A fluorometer on the basis of powerful light emitting diodes for determination of the chlorophyll “a” concentration

A simple fluorometer for determination of the chlorophyll “a” (chl “a”) concentration in an extract based on bright light emitting diodes (LEDs) in the blue and IR spectrum range used as a continuous excitation light source and light detector, respectively, has been described. Results of calibration and validation of the system’s signal with the help of extracts with different chl “a” concentrations are presented.     

浊度对活体叶绿素荧光检测的影响及修正方法

本文研究了泥沙悬浮液浊度对叶绿素荧光计测定水样中活体叶绿素荧光的影响。结果表明,浊度产生的荧光效应和遮蔽效应对活体叶绿素荧光测定具有显著影响。在100 NTU浊度范围内,浊度会导致荧光效应使活体叶绿素荧光值测量结果随着浊度的增大而增大,并构成良好的线性关系;实际测定水体中硅藻的活体叶绿素荧光值时,泥沙悬浮液的浊度会导致遮蔽效应使活体叶绿素荧光值测量结果随着浊度的增大而减小,水体中硅藻质量浓度越高遮蔽效应越显著,在1 000 mV(约10 μg/L)硅藻质量浓度,100 NTU浊度条件下,浊度遮蔽效应可导致活体叶绿素荧光值偏低20%。根据近海泥沙实验数据,本文提出了一种活体叶绿素荧光检测的浊度影响修正方法,在100 NTU浊度内,修正后叶绿素荧光值偏差率都下降到±10%以内,校准后的荧光值与真实叶绿素荧光值较为接近。     

海底峡谷内浊流流动与沉积特征数值模拟研究

数值模拟已成为研究海底浊流的重要方式，开展海底浊流的流动与沉积特征的数值模拟，对深水沉积体系特征研究、海底工程设施稳定性评价以及深海油气勘探均具有重要意义。本文基于不可压缩流体Navier-Stokes方程与湍流k-ε模型构建了浊流数值计算模型，设定不同粒径、速度与悬浮颗粒物浓度等初始条件，模拟并分析了单粒径悬浮颗粒驱动的持续入流的海底浊流沿海底连续坡折带的流动过程及沉积特征。模拟结果显示，浊流在斜坡段处于加速状态，水平段流速骤减并逐渐沉积，且浊流在小坡度的加速不改变浊流的沉积趋势。浊流由于环境水体的夹带效应逐渐增厚，且浊流头部形态与流动特征与实测资料吻合良好。本文另对多频次持续入流浊流进行了模拟，并将模拟结果与实测地层沉积特征对比，结果显示，多频次持续入流的海底浊流在纵向上可能会形成多个不连续鲍玛层序的叠积。     

Analysis of ocean color spectra (II)

A method for evaluating the radiance due to sky light reflected by the sea surface and radiance emerging from the sea is described. The calculation is made as a function of the sun altitude, sky condition and sea state for varying optical properties of sea water. As a result of the contribution of reflected sky light, the shape of the spectral distribution for radiance just below the surface is considerably distorted above the surface, especially when chlorophyll concentrations are high. Special attention is paid to the ratio of radiance emerging from the sea to total upwelling radiance at the wavelength of 670 nrn. The variation in the ratio with wind-speed is small and the ratio decreases with increase in the atomospheric turbidity factor.     

A turbidity survey of Narragansett Bay

A turbidity survey of Narragansett Bay, Rhode Island, was made during the summer months of 1971 and included measurements of the attenuation function for scalar irradiance for daylight and the volume attenuation function for white tungsten light at various depths. One hundred and three stations were made at 17 different locations. Variations in the optical parameters were large, one standard deviation at any given location ranging from 7 to 23 per cent of the mean value. This variation was only slightly dependent on the state of the tidal currents, depth of the location, or weather factors. The magnitude of turbidity variations was almost 4-fold over a north-south range of 31 km within the estuary, with clearest water at the southern mouths of the Bay. A good correlation exists between turbidity parameters and Autumn values of suspended-material concentration found by Morton (1967), with both data sets showing highest turbidity and suspended concentrations in the West Passage of the Bay. “Wedges” and “bulges” of clear water were detected throughout the Bay but were most evident at the southern (Atlantic Ocean) end.Although it was not possible to fully define the parameters producing these temporal and geographic variations in estuarine turbidity, it is suggested that knowledge of these parameters can assist those concerned with the physical and biological state of an estuary, as well as divers and photographers plying their trades within its boundaries.     

用于海洋现场监测的小型叶绿素a荧光计和浊度计

论文描述了一种叶绿素荧光计和浊度计,该仪器采用超亮LED作为叶绿素荧光激发光源,IR管作为浊度照明光源,在光机系统设计上将叶绿素测量功能和浊度测量功能合并,从而使该仪器具备小型化、精度高、便于集成的特点。试验结果表明,该仪器可以用于海洋现场测量。     

光质对条斑紫菜自由丝状体生长和生理指标的影响

光质是影响藻类生长发育的重要因子。本文旨在研究栽培型条斑紫菜(Neopyropia yezoensis)自由丝状体在不同光质(白光、红光、蓝光、绿光)下生长率、形态、超微结构、色素含量及抗氧化酶活性的差异。结果显示:培养21 d后,白光显著提高条斑紫菜自由丝状体特定生长率和叶绿素a含量,其次是红光和绿光,蓝光最差。和白光组相比,蓝光组藻体藻红蛋白(PE)含量最高,红光、绿光组藻体藻蓝蛋白(PC)含量较高。白光组藻体正常黑褐色,细胞壁最厚。红、绿光组藻体绿色,直径和细胞壁厚度与白光组相近。蓝光组藻体鲜艳红色,直径最小,细胞壁最薄,且超微结构显示类囊体上质体小球数量最多。蓝光照射后,藻体丙二醛(MDA)含量最高,超氧化物歧化酶(SOD)活性最低。研究表明,白光最有利于条斑紫菜自由丝状体生长,其次是红光和绿光,蓝光则有不利影响。     

水下光学无线通信的海水信道特性研究

提出了将具有比声学高达几倍的数据通信速率,良好的安全性和隐蔽性的光学无线通信技术应用于海军、海洋科学研究和水下工程等领域,实现高速率的水下无线通信技术实现海量数据的信息交换.基于生物光学特性的水下光学信道模型,建立了水下光学通信系统性能分析方法.并对基于发光二极管(LED)的水下光学无线通信系统进行了仿真,其结果表明所建立的方法可以进行各种海域水质环境的模拟,便于时水下光学无线通信系统性能进行预测评估,为水下光学无线通信系统的设计方案的评估提供了依据.     

Characterization of the solar light field within the ocean mesopelagic zone based on radiative transfer simulations

The solar light field within the ocean from the sea surface to the bottom of the mesopelagic zone was simulated with a radiative transfer model that accounts for the presence of inelastic radiative processes associated with Raman scattering by water molecules, fluorescence of colored dissolved organic matter (CDOM), and fluorescence of chlorophyll-a contained in phytoplankton. The simulation results provide a comprehensive characterization of the ambient light field and apparent optical properties (AOPs) across the entire visible spectral range within the depth range 200–1000 m of the entire mesopelagic zone for varying chlorophyll-a concentration and seawater optical properties in the mixed surface layer of the ocean. With increasing depth in the mesopelagic zone, the solar irradiance is reduced by ~9–10 orders of magnitude and exhibits a major spectral maximum in the blue, typically centered around a light wavelength of 475 nm. In the green and red spectral regions, the light levels are significantly lower but still important owing to local generation of photons via inelastic processes, mostly Raman scattering and to a lesser extent CDOM fluorescence. The Raman scattering produces a distinct secondary maximum in irradiance spectra centered around 565 nm. Comparisons of our results with light produced by the radioactive decay of the unstable potassium isotope contained in sea salt (⁴⁰K) indicates that the solar irradiance dominates over the ⁴⁰K-produced irradiance within the majority of the mesopelagic zone for most scenarios considered in our simulations. The angular distribution of radiance indicates the dominance of downward propagation of light in the blue and approach to uniform distribution in the red throughout the mesopelagic zone. Below the approximate depth range 400–500 m, the shape of the angular distribution is nearly invariant with increasing depth in the green and red and varies weakly in the blue. The AOPs at any light wavelength also assume nearly constant values within the deeper portion of the mesopelagic zone. These results indicate that the mesopelagic light field reaches a nearly-asymptotic regime at depths exceeding ~400–500 m.     

Estuarine classification and response to nitrogen loading: Insights from simple ecological models

Estuaries exhibit a large range in their responses to nitrogen loadings determined in part by characteristics of the driver, such as magnitude and frequency, but also by such intrinsic characteristics as physical/chemical factors (e.g., depth, volume, hypsometry, salinity, turbidity) and biological factors (e.g., nature of ecological communities, trophic interactions). To address the richness of estuarine response to driver variables, the aim ultimately is to establish a simple estuarine classification scheme, beginning with a river-dominated subset of estuarine systems and focusing on the role of water residence time in the estuary. Residence time (or flushing time) is related to other drivers (streamflow, nutrient, and sediment loads) and drives much of the biological response of estuaries because of flushing effects on plankton, temperature, nutrients, and light. Toward this goal, nutrient–phytoplankton–zooplankton (NPZ) models have been used to examine a range of subjects including effects of nutrient limitation and zooplankton predation on phytoplankton dynamics and fish predation. This class of model can admit a wide range of behavior, including multiple steady-states and oscillatory behavior. The NPZ equations include terms for nutrient recycling, phytoplankton settling, benthic regeneration, and zooplankton mortality. Analysis of the equations suggests that both the nature of nitrogen loading (i.e., whether it is correlated with discharge or independent of it) and residence time are critical in determining the steady-state response of the system.     

Airborne Laser Sensing of Scottish Coastal Waters

An Nd:YAG-based airborne lidar system has been used to measure the optical properties of littoral waters off the northwest Scottish coast. The small-scale structure of subsurface scattering layers was also investigated. Methods of solving the Lidar Sensing Equation in the single scattering approximation are described and the values of the derived extinction indices presented. The extinction index averaged over a series of five flights to the northeast of the Gulf Stream was k = 0.224 m -1 with a standard deviation of 0.212 m -1 . Further, it was demonstrated that, in coastal waters, optical inhomogeneities with dimensions between 50 m and 200 km obey the power law Sp k ~ k -P with the parameter P close to two. In turbid or transparent areas, the water extinction index can change by several tenths of a percent with respect to the surrounding water mass. This suggests that the observed nonmonotonic behavior of the power spectra of the water extinction index fluctuations is caused by the outer scale of turbulence, in particular, by the bottom depth at the measurement site.     

Akvazond moored automatic measuring system for vertical profiling of the marine medium

The design and application of the Akvazond moored automatic water profiling system is described. The system was developed at the Shirshov Institute of Oceanology of the Russian Academy of Sciences. The system is designed for multidisciplinary oceanological studies and environmental monitoring on the sea shelves and continental slopes. An autonomous carrier (marine elevator) for different oceanic measuring equipment was developed for the first time in the practice of Russian oceanography. It is a carrier, for example, for an acoustic Doppler current meter, a CTD-profiler, a sensor of dissolved oxygen, a fluorometer, a turbidity meter, etc. The Akvazond system has an energy resource sufficient for profiling the water column in the programming regime for up to several months. The total length of the vertical displacement of the system at a nominal capacity of the power supply reaches 200 km. The main results of the field tests of the Akvazond and preliminary scientific results of its application are presented on the basis of the results of the Black Sea-2006 expedition.     

Advancements in the U.S. army corps of engineers hydrographic survey capabilities: The SHOALS system

In an effort to modernize its hydrographic survey capabilities, the U.S. Army Corps of Engineers has undertaken a joint development program with Canada to construct and field test an operational prototype airborne lidar bathymeter system. The construction and field verification effort of this program began March 1990 with field tests scheduled for winter 1993. The system will be built by Optech, Inc., based on their design of the LARSEN 500, the only commercial lidar system currently producing bathymetric surveys.

The Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS) system will operate out of a medium‐sized helicopter such as the Bell 212 at approximately 200 meters altitude where the laser scanning system generates a swath width of just over 140 meters. System requirements dictate a laser operating at 200 Hz in both the blue‐green wave length for maximum water depth penetration and the infrared for surface interface recognition. Each laser shot strikes the water surface at a known location where its energy is partially reflected back to the receiver and partially transmitted through the water column. Transmitted energy undergoes scattering and absorption along its path to the bottom where the remaining energy is then reflected back to the receiver.

The Transceiver, Positioning, Acquisition, Control and Display, and Ground Based Data Processing subsystems make up the SHOALS system. These subsystems have been designed, constructed, and currently are being laboratory tested prior to total system integration and field testing. This article presents the system's design and discusses system use following development.     

Reconstruction of turbidity currents in Amazon Channel

Quantifying the characteristics of the turbidity currents that are responsible for the erosion, lateral migration and filling of submarine channels maybe useful for predicting the distribution of lithofacies in channel fill and levee reservoirs. This paper uses data from a well-studied submarine channel in Amazon Fan in an attempt to reconstruct the velocity, thickness, concentration, duration, recurrence rates and vertical structure of turbidity currents in this long sinuous channel. Estimates of flow conditions are derived from the morphology of the channels and the characteristics of the deposits within them. In particular, the availability of information on the sediment distribution with respect to the channel topography at the time of deposition allows for insights into the vertical structure of the flow, a key property that has been so far poorly understood. Integration of flow constraints from well and seismic data or from detailed analysis of outcrop with numerical flow models is a critical step toward a complete understanding of the flow and associated deposits. Turbidity currents in sinuous submarine channels, exemplified by Amazon Channel, are found to last for tens of hours and occur on a regular, quasi-annual basis. Model results suggest that these flows had, on average, velocities ranging from 2 to 4 m/s in the canyon/upper fan which decreased to 0.5–1 m/s in the lower fan, travelling in excess of 800 km. The model turbidity currents were subcritical over most of the channel length, indicating a low degree of water entrainment and low rate of deceleration down the channel. The formation of such long, sinuous channels is intrinsically associated with frequent, long-duration, subcritical turbidity currents carrying a silt-dominated sediment load.     

千里崖海域真光层光衰减

根据1986年6月在黄海中部的千里崖海域的水光学实测资料和实验室光学测量,讨论了真光层内光衰减系数在遥感和初级生产力中的应用,定量估算影响光衰减的主要物质成分对光衰减的贡献;并探讨了真光层深度、光衰减系数和透明度三者之间的统计关系。     

The black water around the Changjiang (Yangtze) Estuary in the spring of 2003

The Changjiang (Yangtze) Estuary is located in the East China Sea shelf with shallow water. Affected by the tide mixing and the runoff of the Changjiang River and the Qiantang River, the turbidity is very high. Generally, the water-leaving radiance is high in the turbid water because of the large particle scattering. Based on the in-situ data and ocean color remote sensing data of SeaWiFS, it was found that there was a black water region with the normalized water-leaving radiances less than 0.5 mW/(cm2·μm2·...     

Airborne Laser Sensing of Scottish Coastal Waters

An Nd:YAG-based airborne lidar system has been used to measure the optical properties of littoral waters off the northwest Scottish coast. The small-scale structure of subsurface scattering layers was also investigated. Methods of solving the Lidar Sensing Equation in the single scattering approximation are described and the values of the derived extinction indices presented. The extinction index averaged over a series of five flights to the northeast of the Gulf Stream was ε= 0.224 m -1 with a standard deviation of 0.212 m -1 . Further, it was demonstrated that, in coastal waters, optical inhomogeneities with dimensions between 50 m and 200 km obey the power law Sp ε ~ k -P with the parameter P close to two. In turbid or transparent areas, the water extinction index can change by several tenths of a percent with respect to the surrounding water mass. This suggests that the observed nonmonotonic behavior of the power spectra of the water extinction index fluctuations is caused by the outer scale of turbulence, in particular, by the bottom depth at the measurement site.     

潮间带水沙多层位同步测量系统应用的初步研究

利用水压、光电转换原理研制成的多层位水沙同步测量系统(WCT系统)不仅可测量潮间带水位随时间的变化系列、同一层位的浊度及流速，还可以同步观测这些参数在潮间带水流剖面不同层位上的变化。野外对比试验表明，WCT系统获得的流速值与直读式流速仪的测量结果基本一致，平均相对误差为14．52％；悬沙传感器经野外现场率定获得悬沙浓度，平均相对误差为21．96％，精度比室内率定提高—倍以上。悬沙粒径是影响悬沙浓度测量精度的主要因素。此外，自然环境(如海水温盐度)的变化及仪器本身的特性也可能影响到测量结果。因此，WCT系统在潮间带的水位、流速和悬沙浓度的观测和边界层研究方面有相当潜力。     

基于浮标监测的连云港近海紫菜养殖区水环境特征

为促进海洋渔业经济的健康可持续发展，文章以连云港高公岛附近的紫菜养殖区为研究区域，利用海洋环境综合监测浮标实时监测水环境和气象数据，采用定性和定量相结合的方法，分析紫菜养殖区海域的水温、电导率、水压、溶解氧浓度、pH值、盐度、叶绿素浓度和浊度等水环境因子的统计和变化特征及其相关性，在此基础上分析气象条件对水环境因子的影响。研究结果表明：研究区域的水温和盐度适宜紫菜养殖，浊度属于强变异性；水温和电导率整体呈逐渐升高的趋势，溶解氧浓度和pH值呈逐渐降低的趋势，其他水环境因子呈波动状态；水压的变化与气压具有一致性，水体未受到溶解氧和酸碱污染；水温与电导率之间存在较强的正相关性，水温与溶解氧浓度和pH值之间存在较强的负相关性，pH值与叶绿素浓度和盐度之间存在较强的正相关性；气象条件对水环境因子存在一定的影响，海上大风导致水体浊度陡增。