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.

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.

Our desire to understand the global carbon cycle and its link to the climate system represents a huge challenge. These overarching questions have driven a great deal of scientific endeavour in recent years: What are the basic oceanic mechanisms which control the oceanic carbon reservoirs and the partitioning of carbon between ocean and atmosphere? How do these mechanisms depend on the state of the climate system and how does the carbon cycle feed back on climate? What is the current rate at which fossil fuel carbon dioxide is absorbed by the oceans and how might this change in the future? To begin to answer these questions we must first understand the distribution of carbon in the ocean, its partitioning between different ocean reservoirs (the "solubility" and "biological" pumps of carbon), the mechanisms controlling these reservoirs, and the relationship of the significant physical and biological processes to the physical environment. The recent surveys from the JGOFS and WOCE (Joint Global Ocean Flux Study and World Ocean Circulation Ex periment) programs have given us a first truly global survey of the physical and biogeochemical properties of the ocean. These new, high quality data provide the opportunity to better quantify the present oceans reservoirs of carbon and the changes due to fossil fuel burning. In addition, diverse process studies and time-series observations have clearly revealed the complexity of interactions between nutrient cycles, ecosystems, the carbon-cycle and the physical envi ronment.

Within the joint German-Russian research project Siberian River Run-off (SIRRO) multidisciplinary studies were carried out in the Ob and Yenisei estuaries and adjacent southern Kara Sea (Arctic Ocean). The overall goal of the project was to extend knowledge on understanding the freshwater and sediment input by the major Siberian rivers, and its impact on the environments of the inner Kara Sea. The main results of oceanographical, biological, geochemical, geological and modelling studies are presented in four main chapters.

This book discusses the water and carbon cycle system in the permafrost region of eastern Siberia, Providing vitalin sights into how climate change has affected the permafrost environment in recent decades. It analyzes the relationships between precipitation and evapotranspiration, gross primary production and runoff in the permafrost regions, which differ from those intropical and temperate forests. Eastern Siberia is located in the easternmost part of the Eurasian continent, and the land surface with underlying permafrost has developed over a period of seventy thousand years. The permafrost ecosystem has specific hydrological and meteorological characteristics in terms of the water and carbon dynamics, and the current global warming and resulting changes in the permafrost environment are serious issues in the high-latitude regions. The book is a valuable resource for students, researchers and professionals interested in forest meteorology and hydrology, forest ecology, and boreal vegetation, as well as the impact of climate change and water-carbon cycles in permafrost and non-permafrost regions.