日本語

Lake Kasumigaura is the second largest lake in Japan, located about 60km to the northeast of Tokyo. Owing to the shallow water depth and location on a flat plain, it has a high diversity of organisms, while at the same time being subject to a variety of influences of anthropogenic origin.

Lake Kasumigaura was originally a brackish lake, partially connected to the Pacific Ocean. However, it has undergone drastic changes in the past 50 years, mostly owing to its role as a water source for the Tokyo metropolitan area. It became a freshwater lake after the downstream gates were closed in 1975. In addition, dikes encompassing the lake shoreline had been constructed during the period from 1971 to 1995 –after which the water level had been raised by 30cm.

Research teams from NIES have been collecting data on the water quality on a monthly basis over a period exceeding 30 years. This data includes information on physical/chemical properties of lake water and sediment, as well as on amounts of bacterioplankton; phytoplankton (including picophytoplankton); zooplankton (including protozoa and mysids); and benthos (chironomids and oligochaetes). The monitoring data is used to evaluate the effects of anthropogenic disturbance on the lake ecosystem.

Lake Mashu is a caldera lake located in eastern Hokkaido. It is the least polluted lake in Japan owing to the location of both the lake itself and its catchment area in a section of the protective zone of the Akan National Park - an area into which unauthorized entry is prohibited. In addition, there are no rivers flowing into or out of the Lake. As a consequence of these factors, the cumulative dose of chemical substances in the water, sediment, and the organisms in the Lake could be considered as the standard reference data of the freshwater areas.　

Our research team monitors the qualities of water and sediments as well as quantities of aquatic organisms, and analyzes the cycle of chemical substances in the lake ecosystem.

Lake Monitoring Team of 2011:

TAKAMURA N., UENO R., MATSUZAKI S.S. , NAKAGAWA M., OIKAWA Y. (Center for Environmental Biology and Ecosystem Studies)
IMAI A., TOMIOKA N., IWASAKI K., KOMATSU K., KOHZU A., SHINOHARA R. (Center for Regional Environmental Research)
TANAKA A., TAKEUCHI A., NISHIKAWA M. (Center for Environmental Measurement and Analysis)

The National Institute for Environmental Studies has also been Japan’s National Focal Point of GEMS/Water, a program which develops and maintains a systemized global informational database on freshwater quality. The Focal Point Office is currently located in CEBES, and data from 25 stations across the country are collated and disseminated to the global water quality database, GEMStat. The Focal Point Office is also the contact point for those with an interest in using GEMStat data in Japan.

The location map of the monitoring stations.

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