HR: 15:05h
AN: OS33C-05    [Abstracts]
TI: Monitoring of Water Quality by Satellite Imagery and In-Situ Sediments Componentsf at the Ishikari Bay, Hokkaido, Japan
AU: * Fukuyama, R
EM: fukuyama@hokkaido-ies.go.jp
AU: Saitoh, S
EM: ssaitoh@salmon.fish.hokudai.ac.jp
AU: Hamahara, K
EM: kazuh@hokkaido-ies.go.jp
AU: Tanaka, T
EM: t.tanaka@hokkaido-ies.go.jp
class='hr'> AB: To monitor the water quality of the Ishikari Bay, we studied the diffusion pattern of the fresh water from the Ishikari River using satellite-derived imagery and, verified the water pollution change from the fluctuation of sedimentsf components during the period 1999-2001. All along winter season, icebergs and rough weather prevent us from monitoring the water quality around Hokkaido coastal sea areas. A practical way to conduct the monitoring of this coastal water quality is to use sophisticated remote-sensing techniques. But there are many controversial issues to be solved before using these techniques. Especially the sensor, detecting primary production as chlorophyll sometimes mistakes suspended substance for chlorophyll in the vicinity of river mouth. Because of these problems, there is a need for a new algorithm to make proper interpretations at coastal waters. For this purpose, and to get reasonable information from the high-resolution satellite imagery, the sea-truth data representing chemical species and, their relation with satellite-derived imagery was first of all investigated. The field of study was the Ishikari Bay. At this field, a blooming phytoplankton covering a wide area of the bay was observed when a large quantity of fresh water involved a lot of nutrients discharged from the Ishikari River during a heavy rain event as 100mm of precipitation. The migration of this blooming around the Ishikari Bay was observed in time series till the Okhotsk Sea, by satellite. The results indicate the possibility of the transport of pollutants such as chemical compounds from the Ishikari River basin to the Okhotsk Sea through the medium of plankton. The relationship between satellite-derived imagery (SeaWifs) and chemical species (taken as the sea-truth) was investigated on suspended solids, chlorophyll-a, salinity and water temperature. There is a good relationship between suspended solids and the satellite-derived imagery. The relationship between chlorophyll-a and the satellite- derived imagery was not as obvious, with sometimes the presence of water plumes. Nevertheless, satellite imagery was useful to monitor the influence of fresh water. Furthermore, we investigated the components of sediments sampled in the vicinity of the Ishikari river mouth. The fluctuation of the sedimentsf components around 70 years was observed in organic carbon, Cr, Pb and Cu using the Pb and Cs dating methods. The result indicated that the high concentration (more than 1%) of organic carbon changed during the period of high economic growth, and sometimes there were discharges of high Cr concentration from the abolition mine. And, from the result of fluctuation of the diatom frustules in the sediment, the river and the coastal water had a high primary productivity during the period of the high economic growth. This agrees with the result of the above- mentioned fluctuation of organic matter.
DE: 3050 Ocean observatories and experiments
DE: 4217 Coastal processes
DE: 4251 Marine pollution (0345, 0478)
DE: 4275 Remote sensing and electromagnetic processes (0689, 2487, 3285, 4455, 6934)
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly