Ocean carbon cycle and marine ecosystem dynamics
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Abstract:
On the basis of discussion of present status and problems involved with research on the marine carbon cycle,the role of marine ecosystem dynamics in ocean carbon cycle is analysed.Early studies of the carbon cycle emphasized on the cycle of inorganic carbon.As the research is carried on in a deep going way,the carbon cycle model with a simple biogeochemical process even with an explicit ecosystem is being developed.The future research is pointed out that it includes a better understanding of the physical processes and development of the marine carbon cycle model with an explicit ecosystem.For this reason methods of parameterisation of some key processes should be studied in the marine ecosystem dynamics,and values of some parameters should be determined.It is expected that the future models can be used more precisely to study the response of the marine ecosystems and carbon cycle to global changes.Keywords:
Biogeochemical Cycle
Marine ecosystem
Carbon fibers
Ecosystem model
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Biogeochemistry
Biogeochemical Cycle
Marine habitats
Plastic pollution
Marine ecosystem
Marine Pollution
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The concentration of the atmospheric CO 2, one of the most important greenhouse gases, is increasing since the beginning of industrialization from its pre-industrial value of 280ppmv to its present value of 366ppmv. It has been proved that human activities, including fossil fuel burning, cement production, and land-use change, have severely disrupted the model of the carbon cycle, thereby alter the climate system and affect the processes and mechanisms in terrestrial ecosystems. Understanding the consequences of these changes in the coming decades is critical for the formulation of political, economic, energy, and security policies. So recently,studies in carbon cycle have increasingly become a focus of global change and geo-science in the world. The terrestrial ecosystem,one of the most important parts of the global carbon cycle, is most complex and most greatly affected by human activities. This paper, combined with the latest reports related to carbon cycle in IGBP and IPCC, introduces some major carbon pools, namely, lithosphere, atmosphere, ocean,and terrestrial ecosystem,in the global carbon cycle and their sizes and characteristics. Furthermore, four major approaches, including inventories method, eddy covariance measurements, inverse modeling and model of carbon cycle, which have been used to evaluate the biosphere-atmospheric exchange of CO 2in the terrestrial ecosystems,are introduced. Using inventories method we can get an estimate of the actual accumulation of carbon in terrestrial ecosystem. The eddy covariance approach can detect small changes in net CO 2exchange between terrestrial ecosystems and the atmosphere over various time scales. Inverse modeling approach can be used to infer carbon sources or sinks based on 3-D atmospheric tracer transport models and CO 2 records from the atmospheric observations, fossil fuel combustion and land use change. Model of carbon cycle is a powerful tool to estimate and evaluate the temporal and spatial patterns of carbon sources or sinks in various scales. The existing problems of using these four methods are also analyzed. Moreover, the uncertainties in terrestrial carbon process are analyzed particularly.Additionally,some problems unsettled in carbon cycle and development tendency are specified concisely.
Terrestrial ecosystem
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The Arctic Ocean is one of the fastest changing oceans, plays an important role in global carbon cycling and yet is a particularly challenging ocean to study. Hence, observations tend to be relatively sparse in both space and time. How the Arctic functions, geophysically, but also ecologically, can have significant consequences for the internal cycling of carbon, and subsequently influence carbon export, atmospheric CO2 uptake and food chain productivity. Here we assess the major carbon pools and associated processes, specifically summarizing the current knowledge of each of these processes in terms of data availability and ranges of rates and values for four geophysical Arctic Ocean domains originally described by Carmack & Wassmann (Citation2006): inflow shelves, which are Pacific-influenced and Atlantic-influenced; interior, river-influenced shelves; and central basins. We attempt to bring together knowledge of the carbon cycle with the ecosystem within each of these different geophysical settings, in order to provide specialist information in a holistic context. We assess the current state of models and how they can be improved and/or used to provide assessments of the current and future functioning when observational data are limited or sparse. In doing so, we highlight potential links in the physical oceanographic regime, primary production and the flow of carbon within the ecosystem that will change in the future. Finally, we are able to highlight priority areas for research, taking a holistic pan-Arctic approach.
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Oceanic control of the atmospheric carbon dioxide concentration is the link between the studies of plankton ecology and climate change. Modeling ecosystem dynamics requires some understanding of the physics and chemistry of the upper ocean. In addition, an understanding of the issues involved in predicting climate change can help focus ecological studies. This article is intended as a review of upper ocean physics and chemistry as relevant to ecosystem research, and a summary of climate‐related issues to which ecosystem dynamics might in the future make a contribution. Our picture of the carbon cycle in the upper ocean relies on ecosystem dynamics for an understanding of the efficiency of nutrient uptake and export of carbon in the form of sinking carbon particles, and for the fraction of recycled and exported particulate carbon production. A fundamental variable appears to be the size distribution of phytoplankton. Also, ultimately, an understanding of the partitioning between calcitic‐ and siliceous‐based ecosystems may be important to predicting the long‐term ocean carbon cycle. Ecosystem dynamics of the upper ocean are driven by the interplay between dynamics of the surface ocean mixed layer and the depth of light penetration. This interplay is illustrated by noting the effect of high‐frequency fluctuations in mixed‐layer depth from a physical model (Archer et al. 1993) on an ecosystem model developed at weathership station Papa in the subarctic Pacific ocean (Frost 1987). Three families of surface ocean mixed‐layer models are available for use by plankton ecologists, and although the physical mechanisms by which mixing occurs differ among the model groups, all are generally successful at predicting the observed ocean mixed‐layer depth. This paper explores behavioral distinctions between the three types of models, and summarizes previously published comparisons of the generality, accuracy, and computational requirements of the three models. Nutrients are supplied to the euphotic zone by the exchange of water between nutrient‐depleted surface waters and nutrient‐rich deeper waters. Current understanding of this process is still problematic, with rates of mixing required to balance nutrient uptake estimates higher than values predicted based on turbulence studies. I also review evidence that episodic mixing, driven by frontal and mesocale motions, may be responsible for a significant fraction of vertical nutrient transport.
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Abstract The biogeochemistry of the ocean exerts a strong influence on the climate by modulating atmospheric greenhouse gases. In turn, ocean biogeochemistry depends on numerous physical and biological processes that change over space and time. Accurately simulating these processes is fundamental for accurately simulating the ocean's role within the climate. However, our simulation of these processes is often simplistic, despite a growing understanding of underlying biological dynamics. Here we explore how new parameterizations of biological processes affect simulated biogeochemical properties in a global ocean model. We combine 6 different physical realizations with 6 different biogeochemical parameterizations (36 unique ocean states). The biogeochemical parameterizations, all previously published, aim to more accurately represent the response of ocean biology to changing physical conditions. We make three major findings. First, oxygen, carbon, alkalinity, and phosphate fields are more sensitive to changes in the ocean's physical state. Only nitrate is more sensitive to changes in biological processes, and we suggest that assessment protocols for ocean biogeochemical models formally include the marine nitrogen cycle to assess their performance. Second, we show that dynamic variations in the production, remineralization, and stoichiometry of organic matter in response to changing environmental conditions benefit the simulation of ocean biogeochemistry. Third, dynamic biological functioning reduces the sensitivity of biogeochemical properties to physical change. Carbon and nitrogen inventories were 50% and 20% less sensitive to physical changes, respectively, in simulations that incorporated dynamic biological functioning. These results highlight the importance of a dynamic biology for ocean properties and climate.
Biogeochemistry
Biogeochemical Cycle
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Biogeochemical Cycle
Geotraces
Marine ecosystem
Biogeochemistry
Ocean chemistry
Global Change
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Biogeochemical Cycle
Biological pump
Ocean chemistry
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the SMP phase, has a number of interim goals as well, including the determination of fluxes and inventories of carbon in the modern ocean that air germane to the air-sea partitioning of C0{sub 2}. Models have a role to play here too, because many of these fluxes and inventories, such as the distributions of anthropogenic dissolved inorganic carbon (DIC), new primary production and aphotic zone remineralization, while not amenable to direct observation on the large scale, can be determined using a variety of modeling approaches (Siegenthaler and Oeschger, 1987; Maier-Reimer and Hasselman, 1987, Bacastow and Maier-Reimer, 1990; Sarmiento et al., 1992, Najjar et al., 1992). These twin needs for the development of marine carbon cycle models are expressed in two of the main elements of JGOFS SMP: (1) extrapolation and prediction, and (2) global and regional balances of carbon and related biologically-active substances. We propose to address these program elements through a coordinated, multi-investigator project to evaluate and intercompare several 3-D global marine carbon cycle models.
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There exists about 1.4～1.7GtC missing sink in the global carbon budgets. The missing sink might happen in terrestrial biosphere and coastal continental shelf. However, this guess is lack of support from scientific observation data and research methods. Progress in geo-information science is paving way for studying carbon cycle and its mechanisms of terrestrial ecosystems. To address the scientific issues such as temporal and spatial pattern of terrestrial ecosystem carbon sink, and driving mechanism and scenarios of carbon cycle, this paper proposes a method of geo-information science for studying carbon cycle of terrestrial ecosystems.Bottom-up approach and top-down approach are combined by means of scaling models. The bottom-up approach is based on observations of comprehensive network of carbon storage and carbon cycle process of terrestrial ecosystems, adaptive experiments of biological processes, and researches on carbon transportation processes of rivers. the top-down approach is based on detecting land cover change and retrieving ecological parameters by using satellite data. Retrieval models of carbon budgets are developed by means of the capacity of satellite remote sensing that can frequently supply surface information of geographical processes and ecological processes. On the basis of analyzing data-at-points collected by stations of Chinese Ecosystem Research Network, stations of Chinese Forest Ecosystem Research Network, and observation stations of HINAFLUX, combined with the retrieval models, a numerical simulation model of terrestrial ecosystem carbon cycle is constructed by means of surface theorem, grid generation method and grid computing technique. Pattern and process of carbon cycle are to be simulated; natural and human impacts on carbon cycle of terrestrial ecosystems are to be analyzed; and evolution trends of carbon cycle process of terrestrial ecosystems are to be discussed under the condition of global climate change.
Carbon sink
Terrestrial ecosystem
Global Change
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Biogeochemical Cycle
Biogeochemistry
Carbon flux
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