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红树林输送的溶解态陆源有机质是海洋中陆源有机质的主要来源之一,对其光降解和生物降解过程的研究有助于进一步了解红树林生态系统输出的有机质在近岸的归宿以及对近岸水体生物地球化学过程的影响,因此于2010年4月在海南省清澜港红树林采集间隙水,并进行了光降解和生物降解培养实验。分析了光培养(光降解)和暗培养过程(生物降解)中溶解态有机碳(DOC)、细菌以及溶解态木质素等的变化。结果显示经历128 d的暗培养后,DOC由初始的2 216 μmol/L下降至718 μmol/L,表明红树林间隙水的生物可利用性约为70%左右;经历11 d的自然光照后,DOC下降至800 μmol/L。木质素在光降解过程中的移除速率(-0.132 d-1)远高于生物降解过程(-0.008 d-1)。光培养中,木质素的下降速率高于总体DOC。不同系列溶解态木质素的下降速率不同,随着培养的进行,紫丁香基酚类(S)与香草基酚类(V)的比值(S/V)呈下降趋势,而V系列的酸醛比值((Ad/Al)v)呈上升的趋势。对比光培养和暗培养过程中DOC和木质素的变化可以得出生物消耗是引起红树林间隙水DOC从水体中移除的主要因素;而光照则是陆源有机质从水体中移除的主要因素;光培养和暗培养过程中细菌变化的差异表明光照可以促进细菌对溶解态有机碳的利用。与其他地区比较发现,海南红树林间隙水的光降解速率与热带河流(刚果河)相近,高于温带密西西比河流,降解过程中各参数的变化[S/V和(Ad/Al)v]与其他区域接近。 相似文献
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本文通过对太平洋北部17个站位铁锰结核、间隙水、沉积物和细菌资料的初步研究表明:研究区铁锰结核中Mn主要来自间隙水中Mn~(m )的扩散,而间隙水中Mn~(2 )主要来自沉积物中Mn~(4 ),在细菌的媒介下,参加了沉积物中有机碳的矿化反应,接收了沉积物中某些有机物的电子后被还原。因而提出细菌在太平洋铁锰结核生长及形成过程中起了重要作用。 相似文献
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《热带海洋学报》2016,(4)
调查了珠江口不同季节颗粒有机碳(particulate organic carbon,POC)和溶解有机碳(dissolved organic carbon,DOC)含量的分布特征,结合碳氮比值(C/N)、叶绿素a(Chl a)含量、溶解氧(dissolved oxygen,DO)含量等水化学参数,探讨了珠江口POC、DOC来源、输送方式及混合行为的季节变化。结果表明,珠江口水体POC可能主要受到水体自生浮游植物有机碳输入的影响,DOC可能主要来自于河流输送的陆源有机碳。在降雨量较大的5月份,POC来自自生浮游植物有机碳的贡献相对减小。降雨量同样较大的8月份DOC来自河流输送的陆源有机碳的贡献增加。不同季节珠江口水体总有机碳中的DOC一直高于POC。珠江口POC、DOC含量受到淡水与海水混合进程的影响,淡水与海水的混合效应可能是从出虎门进入伶仃洋的低盐度区(盐度1‰~5‰的水体)开始延伸至外海。微生物的降解作用可能对POC和DOC在出虎门之前的下降趋势产生了重要影响,而微生物对新鲜的浮游植物有机碳的利用、以及浮游植物生产量的降低和颗粒物絮凝沉降作用则可能是POC在出虎门后下降幅度大于DOC的重要原因。 相似文献
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为了解海洋中溶解态丙烯酸(AAd)的浓度分布及影响因素,本研究于2017年3～4月和2018年6～7月对黄东海海水中AAd进行了调查。结果表明:夏季黄东海表层海水中AAd的平均浓度((18.89±15.23) nmol·L~(-1))高于春季((13.94±9.89) nmol·L~(-1)),AAd存在明显的季节性差异。垂直分布上,P断面受长江冲淡水影响,陆源AAd的输入导致AAd含量高于B断面。春季黄东海表层海水及B断面的AAd与溶解态β-二甲基巯基丙酸内盐呈正相关性,这与AAd是β-二甲基巯基丙酸内盐的裂解产物有关。春季AAd的周日变化浓度范围是4.72～29.42 nmol·L~(-1),在18点出现最大值,与浮游动物摄食、光化学氧化及生源控制有关。春、夏季间隙水中AAd的浓度分别为30.89～131.57(平均:86.21±30.61)和5.75～84.86(平均:38.78±31.73)μmol·L~(-1),溶解有机碳(DOC)则为3.59～7.67和3.79～11.82 mg·L~(-1)。间隙水中AAd与二甲基硫(DMS)在春季存在负相关性,说明除了DMSPd的裂解,AAd还有其他的来源。研究海域沉积物间隙水中AAd的浓度比底层海水高出至少三个数量级,表明沉积物间隙水可能是底层海水中AAd的重要来源。 相似文献
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中国近海表层沉积物中氨基酸组成特征及生物地球化学意义 总被引：6，自引：2，他引：4
氨基酸是大多数生物体有机氮和有机碳的主要组分,也是近代沿海海洋沉积物有机质的重要组成部分[1]。海洋中生物残骸蛋白质在细胞破裂后,由微生物分泌的胞外酶和生物细胞残留的蛋白酶能将蛋白质水解成氨基酸,部分氨基酸被微生物作为营养物质吸收利用[2],残余蛋白质和氨基酸经过沉降作用进入沉积物,经历生物作用及成岩改造过程,以蛋白质、肽和水解氨基酸等地质聚合物形式存在,大部分与海洋沉积物结合紧密,少数以游离态存在[3]。因此,相对于常量的碳、氮化合物来说氨基酸通常不稳定,是水体颗粒物和沉积物中有机碳、氮循环的主要物质,也是次级生产者的主要营养物质[1]。 相似文献
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依据2017年8—9月对黄海海域溶解有机物(DOM)的调查,探讨了夏季黄海海水中溶解有机碳(DOC)和有色溶解有机物(CDOM)的空间分布特征。在表层海水中,受陆源影响较大的近岸海域CDOM含量相对较高,北黄海冷水团区域由于水产养殖的饵料引起DOC浓度升高,且该部分DOC以无色为主。DOC浓度随深度逐渐降低,而CDOM逐渐升高,该特征在冷水团区域更为显著,因此DOC和CDOM在冷水团区域的表底差异远大于浅水区的非冷水团区域。陆源输入和初级生产是引起表层DOC升高的主要原因,而光漂白则引起CDOM降低,同时光漂白还导致表层水体中CDOM分子量和芳香性低于底层。底层溶解氧饱和度在冷水团为80%～93%,均表现为弱不饱和状态。层化不仅阻碍了O2向底层水体输送,还抑制了DOC和CDOM的垂向混合,这是引起冷水团区域表底层DOC和CDOM差异较大的主要原因。 相似文献
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厦门湾沉积物间隙水中CDOM的荧光特性及其分布研究 总被引：1，自引：0，他引：1
研究了2003年4月从厦门湾九龙江口、西海域及同安湾采集的表层沉积物及柱状样间隙水中有色溶解有机物(CDOM)的荧光特性及其水平与垂直分布特征.结果表明,间隙水CDOM中均观测到类腐殖质与类色氨酸两类荧光.它们在表层沉积物间隙水中的相对含量均以九龙江口靠近浮宫红树林区的站位最高,同安湾及西海域养殖区各站位次之,分别反映了河口区红树林生态系以及养殖活动的影响;西海域靠近东渡码头的站位两类荧光的相对含量最低,系受疏浚活动影响所致.表层沉积物间隙水中两类荧光的相对含量均远高于底层水,暗示表层沉积物可成为上覆水体CDOM的一个重要来源.大多数站位间隙水中类腐殖质荧光的相对含量随深度增加而渐增,反映了CDOM在缺氧环境下的成岩作用过程.多数站位在3～6 cm深度处出现类色氨酸荧光峰值,随后递减,反映了近表层沉积物中细菌等微生物活动对蛋白质的降解作用. 相似文献
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胶州湾沉积物-海水界面硅的交换速率及其影响因素探讨 总被引：2，自引：1，他引：1
采用实验室培养法在原位温度和溶氧条件下测定了胶州湾沉积物-海水界面硅的交换速率,并探讨了相关环境因子对界面交换速率的影响机制。结果表明,胶州湾沉积物-海水界面硅的交换表现为从沉积物向水体释放,其交换速率在947~4 889 μmol/（m2·d）范围内,平均速率为1 819 μmol/（m2·d）。表层沉积物中叶绿素a（Chl a）和总有机碳（TOC）是影响胶州湾沉积物-海水界面硅交换速率的主要环境因子,同时表层沉积物的含水率（φ）、生源硅（BSi）和粘土含量以及间隙水中溶解硅酸盐（DSi）对沉积物-海水界面硅的交换也有重要影响。由此可推知,胶州湾沉积物-海水界面硅的交换速率主要受生物活动和溶解-扩散双重过程调控,而表层沉积物粒度与底层水体中DSi对胶州湾硅的释放影响较小。 相似文献
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深海沉积物和海水碳交换的同位素示踪Ｊ．Ｅ．Ｂａｎｅｒ等海洋沉积物含有较多的有机碳，对上覆水体中有机质的性质有一定的影响．普遍认为，海底沉积物可能是深层水中老而难已测定的溶解有机碳（ＤＯＣ）的来源；另外，放射性Ｃ同位素值（△１４Ｃ）和稳定Ｃ同位素比值（... 相似文献
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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
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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
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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
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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
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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
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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
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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
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《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