We observed drag coefficients and intensity of turbulence over sea ice field, and estimated sensible and latent heat transfer processes between frozen sea and atmosphere in the Chukchi Sea. which is one of the marginal seas of the Arctic Ocean, under cooling season. The drag coefficient is (1.7—8.9) x 10^-3 and its value is larger than that of several previous studies. On the other hand, the intensity of turbulence is lower than that of the wind-driven sea. and is influenced by the inhomogeneous surface roughness of sea ice and the fresh snow over sea ice. Both sensible and latent heat fluxes show upward large values, that is. 45 ～114 W/m^2 and 20～48 W/m^2. respectively. The effect of open water largely caused to upward heat transfers and local instability of atmosphere. Therefore, present observational data suggest that we have to consider the effect of inhomogeneous roughness of sea ice. fresh snow over sea ice and open water as sensitive subjects of air-sea interaction in the marginal ice zone under cooling season.
Field experiments were carried out to remediate organically enriched sediments. The sediments were collected from the ship fairway to Amagasaki Port and mixed with ion slag and then placed into hydrated iron slag concrete boxes. The experimental setups were placed in shallow seashore in Amagasaki Port. Sediment pH was increased, and oxidation-reduction potential was also increased by mixing of the slag compared to those at the original site. The concentration of acid-volatile sulfide was significantly decreased by these treatments. Biomass of benthic animals was increased significantly, which was high compared to those in an artificial tidal flat constructed ca. 4 years before our experiments near the experimental site. An acceleration of phosphorus cycle in the sediments was suggested as a cause of remediation by the calculation using a benthic ecosystem model. However, which the transfer sediment to the shallow area and the addition of slag is effective on the remediation was not clear in the present experimental settings.
An ecological risk assessment of lead (Pb). copper (Cu) and silver (Ag) in Tokyo Bay in 2005 was conducted using the
numerical model (AIST-RAMTB). The EC50, value (growth inhibition), or LC50. for each of these metals found in the giant Pacific oyster (Crassostrea gigas) in Tokyo Bay were selected as the assessment endpoints. The risk assessment was conducted using the Margin of Exposure (MOE) method with an uncertainty factor (UF) value of 20. The estimated maximum risk values were all less than 1 in the entire bay: 0.03 for Pb. 0.6 for Cu. and 0.018 for Ag. These results indicate that these heavy metals posed no risk to the giant Pacific oyster in Tokyo Bay in 2005.
We studied ecological risk assessment in Tokyo Bay. DecaBDE environmental concentration analyzed by AIST - RAMTB (AIST-The Risk Assessment Model forTokyo Bay). We set three resources (the atmosphere, major river and direct waste from sites) of DecaBDE loading fluxes. We targeted anevaluation object for diatoms, and endpoint was growth inhibition (EC50:1.0 mg • L^-1 ).
Uncertainty factor (UF) defined 10. The result wasshown that there was no risk of DecaBDE in diatoms of Tokyo Bay.
The DONET (Dense Ocean-floor Network system for Earthquakes and Tsunamis) is a submarine cabled real-time seafloor observation infrastructure which is designed to realize the precise monitoring of earthquakes and tsunamis on seafloor for long period. The observation target of DONET is Nankai trough where the one of the highest concern region of mega-thrust earthquake outbreak at this moment. The development of subsea system was started in 2006 and successfully deployed twenty set of state-of-arts observatories in 2011. An unprecedented revolutionary subsea construction technologies using ROV (Remotely Operated Vehicle) was established as a part of DONET project and carried out to make this complex observation system come true. This paper summarized the designing approach and key components of submarine cabled seafloor network system, construction method and engineering tools for ROV operation, and evaluation of the performance of observatory and network refers to some observation results.
The concept of underwater gliders for ocean observation was suggested by Dr. Henry Stommel in 1989. and development was started in the world. In the beginning of this paper, the history of the development of underwater gliders and the outline of the vehicles are described. Next, the underwater gliders for virtual mooring which Kyusyu University and Japan Agency for Marine- Earth Science and Technology (hereafter. ”JAMSTEC”) are building are reported.
Recently, the satellite communication system has been become downsizing, weight saving in the field of ocean observation. The rapid advance and diffusion of satellite communication technology has resulted in changing the needs of ocean observation system user. This paper introduces the satellite communication system, which many users want to utilize.
A profiling float has been used widely for ocean observation recent years, especially since an international program. Argo. was launched to monitor the global ocean. More than 3000 floats are now operating in the global ocean and most of them are under the Argo: thus, a profiling float is very often called an ”Argo float” confusedly. The profiling float is. in brief, a device to move sensors on it vertically from depths to sea surface and to transmit data to stations on land. The profiling float was assembled from different technologies and they have been improved continuously until now. The success of Argo clarified the usefulness of observing network by numerous floats. Thus, various types of profiling floats are now required for the observations in coastal/shallow regions, under sea ice. and in deep oceans. Recent developments of sensor technology also resulted (will result) in reducing sensor size and measuring new marine parameters. Some of them are already available for floats. The profiling floats will be used in wider scenes of ocean observations near future.