The Biogeochemical Silicon Cycle in the Arctic Ocean PDF Download

Author: Bianca Torres Liguori Pires
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Bernard Quéguiner
Publisher: John Wiley & Sons
ISBN: 111913689X
Category : Science
Languages : en
Pages : 146

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In the biogeochemical dynamics of marine ecosystems, silicon is a major element whose role has, for a long time, been underestimated. It is however indispensable to the activity of several biomineralizing marine organisms, some of which play an essential role in the biological pump of oceanic carbon. This book presents notions indispensable to the knowledge on the silicon biogeochemical cycle in ocean systems, first of all describing the main quantitative analysis techniques and examination of the major organisms involved in the cycle. The author then moves on to study the most up-to-date processes to control the use of silicon and its regeneration in natural conditions, before mentioning the central role played by this original element in the control of all the biogeochemical cycles in the global ocean. The available information finally enables the global biogeochemical budget of silicon in the marine environment to be quantified.

Author: Venugopalan Ittekkot
Publisher: Island Press
ISBN: 1597267821
Category : Science
Languages : en
Pages : 297

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Silicon is among the most abundant elements on earth. It plays a key but largely unappreciated role in many biogeochemical processes, including those that regulate climate and undergird marine food webs. The Silicon Cycle is the first book in more than 20 years to present a comprehensive overview of the silicon cycle and issues associated with it. The book summarizes the major outcomes of the project Land-Ocean Interactions: Silica Cycle, initiated by the Scientific Community on Problems of the Environment (SCOPE) of the International Council of Scientific Unions (ICSU). It tracks the pathway of silicon from land to sea and discusses its biotic and abiotic modifications in transit as well as its cycling in the coastal seas. Natural geological processes in combination with atmospheric and hydrological processes are discussed, as well as human perturbations of the natural controls of the silicon cycle.

Author: Rüdiger Stein
Publisher: Springer Science & Business Media
ISBN: 3642189121
Category : Science
Languages : en
Pages : 394

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The flux, preservation, and accumulation of organic carbon in marine systems are controlled by various mechanisms including primary p- duction of the surface water, supply of terrigenous organic matter from the surrounding continents, biogeochemical processes in the water column and at the seafloor, and sedimentation rate. For the world's oceans, phytoplankton productivity is by far the largest organic carbon 9 source, estimated to be about 30 to 50 Gt (10 tonnes) per year (Berger et al. 1989; Hedges and Keil 1995). By comparison, rivers contribute -1 about 0. 15 to 0. 23 Gt y of particulate organi.

Author: Jacqueline M. Grebmeier
Publisher: Springer
ISBN: 9401788634
Category : Science
Languages : en
Pages : 461

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The Pacific Arctic region is experiencing rapid sea ice retreat, seawater warming, ocean acidification and biological response. Physical and biogeochemical modeling indicates the potential for step-function changes to the overall marine ecosystem. This synthesis book was coordinated within the Pacific Arctic Group, a network of international partners working in the Pacific Arctic. Chapter topics range from atmospheric and physical sciences to chemical processing and biological response to changing environmental conditions. Physical and biogeochemical modeling results highlight the need for data collection and interdisciplinary modeling activities to track and forecast the changing ecosystem of the Pacific Arctic with climate change.

Author: Alexander Vetrov
Publisher: Springer Science & Business Media
ISBN: 3662062089
Category : Science
Languages : en
Pages : 346

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This study analyzes carbon-cycle conditions controlling the state of the Arctic ecosystem and their seasonal variations. Territory covered includes the Barents, White, Kara, Laptev, East-Siberian and Chukchi Seas, considering inter-correlations between sources of organic carbon, their fluxes, recycling and burial in bottom sediments. All biological communities (phythoplankton, macrophythobenthos, microphythobentos, bacterioplankton, zooplankton and zoobenthos) are taken into account regarding their participation in the carbon cycle.

Author: Molly Alyse Palmer
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The Arctic Ocean has undergone unprecedented changes in sea ice extent and thickness in recent years, including record-setting sea ice minimums in 2007 and 2012. These changes are predicted to affect Arctic marine primary productivity (the photosynthetic fixation of carbon dioxide by tiny algae called phytoplankton) because the timing and intensity of the summer phytoplankton bloom are strongly controlled by the dynamics of sea ice and water column stabilization. Satellite-based estimates indicate that primary production in ice-free waters has increased dramatically over the last few decades as a result of the increases in open water and length of the growing season associated with the thinning ice cover. In addition, climate models predict that the Arctic will experience greater and more rapid warming than other areas of the planet over the next century, suggesting that these changes may become even more prevalent in the future. The thinning sea ice has already had a dramatic impact on regional biogeochemistry: in 2011, we observed one of the most massive phytoplankton blooms ever recorded under the sea ice in the Chukchi Sea, an area traditionally thought of as too dark and too cold for massive blooms to occur. In the Chukchi, melt-ponds on the ice surface have proliferated to an extent that, in combination with the thinning ice cover, light penetration through the ice to surface waters is now sufficient for net photosynthesis to occur. The bloom we witnessed in 2011 extended for over 100 km into the> 1 m thick ice pack, and was characterized by extraordinarily high diatom biomass and rates of production. These changes represent a marked shift in our conception of Arctic marine ecosystems and have potential global-scale implications due to feedbacks relating to sea ice albedo, global atmospheric and ocean circulation patterns, and natural greenhouse gas exchanges between the atmosphere and ocean. Chapter 1 presents an overall introduction to the Arctic and discusses the causes and consequences of this changing seasonal cycle of productivity. Chapter 2 presents results from field work performed in the Beaufort Sea in the summer of 2008 exploring the spatial and temporal variability of phytoplankton photosynthesis in the ice-associated region of the flaw-lead polynya (area of perennially open water that rings the Arctic Ocean between land-fast ice and the central Arctic ice pack; it can be used somewhat as an analog for future open-water and ice-edged based productivity). Continuing with this theme of exploring primary productivity and biogeochemical cycles in the changing Arctic, Chapter 3 details the results from photophysiological experiments performed during the summer of 2010-2011 that highlight the unique features allowing Arctic phytoplankton to reach high levels of biomass in the extreme environment under the ice. In Chapter 4, I present data from recent 1-D modeling efforts that utilize the light and nutrient-controlled responses of phytoplankton growing under the ice to explore the consequences and implications of this shifting bloom cycle on regional biogeochemical processes.

Author: Adam Jerold Reed
Publisher: Frontiers Media SA
ISBN: 288966967X
Category : Science
Languages : en
Pages : 149

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Author: Edwin Vatro Grill
Publisher:
ISBN:
Category : Silica
Languages : en
Pages : 220

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Author: Mangalaa Kameswari Rajasekaran
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Silicon is the second most abundant element in Earth's crust and one of the key nutrient in aquatic ecosystems. There are strong interactions of Si with carbon cycle and biogeochemical processes. The present thesis focused on variability of silicon (amorphous-ASi, lithogenic-LSi and dissolved-DSi) and Si isotopes along the land to ocean continuum. We investigated the seasonal and spatial variability of ASi, LSi & DSi and Si isotopes in ~20 Indian estuaries. We categorize the estuaries using statistical analysis (PCA and cluster analysis). Diatom uptake seems to be the main process controlling ASi during dry period, especially in the South. Weathering and erosion control the variability of LSi in the remaining estuaries. Similarly lithogenic supply controls Si during wet period in all estuaries and no impact of diatoms was seen because of high suspended load. Si isotopic compositions trace the Si sources and biogeochemical pathways. The isotopic results exhibit clear seasonal difference with high impact of type of weathering during both seasons. They show that southwest watersheds are very special in terms of weathering regime compared to the other watersheds because of topography and climate. The impact of agriculture and forest cover on Si cycle is also clearly evidenced in all the basins during wet period. We show that groundwater Si isotopic variability results from a combination of dissolution and production of minerals. Overall, this study shows the preponderant influence of weathering and type of secondary clays on Si isotopes irrespective to the seasons, rather than the biological uptake or mixing as reported elsewhere.