Ola M. Johannessen

Brief Overview of the Physical Oceanography

In the Nordic Seas have been the sites of many oceanographic stations over the years. Figure 1 shows as an example the sites of most of the Nansen casts up to 1975 for September (summer conditions) and January (winter conditions). No overview yet exists for the STD and CTD casts. (The abbreviation STD is used both for an older, analog instrument and for the salinity, temperature, and depth it measures. The abbreviation CTD is used for a newer, digital instrument and for conductivity, temperature, and depth. Both instruments actually report not depth but pressure.) In addition to data from the Nansen casts several ten thousands of bathythermograph (BT) data, expendablebathythermograph (XBT) data, and aircraftexpendable-bathythermograph (AXBT) data have been obtained; however, these observations give only the temperature profiles to several hundred meters.

ICE EDDY AMBIENT NOISE

Mechanisms affecting ice floe interactions in the marginal ice zone (MIZ) are discussed. These mechanisms are assumed to be the major forcing functions driving the ambient noise levels in the MIZ. Results from previous studies are briefly summarized with hypotheses presented concerning the effect of ice eddies and grease ice on ambient noise. Data are presented from an experiment held in winter 1985, in which sonobuoys were planted in the water just off the compact ice-edge and in the adjacent ice-field containing two eddies. The ambient noise levels are found to be relatively high, with a significant variability over the sampled region. A broad noise peak across the eddy/ice-edge region suggests the eddy as a distributed ambient noise source.

Interaction with the Global Climate System

The Arctic is part of the global climate system. To address the issue of climate, the fluxes of heat, salt, and fresh water must be considered. One of the most speculated reasons for rapid climate change in the subarctic North Atlantic, and the global conveyor belt, is a breakdown of the thermohaline circulation (THC) due to an increased fresh water supply. Whitehead’s (Estuaries 21:281–293, 1998) one-box dynamic model is used to show how multiple states and catastrophe can occur in the Arctic Mediterranean with variable freshening and cooling. The broader question is how this interacts with the global climate. In this chapter, we focus on the oceanic aspects of the arctic climate system, discuss processes, review the data, and speculate on the role this part of the globe has in the greater context of global climate. The interaction with the global system comprises the outflow of freshwater and ice, and deeper, freshened, and cooled seawater into the subarctic North Atlantic, via the Labrador Sea. An example of significant climate variability in the twentieth century is presented.

Assessment and input to risk management

This chapter presents an assessment of the risk of radiological impact on humans as a consequence of the potential release of radioactive material. Although it is clearly beyond the scope of this chapter to provide a comprehensive risk assessment of all potential environmental and human impacts from all scenarios of radioactive releases in Arctic marine and terrestrial realms, we are able to focus on one major set of risks. These are risks to humans associated with potential releases along the major Siberian rivers—the Ob′ and Yenesei—including an assessment of how global warming may affect the consequences. Section 6.1 is an introduction to the assessment, while various scenarios are described in Section 6.2. Section 6.3 describes how dose models are formulated and implemented. The results of risk assessment modeling are provided in Section 6.4. Section 6.5 presents a summary and major conclusions.

Generic model system (GMS) for simulation of radioactive spread in the aquatic environment

This chapter presents a set of numerical modeling techniques for simulating the spread of radioactivity in the aquatic environment, in both marine and inland waters. Section 3.1 describes the concept and structure of the modeling system. Section 3.2 presents a model for the Atlantic and Arctic Oceans. Section 3.3 presents a shelf sea model for the Kara Sea. Section 3.4 describes in detail the river and estuary models for the Ob′ and Yenisei Rivers. These comprise a one-dimensional model for simulation of the transport of radionuclides in a river system (RIVTOX), and a numerical model for three-dimensional dispersion simulation of radionuclides in stratified water bodies (THREETOX). For each model, we present results from validation of the models against comparable measurement data and knowledge based on observations.

Studies of potential radioactive spread in the Nordic Seas and Arctic using the generic model system (GMS)

This chapter is dedicated to study of the spread of radioactivity in the Arctic using the generic model system (GMS) described in Chapter 3. Two sets of numerical experiments were carried out: (1) simulations or “hindcasts” of past contamination by anthropogenic radionuclides, originating from nuclear bomb testing, atmospheric fallout from Chernobyl, discharges from the Sellafield Reprocessing Plant, and radionuclide transport by river from nuclear plants; (2) simulations of contamination as a result of potential accidents in nuclear plants and submarines.

Sources of anthropogenic pollution in the Nordic Seas and Arctic

This chapter describes the sources of radioactive and non-radioactive contamination in the Arctic and Nordic Seas. The primary and secondary sources of radioactivity in the study region are enumerated and described in Section 1.1. Section 1.2 focuses on a detailed description of three major Russian nuclear industries: (1) the Mayak Production Association, Chelyabinsk; (2) the Siberian Chemical Combine, Tomsk-7; and (3) the Mining and Chemical Combine, Krasnoyarsk-26. Section 1.3 provides a substantial description of non-radioactive pollution, including its sources and spread in the marine environment of the Barents, White, Kara, and Laptev Seas. The descriptions given here have been prepared from information from a range of open-literature material, including a wealth of Russian material and more widely known publications; for example, Arctic Monitoring and Assessment Program (AMAP) reports. An effort has been made to provide the most recent information, although the ever-changing status of pollution sources challenges an evaluation of the present situation.

Study region and environmental datasets

This chapter describes the geography of the study region and the observational environmental data used in these analyses. The geographical and oceanographic features of the study region are described in Section 2.1, which is organized in three sub-sections: the Ob′ and Yenisei River systems, the Kara Sea region, and the Nordic Seas and adjacent seas. Section 2.2 presents an overview of the environmental data that are used in this study, organized in three sub-sections: databases and the information system, natural environmental data (e.g., hydrological, oceanographic, and geophysical), and pollution data.

Studies of the spread of non-radioactive pollutants in the Arctic using the generic model system (GMS)

The Arctic Ocean is threatened with contamination not only from the spread of radionuclides (Chapters 1, 3, and 4) but also by other toxic pollutants—for example, persistent organic pollutants (POPs), petroleum hydrocarbons, and heavy metals (AMAP, 2004, 2009)—see also the latter sections in Chapter 1. Although the levels of many POPs have recently declined in the Arctic environment (AMAP, 2009), “legacy” POPs contaminate the Arctic largely as a result of past use and emissions, and emerging and current-use POPs have the potential to transport to and accumulate in the Arctic. Significant increases in oil exploration on Arctic shelf seas and its transportation are foreseen for the near future (AMAP, 2007). These activities will lead to increased risks of oil contamination of the cold Arctic environment, including ice-covered waters.

Evaluation of Nimbus 7 SMMR sensor with airborne radiometers and surface observations in the Norwegian Sea

A comparison of Nimbus 7 SMMR measurements with near simultaneous observations using the airborne SMMR simulator and with surface observations was carried out in the Norwegian Sea in November 1978. The results indicate the need for further work on algorithms and calibration for both radiometric instruments.