东亚边缘海区浮游植物春华的纬向与年际变化

Combined studies of latitudinal and interannual variations of annual phytoplankton bloom peak in East Asian marginal seas(17°–58°N, including the northern South China Sea(SCS), Kuroshio waters, the Sea of Japan and the Okhotsk Sea) are rarely. Based on satellite-retrieved ten-year(2003–2012) median timing of the annual Chlorophyll a concentration(Chl a) climax, here we report that this annual spring bloom peak generally delays from the SCS in January to the Okhotsk Sea in June at a rate of(21.20±2.86) km/d(decadal median±SD). Spring bloom is dominant feature of the phytoplankton annual cycle over these regions, except for the SCS which features winter bloom. The fluctuation of the annual peak timing is mainly within ±48 d departured from the decadal median peak date, therefore this period(the decadal median peak date ±48 d) is defined as annual spring bloom period. As sea surface temperature rises, earlier spring bloom peak timing but decreasing averaged Chl a biomass in the spring bloom period due to insufficient light is evident in the Okhotsk Sea from 2003 to 2012. For the rest of three study domains, there are no significant interannual variance trend of the peak timing and the averaged Chl a biomass. Furthermore this change of spring phytoplankton bloom timing and magnitude in the Okhotsk Sea challenges previous prediction that ocean warming would enhance algal productivity at high latitudes.     

Occurrence and exploration of gas hydrate in the marginal seas and continental margin of the Asia and Oceania region

Supplies of conventional natural gas and oil are declining fast worldwide, and therefore new, unconventional forms of energy resources are needed to meet the ever-increasing demand. Amongst the many different unconventional natural resources are gas hydrates, a solid, ice-like crystalline compound of methane and water formed under specific low temperature and high pressure conditions. Gas hydrates are believed to exist in large quantities worldwide in oceanic regions of continental margins, as well as associated with permafrost regions in the Arctic. Some studies to estimate the global abundance of gas hydrate suggest that the total volume of natural gas locked up in form of gas hydrates may exceed all known conventional natural gas reserves, although large uncertainties exist in these assessments. Gas hydrates have been intensively studied in the last two decades also due to connections between climate forcing (natural and/or anthropogenic) and the potential large volumes of methane trapped in gas hydrate accumulations. The presence of gas hydrate within unconsolidated sediments of the upper few hundred meters below seafloor may also pose a geo-hazard to conventional oil and gas production. Additionally, climate variability and associated changes in pressure-temperature regimes and thus shifts in the gas hydrate stability zone may cause the occurrence of submarine slope failures.Several large-scale national gas hydrate programs exist especially in countries such as Japan, Korea, Taiwan, China, India, and New Zealand, where large demands of energy cannot be met by domestic supplies from natural resources. The past five years have seen several dedicated deep drilling expeditions and other scientific studies conducted throughout Asia and Oceania to understand gas hydrates off India, China, and Korea. This thematic set of publications is dedicated to summarize the most recent findings and results of geo-scientific studies of gas hydrates in the marginal seas and continental margin of the Asia, and Oceania region.     

Occurrence and exploration of gas hydrate in the marginal seas and continental margin of the Asia and Oceania region

Supplies of conventional natural gas and oil are declining fast worldwide, and therefore new, unconventional forms of energy resources are needed to meet the ever-increasing demand. Amongst the many different unconventional natural resources are gas hydrates, a solid, ice-like crystalline compound of methane and water formed under specific low temperature and high pressure conditions. Gas hydrates are believed to exist in large quantities worldwide in oceanic regions of continental margins, as well as associated with permafrost regions in the Arctic. Some studies to estimate the global abundance of gas hydrate suggest that the total volume of natural gas locked up in form of gas hydrates may exceed all known conventional natural gas reserves, although large uncertainties exist in these assessments. Gas hydrates have been intensively studied in the last two decades also due to connections between climate forcing (natural and/or anthropogenic) and the potential large volumes of methane trapped in gas hydrate accumulations. The presence of gas hydrate within unconsolidated sediments of the upper few hundred meters below seafloor may also pose a geo-hazard to conventional oil and gas production. Additionally, climate variability and associated changes in pressure-temperature regimes and thus shifts in the gas hydrate stability zone may cause the occurrence of submarine slope failures.Several large-scale national gas hydrate programs exist especially in countries such as Japan, Korea, Taiwan, China, India, and New Zealand, where large demands of energy cannot be met by domestic supplies from natural resources. The past five years have seen several dedicated deep drilling expeditions and other scientific studies conducted throughout Asia and Oceania to understand gas hydrates off India, China, and Korea. This thematic set of publications is dedicated to summarize the most recent findings and results of geo-scientific studies of gas hydrates in the marginal seas and continental margin of the Asia, and Oceania region.     

东亚海区的海岸带综合管理经验:从地方性示范到区域性合作

本文阐述了东亚海区海岸带综合管理实践如何从地方性的示范发展到区域性的合作管理框架，如何实现海洋和海岸带资源的可持续利用．文中着重突出了厦门市政府在维持环境保护和经济发展的平衡，启动和实施海岸带综合管理，以及与沿海国在国际合作方面的经验，总结了厦门实施海岸带综合管理的主要经验，包括多部门间综合协调机制、海岸带综合管理法律框架、科技支撑体系的建立，海洋功能区划、环境剖面和战略环境管理计划的制定，以及实现海上联合执法等等．同时阐述了东亚海域环境管理区域合作计划（PEMSEA）与澳大利亚合作伙伴之间的关系在推动沿海城市的国际合作中将起到的作用．     

Influence of particle composition on thorium scavenging in the marginal China seas

Thorium-234 and particle composition (organic matter, biogenic silica, carbonate and lithogenic component) were examined in the East China Sea (ECS) and the northern South China Sea (NSCS) in order to constrain the particle types scavenging thorium isotopes. Good positive correlations between particulate organic matter (POM) or carbonate and thorium-234 in suspended particulate matter (SPM) indicates that POM and carbonate are efficient to scavenge thorium-234. No relationship between biogenic silica and thorium-234 suggests that geochemical behavior of thorium-234 may be not influenced by biogenic silica. A simple model was used to evaluate the affinity of thorium-234 to different particle components. The results show that POM is the most efficient scavenger for thorium-234 in the ECS and the NSCS, followed by carbonate. The authors'' results lend support to the utility of thorium-234 as a proxy of POC and carbonate in the upper layer. However, the strong dependence of thorium scavenging on particle composition challenges thorium-230 as a constant flux proxy.     

Noble metals in ferromanganese crusts from marginal seas of the Northwest Pacific

Based on data on the concentration of noble metals (Au, Ag, Pt, Os, Ir, and Ru) in bulk samples of ferromanganese crusts, the presence of inclusions of micro- and nanosized grains of Ag, Au, Pd, and Pt, often with impurities of other elements, as well as their chaotic distribution, three sources of incorporation of these metals into ore crusts of Far Eastern seas are suggested: seawater, postvolcanic gas–hydrothermal fluids, and hydrothermal plumes. The presence of grains of platinoids and gold in ferromanganese crusts on only some mounts may result from peculiarities in the formation of volcanic rocks on the ancient continental basement.     

Microbiological analysis of the contamination of marginal seas in the northwestern part of the Pacific Ocean

A comparative study of the abundance of microorganisms of different environmental and trophic groups in the seawater of several aquatic areas of Far Eastern seas under the conditions of integrated organic contamination was carried out. It was shown that, although marine microorganisms are characterized by polyresistance to a great variety of contaminants, their responses are individual for each of the kinds of pollutants. By the results of microbial indication, the environmental quality in the areas of the greatest ecological stresses at the Pacific Ocean coasts was estimated. These areas were the coasts of Sakhalin Island in the oil production region, the Kamchatka Peninsula in the Avacha Bay region, the southern Primor’e within the impact zone of the Tumannaya River runoff, and Zolotoi Rog Bight located in the central part of the city of Vladivostok. On the basis of the data concerning the microbial indication of the contamination of the aquatic areas studied with oil hydrocarbons, phenols, and nutrients, the applicability of this method to the express estimation of the quality of coastal seawaters and to the short-term forecast of the changes that proceed under the complicated organic contamination was demonstrated.     

Influence of the White Sea on tides in adjacent marginal seas of the North European Basin

An investigation into the interaction of surface M ₂ tides in the system of marginal seas of the North European Basin is carried out using the three-dimensional finite-element hydrostatic model QUODDY-4. Three numerical experiments are performed for this purpose. In the first (control), the model equations are solved in the system of the Norwegian, Greenland, Barents, and White seas; thereby the interaction of the tides in these seas is explicitly taken into account. In the second experiment, the White Sea is excluded from consideration and the no-flux condition is posed at the entrance to the sea. The third experiment uses an approach in which the observed tidal elevations that determine the existence of a finite horizontal transport of barotropic energy to the White Sea are specified at the open boundary of the White Sea. It is shown that changes in tidal dynamics represented by changes in the amplitudes and phases of tidal elevations and in the barotropic tidal velocity ellipse parameters are within the model noise in experiments 2 and 3 when compared with the control experiment. On the contrary, changes in energy characteristics (the horizontal wave transport, density, and dissipation rate of barotropic tidal energy) are equal to or greater (in order of magnitude) than the energy characteristics themselves.     

Along-coast shifts of plankton blooms driven by riverine inputs of nutrients and fresh water onto the coastal shelf: a model simulation

Rivers transport nutrients and suspended sediment matter (SSM) as well as fresh water from land to coastal regions, where the biological productivity is high. In the coastal area, the buoyancy of fresh water leads to the formation of horizontal anticyclonic gyres and vertical circulations, which affect the variation of biological production such as plankton blooms. However, the primary production caused by the 3-D dynamics have not been quantitatively discussed, and observations can hardly capture the daily temporal variations of phytoplankton blooms. We developed an ocean general circulation model including a simple ecosystem model, to investigate the 3-D and temporal changes in phytoplankton blooms caused by riverine input such as flooding. The distribution patterns of nutrients and phytoplankton differ significantly from that of fresh water. The phytoplankton maxima shift from the downstream (right-hand side of the river mouth) to the upstream regions (left-hand side of the river mouth). The shift that occurs is categorized by the different nitrate origins: (1) river-originated nitrate is dominant in the downstream region; (2) subsurface-originated nitrate is dominant in the upstream region, and is transported by upwelling associated with vertical circulation and horizontal anticyclonic gyre; and (3) regenerated nitrate is dominant in the upstream region. The total primary production in phytoplankton blooms is maintained not only by river-originated nitrate but also by subsurface-originated nitrate that is 1.5 times larger than the river-originated. Several case studies (e.g., including SSM) were conducted in this study.     

Comparison of anchovy biomass estimates measured by trawls,egg production methods and hydro-acoustics in the Chesapeake Bay and the Korea Strait

We compared estimates of anchovy biomass derived from trawl surveys, egg production method (EPM) and acoustic surveys, conducted in two remote regions. Biomass density of bay anchovy Anchoa mitchilli was estimated in Chesapeake Bay, USA, by trawls, EPM and acoustics from 1989 to 2000. Biomass density of Pacific anchovy Engraulis japonicus was estimated in the Korea Strait using EPM, simulation-based daily cohort analysis and acoustics from 1984 to 2006. Most of the existing estimates already had considered body-size-dependent gear selectivity, highlyvariable instantaneous natural mortality of anchovy eggs, and avoidance of trawl nets by adult anchovy. Despite great variability in the ratio of trawl to acoustic biomass estimates (0.034–8.35), annually-averaged biomass density of young-ofthe-year individuals derived by the two methods were similar for bay anchovy in Chesapeake Bay and Pacific anchovy in the Korea Strait (0.83 and 0.70 g m^?3, respectively). Results suggested that, despite substantial uncertainty, anchovy biomass estimates are generally compatible between EPM and acoustics. However, reported estimates of biomass density derived from the two acoustic surveys in the Korea Strait differed by a factor of 28, suggesting that further improvements in calibrations are required to reliably estimate anchovy biomass. The comparisons suggested that all biomass estimates could be biased and will require comparison and validation by other, independent sampling methods.     

The three-layer model of the thermohaline structure in the shallow seas

——A three-layer model of the thermohaline structure is developed on the basis of the two -layer model of thermocline. The model is able to simulate the depth,thickness and intensity of both thermocline and halocline, and the temperature and salinity of both upper layer and lower layer in the shallow seas.Camparison of simulation with data is favorable.Detailed analysis is made on a variety of factors affecting the intensity of the thermocline.     

Assimilation of sea surface temperature in the Northwest Pacific Ocean and its marginal seas using the ensemble Kalman filter

Satellite-borne sea surface temperature (SST) data were assimilated with the ensemble Kalman filter (EnKF) in a Northwest Pacific Ocean circulation model to examine the effect of data assimilation. The model domain included the northwestern part of the Pacific Ocean and its marginal seas, such as the Yellow Sea and East/Japan Sea. The performance of the data assimilation was evaluated by comparing the simulated ocean state with that observed. Spatially averaged root-mean-squared errors in the SST and sea surface height (SSH) decreased by 0.44 °C and 4 cm, respectively, by the assimilation. The results of the numerical experiments substantiated the effectiveness of the SST assimilation via the EnKF for all marginal seas, as well as the Kuroshio region. The benefit of the data assimilation depended on the characteristics of each marginal sea. The variation of the SST in the East/Japan Sea and the Kuroshio extension (KE) region were improved 34% and those in the Yellow Sea 12.5%. The variation of the SSH was improved approximately 36% in the KE region. This large improvement was achieved in the deep-water regions because assimilation of SST data corrected the separation point of the western boundary currents, such as the Kuroshio and the East Korea Warm Current, and the associated horizontal surface currents. The SST assimilation via the EnKF also improved the subsurface temperature profiles. The effectiveness of SST assimilation was seasonally dependent, with the improvement being relatively larger in winter than in summer, which was related to the seasonal variation of the vertical mixing and stratification in the ocean surface layer.     

Temporal variations and trends of CFC11 and CFC12 surface-water saturations in Antarctic marginal seas: Results of a regional ocean circulation model

The knowledge of chlorofluorocarbon (CFC11, CFC12) concentrations in ocean surface waters is a prerequisite for deriving formation rates of, and water mass ages in, deep and bottom waters on the basis of CFC data. In the Antarctic coastal region, surface-layer data are sparse in time and space, primarily due to the limited accessibility of the region. To help filling this gap, we carried out CFC simulations using a regional ocean general circulation model (OGCM) for the Southern Ocean, which includes the ocean–ice shelf interaction. The simulated surface layer saturations, i.e. the actual surface concentrations relative to solubility-equilibrium values, are verified against available observations. The CFC surface saturations driven by concentration gradients between atmosphere and ocean are controlled mainly by the sea ice cover, sea surface temperature, and salinity. However, no uniform explanation exists for the controlling mechanisms. Here, we present simulated long-term trends and seasonal variations of surface-layer saturation at Southern Ocean deep and bottom water formation sites and other key regions, and we discuss differences between these regions. The amplitudes of the seasonal saturation cycle vary from 22% to 66% and their long-term trends range from 0.1%/year to 0.9%/year. The seasonal surface saturation maximum lags the ice cover minimum by two months. By utilizing observed bottle data the full seasonal CFC saturation cycle can be determined offering the possibility to predict long-term trends in the future. We show that ignoring the trends and using instead the saturations actually observed can lead to systematic errors in deduced inventory-based formation rates by up to 10% and suggest an erroneous decline with time.     

东海南部海洋净初级生产力与鲐鱼资源量变动关系的研究

海洋初级生产力决定海洋渔业资源的潜在产量,我国应用海洋初级生产力方法估算渔业资源量亦已取得不少研究成果,但海洋生态系统中的营养控制机制复杂多样,将影响海洋初级生产力与鱼类资源量的关系。本文利用中国大型灯光围网渔业在东海南部渔场的鲐鱼(Scomber japonicus)捕捞数据与海洋净初级生产力的遥感资料分析了鲐鱼资源量变化与净初级生产力的关系,探讨了其生态系统营养控制机制。研究结果表明,净初级生产力与标准化CPUE(Catch Per Unit Effort)不存在显著的线性关系(P>0.05),但呈显著非线性关系(P<0.05),且这种非线性关系表现为倒抛物线,即鲐鱼资源量随净初级生产力的增加而提高,但当净初级生产力进一步增加,鲐鱼资源量则呈下降趋势。净初级生产力与标准化CPUE呈显著的倒抛物线关系表明生态系统存在上行控制机制,但并非受该机制完全控制。种间竞争或浮游动物资源量的变动均可能引起鲐鱼资源的相对丰度与净初级生产力呈倒抛物线关系。     

基于DPSIR模型和耦合协调度模型的胶州湾海域承载力分析

海域承载力是海洋资源利用协调发展的重要指标,本研究旨在根据胶州湾海域资源特征,基于DPSIR模型构建海域承载力评价指标体系,运用熵值法评价2000—2020年胶州湾海域承载力,并运用耦合协调度模型分析胶州湾海域承载力子系统内部的耦合协调度。结果表明,2000—2020年胶州湾海域承载力和耦合协调度变化幅度范围分别为0.70~0.95和0.73~0.85。研究结论如下:1)2000—2020年胶州湾海域承载力处于强可载、近满载状态,总体呈降低趋势;2)在压力层中的对海洋资源的需求是影响海域承载力的主要因素,而GDP (Gross Domestic Product)增长率、海洋渔船数和海洋渔船功率、人均滩涂面积和人均用海面积、主要海洋产业增加值年增长率、人工增殖放流则分别是影响驱动力层、压力层、状态层、影响层、响应层的主要因素;3)2000—2020年间胶州湾海域承载力整体耦合协调度总体呈“初级协调至良好协调”态势。     

冷扩散法提取沉积物中的酸可溶硫化物及其在中国边缘海区的应用

为了快速而有效地对中国边缘海区沉积物中的酸可溶硫化物(AVS)进行研究,冷扩散法被引入。用冷扩散法提取不同体积硫化物溶液中的AVS,所得到的AVS含量与所加溶液体积的相关性较好,说明此方法具有较好的提取效果。在中国边缘海不同典型海域的浅表层沉积物中,利用冷扩散法对AVS进行了分析:胶州湾李村河口AVS的浓度在0.4~120.1μmol/g之间;南黄海西北部陆架在0~11.1μmol/g之间;南海北部陆坡一柱状样沉积物中多数样品<1μmol/g。结果显示不同典型海域沉积物中AVS的分布差别较大,符合不同环境沉积物中AVS含量的一般规律。因此冷扩散法作为一种有效的AVS提取方法,值得在研究中使用与推广。     

东海风应力旋度驱动的21天周期的海底压力变化及其传播

在2015年6月至2017年6月期间,跨越庆良间水道的由2台加载压力传感器的倒置式回声仪（PIES）和5台加载压力传感器和海流计的倒置式回声仪（CPIES）组成的观测断面获得了近2年的海底压力时间序列。该时间序列中存在着显著的21天周期的振荡（P_bot21）,该信号在2016年7月至10月期间尤为强烈。P_bot21与东海陆架上的风应力旋度存在较显著的3天延迟相关,其相关系数达到0.65。本文采用正压海洋模式解释了这一信号的产生、传播以及耗散过程,模式结果显示东海陆架上的风应力旋度驱动产生P_bot21并向琉球岛链传播,而深海上的风应力旋度不能驱动产生这一信号。在陆架上,P_bot21伴随21天周期的风应力旋度由海岸向东南方向传播,但由于摩擦作用,信号在离开风场后几天内即耗散。断面能否观测到P_bot21与陆架上21天周期风应力旋度场的分布相关,长江口东南方向风应力旋度驱动的P_bot21能被观测到,而长江口东北方向产生的P_bot21不能被观测到。     

基于构造-流体耦合约束的变速成图方法及其在东海A气田挖潜阶段的成功应用

时深转换是构造解释关键步骤之一,时深转换方法主要包括常速成图与变速成图两大类。常速成图操作简单,应用普遍,但不适合速度场横向变化剧烈的工区。建立一种适应速度场横向变化且符合工区地质及油气藏特征的时深转换方法,是本研究探讨的重点。迭代变速成图技术基于叠加速度反演,综合了流体检测成果,通过不断优化速度场开展变速成图,能较准确地预测地下复杂构造的深度,该方法刻画的构造油气藏含气范围与流体检测分布一致,实现了同一油气藏的分布在不同地震信息维度下的耦合。利用迭代变速成图技术,较好解决了A气田钻前构造气藏面积与“亮点”展布范围之间的矛盾,统一了地质油藏认识,扩大了地质储量,有效推动了A气田的挖潜与调整,实现了增储上产。