基于B-L曲线的河-海划界研究

入海河口是河流向海洋过渡的区域,作为海岸带的一部分,具有独特性与复杂性,基于岸线形态的海岸地貌学指标与众多河口参数具有密切的联系与影响,而以地形节点作为河-海划界方案具备可行性与可操作性。在河流中心线上某点处,定义河流宽度(B)和沿河流中心线到口门处距离(L)的B=f(L)函数来实现河-海划界的定量划分,并对不同类型河口使用该函数曲线寻找地形节点进行河-海划界。结果表明:沙坝或堵塞型河口其地形节点处的河流展宽速率在-0.5~0之间;河道状河口及河网状三角洲其地形节点处的河流展宽速率在0.5~1.2之间;河口湾型河口的地形节点处的河流展宽速率在0.6~1.5之间;喇叭形三角洲河口其地形节点处的河流展宽速率在1.3~4.5之间;鸟足状三角洲和扇形三角洲的入海河口段的河流展宽速率在0~0.2之间,建议以口门处作为地形节点。应用此方法对我国大陆入海河流进行河-海划界,并进行中国大陆河口岸线长度量算,取得良好效果。     

大洋火山玻璃的蚀变：微生物活动的结构证据

在陆地和大洋中均已发现微生物生活在沉积物、沉积岩和火山岩之中。在大洋热液泉口微生物和微生物产物非常丰富,被认为是在海底下发现的喜温和喜高温微生物群落的代表。我们的先期研究支持这种假说：微生物参入了大洋火山壳的矿物转换、地壳的元素提取以及地壳中元素的沉...     

2017年春季长江口-东海连续体pCO2的空间分布特征及其控制因素

厘清河口-陆架连续体的碳源/汇机制是认识海洋在“碳中和”中作用的重要基础。本研究基于2017年春季长江口-东海的走航CO2分压(pCO2)及温、盐等资料,分区域阐述春季长江口-东海连续体pCO2的空间分布格局,半定量解析水团分配、有机质生产及降解等过程对pCO2的控制作用。结果表明：水团来源是决定春季长江口-东海连续体pCO2分布及碳源/汇格局的主要因素,而有机质生产或者降解可强烈影响长江口-东海连续体碳源/汇格局。春季长江口门及浙江沿岸受长江径流影响而具有较高的pCO2,碳源强度可达5.36mmol·m-2·d-1;研究区域北部和东部分别受冲淡水及黑潮表层水的影响,表现为大气碳汇,北部碳汇强度为-15.44mmol·m-2·d-1。2017年春季研究区域平均碳通量为-6.73mmol·m-2·d-1。端元混合模型结果表明陆源有机质降解导致河口pCO2增加了约200μatm,促使春季河口由大气CO2的弱汇转变为碳源;陆架区域在仅考虑水团分配下同样为碳汇,而藻华过程进一步降低了pCO2(下降144μatm),增强了其碳汇能力。     

海洋大气化学及其观测工程技术展望

海洋大气化学是一门海洋化学与大气化学交叉的新兴学科,是研究海洋大气中化学物种(Chemical Species)含量、迁移变化、来源辨别及海气交换通量,以及预估人为和自然影响对全球气候变化和区域海洋生态系统影响的科学。海洋大气化学的进步也得益于海-气系统观测体系建设及其工程技术的创新,其中包括对微量要素的测量、复杂形态的辨别和原位探测等技术的突破。我国的海洋大气化学研究起步于20世纪80年代,通过中国沿海观察站、近海和大洋走航线和断面站以及南北极建立考察站等的立体观测平台,针对海洋大气化学关键过程即大气-海洋生物地球化学循环,开展碳、氮、硫、磷、铁等的迁移变化及其海气通量的观测。在碳、氮的海-气循环及海洋酸化机制,硫的海-气交换的气粒转化及气候效应等研究领域,取得了一批新的认知和引起国际学界关注的成果,促进了学科进步,建成了一个从近岸、大洋到极区的立体观测体系。     

从河口发育过程探讨河海界线

当河口三角洲逐渐向海洋伸展时,必定会对河口附近的海洋进行改造,从而改变口外海滨某些海洋要素,据此可作为河海界线的判断标准,即在常态状况下,某些要素的改变,是否已经改变了口外海滨本来的属性,如果已经改变,应界定为河流,如仍以海洋属性(包括动力、海水理化性质、沉积、地形等)为主,则仍界定为海洋.河口是河流和海洋相互连接的枢纽地带,在这里主要动力有径流(河流属性)、潮汐、海流和波浪(海洋属性)等.在它们的作用下,通过泥沙运移,塑造各种地貌形态,反过来,地貌形态又改变了水动力的属性.从河口地貌学的角度,河口可以分为3部分,即近口段、河口段和口外海滨段.近口段是在原来的口外海滨或河口段,经历三角洲外伸,沙洲并岸,河槽束狭,河槽成型、加深等阶段,逐渐形成的.从近口段的演化过程看出,该段属于河流.口外海滨段虽然受到河流影响,但是其仍然表现为海洋属性,因此,属于海洋无可置疑.河口段介于近口段和口外海滨段之间,该区段受径流和潮流的共同作用而造成自然要素的不连续,这种不连续表现在河口形态,底床形态,潮汐特征,水团(盐度、絮凝体)、浊度及沉积物特性等方面.河口形态的变化比较直观.潮波从外海传入河口口门后,因受到地形的影响而改变,包括潮汐性质、潮差,甚至变形破碎形成涌潮.所以在河海界线上,潮波变形造成的最大潮差、最大流速、乃至潮波破碎形成涌潮的位置具有一定意义.河口段存在最大浊度带,其内界与最大絮凝体位置相当.根据我国现行定义的海陆界线为平均大潮高潮位线,从平面上看河海界线时,沉积相是一个重要指标,即只有出现三角洲平原相时,才说明河口对海洋改造已基本完成.     

珠江广州至虎门段水体中的营养盐

河流和海洋虽是两个不同的体系,但有紧密的联系,两者的相互作用和交换集中表现在河口区域。海洋水体中的溶解态和悬浮态营养盐主要来自河流。在大洋中,由于近表层浮游植物的光合作用的吸收,上、下水层交换缓慢,造成营养盐的分层现象。通常上层含量贫乏,底层富足,相差可达几十倍。而河流则是另一种变化类型。河流水浅,水体含有较多泥沙,加之上、下水层的涡动作用而容易交换,以及水的搅动而混浊,沉积物的再悬浮,致使水体透明度极低,不利于浮游植物的繁殖,因此,上、下水层营养盐含量差别极小。河流所含丰富的营养盐流入海洋后,成为海洋初级生产力的基础,是形成渔场的基本条件之一。     

近100 Ma以来海平面变化机制

海平面变化不仅关系到全球环境的演变,而且与人类社会的发展有着极其密切的关系。关于海平面变化的机制研究与精确估算则一直以来是海洋学研究的重点方向之一。通过分析晚中生代以来全球海平面变化记录,在行星尺度和地球轨道尺度上,分析讨论了海平面变化的主要影响机制。结果显示:虽然近100Ma以来,海平面记录中构造和大洋碳储库周期连续小波分析信号显著,其滤波振幅强度变化也对应了全球性的构造、气候及生物演变事件,反映了由构造运动引起的海-陆格局变化、气候突变以及相应的生物演变事件等全球性变化对海平面变化的影响。但在南极冰盖形成之后,构造周期与大洋碳储库周期的影响对海平面变化的影响出现不同,特别是近5Ma以来两者出现相反的变化趋势;近10Ma以来,偏心率周期、斜率周期和岁差周期分别在约0.8、5.3及6.2Ma之后对海平面变化的影响开始增强,显示出不同地球轨道参数周期对海平面变化影响存在一定的时间差异。而在这一阶段,虽然极地冰盖体积变化与海平面变化的相关性最为显著,但是,海平面变化可能受到地球轨道参数变化引起的高纬度地区冰盖体积变化与低纬度季风演化引起的大洋碳储库变化等因素的共同影响。     

闽江下游及河口沉积物总碳的地球化学特征

分析了闽江下游及河口区的表层水质、悬浮物和沉积物样品,探讨了沉积物总碳的地球化学特征和影响因素,及与其他河流的异同.结果表明,对于相同站位,夏季沉积物总碳占比平均为1.74%,略高于秋季的1.70%,两者差异不明显.研究区沉积物总碳占比为1.21%~4.84%,平均为1.82%,从水口水库至福州市区河段,其含量逐渐升高,在北港达到最高值,而后由河口向外海逐渐降低,呈现"低-高-低"的分布特征.秋季悬浮物含量和化学需氧量(COD)高值区范围大于夏季,且含量也更高.研究区悬浮物含量、COD、颗粒态总碳均呈现先升后降的分布特征,悬浮物中总碳的含量则呈现从库区经河口向外海减少的趋势.沉积物总碳与悬浮物总碳、悬浮物含量、COD总体显著相关,悬浮物的沉降-再悬浮-再沉降过程是影响沉积物总碳分布的重要因素;人类活动产生的污水、农田和畜禽水产养殖废物是有机物的主要来源.闽江口沉积物总碳含量低于黄河、长江,而与其他中小型河口相近,处于国内河口较低水平,这与流域内源岩特性、有机物输入量以及沉积物粒度等相关.北港段沉积物总碳含量显著高于其他河流,有机污染较为严重,将成为影响水体水质的潜在因素.     

长江口生物硅的组成、行为和收支

基于在长江口开展的三个综合航次对河口生物硅组成、行为和收支进行了研究。结果表明，长江口生物硅主要是由植硅体、硅藻和海绵骨针三部分组成，其中植硅体有16种形态，在高混浊区对生物硅的贡献量为23%-83%。收支计算显示，长江输送的生物硅是河口区获取外部生物硅的主要途径，占河口生物硅总输入量的95%；维持河口生物硅水平的主要过程是初级生产（55 Gmol a^-1）和沉积过程（46 Gmol a^-1）；初级生产所贡献的生物硅分别是长江生物硅输送量的2.3倍和河口区向外输送生物硅的63%。从河口区向东海和黄海输送的生物硅是26 Gmol a^-1，与长江的生物硅输送量相当；河口区沉积的生物硅是向外输送量的1.7倍，在其中植硅体贡献了53%至88%的生物硅，表明河口是陆源生物硅汇的作用；反风化作用也是河口活性硅去除的一个重要途径。本研究显示植硅体是河口生物硅的重要组成部分，长江口在生物硅收支与循环中表现出汇的作用。     

长江口营养盐(N,P,Si)分布与变化特征

河口区是河流和海洋的交汇处,是化学元素和有机物质同沉积物交换最激烈的场所。研究河口营养盐(N,P,Si)不仅可了解河流的输出物质,而且还同了解邻近海域及世界大洋的化学组成、变化、平衡等都有密切的关系。因此,对河口N,P,Si的研究已愈益受到重视,成为河口研究的基础工作。一、实验站位布设 1980年6月9—17日,在长江口海域(121°50′-122°30′E,30°55′-31°45′N)布设了14个测站(图1a),其中P8001,P8002,P8003,P8010和P8008等为时间系列,其余各站为大面观测站。     

Oceanic iron fertilization: one of strategies for sequestration atmospheric CO2

Carbon cycle is connected with the most important environmental issue of Global Change.As one of the major carbon reservoirs, oceans play an important part in the carbon cycle. In recent years, iron seems to give us a good news that oceanic iron fertilization could stimulate biological productivity as CO2 sink of human-produced CO2. Oceanic iron fertilization experiments have verified that adding iron into high nutrient low chlorophyll (HNLC) seawaters can increase phytoplankton production and export organic carbon, and hence increase carbon sink of anthropogenic CO2, to reduce global warming. In sixty days, the export organic carbon could reach 10 000 times for adding iron by model prediction and in situ experiment, i.e. the atmospheric CO2 uptake and inorganic carbon drawdown in upper seawaters also have the same magnitude. Therefore, oceanic iron fertilization is one of the strategies for increasing carbon sink of anthropogenic CO2. The paper is focused on the iron fertilization, especially in situ o     

白垩纪黑色页岩与大洋红层:缺氧到富氧的过程与机制

白垩纪是地球历史中一个重要的阶段,期间发生了以黑色页岩为特征的缺氧事件和以大洋红层为特征的富氧环境等许多重大地质事件,从白垩纪大洋缺氧到富氧转化的过程与机制,提出上述两个典型事件是同一原因形成的两个不同结果。一方面,白垩纪大规模的岩浆活动,引起大气中CO2气体浓度的升高和地球内部大量热能释放,并且改变了海陆面积的对比,最终导致大气温度的升高。海水温度的升高和CO2浓度的增加导致海洋环境中溶解O2的降低,缺氧事件随之而产生。另一方面,剧烈的岩浆活动在海底产生大量的富含铁元素的基性和超基性岩,在与海水发生反应时,岩石中的铁元素进入海水中。海水中的铁元素是海洋浮游植物宝贵的营养盐类,其含量的增加可激发浮游植物的大规模繁盛,而这一生命过程可以吸收海水中大量的CO2,并且产生等量的O2。随着海水中O2浓度的不断升高,以富含Fe3 的红色沉积物为特征的海洋富氧环境出现。然而,由岩浆活动引起的缺氧事件和同样由其造成的富氧环境,其机制存在明显的差异,前者以物理、化学过程为主,后者除此之外还演绎了更为复杂的生物—海洋地球化学过程。     

Enhancement/reduction of biological pump depends on ocean circulation in the sea-ice reduction regions of the Arctic Ocean

The biological pump is a central process in the ocean carbon cycle, and is a key factor controlling atmospheric carbon dioxide (CO₂). However, whether the Arctic biological pump is enhanced or reduced by the recent loss of sea ice is still unclear. We examined if the effect was dependent on ocean circulation. Melting of sea ice can both enhance and reduce the biological pump in the Arctic Ocean, depending on ocean circulation. The biological pump is reduced within the Beaufort Gyre in the Canada Basin because freshwater accumulation within the gyre limits nutrient supply from deep layers and shelves hence inhibits the growth of large-bodied phytoplankton. Conversely, the biological pump is enhanced outside the Beaufort Gyre in the western Arctic Ocean because of nutrient supply from shelves and greater light penetration, enhancing photosynthesis, caused by the sea ice loss. The biological pump could also be enhanced by sea ice loss in the Eurasian Basin, where uplifted isohaline surfaces associated with the Transpolar Drift supply nutrients upwards from deep layers. New data on nitrate uptake rates are consistent with the pattern of enhancement and reduction of the Arctic biological pump. Our estimates indicate that the enhanced biological pump can be as large as that in other oceans when the sea ice disappears. Contrary to a recent conclusion based on data from the Canada Basin alone, our study suggests that the biological CO₂ drawdown is important for the Arctic Ocean carbon sink under ice-free conditions.     

The importance of estimating the contribution of the oceans to national economies

The oceans are in trouble. Poorly understood and unprecedented environmental and economic changes are underway in our world's oceans that will significantly affect life in the sea as well as on land. Only in the last thirty years has the contribution of the ocean sector to the economy been measured. An examination of these studies has exposed definitional, conceptual and methodological differences in measuring marine-related economic activity in the economy, making comparisons difficult. Both the ocean and the coastal economies face a world of volatile changes. In the ocean economy marine transport faces unpredictable fuel costs. Coastal tourism also faces losses from climate change impacts and sea level rise. Finally, a warming ocean and increasing acidification of the oceans from greenhouse gases is already affecting coral reefs and a range of fish stocks. Economic measures are important to predict these impacts, as are economic measures of the resilience of different areas of the ocean and coastal economies. This article demonstrates how knowledge of both the ocean, coastal and national economies can help governments address the future impacts and demands posed by nature and human populations on our coasts and oceans.     

Assessing the apparent imbalance between geochemical and biochemical indicators of meso- and bathypelagic biological activity: What the @$♯! is wrong with present calculations of carbon budgets?

Metabolic activity in the water column below the euphotic zone is ultimately fuelled by the vertical flux of organic material from the surface. Over time, the deep ocean is presumably at steady state, with sources and sinks balanced. But recently compiled global budgets and intensive local field studies suggest that estimates of metabolic activity in the dark ocean exceed the influx of organic substrates. This imbalance indicates either the existence of unaccounted sources of organic carbon or that metabolic activity in the dark ocean is being over-estimated. Budgets of organic carbon flux and metabolic activity in the dark ocean have uncertainties associated with environmental variability, measurement capabilities, conversion parameters, and processes that are not well sampled. We present these issues and quantify associated uncertainties where possible, using a Monte Carlo analysis of a published data set to determine the probability that the imbalance can be explained purely by uncertainties in measurements and conversion factors. A sensitivity analysis demonstrates that the bacterial growth efficiencies and assumed cell carbon contents have the greatest effects on the magnitude of the carbon imbalance. Two poorly quantified sources, lateral advection of particles and a population of slowly settling particles, are discussed as providing a means of closing regional carbon budgets. Finally, we make recommendations concerning future research directions to reduce important uncertainties and allow a better determination of the magnitude and causes of the unbalanced carbon budgets.     

二氧化碳海洋倾废的研究进展

简要回顾了二氧化碳深海倾废设想提出的背景及其理论依据,阐述了实施二氧化碳深海倾废的可行性,着重讨论了CO2在深海的水合化过程以及最新的现场实验结果。分析了CO2海洋倾废对深海环境和生态系统的潜在影响。在与其他二氧化碳倾废方式进行比较的基础上,对今后的发展进行了展望。     

Species‐specific photosynthetic responses of symbiotic zoanthids to thermal stress and ocean acidification

Increasing sea‐surface temperatures and ocean acidification (OA) are impacting physiologic processes in a variety of marine organisms. Many sea anemones, corals and jellies in the phylum Cnidaria form endosymbiotic relationships with Symbiodinium spp. (phylum Dinoflagellata) supply the hosts with fixed carbon from photosynthesis. Much work has focused on the generally negative effects of rising temperature and OA on calcification in Symbiodinium‐coral symbioses, but has not directly measured symbiont photosynthesis in hospite or fixed carbon translocation from symbiont to host. Symbiodinium species or types vary in their environmental tolerance and photosynthetic capacity; therefore, primary production in symbiotic associations can vary with symbiont type. However, symbiont type has not been identified in a large portion of Symbiodinium?cnidarian studies. Future climate conditions and OA may favor non‐calcifying, soft‐bodied cnidarians, including zoanthids. Here we show that two zoanthid species, Palythoa sp. and Zoanthus sp., harboring different symbiont types (C1 and A4), had very different responses to increased temperature and increased partial pressure of CO₂ (pCO₂), or dissolved CO₂, and low pH. Thermal stress did not affect carbon fixation or fixed carbon translocation in the Zoanthus sp./A4 association, and high pCO₂/low pH increased carbon fixation. In contrast, both thermal stress and high pCO₂/low pH greatly inhibited carbon fixation in the Palythoa sp./C1 association. However, the combined treatment of high temperature and high pCO₂ increased carbon fixation relative to the treatment of high temperature alone. Our observations support the growing body of evidence that demonstrates that the response of symbiotic cnidarians to thermal stress and OA must be considered on a host‐specific and symbiont‐specific basis. In addition, we show that the effects of increased temperature and pCO₂ on photosynthesis may change when these two stressors are combined. Understanding how carbon fixation and translocation varies among different host?symbiont combinations is critical to predicting which Symbiodinium associations may persist in warm, acidified oceans.     

Evaluation of the ocean governance system in Korea

Considering the small land, dense population and poor natural resources, the oceans are important to Korea, but the recognition of oceans has been weak in Korean society. So ocean governance was fragmented in both institution and policies, which resulted in serious problems in the coastal waters and oceans. However, a series of maritime accidents and failures of policies increased the recognition of the coastal waters and resources and led to the establishment of one single ocean-related governmental agency in 1996. Over the last decade, the ocean governance in Korea has been successful and strong.