定范围内CDOM质量浓度的变化会影响EEMS和SFS的谱形,从而影响EEMS和SFS法定性判定水体CDOM质量浓度的准确性。用EEMS和SFS法定性不同水体中的CDOM要考虑质量浓度的影响。     

水体中有色可溶性有机物遥感在海岸带调查中的应用——以密西西比-阿查法拉亚海湾水域为例

有色可溶性有机物(CDOM)是溶解性有机物的重要组成部分,其光学行为和生物地球化学循环对水体生态系统有明显影响,是海岸带调查的重要指标.通过遥感方法监测水体CDOM的变化是海岸带环境动态监测的重要方法,介绍了CDOM遥感监测的原理及常用的遥感数据,并通过墨西哥湾西北部的密西西比-阿查法拉亚海湾水域系统进行CDOM光学性...     

厦门湾有色溶解有机物的光吸收特性研究

研究了厦门湾九龙江河口区、西海域、同安湾及东侧水道海水中有色溶解有机物(CDOM)的光吸收特性,分析了CDOM的河口行为,并讨论了CDOM光吸收特性与其荧光性质之间的关系。结果表明,厦门湾表层海水CDOM光吸收系数a(355)的水平分布表现为河口区最高、东侧水道最低、西海域和同安湾介于两者之间,底层水a(355)的分布与表层基本相似,表明陆源河流输入是厦门湾CDOM的主要来源;a(355)的垂直分布为表层高于底层,主要受水文和生物因素控制。厦门湾表层水CDOM光谱斜率S的平均值介于0.014—0.018nm-1,但河口低盐度区S值较小,反映陆源腐殖质的影响。a(355)在河口混合中呈保守行为,表明CDOM具有良好的保守性质。CDOM的吸收系数a(355)与其荧光强度之间表现为较好的相关关系,指示可以用灵敏度更高的荧光方法来研究CDOM的分布和行为。     

水体中有色可溶性有机物的研究进展

有色可溶性有机物(CDOM)是水体中一类重要的光吸收物质,在短波的吸收大大降低了紫外辐射在水体的衰减,因而其光学行为和生物地球化学循环将对水体生态系统产生重要影响。CDOM在水体生态系统、水色遥感和全球碳循环研究中具有广阔的应用前景。文章综述了国内外CDOM研究现状与动态,其中包括CDOM的光吸收特性、荧光特性、光化学降解以及CDOM和DOC浓度的水色遥感,最后提出在内陆水体湖泊中开展CDOM研究的设想。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.