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课程摘要
Lecture Abstracts
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地球系统科学的陷阱：人类中心观
Anthropocentralism – a pitfall in Earth system science
汪品先院士
同济大学海洋地质国家重点实验室
近几十年来，人类发现自己正在破坏自身的生态环境，于是着手研究地球系统。但是在这场研究中，却又再陷入另一种错误，那就是人类中心观。人类习惯于拿自己有限的尺度去看待周围的一切，但是在地球系统的时空尺度中，能由人类感官和寿命覆盖的部分实在太小。于是“人类中心论”造成的偏向，犹如当年的“地心说”一样，阻碍着地球系统科学的发展。
一部科学史，其实就是人类不断开阔眼界、拓宽时空视野的历史；换个说法，也就是人类不断克服自身生理的限制，逐渐认识世界的过程。以当前的“全球变化”为例，被许多政府用来决策的气候模型，实际上只是根据地球表层系统中的部分过程、在较短的时间尺度做出的推论。而深海探索的新发现，却证明“全球变化”中“水循环”和“碳循环”这两大关键过程，都从表层系统一直延续到地球内部。现在知道大洋是一个双向系统，既有自上而下、又有自下而上的过程，而后者主要就是从地球内部进入表层系统的能流和物流。尤其是碳循环，无论是水层中的溶解有机碳、还是海底以下的“深部生物圈”，都没有被纳入地球“碳循环”的模型。
“人类中心论”在时间域里的表现，在对于长时间尺度的漠视，习惯于只考虑为和人生寿命、政府任期尺度相近的过程，以为这才值得认真对待。其实在今天的地球系统里，既有宇宙大爆炸留下的136亿年前的残余微波，又有十来分钟繁殖一次的海洋细菌，是一个不同时间尺度相互叠加的复杂系统。地球运行轨道的变化不仅带来冰期旋回，还有更长的季风周期，今天的地球正在经历着40万年一遇的偏心率最小期，然而我们至今并不注意其气候含义。
地球科学中至今所知的各种理论，基本上都是相邻学科在研究地球某种过程中的应用。真正属于地球科学自身的理论，应该是地球系统在不同时空尺度上的相互关系，但是人类及其科学研究在时间上的穿越能力远不如空间。可以推测，克服不同时间尺度的障碍，既能跨越空间、又能跨越时间的研究方向，才有可能解开地球系统运行规律之谜。
海洋作为地球系统中的恒温器及恒化器—兼谈大陆边缘海域之高效能生地化作用
The ocean as a thermostat and chemostat in the earth system with emphasis on continental margins as a powerful biogeochemical reactor
刘康克教授Kon-Kee Liu <kkliu@ncu.edu.tw>
中央大学水文与海洋科学研究所 <http://www.ihs.ncu.edu.tw/>
It has long been well known that the ocean serves as the major thermostat for the earth system because of the high heat capacity of water and the extraordinarily large latent heat associated with phase transitions of water. Only in recent years, it has been gradually appreciated that the chemostatic function of the ocean, or more appropriately, the hydrosphere, is equally important in maintaining the habitability of the Earth. On the millennium time scale, the ocean is the most important carbon reservoir, comprising about 97% of the total carbon in the surface environment of the Earth, that dominates the other reservoirs, namely, the atmosphere (comprising about 2%), soil and the biosphere (the latter two comprising less than 1%). If the anthropogenic CO2 were completely equilibrated between the atmosphere and ocean, less than 20% would remain in the atmosphere. That explains the importance of the ocean as a chemostat. However, the ocean circulation is sluggish, as compared to that of the atmosphere, resulting in slow progress in achieving equilibration between the two reservoirs. In fact, the equilibration action is quite complicated and is often summarily termed as the carbon pump, which involves not only physical processes but also biogeochemical processes. The efficiency of the carbon pump is not the same everywhere, with the most efficient pumps occurring in the very limited region of deep/intermediate water formation in the high latitudes of the northern hemisphere. In contrast to these more confined regions, as pointed out by Arthur Chen, continental margins appear to act as a short cut for carbon transport from the atmosphere to the deep ocean. The “continental margin pump” also involves very complicated physical-biogeochemical processes. It is cautioned that continental margins, though behaves as a net sink of atmospheric CO2 at present, their future changes are far from certain. In addition, biogeochemical processes in continental margins other than those associated with carbon cycle could also play critical roles in the future. One example is the “nitrous oxide surprise,” which could become a major threat to the climate system. It is highly desirable to better understand the very active biogeochemical systems in continental margins because of their potential strong feedback to the earth system. On the geological time scale, the hydrosphere also plays an important role in maintaining the Earth as a habitable planet with the global water cycle and related geochemical processes serving as the major machinery.
深海奧秘 The Mystery of Deep Sea
李昭兴教授Chao-Shing Lee
台湾海洋大学应用地球科学研究所
Institute of Applied Geosciences, National Taiwan Ocean University
The deep sea is the last frontier for human. After 200m water depth, there is no light, but represent 60% of the Earth. Because the sun light can not reach the deep sea, therefore, it has no photosynthesis, usually regard as the “desert”. The tools of new marine technology, such as the Remote Operated Vehicle (ROV), manned Submersible, Automated Underwater Vehicle (AUV) and Marine Cable Observatory system, have enabled the scientist to reach the deep sea, explore the deep sea and begin to understand more about the deep sea. In the last 1-2 decades, the scientist start to discover that there is the particular deep-sea bacteria which can transfer the “poison” sulfur material into the usable “nutrient” and provide the upper level biological communities as the food source. They are living peacefully in the deep sea. We found them in the continental slope of more than 800m, in the mid-ocean ridge of 2,000 – 3,000m deep and more surprisingly in the deep sea trench of deeper than 6,000m. Marine biologist suggests that this may be the “Origin of Life”. Because the oldest fossil is the marine organism; the major contents of the sea water is close to that of the animal blood and easy to be live within it; the marine volcanoes are continuously distributed along the mid-ocean ridges; besides, the deep sea organisms are thermophilic, barophilic, and akalophic. Therefore, they can live in such a hash environment in the deep sea. Marine geologist believes that the deep sea trench is the “Seismogenic Zone”. Because the mega earthquake is usually generated from the subduction zone. Through the helps of new technology, we begin to understand more about the deep-sea resources, such as the deep-sea oil, manganese nodule, heavy metal, and gas hydrate. These will be our human future “Deep Sea Resource” when we deplete the land resource. In the other hand, the marine chemist discovers that a thick deposite of carbon is semi-permanently stored in the deep sea trench in which they regulate the “Climate Change”. The deep sea is mystery, but it is a challenge for our young marine scientist.
深海是全人類的最後一片淨土。水深深於200公尺以下，幾乎一片都是黑漆漆，伸手不見五指(但它佔有全球總面積的60%)。也因為陽光無法穿透，所以無法進行光合作用。通常被認定:不適合於生物寄居的地方，它是一片的「海洋沙漠」。但海洋科技的發達，科學家開始利用無人的遙控載具(ROV)、有人的深海潛艇(manned submersible)、自動潛航載具(AUV)、和各種深海觀測的海底電纜系統(Marine Cable Observatory)等，深入海洋、探勘海洋和瞭解海洋。近一、二十年來，人類開始發現，特殊的深海細菌，它們能夠將「有毒」的硫化物，以「化合作用」分解成為「營養物」，以供應更高等的生物，而且能夠以「共生」的族群方式，生活在深海底。800公尺以下的大陸斜坡上，2,000-3,000公尺的中洋脊上，甚至5,000-6,000公尺的海溝裡都發現它們的「群落」。漸漸地，海洋生物學家開始在懷疑深海的生物，可能是「生命的來源」。因為最古老的化石來自海洋生物;而海水的主要原素與動物的血液最為接近，最適於生物著床之處，海底火山延綿不斷;而且發現的海底生物「群落」，它們可以抗溫、抗壓和抗鹼;對它們而言，生活在海底的惡劣環境已經不是問題。海洋地質學家也發現巨大的地震，大部份來自深海底下的隱沒帶，而且建議它可能是「地震的起源」。通過新穎的科技，人類漸漸瞭解深海底的石油、錳結核、重金屬礦物、天然氣水合物等非生物資源，可能是人類未來在陸上資源匱乏後的主要依賴。海洋化學家更發現，大量的碳被封存於深海溝，以調整全球的氣候變遷。深海是年青海洋科學家挑戰的地方。
Seafloor Biogeochemical Processes: Microbial Methane in Marine Sediments
Prof. Frederick (Rick) S. Colwell
College of Oceanic and Atmospheric Sciences, Oregon State University
Hydrates in marine sediments of continental shelves contain huge quantities of biogenic methane held in place by high pressures and low temperatures. This methane is important as a potential greenhouse gas (if it escapes to the atmosphere), as a source of energy, or as a factor in seafloor stability. However, knowledge of the rates at which this methane accumulates in the sediments and the microbial communities that generate the methane is limited. Our microbiological studies of hydrate bearing sediments focus on determining: 1) the in situ activities of the methanogens and 2) the environmental controls on the distribution of these cells in the sediments. By linking accurate estimates of methanogen numbers at specific depths in hydrate-bearing and adjoining strata with the rates of methanogenesis when these cells are starved – a typical condition for many subsurface cells – we derive realistic in situ methane production rates for these communities. We have also described a novel subsurface occurrence of the microbial communities that anaerobically oxidize methane. These communities develop biofilms in fractured methane-rich sediments where sulfate and methane are depleted. The methanogenesis rates we determine and assessment of factors that constrain microbial life in the subsurface are required for models that describe the dynamics of methane transformation in marine sediments.
Non-thermophilic archaea (Thaumarchaeota) in open oceans: new players in global carbon and nitrogen cycles and Implications for marine GDGT proxies
张传伦教授Chuanlun Zhang
The State Key Laboratory of Marine Geology, Tongji University
And Department of Marine Sciences, University of Georgia
Archaea were originally devided into two kingdoms: Crenarchaeota and Euryarchaeota, which were mostly studied in extreme enviornments such as terrestrial hot springs. Culture-indpendent molecular studies in the past 20 years have demonstrated the ubiquity of archaea in nature, particular the marine settings. Currently, new phyla of archaea include Korarchaeota, Nanoarchaeota, and Thaumarchaeota. The latter was previously called non-thermophilic crenarchaeota. Among these, Thaumarchaeota have received the most attention, particularly in oceanic research. Studies so far demonstrate the wide distribution and vast abundance of Thaumarchaeota in water column and sediments of the ocean, which show spatial and temporal variations in global oceans. Advances in genomic research provide further insight into the physiology and biochemistry of Thauarmchaeota, which are known to play important roles in global nitrogen and carbon cycles. In parallel, advances in LC-MS technologies have allowed us to develop novel proxies based on archaeal lipids for environmental and paleoclimate studies. The integration of molecular DNA and lipid biomarkers is becoming a new trend in archaeal research and driving a new wave of discoveries in marine ecology and biogeochemistry.
Microbiology of Deep-sea vents
Prof. Anna-Louise Reysenbach
Portland State University
We live on a microbial planet. Most of the biodiversity of life on Earth is microbial. These microscopic organisms occupy almost any conceivable habitat where there is available water, energy and carbon for growth, even in the minutest quantity. They live in some of the most salty, cold, hot, nutrient-starved, dry and acidic places on this planet, and they form critical partnerships with many other organisms, including us. At deep-sea vents, microorganisms form the base of the food web, fueling the chemosynthetic-based ecosystem. Here, a huge diversity of microbes are supported by geochemical fluxes from Earth’s interior and the chemical disequilibria that result when chemically reduced fluids vent at the seafloor and mix with oxic seawater. The success of these microbes is tightly coupled to the geochemistry and mineralogy of the dynamic hydrothermal system. Many of the unusual invertebrates, like tubeworms which lack a mouth and gut, have formed obligate partnerships with their microbial symbionts who in turn rely on the geochemistry of the fluids for energy and carbon. Using DNA fingerprinting techniques, we are starting to get a better picture of the extent of the microbial diversity at deep-sea vents. Yet, with only a very small percentage of our deep sea explored, we are just scratching the surface! Nonetheless, every new site explored, every new study initiated, provides new biological discoveries. Much of the research is detective work, knowing that a certain microorganism resides in a particular habitat, yet looking for signs for what that organism is doing through careful sleuthing. Understanding the extent of life on Earth, how that life survives and thrives, whether at deep-sea vents or in a very dry desert or a salt pan, provides scientists with a more informed approach for looking for signs of past and present life elsewhere in the Solar System.
Biomineralization processes in mid-ocean-ridges and beyond
董海良教授Hailiang Dong
Miami University, Oxford, OH, USA
Abstract: Since the initial discovery of hydrothermal vents and their oases of bizarre animals in 1979, scientists from diverse disciplines have been working together to study a number of hydrothermal vent related processes such as ocean circulation, subseafloor tectonics, formation of mineral deposits, geochemical alteration of oceanic crust, and biological diversity and activity. Seafloor mineralization is a complex process where hydrothermal fluids interact with rocks to leach many metals from rocks into fluids. These dissolved metals precipitate as sulfide (mainly Fe-, Cu-, Zn-, Pb-, As-sulfides) and oxide minerals when hot hydrothermal fluids encounter cold seawater. Such deposits form economically valuable ores. However, these deposits are not currently explored because of technology limitations, and detection of hydrothermal activities and related mineral deposits are largely dependent on geochemical, geophysical, and biological signatures.
The subseafloor harbors a substantial biosphere sustained by volcanic heat and chemical fluxes from the Earth’s interior. This discovery has profound scientific implications for the origin of life, the true extent of Earth’s biosphere, and the search for life on other planets. Subsurface geological and biological processes are intimately linked, as subseafloor rocks and fluids provide habitat, energy, and nutrients to support life, but also physical and chemical processes within seafloor provide fundamental controls on the ecology and the diversity of microbial communities. Biological activities can significantly impact geological processes, such as microbial alteration of oceanic crust and ocean chemistry, and biogeochemical cycling of a suite of elements. Recent developments in molecular biology have provided new tools to study microbial biogeography, distribution of microorganisms in relation to geographical distance and environmental variables. Microorganisms in seafloor hydrothermal systems have been found to be much more abundant and diverse than previously thought. Novel microorganisms with novel functions have been discovered that grow in the subsurface under extreme conditions. This talk will highlight a few such novel functions such as microbial Fe(II) and sulfur oxidation, microbial alteration of oceanic crust (bioweathering) and Fe(III) reduction by hyperthermophiles. In these interactive processes, rocks provide abundant nutrients for microbial growth and metabolism, and microbial activity accelerates rock weathering and alters fluid chemistry. However, studies of these interactions are largely dependent on indirect measurements or laboratory simulations. Future investigations will most likely focus on in-situ studies, such as in-situ, long-term seafloor observatories. This talk will end by providing some exciting future research opportunities and challenges, especially in the context of ever-expanding role that Chinese scientists play in this field.
研究深海过程与通量：进展与挑战
Progress and challenges in studying deep ocean processes and fluxes
林间教授 Jian Lin
(jlin@whoi.edu, http://www.whoi.edu/page.do?pid=39595)
美国伍兹霍尔海洋研究所 Woods Hole Oceanographic Institution, USA
The mean depth of world’s oceans is about 3,682 m. Much of the most active geological processes of the Earth occur in the deep oceans, including mid-ocean ridges, trenches, transform faults, seamounts, and oceanic plateaus. The deep-sea processes are responsible for creating the largest earthquakes and tsunamis, as vividly illuminated by the 11 March 2011 magnitude 9.0 quake off Tohoku, Japan, and the devastating tsunami. Meanwhile, the deep oceans and seabed host diverse chemosynthetic life under extreme conditions, much of which is still poorly understood. This presentation highlights recent progress in research of ocean floor processes and fluxes, breakthroughs in deep submergence technology, and challenges in deep-sea exploration, drawing examples from investigations of mid-ocean ridges and subduction zones. The mid-ocean ridge volcanic system is the longest geological feature in the solar system, playing a critical role in the release of heat and chemical fluxes from Earth’s lithosphere to the oceans. Nearly 75% of Earth’s total heat flux occurs through ocean floor, much of it at ocean ridges and young oceanic crust. Hydrothermal vents are areas of focused and rapid outflow of seawater heated by magma sources beneath ocean ridges. Active hydrothermal vents have now been found along ocean ridges in all major oceans, while a significant length of the ridge system is still little explored, especially in high-latitude regions. Directly measuring the heat, chemical, and biological fluxes at ocean ridges and on young oceanic crust are an important goal of the science community but technical challenges remain. Most ocean ridges are located in international waters and the scientific objectives of researchers transcend national boundaries, and thus collaborations and share of knowledge and resources are essential to make progress. The presentation will highlight increasing contributions by Asian countries to deep-sea research and exploration.
Hydrothermal interaction between the seafloor and seawater: the Gueishandao Is. Example
陈镇东教授Chen-Tung Arthur Chen
Institute of Marine Geology and Chemistry,
National Sun Yat-Sen University,
Kaohsiung 804, Taiwan, ROC
E-mail: ctchen@mail.nsysu.edu.tw
Elemental sulfur and hydrogen sulfide emitted offshore of northeastern Taiwan known to local fishermen for generations, but never studied until recently, are found to have originated from a cluster of shallow (<30 m depth) hydrothermal vents. Among the mounds is a massive 6 m high chimney with a diameter of 4 m at the base composed of almost pure sulfur and discharging hydrothermal fluid containing sulfur particles. The sulfur in the chimney has a d34S=1.1‰ that is isotopically lighter than seawater. A yellow smoker at shallow depths with such characteristics has never been reported on anywhere else in the world. Gas discharges from these vents are dominated by CO2 (>92%) with small amounts of H2S. Helium isotopic ratios 7.5 times that of air indicate that these gases originate from the mantle. High temperature hydrothermal fluids have measured temperatures of 78-116 °C and pH (25°C) values as low as 1.52, likely the lowest to be found in world records. Low temperature vents (30-65 °C) have higher pH values. Continuous temperature records from one vent show a close correlation with diurnal tides, suggesting rapid circulation of the hydrothermal fluids.
Evolution and recent transformation of marine nitrogen cycle
海洋氮循环历史变迁与近代的转变
高树基研究员 Shuh-Ji Kao (sjkao@gate.sinica.edu.tw)
Research Center for Environmental Changes, Academia Sinica, Taiwan
台湾”中央”研究院
The nitrogen cycle has been accelerated remarkably as a result of the production and industrial use of artificial nitrogen fertilizers worldwide that enable humankind to greatly increase food production, but it has also led to a host of environmental problems, ranging from eutrophication of terrestrial and aquatic systems to global acidification. Recent investigations on the manifold consequences of human alteration of the nitrogen cycle have advanced our understanding of the scope of the anthropogenic nitrogen problem and possible strategies for managing it. However, less emphasis has been placed on the study of the interactions of nitrogen with the other major biogeochemical cycles, particularly that of carbon, and how these cycles interact with the climate system in the presence of the ever-increasing human intervention in the Earth system. With the continuous release of carbon dioxide (CO2) from the fossil fuel burning the climate system had been driven into an uncharted territory, where major consequences of the altered carbon cycle with nitrogen having a crucial role in controlling key aspects of this cycle. Questions about the nature processes and importance of nitrogen–carbon–climate interactions are becoming increasingly pressing. To explore such web-structured interactions we need to investigate the dynamics of the nitrogen cycle in the context of a changing carbon cycle, a changing climate and changes in human actions over wide spatial and temporal scales. Here I will introduce examples of how the nitrogen cycle has been perturbed, how they links to other elemental cycles and the natural cycles with physical and biological controls and anthropogenic alterations with potential projections to the future.
Comparative analysis of microbial community structure and function of two deep-sea brine pools from the Red Sea
钱培元教授Peiyuan Qian
KAUST Global Collaborative Research Program, Division of Life Science, Hong Kong University of Science and Technology, Hong Kong
The Red Sea formed when the Arabian and African plates started to split 3-5 Ma years ago. It is a largely enclosed basin with a large amount of lava rock containing potassium tholeiites, similar to the basalt rock in other oceans. The high temperature and highly saline environment of the Red Sea are due to the high rate of evaporation, low level of precipitation, and lack of major river inflows. Intriguingly, a large number of deep-sea brine pools (about 25) have been found in the Red Sea during the past 50 years. Their anaerobic, hypersaline, hyperthermal, and metalliferous conditions make these pools among the most unusual and extreme environments on Earth. All of these geochemical and physical parameters make the Red Sea a unique environment compared with other marine ecosystems. Among the brine pools, two neighboring deep-sea brine pools - the Atlantis II Deep and Discovery Deep, which are characterized by high salinity, high temperature, and high metal contents, have been extensively studied for their geochemical and geological characteristics. Over the past 50 years, the seawater temperature of the Atlantis II Deep has raised from 56 to 68oC, whereas that of the Discovery Deep has maintained relatively stable at about 44 oC. We hypothesized that such a drastic temperature change in the Atlantis II Deep shall have driven the microbial community there through substantial adaptive changes; subsequently, there shall be substantial differences in microbial community structure and function between the Atlantis II Deep the Discovery Deep. In this study, we have analyzed community diversity and functional genes of both bacteria and archaea in the brine pool waters, the overlying deep-sea water, and the brine-seawater interfaces, using most advanced sequencing platform. As expected, the bacteria and archaea communities were significantly different in terms of species diversity, metagenomic reads, functional gene groups. Specifically, in the Discovery Deep, he highest microbialabundancewas found in the brine-seawater interface, probably due to a complex mixing environment therein, whereas the upper convective layer of the Atlantis II Deep harbored more microbes than in its interface. Overall, we identified 19 phyla and a high proportion of unclassified groups in both brine pools. The Discovery Deep was dominated by halophilic methanogens, while in contrast, the Atlantis II Deep harbored thermo-tolerant, metal-resistant bacteria that can degrade aromatic compounds and mediate metal precipitation. The presence of aromatic compounds in the Atlantis II Deep was further confirmed by chemical analysis and supported by significantly enriched aromatic degradation pathways in the metagenome of this Deep. These aromatic compounds were believed to be hydrothermally produced under the high temperature. In the Discovery Deep, the most abundant genes from the microbes were related to sugar metabolism pathways and DNA synthesis and repair, suggesting different strategies of utilization of carbon and energy sources between the two brine pools. A substantial divergence in functional profiles of the two pools was further highlighted by different abundances of genes involved in ion transport, signal conduction, and transcription. In summary, the chemical and ecological differences between these two neighboring brine pools have strongly shaped their microbial communities and led to different functions and evolutionary scenarios. Altogether, the two brine pools are unique ecosystems warrant further exploration.
Acknowledgement: This study was supported by an award SA-C0040/UK-C0016 from the King Abdullah University of Science and Technology to PY Qian, Drs Wang Y, Lee OO, Yang JK, Lau SCK, Wong TH, Al-Suwailem A for conducting both field and lab works.
微型生物碳泵——海洋储碳新机制
Microbial Carbon Pump, a mechanism of carbon sequestration in the water column- what, why, and how
焦念志教授Nianzhi Jiao
Xiamen University
The ocean is the largest carbon sink in the world. The known biological mechanism for carbon sequestration in the ocean is the biological pump (BP) which is based on particulate organic matter (POM) sinking process. However, the POM reaches to the marine sediment is only a tiny fraction of the total primary production in the euphotic zone. Where is the rest of the organic carbon gone? In addition to the respired major portion (CO2), the majority of the organic carbon in the ocean is actually in the form of dissolved organic matter (DOM). The biogeochemical behavior of this enormous DOM reservoir is an important issue in understanding the role of the ocean in climate change. The majority of DOM in the ocean is recalcitrant, with an average age of ~5000 years, constituting a sequestration of carbon in the ocean. However, the mechanisms controlling the generation and removal of the recalcitrant DOM (RDOM) are largely unknown.The proposed microbial carbon pump (MCP)（Jiao et al. NATURE REVIEWS Microbiology 2010.8:593-599) offers a formalized and mechanistic focus on the significance of microbial processes in carbon storage in the RDOM reservoir, and a framework for testing the sources and sinks of DOM and the underlying biogeochemical mechanisms. The BP and the MCP are intertwined, Interactions between the two along environmental gradients would affect the fate of the organic carbon. Understanding of the functioning and efficiency of the MCP is an urgent need since ocean warming may change carbon flux partitioning among different pathways and thus potentially enhance the role of the MCP in carbon storage. A working group joined by 26 scientists from 12 countries has been formed under the Scientific Committee on Oceanic Research (SCOR-WG134) to address this multi-faceted biogeochemical issue related to carbon cycling in the ocean and global climate change. This lecture will address the following concerns:
1. What is MCP?
2. Why MCP?
3. How was MCP proposed?
4. What are the differences between MCP and other biological mechanisms (BP, ML, VL)
5. How much dose MCP contribute to the oceanic RDOM pool?
6. How MCP vary along environmental gradients?
7. How MCP respond to global warming?
8. What are the potential MCP applications?
9. What are the related international activities?
10. What we need to do in practice (MCP vs BP; survey vs expt, N,P vs Fe; Arctic vs Warm Pool)?
Iron Limitation and the Ocean’s Carbon and Nutrient Cycles
Prof. David A. Hutchins
Professor, Department of Biological Sciences, University of Southern California
Over the past several decades, oceanographers have come to recognize that the micronutrient iron is a key limiting nutrient for primary producers in the ocean. Over perhaps as much as half of the ocean’s surface, including the vast open ocean High-Nutrient, Low Chlorophyll (HNLC) areas, iron limitation controls the amount of carbon fixed by phytoplankton and hence limits the storage of fossil fuel carbon by the biological pump and the productivity of the entire food web. The reason that iron is so important to marine biology and biogeochemistry is that it plays a central biochemical role in fundamental cellular processes such as photosynthesis, respiration, and nutrient uptake. Iron is supplied to remote open ocean areas largely through the atmospheric deposition of continental dust, so the supply rate is nearly always much lower than the biological demand. The fact that iron largely controls the amount of CO2 that the oceanic biota can fix has led to proposals to draw down atmospheric CO2 concentrations using “geo-engineering” schemes to artificially fertilize the ocean with iron. However, we still know very little about the consequences that iron fertilization might have for marine ecosystems, especially in light of new evidence that suggests the basic nature of the relationship between the marine iron and carbon cycles may be changing in a rapidly acidifying and warming ocean.
Tiny viruses and their big role in the ocean
陈峰副教授Dr. Feng Chen
University of Maryland Center for Environmental Science
Viruses are the most abundant biological entities in the world’s oceans. In seawater, viral abundance exceeds prokaryotic abundance by at least one order of magnitude. It is known now that viral lysis accounts for a significant portion of microbial mortality. Viral lysis of infected microbes transforms their cellular components into organic detritus, in both dissolved and particulate forms, which can be used again by non-infected microbes. This process (also called viral shunt) actually decreases the efficiency of the carbon transfer to higher trophic levels and influences the carbon budget of the oceans. Viral lysis also releases refractory dissolved organic matter (RDOM), and this process is part of microbial carbon pump (MCP). However, the extent of viral contribution to the MCP still remains largely unknown. Small unicellular cyanobacteria (also picocyanobacteria) make up the vast majority of ocean's primary production. Viruses that infect picocyanobacteria (or cyanophage) have been found to co-vary with picocyanobacteria in the ocean. The active interaction between picocyanobacteria and cyanophage can serve as a useful model for understanding the virus-mediated redistribution of carbon from the photic zone to deeper water. Different gene markers have now been developed to monitor the community composition of cyanophage and picocyanobacteria in different water depths. In the past, a great deal of studies on viral ecology has been focused on surface water. Much more effort is needed to better understand the virus-mediated transformation of carbon fixed in the euphotic zone to deeper ocean and ocean floor.
从物理海洋学角度看海气交互作用与气候变化
Ocean-Atmosphere Interaction and Climate Change: a Physical Perspective
陈大可教授Dake Chen
State Key Lab of Satellite Ocean Environment Dynamics, Hangzhou
Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York
The ocean and the atmosphere are two major components of the Earth’s climate system, and the interactions between them play a central role in climate change and variability. This lecture briefly reviews our current understanding of ocean-atmosphere interaction in the context of climate change, mostly from a physical oceanographer’s perspective. We will start with an introduction of the topic, including the characteristics of the momentum, heat and freshwater fluxes at the air-sea interface, and the interplays of the ocean and the atmosphere in the heat and hydrological balances of our planet. Then we will discuss one by one the hotly debated issues of global warming, the possibility of abrupt climate change, the natural climate oscillations on various timescales, and the tropical cyclone activity in the changing climate, all with particular emphasis on the roles of ocean-atmosphere interaction, and on the predictability of the phenomena. The take-home messages include:
● Because of the vast volume and heat capacity of the ocean, it contains most of the memories of the Earth’s ocean-atmosphere coupled system. In order to understand climate change and variability, we have to take the ocean and its interaction with the atmosphere into account.
● The ocean may delay global warming by absorbing large amount of heat and greenhouse gases from the atmosphere; it may initiate abrupt climate change due to its disrupted thermohaline circulation; and it may set the timescales for various natural climate oscillations.
● The slow pace and persistence of oceanic variations give hope to long-range prediction, but there still exist large uncertainties in climate predictability. Presently available observations and coupled models are generally inadequate for long-term projection of climate change.
● The strongly coupled, short-term climate fluctuations such as ENSO are highly predictable even with simplified models. The success in ENSO prediction also demonstrates the effectiveness of large international programs that bring oceanographers and meteorologists together for climate research, and that combine first-rate observational, theoretical and modeling efforts to achieve a well-defined goal.
Effects of global change on marine ecosystems
陈镇东教授Chen-Tung Arthur Chen
Institute of Marine Geology and Chemistry, National Sun Yat-Sen University, Kaohsiung
E-mail: ctchen@mail.nsysu.edu.tw
Climate change will fundamentally alter the structure of oceans and directly impact marine ecosystems and human societies. Recent assessments of the global climate have concluded that ocean temperature, sea level and acidity have been increasing (IPCC report). Further, summaries of recent climatic data indicate that the intensity and frequency of ocean storms are increasing as well.
Climate induced changes and other less-understood anthropogenic changes will be superimposed on other impacts resulting from human activities such as over fishing, pollution, damming of rivers and habitat loss in coastal areas. Consequently, the fundamental characteristics of marine ecosystems, some already under stress, will be altered. Whether overall global yield from marine fisheries will decline due to climate change remains unclear; however, regime shift within individual marine ecosystems and trends in fish landing for certain species will likely occur. Calcareous plankton and coral are already suffering because of more acidic and warmer seawater. Combined with the potential loss of primary and secondary producers and important habitats, detrimental effects of climate change to fisheries are a matter of concern.
Upper Ocean Dynamics, Air-Sea Interactions and their Role in Global Climate Changes
严晓海教授Xiao-Hai Yan
University of Delaware and Xiamen University Joint Institute of Coastal Research and Management (XMU-UD Joint-CRM, 近海海洋研究与管理联合研究所)
One of the principal goals of global climate research is the prediction of long – term – period changes in Earth’s climate. The state of Earth’s climate is adjusted by the upper layers of the ocean, where most of the solar energy flux is absorbed. Hence, the dynamic processes in the upper ocean and the heat flux changes play a vital role in the air-sea interaction. This interaction between the ocean and the atmosphere takes place via three primary physical processes: (1) heat transfer by radiative and turbulent fluxes; (2) momentum transfer by the winds; and (3) moisture transfer by evaporation and precipitation. Therefore, understanding the heat, momentum, and moisture fluxes at the air-sea interface is important for comprehending the energy exchanges and the oceanic response. This lecture will illustrate the upper ocean processes including upper ocean thermal structure, upper ocean mixed layer dynamics, upper ocean heat fluxes and transport, El Nino and Southern Oscillations (ENSO), meridional overturning circulation (MOC), deep ocean convection (DOC), and their roles in global climate changes. Varies data sets and methods including state of art remote sensing methods we developed lately will be introduced in the class.
Oceans and Earth System Modeling
柴扉教授Dr. Fei CHAI
School of Marine Sciences and Climate Change Institute
University of Maine
Ocean plays an important role in regulating the Earth climate system. Incorporating key oceanic processes into the earth system models is crucial for simulating and predicting global change. In this lecture, I will introduce some basic concepts about ocean modeling, and use several examples to illustrate how climate variability affects ocean physics and chemistry and ecosystem dynamics. Using modeling approach, I will demonstrate how oceans redistribute heat, freshwater, and carbon and regulate the climate during the past, present, and future. Also, I will show how ocean biogeochemical cycle and biology may affect physical processes and therefore the Earth climate system. At the end, I will review the basic structure and components of Earth system models, use examples to understand how these models work, their limitations, and directions for improving the simulations and predictions.
Continental Margins: The Link between Land and Ocean
刘祖乾教授James T. Liu and Xiaoqin Du
Institute of Marine Geology and Chemistry, National Sun Yat-sen University
Kaohsiung, Taiwan
Email: james@mail.nsysu.edu.tw
In this talk, the term ‘continental margin’ is used interchangeably as ‘coastal ocean’ because of the high degree of overlapping in geographic location, dimension, and in oceanographic characteristics.
Continental margin is located between the landmass, may it be a continent or an island, and the open ocean. Because of its proximity to land and the open ocean, it is subject to influences from the both. These influences are described in the following areas:
The air-sea boundaries, in which energy and substances are exchanged leading to changes in both the atmosphere and ocean.
The land-ocean boundaries, in which the land and ocean interact with each other on different space and time scales.
The water-sediment boundaries, in which erosion and deposition occur that, could modify the topography of these boundaries.
Hurricanes and typhoons are the most important episodic forcings that affect all these boundaries.
This talk will also have a regional focus on how the three major river-dispersal systems of Huanghe, Changjiang, and Zhujiang affect the two largest marginal seas in the world, the East China Sea and South China Sea. The importance of the high standing island of Taiwan in the export of terrestrial sediment and carbon to the adjacent sea and ocean will be discussed.
Next, the talk will focus on two issues related to the global climatic change:
The warming ocean: bringing about the increased intensity of hurricanes and typhoons.
The rising eustatic sea level: threat to coastal communities and fragile environments around the world.
The talk will end with the reflection of the onset of anthropocene. The activities of the mankind have greatly influenced the planet earth in the past century and the possible course of action in the future.
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