共查询到20条相似文献，搜索用时 78 毫秒
1.
2.
3.
根据2017年7月14日、9月1日和9月3日在山东省威海市褚岛北部海域现场测定的数据,对叶绿素Chl-a、化学需氧量CODmn、溶解氧DO和酸碱度p H等海水生化参数的时空变化特征及相关性展开分析。分析结果表明:(1)在3次测量中,7月14日整个测试海域Chl-a和CODmn浓度处于低值,DO和p H处于高值状态,其中6号站点DO达到9.08 mg/L,p H达到8.10;9月1日整个测试海域中Chl-a和CODmn浓度处于高值,其中12号站点叶绿素浓度达到5.04 mg/m3,CODmn达到0.755 mg/L,p H和DO处于低值状态;9月3日的观测值,Chl-a和CODmn数值与7月14日相近,p H和DO数值与9月1日相近;(2)从空间上看,在整个测试海域中,Chl-a、CODmn和p H的高值区有单峰和双峰型;DO的高值区基本是单峰型;(3)从3个航次整体测量数据来看,Chl-a与CODmn、DO和p H相关性不显著;CODmn与DO有显著相关性,但与p H相关性不显著,DO和p H相关性显著,从具体航次测量数据来看,这些生化参数之间的关系展现出复杂性。 相似文献
4.
胶州湾增养殖海域营养状况与赤潮形成的初步研究 总被引：12，自引：1，他引：11
根据对胶州湾女姑山增养殖海域1998年5月～9月的连续监测资料,参照潜在性富营养化的概念,应用NQI指数对该海域的营养状况进行分析。认为该海域水质富营养化是7月3～8日Skeletonemacostatum和Biddulphiaaurita混合型赤潮形成的基础,磷、硅营养盐的消耗是赤潮消亡的主要原因;赤潮消亡之后浮游植物群落发生演替,水体叶绿素a仍保持较高含量,NQI指数也相应较高,水质表现为磷限制潜在性富营养化,由于磷酸盐的限制没有发展为赤潮。 相似文献
5.
为了理清米氏凯伦藻赤潮形成与环境因素的关系,掌握其发生、发展规律,本文分析了2012年春末夏初三沙湾海域米氏凯伦藻赤潮期间的气象、水文和营养盐情况,并结合室内模拟培养实验,探讨了米氏凯伦藻赤潮形成与各环境因素的相关性。结果显示米氏凯伦藻赤潮通常发生在温度为20.5~25.0℃和盐度为24.3~32.3的海域,其细胞生长的最适温度和最适盐度分别为:22.0~25.0℃和26.0~30.0;Pearson相关性分析显示,米氏凯伦藻细胞密度与叶绿素a、无机磷、化学需氧量呈极显著正相关,与透明度、氨氮呈显著负相关;另外,米氏凯伦藻对磷酸盐的需求较低,其赤潮的形成可能主要受水体中氨氮的影响。基于现场调查和模拟实验结果,综合分析认为稳定的水文和气象条件、发生前期降雨输入的无机氮,以及由于持续阴雨导致的较低光照条件是此次米氏凯伦藻赤潮形成和维持的重要条件。 相似文献
6.
相较于船舶走航监测, 海洋水质浮标在线监测的优势在于能够获取目标海域长期、连续监测数据, 能更好地反映环境状况的动态变化。为了厘清米氏凯伦藻赤潮的发生、发展动态, 本文以2017年6月南麂附近海域米氏凯伦藻赤潮为例, 分析海洋水质浮标获取的连续监测数据, 探讨米氏凯伦藻赤潮过程叶绿素a和水环境因子动态变化特征及其与气象要素的关系。赤潮期间, 水温为22.8~26.0℃、盐度为28.8‰~31.8‰、气温为20.4~27.3℃, 该温盐范围均适宜米氏凯伦藻的细胞生长; 较高的光照强度能够支持较高的藻类细胞密度。Pearson相关性分析显示, 米氏凯伦藻细胞密度与叶绿素a浓度呈显著正相关; 溶解氧(DO)及其饱和度(DO%)、pH、水温、气温等环境因子与叶绿素a浓度呈极显著正相关, 盐度与叶绿素a浓度呈极显著负相关。向岸风生海流有利于藻种向近岸较高营养区域汇集, 为赤潮的爆发创造有利条件。赤潮过程中, 叶绿素a浓度、溶解氧饱和度、pH发生了协同变化, 据此特征可以开展赤潮短期预警。 相似文献
7.
8.
9.
本文从赤潮发生前的天气系统与赤潮位置关系,发生与消亡时水文气象各因子变化情况出发,对2007～2015年发生在江苏海域的各个赤潮案例进行全方位分析。研究发现:在赤潮发生海域邻近都有低压或温带气旋出海过程,且大部分在黄海海域停留了24 h左右。天气系统一般出现在赤潮前1～12 d,且赤潮大部分发生在天气系统移动方向的左侧。赤潮发生前出现的降压、升气温、降水、向岸大风、升水温、降盐、向岸浪等特征,有利于赤潮的发生;赤潮发生后期出现的升压、降气温、无降水、大风、降水温、升盐、大浪等特征,可能有利于赤潮的消亡;同时,初步给出引发赤潮发生与消亡的各水文气象要素变化的量值范围。研究得到的结论,可用于江苏海域赤潮发生与消亡条件预测。 相似文献
10.
11.
Chandralata Raghukumar G. Sheelu P. A. Loka Bharathi Shanta Nair C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16
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. 相似文献
12.
Derek V. Ellis 《Marine Georesources & Geotechnology》2001,19(1):51-63
This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested. 相似文献
13.
G. Parthiban 《Marine Georesources & Geotechnology》2000,18(3):223-235
Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement. 相似文献
14.
Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
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. 相似文献
15.
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. 相似文献
16.
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。 相似文献
17.
The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments. 相似文献
18.
19.
20.
《海洋学报(英文版)》2014,(11):161-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献